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Which is the protein encoded by the human gene GRIK? | Glutamate Receptor Ionotropic Kainate | Functional impairment of the orbital and medial prefrontal cortex underlies
deficits in executive control that characterize addictive disorders, including
alcohol addiction. Previous studies indicate that alcohol alters glutamate
neurotransmission and one substrate of these effects may be through the
reconfiguration of the subunits constituting ionotropic glutamate receptor
(iGluR) complexes. Glutamatergic transmission is integral to cortico-cortical
and cortico-subcortical communication and alcohol-induced changes in the
abundance of the receptor subunits and/or their splice variants may result in
critical functional impairments of prefrontal cortex in alcohol dependence. To
this end, the effects of chronic ethanol self-administration on glutamate
receptor ionotropic AMPA (GRIA) subunit variant and kainate (GRIK) subunit mRNA
expression were studied in the orbitofrontal cortex (OFC), dorsolateral
prefrontal cortex (DLPFC), and anterior cingulate cortex (ACC) of male
cynomolgus monkeys. In DLPFC, total AMPA splice variant expression and total
kainate receptor subunit expression were significantly decreased in alcohol
drinking monkeys. Expression levels of GRIA3 flip and flop and GRIA4 flop mRNAs
in this region were positively correlated with daily ethanol intake and blood
ethanol concentrations (BEC) averaged over the 6 months prior to necropsy. In
OFC, AMPA subunit splice variant expression was reduced in the alcohol treated
group. GRIA2 flop mRNA levels in this region were positively correlated with
daily ethanol intake and BEC averaged over the 6 months prior to necropsy.
Results from these studies provide further evidence of transcriptional
regulation of iGluR subunits in the primate brain following chronic alcohol
self-administration. Additional studies examining the cellular localization of
such effects in the framework of primate prefrontal cortical circuitry are
warranted. A growing body of evidence suggests an association between
microdeletion/microduplication and schizophrenia/intellectual disability.
Abnormal neurogenesis and neurotransmission have been implicated in the
pathogenesis of these neuropsychiatric and neurodevelopmental disorders. The
kainate/AMPA-type ionotropic glutamate receptor (GRIK = glutamate receptor,
ionotropic, kainate) plays a critical role in synaptic potentiation, which is an
essential process for learning and memory. Among the five known GRIK family
members, haploinsufficiency of GRIK1, GRIK2, and GRIK4 are known to cause
developmental delay, whereas the roles of GRIK3 and GRIK5 remain unknown.
Herein, we report on a girl who presented with a severe developmental delay
predomitly affecting her language and fine motor skills. She had a 2.6-Mb
microdeletion in 1p34.3 involving GRIK3, which encodes a principal subunit of
the kainate-type ionotropic glutamate receptor. Given its strong expression
pattern in the central nervous system and the biological function of GRIK3 in
presynaptic neurotransmission, the haploinsufficiency of GRIK3 is likely to be
responsible for the severe developmental delay in the proposita. A review of
genetic alterations and the phenotypic effects of all the GRIK family members
support this hypothesis. The current observation of a microdeletion involving
GRIK3, a kainate-type ionotropic glutamate receptor subunit, and the
neurodevelopmental manifestation in the absence of major dysmorphism provides
further clinical implication of the possible role of GRIK family glutamate
receptors in the pathogenesis of developmental delay. |
Which residue of alpha-synuclein was found to be phosphorylated in Lewy bodies? | Alpha-synuclein phosphorylated at serine 129 (S129) is highly elevated in Parkinson's disease patients where it mainly accumulates in the Lewy bodiesApproximately 90% of α-syn deposited in Lewy bodies is phosphorylated at serine 129 (Ser129). In contrast, only 4% or less of total α-syn is phosphorylated at this residue in the normal brain. This suggests that the accumulation of Ser129-phosphorylated α-syn leads to the formation of Lewy bodies and dopaminergic neurodegeneration in Parkinson's disease | The deposition of the abundant presynaptic brain protein alpha-synuclein as
fibrillary aggregates in neurons or glial cells is a hallmark lesion in a subset
of neurodegenerative disorders. These disorders include Parkinson's disease
(PD), dementia with Lewy bodies (DLB) and multiple system atrophy, collectively
referred to as synucleinopathies. Importantly, the identification of missense
mutations in the alpha-synuclein gene in some pedigrees of familial PD has
strongly implicated alpha-synuclein in the pathogenesis of PD and other
synucleinopathies. However, specific post-translational modifications that
underlie the aggregation of alpha-synuclein in affected brains have not, as yet,
been identified. Here, we show by mass spectrometry analysis and studies with an
antibody that specifically recognizes phospho-Ser 129 of alpha-synuclein, that
this residue is selectively and extensively phosphorylated in synucleinopathy
lesions. Furthermore, phosphorylation of alpha-synuclein at Ser 129 promoted
fibril formation in vitro. These results highlight the importance of
phosphorylation of filamentous proteins in the pathogenesis of neurodegenerative
disorders. A comprehensive, unbiased inventory of synuclein forms present in Lewy bodies
from patients with dementia with Lewy bodies was carried out using
two-dimensional immunoblot analysis, novel sandwich enzyme-linked immunosorbent
assays with modification-specific synuclein antibodies, and mass spectroscopy.
The predomit modification of alpha-synuclein in Lewy bodies is a single
phosphorylation at Ser-129. In addition, there is a set of characteristic
modifications that are present to a lesser extent, including ubiquitination at
Lys residues 12, 21, and 23 and specific truncations at Asp-115, Asp-119,
Asn-122, Tyr-133, and Asp-135. No other modifications are detectable by tandem
mass spectrometry mapping, except for a ubiquitous N-terminal acetylation. Small
amounts of Ser-129 phosphorylated and Asp-119-truncated alpha-synuclein are
present in the soluble fraction of both normal and disease brains, suggesting
that these Lewy body-associated forms are produced during normal metabolism of
alpha-synuclein. In contrast, ubiquitination is only detected in Lewy bodies and
is primarily present on phosphorylated synuclein; it therefore likely occurs
after phosphorylated synuclein has deposited into Lewy bodies. This invariant
pattern of specific phosphorylation, truncation, and ubiquitination is also
present in the detergent-insoluble fraction of brain from patients with familial
Parkinson's disease (synuclein A53T mutation) as well as multiple system
atrophy, suggesting a common pathogenic pathway for both genetic and sporadic
Lewy body diseases. These observations are most consistent with a model in which
preferential accumulation of normally produced Ser-129 phosphorylated
alpha-synuclein is the key event responsible for the formation of Lewy bodies in
various Lewy body diseases. alpha-Synuclein is a major protein component deposited in Lewy bodies and Lewy
neurites that is extensively phosphorylated at Ser(129), although its role in
neuronal degeneration is still elusive. In this study, several apoptotic
pathways were examined in alpha-synuclein-overexpressing SH-SY5Y cells.
Following the treatment with rotenone, a mitochondrial complex I inhibitor, wild
type alpha-synuclein-overexpressing cells demonstrated intracellular
aggregations, which shared a number of features with Lewy bodies, although cells
overexpressing the S129A mutant, in which phosphorylation at Ser(129) was
blocked, showed few aggregations. In wild typealpha-synuclein cells treated with
rotenone, the proportion of phosphorylated alpha-synuclein was about 1.6 times
higher than that of untreated cells. Moreover, induction of unfolded protein
response (UPR) markers was evident several hours before the induction of
mitochondrial disruption and caspase-3 activation. Eukaryotic initiation factor
2alpha, a member of the PERK pathway family, was remarkably activated at early
phases. On the other hand, the S129A mutant failed to activate UPR. Casein
kinase 2 inhibitor, which decreased alpha-synuclein phosphorylation, also
reduced UPR activation. The alpha-synuclein aggregations were colocalized with a
marker for the endoplasmic reticulum-Golgi intermediate compartment. Taken
together, it seems plausible that alpha-synuclein toxicity is dependent on the
phosphorylation at Ser(129) that induces the UPRs, possibly triggered by the
disturbed endoplasmic reticulum-Golgi trafficking. α-Synuclein is causative for autosomal domit familial Parkinson disease and
dementia with Lewy bodies, and the phosphorylation of α-synuclein at residue
Ser-129 is a key posttranslational modification detected in Parkinson
disease/dementia with Lewy bodies lesions. However, the role of Ser-129
phosphorylation on the pathogenesis of Parkinson disease/dementia with Lewy
bodies remains unclear. Here we investigated the neurotoxicity of
Ser-129-substituted α-synuclein in the transgenic Caenorhabditis elegans (Tg
worm) model of synucleinopathy. Tg worms pan-neuronally overexpressing
nonphosphorylatable (S129A) α-synuclein showed severe defects including motor
dysfunction, growth retardation, and synaptic abnormalities. In contrast, Tg
worms expressing phosphorylation mimic (S129D) α-synuclein exhibited nearly
normal phenotypes. Biochemical fractionation revealed that the level of
membrane-bound α-synuclein was significantly increased in S129A-α-synuclein Tg
worms, whereas S129D- as well as A30P-α-synuclein displayed lower membrane
binding properties. Furthermore, A30P/S129A double mutant α-synuclein did not
cause neuronal dysfunction and displayed low membrane binding property. In human
neuroblastoma SH-SY5Y cells, localization of S129A-α-synuclein to membranes was
significantly increased. Finally, gene expression profiling of S129A-Tg worms
revealed a dramatic up-regulation of Daf-16/FOXO pathway genes, which likely act
against the dysfunction caused by S129A-α-synuclein. These results imply a role
of Ser-129 phosphorylation of α-synuclein in the attenuation of
α-synuclein-induced neuronal dysfunction and downstream stress response by
lowering the membrane binding property. |
Is paroxetine effective for treatment of premenstrual dysphoric disorder? | Yes, paroxetine is effective and FDA approved treatment of women with premenstrual dysphoric disorder. A number of well designed clinical trials have confirmed efficacy and safety of both continuous or intermittent regiments of paroxetine for treatment of premenstrual dysphoric disorder. A number of other antidepressants and hormaonal therapies were also shown to be effective and are FDA approved for treatment of women with premenstrual dysphoric disorder. | Research into the psychobiology of premenstrual dysphoric disorder (PDD) finds
alterations in markers associated with serotonergic neurotransmission.
Supporting this is work showing that patients with PDD respond to some agents
that block the reuptake of serotonin. In this open trial, patients were treated
for one cycle with placebo and then for three consecutive cycles with the
serotonin reuptake inhibitor paroxetine. The study population was composed of 14
participants who met DSM-IV criteria for PDD with moderate to severe
symptomatology and specifically endorsed anger and irritability as a central
premenstrual complaint. Patients showed modest improvement over the course of
the pretreatment evaluation, with significant improvement occurring for feelings
of worthlessness, decreased interest, and low energy. The effects of active
treatment were marked by the first active cycle with luteal phase 17-item
Hamilton Rating Scale for Depression scores decreasing from 14.9 (+/- 5.3) to
8.2 (+/- 4.9) in the first, 7.8 (+/- 5.1) in the second, and 7.8 (+/- 6.8) in
the third active treatment cycles (F[1,13] = 17.6; p < 0.0001). A group of items
from daily ratings indicative of anger and irritability (mood swings, anger and
irritability, behavioral dyscontrol, and interpersonal conflicts) also showed
improvement (F[1,13] = 5.94; p < 0.03). Various definitions of response were
applied to treatment completers. The most conservative measure, the Clinical
Global Impression (CGI), revealed that 7 of 14 patients had a complete response
(CGI = 1 or 2) whereas 4 patients had a partial response (CGI = 3). These open
trial findings are consistent with the notion that paroxetine is effective in
the acute phase for the treatment of PDD. Eighteen women with severe premenstrual syndrome (PMS) (premenstrual dysphoric
disorder, PMDD) were treated openly with paroxetine for 10 consecutive menstrual
cycles. Dosage was flexible (5-30 mg/day); also, the patients were free to chose
between continuous medication and medication in the luteal phase only. The
rating of premenstrual irritability, depressed mood, increase in appetite, and
anxiety/tension was markedly lower during treatment with paroxetine than before,
and this reduction in symptomatology appeared unabated for the entire treatment
period. Sedation, dry mouth, and nausea were common side-effects but declined
during the course of the trial; in contrast, reduced libido and anorgasmia,
which were reported by almost 50% of the participants, were not improved with
time. The results indicate that the beneficial effects as well as the sexual
side-effects of serotonin reuptake inhibitors persist unchanged for at least 10
consecutive cycles of treatment. Paroxetine is a potent and selective inhibitor of the neuronal reuptake of
serotonin (5-hydroxytryptamine; 5-HT), which was previously reviewed as an
antidepressant in Drugs in 1991. Since then, more comparative trials with other
antidepressants have become available, and its use in the elderly and as long
term maintece therapy has been investigated. Paroxetine has also been studied
in several other disorders with a presumed serotonergic component, primarily
obsessive compulsive disorder (OCD) and panic disorder. In short term clinical
trials in patients with depression, paroxetine produced clinical improvements
that were significantly greater than those with placebo and similar to those
achieved with other agents including tricyclic antidepressants (TCAs),
maprotiline, nefazodone and the selective serotonin reuptake inhibitors (SSRIs)
fluoxetine, fluvoxamine and sertraline. Long term data suggest that paroxetine
is effective in preventing relapse or recurrence of depression in patients
treated for up to 1 year. In the elderly, the overall efficacy of paroxetine was
at least as good as that of comparator agents. In short term clinical trials
involving patients with OCD or panic disorder, paroxetine was significantly more
effective than placebo and of similar efficacy to clomipramine. Limited long
term data show that paroxetine is effective in maintaining a therapeutic
response over periods of 1 year (OCD) and up to 6 months (panic disorder).
Preliminary data suggest that paroxetine has potential in the treatment of
social phobia, premenstrual dysphoric disorder and chronic headache. Like the
other SSRIs, paroxetine is better tolerated than the TCAs, causing few
anticholinergic adverse effects. The most commonly reported adverse event
associated with paroxetine treatment is nausea, although this is generally mild
and subsides with continued use. Fewer withdrawals from treatment due to adverse
effects occurred with paroxetine treatment than with TCAs. The adverse events
profile of paroxetine appears to be broadly similar to that of other SSRIs,
although data from comparative trials are limited. Serious adverse effects
associated with paroxetine are very rare. In conclusion, paroxetine is effective
and well tolerated, and suitable as first-line therapy for depression. It also
appears to be a useful alternative to other available agents for the treatment
of patients with OCD or panic disorder. Changes in serotonergic parameters have been reported in psychiatric conditions
such as depression but also in the premenstrual dysphoric disorder (PMDD). In
addition, hormonal effects on serotonergic activity have been established. In
the present study, binding of [3H]paroxetine to platelet serotonin uptake sites
and binding of [3H]lysergic acid diethylamide ([3H]LSD) to platelet serotonin
(5-HT)2A receptors were studied in patients with PMDD treated with a low dose of
a gonadotropin releasing hormone (GnRH) agonist (buserelin) or placebo and
compared to controls. The PMDD patients were relieved of premenstrual symptoms
like depression and irritability during buserelin treatment. The number of
[3H]paroxetine binding sites (Bmax) were significantly higher in the follicular
phase in untreated PMDD patients compared to controls. When treated with
buserelin the difference disappeared. No differences in [3H]LSD binding between
the three groups were shown. The present study demonstrated altered platelet
[3H]paroxetine binding characteristics in women with PMDD compared to controls.
Furthermore, [3H]paroxetine binding was affected by PMDD treatment with a low
dose of buserelin. The results are consistent with the hypothesis that changes
in serotonergic transmission could be a trait in the premenstrual dysphoric
disorder. Paroxetine is a potent and selective serotonin reuptake inhibitor (SSRI) with
currently approved indications for the treatment of depression,
obsessive-compulsive disorder, panic disorder and social phobia. It is also used
in the treatment of generalized anxiety disorder, post traumatic stress
disorder, premenstrual dysphoric disorder and chronic headache. Paroxetine, a
phenylpiperidine derivative, is the most potent inhibitor of the reuptake of
serotonin (5-hydroxytryptamine, 5-HT) of all the currently available
antidepressants including the class of SSRIs. It is a very weak inhibitor of
norepinephrine (NE) uptake but it is still more potent at this site than the
other SSRIs. The selectivity of paroxetine, i.e., the ratio of inhibition of
uptake of norepinephrine to serotonin (NE/5-HT) is amongst the highest of the
SSRIs. Paroxetine has little affinity for catecholaminergic, dopaminergic or
histaminergic systems and by comparison with tricyclic antidepressants (TCAs)
has, therefore, a reduced propensity to cause central and autonomic side
effects. Paroxetine exhibits some affinity for the muscarinic cholinergic
receptor but much less than the TCAs. In addition, the adaptive changes of
somatodendritic (5-HT(1A)) and terminal (5-HT(1B/1D)) autoreceptors observed
with paroxetine are different to those observed with TCAs; it also inhibits
nitric oxide synthase. It is both a substrate and an inhibitor of cytochrome
isoenzyme P450 2D6. Paroxetine is well absorbed orally and undergoes extensive
first pass metabolism that is partially saturable. Its metabolites are
pharmacologically inactive in vivo. Steady state levels are achieved after 4-14
days and an elimination half-life of 21 h is consistent with once-daily dosing.
There is wide inter-individual variation in the pharmacokinetics of paroxetine
in adults as well as in the young and the elderly with higher plasma
concentrations and slower elimination noted in the latter. Elimination is also
reduced in severe renal and hepatic impairment. Serious adverse events are,
however, extremely rare even in overdose. In summary, paroxetine is well
tolerated and effective in the treatment of both depressive and anxiety
disorders across the age range. Numerous, but heterogeneous studies have been performed about premenstrual
syndrome, with finally a lack of credibility and interest among practitioners.
More recently with the diagnosis criteria generalization, psychiatrists were
more concerned about this syndrome, because of anxiety and mood symptoms
involved in social impairment and need of medical care. In 1983 in the United
States, the National Institute of Mental Health conference devoted to this topic
proposed the first diagnosis criteria, requiring a prospective and daily
assessment of the symptoms. In 1987, the American Psychiatric Association, in
the DSM III-R, introduced the Late Luteal Phase Dysphoric Disorder diagnosis
that became in 1994 in the DSM IV the Premenstrual Dysphoric Disorder, with the
same diagnosis criteria. In the literature, prevalence rates are very
heterogeneous according to the diagnosis criteria used and to the populations
studied. One of the most relevant criteria is the induced impairment, such as
avoidance of social activities, or search for medical care. Lifetime prevalence
is thus estimated between 75 and 85% if considering the report of one or several
symptoms, between 10 and 15% in case of medical care request, and between 2 and
5% in case of social activities interruption. To distinguish isolated complaints
from a disabling disorder, self-questionnaires are the best way of assessment in
a so complex and changing disease. Most of the epidemiological studies found a
positive correlation between the premenstrual dysphoric symptoms and the
lifetime major depressive disorder diagnosis. However, recent prospective
studies failed to find an association between premenstrual syndrome and an
increased risk of major depression. On the other hand, some studies showed that
the premenstrual period is a risk period for associated psychiatric disorders
exacerbations, as the obsessive-compulsive disorder, more severe alcohol intakes
in case of alcoholism, symptoms increase in schizophrenics, or higher rates of
suicide attempts. The most widely studied and frequently blamed etiopathogenic
hypothesis is the serotonin dysregulation. Serotonin is particularly involved in
expression of irritability and anger, but also in occurrence of depressive
symptoms and specific food cravings, precisely found in the premenstrual
dysphoric disorder. Among their different effects, estrogens increase the
density of serotonin receptors and enhance the sensitivity to serotonin
agonists. Moreover, some studies found a significantly different response to
d-fenfluramine, a serotonin agonist, in women with premenstrual dysphoric
disorder. In psychoanalytical theories the premenstrual syndrome was associated
to a "femininity complex", to an ambivalent pregcy desire, and to unconscious
conflicts relating to sexual preference. In this context, Karen Horney, who took
a great interest in the premenstrual period, was radically opposed to the
Freudian theory of feminine sexuality, in particular the negation of the female
sex. For Karen Homey, the "desire of penis" is more expressive of the woman's
spite not to share the sexual, but also political, social and cultural benefits
fallen to men. To understand the premenstrual period feelings it is also
necessary to take into account the personal history of the woman and the
psychosocial factors involved, as the social and cultural beliefs, and the
mother-daughter communication. Medical cares are necessary when symptoms
constitute a severe and disabling disorder. Among non-psychiatric treatments,
progesterone was the most widely prescribed treatment, but relating to recent
performed studies, it failed to prove its efficiency in such an indication. In
the same way, the efficiency of the contraceptive pill was not demonstrated. The
most prescribed psychiatric treatments are serotonin re-uptake inhibitors and
benzodiazepines. First studies showing serotonin re-uptake inhibitors efficiency
in premenstrual dysphoric disorder were performed in the beginning of the
nineties, with clomipramine and fluoxetine, and later fluvoxamine, paroxetine,
sertraline and citalopram. Studies having compared the efficiency of
antidepressants according to their serotonin activity (paroxetine or sertraline
versus maprotiline, that is a selective noradrenaline re-uptake inhibitor),
showed that serotonin re-uptake inhibitors were significantly more efficient on
all symptoms than maprotiline, that was not more efficient than placebo. Low
doses of clomipramine (10 to 50 mg per day) seem to be sufficient and it appears
also preferable to prescribe an intermittent treatment because of a possible
tolerance effect, susceptible to be warned by phases free of treatment.
Alprazolam was the most studied benzodiazepine in this indication. Most studies
were positive, using daily posologies of 0.25 to 4 mg during the 6 days
preceding the menses, with improvement of irritability, anxiety and depressive
mood. The general practitioner frequently carries out psychological support, in
particular in case of mild symptoms without consequences. Nevertheless,
underestimate a more severe psychological suffering is a risk, firstly because
there is no systematic interrelationship between the somatic symptoms intensity
and the psychological distress, and secondly because premenstrual period is a
special emotionally moment to put in evidence psychological or relational
disruption. All kinds of psychotherapy can be relevant, even though the training
of relaxation techniques is particularly suitable in such an indication. In
conclusion, and in spite of the generalization of the diagnosis criteria in the
international psychiatric classifications as the DSM, the premenstrual syndrome
remains a complex and polymorphous disorder. The premenstrual syndrome was
considered for a long time like a somatic disease, but now the psychiatric
symptoms severity justifies most often the medical cares. In order to
distinguish some isolated and mild complaints, of a disabling disorder, the
standardized prospective auto-assessment is the most relevant method. Finally,
intermittent prescription of serotonin re-uptake inhibitors appears to be the
most effective treatment, the previously used hormonal treatments not having
made proof of their efficiency in such an indication. There have been a large number of studies conducted investigating the use of
selective serotonin reuptake inhibitors (SSRIs) in the treatment of patients
with premenstrual dysphoric disorder (PMDD). The 12 randomised, controlled
trials with continuous dose administration of SSRIs and the eight randomised,
controlled trials with luteal phase dose administration (from ovulation to
menses) are reviewed. All the treatment studies on fluoxetine, sertraline,
paroxetine and citalopram have reported positive efficacy. Fluoxetine and
sertraline have the largest literature, with a smaller number of studies
endorsing paroxetine and citalopram. Mixed efficacy results have been reported
with fluvoxamine. In general, adverse effects from the use of SSRIs in women
with PMDD are the usual mild and transient adverse effects from SSRIs including
anxiety, dizziness, insomnia, sedation, nausea and headache. Sexual dysfunction
and weight gain can be problematic long-term adverse effects of SSRIs, but these
effects have not been systematically evaluated with long-term SSRI use in women
with PMDD. Serotonergic antidepressants have differential superiority over
nonserotonergic antidepressants in the treatment of PMDD. Treatments that
enhance serotonergic action improve premenstrual irritability and dysphoria with
a rapid onset of action, suggesting a different mechanism of action than in the
treatment of depression. It is possible that neurosteroids, such as progesterone
metabolites, are involved in the rapid action of serotonergic antidepressants in
PMDD. Future research needs to address less frequent dose administration
regimens, such as 'symptom-onset' dose administration, and the recommended
length of treatment. Paroxetine is a potent selective serotonin reuptake inhibitor (SSRI) with
indications for the treatment of depression, obsessive- compulsive disorder,
panic disorder and social phobia. It is also used in the treatment of
generalized anxiety disorder, post-traumatic stress disorder, premenstrual
dysphoric disorder and chronic headache. There is wide interindividual variation
in the pharmacokinetics of paroxetine in adults as well as in the elderly with
higher plasma concentrations and slower elimination noted in the latter.
Elimination is also reduced in severe renal and hepatic impairment, however,
serious adverse events are extremely rare even in overdose. A Pub Med search was
used to collect information on the efficacy and tolerability in elderly
patients. There are few studies of depression in the elderly and only one study
in the old-old. In anxiety disorders including general anxiety disorder, panic
disorder, obsessive-compulsive disorder and social anxiety, there are no studies
at all in the elderly. However, the safety of the drug allows its prescription
in the elderly. In summary, paroxetine is well tolerated in the treatment of
depression in those between the ages of 65 and 75, although few studies have
examined its use in those of 75 and older. A controlled-release (CR) formulation of the SSRI paroxetine has been developed.
This CR formulation delays the release of paroxetine until the tablet has passed
through the stomach; the drug is then released over 4-5 hours. In well designed
placebo-controlled trials in patients with major depressive disorder (including
a study in the elderly), social anxiety disorder or premenstrual dysphoric
disorder (PMDD), paroxetine CR was consistently superior to placebo with regards
to primary endpoints (i.e. mean Hamilton Rating Scale for Depression total score
[major depressive disorder], Liebowitz social anxiety scale total score and
Clinical Global Impressions-Global Improvement score [social anxiety disorder]
and Visual Analogue Scale-Mood score [PMDD]). The duration of treatment was 12
weeks or, in PMDD, over three menstrual cycles (intermittent or continuous
administration). Paroxetine CR also demonstrated efficacy in three well designed
studies in patients with panic disorder with or without agoraphobia. Paroxetine
CR was generally well tolerated in clinical trials, with an adverse-event
profile typical of SSRIs, although recipients of paroxetine CR experienced
significantly less nausea than recipients of immediate-release paroxetine in the
first week of treatment. This review focuses on current information about luteal phase administration
(i.e. typically for the last 2 weeks of the menstrual cycle) of pharmacological
agents for the treatment of premenstrual dysphoric disorder (PMDD). Compared
with continuous administration, a luteal phase administration regimen reduces
the exposure to medication and lowers the costs of treatment. Based on evidence
from randomised clinical trials, SSRIs are the first-line treatment for PMDD at
this time. Of these agents, sertraline, fluoxetine and paroxetine (as an
extended-release formulation) are approved by the US FDA for luteal phase, as
well as continuous, administration. Clinical trials of these agents and
citalopram have demonstrated that symptom reduction is similar with both
administration regimens. When used to treat PMDD, SSRI doses are consistent with
those used for major depressive disorder. The medications are well tolerated;
discontinuation symptoms with this intermittent administration regimen have not
been reported. Other medications that have been examined in clinical trials for
PMDD or severe premenstrual syndrome (PMS) using luteal phase administration
include buspirone, alprazolam, tryptophan and progesterone. Buspirone and
alprazolam show only modest efficacy in PMS (in some but not all studies), but
there may be a lower incidence of sexual adverse effects with these medications
than with SSRIs. Symptom reduction with tryptophan was significantly greater
than with placebo, but the availability of this medication is strictly limited
because of safety concerns. Progesterone has consistently failed to show
efficacy for severe PMS/PMDD in large, randomised, placebo-controlled trials. BACKGROUND: Better characterization of safety and efficacy of multiple doses of
selective serotonin reuptake inhibitors for the treatment of a wider range of
symptoms of premenstrual dysphoric disorder (PMDD) will provide clinicians with
flexibility to provide symptom relief along with acceptable tolerability. This
study was designed to assess the efficacy and tolerability of multiple doses of
paroxetine controlled release (CR) in PMDD.
METHODS: In a multicenter (43 outpatient U.S. sites), placebo-controlled trial,
327 females aged 18 to 45 years, with regular menstrual cycles, meeting DSM-IV
criteria for PMDD, were randomly assigned to receive paroxetine CR 12.5 mg;
paroxetine CR 25 mg; or placebo, once daily, for up to three treatment cycles.
The primary efficacy outcome was change from baseline to end point in mean
luteal phase Visual Analogue Scale-Mood (irritability, tension, affective
lability, depressed mood) score.
RESULTS: At end point, subjects treated with paroxetine CR (12.5 mg and 25 mg)
demonstrated significant improvement in VAS-Mood scores compared with those who
received placebo (paroxetine CR 12.5 mg mean treatment difference vs. placebo,
-8.7 mm; 95% CI, -15.7, -1.7; p =.015; paroxetine CR 25 mg mean treatment
difference vs. placebo, -12.1 mm; 95% CI, -18.9, -5.3; p <.001). Results were
also significant across measures of physical symptoms and social functioning.
Paroxetine CR was well tolerated; 9.5% of subjects treated with 12.5 mg and
13.5% of subjects treated with 25 mg withdrew from the trial due to adverse
events, compared with 6.5% of subjects in the placebo group.
CONCLUSIONS: Both doses of paroxetine CR 12.5 mg and 25 mg daily are effective
and well tolerated in patients who suffer from PMDD. Efficacy with both doses
affords greater flexibility to the prescribing physician. BACKGROUND: Because of the poor quality of mental health care received by
minorities, analyses documenting comparable response to and tolerability of
medications for anxiety and depression in large samples of minority and majority
populations could increase the willingness of providers and patients to use
medications in minority populations.
METHOD: A pooled analysis of 14,875 adults who participated in 104 double-blind,
placebo-controlled paroxetine clinical trials investigating major depression,
panic disorder, generalized anxiety disorder, social anxiety disorder,
obsessive-compulsive disorder, posttraumatic stress disorder, or premenstrual
dysphoric disorder from March 1984 through March 2002. An intent-to-treat
analysis with last observation carried forward used the Clinical Global
Impressions (CGI) scale to measure dichotomous outcome, classified as either
response (CGI score of 1 or 2) or more complete response (CGI score of 1) ("full
response"). Minority group differences were examined using logistic regression
for the entire sample and repeated for those with major depression. Adverse
events greater than 5% and twice the rate of placebo were descriptively
tabulated. Finally, a survival analysis examined group differences in speed of
onset of response.
RESULTS: Hispanic and Asian subjects had a slightly lower response rate, while
Asians had the highest rates and Hispanics had the lowest rates of "full
response." The more consistent Hispanic outcome differences appeared to be due
to a higher placebo response rate. There was no treatment by minority group
interaction for depressed patients. Speed of response and adverse effects were
similar across groups.
CONCLUSIONS: There were few consistent differences in medication response and
tolerability. These findings may serve to counteract the greater rate of
negative attitudes toward medication use among minorities and reinforce the
value of medications used to treat anxiety and depression in minorities. AIMS: Several trials have proved the efficacy of selective serotonin re-uptake
inhibitors (SSRI) in the treatment of premenstrual dysphoric disorder (PMDD) in
Western society. The SSRI can be administered continuously throughout the entire
cycle or intermittently from ovulation to the onset of menstruation (luteal
phase). The purpose of the present study was to compare continuous and
intermittent paroxetine treatment in oriental PMDD women during 6 months follow
up.
METHODS: Thirty-six subjects were evaluated and drug free for two menstrual
cycles, and they received daily paroxetine (20 mg) for two further full cycles.
They were then randomly divided into continuous or intermittent treatment groups
(n = 16, 14) over the next four cycles. Responses were assessed every 2 weeks.
Outcome measures included scores on the Prospective Record of the Impact and
Severity of Menstrual Symptomatology (PRISM) calendar, Hamilton Rating Scale for
Depression/Anxiety (HAMD/HAMA), and the Clinical Global Impression scale (CGI).
RESULTS: All these women had significant improvements in the HAMA, HAMD, CGI,
and PRISM calendar. The rate of response to paroxetine treatment lay between 50%
and 78.6% in the continuous-treatment group, and 37.5-93.8% in the
intermittent-treatment group, as determined at the study end-point. Limitations
of the present study included the open-label design and the incorporation of a
limited sample size.
CONCLUSIONS: The present results indicate that paroxetine is effective in both
continuous and intermittent treatment of oriental PMDD women, and that the
effects of active treatment lasted for six consecutive treatment menstrual
cycles. OBJECTIVE: To evaluate the efficacy and safety of intermittent, luteal
phase-only administration of paroxetine (10 mg and 20 mg) in the treatment of
premenstrual dysphoric disorder (PMDD).
METHOD: In this multicenter trial, female outpatients (aged 18-45 years) from 4
Canadian health centers meeting DSM-IV criteria for PMDD were asked to perform
daily ratings of their premenstrual symptoms for 2 consecutive menstrual cycles.
Those displaying the symptoms of irritability and/or depressed mood in the
luteal phases but not in the follicular phases of their menstrual cycles were
randomly assigned to intermittent, luteal phase-only treatment with paroxetine
10 mg or 20 mg or placebo for 4 additional cycles. The primary efficacy endpoint
was the percent change from baseline at study endpoint on the visual analog
scale irritability score. Treatment differences were tested using analysis of
covariance ad hoc. Estimated treatment mean differences and their associated 95%
confidence intervals were also calculated. Data were collected from May 1999 to
November 2002.
RESULTS: Ninety-nine patients were included in the intention-to-treat
population. When compared with placebo, patients treated with paroxetine 20 mg
attained a significant reduction in irritability (difference in median percent
change: -23.9, 95% CI = -51.3 to -6.2, p = .014; difference in mean absolute
change: -18.6, 95% CI = -32.5 to -4.6, p = .007). A statistically significant
difference was not observed when the patients treated with the lower dose of
paroxetine (10 mg) were compared with placebo. Treatment was well tolerated with
no unexpected side effects.
CONCLUSIONS: Intermittent administration of paroxetine 20 mg significantly
reduced irritability symptoms in patients with PMDD. These results are
consistent with previous studies suggesting that PMDD may be treated effectively
by luteal phase-only administration of a selective serotonin reuptake inhibitor.
TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00620581. OBJECTIVE: To evaluate the current nonpharmacologic and pharmacologic treatment
options for symptoms of premenstrual syndrome (PMS) and premenstrual dysphoric
disorder (PMDD).
DATA SOURCES: Literature was obtained through searches of MEDLINE Ovid
(1950-March week 3, 2008) and EMBASE Drugs and Pharmacology (all years), as well
as a bibliographic review of articles identified by the searches. Key terms
included premenstrual syndrome, premenstrual dysphoric disorder, PMS, PMDD, and
treatment.
STUDY SELECTION/DATA EXTRACTION: All pertinent clinical trials, retrospective
studies, and case reports in human subjects published in the English language
were identified and evaluated for the safety and efficacy of pharmacologic and
nonpharmacologic treatments of PMS/PMDD. Data from these studies and information
from review articles were included in this review.
DATA SYNTHESIS: Selective serotonin-reuptake inhibitors (SSRIs) have been proven
safe and effective for the treatment of PMDD and are recommended as first-line
agents when pharmacotherapy is warranted. Currently fluoxetine,
controlled-release paroxetine, and sertraline are the only Food and Drug
Administration-approved agents for this indication. Suppression of ovulation
using hormonal therapies is an alternative approach to treating PMDD when SSRIs
or second-line psychotropic agents are ineffective; however, adverse effects
limit their use. Anxiolytics, spironolactone, and nonsteroidal antiinflammatory
drugs can be used as supportive care to relieve symptoms. Despite lack of
specific evidence, lifestyle modifications and exercise are first-line
recommendations for all women with PMS/PMDD and may be all that is needed to
treat mild-to-moderate symptoms. Herbal and vitamin supplementation and
complementary and alternative medicine have been evaluated for use in PMS/PMDD
and have produced unclear or conflicting results. More controlled clinical
trials are needed to determine their safety and efficacy and potential for drug
interactions.
CONCLUSIONS: Healthcare providers need to be aware of the symptoms of PMS and
PMDD and the treatment options available. Treatment selection should be based on
individual patient symptoms, concomitant medical history, and need for
contraception. Because of limitations in diagnosis coding, it is difficult to determine which
products are used to treat premenstrual dysphoric disorder. To better understand
treatment of premenstrual dysphoric disorder, we examined the antidepressant
prescribing behavior of obstetrician/gynecologists as a marker for premenstrual
dysphoric disorder treatment and compare these use patterns to psychiatrists and
primary care physicians. Over the past quarter, only three percent of
antidepressants were prescribed by obstetrician/gynecologists as compared to 51
percent by primary care physicians and 20 percent by psychiatrists.
Obstetrician/ gynecologists more frequently use selective serotonin reuptake
inhibitors (69% compared to 58% in primary care and 48% in psychiatry) and are
more likely to choose an selective serotonin reuptake inhibitors agent indicated
for the treatment of premenstrual dysphoric disorder (e.g., fluoxetine,
paroxetine, sertraline): 66 percent versus 59 percent for both primary care
physicians and psychiatrists. Use of desvenlafaxine was slightly elevated in
obstetrician/ gynecologists as compared to primary care physicians (0.3% vs.
0.1% of total antidepressants, respectively); however, psychiatrists prescribed
more desvenlafaxine than either group: 0.4 percent of total antidepressant
prescriptions. Discussion of this data is provided. Premenstrual dysphoric disorder, which affects 3-8% of women of reproductive
age, is characterized by a combination of symptoms that may include depressed
mood, irritability, anxiety and/or physical symptoms. These symptoms occur
during the luteal phase of the menstrual cycle, with remission generally
occurring within 3 days after the onset of menses. Presently, treatment
guidelines for premenstrual dysphoric disorder focus on lifestyle management and
psychopharmacologic interventions, with selective serotonin reuptake inhibitors
being considered the first line of medication intervention. The US Food and Drug
Administration and Health Canada recently approved paroxetine for the treatment
of premenstrual dysphoric disorder. This article reviews the properties of this
medication and its use in the treatment of premenstrual dysphoric disorder. |
What is known about thalidomide therapy and survival of glioblastoma patients? | Findings regarding clinical value of thalidomide in terms of survival in patients with glioblastoma remain mixed. It has been shown that thalidomide can improve survival of recurrent glioblastoma patients. However, other authors have not confirmed these findings. Furthermore, thalidomide did not improve survival of newly diagnosed glioblastoma and pediatric glioblastoma patients. | PURPOSE: Little progress has been made in the treatment of adult high-grade
gliomas over the last two decades, thus necessitating a search for novel
therapeutic strategies. Maligt gliomas are vascular or angiogenic tumors,
which leads to the supposition that angiogenesis inhibition may represent a
potentially promising strategy in the treatment of these tumors. We present the
results of a phase II trial of thalidomide, a putative inhibitor of
angiogenesis, in the treatment of adults with previously irradiated, recurrent
high-grade gliomas.
PATIENTS AND METHODS: Patients with a histologic diagnosis of anaplastic mixed
glioma, anaplastic astrocytoma, or glioblastoma multiforme who had radiographic
demonstration of tumor progression after standard external-beam radiotherapy
with or without chemotherapy were eligible. Patients were initially treated with
thalidomide 800 mg/d with increases in dose by 200 mg/d every 2 weeks until a
final daily dose of 1,200 mg was achieved. Patients were evaluated every 8 weeks
for response by both clinical and radiographic criteria.
RESULTS: A total of 39 patients were accrued, with 36 patients being assessable
for both toxicity and response. Thalidomide was well tolerated, with
constipation and sedation being the major toxicities. One patient developed a
grade 2 peripheral neuropathy after treatment with thalidomide for nearly a
year. There were two objective radiographic partial responses (6%), two minor
responses (6%), and 12 patients with stable disease (33%). Eight patients were
alive more than 1 year after starting thalidomide, although almost all with
tumor progression. Changes in serum levels of basic fibroblastic growth factor
(bFGF) were correlated with time to tumor progression and overall survival.
CONCLUSION: Thalidomide is a generally well-tolerated drug that may have
antitumor activity in a minority of patients with recurrent high-grade gliomas.
Future studies will better define the usefulness of thalidomide in newly
diagnosed patients with maligt gliomas and in combination with radiotherapy
and chemotherapy. Additionally, studies will be needed to confirm the potential
utility of changes in serum bFGF as a marker of antiangiogenic activity and/or
glioma growth. PURPOSE: The chemotherapeutic agent temozolomide (TMZ) and the antiangiogenic
agent thalidomide have both demonstrated antitumor activity in patients with
recurrent maligt glioma. The objectives of this study were to determine if
the combined strategy of these oral agents with radiation therapy (RT) is
associated with an improved median survival of patients with newly diagnosed
glioblastoma multiforme and to evaluate toxicity.
METHODS AND MATERIALS: Sixty-seven patients were enrolled in this trial.
Radiotherapy parameters were a total dose of 60 Gy delivered in 2 Gy fractions
over 6 weeks. Temozolomide was administered starting the first day of RT at 150
mg/m(2) daily for 5 days every 4 weeks for the first cycle and escalated to a
maximum dose of 200 mg/m(2). Thalidomide was started on Day 7 of RT at 200 mg
and escalated by 100-200 mg every 1-2 weeks depending on patient tolerance, to a
maximum of 1,200 mg daily.
RESULTS: Sixty-one patients have progressed, with a median time to progression
of 22 weeks. Fifty-six patients have died, and the median survival was 73 weeks.
CONCLUSIONS: This strategy of combination TMZ, thalid and RT was relatively well
tolerated with favorable survival outcome for patients with GM when compared to
patients not treated with adjuvant chemotherapy and similar to those who have
received nitrosourea adjuvant chemotherapy. It is unclear the added advantage
thalid has in combination with TMZ for this patient population. PURPOSE: This Phase II study was designed to determine the median survival time
of adults with supratentorial glioblastoma treated with a combination of
temozolomide (TMZ) and 13-cis-retinoic acid (cRA) given daily with conventional
radiation therapy (XRT).
METHODS AND MATERIALS: This was a single arm, open-labeled, Phase II study.
Patients were treated with XRT in conjunction with cRA and TMZ. Both drugs were
administered starting on Day 1 of XRT, and chemotherapy cycles continued after
the completion of XRT to a maximum of 1 year.
RESULTS: Sixty-one patients were enrolled in the study. Time to progression was
known for 55 patients and 6 were censored. The estimated 6-month
progression-free survival was 38% and the estimated 1-year progression-free
survival was 15%. Median time to progression was estimated as 21 weeks. The
estimated 1-year survival was 57%. The median survival was 57 weeks.
CONCLUSIONS: The combined therapy was relatively well tolerated, but there was
no survival advantage compared with historical studies using XRT either with
adjuvant nitrosourea chemotherapy, with TMZ alone, or with the combination of
TMZ and thalidomide. Based on this study, cRA does not seem to add a significant
synergistic effect to TMZ and XRT. Experimental studies have demonstrated that thalidomide has anti-tumor activity
mediated by blockage of angiogenesis, with clinical efficacy in multiple
myeloma, glioblastoma multiforme, and renal cell cancer. We investigated the
therapeutic activity and toxicity of thalidomide in patients with progressive
metastatic breast cancer pretreated with chemotherapy. Inclusion criteria were
metastatic breast cancer in progression of disease after at least two lines of
chemotherapy, age > or = 18 years, performance status < or = 2, and adequate
hematologic, renal, and hepatic functions. Twelve patients entered the study,
eight of whom were pretreated with three or more lines of chemotherapy (66.7%).
Thalidomide was well tolerated: the most common side effects were constipation
and somnolence (58.3% of patients). No objective response or durable stable
disease was observed. Median time to progression and median overall survival
were 8 weeks (range, 4-10 weeks) and 16 weeks (range, 8-54 weeks), respectively.
In conclusion, thalidomide is an ineffective treatment in patients with
progressive metastatic breast cancer heavily pretreated with chemotherapy. OBJECTIVE: The aim of this study was to assess efficacy and toxicity of
temozolomide given alone or in combination with thalidomide, an
anti-angiogenetic drug, in patients with newly diagnosed glioblastoma multiforme
(GBM).
PATIENTS AND METHODS: 46 patients with histologically proven GBM were eligible
for inclusion. Twenty-three patients (15 males and 8 females) received
temozolomide on a conventional schedule; 23 patients (12 males and 11 females)
received temozolomide on the same schedule and thalidomide was dose-adjusted in
each individual patient based on their tolerance.
RESULTS: The median survival time was 12 months for temozolomide and 13 months
for temozolomide + thalidomide.
CONCLUSION: The administration of temozolomide in association with thalidomide
after radiotherapy (RT) does not offer an advantage over temozolomide alone in
adults with newly diagnosed GBM. The two therapeutic strategies produce similar
results for survival, but the latter regimen shows a moderate increase in
toxicity. We conducted a phase II study of the combination of temozolomide and
angiogenesis inhibitors for treating adult patients with newly diagnosed
glioblastoma. Patients who had stable disease following standard radiation
therapy received temozolomide for 5 days in 28-day cycles, in combination with
daily thalidomide and celecoxib. Patients were treated until tumor progression
or development of unacceptable toxicity. Four-month progression-free survival
(PFS) from study enrollment was the primary end point, and overall survival (OS)
was the secondary end point. In addition, we sought to correlate response with
O(6)-methylguanine-DNA methyltransferase promoter methylation status and serum
levels of angiogenic peptides. Fifty patients with glioblastoma were enrolled
(18 women, 32 men). Median age was 54 years (range, 29-78) and median KPS score
was 90 (range, 70-100). From study enrollment, median PFS was 5.9 months (95%
confidence interval [CI]: 4.2-8.0) and 4-month PFS was 63% (95% CI: 46%-75%).
Median OS was 12.6 months (95% CI: 8.5-16.4) and 1-year OS was 47%. Of the 47
patients evaluable for best response, none had a complete response, five (11%)
had partial response, four (9%) had minor response, 22 (47%) had stable disease,
and 16 (34%) had progressive disease. Analysis of serial serum samples obtained
from 47 patients for four angiogenic peptides failed to show a significant
correlation with response or survival for three of the peptides; higher vascular
endothelial growth factor levels showed a trend toward correlation with
decreased OS (p=0.07) and PFS (p=0.09). The addition of celecoxib and
thalidomide to adjuvant temozolomide was well tolerated but did not meet the
primary end point of improvement of 4-month PFS from study enrollment. PURPOSE: Irinotecan is a cytotoxic agent with activity against gliomas.
Thalidomide, an antiangiogenic agent, may play a role in the treatment of
glioblastoma multiforme (GBM). To evaluate the combination of thalidomide and
irinotecan, we conducted a phase II trial in adults with newly-diagnosed or
recurrent GBM.
PATIENTS AND METHODS: Thalidomide was given at a dose of 100 mg/day, followed by
dose escalation every 2 weeks by 100 mg/day to a target of 400 mg/day.
Irinotecan was administered on day 1 of each 3 week cycle. Irinotecan dose was
700 mg/m(2) for patients taking enzyme-inducing anticonvulsants and 350 mg/m(2)
for all others. The primary endpoint was tumor response, assessed by MRI.
Secondary endpoints were toxicity, progression-free survival, and overall
survival.
RESULTS: Twenty-six patients with a median age of 55 years were enrolled, with
fourteen evaluable for the primary outcome, although all patients were included
for secondary endpoints. One patient (7%) exhibited a partial response after
twelve cycles, and eleven patients (79%) had stable disease. The intention to
treat group with recurrent disease included 16 patients who had a 6-month PFS of
19% (95% CI: 4-46%) and with newly-diagnosed disease included 10 patients who
had a 6-month PFS of 40% (95% CI: 12-74%). Gastrointestinal (GI) toxicity was
mild, but six patients (23%) experienced a venous thromboembolic complication.
Two patients had Grade 4 treatment-related serious adverse events that required
hospitalization. There were no treatment-related deaths.
CONCLUSION: The combination of irinotecan and thalidomide has limited activity
against GBM. Mild GI toxicity was observed, but venous thromboembolic
complications were common. External beam radiation therapy (XRT) with concomitant temozolomide and 6 cycles
of adjuvant temozolomide (5/28-day schedule) improves survival in patients with
newly diagnosed glioblastoma compared with XRT alone. Studies suggest that
dose-dense temozolomide schedules and addition of cytostatic agents may further
improve efficacy. This factorial design phase I/II protocol tested dose-dense
temozolomide alone and combined with cytostatic agents. Patients with newly
diagnosed glioblastoma received fractionated XRT to 60 Gy concomitant with
temozolomide (75 mg/m²)/day for 42 days). In the phase I portion, patients with
stable disease or radiologic response 1 month after chemoradiation were
randomized to adjuvant temozolomide alone (150 mg/m²/day, 7/14-day schedule) or
with doublet combinations of thalidomide (400 mg/day), isotretinoin (100
mg/m²/day), and/or celecoxib (400 mg twice daily), or all 3 agents. Toxicity was
assessed after 4 weeks. Among 54 patients enrolled (median age, 52 years; median
Karnofsky performance status, 90), adjuvant treatment was not administered to 12
(22%), primarily because of disease progression (n = 10). All combinations were
well tolerated. Grade 3/4 lymphopenia developed in 63% of patients, but no
related infections occurred. One patient treated with temozolomide plus
isotretinoin plus thalidomide had dose-limiting grade 3 fatigue and rash, and 1
patient receiving all 4 agents had dose-limiting grade 4 neutropenia. Venous
thrombosis occurred in 7 patients, 4 of whom received thalidomide. From study
entry, median survival was 20 months and the 2-year survival rate was 40%.
Multiple cytostatic agents can be safely combined with dose-dense temozolomide.
The factorial-based phase II portion of this study is currently ongoing. This open-label, single-arm, phase II study combined enzastaurin with
temozolomide plus radiation therapy (RT) to treat glioblastoma multiforme (GBM)
and gliosarcoma. Adults with newly diagnosed disease and Karnofsky performance
status (KPS) ≥ 60 were enrolled. Treatment was started within 5 weeks after
surgical diagnosis. RT consisted of 60 Gy over 6 weeks. Temozolomide was given
at 75 mg/m(2) daily during RT and then adjuvantly at 200 mg/m(2) daily for 5
days, followed by a 23-day break. Enzastaurin was given once daily during RT and
in the adjuvant period at 250 mg/day. Cycles were 28 days. The primary end point
was overall survival (OS). Progression-free survival (PFS), toxicity, and
correlations between efficacy and molecular markers analyzed from tumor tissue
samples were also evaluated. A prospectively planned analysis compared OS and
PFS of the current trial with outcomes from 3 historical phase II trials that
combined novel agents with temozolomide plus RT in patients with GBM or
gliosarcoma. Sixty-six patients were enrolled. The treatment regimen was well
tolerated. OS (median, 74 weeks) and PFS (median, 36 weeks) results from the
current trial were comparable to those from a prior phase II study using
erlotinib and were significantly better than those from 2 other previous studies
that used thalidomide or cis-retinoic acid, all in combination with temozolomide
plus RT. A positive correlation between O-6-methylguanine-DNA methyltransferase
promoter methylation and OS was observed. Adjusting for age and KPS, no other
biomarker was associated with survival outcome. Correlation of relevant
biomarkers with OS may be useful in future trials. BACKGROUND: Therapeutic options for patients with anaplastic gliomas (AGs) are
limited despite better insights into glioma biology. The authors previously
reported improved outcome in patients with recurrent glioblastoma treated with
thalidomide and irinotecan compared with historical controls. Here, results of
the AG arm of the study are reported, using this drug combination.
METHODS: Adults with recurrent AG previously treated with radiation therapy,
with Karnofsky performance score ≥70, adequate organ function and not on
enzyme-inducing anticonvulsants were enrolled. Treatment was in 6-week cycles
with irinotecan at 125 mg/m(2) weekly for 4 weeks followed by 2 weeks off, and
thalidomide at 100 mg daily increased to 400 mg/day as tolerated. The primary
endpoint was progression-free survival rate at 6 months (PFS-6), and the
secondary endpoints were overall survival (OS) and response rate (RR).
RESULTS: In 39 eligible patients, PFS-6 for the intent-to-treat population was
36% (95% confidence interval [CI] = 21%, 53%), median PFS was 13 weeks (95% CI =
6%, 28%) and RR was 10%(95% CI = 3%, 24%). Radiological findings included 2
complete and 2 partial responses and 17 stable disease. Median OS from study
registration was 62 weeks, (95% CI = 51, 144). Treatment-related toxicities
(grade 3 or higher) included neutropenia, diarrhea, nausea, and fatigue; 6
patients experienced venous thromboembolism. Four deaths were attributable to
treatment-related toxicities: 1 from pulmonary embolism, 2 from colitis, and 1
from urosepsis.
CONCLUSIONS: The combination of thalidomide and irinotecan did not achieve
sufficient efficacy to warrant further investigation against AG, although a
subset of patients experienced prolonged PFS/OS. A trial of the more potent
thalidomide analogue, lenalidomide, in combination with irinotecan against AG is
currently ongoing. The Radiation Therapy Oncology Group (RTOG) initiated the single-arm, phase II
study 9806 to determine the safety and efficacy of daily thalidomide with
radiation therapy in patients with newly diagnosed glioblastoma. Patients were
treated with thalidomide (200 mg daily) from day one of radiation therapy,
increasing by 100-200 to 1,200 mg every 1-2 weeks until tumor progression or
unacceptable toxicity. The median survival time (MST) of all 89 evaluable
patients was 10 months. When compared with the historical database stratified by
recursive partitioning analysis (RPA) class, this end point was not different
[hazard ratio (HR) = 1.18; 95 % CI: 0.95-1.46; P = 0.93]. The MST of RPA class
III and IV patients was 13.9 versus 12.5 months in controls (HR = 0.99; 95 % CI:
0.73-1.36; P = 0.48), and 4.3 versus 8.6 months in RPA class V controls
(HR = 1.63, 95 % CI: 1.17-2.27; P = 0.99). In all, 34 % of patients discontinued
thalidomide because of adverse events or refusal. The most common grade 3-4
toxicities were venous thrombosis, fatigue, skin reactions, encephalopathy, and
neuropathy. In conclusion, thalidomide given simultaneously with radiation
therapy was safe, but did not improve survival in patients with newly diagnosed
glioblastoma. |
Is endostatin a proangiogenic factor? | No, endostatin is an antiangiogenic factor | INTRODUCTION: Angiogenesis activation plays a crucial role in tumoral growth and
metastases dissemination. This review summarizes and analyzes current knowledge
on molecular mechanisms related to angiogenesis and the prognostic value of its
effectors. It also focuses on the therapeutical relevance of various drugs that
might inhibit angiogenesic processes.
CURRENT KNOWLEDGE AND KEY POINTS: Tumor angiogenesis involves complex
interactions between tumoral, stromal, endothelial cells, fibroblasts and the
extracellular matrix. Normal and maligt angiogenesis depends on the balance
of proangiogenic and antiangiogenic factors. Endothelial cells are activated by
growth factors, such as Vascular Endothelial Growth Factor (VEGF), and
proliferate; they release proteases able to induce degradation of the basement
membrane and extracellular matrix, and undergo migration and tubulogenesis.
Angiostatin and endostatin are two powerful inhibitors of angiogenesis in
experimental models. Assessment of intratumoral microvessel density and
quantification of angiogenic factors, including VEGF, are of prognostic value in
most cancers, particularly in breast cancer. However, the use of these prognosis
markers in clinical practice is still controversial due to the lack of
prospective studies and to technical limits inherent to the scoring and
standardization of immunohistochemical methods.
FUTURE PROSPECTS AND PROJECTS: Better understanding of the molecular basis of
angiogenesis allows the development of new therapeutical strategies. Biochemical
targets of antiangiogenic therapy are: the interaction between angiogenic
factors and their receptors; the interaction of endothelial cells with the
extracellular matrix; and intracellular signaling pathways. Angiogenesis
inhibitors may not cause tumor regression, but inhibit cellular growth and
produce "disease dormancy". Extensive phase I to III clinical trials involving
antiangiogenesis therapy are in progress. Angiogenesis, or the formation of new blood vessels out of pre-existing
capillaries, is a sequence of events that is fundamental to many physiologic and
pathologic processes such as cancer, ischemic diseases, and chronic
inflammation. With the identification of several proangiogenic molecules such as
the vascular endothelial cell growth factor, the fibroblast growth factors (like
in FGFs), and the angiopoietins, and the recent description of specific
inhibitors of angiogenesis such as platelet factor-4, angiostatin, endostatin,
and vasostatin, it is recognized that therapeutic interference with vasculature
formation offers a tool for clinical applications in various pathologies.
Whereas inhibition of angiogenesis can prevent diseases with excessive vessel
growth such as cancer, diabetes retinopathy, and arthritis, stimulation of
angiogenesis would be beneficial in the treatment of diseases such as coronary
artery disease and critical limb ischemia in diabetes. In this review we
highlight the current knowledge on angiogenesis regulation and report on the
recent findings in angiogenesis research and clinical studies. We also discuss
the potentials, limitations, and challenges within this field of research, in
light of the development of new therapeutic strategies for diseases in which
angiogenesis plays an important role. BACKGROUND: Solid tumors are angiogenesis dependent, and elevated levels of
proangiogenic cytokines have been reported in a variety of histologies.
Endostatin is an antiangiogenic fragment of the basement membrane protein,
collagen XVIII. Because antiangiogenic protein fragments may be generated by
tumor-derived proteases, the authors sought to determine whether circulating
levels of endostatin were elevated in patients with localized soft tissue
sarcoma.
METHODS: The authors analyzed preoperative serum levels of endostatin, vascular
endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) in
25 patients (14 males and 11 females; mean age, 44 years) with soft tissue
sarcoma. For each serum sample, two aliquots were assayed in duplicate using a
competitive enzyme immunoassay. Serum levels were compared with levels from 34
age-matched and gender-matched volunteer blood donors.
RESULTS: Endostatin levels were significantly higher in sera from sarcoma
patients than in sera from healthy controls (43.0 ng/mL vs. 25.8 ng/mL,
respectively; P = 0.0002; Mann-Whitney U test). Significant elevations also were
noted in VEGF and bFGF levels (P = 0.0002 and P = 0.0001, respectively).
Furthermore, endostatin levels > 2 standard deviations above the control mean
(55 ng/mL) were associated with an increased risk of tumor recurrence after
resection (P = 0.047; log-rank test).
CONCLUSIONS: Serum endostatin, VEGF, and bFGF levels are elevated in patients
with soft tissue sarcoma. Elevated endostatin levels appear to be associated
with tumor aggressiveness. The role of these cytokines in sarcoma angiogenesis
and as potential targets for therapy warrants further study. Angiogenesis seems to be important both in the pathogenesis of acute myelogenous
leukemia (AML) and for the susceptibility of AML blasts to chemotherapy. Recent
clinical studies even suggest that antiangiogenic therapy can induce disease
control in patients with AML relapse. In this context we have investigated the
profile of the systemic component of angiogenic regulation in AML by
characterizing the serum levels of (i) the angiogenic regulators angiogenin,
basic fibroblast growth factor (bFGF) and endostatin; (ii) the endothelial cell
marker soluble (s) E-selectin. Patients with untreated AML had increased levels
of angiogenin, endostatin and sE-selectin, whereas the levels of bFGF were not
significantly altered. The systemic levels of the proangiogenic bFGF, the
antiangiogenic endostatin and the endothelial cell marker sE-selectin showed
significant correlations, whereas angiogenin and sE-selectin levels were not
correlated. Furthermore, intensive chemotherapy resulted in decreased systemic
levels of the 2 proangiogenic mediators angiogenin and bFGF, whereas endostatin
levels remained high after treatment. Although angiogenin normally is a part of
the acute phase reaction, its systemic levels were not altered when patients
with chemotherapy-induced cytopenia developed complicating bacterial infections.
Our results suggest that intensive chemotherapy can modulate the systemic
component of angiogenic regulation in AML patients. Cancer therapies based on the inhibition of angiogenesis by endostatin have
recently been developed. We demonstrate that a mutated form of human endostatin
(P125A) can inhibit the angiogenic switch in the C3(1)/Tag mammary cancer model.
P125A has a stronger growth-inhibitory effect on endothelial cell proliferation
than wild-type endostatin. We characterize the angiogenic switch, which occurs
during the transition from preinvasive lesions to invasive carcinoma in this
model, and which is accompanied by a significant increase in total protein
levels of vascular endothelial growth factor (VEGF) and an invasion of blood
vessels. Expression of the VEGF(188) mRNA isoform, however, is suppressed in
invasive carcinomas. The VEGF receptors fetal liver kinase-1 (Flk-1) and
Fms-like tyrosine kinase-1 (Flt-1) become highly expressed in epithelial tumor
and endothelial cells in the mammary carcinomas, suggesting a potential
autocrine effect for VEGF on tumor cell growth. Angiopoietin-2 mRNA levels are
also increased during tumor progression. CD-31 (platelet-endothelial cell
adhesion molecule [PECAM]) staining revealed that blood vessels developed in
tumors larger than 1 mm The administration of P125A human endostatin in
C3(1)/Tag females resulted in a significant delay in tumor onset, decreased
tumor multiplicity and tumor burden and prolonged survival of the animals.
Endostatin treatment did not reduce the number of preinvasive lesions,
proliferation rates or apoptotic index, compared with controls. However, mRNA
levels of a variety of proangiogenic factors (VEGF, VEGF receptors Flk-1 and
Flt-1, angiopoietin-2, Tie-1, cadherin-5 and PECAM) were significantly decreased
in the endostatin-treated group compared with controls. These results
demonstrate that P125A endostatin inhibits the angiogenic switch during mammary
gland adenocarcinoma tumor progression in the C3(1)/Tag transgenic model. Angiogenesis is required for invasive tumor growth and metastasis and
constitutes an important point in the control of cancer progression. Its
inhibition may be a valuable new approach to cancer therapy. Avascular tumors
are severely restricted in their growth potential because of the lack of a blood
supply. For tumors to develop in size and metastatic potential they must make an
"angiogenic switch" through perturbing the local balance of proangiogenic and
antiangiogenic factors. Frequently, tumors overexpress proangiogenic factors,
such as vascular endothelial growth factor, allowing them to make this
angiogenic switch. Two strategies used in the development of antiangiogenic
agents involve the inhibition of proangiogenic factors (eg, anti-vascular
endothelial growth factor monoclonal antibodies) as well as therapy with
endogenous inhibitors of angiogenesis, such as endostatin and angiostatin.
Therapy with endogenous angiogenic inhibitors such as endostatin and angiostatin
may reverse the angiogenic switch preventing growth of tumor vasculature.
Preclinical studies have shown that endostatin effectively inhibits tumor growth
and shrinks existing tumor blood vessels. Phase 1 clinical trials of endostatin
and angiostatin are ongoing, and preliminary results show minimal toxicities. PURPOSE: Endostatin is the first endogenous angiogenesis inhibitor to enter
clinical trials. Laboratory investigations with endostatin have indicated broad
antitumor activity coupled with remarkably low toxicity. A phase I trial of
recombit human endostatin was designed to evaluate toxicity and explore
biologic effectiveness in patients with refractory solid tumors.
PATIENTS AND METHODS: Endostatin was administered as a 1-hour intravenous
infusion given daily for a 28-day cycle. A starting dose of 30 mg/m2 was
explored with subsequent dose escalations of 60, 100, 150, 225, and 300 mg/m2.
Assessment of serum pharmacokinetics was performed on all 21 patients. Western
blot assay and mass spectroscopy were employed to evaluate endostatin
metabolism. Circulating levels of endogenous proangiogenic growth factors were
examined. Tumor and tumor blood supply were imaged by dynamic computed
tomography (CT), magnetic resoce imaging, ultrasound, and positron emission
tomography.
RESULTS: Endostatin given on this schedule was essentially free of significant
drug-related toxicity. Two transient episodes of grade 1 rash were observed. No
clinical responses were observed. Endostatin pharmacokinetics were linear with
dose, and serum concentrations were achieved that are associated with antitumor
activity in preclinical models. No aggregate effect on circulating proangiogenic
growth factors were seen, although several patients exhibited persistent
declines in vascular endothelial growth factor levels while enrolled in the
study. A few patients demonstrated changes in their dynamic CT scans suggestive
of a decline in microvessel density, although overall, no consistent effect of
endostatin on tumor vasculature was seen.
CONCLUSION: Endostatin given daily as a 1-hour intravenous infusion was well
tolerated without dose-limiting toxicity at doses up to 300 mg/m2. The serum concentration of two pro-angiogenic cytokines: basic fibroblast growth
factor (bFGF) and transforming growth factor beta1 (TGF-beta1), and
anti-angiogenic factor endostatin in the serum of 80 never treated B-cell
chronic lymphocytic leukemia (CLL) patients and 27 healthy volunteers was
measured using an enzyme linked immunosorbent assay. The serum levels of both
bFGF and TGF-beta1 were found to be significantly higher in the CLL group
(median 40.5 pg/ml and 38.6 ng/ml respectively) when compared to the control
group (median 9.4 pg/ml and 18.9 ng/ml, respectively) (p<0.001). The levels of
endostatin were not significantly different in CLL and control groups (median
12.3 ng/ml and 8.4 ng/ml, respectively) (p=0.09). In the group of CLL patients
the level of bFGF was significantly higher in patients with progressive disease
as compared with patients with stable disease (median 90.5 pg/ml and 40.5 pg/ml
respectively) (p<0.001). Patients in Rai stage III and IV also had significantly
higher levels of bFGF than patients in Rai stage 0-II (median 100.1 pg/ml and
29.3 pg/ml respectively) (p<0.001). The levels of both TGF-beta1 and endostatin
were lower in patients in Rai stage III and IV (median 28.9 ng/ml and 9.1 ng/ml
respectively) than in patients in Rai stage 0-II (42.8 ng/ml and 13.1 ng/ml
respectively) (p<0.001 and p=0.002 respectively). The level of endostatin was
also lower in the group of CLL patients with progressive disease (median 10.0
ng/ml) as compared to patients with stable disease (median 20.5 ng/ml)
(p=0.008). In conclusion, the disturbance in the balance between pro- and
anti-angiogenic factors may have an important influence on the course of CLL. PURPOSE: Endostatin, a peptide derived from proteolysis of collagen XVIII, is an
endogenous inhibitor of angiogenesis and tumor growth. We have synthesized five
peptide fragments designed to cover the whole length of the endostatin molecule
(containing 40-50 amino acids each) with the aim of exploring the possibility
that a specific sequence within the molecule might be responsible for its
antiangiogenic effects.
EXPERIMENTAL DESIGN: The five peptide sequences, termed fragments I, II, III,
IV, and IVox, the latter bearing the original disulfide bond Cys(135)-Cys(165),
were investigated for their effects on cultured endothelial cells, on enzyme
activities related to angiogenesis, on tube formation in three-dimensional gel
matrices, in vivo in the avascular rabbit cornea assay, and in an experimental
tumor burden paradigm.
RESULTS: Both the fragment covering the COOH-terminal endostatin region,
fragment IV, and particularly fragment IVox, retained the angioinhibitory
effects of endostatin. Fragment IVox strongly inhibited endothelial cell
migration and proliferation, in vitro tube formation, and in vivo angiogenesis,
displaying a potency comparable with that of endostatin. When tested in vivo on
tumor growth, fragment IVox demonstrated to be more effective than full-length
endostatin. Unexpectedly, fragment III exhibited proangiogenic activity,
increasing endothelial cell migration, producing neovascularization to an extent
similar to that of vascular endothelial growth factor, and enhancing the
angiogenic response to vascular endothelial growth factor in the cornea assay.
Peptides encompassing the NH(2)-terminal region of endostatin (fragments I and
II) had negligible effects on angiogenesis.
CONCLUSIONS: In view of these results, which show strikingly distinct profiles
of endostatin fragments, we propose that the amino acid sequence of endostatin
contains both angiosuppressive and angiostimulatory domains. It is here demonstrated that the set of gene expressions underlying the
angiogenic balance in tissues can be molecularly reset en masse by a single
protein. Using genome-wide expression profiling, coupled with RT-PCR and
phosphorylation analysis, we show that the endogenous angiogenesis inhibitor
endostatin downregulates many signaling pathways in human microvascular
endothelium associated with proangiogenic activity. Simultaneously, endostatin
is found to upregulate many antiangiogenic genes. The result is a unique
alignment between the direction of gene regulation and angiogenic status.
Profiling further reveals the regulation of genes not heretofore associated with
angiogenesis. Our analysis of coregulated genes shows complex interpathway
communications in an intricate signaling network that both recapitulates and
extends on current understanding of the angiogenic process. More generally,
insights into the nature of genetic networking from the cell biologic and
therapeutic perspectives are revealed. Hepatocellular carcinoma (HCC) is regarded as a suitable target for
antiangiogenic strategies. However, antiangiogenic agents aimed at single
targets can be neutralized by upregulation of other proangiogenic factors.
Therefore, combined approaches addressing at least two angiogenic targets should
be more effective. Employing an appropriate rat hepatoma model, we examined the
effects of sFlt-1 (soluble vascular endothelial growth factor [VEGF] receptor 1
as an indirect inhibitor of angiogenesis) and endostatin (a direct inhibitor of
angiogenesis) in both single-agent as well as combined approaches under in vitro
and in vivo conditions. Similar to human HCC, rat Morris hepatoma (MH) cells
secreted high levels of VEGF, but no endogenous sFlt-1. Parental MH or MHES(r)
cells, stably expressing rat endostatin, were adenovirally transduced either
with AdsFlt-1 (encoding sFlt-1) or control vector Adnull (containing no
transgene), followed by subcutaneous inoculation into syngeneic ACI rats.
Compared with MH/Adnull cells, expressing no antiangiogenic factors at all,
tumor weights were reduced fourfold in the MHES(r)/Adnull group, 19-fold in the
MH/AdsFlt-1-group, and 77-fold in the MHES(r)/AdsFlt-1 combination therapy
group. Analysis of variance did not show a significant interaction between the
effects of the two factors ES(r) and sFlt-1; their effects multiplied. In
conclusion, combined expression of sFlt-1 and endostatin effectively suppresses
HCC growth under in vivo conditions. Supplementary material for this article can
be found on the HEPATOLOGY website
(http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html). The lysosomal protease cathepsin B has been implicated in a variety of
pathologies including pancreatitis, tumor angiogenesis, and neuronal diseases.
We used a tube formation assay to investigate the role of cathepsin B in
angiogenesis. When cultured between two layers of collagen I, primary
endothelial cells formed tubes in response to exogenously added VEGF.
Overexpressing cathepsin B reduced the VEGF-dependent tube response, whereas
pharmacologically or molecularly suppressing cathepsin B eliminated the
dependence on exogenous VEGF. However, tube formation still required VEGF
receptor activity, which suggested that endothelial cells generated VEGF.
Indeed, VEGF mRNA and protein was detectable in cells treated with cathepsin B
inhibitor, which correlated with a rise in the level of HIF-1alpha. In addition
to boosting the level of proangiogenic factors, blocking cathepsin B activity
reduced the amount of the antiangiogenic protein endostatin. Thus endothelial
cells have the intrinsic capacity to generate pro- and antiangiogenic agents.
These observations complement and expand our appreciation of how endothelial
cell-derived proteases regulate angiogenesis. Increased vessel density in the bone marrow of patients with acute myeloid
leukemia as well as elevated expression of proangiogenic factors by leukemic
cells implies a central role of angiogenesis in hematological maligcies.
Endostatin (ES), a fragment of collagen XVIII, is an endogenous inhibitor of
angiogenesis that has shown therapeutic activity in solid tumors in various
preclinical models. Using microencapsulation technology, we studied the
therapeutic effect of ES in AML. While ES had no effect on proliferation of M1
murine leukemic cells in vitro, ES producing microbeads significantly inhibited
growth of subcutaneous chloromas in SCID mice as compared to controls. In a
leukemia model using M1 cells the concomitant treatment of mice with ES
microbeads prolonged median survival significantly. Histological analysis
revealed a decreased microvessel density and a reduced number of CD31-positive
single cells, putatively endothelial progenitor cells, in the bone marrow of
treated animals. Taken together, ES has inhibitory effects on neo-angiogenesis
in the bone marrow and on progression of leukemia in vivo. These experiments
suggest a possible therapeutic role of antiangiogenic gene therapy with ES in
AML. The hypothesis that tumor growth and metastasis is angiogenesis-dependent was
proposed by Judah Folkman in 1971. Its major implication is that blocking
angiogenesis could be a strategy for arresting tumor growth. This hypothesis is
now supported by extensive experimental evidence, and hence the angiogenic
switch and microvascular endothelial cells recruited by the tumor have emerged
as important targets in cancer therapy. A large number of proangiogenic and
antiangiogenic factors have been discovered. At least three angiogenesis
inhibitors have received FDA approval in the US, with Avastin
(anti-VEGF-antibody) also approved in 26 other countries. The recognition that
antiangiogenic therapy is becoming the fourth therapeutic modality in addition
to surgery, chemotherapy and radiotherapy underlines the urgent need to
understand the systems biology of the antiangiogenic response. A particularly
important question for cancer therapy is whether antiangiogenic therapy will
also face the same drug resistance as one sees with other treatment modalities.
Recently, the cellular signaling induced by the endogenous angiogenesis
inhibitor - endostatin - was dissected revealing that the antiangiogenic
response is characterized by a large number of individual genetic signals, which
are highly coordinated and interdependent. The objective of this review is to
elucidate the multifaceted nature of tumor angiogenesis, and to discuss the
subtle but important distinctions that exist between variations in tumor
responsiveness that evolve with antiangiogenic therapy and the classic
resistance that frequently develops with conventional therapy. Furthermore, this
review discusses the implications of current findings for cancer treatment and
potential ways of overcoming or predicting tumor resistance to these agents. Peritoneal sclerosis is a major and serious complication in patients on
long-term continuous ambulatory peritoneal dialysis (PD). The involvement of
angiogenesis and proangiogenic factors such as vascular endothelial growth
factor (VEGF)-A in progressing peritoneal sclerosis has been reported. We
previously reported the therapeutic efficacy of endostatin peptide, a potent
inhibitor of angiogenesis derived from type XVIII collagen, in a mouse diabetic
nephropathy model. Here, we examined the therapeutic effect of endostatin
peptide in preventing progression in a mouse peritoneal sclerosis model. Male
ICR mice received intraperitoneal injections of chlorhexidine gluconate (CG)
every other day to induce peritoneal sclerosis. Endostatin peptide (1 or 4
mg/kg/day) was administered via subcutaneously implanted osmotic minipumps.
Peritoneal sclerosis (day 24) was significantly suppressed by endostatin peptide
in a dose-dependent manner. Peritoneal accumulation of type III collagen was
significantly suppressed by endostatin peptide. Increase in the number of
CD31(+) blood vessels, F4/80(+) monocyte/macrophage accumulation, and
5-bromodeoxyuridine(+) proliferating cells was significantly inhibited by
endostatin peptide. Increase in peritoneal expression of VEGF-A, profibrotic
transforming growth factor-beta1, and alpha-smooth muscle actin was suppressed
by endostatin peptide. Immunoreactivity for endogenous endostatin (whole
molecule) and endostatin receptor alpha5beta1-integrin was increased and
colocalized to CD31(+) blood vessels in the thickened peritonea of CG-injected
mice. These results demonstrate the potential use of antiangiogenic endostatin
peptide as a novel therapeutic agent in preventing peritoneal sclerosis, a
severe complication in patients undergoing long-term PD. PURPOSE: To determine the molecular basis of corneal avascularity during wound
healing and determine the role of angiogenic and antiangiogenic factors in
corneal vasculogenesis.
METHODS: The expression of proangiogenic factors (vascular endothelial growth
factor [VEGF]; basic fibroblast growth factor [bFGF]; matrix metalloproteinase-2
[MMP-2]; and membrane-type 1-MMP [MT1-MMP]) and antiangiogenic factors (pigment
epithelium-derived factor [PEDF]; angiostatin; restin; and endostatin) was
analyzed in avascular corneas and in models of corneal neovascularization (bFGF
pellet implantation, intrastromal injection of MT1-MMP cDNA, and surgically
induced partial limbal deficiency).
RESULTS: Immunohistochemistry demonstrated the presence of antiangiogenic
factors (PEDF, angiostatin, restin, and endostatin) and proangiogenic molecules
(VEGF, bFGF, MMP-2, and MT1-MMP) in the cornea after wounding. Proangiogenic
MMPs were upregulated in stromal fibroblasts in the vicinity of invading vessels
following bFGF pellet implantation. Corneal neovascularization (NV) was also
induced by intrastromal injection of MT1-MMP naked cDNA in conjunction with
de-epithelialization. Partial limbal deficiency (HLD-) resulted in corneal NV in
MMP-7 and MMP-3 knockout mice but not in wild type controls.
CONCLUSIONS: Corneal angiogenic privilege is an active process involving the
production of antiangiogenic factors to counterbalance the proangiogenic factors
(which are upregulated after wound healing even in the absence of new vessels).
Our finding that the potent antiangiogenic factors, angiostatin and endostatin,
are colocalized with several MMPs during wound healing suggests that MMPs may be
involved in the elaboration of these antiangiogenic molecules by proteolytic
processing of substrates within the cornea. AIM: To evaluate expression of proangiogenic matrix metalloproteinases (MMP) 2
and 9 at distinct intervals after verteporfin photodynamic therapy (PDT) in
human choroidal neovascular membranes (CNV) secondary to age-related macular
degeneration (AMD).
METHODS: Retrospective review of an interventional case series of 49 patients
who underwent removal of CNV. Twenty-six patients were treated with PDT 3 to 383
days prior to surgery. Twenty-three CNV without previous treatment were used as
controls. CNV were stained for CD34, cytokeratin 18, endostatin, MMP-2 and MMP-9
by immunohistochemistry.
RESULTS: CNV without previous therapy disclosed MMP-2, MMP-9 in RPE-Bruch's
membrane, vessels and stroma in different intensities. Three days after PDT,
MMP-9 expression was significantly weaker in stroma (p = 0.0019). Endostatin was
significantly reduced in vessels (p<0.001). At longer post-PDT intervals, a
significant increase of MMP-9 in stroma (p = 0.037) and of endostatin in
RPE-Bruch's membrane (p = 0.02), vessels (p = 0.005) and stroma (p<0.001) were
disclosed. No significant changes in MMP-2 expression were detected.
CONCLUSIONS: PDT induced an early, temporary decrease in MMP-9 and endostatin
expression. At longer intervals, MMP-9 increase is possibly associated with the
angiogenic process responsible for recurrence after PDT. MMP-9, however, acts as
a double-edged sword by concomitant induction of endostatin, an endogenous
inhibitor of angiogenesis. PURPOSE: Circulating and cellular proangiogenic and antiangiogenic proteins such
as vascular endothelial growth factor (VEGF) and endostatin contribute to the
local angiogenic balance. We explored the effects of tamoxifen and aromatase
inhibitors on concentrations of VEGF and endostatin in plasma, serum, and
platelet releasate (induced by platelet activation).
EXPERIMENTAL DESIGN: VEGF and endostatin concentrations were measured with a
quantitative immunoassay before and after 1 to 5 weeks of treatment in 30 women
with breast cancer treated with either tamoxifen (n = 14) or aromatase
inhibitors (n = 16). Platelet activation was induced by a thrombin receptor
agonist.
RESULTS: Tamoxifen therapy resulted in an increase in platelet releasate
concentrations of VEGF (P = 0.01) but no change in plasma VEGF. In contrast,
aromatase inhibitor therapy did not affect serum, plasma, or platelet releasate
VEGF. In univariate analysis, aspirin use attenuated the tamoxifen-associated
increase in VEGF in the platelet releasate and decreased serum levels of VEGF (P
= 0.03). Aromatase inhibitor therapy resulted in a decrease in serum endostatin
concentrations (P = 0.04), whereas plasma concentrations of endostatin tended to
be higher during treatment with aromatase inhibitors (P = 0.06). Tamoxifen
therapy resulted in no change in serum or plasma endostatin concentrations.
Platelet releasate concentrations of endostatin did not change with either
treatment. Interindividual variability was noted among both aromatase
inhibitor--and tamoxifen-treated patients.
CONCLUSIONS: Tamoxifen and aromatase inhibitor therapy affect VEGF and
endostatin levels and likely contribute to the angiogenic balance in breast
cancer patients. Aspirin decreased the proangiogenic effects of tamoxifen,
suggesting that antiplatelet and/or antiangiogenic therapy might improve the
effectiveness of tamoxifen in women with breast cancer. INTRODUCTION: Endostatin is an antiangiogenic growth factor. Together with
proangiogenic growth factors it acts to shape the developing vasculature.
Dysregulation of angiogenesis is a component in the pathogenesis of
bronchopulmonary dysplasia.
OBJECTIVE: Our goal was to study whether the concentration of circulating
endostatin at birth is associated with the development of bronchopulmonary
dysplasia in very low birth weight infants.
PATIENTS AND METHODS: Endostatin concentration was measured in cord plasma from
92 very low birth weight infants (gestational age < 32 weeks; birth weight <
1500 g) and 48 healthy term infants (gestational age > 37 weeks; birth weight >
2500 g).
RESULTS: Endostatin concentration in very low birth weight infants was lower
than in healthy term infants. Within the very low birth weight group no
correlation existed between endostatin concentration and gestational age or
relative birth weight. Very low birth weight infants who subsequently developed
bronchopulmonary dysplasia had higher cord endostatin than those who did not.
Higher endostatin concentration was associated with higher odds for
bronchopulmonary dysplasia. Adjusted for gestational age, the odds for
bronchopulmonary dysplasia were higher.
CONCLUSIONS: Circulating endostatin in term infants was higher than in very low
birth weight infants, suggesting a temporal pattern for fetal endostatin
concentration. In very low birth weight infants a high concentration of
circulating endostatin at birth is associated with the subsequent development of
bronchopulmonary dysplasia. Diabetic retinopathy is considered one of the vision-threatening diseases among
working-age population. The pathogenesis of the disease is regarded
multifactorial and complex: capillary basement membrane thickening, loss of
pericytes, microaneuryms, loss of endothelial cells, blood retinal barrier
breakdown and other anatomic lesions might contribute to macular edema and/or
neovascularization the two major and sight threatening complications of diabetic
retinopathy. A number of proangiogenic, angiogenic and antiangiogenic factors
are involved in the pathogenesis and progression of diabetic retinal disease,
Vascular Endothelial Growth Factor (VEGF) being one of the most important. Other
growth factors, which are known to participate in the pathogenesis of the
disease, are: Platelet Derived Growth Factor (PDGF), Fibroblast Growth Factor
(FGF), Hepatocyte Growth Factor (HGF), Transforming Growth Factor (TGF),
Placental Endothelial Cell Growth Factor (PlGF), Connective Tissue Growth Factor
(CTGF). Other molecules that are involved in the disease mechanisms are:
intergrins, angiopoietins, protein kinase C (PKC), ephrins, interleukins,
leptin, angiotensin, monocyte chemotactic protein (MCP), vascular cell adhesion
molecule (VCAM), tissue plasminogen activator (TPA), and extracellular matrix
metalloproteinases (ECM-MMPs). However, the intraocular concentration of
angiogenic factors is counterbalanced by the ocular synthesis of several
antioangiogenic factors such as pigment epithelial derived factor (PEDF),
angiostatin, endostatin, thrombospondin, steroids, atrial natriuretic peptide
(ANP), inteferon, aptamer, monoclonal antibodies, VEGF receptor blocker, VEGF
gene suppressors, intracellular signal transduction inhibitors, and
extracellular matrix antagonists. Growth stimulation or inhibition by these
factors depends on the state of development and differentiation of the target
tissue. The mechanisms of angiogenesis factor action are very different and most
factors are multipotential; they stimulate proliferation or differentiation of
endothelial cells. This review attempts to briefly outline the knowledge about
peptide growth factor involvement in diabetic retinopathy. Further ongoing
research may provide better understanding of molecular mechanisms, disease
pathogenesis and therapeutic interactions. Alzheimer's disease (AD) is the most common form of dementia among the aging
population and is characterized pathologically by the progressive intracerebral
accumulation of beta-amyloid (Abeta) peptides and neurofibrillary tangles. The
level of proangiogenic growth factors and inflammatory mediators with
proangiogenic activity is known to be elevated in AD brains which has led to the
supposition that the cerebrovasculature of AD patients is in a proangiogenic
state. However, angiogenesis depends on the balance between proangiogenic and
antiangiogenic factors and the brains of AD patients also show an accumulation
of endostatin and Abeta peptides which have been shown to be antiangiogenic. To
determine whether angiogenesis is compromised in the brains of two transgenic
mouse models of AD overproducing Abeta peptides (Tg APPsw and Tg PS1/APPsw
mice), we assessed the growth and vascularization of orthotopically implanted
murine gliomas since they require a high degree of angiogenesis to sustain their
growth. Our data reveal that intracranial tumor growth and angiogenesis is
significantly reduced in Tg APPsw and Tg PS1/APPsw mice compared with their
wild-type littermates. In addition, we show that Abeta inhibits the angiogenesis
stimulated by glioma cells when cocultured with human brain microvascular cells
on a Matrigel layer. Altogether our data suggest that the brain of transgenic
mouse models of AD does not constitute a favorable environment to support
neoangiogenesis and may explain why vascular insults synergistically precipitate
the cognitive presentation of AD. Cathepsin L enhances angiogenesis by increasing extracellular matrix degradation
and remodelling. This study investigated whether plasma cathepsin L could be
used as a biomarker to predict collateral formation in patients with coronary
heart disease (CHD). Patients with CHD (n = 218; aged 67 ± 11 years) underwent
coronary angiography and were categorized as having either 'poor' or 'rich'
collaterals. Plasma cathepsin L, the proangiogenic placenta growth factor (PLGF)
and the antiangiogenic factors, cystatin C and endostatin, were measured.
Elevated cathepsin L and PLGF levels were independently and significantly
associated with enhanced collateral formation in patients with CHD; subgroup
analyses also showed a significant correlation in patients with diabetes and
acute coronary syndrome. Plasma endostatin and cystatin C levels were not
significantly correlated with coronary collateral formation. Plasma cathepsin L
and PLGF, acting as important modulators of angiogenesis, could be used as
biomarkers to predict coronary collateral formation in patients with CHD. INTRODUCTION: Angiostatin and endostatin are endogenous inhibitors of
angiogenesis with anticancer effects. After minimally invasive colorectal
resection (MICR), blood levels of the proangiogenic factors vascular endothelial
growth factor (VEGF) and angiopoetin 2 (Ang-2) are elevated for 2-4 weeks. Also,
postoperative human plasma from weeks 2 and 3 after MICR has been shown to
stimulate endothelial cell proliferation and migration, which are critical to
angiogenesis. This proangiogenic state may stimulate tumor growth early after
MICR. Surgery's impact on angiostatin and endostatin is unknown. This study's
purpose is to determine perioperative plasma levels of these two proteins in
colorectal cancer (CRC) patients undergoing MICR.
METHODS: Endostatin levels were assessed in 34 CRC patients and angiostatin
levels in 30 CRC patients. Blood samples were taken preoperatively and on
postoperative day (POD) 1 and 3 in all patients; in a subset, samples were taken
between POD 7 and 20. The late samples were bundled into 7-day blocks (POD 7-13,
POD 14-20) and considered as single time points. Angiostatin and endostatin
plasma levels were determined via enzyme-linked immunosorbent assay (ELISA) in
duplicate. Wilcoxon signed-rank test and Student's t test were used to analyze
endostatin and angiostatin data, respectively. Significance was set at P<0.0125
(after Bonferroni correction).
RESULTS: There was a significant decrease in median plasma endostatin levels on
POD 1, which returned to the preoperative level by POD 3. There was no
significant difference between pre- and postoperative plasma angiostatin levels.
CONCLUSIONS: MICR has a very transient impact on plasma levels of endostatin and
no impact on angiostatin during the first 21 days following surgery. Thus,
angiostatin and endostatin do not likely contribute to or inhibit the persistent
proangiogenic changes noted after MICR. Recombit human endostatin (rh-endostatin), a potential antiangiogenic agent,
is used in non-small cell lung carcinoma treatment and represses vascular
endothelial cell growth factor (VEGF) levels in tumor cell. However, precise
affection of rh-endostatin on the proangiogenic VEGF isoforms (VEGF(165)) or
antiangiogenic VEGF isoforms (VEGF(165)b) is not clear. We therefore tested the
hypothesis that rh-endostatin could alter expression of these isoforms to
regulate tumor growth. A549 cells were exposed to rh-endostatin, and the
expression of VEGF(165) and VEGF(165)b was detected. The role of SP1 as a
regulator of isoform expression was investigated. We then examined the
anticancer and antiangiogenic efficacy of rh-endostatin in combination with
exogenous VEGF(165)b against A549 cells, EA.HY 926 cells and xenograft model of
human lung cancer. rh-Endostatin reduced VEGF(165) and induced VEGF(165)b as
well as inhibited SP1 in A549 cells. SP1 inhibitor (betulinic acid) also
developed those changes. VEGF(165)b-rh-endostatin combination was highly
synergistic and inhibited growth, survival, and migration of A549 cells,
VEGF-mediated VEGFR2 phosphorylation in EA.HY 926 cells, and tumor growth in
xenograft model of human lung cancer. rh-Endostatin downregulates proangiogenic
vascular endothelial growth factor A (VEGFA) isoform and upregulates
antiangiogenic VEGFA isoform, possibly through inhibition of SP1. Furthermore,
VEGF(165)b sensitizes A549 to rh-endostatin treatment and enhances the
anticancer effect of rh-endostatin. Angiogenesis is regulated by the highly coordinated function of various proteins
with pro- and antiangiogenic functions. Proangiogenic factors include vascular
endothelial growth factor (VEGF), fibroblast growth factor, platelet-derived
growth factor, insulin-like growth factor, transforming growth factor,
angiopoietins, and several chemokines; antiangiogenic factors include
thrombospondin-1, angiostatin, and endostatin. Matrix metalloproteinases display
a dual role in vascular development. Notch signaling affects remodeling of the
primary vascular network of uniformly sized vessels into functionally and
morphologically distinct arteries, veins, and capillaries. Tumors, described as
'wounds that never heal', lose the appropriate balance among these factors.
Although VEGF-targeted therapies are showing promise, new angiogenesis targets
are needed to make additional gains. Here, we highlight recent advances in our
understanding of the regulation of tumor angiogenesis and discuss the potential
of molecular targeting as a new therapeutic approach. Gastric mucosa of aging individuals exhibits increased susceptibility to injury
and delayed healing. Our previous studies in young rats showed that healing of
mucosal injury depends on and is critically dependent on VEGF and angiogenesis.
Since angiogenesis in aging gastric mucosa has not been examined before, in this
study we examined the extent to which angiogenesis is impaired in gastric mucosa
of aging vs. young rats and determined the underlying mechanisms with a focus on
mucosal expression of VEGF (proangiogenic factor) and endostatin (antiangiogenic
factor). Aging rats had significantly impaired gastric angiogenesis by ~12-fold,
5-fold, 4-fold, and 3-fold, respectively (vs. young rats; all P < 0.001) at 24,
48, 72, and 120 h following ethanol-induced gastric injury and reduced and
delayed healing of mucosal erosions. In gastric mucosa of aging (vs. young) rats
at baseline, VEGF expression was significantly reduced, whereas endostatin
levels were significantly increased (P < 0.05 and P < 0.01, respectively). In
contrast to young rats, gastric mucosal VEGF levels did not increase following
ethanol-induced injury in aging rats. MMP-9 enzyme activity was significantly
higher in gastric mucosa of aging vs. young rats both at baseline (2.7-fold) and
24 h (3.8-fold) after ethanol injury (both P < 0.001). Since endostatin is
generated from collagen XVIII by MMP-9, this finding can explain the mechanism
of increased endostatin expression in aging gastric mucosa. The above findings
demonstrate that reduced VEGF and increased endostatin result in the impaired
angiogenesis and delayed injury healing in gastric mucosa of aging rats. |
List Genes associated with adolescent idiopathic scoliosis | Exome Sequencing Identifies a Rare HSPG2 Variant Associated with Familial Idiopathic Scoliosis.Overall, these findings demonstrate a novel role for kif6 in spinal development and identify a new candidate gene for human idiopathic scoliosis. | The etiology of idiopathic scoliosis remains unknown. The condition results in a
characteristic deformity of the spine and surrounding tissues. Both Types I and
II collagen are important constituents of the affected tissues, and thus
defective collagens are reasonable candidates for the primary abnormality in
adolescent idiopathic scoliosis (AIS). Direct analyses of the amount and
solubility of collagen have revealed differences between normal individuals and
those with AIS. However, these changes may be secondary to the mechanical
effects of the spinal deformity. Segregation analysis was done of genetic
markers linked to the structural genes encoding Types I and II collagen to test
these candidate loci in four pedigrees with domitly inherited AIS. In one
pedigree, markers linked to both of the Type I collagen loci (COL1A1 and COL1A2)
were found to be inherited independently of the abnormal phenotype. Two
pedigrees were discordant at one of the Type I loci. The condition also
segregated independently of the locus for Type II collagen (COL2A1) in three
pedigrees. This is evidence against idiopathic scoliosis generally being caused
by mutations in the Types I and II collagen genes. The diversity of hereditary pathology in 5 regions of Kostroma district was
studied. 32 nosological forms of autosomal domit, 30 autosomal recessive and
7 X-linked recessive disorders were found. The most frequent autosomal domit
disorders were: neurofibromatosis, pigmentary degeneration of retina,
hypochondroplasia, ichtiosis, idiopathic scoliosis. The most frequent among the
autosomal recessive disorders were: oligophrenia, pigmentary degeneration of
retina, muscular atrophy of juvenile Kugelberg--Welander type, congenital
cataract. The most frequent X-linked disorders were: muscular Duchenne type
dystrophy and hemophilia A. Analysis of mutant gene distribution over the
territory by the study of birthplaces of probands and their parents was carried
out. The Marfan syndrome is an autosomal domit disorder with pleiotropic
manifestations that involve the cardiovascular, ocular, and skeletal systems.
Through a number of investigational approaches, the gene encoding for fibrillin,
the FBN1 gene on chromosome 15, has been identified as the defective gene
causing the Marfan syndrome. Fibrillin is the large glycoprotein with a
repetitive domain structure and is a major protein component of microfibrils, a
fibrillar system closely associated with elastin in connective tissue.
Mutational analysis of defects in the FBN1 gene in patients with the Marfan
syndrome has revealed that most mutations are private or unique in an affected
individual or family. Analysis of fibrillin protein or gene defects in
individuals with related phenotypes has revealed that a perinatal lethal
syndrome, termed neonatal Marfan syndrome, is due to FBN1 gene mutations. In
addition, fibroblast cell strains from a subset of patients with idiopathic
scoliosis have fibrillin protein defects. Last, fibroblasts from calves affected
with bovine Marfan syndrome display defects in the fibrillin protein. These
studies have wide-ranging implications in the diagnosis, treatment, and
prevention of Marfan syndrome and related disorders. Adolescent idiopathic scoliosis is a genetic disorder of unknown etiology.
Scoliosis is a clinical feature of inherited connective-tissue disorders
including Marfan syndrome. Mutations within the gene of FBN1 (fibrillin 15), a
component of the extracellular matrix, are now linked to Marfan syndrome and
similar clinical phenotypes. This study investigated the potential association
of structural genes encoding for extracellular matrix components of FBN1,
elastin, and one of the polypeptides of type-I collagen (COL1A2) with familial
adolescent idiopathic scoliosis. Eleven pedigrees, including 96 individuals,
were identified in which adolescent idiopathic scoliosis segregated in an
apparent autosomal domit pattern. Fifty-two individuals were determined to be
affected with scoliosis. Genomic DNA was analyzed by genetic linkage utilizing
four intragenic markers for the structural genes of FBN1, elastin, and COL1A2.
Collectively, our results exclude the structural genes of FBN1, elastin, and
COL1A2 as candidate genes within these families. However, when viewed
individually, specific markers cannot be excluded within all of the families.
This information complements previously reported data that fibrillin production
and matrix incorporation from scoliotic fibroblasts in vitro are normal in more
than 80% of patients studied. Idiopathic scoliosis (IS) is a common but poorly understood syndrome. Congenital
scoliosis (CS) is less common but comparably unexplored. Previous studies
suggest that each has a significant genetic component. However, the occurrence
of scoliosis in the presence of other hereditary connective tissue syndromes
raises the possibility that IS and CS are in fact a heterogeneous group of
disorders with varied pathogenetic mechanisms. Mouse mutations have proven
informative in identifying genes that are important in the development of the
musculoskeletal system and provided important mechanistic insights regarding
their roles in human disease. We sought to identify candidate genes for human IS
and CS by reviewing mouse mutations with phenotypes affecting the axial
skeleton. We performed a systematic review using the Mouse Genome Database
(MGD), the Genome Database (GDB), and the Online Mendelian Inheritance in Man
(OMIM) world-wide-web sites with additional searches performed based on the
results of this initial search. We identified approximately 400 mouse mutations,
reviewed approximately 250 of these for vertebral phenotypes, assessed 45 of
these for synteny conservation between mouse and man, and identified 28 mouse
mutations for which 29 credible candidates for human scoliosis could be
identified based on mouse phenotypic and mapping data. For each of these, we
have synthesized information about the mouse mutant phenotype, mapping data,
information regarding molecular pathogenesis when a specific causative gene has
been identified, and information regarding plausible candidates based on map
position when the causative gene has not been identified. Among these were three
loci for which the mutant gene had been identified and the human homologue was
known. Some of the mouse mutants have phenotypes similar to human syndromes. Patients with Duchenne muscular dystrophy (DMD) tend to bleed more during
surgery than do patients with other conditions. A retrospective analysis of
blood loss after spinal surgery for scoliosis was therefore undertaken in 102
patients undergoing surgery in the senior author's unit. These included 48
patients with DMD, 26 patients with spinal muscular atrophy, and a miscellaneous
group of 28 other patients most of whom had idiopathic scoliosis. For each
patient the age at surgery, estimated blood volume, duration of operation, Cobb
angle, and number of vertebrae fused were recorded and compared. Expression of
dystrophin in skeletal muscle and the underlying gene mutation were also
determined. The estimated blood loss in patients with DMD was significantly
higher than that in patients with spinal muscular atrophy undergoing the same or
similar procedure (P < 0.005) and was also significantly greater than that of
the third group, which consisted mostly of patients with idiopathic scoliosis (P
< 0.0005). Blood loss in the patient group with DMD showed a significant
relationship with duration of surgery (P < 0.05). As most patients expressed no
dystrophin, this did not correlate with the estimated blood loss. There was also
no correlation between the estimated blood loss and the type of gene mutation
found causing DMD. The authors' previous observations confirm the increased
blood loss in patients with DMD who undergo scoliosis surgery. Because children
with DMD lack dystrophin in all muscle types, including smooth muscle, the
excessive blood loss may be because of a poor vascular smooth muscle
vaso-constrictive response due to a lack of dystrophin. Segregation analysis using a model with age and gender effects was applied to
101 pedigrees ascertained through a proband with idiopathic scoliosis. The
transmission probability model was used to detect major gene effect. When we
analyzed the pedigrees where affected status was assigned to persons with a
Cobb's angle of more than 5 degrees we did not detect a significant major gene
effect. However, when the affected status was assigned to persons with
pronounced forms of disease only (a curve of at least 11 degrees) a significant
contribution of a major causal gene could be established and inheritance could
be described according to a domit major gene diallele model, assuming
incomplete sex and age dependent penetrance of genotypes. According to this
model, the pronounced forms of idiopathic scoliosis should never occur in the
absence of the mutant allele. This indicates that only the carriers of the
mutant allele develop pronounced forms of the disease. At the same time, only a
fraction of the carriers of the mutant gene should manifest the disease (30% of
males and 50% of females). Scheuermann disease [OMIM number 181440] is the most common cause of structural
kyphosis in adolescence. Segregation analysis using a model with gender effects
was applied to 90 pedigrees from Barnaul (West Siberia, Russia) ascertained
through a proband with Scheuermann disease. The transmission probability model
was used to detect major gene effect. A significant contribution of a major gene
to the control of the pathology was established. Inheritance of the disease can
be described within the framework of a domit major gene diallele model.
According to this model, Scheuermann disease should never occur in the absence
of the mutant allele. All male carriers of the mutant allele develop the
disease, while only a half of female carriers manifest it. We found a high
frequency of idiopathic scoliosis in the families with Scheuermann disease (0.08
vs. 0.01-0.02 in general population). We also observed a succession of
idiopathic scoliosis and Scheuermann disease in consecutive generations. The
familial aggregation of these two spinal pathologies in the present sample may
indicate a genetic unity of Scheuermann disease and idiopathic scoliosis. Idiopathic scoliosis (IS) is a spine deformity of unknown etiology. Family
studies have suggested that IS may be inherited as a mendelian autosomal
domit trait. We have performed linkage analysis on a three-generation IS
Italian family. A positive LOD score value of 3.20 at theta=0.00 was detected
with marker D17S799 after a genome-wide scanning. Analysis of six flanking
microsatellites confirmed the linkage and haplotype inspection defined an
interval of about 20 cM between D17S947 and D17S798. This is the first locus
reported for IS. We scored genes mapping in this interval and studied the
heparan sulfotransferase genes as candidates on the basis of their biochemical
role. No causative mutation was detected in the affected patients. Idiopathic scoliosis (IS) affects approximately 2%-3% of the population and has
a heritable component. The genetics of this disorder are complex. Here, we
describe a family in which a pericentric inversion of chromosome 8 co-segregates
with IS. We have used fluorescence in situ hybridization to identify cloned DNAs
that span the breakpoints on the two arms of the chromosome. We have identified
a bacterial artificial chromosome (BAC) of 150 kb that crosses the q-arm
breakpoint and a BAC of 120 kb that crosses the p-arm breakpoint. The complete
genomic DNA sequence of these BACs has been analyzed to identify candidate genes
and to localize further the precise breakpoints. This has revealed that the
p-arm break does not interrupt any known gene and occurs in a region of highly
repetitive sequence elements. On the q-arm, the break occurs between exons 10
and 11 of the gamma-1 syntrophin (SNTG1) gene. Syntrophins are a group of
cytoplasmic peripheral membrane proteins that associate directly with
dystrophin, the Duchenne muscular dystrophy gene; gamma1-syntrophin has been
shown to be a neuronal cell-specific protein. Mutational analysis of SNTG1 exons
in 152 sporadic IS patients has revealed a 6-bp deletion in exon 10 of SNTG1 in
one patient and a 2-bp insertion/deletion mutation occurring in a polypyrimidine
tract of intronic sequence 20 bases upstream of the SNTG1 exon 5 splice site in
two patients. These changes were not seen in a screen of 480 control
chromosomes. Genomic DNAs from seven affected individuals within the family of a
patient carrying the 6-bp deletion were typed to determine whether the
alteration co-segregated with IS. The deletion was only observed in five out of
these seven individuals. Thus, although genetic heterogeneity or multiple
alleles cannot be ruled out, the 6-bp deletion does not consistently
co-segregate with the disease in this family. STUDY DESIGN: A cohort of 145 patients with adolescent idiopathic scoliosis
(AIS) were identified and contacted to determine whether they had a family
history of scoliosis. These results were submitted to an internal genealogical
database to screen for potential connections to other AIS families. The severity
and incidence of AIS in extended family groups were also analyzed.
OBJECTIVES: Our objectives were to quantify the genetic effect in AIS, determine
the expressivity and penetrance of AIS in large family groupings, and examine
larger scoliosis pedigrees for evidence of multiple genes.
SUMMARY OF BACKGROUND DATA: Previous reports have suggested an 80% connectedness
among scoliosis families, but no clear evidence of multiple genes. It is not
known if there are major gene(s).
METHODS: A cohort of 145 AIS probands were identified and contacted to ascertain
whether they had a family history of AIS. Their medical records and spine
radiographs were reviewed to confirm the diagnosis and determine the disease
severity. Using an internal genealogical database, the cases were screened for
potential connections that would produce larger extended pedigrees.
RESULTS: Overall, 131 of the probands were in the database and 127 showed
connections to other scoliosis families, a 97% connectedness. These results
suggest a major scoliosis gene, as more than 50% of the probands were connected
by founders that all resided in England in the mid 1500s. The differences in
penetrance (41% vs. 34%) and expressivity (38% vs. 61%) between seemingly
unrelated large family groupings might suggest that two different genes are a
major influence for AIS in these families.
CONCLUSIONS: Nearly all (97%) AIS patients have familial origins. There appears
to be at least one major gene, and the differences in penetrance and
expressivity in two large unconnected pedigrees might suggest the presence of
more than one gene. Many studies have demonstrated the role of melatonin in the etiology of AIS.
Previous studies have shown that there is no evidence of mutations in the
melatonin receptor 1A gene in AIS patients. In this study, we have examined the
role of melatonin receptor 1B in predisposition for AIS. Using haplotype block
tagging technique, a set of tagging SNPs were defined for MTNR1B from the Han
Chinese data of the International HapMap project. The association between the
tagging of single nucleotide polymorphisms (tSNPs) in MTNR1B region and the
occurrence of AIS was studied.
METHOD: 473 AIS girls and 311 normal controls were recruited. The age range of
the patients was between 10 and 18 years old. The maximum Cobb was recorded at
latest follow-up in AIS patients. Three of five tSNPs were studied; they were
all located within the coding region of the MTNR1B gene.
RESULTS: There was no significant difference in the genotype or allelic
frequencies (AF) of the 3 tSNPs between AIS and controls. In a case-only
analysis, no difference in curve severity in AIS patients was found among
patients with different genotypes (by one-way ANOVA).
DISCUSSION: The 3 tSNPs showed no association with either the occurrence of AIS
or the maximum Cobb angle within AIS girls. Further analysis of the remaining
tSNPs within the regulatory region of the MTNR1B gene and other related genes in
the melatonin signaling pathway may provide further information on the role of
the melatonin in AIS girls. IGF-I has a pivotal role in bone growth and could be one of the putative
disease-modifier genes in AIS. Two SNPs in IGF-I gene promoter region were
studied for any association with occurrence of AIS and for their effect on the
curve severity among AIS.
METHODS: 506 AIS girls (Cobb>20 degrees) and 227 age-matched Chinese girls were
recruited. The spine (L2-L4) and hip BMD of the subjects were measured by DXA. A
subgroup of AIS patients (N=340) who were followed-up to skeletal maturity and
the maximum Cobb's angle was recorded. Two SNPs were genotyped by PCR-RFLP
(rs5742612 and rs2288377). The chi-square test and one-way ANOVA were used to
test the association between genotypes and quantitative parameters,
respectively.
RESULTS: No association was between the genotypes and the occurrence of AIS and
the BMD of the spine and hip. The allelic frequency of T allele was 0.69 in AIS
and control. However, the Cobb's angle was higher in patients with the
homozygous T allele (Mean Cobb's angle: 38.1 degrees in TT vs 35.9 degrees in TC
vs 33.2 degrees in CC group; p=0.04).
DISCUSSION: Interestingly, IGF-I polymorphism affects the curve severity of AIS
though it was not associated with onset of AIS per se. It indicates that IGF-I
may be a disease modifying gene. The importance of IGF-I in skeletal growth
makes it a good candidate gene which would play a role in the documented
association of rapid growth with curve progression in AIS. In order to explore the concept that scoliosis is fundamentally a loss of
left-right symmetry. surface topography was used to measure asymmetry in three
dimensions at three levels on the back surface. Statistical analysis of
prospectively collected topographic, radiographic and clinical data, in girls
with adolescent idiopathic scoliosis, was carried out and comparisons were made
with theoretically perfect symmetry (test value of zero). All scoliosis showed
statistically significant differences in coronal dimensions, index points on the
convex side of the scoliosis being further from the mid-line than those on the
concave side. Primary thoracic scoliosis differed from thoracolumbar and lumbar
in that they showed directional asymmetry at all levels and in all directions,
the side of the scoliosis convexity being broader, taller and thicker. This
asymmetry is not due to posture, spinal balance or trunk rotation, as left and
right sides are being compared independently of their orientation in space. The
asymmetry is of size in three dimensions and size is determined by growth.
Growth is a three dimensional process, but does not necessarily occur equally in
all three. Differential growth is both directional and regional, particularly
during the pubertal growth spurt, when proportions change substantially, and is
controlled by many genes, as well as by hormones and signalling molecules. The
implication is that scoliotic deformity is the result of asymmetric growth, not
confined to the vertebrae, but affecting the entire trunk. This is a
developmental, rather than pathological, phenomenon. It makes questions of
aetiology redundant and natural history logical. The detection of anomalous extra-spinal left-right skeletal length asymmetries
in the upper limbs, periapical ribs, ilia and lower limbs of subjects with
adolescent idiopathic scoliosis (AIS) raises questions about skeletal bilateral
symmetry of vertebrates in health and disorder, its origin and control. The
vertebrate body plan externally has mirror-image bilateral symmetries that are
highly conserved culminating in the adult form. The normal human body can be
viewed as containing paired skeletal structures in the axial and appendicular
skeleton as 1) separate left and right paired forms (eg long limb bones, ribs,
ilia), and 2) united in paired forms (eg vertebrae, sternum, skull, mandible).
Each of these separate and united pairs are mirror-image forms--etiomorphs.
Left-right asymmetries of growth plates (physes) may cause (1) in long bones
length asymmetries, (2) within one or more vertebral physes putative growth
conflict with distortion as deformity, and (3) between ribs and vertebrae
putative growth conflict that triggers thoracic AIS suggesting preventive
surgery on spine and ribs. There is evidence of a possible role for
environmental factors in AIS development. Genes and the environment
(nature/nurture) may interact pre- and/or post-natally to explain both the
deformity of AIS and its association with widespread anomalous skeletal length
asymmetries. If substantiated there may ultimately be a place for the prevention
of AIS in some subjects. STUDY DESIGN: A genetic association study to comprehensively investigate
variations of melatonin receptor 1B gene polymorphism by a set of tagging single
nucleotide polymorphisms (tagSNPs) derived from the International Hapmap
project.
OBJECTIVES: To determine whether melatonin receptor 1B (MTNR1B) gene
polymorphisms are associated with the predisposition and/or disease severity of
adolescent idiopathic scoliosis (AIS).
SUMMARY OF BACKGROUND DATA: Linkage studies suggested a genetic predisposition
for AIS. In addition, evidence showed that AIS might be related to melatonin
deficiency and dysfunction of melatonin signaling pathway. Locating in one of
the chromosomal regions linked to AIS, MTNR1B gene is a potential candidate gene
for AIS.
METHODS: This study was carried out in 2-stage case-control analysis: 1) initial
screening (472 cases and 304 controls) and 2) separate replication test (342
cases and 347 controls) to confirm results in the screening. In the first
screening stage, 5 tagSNPs were selected to cover most of the genetic variation
in the MTNR1B gene. In the second stage, SNPs showing association in the
screening stage were studied in a separate replication sample set to confirm the
association. Genotyping was performed by PCR-RFLP.
RESULTS: The first stage showed a putative association between rs4753426 and
AIS, which was confirmed in the replication sample set. By meta-analysis, the
frequency of C allele of this SNP locating in the promoter was significantly
higher in the cases than controls (P = 0.006 aftermeta-analysis). Subjects with
the CC genotype had an odds ratio of 1.29 for AIS. Another SNP rs741837 in
promoter region, being moderate linkage disequilibrium with rs4753426, was also
marginally associated with AIS.
CONCLUSION: Polymorphisms of the promoter of MTNR1B gene were associated with
AIS, but not with the curve severity in AIS patients. This suggested that MTNR1B
was an AIS predisposition gene. OBJECTIVE: To investigate the association of vitamin D receptor (VDR) gene
polymorphisms with abnormal growth pattern and low bone mass in adolescent
idiopathic scoliosis (AIS) patients.
METHODS: Peripheral blood samples were obtained from 164 female patients with
AIS, aged 14.4 +/- 2 (9 - 20), and 122 age-matched healthy girls. Polymerase
chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was
used to detect the VDR gene distributions.
RESULTS: The frequency of Bb genotype was significantly higher in the AIS
patients than in the controls (P < 0.01). The frequency of B alleles of the AIS
patients was significantly higher than that of the controls (P < 0.01). In AIS
patients, the expression rate of Aa genotype of the AIS patients with the body
mass index (BMI) > or = 18 kg/m(2) was significantly higher than those with the
BMI < 18 kg/m(2) (P < 0.05), and the expression rate of Bb genotype of the AIS
patients with the BMI < 18 kg/m(2) and arm span < 160 cm was significantly
higher than that of the AIS patients with the BMI > or = 18 kg/m(2) and arm span
> or = 160 cm (P < 0.05).
CONCLUSION: The BsmI site polymorphism of vitamin D receptor gene may be
associated with abnormal growth pattern and low bone mass in girls with AIS. OBJECTIVE: To investigate the major effect of the candidate genes, calmodulin 1
(CALM1) and growth hormone receptor (GHR) gene, in mechanism of adolescent
idiopathic scoliosis (AIS) and to evaluate the cross-influence between the
polymorphism of the candidates genes and risk factors of AIS.
METHODS: Peripheral blood samples were collected from 30 AIS patients, 6 boys
and 24 girls, aged 15.7, and 30 gender and age-matched controls. Genomic DNA was
extracted. PCR amplification and sequencing of the segments containing SNPs
chosen from candidate genes were conducted. The SNPs were genotyped then.
Statistical analysis was conducted. Questionnaire survey was conducted in terms
of the risk factors.
RESULTS: (1) The AIS patients had higher corrected standing height and an
earlier growth spurt than the controls. (2) The frequencies of CC genotype of
CALM1 gene at -16C > T locus and homozygous genotype of GHR gene at exon 10
I526L were significantly higher in the AIS patients than in the controls. (3)
The frequencies of SNP03G-05A and SNP03G-05C haplotypes of GHR gene were
significantly higher in the AIS patients than in the controls. (4) The frequency
of PPGG (PP = homozygous genotype of GHR gene at I526L, GG = homozygous genotype
of MTNR1B gene at rs1562444 locus) of the AIS patients was significantly higher
than that of the controls. (5) The AIS patients who had homozygous genotype of
GHR gene at I526L had an earlier growth spurt and higher standing height than
those who had heterozygous genotype.
CONCLUSION: The -16C > T polymorphism at the promoter region of CALM1 gene and
the homozygous genotype of GHR gene at I526L may be associated with high
susceptibility to AIS. STUDY DESIGN: Case-control study.
OBJECTIVE: As inflammation plays a key role in the etiology of intervertebral
disc degeneration, we suggest a possible contribution of pro-inflammatory gene
polymorphisms in the pathogenesis of adolescent idiopathic scoliosis (AIS).
SUMMARY OF BACKGROUND DATA: The nucleus pulposus of scoliotic discs responds to
exogenous stimuli by secreting interleukin-6 (IL-6) and other inflammatory
cytokines. The association between matrix metalloproteinases (MMPs) and disc
degeneration has been reported by several investigators. A human MMP-3 promoter
5A/6A gene polymorphism regulates MMP-3 genes expression, while the G/C
polymorphism of the promoter region of IL-6 gene influences levels and
functional activity of the IL-6 protein.
METHODS: We conducted a case-control study to investigate whether the 5A/6A
polymorphism of the MMP-3 gene and the G/C polymorphism of the promoter region
of IL-6 gene were associated with susceptibility to AIS.
RESULTS: The frequency of the 5A/5A genotype of MMP-3 gene polymorphism in
patients with scoliosis was almost 3 times higher than in controls (30.2% vs.
11.2%, p 0.001), and the frequency of the G/G genotype of IL-6 gene polymorphism
in patients with scoliosis was almost 2 times higher than in controls (52.8% vs.
26.2%, P < 0.001). 5A/5A genotype of MMP-3 gene polymorphism and G/G genotype of
IL-6 gene polymorphism are independently associated with a higher risk of
scoliosis (odds ratio, respectively, 3.34 and 10.54).
CONCLUSION: This is the first study that has evaluated the possibility that gene
variants of IL-6 and MMPs might be associated with scoliosis and suggests that
MMP-3 and IL-6 promoter polymorphisms constitute important factors for the
genetic predisposition to scoliosis. Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis that
affects a significant number of young teenagers, mainly females (0.2-6 % of the
population). Historically, several hypothesis were postulated to explain the
aetiology of AIS, including genetic factors, biochemical factors, mechanics,
neurological, muscular factors and hormonal factors. The neuroendocrine
hypothesis involving a melatonin deficiency as the source for AIS has generated
great interest. This hypothesis stems from the fact that experimental
pinealectomy in chicken, and more recently in rats maintained in a bipedal mode,
produces a scoliosis. The biological relevance of melatonin in idiopathic
scoliosis is controversial since no significant decrease in circulating
melatonin level has been observed in a majority of studies. Analysis of
melatonin signal transduction in musculoskeletal tissues of AIS patients
demonstrated for the first time a defect occurring in a cell autonomous manner
in different cell types isolated from AIS patients suffering of the most severe
form of that disease. These results have led to a classification of AIS patients
in three different functional groups depending on their response to melatonin,
suggesting that the cause of AIS involves several genes. Molecular analysis
showed that melatonin signaling dysfunction is triggered by an increased
phosphorylation of Gi proteins inactivating their function. This discovery has
led to development of a first scoliosis screening assay. This test, using blood
sample, is currently in clinical validation process in Canada and could be used
for screening children at high risk of developing AIS. Herein we characterize an apparently balanced de novo translocation,
t(X;15)(p22.2;q26.1)dn, in a female patient with scoliosis, hirsutism, learning
problems, and developmental delay (DGAP025). Other clinical findings include a
high-arched palate, 2-3 syndactyly of the toes, and mildly elevated serum
testosterone. No known or predicted genes are disrupted by the Xp22.2
breakpoint. The 15q26.1 breakpoint disrupts chromodomain helicase DNA binding
protein 2 (CHD2). Another member of the chromatin-remodeling gene family, CHD7,
has been associated with a defined constellation of congenital anomalies known
as coloboma, heart anomaly, choanal atresia, mental retardation, genital and ear
anomalies syndrome (CHARGE) and idiopathic scoliosis. Monosomy of 15q26 also has
been associated with a spectrum of congenital abnormalities and growth
retardation that overlaps with those of DGAP025. To provide a biological
correlate, we characterized a mutant mouse model with Chd2 disruption that is
associated with embryonic and perinatal lethality. Expression analysis indicated
that Chd2 is expressed in the heart, forebrain, extremities, facial and dorsal
regions during specific times of embryonic development. Chd2(+/m) mice showed
pronounced lordokyphosis, reduced body fat, postnatal runting, and growth
retardation. These data suggest that haploinsufficiency for CHD2 could result in
a complex of abnormal human phenotypes that includes scoliosis and possibly
features similar to CHARGE syndrome. STUDY DESIGN: A genetic association study of tryptophan hydroxylase 1 gene
(TPH1) and arylalkylamine N-acetyltransferase gene(AANAT) with adolescent
idiopathic scoliosis (AIS) in Han Chinese.
OBJECTIVE: To access whether TPH1 and AANAT polymorphisms are associated with
the predisposition, gender, and/or severity of AIS.
SUMMARY OF BACKGROUND DATA: Studies have shown that AIS is a multifactorial
inheritance disease, but the etiology is still unknown. In addition, several
lines of evidence show that melatonin deficiency is closely associated with AIS,
although there are still doubts and debates. Some polymorphisms in TPH1 and
AANAT, the genes of 2 critical enzymes involved in melatonin biosynthesis, may
contribute to variability of melatonin production in pineal glands.
METHODS: We genotyped 16 reported single nuclear polymorphisms (SNPs) present in
TPH1 and AANAT in 103 AIS patients and 108 controls with matched sex and age.
The data of 6 SNPs with minor allele frequence (MAF) above 5% were analyzed by
the allelic and genotypic association analysis, the genotype-phenotype (gender
and Cobb angle) association analysis, and the haplotype analysis.
RESULTS: The single SNP analysis showed that rs10488682, located in the promoter
region of TPH1, was related with the occurrence of AIS (P < 0.05). No SNP was
found to be correlated with gender or Cobb angle. Two makers (rs8176799 and
rs2108977) in TPH1 were found to be in strong LD [ D' = 1.0 (95% CI, 0.9-1.0),
gamma = 0.501, LOD = 18.93] in the controls. Both global haplotype analysis and
individual haplotype analysis showed that there was no haplotype significantly
associated with AIS in this LD block.
CONCLUSION: TPH1 polymorphisms were associated with AIS but not with gender and
Cobb angle in AIS patients. AANAT polymorphisms were not associated with AIS.
These results suggested that TPH1 was an AIS predisposition gene, and there was
a close relationship between the dyssynthesis of melatonin and AIS. OBJECTIVE: To investigate the association between calmodulin1 (CALM1) gene or
estrogen receptor-alpha (ESR1) polymorphisms and double curve of adolescent
idiopathic scoliosis (AIS).
METHODS: 67 double curve patients (30 degrees < Cobb angle < 90 degrees ), 100
controls. There were 4 polymorphic loci, rs12885713 (-16C > T) and rs5871 locus
in CALM1 gene, rs2234693 (PvuII) and rs9340799 (XbaI) in ESR1 gene analyzed
sequence by ABI3730 genetic analyzer.
RESULTS: There were 60 patients with Cobb angle > or = 40 degrees . According to
the apical location of major curve, there were 40 thoracic curve patients.
Furthermore, 1) there are statistical differences on the polymorphic
distribution of ESR1 gene rs2234693 site between the double curve, Cobb angle >
or = 40 degrees or thoracic curve patients and the controls, respectively
(chi(2) = 6.081, 5.554, 6.1935; P = 0.014, 0.0128, 0.0184); 2) between the
double curve cases and the controls, there is difference on the polymorphic
distribution of rs12885713 site in CALM1 gene (chi(2) = 4.478; P = 0.034); 3)
Between the thoracic curve patients and the controls, there is difference on the
distribution of rs5871 allele polymorphism in CALM1 gene (chi(2) = 6.6061; P =
0.0102).
CONCLUSION: Double curve patterns might be related to ESR1 gene rs2234693
(PvuII) site polymorphism. It is necessary to clarify the association between
the polymorphisms of ESR1 gene and CALM1 gene and different subtypes of
adolescent idiopathic scoliosis in the further study. STUDY DESIGN: A single large family, in which adolescent idiopathic scoliosis
(AIS) and pectus excavatum (PE) segregate as an autosomal domit condition,
was evaluated. Genome-wide linkage analysis and candidate gene sequencing were
performed.
OBJECTIVE: To map the disease-causing locus in a large white family in which AIS
and PE cosegregate.
SUMMARY OF BACKGROUND DATA: AIS and PE are common musculoskeletal conditions
known to have a genetic component, though few genes have been identified for
either. Genetic studies have been confounded by a lack of large families in
which the disorders segregate.
METHODS: Clinical examinations were performed on the proband, who underwent
posterior spinal fusion, and 12 additional affected family members. To map a
gene causing AIS and PE, a genome-wide linkage analysis was performed with the
Affymetrix Mapping 10 K XbaI array on 13 affected and 10 unaffected family
members. Candidate genes were sequenced.
RESULTS: AIS was present in 13 female family members and PE was present in 3
males and 1 female. Genome-wide linkage analysis resulted in a linkage peak on
chromosome 18 q with a maximum parametric multipoint logarithm of the odds score
of 3.86. Recombits delineated the critical genetic region to an interval of
6.4 cM between SNP_A-1519369 and SNP_A-1507702, corresponding to a 7.06-Mb
region (hg18: chr18:26342508-34395660). The chromosome 18 q linkage region
contains more than 30 genes. Resequencing of the coding regions of 21 candidate
genes in the region did not reveal any causative mutation.
CONCLUSION: Linkage analysis in this large family demonstrated a novel locus for
AIS and PE on chromosome 18 q. Because of the increased frequency of PE in
family members of AIS patients, consideration of family members with PE as
affected may increase the power of AIS genetic linkage studies. OBJECTIVE: To investigate the association of FBN3 gene polymorphism with
abnormal growth pattern in adolescent idiopathic scoliosis (AIS) patients.
METHODS: Blood samples were obtained from 273 AIS patients, aged (14.6 +/- 2.1)
(10 - 18), and 287 healthy age-matched females adolescents. The anthropometric
parameters of the AIS group, including age, body height, weight, arm span, Cobb
angle, time of menarche, and Risser's sign were recorded. Polymerase chain
reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used
to detect the FBN3 gene distribution.
RESULTS: The genotype and allele frequency distribution were comparable between
the AIS and normal control groups. There was no association with curve severity,
arm span, BMI in patients with AIS. In the rs7257948, There were not significant
differences in the FBN3 gene polymorphism sites rs35579498, rs12608849, and
rs7257948, and allele distribution between these 2 groups. In the AIS group, the
patients with GG genotype the number of those whose body height was > or = 160
cm was higher than those whose body height was < 160 cm (P = 0.01). In
rs35579498, the frequency of allele T was relatively higher in the AIS patients
than in the controls (P = 0.051). In the AIS patients, the expression rate of CT
genotype in those whose menarche age was > or = 12 years was significantly
higher than those whose menarche was < 12 years (P = 0.042).
CONCLUSION: The polymorphisms of the 4 SNPs in the exons of FBN3 gene are
neither associated with the occurrence nor the curve severity of AIS. However,
in rs35579498, T allele appears to be overrepresented in the patients compared
with the controls. Mutation in this site my plays a role in the occurrence and
progression of AIS, and in rs7257948, polymorphism of FBN3 gene may be
associated with body height of the AIS patients. Spinal deformities, and particularly scoliosis, are the most frequent forms of
orthopedic deformities in children and adolescents. About 1-6% of the population
has scoliosis. This disorder leads to severe spinal deformities and
predomitly affects adolescent girls.Although the multifactorial origin of
adolescent idiopathic scoliosis (AIS) is broadly recognized, the genetic causes
of AIS are still largely unknown. Our previous studies suggested a generalized
dysfunction of melatonin transduction (the hormone that is primarily produced in
the brain and epiphysis). In the meantime we have demonstrated that such a
defect of signal transduction is caused by chemical alterations, which
inactivate the function of the inhibitory G protein-coupled melatonin receptors.
This discovery has led to the development of the first blood test to detect
children without symptoms who are at risk of developing scoliosis. Since a
single function (cellular reaction to melatonin) is determined, the unique
advantage of this test is that it can be performed without knowledge of
mutations in defective genes that could provoke the onset of AIS. STUDY DESIGN: A case-control study is presented.
OBJECTIVE: To investigate the association of estrogen receptor beta gene
polymorphisms with susceptibility to adolescent idiopathic scoliosis.
SUMMARY OF BACKGROUND DATA: Studies have shown that idiopathic scoliosis is
related to genetic factors, such as XbaI site polymorphism of the estrogen
receptor alpha gene. To our knowledge, however, the relationship of estrogen
receptor beta gene polymorphisms and the individual susceptibility to idiopathic
scoliosis has not been studied.
METHODS: This study included 218 patients with AIS and 140 healthy controls.
Height, menarche status, curve pattern, Cobb angle, and Risser sign in female
patients were recorded. Blood samples were taken from each subject by
venipuncture. Genomic DNA was extracted from peripheral blood leukocytes using
standard phenol/chloroform extraction. PCR products from amplification of
genomic DNA from all individuals were analyzed using denaturing high-performance
liquid chromatography. Samples with aberrant HPLC profiles were sequenced in
both the forward and the reverse directions on an ABI 3100 automated sequencer.
The chi test was used to determine the significant difference in genotype
distribution between patients with AIS and the controls.
RESULTS: The frequency of CC genotype of the exon ØK (in reality 5' UTR OK-1)was
significantly higher in patients than that in controls (P < 0.05). The C alleles
appeared to be overrepresented in patients compared with controls (P < 0.05).
Furthermore, the frequencies of CC genotypes in female patients whose height was
> or =160 cm and Cobb angle was > or =30 degrees were higher than those whose
height was <160 cm and Cobb angle was <30 degrees (P < 0.05). CONCLUSION.: The
sites of the exon ØK polymorphisms of estrogen receptor beta gene may be
associated with a susceptibility of AIS. Furthermore, the sites of the exon ØK
polymorphism may be associated with the height and the curve severity of
patients. Adolescent idiopathic scoliosis (AIS) is a common disorder with strong evidence
for genetic predisposition. Quantitative trait loci (QTLs) for AIS
susceptibility have been identified on chromosomes. We performed a genome-wide
genetic linkage scan in seven multiplex families using 400 marker loci with a
mean spacing of 8.6 cM. We used Genehunter Plus to generate linkage statistics,
expressed as homogeneity (HLOD) scores, under domit and recessive genetic
models. We found a significant linkage signal on chromosome 12p, whose support
interval extends from near 12 pter, spanning approximately 10 million bases or
31 cM. Fine mapping within the region using 20 additional markers reveals
maximum HLOD = 3.7 at 5 cM under a domit inheritance model, and a split peak
maximum HLOD = 3.2 at 8 and 18 cM under a recessive inheritance model. The
linkage support interval contains 95 known genes. We found evidence suggestive
of linkage on chromosomes 1, 6, 7, 8, and 14. This study is the first to find
evidence of an AIS susceptibility locus on chromosome 12. Detection of AIS
susceptibility QTLs on multiple chromosomes in this and other studies
demonstrate that the condition is genetically heterogeneous. Marfan syndrome is a variable autosomal domit disorder; most cases result
from mutations of fibrillin-1. Diagnosis is guided by the Ghent nosology. The
condition may manifest in the cardiovascular and ocular systems. Musculoskeletal
manifestations include scoliosis, dural ectasia, protrusio acetabuli, and
ligamentous laxity. Compared with patients with idiopathic scoliosis, patients
with Marfan syndrome tend to have scoliosis that progresses at a faster rate and
is more resistant to bracing; undergo scoliosis surgery complicated by greater
blood loss, pseudarthrosis, and additional curvature; and have more frequent
occurrences of dural ectasia, which may cause headaches, leg pain, or perineal
pain. Protrusio acetabuli may result in hip joint arthritis and may require
valgus osteotomy or total hip arthroplasty. OBJECTIVE: To identify whether SH3GL1 gene serves as a disease associated gene
of adolescent idiopathic scoliosis (AIS).
METHODS: Positioning candidate cloning: "case-sibling or case-family control
design" research scheme based on family constellation was designed. Fifty-six
AIS patients (15 male and 41 female, mean age 15 years old, ranged from 8 to 22
years old, Cobb angle from 25 degrees to 110 degrees , average Cobb angle of
67.5 degrees ) from November 2007 to December 2008 were recruited. In all
patients, blood preparation was collected, and genome DNA was extracted.
According to nucleotide sequence of gene SH3GL1, primer pair for PCR
amplification, cloning, and sequencing with 10 exons as emphasis was designed.
Sequence comparative analysis for exon sequencing result between sib pairs or
family pairs, and that between sib pair or family pairs and NCBI (National
Center for Biotechnology Information) were conducted through Vector NTI Advance
10.3 software to judge whether basic group mutation occurred or not. Amino acid
sequence comparative analysis for prediction was made.
RESULTS: Ten exons of the candidate gene SH3GL1 were successfully amplified and
cloned in genome DNA of an AIS sib pair and family pairs, and the sequencing
obtained positive results. Twelve basic group mutations were found in 10 exons
of the candidate gene SH3GL1 of patients with AIS. These mutations were located
in the second exon (3 mutations), the fourth exon (1 mutations), the fifth exon
(4 mutations), the sixth exon (1 mutations), the eighth exon (1 mutations), and
the tenth exon (2 mutations, noncoding region). If basic group in 515 of mRNA
was mutated to T, termination codon(TAG) came into being and open reading frame
was altered. The sequence of protein showed brachytmema protein was encoded,
which could cause changes of primary structure.
CONCLUSION: SH3GL1 is possibly one of the disease associated genes of AIS. BACKGROUND: Adolescent idiopathic scoliosis (AIS) is the most common spinal
deformity in children. Studies have shown low melatonin levels resulting from
pinealectomy in chickens and mice result in the development scoliosis, whereas
supplementation with melatonin after the pinealectomy prevented it. The mere
characterization of low melatonin levels is not sufficient to explain the
development of idiopathic scoliosis in primates and humans, but we hypothesize
that a mutation in melatonin-related receptors may be involved with the
development of scoliosis.
METHODS: The coding, splice-site, and promoter regions of 3 melatonin-related
receptors (hMel-1B, RORalpha, and GPR50) were evaluated by DNA sequencing for
variants associated with the phenotype of adolescent idiopathic scoliosis. An
initial screening of 50 scoliosis patients with adolescent idiopathic scoliosis
was compared with 50 controls by DNA sequencing of the 3 receptors. Additional
cases and controls were evaluated when genetic variants were observed (for a
total of 885 individuals).
RESULTS: No significant differences were found in the hMel-1B and RORalpha
receptors. We found 2 cSNPs in GPR50 (rs561077 and rs13440581) in the initial 50
patients. To evaluate the significance of these cSNPs, an additional 356
patients and 429 controls were analyzed. When the combined groups were analyzed,
no significant associations were observed.
CONCLUSIONS: Despite the observed relationship between melatonin and scoliosis,
there is no significant association between mutations found in any known
melatonin-related receptors with adolescent idiopathic scoliosis. The strong
evidence of a melatonin-related cause for the development of idiopathic
scoliosis still encourages research into undiscovered melatonin-related
receptors, melatonin-related hormones, and the catalytic enzymes for the
serotonin-melatonin pathway.
CLINICAL RELEVANCE: This investigation is a genetic testing of the remaining
currently known melatonin-related receptors that have not been analyzed earlier
for association with AIS. Given the support in the literature of a relationship
between melatonin and AIS, we have shown no mutations in any of the known
melatonin-related receptor in patients with AIS. Adolescent idiopathic scoliosis (AIS) is a condition characterized by a
three-dimensional structural deformity of the spine. It is the most common type
of spine deformity occurring in children aged 10 to maturity. Although the
etiology of AIS still remains unknown, the role of genetic factors in the
development of idiopathic scoliosis is widely accepted. However, to date no
causative genes of AIS have been identified. Recently, the semicircular canals,
which are part of the inner ear, were found to be morphologically abnormal in
idiopathic scoliosis patients. Here we hypothesized that genetic predisposition
to inner ear anomalies in AIS patients may be a strong factor in the generation
of idiopathic scoliosis. The proposed idea is that gene defects could impair the
development of the semicircular canals. A malformation of semicircular canals
might affect the transmission of sensory signal about rotational movement of the
body to the central nervous system; leading to an alteration in the neuronal
circuit of balance. This will in turn affect body posture and results in the
initiation of the curvature of the spine. This hypothesis may provide new
insights in the understanding of the pathophysiologic mechanisms of idiopathic
scoliosis. It can also offer hopes for potential early prediction of scoliosis. STUDY DESIGN: Genetic association study investigating the association of genetic
markers of melatonin signaling and biosynthesis with adolescent idiopathic
scoliosis (AIS).
OBJECTIVE: To determine whether gene polymorphisms related to the melatonin
signaling or biosynthesis pathways are associated with AIS.
SUMMARY OF BACKGROUND DATA: Data have been published on the potential role of
gene polymorphisms for melatonin receptor (MTNR) 1B in predicting AIS. Other
genes in the melatonin pathways have been tested for association with AIS.
METHODS: The following genes involved in melatonin synthesis were evaluated
herein: tryptophan 5-hyroxylase 1 (TPH1), serotonin N-acetyltransferase (SNAT),
and hydroxyindoleo-methyltransferase (HIOMT). In addition, proteins involved in
melatonin signaling were also included in this study: MTNR1A, MTNR1B, and
protein kinase C delta (PKCd). High throughput microarray-based single
nucleotide polymorphism (SNP) genotyping was performed for these seven genes
using DNA samples from 589 AIS subjects and 1533 ethnically matched controls.
Chi-square analyses of allele frequency between AIS cases and controls were
performed and odds ratios were calculated for all SNP markers.
RESULTS: Three SNPs were tested for both MTNR1A and HIOMT, 4 for TPH1 and SNAT,
12 for PKCd, and 7 for MTNR1B. The minor allele frequencies were not
significantly different between AIS cases and controls. No association was thus
found between AIS and the investigated SNPs.
CONCLUSIONS: Genetic polymorphisms associated with either melatonin synthesis or
its signaling pathway are unlikely to be commonly associated with AIS. Adolescent idiopathic scoliosis (AIS) is a spinal deformity most commonly
arising in apparently healthy girls around puberty. AIS has a strong genetic
predisposition. Several genetic associations between AIS and single nucleotide
polymorphisms (SNPs) have been reported; common SNPs in the genes for matrilin 1
(MATN1), melatonin receptor 1B (MTNR1B), tryptophan hydroxylase 1 (TPH1), and
insulin-like growth factor 1 (IGF1) are reported to be associated with AIS in
Chinese. However, these associations have not been replicated so far. To confirm
the associations, we compared these SNPs with AIS predisposition and curve
severity in a population of Japanese females consisting of 798 AIS patients and
1,239 controls. All the subjects were genotyped using the PCR-based Invader
assay. We found no association of any of the SNPs with AIS predisposition or
curve severity. Considering the statistical power and sample size of the present
study, we concluded that these SNPs are not associated with either AIS
predisposition or curve severity in Japanese. Adolescent idiopathic scoliosis (AIS) is a common disorder with a strong genetic
predisposition. Associations between AIS and common single nucleotide
polymorphisms (SNPs) in estrogen receptor genes have been reported. rs9340799 in
the gene for estrogen receptor α (ESR1) is reported to be associated with curve
severity in Japanese and with AIS predisposition and curve severity in Chinese.
In addition, rs1256120 in the gene for estrogen receptor β (ESR2) is reported to
be associated with AIS predisposition and curve severity in Chinese. However,
the sample sizes of these previous studies were small, and the associations of
these SNPs have not been replicated. To examine the association between AIS and
estrogen receptor genes, we investigated the association of rs9340799 and
rs1256120 with AIS predisposition and curve severity using a large Japanese
population, consisting of 798 AIS patients and 637 sex-matched controls. We
found no association of either SNP with AIS predisposition or curve severity in
the Japanese population. Considering the statistical power of the present study
and the limitations of the previous reports, we conclude that the associations
of rs9340799 and rs1256120 with AIS predisposition and curve severity are
negative. PURPOSE: To investigate whether the predisposition genes previously reported to
be associated with the occurrence or curve severity of adolescent idiopathic
scoliosis (AIS) play a role in the effectiveness of brace treatment.
METHOD: A total of 312 AIS patients treated with bracing were enrolled in this
study. The Cobb angle of the main curve was recorded at the beginning of brace
treatment as well as at each follow-up. The patients were divided into two
groups according to the outcome of brace treatment (success/failure). The
failure of brace treatment was defined as a curve progression of more than 5°
compared to the initial Cobb angle or surgical intervention because of curve
progression. Single nucleotide polymorphism (SNP) sites in the genes for
estrogen receptor α (ERα), estrogen receptor β (ERβ), tryptophan hydroxylase 1
(TPH-1), melatonin receptor 1B (MTNR1B) and matrillin-1 (MATN1), which were
previously identified to be predisposition genes for AIS, were selected for
genotyping by the PCR-RFLP method. Differences of genotype and allele
distribution between the two groups were compared by the χ(2) test. A logistic
regression analysis was used to figure out the independent predictors of the
outcome of brace treatment.
RESULTS: There were 90 cases (28.8%) in the failure group and 222 cases (71.2%)
in the success group. Patients in the failure group were associated with the
genotype GA (50.9 vs. 17.9% p < 0.001) and the G allele (27.1 vs. 12.0%, p <
0.001) at SNP rs9340799 of the ERα gene. Similarly, they were also associated
with the genotype AT (33.3 vs. 13.0%, p = 0.002) and the A allele (16.7 vs.
9.6%, p = 0.033) at SNP rs10488682 of the TPH-1 gene. For MTNR1B, the difference
of genotype distribution between the two groups was found to be statistically
significant, while the difference of allele distribution between the two groups
was found to be marginally statistically significant; for the MATN1 and ERβ
genes, we found no significant differences of the genotype or allele
distribution between the two groups. In the logistic regression analysis, ERα
and TPH-1 were demonstrated to be independent factors predictive of bracing
effectiveness.
CONCLUSIONS: ERα and TPH-1 might be potential genetic markers that could predict
the outcome of brace treatment. Patients with the G allele at the rs9340799 site
of the ERα gene and the A allele at the rs10488682 site of the TPH-1 gene are
prone to be resistant to brace treatment. Clinical studies have suggested that defects in the epaxial muscles,
particularly multifidus, may contribute to the etiology of idiopathic scoliosis.
While the epaxial muscles and the vertebrae derive from the same embryonic
segmentation process, the mechanisms that pattern the multisegmental back
muscles are still unclear. The process of segmentation is regulated by the Notch
signaling pathway, and mutations in the modulators delta-like 3 (Dll3) and
lunatic fringe (Lfng) are genetic models for spinal disorders such as scoliosis.
Osteological defects have been characterized in these genetic models, but
myological phenotypes have not previously been studied. We analyzed the
multifidus muscle in the mouse (Mus musculus) and observed intriguing changes in
the cranio-caudal borders of multifidus in Dll3 and Lfng models. Statistical
analysis did not find a significant association between the majority of the
multifidus anomalies and the vertebral defects, suggesting a previously
unappreciated role for Notch signaling in patterning epaxial muscle groups.
These findings indicate an additional mechanism by which DLL3 and LFNG may play
a role in the etiology of human idiopathic scoliosis. STUDY DESIGN: A genetic association study to comprehensively investigate
variations of neurotrophin 3 (NTF3) gene polymorphisms in a Chinese Han
population.
OBJECTIVE: To explore whether the NTF3 gene polymorphisms are associated with
the susceptibility, curve severity, or bracing effectiveness of adolescent
idiopathic scoliosis (AIS).
SUMMARY OF BACKGROUND DATA: Scoliosis has developed in mice with NTF3 deficiency
in previous studies. Increased expression of NTF3 mRNA was detected in the
paravertebral muscle in AIS. Moreover, linkage study has defined a novel AIS
locus on chromosome 12p while NTF3 gene is located exactly in this interval. All
evidence indicates a potential role of NTF3 in the pathogenesis of AIS. As for
brace treatment of AIS, continuous sensory stimulation caused by an orthosis
could help awareness of body misalignment and trigger curve correction through
postural reflex. While NTF3 gene is tightly associated with proprioceptive
feedback mechanism to adjust postural control, we hypothesized NTF3 as a
potential candidate gene associated with the bracing effectiveness.
METHODS: A total of 362 AIS patients and 377 age-matched healthy controls were
recruited. Two single-nucleotide polymorphisms (SNPs) were selected on the basis
of the Chinese data from the HapMap project, and genotyping was carried out by
polymerase chain reaction-restriction fragment length polymorphism for each SNP,
respectively. Case-control study and case-only study were performed to define
the contribution of NTF3 gene polymorphisms to predisposition and disease
severity of AIS. Another subgroup of 120 skeletally immature AIS patients who
received continuous brace treatment for minimal 2 years was genotyped, and
bracing effectiveness was assessed to determine its association with NTF3 gene
polymorphisms.
RESULTS: The genotype and allele frequency distribution were similar between AIS
and normal control for these 2 SNPs (χ² test: P > 0.05). For SNP rs11063714 in
the promoter region of NTF3 gene, AIS patients with AA genotype showed
significantly lower mean maximum Cobb angle than the patients with AG or GG
genotypes (analysis of variance: P = 0.008). In addition, skeletally immature
bracing AIS patients with AA genotype possessed significantly higher successful
ratio of brace treatment compared with GG genotype (χ² test: P = 0.043). For SNP
rs1805149, no significant association with predisposition or curve severity was
detected.
CONCLUSION: The NTF3 gene polymorphisms are not associated with the occurrence
of AIS, but the promoter polymorphism (rs11063714) is associated with the curve
severity, implicating an alleviating role of NTF3 in the curve progression of
AIS. In addition, the promoter polymorphism is also associated with brace
responsiveness. These findings indicated that NTF3 gene might be a
disease-modifying gene of AIS. PURPOSE: To investigate the effects of genetic factors on idiopathic scoliosis
(IS) and genetic modes through genetic epidemiological survey on IS in Chongqing
City, China, and to determine whether SH3GL1, GADD45B, and FGF22 in the
chromosome 19p13.3 are the pathogenic genes of IS through genetic sequence
analysis.
METHODS: 214 nuclear families were investigated to analyse the age incidence,
familial aggregation, and heritability. SH3GL1, GADD45B, and FGF22 were chosen
as candidate genes for mutation screening in 56 IS patients of 214 families. The
sequence alignment analysis was performed to determine mutations and predict the
protein structure.
RESULTS: The average age of onset of 10.8 years suggests that IS is a early
onset disease. Incidences of IS in first-, second-, third-degree relatives and
the overall incidence in families (5.68%) were also significantly higher than
that of the general population (1.04%). The U test indicated a significant
difference, suggesting that IS has a familial aggregation. The heritability of
first-degree relatives (77.68 ±10.39%), second-degree relatives (69.89 ±3.14%),
and third-degree relatives (62.14 ±11.92%) illustrated that genetic factors play
an important role in IS pathogenesis. The incidence of first-degree relatives
(10.01%), second-degree relatives (2.55%) and third-degree relatives (1.76%)
illustrated that IS is not in simple accord with monogenic Mendel's law but
manifests as traits of multifactorial hereditary diseases. Sequence alignment of
exons of SH3GL1, GADD45B, and FGF22 showed 17 base mutations, of which 16
mutations do not induce open reading frame (ORF) shift or amino acid changes
whereas one mutation (C→T)occurred in SH3GL1 results in formation of the
termination codon, which induces variation of protein reading frame. Prediction
analysis of protein sequence showed that the SH3GL1 mutant encoded a truncated
protein, thus affecting the protein structure.
CONCLUSION: IS is a multifactorial genetic disease and SH3GL1 may be one of the
pathogenic genes for IS. Adolescent idiopathic scoliosis (AIS) is a complex disorder with an unclear
etiology and pathogenesis. In previous studies, genome-wide linkage and genetic
association analyses have been carried out to find genetic factors linked with
AIS. In this study, we examined whether the susceptibility to AIS is associated
with MATN1 gene polymorphisms in a Korean population, which included 166
individuals with AIS and 126 controls. We found that there were no statistically
significant associations between any of the MATN1-linked allele or genotype
frequencies between AIS and controls. However, statistically significant
associations were found at single nucleotide polymorphism (SNP) rs1065755 when
comparing the curve patterns of AIS with the controls. The A allele of SNP
rs1065755 was associated with a higher risk of AIS than the allele G in the
genotype-phenotype (curve pattern) analysis (P = 0.029). In addition, the
frequency of the A allele of SNP rs1065755 in AIS with double major curves was
higher than in controls (P = 0.021, ORs = 2.56 within 95% CI = 1.12-5.83).
Additionally, among the predicted common haplotypes, the frequency of the
haplotype GATT (31.3%) in AIS with double major curves was higher than in
controls (15.2%) (P = 0.024, ORs = 2.54 within 95% CI = 1.11-5.84). We conclude
that the A allele of SNP rs1065755 in the MATN1 gene is associated with AIS. Leptin has been suggested to play a role in the etiology of Adolescent
Idiopathic Scoliosis (AIS), however, the leptin levels in AIS girls are still a
discrepancy, and no in vitro study of leptin in AIS is reported. We took a
series of case-control studies, trying to understand whether Leptin gene
polymorphisms are involved in the etiology of the AIS or the change in leptin
level is a secondary event, to assess the level of leptin receptor, and to
evaluate the differences of response to leptin between AIS cases and controls.
We screened all exons of Leptin gene in 45 cases and 45 controls and selected
six tag SNPs to cover all the observed variations. Association analysis in 446
AIS patients and 550 healthy controls showed no association between the
polymorphisms of Leptin gene and susceptibility/severity to AIS. Moreover,
adipogenesis assay of bone mesenchymal stem cells (MSCs) suggested that the
adipogenic ability of MSCs from AIS girls was lower than controls. After
adjusting the differentiation rate, expressions of leptin and leptin receptor
were similar between two groups. Meanwhile, osteogenesis assay of MSC showed the
leptin level was similar after adjusting the differentiation rate, but the
leptin receptor level was decreased in induced AIS osteoblasts.
Immunocytochemistry and western blot analysis showed less leptin receptors
expressed in AIS group. Furthermore, factorial designed studies with
adipogenesis and osteogenesis revealed that the MSCs from patients have no
response to leptin treatment. Our results suggested that Leptin gene variations
are not associated with AIS and low serum leptin probably is a secondary outcome
which may be related to the low capability of adipogenesis in AIS. The decreased
leptin receptor levels may lead to the hyposensitivity to leptin. These findings
implied that abnormal peripheral leptin signaling plays an important role in the
pathological mechanism of AIS. Recently, several genome wide association studies suggested IL-17RC, CHL1, DSCAM
and CNTNAP2 genes polymorphisms were associated with AIS. To confirm these
associations, we performed this case-control study using data from 648 AIS
patients and 573 healthy adolescent of Chinese Han population. A polymerase
chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was
performed to detect the genotypes of polymorphic loci: rs708567 rs279545 in
IL-17RC gene, and rs2055314, rs331894, rs2272524, rs2272522 in CHL1 gene, and
rs2222973 in DSCAM gene, and rs2710102, rs11770843 in CNTNAP2 gene. Statistical
analysis of genotype frequencies between AIS patients and controls were
performed by χ2 test. Our results show that both the genotype frequency and
allele frequency of loci rs708567 were significantly different between AIS
patients and controls (P = 0.023, 0.028, respectively). As for polymorphic loci
rs279545, rs2222973, rs279545, rs2055314, rs331894, rs2272524, rs2272522, no
significant difference was found between AIS patients and controls either
genotype or allele frequencies (p>0.05). Overall, our study found a
significant association of IL-17RC gene polymorphisms with AIS in a Chinese Han
population, indicating IL-17RC gene may be as a susceptibility gene for AIS;
While CHL1, CNTNAP2 and DSCAM genes were not associated with AIS, suggesting
that those genes may not be involved in the etiopathogenesis of AIS. However,
association study of these genes with AIS in other races is needed to clarify
the role of these genes in the etiology of AIS. BACKGROUND: Adolescent idiopathic scoliosis occurs between two and ten times
more frequently in females than in males. The exact cause of this sex
discrepancy is unknown, but it may represent a difference in susceptibility to
the deformity. If this difference is attributable to genetic factors, then males
with adolescent idiopathic scoliosis would need to inherit a greater number of
susceptibility genes compared with females to develop the deformity. Males would
also be more likely to transmit the disease to their children and to have
siblings with adolescent idiopathic scoliosis. Such a phenomenon is known as the
Carter effect, and the presence of such an effect would support a multifactorial
threshold model of inheritance.
METHODS: One hundred and forty multiplex families in which more than one
individual was affected with adolescent idiopathic scoliosis were studied. These
families contained 1616 individuals, including 474 individuals with adolescent
idiopathic scoliosis and 1142 unaffected relatives. The rates of transmission
from the 122 affected mothers and from the twenty-eight affected fathers were
calculated, and the prevalence among siblings was determined in the nuclear
families of affected individuals.
RESULTS: The prevalence of adolescent idiopathic scoliosis in these multiplex
families was lowest in sons of affected mothers (36%, thirty-eight of 105) and
highest in daughters of affected fathers (85%, twenty-two of twenty-six).
Affected fathers transmitted adolescent idiopathic scoliosis to 80%
(thirty-seven) of forty-six children, whereas affected mothers transmitted it to
56% (133) of 239 children (p < 0.001). Siblings of affected males also had a
significantly higher prevalence of adolescent idiopathic scoliosis (55%,
sixty-one of 110) compared with siblings of affected females (45%, 206 of 462)
(p = 0.04).
CONCLUSIONS: This study demonstrates the presence of the Carter effect in
adolescent idiopathic scoliosis. This pattern can be explained by polygenic
inheritance of adolescent idiopathic scoliosis, with a greater genetic load
required for males to be affected. PURPOSE: To investigate whether rs11190870 near LBX1 correlates with the
susceptibility or curve progression of adolescent idiopathic scoliosis (AIS) in
a Han Chinese population.
METHODS: A total of 949 AIS patients and 976 age-matched healthy controls were
recruited. All the subjects were genotyped using the PCR-based invader assay.
Case-control study and case-only study were performed to define the contribution
of rs11190870 to predisposition and curve severity of AIS. Additionally, we
further conducted a meta-analysis of the study findings together with those of
previously reported studies.
RESULTS: A significant association of rs11190870 with AIS was observed in the
Han Chinese population (P = 1.8 × 10(-9); odd ratio = 1.51; 95 % confidence
interval = 1.33-1.71), and AIS patients with TT genotype had a larger Cobb angle
than those with TC or CC genotype (P = 0.005). The meta-analysis confirmed that
the positive association of this SNP with AIS in the East Asian population.
CONCLUSIONS: The SNP rs11190870 near LBX1 is associated with both susceptibility
and curve progression of AIS. BACKGROUND: VDR may be considered as a candidate gene potentially related to
idiopathic scoliosis susceptibility and natural history. Transcriptional profile
of VDR mRNA isoforms might be changed in the structural tissues of the scoliotic
spine and potentially influence the expression of VDR responsive genes. The
purpose of the study was to determine differences in mRNA abundance of VDR
isoforms in bone, cartilage and paravertebral muscles between tissues from curve
concavity and convexity, between JIS and AIS and to identify VDR responsive
genes differentiating juvenile and adolescent idiopathic scoliosis in
paravertebral muscles.
METHODS: In a group of 29 patients with JIS and AIS, specimens of bone,
cartilage, paravertebral muscles were harvested at the both sides of the curve
apex together with peripheral blood samples. Extracted total RNA served as a
matrix for VDRs and VDRl mRNA quantification by QRT PCR. Subsequent microarray
analysis of paravertebral muscular tissue samples was performed with HG U133A
chips (Affymetrix). Quantitative data were compared by a nonparametric Mann
Whitney U test. Microarray results were analyzed with GeneSpring 11GX
application. Matrix plot of normalized log-intensities visualized the degree of
differentiation between muscular tissue transcriptomes of JIS and AIS group.
Fold Change Analysis with cutoff of Fold Change ≥2 identified differentially
expressed VDR responsive genes in paravertebral muscles of JIS and AIS.
RESULTS: No significant differences in transcript abundance of VDR isoforms
between tissues of the curve concavity and convexity were found. Statistically
significant difference between JIS and AIS group in mRNA abundance of VDRl
isoform was found in paravertebral muscles of curve concavity. Higher degree of
muscular transcriptome differentiation between curve concavity and convexity was
visualized in JIS group. In paravertebral muscles Tob2 and MED13 were selected
as genes differentially expressed in JIS and AIS group.
CONCLUSIONS: In Idiopathic Scolioses transcriptional activity and alternative
splicing of VDR mRNA in osseous, cartilaginous, and paravertebral muscular
tissues are tissue specific and equal on both sides of the curve. The number of
mRNA copies of VDRl izoform in concave paravertebral muscles might be one of the
factors differentiating JIS and AIS. In paravertebral muscles Tob2 and Med13
genes differentiate Adolescent and Juvenile type of Idiopathic Scoliosis. PURPOSE: The incidence of adolescent idiopathic scoliosis (AIS) has rapidly
increased, and with it, physician consultations and expenditures (about one and
a half times) in the last 5 years. Recent etiological studies reveal that AIS is
a complex genetic disorder that results from the interaction of multiple gene
loci and the environment. For personalized treatment of AIS, a tool that can
accurately measure the progression of Cobb's angle would be of great use. Gene
analysis utilizing single nucleotide polymorphism (SNP) has been developed as a
diagnostic tool for use in Caucasians but not Koreans. Therefore, we attempted
to reveal AIS-related genes and their relevance in Koreans, exploring the
potential use of gene analysis as a diagnostic tool for personalized treatment
of AIS therein.
MATERIALS AND METHODS: A total of 68 Korean AIS and 35 age- and sex-matched,
healthy adolescents were enrolled in this study and were examined for 10
candidate scoliosis gene SNPs.
RESULTS: This study revealed that the SNPs of rs2449539 in lysosomal-associated
transmembrane protein 4 beta (LAPTM4B) and rs5742612 in upstream and
insulin-like growth factor 1 (IGF1) were associated with both susceptibility to
and curve severity in AIS. The results suggested that both LAPTM4B and IGF1
genes were important in AIS predisposition and progression.
CONCLUSION: Thus, on the basis of this study, if more SNPs or candidate genes
are studied in a larger population in Korea, personalized treatment of Korean
AIS patients might become a possibility. PURPOSE: Adolescent Idiopathic Scoliosis (AIS) is considered a complex genetic
disease, in which malfunctioning or dysregulation of one or more genes has been
proposed to be responsible for the expressed phenotype. However, to date, no
disease causing genes has been identified and the pathogenesis of AIS remains
unknown. The aim of this study is, therefore, to identify specific molecules
with differing expression patterns in AIS compared to healthy individuals.
METHODS: Microarray analysis and quantitative RT-PCR have examined differences
in the gene transcription profile between primary osteoblasts derived from
spinal vertebrae of AIS patients and those of healthy individuals.
RESULTS: There are 145 genes differentially expressed in AIS osteoblasts. A
drastic and significant change has been noted particularly in the expression
levels of Homeobox genes (HOXB8, HOXB7, HOXA13, HOXA10), ZIC2, FAM101A, COMP and
PITX1 in AIS compared to controls. Clustering analysis revealed the interaction
of these genes in biological pathways crucial for bone development, in
particular in the differentiation of skeletal elements and structural integrity
of the vertebrae.
CONCLUSIONS: This study reports on the expression of molecules that have not
been described previously in AIS. We also provide for the first time gene
interaction pathways in AIS pathogenesis. These genes are involved in various
bone regulatory and developmental pathways and many of them can be grouped into
clusters to participate in a particular biological pathway. Further studies can
be built on our findings to further elucidate the association between different
biological pathways and the pathogenesis of AIS. BACKGROUND: Dystonia is a movement disorder characterized by involuntary muscle
contractions that cause twisting movements and abnormal postures. Primary
dystonia is the most common form and is thought to be a multifactorial condition
in which one or more genes combine with environmental factors to reach disease.
METHODS: We reviewed controlled studies on possible environmental risk factors
for primary early- and late-onset dystonia.
RESULTS: Environmental factors associated with primary early-onset dystonia are
poorly understood. Early childhood illnesses have been reported to be more
frequent in patients with DYT1 dystonia than in subjects carrying the DYT1
mutation that did not manifest dystonia, thus raising the possibility that such
exposures precipitate dystonia among DYT1 carriers. Conversely, several
environmental factors have been associated with primary adult-onset focal
dystonias compared to control subjects. Namely, eye diseases, sore throat,
idiopathic scoliosis, and repetitive upper limb motor action seem to be
associated with blepharospasm (BSP), laryngeal dystonia (LD), cervical dystonia
(CD), and upper limb dystonia, respectively. In addition, an inverse association
between coffee drinking and BSP has been observed in both case-unrelated control
and family-based case-control studies. Additional evidence supporting a causal
link with different forms of primary late-onset dystonia is only available for
diseases of the anterior segment of the eye, writing activity, and coffee
intake.
CONCLUSION: There is reasonable epidemiological evidence that some environmental
factors are risk-modifying factors for specific forms of primary adult-onset
focal dystonia. BACKGROUND: Adolescent idiopathic scoliosis (AIS) is characterized by a complex
curvature of the spine of unknown etiology. Unknown genetic factors likely play
a role in disease pathogenesis. Recent studies suggest that AIS could result
from central nervous system dysfunction and be related to dystonia. On the basis
of this information, we hypothesized that genes linked to dystonia contribute to
the pathogenesis of AIS.
METHODS: To test this hypothesis, we evaluated the potential association between
sequence variants in candidate dystonia genes and AIS. We sequenced the coding
region of 5 selected dystonia-causing genes in 24 subjects with AIS, followed by
targeted confirmation in additional 89 patients and 73 controls.
RESULTS: No mutations were identified in any of the dystonia genes studied.
CONCLUSIONS: We found no genetic link between dystonia and AIS.
CLINICAL RELEVANCE: This investigation is a genetic evaluation of the
association between dystonia and AIS. Despite the support in the literature for
a pathogenic link between both the disorders, we have not identified any
mutations in dystonia genes in patients with AIS. Adolescent idiopathic scoliosis (AIS) is the most common spinal deformity,
affecting around 2% of adolescents worldwide. Genetic factors play an important
role in its etiology. Using a genome-wide association study (GWAS), we recently
identified novel AIS susceptibility loci on chromosomes 10q24.31 and 6q24.1. To
identify more AIS susceptibility loci relating to its severity and progression,
we performed GWAS by limiting the case subjects to those with severe AIS.
Through a two-stage association study using a total of ∼12,000 Japanese
subjects, we identified a common variant, rs12946942 that showed a significant
association with severe AIS in the recessive model (P=4.00 × 10(-8), odds ratio
[OR]=2.05). Its association was replicated in a Chinese population (combined
P=6.43 × 10(-12), OR = 2.21). rs12946942 is on chromosome 17q24.3 near the genes
SOX9 and KCNJ2, which when mutated cause scoliosis phenotypes. Our findings will
offer new insight into the etiology and progression of AIS. The Escobar variant of multiple pterygium syndrome (OMIM #265000) is a rare,
autosomal recessive disorder associated with mutations in the γ-subunit of the
nicotinic acetylcholine receptor (CHRNG). CHRNG is expressed in fetal muscle
during motor development and contributes to the formation of neuromuscular
junctions (NMJs). Anomalies in NMJ structure and function have not been
investigated in patients with Escobar syndrome. We report five patients
identified as having Escobar syndrome, from four families. In three families,
the same mutation (c.459dupA) was identified in CHRNG. A biopsy from
brachioradialis muscle was collected from a patient from one of these families
and analyzed for NMJ organization using fluorescence microscopy. Compared to
spinalis muscle from control patients with idiopathic scoliosis or cerebral
palsy (CP), the patient with Escobar syndrome had a significantly higher degree
of acetylcholine receptor present outside acetylcholinesterase and significantly
less acetylcholinesterase outside acetylcholine receptors. Given the role of the
acetylcholine receptor γ-subunit in fetal neuromuscular signal transduction and
in establishing the primary encounter of muscle and motor nerve terminal, the
CHRNG mutations described in Escobar syndrome may cause a broader disruption of
postsynaptic proteins and result in aberrant development of the NMJ due to
impaired prenatal neuromuscular transmission and/or abnormal neuromuscular
synaptogenesis. Several previous studies have evaluated the association between rs1149048
polymorphism in the matrilin-1 gene (MATN1) and the risk of adolescent
idiopathic scoliosis (AIS). However the results of those studies were
inconsistent. We conducted this meta-analysis to assess whether rs1149048
polymorphism was involved in the risk of AIS and evaluated the associations in
different ethnicities. Electronic databases, such as: PubMed, EMBASE, WANFANG
databases in any languages up to Dec 2012 were searched to assess the
association between rs1149048 polymorphism and AIS. Meta-analysis was performed
by STATA 12.0 software to estimate the pooled odds ratio (OR) and the 95 %
confidence interval (CI). Finally four papers including five studies which
involved 1436 AIS patients and 1,879 controls were identified for this
meta-analysis. The results showed that G allele of the rs1149048 was
significantly associated with increased AIS risk [OR = 1.13, 95 % CI
(1.02-1.25), P = 0.023]. As for genotype (GG vs. GA + AA), homozygous GG
genotype was also found to be a risk factor of developing AIS. The subgroup
meta-analysis results showed G allele and GG genotype were significantly
associated with AIS in Asian group but not in Caucasian group. Neither Egger's
test nor Begg's test found evidence of publication bias in current study (P >
0.05). In summary, this meta-analysis found an overall significant association
of rs1149048 polymorphism with risk of AIS, especially in Asian population. The
relationship between rs1149048 polymorphism and AIS in other ethnic population
is needed to be investigated. OBJECTIVE: Idiopathic scoliosis is the most common pediatric spinal deformity
affecting 1% to 3% of the population, and adolescent idiopathic scoliosis (AIS)
accounts for approximately 80% of these cases; however, the etiology and
pathogenesis of AIS are still uncertain. The current study aims to identify the
relationship between calmodulin 1 (CALM1) gene and AIS predisposition, to
identify the relationship between the genotypes of the SNPs and the clinical
phenotypes of AIS.
METHODS: 146 AIS patients and 146 healthy controls were enrolled into this
case-control study. 12 single nucleotide polymorphisms (SNPs) candidates in
CALM1 gene were selected to determine the relationship between CALM1 gene and
AIS predisposition. Case-only study was performed to determine the effects of
these variants on the severity of the condition.
RESULTS: Three SNPs from 12 candidates were found to be associated with AIS
predisposition. The ORs were observed as 0.549 (95% CI 0.3519-0.8579, P =
0.0079), 0.549 (95% CI 0.3519-0.8579, P = 0.0079), and 1.6139 (95% CI
1.0576-2.4634, P = 0.0257) for rs2300496, rs2300500, and rs3231718,
respectively. There was no statistical difference between main curve, severity,
and genotype distributions of all of 12 SNPs.
CONCLUSION: Genetic variants of CALM1 gene are associated with AIS
susceptibility. Adolescent idiopathic scoliosis (AIS) causes spinal deformity in 3% of children.
Despite a strong genetic basis, few genes have been associated with AIS and the
pathogenesis remains poorly understood. In a genome-wide rare variant burden
analysis using exome sequence data, we identified fibrillin-1 (FBN1) as the most
significantly associated gene with AIS. Based on these results, FBN1 and a
related gene, fibrillin-2 (FBN2), were sequenced in a total of 852 AIS cases and
669 controls. In individuals of European ancestry, rare variants in FBN1 and
FBN2 were enriched in severely affected AIS cases (7.6%) compared with in-house
controls (2.4%) (OR = 3.5, P = 5.46 × 10(-4)) and Exome Sequencing Project
controls (2.3%) (OR = 3.5, P = 1.48 × 10(-6)). Scoliosis severity in AIS cases
was associated with FBN1 and FBN2 rare variants (P = 0.0012) and replicated in
an independent Han Chinese cohort (P = 0.0376), suggesting that rare variants
may be useful as predictors of curve progression. Clinical evaluations revealed
that the majority of AIS cases with rare FBN1 variants do not meet diagnostic
criteria for Marfan syndrome, though variants are associated with tall stature
(P = 0.0035) and upregulation of the transforming growth factor beta pathway.
Overall, these results expand our definition of fibrillin-related disorders to
include AIS and open up new strategies for diagnosing and treating severe AIS. Most researchers agree that idiopathic scoliosis (IS) is a multifactorial
disease influenced by complex genetic and environmental factors. The onset of
the spinal deformity that determines the natural course of the disease, usually
occurs in the juvenile or adolescent period. Transforming growth factors β
(TGF-βs) and their receptors, TGFBRs, may be considered as candidate genes
related to IS susceptibility and natural history. This study explores the
transcriptional profile of TGF-βs, TGFBRs, and TGF-β responsive genes in the
paravertebral muscles of patients with juvenile and adolescent idiopathic
scoliosis (JIS and AIS, resp.). Muscle specimens were harvested intraoperatively
and grouped according to the side of the curve and the age of scoliosis onset.
The results of microarray and qRT-PCR analysis confirmed significantly higher
transcript abundances of TGF-β2, TGF-β3, and TGFBR2 in samples from the curve
concavity of AIS patients, suggesting a difference in TGF-β signaling in the
pathogenesis of juvenile and adolescent curves. Analysis of TGF-β responsive
genes in the transcriptomes of patients with AIS suggested overrepresentation of
the genes localized in the extracellular region of curve concavity: LTBP3,
LTBP4, ITGB4, and ITGB5. This finding suggests the extracellular region of
paravertebral muscles as an interesting target for future molecular research
into AIS pathogenesis. Idiopathic scoliosis occurs in 3% of individuals and has an unknown etiology.
The objective of this study was to identify rare variants that contribute to the
etiology of idiopathic scoliosis by using exome sequencing in a
multigenerational family with idiopathic scoliosis. Exome sequencing was
completed for three members of this multigenerational family with idiopathic
scoliosis, resulting in the identification of a variant in the HSPG2 gene as a
potential contributor to the phenotype. The HSPG2 gene was sequenced in a
separate cohort of 100 unrelated individuals affected with idiopathic scoliosis
and also was examined in an independent idiopathic scoliosis population. The
exome sequencing and subsequent bioinformatics filtering resulted in 16
potentially damaging and rare coding variants. One of these variants,
p.Asn786Ser, is located in the HSPG2 gene. The variant p.Asn786Ser also is
overrepresented in a larger cohort of idiopathic scoliosis cases compared with a
control population (P = 0.024). Furthermore, we identified additional rare HSPG2
variants that are predicted to be damaging in two independent cohorts of
individuals with idiopathic scoliosis. The HSPG2 gene encodes for a ubiquitous
multifunctional protein within the extracellular matrix in which loss of
function mutation are known to result in a musculoskeletal phenotype in both
mouse and humans. Based on these results, we conclude that rare variants in the
HSPG2 gene potentially contribute to the idiopathic scoliosis phenotype in a
subset of patients with idiopathic scoliosis. Further studies must be completed
to confirm the effect of the HSPG2 gene on the idiopathic scoliosis phenotype. |
Can botulism poisoning of a pregnant woman harm her fetus? | Botulinum toxin, which causes botulism, is not expected to be present in systemic circulation following proper intramuscular or intradermal injection. Moreover, botulinum toxin has a high molecular weight, and does not appear to cross the placenta. Based on the study cases reported in the literature, botulism poisoning during pregnancy does not appear to increase the risk of adverse outcome in the fetus. | During 1985-2005, a total of 91 laboratory-confirmed outbreaks of foodborne
botulism occurred in Canada; these outbreaks involved 205 cases and 11 deaths.
Of the outbreaks, 75 (86.2%) were caused by Clostridium botulinum type E,
followed by types A (7, 8.1%) and B (5, 5.7%). Approximately 85% of the
outbreaks occurred in Alaska Native communities, particularly the Inuit of
Nunavik in northern Quebec and the First Nations population of the Pacific coast
of British Columbia. These populations were predomitly exposed to type E
botulinum toxin through the consumption of traditionally prepared marine mammal
and fish products. Two botulism outbreaks were attributed to commercial
ready-to-eat meat products and 3 to foods served in restaurants; several cases
were attributed to non-Native home-prepared foods. Three affected pregt women
delivered healthy infants. Improvements in botulism case identification and
early treatment have resulted in a reduction in the case-fatality rate in
Canada. |
List the off-label use of SSRIs | depression during childhood and adolescence
Premature ejaculation (PE)
erectile dysfunction
Insomnia
postprostatectomy established stress urinary incontinence.
mood and anxiety disorders during pregnancy and breast feeding
symptoms of vasomotor dysregulation (hot flashes) associated with the menopausal transition and sex hormone deprivation
..off-label uses include the treatment of bulimia, benzodiazepine/alcohol dependence, fibromyalgia, central nervous system degenerative diseases (behavioral disorders in dementia and other organic disorders), schizophrenia, chronic pain disease and diabetic neuropathy, sexual dysfunction. | BACKGROUND: The last few years have seen a remarkable rise in the off-label use
of trazodone for inducing sleep in nondepressed patients, to a degree that it is
prescribed for this purpose as commonly as the leading hypnotic. In view of this
widespread popularity, it seems prudent to review what is known of the safety
and efficacy of trazodone when used in this context.
DATA SOURCES AND SELECTION: A MEDLINE search of the literature published in
English between 1975 and 2003 that included the keywords sleep, trazodone,
Desyrel, depression, sleeping pill, and sedative-hypnotics was conducted.
DATA SYNTHESIS: From this review, it is concluded that there are very few data
to suggest that trazodone improves sleep in patients without mood disorder,
though it does increase total sleep in patients with major depressive disorder.
There are virtually no dose-response data for trazodone vis-à-vis sleep and,
similarly, no available data on tolerance to its possible hypnotic effects.
Areas of concern with its use include reports of significant dropout rates and
induction of arrhythmias, primarily in patients with histories of cardiac
disease, as well as the development of priapism.
CONCLUSION: In summary, there are few data to support the use of trazodone in
nondepressed subjects. When the risk-benefit ratio of trazodone is assessed, its
side effect profile, which is much more significant than that of conventional
hypnotics, should be considered. Mood and anxiety disorders are common in women during their childbearing years.
The prevalence of depression has been reported to be between 10% and 16% during
pregcy. The use of selective serotonin reuptake inhibitors during pregcy
or lactation is, to date, not promoted because of lack of safety documentation.
However, the off-label use of these drugs has been common for several years. In
the treatment of mood and anxiety disorders during pregcy, the serotonin
reuptake inhibitors are often preferred over tricyclic antidepressants because
of their relatively few adverse effects and safety in overdose. This has created
concern among women planning pregcies and pregt women, as well as among
their families and physicians. Several studies and reports of the use of
serotonin reuptake inhibitors during both pregcy and lactation have been
published and advanced our knowledge. We here review and discuss those studies
which have been published so far on this subject. The landscape has dramatically changed for patients seeking treatment for rapid
ejaculation. Previously, psychotherapy or behavioral treatment was considered to
be the treatment of choice for this troubling sexual dysfunction. Since the
early 1990s, an efficacious alternative treatment has emerged-the off-label
administration of SSRI medications. Currently, several short-acting SSRI
compounds are in phase III clinical trials and are likely to receive approval as
the first medical treatment for rapid ejaculation. Given the presumed efficacy
of these new compounds and the off-label use of the current SSRIs, one might
conclude that psychotherapy\behavior therapy for rapid ejaculation is an
obsolete and antiquated intervention. On the contrary, psychotherapy is now more
relevant than ever. The two aims of this paper are to review
psychological/behavioral therapies for rapid ejaculation and to discuss the
important role of combined psychological and medical treatment. In the new age
of SSRI treatment for rapid ejaculation, some form of psychological/behavioral
intervention is essential to help patients/couples make better use of medical
therapies, to learn skills to delay ejaculation once off medication, to bolster
sexual confidence, and to enhance patient and partner sexual satisfaction. PURPOSE: Depression affects approximately 2-8% of all children and adolescents,
and treatment of depression in children and adolescents has been the center of
recent serious debates. We examined national trends in depression visits and
treatment among outpatients aged 7 to 17 years.
METHODS: We analyzed visit-based data between 1995 and 2002 in two national
ambulatory care surveys.
RESULTS: The number of visits by children and adolescents during which
depression was reported more than doubled from 1995-1996 (1.44 million) to
2001-2002 (3.22 million). The proportion of these visits during which
antidepressants were prescribed rose slightly from 47% in 1995-1996 to 52% in
2001-2002, whereas the proportion during which psychotherapy or mental health
counseling was provided declined from 83% to 68%. Selective serotonin reuptake
inhibitors (SSRI) represented 76% of all antidepressants prescribed in 1995-1996
and 81% in 2001-2002. In absolute terms, SSRIs were reported in 1.35 million
visits in 2001-2002, reflecting a 2.6-fold increase from 1995-1996. Fluoxetine
was prescribed in 207,914 visits in 1995-1996 and increased 100% to 415,580
visits in 2001-2002. The use of sertraline increased by 62% to 345,576 visits
and paroxetine by 269% to 279,275 visits.
CONCLUSIONS: We observed a declining trend in the provision of
psychotherapy/mental health counseling during outpatient visits by children and
adolescents diagnosed with depression. Although the likelihood of receiving
antidepressants remained essentially unchanged, the number of children and
adolescents whose visits involved prescription of antidepressants, particularly
SSRIs, has increased markedly through 2002. Although fluoxetine remained the
most commonly prescribed, other SSRIs were increasingly prescribed through 2002.
These trends raise concerns regarding the widespread off-label use of
antidepressants lacking reliable evidence of safety and efficacy for use in
children and adolescents. Premature ejaculation (PE) is the most common male sexual disorder, estimated to
affect up to 30% of men. Over the past one or two decades, clinical
investigators have participated in an increasing number of studies that are
helping in our understanding of PE, which will undoubtedly facilitate future
treatments. Apart from a number of behavioral approaches, the treatment of PE
consists of primarily off-label use of oral selective serotonin reuptake
inhibitors (SSRIs) via either on-demand or daily delivery. However, various
undesirable side-effects of these medications have led researchers to search for
and develop new therapeutic approaches for PE. Dapoxetine is a short-acting SSRI
developed specifically for the treatment of PE. Early trials with dapoxetine
have documented successful outcomes without serious short- or long-term
side-effects. This review addresses the definition, classification, diagnosis,
physiology, and neurobiopathology of PE, and evaluates therapeutic strategies
with novel treatments for PE. INTRODUCTION: The manufacturer of dapoxetine funded randomized clinical trials
to study its effect in premature ejaculation (PE). Ficial support by
pharmaceutical companies, however, may jeopardize the neutrality of clinical
research.
AIM: To investigate the scientific process that has been followed in dapoxetine
treatment trials and reviews as compared to daily drug treatment trials and
reviews with selective serotonin reuptake inhibitors (SSRIs) in men with PE.
METHODS: A search of Medline and Embase was conducted using the search terms
"dapoxetine" or "SSRI." References of retrieved articles were searched. Only
studies describing the use of these drugs in men with PE were included. Main
Outcome Measures. Compared fold-increase intravaginal ejaculation latency time
(IELT), geometric mean IELT, and adverse effect profiles between dapoxetine and
SSRIs in PE.
RESULTS: Preclinical studies on dapoxetine, including a multicenter study
(category A) and reviews (category B), were compared with clinical studies with
daily conventional SSRIs in PE (category C). Categories A/B focused on
patient-reported outcomes with less attention for the IELT. The
ejaculation-delaying effect of dapoxetine was expressed as natural mean IELT
rather than as geometrical mean IELT. Dapoxetine side effects were monthly
scored. In contrast, a significant part of category C articles focused on IELT
data, used geometric mean IELT outcomes, and one study reported the side effects
measured 24-48 hours after drug intake using a validated questionnaire. Without
the Food and Drug Administration approval, dapoxetine, as well as other SSRIs in
PE, is an off-label drug for PE. However, the off-label use of dapoxetine has
never been criticized by clinical investigators in contrast to commentaries
against the off-label use of daily SSRI treatment in PE.
CONCLUSIONS: Manufacturer-funded drug treatment research (categories A and B) is
advantageously treated by some authors as compared with nonfunded trials with
daily conventional SSRIs (category C). PE drug treatment research is a young and
dynamic field, and its development deserves transparency to its development. Phosphodiasterase type 5 inhibitors (sildenafil, vardenafil, tadalafil) are the
first line symptomatic therapy for patients with erectile dysfunction. The
patient should receive a meticolous information on the use of these drugs and
their possible side effects. These drugs are safe and can be used even in
patients with stable cardiovascular disease. Patients not responding to oral
drugs may be offered intraurethral or intracavernous alprostadil. Vacuum
constriction devices are a second line option more acceptable to older patients.
Penile prosthesis are very seldom used in Switzerland and vascular surgery is a
vanishing option. Testosterone substitution is seldom needed in this setting.
Treatment of premature ejaculation subdivides into behavioural therapy
("stop-start" or "squeeze" technique) and drug therapy as well. Topical therapy
with lidocaine/prilocaine-containing medications to be applied before sexual
intercourse and a oral daily off label use therapy with selective serotonin
re-uptake inhibitors (paroxetine, fluoxetine, sertraline) can be offered.
Dapoxetine, a potent selective serotonin reuptake inhibitor with short half life
time, is the first officially approved medication for the treatment of premature
ejaculation and should be available soon in Switzerland. Fibromyalgia (FM) is a common syndrome characterised by widespread pain and at
least 11/18 painful tender points that requires multimodal pharmacological
treatment also combined with non-pharmacological therapy. Various drugs
currently are available to control the complex and different symptoms reported
by patients. Only three drugs (duloxetine, milnacipram, pregabalin) are approved
by the American Food and Drug Administration (FDA) and none by the European
Medicines Agency (EMEA), consequently, off-label use is habitual in Europe. Most
of the drugs improve only one or two symptoms; no drug capable of overall
symptom control is yet available. Furthermore, different classes of drugs with
different mechanisms of action are used off-label, including tricyclic
antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs),
serotonin norepinephrine reuptake inhibitors (SNRIs), opioids, non-steroidal
anti-inflammatory drugs (NSAIDs), growth hormone, corticosteroids and sedative
hypnotics. As no single drug fully manages FM symptoms, multicomponent therapy
should be used from the beginning. Various pharmacological treatments have been
used to treat FM with inconclusive results, and gradually increasing low doses
is suggested in order to maximise efficacy. The best treatment should be
individualised and combined with patient education and non-pharmacological
therapy. OBJECTIVE: Estrogen supplementation is considered a reliable therapeutic
approach to symptoms of vasomotor dysregulation (hot flashes) associated with
the menopausal transition and sex hormone deprivation. Implication of changes in
central neurotransmission in the pathogenesis of hot flashes has prompted the
off-label use of serotonergic and γ-aminobutyric acid-ergic drugs as a
therapeutic alternative, claiming similarity of outcomes to those of estrogen
treatment.
METHODS: Using telemetric recordings in a rat model of estrogen deficit-induced
vasomotor dysregulation, we compared the long- and short-term effects of
estrogen supplementation and treatment with neuropharmaceuticals (venlafaxine,
desvenlafaxine, fluoxetine, agomelatine, gabapentin) on endpoints of
thermoregulation.
RESULTS: Among the tested drugs, only fluoxetine was capable to emulate the
restorative action of estradiol on the diurnal oscillations in skin temperature
and control of heat dissipation. Unlike estradiol, several of the tested
compounds produced marked transient decreases in skin temperature within the
first 2 hours of application while being unable to restore physiological diurnal
patterns of thermoregulation.
CONCLUSIONS: Our findings suggest that in this animal model of impaired
thermoregulation, neuropharmaceuticals may simulate therapeutic effects by
eliciting immediate but transient hypothermia, which is not associated with the
recovery of physiological control of heat dissipation. Therefore, short-term
monitoring of drug actions in this disease model may considerably bias readouts
of drug discovery for menopausal vasomotor symptoms. INTRODUCTION: Trazodone is an antidepressant belonging to the class of serotonin
receptor antagonists and reuptake inhibitors. It is approved by the FDA for the
treatment of depression. Insomnia is the most frequent reason for prescription
of trazodone. It has also been proven useful in the treatment of anxiety
disorders. Other off-label uses include the treatment of bulimia,
benzodiazepine/alcohol dependence, fibromyalgia, central nervous system
degenerative diseases (behavioral disorders in dementia and other organic
disorders), schizophrenia, chronic pain disease and diabetic neuropathy, sexual
dysfunction.
AREAS COVERED: This paper evaluates trazodone's efficacy and safety in its
off-label uses. It also discusses the possibility that a combination of
trazodone with SSRIs may prevent or treat some of the SSRI side effects, such as
anxiety, insomnia and sexual dysfunction, in addition to synergically increasing
SSRIs' antidepressant activity.
EXPERT OPINION: Few clinical trials have been conducted to evaluate trazodone's
efficacy in the treatment of the diseases and symptoms for which it is often
used in clinical practice. More studies are necessary to investigate possible
new therapeutic indications, and to scientifically demonstrate the risk/benefit
ratio for the many conditions for which trazodone is used, but not approved by
the FDA. BACKGROUND: The scheduled update to the German S3 guidelines on fibromyalgia
syndrome (FMS) by the Association of the Scientific Medical Societies
("Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften",
AWMF; registration number 041/004) was planned starting in March 2011.
MATERIALS AND METHODS: The development of the guidelines was coordinated by the
German Interdisciplinary Association for Pain Therapy ("Deutsche
Interdisziplinären Vereinigung für Schmerztherapie", DIVS), 9 scientific medical
societies and 2 patient self-help organizations. Eight working groups with a
total of 50 members were evenly balanced in terms of gender, medical field,
potential conflicts of interest and hierarchical position in the medical and
scientific fields. Literature searches were performed using the Medline,
PsycInfo, Scopus and Cochrane Library databases (until December 2010). The
grading of the strength of the evidence followed the scheme of the Oxford Centre
for Evidence-Based Medicine. The recommendations were based on level of
evidence, efficacy (meta-analysis of the outcomes pain, sleep, fatigue and
health-related quality of life), acceptability (total dropout rate), risks
(adverse events) and applicability of treatment modalities in the German health
care system. The formulation and grading of recommendations was accomplished
using a multi-step, formal consensus process. The guidelines were reviewed by
the boards of the participating scientific medical societies.
RESULTS AND CONCLUSION: Amitriptyline and-in case of comorbid depressive
disorder or generalized anxiety disorder-duloxetine are recommended. Off-label
use of duloxetine and pregabalin can be considered in case of no comorbid mental
disorder. Strong opioids are not recommended. The English full-text version of
this article is available at SpringerLink (under "Supplemental"). Premature ejaculation (PE) is a common sexual dysfunction affecting 20% to 30%
of men worldwide. Definitions of PE vary, but it is typically characterized by
short intravaginal ejaculatory latency time (IELT) with concomitant sexual
dissatisfaction and distress. PE may be lifelong or acquired, but its etiology
remains unclear. Treatment of PE typically involves pharmacotherapy,
particularly when lifelong. Although there are numerous reports on the off-label
use of selective serotonin reuptake inhibitors (SSRIs) and other compounds, only
2 treatments have been evaluated in randomized controlled phase 3 clinical
trials: PSD502 and dapoxetine (SSRI). Both significantly improved IELT and
patient-reported outcome domains of ejaculatory control, sexual satisfaction,
and distress as measured by the index of premature ejaculation (IPE), compared
with placebo. They constitute the focus of this review. Evidence demonstrated
that PSD502, dapoxetine and other SSRIs all significantly improve the symptoms
of PE. Systemic use of SSRIs presents risks associated with the known
pharmacology of this class. PSD502 allows for topical on-demand treatment
applied applied immediately before intercourse, and is not associated with
systemic adverse events. |
Which is the definition of pyknons in DNA? | Pyknons are non-random sequence patterns significantly repeated throughout non-coding genomic DNA, which have additional nonoverlapping instances in the untranslated and protein-coding regions. They are found more frequently in the 3' untranslated regions of genes than in other regions of the human genome. | We describe current research that applies epigenetics to a novel understanding
of the immuno-neuropathogenesis of HIV-1 viral infection and NeuroAIDS. We
propose the hypothesis that HIV-1 alters the structure-function relationship of
chromatin, coding DNA and non-coding DNA, including RNA transcribed from these
regions resulting in pathogenesis in AIDS, drug abuse, and NeuroAIDS. We discuss
the general implications of molecular epigenetics with special emphasis on drug
abuse, bar-codes, pyknons, and miRNAs for translational and clinical research.
We discuss the application of the recent recursive algorithm of biology to this
field and propose to synthesize the Genomic and Epigenomic views into a holistic
approach of HoloGenomics. Pyknons are non-random sequence patterns significantly repeated throughout
non-coding genomic DNA that also appear at least once among coding genes. They
are interesting because they portend an unforeseen connection between coding and
non-coding DNA. Pyknons have only been discovered in the human genome, so it is
unknown whether pyknons have wider biological relevance or are simply a
phenomenon of the human genome. To address this, DNA sequence patterns from the
Arabidopsis thaliana genome were detected using a probability-based method. 24
654 statistically significant sequence patterns, 16 to 24 nucleotides long,
repeating 10 or more times in non-coding DNA also appeared in 46% of A. thaliana
protein-coding genes. A. thaliana pyknons exhibit features similar to human
pyknons, including being distinct sequence patterns, having multiple instances
in genes and having remarkable similarity to small RNA sequences with roles in
gene silencing. Chromosomal position mapping revealed that genomic pyknon
density has concordance with siRNA and transposable element positioning density.
Because the A. thaliana and human genomes have approximately the same number of
genes but drastically different amounts of non-coding DNA, these data reveal
that pyknons represent a biologically important link between coding and
non-coding DNA. Because of the association of pyknons with siRNAs and
localization to silenced regions of heterochromatin, we postulate that
RNA-mediated gene silencing leads to the accumulation of gene sequences in
non-coding DNA regions. Small deletions and duplications frequently occur in the pericentromeric region
of chromosomes and many of these are associated with developmental
abnormalities. These developmental syndromes are conventionally attributed to
abnormal expression of protein-coding genes in the affected region. A hypothesis
has recently been published concerning a Master Development Program based on
noncoding transcripts from these regions (Parris GE. A hypothetical Master
Development Program for multi-cellular organisms: Ontogeny and phylogeny. Biosci
Hypotheses 2009;2:3-12.). This paper summarizes and expands the recently
published hypothesis to include it application to developmental diseases. The
author proposes that development of multi-cellular organisms is guided by a
Master Development Program (MDP) located primarily in the pericentromeric
heterochromatin. The MDP is believed to consist of a series of
Generation-Specific Control Keys (GSCK) transcribed in sequence by Ikaros family
transcription factors unless the GSCKs are suppressed by Sall1-family or
Dnmt3b-family proteins. The MDP is proposed to increment with each cell cycle to
the next GSCK resulting in development of the clone. A clone may be programmed
to split into two clones as necessary through a two-cycle mitosis processes. The
transcripts of the GSCKs presumably yield noncoding nuclear messenger RNAs
(nmRNAs, 8-30 nt units) that act directly (e.g., as primers for RNA polymerase
II) and indirectly to regulate HOX and other high-level transcription factor and
developmental genes. As envisioned, the MDP would evolve by terminal addition of
new GSCKs. The new GSCKs are produced by evolutionary consolidation of
retro-transcripts into pyknons that collect and evolve at the end of the
pericentromeric heterochromatin and are eventually incorporated into the MDP.
The retro-transcripts are though to be produced during episodic retrovirus
epidemics and account for punctuated equilibrium in species evolution. |
Does a linker histone exist in the yeast genome? | Here, we present our results showing a connection between the linker histones, the higher-order chromatin structures, and the process of chronological lifespan of yeast cells. Characteristically, linker histone depleted chromatin generally exhibited longer chromatin loops than the wild-type. These results suggest that HHO1p may play a similar role to linker histones, but at restricted locations in the chromatin. The binding was structure specific, since the use of double-stranded DNA, or a mutant Hho1p in which the second DNA binding site of globular domain 1 was abolished, resulted in a significant decrease in bridged binding. | There is currently no published report on the isolation and definitive
identification of histone H1 in Saccharomyces cerevisiae. It was, however,
recently shown that the yeast HHO1 gene codes for a predicted protein homologous
to H1 of higher eukaryotes (Landsman, D. (1996) Trends Biochem. Sci. 21,
287-288; Ushinsky, S. C., Bussey, H. , Ahmed, A. A., Wang, Y., Friesen, J.,
Williams, B. A., and Storms, R. K. (1997) Yeast 13, 151-161), although there is
no biochemical evidence that shows that Hho1p is, indeed, yeast histone H1. We
showed that purified recombit Hho1p (rHho1p) has electrophoretic and
chromatographic properties similar to linker histones. The protein forms a
stable ternary complex with a reconstituted core di-nucleosome in vitro at molar
rHho1p:core ratios up to 1. Reconstitution of rHho1p with H1-stripped chromatin
confers a kinetic pause at approximately 168 base pairs in the micrococcal
nuclease digestion pattern of the chromatin. These results strongly suggest that
Hho1p is a bona fide linker histone. We deleted the HHO1 gene and showed that
the strain is viable and has no growth or mating defects. Hho1p is not required
for telomeric silencing, basal transcriptional repression, or efficient
sporulation. Unlike core histone mutations, a hho1Delta strain does not exhibit
a Sin or Spt phenotype. The absence of Hho1p does not lead to a change in the
nucleosome repeat length of bulk chromatin nor to differences in the in vivo
micrococcal nuclease cleavage sites in individual genes as detected by primer
extension mapping. Biochemical studies to date have not been able to identify the linker histone H1
protein in the budding yeast Saccharomyces cerevisiae. Database homology
searching against the complete yeast genome has identified a gene, HHO1, (or
YPL127C, formerly LPI17) which encodes a protein that has two regions that show
similarity to the pea histone H1 globular domain. To determine whether Hho1p can
assume the shape of an H1 protein, homology model building experiments were
performed using the structure of chicken histone H5 globular domain as the basis
for comparison. A statistically significant match between each of the two
globular domains of Hho1p and the chicken histone H5 structure was obtained, and
probability values indicate that there is a less than 1 in 100 chance that such
a match would be the result of a random event. These findings support the
proposal that Hho1p acts as an "H1 dimer" and could be responsible for the
decreased linker DNA length observed between nucleosomal core particles. In virtually all eukaryotic organisms, linker DNA between nucleosomes is
associated with a histone termed linker histone or histone H1. In Saccharomyces
cerevisiae, HHO1 encodes a putative linker histone with very significant
homology to histone H1. The encoded protein is expressed in the nucleus, but has
not been shown to affect global chromatin structure, nor has its deletion shown
any detectable phenotype. In vitro chromatin assembly experiments with
recombit HHO1p have shown that it is able to complex with dinuncleosomes in a
similar manner to histone H1. Here we report that while disruption of HHO1 has
little affect on RNA levels of most cellular transcripts, there are numerous
exceptions. Measurement of HHO1p concentration in the wild-type cell showed a
stoichiometry of about one HHO1p molecule per 37 nucleosomes. Localization of
HHO1p in the chromatin, using an immunoprecipitation technique, showed
preferential HHO1p binding to rDNA sequences. These results suggest that HHO1p
may play a similar role to linker histones, but at restricted locations in the
chromatin. Saccharomyces cerevisiae encodes a single linker histone, Hho1p, with two
globular domains. This raised the possibility that Hho1p could bind to two
nucleosome cores simultaneously. To evaluate this idea, we studied the ability
of a four-way junction, immobilized on the surface of a magnetic bead, to pull
down a radiolabeled four-way junction in the presence of different Hho1
proteins. Four-way junctions are known to bind to H1, presumably due to
structure similarities to the DNA at the nucleosomal entry/exit point. We found
a significant increase in the ability of full-length Hho1p to pull down
radiolabeled four-way junction DNA under ionic conditions where both globular
domains could bind. The binding was structure specific, since the use of
double-stranded DNA, or a mutant Hho1p in which the second DNA binding site of
globular domain 1 was abolished, resulted in a significant decrease in bridged
binding. Additionally, bridged binding required a covalent attachment between
the two globular domains, since factor Xa protease treatment of the complex
formed by a modified Hho1p that contained a factor Xa cleavage site between the
two globular domains resulted in a significant release of radiolabeled four-way
junction. These findings demonstrated that the two globular domains
independently associated with two different four-way junction molecules in a
manner that required amino acid residues implicated in structure-specific
binding in the nucleosome. We discuss the implication of these findings on the
chromatin structure of yeast and propose a model where a single Hho1 protein
binds to two serially adjacent nucleosomes. Nucleosome core particles in eukaryotes are linked by a stretch of DNA that is
usually associated with a linker histone. Here, we show in yeast, that the
presence of yeast linker histone Hho1p represses expression of a pol II
transcribed gene (MET15) embedded in the rDNA. In vivo deletions of Hho1p
sequences showed that the second globular domain is sufficient for that
repression, whereas the presence of the N terminus is required for its
derepression. In contrast, a run-on assay confirmed by a ChIP experiment showed
that Hho1p is required for maximal pol I processivity during rDNA transcription.
Psoralen accessibility experiments indicated that Hho1p is necessary for normal
rDNA compaction. DNA array expression analysis comparing RNA transcripts in
wild-type and hho1 strains before and after a heat-shock showed that Hho1p is
necessary to achieve wild-type mRNA levels of transcripts that encode ribosomal
components. Taken together, our results suggest that Hho1p is involved in rDNA
compaction, and like core histones, is required for efficient rDNA transcription
by pol I. Saccharomyces cerevisiae linker histone Hho1p is not essential for cell
viability, and very little is known about its function in vivo. We show that
deletion of HHO1 (hho1Delta) suppresses the defect in transcriptional silencing
caused by a mutation in the globular domain of histone H4. hho1Delta also
suppresses the reduction in HML silencing by the deletion of SIR1 that is
involved in the establishment of silent chromatin at HML. We further show that
hho1Delta suppresses changes in silent chromatin structure caused by the histone
H4 mutation and sir1Delta. These results suggest that HHO1 plays a negative role
in transcriptionally silent chromatin. We also provide evidence that Hho1p
hinders the de novo establishment of silent chromatin but does not affect the
stability of preexistent silent chromatin. Unlike canonical linker histones in
higher eukaryotes that have a single conserved globular domain, Hho1p possesses
two globular domains. We show that the carboxyl-terminal globular domain of
Hho1p is dispensable for its function, suggesting that the mode of Hho1p action
is similar to that of canonical linker histones. Despite the existence of certain differences between yeast and higher eukaryotic
cells a considerable part of our knowledge on chromatin structure and function
has been obtained by experimenting on Saccharomyces cerevisiae. One of the
peculiarities of S. cerevisiae cells is the unusual and less abundant linker
histone, Hho1p. Sparse is the information about Hho1p involvement in yeast
higher-order chromatin organization. In an attempt to search for possible
effects of Hho1p on the global organization of chromatin, we have applied
Chromatin Comet Assay (ChCA) on HHO1 knock-out yeast cells. The results showed
that the mutant cells exhibited highly distorted higher-order chromatin
organization. Characteristically, linker histone depleted chromatin generally
exhibited longer chromatin loops than the wild-type. According to the Atomic
force microscopy data the wild-type chromatin appeared well organized in
structures resembling quite a lot the "30-nm" fiber in contrast to HHO1
knock-out yeast. The differentiation of gametes involves dramatic changes to chromatin, affecting
transcription, meiosis, and cell morphology. Sporulation in Saccharomyces
cerevisiae shares many chromatin features with spermatogenesis, including a
10-fold compaction of the nucleus. To identify new proteins involved in spore
nuclear organization, we purified chromatin from mature spores and discovered a
significant enrichment of the linker histone (Hho1). The function of Hho1 has
proven to be elusive during vegetative growth, but here we demonstrate its
requirement for efficient sporulation and full compaction of the spore genome.
Hho1 chromatin immunoprecipitation followed by sequencing (ChIP-seq) revealed
increased genome-wide binding in mature spores and provides novel in vivo
evidence of the linker histone binding to nucleosomal linker DNA. We also link
Hho1 function to the transcription factor Ume6, the master repressor of early
meiotic genes. Hho1 and Ume6 are depleted during meiosis, and analysis of
published ChIP-chip data obtained during vegetative growth reveals a high
binding correlation of both proteins at promoters of early meiotic genes.
Moreover, Ume6 promotes binding of Hho1 to meiotic gene promoters. Thus, Hho1
may play a dual role during sporulation: Hho1 and Ume6 depletion facilitates the
onset of meiosis via activation of Ume6-repressed early meiotic genes, whereas
Hho1 enrichment in mature spores contributes to spore genome compaction. Intricate, dynamic, and absolutely unavoidable ageing affects cells and
organisms through their entire lifetime. Driven by diverse mechanisms all
leading to compromised cellular functions and finally to death, this process is
a challenge for researchers. The molecular mechanisms, the general rules that it
follows, and the complex interplay at a molecular and cellular level are yet
little understood. Here, we present our results showing a connection between the
linker histones, the higher-order chromatin structures, and the process of
chronological lifespan of yeast cells. By deleting the gene for the linker
histone in Saccharomyces cerevisiae we have created a model for studying the
role of chromatin structures mainly at its most elusive and so far barely
understood higher-order levels of compaction in the processes of yeast
chronological lifespan. The mutant cells demonstrated controversial features
showing slower growth than the wild type combined with better survival during
the whole process. The analysis of the global chromatin organization during
different time points demonstrated certain loss of the upper levels of chromatin
compaction in the cells without linker histone. The results underlay the
importance of this histone for the maintece of the chromatin loop structures
during ageing. |
What is the role of deadenylases in the cell? | The 3'-poly(A) tail, found on mRNAs, is enzymatically shortened by a process referred to as "deadenylation" which is carried out by deadenylases. Deadenylases are magnesium dependent exoribonucleases that specifically catalyze the degradation of eukaryotic mRNA poly(A) tail in the 3'-->5' direction with the release of 5'-AMP as the product. They consist of three potential RNA-binding domains: the catalytic nuclease domain, the R3H domain and the RRM domain. | The CCR4 family proteins are 3'-5'-deadenylases that function in the first step
of the degradation of poly(A) mRNA. Here we report the purification to
homogeneity of the yeast CCR4 protein and the analysis of its substrate
specificities. CCR4 deadenylated a 7N+23A substrate (seven nucleotides followed
by 23 A residues) in a distributive manner. Only small differences in CCR4
activity for different A length substrates were observed until only 1 A residue
remained. Correspondingly, the K(m) for a 25N+2A substrate was found to be at
least 20-fold lower than that for a 26N+1A substrate, although their V(max)
values differed by only 2-fold. In addition, the total length of the RNA was
found to contribute to CCR4 activity: up to 17 nucleotides (not necessarily
poly(A)) could be recognized by CCR4. Poly(U), poly(C), and poly(G) were also
found to be 12-30-fold better inhibitors of CCR4 compared with poly(A),
supporting the observation that CCR4 contains a non-poly(A)-specific binding
site. Surprisingly, even longer substrates (>/=45 nucleotides) stimulated CCR4
to become a processive enzyme, suggesting that CCR4 undergoes an additional
transition in the presence of such substrates. CCR4 also displayed no difference
in its activity with capped or uncapped RNA substrates. These results indicate
that CCR4 recognition of its RNA substrates involves several features of the RNA
that could be sites in vivo for controlling the rate of specific mRNA
deadenylation. The stability of mRNAs is an important point in the regulation of gene
expression in eukaryotes. The mRNA turnover pathways have been identified in
yeast and mammals. However, mRNA turnover pathways in trypanosomes have not been
widely studied. Deadenylation is the first step in the major mRNA turnover
pathways of yeast and mammals. To better understand mRNA degradation processes
in these organisms, we have developed an in vitro mRNA turnover system that is
functional for deadenylation. In this system, addition of poly(A) homopolymer
activates the deadenylation of poly(A) tails. The trypanosomal deadenylase
activity is a 3'-->5' exonuclease specific for adenylate residues, generates
5'-AMP as a product, is magnesium dependent, and is inhibited by neomycin B
sulfate. These characteristics suggest similarity with other eukaryotic
deadenylases. Furthermore, this activity is cap independent, indicating a
potential difference between the trypanosomal activity and PARN, but suggesting
similarity to Ccr4p/Pop2p activities. Extracts immunodepleted of Pab1p required
the addition of poly(A) competition to activate deadenylation. Trypanosomal
Pab1p functions as an inhibitor of the activity under in vitro conditions. Pab1p
appears to be one of several mRNA stability proteins in trypanosomal extracts. Deadenylation of mRNA is often the first and rate-limiting step in mRNA decay.
PARN, a poly(A)-specific 3' --> 5' ribonuclease which is conserved in many
eukaryotes, has been proposed to be primarily responsible for such a reaction,
yet the importance of the PARN function at the whole-organism level has not been
demonstrated in any species. Here, we show that mRNA deadenylation by PARN is
essential for viability in higher plants (Arabidopsis thaliana). Yet, this
essential requirement for the PARN function is not universal across the
phylogenetic spectrum, because PARN is dispensable in Fungi (Schizosaccharomyces
pombe), and can be at least severely downregulated without any obvious
consequences in Metazoa (Caenorhabditis elegans). Development of the Arabidopsis
embryos lacking PARN (AtPARN), as well as of those expressing an enzymatically
inactive protein, was markedly retarded, and ultimately culminated in an arrest
at the bent-cotyledon stage. Importantly, only some, rather than all,
embryo-specific transcripts were hyperadenylated in the mutant embryos,
suggesting that preferential deadenylation of a specific select subset of mRNAs,
rather than a general deadenylation of the whole mRNA population, by AtPARN is
indispensable for embryogenesis in Arabidopsis. These findings indicate a
unique, nonredundant role of AtPARN among the multiple plant deadenylases. The majority of messenger RNA (mRNA) decay in mammalian cells appears to be the
work of a series of RNA exoribonucleases. A set of multiple poly(A)-specific
deadenylases has been identified, some, if not most, of which are likely to play
a role in the key first step of mRNA turnover--the regulated shortening of the
poly(A) tail. After deadenylation, the transcript likely gets degraded by either
a 5'-to-3' or a 3'-to-5' exonucleolytic pathway. Interestingly, multiple
exonucleases have been identified for both of these pathways that appear to form
multicomponent complexes with diverse roles in cellular biology. Therefore these
enzymes appear not only to be important components of the mRNA turnover
machinery, but also may function in a networked fashion in the
post-transcriptional control of gene expression. PUF proteins control gene expression by binding to the 3'-untranslated regions
of specific mRNAs and triggering mRNA decay or translational repression. Here we
focus on the mechanism of PUF-mediated regulation. The yeast PUF protein, Mpt5p,
regulates HO mRNA and stimulates removal of its poly(A) tail (i.e.
deadenylation). Mpt5p repression in vivo is dependent on POP2, a component of
the cytoplasmic Ccr4p-Pop2p-Not complex that deadenylates mRNAs. In this study,
we elucidate the individual roles of the Ccr4p and Pop2p deadenylases in
Mpt5p-regulated deadenylation. Both in vivo and in vitro, Pop2p and Ccr4p
proteins are required for Mpt5p-regulated deadenylation of HO. However, the
requirements for the two proteins differ dramatically: the enzymatic activity of
Ccr4p is essential, whereas that of Pop2p is dispensable. We conclude that Pop2p
is a bridge through which the PUF protein recruits the Ccr4p enzyme to the
target mRNA, thereby stimulating deadenylation. Our data suggest that PUF
proteins may enhance mRNA degradation and repress expression by both
deadenylation-dependent and -independent mechanisms, using the same Pop2p bridge
to recruit a multifunctional Pop2p complex to the mRNA. Deadenylation is the major step triggering mammalian mRNA decay. One consequence
of deadenylation is the formation of nontranslatable messenger RNA (mRNA)
protein complexes (messenger ribonucleoproteins [mRNPs]). Nontranslatable mRNPs
may accumulate in P-bodies, which contain factors involved in translation
repression, decapping, and 5'-to-3' degradation. We demonstrate that
deadenylation is required for mammalian P-body formation and mRNA decay. We
identify Pan2, Pan3, and Caf1 deadenylases as new P-body components and show
that Pan3 helps recruit Pan2, Ccr4, and Caf1 to P-bodies. Pan3 knockdown causes
a reduction of P-bodies and has differential effects on mRNA decay. Knocking
down Caf1 or overexpressing a Caf1 catalytically inactive mutant impairs
deadenylation and mRNA decay. P-bodies are not detected when deadenylation is
blocked and are restored when the blockage is released. When deadenylation is
impaired, P-body formation is not restorable, even when mRNAs exit the
translating pool. These results support a dynamic interplay among deadenylation,
mRNP remodeling, and P-body formation in selective decay of mammalian mRNA. In eukaryotic organisms, initiation of mRNA turnover is controlled by
progressive shortening of the poly-A tail, a process involving the mega-Dalton
Ccr4-Not complex and its two associated 3'-5' exonucleases, Ccr4p and Pop2p
(Caf1p). RNA degradation by the 3'-5' DEDDh exonuclease, Pop2p, is governed by
the classical two metal ion mechanism traditionally assumed to be dependent on
Mg(2+) ions bound in the active site. Here, we show biochemically and
structurally that fission yeast (Schizosaccharomyces pombe) Pop2p prefers Mn(2+)
and Zn(2+) over Mg(2+) at the concentrations of the ions found inside cells and
that the identity of the ions in the active site affects the activity of the
enzyme. Ion replacement experiments further suggest that mRNA deadenylation
could be subtly regulated by local Zn(2+) levels in the cell. Finally, we use
site-directed mutagenesis to propose a mechanistic model for the basis of the
preference for poly-A sequences exhibited by the Pop2p-type deadenylases as well
as their distributive enzymatic behavior. Deadenylation is the first and rate-limiting step during turnover of mRNAs in
eukaryotes. In the yeast, Saccharomyces cerevisiae, two distinct 3'-5'
exonucleases, Pop2p and Ccr4p, have been identified within the Ccr4-NOT
deadenylase complex, belonging to the DEDD and
Exonuclease-Endonuclease-Phosphatase (EEP) families, respectively. Ngl3p has
been identified as a new member of the EEP family of exonucleases based on
sequence homology, but its activity and biological roles are presently unknown.
Here, we show using in vitro deadenylation assays on defined RNA species
mimicking poly-A containing mRNAs that yeast Ngl3p is a functional 3'-5'
exonuclease most active at slightly acidic conditions. We further show that the
enzyme depends on divalent metal ions for activity and possesses specificity
towards poly-A RNA similar to what has been observed for cellular deadenylases.
The results suggest that Ngl3p is naturally involved in processing of
poly-adenylated RNA and provide insights into the mechanistic variations
observed among the redundant set of EEP enzymes found in yeast and higher
eukaryotes. BACKGROUND/AIMS: The degradation of mRNA is a key process in the control of gene
expression correlated to anomalous cell proliferation. The rate-limiting step of
mRNA degradation is the removal of the poly(A) tail by deadenylases. However,
studies on deadenylase expression in cancer are limited. Herein, we analyzed the
expression of several deadenylases from acute lymphoblastic leukemia (ALL) and
acute myeloid leukemia (AML).
METHODS: Clinical samples from patients diagnosed with ALL and AML were the
source of leukemic cells. Extracts from leukemic and control cells were analyzed
for deadenylase mRNA levels using qRT-PCR, and the protein levels of PARN and
CNOT7 deadenylases using immunoblotting.
RESULTS: RT-PCR analysis revealed altered expression for CNOT6, CNOT6L, CNOT7
and PARN deadenylases. The most significant alterations were observed for PARN
and CNOT7 mRNA levels, which also reflect on the cognate protein level. Further
analysis revealed that a significant amount of PARN is phosphorylated in ALL.
CONCLUSIONS: We show that the expression of several deadenylases in acute
leukemias is altered. The increase of PARN expression and the alteration of its
phosphorylation status indicate important regulatory events. These data suggest
that the role of deadenylases as auxiliary biomarkers and therapeutic targets
should be meticulously investigated. Deadenylation is the exoribonucleolytic shortening of eukaryotic poly(A) tails.
It is often the first and rate-limiting step for mRNA decay and translational
silencing. The process is catalysed by a diversity of deadenylases, which
provide robust and flexible means to control mRNA levels and gene expression.
Poly(A)-specific ribonuclease (PARN) is a major mammalian deadenylase and the
only known to concurrently bind the 5' cap-structure and the 3' poly(A), thus
enhancing the degradation rate and amplifying its processivity. PARN is
important during oocyte maturation, embryogenesis, early development, DNA
damage, and in cell-cycle progression, but also in processes beyond mRNA
metabolism, such as the maturation of snoRNAs. The enzyme also participates in
nonsense-mediated mRNA decay and in the regulation of cytoplasmic
polyadenylation. Importantly, PARN is involved in the degradation of several
cancer-related genes, while its expression is altered in cancer. Apart from the
direct interaction with the cap structure, several strategies regulate PARN
activity, such as phosphorylation, interaction with RNA-binding proteins (RBPs),
and natural nucleotides. Recent studies have focused on the regulation of its
activity by synthetic nucleoside analogues with therapeutic potential. In this
context, the wide repertoire of RBPs and molecules that regulate PARN activity,
together with the established role of deadenylases in miRNA-mediated regulation
of mRNA expression, suggest that mRNA turnover is more complex than it was
previously thought and PARN holds a key role in this process. In this review, we
highlight the importance of PARN during RNA's lifecycle and discuss clinical
perspectives of modulating its activity. PUF proteins are a conserved family of eukaryotic RNA-binding proteins that
regulate specific mRNAs: they control many processes including stem cell
proliferation, fertility, and memory formation. PUFs repress protein expression
from their target mRNAs but the mechanism by which they do so remains unclear,
especially for humans. Humans possess two PUF proteins, PUM1 and PUM2, which
exhibit similar RNA binding specificities. Here we report new insights into
their regulatory activities and mechanisms of action. We developed functional
assays to measure sequence-specific repression by PUM1 and PUM2. Both robustly
inhibit translation and promote mRNA degradation. Purified PUM complexes were
found to contain subunits of the CCR4-NOT (CNOT) complex, which contains
multiple enzymes that catalyze mRNA deadenylation. PUMs interact with the CNOT
deadenylase subunits in vitro. We used three approaches to determine the
importance of deadenylases for PUM repression. First, domit-negative mutants
of CNOT7 and CNOT8 reduced PUM repression. Second, RNA interference depletion of
the deadenylases alleviated PUM repression. Third, the poly(A) tail was
necessary for maximal PUM repression. These findings demonstrate a conserved
mechanism of PUF-mediated repression via direct recruitment of the CCR4-POP2-NOT
deadenylase leading to translational inhibition and mRNA degradation. A second,
deadenylation independent mechanism was revealed by the finding that PUMs
repress an mRNA that lacks a poly(A) tail. Thus, human PUMs are repressors
capable of deadenylation-dependent and -independent modes of repression. Eukaryotic releasing factor GSPT/eRF3 mediates translation termination-coupled
mRNA decay via interaction with a cytosolic poly(A)-binding protein (PABPC1). A
region of eRF3 containing two overlapping PAM2 (PABPC1-interacting motif 2)
motifs is assumed to bind to the PABC domain of PABPC1, on the poly(A) tail of
mRNA. PAM2 motifs are also found in the major deadenylases Caf1-Ccr4 and
Pan2-Pan3, whose activities are enhanced upon PABPC1 binding to these motifs.
Their deadenylase activities are regulated by eRF3, in which two overlapping
PAM2 motifs competitively prevent interaction with PABPC1. However, it is
unclear how these overlapping motifs recognize PABC and regulate deadenylase
activity in a translation termination-coupled manner. We used a
domit-negative approach to demonstrate that the N-terminal PAM2 motif is
critical for eRF3 binding to PABPC1 and that both motifs are required for
function. Isothermal titration calorimetry (ITC) and NMR analyses revealed that
the interaction is in equilibrium between the two PAM2-PABC complexes, where
only one of the two overlapping PAM2 motifs is PABC-bound and the other is
PABC-unbound and partially accessible to the other PABC. Based on these results,
we proposed a biological role for the overlapping PAM2 motifs in the regulation
of deadenylase accessibility to PABPC1 at the 3' end of poly(A). The degradation of most eukaryotic mRNAs is initiated by removal of the poly(A)
tail, and the major deadenylase activity is associated with the CCR4/CAF1/NOT
complex (NOT complex). We here study the role of CNOT10, a protein that is found
in human and trypanosome, but not in yeast, NOT complexes. Trypanosome (Tb)
CNOT10 is essential for growth. TbCNOT10 interacted with the deadenylase TbCAF1
and the scaffold protein TbNOT1; TbCAF1 also interacted with TbNOT1 in a yeast
two-hybrid assay. In both trypanosomes and human embryonic kidney cells,
approximately half of CAF1 was associated with the NOT complex. Depletion of
CNOT10 from human cells did not affect this association. In contrast, depletion
of TbCNOT10 in trypanosomes caused a decrease in the level of TbNOT1, detachment
of TbCAF1 from the complex and pronounced stabilization of most trypanosome
mRNAs. Artificial tethering of TbCAF1 to a reporter mRNA in vivo resulted in
mRNA degradation, and this was not affected by TbCNOT10 depletion. We conclude
that in trypanosomes, TbCNOT10 may stabilize the interaction between TbCAF1 and
the NOT complex. The results further suggest that TbCAF1 is only able to
deadenylate mRNA in vivo if it is recruited to the mRNA through other NOT
complex components. Deadenylation is the major step in triggering mRNA decay and results in mRNA
translation inhibition in eukaryotic cells. Therefore, it is plausible that
deadenylation also induces the mRNP remodeling required for formation of GW
bodies or RNA processing bodies (P-bodies), which harbor translationally
silenced mRNPs. In this chapter, we discuss several examples to illustrate the
roles of deadenylation in regulating gene expression. We highlight several lines
of evidence indicating that even though non-translatable mRNPs may be prepared
and/or assembled into P-bodies in different ways, deadenylation is always a
necessary, and perhaps the earliest, step in mRNA decay pathways that enable
mRNP remodeling required for P-body formation. Thus, deadenylation and the
participating deadenylases are not simply required for preparing mRNA
substrates; they play an indispensable role both structurally and functionally
in P-body formation and regulation. PARN, Nocturnin and Angel are three of the multiple deadenylases that have been
described in eukaryotic cells. While each of these enzymes appear to target
poly(A) tails for shortening and influence RNA gene expression levels and
quality control, the enzymes differ in terms of enzymatic mechanisms, regulation
and biological impact. The goal of this review is to provide an in depth
biochemical and biological perspective of the PARN, Nocturnin and Angel
deadenylases. Understanding the shared and unique roles of these enzymes in cell
biology will provide important insights into numerous aspects of the
post-transcriptional control of gene expression. This article is part of a
Special Issue entitled: RNA Decay mechanisms. Deadenylases specifically catalyze the degradation of eukaryotic mRNA poly(A)
tail in the 3'- to 5'-end direction with the release of 5'-AMP as the product.
Among the deadenylase family, poly(A)-specific ribonuclease (PARN) is unique in
its domain composition, which contains three potential RNA-binding domains: the
catalytic nuclease domain, the R3H domain and the RRM domain. In this research,
we investigated the roles of these RNA-binding domains by comparing the
structural features and enzymatic properties of mutants lacking either one or
two of the three RNA-binding domains. The results showed that the R3H domain had
the ability to bind various oligonucleotides at the micromolar level with no
oligo(A) specificity. The removal of the R3H domain dissociated PARN into
monomers, which still possessed the RNA-binding ability and catalytic functions.
Unlike the critical role of the RRM domain in PARN processivity, the removal of
the R3H domain did not affect the catalytic pattern of PARN. Our results
suggested that both R3H and RRM domains were essential for the high affinity of
long poly(A) substrate, but the R3H domain did not contribute to the substrate
recognition of PARN. Compared to the RRM domain, the R3H domain played a more
important role in the structural integrity of the dimeric PARN. The multiple
RNA-binding domain architecture endows PARN the property of highly efficient
catalysis in a highly processive mode. Deadenylation of eukaryotic mRNA is a mechanism critical for mRNA function by
influencing mRNA turnover and efficiency of protein synthesis. Here, we review
poly(A)-specific ribonuclease (PARN), which is one of the biochemically best
characterized deadenylases. PARN is unique among the currently known eukaryotic
poly(A) degrading nucleases, being the only deadenylase that has the capacity to
directly interact during poly(A) hydrolysis with both the m(7)G-cap structure
and the poly(A) tail of the mRNA. In short, PARN is a divalent metal-ion
dependent poly(A)-specific, processive and cap-interacting 3'-5' exoribonuclease
that efficiently degrades poly(A) tails of eukaryotic mRNAs. We discuss in
detail the mechanisms of its substrate recognition, catalysis, allostery and
processive mode of action. On the basis of biochemical and structural evidence,
we present and discuss a working model for PARN action. Models of regulation of
PARN activity by trans-acting factors are discussed as well as the physiological
relevance of PARN. |
What molecule is targeted by brodalumab? | Interleukin-17. Brodalumab is anti interleukin-17 monoclonal antibody. | BACKGROUND: In this phase 2, randomized, double-blind, placebo-controlled,
dose-ranging study, we assessed the efficacy and safety of brodalumab (AMG 827),
a human anti-interleukin-17-receptor monoclonal antibody, for the treatment of
moderate-to-severe plaque psoriasis.
METHODS: We randomly assigned patients with a score of 12 or higher on the
psoriasis area-and-severity index (PASI, on which scores range from 0 to 72,
with higher scores indicating more severe disease) and with 10% or more of their
body-surface area affected by psoriasis to receive brodalumab (70 mg, 140 mg, or
210 mg at day 1 and weeks 1, 2, 4, 6, 8, and 10 or 280 mg monthly) or placebo.
The primary end point was the percentage improvement from baseline in the PASI
score at week 12. Secondary end points included improvement of at least 75% and
at least 90% in the PASI score and the score on the static physician's global
assessment at week 12.
RESULTS: A total of 198 patients underwent randomization. At week 12, the mean
percentage improvements in the PASI score were 45.0% among patients receiving 70
mg of brodalumab, 85.9% among those receiving 140 mg, 86.3% among those
receiving 210 mg, 76.0% among those receiving 280 mg, and 16.0% among those
receiving placebo (P<0.001 for all comparisons with placebo). An improvement of
at least 75% and at least 90% in the PASI score at week 12 was seen in 77% and
72%, respectively, of the patients in the 140-mg brodalumab group and in 82% and
75%, respectively, of the patients in the 210-mg group, as compared with 0% in
the placebo group (P<0.001 for all comparisons). The percentage of patients with
a static physician's global assessment of clear or minimal disease was 26%, 85%,
80%, and 69% with the 70-mg, 140-mg, 210-mg, and 280-mg doses, respectively, of
brodalumab, as compared with 3% with placebo (P<0.01 for all comparisons with
placebo). Two cases of grade 3 neutropenia were reported in the 210-mg
brodalumab group. The most commonly reported adverse events in the combined
brodalumab groups were nasopharyngitis (8%), upper respiratory tract infection
(8%), and injection-site erythema (6%).
CONCLUSIONS: Brodalumab significantly improved plaque psoriasis in this 12-week,
phase 2 study. (Funded by Amgen; ClinicalTrials.gov number, NCT00975637.). RATIONALE: IL-17 signaling has been implicated in development and persistence of
asthma. Cytokine-targeted strategies blocking IL-17 receptor signaling may be
beneficial in asthma treatment.
OBJECTIVES: To determine efficacy and safety of brodalumab, a human anti-IL-17
receptor A monoclonal antibody, in subjects with inadequately controlled
moderate to severe asthma taking regular inhaled corticosteroids.
METHODS: Three hundred two subjects were randomized to brodalumab (140, 210, or
280 mg) or placebo. Primary endpoint was change in Asthma Control Questionnaire
(ACQ) score from baseline to Week 12. Secondary endpoints included FEV1, symptom
scores, and symptom-free days. Prespecified subgroup analyses were conducted to
identify potential responsive subpopulations. Analyses included randomized
subjects receiving one or more doses of investigational product using
last-observation-carried-forward imputation.
MEASUREMENTS AND MAIN RESULTS: Demographics and baseline characteristics were
generally balanced among groups (n = 302; n = 226 brodalumab). For the overall
study population, no treatment differences were observed. Nine prespecified
subgroups were examined without corrections for multiple testing. In only the
high-reversibility subgroup (post-bronchodilator FEV1 improvement ≥ 20%; n =
112) was an ACQ change with nominal significance noted; ACQ responses were
nominally significant in the 210-mg group (estimated treatment difference, 0.53)
but not significant in the higher 280-mg group (estimated treatment difference,
0.38). Adverse events, generally balanced among groups, were most commonly
asthma, upper respiratory tract infection, and injection site reaction.
CONCLUSIONS: Inhibition of IL-17 receptor A did not produce a treatment effect
in subjects with asthma. The results of the high-reversibility subgroup analysis
are of uncertain significance, requiring further study of brodalumab in this
asthma subpopulation. Clinical trial registered with www.clinicaltrials.gov
(NCT01199289). Abstract Background: Studies investigating the molecular basis of psoriasis have
established the central roles of TNFα, interleukin (IL)-12, IL-22 and IL-23 and
there is increasing evidence that IL-17 plays a critical role in the complex
pathophysiology. Preclinical studies suggest that IL-17 is a desirable
therapeutic target for psoriasis treatment.
METHODS: We reviewed the results of the phase II clinical trials for the
anti-IL-17 agents secukinumab, ixekizumab and brodalumab in order to assess the
efficacy and safety profile of each agent.
RESULTS: By week 12, the proportion of patients reaching Psoriasis Area and
Severity Index (PASI 75) was comparable among the most efficacious dosage
between the different agents (secukinumab 82%, ixekizumab 83% and brodalumab
82%; p<0.001 compared to placebo for all agents). The safety profiles of the
agents were similar with the most frequently reported adverse events of
nasopharyngitis, upper respiratory infections and injection site reaction. A
small percentage of patients experienced low-grade neutropenia that was
predomitly transient and asymptomatic.
CONCLUSION: The anti-IL-17 agents demonstrated a rapid and robust clinical
improvement accompanied by a favorable short-term safety profile. The results of
the phase II trials support the theory that the IL-17 pathway is an essential
target in psoriasis treatment. The IL-17 pathway is an established driver of psoriasis pathogenesis. We
examined the detailed molecular and cellular effects of blockade of IL-17
signaling in human psoriatic skin before and following treatment with
brodalumab, a competitive inhibitor of the IL-17 Receptor A subunit. Thousands
of aberrantly expressed genes in lesional skin normalized within 2 weeks
following brodalumab treatment, with conversion of the lesional psoriasis
transcriptome to resemble that seen in nonlesional skin. Keratinocyte-expressed
genes appeared to normalize rapidly, whereas T cell-specific normalization
occurred over six weeks. The three IL-17 ligand genes that are upregulated in
lesional skin, IL17A, IL17C, and IL17F, were all downregulated in a
dose-dependent manner following brodalumab treatment. Cellular measures also
showed a similar pattern with dramatic decreases in keratinocyte hyperplasia
within one week, and decreases in infiltrating leukocytes occurred over a longer
timescale. Individuals with the highest brodalumab exposure showed normalization
of both IL-17-responsive genes and the psoriasis transcriptome, whereas subjects
with lower exposures showed transient or incomplete molecular responses.
Clinical and molecular response appeared dependent on the extent of brodalumab
exposure relative to the expression of IL-17 ligand genes, and reduction of
IL-17 signaling into the nonlesional range was strongly correlated with
normalization of the psoriasis transcriptome. These data indicate that blockade
of IL-17 signaling in psoriatic skin leads to rapid transcriptomal changes
initially in keratinocyte-expressed genes, followed by normalization in the
leukocyte abnormalities, and demonstrates the essential role of the IL-17R on
keratinocytes in driving disease pathogenesis. BACKGROUND: We assessed the efficacy and safety of brodalumab, a human
monoclonal antibody against interleukin-17 receptor A (IL17RA), in a phase 2,
randomized, double-blind, placebo-controlled study involving patients with
psoriatic arthritis.
METHODS: We randomly assigned patients with active psoriatic arthritis to
receive brodalumab (140 or 280 mg subcutaneously) or placebo on day 1 and at
weeks 1, 2, 4, 6, 8, and 10. At week 12, patients who had not discontinued their
participation in the study were offered open-label brodalumab (280 mg) every 2
weeks. The primary end point was 20% improvement in American College of
Rheumatology response criteria (ACR 20) at week 12.
RESULTS: Of the 168 patients who underwent randomization (57 in the brodalumab
140-mg group, 56 in the brodalumab 280-mg group, and 55 in the placebo group),
159 completed the double-blind phase and 134 completed 40 weeks of the
open-label extension. At week 12, the brodalumab 140-mg and 280-mg groups had
higher rates of ACR 20 than the placebo group (37% [P=0.03] and 39% [P=0.02],
respectively, vs. 18%); they also had higher rates of 50% improvement (ACR 50)
(14% [P=0.05] and 14% [P=0.05] vs. 4%). Rates of 70% improvement were not
significantly higher in the brodalumab groups. Similar degrees of improvement
were noted among patients who had received previous biologic therapy and those
who had not received such therapy. At week 24, ACR 20 response rates in the
brodalumab 140-mg and 280-mg groups were 51% and 64%, respectively, as compared
with 44% among patients who switched from placebo to open-label brodalumab;
responses were sustained through week 52. At week 12, serious adverse events had
occurred in 3% of patients in the brodalumab groups and in 2% of those in the
placebo group.
CONCLUSIONS: Brodalumab significantly improved response rates among patients
with psoriatic arthritis. Larger studies of longer duration are necessary to
assess adverse events. (Funded by Amgen; ClinicalTrials.gov number, NCT01516957
.). Advances in knowledge regarding the pathogenesis of psoriasis have allowed the
development of a new class of agents known as biologic drugs. Data confirm that
T helper (Th)17 and interleukin (IL)-17 signaling has a crucial role in the
pathogenesis of the disease. High levels of IL-17 and Th17-related cytokines
have been reported in psoriasis, leading to the suggestion of agents targeting
IL-17 as a potential therapeutic strategy in psoriasis. Brodalumab is a human
monoclonal antibody that targets IL-17 receptor A, blocking the effects of
IL-17A, IL-17F, and IL-17E. Data from Phase I and Phase II clinical trials
indicate that brodalumab has a favorable safety and tolerability profile, with
strong clinical activity, suggesting that it is a potential tool for use in the
treatment of moderate-to-severe psoriasis. "Psoriasis" is a chronic immune-mediated inflammatory disorder with epidermal
hyperplasia. There is some evidence that the cytokine interleukin-17A (often
known as IL-17), which is mainly produced by Th17 cells, has a role in the
pathogenesis of psoriasis. "IL-17" is a pro-inflammatory cytokine mainly
important in the host's defense against extracellular bacteria and fungi. The
three new therapies with biologic drugs - brodalumab, secukinumab, and
ixekizumab - all target the IL-17 signaling pathway. Secukinumab and ixekizumab
neutralize IL-17A, while brodalumab blocks its receptor. Results from clinical
trials have shown marked improvements in disease severity in patients with
moderate-to-severe plaque psoriasis, using any of these three drugs. The
biologic agents were generally well tolerated, but the duration of the trials
was relatively short. In this review, we focus on the role of the IL-17 cytokine
family in the pathogenesis of psoriasis; the efficacy, safety, and tolerability
of brodalumab, secukinumab, and ixekizumab in clinical trials; and possible
differences between targeting of the IL-17A receptor and targeting of the IL-17A
ligand. PURPOSE OF REVIEW: In recent years, there has been an increasing understanding
of the importance of the TH17 lineage of T cells and related cytokines,
including interleukin (IL)17 and IL23, not only in the biology of innate host
defense but also in the pathogenesis of inflammatory/autoimmune diseases. These
diseases include psoriasis, psoriatic arthritis, the broader category of
spondyloarthritides including ankylosing spondylitis and rheumatoid arthritis.
It is postulated that in genetically predisposed individuals, external or
internal stimuli such as microbial antigens, alterations in the intestinal
microbiome, biomechanical stress and/or immunologic dysregulation may lead to an
increased expression of cytokines such as IL23, which in turn stimulate the
differentiation and activation of TH17 and other immune cells, which are a part
of the innate immune system that trigger adaptive immune processes and chronic
inflammatory diseases. Herein, we explore the effect of targeting this pathway
therapeutically.
RECENT FINDINGS: New drugs that are designed to inhibit steps in this pathway,
the IL12/IL23 inhibitor, ustekinumab, the IL17A inhibitors secukinumab and
ixekizumab, the IL17A receptor inhibitor, brodalumab, and the IL23 inhibitors
guselkumab and tildrakizumab, have demonstrated significant effectiveness in
treating these diseases, particularly psoriasis, psoriatic arthritis and
ankylosing spondylitis.
SUMMARY: This article reviews the relevant biology, efficacy and safety of new
medications targeting the TH17 pathway, including inhibition of IL17 and IL23,
particularly in psoriasis and psoriatic arthritis. Especially for patients who
have not gained benefit from, lost effectiveness to or could not use antitumour
necrosis factor (TNF) medications for safety or tolerability reasons, having
effective medicines with an alternative mechanism of action will improve our
ability to diminish disease activity impact on patient lives. Psoriasis is a common chronic inflammatory disease of the skin. Current biologic
therapies are highly effective in the treatment of psoriasis, transforming the
lives of patients with this significantly disabling disease. Advances in the
understanding of the immunological pathogenesis of psoriasis have led to the
development of new biologic therapies, targeting specific inflammatory cytokines
upregulated in psoriasis. These include the IL-17 antagonists, secukinumab,
brodalumab and ixekizumab; the IL-23 antagonists, guselkumab and tildrakizumab;
and the oral small molecule therapies, tofacitinib and apremilast. Here, we
review evidence for the efficacy and safety of these novel psoriasis therapies,
providing clinicians with an overview of the next era in immunotherapy for
psoriasis. BACKGROUND: Early clinical studies suggested that the anti-interleukin-17
receptor A monoclonal antibody brodalumab has efficacy in the treatment of
psoriasis.
METHODS: In two phase 3 studies (AMAGINE-2 and AMAGINE-3), patients with
moderate-to-severe psoriasis were randomly assigned to receive brodalumab (210
mg or 140 mg every 2 weeks), ustekinumab (45 mg for patients with a body weight
≤100 kg and 90 mg for patients >100 kg), or placebo. At week 12, patients
receiving brodalumab were randomly assigned again to receive a brodalumab
maintece dose of 210 mg every 2 weeks or 140 mg every 2 weeks, every 4 weeks,
or every 8 weeks; patients receiving ustekinumab continued to receive
ustekinumab every 12 weeks, and patients receiving placebo received 210 mg of
brodalumab every 2 weeks. The primary aims were to evaluate the superiority of
brodalumab over placebo at week 12 with respect to at least a 75% reduction in
the psoriasis area-and-severity index score (PASI 75) and a static physician's
global assessment (sPGA) score of 0 or 1 (clear or almost clear skin), as well
as the superiority of brodalumab over ustekinumab at week 12 with respect to a
100% reduction in PASI score (PASI 100).
RESULTS: At week 12, the PASI 75 response rates were higher with brodalumab at
the 210-mg and 140-mg doses than with placebo (86% and 67%, respectively, vs. 8%
[AMAGINE-2] and 85% and 69%, respectively, vs. 6% [AMAGINE-3]; P<0.001); the
rates of sPGA scores of 0 or 1 were also higher with brodalumab (P<0.001). The
week 12 PASI 100 response rates were significantly higher with 210 mg of
brodalumab than with ustekinumab (44% vs. 22% [AMAGINE-2] and 37% vs. 19%
[AMAGINE-3], P<0.001). The PASI 100 response rates with 140 mg of brodalumab
were 26% in AMAGINE-2 (P=0.08 for the comparison with ustekinumab) and 27% in
AMAGINE-3 (P=0.007). Rates of neutropenia were higher with brodalumab and with
ustekinumab than with placebo. Mild or moderate candida infections were more
frequent with brodalumab than with ustekinumab or placebo. Through week 52, the
rates of serious infectious episodes were 1.0 (AMAGINE-2) and 1.3 (AMAGINE-3)
per 100 patient-years of exposure to brodalumab.
CONCLUSIONS: Brodalumab treatment resulted in significant clinical improvements
in patients with moderate-to-severe psoriasis. (Funded by Amgen; AMAGINE-2 and
AMAGINE-3 ClinicalTrials.gov numbers, NCT01708603 and NCT01708629.). |
How long, in kb (kilobases), is a "Long interspersed nuclear element"? | The retrotransposon known as long interspersed nuclear element-1 (L1) is 6-7 kb long, | Leukemic cells of a patient diagnosed with chronic myeloid leukemia (CML) showed
a complex BCR-ABL1 rearrangement hidden within a normal appearing karyotype.
Previous molecular studies had established that the 3' BCR had recombined at a
novel site within the variable region of the immunoglobulin lambda locus ( IGL).
A segment of DNA mapping very close to the site of the IGL/3' BCR recombination
recognized a previously undescribed insertion polymorphism. A combination of
molecular hybridization studies and long-range polymerase chain reaction was
used to isolate a 6-kb full-length long interspersed nuclear element (LINE or
L1), here designated L1(IGL), which occupies 19% of alleles in the general
population. Although unclonable, DNA sequence analysis by a primer walking
approach established that L1(IGL) has features characteristic of an actively
retrotransposing element. The L1(IGL) element has a 5' untranslated region, two
open reading frames (ORF-1 and ORF-2), a 3' untranslated region and terminates
in a poly-A tail. We compared the DNA sequence and the predicted amino acid
sequence of L1(IGL) with a consensus sequence compiled from seven reported
active L1 elements. This analysis indicated that L1(IGL) has high potential for
involvement in as yet undetermined somatically and constitutionally acquired
disease, not only through recombination mechanisms, but also through
retrotransposition events. This full-length L1 element maps close within the
IGLlocus to L1.2, one of only nine active L1 elements that have been reported so
far. L1(IGL) and L1.2 map within a wider and well-recognized region of genomic
instability on chromosome 22. The retrotransposon known as long interspersed nuclear element-1 (L1) is 6 kb
long, although most L1s in mammalian and other eukaryotic cells are truncated.
L1 contains two open reading frames, ORF1 and ORF2, that code for an RNA-binding
protein and a protein with endonuclease and reverse transcriptase activities,
respectively. In this work, we examined the effects of full length L1-ORF2 and
ORF2 fragments on green fluorescent protein gene (GFP) expression when inserted
into the pEGFP-C1 vector downstream of GFP. All of the ORF2 fragments in sense
orientation inhibited GFP expression more than when in antisense orientation,
which suggests that small ORF2 fragments contribute to the distinct inhibitory
effects of this ORF on gene expression. These results provide the first evidence
that different 280-bp fragments have distinct effects on the termination of gene
transcription, and that when inserted in the antisense direction, fragment 280-9
(the 3' end fragment of ORF2) induces premature termination of transcription
that is consistent with the effect of ORF2. A typical eukaryotic genome harbors a rich variety of repetitive elements. The
most abundant are retrotransposons, mobile retroelements that utilize reverse
transcriptase and an RNA intermediate to relocate to a new location within the
cellular genomes. A vast majority of the repetitive mammalian genome content has
originated from the retrotransposition of SINE (100-300 bp short interspersed
nuclear elements that are derived from the structural 7SL RNA or tRNA), LINE
(7kb long interspersed nuclear element), and LTR (2-3 kb long terminal repeats)
transposable element superfamilies. Broadly labeled as "evolutionary junkyard"
or "fossils", this enigmatic "dark matter" of the genome possesses many yet to
be discovered properties. |
Which is the gene mutated in type 1 neurofibromatosis? | NF1 gene, encoding neurofibromin 1 | Neurofibromatosis type 1 (NF1) is caused by deletions, insertions,
translocations, and point mutations in the NF1 gene, which spans 350 kb on the
long arm of human chromosome 17. Although several point mutations have been
described, large molecular abnormalities have rarely been characterized in
detail. We describe here the molecular breakpoints of a 12-kb deletion of the
NF1 gene, which is responsible for the NF1 phenotype in a kindred with two
children affected because of germline mosaicism in the unaffected father, who
has the mutation in 10% of his spermatozoa. The mutation spans introns 31-39,
removing 12,021 nt and inserting 30 bp, of which 19 bp are a direct repetition
of a sequence located in intron 31, just 4 bp before the 5' breakpoint. The 5'
and 3' breakpoints contain the sequence TATTTTA, which could be involved in the
generation of the deletion. The most plausible explanation for the mechanism
involved in the generation of this 12-kb deletion is homologous/nonhomologous
recombination. Since sperm of the father does not contain the corresponding
insertion of the 12-kb deleted sequence, this deletion could have occurred
within the NF1 chromosome through loop formation. RNA from lymphocytes of one of
the NF1 patients showed similar levels of the mutated and normal transcripts,
suggesting that the NF1-mRNA from mutations causing frame shifts of the reading
frame or stop codons in this gene is not degraded during its processing. The
mutation was not detected in fresh lymphocytes from the unaffected father by PCR
analysis, supporting the case for true germ-line mosaicism. Lysine 1423 of neurofibromin (neurofibromatosis type I gene product [NF1]) plays
a crucial role in the function of NF1. Mutations of this lysine were detected in
samples from a neurofibromatosis patient as well as from cancer patients. To
further understand the significance of this residue, we have mutated it to all
possible amino acids. Functional assays using yeast ira complementation have
revealed that lysine is the only amino acid that produced functional NF1.
Quantitative analyses of different mutant proteins have suggested that their
GTPase-activating protein (GAP) activity is drastically reduced as a result of a
decrease in their Ras affinity. Such a requirement for a specific residue is not
observed in the case of other conserved residues within the GAP-related domain.
We also report that another residue, phenylalanine 1434, plays an important role
in NF1 function. This was first indicated by the finding that defective NF1s due
to an alteration of lysine 1423 to other amino acids can be rescued by a second
site intragenic mutation at residue 1434. The mutation partially restored GAP
activity in the lysine mutant. When the mutation phenylalanine 1434 to serine
was introduced into a wild-type NF1 protein, the resulting protein acquired the
ability to suppress activated phenotypes of RAS2Val-19 cells. This suppression,
however, does not involve Ras interaction, since the phenylalanine mutant does
not stimulate the intrinsic GTPase activity of RAS2Val-19 protein and does not
have an increased affinity for Ras proteins. Neurofibromatosis type 1 (NF1) gene is a tumor suppressor gene, and the NF1 gene
product, neurofibromin, can downregulate the N-ras gene. Because the N-ras gene
is often mutated in acute myelogenous leukemia (AML), we wondered if the NF1
gene might be mutated in those AML samples not having N-ras mutations. We
investigated the mutational status of the N-ras gene and the FLR exon of codons
1371-1423 of the open reading frame of the full-length NF1 cDNA, which has a
strong homology with the mammalian ras GTPase-activating protein (GAP),
especially for a stretch of three consecutive amino acids (F, L, R), by
single-strand conformation polymorphism analysis and direct sequencing in
samples from patients with AML. Of 48 AML patients, 10 (21%) had point
(missense) mutations of the N-ras gene involving codons 12, 13 and 61. However,
mutations in the FLR exon of the NF1 gene were not detected in any of the AML
samples. We also examined the difference of clinical response to induction
therapy between AML patients with and without N-ras mutation. A significantly
lower rate of complete remission was noted in individuals with N-ras gene
mutations. These results suggest that mutation of the NF1 gene, at least in the
FLR exon, is very rare in AML and the NF1 gene probably is not a functional
complement of the N-ras gene mutation. The presence of N-ras gene mutation may
be associated with a lower clinical response to antileukemic therapy. The proto-oncogene ras is an essential gene for the growth and the
differentiation for various types of cells. Ras, ras gene product, is a GTP
binding protein which controls the signal transduction by GTP hydrolysis. The
ras gene is frequently activated by point mutations in various types of human
cancers, which results in a decrease in the GTPase activity of its product. A
GTPase-activating protein p120 (p120GAP) was identified as a factor which
stimulates the GTPase of normal ras gene product p21 but not of the mutated. An
NF1 gene was identified as a gene whose loss of function causes an onset of
human disorder, neurofibromatosis type I. The NF1 gene encodes a protein which
contains a region with a similarity to the catalytic domain of p120GAP. We
recently purified a novel Ras GAP whose molecular weight and immunogenecity are
different from those of p120GAP and NF1. We named the novel mammalian Ras GAP as
Gap1m. Isolation and sequencing of Gap1m cDNA revealed that Gap1m is indeed a
novel Ras GAP. We also succeeded in isolation of another novel Ras GAP gene,
GapIII/Gap1IP4BP, which is closely related to Gap1m. Recently, it is shown that
GapIII/Gap1IP4BP binds inositol-tetrakis phosphate compounds. The overview of
these Ras GAP molecules is described. CpG dinucleotides provide hotspots for transitional mutations in a variety of
genes, some leading to genetic diseases in humans. Although this phenomenon is
attributed to cytosine methylation at such sites, direct and specific
observations of CpG methylation at the sites of recurrent mutations are lacking.
We have used a bisulfite genomic sequencing method to analyze DNA methylation
within three representative exons from the neurofibromatosis type 1 (NF1) gene,
well recognized for its high frequency of spontaneous mutations. We observed
that the cytosine methylation within NF1 exons 28, 29, and 31 is restricted to
CpG dinucleotides, including the CpG dinucleotide present at the site of the
recurrent NF1 mutation (C5839T; also referred to as R1947X). At several sites,
clone-specific methylation differences were also observed. Our results provide
experimental evidence for the hypothesis that methylatable CpGs in the NF1 gene
contribute to spontaneous germline mutations associated with this gene, by
showing that DNA methylation does occur at all CpGs contained within these
representative NF1 exons. As well, the DNA methylation seen at the common
mutation site in exon 31 may explain why this site is frequently mutated.
Methylation-dependent mutagenesis may also provide a basis for some somatic
(second hit) mutations which disable the normal allele and result in the
development of NF1 associated symptoms. Two forms of neurofibromatosis, type 1 (NF1) and type 2 (NF2) are connected with
genes localized on chromosomes 17 and 22, respectively. The genes that are
inactivated in neurofibromatosis code for the proteins neurofibromine and
merline, respectively. Since inactivation leads to neoplasia, they are called
tumour suppressor genes. Neurofibromine shows resemblances to proteins that
serve to inactivate oncogenes. Merline has a relationship with proteins that
connect the cytoskeleton and the cell membrane. The precise function of the
proteins is still unknown. The NF1 gene is characterized by extraordinarily high
sensitivity to mutation; half the NF1 patients have not inherited the disease.
In the familial form of neurofibromatosis, a mutated gene is inherited and the
normal allele in the tumour is inactivated, making tumour growth possible. In
the sporadic form of neurofibromatosis, both normal alleles are inactivated
locally in the tissue so that a tumour develops in that place. Neurofibroma is a benign tumor that arises from small or large nerves. This
neoplastic lesion is a common feature of neurofibromatosis type 1 (NF1), one of
the most common autosomal domit disorders. The NF1 gene codes for a protein
called "neurofibromin." It possesses a region that shares a high homology with
the family of GTPase-activating proteins, which are negative regulators of RAS
function and thereby control cell growth and differentiation. The evidence
points to the NF1 gene being a tumor-suppressor gene. NF1 patients also have an
increased incidence of certain maligt tumors that are believed to follow the
"two hit" hypothesis, with one allele constitutionally inactivated and the other
somatically mutated. Recently, somatic loss of heterozygosity (LOH) has been
described for neurofibromas, and mutations in both copies of the NF1 gene have
been reported for a dermal neurofibroma. The aim of our study was the analysis
of the NF1 locus in benign neurofibromas in NF1 patients. We performed LOH
analysis on 60 neurofibromas belonging to 17 patients, 9 of them with family
history of the disease and 8 of them sporadic. We have analyzed five intragenic
NF1 markers and six extragenic markers, and we have found LOH in 25% of the
neurofibromas (corresponding to 53% of the patients). In addition, we found that
in the neurofibromas of patients from familial cases the deletions occurred in
the allele that is not transmitted with the disease, indicating that both copies
of the NF1 gene were inactivated in these tumors. Therefore, the recent reports
mentioned above, together with our findings, strongly support the double
inactivation of the NF1 gene in benign neurofibromas. Tumors of the central nervous system are the most frequent solid tumors in
childhood. With 30-40% of this heterogenous group, low-grade astrocytomas
represent the most common subtype. Neurofibromatosis type 1 (NF1) is strongly
associated with the development of pilocytic astrocytoma (PA), frequently
appearing as optic glioma. Neurofibromatosis 1 gene (NF1 ) fulfills the criteria
of a tumor suppressor gene and is deleted or mutated heterozygously in patients
with NF1. This suggests an involvement in the development of PA. To clarify
whether silencing of NF1 by promoter methylation plays a role in PA and
especially in optic glioma, the authors investigated the methylation status in
30 PA, 6 of which had optic glioma. However, no methylation was found at the NF1
promoter region in PA. To rule out that silencing of NF1 by promoter methylation
is restricted to higher-grade astrocytomas, 15 pediatric WHO II degree and IV
degree astrocytomas were analyzed: 12 astrocytomas II and 3 glioblastomas
displayed no NF1 promoter methylation. The authors conclude that NF1 silencing
by methylation plays no role in low-grade astrocytoma. The tumorigenesis of sporadic endocrine tumors is still not fully understood. It
is well known that patients with von Recklinghausen syndrome (NF-1) (OMIM
162200) carrying NF1 germline mutations are predisposed to endocrine tumors
including pheochromocytomas and duodenal somatostatinomas. It is unclear,
however, whether the rarely reported occurrence of pancreatic insulinomas in
NF-1 patients represents a coincidental finding or whether insulinomas are a
rare manifestation of the NF-1 syndrome. To determine the potential association
between the NF-1 syndrome and pancreatic endocrine tumors, we analyzed a NF-1
patient with a well-differentiated pancreatic endocrine carcinoma for NF1
mutation, allelic loss of the NF1 gene and its expression in peripheral blood
and tumor cells. The germline mutation c. 499 del TGTT known in the family was
confirmed by polymerase chain reaction (PCR) and direct sequencing of exon 4 in
DNA extracted from peripheral blood. Loss of heterozygosity (LOH) analysis of
the NF1 gene was carried out using 3 intragenic microsatellite markers on
17q11.2. RNA expression was examined by reverse transcription and a consecutive
PCR spanning intron 3 of the NF1 gene including the mutated site in exon 4.
Immunohistochemistry was used to analyze NF-1 protein expression. Mutation
analysis of peripheral blood leukocytes confirmed the 4 base pair deletion in
exon 4 starting at codon 167 (499 del TGTT). LOH analysis of tumor tissue
revealed retention of both NF1 alleles. While reverse transcriptase-PCR of
peripheral blood showed bi-allelic expression of both the wild-type NF1 and the
mutated form, reverse transcriptase-PCR of tumor extracts demonstrated
expression of the mutated but not the wild-type NF1 allele. Additionally,
neurofibromin, the NF1 gene product, was absent in the tumor tissue of the NF-1
patient. These results show that the wild-type NF1 transcrips and protein are
reduced, in the reported insulinoma, supposedly by epigenetic mechanisms. This
provides strong evidence that there is a relationship between von Recklinghausen
disease and the patient's insulinoma. In this line, insulinomas may be viewed as
a rare manifestation of the NF-1 syndrome. Furthermore, the NF1 gene must be
considered as a candidate tumor suppressor gene for sporadic insulinomas and
probably other pancreatic endocrine tumors. BACKGROUND: Neurofibromatosis type 1 (NF1) is a neurocutaneous disorder
resulting in the growth of a variety of tumours, and is inherited in an
autosomal domit pattern. Gastrointestinal stromal tumours (GISTs) are
mesenchymal tumours that commonly harbour oncogenic mutations in KIT or PDGFRA
and are thought to arise from the interstitial cells of Cajal (ICC; the
pacemaker cells of the gut).
AIM: To characterise two patients with NF1 and GISTs.
METHODS: Two patients were genotyped for germline mutations in NF1. GISTs from
both patients were genotyped for somatic mutations in KIT and PDGFRA. Loss of
heterozygosity (LOH) of NF1 in one GIST was assessed by genotyping seven
microsatellite markers spanning 2.39 Mb of the NF1 locus in the tumour and in
genomic DNA. The known germline mutation in NF1 was confirmed in GIST DNA by
sequencing. The copy number of the mutated NF1 allele was determined by
multiplex ligand-dependent probe amplification.
RESULTS: GISTs from both patients were of wild type for mutations in KIT and
PDGFRA. In the GIST with adequate DNA, all seven markers were informative and
showed LOH at the NF1 locus; sequencing of NF1 from that GIST showed no
wild-type sequence, suggesting that it was lost in the tumour. Multiplex
ligand-dependent probe amplification analysis showed that two copies of all NF1
exons were present.
CONCLUSIONS: This is the first evidence of mitotic recombination resulting in a
reduction to homozygosity of a germline NF1 mutation in an NF1-associated GIST.
We hypothesise that the LOH of NF1 and lack of KIT and PDGFRA mutations are
evidence of an alternative pathogenesis in NF1-associated GISTs. Neurofibromatosis type 1 (NF1) is the most frequent neurocutaneous disorder with
autosomal domit inheritance. Phenotype variability is high ranging from
merely several café-au-lait spots to maligt peripheral nerve sheath tumors or
severe disfigurement through plexiform neurofibromas. Identification of genetic
factors that modify the NF1 phenotype would contribute to the understanding of
NF1 pathophysiology and improve patient counselling. As even monozygotic (MZ)
twins with NF1 may differ phenotypically, we wondered whether these variations
might be inherited in a non-Mendelian fashion. Mitochondrial DNA (mtDNA) is
inherited extrachromosomally through the cytoplasm of the oocyte and often
harbours heteroplasmic sequence variations. At the time of blastomere
separation, these variants may be skewedly distributed and effect phenotypic
differences. Because of their co-localization with the tumor suppressor protein
neurofibromin, which is mutated in NF1, mitochondria were particular attractive
candidates for investigation. MtDNA was extracted from nucleated blood cells of
four pairs of discordant MZ twins with NF1 and from cutaneous neurofibromas of
one twin pair. We sequenced the entire mitochondrial genome and determined the
state of heteroplasmy by investigating a microsatellite region of the
mitochondrial D-loop (D310-tract). The clinical diagnosis was confirmed in all
patients by detection of pathogenic mutations in the NF1 gene. Monozygosity was
verified by genotyping. However, we did not detect evidence for mtDNA sequence
differences or for different degrees of heteroplasmy between individuals of the
same twin pair. The phenotypic discordance of MZ twins with NF1 cannot be
explained by skewed distribution of mtDNA mutations or polymorphisms. BACKGROUND: Neurofibromatosis type 1 (NF1) is a common disorder of dysregulated
tissue growth secondary to mutations in the tumor suppressor gene NF1. Pulmonary
arterial hypertension (PAH) in patients with NF1 is hypothesized to be secondary
to an underlying vasculopathy.
METHODS: We describe the entity we term NF1-associated PAH (NF1-PAH) in four new
patients and update the data on four previously published reports of patients
with PAH and NF1. We performed genetic testing of the bone morphogenic protein
receptor 2 (BMPR2) gene, which mutated in 70% of patients with familial PAH and
approximately 25% of patients with idiopathic PAH. We report, for the first
time, pathologic findings in the autopsy-obtained lung of one patient with
NF1-PAH.
RESULTS: Patients with NF1-PAH have a generally poor long-term prognosis. In
four patients, we observed the mosaic pattern of lung attenuation on a CT scan
of the chest, a radiographic finding that can be consistent with an underlying
vasculopathy. No mutations or rearrangements in the BMPR2 gene were found. We
observed complex plexiform lesions in the one available autopsy specimen.
Similar lesions are a hallmark of plexogenic pulmonary arteriopathy and are
associated with several severe types of PAH. (Plexiform lesions should not be
confused with plexiform neurofibromas, which are distinctive tumors seen in
NF1.)
CONCLUSIONS: Our findings suggest that NF1 should be considered as being
"associated with PAH as outlined in the Revised Clinical Classification of
Pulmonary Hypertension. Understanding the mechanism of PAH in NF1 may inform the
pathogenesis of PAH, NF1-PAH itself, and other NF1-associated vasculopathies.
The pulmonary vasculature should now be included among the arterial beds
affected by NF1 vasculopathy. |
List receptors of the drug Cilengitide | Cilengitide binds αvβ3 and αvβ5 integrins. It inhibits attachment and invasion of malignant cells. Thus, cilengitide is being tested for treatment of cancer patients. | Two randomized trials demonstrated an improvement in survival with
docetaxel-based chemotherapy for patients with metastatic, androgen-independent
prostate disease. However, the effect of current therapy is suboptimal in that
it is complicated by toxicities and has no curative potential. Cilengitide
(EMD121974; NSC 707544), is a potent selective alphavbeta3 and alphavbeta5
integrin antagonist. Integrins are cell surface receptors that mediate a variety
of cell activities including endothelial cell proliferation and migration.
Blocking the ligation of integrins by antagonists promotes apoptosis of
proliferative angiogenic cells, thereby suspending new blood vessel formation,
which is essential for the growth of maligt disease. In prostate cancer
specifically, integrins are known to be involved in metastases with differential
expression on tumor cells. Tumors and vascular endothelial cells produce
factors, such as vascular endothelial growth factor and basic fibroblast growth
factor, that promote neovascularization, which has been implicated in prostate
cancer progression. Cilengitide has been shown to inhibit alphavbeta3- and
alphavbeta5-mediated cell adhesion and block in vitro endothelial cell
migration. In vivo experiments demonstrated that cilengitide inhibited
cytokine-induced basic fibroblast growth factor- and vascular endothelial growth
factor-mediated angiogenesis in a dose-dependent manner. Cilengitide also
inhibited tumor growth in various in vivo systems. Two Cancer Therapy Evaluation
Program-sponsored, multicenter, phase II trials are designed to evaluate the
safety and efficacy of this agent in patients with androgen-independent prostate
cancer. National Cancer Institute trial 6735 is evaluating cilengitide at 2000
mg in patients with nonmetastatic androgen-independent prostate cancer, and
National Cancer Institute trial 6372 is evaluating 2 dose levels of cilengitide,
500 mg or 2000 mg, intravenously twice weekly in patients with metastatic
prostate cancer. Development of molecular devices endowed with tumor-targeting functions and
carrying cytotoxic components should enable the specific delivery of
chemotherapeutics to maligt tissues, thus increasing their local efficacy
while limiting their peripheral toxicity. Such molecular vectors can pave the
way for the development of new classes of therapeutics, fighting against
protagonists of neoplastic development. In line with this concept, peptide
ligands containing the Arginine-Glycine-Aspartate (RGD) triad, which display a
strong affinity and selectivity to the alpha(V)beta(3) integrin, have been
developed to target the tumor-associated cells expressing the alpha (V)beta (3)
receptors. Among the validated ligands, the leader compound is the cyclic
pentapeptide c[-RGDf(NMe)V-] (Cilengitide) developed by kessler et al. (J. Med.
Chem., 1999, 42, 3033-3040). This compound has entered phase II clinical trials
as an anti-angiogenic agent. Further studies have been directed to develop
molecular conjugates of the parent c[-RGDfK-] with conventional
chemotherapeutics or with labels for non-invasive imaging technologies. More
recently, multimeric RGD containing compounds have been exploited to improve the
targeting potential as well as cell-membrane breaching, through
receptor-mediated endocytosis. The latter have been constructed on various
scaffolds (polylysines or polyglutamates, liposomes, oparticles...). Our
group has developed a chemical system combining all these properties where
multivalent RGD targeting functions are associated with functional molecules
through a cyclopeptide template. The latter represents a relevant non-viral
vector for tumor targeting, imaging and therapy. This review describes the
considerations for the design of the diverse RGD ligands developed so far and
reports an overview of the main applications of these structures in cancer
research. Growth factor receptors and angiogenesis play major roles in the oncogenesis of
gliomas. Over the last several years, several noncytotoxic molecular targeted
therapies have been developed against growth factor receptors and tumor
angiogenesis. In gliomas, two main anti-growth factor receptor strategies have
been evaluated in phase I/II clinical trials: (a) small molecule tyrosine kinase
inhibitors (TKIs) and (b) monoclonal antibodies that target growth factors or
growth factor receptors other than vascular endothelial growth factor (VEGF). Up
to now, few glioma patients have responded to small TKIs (0%-14%) or monoclonal
antibodies (three case reports) delivered as a single agent. Greater doses,
combined therapies, as well as the identification of molecular biomarkers
predictive of response and resistance are important in order to optimize drug
delivery and improve efficacy. Antiangiogenic therapies are promising for the
treatment of gliomas. Thalidomide and metronomic chemotherapy were the first
antiangiogenic strategies evaluated, but they have shown only modest activity.
Recent studies of bevacizumab, an anti-VEGF antibody, and irinotecan, a
topoisomerase I inhibitor, have demonstrated a high response rate, suggesting
that targeted antiangiogenic therapies may play a significant role in the
management of high-grade gliomas in the future. However, the toxicity profiles
of these agents are not fully defined and the radiological evaluation of
possible tumor response is challenging. Clinical evaluation of several VEGF
receptor TKIs is currently ongoing; one of these inhibitors, cediranib, has
already demonstrated interesting activity as a single agent. The integrin
inhibitor cilengitide represents another promising strategy. Integrins are a large family of dimeric receptors composed by alpha and beta
subunits that, once bound to extra-cellular matrix (ECM) proteins, regulate a
variety of cellular processes such as cell motility, migration, and
proliferation. The integrins transduce signals from inside-out and outside-in
the cell, thus representing the cellular link to the external environment. For
these properties, integrin activation has been involved in pathological
processes like tumor growth and metastasis formation. Recent advances in the
elucidation of the crystallographic structures of the alphavbeta3 and
alphaIIbeta3 integrins are promoting studies focused to the search of small
molecule antagonists that can block the integrin binding to ECM and inhibit the
biological effects exerted by these receptors. In this review we will focus on
small molecule antagonists of alphavbeta3 and alphavbeta5 integrin as tools for
cancer therapy while other integrins will only be briefly mentioned. Cilengitide
(cyclic peptidic alphavbeta3 and alphavbeta5 antagonist) is currently in
clinical trials for anti cancer therapy. Combination of integrin alphavbeta3
antagonists and other traditional therapeutic approaches may represent a future
strategy to inhibit tumor growth and metastasis spreading. The aim of this study was to investigate the effect of inhibiting αvβ(3)/α(v)
β(5) integrins by cilengitide in experimentally induced breast cancer bone
metastases using noninvasive imaging techniques. For this purpose, nude rats
bearing established breast cancer bone metastases were treated with cilengitide,
a small molecule inhibitor of αvβ(3) and αvβ(5) integrins (75 mg/kg, five days
per week; n = 12 rats) and compared to vehicle-treated control rats (n = 12). In
a longitudinal study, conventional magnetic resoce imaging (MRI) and flat
panel volumetric computed tomography were used to assess the volume of the soft
tissue tumor and osteolysis, respectively, and dynamic contrast-enhanced (DCE-)
MRI was performed to determine functional parameters of the tumor vasculature
reflecting blood volume and blood vessel permeability. In rats treated with
cilengitide, VCT and MRI showed that osteolytic lesions and the respective bone
metastatic soft tissue tumors progressed more slowly than in vehicle-treated
controls. DCE-MRI indicated a decrease in blood volume and an increase in vessel
permeability and immunohistology revealed increased numbers of immature vessels
in cilengitide-treated rats compared to vehicle controls. In conclusion,
treatment of experimental breast cancer bone metastases with cilengitide
resulted in pronounced antiresorptive and antitumor effects, suggesting that
αvβ(3)/αvβ(5) inhibition may be a promising therapeutic approach for bone
metastases. BACKGROUND: Integrins mediate invasion and angiogenesis in prostate cancer bone
metastases. We conducted a phase II study of cilengitide, a selective antagonist
of α(v)β(3) and α(v)β(5) integrins, in non-metastatic castration resistant
prostate cancer with rising PSA.
METHODS: Patients were observed for 4 weeks with PSA monitoring, and then
treated with 2,000 mg IV of cilengitide twice weekly until toxicity/progression.
PSA, circulating tumor cells (CTCs) and circulating endothelial cells (CECs)
were monitored each cycle with imaging performed every three cycles. Primary end
point was PSA decline by ≥ 50%. Secondary endpoints were safety, PSA slope, time
to progression (TTP), overall survival (OS), CTCs, CECs and gene expression.
RESULTS: 16 pts were enrolled; 13 were eligible with median age 65.5 years,
baseline PSA 8.4 ng/mL and median Gleason sum 7. Median of three cycles was
administered. Treatment was well tolerated with two grade three toxicities and
no grade four toxicities. There were no PSA responses; 11 patients progressed by
PSA after three cycles. Median TTP was 1.8 months and median OS has not been
reached. Median pre- and on-treatment PSA slopes were 1.1 and 1.8 ng/mL/month.
Baseline CTCs were detected in 1/9 patients. CTC increased (0 to 1; 2 pts),
remained at 0 (2 pts) or decreased (23 to 0; 1 patient) at progression. Baseline
median CEC was 26 (0-61) and at progression, 47 (15-148). Low cell counts
precluded gene expression studies.
CONCLUSIONS: Cilengitide was well tolerated but had no detectable clinical
activity. CTCs are of questionable utility in non-metastatic prostate cancer. Cilengitide, a cyclic RGD pentapeptide, is currently in clinical phase III for
treatment of glioblastomas and in phase II for several other tumors. This drug
is the first anti-angiogenic small molecule targeting the integrins αvβ3, αvβ5
and αvβ1. It was developed by us in the early 90s by a novel procedure, the
spatial screening. This strategy resulted in c(RGDfV), the first superactive
αvβ3 inhibitor (100 to 1000 times increased activity over the linear reference
peptides), which in addition exhibited high selectivity against the platelet
receptor αIIbβ3. This cyclic peptide was later modified by N-methylation of one
peptide bond to yield an even greater antagonistic activity in c(RGDf(NMe)V).
This peptide was then dubbed Cilengitide and is currently developed as drug by
the company Merck-Serono (Germany). This article describes the chemical
development of Cilengitide, the biochemical background of its activity and a
short review about the present clinical trials. The positive anti-angiogenic
effects in cancer treatment can be further increased by combination with
"classical" anti-cancer therapies. Several clinical trials in this direction are
under investigation. The purpose of this study was the assessment of the feasibility of dynamic
positron emission tomography (PET) studies with fluorine-18 fluorodeoxyglucose
((18)F-FDG) to quantify effects of the cyclic Arg-Gly-Asp peptide cilengitide,
which targets the ανβ 3 and ανβ 5 integrin receptors in rats with breast cancer
bone metastases. Rats were inoculated with MDA-MB-231 breast cancer cells,
followed by the development of lytic lesions in the hind leg. Rats with lytic
lesions were treated with cilengitide five times weekly on a continuous basis
from days 30 to 55 after tumor cell inoculation. Dynamic PET studies with
(18)F-FDG were performed in untreated (n=9), controlled (n=4) and treated rats
(n=6). The data were assessed using learning-machine two-tissue compartmental
analysis. The (18)F-FDG kinetic parameters obtained by two-tissue compartmental
model learning-machine showed significant differences when individual parameters
were compared between the control group and treated animals. Quantitative
assessment of the tracer kinetics and the application of classification analysis
to the data provided us with evidence to identify those tumors that demonstrated
effect of cilengitide treatment. The transport rate K1 and the phosphorylation
rate k3 were significantly different (P=0.033 and 0.038, respectively).
Classification analysis based on support vector machines ranking feature
elimination of the combination of PET parameters revealed an overall accuracy of
80.0% between treated animals and the control group. We were able to identify
83.3% treated animals compared with the control group based on k2 and VB. In
conclusion, the results revealed that cilengitide treatment of experimental
breast cancer bone metastases had a significant therapeutic impact on (18)F-FDG
kinetics. The tumor environment is critical for tumor maintece and progression.
Integrins are a large family of cell surface receptors mediating the interaction
of tumor cells with their microenvironment and play important roles in glioma
biology, including migration, invasion, angiogenesis and tumor stem cell
anchorage. Here, we review preclinical and clinical data on integrin inhibition
in maligt gliomas. Various pharmacological approaches to the modulation of
integrin signaling have been explored including antibodies and peptide-based
agents. Cilengitide, a cyclic RGD-mimetic peptide of αvβ3 and αvβ5 integrins is
in advanced clinical development in glioblastoma. Cilengitide had only limited
activity as a single agent in glioblastoma, but, when added to standard
radiochemotherapy, appeared to prolong progression-free and overall survival in
patients with newly diagnosed glioblastomas and methylation of the promoter of
the O⁶ methylguanine methyltransferase (MGMT) gene. MGMT gene promoter
methylation in turn predicts benefit from alkylating chemotherapy. A phase III
randomized clinical trial in conjunction with standard radiochemotherapy in
newly diagnosed glioblastoma patients with MGMT gene promoter methylation has
recently completed accrual (EORTC 26071-22072). A companion trial explores a
dose-escalated regimen of cilengitide added to radiotherapy plus temozolomide in
patients without MGMT gene promoter methylation. Promising results in these
trials would probably result in a broader interest in integrins as targets for
glioma therapy and hopefully the development of a broader panel of anti-integrin
agents. Last years saw the development of anti-angiogenic strategies in the treatment of
cancers. Cilengitide (EMD121974; Merck KGaA, Darmstadt, Germany) is a new drug
targeting αvβ3 and αvβ5 integrins thanks to a specific peptide called RGD
sequence. Cilengitide acts in correlations between endothelial cells, tumor
cells and extracellular matrix. The promising results obtained with Cilengitide
in vitro, used alone or in combination with cytotoxic chemotherapy or ionizing
radiations, could give many hopes especially for the treatment of cerebral
tumors. Clinical trials are nowadays ongoing in this indication. The aim of this
review is to take stock of the situation on the mechanisms of action of the
integrin inhibitor Cilengitide (EMD121974; Merck KGaA, Darmstadt, Germany) with
a focus on the first pre-clinical and clinical results. Aza-peptides are obtained by replacement of the α-C-atom of one or more amino
acids by a nitrogen atom in a peptide sequence. Introduction of aza-residues
into peptide sequences may result in unique structural and pharmacological
properties, such that aza-scanning may be used to probe structure-activity
relationships. In this study, a general approach for the synthesis of cyclic
aza-peptides was developed by modification of strategies for linear aza-peptide
synthesis and applied in the preparation of cyclic aza-pentapeptides containing
the RGD (Arg-Gly-Asp) sequence. Aza-amino acid scanning was performed on the
cyclic RGD-peptide Cilengitide, cyclo[R-G-D-f-N(Me)V] 1, and its parent peptide
cyclo(R-G-D-f-V) 2, potent antagonists of the αvβ3, αvβ5, and α5β1 integrin
receptors, which play important roles in human tumor metastasis and
tumor-induced angiogenesis. Although incorporation of the aza-residues resulted
generally in a loss of binding affinity, cyclic aza-peptides containing
aza-glycine retained omolar activity toward the αvβ3 receptor. Isolated limb perfusion (ILP) with melphalan and tumor necrosis factor (TNF)-α
is used to treat bulky, locally advanced melanoma and sarcoma. However, TNF
toxicity suggests a need for better-tolerated drugs. Cilengitide (EMD 121974), a
novel cyclic inhibitor of alpha-V integrins, has both anti-angiogenic and direct
anti-tumor effects and is a possible alternative to TNF in ILP. In this study,
rats bearing a hind limb soft tissue sarcoma underwent ILP using different
combinations of melphalan, TNF and cilengitide in the perfusate. Further groups
had intra-peritoneal (i.p.) injections of cilengitide or saline 2 hr before and
3 hr after ILP. A 77% response rate (RR) was seen in animals treated i.p. with
cilengitide and perfused with melphalan plus cilengitide. The RR was 85% in
animals treated i.p. with cilengitide and ILP using melphalan plus both TNF and
cilengitide. Both RRs were significantly greater than those seen with melphalan
or cilengitide alone. Histopathology showed that high RRs were accompanied by
disruption of tumor vascular endothelium and tumor necrosis. Compared with ILP
using melphalan alone, the addition of cilengitide resulted in a three to
sevenfold increase in melphalan concentration in tumor but not in muscle in the
perfused limb. Supportive in vitro studies indicate that cilengitide both
inhibits tumor cell attachment and increases endothelial permeability. Since
cilengitide has low toxicity, these data suggest the agent is a good alternative
to TNF in the ILP setting. PURPOSE: Aim of this study was to investigate the specific treatment effects of
inhibiting αvβ3/αvβ5 integrins by cilengitide in an animal model of breast
cancer bone metastases using dynamic (18)F-FDG PET and gene expression analysis.
METHODS: For this purpose, nude rats bearing bone metastases were treated with
cilengitide, a small molecule inhibitor of αvβ3 and αvβ5 integrins, from day 30
to 55 after tumor cell inoculation of MDA-MB-231 breast cancer cells (25 mg/kg,
5 days per week; n = 8 rats) and compared to control rats (n = 8). Dynamic
(18)F-FDG PET data were assessed at days 30, 35 and 55 after tumor cell
inoculation determining the vascular fraction VB and the metabolic variables
k1-k4. At day 55, genome-wide mRNA expression analysis was performed to assess
the treatment-specific expression changes from cilengitide-treated and control
rats.
RESULTS: In a longitudinal (18)F-FDG PET study, the vascular fraction VB was
significantly decreased in bone metastases between days 30/35, 30/55 and 35/55,
whereas the kinetic parameters k1 and k4 were significantly decreased between
days 30/55 in skeletal lesions of treated animals. Gene expression analysis from
bone metastases at day 55 revealed that tumor-produced integrins (αvβ5) as well
as factors relevant for angiogenesis (αvβ3, VEGF, PDGF), bone resorption (PTHrP
and RANKL), extracellular matrix remodeling (collagen, CD44) and bone marrow
microenvironment (CXCR4) were significantly reduced upon therapy with
cilengitide.
CONCLUSIONS: Here, we provide evidence that cilengitide inhibits pivotal factors
of all compartments of bone metastases including tumor cells, vasculature and
bone microenvironment in vivo and by whole-genome transcriptome analysis. The prognosis of children with high-grade glioma or high-risk neuroblastoma
remains poor. Cilengitide is a selective antagonist of αvβ3 and αvβ5 integrins,
which are involved in tumor growth and development of metastasis. We have
evaluated the effects of cilengitide on pediatric glioma and neuroblastoma cell
lines for the first time. Expression levels of αvβ3 and αvβ5 were determined by
flow cytometry in three neuroblastoma and five pediatric glioma cell lines
compared with adult U87-MG before and after irradiation. Cell detachment,
cytotoxicity, and cell growth under nonadhesive conditions were measured using
the MTS assay. Cell death and apoptosis were assessed by annexin-V/propidium
iodide staining. The varying αvβ3 and αvβ5 expression levels were unrelated to
tumor grade. Irrespective of the αvβ5 expression level, the pediatric cells
expressing αvβ3 were dose dependently sensitive to cilengitide. UW479 cells
expressed only αvβ5 integrin and were not sensitive to cilengitide, suggesting
that cilengitide's action largely depends on αvβ3 inhibition. Cell detachment
resulted in a higher cytotoxicity in pediatric glioma compared with U87-MG
cells, which seem able to grow despite the significant cilengitide-induced cell
detachment. Growth kinetics on polyHEMA showed that only pediatric glioma cells
were sensitive to anoikis and so died after cilengitide-induced detachment.
Furthermore, irradiation of glioma cells increased αvβ3 expression slightly but
not cilengitide sensitivity. Cilengitide's action on glioma and neuroblastoma
cells appears to be dependent on αvβ3 expression and sensitivity to anoikis.
Cilengitide is able to target pediatric glioma and neuroblastoma cells in vitro
directly and efficiently. Tumor context could validate these promising
observations. Cilengitide is an RGD-peptide of sequence cyclo[RGDfNMeV] that was was developed
as a highly active and selective ligand for the αvβ3 and αvβ5 integrin
receptors. We describe the synthesis of three analogues of this peptide in which
the N-Me group has been replaced by N-oligoethylene glycol (N-OEG) chains of
increasing size: namely N-OEG2, N-OEG11, and N-OEG23, which are respectively
composed of 2, 11, and 23 ethylene oxide monomer units. The different N-OEG
cyclopeptides and the original peptide were compared with respect to
lipophilicity and biological activity. The N-OEG2 analogue was straightforward
to synthesize in solid phase using an Fmoc-N-OEG2 building block. The syntheses
of the N-OEG11 and N-OEG23 cyclopeptides are hampered by the increased steric
hindrance of the N-substituent, and could only be achieved by segment coupling,
which takes place with epimerization and thus requires extensive product
purification. All the N-OEG analogues were found to be more hydrophobic than the
parent peptide, and their hydrophobicity was systematically enhanced upon
increasing the length of the OEG chain. The N-OEG2 cyclopeptide displayed the
same capacity as Cilengitide to inhibit the integrin-mediated adhesion of HUVEC
endothelial, DAOY gliobastoma, and HT-29 colon cancer cells to their ligands
vitronectin and fibrinogen. The N-OEG11 and N-OEG23 analogues also inhibited
cell adhesion to these immobilized ligands, but their IC50 values dropped by 1
order of magnitude with respect to the parent peptide. These results indicate
that replacement of the backbone N-Me group of Cilengitide by a short N-OEG
chain provides a more lipophilic analogue with a similar biological activity.
Upon increasing the size of the N-OEG chain, liophilicity is enhanced, but
synthetic yields drop and the longer polymer chains may impede targeted binding. The RGD cyclic pentapetide, cilengitide, is a selective inhibitor of αvβ3 and
αvβ5 integrins and was developed for antiangiogenic therapy. Since cilengitide
interacts with platelet αIIbβ3 and platelets express αv integrins, the effect of
cilengitide on platelet pro-coagulative response and adhesion is of interest.
Flow-based adhesion assays were performed to evaluate platelet adhesion and
rolling on von Willebrand factor (vWf), on fibrinogen and on human umbilical
vein endothelial cells (HUVECs). Flow cytometry was used to detect platelet
activation (PAC1) and secretion (CD62P) by cilengitide and light transmission
aggregometry was used to detect cilengitide-dependent platelet aggregation.
Cilengitide inhibited platelet adhesion to fibrinogen at concentrations above
250 µM [which is the Cmax in human studies] and adhesion to vWf and HUVECs at
higher concentrations under physiologic flow conditions. Platelet aggregation
was already impaired at cilengitide concentrations >10 µM. Activation of αIIbβ3
integrin was inhibited by 250 µM cilengitide, whereas platelet secretion was
unaffected by cilengitide. No evidence of cilengitide-induced platelet
activation was found at all tested concentrations (0.01-1500 µM). At higher
concentrations, platelet activation was inhibited, predomitly due to αIIbβ3
inhibition. Maligt pleural mesothelioma (MPM) is an almost invariably fatal,
asbestos-related maligcy arising from the mesothelial membrane lining the
thoracic cavities. Despite some improvements in treatment, therapy is not
considered curative and median survival following diagnosis is less than 1 year.
Although still classed as a rare cancer, the incidence of MPM is increasing, and
the limited progress in treating the disease makes the identification of new
therapies a priority. As there is evidence for expression of the integrins αvβ3
and αvβ5 in MPM, there is a rationale for investigating the effects on MPM of
cilengitide, a synthetic peptide inhibitor of integrin αv heterodimer with high
specificity for αvβ3 and αvβ5. In mesothelial cells (MC) and 7 MPM cell lines,
growth inhibition by cilengitide was associated with the expression level of its
target integrins. Furthermore, cilengitide caused cell detachment and subsequent
death of anoikis-sensitive cells. It also suppressed invasion of MPM cells in
monolayer and three-dimensional cultures. Gene knockdown experiments indicated
that these effects of cilengitide were, at least partly, due to antagonism of
αvβ3 and αvβ5. Molecules that target and inhibit αvβ3, αvβ5, and α5β1 integrins have generated
great interest because of the role of these receptors in mediating angiogenesis
and metastasis. Attempts to increase the binding affinity and hence the efficacy
of integrin inhibitors by dimerization have been marginally effective. In the
present work, we achieved this goal by using oxime-based chemical conjugation to
synthesize dimers of integrin-binding cystine knot (knottin) miniproteins with
low-picomolar binding affinity to tumor cells. A non-natural amino acid
containing an aminooxy side chain was introduced at different locations within a
knottin monomer and reacted with dialdehyde-containing cross-linkers of
different lengths to create knottin dimers with varying molecular topologies.
Dimers cross-linked through an aminooxy functional group located near the middle
of the protein exhibited higher apparent binding affinity to integrin-expressing
tumor cells compared with dimers cross-linked through an aminooxy group near the
C-terminus. In contrast, the cross-linker length had no effect on the integrin
binding affinity. A chemical-based dimerization strategy was critical, as
knottin dimers created through genetic fusion to a bivalent antibody domain
exhibited only modest improvement (less than 5-fold) in tumor cell binding
relative to the knottin monomer. The best oxime-conjugated knottin dimer
achieved an unprecedented 150-fold increase in apparent binding affinity over
the knottin monomer. Also, this dimer bound 3650-fold stronger and inhibited
tumor cell migration and proliferation compared with cilengitide, an
integrin-targeting peptidomimetic that performed poorly in recent clinical
trials, suggesting promise for further therapeutic development. |
Can protein coding exons originate from ALU sequences? | Yes. Intronic ALUs can evolve into exons by the activation of splice signals residing within the ALU sequence. While most ALU exons do not add or modify the coding capacity of the resulting transcript, examples have been identified of ALU exons becoming protein coding. | Alu repetitive elements can be inserted into mature messenger RNAs via a
splicing-mediated process termed exonization. To understand the molecular basis
and the regulation of the process of turning intronic Alus into new exons, we
compiled and analyzed a data set of human exonized Alus. We revealed a mechanism
that governs 3' splice-site selection in these exons during alternative
splicing. On the basis of these findings, we identified mutations that activated
the exonization of a silent intronic Alu. Alu exonization, which is an evolutionary pathway that creates primate-specific
transcriptomic diversity, is a powerful tool for studying alternative-splicing
regulation. Through bioinformatic analyses combined with experimental
methodology, we identified the mutational changes needed to create functional 5'
splice sites in Alu. We revealed a complex mechanism by which the sequence
composition of the 5' splice site and its base pairing with the small nuclear
RNA U1 govern alternative splicing. We show that in Alu-derived GC introns the
strength of the base pairing between U1 snRNA and the 5' splice site controls
the skipping/inclusion ratio of alternative splicing. Based on these findings,
we identified 7810 Alus within the human genome that are prone to exonization.
Mutations in these Alus may cause genetic disorders or contribute to
human-specific protein diversity. The majority of more than one million primate-specific Alu elements map to
nonfunctional parts of introns or intergenic sequences. Once integrated, they
have the potential to become exapted as functional modules, e.g., as
protein-coding domains via alternative splicing. This particular process is also
termed exonization and increases protein versatility. Here we investigate 153
human chromosomal loci where Alu elements were conceivably exonized. In four
selected examples, we generated, with the aid of representatives of all primate
infraorders, phylogenetic reconstructions of the evolutionary steps presumably
leading to exonization of Alu elements. We observed a variety of possible
scenarios in which Alu elements led to novel mRNA splice forms and which, like
most evolutionary processes, took different courses in different lineages. Our
data show that, once acquired, some exonizations were lost again in some
lineages. In general, Alu exonization occurred at various time points over the
evolutionary history of primate lineages, and protein-coding potential was
acquired either relatively soon after integration or millions of years
thereafter. The course of these paths can probably be generalized to the
exonization of other elements as well. Ancient Alu elements have been shown to be included in mature transcripts by
point mutations that improve their 5' or 3' splice sites. We have examined
requirements for exonization of a younger, disease-associated AluYa5 in intron
16 of the human ACE gene. A single G>C transversion in position -3 of the new
Alu exon was insufficient for Alu exonization and a significant inclusion in
mRNA was only observed when improving several potential splice donor sites in
the presence of 3' CAG. Since complete Alu exonization was not achieved by
optimizing traditional splicing signals, including the branch site, we tested
whether auxiliary elements in AluYa5 were required for constitutive inclusion.
Exonization was promoted by a SELEX-predicted heptamer in Alu consensus sequence
222-228 and point mutations in highly conserved nucleotides of this heptamer
decreased Alu inclusion. In addition, we show that Alu exonization was
facilitated by a subset of serine/arginine-rich (SR) proteins through activation
of the optimized 3' splice site. Finally, the haplotype- and allele-specific ACE
minigenes generated similar splicing patterns in both ACE-expressing and
non-expressing cells, suggesting that previously reported allelic association
with plasma ACE activity and cardiovascular disease is not attributable to
differential splicing of introns 16 and 17. Survivin is a member of the inhibitor apoptosis family that is overexpressed in
many maligcies. It has five known alternative splice forms, some of which
differ in their antiapoptotic properties and expression levels in human cancers.
Here we describe a novel donor splice site (DSS), 2B+32 DSS, which is used in
conjunction with survivin alternative exon 2B, resulting in the inclusion of 32
additional nucleotides from intron 2 at the 3' end of this exon. Sequence
analysis showed that both the classical exon 2B DSS and 2B+32 are provided by an
Alu sequence, which is inserted in intron 2 downstream of a functional acceptor
splice site, leading to the exonization of part of the repetitive element. Minor
transcripts including the 2B+32 alternative exon, or retaining the whole
intronic region comprised between exons 2B and 3, were detected in several human
cell lines and in some human tissues. Survivin 2B+32 containing variants acquire
a premature stop codon (PTC) and may therefore be degraded by the nonsense
mediated decay pathway. The implication of these novel isoforms, as well as
other PTC+ survivin variants, in the overall regulation of survivin expression
is discussed. Sequence analysis of intron 2 which contains the Alu Y element was
performed on different primate species in order to trace its insertion and
exonization during primate evolution. BACKGROUND: Transposed elements (TEs) have a substantial impact on mammalian
evolution and are involved in numerous genetic diseases. We compared the impact
of TEs on the human transcriptome and the mouse transcriptome.
RESULTS: We compiled a dataset of all TEs in the human and mouse genomes,
identifying 3,932,058 and 3,122,416 TEs, respectively. We than extracted TEs
located within human and mouse genes and, surprisingly, we found that 60% of TEs
in both human and mouse are located in intronic sequences, even though introns
comprise only 24% of the human genome. All TE families in both human and mouse
can exonize. TE families that are shared between human and mouse exhibit the
same percentage of TE exonization in the two species, but the exonization level
of Alu, a primate-specific retroelement, is significantly greater than that of
other TEs within the human genome, leading to a higher level of TE exonization
in human than in mouse (1,824 exons compared with 506 exons, respectively). We
detected a primate-specific mechanism for intron gain, in which Alu insertion
into an exon creates a new intron located in the 3' untranslated region (termed
'intronization'). Finally, the insertion of TEs into the first and last exons of
a gene is more frequent in human than in mouse, leading to longer exons in
human.
CONCLUSION: Our findings reveal many effects of TEs on these two transcriptomes.
These effects are substantially greater in human than in mouse, which is due to
the presence of Alu elements in human. BACKGROUND: Gene duplication and exonization of intronic transposed elements are
two mechanisms that enhance genomic diversity. We examined whether there is less
selection against exonization of transposed elements in duplicated genes than in
single-copy genes.
RESULTS: Genome-wide analysis of exonization of transposed elements revealed a
higher rate of exonization within duplicated genes relative to single-copy
genes. The gene for TIF-IA, an RNA polymerase I transcription initiation factor,
underwent a humanoid-specific triplication, all three copies of the gene are
active transcriptionally, although only one copy retains the ability to generate
the TIF-IA protein. Prior to TIF-IA triplication, an Alu element was inserted
into the first intron. In one of the non-protein coding copies, this Alu is
exonized. We identified a single point mutation leading to exonization in one of
the gene duplicates. When this mutation was introduced into the TIF-IA coding
copy, exonization was activated and the level of the protein-coding mRNA was
reduced substantially. A very low level of exonization was detected in normal
human cells. However, this exonization was abundant in most leukemia cell lines
evaluated, although the genomic sequence is unchanged in these cancerous cells
compared to normal cells.
CONCLUSION: The definition of the Alu element within the TIF-IA gene as an exon
is restricted to certain types of cancers; the element is not exonized in normal
human cells. These results further our understanding of the delicate interplay
between gene duplication and alternative splicing and of the molecular
evolutionary mechanisms leading to genetic innovations. This implies the
existence of purifying selection against exonization in single copy genes, with
duplicate genes free from such constrains. Transposable elements (TEs) are major sources of new exons in higher eukaryotes.
Almost half of the human genome is derived from TEs, and many types of TEs have
the potential to exonize. In this work, we conducted a large-scale analysis of
human exons derived from mammalian-wide interspersed repeats (MIRs), a class of
old TEs which was active prior to the radiation of placental mammals. Using exon
array data of 328 MIR-derived exons and RT-PCR analysis of 39 exons in 10
tissues, we identified 15 constitutively spliced MIR exons, and 15 MIR exons
with tissue-specific shift in splicing patterns. Analysis of RNAs from multiple
species suggests that the splicing events of many strongly included MIR exons
have been established before the divergence of primates and rodents, while a
small percentage result from recent exonization during primate evolution.
Interestingly, exon array data suggest substantially higher splicing activities
of MIR exons when compared with exons derived from Alu elements, a class of
primate-specific retrotransposons. This appears to be a universal difference
between exons derived from young and old TEs, as it is also observed when
comparing Alu exons to exons derived from LINE1 and LINE2, two other groups of
old TEs. Together, this study significantly expands current knowledge about
exonization of TEs. Our data imply that with sufficient evolutionary time,
numerous new exons could evolve beyond the evolutionary intermediate state and
contribute functional novelties to modern mammalian genomes. Insertion of transposed elements within mammalian genes is thought to be an
important contributor to mammalian evolution and speciation. Insertion of
transposed elements into introns can lead to their activation as alternatively
spliced cassette exons, an event called exonization. Elucidation of the
evolutionary constraints that have shaped fixation of transposed elements within
human and mouse protein coding genes and subsequent exonization is important for
understanding of how the exonization process has affected transcriptome and
proteome complexities. Here we show that exonization of transposed elements is
biased towards the beginning of the coding sequence in both human and mouse
genes. Analysis of single nucleotide polymorphisms (SNPs) revealed that
exonization of transposed elements can be population-specific, implying that
exonizations may enhance divergence and lead to speciation. SNP density analysis
revealed differences between Alu and other transposed elements. Finally, we
identified cases of primate-specific Alu elements that depend on RNA editing for
their exonization. These results shed light on TE fixation and the exonization
process within human and mouse genes. Recently, genome-wide association studies have identified a strong association
between the ZBTB38 locus and human height. In a functional study, we detected
two RT-PCR products of ZBTB38, amplified with primers in exons 7 and 8 from a
chondrocyte cell line, C-28/I2. Sequencing revealed that the longer product
contained an Alu segment in intron 7 of ZBTB38, which contained a potential
splicing acceptor site that likely was used to generate the alternative
transcript. Insertion of the Alu segment changed the consensus Kozak sequence of
the ZBTB38 transcript, potentially altering translational efficiency. We
performed RT-PCR using 16 tissue samples from humans and 8 tissue samples from
primates to determine any tissue specificity or evolutionary conservation of the
alternative splicing. Although we failed to identify any difference among the
tissues, all primate samples expressed only the shorter Alu segment (lacking the
transcript), suggesting that the alternative splicing event is hominid
primate-specific. The Alu element has been a major source of new exons during primate evolution.
Thousands of human genes contain spliced exons derived from Alu elements.
However, identifying Alu exons that have acquired genuine biological functions
remains a major challenge. We investigated the creation and establishment of Alu
exons in human genes, using transcriptome profiles of human tissues generated by
high-throughput RNA sequencing (RNA-Seq) combined with extensive RT-PCR
analysis. More than 25% of Alu exons analyzed by RNA-Seq have estimated
transcript inclusion levels of at least 50% in the human cerebellum, indicating
widespread establishment of Alu exons in human genes. Genes encoding zinc finger
transcription factors have significantly higher levels of Alu exonization.
Importantly, Alu exons with high splicing activities are strongly enriched in
the 5'-UTR, and two-thirds (10/15) of 5'-UTR Alu exons tested by luciferase
reporter assays significantly alter mRNA translational efficiency. Mutational
analysis reveals the specific molecular mechanisms by which newly created 5'-UTR
Alu exons modulate translational efficiency, such as the creation or elongation
of upstream ORFs that repress the translation of the primary ORFs. This study
presents genomic evidence that a major functional consequence of Alu exonization
is the lineage-specific evolution of translational regulation. Moreover, the
preferential creation and establishment of Alu exons in zinc finger genes
suggest that Alu exonization may have globally affected the evolution of primate
and human transcriptomes by regulating the protein production of master
transcriptional regulators in specific lineages. There are ~650,000 Alu elements in transcribed regions of the human genome.
These elements contain cryptic splice sites, so they are in constant danger of
aberrant incorporation into mature transcripts. Despite posing a major threat to
transcriptome integrity, little is known about the molecular mechanisms
preventing their inclusion. Here, we present a mechanism for protecting the
human transcriptome from the aberrant exonization of transposable elements.
Quantitative iCLIP data show that the RNA-binding protein hnRNP C competes with
the splicing factor U2AF65 at many genuine and cryptic splice sites. Loss of
hnRNP C leads to formation of previously suppressed Alu exons, which severely
disrupt transcript function. Minigene experiments explain disease-associated
mutations in Alu elements that hamper hnRNP C binding. Thus, by preventing
U2AF65 binding to Alu elements, hnRNP C plays a critical role as a genome-wide
sentinel protecting the transcriptome. The findings have important implications
for human evolution and disease. |
How could U1 small nuclear RNA be used in therapeutics? | Until now, two main types of therapeutic strategies have been developed using U1 small nuclear RNA (snRNA): 1) Production of a defective, but partially functional protein, with the help of exon skipping, through modulation of pre-mRNA splicing, and 2) Correction of pathogenic effects of splice donor site mutations with the use of U1 snRNA adapted to the defective variant. | We describe a gene silencing method that employs a mechanism of action distinct
from those of antisense and RNA interference. U1 Adaptors are bifunctional
oligonucleotides with a 'target domain' complementary to a site in the target
gene's terminal exon and a 'U1 domain' that binds to the U1 small nuclear RNA
component of the U1 small nuclear ribonucleoprotein (U1 snRNP) splicing factor.
Tethering of U1 snRNP to the target pre-mRNA inhibits poly(A)-tail addition,
causing degradation of that RNA species in the nucleus. U1 Adaptors can inhibit
both endogenous and reporter genes in a sequence-specific manner. Comparison of
U1 Adaptors with small interfering RNA (siRNA) using a genome-wide microarray
analysis indicates that U1 Adaptors have limited off-target effects and no
detectable adverse effects on splicing. Further, targeting the same gene either
with multiple U1 Adaptors or with a U1 Adaptor and siRNA strongly enhances gene
silencing. The U1 small nuclear RNA (U1 snRNA) as a component of the major U2-dependent
spliceosome recognizes 5' splice sites (5'ss) containing GT as the canonical
dinucleotide in the intronic positions +1 and +2. The c.165+1G>T germline
mutation in the 5'ss of exon 2 of the Fanconi anemia C (FANCC) gene commonly
predicted to prevent correct splicing was identified in nine FA patients from
three pedigrees. RT-PCR analysis of the endogenous FANCC mRNA splicing pattern
of patient-derived fibroblasts revealed aberrant mRNA processing, but
surprisingly also correct splicing at the TT dinucleotide, albeit with lower
efficiency. This consequently resulted in low levels of correctly spliced
transcript and minute levels of normal posttranslationally processed FANCD2
protein, indicating that this naturally occurring TT splicing might contribute
to the milder clinical manifestations of the disease in these patients.
Functional analysis of this FANCC 5'ss within splicing reporters revealed that
both the noncanonical TT dinucleotide and the genomic context of FANCC were
required for the residual correct splicing at this mutant 5'ss. Finally, use of
lentiviral vectors as a delivery system to introduce expression cassettes for
TT-adapted U1 snRNAs into primary FANCC patient fibroblasts allowed the
correction of the DNA-damage-induced G2 cell-cycle arrest in these cells, thus
representing an alternative transcript-targeting approach for genetic therapy of
inherited splice-site mutations. Bardet-Biedl syndrome (BBS) is a multisystem disorder caused by ciliary defects.
To date, mutations in 15 genes have been associated with the disease and BBS1 is
most frequently affected in patients with BBS. The use of homozygosity mapping
in a large consanguineous family allowed us to identify the splice donor site
(SD) mutation c.479G>A in exon 5 of BBS1. Clinically affected family members
show symptoms of retinitis pigmentosa (RP) but lack other primary features that
would clearly support the diagnosis of BBS. In agreement with this exceptionally
mild BBS1-associated phenotype, we did not detect obvious ciliary defects in
patient-derived cells. SDs are bound by the U1 small nuclear RNA (U1), a process
that initiates exon recognition during splicing. The mutation described herein
interferes with U1 binding and induces aberrant splicing of BBS1. For a gene
therapeutic approach, we have adapted the sequence of U1 to increase its
complementarity to the mutated SD. Lentiviral treatment of patient-derived
fibroblasts with the adapted U1 partially corrected aberrant splicing of
endogenously expressed BBS1 transcripts. This therapeutic effect was
dose-dependent. Our results show that the adaptation of U1 can correct
pathogenic effects of splice donor site mutations and suggest a high potential
for gene therapy. A significant proportion of disease-causing mutations affect precursor-mRNA
splicing, inducing skipping of the exon from the mature transcript. Using F9
exon 5, CFTR exon 12 and SMN2 exon 7 models, we characterized natural mutations
associated to exon skipping in Haemophilia B, cystic fibrosis and spinal
muscular atrophy (SMA), respectively, and the therapeutic splicing rescue by
using U1 small nuclear RNA (snRNA). In minigene expression systems, loading of
U1 snRNA by complementarity to the normal or mutated donor splice sites (5'ss)
corrected the exon skipping caused by mutations at the polypyrimidine tract of
the acceptor splice site, at the consensus 5'ss or at exonic regulatory
elements. To improve specificity and reduce potential off-target effects, we
developed U1 snRNA variants targeting non-conserved intronic sequences
downstream of the 5'ss. For each gene system, we identified an exon-specific U1
snRNA (ExSpeU1) able to rescue splicing impaired by the different types of
mutations. Through splicing-competent cDNA constructs, we demonstrated that the
ExSpeU1-mediated splicing correction of several F9 mutations results in complete
restoration of secreted functional factor IX levels. Furthermore, two ExSpeU1s
for SMA improved SMN exon 7 splicing in the chromosomal context of normal cells.
We propose ExSpeU1s as a novel therapeutic strategy to correct, in several human
disorders, different types of splicing mutations associated with defective exon
definition. We report the use of the U1 snRNA as a vector for the stable expression of
antisense molecules against the splice junctions of specific dystrophin exons.
The single-stranded 5' terminus of U1 can be replaced by unrelated sequences as
long as 50 nucleotides without affecting both the stability and the ability to
assemble into snRNP particles. Effective exon skipping has been obtained for
different dystrophin exons by antisense sequences against 5' and 3' splice sites
alone or in combination with ESE sequences. The efficacy of these molecules has
been studied both in in vitro systems and in animals. In both cases the chimeric
molecules, delivered as part of lentiviral or AAV vectors (De Angelis et al.
Proc Natl Acad Sci USA 99:9456-9461, 2002; Denti et al. Proc Natl Acad Sci USA
103: 3758-3763, 2006; Denti et al. Hum Gene Ther 17: 565-743, 2006; Denti et al.
Hum Gene Ther 19: 601-608, 2008; Incitti et al. Mol Ther 18: 1675-1682, 2010),
provided high skipping activity and efficient rescue of dystrophin synthesis.
Moreover, the U1-antisense molecules, delivered to mice via systemic injection
of recombit AAV viruses, displayed body wide transduction, long-term
expression, dystrophin rescue as well as morphological and functional benefit
(Denti et al. Hum Gene Ther 19: 601-608, 2008). In this Chapter we report
methods for producing U1-antisense expression cassettes in the backbone of
lentiviral constructs and for testing their activity both in patients' derived
myoblasts as well as in fibroblasts reprogrammed to muscle differentiation. Antisense-mediated splicing modulation of premessenger RNA represents a novel
therapeutic strategy for several types of pathologies such as genetic disorders,
cancers, and infectious diseases. Antisense oligonucleotides designed to bind to
specific mRNA molecules have been actively developed for more than 20 years as a
form of molecular medicine to modulate splicing patterns or inhibit protein
translation. More recently, small nuclear RNA such as U7 or U1 small nuclear RNA
have been used to carry antisense sequences, offering the advantage of long-term
effect when delivered to cells using viral vectors. We have previously
demonstrated the therapeutic potential of U7snRNA targeting dystrophin mRNA as a
treatment for Duchenne muscular dystrophy. In particular, we showed that
bifunctional U7 snRNAs harboring silencer motifs induce complete skipping of
exon 51, and thus restore dystrophin expression in DMD patients cells to near
wild-type levels. These new constructs are very promising for the optimization
of therapeutic exon skipping for DMD, but also offer powerful and versatile
tools to modulate pre-mRNA splicing in a wide range of applications. Here, we
outline the design of these U7snRNA constructs to achieve efficient
exon-skipping and describe methods to evaluate the efficacy of such U7snRNA
constructs in vitro using the dystrophin gene as an example. Exon skipping has been demonstrated to be a successful strategy for the gene
therapy of Duchenne muscular dystrophy (DMD): the rational being to convert
severe Duchenne forms into milder Becker ones. Here, we show the selection of U1
snRNA-antisense constructs able to confer effective rescue of dystrophin
synthesis in a Δ44 Duchenne genetic background, through skipping of exon 45;
moreover, we demonstrate that the resulting dystrophin is able to recover timing
of myogenic marker expression, to relocalize neuronal nitric oxide synthase
(nNOS) and to rescue expression of miRNAs previously shown to be sensitive to
the Dystrophin-nNOS-HDAC2 pathway. Becker mutations display different
phenotypes, likely depending on whether the shorter protein is able to
reconstitute the wide range of wild-type functions. Among them, efficient
assembly of the dystrophin-associated protein complex (DAPC) and nNOS
localization are important. Comparing different Becker deletions we demonstrate
the correlation between the ability of the mutant dystrophin to relocalize nNOS
and the expression levels of two miRNAs, miR-1 and miR29c, known to be involved
in muscle homeostasis and to be controlled by the Dys-nNOS-HDAC2 pathway. |
What is the influence of patent expiry on ACE inhibitor prescribing. | Patent expiry has different effects on prescribing in different systems. It leads to decreased cost but no decreased refill compliance in countries like Sweden, Germany etc. In countries like Taiwan, where doctors profit directly from dispensing, patients are switched to ARBs which are more costly. | BACKGROUND: In order to increase price competition, government regulations focus
on controlling drug costs. Drug costs after patent expiry are an area of
particular interest because the substitution of branded medication with generics
represents an opportunity for lowering drug costs. However, drug costs may not
decrease after patent expiry, because of a lack of price competition and
different national pricing systems.
AIM: The aim of this study was to investigate the trends in the use of generics
after patent expiry for enalapril, fluoxetine and ranitidine and the subsequent
changes, if any, in the costs of these medications.
METHODS: A drug-utilisation study was performed using data from a large sample
of Dutch pharmacies. Both volumes (measured as defined daily doses [DDD] per
1000 population) as well as drug costs (calculated per DDD) prior to and after
patent expiry were calculated. Costs per DDD were compared using trend-line
analysis. In addition, the relative market shares of the different trade
channels (branded, parallel imported and generic) were compared before and after
patent expiry.
RESULTS: The costs per DDD decreased for all three drugs and, as expected, these
costs decrease more rapidly after patent expiry. Significant differences in the
trend lines were found for enalapril and fluoxetine.
CONCLUSIONS: Despite relatively high reimbursement prices for generics in the
Netherlands, this example from the Dutch pharmaceutical market demonstrates the
benefit of generic substitution for containing pharmaceutical costs, which
contrasts with concerns raised by the Dutch government. |
Is there evidence that tomato juice lowers cholesterol levels? | Yes, there is evidence to suggest that tomato juice (and other tomato products) can decrease cholesterol concentrations. It was shown that tomatoes inhibit cholesterol biosynthesis. | High dietary intakes of tomato products are often associated with a reduced risk
of CVD, but the atheroprotective mechanisms have not been established. This
study was conducted to investigate the effects of increased dietary intake of
tomato products on plasma lipids and LDL oxidation. The diet intervention
included a baseline period, a 3-week low tomato diet (no tomato products
allowed) and a 3-week high tomato diet (400 ml tomato juice and 30 mg tomato
ketchup daily). Twenty-one healthy study subjects participated in the study.
Total cholesterol concentration was reduced by 5.9 (sd 10) % (P = 0.002) and LDL
cholesterol concentration by 12.9 (sd 17.0) % (P = 0.0002) with the high tomato
diet compared to the low tomato diet. The changes in total and LDL cholesterol
concentrations correlated significantly with the changes in serum lycopene (r
0.56, P = 0.009; r 0.60, P = 0.004, total and LDL, respectively), beta-carotene
(r 0.58, P = 0.005; r 0.70, P < 0.001) and gamma-carotene concentrations (r
0.64, P = 0.002; r 0.64, P = 0.002). The level of circulating LDL to resist
formation of oxidized phospholipids increased 13 % (P = 0.02) in response to the
high tomato diet. In conclusion, a high dietary intake of tomato products had
atheroprotective effects, it significantly reduced LDL cholesterol levels, and
increased LDL resistance to oxidation in healthy normocholesterolaemic adults.
These atheroprotective features associated with changes in serum lycopene,
beta-carotene and gamma-carotene levels. Studies suggest that tomato and soy foods may contribute to a lower risk of
certain cancers. We developed a novel soy germ tomato juice to be used in
controlled cancer prevention trials. This study describes an initial test of
compliance, phytochemical bioavailability, and effects on biomarkers of blood
lipids. Healthy men and women (n = 18) consumed a soy germ-fortified juice daily
(300 mL supplying 66 mg isoflavones and 22 mg lycopene) for 8 wk. A single-dose
bioavailability study was completed on day 1 and isoflavones in plasma and
urine, and lycopene in the plasma, were measured. All subjects completed the
trial, with 97.7% ± 3.5% (mean ± SD) of the scheduled juice consumed. No adverse
effects were documented. The postprandial study indicated that 3.1% ± 2.3% of
lycopene was absorbed and that 49.3% ± 12.1% isoflavones ingested were recovered
in 24-h urines. Lycopene plasma concentration changed from 0.60 ± 0.22 to 1.24 ±
0.30 μmol/L during 8 wk of consumption. Juice consumption significantly improved
resistance of LDL+VLDL-C to Cu(2+)-mediated oxidation (P = 0.039), HDL-C (47.3 ±
15.8 to 51.7 ± 14.8 mg/dL, P < 0.001), and the ratio of total-C/HDL-C (4.25 ±
1.59 to 3.63 ± 1.16, P < 0.001) at 8 wk. A well-characterized soy-fortified
tomato juice can be produced in large scale for multiinstitutional long-term
cancer prevention trials and showed excellent compliance with no toxicity, while
demonstrating absorption of biologically active phytochemicals. Few epidemiologic studies have examined the potential cardiovascular mechanisms
of tomato-based food products, the primary dietary source of lycopene. We
examined the cross-sectional association between tomato-based food product
intake and coronary biomarkers in the Women's Health Study. Tomato-based food
products (tomatoes, tomato juice, tomato sauce, pizza) were summed from a
semiquantitative FFQ and multiple risk factors ascertained. Plasma from baseline
blood samples were assayed for lipids, lipoproteins, hemoglobin A1c, C-reactive
protein, fibrinogen, soluble intracellular adhesion molecule-1, and creatinine.
A total of 27,261 women aged ≥45 y who were free of cardiovascular disease and
cancer provided relevant data for this study. Tomato-based food product intake
was modest, with 84% of women consuming <1 serving/d, but those with greater
intake had healthier lifestyle and dietary habits. Women consuming ≥10 compared
with <1.5 servings/wk of tomato-based food products had significant but
clinically modest improvements in total cholesterol (TC) (5.38 vs. 5.51 mmol/L;
P = 0.029), the TC:HDL cholesterol ratio (4.08 vs. 4.22; P = 0.046), and
hemoglobin A1c (5.02 vs. 5.13%; P < 0.001) in multivariable models. Considering
clinical cutpoints, women consuming ≥10 compared with <1.5 servings/wk were 31%
(95% CI = 6%, 50%), 40% (95% CI = 13%, 59%), and 66% (95% CI = 20%, 86%) less
likely to have elevated TC (≥6.21 mmol/L), LDL cholesterol (≥4.14 mmol/L), and
hemoglobin A1c (≥6%), respectively. Other coronary biomarkers were unassociated
with tomato-based food products. In conclusion, women consuming ≥10 compared
with <1.5 servings/wk of tomato-based food products had clinically modest but
significant improvements in TC, the TC:HDL cholesterol ratio, and hemoglobin A1c
but not other coronary biomarkers. The hypocholesterolemic effect of tomato juice has been investigated in an
intervention study with rats, along with the possible inhibition effect of
bioactive tomato compounds binding to the HMGCR enzyme. Two experimental groups
(n = 8 Sprague-Dawley rats) were fed ad libitum for five weeks, with water or
tomato juice provided to the control and intervention groups, respectively.
Total, LDL and HDL cholesterol, and total triglycerides were analysed in plasma,
and the lycopene content and the expression and activity of the enzyme HMGCR
were determined in liver samples. A computational molecular modelling was
carried out to determine the interactions between HMGCR and lycopene,
chlorogenic acid and naringenin. Total, LDL and HDL cholesterol were
significantly lower in the intervention group after the intake of tomato juice.
In addition, a significant reduction in HMGCR activity was observed, although
this was not accompanied by changes in gene expression. The molecular modelling
showed that components of tomato can bind to the active site of the enzyme and
compete with the ligand HMGCoA. Lycopene, from tomato juice, accumulates in the
liver and can inhibit the activity of the rate-limiting enzyme of cholesterol
biosynthesis, HMGCR. |
Are there transposon-free regions in mammalian genomes? | Yes. Despite the presence of over 3 million transposons separated on average by approximately 500 bp, the human and mouse genomes each contain almost 1000 transposon-free regions (TFRs) over 10 kb in length. The majority of human TFRs correlate with orthologous TFRs in the mouse, despite the fact that most transposons are lineage specific. Many human TFRs also overlap with orthologous TFRs in the marsupial opossum, indicating that these regions have remained refractory to transposon insertion for long evolutionary periods. Over 90% of the bases covered by TFRs are noncoding, much of which is not highly conserved. Most TFRs are not associated with unusual nucleotide composition, but are significantly associated with genes encoding developmental regulators, suggesting that they represent extended regions of regulatory information that are largely unable to tolerate insertions, a conclusion difficult to reconcile with current conceptions of gene regulation. | BACKGROUND: We recently reported the existence of large numbers of regions up to
80 kb long that lack transposon insertions in the human, mouse and opossum
genomes. These regions are significantly associated with loci involved in
developmental and transcriptional regulation.
RESULTS: Here we report that transposon-free regions (TFRs) are prominent
genomic features of amphibian and fish lineages, and that many have been
maintained throughout vertebrate evolution, although most transposon-derived
sequences have entered these lineages after their divergence. The zebrafish
genome contains 470 TFRs over 10 kb and a further 3,951 TFRs over 5 kb, which is
comparable to the number identified in mammals. Two thirds of zebrafish TFRs
over 10 kb are orthologous to TFRs in at least one mammal, and many have
orthologous TFRs in all three mammalian genomes as well as in the genome of
Xenopus tropicalis. This indicates that the mechanism responsible for the
maintece of TFRs has been active at these loci for over 450 million years.
However, the majority of TFR bases cannot be aligned between distantly related
species, demonstrating that TFRs are not the by-product of strong primary
sequence conservation. Syntenically conserved TFRs are also more enriched for
regulatory genes compared to lineage-specific TFRs.
CONCLUSION: We suggest that TFRs contain extended regulatory sequences that
contribute to the precise expression of genes central to early vertebrate
development, and can be used as predictors of important regulatory regions. The Drosophila Gene Disruption Project (GDP) has created a public collection of
mutant strains containing single transposon insertions associated with different
genes. These strains often disrupt gene function directly, allow production of
new alleles, and have many other applications for analyzing gene function. Here
we describe the addition of ∼7600 new strains, which were selected from >140,000
additional P or piggyBac element integrations and 12,500 newly generated
insertions of the Minos transposon. These additions nearly double the size of
the collection and increase the number of tagged genes to at least 9440,
approximately two-thirds of all annotated protein-coding genes. We also compare
the site specificity of the three major transposons used in the project. All
three elements insert only rarely within many Polycomb-regulated regions, a
property that may contribute to the origin of "transposon-free regions" (TFRs)
in metazoan genomes. Within other genomic regions, Minos transposes essentially
at random, whereas P or piggyBac elements display distinctive hotspots and
coldspots. P elements, as previously shown, have a strong preference for
promoters. In contrast, piggyBac site selectivity suggests that it has evolved
to reduce deleterious and increase adaptive changes in host gene expression. The
propensity of Minos to integrate broadly makes possible a hybrid finishing
strategy for the project that will bring >95% of Drosophila genes under
experimental control within their native genomic contexts. |
Are messenger RNA molecules epigenetically methylated? | Yes, methyltranscriptome is an exciting new area that studies the mechanisms and functions of methylation in transcripts. | Methyltranscriptome is an exciting new area that studies the mechanisms and
functions of methylation in transcripts. The MethylTranscriptome DataBase
(MeT-DB, http://compgenomics.utsa.edu/methylation/) is the first comprehensive
resource for N6-methyladenosine (m(6)A) in mammalian transcriptome. It includes
a database that records publicaly available data sets from methylated RNA
immunoprecipitation sequencing (MeRIP-Seq), a recently developed technology for
interrogating m(6)A methyltranscriptome. MeT-DB includes ∼ 300 k m(6)A
methylation sites in 74 MeRIP-Seq samples from 22 different experimental
conditions predicted by exomePeak and MACS2 algorithms. To explore this rich
information, MeT-DB also provides a genome browser to query and visualize
context-specific m(6)A methylation under different conditions. MeT-DB also
includes the binding site data of microRNA, splicing factor and RNA binding
proteins in the browser window for comparison with m(6)A sites and for exploring
the potential functions of m(6)A. Analysis of differential m(6)A methylation and
the related differential gene expression under two conditions is also available
in the browser. A global perspective of the genome-wide distribution of m(6)A
methylation in all the data is provided in circular ideograms, which also act as
a navigation portal. The query results and the entire data set can be exported
to assist publication and additional analysis. Recent discoveries of reversible N(6)-methyladenosine (m(6)A) methylation on
messenger RNA (mRNA) and mapping of m(6)A methylomes in mammals and yeast have
revealed potential regulatory functions of this RNA modification. In plants,
defects in m(6)A methyltransferase cause an embryo-lethal phenotype, suggesting
a critical role of m(6)A in plant development. Here, we profile m(6)A
transcriptome-wide in two accessions of Arabidopsis thaliana and reveal that
m(6)A is a highly conserved modification of mRNA in plants. Distinct from
mammals, m(6)A in A. thaliana is enriched not only around the stop codon and
within 3'-untranslated regions, but also around the start codon. Gene ontology
analysis indicates that the unique distribution pattern of m(6)A in A. thaliana
is associated with plant-specific pathways involving the chloroplast. We also
discover a positive correlation between m(6)A deposition and mRNA abundance,
suggesting a regulatory role of m(6)A in plant gene expression. miRNAs and DNA methylation are both critical regulators of gene expression.
Aberration in miRNA expression or DNA methylation is a causal factor for
numerous pathological conditions. DNA methylation can inhibit the transcription
of miRNAs, just like coding genes, by methylating the CpG islands in the
promoter regions of miRNAs. Conversely, certain miRNAs can directly target DNA
methyltransferases and bring about their inhibition, thereby affecting the whole
genome methylation pattern. Recently, methylation patterns have also been
revealed in mRNA. Surprisingly, the two most commonly studied methylation states
in mRNA (m6A and m5C) are found to be enriched in 3'-UTRs (untranslated
regions), the target site for the majority of miRNAs. Whereas m5C is reported to
stabilise mRNA, m6A has a destabilising effect on mRNA. However, the effect of
mRNA methylation on its interaction with miRNAs is largely unexplored. The
review highlights the complex interplay between microRNA and methylation at DNA
and mRNA level. N(6)-methyladenosine (m6A) is the most abundant modified base in eukaryotic mRNA
and has been linked to diverse effects on mRNA fate. Current mapping approaches
localize m6A residues to transcript regions 100-200 nt long but cannot identify
precise m6A positions on a transcriptome-wide level. Here we developed m6A
individual-nucleotide-resolution cross-linking and immunoprecipitation (miCLIP)
and used it to demonstrate that antibodies to m6A can induce specific mutational
signatures at m6A residues after ultraviolet light-induced antibody-RNA
cross-linking and reverse transcription. We found that these antibodies
similarly induced mutational signatures at N(6),2'-O-dimethyladenosine (m6Am), a
modification found at the first nucleotide of certain mRNAs. Using these
signatures, we mapped m6A and m6Am at single-nucleotide resolution in human and
mouse mRNA and identified small nucleolar RNAs (snoRNAs) as a new class of
m6A-containing non-coding RNAs (ncRNAs). |
Which genes are more frequently affected by somatic mutations in Chronic Lymphocytic Leukemia | TP53, ATM, NOTCH1, XPO1, MYD88, KLHL6, SF3B1, ZMYM3, MAPK1, FBXW7 and DDX3X | Although B cell chronic lymphocytic leukemia (B-CLL) has been traditionally
viewed as a tumor of virgin B cells, this notion has been recently questioned by
data suggesting that a fraction of B-CLL derives from antigen experienced B
cells. In order to further clarify the histogenetic derivation of this
lymphoproliferation, we have analyzed the DNA sequences of the 5' non-coding
region of BCL-6 proto-oncogene in 28 cases of B-CLL. Mutations of BCL-6
proto-oncogene, a zinc finger transcription factor implicated in lymphoma
development, represent a histogenetic marker of B cell transit through the
germinal center (GC) and occur frequently in B cell maligcies derived from GC
or post-GC B cells. For comparison, the same tumor panel was analyzed for
somatic mutations of the rearranged immunoglobulin variable (IgV) genes, which
are known to be acquired at the time of B cell transit through the GC. Sequence
analyses of BCL-6 and IgV genes allowed the definition of three groups of B-CLL.
Group I B-CLL displayed mutations of both BCL-6 and IgV genes (10/28; 36%).
Group II B-CLL displayed mutated IgV genes, but a germline BCL-6 gene (5/28;
18%). Finally, group III B-CLL included the remaining cases (13/28; 46%) that
were characterized by the absence of somatic mutations of both BCL-6 and IgV
genes. Overall, the distribution of BCL-6 and IgV mutations in B-CLL reinforce
the notion that this leukemia is histogenetically heterogeneous and that a
substantial subgroup of these lymphoproliferations derives from post-germinal
center B cells. Chronic lymphocytic leukaemia (CLL), the most frequent leukaemia in adults in
Western countries, is a heterogeneous disease with variable clinical
presentation and evolution. Two major molecular subtypes can be distinguished,
characterized respectively by a high or low number of somatic hypermutations in
the variable region of immunoglobulin genes. The molecular changes leading to
the pathogenesis of the disease are still poorly understood. Here we performed
whole-genome sequencing of four cases of CLL and identified 46 somatic mutations
that potentially affect gene function. Further analysis of these mutations in
363 patients with CLL identified four genes that are recurrently mutated: notch
1 (NOTCH1), exportin 1 (XPO1), myeloid differentiation primary response gene 88
(MYD88) and kelch-like 6 (KLHL6). Mutations in MYD88 and KLHL6 are predomit
in cases of CLL with mutated immunoglobulin genes, whereas NOTCH1 and XPO1
mutations are mainly detected in patients with unmutated immunoglobulins. The
patterns of somatic mutation, supported by functional and clinical analyses,
strongly indicate that the recurrent NOTCH1, MYD88 and XPO1 mutations are
oncogenic changes that contribute to the clinical evolution of the disease. To
our knowledge, this is the first comprehensive analysis of CLL combining
whole-genome sequencing with clinical characteristics and clinical outcomes. It
highlights the usefulness of this approach for the identification of clinically
relevant mutations in cancer. Here we perform whole-exome sequencing of samples from 105 individuals with
chronic lymphocytic leukemia (CLL), the most frequent leukemia in adults in
Western countries. We found 1,246 somatic mutations potentially affecting gene
function and identified 78 genes with predicted functional alterations in more
than one tumor sample. Among these genes, SF3B1, encoding a subunit of the
spliceosomal U2 small nuclear ribonucleoprotein (snRNP), is somatically mutated
in 9.7% of affected individuals. Further analysis in 279 individuals with CLL
showed that SF3B1 mutations were associated with faster disease progression and
poor overall survival. This work provides the first comprehensive catalog of
somatic mutations in CLL with relevant clinical correlates and defines a large
set of new genes that may drive the development of this common form of leukemia.
The results reinforce the idea that targeting several well-known genetic
pathways, including mRNA splicing, could be useful in the treatment of CLL and
other maligcies. Chronic lymphocytic leukemia (CLL) is a heterogeneous disease without a
well-defined genetic alteration responsible for the onset of the disease.
Several lines of evidence coincide in identifying stimulatory and growth signals
delivered by B-cell receptor (BCR), and co-receptors together with NFkB pathway,
as being the driving force in B-cell survival in CLL. However, the molecular
mechanism responsible for this activation has not been identified. Based on the
hypothesis that BCR activation may depend on somatic mutations of the BCR and
related pathways we have performed a complete mutational screening of 301
selected genes associated with BCR signaling and related pathways using massive
parallel sequencing technology in 10 CLL cases. Four mutated genes in coding
regions (KRAS, SMARCA2, NFKBIE and PRKD3) have been confirmed by capillary
sequencing. In conclusion, this study identifies new genes mutated in CLL, all
of them in cases with progressive disease, and demonstrates that next-generation
sequencing technologies applied to selected genes or pathways of interest are
powerful tools for identifying novel mutational changes. |
How effective is the dentritic cells treatment on cancer? | Another approach to cancer therapy takes advantage of the normal role of the dendritic cell as an immune educator. Dendritic cells grab antigens from viruses, bacteria, or other organisms and wave them at T cells to recruit their help in an initial T cell immune response. This works well against foreign cells that enter the body, but cancer cells often evade the self/non-self detection system. By modifying dendritic cells, researchers are able to trigger a special kind of autoimmune response that includes a T cell attack of the cancer cells. Because a cancer antigen alone is not enough to rally the immune troops, scientists first fuse a cytokine to a tumor antigen with the hope that this will send a strong antigenic signal. Next, they grow a patient's dendritic cells in the incubator and let them take up this fused cytokine-tumor antigen. This enables the dendritic cells to mature and eventually display the same tumor antigens as appear on the patient's cancer cells. When these special mature dendritic cells are given back to the patient, they wave their newly acquired tumor antigens at the patient's immune system, and those T cells that can respond mount an attack on the patient's cancer cells. | Dendritic cells are critical initiators of immune responses. They not only
activate pathogen-specific T and B lymphocytes, they also stimulate cells of the
innate immune system. Furthermore, dentritic cells are involved in immunological
tolerance induction through the elimination of autoreactive T lymphocytes. Over
the last ten years, understanding of the development, biology and
physiopathology of dentritic cells has progressed considerably which has lead to
the use of dentritic cells in immunotherapy protocols to treat tumors,
infections and auto-immune diseases. Due to their central role in controlling immunity, dendritic cells are logical
targets for priming naive cytotoxic T lymphocytes against tumour cells. In a
strictly autologous system, we fused dendritic cells with melanoma cells, both
of which were derived from patients with metastatic maligt melanoma.
Hybridomas were positive for major histocompatibility complex (MHC) class II,
CD40, CD54, CD83, CD86, and the pro-inflammatory cytokine interleukin-12.
Autologous T lymphocytes were co-incubated with hybridomas. After 6 days,
in-vitro-primed T lymphocytes revealed a strong proliferation activity and
released Th-1-associated, but not Th-2-associated, cytokines. Furthermore they
showed effective anti-melanoma activity, resulting in death of 70 +/- 9% of
autologous melanoma cells. After depletion of CD4+ cells from the mixed
population of primed T lymphocytes, the remaining CD8+ cells were able to kill
63+/-8% of autologous melanoma cells. Following depletion of CD8+ cells,
however, the cytotoxic capacity of the remaining T lymphocytes caused death in
only 32+/-6% of autologous melanoma cells. Blocking of MHC class I, but not
class II, molecules on hybridomas impaired T cell proliferation, secretion of
Th-1-associated cytokines, as well as the cytotoxic activity of primed T cells.
These findings strongly suggest that hybridomas deliver melanoma-associated
antigens via MHC class I molecules to T lymphocytes, resulting in the generation
of CD8+ cytotoxic T lymphocytes with effective anti-melanoma activity in vitro.
The data may serve as a basis for the use of hybridomas in the immunotherapy of
maligt melanoma in vivo. Survivin, a member of the IAP family is an attractive target for cancer
treatment due to it's over expression in most cancers and low or no expression
in most differentiated adult tissues. Survivin expression is a poor prognostic
marker in a number of cancers. Clinical trials are currently underway evaluating
anti-sense oligonucleotides against Survivin, immunotherapy using Survivin
primed dentritic cells and peptide mimics that block interaction of Survivin
with Hsp90 resulting in loss of Survivin protein stability. Additional
approaches using ribozymes against Survivin mRNA, or domit-negative cDNA to
block Survivin function are in pre-clinical stages. Like many genes, Survivin is
alternately spliced and a number of new splice variants have recently been
identified. Expression of some of these splice variants correlates with loss of
steroid receptors as well as the tumor suppressor p53, in some cancers,
suggesting that like wild-type Survivin, at least some of these splice variants
may also have prognostic relevance. This review will focus on the current
understanding of the function of Survivin splice variants and their expression
and sub-cellular localization in normal and neoplastic tissues as well as
critically evaluating the potential toxicity of the Survivin directed therapies
and their predicted effect on the alternatively spliced Survivin isoforms. Angioimmunoblastic T-cell lymphoma (AITL) is a rare and aggressive neoplasm
clinically characterized by sudden onset of constitutional symptoms,
lymphadenopathy, hepatosplenomegaly, frequent autoimmune phenomena, particularly
hemolytic anemia and thrombocytopenia, and polyclonal hypergammaglobulinemia.
The lymph node histological picture is also distinctive, constituted by a
polymorphic infiltrate, a marked proliferation of high endothelial venules, and
a dense meshwork of dentritic cells. The neoplastic CD4+ T-cells represent a
minority of the lymph node cell population; its detection is facilitated by the
aberrant expression of CD10. Almost all cases arbor an EBV infected B-cell
population. Patients with AITL have a poor prognosis with conventional
treatment, with a median overall survival of less than 3 years. Patients
achieving a good clinical response seem beneficiate from a consolidation with
high-dose therapy and autologous stem cell transplantation. Constitutional
symptoms and autoimmune phenomena, and some times also the neoplastic masses may
respond to immunosuppressive or immunomodulatory agents such as thalidomide. BACKGROUND: CD1d-restricted iNKT cells are protective against murine melanoma
B16F10-Nex2 growing subcutaneously in syngeneic C57Bl/6 mice as inferred from
the fast tumor development in CD1d-KO in comparison with wild type animals. CD1d
glycoproteins are related to the class I MHC molecules, and are involved in the
presentation, particularly by dentritic cells (DC), of lipid antigens to iNKT
cells. In the present work we attempted to identify the endogenous lipid
mediator expressed in melanoma cells inducing such immunesurveillance response
and study the possibility of protecting animals challenged with tumor cells with
lipid-primed DC.
RESULTS: Crude cytosolic and membrane fractions from in vivo growing melanoma
contained iNKT-stimulating substances. Lipids were then extracted from these
cells and one of the fractions (i.e. F3A) was shown to prime bone marrow-derived
dendritic cells (BMDC) to stimulate iNKT murine hybridoma (DN32D3) cells to
produce IL-2. The active fraction was analyzed by electrospray ionization-mass
spectrometry (ESI-LIT-MS) and both iGb3 and iGb4 were identified along with GM3.
When iGb3 was incubated with BMDC and tested with DN32D3 cells, IL-2 was equally
produced indicating iNKT cell activation. GM3 consistently inhibited this
response. To assess the antitumor response-induced by iGb3, a cytotoxicity assay
in vitro was used with [3H]-thymidine labeled B16F10-Nex2 cells. At
target/effector (iGb3-activated iNKT) cell ratio of 100(-1)-100(-4) tumor cell
lysis was shown. The antitumor activity in vivo was tested in mice challenged
i.v. with B16F10-Nex2 cells and treated with iGb3- or
alpha-galactosylceramide-primed DCs. A 4-fold lower tumor load in the lungs was
observed with either treatment.
CONCLUSION: Our results show the expression of globo and
isoglobohexosylceramides in murine melanoma B16F10-Nex2. The expression of iGb3
and its precursor, iGb4, on tumor cells may prime an effective iNKT
cell-dependent antitumor response, modulated negatively by GM3 which is also
produced in these cells. iGb3-primed BMDC exerted a significant iNKT
cell-mediated anti-tumor activity in mice challenged with melanoma cells. The recently updated World Health Organization (WHO) classification of tumors of
hematopoietic and lymphoid tissues, published in 2008, has made great advances
in revising the disorders previously included in the pool of natural killer (NK)
cell tumors. Although NK cell neoplasms represent a relatively rare group of
diseases, accounting for <5% of all lymphoid neoplasms, they include very
distinctive conditions both clinically and pathologically. This family of
diseases includes the most indolent clinical forms, such as the provisional new
entry of chronic lymphoproliferative disorder of NK cells (CLPD-NK) in the WHO
classification, as well as one of the most fatal diseases recognized in medical
oncology, aggressive NK cell leukemia (ANKL), which is characterized by a
prognosis of weeks, or even days. In addition, some disorders previously
identified as blastic NK cell lymphoma within the NK cell system have been more
properly defined and included in the blastic plasmacytoid dentritic cell
neoplasms, although rare cases of bona fide immature NK lymphoid tumors (now
classified as NK cell lymphoblastic leukemia/lymphoma) have been reported in the
literature. This paper focuses on recent concepts and progress in morphology,
pathogenesis, clinicopathological features, treatment approaches, and outcomes
of NK cell maligcies. PURPOSE: To morphometrically quantify CD1a+ dentritic cells and DC-SIGN+
dendritic cells in HIV-positive patients with anal squamous intraepithelial
neoplasia and to evaluate the effects of HIV infection, antiretroviral therapy
and HPV infection on epithelial and subepithelial dendritic cells.
METHODS: A prospective study was performed to morphometrically analyze the
relative volume of the dendritic cells and the relationship between anal
intraepithelial neoplasia and cancer in HIV-positive patients from the Tropical
Medicine Foundation of Amazonas, Brazil. All patients were submitted to biopsies
of anorectal mucosa to perform a classic histopathological and
immunohistochemical analysis, employing antibodies against CD1a and DC-SIGN for
the morphometric quantification of dendritic cells.
RESULTS: HIV-negative patients displayed a CD1a DC density significantly higher
than that of HIV-positives patients (3.75 versus 2.54) (p=0.018), and in
patients with severe anal intraepithelial neoplasia had correlated between DC
CD1a density with levels of CD4 + cells (p: 0.04) as well as the viral load of
HIV-1 (p: 0.035). A not significant rise in the median density of CD1a+ DC was
observed in the HIV positive/ HAART positive subgroup compared to the HIV
positive/ HAART negative subgroup. The CD1a+ DC were also significantly
increased in HIV-negative patients with anorectal condyloma (2.33 to 3.53;
p=0.05), with an opposite effect in HIV-positive patients.
CONCLUSIONS: Our data support an enhancement of the synergistic action caused by
HIV-HPV co-infection on the anal epithelium, weakening the DC for its major role
in immune surveillance. Notoriously in patients with severe anal intraepithelial
neoplasia, the density of CD1a+ epithelial dendritic cells was influenced by the
viral load of HIV-1. Our study describes for the first time the density of
subepithelial DC-SIGN+ dendritic cells in patients with anal severe anal
intraepithelial neoplasia and points to the possibility that a specific therapy
for HIV induces the recovery of the density of epithelial DC. It has been shown that silencing of suppressor of cytokine signalling 1 (Socs1)
or stably expressing transgenic protein Ags in antigen-presenting dentritic
cells (DCs) strongly enhances antigen-specific anti-tumour immunity. However,
whether the strong and long-lasting T cell responses induced by the modified DCs
could modulate the immunosuppressive tumour microenvironment has not been
clarified. In this study, we explored the anti-tumour immunity of DCs modified
by Socs1-shRNA lentiviral transduction combined with sustained expression of
TRP2 in different tumour models. We showed that transfer Socs1-silenced or
tumour antigen TRP2 persistent expressed DCs, or DCs modified by combination of
Socs1-silencing and sustaining TRP2 expression prior to inoculation of tumour
cells delayed B16 tumour cell growth, prolonged mouse survival and increased the
ratio of CD8+ T/Treg as well as the CTL activity in tumours. However, there was
no significant effect on tumour growth and mouse survival rate upon tumour
established. Further, we showed that tumour cell secreted IL-10 counteracted the
immunity of modified DCs in established tumour model, injection of Socs1-shRNA
and TRP2 antigen modified significantly inhibited growth of the established
B16-IL-10(-/-) tumours. These data indicated that the high level of IL-10 within
tumour microenvironment is one of factors that compromise DC vaccine functions. BACKGROUND: In the direct pathway, T cells recognize intact donor major
histocompatability complexes and allogeneic peptide on the surface of donor
antigen presenting cells (APCs). Indirect allorecognition results from the
recognition of processed alloantigen by self MHC complexes on self APCs. In this
study, we wished to evaluate the relative contribution of different intragraft
cells to the alloactivation of nave and memory T cells though the direct and the
indirect pathway of allorecognition.
METHODS: The processing of membrane fragments from IFN-treated single donor
endothelial cells (EC), fibroblasts or renal epithelial cells (RPTEC) was
evaluated by DiOC labeling of each cell type and flow cytometry following
interaction with PBMC. Direct pathway activation of nave CD45RA+ or memory
CD45RO+ CD4+ T cells was evaluated following coculture with IFN-treated and MHC
class II-expressing EC, fibroblasts or RPTEC. Indirect pathway activation was
assessed using CD45RA+ or CD45RO+ CD4+ T cells cocultured with autologous
irradiated APCs in the absence or presence of sonicates derived from IFN-treated
allogeneic EC, fibroblasts or RPTEC. Activation of T cells was assessed by
[3H]thymidine incorporation and by ELISpot assays.
RESULTS: We find that CD14+ APCs readily acquire membrane fragments from
fibroblasts and RPTEC, but fail to acquire membrane fragments from intact EC.
However, APCs process membranes from EC undergoing apoptosis.There was a notable
direct pathway alloproliferative response of CD45RO+ CD4+ T cells to IFN-treated
EC, but not to fibroblasts or RPTEC. Also, there was a minimal direct pathway
response of CD45RA+ CD4+ T cells to all cell types. In contrast, we found that
both CD45RA+ and CD45RO+ CD4+ T cells proliferated following coculture with
autologous APCs in the presence of sonicates derived from IFN-treated EC,
fibroblasts or RPTEC. By ELISpot, we found that these T cells stimulated via the
indirect pathway also produced the cytokines IFN, IL-2, IL-4 and IL-5.
CONCLUSIONS: Recipient APCs may readily process membrane fragments from
allogeneic intragraft cells, but not from EC unless they are undergoing
apoptosis. This processing is sufficient for indirect pathway alloactivation of
both CD45RA+ and CD45RO+ CD4+ T cells. Only graft vascular EC mediate direct
pathway reactivation of CD4+ T cells. The BAFF system plays a key role in the development of autoimmunity, especially
in systemic lupus erythematosus (SLE). This often leads to the assumption that
BAFF is mostly a B cell factor with a specific role in autoimmunity. Focus on
BAFF and autoimmunity, driven by pharmaceutical successes with the recent
approval of a novel targeted therapy Belimumab, has relegated other potential
roles of BAFF to the background. Far from being SLE-specific, the BAFF system
has a much broader relevance in infection, cancer and allergy. In this review,
we provide the latest views on additional roles of the BAFF system in health and
diseases, as well as an update on BAFF and autoimmunity, with particular focus
on current clinical trials. |
What is the mode of inheritance of nemaline myopathy? | Nemaline myopathy has a autosomal dominant or recessive mode of inheritance. | We present comparisons of the clinical pictures in a series of 60 patients with
nemaline myopathy in whom mutations had been identified in the genes for nebulin
or skeletal muscle alpha-actin. In the patients with nebulin mutations, the
typical form of nemaline myopathy predominated, while severe, mild or
intermediate forms were less frequent. Autosomal recessive inheritance had been
verified or appeared likely in all nebulin cases. In the patients with actin
mutations, the severe form of nemaline myopathy was the most common, but some
had the mild or typical form, and a few showed other associated features such as
intranuclear rods or actin accumulation. Most cases were sporadic, but in
addition there were instances of both autosomal domit and autosomal recessive
inheritance, while two families showed mosaicism for domit mutations.
Although no specific phenotype was found to be associated with mutations in
either gene, clinical and histological features together with pedigree data may
be used in guiding mutation detection. Finding the causative mutation(s)
determines the mode of inheritance and permits prenatal diagnosis if requested,
but will not as such permit prognostication. OBJECTIVE: To describe the clinical, morphologic, and genetic findings in a
family in which one woman had nemaline myopathy, whereas her daughter showed
features of cap disease.
PATIENTS: A 66-year-old woman and her 35-year-old daughter had congenital,
slowly progressive muscle weakness. They had weakness in both proximal and
distal muscles and facial diplegia with bilateral ptosis, a long narrow face, a
high arched palate, and micrognathia.
RESULTS: Muscle biopsy specimens in the mother at age 57 years had shown
nemaline myopathy, whereas a biopsy specimen at age 32 years had demonstrated no
rods. Muscle biopsy specimens in the daughter at age 26 years had shown features
of cap disease and no apparent nemaline rods. A missense mutation, Glu41Lys, in
the beta-tropomyosin gene TPM2 was identified in both patients but was absent in
their healthy relatives.
CONCLUSIONS: The results indicate that mutations in TPM2 may cause nemaline
myopathy as well as cap disease with a domit mode of inheritance. These
disorders may thus be phenotypic variants of the same genetic defect. |
Which syndrome is NHE6 associated with? | Mutations in the solute carrier family 9, subfamily A member 6 (SLC9A6) gene, encoding the endosomal Na+/H+ exchanger 6 (NHE6) are associated with Christianson syndrome, a syndromic form of X-linked intellectual disability characterized by microcephaly, severe global developmental delay, autistic behavior, early onset seizures and ataxia. | Neuronal arborization is regulated by cell-autonomous and nonautonomous
mechanisms including endosomal signaling via BDNF/TrkB. The endosomal Na⁺/H⁺
exchanger 6 (NHE6) is mutated in a new autism-related disorder. NHE6 functions
to permit proton leak from endosomes, yet the mechanisms causing disease are
unknown. We demonstrate that loss of NHE6 results in overacidification of the
endosomal compartment and attenuated TrkB signaling. Mouse brains with disrupted
NHE6 display reduced axonal and dendritic branching, synapse number, and circuit
strength. Site-directed mutagenesis shows that the proton leak function of NHE6
is required for neuronal arborization. We find that TrkB receptor colocalizes to
NHE6-associated endosomes. TrkB protein and phosphorylation are reduced in NHE6
mutant neurons in response to BDNF signaling. Finally, exogenous BDNF rescues
defects in neuronal arborization. We propose that NHE6 mutation leads to circuit
defects that are in part due to impoverished neuronal arborization that may be
treatable by enhanced TrkB signaling. OBJECTIVE: Recently, Christianson syndrome (CS) has been determined to be caused
by mutations in the X-linked Na(+) /H(+) exchanger 6 (NHE6). We aimed to
determine the diagnostic criteria and mutational spectrum for CS.
METHODS: Twelve independent pedigrees (14 boys, age = 4-19 years) with mutations
in NHE6 were administered standardized research assessments, and mutations were
characterized.
RESULTS: The mutational spectrum was composed of 9 single nucleotide variants, 2
indels, and 1 copy number variation deletion. All mutations were
protein-truncating or splicing mutations. We identified 2 recurrent mutations
(c.1498 c>t, p.R500X; and c.1710 g>a, p.W570X). Otherwise, all mutations were
unique. In our study, 7 of 12 mutations (58%) were de novo, in contrast to prior
literature wherein mutations were largely inherited. We also report prominent
neurological, medical, and behavioral symptoms. All CS participants were
nonverbal and had intellectual disability, epilepsy, and ataxia. Many had prior
diagnoses of autism and/or Angelman syndrome. Other neurologic symptoms included
eye movement abnormalities (79%), postnatal microcephaly (92%), and magnetic
resoce imaging evidence of cerebellar atrophy (33%). Regression was noted in
50%, with recurrent presentations involving loss of words and/or the ability to
walk. Medical symptoms, particularly gastrointestinal symptoms, were common.
Height and body mass index measures were below normal ranges in most
participants. Behavioral symptoms included hyperkinetic behavior (100%), and a
majority exhibited high pain threshold.
INTERPRETATION: This is the largest cohort of independent CS pedigrees reported.
We propose diagnostic criteria for CS. CS represents a novel neurogenetic
disorder with general relevance to autism, intellectual disability, Angelman
syndrome, epilepsy, and regression. |
What is known about the reimbursement of Viagra | Coverage of Viagra/Sildenafil for erectile dysfunction by health insurance plans is a contentious issue in developed countries. There are data of the limitations (6 per month) and co-payments (26.6%) by patients in the US.
The costs for Viagra/Sildenafil for PAH (pulmonary artery hypertension) appear to be covered by health insurances in the US. | The article describes the controversy about the question whether statutory
social health insurances are obliged to reimburse the costs for the treatment of
erectile dysfunction. Next to the question whether the 'Bundesausschuss der
Arzte und Krankenkassen' was entitled to decide it was highly controversial
whether erectile dysfunction is a disease according to the laws of social
insurance. This enforces more general considerations regarding the possibility
to define disease and the relevancy of a concept of disease for the
justification and limitation of socially ficed services in medicine. This paper discusses the problematic and sometimes implicit nature of some
central notions and criteria used in debates about inclusion (or exclusion) of
health care services in the health care benefit package. An analysis of
discussions about four health care services--lungtransplantation, statins,
(sildenafil (viagra) and rivastigmine--illustrates a case-by-case approach and
inconsistent use of criteria, which present a challenge to develop a
decision-making procedure in which important criteria or central notions can be
discussed explicitly. BACKGROUND: Inclusion or not of a treatment strategy in the publicly ficed
health care is really a matter of prioritisation. In Sweden priority setting
decisions are governed by law in which it is stated that decisions should be
guided by firstly the principle of need and secondly the principle of
cost-effectiveness.
OBJECTIVE: The purpose of the paper is to discuss and illustrate the roles of
need and cost-effectiveness in decisions on inclusion or not of treatment
strategies in the publicly ficed health care.
METHODS: The theoretical backgrounds of need and cost-effectiveness are
discussed in short, both with respect to their meaning and to their potential
roles in decisions on priority setting. Four treatment strategies, Viagra,
Rivastigmine, statins, and lung transplants, are analysed with respect to
whether either cost-effectiveness or need, or both, seem to have played a role
in the decisions of inclusion or not in the basic health care package.
RESULTS: Both need and cost-effectiveness are important and should be important
aspects when making decisions on priority setting. From the examples of the four
treatment strategies it seems that decisions are almost exclusively made with
reference to the principle of need.
CONCLUSIONS: The most evident conclusion to be drawn from this study is that
decisions on priority setting are almost solely based on the principle of need.
This implies that the principle of cost-effectiveness is given very little
space, which is a problem as this means an obvious risk of inefficient resource
use. OBJECTIVE: Erectile dysfunction (ED) affects approximately 30 million men in the
United States. The objectives of this study were to (1) assess the cost and
utilization of sildenafil citrate (Viagra), an oral therapeutic agent for ED, in
a large managed care organization (MCO) with a quantity limit of 6 units per
30-day supply and (2) describe the incidence of comorbid conditions and the
severity of cardiovascular disease in adult male users of sildenafil.
METHODS: Pharmacy claims for sildenafil were identified from an administrative
database of claims with dates of service in calendar year 2001 for male members
aged 18 years or older. Medical claims for MCO members who had sildenafil claims
were used to identify comorbid diseases and categorize patients by degree of
cardiovascular risk. High risk was defined as having at least 1 medical claim
with a diagnosis of diabetes mellitus, ischemic heart disease, abdominal aortic
aneurysm, or peripheral arterial disease, and medium risk was defined as not
having any diagnosis in the high-risk category but at least 1 cardiovascular
risk factor that included smoking, hypertension, hypercholesterolemia, family
history of premature coronary heart disease, or being aged 45 years or older.
RESULTS: There were 67,914 pharmacy claims for sildenafil during 2001 for 20,281
MCO members, an average of 3.3 pharmacy claims per patient. The prevalence of
sildenafil use was 54.1 per 1,000 male MCO members aged 18 years or older. The
total allowed charges for sildenafil pharmacy claims in 2001 were 3.56 million
US dollars, of which patients paid 26.6% in average cost-share, and the net MCO
cost per member per month (PMPM) was 0.18 US dollars. A total of 1,681 patients
(8.3%) exceeded their quantity restrictions for sildenafil tablets in 2001, of
which 1,362 (81.0%) paid cash and 319 (19.0%, or 1.6% of all sildenafil users)
appealed and received approval from the MCO for additional sildenafil tablets
beyond the restriction of 6 tablets per month. Medical claims were available for
15,644 sildenafil patients (77.1%), and 12,720 sildenafil users (81.3% of those
with medical claims) were judged to be at high or medium cardiovascular risk.
CONCLUSIONS: A quantity limit of 6 tablets of sildenafil per 30-day period was
associated with a drug cost to users and the MCO of 0.25 US dollars PMPM.
Sildenafil users paid an average cost-share of 26.6%, resulting in a net drug
cost of 0.18 US dollars PMPM to the MCO. BACKGROUND AND OBJECTIVE: Clinicians must choose between an increasing number of
medications for the treatment of pulmonary arterial hypertension (PAH) with
different routes of administration, adverse effects, costs and efficacies. We
constructed a decision analysis to help inform treatment choices in PAH.
METHODS: We created a Markov-type model to evaluate 1-year treatment with
bosentan, treprostinil, epoprostenol, inhaled iloprost, sildenafil, sitaxentan
and ambrisentan. Transition probabilities were based on observed transitions
between WHO functional classes, adjusted by relative risk of improvement in a
6-minute walk test. Utilities were based on reported values for each functional
class, adjusted for burden of treatment administration. Costs were estimated
from Medicare and Medicaid reimbursement data. Sensitivity analyses evaluated
changes in efficacy, utilities and costs.
RESULTS: Treatment with sildenafil was less costly and resulted in a greater
gain in quality-adjusted life-years (QALYs) compared with other treatments.
Treatment with ambrisentan and bosentan resulted in the same gain in QALYs as
sildenafil, but at a higher cost. Sensitivity analyses had minimal impact on
these results.
CONCLUSIONS: Based on this model, sildenafil is a cost-effective treatment for
PAH with a low price and a net increase in QALYs. The results from this analysis
are a tool to help guide clinicians in deciding which PAH medications to use;
however, the final decisions should be individualized because the effectiveness
of therapy, resulting utilities and acceptable costs will differ with each
patient. OBJECTIVE: To explore treatment patterns and resource utilization and cost for
subjects with pulmonary arterial hypertension (PAH).
RESEARCH DESIGN: Retrospective claims database analysis of 706 patients with PAH
enrolled in a large, geographically diverse US managed-care organization.
RESULTS: In the final sample of PAH patients treated with bosentan (n=251) or
sildenafil (n=455), average age was 57 years, 86% of patients were commercially
insured, and 52% of patients were male. Gender distribution varied significantly
across subgroups, with a lower proportion of males in the bosentan (30%)
subgroup compared with the sildenafil group (64%) (p<0.001). Average baseline
Charlson comorbidity score was 2.4. Average numbers of fills per month were 0.8
and 0.4 for bosentan and sildenafil patients, respectively (p<0.001). Over 80%
of patients received only one PAH treatment in the first 90 days following the
index date, with 28% of bosentan and 13% of sildenafil patients receiving
combination therapy (p<0.001). Over one-third of bosentan patients and
one-quarter of sildenafil patients experienced a dose increase in the follow-up
period (p=0.009). Sixteen percent of sildenafil patients experienced a dose
decrease in the follow-up period, while a smaller proportion of patients
receiving bosentan (4%) experienced a dose decrease (p<0.001). On average,
number of PAH-related per subject per month (PSPM) inpatient stays and emergency
department visits and PSPM length of inpatient stays were statistically similar
between the subgroups. PAH-related PSPM healthcare costs were high for both
subgroups, with average monthly costs of $5,332 and $3,632 among bosentan and
sildenafil patients, respectively (p=0.003). Differences in total costs were
driven mainly by differences in pharmacy expenditures.
CONCLUSIONS: Of the oral agents approved for treating PAH at the time of this
study, sildenafil was most commonly prescribed as index therapy and was also
associated with the lowest costs, largely due to significantly lower pharmacy
costs. This study is characterized by limitations inherent to claims database
analyses, such as the potential for coding errors and lack of information on
whether a drug was taken as prescribed. Furthermore, PAH severity (WHO
functional class) was not assessed. OBJECTIVES: To describe treatment patterns and healthcare burden among
individuals with suspected pulmonary arterial hypertension (PAH), as identified
through a practice guideline-based healthcare claims algorithm.
METHODS: Adults with evidence of PAH from 1 January 2004 (commercial and
Medicaid) or 1 July 2006 (Medicare Advantage) through 30 June 2008 were
identified. Given the lack of an ICD-9 code for PAH, an algorithm was developed
requiring: (1) ≥ 1 claim for PAH medication (index date); (2) ≥ 1 claim with a
pulmonary hypertension diagnosis code in the 6-month pre-index period (baseline)
or within 90 days post-index; (3) a right heart catheterization or pulmonary
hypertension-related inpatient stay during baseline or within 90 days
post-index; and (4) continuous health plan enrollment for 6 months pre-index and
≥ 6 months post-index. Patients with PAH-specific medications during baseline
were excluded. Treatment patterns, healthcare utilization, and costs were
assessed during the period ending with the earlier of health plan disenrollment
or 31 December 2008.
RESULTS: Among the 521 included patients, 69% were female. Most patients (94%)
initiated treatment with monotherapy (most commonly sildenafil or bosentan), and
12.7% of all patients augmented their therapy by the end of the observation
period. The medication possession ratio was 0.96 each for ambrisentan (SD=0.04),
bosentan (SD=0.04), and sildenafil (SD=0.05). Overall, 72.6% of patients
discontinued therapy with a mean of 149 (SD=170) days until discontinuation. A
mean (SD) of 2.14 (1.82) all-cause office and 1.64 (1.98) outpatient visits
occurred per patient per month. Mean PAH-related healthcare costs were $6617 per
patient per month, comprising 71% of all-cause costs. The guideline-based
algorithm may not have perfectly captured patients with PAH.
CONCLUSIONS: Patients with suspected PAH were likely to initiate treatment with
oral monotherapy, had high compliance rates, and received close ambulatory
follow-up. PAH-related costs constituted the majority of all-cause healthcare
costs. BACKGROUND: Little is known concerning the degree to which initiation of
sildenafil for pulmonary arterial hypertension (PAH) impacts patterns of
healthcare utilization and costs.
METHODS: Using a large US health insurance claims database, we identified all
patients with evidence of PAH (ICD-9-CM diagnosis codes 416.0, 416.8) who
received sildenafil between 1/1/2005 and 9/30/2008. Date of the first-noted
prescription for sildenafil was designated the "index date," and claims data
were compiled for all study subjects for 6 months prior to their index date
("pretreatment") and 6 months thereafter ("follow-up"); patients with incomplete
data during either of these periods were excluded. Healthcare utilization and
costs were then compared between pretreatment and follow-up for all study
subjects.
RESULTS: A total of 567 PAH patients were identified who began therapy with
sildenafil and met all other study entry criteria. Mean (SD) age was 52 (10)
years; 73% were women. Healthcare utilization was largely unchanged between
pretreatment and follow-up, the only exceptions being decreases in the mean
number of emergency department visits (from 0.7 to 0.5 per patient; p<0.01) and
the percentage of patients hospitalized (from 35% to 29%; p=0.01). The mean cost
of all PAH-related medication was $7139 during pretreatment and $14,095 during
follow-up (sildenafil cost during follow-up= $5236); exclusive of PAH-related
medications, however, total healthcare costs decreased modestly (from $30,104 to
$27,605) (p<0.01 for all comparisons).
CONCLUSIONS: The cost of sildenafil therapy may be partially offset by
reductions in other healthcare costs. |
Why is lock mass used in Orbitrap measurements? | The lock mass is a compound of known mass and is used to compensate for drifts in instrument calibration. | The positive role and application of highly accurate mass measurements in
proteomics is well documented. The new generation of hybrid FTMS and Q-TOF
instruments, including the LTQ-Orbitrap (OT), is remarkable in their ability to
routinely produce single-digit to subppm statistical mass accuracy while
maintaining high analytical sensitivity. The use of mass calibrants (lock
masses) to reduce the systematic error of mass-to-charge measurements has also
been reported and, in some cases, incorporated in the instrument control
software by the instrument manufacturers. We evaluated the use of one such
calibrant in the OT (e.g., polydimethylcyclosiloxane, PCM) to study its impact
on the rate of phosphopeptide annotation and found it to lack robustness under
normal laboratory conditions. Therefore, we devised a strategy to improve its
performance by increasing the external abundance of calibrant molecules in
laboratory air. This resulted in a more robust performance of the preprogrammed
lock mass recalibration feature as evidenced by improvements in both statistical
mass accuracy and peptide annotation rates. Mass accuracy is a key parameter in proteomic experiments, improving
specificity, and success rates of peptide identification. Advances in
instrumentation now make it possible to routinely obtain high resolution data in
proteomic experiments. To compensate for drifts in instrument calibration, a
compound of known mass is often employed. This 'lock mass' provides an internal
mass standard in every spectrum. Here we take advantage of the complexity of
typical peptide mixtures in proteomics to eliminate the requirement for a
physical lock mass. We find that mass scale drift is primarily a function of the
m/z and the elution time dimensions. Using a subset of high confidence peptide
identifications from a first pass database search, which effectively substitute
for the lock mass, we set up a global mathematical minimization problem. We
perform a simultaneous fit in two dimensions using a function whose
parameterization is automatically adjusted to the complexity of the analyzed
peptide mixture. Mass deviation of the high confidence peptides from their
calculated values is then minimized globally as a function of both m/z value and
elution time. The resulting recalibration function performs equal or better than
adding a lock mass from laboratory air to LTQ-Orbitrap spectra. This 'software
lock mass' drastically improves mass accuracy compared with mass measurement
without lock mass (up to 10-fold), with none of the experimental cost of a
physical lock mass, and it integrated into the freely available MaxQuant
analysis pipeline ( www.maxquant.org ). A recent trend in the use of high resolution accurate mass screening (HRAMS) for
doping control testing in both human and animal sports has emerged due to
significant improvement in high resolution mass spectrometry in terms of
sensitivity, mass accuracy, mass resolution, and mass stability. A number of
HRAMS methods have been reported for the detection of multi-drug residues in
human or equine urine. As blood has become a common matrix for doping control
analysis, especially in equine sports, a sensitive, fast and wide coverage
screening method for detecting a large number of drugs in equine blood samples
would be desirable. This paper presents the development of a liquid
chromatography-high resolution mass spectrometry (LC-HRMS) screening method for
equine plasma samples to cover over 320 prohibited substances in a single
analytical run. Plasma samples were diluted and processed by solid-phase
extraction. The extracts were then analyzed with LC-HRMS in full-scan positive
electrospray ionization mode. A mass resolution of 60 000 was employed.
Benzyldimethylphenylammonium was used as an internal lock mass. Drug targets
were identified by retention time and accurate mass, with a mass tolerance
window of ±3 ppm. Over 320 drug targets could be detected in a 13-min run.
Validation data including sensitivity, specificity, extraction recovery and
precision are presented. As the method employs full-scan mass spectrometry, an
unlimited number of drug targets can theoretically be incorporated. Moreover,
the HRAMS data acquired can be re-processed retrospectively to search for drugs
which have not been targeted at the time of analysis. |
Which virus is Cidofovir (Vistide) indicated for? | Cidofovir is commonly used in the treatment of cytomegalovirus (CMV) infection and disease. | A retrospective study was performed to collect information regarding efficacy
and toxicity of cidofovir (CDV) in allogeneic stem cell transplant patients.
Data were available on 82 patients. The indications for therapy were
cytomegalovirus (CMV) disease in 20 patients, primary preemptive therapy in 24
patients, and secondary preemptive therapy in 38 patients. Of the patients, 47
had received previous antiviral therapy with ganciclovir, foscarnet, or both
drugs. The dosage of CDV was 1 to 5 mg/kg per week followed by maintece every
other week in some patients. The duration of therapy ranged from 1 to 134 days
(median, 22 days). All patients received probenecid and prehydration. Ten of 20
(50%) patients who were treated for CMV disease (9 of 16 with pneumonia)
responded to CDV therapy, as did 25 of 38 (66%) patients who had failed or
relapsed after previous preemptive therapy and 15 of 24 (62%) patients in whom
CDV was used as the primary preemptive therapy. Of the patients, 21 (25.6%)
developed renal toxicity that remained after cessation of therapy in 12
patients. Fifteen patients developed other toxicities that were potentially due
to CDV or the concomitantly given probenecid. No toxicity was seen in 45 (61.6%)
patients. Cidofovir can be considered as second-line therapy in patients with
CMV disease failing previous antiviral therapy. However, additional studies are
needed before CDV can be recommended for preemptive therapy. Cytomegalovirus (CMV) infection is very common throughout the world, and has
become more of a pediatric clinical concern given the high incidence of
congenital CMV infections as well as the increasing numbers of immunocompromised
patients. Because of this, the need for antiviral therapies in infants and
neonates is growing. Currently, there are four antivirals available that are
active against CMV: ganciclovir, valganciclovir, foscarnet, and cidofovir. At
this time, none have approved indications for use in children. Although there
are limited data regarding the dose, pharmacokinetics (PK), safety, and adverse
events for some of these antivirals, ganciclovir, and its oral prodrug
valganciclovir, have been the best studied in the infant and neonate
populations. In general, pharmaceutical PK studies in young children are limited
by the constraints of sampling difficulties and blood volume requirements; fewer
sampling times and studies may be available for drug evaluation. Given this
caveat, ganciclovir and valganciclovir PK in children thus far appears to follow
a monocompartmental model, contrary to what has been described in adults.
However, when normalized for weight, the volume of distribution, clearance, and
half-life of ganciclovir are similar to those found in adults. Given the
findings that ganciclovir (and thus valganciclovir) clearance is directly
proportionate to renal function, care must be taken when administering the drug
to patients with impaired renal function. Recent studies evaluating
valganciclovir PK in infants (at a dose of 16 mg/kg every 12 hours) have shown
similar areas under the plasma concentration-time curve (AUCs) to intravenous
ganciclovir (at a dose of 6 mg/kg every 12 hours), and that these AUCs remain
quite stable over a number of weeks. As seen in adults, oral ganciclovir has a
low bioavailability (4.8% in a pediatric analysis) and is therefore a poor
alternative for treating serious CMV infections. Neutropenia is the most
frequent toxicity associated with ganciclovir and valganciclovir therapy,
whereas significant (and possibly irreversible) renal toxicity can be seen with
cidofovir. Foscarnet administration can also result in renal toxicity as well as
significant electrolyte imbalances. Several of these drugs have potential
toxicities that are of concern, including carcinogenesis, teratogenesis, and
azospermia (ganciclovir, valganciclovir, and cidofovir) and deposition into bone
or dentition (foscarnet) that may have significant implications when treating an
infant. Given these potential ill effects, careful consideration of the
indications for the clinical use of these antivirals is necessary before using
them for CMV infection in neonates and infants. |
Have gnotobiotic animal models been used for the study of bowel disease? | Yes, gnotobiotic animals (e.g. mice) have been used for the study of bowel disease (e.g. inflammatory bowel disease). | The pathogenesis of enteric changes was studied in gnotobiotic piglets which,
after hysterectomy had been infected orally with Campylobacter jejuni on the
first day of their life. The involvement of the entire large intestine became
clinically manifest by scouring on days post infection (DPI) 4 to DPI 5, and
pathomorphologically, by simultaneous inflammation and severe edema of the
intestinal wall. Histology and SEM revealed inflammatory edema with abundant
neutrophils, microulcerations, focal propagation and activation of goblet cells,
and a presence of mucin-positive material within the intestinal lumen. TEM
examination revealed disconnected interdigitating folds and wide dilated
intercellular spaces between enterocytes. The endothelial cells of small blood
vessels in the lamina propria showed hypertrophy with increase in the thickness
of their basal lamina. Ultrastructural lesions of the large intestinal
microcirculation also support the hypothesis that disturbances in the vascular
system are responsible for edema in the cecum and colon. Gnotobiotic piglets may
be used as a suitable animal model to study colitis induced by C. jejuni. BACKGROUND & AIMS: Recently, a number of animal models for different aspects of
inflammatory bowel disease (IBD) have been developed. The aim of this study was
to use one of these to determine whether particular, ostensibly innocuous,
intestinal bacteria could provoke or exacerbate IBD.
METHODS: Conventionally reared C.B17 SCID mice were compared with germ-free and
gnotobiotic mice, monoassociated with 1 of 5 intestinal bacteria, after transfer
of CD45RB(high) CD4(+) T cells from conventionally reared congenic BALB/c mice.
Recipient mice were monitored over 7-12 weeks for clinical signs of IBD, and
tissues were analyzed by histology/flow cytometry for abnormal inflammation and
CD4(+) T cell outgrowth.
RESULTS: Neither germ-free mice nor mice monoassociated with segmented
filamentous bacteria, Ochrobactrum anthropi, a nonpathogenic mutant of Listeria
monocytogenes, or Morganella morganii developed any signs of IBD. In contrast,
mice monoassociated with Helicobacter muridarum displayed an accelerated
development of IBD in 5-6 weeks compared with 8-12 weeks observed in
conventionally reared mice. The outgrowth of CD4(+) T cells in spleen and large
intestine of H. muridarum monoassociated mice, as well as in conventionally
reared mice was significantly higher than that in the other monoassociated mice.
CONCLUSIONS: Among the intestinal bacteria tested, H. muridarum can serve as a
provocateur of IBD in this model. Bacteroides, a predomit commensal bacteria in the gut, are thought to be
responsible for the development of inflammatory bowel disease (IBD). In the
present study, we examined whether or not bifidobacteria suppress B. vulgatus, a
representative pathogenic Bacteroides species, in both the coculture system and
the gnotobiotic murine model. As a result, Bifidobacterium infantis 1222 highly
inhibited the growth of B. vulgatus in the coculture and also significantly
suppressed the systemic antibody response raised by B. vulgatus colonizing the
gut in gnotobiotic mice. Colonization of the mice by B. vulgatus increased the
number of Peyer's patch (PP) cells bearing PNA (peanut agglutinin)+/anti-kappa+
phenotype, which represents plasma cell-like B cells. Moreover, treatment of
those B. vulgatus-implanted mice with B. infantis 1222 abrogated such increase
in the number of PNA+/anti-kappa+ cells. These results thus suggested that B.
infantis 1222 protected the gut epithelial layer including the PP from being
invaded by Bacteroides, thereby suppressing the systemic antibody response
raised by Bacteroides. Initial events and effector mechanisms of most inflammatory and autoimmune
diseases remain largely unknown. Dysfunction of the innate and adaptive immune
systems associated with mucosae (the major interface between the organism and
its environment, e.g., microbiota, food) can conceivably cause impairment of
mucosal barrier function and development of localized or systemic inflammatory
and autoimmune processes. Animal models help in elucidating the etiology and
pathogenetic mechanisms of human diseases, such as the inflammatory bowel
diseases, Crohn's disease and ulcerative colitis, severe chronic diseases
affecting the gut. To study the role of innate immunity and gut microbiota in
intestinal inflammation, colitis was induced by dextran sulfate sodium (DSS) in
mice with severe combined immunodeficiency (SCID). Conventionally reared
(microflora-colonized) SCID mice displayed severe inflammation like that seen in
immunocompetent Balb/c mice, whereas only minor changes appeared in the
intestinal mucosa of DSS-fed gnotobiotic germ-free SCID mice. The presence of
microflora facilitates the inflammation in DSS-induced colitis that develops in
immunodeficient SCID mice, that is, in the absence of T and B lymphocytes.
Celiac disease, a chronic autoimmune small bowel disorder, afflicts genetically
susceptible individuals with wheat gluten intolerance. We showed that, in
contrast with any other food proteins, wheat gliadin and its peptic fragments
activate mouse macrophages and human monocytes to produce proinflammatory
cytokines through the nuclear factor-kappaB signaling pathway. Activation of
innate immunity cells by food proteins or components from gut microbiota thus
could participate in the impairment of intestinal mucosa and the development of
intestinal and/or systemic inflammation. BACKGROUND: Specific pathogen-free (SPF), but not germfree (GF), interleukin
(IL)-2-deficient (IL-2-/-) mice develop inflammatory bowel disease (IBD) at 10
to 15 weeks of age. Gnotobiotic IL-2-/- mice monocolonized with E. coli mpk
develop IBD at 25 to 33 weeks of age but not B. vulgatus mpk, E. coli Nissle
1917, or mice cocolonized with both E. coli mpk and B. vulgatus.
METHODS: To determine genes regulated by these commensal bacteria, host gene
expression in the colon of 8-week-old IL-2-/- mice was compared by using
microarrays and semiquantitative reverse-transcription polymerase chain
reaction. Colonization with E. coli mpk/B. vulgatus or SPF microbiota altered
the gene expression profile more profoundly than monocolonization with either B.
vulgatus, E. coli mpk or E. coli Nissle indicating that the complexity of the
gene expression pattern is influenced by the diversity of the microbiota.
RESULTS: A small but distinct group of genes could be defined which might be
associated with colitis development. Thus, 8 week old E. coli mpk IL-2-/- mice
rone to colitis compared to E. coli Nissle, B. vulgatus and E. coli mpk/B.
vulgatus IL-2-/- mice displayed a lower expression of the anti-inflammatory
RegIII family genes such as RegIII[gamma] and pancreatitis associated protein
(PAP) and peroxisome proliferator-activated receptor-[gamma] regulated genes
such as adipsin and adiponectin.
CONCLUSION: The increased expression of these genes in B. vulgatus colonized
mice might be associated with prevention of E. coli mpk triggered colitis in E.
coli mpkM/B. vulgatus IL-2-/- mice. BACKGROUND & AIMS: Klotho (KL) is an anti-inflammatory protein that protects the
endothelium from nitric oxide (NO)-induced dysfunction, reduces the expression
of endothelial adhesion molecules, and potentially regulates T-cell functions.
KL deficiency leads to premature senescence and impaired Ca2+/Pi homeostasis,
which can lead to inflammatory bowel disease (IBD)-associated
osteopenia/osteoporosis. We investigated the changes in renal expression of Kl
as a consequence of colitis.
METHODS: We studied 3 mouse models of IBD: colitis induced by trinitrobenzene
sulfonic acid, colitis induced by microflora (in gnotobiotic
interleukin-10(-/-)), and colitis induced by adoptive transfer of
CD4(+)CD45RB(high) T cells. Effects of the tumor necrosis factor (TNF) and
interferon (IFN)-gamma on Kl expression and the activity of its promoter were
examined in renal epithelial cells (mpkDCT4 and mIMCD3).
RESULTS: Renal expression of Kl messenger RNA (mRNA) and protein was reduced in
all 3 models of IBD. Reduced level of KL correlated with the severity of
colitis; the effect was reversed by neutralizing antibodies against TNF. In
vitro, TNF inhibited Kl expression, an effect potentiated by IFN-gamma. The
combination of TNF and IFN-gamma increased expression of inducible nitric oxide
synthase (iNOS) and increased NO production. The effect of IFN-gamma was
reproduced by exposure to an NO donor and reversed by the iNOS inhibitor. In
cells incubated with TNF and/or IFN-gamma, Kl mRNA stability was unaffected,
whereas Kl promoter activity was reduced, indicating that these cytokines
regulate Kl at the transcriptional level.
CONCLUSIONS: The down-regulation of KL that occurs during inflammation might
account for the extraintestinal complications such as abnormalities in bone
homeostasis that occur in patients with IBD. Metagenomic approaches are currently being used to decipher the genome of the
microbiota (microbiome), and, in parallel, functional studies are being
performed to analyze the effects of the microbiota on the host. Gnotobiological
methods are an indispensable tool for studying the consequences of bacterial
colonization. Animals used as models of human diseases can be maintained in
sterile conditions (isolators used for germ-free rearing) and specifically
colonized with defined microbes (including non-cultivable commensal bacteria).
The effects of the germ-free state or the effects of colonization on disease
initiation and maintece can be observed in these models. Using this approach
we demonstrated direct involvement of components of the microbiota in chronic
intestinal inflammation and development of colonic neoplasia (i.e., using models
of human inflammatory bowel disease and colorectal carcinoma). In contrast, a
protective effect of microbiota colonization was demonstrated for the
development of autoimmune diabetes in non-obese diabetic (NOD) mice.
Interestingly, the development of atherosclerosis in germ-free apolipoprotein E
(ApoE)-deficient mice fed by a standard low-cholesterol diet is accelerated
compared with conventionally reared animals. Mucosal induction of tolerance to
allergen Bet v1 was not influenced by the presence or absence of microbiota.
Identification of components of the microbiota and elucidation of the molecular
mechanisms of their action in inducing pathological changes or exerting
beneficial, disease-protective activities could aid in our ability to influence
the composition of the microbiota and to find bacterial strains and components
(e.g., probiotics and prebiotics) whose administration may aid in disease
prevention and treatment. To model inflammatory bowel disease, we assessed infection with Helicobacter
hepaticus 3B1 (ATCC 51449) and a potential probiotic Lactobacillus reuteri (ATCC
PTA-6475) in gnotobiotic B6.129P2-IL-10(tm1Cgn) (IL-10(-/-) ) mice. No
typhlocolitis developed in germ-free controls (n=21) or in L. reuteri (n=8) or
H. hepaticus (n=18) mono-associated mice for 20 weeks post-infection. As
positive controls, three specific pathogen-free IL-10(-/-) mice dosed with H.
hepaticus developed severe typhlocolitis within 11 weeks. Because L. reuteri
PTA-6475 has anti-inflammatory properties in vitro, it was unexpected to observe
significant typhlocolitis (P<0·0001) in mice that had been infected with L.
reuteri followed in 1 week by H. hepaticus (n=16). The H. hepaticus colonization
was not affected through 20 weeks post-infection but L. reuteri colonization was
lower in co-infected compared with L. reuteri mono-associated mice at 8-11 weeks
post-infection (P<0·05). Typhlocolitis was associated with an increased T helper
type 1 serum IgG2c response to H. hepaticus in co-infected mice compared with H.
hepaticus mono-associated mice (P<0·005) and similarly, mRNA expression in
caecal-colonic tissue was elevated at least twofold for chemokine ligands and
pro-inflammatory interleukin-1α (IL-1α), IL-1β, IL-12 receptor, tumour necrosis
factor-α and inducible nitric oxide synthase. Anti-inflammatory transforming
growth factor-β, lactotransferrin, peptidoglycan recognition proteins, Toll-like
receptors 4, 6, 8 and particularly 9 gene expression, were also elevated only in
co-infected mice (P<0·05). These data support that the development of
typhlocolitis in H. hepaticus-infected IL-10(-/-) mice required co-colonization
with other microbiota and in this study, required only L. reuteri. Although the
effects other microbiota may have on H. hepaticus virulence properties remain
speculative, further investigations using this gnotobiotic model are now
possible. Campylobacter jejuni infections have a high prevalence worldwide and represent a
significant socioeconomic burden. C. jejuni can cross the intestinal epithelial
barrier as visualized in biopsies derived from human patients and animal models,
however, the underlying molecular mechanisms and associated immunopathology are
still not well understood. We have recently shown that the secreted serine
protease HtrA (high temperature requirement A) plays a key role in C. jejuni
cellular invasion and transmigration across polarized epithelial cells in vitro.
In the present in vivo study we investigated the role of HtrA during C. jejuni
infection of mice. We used the gnotobiotic IL-10(-/-) mouse model to study
campylobacteriosis following peroral infection with the C. jejuni wild-type (WT)
strain NCTC11168 and the isogenic, non-polar NCTC11168ΔhtrA deletion mutant. Six
days post infection (p.i.) with either strain mice harbored comparable
intestinal C. jejuni loads, whereas ulcerative enterocolitis was less pronounced
in mice infected with the ΔhtrA mutant strain. Moreover, ΔhtrA mutant infected
mice displayed lower apoptotic cell numbers in the large intestinal mucosa, less
colonic accumulation of neutrophils, macrophages and monocytes, lower large
intestinal nitric oxide, IFN-γ, and IL-6 as well as lower TNF-α and IL-6 serum
concentrations as compared to WT strain infected mice at day 6 p.i. Notably,
immunopathological responses were not restricted to the intestinal tract given
that liver and kidneys exhibited mild histopathological changes 6 days p.i. with
either C. jejuni strain. We also found that hepatic and renal nitric oxide
levels or renal TNF-α concentrations were lower in the ΔhtrA mutant as compared
to WT strain infected mice. In conclusion, we show here that the C. jejuni HtrA
protein plays a pivotal role in inducing host cell apoptosis and immunopathology
during murine campylobacteriosis in the gut in vivo. |
List chromosomes that have been linked to Arnold Chiari syndrome in the literature. | Chromosomes 1, 3, 5, 6, 8, 9, 12, 13, 15, 16, 18, 22, X and Y have been reported in association with Arnold Chiari syndrome in genetic linkage studies and individual case reports. | A variety of anomalies of the central nervous system are observed in trisomy 18.
The present case describes an infant having a type II Arnold-Chiari malformation
without spina bifida. One previous case of an Arnold-Chiari malformation was
reported in trisomy 18 but that infant also had a lumbar meningomyelocoele.
Abnormalities of cerebral gyration, hydrocephalus, and agenesis of the corpus
callosum were also found in the present case. A rare case of syringomyelia associated with Arnold-Chiari malformation, primary
IgA deficiency and sex chromosomal abnormality is reported. A 26-year-old
Ethiopian black male was admitted with a complaint of hypalagesia of his left
arm and face for 10 years. Neurological examination on admission revealed
dissociated sensory loss of his left arm and face. Mild motor weakness of his
hand and rotatory nystagmus on left gaze were also noticed. Plain craniogram of
lateral view showed small posterior cranial fossa with low positioned inion and
platybasia. MRI with T1-weighted images in sagittal plane revealed tonsillar
herniation reaching C1 and syrinx extending from C2 to lumbar region. Although
no episode of infectious disease nor allergy were experienced, blood analysis
disclosed low serum level of IgA (7 mg/dl). The values of other immunoglobulins
were within normal range. IgA in saliva was not detected, too. According to the
clinical history and symptoms, a diagnosis is of primary asymptomatic IgA
deficiency was obtained. Karyotype analysis showed inversion of Y chromosome. In
an attempt to avoid anaphylactic shock on blood transfusion in a patient with
IgA deficiency, autologous blood was prepared before surgery. Decompressive
craniectomy of the posterior fossa with posterior arch of C1 and C2 was
performed together with syringosubarachnoid shunt at Th 6-7 level. Postoperative
course was successful and slight improvement of sensory disturbance was
obtained. No respiratory or wound infection was occurred. The association of
these three anomalies is very rare and genetical relationship is not known. From
surgical point of view, it is conceivable that preoperative management in a case
of asymptomatic IgA deficiency is uneventful. The clinical features and morphological findings in 31 Japanese infants with
trisomy 18 are presented. The majority were small-for-date infants. There was no
sex predomice in our series, as opposed to male:female ratios of 1:3 reported
in the literature. The average age at death was greater in females than in
males. Cardiovascular anomalies were consistently present; ventricular septar
defect and patent ductus arteriosus being the most common malformations. Various
other internal malformations including the Arnold-Chiari malformation were
observed. A patient with microbrachycephaly, high forehead, long philtrum, thin upper lip,
downturned corners of the mouth, low set ears with overlapping helix,
fifth-finger clinodactyly, small hands and feet, bilateral transverse palmar
crease, low total finger ridge count, hypotonia, severe growth and psychomotor
delay, mild hypoplasia of corpus callosum, and Arnold-Chiari type 1 malformation
is reported. The karyotype showed 46, XY, del(1)(q23q31.2). Coagulation factor V
(F5, 1q23) and coagulation factor XIII (F13B, 1q31-q32.1) levels were normal. As
expected, antithrombin III (AT3, 1q23-q25.1) serum level and activity were half
of normal. We performed a review of the literature on proximal and intermediate
deletion 1q syndrome, and we hypothesize the existence of only one 1q
interstitial deletion syndrome, clinically characterized by ATIII deficiency. Interstitial deletions of the middle portion of the long arm of chromosome 5 are
relatively rare. So far, only 36 cases have been reported. Because of the
repetitive banding pattern of this region, the extent and localization of the
deleted segment has not been well characterized in the majority of reported
cases. This has complicated attempts to establish a definite karyotype-phenotype
correlation. We report a further case with a de novo interstitial deletion of
the region 5q?15 to 5q?22 identified by standard karyotype analysis. The proband
presented with failure to thrive, developmental delay, distinct craniofacial
dysmorphic features, and associated structural anomalies (amongst them cleft
palate, iris colobomata, and horseshoe kidney, which have previously been
reported in 5q deletion cases). In addition, this child had an Arnold-Chiari
type I malformation that required surgical decompression. FISH studies using BAC
clones spanning the 5q15 to 5q22 region revealed that these were all present in
both homologues. Use of more distal clones allowed delineation of the deleted
region to 5q22.3q23.3 and to narrow down the breakpoints to approximately 200
kb. The 14 Mb deleted region contains about 60 genes but, with the possible
exception of FBN2 and DMXL1, there are no obvious candidate genes for the
specific components of the phenotype. This case illustrates the discrepancy
between cytogenetic and molecular techniques in trying to delineate 5q
interstitial deletions. Molecular studies need to be performed on these
patients, to establish genotype-phenotype correlation and to understand the role
and influence of genes in this region. Chiari type I malformation (CMI; OMIM 118420) is narrowly defined when the
tonsils of the cerebellum extend below the foramen magnum, leading to a variety
of neurological symptoms. It is widely thought that a small posterior fossa (PF)
volume, relative to the total cranial volume leads to a cramped cerebellum and
herniation of the tonsils into the top of the spinal column. In a collection of
magnetic resoce imagings (MRIs) from affected individuals and their family
members, we measured correlations between ten cranial morphologies and estimated
their heritability in these families. Correlations between bones delineating the
PF and significant heritability of PF volume (0.955, P = 0.003) support the
cramped PF theory and a genetic basis for this condition. In a collection of 23
families with 71 affected individuals, we performed a genome wide linkage screen
of over 10,000 SNPs across the genome to identify regions of linkage to CMI.
Two-point LOD scores on chromosome 15 reached 3.3 and multipoint scores in this
region identified a 13 cM region with LOD scores over 1 (15q21.1-22.3). This
region contains a biologically plausible gene for CMI, fibrillin-1, which is a
major gene in Marfan syndrome and has been linked to Shprintzen-Goldberg
syndrome, of which CMI is a distinguishing characteristic. Multipoint LOD scores
on chromosome 9 maximized at 3.05, identifying a 40 cM region with LOD scores
over 1 (9q21.33-33.1) and a tighter region with multipoint LOD scores over 2
that was only 8.5 cM. This linkage evidence supports a genetic role in Chiari
malformation and justifies further exploration with fine mapping and
investigation of candidate genes in these regions. Pentasomy 49,XXXXY occurs in 1/85,000 newborn males. The origin of this
particular form of aneuploidy is believed to be a result of consecutive
nondisjunction events during maternal meiosis. Typical presentation consists of
hypotonia, developmental delay, various dysmorphic features, and severe
hypogenitalism. A 13-year-old with pentasomy 49,XXXXY and a Chiari type 1
malformation with an associated cervical syrinx is presented. Rubinstein-Taybi Syndrome (RSTS, OMIM 180849) is a rare condition, which in 65%
of cases is caused by haploinsufficiency of CREBBP (cAMP response element
binding protein binding protein) localized to 16p13.3. A small subset of RSTS
cases caused by 16p13.3 microdeletions involving neighboring genes have been
recently suggested to be a true contiguous gene syndrome called severe RSTS or
16p13.3 deletion syndrome (OMIM 610543). In the present report, we describe a
case of a 2-year-old female with RSTS who, besides most of the typical features
of RSTS has corpus callosum dysgenesis and a Chiari type I malformation which
required neurosurgical decompression. CGH microarray showed a approximately
520.7 kb microdeletion on 16p13.3 involving CREBBP, ADCY9, and SRL genes. We
hypothesize that the manifestations in this patient might be influenced by the
haploinsufficiency for ADCY9 and SRL. A combination of the congenital abnormalities, Müllerian duct aplasia, renal
aplasia, and cervicothoracic somite dysplasia, is defined as the MURCS
association. Various genetic defects have been described in the MURCS
association so far, yet the unambiguous molecular basis of these disorders has
not been established. We report the case of an 18-year-old woman who presented
with primary amenorrhea, right kidney, Arnold-Chiari malformation, and
Klippel-Feil syndrome. In addition, the patient showed the following unusual
features: right ovarian and Skenes gland agenesis, cubitus valgus with
hyperextension and decreased range of motion at elbows, and facial changes.
Moreover, the performed DNA analysis showed interstitial duplication in
chromosome 5 (5q35.1). In the duplicated region, there are genes whose function
is not well known. It is thought that they have an influence on the early stages
of development and their joining in the later period can lead to neoplastic
disorders, especially leukemias. Chiari Type I Malformation (CMI) is characterized by displacement of the
cerebellar tonsils below the base of the skull, resulting in significant
neurologic morbidity. Although multiple lines of evidence support a genetic
contribution to disease, no genes have been identified. We therefore conducted
the largest whole genome linkage screen to date using 367 individuals from 66
families with at least two individuals presenting with nonsyndromic CMI with or
without syringomyelia. Initial findings across all 66 families showed minimal
evidence for linkage due to suspected genetic heterogeneity. In order to improve
power to localize susceptibility genes, stratified linkage analyses were
performed using clinical criteria to differentiate families based on etiologic
factors. Families were stratified on the presence or absence of clinical
features associated with connective tissue disorders (CTDs) since CMI and CTDs
frequently co-occur and it has been proposed that CMI patients with CTDs
represent a distinct class of patients with a different underlying disease
mechanism. Stratified linkage analyses resulted in a marked increase in evidence
of linkage to multiple genomic regions consistent with reduced genetic
heterogeneity. Of particular interest were two regions (Chr8, Max LOD = 3.04;
Chr12, Max LOD = 2.09) identified within the subset of "CTD-negative" families,
both of which harbor growth differentiation factors (GDF6, GDF3) implicated in
the development of Klippel-Feil syndrome (KFS). Interestingly, roughly 3-5% of
CMI patients are diagnosed with KFS. In order to investigate the possibility
that CMI and KFS are allelic, GDF3 and GDF6 were sequenced leading to the
identification of a previously known KFS missense mutation and potential
regulatory variants in GDF6. This study has demonstrated the value of reducing
genetic heterogeneity by clinical stratification implicating several convincing
biological candidates and further supporting the hypothesis that multiple,
distinct mechanisms are responsible for CMI. The first child (proband) of nonconsanguineous Caucasian parents underwent
genetic investigation because she was affected with congenital choanal atresia,
heart defects and kidney hyposplasia with mild transient renal insufficiency.
The direct DNA sequencing after PCR of the CHD7 gene, which is thought to be
responsible for approximately 60-70% of the cases of CHARGE
syndrome/association, found no mutations. The cytogenetic analysis (standard GTG
banding karyotype) revealed the presence of extrachromosomal material on 10q.
The chromosome analysis was completed with array CGH (30 kb resolution), MLPA
and FISH, which allowed the identification of three 6p regions (6p.25.3p23 × 3):
2 of these regions are normally located on chromosome 6, and the third region is
translocated to the long arm of chromosome 10. The same chromosomal
rearrangement was subsequently found in the father, who was affected with
congenital ptosis and progressive hearing loss, and in the proband's sister, the
second child, who presented at birth with choanal atresia and congenital heart
defects. The mutated karyotypes, which were directly inherited, are thought to
be responsible for a variable phenotype, including craniofacial dysmorphisms,
choanal atresia, congenital ptosis, sensorineural hearing loss, heart defects,
developmental delay, and renal dysfunction. Nevertheless, to achieve a complete
audiological assessment of the father, he underwent further investigation that
revealed an increased level of the coagulation factor XIII (300% increased
activity), fluctuating levels of fibrin D-dimer degradation products (from 296
to 1,587 ng/ml) and a homoplasmic mitochondrial DNA mutation: T961G in the
MTRNR1 (12S rRNA) gene. He was made a candidate for cochlear implantation.
Preoperative high-resolution computed tomography and magnetic resoce imaging
of the temporal bone revealed the presence of an Arnold-Chiari malformation type
I. To the best of our knowledge, this study is the second report on partial 6p
trisomy that involves the 10q terminal region. Furthermore, we report the first
case of documented Arnold-Chiari malformation type I and increased factor XIII
activity associated with 6p trisomy. We present a comprehensive report of the
familial cases and an exhaustive literature review. |
Which translocation is the hallmark of Ewing sarcoma? | Tumours defined as Ewing sarcoma (ES) constitute a group of highly malignant neoplasms that most often affect children and young adults in the first 2 decades of life. The EWS/Fli-1 fusion gene, a product of the translocation t(11;22) (q24; 12), is detected in 95% of ES patients | PURPOSE: To describe a patient with metastasis of Ewing sarcoma to the choroid
and the molecular genetics of the tumor.
METHODS: A 26-year-old woman with metastatic Ewing sarcoma developed large
choroidal masses in the left eye and died 2 months later. Autopsy of the eyes
was performed. Dual-color fluorescent in situ hybridization was used to detect
genetic alteration in the ocular tumor with EWS and FLI-1 probes.
RESULTS: Histopathology confirmed choroidal metastatic Ewing sarcoma. Molecular
analysis showed chromosomal translocation t(11;22)(q24;q12) or EWS/FLI-1
rearrangement in the maligt cells of the eye.
CONCLUSIONS: Ewing sarcoma can rarely metastasize to the uvea. Molecular
detection of the t(11;22)(q24;q12) translocation in Ewing sarcoma is valuable in
the differential diagnosis of small round cell tumors. Primitive neuroectodermal tumors are in the Ewing's sarcoma family of tumors and
are composed of small round cells. Because of their rare occurrence, optimal
therapy is challenging, particularly if they occur in the head and neck.
Diagnosis is based on history, immunostaining with at least 2 neural markers,
ultrastructural examination, and evidence of an abnormal t(11;22)(q24;q12)
translocation as the hallmark for the Ewing's sarcoma family. The prognosis in
general is poor because of overt metastasis at the time of diagnosis. Of 27
reported patients with primitive neuroectodermal tumors of the head and neck, 23
were less than 20 years of age. Most patients presented with a tumor in the
nasal cavity, paranasal sinuses, or neck. Symptoms developed rapidly (3.6
months, on average), and a lethal outcome occurred in 9 patients. This highly
maligt tumor requires an aggressive combination of radical resection,
chemotherapy, and radiotherapy. A close follow-up with regular radiographic
examination for at least 5 years is mandatory. EWS-Fli1, a fusion gene resulting from a chromosomal translocation t(11;22,
q24;q12) and found in Ewing sarcoma and primitive neuroectodermal tumors,
encodes a transcriptional activator and promotes cellular transformation.
However, the precise biological functions of its products remain unknown. To
investigate the role of EWS-Fli1 in cell growth signaling, we transfected Ewing
sarcoma TC-135 cells with short interfering RNAs for EWS-Fli1. EWS-Fli1
knockdown reduced cell growth and platelet-derived growth factor
(PDGF)-BB-induced activation of the growth signaling enzymes. Interestingly,
phospholipase D2 (but not the PDGF-BB receptor) showed marked down-regulation in
the EWS-Fli1-knocked down TC-135 cells compared with the control cells. In Ewing
sarcoma TC-135 cells, the PDGF-BB-induced phosphorylation of growth signaling
involving extracellular signal-regulated kinase, Akt, p70S6K, and the expression
of cyclin D3 were markedly inhibited by transfection with short interfering RNA
phospholipase (PL)-D2. The PDGF-BB-induced activation of growth signaling was
also suppressed by 1-butanol, which prevents the production of phosphatidic acid
by phospholipase D (but not by t-butyl alcohol), thereby implicating PLD2 in
PDGF-BB-mediated signaling in TC-135 cells. These results suggest that EWS-Fli1
may play a role in the regulation of tumor proliferation-signaling enzymes via
PLD2 expression in Ewing sarcoma cells. Ewing's sarcoma (ES) is a highly maligt tumor composed of uniform small round
cells. Recently, a single biologic entity, Ewing's sarcoma family of tumors
(ESFT) has been accepted. The entity includes ES, extraskeletal Ewing's sarcoma
(EES) and primitive neuroectodermal tumor (PNET). ESFT cells have
immunoreactivity for CD99, an antigen determined by the MIC2 gene. Most ESFT has
the (11;22) (q24;q12) translocation. The translocation results in the fusion of
the EWS gene with the transcription factor gene FLI1 which has been considered a
hallmark of ESFT. We present an extremely unusual case with ESFT in a spinal
nerve root mimicking a neurogenic dumbbell tumor. A male aged 20 years noticed
pain in his right buttock. Magnetic resoce imaging (MRI) revealed a mass in
the right L5/S intervertebral foramen and the lesions in the sacrum. Surgery was
performed with a presumptive diagnosis of a nerve sheath tumor. At surgery, the
tumor was located in the right L5 nerve root sleeve. The sacral lesions were
observed closely. At one month after surgery, radiologically multiple lesions
were detected in the pelvic bones. Microscopically the lesions from the root and
ilium were composed of small round cells immunoreactive for CD99. Reverse
transcription-polymerase chain reaction detected transcripts resulting from the
fusion of the EWS gene with FLI1 genes in the iliac lesion. Immunoreactivity for
CD99 and detection of the EWS-FLI1 hybrid transcripts are important for the
correct diagnosis of ESFT arising in an unusual location. Ewing/PNET (peripheral neuroepithelioma) tumors are rare aggressive bone
sarcomas occurring in young people. Rare-disease clinical trials can require
global collaborations and many years. In vivo models that as accurately as
possible reflect the clinical disease are helpful in selecting therapeutics with
the most promise of positive clinical impact. Human Ewing/PNET sarcoma cell
lines developed over the past 45 years are described. Several of these have
undergone genetic analysis and have been confirmed to be those of Ewing/PNET
sarcoma. The A673 Ewing sarcoma line has proven to be particularly useful in
understanding the biology of this disease in the mouse. The chromosomal
translocation producing the EWS/FLI1 fusion transcript characterizes clinical
Ewing sarcoma. Cell lines that express this genetic profile are confirmed to be
those of Ewing sarcoma. The A673 Ewing sarcoma line grows in culture and as a
xenograft in immunodeficient mice. The A673 model has been used to study Ewing
sarcoma angiogenesis and response to antiangiogenic agents. Many Ewing sarcoma
clinical specimens express the cell surface protein endosialin. Several Ewing
sarcoma cell lines, including the A673 line, also express cell surface
endosialin when grown as subcutaneous tumor nodules and as disseminated disease;
thus the A673 is a useful model for the study of endosialin biology and
endosialin-directed therapies. With the advent of tools that allow
characterization of clinical disease to facilitate optimal treatment, it becomes
imperative, especially for rare tumors, to develop preclinical models reflecting
disease subsets. Ewing PNET sarcomas are a rare disease where models are
available. BACKGROUND: Chromosomal translocations generating oncogenic transcription
factors are the hallmark of a variety of tumors, including many sarcomas. Ewing
sarcoma family of tumors (ESFTs) are characterized by the t(11;22)(q24;q12)
translocation that generates the Ewing sarcoma breakpoint region 1 and Friend
leukemia virus integration 1 (EWS-FLI1) fusion transcription factor responsible
for the highly maligt phenotype of this tumor. Although continued expression
of EWS-FLI1 is believed to be critical for ESFT cell survival, a clinically
effective small-molecule inhibitor remains elusive likely because EWS-FLI1 is a
transcription factor and therefore widely felt to be "undruggable."
METHODS: We developed a high-throughput screen to evaluate more than 50 000
compounds for inhibition of EWS-FLI1 activity in TC32 ESFT cells. We used a TC32
cell-based luciferase reporter screen using the EWS-FLI1 downstream target NR0B1
promoter and a gene signature secondary screen to sort and prioritize the
compounds. We characterized the lead compound, mithramycin, based on its ability
to inhibit EWS-FLI1 activity in vitro using microarray expression profiling,
quantitative reverse transcription-polymerase chain reaction, and immunoblot
analysis, and in vivo using immunohistochemistry. We studied the impact of this
inhibition on cell viability in vitro and on tumor growth in ESFT xenograft
models in vivo (n = 15-20 mice per group). All statistical tests were two-sided.
RESULTS: Mithramycin inhibited expression of EWS-FLI1 downstream targets at the
mRNA and protein levels and decreased the growth of ESFT cells at half maximal
inhibitory concentrations between 10 (95% confidence interval [CI] = 8 to 13 nM)
and 15 nM (95% CI = 13 to 19 nM). Mithramycin suppressed the growth of two
different ESFT xenograft tumors and prolonged the survival of ESFT
xenograft-bearing mice by causing a decrease in mean tumor volume. For example,
in the TC32 xenograft model, on day 15 of treatment, the mean tumor volume for
the mithramycin-treated mice was approximately 3% of the tumor volume observed
in the control mice (mithramycin vs control: 69 vs 2388 mm(3), difference = 2319
mm(3), 95% CI = 1766 to 2872 mm(3), P < .001).
CONCLUSION: Mithramycin inhibits EWS-FLI1 activity and demonstrates ESFT
antitumor activity both in vitro and in vivo. Approximately one-third of sarcomas contain specific translocations. Ewing
sarcoma is the prototypical member of this group of sarcomas; it was the first
to be recognized pathologically as a singular entity and to have its signature
translocation defined cytogenetically, which led to the identification of its
key driver alteration, the EWS-FLI1 gene fusion that encodes this aberrant,
chimeric transcription factor. We review recent progress in selected areas of
Ewing sarcoma research, including the application of genome-wide chromatin
immunoprecipitation analyses, to provide a comprehensive view of the EWS-FLI1
target gene repertoire, the identification of EWS-FLI1 target genes that may
also point to therapeutically targetable pathways, and data from model systems
as they relate to the elusive cell of origin of Ewing sarcoma and its possible
similarities to mesenchymal stem cells. BACKGROUND: Ewing sarcoma is extremely rare in people from East and Southeast
Asia.
METHODS: The records of 12 patients diagnosed with primary Ewing sarcoma and
treated at our institution from 1997 to 2009 were retrospectively reviewed.
RESULTS: There were seven male and five female patients and their mean age at
diagnosis was 22 years (range, 12-48 years). Two patients (16.7%) had distant
metastasis at diagnosis. The primary tumor sites were the trunk in seven
patients (58.3%) and the extremities in five patients (41.7%). Eleven patients
received neoadjuvant chemotherapy followed by wide excision surgery, and then
adjuvant chemotherapy. One patient received only chemotherapy without surgical
intervention due to poor cardiac and pulmonary function. At a mean follow-up of
33 months, the 2-year overall survival rate (OS) was 45.5%. Distant metastasis
was the only statistically significant prognostic factor of OS in our study. The
2-year OS rates of patients with lung metastasis and without lung metastasis
were 0% and 42.9%, respectively (p = 0.021). The t(11;22)(q24:q12) translocation
was present in all patients in our series.
CONCLUSION: We confirmed that distant metastases is highly predictive of a poor
outcome, and that the t(11;22)(q24:q12) translocation was present in all
patients in our series. The hallmark of Ewing's sarcoma (EWS) is a
translocation--t(11;22)(q24;q12)--that most frequently results in the EWS/FLI1
aberrant chimeric gene. Because EWS afflicts young patients, it stands out among
the diverse sarcoma subtypes. The frontline, standard-of-care cytotoxic
chemotherapy regimens produce minimal benefit in patients with metastases at
presentation or those with relapsed disease. While the outcomes of
chemorefractory EWS patients are generally poor, recent developments have led to
the promising use of targeted therapy. Specifically, inhibition of insulin-like
growth factor 1 receptor (IGF1R) signaling and the mammalian target of rapamycin
(mTOR) pathways has emerged as a targeted therapy in EWS, with select patients
experiencing dramatic therapeutic responses. However, targeted therapies in
general, and these responders in particular, are faced with the ultimate
conundrum of eventual resistance. To optimize response, combining IGF1R and mTOR
inhibitor-based regimens with chemotherapy in the upfront setting in newly
diagnosed high-risk EWS may clarify the true benefit of IGF1R inhibitors in
these patients. Another option is to explore novel targeted multikinase
inhibitors and poly(ADP-ribose) polymerase (PARP) inhibitors, which have
experienced a surge in supporting preclinical data. Drugs inhibiting the
downstream targets of EWS/FLI1 are also in preclinical development. However,
ultimately, the underlying biomarker correlates of resistance and response must
be delineated along with ways to overcome them. Novel agents, together with
integration of advances in multimodal approaches (including surgery and
radiation), as well as offering targeted therapies early in the disease course
represent new strategies for confronting the challenges of EWS. BACKGROUND: Ewing's sarcoma is a maligcy characterized by a specific 11:22
chromosomal translocation which generates a novel EWS-FLI1 fusion protein
functioning as an aberrant transcription factor. In the present study, we have
further characterized the junction region of the EWS-FLI1 fusion protein.
METHODS: In-silico model of EWS-FLI1 fusion protein was analysed for ligand
binding sites, and a putative region (amino acid (aa) 251-343 of the type 1
fusion protein) in the vicinity of the fusion junction was cloned and expressed
using bacterial expression. The recombit protein was characterized by
Circular Dichroism (CD). We then expressed aa 251-280 ectopically in Ewing's
sarcoma cell-line and its effect on cell proliferation, tumorigenicity and
expression of EWS-FLI1 target genes were analysed.
RESULTS: Our modelling analysis indicated that Junction region (aa 251-343)
encompasses potential ligand biding sites in the EWS-FLI1 protein and when
expressed in bacteria was present as soluble form. Ectopically expressing this
region in Ewing's sarcoma cells inhibited tumorigenicity, and EWS-FLI1 target
genes indicating a domit negative biological effect.
CONCLUSIONS: Junction region can be exploited further as target for drug
development in future to specifically target EWS-FLI1 in Ewing's Sarcoma. Tumours defined as Ewing sarcoma (ES) constitute a group of highly maligt
neoplasms that most often affect children and young adults in the first 2
decades of life. The EWS/Fli-1 fusion gene, a product of the translocation
t(11;22) (q24; 12), is detected in 95% of ES patients. Recently, it was
validated that cells emit a heterogeneous mixture of vesicular, organelle-like
structures (microvesicles, MVs) into their surroundings including blood and body
fluids, and that these MVs contain a selected set of tumor-related proteins and
high levels of mRNAs and miRNAs. In this present study, we detected the Ewing
sarcoma-specific EWS/Fli-1 mRNA in MVs from the culture medium of ES cell lines
carrying t(11;22) (q24; 12). Also, we detected this fusion gene in approximately
40% of the blood samples from mice inoculated with xenografts of TC135 or A673
cells. These findings indicate the EWS/Fli-1 mRNA in MVs might be a new
non-invasive diagnostic marker for specific cases of Ewing sarcoma. Translocations involving ETS-transcription factors, most commonly leading to the
EWSR1-FLI1 fusion protein, are the hallmark of Ewing sarcoma. Despite knowledge
of this driving molecular event, an effective therapeutic strategy is lacking.
To test potential treatment regimes, we established a novel Ewing sarcoma
zebrafish engraftment model allowing time-effective, dynamic quantification of
Ewing sarcoma progression and tumour burden in vivo, applicable for screening of
single and combined compounds. In Ewing sarcoma the tumour-suppressor gene TP53
is commonly found to be wild-type, thus providing an attractive target for
treatment. Here, we study TP53 wild-type (EW7, CADO-ES1 and TC32) and
TP53-deleted (SK-N-MC) Ewing sarcoma cell lines to investigate the potentiating
effect of p53 reactivation by Nutlin-3 on treatment with YK-4-279 to block
transcriptional activity of EWSR1-FLI1 protein. Blocking EWSR1-FLI1
transcriptional activity reduced Ewing sarcoma tumour cell burden irrespective
of TP53 status. We show that simultaneous YK-4-279 treatment with Nutlin-3 to
stabilize p53 resulted in an additive inhibition of TP53 wild-type Ewing sarcoma
cell burden, whilst not affecting TP53-deleted Ewing sarcoma cells. Improved
inhibition of proliferation and migration by combinatorial treatment was
confirmed in vivo by zebrafish engraftments. Mechanistically, both compounds
together additively induced apoptosis of tumour cells in vivo by engaging
distinct pathways. We propose reactivation of the p53 pathway in combination
with complementary targeted therapy by EWSR1-FLI1 transcriptional activity
disruption as a valuable strategy against p53 wild-type Ewing sarcoma. |
Is invasion and metastasis one of the hallmarks of cancer? | Yes, invasion and metastasis are one of the so-called hallmarks of cancer. | Maligt mesothelioma (MM) is a maligt tumor derived from mesothelial cells,
native cells of the body cavities. Exposure to asbestos is the most strongly
established etiologic factor, predomitly for the most common disease form,
pleural mesothelioma. The pathogenesis of MM involves the accumulation of
extensive cytogenetic changes, as well as cancer-related phenotypic alterations
that facilitate tumor cell survival, invasion and metastasis. This review
presents current knowledge regarding the biological characteristics of this
disease that are linked to the so-called hallmarks of cancer. In addition, data
suggesting that the anatomic site (solid tumor vs. effusion) affects the
expression of metastasis-associated and regulatory molecules in MM are
presented. Finally, recent work in which high-throughput methodology has been
applied to MM research is reviewed. The data obtained in the reviewed research
may aid in defining new prognostic markers and therapeutic targets for this
aggressive disease in the future. |
Is it possible to detect survivin protein expression in normal human adult tissues? | No. Survivin is an inhibitor of apoptosis that is undetectable in normal differentiated tissues of adult human. | Recently, a novel antiapoptosis gene, i.e., survivin, was identified as a
structurally unique member of the inhibitor of apoptosis protein family.
Survivin expression is turned off during fetal development and not found in
non-neoplastic adult human tissues but is again turned on in the most common
human cancers. The antiapoptotic properties of survivin might provide a
significant growth advantage in tumors and possibly also contribute to
chemoresistance of cancer. Therefore, we analyzed the expression of survivin in
human renal cell carcinomas (RCCs), known to be largely resistant to
chemotherapy. Northern blot analysis and RT-PCR revealed survivin expression in
newly established RCC cell lines (n = 11) of all major histological types.
Moreover, we identified two novel splice variants of survivin, lacking exon 3
(survivin-deltaEx3) or retaining a part of intron 2 as a cryptic exon
(survivin-2B). Both sequence alterations cause marked changes in the structure
of the corresponding proteins, including structural modifications of the
baculovirus inhibitor of apoptosis protein repeat domain. The role of the novel
isoforms in the regulation of apoptosis was assessed in transfection
experiments, showing conservation of antiapoptotic properties for
survivin-deltaEx3 and a markedly reduced antiapoptotic potential for
survivin-2B. In conclusion, our observations suggest a complex regulatory
balance between the different isoforms of survivin, which might determine the
response to proapoptotic stimuli, not only in human RCCs but also in fetal
tissues and other types of cancer. Survivin is a member of the inhibitor of apoptosis (IAP) family, and is also
involved in the regulation of cell division. Survivin is widely expressed in
foetal tissues and in human cancers, but generally not in normal adult tissue.
This study examined the expression of surviving protein in a series of 293 cases
of invasive primary breast carcinoma. Survivin immunoreactivity was assessed
using two different polyclonal antibodies, and evaluated semiquantitatively
according to the percentage of cells demonstrating distinct nuclear and/or
diffuse cytoplasmic staining. Overall, 60% of tumours were positive for
survivin: 31% demonstrated nuclear staining only, 13% cytoplasmic only, and 16%
of tumour cells demonstrated both nuclear and cytoplasmic staining. Statistical
analysis revealed that survivin expression was independent of patient's age,
tumour size, histological grade, nodal status, and oestrogen receptor status. In
multivariate analysis, nuclear survivin expression was a significant independent
prognostic indicator of favourable outcome both in relapse-free and overall
survival (P<0.001 and P=0.01, respectively). In conclusion, our results show
that survivin is frequently overexpressed in primary breast cancer. Nuclear
expression is most common and is an independent prognostic indicator of good
prognosis. We previously reported that prostate derived Ets transcription factor (PDEF) is
a breast tumor-associated molecule. To obtain further insights into PDEF
expression in other human tumor types, a cDNA library database from human adult
normal and tumor tissues was compiled and searched for PDEF distribution. The
results showed that PDEF is present at relative higher frequencies in the cDNA
libraries from brain, breast, lung and ovarian tumors in comparison to those
from the corresponding normal tissues. RT/PCR analysis of PDEF expression in
ovarian tumors confirmed that PDEF is expressed in 36 out of 51 (71%) ovarian
tumors. Further comparison of the distribution of PDEF with other widely
recognized cancer-associated molecules showed that PDEF has more restricted
distributions than Her-2/neu, Bcl-2, survivin or telomerase in cDNA libraries
from normal human tissues and more increased distribution than Her-2/neu,
CA-125, Bcl-2, survivin and telomerase in cDNA libraries from brain (except
survivin), breast, lung and ovarian tumors. These data together show a better
tumor-association for PDEF and suggest that PDEF is a more suitable target for
developing specific cancer therapies. OBJECTIVE: To investigate the practicability of survivin detection in urine as a
novel diagnostic method and prognostic molecular marker of bladder cancer.
METHODS: Nested RT-PCR was used to detect survivin mRNA expression in urine
specimens from 20 healthy persons and patients with bladder carcinomas (n=30),
prostate cancer (n=10), and renal cancer (n=6).
RESULTS: The result show that survivin was not detected in the urine samples of
six of 30 patients with bladder cancer, whereas all the results were negative
the other 36 persons. The positive rates of survivin and their expression levels
increased with the tumors' histological grade. Six of 21 new-onset bladder
tumors did not present survivin mRNA expression; however, none of the nine
recurrent bladder tumors were negative, and patients with new-onset bladder
tumors (0.5973+/-0.1968) had significantly lower survivin levels than those with
recurrent ones (1.1627+/-0.1341)( P=2.10228E-05). We also found that survivin
expression was not correlated with gender, age, and clinical stage.
CONCLUSION: The high sensitivity and specificity of urine survivin can indicate
the occurrence of bladder carcinomas, and its expression level might be
correlated with the maligcy and prognosis of bladder carcinomas. In addition,
the fact that survivin was only detected in urine samples of patients with
bladder cancer, rather than in normal adult tissue (except thymus gland),
suggests that survivin can be used as an ideal target in bladder carcinoma
treatment. Survivin is a member of the inhibitor apoptosis family that is overexpressed in
many maligcies. It has five known alternative splice forms, some of which
differ in their antiapoptotic properties and expression levels in human cancers.
Here we describe a novel donor splice site (DSS), 2B+32 DSS, which is used in
conjunction with survivin alternative exon 2B, resulting in the inclusion of 32
additional nucleotides from intron 2 at the 3' end of this exon. Sequence
analysis showed that both the classical exon 2B DSS and 2B+32 are provided by an
Alu sequence, which is inserted in intron 2 downstream of a functional acceptor
splice site, leading to the exonization of part of the repetitive element. Minor
transcripts including the 2B+32 alternative exon, or retaining the whole
intronic region comprised between exons 2B and 3, were detected in several human
cell lines and in some human tissues. Survivin 2B+32 containing variants acquire
a premature stop codon (PTC) and may therefore be degraded by the nonsense
mediated decay pathway. The implication of these novel isoforms, as well as
other PTC+ survivin variants, in the overall regulation of survivin expression
is discussed. Sequence analysis of intron 2 which contains the Alu Y element was
performed on different primate species in order to trace its insertion and
exonization during primate evolution. Fragile histidine triad (FHIT) gene, a candidate tumor suppressor gene located
at 3p14.2, has been shown to be involved in carcinogenesis of many human
tissues, including digestive tract tissues. However, the expression and role of
FHIT in the initiation and the development of the colorectal cancer (CRC) are
poorly understood. In our present study, we have demonstrated that the FHIT gene
exhibits significantly decreased expression in human CRC compared to colorectal
adenoma and normal colorectal tissue by tissue microarray (TMA). The positive of
FHIT gene expression in normal colorectal tissue, adenoma and adenocarcinoma
were 93.75%, 68.75% and 46.25%, respectively. We showed that decreased FHIT
expression was significantly correlated with the progression of colorectal
carcinoma (P<0.05) as well as differentiation and lymph node metastasis
(P<0.05). Two somatic mutations in the FHIT gene were also detected in human
CRC. The presence of these mutations correlated significantly with decreased
FHIT expression in the human CRC. In addition, we identified decreased FHIT
expression resulting in apoptosis inhibition and decreasing apoptosis associated
with abnormal levels of some pro- and anti-apoptotic proteins (Bax, Bcl-2 and
Survivin) by TUNEL and TMA. Our results demonstrated that the mutation in the
FHIT gene significantly reduced FHIT expression in human CRC. Both TUNEL and TMA
experiments demonstrated significantly inhibited apoptosis by down-regulation of
Bax and up-regulation of Survivin and Bcl-2. Collectively, these studies
identify the mechanism by which an important tumor suppressor gene, FHIT,
inactivated specifically in human CRC, and contributes to our understanding of
the mechanism of colorectal carcinogenesis. BACKGROUND: Gene expression profiling has revolutionized our ability to
molecularly classify primary human tumors and significantly enhanced the
development of novel tumor markers and therapies; however, progress in the
diagnosis and treatment of melanoma over the past 3 decades has been limited,
and there is currently no approved therapy that significantly extends lifespan
in patients with advanced disease. Profiling studies of melanoma to date have
been inconsistent due to the heterogeneous nature of this maligcy and the
limited availability of informative tissue specimens from early stages of
disease.
METHODOLOGY/PRINCIPLE FINDINGS: In order to gain an improved understanding of
the molecular basis of melanoma progression, we have compared gene expression
profiles from a series of melanoma cell lines representing discrete stages of
maligt progression that recapitulate critical characteristics of the primary
lesions from which they were derived. Here we describe the unsupervised
hierarchical clustering of profiling data from melanoma cell lines and
melanocytes. This clustering identifies two distinctive molecular subclasses of
melanoma segregating aggressive metastatic tumor cell lines from less-aggressive
primary tumor cell lines. Further analysis of expression signatures associated
with melanoma progression using functional annotations categorized these
transcripts into three classes of genes: 1) Upregulation of activators of cell
cycle progression, DNA replication and repair (CDCA2, NCAPH, NCAPG, NCAPG2, PBK,
NUSAP1, BIRC5, ESCO2, HELLS, MELK, GINS1, GINS4, RAD54L, TYMS, and DHFR), 2)
Loss of genes associated with cellular adhesion and melanocyte differentiation
(CDH3, CDH1, c-KIT, PAX3, CITED1/MSG-1, TYR, MELANA, MC1R, and OCA2), 3)
Upregulation of genes associated with resistance to apoptosis (BIRC5/survivin).
While these broad classes of transcripts have previously been implicated in the
progression of melanoma and other maligcies, the specific genes identified
within each class of transcripts are novel. In addition, the transcription
factor NF-KB was specifically identified as being a potential "master regulator"
of melanoma invasion since NF-KB binding sites were identified as consistent
consensus sequences within promoters of progression-associated genes.
CONCLUSIONS/SIGNIFICANCE: We conclude that tumor cell lines are a valuable
resource for the early identification of gene signatures associated with
maligt progression in tumors with significant heterogeneity like melanoma. We
further conclude that the development of novel data reduction algorithms for
analysis of microarray studies is critical to allow for optimized mining of
important, clinically-relevant datasets. It is expected that subsequent
validation studies in primary human tissues using such an approach will lead to
more rapid translation of such studies to the identification of novel tumor
biomarkers and therapeutic targets. Survivin is an inhibitor of apoptosis protein and regulates the cell cycle in
the G2/M phase. Survivin is expressed during embryonic and fetal development,
selectively over-expressed in common human cancers and completely down-regulated
in normal adult tissue. This work was aimed at studying the expression of the
survivin homologues and their subcellular distribution in fetal and normal adult
tissues of rat. Survivin expression was evaluated by immunohistochemistry in
formalin-fixed, paraffin-embedded tissue sections of fetal and normal adult
tissues of rat using the polyclonal serum SUR12A-CFI. This serum demonstrated
intense positive survivin staining in adult kidney, ovary and oviduct, and a
variable expression in different fetal organs, with particularly intense
expression detected in the adrenal gland, liver, stomach, small intestine,
colon, kidney and skin. In both fetal and adult tissues, the expression was
predomitly cytoplasmic. It was concluded that survivin was abundantly and
prominently expressed during fetal development in rat and that the polyclonal
anti-human survivin antibody SUR12A-CFI is reactive with rat survivin. Inhibition of apoptosis is a critical step in tumorigenesis in many cancers,
including Merkel cell carcinoma; however, the exact regulatory mechanisms are
not fully understood. Survivin is an inhibitor of apoptosis that is undetectable
in most terminally differentiated normal human tissues, strongly expressed in
embryonic and fetal organs and is strongly expressed in many different human
cancers. In this study, we investigated the expression of survivin in cutaneous
Merkel cell carcinoma using immunohistochemistry and correlated the findings
with long-term clinical follow-up. We collected and immunostained 19 cases of
Merkel cell carcinoma with antibodies to survivin. The median patient age was 79
years, with an average follow-up of 17 months, and a male/female ratio of 7:11.
All but one sample represented primary lesions and two cases were obtained from
one patient. Clinical follow-up was obtained in 15 cases (79%). All 19 cases of
Merkel cell carcinoma demonstrated strong immunoreactivity for survivin.
Survivin protein was localized and classified into predominately nuclear (N=8)
or cytoplasmic (N=4) compartments. A mixed pattern of survivin expression was
also seen in three cases. Cases with a nuclear staining pattern were
distinguished by an aggressive clinical course, with seven of eight patients
developing metastases or dead of disease on follow-up. Furthermore, all of the
cases with predominately cytoplasmic survivin localization (N=4) were free of
disease on follow-up. Merkel cell carcinomas represent aggressive maligcies
regulated by apoptotic pathways. We demonstrate that survivin, a protein with a
dual role in inhibition of apoptosis and regulation of cellular proliferation is
expressed in Merkel cell carcinoma. Moreover, nuclear subcellular localization
of survivin in Merkel cell carcinomas may portend a poor prognosis and
identification of these cases may assist clinical management. Hepatocellular carcinoma (HCC) is known to be resistant to chemotherapy.
Survivin, a member of the inhibitor of apoptosis proteins, is overexpressed in
most cancers but is absent in most normal adult tissue. The aim of this study
was to investigate whether expression of survivin contributes to resistance to
cisplatin-induced apoptosis. We confirmed induction of survivin expression in
hepatoma in the N-diethylnitrosamine (DEN) induced rat and in the rat hepatoma
cell line (K-251). We examined cell proliferation after treatment with cisplatin
(CDDP) in the presence and absence of siRNA or the phosphatidylinositol 3-kinase
(PI3K) inhibitor LY294002 to suppress survivin or PI3K/Akt, respectively.
Survivin was expressed in DEN-induced rat HCC with RT-PCR and Western blotting.
Expression of survivin was observed primary in the nuclei and in the cytoplasm
with immunohistochemistry. However, survivin was not detected in non-tumor
tissues. Expression of survivin was also observed primarily in the nuclei and in
the cytoplasm of the K-251 rat hepatoma cell line. CDDP induced survivin
expression, which was blocked by siRNA. LY294002 also attenuated survivin
expression induced by CDDP. Our results indicate that survivin expression via
PI3K contributes to resistance to CDDP-induced apoptosis in a rat hepatoma cell
line. A cardinal feature of maligt melanoma is its metastatic propensity. An
incomplete view of the genetic events driving metastatic progression has been a
major barrier to rational development of effective therapeutics and prognostic
diagnostics for melanoma patients. In this study, we conducted global genomic
characterization of primary and metastatic melanomas to examine the genomic
landscape associated with metastatic progression. In addition to uncovering
three genomic subclasses of metastastic melanomas, we delineated 39 focal and
recurrent regions of amplification and deletions, many of which encompassed
resident genes that have not been implicated in cancer or metastasis. To
identify progression-associated metastasis gene candidates, we applied a
statistical approach, Integrative Genome Comparison (IGC), to define 32 genomic
regions of interest that were significantly altered in metastatic relative to
primary melanomas, encompassing 30 resident genes with statistically significant
expression deregulation. Functional assays on a subset of these candidates,
including MET, ASPM, AKAP9, IMP3, PRKCA, RPA3, and SCAP2, validated their
pro-invasion activities in human melanoma cells. Validity of the IGC approach
was further reinforced by tissue microarray analysis of Survivin showing
significant increased protein expression in thick versus thin primary cutaneous
melanomas, and a progression correlation with lymph node metastases. Together,
these functional validation results and correlative analysis of human tissues
support the thesis that integrated genomic and pathological analyses of staged
melanomas provide a productive entry point for discovery of melanoma metastases
genes. We studied the effects of AZD1152, an Aurora B kinase inhibitor, on Burkitt's
lymphoma (BL) and Hodgkin's lymphoma (HL) in human tissues and cell cultures and
in a murine xenograft model of lymphoma. Aurora kinase A and B levels were
assessed by RT-PCR and immunohistochemistry. They were aberrantly expressed in
BL and HL cell lines, and in lymph nodes from patients with BL and HL. Next,
activation of the Aurora B promoter was detected by reporter gene assays. The
promoter activity of Aurora B kinase was high in BL cell lines and the Aurora B
promoter contained a positive regulatory region between -74 and -104 from the
transcription initiation site. AZD1152-hQPA had antiproliferative effects in the
BL and HL cell lines studied; inhibited the phosphorylation of histone H3 and
retinoblastoma proteins, and resulted in cells with > 4N DNA content.
AZD1152-hQPA induced caspase-dependent apoptosis of some cell lines,
demonstrated by loss of mitochondrial membrane potential, activation of
caspase-9, followed by activation of caspase-3. This effect was accompanied by
the inhibition of survivin expression. In vivo efficacy was determined in
NOD/SCID/γc(null) mice implanted with the Ramos human BL cell line. AZD1152 had
anti-tumour effects in this murine xenograft model. There preclinical data
suggest that the inhibition of Aurora B kinase is a potentially useful
therapeutic strategy in BL and HL. Polycomb group proteins are essential regulators of stem cell function during
embryonic development and in adult tissue homeostasis. Bmi1, a key component of
the Polycomb Repressive Complex 1, is highly expressed in undifferentiated
neural stem cells (NSC) as well as in several human cancers including high-grade
gliomas--highly aggressive brain tumors. Using a conditional gene activation
approach in mice, we show that overexpression of Bmi1 induces repressive
epigenetic regulation of the promoter of Survivin, a well-characterized
antiapoptotic protein. This phenomenon is cell type-specific and it leads to
apoptotic death of progenitor cells exclusively upon commitment toward a
neuronal fate. Moreover, we show that this is triggered by increased oxidative
stress-induced DNA damage. In contrast, undifferentiated NSC as well as
glioma-initiating cells display an open chromatin configuration at the Survivin
promoter and do not undergo apoptotic death. These findings raise the
possibility that normal and neoplastic stem cells depend on the same mechanism
for surviving the hyperproliferative state induced by increased Bmi1 expression. |
List symptoms of Meigs' Syndrome. | Meigs' syndrome is a benign ovarian tumor associated with ascites and pleural effusion. | BACKGROUND: The Meigs' syndrome is a rare but well-known syndrome defined as the
triad of benign solid ovarian tumor, ascites, and pleural effusion. Meigs'
syndrome always requires surgical treatment. However, the optimal approach for
its management has not been sufficiently investigated.
CASE PRESENTATION: We report a patient with a large twisted ovarian fibroma
associated with Meigs' syndrome, abdominal pain and severe hemolytic anemia that
was treated by laparoscopic surgery. This case highlights the difficulties that
may be encountered in the management of patients with Meigs' syndrome, including
potential misdiagnosis of the tumor as a maligt ovarian neoplasm that may
influence the medical and surgical approach and the adverse impact that Meigs'
syndrome can have on the patient's condition, especially if it is associated
with acute pain and severe anemia. Considering the patient's serious clinical
condition and assuming that she had Meigs' syndrome with a twisted large ovarian
mass and possible hemolytic anemia, we first concentrated on effective medical
management of our patient and chose the most appropriate surgical treatment
after laparoscopic examination. The main aim of our initial approach was
preoperative management of the anemia. Blood transfusions and glucocorticoid
therapy resulted in stabilization of the hemoglobin level and normalization of
the bilirubin levels, which confirmed the appropriateness of this approach.
Laparoscopic surgery 4 days after admission enabled definitive diagnosis of the
tumor, confirmed torsion and removed the bulky ovarian fibroma, resulting in
timely resolution of symptoms, short hospitalization, relatively low morbidity
and a rapid return to her social and professional life.
CONCLUSIONS: This case highlights the difficulties that may be encountered in
the management of patients with Meigs' syndrome, including potential
misdiagnosis of the tumor as a maligt ovarian neoplasm that may influence the
medical and surgical approach, and the adverse impact that Meigs' syndrome can
have on the patient's condition, especially if it is associated with acute pain
and severe anemia. The present case suggests that laparoscopic surgery for
potentially large maligt tumors is feasible and safe, but requires an
appropriate medical and gynecological oncology expertise. BACKGROUND: The Demons-Meigs syndrome should usually be evoked in case of
presence of a typical triad: abdominopelvic mass, ascites and hydrothorax. Its
diagnosis appears crucial to prevent the realization of unnecessary surgical
procedures.
CASE PRESENTATION: A 32-year-old woman presented in April 2012 to the emergency
department of our maternity unit (General Hospital, Thiers, France) with an
abdominal distension mimicking the symptoms of a pregcy at term. Physical
examination revealed a voluminous painful abdominopelvic mass, extended from the
pelvis to the upper abdomen with a large right pleural effusion. Ultrasound and
computed tomography showed it was a tumor measuring more than 300 mm in diameter
with a right hydrothorax. Serum CA-125 level was 289 U/ml. Cytologic analysis of
the pleural effusion didn't show any maligt cells. In this study,
Demons-Meigs syndrome was recognized. A laparoscopico-laparotomic management
permitted an aspiration of 23 liters of a brownish liquid and an unilateral
adnexectomy after pleural paracentesis was performed. Frozen section
demonstrated benign mucinous cystadenoma. The final histologic findings
objectified intracystic intestinal type ovarian mucinous borderline tumor. After
multidisciplinary consultation, the patient was re-operated one month later. The
exploration didn't reveal any suspected lesions and appendectomy and omentectomy
were performed. The postoperative course was uneventful. Serum CA-125 level was
normal at the time of the reoperation and 24 months after the initial surgery.
CONCLUSION: The preoperative recognition of a Demons-Meigs syndrome or a Demons'
pseudosyndrome is essential to avoid useless surgical procedures. |
What is the effect of CRD-BP on the stability of c-myc mRNA? | The c-myc mRNA coding region determinant-binding protein (CRD-BP) has high affinity for the coding region determinant (CRD) of c-myc mRNA. Such affinity is believed to protect c-myc CRD from endonucleolytic attack. | We previously isolated and characterized a coding region determit-binding
protein (CRD-BP) that might regulate c-myc mRNA post-transcriptionally. CRD-BP
binds specifically to the coding region of c-myc mRNA and might stabilize c-myc
mRNA in vitro by protecting it from endonucleolytic cleavage. Since c-myc
abundance is regulated during embryonic development and cell replication, we
investigated whether CRD-BP is also regulated in animal tissues. We focused on
CRD-BP expression during rat liver development and liver regeneration, because
c-myc mRNA is regulated post-transcriptionally in both cases. CRD-BP expression
parallels c-myc expression during liver development; the protein is present in
fetal and neonatal liver but is absent or in low abundance in adult liver. In
contrast, the up-regulation of c-myc mRNA following partial hepatectomy is not
accompanied by up-regulation of CRD-BP. To our knowledge, CRD-BP is the first
example of a putative mammalian mRNA-binding protein that is abundant in a fetal
tissue but either absent from or scarce in adult tissues. Its expression in
fetal liver and in transformed cell lines suggests CRD-BP is an oncofetal
protein. Antisense oligodeoxynucleotides (ODNs) are designed to bind to and inhibit a
target mRNA. We used a novel approach for the design of ODNs to the c-myc mRNA
using protein binding sites as targets for ODN action. Our strategy was to
identify ODNs that could interfere with the coding region determit-binding
protein (CRD-BP), a protein that binds to the CRD region of the c-myc mRNA.
Using an in vitro gel shift assay, we show that ODN molecules can occlude the
CRD-BP from the mRNA. The best ODN, CRD-ODN4, was able to inhibit RNA binding of
the CRD-BP by 75%. This effect was sequence-specific and concentration
dependent. K562 cells treated with a 2'-O-methyl derivative of CRD-ODN4 showed a
concentration-dependent decrease in both c-myc mRNA and protein levels, with a
maximal 65% inhibition of protein expression at 200 nM CRD-ODN4. In contrast, a
2'-O-methyl ODN derivative targeting the translation initiation codon
(antimyc-aug) reduced c-myc protein but actually increased mRNA levels, an
effect resulting at least partly from stabilization of the c-myc mRNA. CRD-ODN4
treatment did not alter the c-myc mRNA half-life. CRD-ODN4 was more effective in
inhibiting K562 cell growth than antimyc-aug, reducing cell number by
approximately 70% after 48 h of exposure to 750 nM. The correlation between ODN
effects on RNA-protein interactions in vitro and those observed in cells
supports the hypothesis that CRD-ODN4 inhibits the interaction between the
CRD-BP and the c-myc mRNA and that disrupting this RNA-protein interaction
reduces c-myc expression in cells. Mouse coding region determit-binding (mCRD-BP) and human IGF-II mRNA-binding
1 (hIMP-1) proteins are orthologous mRNA-binding proteins that recognize c-myc
and IGF-II mRNA, respectively, and regulate their expression
posttranscriptionally. Here, we confirm that human CRD-BP/IMP-1 binds to c-myc
mRNA and that it is predomitly expressed in fetal tissues. Moreover,
hCRD-BP/IMP-1 expression was detected in cell lines of neoplastic origin and in
selected primary tumors. In a series of 33 maligt and 10 benign mesenchymal
tumors, 73% and 40%, respectively, were found to express hCRD-BP/IMP-1. In
particular, expression was significant in 14 Ewing's sarcomas, all of which were
positive. The data suggest that hCRD-BP/IMP-1 plays a role in abnormal cell
proliferation in mesenchymal tumors. The Coding Region Determit-Binding Protein (CRD-BP) is an RRM and
KH-domain-containing protein that recognizes specifically at least three RNAs.
It binds to one of the two c-myc mRNA instability elements, to the 5'Un
Translated Region (UTR) of the leader 3 IGF-II mRNA and to the oncofetal H19
RNA. CRD-BP has been assigned a role in stabilizing c-myc mRNA by preventing its
endonucleolytic cleavage and in repressing the translation of the leader 3
IGF-II mRNA, the major embryonic species of this message. CRD-BP is normally
expressed only in fetal tissues. However, its expression is detected in primary
tumors and transformed cell lines of different origins. The vast majority of
colon (80%) and breast (60%) tumors and sarcomas (73%) express CRD-BP whereas in
other tumor types, for example prostate carcinomas, its expression is rare.
CRD-BP expression has also been detected in benign tumors such as breast
fibroadenomas, meningiomas and other benign mesenchymal tumors, implying a role
for this gene in abnormal cell proliferation. In breast carcinomas, CRD-BP
expression and or gene copy number gains in the region encompassing the c-myc
locus were detected in approximately 75% of tumors, implying that the
deregulated expression of c-myc may be more widespread than previously believed.
Infiltrated lymph nodes, corresponding to CRD-BP-positive primary tumors, were
also found positive indicating that monitoring for CRD-BP could prove useful for
the detection and monitoring of disseminated disease. Although constitutive activation of beta-catenin/Tcf signalling is implicated in
the development of human cancers, the mechanisms by which the beta-catenin/Tcf
pathway promotes tumorigenesis are incompletely understood. Messenger RNA
turnover has a major function in regulating gene expression and is responsive to
developmental and environmental signals. mRNA decay rates are dictated by
cis-acting elements within the mRNA and by trans-acting factors, such as
RNA-binding proteins (reviewed in refs 2, 3). Here we show that beta-catenin
stabilizes the mRNA encoding the F-box protein betaTrCP1, and identify the
RNA-binding protein CRD-BP (coding region determit-binding protein) as a
previously unknown target of beta-catenin/Tcf transcription factor. CRD-BP binds
to the coding region of betaTrCP1 mRNA. Overexpression of CRD-BP stabilizes
betaTrCP1 mRNA and elevates betaTrCP1 levels (both in cells and in vivo),
resulting in the activation of the Skp1-Cullin1-F-box protein (SCF)(betaTrCP) E3
ubiquitin ligase and in accelerated turnover of its substrates including IkappaB
and beta-catenin. CRD-BP is essential for the induction of both betaTrCP1 and
c-Myc by beta-catenin signalling in colorectal cancer cells. High levels of
CRD-BP that are found in primary human colorectal tumours exhibiting active
beta-catenin/Tcf signalling implicates CRD-BP induction in the upregulation of
betaTrCP1, in the activation of dimeric transcription factor NF-kappaB and in
the suppression of apoptosis in these cancers. |
What is the molecular function of psoralen photobinding on DNA? | The interaction of two water-soluble furocoumarins, 8-(omega-diethyl aminopropyloxy)psoralen hydrochloride (I) and its 5-isomer (II), with DNA has been investigated by spectroscopic, equilibrium dialysis, hydrodynamic and chiroptical techniques. Both compounds intercalate into the polynucleotide double helix. | The effects of different DNA sequences on the photoreaction of various
furocoumarin derivatives was investigated from a quantitative point of view
using a number of self-complementary oligonucleotides. These contained 5'-TA and
5'-AT residues, having various flanking sequences. The furocoumarins included
classical bifunctional derivatives, such as 8-methoxy- and 5-methoxypsoralen, as
well as monofunctional compounds, such as angelicin and benzopsoralen. Taking
into an account the thermodynamic constant for noncovalent binding of each
psoralen to each DNA sequence, the rate constants for the photobinding process
to each fragment were evaluated. The extent of photoreaction is greatly affected
by the DNA sequence examined. While sequences of the type 5'-(GTAC)n are quite
reactive towards all furocoumarins, 5'-TATA exhibited a reduced rate of
photobinding using monofunctional psoralens. In addition terminal 5'-TA groups
were the least reactive with 5- and 8-methoxypsoralen, but not with angelicin or
benzopsoralen. Also 5'-AT-containing fragments exhibited remarkably variable
responses toward monofunctional or bifunctional psoralen derivatives. As a
general trend the photoreactivity rate of the former is less sequence-sensitive,
the ratio between maximum and minimum being less than 2 for the examined
fragments. The same ratio is about 3.4 for 8-methoxypsoralen and 6.2 for
5-methoxypsoralen. This approach, in combination with footprinting studies,
appears to be quite useful for a quantitative investigation of the process of
covalent binding of psoralens to specific sites in DNA. The interaction of two water-soluble furocoumarins, 8-(omega-diethyl
aminopropyloxy)psoralen hydrochloride (I) and its 5-isomer (II), with DNA has
been investigated by spectroscopic, equilibrium dialysis, hydrodynamic and
chiroptical techniques. Both compounds intercalate into the polynucleotide
double helix. From the dependence of the binding on ionic strength, ion release
and binding free energy corrected for counterion release have been
quantitatively estimated. It is shown that the differences in DNA-affinity
observed for compounds I and II arise primarily from non electrostatic
contributions. The binding process is exothermic, with slightly different van't
Hoff enthalpies for the examined furocoumarins. Helix lengthening and dichroic
effects indicate different intercalation geometries for the isomeric compounds.
These studies allow a possible explanation for the finding that isomer I
exhibits largely better DNA-photobinding properties, while isomer II is by far
more effective as an antiviral agent. Transcription has the capacity to mechanically modify DNA topology, DNA
structure and nucleosome arrangement. Resulting from ongoing transcription,
these modifications in turn may provide instant feedback to the transcription
machinery. To substantiate the connection between transcription and DNA
dynamics, we charted an ENCODE map of transcription-dependent dynamic
supercoiling in human Burkitt's lymphoma cells by using psoralen photobinding to
probe DNA topology in vivo. Dynamic supercoils spread ~1.5 kilobases upstream of
the start sites of active genes. Low- and high-output promoters handled this
torsional stress differently, as shown by using inhibitors of transcription and
topoisomerases and by chromatin immunoprecipation of RNA polymerase and
topoisomerases I and II. Whereas lower outputs are managed adequately by
topoisomerase I, high-output promoters additionally require topoisomerase II.
The genome-wide coupling between transcription and DNA topology emphasizes the
importance of dynamic supercoiling for gene regulation. |
Is progesterone effective for treatment of patients with traumatic brain injury based on clinical trial data? | No. Progesterone has been associated with robust positive effects in animal models of traumatic brain injury (TBI) and with clinical benefits in two phase 2 randomized, controlled trials. However, a recent large clinical trial showed no clinical benefit of progesterone in patients with severe TBI. These data stand in contrast to the robust preclinical data and results of early single-center trials that provided the impetus to initiate phase 3 trials. | PURPOSE OF REVIEW: Translating the efficacy of neuroprotective agents in
experimental traumatic brain injury to clinical benefit has proven an extremely
complex and, to date, unsuccessful undertaking. The focus of this review is on
neuroprotective agents that have recently been evaluated in clinical trials and
are currently under clinical evaluation, as well as on those that appear
promising and are likely to undergo clinical evaluation in the near future.
RECENT FINDINGS: Excitatory neurotransmitter blockage and magnesium have
recently been evaluated in phase III clinical trials, but showed no
neuroprotective efficacy. Cyclosporin A, erythropoietin, progesterone and
bradykinin antagonists are currently under clinical investigation, and appear
promising.
SUMMARY: Traumatic brain injury is a complex disease, and development of
clinically effective neuroprotective agents is a difficult task. Experimental
traumatic brain injury has provided numerous promising compounds, but to date
these have not been translated into successful clinical trials. Continued
research efforts are required to identify and test new neuroprotective agents,
to develop a better understanding of the sequential activity of pathophysiologic
mechanisms, and to improve the design and analysis of clinical trials, thereby
optimizing chances for showing benefit in future clinical trials. In this article, we review published preclinical and epidemiologic studies that
examine progesterone's role in the central nervous system. Its effects on the
reproductive and endocrine systems are well known, but a large and growing body
of evidence, including a recently published pilot clinical trial, indicates that
the hormone also exerts neuroprotective effects on the central nervous system.
We now know that it is produced in the brain, for the brain, by neurons and
glial cells in the central and peripheral nervous system of both male and female
individuals. Laboratories around the world have reported that administering
relatively large doses of progesterone during the first few hours to days after
injury significantly limits central nervous system damage, reduces loss of
neural tissue, and improves functional recovery. Although the research published
to date has focused primarily on progesterone's effects on blunt traumatic brain
injury, there is evidence that the hormone affords protection from several forms
of acute central nervous system injury, including penetrating brain trauma,
stroke, anoxic brain injury, and spinal cord injury. Progesterone appears to
exert its protective effects by protecting or rebuilding the blood-brain
barrier, decreasing development of cerebral edema, down-regulating the
inflammatory cascade, and limiting cellular necrosis and apoptosis. All are
plausible mechanisms of neuroprotection. There are several candidate neuroprotective agents that have been shown in
preclinical testing to improve outcomes following traumatic brain injury (TBI).
Xiao and colleagues have performed an in hospital, double blind, randomized,
controlled clinical trial utilizing progesterone in the treatment of patients
sustaining TBI evaluating safety and long term clinical outcomes. These data,
combined with the results of the previously published ProTECT trial, show
progesterone to be safe and potentially efficacious in the treatment of TBI.
Larger phase III trials will be necessary to verify results prior to clinical
implementation. Clinical trials networks devoted to the study of TBI are vital
to the timely clinical testing of these candidate agents and need to be
supported. Studies on the neuroprotective and promyelinating effects of progesterone in the
nervous system are of great interest due to their potential clinical
connotations. In peripheral neuropathies, progesterone and reduced derivatives
promote remyelination, axonal regeneration and the recovery of function. In
traumatic brain injury (TBI), progesterone has the ability to reduce edema and
inflammatory cytokines, prevent neuronal loss and improve functional outcomes.
Clinical trials have shown that short-and long-term progesterone treatment
induces a significant improvement in the level of disability among patients with
brain injury. In experimental spinal cord injury (SCI), molecular markers of
functional motoneurons become impaired, including brain-derived neurotrophic
factor (BDNF) mRNA, Na,K-ATPase mRNA, microtubule-associated protein 2 and
choline acetyltransferase (ChAT). SCI also produces motoneuron chromatolysis.
Progesterone treatment restores the expression of these molecules while
chromatolysis subsided. SCI also causes oligodendrocyte loss and demyelination.
In this case, a short progesterone treatment enhances proliferation and
differentiation of oligodendrocyte progenitors into mature myelin-producing
cells, whereas prolonged treatment increases a transcription factor (Olig1)
needed to repair injury-induced demyelination. Progesterone neuroprotection has
also been shown in motoneuron neurodegeneration. In Wobbler mice spinal cord,
progesterone reverses the impaired expression of BDNF, ChAT and Na,K-ATPase,
prevents vacuolar motoneuron degeneration and the development of mitochondrial
abnormalities, while functionally increases muscle strength and the survival of
Wobbler mice. Multiple mechanisms contribute to these progesterone effects, and
the role played by classical nuclear receptors, extra nuclear receptors,
membrane receptors, and the reduced metabolites of progesterone in
neuroprotection and myelin formation remain an exciting field worth of
exploration. Biologic sex and sex steroids are important factors in clinical and experimental
stroke and traumatic brain injury (TBI). Laboratory data strongly show that
progesterone treatment after TBI reduces edema, improves outcomes, and restores
blood-brain barrier function. Clinical studies to date agree with these data,
and there are ongoing human trials for progesterone treatment after TBI.
Estrogen has accumulated an impressive reputation as a neuroprotectant when
evaluated at physiologically relevant doses in laboratory studies of stroke, but
translation to patients remains to be shown. The role of androgens in male
stroke or TBI is understudied and important to pursue given the epidemiology of
stroke and trauma in men. To date, male sex steroids remain largely evaluated at
the bench rather than the bedside. This review evaluates key evidence and
highlights the importance of the platform on which brain injury occurs (i.e.,
genetic sex and hormonal modulators). IMPORTANCE OF THE FIELD: Traumatic brain injury (TBI) has yet to find a safe and
effective acute-stage neuroprotective treatment. Experimental drugs targeting a
single receptor mechanism, gene, or brain locus have failed.
AREAS COVERED IN THIS REVIEW: We review the latest clinical trials using
progesterone (PROG) to treat moderate to severe TBI, and present background
showing why this hormone and some of its metabolites should be considered as
candidates for neuroprotective therapy. TBI is a complex disease caused by a
cascade of systemic toxic events in the brain and throughout the body. Attention
is now turning to combinatorial or pleiotropic drugs that act on multiple
genomic, proteomic and metabolic pathways to enhance morphological and
functional outcomes.
WHAT THE READER WILL GAIN: PROG has long been considered merely a female
reproductive hormone with little role in neuroprotection after brain injury.
This review will help readers to understand that PROG and its metabolites have
multiple neuroprotective mechanisms, and may be among the first safe, low-cost,
easily administered, effective treatments for a variety of CNS disorders.
TAKE HOME MESSAGE: The idea that PROG is just a female reproductive hormone is
outdated. We propose that PROG has substantial pleiotropic properties as a
neuroprotective agent in a variety of CNS injury models. BACKGROUND: Traumatic brain injury is a leading cause of death and disability.
Progesterone is a potential neuroprotective drug to treat patients with
traumatic brain injury.
OBJECTIVES: To assess the effectiveness and safety of progesterone in people
with acute traumatic brain injury (TBI).
SEARCH STRATEGY: We searched: the Cochrane Injuries Group's Specialised Register
(to April 2010), Cochrane Central Register of Controlled Trials 2010, Issue 1
(The Cochrane Library), MEDLINE (Ovid) (1950 to April week 1 2010), EMBASE
(Ovid) (1980 to week 14 2010), LILACS (to 17 April 2010 ), Zetoc (to 21 April
2010), Clinicaltrials.gov (17 April 2010 ), Controlled-trials.com (17 April
2010).
SELECTION CRITERIA: We included published and unpublished randomised controlled
trials (RCTs) of progesterone versus no progesterone (or placebo) for the
treatment of acute TBI.
DATA COLLECTION AND ANALYSIS: Two authors independently screened search results
to identify the full texts of potentially relevant studies for inclusion. From
the results of the screened searches two authors independently selected trials
meeting the inclusion criteria, with no disagreement.
MAIN RESULTS: Three studies were included with 315 patients. All three studies
reported the effects of progesterone on mortality. The pooled relative risk (RR)
for mortality at end of follow-up is 0.61, 95% confidence interval (CI) 0.40 to
0.93. Three studies measured disability and found the RR of death or severe
disability in patients treated with progesterone was 0.77, 95% confidence
interval (CI) 0.62 to 0.96. Two studies presented data on intracranial pressure
and adverse events. One study presented blood pressure and temperature data.
There was no substantial evidence for the presence of heterogeneity.
AUTHORS' CONCLUSIONS: Current clinical evidence from three small RCTs indicates
progesterone may improve the neurologic outcome of patients suffering TBI. This
evidence is still insufficient and further multicentre randomised controlled
trials are required. Despite decades of laboratory research and clinical trials, a safe and effective
treatment for traumatic brain injury has yet to reach clinical practice. The
failure is due in part to the prevalence of a reductionist philosophy and
research praxis that targets a single receptor mechanism, gene, or brain locus.
This approach fails to account for the fact that traumatic brain injury is a
very complex disease caused by a cascade of systemic toxic events in the brain
and throughout the body. Attention is now turning to pleiotropic drugs that act
on multiple genomic, proteomic, and metabolic pathways to enhance morphological
and functional outcomes after brain injury. Of the agents now in clinical trial,
the neurosteroid progesterone appears to hold considerable promise. Many still
assume that progesterone is "just a female hormone" with limited, if any,
neuroprotective properties, but this view is outdated. This review will survey
the evidence that progesterone has salient pleiotropic properties as a
neuroprotective agent in a variety of central nervous system injury models. This
article is part of a Special Issue entitled: Neuroactive Steroids: Focus on
Human Brain. La progestérone est indispensable à la grossesse normale mais nous savons
maintet qu'elle a aussi d'autres fonctions importantes. De récentes
recherches démontrent que cette hormone est aussi un puissant neurostéroïde
susceptible de protéger les cellules des systèmes nerveux périphérique et
central altérées, et qu'elle est capable d'action rapide allant bien au-delà de
ses effets sur le classique récepteur intranucléaire à la progestérone. Des
années de recherche préclinique ont démontré sa sécurité d'emploi et son
efficacité dans des modèles animaux de lésion du système nerveux central.
L'hormone a été récemment évaluée dans deux études cliniques de phase 2 pour les
lésions cérébrales traumatiques (LCT). Une étude clinique nationale de phase 3,
ficée par les National Institutes of Health aux États-Unis, évalue maintet
la progestérone dans les LCT modérées à sévères chez 1 200 patients. Une étude
internationale de phase 3 ficée par l'industrie est également en cours ainsi
que la planification d'une étude utilisant la progestérone pour traiter les
lésions cérébrales chez l'enfant. Des données précliniques suggèrent que la
progestérone pourrait être aussi efficace dans les accidents vasculaires
cérébraux et certains troubles neurodégénératifs. OBJECTIVE: To evaluate all the possible therapeutic measures concerning the
acute management of traumatic brain injury (TBI) mentioned in Cochrane
Systematic Reviews published in the Cochrane Database of Systematic Reviews
(CDSR).
METHODS: An exhausted literature search for all published Cochrane Systematic
Reviews discussing therapeutic rather than prevention or rehabilitative
interventions of TBI was conducted. We retrieved such databases as CDSR and
Cochrane Injury Group, excluded the duplications, and eventually obtained 20
results, which stand for critical appraisal for as many as 20 different measures
for TBI patients. The important data of each systematic review, including total
population, intervention, outcome, etc, were collected and presented in a
designed table. Besides, we also tried to find out the possible weakness of
these clinical trials included in each review.
RESULTS: Analysis of these reviews yielded meanfuling observations: (1) The
effectiveness of most ordinary treatments in TBI is inconclusive except that
corticosteroids are likely to be ineffective or harmful, and tranexamic acid,
nimodipine and progesterone show a promising effect in bleeding trauma,
traumatic subarachnoid hemorrhage, TBI or severe TBI. (2) A majority of the
systematic reviews include a small number of clinical trials and the modest
numbers of patients, largely due to the uncertainty of the effectiveness. (3)
The quality of most trials reported in the systematic reviews is more or less
questionable. (4) In addition, lots of other complex factors together may lead
to the inconclusive results demonstrated in the Cochrane Systematic Reviews.
CONCLUSIONS: For clinical physicians, to translate these conclusions into
practice with caution is essential. Basic medication and nursing care deserve
additional attention as well and can be beneficial. For researchers, high
quality trials with perfect design and comprehensive consideration of various
factors are urgently required. Progesterone (PROG) has been shown to protect the brain from traumatic injury
and is now in Phase III clinical trials. Our work shows that PROG's beneficial
effects can be reduced in vitamin D hormone (VDH)-deficient subjects. VDH can
modulate neuronal apoptosis, trophic factors, inflammation, oxidative stress,
excitotoxicity, and myelin and axon repair. We investigated whether VDH combined
with PROG could improve behavioral outcomes more than PROG alone in
VDH-sufficient rats given bilateral contusions of the medial frontal cortex.
PROG and different doses of VDH (1 μg/kg, VDH1; 2.5 μg/kg, VDH2; 5 μg/kg, VDH3)
were injected intraperitoneally 1 h post-injury. Eight additional doses of PROG
were given subcutaneously over 8 days with tapering over the last 2 days.
Neurobehavioral tests, necrotic cavity, neuronal death and activation of
astrocytes were evaluated 21 days post-injury. We found that PROG and PROG + VDH
preserve spatial memory processing. VDH1 + PROG improved performance in
acquisition more effectively than PROG alone, indicating that the low VDH dose
is optimal for combination therapy. There were no significant differences in
necrotic cavity size among the groups. The density of positive staining for
reactive astrocytes (glial fibrillary acidic protein (GFAP)) increased and the
cell bodies and processes of GFAP-positive cells were enlarged in the PROG +
VDH1 group. Our data indicate that the combination of PROG and VDH is more
effective than PROG alone in preserving spatial and reference memory, and that
PROG plus low-dose VDH can activateGFAP reactions up to 21 days after injury.
This effect may be one of the mechanisms underlying PROG's neuroprotective
effects in combination with VDH. Despite decades of laboratory research and clinical trials, a safe and effective
treatment for traumatic brain injury (TBI) has yet to be put into successful
clinical use. I suggest that much of the problem can be attributed to a
reductionist perspective and attendant research strategy directed to finding or
designing drugs that target a single receptor mechanism, gene, or brain locus.
This approach fails to address the complexity of TBI, which leads to a cascade
of systemic toxic events in the brain and throughout the body that may persist
over long periods of time. Attention is now turning to pleiotropic drugs: drugs
that act on multiple genomic, proteomic and metabolic pathways to enhance
morphological and functional outcomes after brain injury. Of the various agents
now in clinical trials, the neurosteroid progesterone (PROG) is gaining
attention despite the widespread assumption that it is "just a female hormone"
with limited, if any, neuroprotective properties. This perspective should
change. PROG is also a powerful developmental hormone that plays a critical role
in protecting the fetus during gestation. I argue here that development,
neuroprotection and cellular repair have a number of properties in common. I
discuss evidence that PROG is pleiotropically neuroprotective and may be a
useful therapeutic and neuroprotective agent for central nervous system injury
and some neurodegenerative diseases. BACKGROUND: Traumatic brain injury (TBI) is a leading cause of death and
disability. Progesterone is a potential neuroprotective drug to treat patients
with TBI.
OBJECTIVES: To assess the effectiveness and safety of progesterone in people
with acute TBI.
SEARCH METHODS: We searched: the Cochrane Injuries Group's Specialised Register
(13 July 2012), Cochrane Central Register of Controlled Trials (CENTRAL) (Issue
7, 2012), MEDLINE (Ovid) (1950 to August week 1, 2012), EMBASE (Ovid) (1980 to
week 32 2012), LILACS (12 August 2012), Zetoc (13 July 2012), Clinicaltrials.gov
(12 August 2012), Controlled-trials.com (12 August 2012).
SELECTION CRITERIA: We included published and unpublished randomised controlled
trials (RCTs) of progesterone versus no progesterone (or placebo) for the
treatment of people with acute TBI.
DATA COLLECTION AND ANALYSIS: Two review authors independently screened search
results to identify the full texts of potentially relevant studies for
inclusion. From the results of the screened searches two review authors
independently selected trials meeting the inclusion criteria, with no
disagreement.
MAIN RESULTS: Three studies were included with a total of 315 people. Two
included studies were of high methodological quality, with low risk of bias in
allocation concealment, blinding and incomplete outcome data. One study did not
use blinding and had unclear risk of bias in allocation concealment and
incomplete outcome data. All three studies reported the effects of progesterone
on mortality. The pooled risk ratio (RR) for mortality at end of follow-up was
0.61, 95% confidence interval (CI) 0.40 to 0.93. Three studies measured
disability and found the RR of death or severe disability in patients treated
with progesterone to be 0.77, 95% CI 0.62 to 0.96. Data from two studies showed
no difference in mean intracranial pressure or the rate of adverse and serious
adverse events among people in either group. One study presented blood pressure
and temperature data, and there were no differences between the people in the
progesterone or control groups. There was no substantial evidence for the
presence of heterogeneity.
AUTHORS' CONCLUSIONS: Current clinical evidence from three small RCTs indicates
progesterone may improve the neurologic outcome of patients suffering TBI. This
evidence is still insufficient and further multicentre randomised controlled
trials are required. OBJECTIVE: Severe traumatic brain injury (TBI) has a major role in mortality
rate among the other types of trauma. The aim of this clinical study was to
assess the effect of progesterone on the improvement of neurologic outcome in
patients with acute severe TBI.
METHODS: A total of 76 patients who had arrived within 8h of injury with a
Glasgow Coma Score≤8 were enrolled in the study. In a randomized style 38
received progesterone (1mg/kg per 12h for 5 days) and 38 did not.
RESULTS: There was a better recovery rate and GOS score for the patients who
were given progesterone than for those in the control group in a 3-months
follow-up period (50% vs. 21%); subgroup analysis showed a significant
difference in the percentage of favorable outcome between the two groups with
GCS of 5-8 (p=0.03).
CONCLUSION: The use of progesterone may significantly improve neurologic outcome
of patients suffering severe TBI up to 3 months after injury, especially those
with 5≤GCS≤8, providing a potential benefit to the treatment of acute severe TBI
patients. Considering this drug had no significant side effects, so progesterone
could be used in patients with severe TBI as a neuro-protective drug. OBJECTIVE: To review emerging pharmacological agents for the treatment of
traumatic brain injury with regard to survival outcomes and provide
recommendations regarding their use.
METHODS: An Ovid MEDLINE (up to May 2013) and the Cochrane Central Register of
Controlled Trials (up to May 2013) search was conducted to identify emerging
pharmacological therapies for the treatment of traumatic brain injury. The
search was limited to English language and humans. Pharmacological agents that
were evaluated with respect to survival as an outcome were included.
MAIN RESULTS: Based on the search, the investigators identified the following
new therapies: beta-receptor antagonists, erythropoiesis stimulating agents,
hydroxymethylglutaryl-CoA reductase inhibitors (statins) and progesterone. With
the exception of progesterone, which was studied in several small, randomized,
controlled trials, the remaining agents were primarily studied in observational
retrospective cohorts. For each of the agents identified, a potential increase
in survival was noted.
CONCLUSIONS: Emerging pharmacological agents represent promising treatment
options for traumatic brain injury to improve survival. Most of these agents are
commercially available for other indications. However, limitations in study
design, sample size, duration of treatment, timing of treatment and inclusion of
heterogeneous patient populations make it difficult to draw definitive
conclusions from the literature. Collaborators: Wright DW, Frankel M, Merck LH, Espinoza TR, Salomone JP, Dhall
SS, Hudgins PA, Allen JW, Goldstein F, Hertzberg V, Rogers SD, Calcaterra AM,
Howlett-Smith H, Lane B, Lunney MP, Cook N, Hall A, Hall A, McDougal A,
Subramanian A, Pradilla G, Stein DG, Silbergleit R, Barsan WG, Pancioli A,
Lowenstein D, Meurer WJ, Morgenstern LB, Stevenson V, Bengelink E, Harney D, De
Yampert A, Mawocha S, Pinkerton J, Caveney A, Yeatts S, Palesch Y, Zhao W, Pauls
Q, Pauls K, Dillon CR, Conner C, Henry A, Patel K, Simons JL, Manley G, Aarabi
B, Harris O, Hemphill C, LeRoux P, Narayan R, Okonkwo DO, Pascual J, Salomone
JP, Schwab W, Valadka A, Wright DW, Janis S, Conwit R, Denninghoff K, Friese R,
Zabramski J, Oneill PJ, Feinstein A, Yonas H, Stasinski G, Barnhart B, Wood L,
Haney S, Livergood DL, Burlbaw B, Wright DW, Frankel M, Croce MA, McCafferty RR,
Lunney MP, Panzer-Baggett S, Warren JB, Hall AJ, McDougal AG, Cook N, Wilson S,
Waddle-Smith L, Barrow S, Pitotti R, Espinoza TR, Hudgins PA, Allen JW,
Subramanian A, Fabian TC, Muhlbauer MS, Hilliard MW, Bebarta VS, Gunst MA,
Amador RR, Lo IW, Quinn JV, Lee M, Blumenfeld K, Venkatasubramanian C,
Visweswaran A, Mann R, Harris OA, D'Souza P, Spain DA, Hirsch K, Torres R, Kline
R, Benford J, Traver C, Yeh D, Pancioli A, Shutter L, Johannigman J, Bonomo J,
Stark S, Ewing I, Waymeyer P, Schmit P, Adeoye O, Mcmullan J, Robinson B,
Andaluz N, Newman P, Biros M, Irwin ED, Dries DJ, Rockswold G, Miller K, Sargent
C, Reicks P, Wewerka SS, Salzman J, Zagar A, Kragness K, Hildebrandt D, Scherber
J, Bennett BA, Zwank MD, Jones E, Milling TJ Jr, Ottman M, Mendoza-Moore M,
LaChance L, King B, Doshi P, Aufderheide TP, Lynch J, Torbey M, Boettcher M,
Bialkowski W, Brandt JT Jr, Burpee K, Gauger S, Herdeman C, Hermanson B,
Hessenthaler A, Jasti J, McCormick K, Mena M, Morrow K, Price G, Sandoval C,
Qaisar T, Quering B, Zellner S, Zeisse M, Brasel K, Maiman D, Zaidat OO, Baren
JM, Portner M, Merck LH, Sarani B, Stehly C, Bertsch K, Garey C, Lamond K,
Durinka JB, Gromek S, Jochym N, Pascual JL, Kasner SE, LeRoux PD, Schuster J,
Gentile NT, Saks M, Fisher MA, Jallo J, Timmons S, McNelis PM, Reimer H, Nocera
R, Campbell NA, Gardner K, Weaver M, Goldberg A, Wang A, Healy M, Warden CR,
Prewitt L, Hilliard C, Schreiber M, Lowe R, Ornato JP, Mathern BE, Mathern K,
Merchant RE, Feeser VR, Dhindsa HS, Leahman CE, Humphries RL, Short J,
Dechtenberg L, Taylor DG, Pettigrew L, Carter CT, Desai S, Welch RD, Swor RA,
Mika VH, Paternoster RA, Norris GM, Coplin WM, Pearson C, O'Neil BJ, Ayaz SI,
Clark CL, Sawyer KN, Rae RW Jr, Wiener MA, Grace HA, Hemphill J 3rd, Meeker M,
Duncan J, Alvarado E, Casey S, Lauder I, Manley G, Lewandowski CA, Miller JB,
Borgialli DA, Lundell AM, Baker A, LaChance J, Falvo A, Abdelhak T, Vohra T,
Nagarwala J, Fowkes R, Claassen J, Rosengart A, Falo M, Fokken T, Agarwal S,
Lord A, Connolly E, Velander A, Pavol M, Zammit C, Foreman B, Mayer S, Stern B,
Eisenberg H, Aldrich C, Ganley V, Aarabi B, Goldstein JN, Rosenthal ES, Burke P,
Nentwich LM, Howell M, Mitchell P, Riklin E, Feldman J, Levine SR, Jain A,
Zelonis S, Bushey M, Sinert R, Ver Halen N, Rojas-Soto D, Martindale J, Paladino
L, Legome E, Valsamis LH, Brandler E, Chatterjee P, Torbey M, Green A, Angelos
M, Caterino J, Elder J, Steinberg S, Callaway C, Okonkwo DO, Puccio AM, Shutter
LA, Dezfulian C. Collaborators: Marmarou A, Maas AI, Narayan R, Skolnick BE, Ward J, Stocchetti
N, Dearden NM, Clarence-Smith K, Genazzani AR, Grady MS, Steyerberg EW, Okonkwo
D, Grieve G, Zaaroor M, Levi L, Smrcka M, May A, Pachl J, Manji M, Chen J,
Pichon N, Lobato RD, Norasetthada T, Puybasset L, Petit L, Meisel H, Fakhry S,
Wilberger J, Sahuquillo J, Rabb C, Walsh J, Mokry M, Yutthakasemsunt S, Huynh T,
Rumana C, Audibert G, Citerio G, Agazzi S, Gruen J, O'Leary S, Ransom K, Trimmel
H, Turner M, Zucker L, Umansky F, Nardi G, Dominguez JI, Zauberman J, Claridge
J, Bulters D, Mace JC, McCarthy M, Colpaert K, Ratanalert S, Couture D, Choi K,
Verma V, Cheng Y, Wang E, Rosen C, Medow J, Patterson L, Alberico A, Avila RA,
Vega E, Unterberg A, Stocchetti N, Zhou L, Wong S, Beretta L, Laskowitz D,
Vincent JL, Dominguez-Roldán J, Molina JM, Wang Z, Coimbra R, German J, Emhoff
T, Boakye M, Surdell DL, García E, Leone M, Nimsky C, Sandesc D, Nagy L, Badenes
R, Öhman J, Barnes S, Jacoby M, Shillinglaw W, Orlandi C, Vander Laenen M,
Grigoriev R, Rohde V, Vajkoczy P, Raventós AA, Minguillón MA, Oram J, Kuang Y,
Chou N, Grindlinger G, Rodgers R, Tinti M, Nagy K, Pellegrini J, George R,
Brevard SB, Barbozà A, Payen JF, Troubleyn J, Lavicka P, van der Naalt J,
Spoelstra-de Man A, Molina JA, Miranda P, Lopez PM, Wright J, Thambinayagam H,
Cheng W, Fulda G, Garrote M, Schmutzhard E, Depreitere B, Greiner C, Zacharowski
K, Nevo M, Kang D, Yu R, Alias A, Nor MM, Espinosa J, Shaffrey M, Beauchamp K,
Faber T, Dailler F, Cejpek P, Belkin S, Sardaryan I, Kobyakov G, Orel V, Weber
F, Procaccio F, Della Corte F, Barzó P, Laha S, Zhang B, Cheang V, Arnold P,
Badr A, Andersen B, Putnam A 2nd, Murali R, Videtta W, Regelsberger J, Rappaport
ZH, Büki A, Mendiluce RM, Kumar D, Ng I, Tu YK. |
Is there a role for the cylindromatosis tumor suppressor (CYLD) in lung cancer? | To explore a correlation between CYLD expression and responsiveness to TRAIL in lung cancer cell lines, we established lung cancer cell lines that stably express CYLD. Our data provided the first evidence that increased expression of CYLD directly blocks TRAIL-induced NF - B activation, and consequently increases TRAIL-induced apoptosis in lung cancer cells. CYLD may act as a therapeutic target of lung cancer. Targeting CYLD, in combination with TRAIL, may be a new strategy to treat lung cancer with high NF - B activity. Cyld encodes a 956-amino acid deubiquitinating enzyme, which is a negative regulator of nuclear factor kappaB and mitogen-activated protein kinase pathways. Mutations that truncate and inactivate the carboxyl-terminal deubiquitinating domain of CYLD underlie the development of skin appendage tumors in humans, whereas down-regulation of Cyld expression has been associated with the development of various types of human malignancies including lung cancer. To establish an animal model of human CYLD inactivation and characterize the biological role of CYLD in vivo, we generated mice carrying a homozygous deletion of Cyld exon 9 mice ) using a conditional approach. Our study identifies an important role of CYLD in lung maturation, which may underlie the development of many cases of lung cancer. | Cyld encodes a 956-amino acid deubiquitinating enzyme (CYLD), which is a
negative regulator of nuclear factor kappaB and mitogen-activated protein kinase
pathways. Mutations that truncate and inactivate the carboxyl-terminal
deubiquitinating domain of CYLD underlie the development of skin appendage
tumors in humans, whereas down-regulation of Cyld expression has been associated
with the development of various types of human maligcies including lung
cancer. To establish an animal model of human CYLD inactivation and characterize
the biological role of CYLD in vivo, we generated mice carrying a homozygous
deletion of Cyld exon 9 (Cyld(Delta 9/Delta 9) mice) using a conditional
approach. Deletion of exon 9 would cause a carboxyl-terminal truncation of CYLD
and inactivation of its deubiquitinating activity. In accordance with previous
studies, fibroblasts from Cyld(Delta 9/Delta 9) embryos had hyperactive nuclear
factor kappaB and c-Jun kinase pathways compared with control fibroblasts.
Cyld(Delta 9/Delta 9) newborn mice were smaller than wild-type littermates with
a short and kinky tail and no major developmental defects. However, Cyld(Delta
9/Delta 9) mice died shortly after birth from apparent respiratory dysfunction.
Histological examination of E18.5 Cyld(Delta 9/Delta 9) lungs demonstrated an
immature phenotype characterized by hyperplasic mesenchyme but apparently normal
epithelial, smooth muscle. and endothelial structures. Our study identifies an
important role of CYLD in lung maturation, which may underlie the development of
many cases of lung cancer. |
Which medical diagnostic tests are used to test kidney function? | Most common tests used in diagnosing normal kidney function include blood tests such as serum creatinine levels, glomerular filtration rate (GFR) and blood urea nitrogen (BUN) levels, also medical imaging tests like ultrasound and CT Scan. Additionally kidney biopsy is used in more direct but invasive approach. Lastly, and probably the most relevant tests to kidney function are urine tests along the lines of urinalysis, urine protein levels and microalbuminuria creatinine clearance. | Eighty measurements of plasma creatinine concentration, height:creatinine ratio,
and plasma beta 2 microglobulin concentration were made on 72 children (age 4
months-18.5 years) with known renal disease. Results were compared with
simultaneous measurements of glomerular filtration rate using plasma clearance
of 51Cr edetic acid to assess the performance of each test as an initial
screening procedure of renal insufficiency. Height:creatinine index less than
2.1 was found to have a higher sensitivity and predictive value of a normal
result than the other tests and is therefore the preferred test for a screening
procedure. There is much symptomatic similarity between acute kidney disease and acute
heart disease. Both may present with shortness of breath and chest discomfort,
and thus it is not surprising that biomarkers of acute myocardial and renal
disease often coexist in many physicians' diagnostic work-up schedules. In this
review we explore the similarities and differences between current and future
tests of myocardial and renal injury and function, with particular emphasis on
the diagnostic utility of currently available biomarkers to assist with the
diagnosis of cardiorenal syndromes. Imaging studies have not traditionally been
viewed as clinical biomarkers, but as tests of structure and function; they
contribute to the diagnostic process, and we believe that they should be
considered alongside more traditional biomarkers such as blood and urine
measurements of circulating proteins and metabolites. We discuss the place of
natriuretic peptides, novel tests of kidney damage as well as kidney function
and conclude with a discussion of their place in guiding future research studies
whose goals must include better characterization of the degree of dysfunction
imposed on one organ system by failure of the other. BACKGROUND: Increased proteinuria would lead to a larger risk for renal failure
in the long term. Therefore, proteinuria requires immediate and thorough
evaluation. This study was designed to evaluate the effects of pioglitazone on
proteinuria in patients with non-diabetic renal disease.
METHODS: In this self-controlled clinical trial study, forty four non-diabetic
patients aged 18 and more, who had renal disease and a stable proteinuria of
over 0.5 g in 24 hour, were studied. All patients received 15 mg of daily
pioglitazone for 4 months. Urine protein excretion was measured as a main end
point prior to the study, at the end of the 2nd and 4th months of treatment, and
2 and 4 months after the cessation of the active drug. Other evaluated variables
included systolic blood pressure, serum creatinine, urea, alanine
aminotransferase (ALT), aspartate aminotransferase (AST), fasting blood sugar
(FBS), blood urea nitrogen (BUN) and glomerular filtration rate (GFR) levels.
RESULTS: Proteinuria (mean ± SEM) prior to the study, at the 2nd and 4th months
of the treatment, and 2 and 4 months after the cessation of pioglitazone were
1088.6 ± 131.1, 699.9 ± 118.3, 433.9 ± 68.7, 416.1 ± 54.9 and 646.9 ± 89.1,
respectively (p < 0.001). In addition, the reduction of 24-hour urine protein
was statistically significant for both male and female patients (p < 0.001 for
both).
CONCLUSIONS: A reduction of proteinuria in patients with non-diabetic renal
disease was observed during the 4-month treatment with pioglitazone which
continued for 2 months after the cessation of the treatment. However, 4 months
after the cessation of the treatment, a little increase was detected in the
level of proteinuria. To estimate the glomerular filtration rate (GFR) in conscious rabbits, a
single-sample method using the non-ionic contrast medium iodixanol was compared
with a three-sample method using the standard agent inulin. Iodixanol and inulin
were co-administered intravenously to male New Zealand White rabbits at 60 mg
I/kg and 40 mg/kg, respectively, and blood was collected 30, 60, 90 and 120 min
later. Serum iodixanol and inulin concentrations were separately determined by
high performance liquid chromatography and colorimetry, respectively. Serum urea
nitrogen (UN) and creatinine concentrations were also determined. Based on the
data from healthy and cisplatin-treated rabbits, the GFR estimated by iodixanol
was well consistent with that by inulin. Further, when the GFR decreased to more
than 60% of the reference value, serum creatinine concentrations became
elevated. However, serum UN concentrations exhibited wide fluctuations,
presumably due to a difference in renal handlings. The single-sample method
using iodixanol was considered to be an expedient tool in both clinical and
research settings, because the stress due to a multi-sample method was reduced. The aim of this study was to investigate the normal values of glomerular
filtration rate (GFR) by technetium-99m diaethylene-triamine-pentaacetic acid
((99m)Tc-DTPA) renal dynamic imaging for living kidney graft donors. In a total
of 212 candidate donors, GFR was examined using (99m)Tc-DTPA renal dynamic
imaging. Donors with GFR≥80mL/(min×1.73m(2)) and as low as with
GFR≥70mL/(min×1.73m(2)) but a normal endogenous creatinine clearance rate (CCr)
were quantified for living kidney donation. Differences in GFR levels based on
sex and age were analyzed using rank correlation coefficient. Out of the 212
candidates, 161 were finally selected as kidney graft donors. The double kidney
total GFR between the male and female donor groups, the GFR levels among
differently-aged donor groups, and the GFR levels between the elderly (>55
years) and young- and middle-aged (≤55 years) donor groups did not show any
significant difference (P>0.05). After kidney donation, renal function measured
by blood urea nitrogen (BUN) and serum creatinine of all donors returned to
normal within one week, and no serious complications were noticed. In
conclusion, renal dynamic imaging by (99m)Tc-DTPA had a good accuracy and
repeatability in GFR evaluation for living kidney donors. Candidate donors with
GFR between 70mL/(min×1.73m(2)) and 80mL/(min×1.73m(2)) can be selected as
kidney donors after strict screening. In living kidney donors GFR is not
significantly correlated with age or sex. OBJECTIVE: The objective of this article is to review and evaluate the various
parameters used in determining renal status.
CONCLUSION: The physiologic determination of renal status is the measured
glomerular filtration rate (mGFR). Serum creatinine, blood urea nitrogen,
cystatin C, and estimated GFR (eGFR), based on serum creatinine have failed to
replace mGFR. All physicians should be aware of limitations of substituted mGFR. STUDY OBJECTIVE: To determine the rate, risk factors, and outcome of
vancomycin-associated acute kidney injury (AKI) in critically ill children.
DESIGN: Retrospective cohort study.
SETTING: Tertiary care children's hospital.
PATIENTS: We reviewed the charts of children admitted to the pediatric intensive
care unit during a 2-year period who were treated with vancomycin. Courses of
vancomycin interrupted by 3 days or more were counted separately. Patients were
excluded if they received vancomycin treatment for fewer than 3 days, had
preexisting renal failure, or had incomplete serum creatinine (Scr ) data.
MEASUREMENTS AND MAIN RESULTS: Demographic and laboratory data; vancomycin dose,
duration, and concentrations; and concurrent use of nephrotoxic drugs were
recorded. Acute kidney injury was defined as a decrease in estimated glomerular
filtration rate of 50% or more from the beginning of vancomycin therapy.
Descriptive statistics, step-wise logistic regression, and repeated measures
ANOVA were used to analyze the data. A total of 284 patients were included, for
a total of 391 courses of vancomycin (272 children and 119 infants). The mean
duration of vancomycin therapy was 6.9 ± 4.5 days. Forty nine (17.2%) patients
developed AKI during 61 (15.6%) courses. Elevated Scr concentrations returned to
baseline after stopping vancomycin in 53 (87%) courses. Mortality was higher in
children who developed AKI (p<0.001; Fisher's exact test). Administration of
nephrotoxic drugs (odds ratio 2.23, Confidence Interval 1.27-3.93) and presence
of high blood urea nitrogen (BUN):Scr ratio before vancomycin therapy (p<0.05)
were associated with AKI. The BUN and Scr concentrations significantly increased
during vancomycin therapy and decreased after vancomycin was discontinued
(p<0.05).
CONCLUSIONS: In critically ill children, the development of reversible AKI
during vancomycin therapy is associated with administration of nephrotoxic drugs
and an elevated BUN: Scr ratio. BACKGROUND: Decreased tryptophan (TRP) and increased kynurenine (KYN) and
kynurenic acid (KYNA) in blood have been reported in patients and experimental
animals with renal diseases. We investigated if these compounds could be used as
new biomarkers for the assessment of renal function.
METHODS: Eighty hospitalized hypertensive patients (20 with chronic kidney
disease (CKD), and other 60 were considered as control) were enrolled for the
investigation. Plasma TRP, KYN, and KYNA were determined by high-performance
liquid chromatography. Change rate (CR) was employed to evaluate the sensitivity
of the parameters of renal function.
RESULTS: CR of plasma KYNA/TRP ratio (+103%) was much higher than the CRs of
blood urea nitrogen (+44%), serum creatinine (+56%) and estimated glomerular
filtration rate (-35%). Plasma KYNA/TRP ratio was in close relationship with
blood urea nitrogen (r = 0.622), serum creatinine (r = 0.797), urine
micro-albumin/24-h (r = 0.518) and estimated glomerular filtration rate (r =
-0.662), respectively, with all p-values <0.001.
CONCLUSIONS: Plasma KYNA/TRP ratio was sensitive and reliable to indicate renal
function and could be used as a new biomarker to assess the risk or presence of
kidney disease. |
Against which protein is the antibody used for immonostaining of Lewy bodies raised? | alpha-Synuclein is a presynaptic protein, which was identified as a specific component of Lewy bodies (LB) and Lewy neurites. Therefore, immunostaining for detecting the presence of Lewy bodies is carried out using antibodies against alpha-synuclein. | A mutation in the alpha-synuclein gene has recently been linked to some cases of
familial Parkinson's disease (PD). We characterized the expression of this
presynaptic protein in the midbrain, striatum, and temporal cortex of control,
PD, and dementia with Lewy bodies (DLB) brain. Control brain showed punctate
pericellular immunostaining. PD brain demonstrated alpha-synuclein
immunoreactivity in nigral Lewy bodies, pale bodies and abnormal neurites. Rare
neuronal soma in PD brain were immunoreactive for alpha-synuclein. DLB cases
demonstrated these findings as well as alpha-synuclein immunoreactivity in
cortical Lewy bodies and CA2-3 neurites. These results suggest that, even in
sporadic cases, there is an early and direct role for alpha-synuclein in the
pathogenesis of PD and the neuropathologically related disorder DLB. The precursor of the non-Abeta component of Alzheimer's disease amyloid (NACP)
(also known as alpha-synuclein) is a presynaptic terminal molecule that
abnormally accumulates in the plaques of Alzheimer's disease (AD) and in the
Lewy bodies (LBs) of Lewy body variant of AD, diffuse Lewy body disease, and
Parkinson's disease. To better understand the distribution of
NACP/alpha-synuclein and its fragments in the LB-bearing neurons and neurites,
as well as to clarify the patterns of NACP/alpha-synuclein compartmentalization,
we studied NACP/alpha-synuclein immunoreactivity using antibodies against the
C-terminal, N-terminal, and NAC regions after Proteinase K and formic acid
treatment in the cortex of patients with LBs. Furthermore, studies of the
subcellular localization of NACP/alpha-synuclein within LB-bearing neurons were
performed by immunogold electron microscopy. These studies showed that the
N-terminal antibody immunolabeled the LBs and dystrophic neurites with great
intensity and, to a lesser extent, the synapses. In contrast, the C-terminal
antibody strongly labeled the synapses and, to a lesser extent, the LBs and
dystrophic neurites. Whereas Proteinase K treatment enhanced
NACP/alpha-synuclein immunoreactivity with the C-terminal antibody, it
diminished the N-terminal NACP/alpha-synuclein immunoreactivity. Furthermore,
formic acid enhanced LB and dystrophic neurite labeling with both the C- and
N-terminal antibodies. In addition, whereas without pretreatment only slight
anti-NAC immunoreactivity was found in the LBs, formic acid pretreatment
revealed an extensive anti-NAC immunostaining of LBs, plaques, and glial cells.
Ultrastructural analysis revealed that NACP/alpha-synuclein immunoreactivity was
diffusely distributed within the amorphous electrodense material in the LBs and
as small clusters in the filaments of LBs and neurites. These results support
the view that aggregated NACP/alpha-synuclein might play an important role in
the pathogenesis of disorders associated with LBs. alpha-Synuclein is a presynaptic protein recently identified as a specific
component of Lewy bodies (LB) and Lewy neurites. The aim of this study was to
assess the morphology and distribution of alpha-synuclein immunoreactivity in
cases of dementia with LB (DLB), and to compare alpha-synuclein with ubiquitin
immunostaining. We examined substantia nigra, paralimbic regions (entorhinal
cortex, cingulate gyrus, insula and hippocampus), and neocortex (frontal and
occipital association cortices) with double alpha-synuclein and ubiquitin
immunostaining in 25 cases meeting neuropathological criteria for DLB.
alpha-Synuclein immunostaining was more specific than ubiquitin immunostaining
in that it differentiated LB from globose tangles. It was also slightly more
sensitive, staining 4-5% more intracytoplasmic structures, especially diffuse
alpha-synuclein deposits that were ubiquitin negative. In addition to LB,
alpha-synuclein staining showed filiform and globose neurites in the substantia
nigra, CA2-3 regions of the hippocampus, and entorhinal cortex. A spectrum of
alpha-synuclein staining was seen in substantia nigra: from diffuse "cloud-like"
inclusions to aggregated intracytoplasmic inclusions with variable ubiquitin
staining to classic LB. We hypothesize that these represent different stages in
LB formation. BACKGROUND: Dementia is a frequent complication of idiopathic parkinsonism or
PD, usually occurring later in the protracted course of the illness. The primary
site of neuropathologic change in PD is the substantia nigra, but the
neuropathologic and molecular basis of dementia in PD is less clear. Although
Alzheimer's pathology has been a frequent finding, recent advances in
immunostaining of alpha-synuclein have suggested the possible importance of
cortical Lewy bodies (CLBs) in the brains of demented patients with PD.
METHODS: The brains of 22 demented and 20 nondemented patients with a clinical
and neuropathologic diagnosis of PD were evaluated with standard neuropathologic
techniques. In addition, CLBs and dystrophic neurites were identified
immunohistochemically with antibodies specific for alpha-synuclein and
ubiquitin; plaques and tangles were identified by staining with thioflavine S.
Associations between dementia status and pathologic markers were tested with
logistic regression.
RESULTS: CLBs positive for alpha-synuclein are highly sensitive (91%) and
specific (90%) neuropathologic markers of dementia in PD and slightly more
sensitive than ubiquitin-positive CLBs. They are better indicators of dementia
than neurofibrillary tangles, amyloid plaques, or dystrophic neurites.
CONCLUSION: CLBs detected by alpha-synuclein antibodies in patients with PD are
a more sensitive and specific correlate of dementia than the presence of
Alzheimer's pathology, which was present in a minority of the cases in this
series. Hallervorden-Spatz syndrome (HSS) is a rare autosomal recessive disorder
clinically characterized by extrapyramidal signs and progressive dementia. In a
typical case, the clinical symptoms become apparent during late childhood, and
usually the course is protracted over a decade or more. We recently had an
opportunity to study the brains of two cases of HSS with a clinical course of
over 30 years. Case 1 was a 44-year-old female and case 2 was a 37-year-old
male. Grossly, the brains showed severe fronto-temporal lobar atrophy with
abundant spheroids and mild iron deposits in the globus pallidus, associated
with features of motor neuron disease. In addition, there was diffuse sponginess
in the atrophic cortex as well as widespread Alzheimer's neurofibrillary tangles
(NFTs) and Lewy bodies (LBs) in the cortical and subcortical regions, including
the spinal cord. Ultrastructurally, NFTs were composed of paired helical
filaments, and LBs of central dense cores with radiating fibrils. Discrete
immunostaining was demonstrated in NFTs and neuropil threads with various
antibodies against phosphorylated tau, and in LBs with antibody against
alpha-synuclein. In addition, diffuse, overlapping immunoreactivity of
alpha-synuclein and phosphorylated tau was seen within the cytoplasm of many
neurons. However, when LBs and NFTs coexisted within the same neurons, they were
clearly segregated. The findings of our present cases as well as those reported
in the literature may indicate that simultaneous and extensive occurrence of
abnormal phosphorylation of tau and accumulation of alpha-synuclein may
constitute cardinal pathological features of HSS with protracted clinical
course. It is increasingly clear that the normal protein alpha-synuclein is in some
manner closely associated with presynaptic components of select neuronal types
within the adult human central nervous system (CNS) and, in addition, that in
its pathologically altered state alpha-synuclein aggregates selectively in the
form of filamentous inclusion bodies during certain progressive
neurodegenerative disorders, such as familial and sporadic Parkinson's disease.
By having the antibody AFshp raised specifically to alpha-synuclein to label
Parkinson disease-specific Lewy bodies and Lewy neurites as well as synaptic
boutons containing the unaltered protein, an initial attempt is made to map the
overall distribution pattern and describe the staining behavior of the
immunoreactive punctae in select regions of the prosencephalon. Neocortical
immunolabeling is most prominent in the prodigious, but incompletely myelinated,
association fields and faintest in the heavily myelinated primary motor and
primary sensory fields, with the premotor and first order sensory association
areas occupying an intermediate position. Of the thalamic grays evaluated, those
containing powerfully myelinated fiber tracts (e.g. centrum medianum, habenular
complex) show the weakest immunolabeling, whereas, less sturdily myelinated
structures are highly immunoreactive. The fact that the immunostaining spectrum
for normal alpha-synuclein is so broad, together with the fact that some
thalamic sites actually are immunonegative leads to the following conclusions
(1) alpha-synuclein, although present in the synaptic boutons of many nerve
cells in the adult human CNS, is by no means ubiquitous there, and (2) neuronal
types lacking the normal protein cannot generate the Parkinson's
disease-specific filamentous pathology. Diffuse Lewy body disease (DLBD) is characterized by the presence of Lewy bodies
(LB) in the neurons and neurites of cortical, subcortical, and brain stem
structures. Recently, alpha-synuclein (alphaS) has been found to be a central
constituent of LB. In DLBD, abnormal accumulation of alphaS has been reported in
both neurons and glia, but studies on glial lesions in DLBD have been limited.
We examined in detail the constituents and distribution of glial lesions in
eight patients with DLBD and report the pathogenesis of the glial lesions.
alphaS-positive neuronal cytoplasmic inclusions (NI), neuropil threads (NT), and
coiled bodies (CB) showed similar immunostaining profiles. Without pretreatment,
NI, NT, and CB were detected by all antibodies against alphaS. The
immunostaining profile of star-like astrocytes (SLA) was quite different from
those of NI, NT, and CB. A few SLA were stained by an antibody against the
non-Abeta component portion of alphaS without pretreatment, but formic acid
pretreatment dramatically enhanced SLA immunoreactivity. SLA and CB were found
in all eight brains with DLBD. SLA were scarce in the brain stem, but there were
hundreds of SLA per visual field at x100 magnification in the temporal cortex of
most cases, while CB were found diffusely in both the cerebral cortex and brain
stem, similar to NI. This suggests that the pathogenesis of SLA is different
from those of NI and CB. The major protein constituent of Lewy bodies (LBs), the pathological hallmark of
Parkinson disease and dementia with Lewy bodies, is considered to be
alpha-synuclein, but other proteins, in particular the microtubule-associated
protein tau, have been implicated in the pathogenesis of LBs. Tau is the major
structural component of neurofibrillary tangles (NFTs). Both direct
immunochemical studies of partially purified LBs and indirect
immunohistochemical studies have suggested that LBs may contain tau, but most of
these studies were based upon a single tau antibody, and immunologic
cross-reactivity was not completely excluded. To gain insight into the relation
between tau and alpha-synuclein in LBs, double immunostaining was performed in
Lewy body cases with a rabbit polyclonal antibody to alpha-synuclein and a panel
of monoclonal antibodies to phospho- and nonphospho-tau epitopes (Alz50, CP9,
CP13, PG5, TG3, PHFI) that spanned the length of the tau molecule.
Tau-immunoreactive LBs were present in the medulla in 80% of the cases,
irrespective of Braak stage. All tau antibodies recognized at least some LBs,
arguing against nonspecific antibody cross-reactivity. In most lesions the tau
immunostaining was present at the periphery of the LB. The phospho-tau antibody,
TG3, detected more LBs than any of the other tau antibodies. The proportion of
LBs with tau immunoreactivity was greatest in neurons vulnerable to NETs, such
as those in the locus ceruleus and basal nucleus of Meynert, and least in
neurons resistant to NFTs, such as the dorsal motor nucleus of the vagus in the
medulla. The present results suggest that tau may coaggregate with
alpha-synuclein in LBs, especially in neuronal populations vulnerable to both
NFTs and LBs. Progressive supranuclear palsy (PSP) is a neurodegenerative tauopathy
characterized by Parkinsonism, vertical gaze palsy, and early falls. Lewy bodies
(LBs) are detected in approximately 10% of PSP cases, but there is little
information on the relationship of LBs to tau pathology. We determined the
frequency of LBs in a large series of autopsy-confirmed cases of PSP and studied
the density and distribution of LBs, including Parkinson disease stage, in cases
with LBs (PSP/LBD). PSP/LBD was compared with pure LB disease (LBD), including
assessment of neuronal loss in key brainstem nuclei. Immunohistochemistry for
alpha-synuclein revealed LBs in 31 of 290 PSP cases (11%). One case had multiple
system atrophy in addition to PSP and was excluded from further study along with
2 PSP/LBD cases with concurrent Alzheimer disease. The 29 cases of PSP/LBD were
compared with 30 cases of PSP and 24 cases of LBD. The age, sex, brain weight,
Braak neurofibrillary tangle (NFT) stage, as well as counts of NFTs and senile
plaques were not different among PSP, LBD, and PSP/LBD, but disease duration was
longer in LBD. The Parkinson disease stage was similar, but the density of LBs
in most subcortical nuclei tended to be greater in LBD than in PSP/LBD. In
contrast, substantia nigra neuronal loss was greater in PSP/LBD than both PSP
and LBD. Double immunostaining demonstrated alpha-synuclein and tau in different
neurons with few exceptions. The findings suggest that LBs in PSP are similar in
distribution to those in LBD and independent of tau pathology. The greater
density of LBs in LBD compared with PSP/LBD may be the result of longer disease
duration in LBD, whereas greater neuronal loss in the substantia nigra in
PSP/LBD may be the result of vulnerability of this brain region to both disease
processes. Parkinson's disease and dementia with Lewy bodies are very frequent neurological
disorders of the elderly. Mutations in the alpha-synuclein (alphaSYN) gene cause
Parkinson's disease, often associated with dementia. Neuropathologically these
diseases are characterized by the presence of Lewy bodies and Lewy neurites,
intraneuronal inclusions mostly composed of alphaSYN protein fibrils. Moreover,
alphaSYN is phosphorylated at S129 (phospho-serine-129 [PSer129]) in
neuropathological lesions. Using our (Thy1)-[A30P]alphaSYN transgenic mouse
model that develops age-dependent impairment in fear conditioning behavior, we
investigated PSer129 immunostaining in the brain. We found distinct staining
patterns using new, sensitive monoclonal antibodies. Somal and nuclear PSer129
immunoreactivity increased with age in hippocampal and cortical areas as well as
the lateral/basolateral amygdalar nuclei and was present also in young,
pre-symptomatic mice, but not wild-type controls. The tendency of PSer129
immunostaining to accumulate in the nucleus was confirmed in cell culture.
(Thy1)-[A30P]alphaSYN transgenic mice further developed age-dependent, specific
neuritic/terminal alphaSYN pathology in the medial parts of the central
amygdalar nucleus and one of its projection areas, the lateral hypothalamus.
Interestingly, this type of PSer129 neuropathology was thioflavine S negative,
unlike the Lewy-like neuropathology present in the brain stem of
(Thy1)-[A30P]alphaSYN mice. Thus, alphaSYN becomes phosphorylated in distinct
parts of the brain in this alpha-synucleinopathy mouse model, showing
age-dependent increases of nuclear PSer129 in cortical brain areas and the
formation of neuritic/terminal PSer129 neuropathology with variable amyloid
quality within the fear conditioning circuitry and the brain stem. α-Synuclein is the major protein associated with Lewy body dementia, Parkinson's
disease and multiple system atrophy. Since α-synuclein is present in the brain
in physiological conditions as a presynaptic protein, it is crucial to
characterize disease-associated modifications to develop an in vivo biomarker.
With the aim to develop antibodies showing high specificity and sensitivity for
disease-associated α-synuclein, synthetic peptides containing different amino
acid sequences were used for immunization of mice. After generation of
α-synuclein aggregates, ELISA and immunoblotting were used to test the
specificity of antibodies. Tissue microarray sections originating from different
human α-synucleinopathies were used to compare immunostaining with other,
commercially available antibodies. Immunization of mice with the peptide
TKEGVVHGVATVAE (amino acid 44-57 of α-synuclein) resulted in the generation of a
monoclonal antibody (5G4), which was able to bind aggregated α-synuclein
preparation in sandwich ELISA or coated on magnetic beads. 5G4 proved to be
superior to other antibodies in comparative immunohistochemical studies by
revealing more widespread and distinct α-synuclein pathology. Immunoblotting of
human brain tissue revealed an additional band seen in dementia with Lewy
bodies, whereas the band representing monomeric α-synuclein was very weak or
lacking. In summary, the 5G4 antibody is most promising for re-evaluation of
archival material and may offer new perspective for the development of in vivo
diagnostic assays for detecting disease-associated α-synuclein in body fluids. |
Which are the main causes of fetal echogenic bowel? | Fetal echogenic bowel is mainly associated to feto-maternal, intramniotic bleeding but in several cases it is linked to cystic fibrosis, cytomegalovirus (CMV), herpes simplex virus and other viral infections and fetal aneuploidy. | Congenital cytomegalovirus infection with oligohydramnios and echogenic bowel at
14 weeks' gestation. Though echogenic fetal bowel has been associated with meconium ileus and/or
peritonitis, it may be a normal finding in the second trimester. The purpose of
this study is to determine which characteristics might distinguish fetuses
ultimately having abnormal outcomes in a population at low risk for cystic
fibrosis. Seven fetuses with echogenic bowel were identified: 5 fetuses < or =
20 weeks gestation (group 1) and 2 fetuses 20-25 weeks gestation (group 2) at
diagnosis. Four of 5 group 1 fetuses had resolution of the echogenic bowel
during the second trimester. One group 2 fetus had a persistent mass associated
with growth deficiency and trisomy 18. The neonatal bowel evaluation was normal
in the remaining 2 fetuses although echogenic findings persisted into the third
trimester. In a low-risk population, echogenic bowel usually resolves without
neonatal sequelae. Even when persistent into the third trimester, echogenic
bowel does not uniformly herald an abnormal outcome. Echogenic bowel coexistent
with other abnormalities (such as growth deficiency or structural malformations)
may be a comarker for aneuploidy. BACKGROUND: An increased frequency of hyperechogenic bowel on ultrasound has
been reported in fetuses with cystic fibrosis (CF) and trisomy-21. However, the
diagnostic application of this observation has been hampered by the absence of a
means of measuring echogenicity.
METHODS: We devised an ultrasonic grading system in which echogenicity was
quantified by linear gain reduction and comparison with fetal iliac crest. From
7400 second-trimester ultrasound referrals, 145 patients were identified as
having a fetus with abnormally echogenic bowel. They were offered genetic
counselling, parental and (if appropriate) CF carrier testing, and amniocentesis
for karyotype and CF status if parents were informative. Follow-up was to 4
months of age.
FINDINGS: Of 40 fetuses with mild increase in bowel sonodensity (grade 1), none
had CF or aneuploidy. Of 81 patients identified with a moderate increase (grade
2), 2 had trisomy 21 and 2 had CF. And of 24 pregcies with a pronounced
increase (grade 3), 5 had CF and 6 had trisomy-21.
INTERPRETATION: Parental CF carrier testing and amniocentesis to identify
aneuploidy or fetal CF status has a high positive ascertainment rate in fetuses
with echogenic bowel grades 2 and 3. Previous studies cite different possible etiologies for fetal echogenic bowel
(FEB). The purpose of this study was to evaluate the possible etiologies for
second-trimester FEB, and to provide clinical guidelines for evaluation of this
finding. The study included 79 patients diagnosed with FEB in the second
trimester. Fifteen cases (19%) were associated with maternal vaginal bleeding.
Of these, 12 patients underwent amniocentesis, 9 of which had visible blood
products in the amniotic fluid. Seven cases (8.9%) had associated severe
malformation. Seven other cases (8.9%) were noted in multifetal pregcies.
Five fetuses (6.3%) had evidence of bowel obstruction or perforation not
associated with cystic fibrosis (CF). Chromosomal aberrations were found in 5
fetuses (6.3%). Intrauterine infection with cytomegalovirus, herpes simplex
virus, varicella-zoster virus, or parvovirus B-19 was documented in 5 patients
(6.3%). Three cases (3.8%) were associated with subsequent unexplained
stillbirth. Two fetuses (2.5%) were found to be affected by CF. Finally, in 30
cases (38%), no obvious reason for FEB was found. We conclude that the
evaluation of second-trimester FEB should include targeted ultrasound for
associated malformations, infectious studies, DNA analysis for CF mutations,
amniocentesis for chromosomal analysis and evaluation of the amniotic fluid for
degraded blood products, and an autopsy in cases of stillbirth. Even when no
apparent reason is found, pregcies should be considered at high risk for poor
outcome. Fetal echogenic bowel has been reported as a normal variant in the second
trimester, and has also been associated with an adverse fetal outcome, including
cystic fibrosis (CF), an autosomal recessive genetic disease. Previous studies
have reported that 3.3 to 13.3 per cent of fetuses with echogenic bowel
discovered during the second trimester were affected with CF. Between 1994 and
1998 our laboratory tested 159 cases with echogenic bowel detected during a
routine ultrasound examination. The ethnic/racial background of cases included
Caucasian, African-American, Middle Eastern, Hispanic, Ashkenazi Jewish and
Asian. We identified two CF fetuses (1.3 per cent) and eight fetuses with a
single identifiable CF mutation (5 per cent) within this diverse population.
These data indicated that the risk of CF in a fetus with echogenic bowel in this
population was less than the 3.3 to 13.3 per cent prior risk currently used in
most Bayesian calculations. Furthermore, the results suggested that specific
risks for couples should be calculated using data specific for their ethnic or
racial background. Based on our results, we recommend either amniocentesis for
fetal CF studies or CF carrier screening of both parents when fetal echogenic
bowel is detected as a 1.3 per cent risk of CF is considered high enough to
warrant further testing. OBJECTIVE: Fetal echogenic bowel has been observed in fetuses with meconium
peritonitis, cystic fibrosis, aneuploidy, congenital viral infection and
intrauterine growth restriction. The pathogenesis of echogenic bowel is unknown,
but it may be attributed to bowel ischemia. Fetuses affected by homozygous
alpha-thalassemia-1 are severely anemic and hypoxic. We investigated the
incidence of echogenic bowel in these hypoxic fetuses in the first and second
trimesters.
DESIGN: Prospective observational study.
SUBJECTS: Women referred for the prenatal diagnosis of homozygous
alpha-thalassemia-1 before 24 weeks' gestation.
METHODS: All subjects had one or more abdominal and/or vaginal ultrasound
examination between 12 and 24 weeks' gestation. Echogenic bowel was diagnosed if
the bowel appeared either isoechogenic or more echogenic than the bone.
RESULTS: Between March 1997 and July 1998, 126 pregcies were studied.
Thirty-six fetuses were confirmed to be affected by homozygous
alpha-thalassemia-1, and 11 of them (31%, 95% CI 16-48%) had echogenic bowel.
These observations were made before the invasive test results were available.
None of the fetuses unaffected by homozygous alpha-thalassemia-1 had echogenic
bowel.
CONCLUSION: There is a strong association between homozygous alpha-thalassemia-1
and echogenic bowel. The pathogenesis is unknown. Speculations include bowel
hypoperistalsis or bowel wall edema due to severe anemia and hypoxia. OBJECTIVE: To assess the relationship between intra-amniotic bleeding and fetal
echogenic bowel.
METHODS: Comprehensive fetal ultrasound examinations were done before and 12
hours after fetal transfusions. Follow-up ultrasound examinations were done
weekly in 28 fetuses with intra-amniotic bleeding. Hyperechogenic bowel was
diagnosed when the echogenicity of fetal bowel was similar to that of bone.
Postpuncture bleeding was identified when a stream of echogenic material from
the cord into the amniotic space was seen, lasting at least 60 seconds.
RESULTS: None of the fetuses had echogenic bowel before initial transfusions.
Intra-amniotic bleeding was followed by bowel echogenicity in seven of 28
fetuses within the first 12 hours after bleeding episodes. Echogenic bowel
remained in five fetuses 2 weeks after the bleeding episodes. In three fetuses,
echogenic bowel was still seen 4 weeks later.
CONCLUSION: Intra-amniotic bleeding can lead to echogenic bowel. 1. Ultrasound Obstet Gynecol. 2000 Nov;16(6):510-4. doi:
10.1046/j.1469-0705.2000.00322.x. OBJECTIVE: The purpose of this study was to determine the incidence of cystic
fibrosis, aneuploidy, and intrauterine infection with toxoplasmosis and
cytomegalovirus in second-trimester fetuses with the sonographic finding of
echogenic bowel.
STUDY DESIGN: All cases of echogenic bowel that were diagnosed in our ultrasound
unit from 1993 to 2000 were identified. Only cases in which bowel echogenicity
was as bright as bone with no associated major fetal anomalies were included.
Patients who were referred from other hospitals were excluded. Echogenicity was
classified as focal or multifocal. Fetal karyotypes, cystic fibrosis carrier
testing, and maternal serologic test results were determined.
RESULTS: One hundred seventy-five fetuses in 171 pregcies met inclusion
criteria. Cystic fibrosis mutations were identified in 7 of 138 mothers (5%) and
9 of 86 fathers (10.5%) who were tested. Five fetuses were affected with cystic
fibrosis. Fetal karyotype was obtained in 139 cases, and autosomal trisomy was
diagnosed in 5 cases (3.6%). One hundred sixty-six patients were tested for
toxoplasmosis, and 111 patients were tested for cytomegalovirus. There were no
cases of congenital toxoplasmosis. There was maternal serologic and fetal
pathologic evidence of cytomegalovirus infection in 1 case. In all cases of
cystic fibrosis and aneuploidy, echogenicity was multifocal; in the case of
cytomegalovirus, echogenicity was focal.
CONCLUSION: In our population, mid-trimester fetal echogenic bowel was
associated with a high prevalence of cystic fibrosis, aneuploidy, and
cytomegalovirus (11/175 fetuses [6.3%]). This information should be considered
when counseling patients after mid-trimester echogenic bowel is diagnosed. OBJECTIVE: The objective was to evaluate the incidence of gastrointestinal
abnormalities amongst those fetuses with antenatally diagnosed echogenic bowel
(EB).
MATERIALS AND METHODS: A retrospective review of all cases delivered from April
2002 to March 2003 with antenatally diagnosed EB was conducted. This was defined
as bowel that appeared as echogenic as (if not greater than) the iliac bone on a
real-time image. The postnatal outcomes with regard to gastrointestinal
abnormalities, till their discharge, were noted.
RESULTS: Of the 13,941 patients delivered, there were 70 cases with antenatally
diagnosed EB, giving an incidence of 70/13,941 or 0.50%. Of these, 6 defaulted
follow-up and 1 had a mid-trimester termination of pregcy at 21 weeks'
gestation for social reasons. Of the remaining 63 cases with EB, 2 were
stillbirths at 31 weeks and 35 weeks of gestation, respectively. Three fetuses
(3/63 or 4.76%) were diagnosed with gastrointestinal abnormalities. Meconium
plug syndrome was diagnosed postnatally in 2 cases, of which, 1 resolved with
conservative management while the other required an emergency laparotomy.
Intestinal atresia was diagnosed in the postmortem of one of the stillbirths.
There was evidence of intrauterine growth retardation (IUGR) in both the
stillbirth and the fetus that had required laparotomy. None of the 3 fetuses
exhibited clinical features of aneuploidy.
CONCLUSION: As the quoted background risk for gastrointestinal pathology is
0.23%, an increased incidence (4.76%) is observed in those fetuses found to have
antenatal EB. It is possible that the presence of IUGR is associated with a
worse prognosis. Further prospective studies are needed to verify this
association. Author information:
(1)Department of Obstetrics and Gynecology, Sahlgrenska University Hospital,
Göteborg, Sweden. [email protected] Echogenic bowel is diagnosed in 0.2% to 1.4% of second trimester
ultrasonographic examinations. This finding occurs as a normal variant in the
second trimester but also has been associated with several pathologic conditions
that include cystic fibrosis, chromosomal abnormalities and in utero infection
with cytomegalovirus and toxoplasmosis. Ultrasound assessment of echogenic bowel
is usually subjective by comparing the echogenicity with adjacent bone or liver.
The diagnosis of fetal echogenic bowel in the second trimester has significant
implications for prenatal management. Fetal echogenic bowel should be considered
an important marker of placental damage. This finding in the second trimester is
strongly associated with adverse pregcy outcome due to utero-placental
insufficiency, particularly in women with elevated maternal serum
alpha-fetoprotein concentration due to severe feto-maternal bleeding. This
review focuses on the definition and diagnosis of this entity and problems
raised by echogenic bowel due to subjectivity of the diagnosis. It also includes
the pathophysiology in the different conditions and the prevalence of each
condition. Based on this review, we suggest the evaluation that is needed, as
well as the recommendations to follow-up, during the remaining term of pregcy
according to the literature. We describe some fetal ultrasound findings associated with intrauterine
cytomegalovirus (CMV) infection. We report a 38-year-old gravida 3, para 2 at 16
weeks of gestation who underwent ultrasound examination for anomaly screening.
The scan revealed an extensive irregular echogenic area in the fetal brain,
especially at the level of lateral ventricles, suggestive of intraventricular
and cerebral hemorrhage. Cardiomegaly, hepatomegaly, and mild ascites as well as
an echogenic bowel were demonstrated. Abnormal chromosomes and hemoglobin Bart
disease were excluded by analysis of fetal blood. Follow-up ultrasound at 20
weeks of gestation showed frank hydrops fetalis, and termination of the
pregcy was performed based on the couple's decision, giving stillbirth to a
male fetus weighing 450 g. Autopsy findings showed intracerebral hemorrhage
(right cerebral hemisphere) and hydrops fetalis with hepatosplenomegaly.
Microscopic investigation showed typical changes of CMV infection in several
organs, including brain, thyroid gland, lung, liver, kidney, heart, pancreas,
and placenta. Sonographically, the combination of hydrops fetalis, cerebral
hemorrhage, and hyperechoic bowel should raise the possibility of a CMV
infection, particularly in cases with no obvious cause of hydrops fetalis. OBJECTIVE: To investigate the association between fetal echogenic bowel (FEB)
during the second trimester and perinatal outcome.
METHODS: A retrospective chart review of FEB during the second trimester over 3
years.
RESULTS: A total of 56 women were identified of 9067 screened (0.6%) women.
Forty-seven agreed to genetic counseling (84%). Of those, 22 (39%) agreed to an
amniocentesis. There were three cases of trisomy 21, one case of trisomy 18 and
one case of fetal CMV infection. Twelve fetuses had an adverse outcome (21%),
with only three of them having an echogenic bowel as the only finding.
CONCLUSIONS: In our study, almost 80% of the fetuses had an uncomplicated
perinatal outcome. FEB was present as the only finding in only 5% of the fetuses
with an adverse outcome. A potential association with placental abnormalities
and a low prevalence of viral infections was observed. These findings may be of
use in counseling parents. OBJECTIVE: To investigate perinatal outcomes of fetal echogenic bowel (FEB).
METHOD: This is a retrospective observational study of FEB cases from Jan
2005-Dec 2010. Data from ultrasound and fetal medicine investigations, uterine
artery Doppler (UAD), intra-partum care and neonatal outcome were obtained from
Fetal Medicine, Obstetric and Neonatal Databases.
RESULTS: There were 139 cases presenting at 21(+5) (15(+1) -35(+5) ) weeks
gestation. Overall, 106/139 (76.2%) were live born (LB), 8/139 (5.8%) were
complicated by intra-uterine deaths (IUD), 11/139 (7.9%) had termination of
pregcy (TOP) and 14/139 (10.1%) were lost to follow-up after 28 weeks
gestation. Six had chromosomal/genetic abnormalities, two had congenital
cytomegalovirus, none had cystic fibrosis.Uterine artery Doppler was normal in
106/130 (81.5%) cases. In this group, there were no cases of fetal growth
restriction (FGR), 95/106 (89.6%) were LB, 1/106 (0.94%) had an IUD. In the
abnormal UAD group, 17/24 (70.1%) developed FGR, 11/24 (45.8%) were LB, 4/24
(16.7%) had TOP, 7/24 (29.2%) had IUD.In total, 20/106 (18.9%) live births were
admitted for specialist neonatal care, 12/20 (60%) for prematurity. Only one had
primary bowel pathology.
CONCLUSION: Pregcies with FEB and screen positive UAD are at risk of adverse
perinatal outcome. Primary bowel pathology is rare following the finding of FEB. OBJECTIVE: Fetal echogenic bowel (FEB) is a soft marker found on second
trimester sonography. Our main aim was to determine the outcome of infants who
presented with FEB and secondarily to identify additional sonographic findings
that might have clinical relevance for the prognosis.
DESIGN: We reviewed all pregcies in which the diagnosis FEB was made in our
Fetal Medicine Unit during 2009-2010 (N=121). We divided all cases into five
groups according to additional sonographic findings. Group 1 consisted of cases
of isolated FEB, group 2 of FEB associated with dilated bowels, group 3 of FEB
with one or two other soft markers, group 4 of FEB with major congenital
anomalies or three or more other soft markers, and group 5 consisted of FEB with
isolated intrauterine growth restriction (IUGR).
RESULTS: Of 121 cases, five were lost to follow-up. Of the remaining 116 cases,
48 (41.4%) were assigned to group 1, 15 (12.9%) to group 2, 15 (12.9%) to group
3, 27 (23.2%) to group 4, and 11 (9.5%) to group 5. The outcome for group 1 was
uneventful. In group 2 and 3, two anomalies, anorectal malformation and cystic
fibrosis, were detected postnatally (6.7%). In group 4, mortality and morbidity
were high (78% resp. 22%). Group 5 also had high mortality (82%) and major
morbidity (18%).
CONCLUSIONS: If FEB occurs in isolation, it is a benign condition carrying a
favourable prognosis. If multiple additional anomalies or early IUGR are
observed, the prognosis tends to be less favourable to extremely poor. |
How does trimetazidine affect intracellular kinase signaling in the heart? | Trimetazidine activates AMPK in diabetic myocardium. Trimetazidine when administered before reperfusion results in activation of p38 mitogen-activated protein kinase and Akt signaling. Trimetazidine when administered during reperfusion does not affect p38MAPK and JNK activation. | The present study investigated the tolerance of the isolated rat heart to
ischemia-reperfusion after administration of trimetazidine (TMZ) at different
experimental phases, as well as the possible involvement of p38 MAPK and JNKs in
this response. Isolated rat hearts were perfused in Langendorff mode. Untreated
hearts after stabilization (S) were subjected to 20 min of zero-flow global
ischemia (I) and 45 min of reperfusion (R), (NORM), n = 9. TMZ (10(-5) M) was
administered (in the perfusate): a) only at S phase, (TMZ-STAB), n = 8, b) only
at R, (TMZ-REP), n = 8 and c) during both S and R, (TMZ-STAB+REP), n = 8.
Recovery of left ventricular developed pressure at 45 min of R (Rec) was
significantly higher in TMZ-STAB and TMZ-STAB+REP and LDH release was lower in
TMZ-STAB+REP and TMZ-STAB than NORM, [1153.2 (121.0) and 1152.1 (86.8) vs 1573.5
(138.2), P < 0.05]. TMZ induced cardioprotection did not involve p38 MAPK and
JNKs. Phospho-p38 MAPK and JNKs levels after I/R were not changed with TMZ
treatment. In TMZ-REP, Rec and LDH release were similar to NORM, but the rate of
functional recovery (ratio of Rec at 10 min of R to Rec) was 86.7% (13.3) for
TMZ-REP vs 53.8% (7.7) for NORM, P < 0.05. This effect was associated with
decreased myocardial lactate content early at reperfusion. In conclusion,
preischemic administration of TMZ protects against I/R injury while TMZ given
only at reperfusion accelerates recovery of function without reducing the extent
of injury. BACKGROUND: Trimetazidine is an anti-ischemic agent with cardioprotective
effects. The purpose of this double-blind, controlled, prospective randomized
study was to investigate the possible effects of the preoperative use of
trimetazidine on the biochemical markers of myocardial injury during open heart
surgery and to determine if it has any myocardial protective effects.
METHODS: Thirty patients undergoing coronary artery bypass grafting surgery,
received either trimetazidine (study group, n = 15) or not (control group, n =
15). Pretreatment began 2 weeks before the operation with trimetazidine (60
mg/day orally), and the control group received no medication. We measured the
levels of serum creatine kinase (CK), CK isoenzyme MB (CK-MB), myoglobin, and
troponin T in venous blood samples obtained before and after the operation to
evaluate the effect of this drug against myocardial damage. We also took serial
blood samples from the radial artery and the coronary sinus before the
institution of cardiopulmonary bypass (CPB) and at 2 and 15 minutes after the
removal of the cross-clamp to measure lactate levels and calculate the lactate
extraction of the myocardium.
RESULTS: Postoperative levels of myoglobin, troponin T, CK, and CK-MB were
significantly lower in the trimetazidine group than in the control group (P <
.05). There was also a significant difference in the values for the lactate
extraction calculation between the groups at minute 2 after the removal of the
cross-clamp (P < .05).
CONCLUSION: We conclude that pretreatment with trimetazidine has some beneficial
effects in protecting the myocardium and decreasing myocardial injury during the
cardioplegic arrest period in open heart surgery without affecting postoperative
hemodynamics. AIM: To investigate the influence of trimetazidine, which is known to be an
antioxidant and modulator of metabolism, on cardiac function and the development
of diabetic cardiomyopathy in db/db mouse.
METHODS: Trimetazidine was administered to db/db mice for eight weeks. Cardiac
function was measured by inserting a Millar catheter into the left ventricle,
and oxidative stress and AMP-activated protein kinase (AMPK) activity in the
myocardium were evaluated.
RESULTS: Untreated db/db mice exhibited a significant decrease in cardiac
function compared to normal C57 mice. Oxidative stress and lipid deposition were
markedly increased in the myocardium, concomitant with inactivation of AMPK and
increased expression of peroxisome proliferator-activated receptor coactivator-1
alpha (PGC-1 alpha). Trimetazidine significantly improved systolic and diastolic
function in hearts of db/db mice and led to reduced production of reactive
oxygen species and deposition of fatty acid in cardiomyocytes. Trimetazidine
also caused AMPK activation and reduced PGC-1 alpha expression in the hearts of
db/db mice.
CONCLUSION: The data suggest that trimetazidine significantly improves cardiac
function in db/db mice by attenuating lipotoxicity and improving the oxidation
status of the heart. Activation of AMPK and decreased expression of PGC-1 alpha
were involved in this process. Furthermore, our study suggests that
trimetazidine suppresses the development of diabetic cardiomyopathy, which
warrants further clinical investigation. |
Which is the enzymatic activity of the myotubularin family of proteins? | The myotubularin family of proteins are lipid inositol phosphatases | The myotubularin-related genes define a large family of eukaryotic proteins,
most of them initially characterized by the presence of a ten-amino acid
consensus sequence related to the active sites of tyrosine phosphatases,
dual-specificity protein phosphatases and the lipid phosphatase PTEN.
Myotubularin (hMTM1), the founder member, is mutated in myotubular myopathy, and
a close homolog (hMTMR2) was recently found mutated in a recessive form of
Charcot-Marie-Tooth neuropathy. Although myotubularin was thought to be a
dual-specificity protein phosphatase, recent results indicate that it is
primarily a lipid phosphatase, acting on phosphatidylinositol 3-monophosphate,
and might be involved in the regulation of phosphatidylinositol 3-kinase (PI
3-kinase) pathway and membrane trafficking. Myotubularin is the archetype of a family of highly conserved protein-tyrosine
phosphatase-like enzymes. The myotubularin gene, MTM1, is mutated in the genetic
disorder, X-linked myotubular myopathy. We and others have previously shown that
myotubularin utilizes the lipid second messenger, phosphatidylinositol
3-phosphate (PI(3)P), as a physiologic substrate. We demonstrate here that the
myotubularin-related protein MTMR2, which is mutated in the neurodegenerative
disorder, type 4B Charcot-Marie-Tooth disease, is also highly specific for
PI(3)P as a substrate. Furthermore, the MTM-related phosphatases MTMR1, MTMR3,
and MTMR6 also dephosphorylate PI(3)P, suggesting that activity toward this
substrate is common to all myotubularin family enzymes. A direct comparison of
the lipid phosphatase activities of recombit myotubularin and MTMR2
demonstrates that their enzymatic properties are indistinguishable, indicating
that the lack of functional redundancy between these proteins is likely to be
due to factors other than the utilization of different physiologic substrates.
To this end, we have analyzed myotubularin and MTMR2 transcripts during induced
differentiation of cultured murine C2C12 myoblasts and find that their
expression is divergently regulated. In addition, myotubularin and MTMR2
enhanced green fluorescent protein fusion proteins exhibit overlapping but
distinct patterns of subcellular localization. Finally, we provide evidence that
myotubularin, but not MTMR2, can modulate the levels of endosomal PI(3)P. From
these data, we conclude that the developmental expression and subcellular
localization of myotubularin and MTMR2 are differentially regulated, resulting
in their utilization of specific cellular pools of PI(3)P. Myotubularin-related genes define a novel highly conserved family of eukaryotic
proteins of at least 11 human members. The hMTM1 gene that codes for
myotubularin is mutated in X-linked myotubular myopathy, a severe congenital
disease. Recently, we and others have characterized myotubularin as a potent and
specific phosphatidylinositol 3-phosphate 3-phosphatase. In the present study we
investigated the lipid phosphatase activity and the subcellular localization of
two other members of the family, hMTMR2 protein that is mutated in the
demyelinating neuropathy Charcot-Marie-Tooth type 4B and the FYVE-finger
containing hMTMR3 protein. Our results show that both proteins are potent
phosphatidylinositol 3-phosphate 3-phosphatases either in vitro or in yeast
where they interfered with vesicular trafficking. Their localization is mainly
cytoplasmic, with however strong labeling of Rac-inducible plasma membrane
ruffles. The fact that the ubiquitously expressed hMTM1 and hMTMR2 genes are
involved in different pathologies indicates that despite their shared enzymatic
activity, they are not functionally redundant, at least in certain cell types.
This might be explained by subtle differences in expression and/or in
recruitment and regulation at their specific site of action. Phosphatidylinositol 3-phosphate [PtdIns(3)P] acts as a second messenger via the
recruitment of diverse signalling proteins to various cellular compartments.
Recent advances have highlighted the association of human diseases with
mutations in phosphatases that regulate PtdIns(3)P levels. Myotubularin, the
gene mutated in myotubular myopathy, functions as a lipid phosphatase with
specificity for PtdIns(3)P. It is now apparent that there is an increasing
family of proteins that are defined by their significant homology with
myotubularin. The myotubularin-related gene family includes proteins that
exhibit a lipid phosphatase catalytic motif, those that contain mutations of the
critical catalytic residues, and at least one protein that functions as an
adapter subunit for PtdIns(3)P-3-phosphatase activity. The present challenge is
to understand how deregulation of phosphoinositide metabolism causes human
disease. Myotubularin, the phosphatase mutated in X-linked myotubular myopathy, was shown
to dephosphorylate phosphatidylinositol 3-monophosphate (PtdIns3P) and was also
reported to interact with nuclear transcriptional regulators from the trithorax
family. We have characterized a panel of specific antibodies and investigated
the subcellular localization of myotubularin. Myotubularin is not detected in
the nucleus, and localizes mostly as a dense cytoplasmic network. Overexpression
of myotubularin does not detectably affect vesicle trafficking in the mammalian
cells investigated, in contrast to previous observations in yeast models. Both
mutation of a key aspartate residue of myotubularin and domit activation of
Rac1 GTPase lead to the recruitment of myotubularin to specific plasma membrane
domains. Localization to Rac1-induced ruffles is dependent on the presence of a
domain highly conserved in the myotubularin family (that we named RID). We thus
propose that myotubularin may dephosphorylate a subpool of PtdIns3P (or another
related substrate) at the plasma membrane. Phosphoinositides control many different processes required for normal cellular
function. Myotubularins are a family of Phosphatidylinositol 3-phosphate
(PtdIns3P) phosphatases identified by the positional cloning of the MTM1 gene in
patients suffering from X-linked myotubular myopathy and the MTMR2 gene in
patients suffering from the demyelinating neuropathy Charcot-Marie-Tooth disease
type 4B. MTM1 is a phosphatidylinositol phosphatase with reported specificity
toward PtdIns3P, while the related proteins MTMR2 and MTMR3 hydrolyze both
PtdIns3P and PtdIns(3,5)P2. We have investigated MTM1 and MTMR6 and find that
they use PtdIns(3,5)P2 in addition to PtdIns3P as a substrate in vitro. The
product of PtdIns(3,5)P2 hydrolysis, PtdIns5P, causes MTM1 to form a heptameric
ring that is 12.5 nm in diameter, and it is a specific allosteric activator of
MTM1, MTMR3, and MTMR6. A disease-causing mutation at arginine 69 of MTM1
falling within a putative pleckstrin homology domain reduces the ability of the
enzyme to respond to PtdIns5P. We propose that the myotubularin family of
enzymes utilize both PtdIns3P and PtdIns(3,5)P2 as substrates, and that PtdIns5P
functions in a positive feedback loop controlling their activity. These findings
highlight the importance of regulated phosphatase activity for the control of
phosphoinositide metabolism. Myotubularins (MTMs) constitute a large family of lipid phosphatases that
specifically dephosphorylate phosphatidylinositol (3)P. MTM1 and MTM2 are
mutated in X-linked myotubular myopathy and Charcot-Marie-Tooth disease (type
4B), respectively, although the mechanisms whereby MTM dysfunction leads to
these diseases is unknown. To gain insight into MTM function, we undertook the
study of MTMs in the nematode Caenorhabditis elegans, which possesses
representative homologues of the four major subgroups of MTMs identified in
mammals. As in mammals, we found that C. elegans MTMs mediate distinct
functions. let-512 (vps34) encodes the C. elegans homologue of the yeast and
mammalian homologue of the phosphatidylinositol 3-kinase Vps34. We found that
reduction of mtm-6 (F53A2.8) function by RNA inhibition rescued the larval
lethality of let-512 (vps34) mutants and that the reduction of mtm-1 (Y110A7A.5)
activity by RNA inhibition rescued the endocytosis defect of let-512 animals.
Together, these observations provide genetic evidence that MTMs negatively
regulate phosphatidylinositol (3)P levels. Analysis of MTM expression patterns
using transcriptional green fluorescence protein reporters demonstrated that
these two MTMs exhibit mostly non-overlapping expression patterns and that
MTM-green fluorescence protein fusion proteins are localized to different
subcellular locations. These observations suggest that some of the different
functions of MTMs might, in part, be a consequence of unique expression and
localization patterns. However, our finding that at least three C. elegans MTMs
play essential roles in coelomocyte endocytosis, a process that also requires
VPS34, indicates that MTMs do not simply turn off VPS34 but unexpectedly also
function as positive regulators of biological processes. The myotubularin family is a large eukaryotic group within the
tyrosine/dual-specificity phosphatase super-family (PTP/DSP). Among the 14 human
members, three are mutated in genetic diseases: myotubular myopathy and two
forms of Charcot-Marie-Tooth neuropathy. We present an analysis of the
myotubularin family in sequenced genomes. The myotubularin family encompasses
catalytically active and inactive phosphatases, and both classes are well
conserved from nematode to man. Catalytically active myotubularins
dephosphorylate phosphatidylinositol 3-phosphate (PtdIns3P) and PtdIns3,5P2,
leading to the production of PtdIns and PtdIns5P. This activity may be modulated
by direct interaction with catalytically inactive myotubularins. These
phosphoinositides are signaling molecules that are notably involved in vacuolar
transport and membrane trafficking. Myotubularins are thus proposed to be
implicated in these cellular mechanisms, and recent observations on
myotubularins homologues in the nematode Caenorhabditis elegans indicate a role
in endocytosis. Myotubularin-related proteins are a large subfamily of protein tyrosine
phosphatases (PTPs) that dephosphorylate D3-phosphorylated inositol lipids.
Mutations in members of the myotubularin family cause the human neuromuscular
disorders myotubular myopathy and type 4B Charcot-Marie-Tooth syndrome. The
crystal structure of a representative member of this family, MTMR2, reveals a
phosphatase domain that is structurally unique among PTPs. A series of mutants
are described that exhibit altered enzymatic activity and provide insight into
the specificity of myotubularin phosphatases toward phosphoinositide substrates.
The structure also reveals that the GRAM domain, found in myotubularin family
phosphatases and predicted to occur in approximately 180 proteins, is part of a
larger motif with a pleckstrin homology (PH) domain fold. Finally, the MTMR2
structure will serve as a model for other members of the myotubularin family and
provide a framework for understanding the mechanism whereby mutations in these
proteins lead to disease. Charcot-Marie-Tooth disease type 4B (CMT4B) is a severe, demyelinating
peripheral neuropathy characterized by distinctive, focally folded myelin
sheaths. CMT4B is caused by recessively inherited mutations in either
myotubularin-related 2 (MTMR2) or MTMR13 (also called SET-binding factor 2).
MTMR2 encodes a member of the myotubularin family of
phosphoinositide-3-phosphatases, which dephosphorylate phosphatidylinositol
3-phosphate (PI(3)P) and bisphosphate PI(3,5)P2. MTMR13 encodes a large,
uncharacterized member of the myotubularin family. The MTMR13 phosphatase domain
is catalytically inactive because the essential Cys and Arg residues are absent.
Given the genetic association of both MTMR2 and MTMR13 with CMT4B, we
investigated the biochemical relationship between these two proteins. We found
that the endogenous MTMR2 and MTMR13 proteins are associated in human embryonic
kidney 293 cells. MTMR2-MTMR13 association is mediated by coiled-coil sequences
present in each protein. We also examined the cellular localization of MTMR2 and
MTMR13 using fluorescence microscopy and subcellular fractionation. We found
that (i) MTMR13 is a predomitly membrane-associated protein; (ii) MTMR2 and
MTMR13 cofractionate in both a light membrane fraction and a cytosolic fraction;
and (iii) MTMR13 membrane association is mediated by the segment of the protein
which contains the pseudophosphatase domain. This work, which describes the
first cellular or biochemical investigation of the MTMR13 pseudophosphatase
protein, suggests that MTMR13 functions in association with MTMR2. Loss of
MTMR13 function in CMT4B2 patients may lead to alterations in MTMR2 function and
subsequent alterations in 3-phosphoinositide signaling. Such a mechanism would
explain the strikingly similar phenotypes of patients with recessive mutations
in either MTMR2 or MTMR13. The myotubularins (MTMs) constitute a large family of phosphoinositide lipid
3-phosphatases with specificity for PtdIns3P and PtdIns (3,5)P2. Mutations in
MTM proteins are associated with inherited conditions such as myotubular
myopathy and Charcot-Marie-Tooth syndrome. The substrate lipids are known to be
regulators of the endosomal pathway through recruitment of specific effector
proteins. Hydrolysis of PtdIns (3,5)P2 provides a biosynthetic pathway to the
production of PtdIns5P, which itself can allosterically activate MTMs. We review
the properties of this intriguing family of proteins and discuss potential
physiological functions that include regulation of the endocytic pathway. The human neuromuscular diseases X-linked myotubular myopathy and
Charcot-Marie-Tooth disease type 4B are caused by mutations in myotubularin
family proteins. The myotubularins are a unique subfamily of protein tyrosine
phosphatases that utilize inositol phospholipids, rather than phosphoproteins,
as substrates. Recent structural studies, including the first crystal structure
of a myotubularin family protein, have defined the structural features that are
characteristic of the family and revealed the molecular basis of their unique
substrate specificity. Interestingly, the myotubularin family contains a
subgroup of proteins that are catalytically inactive. Recent biochemical studies
have established that the inactive myotubularins function as adaptors for the
active members and play an important regulatory role within the family. Myotubularins, a large family of catalytically active and inactive proteins,
belong to a unique subgroup of protein tyrosine phosphatases that use inositol
phospholipids, rather than phosphoproteins, as physiological substrates. Here,
by integrating crystallographic and deuterium-exchange mass spectrometry studies
of human myotubularin-related protein-2 (MTMR2) in complex with
phosphoinositides, we define the molecular basis for this unique substrate
specificity. Phosphoinositide substrates bind in a pocket located on a
positively charged face of the protein, suggesting an electrostatic mechanism
for membrane targeting. A flexible, hydrophobic helix makes extensive
interactions with the diacylglycerol moieties of substrates, explaining the
specificity for membrane-bound phosphoinositides. An extensive H-bonding network
and charge-charge interactions within the active site pocket determine
phosphoinositide headgroup specificity. The conservation of these specificity
determits within the active, but not the inactive, myotubularins provides
insight into the functional differences between the active and inactive members. The myotubularins are a large family of lipid phosphatases with specificity
towards PtdIns3P and PtdIns(3,5)P(2). Each of the 14 family members bears a
signature phosphatase domain, which is inactive in six cases due to amino acid
changes at the catalytic site. Fragmentary data have indicated heteromeric
interactions between myotubularins, which have hitherto paired an active family
member with an inactive one. In this study we have conducted a largescale
analysis of potential associations within the human myotubularin family, through
directed two-hybrid screening and immunoprecipitation of epitope-tagged
proteins. We have confirmed all previously reported combinations and identified
novel heteromeric interactions: MTMR8 with MTMR9, and MTMR3 with MTMR4, the
first such combination of enzymatically active MTMs. We also report the capacity
of several family members to self-associate, including MTMR3 and MTMR4.
Subcellular localisation studies reveal a unique distribution of MTMR4 to
endosomal structures, the major site of substrate lipid accumulation. All active
MTMs we have tested (MTM1, MTMR2-MTMR4) reduce endosomal PtdIns3P levels upon
overexpression. Despite this, only MTMR4 exerts any effect on EGF receptor
trafficking and degradation, which is more pronounced with a phosphatase
inactive form of MTMR4 and requires an intact FYVE domain. In eukaryotic cells, phosphatidylinositol is subject to differential
phosphorylation, resulting in the production of seven distinct
phosphatidylinositol phosphates, often referred to as phosphoinositides (PIs).
PIs have numerous distinct roles in cellular regulation and membrane
trafficking. Recently, myotubularin family PI 3-phosphatases have emerged as key
regulators of phosphatidylinositol 3-phosphate and phosphatidylinositol
3,5-bisphosphate, two PIs that regulate traffic within the endosomal-lysosomal
pathway. Mutations in several myotubularin genes lead to myotubular myopathy and
Charcot-Marie-Tooth peripheral neuropathy. Strikingly, nearly half of the
members of the human myotubularin family appear to be catalytically inactive.
Several inactive myotubularins have essential functions in mammals. Recent work
in mammalian cells and model organisms is shedding light on the roles of
myotubularins in membrane traffic. Myotubularins (MTM) are a large subfamily of lipid phosphatases that
specifically dephosphorylate at the D3 position of phosphatidylinositol
3-phosphate (PI(3)P) in PI(3)P and PI(3,5)P2. We recently found that MTMR6
specifically inhibits the Ca2+-activated K+ channel, KCa3.1, by
dephosphorylating PI(3)P. We now show that inhibition is specific for MTMR6 and
other MTMs do not inhibit KCa3.1. By replacing either or both of the coiled-coil
(CC) and pleckstrin homology/GRAM (PH/G) domains of MTMs that failed to inhibit
KCa3.1 with the CC and PH/G domains of MTMR6, we found that chimeric MTMs
containing both the MTMR6 CC and PH/G domains functioned like MTMR6 to inhibit
KCa3.1 channel activity, whereas chimeric MTMs containing either domain alone
did not. Immunofluorescent microscopy demonstrated that both the MTMR6 CC and
PH/G domains are required to co-localize MTMR6 to the plasma membrane with
KCa3.1. These findings support a model in which two specific low affinity
interactions are required to co-localize MTMR6 with KCa3.1: 1) between the CC
domains on MTMR6 and KCa3.1 and (2) between the PH/G domain and a component of
the plasma membrane. Our inability to detect significant interaction of the
MTMR6 G/PH domain with phosphoinositides suggests that this domain may bind a
protein. Identifying the specific binding partners of the CC and PH/G domains on
other MTMs will provide important clues to the specific functions regulated by
other MTMs as well as the mechanism(s) whereby loss of some MTMs lead to
disease. The Protein Tyrosine Phosphatase (PTP) family comprises a large and diverse
group of enzymes, regulating a range of biological processes through
de-phosphorylation of many proteins and lipids. These enzymes share a catalytic
mechanism that requires a reduced and reactive cysteine nucleophile, making them
potentially sensitive to inactivation and regulation by oxidation. Analysis of
ten PTPs identified substantial differences in the sensitivity of these enzymes
to oxidation in vitro. More detailed experiments confirmed the following rank
order of sensitivity: PTEN and Sac1>PTPL1/FAP-1>>myotubularins. When the
apparent sensitivity to oxidation of these PTPs in cells treated with hydrogen
peroxide was analysed, this correlated well with the observed sensitivities to
oxidation in vitro. These data suggested that different PTPs may fall into at
least three different classes with respect to mechanisms of cellular redox
regulation. 1. PTEN and Sac1 were readily and reversibly oxidised in vitro and
in cells treated with hydrogen peroxide 2. PTPL1 appeared to be resistant to
oxidation in cells, correlating with its sensitivity to reduction by glutathione
in vitro 3. The myotubularin family of lipid phosphatases was almost completely
resistant to oxidation in vitro and in cells. Our results show that sensitivity
to reversible oxidation is not a necessary characteristic of the PTPs and imply
that such sensitivity has evolved as a regulatory mechanism for some of this
large family, but not others. BACKGROUND: It has been shown that mutations in at least four myotubularin
family genes (MTM1, MTMR1, 2 and 13) are causative for human neuromuscular
disorders. However, the pathway and regulative mechanism remain unknown.
METHODOLOGY/PRINCIPAL FINDINGS: Here, we reported a new role for Mtmr8 in
neuromuscular development of zebrafish. Firstly, we cloned and characterized
zebrafish Mtmr8, and revealed the expression pattern predomitly in the eye
field and somites during early somitogenesis. Using morpholino knockdown, then,
we observed that loss-of-function of Mtmr8 led to defects in somitogenesis.
Subsequently, the possible underlying mechanism and signal pathway were
examined. We first checked the Akt phosphorylation, and observed an increase of
Akt phosphorylation in the morphant embryos. Furthermore, we studied the PH/G
domain function within Mtmr8. Although the PH/G domain deletion by itself did
not result in embryonic defect, addition of PI3K inhibitor LY294002 did give a
defective phenotype in the PH/G deletion morphants, indicating that the PH/G
domain was essential for Mtmr8's function. Moreover, we investigated the
cooperation of Mtmr8 with PI3K in actin filament modeling and muscle
development, and found that both Mtmr8-MO1 and Mtmr8-MO2+LY294002 led to the
disorganization of the actin cytoskeleton. In addition, we revealed a possible
participation of Mtmr8 in the Hedgehog pathway, and cell transplantation
experiments showed that Mtmr8 worked in a non-cell autonomous manner in actin
modeling.
CONCLUSION/SIGNIFICANCE: The above data indicate that a conserved functional
cooperation of Mtmr8 with PI3K regulates actin filament modeling and muscle
development in zebrafish, and reveal a possible participation of Mtmr8 in the
Hedgehog pathway. Therefore, this work provides a new clue to study the
physiological function of MTM family members. Autophagy initiation is strictly dependent on phosphatidylinositol 3-phosphate
(PI3P) synthesis. PI3P production is under tight control of PI3Kinase, hVps34,
in complex with Beclin-1. Mammalian cells express several PI3P phosphatases that
belong to the myotubularin family. Even though some of them have been linked to
serious human diseases, their cellular function is largely unknown. Two recent
studies indicate that PI3P metabolism involved in autophagy initiation is
further regulated by the PI3P phosphatases Jumpy and MTMR3. Additional pools of
PI3P, upstream of mTOR and on the endocytic pathway, may modulate autophagy
indirectly, suggesting that other PI3P phosphatases might be involved in this
process. This review sums up our knowledge on PI3P phosphatases and discusses
the recent progress on their role in autophagy. Phosphatidylinositol 3-phosphate [PtdIns(3)P] regulates endocytic trafficking
and the sorting of receptors through early endosomes, including the rapid
recycling of transferrin (Tfn). However, the phosphoinositide phosphatase that
selectively opposes this function is unknown. The myotubularins are a family of
eight catalytically active and six inactive enzymes that hydrolyse PtdIns(3)P to
form PtdIns. However, the role each myotubularin family member plays in
regulating endosomal PtdIns(3)P and thereby endocytic trafficking is not well
established. Here, we identify the myotubularin family member MTMR4, which
localizes to early endosomes and also to Rab11- and Sec15-positive recycling
endosomes. In cells with MTMR4 knockdown, or following expression of the
catalytically inactive MTMR4, MTMR4(C407A), the number of PtdIns(3)P-decorated
endosomes significantly increased. MTMR4 overexpression delayed the exit of Tfn
from early endosomes and its recycling to the plasma membrane. By contrast,
expression of MTMR4(C407A), which acts as a domit-negative construct,
significantly accelerated Tfn recycling. However, in MTMR4 knockdown cells Tfn
recycling was unchanged, suggesting that other MTMs might also contribute to
recycling. MTMR4 regulated the subcellular distribution of Rab11 and, in cells
with RNAi-mediated knockdown of MTMR4, Rab11 was directed away from the
pericentriolar recycling compartment. The subcellular distribution of VAMP3, a
v-SNARE protein that resides in recycling endosomes and endosome-derived
transport vesicles, was also regulated by MTMR4. Therefore, MTMR4 localizes at
the interface of early and recycling endosomes to regulate trafficking through
this pathway. The MTM (myotubularin)/MTMR (myotubularin-related) protein family is comprised
of 15 lipid phosphatases, of which nine members are catalytically active. MTMs
are known to play a fundamental role in human physiology as gene mutations can
give rise to X-linked myotubular myopathy or Charcot-Marie-Tooth disease, which
manifest in skeletal muscle or in peripheral neurons respectively.
Interestingly, studies have shown MTMR2 and MTMR5, two MTM family members, to be
highly expressed in the testis, particularly in Sertoli and germ cells, and
knockout of either gene resulted in spermatogenic defects. Other studies have
shown that MTMR2 functions in endocytosis and membrane trafficking. In the
testis, MTMR2 interacts and co-localizes with c-Src/phospho-Src-(Tyr⁴¹⁶), a
non-receptor protein tyrosine kinase that regulates the phosphorylation state of
proteins at the apical ES (ectoplasmic specialization), a unique type of cell
junction found between Sertoli cells and elongating/elongated spermatids. In the
present review, we highlight recent findings that have made a significant impact
on our understanding of this protein family in normal cell function and in
disease, with the emphasis on the role of MTMs and MTMRs in spermatogenesis. We
also describe a working model to explain how MTMR2 interacts with other proteins
such as c-Src, dynamin 2, EPS8 (growth factor receptor pathway substrate 8) and
ARP2/3 (actin-related protein 2/3) at the apical ES and the apical TBC
(tubulobulbar complex; tubular-like invaginations that function in the
disassembly of the apical ES and in the recycling of its components) to regulate
spermiation at late stage VIII of the seminiferous epithelial cycle. MTMR2 is a member of the myotubularin family of inositol lipid phosphatases, a
large protein-tyrosine phosphatase subgroup that is conserved from yeast to
humans. Furthermore, the peripheral neuromuscular disease Charcot-Marie Tooth
disease type 4B has been attributed to mutations in the mtmr2 gene. Because the
molecular mechanisms regulating MTMR2 have been poorly defined, we investigated
whether reversible phosphorylation might regulate MTMR2 function. We used mass
spectrometry-based methods to identify a high stoichiometry phosphorylation site
on serine 58 of MTMR2. Phosphorylation at Ser(58), or a phosphomimetic S58E
mutation, markedly decreased MTMR2 localization to endocytic vesicular
structures. In contrast, a phosphorylation-deficient MTMR2 mutant (S58A)
displayed constitutive localization to early endocytic structures. This
localization pattern was accompanied by displacement of a PI(3)P-specific sensor
protein and an increase in signal transduction pathways. Thus, MTMR2
phosphorylation is likely to be a critical mechanism by which MTMR2 access to
its lipid substrate(s) is temporally and spatially regulated, thereby
contributing to the control of downstream endosome maturation events. Myotubularin related protein 2 (MTMR2) is a member of the myotubularin family of
phosphoinositide lipid phosphatases. Although MTMR2 dephosphorylates the
phosphoinositides PI(3)P and PI(3,5)P2, the phosphoinositide binding proteins
that are regulated by MTMR2 are poorly characterized. In this study,
phosphoinositide affinity chromatography coupled to mass spectrometry identified
receptor mediated endocytosis 8 (RME-8) as a novel PI(3)P binding protein. RME-8
co-localized with the PI(3)P marker DsRed-FYVE, while the N-terminal region of
RME-8 is required for PI(3)P and PI(3,5)P(2) binding in vitro. Depletion of
PI(3)P by MTMR2 S58A or wortmannin treatment attenuated RME-8 endosomal
localization and co-localization with EGFR on early endosomes. Our results
suggest a model in which the localization of RME-8 to endosomal compartments is
spatially mediated by PI(3)P binding and temporally regulated by MTMR2 activity. The myotubularin family of phosphoinositide phosphatases includes several
members mutated in neuromuscular diseases or associated with metabolic syndrome,
obesity, and cancer. Catalytically dead phosphatases regulate their active
homologs by heterodimerization and potentially represent key players in the
phosphatase-kinase balance. Although the enzymatic specificity for
phosphoinositides indicates a role for myotubularins in endocytosis and membrane
trafficking, recent findings in cellular and animal models suggest that
myotubularins regulate additional processes including cell proliferation and
differentiation, autophagy, cytokinesis, and cytoskeletal and cell junction
dynamics. In this review, we discuss how myotubularins regulate such diverse
processes, emphasizing newly identified functions in a physiological and
pathological context. A better understanding of myotubularin pathophysiology
will pave the way towards therapeutic strategies. The level and turnover of phosphoinositides (PIs) are tightly controlled by a
large set of PI-specific enzymes (PI kinases and phosphatases). Mammalian PI
phosphatases are conserved through evolution and among this large family the
dual-specificity phosphatase (PTP/DSP) are metal-independent enzymes displaying
the amino acid signature Cys-X5-Arg-Thr/Ser (CX5RT/S) in their active site. Such
catalytic site characterizes the myotubularin 3-phosphatases that
dephosphorylate PtdIns3P and PtdIns(3,5)P₂ and produce PtdIns5P. Substrates of
myotubularins have been implicated in endocytosis and membrane trafficking while
PtdIns5P may have a role in signal transduction. As a paradox, 6 of the 14
members of the myotubularin family lack enzymatic activity and are considered as
dead phosphatases. Several myotubularins have been genetically linked to human
diseases: MTM1 is mutated in the congenital myopathy X-linked centronuclear or
myotubular myopathy (XLCNM) and MTMR14 (JUMPY) has been linked to an autosomal
form of such disease, while MTMR2 and MTMR13 are mutated in Charcot-Marie-Tooth
(CMT) neuropathies. Furthermore, recent evidences from genetic association
studies revealed that several other myotubularins could be associated to chronic
disorders such as cancer and obesity, highlighting their importance for human
health. Here, we discuss cellular and physiological roles of myotubularins and
their implication in human diseases, and we present potential pathological
mechanisms affecting specific tissues in myotubularin-associated diseases. BACKGROUND: Autophagy is a ubiquitous cellular process responsible for the bulk
degradation of cytoplasmic components through the autophagosomal-lysosomal
pathway. In skeletal muscle, autophagy has been regarded as a key regulator for
muscle mass maintece, and its imbalance leads to sarcopenia. However, the
underlying mechanism is poorly understood.
RESULTS: In this study, we demonstrate that ceMTM3, a FYVE-domain containing
myotubalarin family phosphatase, is required for the maintece of muscle
fibers by preventing excessive autophagy in Caenorhabditis elegans. Knockdown of
ceMTM3 by using feeding-based RNA interference caused loss of muscle fibers
accompanied by shortening of muscle cell and body size in aged C. elegans worms.
This was preceded by the occurrence of excessive autophagy in the muscle and
other tissues, which subsequently resulted in increased lysosomal activity and
necrotic cell death. However, knockdown of ceMTM3 did not aggravate the
abnormalities of muscle wasting in autophagy-deficient atg-18 mutant worms.
CONCLUSIONS: Our data suggest an important role of ceMTM3 in regulating
autophagy and maintaining muscle fibers. This study may have clinical
implications for prevention and treatment of sarcopenia. Phosphatidylinositol (PtdIns) is a membrane phospholipid composed of
diacylglycerol and a D-myo-inositol head group. In mammals, the hydroxyl groups
at the D3, D4 and D5 positions of the inositol ring can be phosphorylated to
yield seven phosphoinositide derivatives. PtdIns-3,5-bisphosphate
[PtdIns(3,5)P2] is the most recently discovered species of phosphoinositide that
is generated by the phosphorylation of PtdIns(3)P at the D5 position by PtdIns
phosphate kinase and catabolized through the dephosphorylation by myotubularin
family of phosphatases. Genetic and biochemical analyses of the enzymes
metabolizing PtdIns(3,5)P2 have revealed that this phospholipid is involved in
the control of endolysosomal systems and plays crucial roles in various
mammalian tissues. In this article, we review the current state of knowledge of
the metabolic/physiological functions of PtdIns(3,5)P2, and describe how
disruption of these functions may contribute to human diseases. |
Can we detect DNA strand asymmetries using dinucleotide relative abundance "genomic signatures"? | The set of dinucleotide relative abundances can be regarded as a genomic signature because, despite diversity between species, it varies little between 50 kilobase or longer windows on a given genome. Thus, dinucleotide relative abundance profiles are species-type specific. These profiles are computed from the base step "odds ratios" that compare dinucleotide frequencies to those expected under the assumption of stochastic equilibrium (thorough shuffling). Dinucleotide relative abundance "genomic signatures" are strand-independent second-order DNA features. Thus, they cannot be used to detect DNA strand asymmetries. | Early biochemical experiments established that the set of dinucleotide odds
ratios or 'general design' is a remarkably stable property of the DNA of an
organism, which is essentially the same in protein-coding DNA, bulk genomic DNA,
and in different renaturation rate and density gradient fractions of genomic DNA
in many organisms. Analysis of currently available genomic sequence data has
extended these earlier results, showing that the general designs of disjoint
samples of a genome are substantially more similar to each other than to those
of sequences from other organisms and that closely related organisms have
similar general designs. From this perspective, the set of dinucleotide odds
ratio (relative abundance) values constitute a signature of each DNA genome,
which can discriminate between sequences from different organisms.
Dinucleotide-odds ratio values appear to reflect not only the chemistry of
dinucleotide stacking energies and base-step conformational preferences, but
also the species-specific properties of DNA modification, replication and repair
mechanisms. We compare and contrast genome-wide compositional biases and distributions of
short oligonucleotides across 15 diverse prokaryotes that have substantial
genomic sequence collections. These include seven complete genomes (Escherichia
coli, Haemophilus influenzae, Mycoplasma genitalium, Mycoplasma pneumoniae,
Synechocystis sp. strain PCC6803, Methanococcus jannaschii, and Pyrobaculum
aerophilum). A key observation concerns the constancy of the dinucleotide
relative abundance profiles over multiple 50-kb disjoint contigs within the same
genome. (The profile is rhoXY* = fXY*/fX*fY* for all XY, where fX* denotes the
frequency of the nucleotide X and fY* denotes the frequency of the dinucleotide
XY, both computed from the sequence concatenated with its inverted complementary
sequence.) On the basis of this constancy, we refer to the collection [rhoXY*]
as the genome signature. We establish that the differences between [rhoXY*]
vectors of 50-kb sample contigs of different genomes virtually always exceed the
differences between those of the same genomes. Various di- and tetranucleotide
biases are identified. In particular, we find that the dinucleotide CpG=CG is
underrepresented in many thermophiles (e.g., M. jannaschii, Sulfolobus sp., and
M. thermoautotrophicum) but overrepresented in halobacteria. TA is broadly
underrepresented in prokaryotes and eukaryotes, but normal counts appear in
Sulfolobus and P. aerophilum sequences. More than for any other bacterial
genome, palindromic tetranucleotides are underrepresented in H. influenzae. The
M. jannaschii sequence is unprecedented in its extreme underrepresentation of
CTAG tetranucleotides and in the anomalous distribution of CTAG sites around the
genome. Comparative analysis of numbers of long tetranucleotide microsatellites
distinguishes H. influenzae. Dinucleotide relative abundance differences between
bacterial sequences are compared. For example, in these assessments of
differences, the cyanobacteria Synechocystis, Synechococcus, and Anabaena do not
form a coherent group and are as far from each other as general gram-negative
sequences are from general gram-positive sequences. The difference of M.
jannaschii from low-G+C gram-positive proteobacteria is one-half of the
difference from gram-negative proteobacteria. Interpretations and hypotheses
center on the role of the genome signature in highlighting similarities and
dissimilarities across different classes of prokaryotic species, possible
mechanisms underlying the genome signature, the form and level of genome
compositional flux, the use of the genome signature as a chronometer of
molecular phylogeny, and implications with respect to the three putative
eubacterial, archaeal, and eukaryote domains of life and to the origin and early
evolution of eukaryotes. Several bacterial genomes exhibit preference for G over C on the DNA leading
strand extending from the origin of replication to the ter-region in the genomes
of Escherichia coli, Mycoplasma genitalium, Bacillus subtilis, and marginally in
Haemophilus influenzae, Mycoplasma pneumoniae, and Helicobacter pylori. Strand
compositional asymmetry is not observed in the cyanobacterium Synechocystis sp.
genome nor in the archaeal genomes of Methanococcus jannaschii, Methanobacterium
thermoautotrophicum, and Archaeoglobus fulgidus. A strong strand compositional
asymmetry is observed in beta-type but not alpha- or gamma-type human
herpesviruses featuring G > C downstream of oriL and C > G upstream of oriL.
Dinucleotide relative abundances (i.e., dinucleotide representations normalized
by the component nucleotide frequencies) are consot with respect to the
leading and lagging strands. Strand compositional asymmetry may reflect on
differences in replication synthesis of the leading versus lagging strand, on
differences between template and coding strand associated with
transcription-coupled repair mechanisms, on differences in gene density between
the two strands, on differences in residue and codon biases in relation to gene
function, expression level, or operon organization, or on differences in single
or context-dependent base mutational rates. The absence of strand asymmetry in
the archaeal genomes may reflect the presence of multiple origins of
replication. We provide data and analysis to support the hypothesis that the ancestor of
animal mitochondria (Mt) and many primitive amitochondrial (a-Mt) eukaryotes was
a fusion microbe composed of a Clostridium-like eubacterium and a
Sulfolobus-like archaebacterium. The analysis is based on several observations:
(i) The genome signatures (dinucleotide relative abundance values) of
Clostridium and Sulfolobus are compatible (sufficiently similar) and each has
significantly more similarity in genome signatures with animal Mt sequences than
do all other available prokaryotes. That stable fusions may require
compatibility in genome signatures is suggested by the compatibility of plasmids
and hosts. (ii) The expanded energy metabolism of the fusion organism was
strongly selective for cementing such a fusion. (iii) The molecular apparatus of
endospore formation in Clostridium serves as raw material for the development of
the nucleus and cytoplasm of the eukaryotic cell. Various methods have been developed to detect horizontal gene transfer in
bacteria, based on anomalous nucleotide composition, assuming that compositional
features undergo amelioration in the host genome. Evolutionary theory predicts
the inevitability of false positives when essential sequences are strongly
conserved. Foreign genes could become more detectable on the basis of their
higher order compositions if such features ameliorate more rapidly and uniformly
than lower order features. This possibility is tested by comparing the
heterogeneities of bacterial genomes with respect to strand-independent first-
and second-order features, (i) G + C content and (ii) dinucleotide relative
abundance, in 1 kb segments. Although statistical analysis confirms that (ii) is
less inhomogeneous than (i) in all 12 species examined, extreme anomalies with
respect to (ii) in the Escherichia coli K12 genome are typically co-located with
essential genes. |
What is the percentage of responders to tetrabenazine treatment for dystonia in children? | Tetrabenazine is used empirically in the treatment of dystonia in children with variable success. Observational studies report improvement of up to > 60% of the patients. | We retrospectively reviewed the clinical course and response to treatment of 67
patients with tardive dystonia. The age at onset ranged from 13 to 72 years
without predilection to any particular age group or sex. Patients developed
tardive dystonia even after relatively short duration of exposure to dopamine
antagonists (21% within one year). Five of 42 patients withdrawn from these
drugs remitted. Overall clinical improvement occurred in 52% of patients.
Tetrabenazine and reserpine were most effective (greater than 50% response rate)
in controlling dystonia. Anticholinergic drugs diminished dystonia in 46% of
patients. Twenty-three children (aged less than 18 years) and 17 adults with severe
widespread dystonia were treated with high doses of benzhexol (up to 130 mg
daily introduced slowly over many weeks). Children tolerated higher doses
(median 30 mg/day) than adults (median 20 mg/day). 52% of the children gained
useful benefit, many (43%) without unwanted side effects. Such an approach was
less successful in adults; 41% gained benefit, but only 35% had no side effects.
Twelve adults with severe axial dystonia, and two children with life-threatening
generalised dystonia were treated with a combination of a low constant dose of
tetrabenazine to which were added pimozide and benzhexol as necessary. The dose
of tetrabenazine was aimed at 75 mg daily; pimozide was increased (6 to 25
mg/day) until the dystonia was relieved or Parkinsonism and other side-effects
prevented further increments; if necessary benzhexol (6 to 30 mg/day) then was
added to control side-effects and to provide additional benefit. 75% of the
adults with severe axial dystonia, and one of the two children with life
threatening generalised dystonia gained useful benefit from this regime. It is
concluded that high dose benzhexol is the present first treatment of choice for
children with severe dystonia, and is worth a try in adults but with less
expectation of success. When benzhexol treatment alone fails in adults with
severe disabling axial dystonia, or in children with life-threatening
generalised dystonia, combined therapy with tetrabenazine, pimozide and
benzhexol may give valuable symptomatic relief. Myoglobinuria may follow extreme muscular exertion or disorders that cause
muscle necrosis. Dystonia has not been implicated previously. We studied an
8-year-old boy of non-Jewish, Mexican-American descent with autosomal-domit
dystonia musculorum deformans who developed rapidly progressive and severe
generalized dystonia, hyperpyrexia, myoglobinuria, and renal failure.
Curarization was required. Transient improvement was achieved with tetrabenazine
and baclofen, but bilateral thalamotomy was then performed. Patients with severe
dystonia should be observed for evidence of myoglobinuria. INTRODUCTION: Cerebral calcifications are a cause of secondary dystonia and may
be an uncommon complication of radiotherapy. We report a very severe case of
generalized dystonia due to postradiotherapy basal ganglia calcifications.
CASE REPORT: An 8-year-old girl received 53 grays radiotherapy after surgery for
craniopharyngioma. One year later she developed generalized dystonia. Computed
tomography showed bilateral basal ganglia calcifications, especially of the
lenticular nuclei. Pharmacological treatment with tetrabenazine, clonazepam and
trihexiphenydile allowed a very limited improvement of dystonia; the course was
complicated by dystonic storms and decompensations resulting from the
iatrogenous panhypopituitarism.
CONCLUSION: This case illustrates a severe complication of cranial irradiation
which should be considered in the indications of this treatment, especially for
children. The authors report a patient with dystonia secondary to bilateral lesions of the
basal ganglia, who improved dramatically with levodopa. The patient presented at
the age of 4 years with progressive dystonia of the lower extremities and right
upper extremity. Magnetic resoce imaging (MRI) of the brain showed bilateral
hyperintensities of the globus pallidus that remained stable over the years.
Despite extensive investigations, the etiology of her basal ganglia lesions
remained nebulous. The patient's dystonia responded to Trihexyphenidyl and to
tetrabenazine, but these medications needed to be stopped because of side
effects. At the age of 12 years, small doses of levodopa-carbidopa were tried
and resulted in dramatic improvement of her dystonia. The authors believe that
in the pediatric population with secondary dystonias other than Segawa disease,
even though this has been reported only rarely to be effective, a therapeutic
trial with levodopa should be considered in some instances. |
Is there any relationship between histone ubiquitylation and splicing? | Yes, in the case of histone H2B | Pre-messenger RNA splicing is carried out by a large ribonucleoprotein complex
called the spliceosome. Despite the striking evolutionary conservation of the
spliceosomal components and their functions, controversy persists about the
relative importance of splicing in Saccharomyces cerevisiae-particularly given
the paucity of intron-containing genes in yeast. Here we show that splicing of
one pre-messenger RNA, SUS1, a component of the histone H2B ubiquitin protease
machinery, is essential for establishing the proper modification state of
chromatin. One protein complex that is intimately involved in pre-mRNA splicing,
the yeast cap-binding complex, appears to be particularly important, as
evidenced by its extensive and unique genetic interactions with enzymes that
catalyze histone H2B ubiquitination. Microarray studies show that cap binding
complex (CBC) deletion has a global effect on gene expression, and for
approximately 20% of these genes, this effect is suppressed when ubiquitination
of histone H2B is eliminated. Consistent with this finding of histone H2B
dependent effects on gene expression, deletion of the yeast cap binding complex
leads to overubiquitination of histone H2B. A key component of the
ubiquitin-protease module of the SAGA complex, Sus1, is encoded by a gene that
contains two introns and is misspliced when the CBC is deleted, leading to
destabilization of the ubiquitin protease complex and defective modulation of
cellular H2B levels. These data demonstrate that pre-mRNA splicing plays a
critical role in histone H2B ubiquitination and that the CBC in particular helps
to establish the proper state of chromatin and proper expression of genes that
are regulated at the level of histone H2B ubiquitination. BACKGROUND: The packaging of DNA into chromatin regulates transcription from
initiation through 3' end processing. One aspect of transcription in which
chromatin plays a poorly understood role is the co-transcriptional splicing of
pre-mRNA.
RESULTS: Here we provide evidence that H2B monoubiquitylation (H2BK123ub1) marks
introns in Saccharomyces cerevisiae. A genome-wide map of H2BK123ub1 in this
organism reveals that this modification is enriched in coding regions and that
its levels peak at the transcribed regions of two characteristic subgroups of
genes. First, long genes are more likely to have higher levels of H2BK123ub1,
correlating with the postulated role of this modification in preventing cryptic
transcription initiation in ORFs. Second, genes that are highly transcribed also
have high levels of H2BK123ub1, including the ribosomal protein genes, which
comprise the majority of intron-containing genes in yeast. H2BK123ub1 is also a
feature of introns in the yeast genome, and the disruption of this modification
alters the intragenic distribution of H3 trimethylation on lysine 36 (H3K36me3),
which functionally correlates with alternative RNA splicing in humans. In
addition, the deletion of genes encoding the U2 snRNP subunits, Lea1 or Msl1, in
combination with an htb-K123R mutation, leads to synthetic lethality.
CONCLUSION: These data suggest that H2BK123ub1 facilitates cross talk between
chromatin and pre-mRNA splicing by modulating the distribution of intronic and
exonic histone modifications. Eukaryotic gene expression involves tight coordination between transcription and
pre-mRNA splicing; however, factors responsible for this coordination remain
incompletely defined. Here, we explored the genetic, functional, and biochemical
interactions of a likely coordinator, Npl3, an SR-like protein in Saccharomyces
cerevisiae that we recently showed is required for efficient co-transcriptional
recruitment of the splicing machinery. We surveyed the NPL3 genetic interaction
space and observed a significant enrichment for genes involved in histone
modification and chromatin remodeling. Specifically, we found that Npl3
genetically interacts with both Bre1, which mono-ubiquitinates histone H2B as
part of the RAD6 Complex, and Ubp8, the de-ubiquitinase of the SAGA Complex. In
support of these genetic data, we show that Bre1 physically interacts with Npl3
in an RNA-independent manner. Furthermore, using a genome-wide splicing
microarray, we found that the known splicing defect of a strain lacking Npl3 is
exacerbated by deletion of BRE1 or UBP8, a phenomenon phenocopied by a point
mutation in H2B that abrogates ubiquitination. Intriguingly, even in the
presence of wild-type NPL3, deletion of BRE1 exhibits a mild splicing defect and
elicits a growth defect in combination with deletions of early and late splicing
factors. Taken together, our data reveal a connection between Npl3 and an
extensive array of chromatin factors and describe an uticipated functional
link between histone H2B ubiquitination and pre-mRNA splicing. |
Which disease can be treated with Delamanid? | Delamanid is used in patients with multidrug-resistant tuberculosis. | The advent of antibiotics for the treatment of tuberculosis (TB) represented a
major breakthrough in the fight against the disease. However, since its first
use, antibiotic therapy has been associated with the emergence of resistance to
drugs. The incorrect use of anti-TB drugs, either due to prescription errors,
low patient compliance, or poor quality of drugs, led to the widespread
emergence of Mycobacterium tuberculosis strains with an expanding spectrum of
resistance. The spread of multidrug-resistant (MDR) strains (ie, strains
resistant to both isoniazid and rifampicin) has represented a major threat to TB
control since the 1990s. In 2006, the first cases of MDR strains with further
resistance to fluoroquinolone and injectable drugs were described and named
extensively drug-resistant TB (XDR-TB). The emergence of XDR-TB strains is a
result of mismanagement of MDR cases, and treatment relies on drugs that are
less potent and more toxic than those used to treat drug-susceptible or MDR
strains. Furthermore, treatment success is lower and mortality higher than
achieved in MDR-TB cases, and the number of drugs necessary in the intensive
phase of treatment may be higher than the four drugs recommended for MDR-TB.
Linezolid may represent a valuable drug to treat cases of XDR-TB. Delamanid,
bedaquiline, and PA-824 are new anti-TB agents in the development pipeline that
have the potential to enhance the cure rate of XDR-TB. The best measures to
prevent new cases of XDR-TB are the correct management of MDR-TB patients, early
detection, and proper treatment of existing patients with XDR-TB. INTRODUCTION: The limited availability of effective drugs causes difficulties in
the management of multidrug-resistant tuberculosis (MDR-TB) and novel
therapeutic agents are needed. Delamanid , a new nitro-hydro-imidazooxazole
derivative, inhibits mycolic acid synthesis. This review covers the efficacy and
safety of delamanid for MDR-TB.
AREA COVERED: This paper reviews the pharmacological profile of delamanid and
the results of clinical trials evaluating its efficacy for treating MDR-TB in
combination with other anti-TB drugs. The drug's safety and tolerability
profiles are also considered.
EXPERT OPINION: Delamanid showed potent activity against drug-susceptible and
-resistant Mycobacterium tuberculosis in both in vitro and in vivo studies. In
clinical trials, the drug showed significant early bactericidal activity in
pulmonary TB patients, and increased culture conversion after 2 months of
treatment in combination with an optimized background regimen in MDR-TB
patients. In addition, decreased mortality was observed in MDR-TB patients who
received > 6 months of delamanid treatment. The drug was generally tolerable,
but QT prolongation should be monitored carefully using electrocardiograms and
potassium levels. Therefore, delamanid could be used as part of an appropriate
combination regimen for pulmonary MDR-TB in adult patients when an effective
treatment regimen cannot otherwise be composed for reasons of resistance or
tolerability. Tuberculosis (Tb) continues to be a dreadful infection worldwide with nearly 1.5
million deaths in 2013. Furthermore multi/extensively drug-resistant Tb
(MDR/XDR-Tb) worsens the condition. Recently approved anti-Tb drugs (bedaquiline
and delamanid) have the potential to induce arrhythmia and are recommended in
patients with MDR-Tb when other alternatives fail. The goal of elimination of Tb
by 2050 will not be achieved without an effective new vaccine. The recent
advancement in the development of Tb vaccines is the keen focus of this review.
To date, Bacille Calmette Guerin (BCG) is the only licensed Tb vaccine in use,
however its efficacy in pulmonary Tb is variable in adolescents and adults.
There are nearly 15 vaccine candidates in various phases of clinical trials,
includes five protein or adjuvant vaccines, four viral-vectored vaccines, three
mycobacterial whole cell or extract vaccines, and one each of the recombit
live and the attenuated Mycobacterium tuberculosis (Mtb) vaccine. |
What was the aim of the COSS (Carotid Occlusion Surgery Study) clinical trial? | The Carotid Occlusion Surgery Study (COSS) was conducted to determine if superficial temporal artery-middle cerebral artery (STA-MCA) bypass, when added to the best medical therapy, would reduce subsequent ipsilateral stroke in patients with complete internal carotid artery (ICA) occlusion and an elevated oxygen extraction fraction (OEF) in the cerebral hemisphere distal to the occlusion. | Intracranial atherosclerotic disease (ICAD) is the most common proximate
mechanism of ischemic stroke worldwide. Approximately half of those affected are
Asians. For diagnosis of ICAD, intra-arterial angiography is the gold standard
to identify extent of stenosis. However, noninvasive techniques including
transcranial ultrasound and MRA are now emerging as reliable modalities to
exclude moderate to severe (50%-99%) stenosis. Little is known about measures
for primary prevention of the disease. In terms of secondary prevention of
stroke due to intracranial atherosclerotic stenosis, aspirin continues to be the
preferred antiplatelet agent although clopidogrel along with aspirin has shown
promise in the acute phase. Among Asians, cilostazol has shown a favorable
effect on symptomatic stenosis and is of benefit in terms of fewer bleeds.
Moreover, aggressive risk factor management alone and in combination with dual
antiplatelets been shown to be most effective in this group of patients.
Interventional trials on intracranial atherosclerotic stenosis have so far only
been carried out among Caucasians and have not yielded consistent results. Since
the Asian population is known to be preferentially effected, focused trials need
to be performed to establish treatment modalities that are most effective in
this population. BACKGROUND AND PURPOSE: The Carotid Occlusion Surgery Study (COSS) was an
improvement over the Extracranial-Intracranial Bypass Study, which did not
utilize physiological selection. To assess possible reasons for early closure of
the COSS trial, we reviewed COSS methods used to identify high-risk patients and
compared results with separate quantitative data.
METHODS: Increased oxygen extraction fraction (OEF) by positron emission
tomography is a gold standard for ischemia, but the specific thresholds and
equivalency of the semiquantitative OEF ratio utilized in COSS and quantitative
OEF are at issue.
RESULTS: The semiquantitative hemispheric OEF ratio used in COSS did not
identify the same group of patients as did quantitative OEF using a threshold of
50%.
CONCLUSIONS: The failure of COSS is likely caused by a failure of the
semiquantitative, hemispheric OEF ratio method rather than by the selection for
bypass based on hemodynamic compromise. Collaborators: Powers WJ, Grubb RL Jr, Videen TO, Derdeyn CP, Papps CH, McElvany
K, Counts L, Kelly C, Barnard T, Ferrari J, Davis T, Hall T, Clarke WR Jr, Adams
HP Jr, Costigan M, Singletary K, Fang Y, Marmet J, Ecklund D, Wichman M, Hansen
M, Peters R, Anderson D, Woolson RF, Diltz C, Lang J, Beane L, Sieren J, Zhang
Y, Videen TO, Hood JT Jr, Adams HP Jr, Weir BK, Brott T, Gorelick P, Ferguson G,
Marler J, Ravina B, Galpern W, Moy C, Janis S, Haley EC, Grady S, Palesch Y,
Eidelberg D, Derdeyn CP, Shinawi L, Hantler N, Tyler A, Catanzaro M, Fritsch S,
Dacey R, Chicoine M, Zipfel G, Davis P, Olalde H, Rogers M, Jacobs P, Hitchon P,
Leira E, Howard M, Hoballah J, Ireland J, Marshall R, Slane K, Connolly ES,
Festa J, Solomon R, Dhamoon M, Wiley J, Linares G, Marchidann A, Szeder V,
Noskin O, Antoniello D, Liberato B, Frontera J, Prabhakaran S, Chong J, Wright
C, Zuccarello M, Koenig C, Sprafka L, Flaherty M, Kissela B, Kleindorfer D,
Kempinsky-Cliver S, Broderick J, Roggee C, Kanter D, Woo D, Schneider A, Ewing
I, Charbel F, Watson K, Mlinarevich N, Ruland S, Sepideh AH, Grysiewicz R, Jones
J, Wilson J, Glazier S, Miller C, Jenkins W, Mintz A, Craig J, Tegeler C,
O'Brien K, Ching M, Ionita C, Lee-Kwen P, Chan R, Munschauer F 3rd, Parkes K,
Coad ML, Wrest K, Olson K, Harrington S, Hopkins LN, Grand W, Ferguson R,
Heckler E, Pereira L, Sawyer R, Budny J, Levy E, Nemeth L, Ali J, Rasmussen P,
Andrews-Hinders D, Katzan I, Uchino K, Mayberg M, Gupta R, Bartholomew J, Urbain
JL, Wheeler T, Strozniak L, Krisht A, Partington S, Fewell D, Schmidley J,
Steinberg G, Coburn M, Luu D, Wijman C, Darsaut T, Sinclair J, Guzman R,
Ciaravino A, Varga M, Biederman K, Horner T, Payner T, Redelman K, Fleck J,
Scott J, Barrow D, Holland E, Nahab F, Rahimazadeh K, Waddy S, Burke S,
Chimowitz M, Frankel M, Samuels O, Sailor S, Braimah J, Stark C, Lane B, Lessard
N, Howlett-Smith H, Ezzedine M, Stern B, Shipp B, Hanson K, Turan T, Osman N,
Ivan C, Bruno A, Biller J, Lincoln FN, Guingrich S, Micheels A, Pritz M, Fleck
J, Williams L, Jones W, Sears A, Faber K, Lopez A, Chadwick L, Matthews V,
Girdler M, Lawton M, Hannegan L, Smith W, Dempsey R, Winne P, Washburn M, Li A,
Sattin J, Jensen M, Chacon M, Dulli D, Newman G, Geraghty M, Page N, Kish J,
Chan R, Hesser K, Lownie S, Hachinski V, Frank C, Fleming L, Baptista K,
Matijevic S, Jovin T, Yonas H, Uchino K, Billigen J, Kirby L, Hammer M, Jumaa M,
Lin R, Malik A, Ranawat N, Reddy V, Wechsler L, Zaidi S, Ranawat N, Rothfus MA,
Adelson D, Gupta R, Tayal A, Gebel J, Nemoto E, Pindzola R, Mallory Y, Thompson
BG, Auer D, Persad C, Powells D, Zahuranec D, Brown D, Hickenbottom S,
Rosenwasser R, Simons E, Jensen M, Bell R, Kumar M, Moussouttas M, Pineda C,
August D, Veznedaroglu E, Brock D, McGinnis G, Scollon R, Hilbert K, Johnson M,
Unwin H, Graybeal D, Kopitnik T, Davis L, Blair A, Samson D, Lee J, Kassab M,
Martin N, Saver J, Guzy J, Haines J, Varma J, Smith H, Fiaz R, Ali L, Carmichael
ST, Liebeskind D, Ovbiagele B, Vespa P, Duke K, Starkman S, Froehler M, Tenser
M, Villablanca P, Miller C, Shah S, Czernin J, Suzuki S, Dobkin B, Towfighi A,
Kidwell C, Fredieu A, Tremwel M, Manglona D, Zabramski J, Snyder J, Frey J,
Spetzler R, Flaster M, Mahmood MA, Akins P, Byer J, Schaefer J, Wentworth D,
Croopnick S, Newman L, Cabe K, Hanson S, Castle A, Nussbaum E, Kuno L, Mattson
J, Yonas H, Brown A, Malkoff M, Graham G, Stack E, Kirby L, Diaz F, Fessler R,
Gordon V, Jacobs B, Ogilvy C, Buckley D, Mansala J, Bruce A, Buono F, Greer
D, Whalen M, Meyer F, Fode-Thomas N, Thalacker S, Piepgras D, Fulgham J,
Atkinson J, Biller J, Chadwick L, Anderson D, Schneck M, Dafer R, Vidal SM,
Duckworth E, Selman W, Zalaski G, Cwiklinski V, Sila C, Tarr R, Bambakadis N,
Suarez J, Graffagnino C, Stoner J, Moore S, Friedman A, Chilikuri V, Kesler J,
Watridge C, Pannell M, Miller G, Jaciewicz M, Wright L, Newell D, Kraybill BM,
Likosky W, French B, Bush J, Brown A, Block J, Blanchard B, Becker K, Sekhar L,
Newell D, Tanzi P, Nuxoll D, Bybee H, Cramer S, Volpi J, Bautista M, Zhang J,
Chiu D, Ling J, Bledsoe D, Tenorio J, Abdulrauf S, Kane M, Richard C, Swoboda M,
Cruz-Flores S, Ibata B, Fessler R, Telck K, Gordon V, Pieper D, Silverman B,
Diaz F, Whapham J, Hanson S, Castle A, Nussbaum E, Sherman D, Leonard A, Moreno
L, Tonarelli S, Hart R, Carolin M, Roman G, Caron JL, Benevente O, Vollmer D,
Sher A, Jett S, Neely G, Wallis RA, Panizzon K, Licht E, Cheng E, Gardner R,
McAdoo J, Haupt D, Riggs-Ruupp K, Kassab M, Wehner S, Majid A, Slivka A,
Agriesti J, Dobbs M, Fowler A, Pettigrew LC, Vaishnar A, Ryan S, Williams S,
Nichols F, Close B, Bruno A, Switzer J, Hess D, Hall C, Rogalsky-Nacca J, Wilson
S, Aucutt-Walter N, Huang D, Poole R, Ostrander M, Logan W, Schroer S, Friday G,
Brown J, Derdeyn CP, Lich L, Schwarz S, Gaehle G, Mantil J, Strohmeyer P,
Gagermeier E, Mattmuller S, Naraya T, Shi B, Satter M, Simmons G, Christian
B, Carone M, Perkins T, Brackney M, Mountz J, Price J, Sashin D, Meltzer C,
Mathis C, Abella E, Cariddi D, Finley B, Valk P, Cronin J, Tesar R, Hichwa R,
Sunderland J, Watkins L, Ponto L, Van Heertum R, Simpson N, Saxena C, Lockwood
A, Haka M, Chugani H, Ferguson L, Musik O, Manger T, Reiman E, Intorcia D,
Reeder S, Bandy D, Giurlani T, Prouty A, Burns C, Stone C, Christian B, Converse
A, Roberts A, Oakes T, Dabbs K, Mullan B, Jacobson M, Kemp B, Brinkman T, Garg
P, Morton K, Stroud P, Link K, Brown-Proctor C, Fahey F, Wollenweber S, Smith H,
Fox P, Hardies J, Morena L, Narayana S, Jerabek P, Mazziotta J, Woods R,
Ferdez O, Jaffer N, Brady T, Fischman A, Callahan R, Correi J, Goodman M,
Crowe R, Votaw J, Bremner JD, Nye J, Eary J, Krohn K, Kauno K, Lewellen B,
Kimura L, Shoner S, Lewellen T, Coleman RE, Petry N. Intracranial atherosclerotic disease (ICAD) is a major cause of ischemic stroke
worldwide and represents a significant health problem. The pathogenesis and
natural history of ICAD are poorly understood, and rigorous treatment paradigms
do not exist as they do for extracranial atherosclerosis. Currently, the best
treatment for ICAD remains aspirin therapy, but many patients who are placed on
aspirin continue to experience recurrent strokes. As microsurgical and
endovascular techniques continue to evolve, the role of extracranial to
intracranial bypass operations and stenting are increasingly being reconsidered.
We performed a PubMed review of the English literature with a particular focus
on treatment options for ICAD and present evidence-based data for the role of
surgery and stenting in ICAD against medical therapy alone. BACKGROUND: Transcranial Doppler (TCD) CO2-reactivity and oxygen-15 positron
emission tomography (PET) have both been used to measure the cerebral
haemodynamic state in patients who may have a compromised blood flow. Our
purpose was to investigate whether PET and TCD identify the same patients with
an impaired flow state of the brain in patients with internal carotid artery
(ICA) occlusion.
METHODS: Patients with recent transient ischaemic attack or minor ischaemic
stroke associated with ICA occlusion underwent TCD with measurement of
CO2-reactivity and oxygen-15 PET within a median time interval of 6 days.
RESULTS: We included 24 patients (mean age 64 ± 10 years). Seventeen (71%)
patients had impaired CO2-reactivity (≤20%), of whom six had absent reactivity
(0%) or steal (<0%) in the hemisphere ipsilateral to the ICA occlusion. PET of
the perfusion state of the hemisphere ipsilateral to the ICA occlusion
demonstrated stage 1 haemodynamic compromise (decreased cerebral blood flow
(CBF) or increased cerebral blood volume (CBV) without increased oxygen
extraction fraction (OEF)) in 13 patients and stage 2 (increased OEF) in 2
patients. In 12 patients (50%), there was agreement between TCD and PET,
indicating haemodynamic compromise in 10 and a normal flow state of the brain in
2 patients. There was no significant correlation between CO2-reactivity and CBF
ipsilateral/contralateral hemispheric ratio (r = 0.168, p value = 0.432), OEF
ratio (r = -0.242, p value = 0.255), or CBV/CBF ratio (r = -0.368, p
value = 0.077).
CONCLUSIONS: In patients with symptomatic ICA occlusion, identification of an
impaired flow state of the brain by PET and TCD CO2-reactivity shows concordance
in only half of the patients. OBJECT: The Carotid Occlusion Surgery Study (COSS) was conducted to determine if
superficial temporal artery-middle cerebral artery (STA-MCA) bypass, when added
to the best medical therapy, would reduce subsequent ipsilateral stroke in
patients with complete internal carotid artery (ICA) occlusion and an elevated
oxygen extraction fraction (OEF) in the cerebral hemisphere distal to the
occlusion. A recent publication documented the methodology of the COSS in detail
and briefly outlined the major findings of the trial. The surgical results of
the COSS are described in detail in this report.
METHODS: The COSS was a prospective, parallel-group, 1:1 randomized, open-label,
blinded-adjudication treatment trial. Participants, who had angiographically
demonstrated complete occlusion of the ICA causing either a transient ischemic
attack or ischemic stroke within 120 days and hemodynamic cerebral ischemia
indicated by an increased OEF measured by PET, were randomized to either
surgical or medical treatment. One hundred ninety-five patients were randomized:
97 to the surgical group and 98 to the medical group. The surgical patients
underwent an STA-MCA cortical branch anastomosis.
RESULTS: In the intention-to-treat analysis, the 2-year rates for the primary
end point were 21% for the surgical group and 22.7% for the medical group (p =
0.78, log-rank test). Fourteen (15%) of the 93 patients who had undergone an
arterial bypass had a primary end point ipsilateral hemispheric stroke in the
30-day postoperative period, 12 within 2 days after surgery. The STA-MCA
arterial bypass patency rate was 98% at the 30-day postoperative visit and 96%
at the last follow-up examination. The STA-MCA arterial bypass markedly
improved, although it did not normalize, the level of elevated OEF in the
symptomatic cerebral hemisphere. Five surgically treated and 1 nonsurgically
treated patients in the surgical group had a primary end point ipsilateral
hemispheric stroke after the 30-day postoperative period. No baseline
characteristics or intraoperative variables revealed those who would experience
a procedure-related stroke.
CONCLUSIONS: Despite excellent bypass graft patency and improved cerebral
hemodynamics, STA-MCA anastomosis did not provide an overall benefit regarding
ipsilateral 2-year stroke recurrence, mainly because of a much better than
expected stroke recurrence rate (22.7%) in the medical group, but also because
of a significant postoperative stroke rate (15%). Clinical trial registration
no.: NCT00029146. OBJECT: The Carotid Occlusion Surgery Study (COSS) was a large, prospective
clinical trial that examined whether superficial temporal artery-middle cerebral
artery (STA-MCA) bypass, in addition to best medical therapy, reduced the risk
of ipsilateral ischemic stroke in patients with carotid artery occlusion and
hemodynamic cerebral ischemia. Despite improved cerebral hemodynamics and
excellent bypass graft patency rates, COSS failed to show a benefit for the
surgical group with respect to ipsilateral stroke recurrence at 2 years after
treatment. This was due to a lower than expected rate of recurrent ipsilateral
stroke in the medically treated group and a high rate of perioperative
ipsilateral strokes in the surgical group. Critics of the trial have cited
surgeon inexperience and technical difficulties related to the performance of
the bypass graft as a leading cause of failure of the trial.
METHODS: The authors retrospectively identified all patients from the COSS with
an ipsilateral, perioperative (< 30 days) ischemic stroke after STA-MCA cortical
branch anastomosis. Study records, operative notes, stroke adjudication forms,
and imaging studies were reviewed. Ischemic strokes were characterized as bypass
graft related or non-bypass graft related based on clinical and radiographic
findings.
RESULTS: Fourteen of 93 surgically treated patients experienced an ipsilateral,
perioperative ischemic stroke. Postoperatively, the mean oxygen extraction
fraction (OEF) ratio between the symptomatic and asymptomatic cerebral
hemisphere significantly improved in these patients (1.30 ± 0.18 preoperative vs
1.12 ± 0.11 postoperative; p = 0.02), but did not normalize. In this cohort,
total MCA occlusion time during the anastomosis (54.3 ± 23.5 minutes) was no
different from the MCA occlusion time in those surgical patients who did not
have a perioperative stroke (45.4 ± 24.2 minutes, p = 0.2). Bypass graft patency
rates in patients with a perioperative stroke were 92% at 30 days (11 of 12
patients with patency data) and 83% at last follow-up visit (10 of 12 patients
with patency data). These patency rates were not significantly different from
those achieved at 30 days (100%; 76 of 76 patients with patency data; p = 0.14)
and at last follow-up (99%; 71 of 72 patients with patency data; p = 0.052) in
patients without a perioperative stroke. Eighty-six percent (12 of 14 patients)
of strokes were likely attributable to factors unrelated to the STA-MCA
anastomosis. Only 21% of strokes (3 of 14 patients) were in the territory of the
recipient vessel and likely related to technical performance of the anastomosis
itself. One patient was thought to have dual stroke mechanisms.
CONCLUSIONS: Only a small minority of ipsilateral, perioperative ischemic
strokes in the COSS could be attributed to technical problems of the bypass
anastomosis. The majority of ischemic strokes could not be ascribed to this
cause and were most likely due to patient hemodynamic fragility and the
inability of patients to tolerate surgery. Complete long segment carotid occlusion presents a treatment challenge. These
patients cannot be managed adequately by endarterectomy or stenting. Despite
best medical management, many continue to develop recurrent strokes. In this
select group of patients, there may be role for flow augmentation techniques
like superficial temporal-middle cerebral artery bypass. We report a patient who
was thus successfully treated and remains asymptomatic. The relevant literature
is reviewed. |
What are the advantages of the top down mass spectrometric analysis of histones? | Top down mass spectrometry is a way to analyze intact proteins thus enabling: isoform characteriztion and analysis of post-translational modifications. | For more complete characterization of DNA-predicted proteins (including their
posttranslational modifications) a "top-down" approach using high-resolution
tandem MS is forwarded here by its application to methanogens in both
hypothesis-driven and discovery modes, with the latter dependent on new
automation benchmarks for intact proteins. With proteins isolated from ribosomes
and whole-cell lysates of Methanococcus jannaschii (approximately 1,800 genes)
using a 2D protein fractionation method, 72 gene products were identified and
characterized with 100% sequence coverage via automated fragmentation of intact
protein ions in a custom quadrupole/Fourier transform hybrid mass spectrometer.
Three incorrect start sites and two modifications were found, with one of each
determined for MJ0556, a 20-kDa protein with an unknown methylation at
approximately 50% occupancy in stationary phase cells. The separation approach
combined with the quadrupole/Fourier transform hybrid mass spectrometer allowed
targeted and efficient comparison of histones from M. jannaschii, Methanosarcina
acetivorans (largest Archaeal genome, 5.8 Mb), and yeast. This finding revealed
a striking difference in the posttranslational regulation of DNA packaging in
Eukarya vs. the Archaea. This study illustrates a significant evolutionary step
for the MS tools available for characterization of WT proteins from complex
proteomes without proteolysis. Eukaryotic histones serve as prototypical examples of posttranslational
complexity with diverse modifications (PTMs) on many different residues that
comprise a "Histone Code". To help crack this code more efficiently, we
demonstrate a new strategy for protein characterization wherein complete PTM
descriptions are obtained by database retrieval instead of manual interpretation
of information-rich data from high-resolution tandem mass spectrometry (MS/MS).
A database of nearly 50 000 modified histone H4 sequences was created and
queried with 91 fragment ions from electron capture dissociation of a histone
form +112 Da (versus unmodified mass) selectively accumulated in a quadrupole
Fourier transform hybrid mass spectrometer. The correct form atop the retrieval
list indicated dimethylation at Lys20, acetylation at the N terminus, and
acetylation at Lys16 (resolved from trimethylation, Deltam = 0.036 Da). A
statistical evaluation reveals the critical role of mass accuracy and that PTM
"isomers" are retrieved as next-best matches. The applicability of shotgun
annotation to forms of H4 with up to six PTMs is demonstrated, with
extensibility to other histones (e.g., H2A, H2B, H3) and other protein classes
projected. The basis set of protein forms expressed by human cells from the H2B gene family
was determined by Top Down Mass Spectrometry. Using Electron Capture
Dissociation for MS/MS of H2B isoforms, direct evidence for the expression of
unmodified H2B.Q, H2B.A, H2B.K/T, H2B.J, H2B.E, H2B.B, H2B.F, and monoacetylated
H2B.A was obtained from asynchronous HeLa cells. H2B.A was the most abundant
form, with the overall expression profile not changing significantly in cells
arrested in mitosis by colchicine or during mid-S, mid-G2, G2/M, and mid-G1
phases of the cell cycle. Modest hyperacetylation of H2B family members was
observed after sodium butyrate treatment. The modification of H3 in asynchronous HeLa cells was profiled using Top Down
Mass Spectrometry. A broad distribution of species differing by 14 Da and
containing less than 3% unmodified protein was observed for all three variants.
Species of up to +168 Da were observed for H3.1, and fragmentation of all
species by Electron Capture Dissociation (ECD) revealed approximately 5%
methylation of K4 and approximately 50% dimethylation of K9. K14 and K23 were
major sites of acetylation. H3.3 was slightly hypermodified with the apex of the
distribution shifted by approximately +14 Da compared to H3.1. H3.1 (50% and
15%) from colchicine-treated cells was monophosphorylated and diphosphorylated,
respectively, with equivalent modification of S10 and S28. Top Down analysis revealed that at least fourteen genes encoding histone H2A are
coexpressed in HeLa cells. Characterization of these species revealed that all
except H2A.Z and H2A.F/Z were alpha-N-acetylated, H2A.O and H2A.C,D,I,N,P were
the most abundant, and those exceeding approximately 10% abundance lacked
post-translational modifications. This unequivocal identification of H2A forms
illustrates the advantages of Top Down Mass Spectrometry and provides a global
perspective of H2A regulation through the cell cycle. Recent developments in top down mass spectrometry have enabled closely related
histone variants and their modified forms to be identified and quantitated with
unprecedented precision, facilitating efforts to better understand how histones
contribute to the epigenetic regulation of gene transcription and other nuclear
processes. It is therefore crucial that intact MS profiles accurately reflect
the levels of variants and modified forms present in a given cell type or cell
state for the full benefit of such efforts to be realized. Here we show that
partial oxidation of Met and Cys residues in histone samples prepared by
conventional methods, together with oxidation that can accrue during storage or
during chip-based automated oflow electrospray ionization, confounds MS
analysis by altering the intact MS profile as well as hindering
posttranslational modification localization after MS/MS. We also describe an
optimized performic acid oxidation procedure that circumvents these problems
without catalyzing additional oxidations or altering the levels of
posttranslational modifications common in histones. MS and MS/MS of HeLa cell
core histones confirmed that Met and Cys were the only residues oxidized and
that complete oxidation restored true intact abundance ratios and significantly
enhanced MS/MS data quality. This allowed for the unequivocal detection, at the
intact molecule level, of novel combinatorially modified forms of H4 that would
have been missed otherwise. Oxidation also enhanced the separation of human core
histones by reverse phase chromatography and decreased the levels of
salt-adducted forms observed in ESI-FTMS. This method represents a simple and
easily automated means for enhancing the accuracy and sensitivity of top down
analyses of combinatorially modified forms of histones that may also be of
benefit for top down or bottom up analyses of other proteins. A global view of all core histones in yeast is provided by tandem mass
spectrometry of intact histones H2A, H2B, H4, and H3. This allowed detailed
characterization of >50 distinct histone forms and their semiquantitative
assessment in the deletion mutants gcn5Delta, spt7Delta, ahc1Delta, and
rtg2Delta, affecting the chromatin remodeling complexes SAGA, SLIK, and ADA. The
"top down" mass spectrometry approach detected dramatic decreases in acetylation
on H3 and H2B in gcn5Delta cells versus wild type. For H3 in wild type cells,
tandem mass spectrometry revealed a direct correlation between increases of
Lys(4) trimethylation and the 0, 1, 2, and 3 acetylation states of histone H3.
The results show a wide swing from 10 to 80% Lys(4) trimethylation levels on
those H3 tails harboring 0 or 3 acetylations, respectively. Reciprocity between
these chromatin marks was apparent, since gcn5Delta cells showed a 30% decrease
in trimethylation levels on Lys(4) in addition to a decrease of acetylation
levels on H3 in bulk chromatin. Deletion of Set1, the Lys(4) methyltransferase,
was associated with the linked disappearance of both Lys(4) methylation and
Lys(14) and Lys(18) or Lys(23) acetylation on H3. In sum, we have defined the
"basis set" of histone forms present in yeast chromatin using a current mass
spectrometric approach that both quickly profiles global changes and directly
probes the connectivity of modifications on the same histone. Methylation of histone H4 at lysine 20 (K20) has been implicated in
transcriptional activation, gene silencing, heterochromatin formation, mitosis,
and DNA repair. However, little is known about how this modification is
regulated or how it contributes to these diverse processes. Metabolic labeling
and top-down mass spectrometry reveal that newly synthesized H4 is progressively
methylated at K20 during the G(2), M, and G(1) phases of the cell cycle in a
process that is largely inescapable and irreversible. Approximately 98% of new
H4 becomes dimethylated within two to three cell cycles, and K20 methylation
turnover in vivo is undetectable. New H4 is methylated regardless of prior
acetylation, and acetylation occurs predomitly on K20-dimethylated H4,
refuting the hypothesis that K20 methylation antagonizes H4 acetylation and
represses transcription epigenetically. Despite suggestions that it is required
for normal mitosis and cell cycle progression, K20 methylation proceeds normally
during colchicine treatment. Moreover, delays in PR-Set7 synthesis and K20
methylation which accompany altered cell cycle progression during sodium
butyrate treatment appear to be secondary to histone hyperacetylation or other
effects of butyrate since depletion of PR-Set7 did not affect cell cycle
progression. Together, our data provide an unbiased perspective of the
regulation and function of K20 methylation. Recent advances in mass spectrometry instrumentation, such as FTICR and
OrbiTrap, have made it possible to generate high-resolution spectra of entire
proteins. While these methods offer new opportunities for performing "top-down"
studies of proteins, the computational tools for analyzing top-down data are
still scarce. In this paper we investigate the application of spectral alignment
to the problem of identifying protein forms in top-down mass spectra (i.e.,
identifying the modifications, mutations, insertions, and deletions). We
demonstrate how spectral alignment efficiently discovers protein forms even in
the presence of numerous modifications and how the algorithm can be extended to
discover positional isomers from spectra of mixtures of isobaric protein forms. Quantitative proteomics has focused heavily on correlating protein abundances,
ratios, and dynamics by developing methods that are protein expression-centric
(e.g. isotope coded affinity tag, isobaric tag for relative and absolute
quantification, etc.). These methods effectively detect changes in protein
abundance but fail to provide a comprehensive perspective of the diversity of
proteins such as histones, which are regulated by post-translational
modifications. Here, we report the characterization of modified forms of HeLa
cell histone H4 with a dynamic range >10(4) using a strictly Top Down mass
spectrometric approach coupled with two dimensions of liquid chromatography.
This enhanced dynamic range enabled the precise characterization and
quantitation of 42 forms uniquely modified by combinations of methylation and
acetylation, including those with trimethylated Lys-20, monomethylated Arg-3,
and the novel dimethylated Arg-3 (each <1% of all H4 forms). Quantitative
analyses revealed distinct trends in acetylation site occupancy depending on
Lys-20 methylation state. Because both modifications are dynamically regulated
through the cell cycle, we simultaneously investigated acetylation and
methylation kinetics through three cell cycle phases and used these data to
statistically assess the robustness of our quantitative analysis. This work
represents the most comprehensive analysis of histone H4 forms present in human
cells reported to date. Transcriptional states are formed and maintained by the interaction and
post-translational modification (PTM) of several chromatin proteins, such as
histones and high mobility group (HMG) proteins. Among these, HMGA1a, a small
heterochromatin-associated nuclear protein has been shown to be
post-translationally modified, and some of these PTMs have been linked to
apoptosis and cancer. In cancerous cells, HMGA1a PTMs differ between metastatic
and nonmetastatic cells, suggesting the existence of an HMGA1a PTM code
analogous to the "histone code." In this study, we expand on current knowledge
by comprehensively characterizing PTMs on HMGA1a purified from human cells using
both oflow liquid chromatography collision activated dissociation mediated
Bottom Up and electron-transfer dissociation facilitated middle and Top Down
mass spectrometry (MS). We find HMGA1a to be pervasively modified with many
types of modifications such as methylation, acetylation, and phosphorylation,
including finding novel sites. While Bottom Up MS identified lower level
modification sites, Top and Middle Down MS were utilized to identify the most
commonly occurring combinatorially modified forms. Remarkably, although we
identify several individual modification sites through our Bottom Up and Middle
Down MS analyses, we find relatively few combinatorially modified forms dominate
the population through Top Down proteomics. The main combinatorial PTMs we find
through the Top Down approach are N-terminal acetylation, Arg25 methylation
along with phosphorylation of the three most C-terminal serine residues in
primarily a diphosphorylated form. This report presents one of the most detailed
analyses of HMGA1a to date and illustrates the strength of using a combined MS
effort. Detailed characterization of the amino acid (aa) compositions of recombit
histone H3 (Xenopus laevis) and its Lys-9 mono-, di-, and trimethylated isoforms
was carried out by ESI/FT-ICR-MS. The measured molecular masses of these four
proteins did not agree with those predicted from the published wild-type histone
H3 sequence. Using MS/MS with both collision-activated dissociation and electron
capture dissociation, three aa substitutions (Gly102Ala, Cys110Ala, and
Gly111Ala) were unambiguously identified in each protein by protein database
searching and de novo peptide tag sequencing. In addition, it was determined
through accurate mass measurement and elemental composition generation that
Lys-9, to which the methyl groups are attached, is not in fact a lysine.
Instead, it was identified as a chemical analog of
lysine--aminoethylcysteine--in the methylated proteins. After incorporation of
these three aa substitutions and the aminoethylcysteine into the protein
sequences, the re-calculated molecular masses of four proteins were completely
consistent with the measured values within 1 ppm. This work demonstrates the
power of top-down MS for a detailed structural confirmation of recombit
proteins, even without prior information on aa substitutions or modifications. Applying high-throughput Top-Down MS to an entire proteome requires a
yet-to-be-established model for data processing. Since Top-Down is becoming
possible on a large scale, we report our latest software pipeline dedicated to
capturing the full value of intact protein data in automated fashion. For intact
mass detection, we combine algorithms for processing MS1 data from both
isotopically resolved (FT) and charge-state resolved (ion trap) LC-MS data,
which are then linked to their fragment ions for database searching using
ProSight. Automated determination of human keratin and tubulin isoforms is one
result. Optimized for the intricacies of whole proteins, new software modules
visualize proteome-scale data based on the LC retention time and intensity of
intact masses and enable selective detection of PTMs to automatically screen for
acetylation, phosphorylation, and methylation. Software functionality was
demonstrated using comparative LC-MS data from yeast strains in addition to
human cells undergoing chemical stress. We further these advances as a key
aspect of realizing Top-Down MS on a proteomic scale. An online metal-free weak cation exchange-hydrophilic interaction LC/RPLC system
has been developed for sensitive, high-throughput top-down MS. Here, we report
results for analyzing PTMs of core histones, with a focus on histone H4, using
this system. With just ∼24 μg on-column of core histones (H4, H2B, H2A, and H3)
purified from human fibroblasts, 41 H4 isoforms were identified, with the type
and location of PTMs unambiguously mapped for 20 of these variants. Compared to
corresponding offline studies reported previously, the online weak cation
exchange-hydrophilic interaction LC/RPLC platform offers significant improvement
in sensitivity, with several orders of magnitude reduction in sample
requirements and a reduction in the overall analysis time. To the best of our
knowledge, this study represents the first online 2-D LC-MS/MS characterization
of core histone mixture at the intact protein level. Recent technological advancements have allowed for highly-sophisticated mass
spectrometry-based studies of the histone code, which predicts that combinations
of post-translational modifications (PTMs) on histone proteins result in defined
biological outcomes mediated by effector proteins that recognize such marks.
While significant progress has been made in the identification and
characterization of histone PTMs, a full appreciation of the complexity of the
histone code will require a complete understanding of all the modifications that
putatively contribute to it. Here, using the top-down mass spectrometry approach
for identifying PTMs on full-length histones, we report that lysine 37 of
histone H2B is dimethylated in the budding yeast Saccharomyces cerevisiae. By
generating a modification-specific antibody and yeast strains that harbor
mutations in the putative site of methylation, we provide evidence that this
mark exist in vivo. Importantly, we show that this lysine residue is highly
conserved through evolution, and provide evidence that this methylation event
also occurs in higher eukaryotes. By identifying a novel site of histone
methylation, this study adds to our overall understanding of the complex number
of histone modifications that contribute to chromatin function. Mass spectrometry (MS) is rapidly becoming an indispensable tool for the
analysis of posttranslational modifications (PTMs) of proteins, and particularly
histone PTMs that regulate physiological processes. The more traditional
bottom-up approach of searching for modifications on peptides rather than intact
proteins (top-down) has proven useful for finding phosphorylation, acetylation,
and ubiquitination sites. With the use of modern instrumentation and various
MS-based techniques, peptides and their PTMs can be characterized in a
high-throughput manner while still maintaining high sensitivity and specificity.
In complement to bottom-up MS, recent advances in MS technology, such as
high-field Fourier transform ion cyclotron resoce (FTICR)-mass spectrometry,
have permitted the study of intact proteins and their modifications. On-line and
off-line protein separation instruments coupled to FTICR-MS allow the
characterization of PTMs previously undetectable with bottom-up approaches. The
use of unique fragmentation techniques in FTICR-MS provides a viable option for
the study of labile modifications. In this chapter, we provide a detailed
description of the analytical tools - mass spectrometry in particular - that are
used to characterize modifications on peptides and proteins. We also examine the
applicability of these mass spectrometric techniques to the study of PTMs on
histones via both the bottom-up and top-down proteomics approaches. Chromatin is a highly structured nucleoprotein complex made of histone proteins
and DNA that controls nearly all DNA-dependent processes. Chromatin plasticity
is regulated by different associated proteins, post-translational modifications
on histones (hPTMs) and DNA methylation, which act in a concerted manner to
enforce a specific "chromatin landscape", with a regulatory effect on gene
expression. Mass Spectrometry (MS) has emerged as a powerful analytical strategy
to detect histone PTMs, revealing interplays between neighbouring PTMs and
enabling screens for their readers in a comprehensive and quantitative fashion.
Here we provide an overview of the recent achievements of state-of-the-art mass
spectrometry-based proteomics for the detailed qualitative and quantitative
characterization of histone post-translational modifications, histone variants,
and global interactomes at specific chromatin regions. This synopsis emphasizes
how the advances in high resolution MS, from "Bottom Up" to "Top Down" analysis,
together with the uptake of quantitative proteomics methods by chromatin
biologists, have made MS a well-established method in the epigenetics field,
enabling the acquisition of original information, highly complementary to that
offered by more conventional, antibody-based, assays. |
What is situs inversus? | Situs inversus totalis is a rare congenital anomaly with a complete mirror image of the thoracic and abdominal organs. | The authors reported a 73-year-old alcoholic man with previously-unrecognized
situs inversus totalis suffering from left upper quadrant pain. Acute myocardial
infarction was diagnosed and coronary angioplasty was performed immediately.
However, the massive bleeding from the previously-unfound hepatomas caused
hypovolemic shock and fatal outcome. Situs inversus totalis is a rare congenital
anomaly with a complete mirror image of the thoracic and abdominal organs.
Although being considered a benign entity, it would disturb diagnosis-making of
the visceral diseases owing to the altered anatomy. To our knowledge, the
coexistence of the coronary artery disease and ruptured hepatomas in situs
inversus totalis, as in our patient, is never described. Recognition of any
situs anomalies in time is the key to avoid misdiagnosis, inappropriate
managements, and unwanted consequences. INTRODUCTION: Situs inversus totalis (SIT) is an uncommon congenital syndrome,
which refers to a reversal mirror-image of the normal thoracoabdominal organs
position. The coexistence of SIT and abdominal aortic aneurysm has been seldom
previously reported.
PRESENTATION OF THE CASE: We report a case of a 69-year-old man with SIT and
infrarenal abdominal aortic aneurysm (AAA) that underwent open repair with a
straight graft through a minilaparatomy without evisceration.
DISCUSSION: There is no consensus on which should be the optimum approach in
cases of open surgical repair of AAA due to the limited number of cases
described. The fact of intestinal scrolling to the left abdomen, unlike usual,
is due to the anatomical arrangement of the root of the mesentery which is
directed obliquely from duodenojejunal on the left side of the vertebra L2 to
the ileocecal junction and right sacroiliac joint.
CONCLUSION: A minilaparotomy without evisceration and with intestinal scrolling
to left hemiabdomen, can be very useful and beneficial on those cases of
congenital anatomical abnormalities that may add difficulty during the surgical
procedure. INTRODUCTION: Situs inversus totalis (SIT) represents a total vertical
transposition of the thoracic and abdominal organs which are arranged in a
mirror image reversal of the normal positioning. We presented a successful
pre-dialysis kidney transplantation from a living sibling donor with SIT and the
longest donor follow-up period, along with analysis of the reviewed literature.
CASE REPORT: The pair for pre-dialysis kidney transplantation included a
68-year-old mother and 34-year-old daughter at low immunological risk. Comorbid-
ities evidenced in kidney donors with previously diagnosed SIT, included
moderate arterial hypertension and borderline blood glucose level. Explantation
of the left donor kidney and its placement into the right iliac fossa of the
recipient were performed in the course of the surgical procedure. A month after
nephrectomy, second degree renal failure was noticed in the donor. A 20-month
follow-up of the donor's kidney and graft in the recipient proved that their
functions were excellent.
CONCLUSION: In donors with previously di- agnosed SIT the multidisciplinary
approach, preoperative evaluation of the patient and detection of possible
vascular anomalies are required to provide maximum safety for the donor. BACKGROUND: Situs inversus totalis is a relatively rare condition and is an
autosomal recessive congenital defect in which an abdominal and/or thoracic
organ is positioned as a "mirror image" of the normal position in the sagittal
plane. We report our experience of laparoscopic-assisted total gastrectomy with
lymph node dissection performed for gastric cancer in a patient with situs
inversus totalis.
CASE PRESENTATION: A 58-year-old male was diagnosed with cT1bN0N0 gastric
cancer. There were no vascular anomalies on abdominal angiographic computed
tomography with three-dimensional reconstruction. laparoscopic-assisted total
gastrectomy was performed with D1+ lymph node dissection, in accordance with the
Japanese Gastric Cancer Treatment Guidelines. There were no intraoperative
issues, and no postoperative complications.
CONCLUSIONS: This was the first report describing laparoscopic-assisted total
gastrectomy with the standard typical lymph node dissection in the English
literature. We emphasize that the position of trocars and the standing side of
the primary surgeon during the lymph node dissection are critical. Agnathia, holoprosencephaly and situs inversus complex is an extremely rare form
of congenital malformation. Though a few cases have been reported from other
parts of the world, to the best of our knowledge none has been reported from
India so far. Maternal alcoholism is regarded as an important factor causing
holoprosencephaly. Disruption of the Shh gene signaling pathway is also said to
be a factor for the occurrence of holoprosencephaly as well as left right
asymmetry. Though several factors are suspected as a cause of this deformity,
the precise aetiopathogenesis is still under debate. Lack of knowledge might be
due to paucity of data from cases due to its rarity. Hereby, we are presenting a
case of agnathia, holoprosencephaly and situs inversus born at 32 wk of
gestation by an alcoholic mother. Externally the child had agnathia and
cyclopia. There was no mandible or any oral cavity. It was accompanied by
noticeable limb deformity. Internally there was holoprosencephaly, situs
inversus totalis with several visceral abnormalities. To the best of our
knowledge this is the first case of agnathia, holoprosencephaly and situs
inversus complex to be reported in an indexed literature from India. This report
also strengthens the association of maternal alcoholism with occurrence of
holoprosencephaly. Situs inversus totalis is a rare congenital anomaly in which position of the
heart and all abdominal viscera is reversed. Situs abnormalities usually go
unnoticed but may be recognized by radiography or ultrasonography as an
incidental finding or during evaluation for congenital heart diseases. We
present such an extremely rare and to the best of our knowledge the third
reported case of an injured spleen in the right hypochondrium, following
seemingly trivial blunt trauma in a patient with situs inversus totalis who
underwent splenectomy. The presence of associated congenital heart defects,
visceral anatomical variations and mirror imaging makes the anaesthetic
management as well as the surgical exercise a challenging one in such cases. |
Can SUMO affect calcium homeostasis? | Yes, SUMO proteins can affect calcium homeostasis. | The calcium-transporting ATPase ATP2A2, also known as SERCA2a, is a critical
ATPase responsible for Ca(2+) re-uptake during excitation-contraction coupling.
Impaired Ca(2+) uptake resulting from decreased expression and reduced activity
of SERCA2a is a hallmark of heart failure. Accordingly, restoration of SERCA2a
expression by gene transfer has proved to be effective in improving cardiac
function in heart-failure patients, as well as in animal models. The small
ubiquitin-related modifier (SUMO) can be conjugated to lysine residues of target
proteins, and is involved in many cellular processes. Here we show that SERCA2a
is SUMOylated at lysines 480 and 585 and that this SUMOylation is essential for
preserving SERCA2a ATPase activity and stability in mouse and human cells. The
levels of SUMO1 and the SUMOylation of SERCA2a itself were greatly reduced in
failing hearts. SUMO1 restitution by adeno-associated-virus-mediated gene
delivery maintained the protein abundance of SERCA2a and markedly improved
cardiac function in mice with heart failure. This effect was comparable to
SERCA2A gene delivery. Moreover, SUMO1 overexpression in isolated cardiomyocytes
augmented contractility and accelerated Ca(2+) decay. Transgene-mediated SUMO1
overexpression rescued cardiac dysfunction induced by pressure overload
concomitantly with increased SERCA2a function. By contrast, downregulation of
SUMO1 using small hairpin RNA (shRNA) accelerated pressure-overload-induced
deterioration of cardiac function and was accompanied by decreased SERCA2a
function. However, knockdown of SERCA2a resulted in severe contractile
dysfunction both in vitro and in vivo, which was not rescued by overexpression
of SUMO1. Taken together, our data show that SUMOylation is a critical
post-translational modification that regulates SERCA2a function, and provide a
platform for the design of novel therapeutic strategies for heart failure. The axon/dendrite specification collapsin response mediator protein 2 (CRMP2)
bidirectionally modulates N-type voltage-gated Ca ( 2+) channels (CaV2.2). Here
we demonstrate that small ubiquitin-like modifier (SUMO) protein modifies CRMP2
via the SUMO E2-conjugating enzyme Ubc9 in vivo. Removal of a SUMO conjugation
site KMD in CRMP2 (K374A/M375A/D376A; CRMP2AAA) resulted in loss of SUMOylated
CRMP2 without compromising neurite branching, a canonical hallmark of CRMP2
function. Increasing SUMOylation levels correlated inversely with calcium influx
in sensory neurons. CRMP2 deSUMOylation by SUMO proteases SENP1 and SENP2
normalized calcium influx to those in the CRMP2AAA mutant. Thus, our results
identify a novel role for SUMO modification in CRMP2/CaV2.2 signaling pathway. The rapid, activity-dependent quantal presynaptic release of neurotransmitter is
vital for brain function. The complex process of vesicle priming, fusion, and
retrieval is very precisely controlled and requires the spatiotemporal
coordination of multiple protein-protein interactions. Here, we show that
posttranslational modification of the active zone protein Rab3-interacting
molecule 1α (RIM1α) by the small ubiquitin-like modifier 1 (SUMO-1) functions as
a molecular switch to direct these interactions and is essential for fast
synaptic vesicle exocytosis. RIM1α SUMOylation at lysine residue K502
facilitates the clustering of CaV2.1 calcium channels and enhances the Ca(2+)
influx necessary for vesicular release, whereas non-SUMOylated RIM1α
participates in the docking/priming of synaptic vesicles and maintece of
active zone structure. These results demonstrate that SUMOylation of RIM1α is a
key determit of rapid, synchronous neurotransmitter release, and the
SUMO-mediated "switching" of RIM1α between binding proteins provides insight
into the mechanisms underpinning synaptic function and dysfunction. |
What is the indication of Daonil (Glibenclamide)? | Glibenclamide is an antidiabetic and antiglycemic, used in severe NIDDM, and increasingly viewed as a rational alternative to insulin therapy. | We have investigated the presence of diazoxide- and nicorandil-activated K+
channels in rat skeletal muscle. Activation of potassium transport in the rat
skeletal muscle myoblast cell line L6 caused a stimulation of cellular oxygen
consumption, implying a mitochondrial effect. Working with isolated rat skeletal
muscle mitochondria, both potassium channel openers (KCOs) stimulate
respiration, depolarize the mitochondrial inner membrane and lead to oxidation
of the mitochondrial NAD-system in a strict potassium-dependent manner. This is
a strong indication for KCO-mediated stimulation of potassium transport at the
mitochondrial inner membrane. Moreover, the potassium-specific effects of both
diazoxide and nicorandil on oxidative phosphorylation in skeletal muscle
mitochondria were completely abolished by the antidiabetic sulfonylurea
derivative glibenclamide, a well-known inhibitor of ATP-regulated potassium
channels (K(ATP) channels). Since both diazoxide and nicorandil facilitated
swelling of de-energised mitochondria in KSCN buffer at the same concentrations,
our results implicate the presence of a mitochondrial ATP-regulated potassium
channel (mitoK(ATP) channel) in rat skeletal muscle which can modulate
mitochondrial oxidative phosphorylation. 1. The hypoglycaemic effect of fermented seeds of Parkia biglobosa (PB; African
locust bean), a natural nutritional condiment that features frequently in some
African diets as a spice, was investigated in the present study in
alloxan-induced diabetic rats. Its effect was compared with that of
glibenclamide (Daonil; Sanofi-Aventis, Paris, France), a reference antidiabetic
drug. The effects of PB on lipid profiles were also examined. 2. In order to
assess the hypoglycaemic and hypolipidaemic effects of aqueous and methanolic
extracts of PB on experimental animals, fasting plasma glucose (FPG), total
cholesterol, triglyceride, high-density lipoprotein (HDL) and low-density
lipoprotein (LDL) were determined. In addition, the weight of each animal was
determined to assess any possible weight gain or loss in the experimental
animals (diabetic rats treated with Daonil (group C), the aqueous extract of PB
(group D) or the methanolic extract of PB (group E)) compared with control
groups (non-diabetic (group A) and non-treated diabetic (group B)). 3. A single
dose of 120 mg/kg, i.v., alloxan administered to rats resulted in significant
increases in the FPG (P < 0.001) of test animals compared with controls.
However, dietary supplementation with PB (6 g/kg extract for 4 weeks
administered orally using an intragastric tube) ameliorated the alloxan-induced
diabetes in a manner comparable with that of the reference antidiabetic drug
glibenclamide. Aqueous and methanolic extracts of PB (6% w/w) elicited 69.2% and
64.4% reductions, respectively, in FPG compared with 70.4% in 0.01 mg/150 g
glibenclamide-treated rats. 4. Although animals treated with the aqueous extract
of PB gained weight in manner similar to normal controls, animals given the
methanolic extract and glibenclamide lost weight in manner similar to
non-treated diabetic rats. In addition, high levels of HDL and low LDL were
observed in animals treated with the aqueous extract of PB, a pattern similar to
that seen in normal controls. Low levels of HDL and high levels of LDL were
observed in animals treated with the methanolic extract of PB, a pattern similar
to that seen in non-treated diabetic controls. 5. The results of the present
study demonstrate that both aqueous and methanolic extracts of fermented seeds
of PB exert a hypoglycaemic effect; hence, PB has an antidiabetic property.
However, only the aqueous extract of PB ameliorated the loss of bodyweight
usually associated with diabetes. Although the aqueous extract has a favourable
lipid profile, which is probably an indication of its possible anti-arteriogenic
property (hypertension and ischaemic heart diseases being common complications
in diabetes mellitus), the methanolic extract shows possible contraindication to
ischaemic heart diseases. |
Which is the most typical peptide sequence responsible for retrieval of endoplasmic reticulum (ER) lumenal proteins from the Golgi apparatus? | The lumenal endoplasmic reticulum (ER) proteins carry a specific sorting signal which enables their retrieval from multiple post-ER compartments (up to the TGN along the exocytotic pathway), back to the ER. The most typical such signal is the carboxyl-terminal Lys-Asp-Glu-Leu (KDEL), which is bound by a KDEL receptor in the Golgi apparatus, as well as in the intermediate compartment. Thus KDEL functions as a retrieval signal of lumenal ER proteins from Golgi to ER. | In eukaryotic cells, protein secretion provides a complex organizational
problem. Secretory proteins are first transported, in an unfolded state, across
the membrane of the endoplasmic reticulum (ER), and are then carried in small
vesicles to the Golgi apparatus and finally to the cell membrane. The ER
contains soluble proteins which catalyse the folding of newly synthesized
polypeptides. These proteins are sorted from secretory proteins in the Golgi
complex: they carry a sorting signal (the tetrapeptide KDEL or a related
sequence) that allows them to be selectively retrieved and returned to the ER.
This retrieval process also appears to be used by some bacterial toxins to aid
their invasion of the cell: these toxins contain KDEL-like sequences and may, in
effect, follow the secretory pathway in reverse. The membrane-bound receptor
responsible for sorting luminal ER proteins has been identified in yeast by
genetic means, and related receptors are found in mammalian cells. Unexpectedly,
this receptor has a second role: in yeast it is required to maintain the normal
size and function of the Golgi apparatus. By helping to maintain the composition
of both ER and Golgi compartments, the KDEL receptor has an important role in
the organization of the secretory pathway. The carboxyl-terminal Lys-Asp-Glu-Leu (KDEL), or a closely-related sequence, is
important for ER localization of both lumenal as well as type II membrane
proteins. This sequence functions as a retrieval signal at post-ER
compartment(s), but the exact compartment(s) where the retrieval occurs remains
unresolved. With an affinity-purified antibody against the carboxyl-terminal
sequence of the mammalian KDEL receptor, we have investigated its subcellular
localization using immunogold labeling on thawed cryosections of different
tissues, such as mouse spermatids and rat pancreas, as well as HeLa, Vero, NRK,
and mouse L cells. We show that rab1 is an excellent marker of the intermediate
compartment, and we use this marker, as well as budding profiles of the mouse
hepatitis virus (MHV) in cells infected with this virus, to identify this
compartment. Our results demonstrate that the KDEL receptor is concentrated in
the intermediate compartment, as well as in the Golgi stack. Lower but
significant labeling was detected in the rough ER. In general, only small
amounts of the receptor were detected on the trans side of the Golgi stack,
including the trans-Golgi network (TGN) of normal cells and tissues. However,
some stress conditions, such as infection with vaccinia virus or vesicular
stomatitis virus, as well as 20 degrees C or 43 degrees C treatment, resulted in
a significant shift of the distribution towards the trans-TGN side of the Golgi
stack. This shift could be quantified in HeLa cells stably expressing a TGN
marker. No significant labeling was detected in structures distal to the TGN
under all conditions tested. After GTP gamma S treatment of permeabilized cells,
the receptor was detected in the beta-COP-containing buds/vesicles that
accumulate after this treatment, suggesting that these vesicles may transport
the receptor between compartments. We propose that retrieval of KDEL-containing
proteins occurs at multiple post-ER compartments up to the TGN along the
exocytotic pathway, and that within this pathway, the amounts of the receptor in
different compartments varies according to physiological conditions. The secretory pathway of eukaryotic cells consists of a number of distinct
membrane-bound compartments interconnected by vesicular traffic. Each
compartment has a characteristic content of proteins and lipids, which must be
maintained. This is achieved in most cases by active sorting-proteins may reach
the wrong compartment but are continually retrieved. A good example is the
retrieval system for lumenal ER proteins. These proteins carry a specific
sorting signal, typically the tetrapeptide KDEL, which is bound by a receptor in
the Golgi apparatus. The receptor-ligand complex, together with escaped ER
membrane proteins, returns to the ER. Many of the components of vesicle traffic,
including the coat proteins required for vesicle budding from the ER, those that
form retrograde vesicles on post-ER compartments, and integral membrane proteins
that target the vesicles to their correct destination, have been identified. The
sorting events that occur can largely be understood in terms of specific
protein-protein interactions involving these components. However, sorting of
some membrane proteins, including the vesicle targeting molecules, is influenced
by their transmembrane domains, and it is likely that segregation of these is
dependent on the composition and biophysical properties of the lipid bilayer,
which very between compartments. The secretory pathway is thus a dynamic entity,
split into discrete organelles by the constant segregation and recycling of
lipids and proteins, processes that are ultimately driven by the mechanics of
vesicle formation and fusion. Retention of soluble proteins in the endoplasmic reticulum is dependent on their
interaction with the KDEL (Lys-Asp-Glu-Leu) receptor in the Golgi apparatus and
their subsequent retrieval back to the endoplasmic reticulum. We have studied
the three-dimensional organization of the human KDEL receptor using
site-directed mutagenesis and sulfhydryl-specific labeling. We have identified
four amino acid residues, Arg-5, Asp-50, Tyr-162, and Asn-165, which we suggest
participate in the formation of the ligand binding pocket. Arg-5 and Asp-50 are
shown to be located on the lumenal side of the membrane and are inaccessible
from the cytoplasm. In addition, our results strongly support a topology of the
KDEL receptor similar to the family of G-protein-coupled receptors with seven
transmembrane domains. Furthermore, Asp-50 plays a crucial role in the binding
of His/Lys-Asp-Glu-Leu ligands, but is not required for Asp-Asp-Glu-Leu binding,
suggesting that this residue forms an ion pair with the positively charged amino
acid residue positioned 4 residues from the carboxyl terminus of the ligand. To investigate the role of the KDEL receptor in the retrieval of protein toxins
to the mammalian cell endoplasmic reticulum (ER), lysozyme variants containing
AARL or KDEL C-terminal tags, or the human KDEL receptor, have been expressed in
toxin-treated COS 7 and HeLa cells. Expression of the lysozyme variants and the
KDEL receptor was confirmed by immunofluorescence. When such cells were
challenged with diphtheria toxin (DT) or Escherichia coli Shiga-like toxin 1
(SLT-1), there was no observable difference in their sensitivities as compared
to cells which did not express these exogenous proteins. By contrast, the
cytotoxicity of Pseudomonas exotoxin A (PE) is reduced by expressing
lysozyme-KDEL, which causes a redistribution of the KDEL receptor from the Golgi
complex to the ER, and cells are sensitised to this toxin when they express
additional KDEL receptors. These data suggest that, in contrast to SLT-1, PE can
exploit the KDEL receptor in order to reach the ER lumen where it is believed
that membrane transfer to the cytosol occurs. This contention was confirmed by
microinjecting into Vero cells antibodies raised against the cytoplasmically
exposed tail of the KDEL receptor. Immunofluorescence confirmed that these
antibodies prevented the retrograde transport of the KDEL receptor from the
Golgi complex to the ER, and this in turn reduced the cytotoxicity of PE, but
not that of SLT-1, to these cells. Hydroxylation of lysyl residues is crucial for the unique glycosylation pattern
found in collagens and for the mechanical strength of fully assembled
extracellular collagen fibers. Hydroxylation is catalyzed in the lumen of the
endoplasmic reticulum (ER) by a specific enzyme, lysyl hydroxylase (LH). The
absence of the known ER-specific retrieval motifs in its primary structure and
its association with the ER membranes in vivo have suggested that the enzyme is
localized in the ER via a novel retention/retrieval mechanism. We have
identified here a 40-amino acid C-terminal peptide segment of LH that is able to
convert cathepsin D, normally a soluble lysosomal protease, into a
membrane-associated protein. The same segment also markedly slows down the
transport of the reporter protein from the ER into post-ER compartments, as
assessed by our pulse-chase experiments. The retardation efficiency mediated by
this C-terminal peptide segment is comparable with that of the intact LH but
lower than that of the KDEL receptor-based retrieval mechanism. Within this
40-amino acid segment, the first 25 amino acids appear to be the most crucial
ones in terms of membrane association and ER localization, because the last 15
C-terminal amino acids did not possess substantial retardation activity alone.
Our findings thus define a short peptide segment very close to the extreme C
terminus of LH as the only necessary determit both for its membrane
association and localization in the ER. |
What are the clinical trial outcomes of metformin use in polycystic ovary disease? | Metformin treatment vs placebo significantly but modestly improves ovulation frequency in women with abnormal ovarian function/oligomenorrhea and polycystic ovaries, the lower BMI women were more likely to become pregnant. While in naturally conceiving normal weight PCOS women pre-treatment with metformin tends to improve pregnancy rates, pre-treatment with metformin prior to conventional IVF/ICSI in women with PCOS does not improve stimulation or clinical outcome.
Metformin is an effective addition to Clomifene Citrate in term of reestablishment of ovulation and full-term pregnancies achievement.
Studies on the effect of metformin on serum Anti-Mullerian Hormone levels /AMH concentrations bring conflicting results, from Metformin having no effect on AMH to Metformin treatment resulting in significant decrease of AMH levels, antral follicle numbers and ovarian volume.
Metformin has been shown to cause significant weight loss (and leptin reduction) in PCOS. | BACKGROUND: Metformin, an insulin-sensitizing agent, has been used successfully
as the first-line drug to induce ovulation in women with polycystic ovary
syndrome. There are, however, very few studies evaluating metformin treatment in
women with clomiphene citrate (CC)-resistant polycystic ovaries (PCO).
METHODS: Twenty infertile Chinese women aged <40 years, who had ultrasound
features of PCO and remained anovulatory on CC, were randomized by computer
using the sealed envelope method to receive placebo or metformin 500 mg three
times a day for 3 months. Hormonal and metabolic profiles were determined before
the therapy and were repeated after 3 months for women who failed to become
pregt within this period. Clomiphene was then added for one cycle to those
women who did not ovulate after taking placebo or metformin alone.
RESULTS: The median ovulation rate in the placebo group was 0% (range: 0--50%)
after placebo only and 6.9% (range: 0--50%) after placebo and CC, whereas the
corresponding rates in the metformin group were 0% (range: 0--22%) and 0%
(range: 0--22%) respectively. There was no improvement in the ovulation rate
despite a significant reduction of body mass index, serum testosterone and
fasting leptin concentrations in the metformin group.
CONCLUSIONS: Metformin treatment may result in successful ovulation only in
certain subgroups of these women. Women with oligomenorrhea and polycystic ovaries show a high incidence of
ovulation failure perhaps linked to insulin resistance and related metabolic
features. A number of reports show that the biguanide metformin improves ovarian
function. However, in these trials the quality of evidence supporting ovulation
is suboptimal, and few studies have been placebo-controlled. The aim of our
study was to use a double-blind, placebo-controlled approach with detailed
assessment of ovarian activity (two blood samples per week) to assess the
validity of this therapeutic approach in this group of women. Of the 94 patients
randomized, 2 withdrew before treatment commenced, 47 received placebo, and 45
received metformin (850 mg, twice a day). The numbers discontinuing the study
prematurely were higher in the treatment group (n = 15) than the placebo group
(n = 5; P < 0.05). The ovulation frequency assessed by the ratio of luteal phase
weeks to observation weeks was significantly (P < 0.01) higher in the treated
group (23%) compared with the placebo (13%), and the time to first ovulation was
significantly (P < 0.05) shorter [23.6 d; 95% confidence interval (CI), 17, 30;
compared with 41.8 d; 95% CI, 28, 56]. The proportion of patients failing to
ovulate during the placebo-treatment period was higher (P < 0.05) in the placebo
group, and the majority of ovulations were characterized by normal progesterone
concentrations in both groups. The effect of metformin on follicular maturation
was rapid, because the E2 circulating concentration increased over the first
week of treatment only in the metformin group. Significant (P < 0.01) weight
loss (and leptin reduction) was recorded in the metformin group, whereas the
placebo group actually increased weight (P < 0.05). A significant increase in
circulating high-density lipoprotein was observed only in the metformin-treated
group. Metabolic risk factor benefits of metformin treatment were not observed
in the morbidly obese subgroup of patients (body mass index > 37). No change in
fasting glucose concentrations, fasting insulin, or insulin responses to glucose
challenge was recorded after 14-wk metformin or placebo therapy. There was an
inverse relationship between body mass and treatment efficacy. We show in a
large randomized placebo-controlled trial that metformin treatment improves
ovulation frequency in women with abnormal ovarian function and polycystic
ovaries significantly but to a modest degree, and protracted treatment improves
cardiovascular risk factors. These data support a beneficial effect of metformin
in improving ovarian function in women with oligomenorrhea and polycystic
ovaries. The syndrome of polycystic ovaries (PCOS) is associated with adiposity and
metabolic changes predisposing to insulin resistance and diabetes mellitus.
Because the recently discovered GH secretagogue, ghrelin, is intimately involved
in the control of appetite and weight regulation, we studied ghrelin levels in a
group of 26 otherwise healthy women with PCOS. They were compared with 61
healthy female control subjects and 5 gastrectomized women. Insulin sensitivity
was assessed by homeostasis model assessment (HOMA) and continuous infusion of
glucose with model assessment (CIGMA) in all patients. In PCOS women, serum
ghrelin levels were significantly lower than in healthy lean or obese controls
(P < 0.001). In insulin-sensitive PCOS women, ghrelin concentrations compared
well with the healthy controls, whereas in insulin-resistant PCOS ghrelin levels
were significantly lower and indistinguishable from the low levels found in the
gastrectomized women. There was a close correlation of ghrelin to insulin
sensitivity (HOMA, r(2) = 0.330, P < 0.002; CIGMA, r(2) = 0.568, P < 0.0001).
Treatment of 10 insulin-resistant PCOS women with metformin significantly
increased circulating fasting ghrelin concentrations (P < 0.02). Ghrelin levels
did not correlate to any of the parameters of hyperandrogenemia, to the LH/FSH
ratio, to body mass index, or to fasting insulin and glucose concentrations. In
summary, ghrelin levels are decreased in PCOS women and are highly correlated to
the degree of insulin resistance. This suggests that ghrelin could be linked to
insulin resistance in PCOS women. However, whether low ghrelin in PCOS is a
cause or the consequence of insulin resistance awaits further investigations. BACKGROUND: Our aim was to investigate the effect of pre-treatment with
metformin in women with polycystic ovary syndrome (PCOS) scheduled for IVF
stimulation.
METHODS: Seventy-three oligo/amenorrhoeic women with polycystic ovaries and at
least one of the following criteria: hyperandrogenaemia, elevated LH/FSH ratio,
hyperinsulinism, decreased SHBG levels or hirsutism, were studied. Normal weight
and overweight patients were randomized separately in a prospective, randomized,
double blind study. All patients were treated for at least 16 weeks with
metformin (1000 mg bid) or placebo ending on the day of HCG injection.
RESULTS: No differences were found in the primary end-points: duration of FSH
stimulation 14.4 (13.1-15.7) versus 14.2 (12.6-15.7) days or estradiol on the
day of HCG injection 6.8 (5.3-8.2) versus 7.6 (5.6-9.6) nmol/l in the metformin
and placebo groups, respectively. The secondary end-points number of oocytes,
fertilization rates, embryo quality, pregcy rates and clinical pregcy
rates were equal. However, in the normal weight subgroup (BMI <28 kg/m(2), n =
27), pregcy rates following IVF were 0.71 (0.63-0.79) versus 0.23 (0.15-0.31)
in the metformin and placebo groups, respectively (P = 0.04). Overall clinical
pregcy rates were equal: 0.51 (0.34-0.68) versus 0.44 (0.27-0.62) in the
metformin and placebo groups, respectively. However, in the normal weight
subgroup, clinical pregcy rates were 0.67 (0.43-0.91) and 0.33 (0.06-0.60),
respectively (P = 0.06).
CONCLUSIONS: Pre-treatment with metformin prior to conventional IVF/ICSI in
women with PCOS does not improve stimulation or clinical outcome. However, among
normal weight PCOS women, pre-treatment with metformin tends to improve
pregcy rates. Further studies in subgroups of PCOS women are required. BACKGROUND: Anti-Müllerian hormone (AMH) is secreted by granulosa cells of
ovarian early developing follicles and its serum levels have been shown to
correlate with small antral follicle number. Since the pronounced androgen
secretion from follicles/stroma in women with polycystic ovary syndrome (PCOS)
remains until late reproductive age, and since AMH reflects the number of antral
follicles, it was of interest to study the possible age-related relationship
between AMH, androgens and follicle number in women with PCOS and in control
women. Moreover, the possible effect of metformin on serum AMH levels and the
relationship to follicle count and volume were studied.
METHODS: Forty-four healthy women (aged 21-44 years) and 65 women with
previously diagnosed PCOS (aged 16-44 years) participated in the study. Serum
basal AMH levels were correlated with those of serum androstenedione,
testosterone, estradiol (E2), LH, FSH and inhibin B, and with follicle number.
The effect of metformin on serum AMH concentrations, follicle number and ovarian
volume was studied in 26 women (aged 20-41 years) with PCOS after 6 months of
treatment.
RESULTS: Serum AMH levels were 2- to 3- fold higher in PCOS women than in
healthy women. In control women, serum AMH levels correlated positively with
those of serum androstenedione (r = 0.564, P < 0.001) and testosterone (r =
0.328, P = 0.036) and negatively with serum FSH concentrations (r = -0.374, P =
0.012) and age (r = -0.691, P<0.001). In women with PCOS, serum AMH levels
correlated positively with those of androstenedione (r = 0.311, P = 0.011) and
testosterone (r = 0.310, P = 0.011) and with follicle count (r = 0.352, P =
0.012), and negatively with age (r = -0.300, P = 0.014). Serum AMH levels, the
number of antral follicles and ovarian volume decreased significantly during
metfromin treatment.
CONCLUSIONS: Serum AMH levels decreased with age both in healthy women and in
women with PCOS, although they were always 2- to 3-fold higher and remained
elevated until 40 years of age in PCOS subjects. Thus, since serum AMH levels
correlate well with antral follicle count and serum androgen levels, the
measurement of AMH could be used as a tool to assess ovarian ageing, to diagnose
polycystic ovaries/PCOS and to evaluate treatment efficacy. BACKGROUND: Current data suggest that excessive androgen exposure can lead to
the development of polycystic ovaries and polycystic ovary syndrome (PCOS).
Anti-Müllerian hormone (AMH) levels reflect the number of small antral follicles
in the ovaries and are elevated in PCOS. We hypothesized that protracted
reduction of circulating androgens and/or insulin resistance would reduce
circulating AMH concentrations in women with PCOS.
METHODS: A prospective, randomized, double-blind 26 week long study was
undertaken in 50 women with PCOS. They all received diet and lifestyle
counselling, and metformin 850 mg three times daily. Concomitantly, they were
randomized to either dexamethasone 0.25 mg daily (n = 25) or placebo (n = 25).
Thirty-eight women completed the study. AMH (primary outcome) and other hormone
levels were measured at inclusion and after 8 and 26 weeks of treatment.
RESULTS: At baseline in univariate regression analyses, AMH levels associated
positively with testosterone levels (P = 0.041) and ovarian volume (P = 0.002).
In multivariate regression analyses, AMH associated positively with testosterone
P = 0.004), and negatively with dehydroepiandrosterone sulphate (DHEAS) (P =
0.001) and C-peptide levels (P = 0.020). Circulating AMH concentrations were
unaffected by 6 months of lifestyle counselling with metformin and placebo
treatment. AMH levels were also unaffected by 6 months of androgen suppression
with dexamethasone in addition.
CONCLUSIONS: AMH levels in untreated PCOS women associated positively with
testosterone, and negatively with DHEAS and C-peptide levels. Six months of
androgen suppression by either metformin or low-dose dexamethasone treatment
failed to influence circulating AMH levels. BACKGROUND: Polycystic ovarian syndrome (PCOS) is the most common hormonal
dysfunction in women. It's a cause of female infertility by oligoanovulation,
clinical and biochemical hyperandrogenism and polycystic ovaries. Weight loss,
firstly proposed in overweight or obese patient suffering from PCOS, aims to
reduce hyperinsulinism and hyperandrogenism. Recently, Metformin, an insulin
sensitizer, has been proposed as an alternative first line treatment for
polycystic ovarian syndrome by improving hyperinsulinemia and hyperandrogenism
in these women.
AIM: The aim of our study, and through a literature review, is to demonstrate if
Metformin should be used as a first-line drug for infertile women with this
syndrome or as an adjunction to Clomifene Citrate, the longest established
treatment already used in this syndrome.
METHODS: A prospective comparative study including 63 patients with PCOS has
been done during 2 years. Women were randomly allocated to clomifene + Metformin
(Metformin group, Metformin took during 8 weeks, 850 mg twice a day, plus
Clomifene 100 mg per day during five days) or Clomifene only (100 mg per day
during five days). All patients underwent a two- month's diet.
RESULTS: The middle age was about 30.63 years and the body mass index (BMI) was
about 29.88 kg/ m(2). We noticed a 6.2% weight loss in both groups (a non
significant difference in p=0.04). The median of infertility period was about
2.49 years. The ovulation rate in the Metformin group was 53.12% (significant
difference for inducing ovulation p=0.02) and 32.25% in Clomifene group
(non-significant difference 0.07). There was also a significant difference for
ongoing pregcies (p=0.04). In fact, 11 on 32 patients (34%) achieved a
full-term pregcy in Metformin group versus only 4 ones on 31 patients (12.9%)
in Clomifene group.
CONCLUSION: Our conclusion is that Metformin is an effective addition to
Clomifene Citrate in term of reestablishment of ovulation and full-term
pregcies achievement, excluding ART cycles. BACKGROUND: Metformin has failed to gain wide acceptance as a first-line
treatment option for women with anovulatory infertility related to polycystic
ovary syndrome. This study aimed to ascertain factors that predict fertility
success with treatment that included metformin compared to standard
(non-metformin) treatment.
METHODS: Randomised trial data analysis by logistic regression of factors likely
to have a differential influence on the likelihood of success of metformin
versus non-metformin treatment amongst women with ovulation dysfunction related
to polycystic ovary syndrome.
RESULTS: metformin versus those receiving placebo and those with lower BMI who
received metformin were more likely to become pregt than their lower BMI
counterparts who received placebo (P=0.039). The subpopulation of women with
BMI≤32 kg/m(2) had no factors showing a significantly different impact on the
chance of pregcy for women treated with metformin versus those receiving
clomiphene treatment or combination metformin/clomiphene treatment versus
clomiphene treatment. There were no significantly different effects of free
testosterone, fasting insulin, duration of infertility or ultrasound appearance
of polycystic ovaries in any treatment groups.
CONCLUSION: This study provides preliminary evidence that BMI may be an
important prognostic factor in response to metformin for women with ovulation
dysfunction related to polycystic ovary syndrome, suggesting that women with a
lower BMI may respond better to metformin treatment versus placebo amongst women
with BMI>32 kg/m(2) . Individual patient data meta-analysis of existing
randomised trials would clarify this further and would assess whether other
factors might predict better response to metformin versus standard treatments. AIM: Polycystic ovary syndrome (PCOS) is a multifactorial pathology affecting
5-10% of the female population. Usually occurs with oligo/amenorrhea,
anovulation, hirsutism, polycystic ovaries. Hyperinsulinemia associated with
insulin resistance has been causally linked to all features of the syndrome. It
has been demonstrated that by reducing hyperinsulinemia, in particular with the
administration of metformin, insulin-lowering agents might improve endocrine and
reproductive abnormalities in PCOS patients.
METHODS: A new molecule with insulin-sensitizing properties, myo-inositol, has
recently been successfully administered in women with PCOS. New associations
between natural substances like myo-inositol and other components have been
proposed to improve the therapeutical efficacy. Among these substances, the
monacolin K, a natural statin appeared to have important actions in cholesterol
synthesis. In this article we study the effect of inositol alone and the
association between myo-inositol and monacolinin K in the treatment of PCOS with
insulin resistance, menstrual irregularities and hirsutism.
RESULTS AND CONCLUSION: The results of this study demonstrated a good efficacy
of both treatments, although in the group treated with the combination of
myo-inositol/monacolin K improvement in lipids and hyperandrogenism were
significantly better. |
List the main proteases used for sample digestion in proteomics. | Trypsin is the main protease used in proteomics followed by Asp-N, chymotrypsin, LysC, GluC and thermolysin. | Quantitative proteomics using isobaric labeling typically involves sample
digestion, peptide-level labeling and 2D LC-MS/MS. Proteomic analysis of complex
samples can potentially be performed more comprehensively with GeLC-MS/MS.
However, combining this approach with peptide-level labeling of multiple in-gel
digests from entirely sectioned gel lanes can introduce many points of variation
and adversely affect the final quantitative accuracy. Alternatively, samples
labeled with isobaric tags at the protein level can be combined and analyzed by
GeLC-MS/MS as a single gel lane. A caveat to this strategy is that only lysine
residues are labeled, which might limit protein digestion and quantitation of
peptides. Here we have compared a protein-level labeling GeLC-MS/MS strategy
with a peptide-level labeling 2D LC-MS/MS approach, using mouse hippocampus
synaptosomes and isobaric tandem mass tags. Protein-level labeling enabled the
identification of 3 times more proteins (697 versus 241) than did peptide-level
labeling, and importantly for quantitation, twice as many proteins with labeled
peptides (480 versus 232) were identified. Preliminary in silico analysis also
suggested the alternative use of Asp-N to trypsin to circumvent the interference
of lysine labeling on protein digestion. Use of Asp-N resulted in the effective
analysis of fewer peptides than with trypsin for the protein-level approach
(1677 versus 3131), but yielded a similar quantitative proteomic coverage in
terms of both peptides (1150 versus 1181) and proteins (448 versus 480). Taken
together, these experiments demonstrate that protein-level labeling combined
with GeLC-MS/MS is an effective strategy for the multiplexed quantitation of
synaptosomal preparations, and may also be applicable to samples of a similar
proteomic complexity and dynamic range of protein abundance. Analytical advantages of using multiple enzymes for sample digestion (MED),
primarily an increase of sequence coverage, have been reported in several
studies. However, this approach is only rarely used, mainly because it requires
additional sample and mass spectrometric measurement time. We have previously
described Filter Aided Sample Preparation (FASP), a type of proteomic reactor,
in which samples dissolved in sodium dodecyl sulfate (SDS) are digested in an
ultrafiltration unit. In FASP, such as in any other preparation protocol, a
portion of sample remains after digestion and peptide elution. Making use of
this fact, we here develop a protocol enabling consecutive digestion of the
sample with two or three enzymes. By use of the FASP method, peptides are
liberated after each digestion step and remaining material is subsequently
cleaved with the next proteinase. We observed excellent performance of the
ultrafiltration devices in this mode, allowing efficient separation of
orthogonal populations of peptides, resulting in an increase in the numbers of
identified peptides and proteins. At the low microgram level, we found that the
consecutive use of endoproteinases LysC and trypsin enabled identification of up
to 40% more proteins and phosphorylation sites in comparison to the commonly
used one-step tryptic digestion. MED-FASP offers efficient exploration of
previously unused sample material, increasing depth of proteomic analyses and
sequence coverage. Proteomic profiling of heart tissue might help to discover the molecular events
related to or even causing cardiovascular diseases in human. However, this
material is rare and only available from biopsies taken for diagnostics, e.g.,
assessment of inflammatory events or virus persistence. Within this chapter, we
describe a workflow for the quantitative proteome analysis of heart biopsies.
Starting with 1-2 mg of tissue material, crude protein extracts were prepared,
digested with LysC and trypsin, and then analyzed by LC-ESI-tandem mass
spectrometry. Due to the low technical variance, the method can be used for
label-free quantitation of disease-specific alterations in the human heart.
Methods discussed include homogenization of biopsy tissue, sample preparation,
proteolytic digestion, as well as data analysis for label-free quantitation. Dried blood spots offer many advantages as a sample format including ease and
safety of transport and handling. To date, the majority of mass spectrometry
analyses of dried blood spots have focused on small molecules or hemoglobin.
However, dried blood spots are a potentially rich source of protein biomarkers,
an area that has been overlooked. To address this issue, we have applied an
untargeted bottom-up proteomics approach to the analysis of dried blood spots.
We present an automated and integrated method for extraction of endogenous
proteins from the surface of dried blood spots and sample preparation via
trypsin digestion by use of the Advion Biosciences Triversa Nanomate robotic
platform. Liquid chromatography tandem mass spectrometry of the resulting
digests enabled identification of 120 proteins from a single dried blood spot.
The proteins identified cross a concentration range of four orders of magnitude.
The method is evaluated and the results discussed in terms of the proteins
identified and their potential use as biomarkers in screening programs. Nowadays, mass spectrometry-based proteomics is carried out primarily in a
bottom-up fashion, with peptides obtained after proteolytic digest of a whole
proteome lysate as the primary analytes instead of the proteins themselves. This
experimental setup crucially relies on a protease to digest an abundant and
complex protein mixture into a far more complex peptide mixture. Full knowledge
of the working mechanism and specificity of the used proteases is therefore
crucial, both for the digestion step itself as well as for the downstream
identification and quantification of the (fragmentation) mass spectra acquired
for the peptides in the mixture. Targeted protein analysis through selected
reaction monitoring, a relative newcomer in the specific field of mass
spectrometry-based proteomics, even requires a priori understanding of protease
behavior for the proteins of interest. Because of the rapidly increasing
popularity of proteomics as an analytical tool in the life sciences, there is
now a renewed demand for detailed knowledge on trypsin, the workhorse protease
in proteomics. This review addresses this need and provides an overview on the
structure and working mechanism of trypsin, followed by a critical analysis of
its cleavage behavior, typically simply accepted to occur exclusively yet
consistently after Arg and Lys, unless they are followed by a Pro. In this
context, shortcomings in our ability to understand and predict the behavior of
trypsin will be highlighted, along with the downstream implications.
Furthermore, an analysis is carried out on the inherent shortcomings of trypsin
with regard to whole proteome analysis, and alternative approaches will be
presented that can alleviate these issues. Finally, some reflections on the
future of trypsin as the workhorse protease in mass spectrometry-based
proteomics will be provided. The majority of mass spectrometry-based protein quantification studies uses
peptide-centric analytical methods and thus strongly relies on efficient and
unbiased protein digestion protocols for sample preparation. We present a novel
objective approach to assess protein digestion efficiency using a combination of
qualitative and quantitative liquid chromatography-tandem MS methods and
statistical data analysis. In contrast to previous studies we employed both
standard qualitative as well as data-independent quantitative workflows to
systematically assess trypsin digestion efficiency and bias using mitochondrial
protein fractions. We evaluated nine trypsin-based digestion protocols, based on
standard in-solution or on spin filter-aided digestion, including new optimized
protocols. We investigated various reagents for protein solubilization and
denaturation (dodecyl sulfate, deoxycholate, urea), several trypsin digestion
conditions (buffer, RapiGest, deoxycholate, urea), and two methods for removal
of detergents before analysis of peptides (acid precipitation or phase
separation with ethyl acetate). Our data-independent quantitative liquid
chromatography-tandem MS workflow quantified over 3700 distinct peptides with
96% completeness between all protocols and replicates, with an average 40%
protein sequence coverage and an average of 11 peptides identified per protein.
Systematic quantitative and statistical analysis of physicochemical parameters
demonstrated that deoxycholate-assisted in-solution digestion combined with
phase transfer allows for efficient, unbiased generation and recovery of
peptides from all protein classes, including membrane proteins. This
deoxycholate-assisted protocol was also optimal for spin filter-aided digestions
as compared with existing methods. The in-depth analysis of complex proteome samples requires fractionation of the
sample into subsamples prior to LC-MS/MS in shotgun proteomics experiments. We
have established a 3D workflow for shotgun proteomics that relies on protein
separation by 1D PAGE, gel fractionation, trypsin digestion, and peptide
separation by in-gel IEF, prior to RP-HPLC-MS/MS. Our results show that applying
peptide IEF can significantly increase the number of proteins identified from
PAGE subfractionation. This method delivers deeper proteome coverage and
provides a large degree of flexibility in experimentally approaching highly
complex mixtures by still relying on protein separation according to molecular
weight in the first dimension. Immune complexome analysis is a method for identifying and profiling of antigens
in circulating immune complexes (CICs); it involves separation of immune
complexes from serum, direct tryptic digestion of these complexes, and protein
analysis via o-liquid chromatography-tandem mass spectrometry
(o-LC-MS/MS). To improve this method, we initially investigated the effects
of two factors-the gradient elution program and o-LC column type (C18-packed,
C8-packed, or packed spray capillary column)-on the numbers of peptides and
proteins identified. Longer gradient elution times resulted in higher
identification capability throughout the range of 25-400 min. Moreover, the
packed spray capillary column supported identification of more peptides and
proteins than did any other column. In addition, microwave-assisted digestion
was compared with conventional digestion, which involved incubation overnight at
37 °C. Microwave-assisted digestion produced more partially digested peptides
than did conventional digestion. However, the percentages of miscleaved peptides
in all of the identified peptides in microwave-assisted digestion of immune
complexes (a protein mixture) were lower than those in the physical
stimulation-assisted digestion of a model protein. Microwave-assisted digestion
is slightly inferior to, or as effective as, conventional digestion, but it
drastically reduces the digestion time. Gan et al. (Proteomics 2013, 13, 3117-3123) described a new "macropore" protocol
for effective protein digestion by trypsin suitable for a wide range of pH
including acidic pH. It was effective not only in experiments with solutions of
a model protein (myoglobin), but also with a subfraction of rat liver cytosol.
This significantly simplifies and accelerates protein digestion procedures for
subsequent MS. However, further studies are needed to find limits of
experimental applicability of the described protocol in proteomics. Oil bodies, lipid-storage organelles, are stabilized by a number of specific
proteins. These proteins are very hydrophobic, which complicates their
identification by "classical" proteomic protocols using trypsin digestion. Due
to the lack of trypsin cleavage sites, the achievable protein coverage is
limited or even insufficient for reliable protein identification. To identify
such proteins and to enhance their coverage, we introduced a modified method
comprising standard three-step procedure (SDS-PAGE, in-gel digestion, and
LC-MS/MS analysis). In this method, chymotrypsin, single or in combination with
trypsin, was used, which enabled to obtain proteolytic peptides from the
hydrophobic regions and to identify new oil bodies' proteins. Our method can be
easily applied to identification of other hydrophobic proteins. In this study, soft-shelled turtle (Pelodiscus sinensis) egg white (SSTEW)
proteins were digested by thermolysin and the resulting small peptides were
further fractionated by reverse phase chromatography. Peptides with angiotensin
I-converting enzyme inhibitory (ACEI) activity from these fractions were
screened. A lysozyme-derived peptide, IW-11, from the fraction with the most
effective ACEI was identified by liquid chromatography-tandem mass spectrometry
(LC-MS/MS) and its purified form showed effective ACEI activity in vitro
(IC50=4.39±0.31μM). The Lineweaver-Burk plots indicated that the inhibition
towards ACE caused by this peptide is a competitive inhibition. The molecular
docking study further revealed that the ACEI activity of IW-11 is mainly
attributed to the formation of hydrogen bonds between the N-terminal residue of
IW-11 and the S1 pocket (Ala354 and Tyr523) and the S2' region (His513 and
His353) of ACE. Moreover, the digestion parameters were further optimized and
the target peptide (82% purity) was readily obtained (15% yield) without any
cumbersome purification procedure. Notably, lysozyme C is the most abundant
protein in SSTEW, which implies that an efficient production of this ACEI
peptide from SSTEW is promising.
BIOLOGICAL SIGNIFICANCE: Inhibition of ACE has proven to be an effective
strategy in prevention and treatment of hypertension and related diseases.
Unlike typical synthetic ACE inhibitors which exert well described side effects,
food-derived peptides with ACE inhibitory activity may be safer alternatives for
hypertension treatment. In this study, we comprehensively identified peptides
derived from SSTEW digest using a proteomic approach. IW-11, which is derived
from lysozyme, the most abundant protein in SSTEW, showed remarkable inhibition
towards ACE. This peptide has been demonstrated to have a competitive inhibitory
property which is able to bind to ACE active site and found to be a true
inhibitor against ACE according to Lineweaver-Burk plots. Using an optimized
thermolysin condition, IW-11 can be readily obtained without any complex
purification step, which will benefit its further application to prevention or
treatment of hypertension. Workflows in bottom-up proteomics have traditionally implemented the use of
proteolysis during sample preparation; enzymatic digestion is most commonly
performed using trypsin. This results in the hydrolysis of peptide bonds forming
tryptic peptides, which can then be subjected to LC-MS/MS analysis. While the
structure, specificity, and kinetics of trypsin are well characterized, a lack
of consensus and understanding has remained regarding fundamental parameters
critical to obtaining optimal data from a proteomics experiment. These include
the type of trypsin used, pH during digestion, incubation temperature as well as
enzyme-to-substrate ratio. Through the use of design of experiments (DOE), we
optimized these parameters, resulting in deeper proteome coverage and a greater
dynamic range of measurement. The knowledge gained from optimization of a
discovery-based proteomics experiment was applied to targeted LC-MS/MS
experiments using protein cleavage-isotope dilution mass spectrometry for
absolute quantification. We demonstrated the importance of these digest
parameters with respect to our limit of detection as well as our ability to
acquire more accurate quantitative measurements. Additionally, we were able to
quantitatively account for peptide decay observed in previous studies, caused by
nonspecific activity of trypsin. The tryptic digest optimization described here
has eliminated this previously observed peptide decay as well as provided a
greater understanding and standardization for a common but critical sample
treatment used across the field of proteomics. Implementation of quantitative clinical chemistry proteomics (qCCP) requires
targeted proteomics approaches, usually involving bottom-up multiple reaction
monitoring-mass spectrometry (MRM-MS) with stable-isotope labeled standard (SIS)
peptides, to move toward more accurate measurements. Two aspects of qCCP that
deserve special attention are (1) proper calibration and (2) the assurance of
consistent digestion. Here, we describe the evaluation of tryptic digestion
efficiency by monitoring various signature peptides, missed cleavages, and
modifications during proteolysis of apolipoprotein A-I and B in normo- and
hypertriglyceridemic specimens. Absolute quantification of apolipoprotein A-I
and B was performed by LC-MRM-MS with SIS peptide internal standards at two time
points (4 and 20 h), using three native protein calibrators. Comparison with an
immunoturbidimetric assay revealed recoveries of 99.4 ± 6.5% for apolipoprotein
A-I and 102.6 ± 7.2% for apolipoprotein B after 4 h of trypsin digestion.
Protein recoveries after 20 h trypsin incubation equaled 95.9 ± 6.9% and 106.0 ±
10.0% for apolipoproteins A-I and B, respectively. In conclusion, the use of
metrologically traceable, native protein calibrators looks promising for
accurate quantification of apolipoprotein A-I and B. Selection of rapidly formed
peptides, that is, with no or minor missed cleavages, and the use of short
trypsin incubation times for these efficiently cleaved peptides are likely to
further reduce the variability introduced by trypsin digestion and to improve
the traceability of test results to reach the desirable analytical performance
for clinical chemistry application. |
Which proteins act as factors that promote transcription-coupled repair in bacteria? | Transcription coupled nucleotide excision repair (TC-NER or TCR) is a cellular process by which UV-induced damage and other road-blocks encountered in the transcribed strand are restored. Bacterial transcription-coupled repair is initiated when RNA polymerase stalled at a DNA lesion is removed by Mfd (Mutation frequency decline), an ATP-dependent DNA translocase. Mfd is the major transcription repair coupling factor in bacteria. Also, the transcription elongation factor NusA, in addition to its role in recruiting translesion synthesis (TLS) DNA polymerases to gaps encountered during transcription, promotes an alternative class of TCR involved in the identification and removal of a class of lesion, such as the N(2)-f-dG lesion. | Heterogeneity of DNA repair has been observed at different levels of genomic
organization, including chromatin domains, expressed genes and DNA strands. If
heterogeneity also existed intragenically, it could reveal fine details of the
excision repair mechanism in vivo. Here we measure the frequency of UV-induced
cyclobutane pyrimidine dimers at individual nucleotides within defined portions
of two Escherichia coli genes, lacl and lacZ, at various times after
irradiation. Two domains of differential repair rates were apparent, with repair
being slow at nucleotides adjacent to the transcription start sites. In lacZ,
the domain of faster repair began 32 bases downstream of the transcription start
site and required the mfd gene. Since mfd codes for a transcription-repair
coupling factor, this transcription-coupled repair system evidently becomes
operative downstream of the initiation complex region in vivo. Unexpectedly,
however, (1) an mfd mutation reduced repair in the downstream domain even when
transcription was at a very low level and (2) induction of lacZ transcription
with isopropyl-beta-D-thiogalactoside overcame this reduction. Evidently, the
Mfd transcription-repair coupling factor is required for basal levels of
strand-specific repair in this gene, but induced levels of repair are related to
transcription through another mechanism. Transcription-coupled repair, the targeted repair of the transcribed strands of
active genes, is defective in bacteria, yeast, and human cells carrying
mutations in mfd, RAD26 and ERCC6, respectively. Other factors probably are also
uniquely involved in transcription-repair coupling. Recently, a defect was
described in transcription-coupled repair for Escherichia coli mismatch repair
mutants and human tumor cell lines with mutations in mismatch repair genes. We
examined removal of UV-induced DNA damage in yeast strains mutated in mismatch
repair genes in an effort to confirm a defect in transcription-coupled repair in
this system. In addition, we determined the contribution of the mismatch repair
gene MSH2 to transcription-coupled repair in the absence of global genomic
repair using rad7 delta mutants. We also determined whether the
Rad26-independent transcription-coupled repair observed in rad26 delta and rad7
delta rad26 delta mutants depends on MSH2 by examining repair deficiencies of
rad26 delta msh2 delta and rad7 delta rad26 delta msh2 delta mutants. We found
no defects in transcription-coupled repair caused by mutations in the mismatch
repair genes MSH2, MLH1, PMS1, and MSH3. Yeast appears to differ from bacteria
and human cells in the capacity for transcription-coupled repair in a mismatch
repair mutant background. Transcription and DNA repair are coupled in E. coli by the Mfd protein, which
dissociates transcription elongation complexes blocked at nonpairing lesions and
mediates recruitment of DNA repair proteins. We show that Mfd influences the
elongation state of RNA polymerase (RNAP); transcription complexes that have
reverse translocated into the backtracked position, a potentially important
intermediate in RNA proofreading and repair, are restored to the forward
position by the activity of Mfd, and arrested complexes are rescued into
productive elongation. Mfd may act through a translocase activity that rewinds
upstream DNA, leading either to translocation or to release of RNA polymerase
when the enzyme active site cannot continue elongation. The bacterial Mfd protein is a transcription-repair coupling factor that
performs two key functions during transcription-coupled DNA repair. The first is
to remove RNA polymerase (RNAP) complexes that have been stalled by a DNA lesion
from the site of damage, and the second is to mediate the recruitment of DNA
repair proteins. Mfd also displaces transcription complexes that have been
stalled by protein roadblocks, and catalyses the reactivation of transcription
complexes that have become 'backtracked'. We have identified amino acid
substitutions in the beta subunit of Escherichia coli RNAP that disrupt a direct
interaction between Mfd and RNAP. These substitutions prevent Mfd displacing
stalled RNAP from DNA in vivo and in vitro. They define a highly conserved
surface-exposed patch on the beta1 domain of RNAP that is required by Mfd for
the initial step of transcription-coupled repair, the enhancement of roadblock
repression and the reactivation of backtracked transcription complexes. Coupling of transcription and DNA repair in bacteria is mediated by
transcription-repair coupling factor (TRCF, the product of the mfd gene), which
removes transcription elongation complexes stalled at DNA lesions and recruits
the nucleotide excision repair machinery to the site. Here we describe the 3.2
A-resolution X-ray crystal structure of Escherichia coli TRCF. The structure
consists of a compact arrangement of eight domains, including a translocation
module similar to the SF2 ATPase RecG, and a region of structural similarity to
UvrB. Biochemical and genetic experiments establish that another domain with
structural similarity to the Tudor-like domain of the transcription elongation
factor NusG plays a critical role in TRCF/RNA polymerase interactions.
Comparison with the translocation module of RecG as well as other structural
features indicate that TRCF function involves large-scale conformational
changes. These data, along with a structural model for the interaction of TRCF
with the transcription elongation complex, provide mechanistic insights into
TRCF function. DNA damage that blocks the transcription of genes is prioritized for repair by
transcription-coupled DNA repair pathways. RNA polymerases stalled at DNA
lesions obstruct repair enzymes, but this situation is turned to the advantage
of the cell by transcription-repair coupling factors that remove the stalled RNA
polymerase from DNA and increase the rate at which the lesion is repaired.
Recent structural studies of the bacterial transcription-repair coupling factor,
Mfd, have revealed a modular architecture in which an ATP-dependent DNA-based
motor is coupled to protein-protein interaction domains that can attach the
motor to RNA polymerase and the DNA repair protein UvrA. Here I review the key
features of this multifunctional protein and discuss how recent mechanistic and
structural findings have advanced our understanding of transcription-coupled DNA
repair in bacteria. In vivo studies suggest that replication forks are arrested by encounters with
head-on transcription complexes. Yet, the fate of the replisome and RNA
polymerase (RNAP) after a head-on collision is unknown. We found that the
Escherichia coli replisome stalls upon collision with a head-on transcription
complex, but instead of collapsing, the replication fork remains highly stable
and eventually resumes elongation after displacing the RNAP from DNA. We also
found that the transcription-repair coupling factor Mfd promotes direct restart
of the fork after the collision by facilitating displacement of the RNAP. These
findings demonstrate the intrinsic stability of the replication apparatus and a
previously unknown role for the transcription-coupled repair pathway in
promoting replication past a RNAP block. Transcription-coupled nucleotide excision repair (TC-NER) removes certain kinds
of lesions from the transcribed strand of expressed genes. The signal for TC-NER
is thought to be RNA polymerase stalled at a lesion in the DNA template. In
Escherichia coli, the stalled polymerase is dissociated from the lesion by the
transcription repair coupling factor (Mfd protein), which also recruits excision
repair proteins to the site resulting in efficient removal of the lesion. TC-NER
has been documented in cells from a variety of organisms ranging from bacteria
to humans. In each case, the RNA polymerase involved has been a multimeric
protein complex. To ascertain whether a gene transcribed by the monomeric RNA
polymerase of bacteriophage T7 could be repaired by TC-NER, we constructed
strains of E. coli in which the chromosomal lacZ gene is controlled by a T7
promoter. In the absence of T7 RNA polymerase, little or no beta-galactosidase
is produced, indicating that the E. coli RNA polymerase does not transcribe lacZ
efficiently, if at all, in these strains. By introducing a plasmid (pAR1219)
carrying the T7 gene 1 under control of the E. coli lac UV5 promoter into these
strains, we obtained derivatives in which the level of T7 RNA polymerase could
be regulated. In cultures containing upregulated levels of the polymerase,
beta-galactosidase was actively produced indicating that the T7 RNA polymerase
transcribes the lacZ gene efficiently. Under these conditions, we observed that
UV-induced cyclobutane pyrimidine dimers were removed more rapidly from the
transcribed strand of lacZ than from the nontranscribed strand, supporting the
conclusion that TC-NER occurred in this gene. This response was absent in an
mfd-1 mutant, indicating that the underlying mechanism may be similar to that
for the bacterial RNA polymerase. Transcription-coupled DNA repair (TCR) is a subpathway of nucleotide excision
repair (NER) that is triggered when RNA polymerase is stalled by DNA damage.
Lesions targeted by TCR are repaired more quickly than lesions repaired by the
transcription-independent "global" NER pathway, but the mechanism underlying
this rate enhancement is not understood. Damage recognition during bacterial NER
depends upon UvrA, which binds to the damage and loads UvrB onto the DNA.
Bacterial TCR additionally requires the Mfd protein, a DNA translocase that
removes the stalled transcription complexes. We have determined the properties
of Mfd, UvrA, and UvrB that are required for the elevated rate of repair
observed during TCR. We show that TCR and global NER differ in their
requirements for damage recognition by UvrA, indicating that Mfd acts at the
very earliest stage of the repair process and extending the functional
similarities between TCR in bacteria and eukaryotes. Transcription coupled nucleotide excision repair (TC-NER) is involved in
correcting UV-induced damage and other road-blocks encountered in the
transcribed strand. Mutation frequency decline (Mfd) is a transcription repair
coupling factor, involved in repair of template strand during transcription. Mfd
from M. tuberculosis (MtbMfd) is 1234 amino-acids long harboring characteristic
modules for different activities. Mtbmfd complemented Escherichia coli mfd
(Ecomfd) deficient strain, enhanced survival of UV irradiated cells and
increased the road-block repression in vivo. The protein exhibited ATPase
activity, which was stimulated ∼1.5-fold in the presence of DNA. While the
C-terminal domain (CTD) comprising amino acids 630 to 1234 showed ∼2-fold
elevated ATPase activity than MtbMfd, the N-terminal domain (NTD) containing the
first 433 amino acid residues was able to bind ATP but deficient in hydrolysis.
Overexpression of NTD of MtbMfd led to growth defect and hypersensitivity to UV
light. Deletion of 184 amino acids from the C-terminal end of MtbMfd (MfdΔC)
increased the ATPase activity by ∼10-fold and correspondingly exhibited
efficient translocation along DNA as compared to the MtbMfd and CTD.
Surprisingly, MtbMfd was found to be distributed in monomer and hexamer forms
both in vivo and in vitro and the monomer showed increased susceptibility to
proteases compared to the hexamer. MfdΔC, on the other hand, was predomitly
monomeric in solution implicating the extreme C-terminal region in
oligomerization of the protein. Thus, although the MtbMfd resembles EcoMfd in
many of its reaction characteristics, some of its hitherto unknown distinct
properties hint at its species specific role in mycobacteria during
transcription-coupled repair. Transcription-coupled repair (TCR) is a cellular process by which some forms of
DNA damage are repaired more rapidly from transcribed strands of active genes
than from nontranscribed strands or the overall genome. In humans, the TCR
coupling factor, CSB, plays a critical role in restoring transcription following
both UV-induced and oxidative DNA damage. It also contributes indirectly to the
global repair of some forms of oxidative DNA damage. The Escherichia coli
homolog, Mfd, is similarly required for TCR of UV-induced lesions. However, its
contribution to the restoration of transcription and to global repair of
oxidative damage has not been examined. Here, we report the first direct study
of transcriptional recovery following UV-induced and oxidative DNA damage in E.
coli. We observed that mutations in mfd or uvrA reduced the rate that
transcription recovered following UV-induced damage. In contrast, no difference
was detected in the rate of transcription recovery in mfd, uvrA, fpg, nth, or
polB dinB umuDC mutants relative to wild-type cells following oxidative damage.
mfd mutants were also fully resistant to hydrogen peroxide (H(2)O(2)) and
removed oxidative lesions from the genome at rates comparable to wild-type
cells. The results demonstrate that Mfd promotes the rapid recovery of gene
expression following UV-induced damage in E. coli. In addition, these findings
imply that Mfd may be functionally distinct from its human CSB homolog in that
it does not detectably contribute to the recovery of gene expression or global
repair following oxidative damage. Transcription-coupled repair (TCR) is a subpathway of nucleotide excision repair
(NER) that acts specifically on lesions in the transcribed strand of expressed
genes. First reported in mammalian cells, TCR was then documented in Escherichia
coli. In this organism, an RNA polymerase arrested at a lesion is displaced by
the transcription repair coupling factor, Mfd. This protein recruits the NER
lesion-recognition factor UvrA, and then dissociates from the DNA. UvrA binds
UvrB, and the assembled UvrAB* complex initiates repair. In mutants lacking
active Mfd, TCR is absent. A gene transcribed by the bacteriophage T7 RNA
polymerase in E. coli also requires Mfd for TCR. The CSB protein (missing or
defective in cells of patients with Cockayne syndrome, complementation group B)
is essential for TCR in humans. CSB and its homologs in higher eukaryotes are
likely functional equivalents of Mfd. Transcription-coupled DNA repair uses components of the transcription machinery
to identify DNA lesions and initiate their repair. These repair pathways are
complex, so their mechanistic features remain poorly understood. Bacterial
transcription-coupled repair is initiated when RNA polymerase stalled at a DNA
lesion is removed by Mfd, an ATP-dependent DNA translocase. Here we use
single-molecule DNA omanipulation to observe the dynamic interactions of
Escherichia coli Mfd with RNA polymerase elongation complexes stalled by a
cyclopyrimidine dimer or by nucleotide starvation. We show that Mfd acts by
catalysing two irreversible, ATP-dependent transitions with different
structural, kinetic and mechanistic features. Mfd remains bound to the DNA in a
long-lived complex that could act as a marker for sites of DNA damage, directing
assembly of subsequent DNA repair factors. These results provide a framework for
considering the kinetics of transcription-coupled repair in vivo, and open the
way to reconstruction of complete DNA repair pathways at single-molecule
resolution. In conditions of halted or limited genome replication, like those experienced in
sporulating cells of Bacillus subtilis, a more immediate detriment caused by DNA
damage is altering the transcriptional programme that drives this developmental
process. Here, we report that mfd, which encodes a conserved bacterial protein
that mediates transcription-coupled DNA repair (TCR), is expressed together with
uvrA in both compartments of B. subtilis sporangia. The function of Mfd was
found to be important for processing the genetic damage during B. subtilis
sporulation. Disruption of mfd sensitized developing spores to mitomycin-C (M-C)
treatment and UV-C irradiation. Interestingly, in non-growing sporulating cells,
Mfd played an anti-mutagenic role as its absence promoted UV-induced mutagenesis
through a pathway involving YqjH/YqjW-mediated translesion synthesis (TLS). Two
observations supported the participation of Mfd-dependent TCR in spore
morphogenesis: (i) disruption of mfd notoriously affected the efficiency of B.
subtilis sporulation and (ii) in comparison with the wild-type strain, a
significant proportion of Mfd-deficient sporangia that survived UV-C treatment
developed an asporogenous phenotype. We propose that the Mfd-dependent repair
pathway operates during B. subtilis sporulation and that its function is
required to eliminate genetic damage from transcriptionally active genes. Transcription-coupled nucleotide excision repair (TCR) accelerates the removal
of noncoding lesions from the template strand of active genes, and hence
contributes to genome-wide variations in mutation frequency. Current models for
TCR suppose that a lesion must cause RNA polymerase (RNAP) to stall if it is to
be a substrate for accelerated repair. We have examined the substrate
requirements for TCR using a system in which transcription stalling and damage
location can be uncoupled. We show that Mfd-dependent TCR in bacteria involves
the formation of a damage search complex that can detect lesions downstream of a
stalled RNAP, and that the strand specificity of the accelerated repair pathway
is independent of the requirement for a lesion to stall RNAP. We also show that
an ops (operon polarity suppressor) transcription pause site, which causes
backtracking of RNAP, can promote the repair of downstream lesions when those
lesions do not themselves cause the polymerase to stall. Our findings indicate
that the transcription-repair coupling factor Mfd, which is an ATP-dependent
superfamily 2 helicase that binds to RNAP, continues to translocate along DNA
after RNAP has been displaced until a lesion in the template strand is located.
The discovery that pause sites can promote the repair of nonstalling lesions
suggests that TCR pathways may play a wider role in modulating mutation
frequencies in different parts of the genome than has previously been suspected. |
What is the association between Generalized anxiety disorder and mortality risk? | Numerous studies have demonstrated that Generalized anxiety disorder is associated with increased mortality risk in different populations, including veterans and non demented elderly individuals. Anxiety disorders predict greater mortality, particularly when present with other psychiatric disorders. However, one study has found that generalized anxiety disorder was not associated with excess mortality in depressive elderly people. | Over the past two decades, anxiety disorders have become the focus of much
research after years of relative obscurity. The accumulating data has suggested
that anxiety disorders may have many consequences including decreased quality of
life, economic dependence, multiple somatic complaints, maladaptive personality
traits, and increased mortality due to suicide, cardiovascular, and
cerebrovascular causes. Aggressive management of these disorders may greatly
lessen the impact. Anxiety disorders, which include generalized anxiety disorder, panic disorder,
posttraumatic stress disorder, obsessive-compulsive disorder, and phobic
disorders, are the psychiatric disorders most commonly found in the community,
according to the results of recent epidemiologic studies. However, failure to
diagnose these disorders occurs in up to 50% of patients with an anxiety
disorder. This failure to correctly diagnose and appropriately treat anxiety
disorders can result in overutilization of health care services and increased
morbidity and mortality rates from either the anxiety disorder or comorbid
medical conditions. Reliable diagnostic tools to improve the early recognition
of anxiety disorders can subsequently result in more effective treatment. BACKGROUND: Previous reports of suicide risk in patients with anxiety disorders
have been inconsistent.
METHODS: Using the FDA database, we assessed suicide and suicide attempt risk
among patients, participating in recent clinical trials evaluating new
anti-anxiety medications, with diagnosis of panic disorder (PD), social anxiety
disorder or social phobia (SP), generalized anxiety disorder (GAD), post
traumatic stress disorder (PTSD), and obsessive compulsive disorder (OCD).
RESULTS: Overall, among 20076 participating anxious patients, 12 committed
suicide and 28 attempted suicide. The annual suicide risk rate was 193/100000
patients and annual suicide attempt risk was 1350/100000 patients.
LIMITATIONS: Clinical trial data have limited applicability to clinical
practice. Participants in clinical trials are a highly selected,
nonrepresentative sample of the clinical population. A number of patients never
complete clinical trials and thus data are based on a limited sub-sample. These
trials were not primarily designed to assess suicide risk.
CONCLUSIONS: Suicide risk in patients with anxiety disorders is higher than
previously thought. Patients with anxiety disorders warrant explicit evaluation
for suicide risk. Anxiety disorders are prevalent and associated with increased morbidity and
mortality. Some chronic anxiety disorders, including generalized anxiety
disorder (GAD), may be characterized by an underlying high level of anxiety on
which exacerbations of symptoms are superimposed. Effective treatment of anxiety
disorders should therefore strive to attain both an acute reduction in the
symptoms of anxiety (a response) and sustained resolution of the symptoms of any
underlying chronic anxiety (remission). This strategy may necessitate long-term
treatment of these disorders by pharmacotherapy and/or psychotherapy. Studies
using the serotonin and norepinephrine reuptake inhibitor (SNRI), venlafaxine
extended release (XR), suggest that these aims may be achieved using this newer
class of drugs. Studies with venlafaxine XR in patients with GAD have
demonstrated robust anxiolytic efficacy over placebo, particularly regarding
worry, cognitive dysfunction, and muscular tension, which are specific to GAD.
Administration of venlafaxine XR over both short- (8-week) and long-term
(6-month) periods resulted in a significantly greater number of patients
achieving response and remission than obtained with placebo. Long-term treatment
with venlafaxine XR in patients with GAD showed greater efficacy than that
observed in short-term studies. This was achieved without any loss of short-term
efficacy and patients' social functioning was also restored. While available
data indicate that venlafaxine XR is an appropriate choice of agent in the
long-term treatment of GAD, more studies are needed to determine how to further
increase remission rates and to maintain remission beyond 6 months. BACKGROUND: The association between depression and an increased risk of death in
elderly persons has been established in both clinical and community studies.
Co-occurrence of depression and generalized anxiety has been shown to represent
more severe and more chronic psychopathology. However, little is known about the
relation between generalized anxiety disorder, mixed anxiety-depression
(generalized anxiety disorder and depression) and excess mortality in the
elderly.
OBJECTIVE: To investigate whether generalized anxiety and mixed
anxiety-depression are associated with mortality.
METHOD: Generalized anxiety disorder, mixed anxiety-depression and depression
were assessed in 4051 older persons with a ten-year follow-up of community death
registers. The mortality risk of generalized anxiety, depression and mixed
anxiety-depression was calculated after adjustment for demographic variables,
physical illness, functional disabilities and social vulnerability.
RESULTS: In generalized anxiety disorder and mixed anxiety-depression no
significant excess mortality was found. In depression a significant excess
mortality was found in men [HR 1.44 (1.09-1.89)] but not in women [HR 1.04
(0.87-1.24)] after adjustment for the different variables.
CONCLUSIONS: In elderly persons depression increases the risk of death in men.
Neither generalized anxiety nor mixed anxiety-depression are associated with
excess mortality. Generalized anxiety disorder may even predict less mortality
in depressive elderly people. The relation between generalized anxiety disorder
and its possibly protective effect on mortality has to be further explored. Anxiety disorders are prevalent and associated with an increase in morbidity and
mortality, particularly when present with additional psychiatric disorders. They
represent a public health and economic burden, yet they are commonly
underrecognized and undertreated. Benzodiazepines are effective anxiolytics, but
they primarily treat the somatic symptoms of generalized anxiety disorder (GAD),
and are not effective in treating the depressive symptoms that are often
comorbid in chronic anxiety disorders like GAD. Some antidepressants may
therefore offer the best choice of therapy. Their benefit in the treatment of
GAD has been demonstrated using the tricyclic antidepressant, imipramine, and
some selective serotonin reuptake inhibitors. The serotonin and norepinephrine
reuptake inhibitor venlafaxine extended release (XR), has been indicated for GAD
and has proven to be effective in both the short- and long-term treatment of
patients with this disorder. Many patients treated with venlafaxine XR achieve
and sustain remission from the symptoms of GAD, which is the goal of treatment. OBJECTIVE: To examine whether the 1-year prevalence of major depressive disorder
(MDD), generalized anxiety disorder (GAD), and their comorbidity were associated
with subsequent all-cause and cardiovascular disease (CVD) mortality during 15
years in Vietnam veterans.
METHODS: Participants (N = 4256) were from the Vietnam Experience Study.
Service, sociodemographic, and health data were collected from service files,
telephone interviews, and a medical examination. One-year prevalence of MDD and
GAD was determined through a diagnostic interview schedule based on the
Diagnostic and Statistical Manual of Mental Disorders (version IV) criteria.
Mortality over the subsequent 15 years was gathered from US army records.
RESULTS: MDD and GAD were positively and significantly associated with all-cause
and CVD mortality. The relationships between MDD and GAD and CVD mortality were
no longer significant after adjustment for sociodemograhics, health status at
entry, health behaviors, and other risk markers. Income was the covariate with
the strongest impact on this association. In analyses comparing comorbidity and
GAD and MDD alone, with neither diagnosis, comorbidity proved to be the
strongest predictor of both all-cause and CVD mortality.
CONCLUSION: GAD and MDD predict all-cause mortality in a veteran population
after adjusting for a range of covariates. However, those with both GAD and MDD
were at greatest risk of subsequent death, and it would seem that these
disorders may interact synergistically to affect mortality. Future research on
mental disorders and health outcomes, as well as future clinical interventions,
should pay more attention to comorbidity. OBJECTIVE: To examine the 1-month prevalence of generalized anxiety disorder
(GAD) according to Diagnostic and Statistical Manual of Mental Disorders, Fourth
Edition (DSM-IV), Diagnostic and Statistical Manual of Mental, Fifth Edition
(DSM-V), and International Classification of Diseases, Tenth Revision (ICD-10),
and the overlap between these criteria, in a population sample of 75-year-olds.
We also aimed to examine comorbidity between GAD and other psychiatric
diagnoses, such as depression.
METHOD: During 2005-2006, a comprehensive semistructured psychiatric interview
was conducted by trained nurses in a representative population sample of
75-year-olds without dementia in Gothenburg, Sweden (N = 777; 299 men and 478
women). All psychiatric diagnoses were made according to DSM-IV. GAD was also
diagnosed according to ICD-10 and DSM-V.
RESULTS: The 1-month prevalence of GAD was 4.1% (N = 32) according to DSM-IV,
4.5% (N = 35) according to DSM-V, and 3.7% (N = 29) according to ICD-10. Only
46.9% of those with DSM-IV GAD fulfilled ICD-10 criteria, and only 51.7% and
44.8% of those with ICD-10 GAD fulfilled DSM-IV/V criteria. Instead, 84.4% and
74.3% of those with DSM-IV/V GAD and 89.7% of those with ICD-10 GAD had
depression. Also other psychiatric diagnoses were common in those with ICD-10
and DSM-IV GAD. Only a small minority with GAD, irrespective of criteria, had no
other comorbid psychiatric disorder. ICD-10 GAD was related to an increased
mortality rate.
CONCLUSIONS: While GAD was common in 75-year-olds, DSM-IV/V and ICD-10 captured
different individuals. Current definitions of GAD may comprise two different
expressions of the disease. There was greater congruence between GAD in either
classification system and depression than between DSM-IV/V GAD and ICD-10 GAD,
emphasizing the close link between these entities. BACKGROUND: There are conflicting data on the role of anxiety in predicting
mortality.
AIMS: To evaluate the 10-year mortality risk associated with anxiety in
community-dwelling elderly people.
METHOD: Using data from 718 men and 1046 women aged 65 years and over,
gender-stratified associations of anxiety symptoms (Spielberger State-Trait
Anxiety Inventory, third tertile) and current DSM-IV anxiety disorder including
generalised anxiety disorder (GAD) and phobia with all-cause and cardiovascular
mortality were determined.
RESULTS: In women, mortality risk was increased for anxiety disorder and GAD in
multivariate Cox models (hazard ratio (HR) = 1.53, 95% CI 1.02-2.27 and HR =
2.04, 95% CI 1.08-3.86 respectively), whereas for phobia it was nearly
significant (HR = 1.52, 95% CI 0.94-2.47). Anxiety trait symptoms became
non-significant as a result of the confounding effect of depressive symptoms.
Anxiety disorder was associated with cardiovascular mortality in univariate
analysis (HR = 2.42, 95% CI 1.16-5.07). No significant associations were found
in men.
CONCLUSIONS: Our study suggests a gender-specific association of anxiety and
mortality. |
Which molecule is targeted by a monoclonal antibody Mepolizumab? | Mepolizumab is a humanized monoclonal antibody that binds to and inactivates interleukin-5 that has been shown to reduce asthma exacerbations in patients with severe eosinophilic asthma. | The role of eosinophils as effector cells in asthma pathogenesis has been
questioned since an anti-interleukin (IL)-5 monoclonal antibody (mepolizumab),
which depleted blood and sputum eosinophils, failed to inhibit allergen-induced
bronchoconstriction and airway hyperresponsiveness. However, the effect of IL-5
blockade on tissue eosinophils was not examined. We sought to determine whether
mepolizumab depletes airway tissue eosinophils and their products. Twenty-four
patients with mild asthma received three intravenous doses of either 750 mg of
mepolizumab or placebo in a randomized, double-blind, parallel-group fashion
over 20 weeks. Mepolizumab produced a median decrease from baseline of 55% for
airway eosinophils (interquartile range, 29-89%; p = 0.009 versus placebo), 52%
for bone marrow eosinophils (45-76%, p = 0.003), and 100% for blood eosinophils
(range, 67-100%, p = 0.02). Mepolizumab had no appreciable effect on bronchial
mucosal staining of eosinophil major basic protein. There were no significant
changes in clinical measures of asthma (airway hyperresponsiveness, FEV1, and
peak flow recordings) between the mepolizumab and placebo-treated groups.
Anti-IL-5 treatment reduces but does not deplete airway or bone marrow
eosinophils. The role of the eosinophil remains uncertain. Further clinical
studies in asthma with more effective antieosinophil strategies are required. GlaxoSmithKline (formerly SmithKline Beecham) is developing mepolizumab
(SB-240563), a monoclonal antibody directed against IL-5, as a potential
treatment for asthma and atopic dermatitis. Phase II trials in asthma were
underway by April 1998 and by March 2002, phase II trials had also been
initiated in atopic dermatitis. BACKGROUND: IL-5 is a cytokine critically involved in regulating several aspects
of eosinophils including their production, activation, and tissue recruitment.
As such, IL-5 may be involved in the pathogenesis of hypereosinophilic
syndromes, a group of poorly treated diverse disorders characterized by
sustained peripheral blood and/or tissue eosinophilia.
OBJECTIVE: We aimed to assess the safety and efficacy of a humanized blocking
monoclonal antibody against IL-5 (mepolizumab) in patients with several forms of
hyper-eosinophilic syndromes.
METHODS: We performed an open-label trial of anti-IL-5 in which 3 intravenous
doses (10 mg/kg, maximum 750 mg) were administered at 4-week intervals to 4
patients with hypereosinophilic syndromes (defined by peripheral blood and/or
tissue eosinophilia). The effects of treatment on safety, eosinophil levels (in
peripheral blood and/or diseased tissue), pulmonary function, and quality of
life were measured over a 28-week period.
RESULTS: Anti-IL-5 was well tolerated in all patients and lowered peripheral
blood eosinophil counts despite ongoing systemic glucocorticoid therapy. The
decline in circulating eosinophil counts was sustained for at least 12 weeks
after the last dose of anti-IL-5. In addition, anti-IL-5 improved clinical and
quality of life measurements. In one patient with striking tissue eosinophilia
(eosinophilic esophagitis), anti-IL-5 resulted in a 10-fold reduction in tissue
eosinophil levels.
CONCLUSIONS: These results suggest that anti-IL-5 is safe, effective in lowering
eosinophil levels, and has potential glucocorticoid-sparing effects in patients
with a variety of hyper-eosinophilic syndromes. As such, anti-IL-5 may have
significant therapeutic potential for hypereosinophilic syndromes. BACKGROUND: Eosinophils may play an important role in the pathogenesis of atopic
dermatitis (AD). Interleukin-5 is essential for eosinophil growth,
differentiation and migration. A monoclonal antibody to human interleukin-5
(mepolizumab) was developed for atopic diseases. This study was designed to
study the effect of mepolizumab in AD.
METHODS: Two single doses of 750 mg mepolizumab, given 1 week apart, were
studied in patients with moderate to severe AD using a randomized,
placebo-controlled parallel group design. The primary endpoint of 'success' to
treatment was defined as the percentage of patients with at least 'marked
improvement' after 2 weeks as assessed by the Physician's Global Assessment of
Improvement (PGA). Furthermore, SCORing AD (SCORAD), pruritus scoring, number of
blood eosinophils and serum thymus and activation-regulated chemokine (TARC)
values served as secondary endpoints. Fluticasone propionate cream 0.05%, once
daily could be used as rescue medication from day 16 if no improvement was
recorded.
RESULTS: Eighteen patients received mepolizumab and 22 placebo treatment.
Peripheral blood eosinophil numbers were significantly reduced in the treatment
group compared with placebo (P < 0.05). No clinical success was reached by PGA
assessment (P = 0.115), SCORAD (P = 0.293), pruritus scoring and TARC values in
the mepolizumab-treated group compared with placebo. However, modest improvement
(<50% improvement) assessed by PGA was scored significantly more in the
mepolizumab-treated group compared with placebo (P < 0.05).
CONCLUSION: Two single doses of 750 mg mepolizumab did not result in clinical
success in patients with AD, despite a significant decrease in peripheral blood
eosinophils. Hypereosinophilic syndrome (HES) is a rare disorder that is characterized by
persistent and marked eosinophilia combined with organ system dysfunction. HES
has substantial clinical heterogeneity but can be fatal without treatment,
especially in patients who present with a myelodysplastic variant of the
disorder. Although the pathophysiology of HES is poorly defined, dysregulation
of cytokines (interleukin 5 [IL-5], IL-3, granulocyte-macrophage
colony-stimulating factor [GM-CSF]) responsible for the maturation of
eosinophils is a primary feature. Of these cytokines, IL-5 appears to have the
greatest role in the regulation of eosinophil maturation. There is no Food and
Drug Administration-approved treatment for HES as yet; current strategies are
designed to lower blood eosinophils and attempt to limit end-organ damage.
Historically, corticosteroids and cytotoxic agents have been the mainstays of
therapy, with biological response modifiers such as interferon-alpha also
effective in some patients. However, despite improvements in survival, available
agents have significant limitations in terms of efficacy, tolerability, and
long-term toxicity. More recently, new agents directed at specific targets in
the pathogenesis of HES have been developed. These include imatinib mesylate, a
tyrosine kinase inhibitor, and more recently, mepolizumab, an anti-IL-5
monoclonal antibody. In a small case series of patients, these agents have been
shown to produce hematological and clinical responses in patients with HES,
although they may be effective in different subsets of patients. These targeted
therapies have the potential to improve clinical outcomes and to further the
understanding the pathophysiology of this difficult-to-treat condition. Diagnosis of major hypereosinophilia (>1500 x 10(9)/L) is complex because the
possible causes cover the entire range of medical specialties. History and
clinical condition will usually suggest parasitic or allergic diseases or drug
reactions. When workups for them are negative, rarer causes must be suspected:
specific organ diseases (chronic eosinophilic pneumonia, bullous pemphigoid,
etc.), solid tumor, clonal blood disorders, or vasculitis. When the condition is
prolonged and unexplained, hypereosinophilic syndrome is diagnosed. A rare
disorder, its prognosis depends on largely on its cardiac effects. It is usually
associated with heterogeneous hematologic conditions, mainly myeloproliferative
and lymphocytic disease. The myeloproliferative or primary variant sometimes
follows chromosomal deletions that cause a fusion between the Fip1-like1
(FIP1L1) and platelet-derived growth factor receptor (PDGFR) genes, thus
increasing the tyrosine kinase activity of the latter. Imatinib mesylate, a
tyrosine kinase inhibitor, is usually effective in this situation. In the
lymphocytic variant, hypereosinophilia is secondary to a primitive Th2
lymphocyte expansion that causes overproduction of interleukin 5 (IL-5).
Corticosteroids are the first-line therapy. Mepolizumab, an anti-IL-5 monoclonal
antibody, currently being evaluated, seems promising. Despite recent progress,
about 40% of the cases of hypereosinophilic syndrome remain unexplained. BACKGROUND: The atopy patch test (APT) is an in vivo model to study the
induction of eczema by inhalant allergens in atopic dermatitis (AD) patients.
Mepolizumab is a monoclonal antibody to interleukin-5, which reduces peripheral
blood eosinophils. Previously, we reported that mepolizumab treatment did not
result in clinical improvement in AD. The current study investigates the effect
of mepolizumab therapy on the APT in the same patients.
METHODS: Mepolizumab treatment was given at days 0 and 7 in a double-blind
placebo-controlled design. The APT was applied at days -2, 0, 14 and 28.
Clinical evaluation of each APT was conducted 48 h after application at days 0,
2, 16 and 30. Skin biopsies were taken at days 0, 2 and 16 for eosinophil
counts.
RESULTS: The mepolizumab-treated group showed no significant reduction in
macroscopic outcome of the APT. Tissue eosinophils were reduced in the
mepolizumab-treated group at day 16 compared with placebo; however, this was not
significant.
CONCLUSION: Mepolizumab therapy cannot prevent the eczematous reaction induced
by the APT. Furthermore, the influx of tissue eosinophil numbers in the APT is
not significantly inhibited after mepolizumab treatment compared with placebo,
despite a significant reduction in peripheral blood eosinophils. RATIONALE: Accumulation of eosinophils in the bronchial mucosa of individuals
with asthma is considered to be a central event in the pathogenesis of asthma.
In animal models, airway eosinophil recruitment and airway hyperresponsiveness
in response to allergen challenge are reduced by specific targeting of
interleukin-5. A previous small dose-finding study found that mepolizumab, a
humanized anti-interleukin-5 monoclonal antibody, had no effect on allergen
challenge in humans.
OBJECTIVES: To investigate the effect of three intravenous infusions of
mepolizumab, 250 or 750 mg at monthly intervals, on clinical outcome measures in
362 patients with asthma experiencing persistent symptoms despite inhaled
corticosteroid therapy (400-1,000 mug of beclomethasone or equivalent).
METHODS: Multicenter, randomized, double-blind, placebo-controlled study.
MEASUREMENTS AND MAIN RESULTS: Morning peak expiratory flow, forced expiratory
volume in 1 second, daily beta(2)-agonist use, symptom scores, exacerbation
rates, and quality of life measures. Sputum eosinophil levels were also measured
in a subgroup of 37 individuals. Mepolizumab was associated with a significant
reduction in blood and sputum eosinophils in both treatment groups (blood, P <
0.001 for both doses; sputum, P = 0.006 for 250 mg and P = 0.004 for 750 mg).
There were no statistically significant changes in any of the clinical end
points measured. There was a nonsignificant trend for decrease in exacerbation
rates in the mepolizumab 750-mg treatment group (P = 0.065).
CONCLUSIONS: Mepolizumab treatment does not appear to add significant clinical
benefit in patients with asthma with persistent symptoms despite inhaled
corticosteroid therapy. Further studies are needed to investigate the effect of
mepolizumab on exacerbation rates, using protocols specifically tailored to
patients with asthma with persistent airway eosinophilia. Mepolizumab is an anti-interleukin-5 monoclonal antibody that is in clinical
trials with GlaxoSmithKline (GSK) for the treatment of severe asthma, nasal
polyposis and hypereosinophilic syndrome and eosinophilic oesophagitis (the
latter two indications are classed as eosinophilia in the phase table).
Interleukin-5 stimulates the production, activation and maturation of
eosinophils. Since mepolizumab inhibits interleukin-5 and has a long terminal
half-life, treatment with mepolizumab causes a sustained reduction in the
numbers of circulating eosinophils. Thus, mepolizumab may be a useful
therapeutic agent for the treatment of conditions characterized by increased
levels of eosinophils. Hypereosinophilic syndrome is a rare idiopathic disease
with broad clinical signs and symptoms that is diagnosed based on a persistent
blood eosinophil count of >1500 cells, various end-organ damages (including
skin, heart, lung, nervous system and digestive system), and with exclusion of
known secondary causes of hypereosinophilia. Mepolizumab is in clinical trials
for the treatment of hypereosinophilic syndrome, eosinophilc oesophagitis,
severe asthma (in patients with airway eosinophilia) and nasal polyposis.
GlaxoSmithKline (GSK) has completed enrolment in a phase II study of mepolizumab
in 20 patients with symptomatic eosinophilic bronchitis with or without asthma
in Canada. The randomized, double-blind, placebo-controlled study is evaluating
the effects of intravenous mepolizumab on asthma control, airway eosinophilia
and the degree to which concomitant corticosteroid treatment can be reduced
(NCT00292877). In previous clinical studies, including trials in the EU and US,
mepolizumab has shown a lack of effect on allergen-induced airway responses and
inflammation despite a significant reduction in blood and sputum eosinophil
levels.A randomized, double-blind, placebo-controlled, multicentre, phase III
study of mepolizumab over 9 months in 85 patients with hypereosinophilic
syndrome was completed in 2006. All patients have been offered, and continued
in, a phase III, open-label, long-term extension study of mepolizumab. Enrolment
in this study was completed in September 2006.A phase III, compassionate use
trial of mepalizumab (NCT00244686) in patients with hypereosinophilic syndrome
was ongoing in October 2007 in the US. Patients who have significant clinical
disease but are unresponsive to traditional treatment and those who have
demonstrated clinical benefit from previous anti-IL-5 treatment are eligible to
take part in the trial. Mepolizumab received orphan drug status for first-line
treatment in patients with hypereosinophilic syndrome in the US and the EU in
2004. Mepolizumab is also in phase I/II clinical development for the treatment
of eosinophilic oesophagitis. A phase I/II trial (NCT00358449) began in August
2006 in the US, Australia, the UK and Canada, and will enrol approximately 72
paediatric patients with eosinophilic oesophagitis. The randomized,
parallel-group clinical trial will evaluate the safety, tolerability,
pharmacokinetics and pharmacodynamics of intravenous mepolizumab for 12 weeks.
In September 2006, GSK completed enrolment in a phase I/II study of mepolizumab
for the treatment of eosinophilic oesophagitis in ten adult patients in
Switzerland (NCT00274703). The randomized, double-blind, placebo-controlled
study will evaluate the pharmacokinetics, pharmacodynamics, safety and
tolerability of IV mepolizumab.A phase I/II trial of mepolizumab in four
patients with eosinophilic oesophagitis conducted by Cincinnati Children's
hospital found the monoclonal antibody was safe and effective. Brigham and
Women's Hospital in association with GSK is conducting a phase I/II trial of
mepolizumab in patients with Churg-Strauss Syndrome (CSS) in the US. The trial,
which started in September 2007, will evaluate the potential of mepolizumab to
reduce the need for corticosteroid therapy in patients with CSS (NCT00527566).
CSS, otherwise known as allergic granulomatosis, is defined by patients with
asthma, eosinophilia and vasculitis. OBJECTIVE: Eosinophilic oesophagitis (EoO) is a clinicopathological condition
defined by proton pump inhibitor-refractory oesophageal symptoms combined with
oesophageal eosinophilia. The pharmacodynamic effect of mepolizumab (a humanised
anti-interleukin-5 monoclonal antibody) in EoO was evaluated.
METHODS: Eleven adults with active EoO (>20 peak eosinophil number/high power
field (hpf) and dysphagia) were randomised to 750 mg of mepolizumab (n = 5) or
placebo (n = 6) and received two intravenous infusions, 1 week apart. Those not
in complete remission (<5 peak eosinophil number/hpf) after 8 weeks received two
further doses 4 weeks apart, 1500 mg of mepolizumab or placebo. The effect of
mepolizumab was assessed clinically, endoscopically, histologically, and via
blood and tissue biomarkers.
RESULTS: As assessed by immunofluorescence, a marked reduction of mean
oesophageal eosinophilia (p = 0.03) was seen in the mepolizumab group (-54%)
compared with the placebo group (-5%) 4 weeks after initiation of treatment. No
further reduction of eosinophil numbers was observed in response to the two
additional infusions in either group. Mepolizumab reduced tenascin C (p = 0.033)
and transforming growth factor beta1 (p = 0.05) expression in the oesophageal
epithelial layer 13 weeks after initiation of treatment. Clinically, limited
improvement of symptoms was seen, although a trend was seen between 4 and 13
weeks after initiation of mepolizumab treatment. Mepolizumab was well tolerated.
CONCLUSIONS: Mepolizumab significantly reduced eosinophil numbers in oesophageal
tissues in adult patients with active EoO, and changes in the expression of
molecules associated with oesophageal remodelling were reversed. Minimal
clinical improvement was achieved in a subgroup of patients with EoO.
Mepolizumab had an acceptable safety profile, even at the high 1500 mg dose
level.
TRIAL REGISTRATION NUMBER: NCT00274703. Eosinophils are major pro-inflammatory cells that make a major contribution to
diseases that affect the upper and lower airways, skin and gastrointestinal
tract. Interleukin (IL)-5 is central to their maturation and release from the
bone marrow together with their subsequent accumulation and activation in the
tissues. Mepolizumab is a humanized monoclonal antibody (mAb) with potent IL-5
neutralizing effects that represents a potential treatment for eosinophilic
diseases. Several clinical trials with mepolizumab reported that treatment of
patients with mild to severe asthma resulted in a substantial reduction in blood
and sputum eosinophil numbers. However, clinical outcomes were disappointing as
there were no significant effects on airway hyper-reactivity or the late
asthmatic reaction to inhaled allergen challenge. More recently two studies, one
in in patients with refractory eosinophilic asthma with a history of recurrent
severe exacerbations and the other in patients with persistent sputum
eosinophilia and symptoms despite systemic treatment with prednisone treatment,
reported that monthly intravenous mepolizumab reduced sputum/blood eosinophilia,
asthma exacerbations together with improvments in quality of life. Mepolizumab
also appears to be an effective therapy for hypereosinophilic syndrome while
other trials have shown efficacy of mepolizumab therapy in eosinophilic
esophagitis. This review will consider the current status of the clinical
development of mepolizumab for diseases with a significant eosinophilic
component to their pathology. Among diagnostic progress over the last three years in internal medicine,
Antisynthetase Syndrome is now more easily recognised with the diffusion of
laboratory tests for research of antibodies against tRNA synthetases (Anti JO1,
anti PL7, Anti PL12). In two third of cases, these antibodies are found despite
absence of antinuclear antibodies. Hence, we have to search them specifically in
patients with polyarthritis associated with myositis, cutaneous manifestations
(Raynaud phenomenom and "mechanic'hands") and interstitial lung disease.
Discovery of asymptomatic mutation in the L ferritin coding sequence help us to
better understand the "unexplained" hyperferritinemia. Initially described by
japonese gastroenterologists, auto immune pancreatitis in fact a part of a
systemic sclerosing disease with a biochemical hallmark: in crease of a subclass
of immunoglobulins G (IgG4). A new pediatric disease due to a deficiency of the
interleukin1 receptor antagonist (multifocal aseptic osteitis, periostitis,
stomatitis, disseminated pustulosis) help us to better understand unexplained
auto inflammatory diseases. The therapeutic progress is primarily due to an
explosion of biological therapies, particularly four of them very useful for
internists (in an off label use) : Interleukin 1 inhibitors (anakinra,
Canakinumab) to treat some auto inflammatory diseases (cryopirin associated
periodic syndromes and deficency of interleukin 1 receptor antagonist),
monoclonal antibody against interleukin 5 (mepolizumab) to treat some
hypereosinophilic syndromes and Churg and Strauss angiitis, interleukin 6
inhibitiors to treat multifocal Castleman's disease and adult Still disease, a
monoclonal antibody against vascular endothelial growth factor (Bevacizumab) to
treat hereditary hemorrhagic telangiectasia. BACKGROUND: Treatments for Churg-Strauss syndrome (CSS), a rare eosinophilic
vasculitis characterized by asthma, sinusitis, peripheral eosinophilia,
pulmonary infiltrates, and tissue infiltration, are limited by toxicity or poor
efficacy. Levels of IL-5, a cytokine regulating eosinophils, can be increased in
patients with CSS. Mepolizumab, a humanized monoclonal anti-IL-5 antibody,
decreases steroid requirements in patients with non-CSS hypereosinophilic
syndromes.
OBJECTIVE: The purpose of this study was to assess whether mepolizumab would
safely allow corticosteroid tapering in patients with steroid-dependent CSS
while decreasing serum markers of disease activity.
METHODS: This open-label pilot study treated 7 patients with 4 monthly doses of
mepolizumab to assess whether it safely decreased CSS disease activity and
permitted tapering of systemic corticosteroids.
RESULTS: Mepolizumab was safe and well tolerated in patients with CSS.
Mepolizumab reduced eosinophil counts and allowed for safe corticosteroid
reduction in all 7 subjects. On cessation of mepolizumab, CSS manifestations
recurred, necessitating corticosteroid bursts.
CONCLUSION: Mepolizumab is a safe and well-tolerated therapy in patients with
CSS, offering clinical benefit by enabling corticosteroid tapering while
maintaining clinical stability. Eosinophilic oesophagitis (EE) is a clinico-pathological entity recognized with
increased frequency in children and adults. It is an atopic disease involving
ingested and inhaled allergens. A pathological eosinophilic infiltrate is
diagnosed by finding ≥ 15 eosinophils per high-powered field on oesophageal
mucosal biopsies. This infiltrate may result in a narrowed oesophageal lumen. It
does not involve the stomach or duodenum. Children commonly present with
abdominal pain, vomiting and dysphagia. Presentation in adults is with
dysphagia, heartburn, chest pain or impaction of a food bolus in the oesophagus.
There is often a history of allergy (asthma, hay fever, eczema). A male
predomice (70% in adults) is unexplained. Distinctive endoscopic features are
linear furrows, mucosal rings and white papules, and the narrowed lumen may be
appreciated. Although EE and gastro-oesophageal reflux disease are separate
entities, there is a significant overlap of the conditions. Treatment options
include nonpharmacological approaches including an elimination or elemental
diet, and/ or medications, chiefly with corticosteroids. The topical
administration of fluticasone propionate has been demonstrated to improve
symptoms and mobilize the pathological infiltrate of eosinophils. There has been
a variable effect with the leukotriene receptor antagonist montelukast and
promising early results with mepolizumab, a monoclonal antibody against
interleukin-5. The long-term efficacy of topical corticosteroids has not been
well studied and most patients experience recurrent symptoms when treatment is
completed. Currently, repeated short courses of topical corticosteroids are
utilized. Acid suppression by a proton pump inhibitor may be considered in view
of the overlap between EE and gastro-oesophageal reflux disease. Mepolizumab (Bosatria(®), GlaxoSmithKline) is a biologic agent developed to
treat asthma. It represents a humanized monoclonal antibody of IgG1 κ type,
which targets human IL-5 and thus prevents its interaction with the α-chain of
the IL-5 receptor. To date, it has not been approved for use in any
eosinophil-related disorder; however, several studies have suggested some
therapeutic benefit across a spectrum of eosinophil-related disorders. This
article evaluates the currently available preclinical and clinical studies, and
the impact of mepolizumab against a variety of eosinophilic disorders. Peripheral blood eosinophilia and eosinophilic lung inflammation are common in a
variety of pulmonary conditions, including eosinophilic pneumonia and asthma,
hypereosinophilic syndrome and Churg-Strauss syndrome. Therapy in most of these
clinical entities consists of long-term treatment with systemic corticosteroids,
which is not always successful and has substantial side-effects. Interest has
increased considerably regarding alternative corticosteroid-sparing "smart"
regimens in these diseases that target IL-5, an important regulator of
eosinophilic development and function. To date, two humanized monoclonal
antibodies, mepolizumab and reslizumab, have been developed that bind to human
IL-5. In addition a new monoclonal antibody (MEDI-563) has been recently
developed targeting the IL-5 receptor. This review will investigate the current
status on IL-5 targeted therapy and related patents regarding eosinophil-driven
respiratory diseases, primarily eosinophilic asthma but also CSS and HES. Recent
advances and information from clinical trials will be presented in a way that
will allow the reader to approach the role of the eosinophil in the lung
diseases presented in this review. BACKGROUND: Approximately 85% of nasal polyps (NPs) in white subjects are
characterized by prominent eosinophilia. IL-5 is the key driver of eosinophilic
differentiation and survival.
OBJECTIVE: We sought to investigate the therapeutic potential of inhibiting IL-5
with a humanized mAb as treatment for severe nasal polyposis.
METHODS: Thirty patients with severe nasal polyposis (grade 3 or 4 or recurrent
after surgery) refractory to corticosteroid therapy were randomized in a
double-blind fashion to receive either 2 single intravenous injections (28 days
apart) of 750 mg of mepolizumab (n = 20) or placebo (n = 10). Change from
baseline in NP score was assessed monthly until 1 month after the last dose
(week 8). Computed tomographic scans were also performed at week 8.
RESULTS: Twelve of 20 patients receiving mepolizumab had a significantly
improved NP score and computed tomographic scan score compared with 1 of 10
patients receiving placebo at week 8 versus baseline.
CONCLUSION: Mepolizumab achieved a statistically significant reduction in NP
size for at least 1 month after dosing in 12 of 20 patients. IL-5 inhibition is
a potential novel therapeutic approach in patients with severe eosinophilic
nasal polyposis. Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation,
maturation, migration, development, survival, trafficking and effector function
of blood and local tissue eosinophils, in addition to basophils and mast cells.
The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts
in conformationally dynamic ways with the receptor's βc subunit, an aggregate of
domains it shares with binding sites of IL-3 and granulocyte-macrophage
colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune
responses characterizing numerous diseases, such as asthma, atopic dermatitis,
chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases,
hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal
polyposis. Although corticosteroid therapy is the primary treatment for these
diseases, a substantial number of patients exhibit incomplete responses and
suffer side-effects. Two monoclonal antibodies have been designed to neutralize
IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability
to reduce blood and tissue eosinophil counts. One additional monoclonal
antibody, benralizumab (MEDI-563), has been developed to target IL-5R and
attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All
three monoclonal antibodies are being clinically evaluated. Antisense
oligonucleotide technology targeting the common βc IL-5R subunit is also being
used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small
interfering RNA technology has also been used therapeutically to inhibit the
expression of IL-5 in animal models. This review summarizes the structural
interactions between IL-5 and IL-5R and the functional consequences of such
interactions, and describes the pre-clinical and clinical evidence supporting
IL-5R as a therapeutic target. INTRODUCTION: Five percent of asthmatics have severe symptoms despite high doses
of inhaled (ICS) or additional oral corticosteroids (OCS): these patients have
high morbidity, risk for asthma death, and account for half of asthma healthcare
spending. A subgroup (20 - 40%) of these has persistent airway eosinophilia and
frequent exacerbations. Mepolizumab is a humanized monoclonal antibody that
blocks binding of the key cytokine implicated specifically in eosinophil
maturation and survival, interleukin-5, to its receptor.
AREAS COVERED: Pharmacology, Phase I/IIa and Phase II/III studies of mepolizumab
for asthma. Mepolizumab depleted blood and sputum eosinophils and partially
reduced airway and bone marrow eosinophils. It also reduced airway remodeling.
In unselected patients with moderate/severe asthma there was no clinically
significant effect on lung function, but a trend to reduced exacerbation rates.
When patients were selected for persistent sputum eosinophilia despite high-dose
ICS/OCS, and frequent exacerbations, mepolizumab reduced exacerbations by 50%.
EXPERT OPINION: Mepolizumab can reduce exacerbation rates in the severe asthma
cohort who have eosinophilic airway inflammation despite corticosteroid
treatment. This may be 30% of severe asthmatics and represents a new and
important treatment option. Further studies need to confirm efficacy and
indications for asthma (and other eosinophilic airway disease), and to examine
clinical consequences of reducing remodeling. BACKGROUND: We examined levels of hyaluro, a matrix glycosaminoglycan and
versican, a matrix proteoglycan, in the sputum of asthmatics treated with
mepolizumab (anti-IL-5 monoclonal antibody) versus placebo to evaluate the
utility of these measurements as possible biomarkers of asthma control and
airway remodeling.
METHODS: Patients with severe, prednisone-dependent asthma received either
mepolizumab or placebo as described in a previously published randomized,
double-blind, placebo-controlled study. We measured hyaluro and versican
levels by enzyme-linked immunosorbent assay in sputum collected before and after
the 16-week treatment phase. Patients underwent a predefined prednisone tapering
schedule if they remained exacerbation free, and sputum eosinophil percentage,
asthma control questionnaire (ACQ) and spirometry were monitored.
RESULTS: After 6 months of mepolizumab therapy and prednisone tapering, there
was a significant increase in sputum hyaluro in the placebo group compared
with baseline (p = 0.003). In contrast, there was a significant decrease in
sputum hyaluro in the active treatment group compared with placebo (p =
0.007), which correlated with improvements in percent forced expiratory volume
in 1 s (FEV1%) (p = 0.001) and ACQ scores (p = 0.009) as well as a decrease in
sputum eosinophils (p = 0.02). There was a nonsignificant increase in sputum
versican in the placebo group (p = 0.16), a decrease in the mepolizumab group (p
= 0.13) and a significant inverse correlation between versican reduction and
FEV1% improvement (p = 0.03).
CONCLUSIONS: Sputum hyaluro values are reduced with mepolizumab therapy and
correlate with improved clinical and spirometry values, suggesting this
measurement may serve as a noninvasive biomarker of asthma control. In this large (616 patients), double-blind, placebo-controlled, dose-ranging
study of mepolizumab (a monoclonal antibody that blocks IL-5 binding to its
receptor), patients were given placebo, 75-, 250- or 750-mg mepolizumab by
intravenous infusion every 4 weeks for 1 year. Exacerbation rates at all doses
were 50% less than those in the placebo group. There were no changes in any
other asthma measures (symptoms, quality of life or lung function). This may be
a useful advance for a subgroup of severe asthma with frequent exacerbations and
persistent eosinophilia, which may be about half of severe asthmatics. More
information on patient selection and cost-benefit will be required. BACKGROUND: Interleukin (IL)-5 is believed to be a key cytokine in eosinophil
inflammatory infiltration in asthma. Previous clinical trials have evaluated the
efficacy and safety of mepolizumab, a monoclonal antibody against IL-5, in
patients with asthma. However, most of these studies were small, the conclusions
were inconsistent, and the precise effects are therefore debatable.
METHODS: A meta-analysis of randomized placebo-controlled trials was conducted
to evaluate the effect of intravenous infusion of mepolizumab on clinical
outcomes in patients with asthma. Trials were searched in PubMed, Embase, Web of
Science, Cochrane CENTRAL, Scopus, reviews, and reference lists of relevant
articles. The outcome variables analyzed included eosinophil counts in blood and
sputum, airways outcome measures, exacerbations, asthma control, and quality of
life scores.
RESULTS: Seven studies met final inclusion criteria (total n = 1131). From the
pooled analyses, mepolizumab significantly reduced eosinophils in blood (MD
-0.29×10(9)/L, 95% CI -0.44 to -0.14×10(9)/L, P = 0.0001) and sputum (MD -6.05%,
95% CI -9.34 to -2.77%, P = 0.0003). Mepolizumab was also associated with
significantly decreased exacerbation risk than placebo (OR 0.30, 95%CI 0.13 to
0.67, P = 0.004), and with a significant improvement in the scores on the Asthma
Quality of Life Questionnaire (AQLQ) (MD 0.26, 95% CI 0.03 to 0.49, P = 0.03) in
patients with eosinophilic asthma. There were no statistical differences between
the groups with respect to FEV1, PEF, or histamine PC20 (all P>0.05), and a
non-significant trend for improvement in scores on the Juniper Asthma Control
Questionnaire (JACQ) (MD -0.21, 95% CI -0.43 to 0.01, P = 0.06) in the
mepolizumab group was observed.
CONCLUSIONS: Mepolizumab reduces the risk of exacerbations and improves quality
of life in patients with eosinophilic asthma, but no significant improvement in
lung function outcomes was observed. Further research is required to establish
the possible role of anti-IL-5 as a therapy for asthma. Several lines of evidence suggest that deficiency of eosinophils is not
associated with any characteristic abnormality. Patients lacking eosinophils, in
the setting of immunodeficiency or as a consequence of IgG-mediated eosinophil
precursor destruction, do not display any distinguishing abnormalities related
to eosinophil reduction. The observation that eosinophil-deficient mice do not
display any distinctive syndrome or failure of their health is evidence that,
under ordinary laboratory conditions, the eosinophil does not play a critical
role in the well-being of mammals. Observations that monoclonal antibodies to
interleukin-5 (IL-5) are well tolerated appear unsurprising in light of these
findings. For example, patients with the hypereosinophilic syndrome have
received mepolizumab, an anti-IL-5 monoclonal antibody, for as long as 6 years
and have not developed any characteristic set of adverse events. Safety data for
reslizumab, another anti-IL-5 monoclonal antibody, and benralizumab, a
monoclonal antibody to the IL-5 receptor α-chain, are comparatively limited,
especially for benralizumab, although reports of administration of these
antibodies to humans suggest that they are well tolerated. Thus, data to the
present suggest that reduction of eosinophils appears to have no characteristic
ill effects on normal health, and monoclonal antibodies that deplete eosinophils
have the potential to be widely employed in the treatment of
eosinophil-associated diseases. PURPOSE OF REVIEW: Eosinophils play an important role in the pathogenesis of
allergic, infectious and maligt diseases. Over the last decade, new
diagnostic tools and treatment modalities have led to the re-evaluation of the
existing definition of eosinophilic disorders. This review discusses a recent
proposal for new terminology and classification of hypereosinophilia. The
results of targeted therapy for hypereosinophilia-related disorders are also
summarized.
RECENT FINDINGS: A panel of multidisciplinary experts agreed on unifying
definitions and criteria of eosinophilia-associated disorders and created a new
classification of hypereosinophilia-related conditions based on clinical,
haematological and laboratory findings as well as the underlying cause of
hypereosinophilia. Recent results of the treatment of idiopathic
hypereosinophilic syndrome (HES) with the anti-interleukin 5 monoclonal antibody
mepolizumab showed its efficacy and manageable safety profile. The treatment of
platelet-derived growth factor alpha (PDGFRA)-positive HES with imatinib
demonstrated long-lasting efficacy and low likelihood of drug resistance.
SUMMARY: The unifying terminology and definitions should aid physicians caring
for patients with hypereosinophilia. Despite much progress, serum biomarkers
correlate with disease severity and predict responses to treatment that are
needed. There is also a great need for understanding and specific therapy for
PDGFRA-negative HES. Eosinophilia-associated myopathies are clinically and pathologically
heterogeneous conditions characterized by the presence of peripheral and/or
muscle eosinophilia. There are at least three distinct subtypes: focal
eosinophilic myositis, eosinophilic polymyositis, and eosinophilic perimyositis.
Infiltrating eosinophils are not always identified in conventional muscle
histologic examination, but the eosinophil major basic protein, whose
extracellular diffusion is considered a hallmark of eosinophilic cytotoxicity,
is usually detected by immunostaining in muscle biopsy. Whereas focal
eosinophilic myositis seems to be a benign and isolated condition, and
perimyositis is usually related with the inflammatory infiltrate due to
fasciitis, eosinophilic polymyositis can be associated with muscular dystrophy
or be a feature of multiorgan hypereosinophilic syndrome. Muscle biopsy remains
the cornerstone for the diagnosis. Parasitic infections, connective tissue
disorders, hematologic and non-hematologic maligcies, drugs, and toxic
substances are the main etiologic agents of eosinophilia-associated myopathy.
However, in some cases, no known etiologic factor is identified, and these are
considered idiopathic. Glucocorticoids are the mainstay therapy in idiopathic
forms. Imatinib and mepolizumab, a humanized anti-interleukin 5 monoclonal
antibody, may be useful in patients with eosinophilic myositis as part of a
hypereosinophilic syndrome. Despite the administration of appropriate treatment, a high number of patients
with asthma remain uncontrolled. This suggests the need for alternative
treatments that are effective, safe and selective for the established asthma
phenotypes, especially in patients with uncontrolled severe asthma. The most
promising options among the new asthma treatments in development are biological
therapies, particularly those monoclonal antibodies directed at selective
targets. It should be noted that the different drugs, and especially the new
biologics, act on very specific pathogenic pathways. Therefore, determination of
the individual profile of predomit pathophysiological alterations of each
patient will be increasingly important for prescribing the most appropriate
treatment in each case. The treatment of severe allergic asthma with anti-IgE
monoclonal antibody (omalizumab) has been shown to be effective in a large
number of patients, and new anti-IgE antibodies with improved pharmacodynamic
properties are being investigated. Among developing therapies, biologics
designed to block certain pro-inflammatory cytokines, such as IL-5 (mepolizumab)
and IL-13 (lebrikizumab), have a greater chance of being used in the clinic.
Perhaps blocking more than one cytokine pathway (such as IL-4 and IL-13 with
dulipumab) might confer increased efficacy of treatment, along with acceptable
safety. Stratification of asthma based on the predomit pathogenic mechanisms
of each patient (phenoendotypes) is slowly, but probably irreversibly, emerging
as a tailored medical approach to asthma, and is becoming a key factor in the
development of drugs for this complex respiratory syndrome. BACKGROUND: Some patients with severe asthma have frequent exacerbations
associated with persistent eosinophilic inflammation despite continuous
treatment with high-dose inhaled glucocorticoids with or without oral
glucocorticoids.
METHODS: In this randomized, double-blind, double-dummy study, we assigned 576
patients with recurrent asthma exacerbations and evidence of eosinophilic
inflammation despite high doses of inhaled glucocorticoids to one of three study
groups. Patients were assigned to receive mepolizumab, a humanized monoclonal
antibody against interleukin-5, which was administered as either a 75-mg
intravenous dose or a 100-mg subcutaneous dose, or placebo every 4 weeks for 32
weeks. The primary outcome was the rate of exacerbations. Other outcomes
included the forced expiratory volume in 1 second (FEV1) and scores on the St.
George's Respiratory Questionnaire (SGRQ) and the 5-item Asthma Control
Questionnaire (ACQ-5). Safety was also assessed.
RESULTS: The rate of exacerbations was reduced by 47% (95% confidence interval
[CI], 29 to 61) among patients receiving intravenous mepolizumab and by 53% (95%
CI, 37 to 65) among those receiving subcutaneous mepolizumab, as compared with
those receiving placebo (P<0.001 for both comparisons). Exacerbations
necessitating an emergency department visit or hospitalization were reduced by
32% in the group receiving intravenous mepolizumab and by 61% in the group
receiving subcutaneous mepolizumab. At week 32, the mean increase from baseline
in FEV1 was 100 ml greater in patients receiving intravenous mepolizumab than in
those receiving placebo (P=0.02) and 98 ml greater in patients receiving
subcutaneous mepolizumab than in those receiving placebo (P=0.03). The
improvement from baseline in the SGRQ score was 6.4 points and 7.0 points
greater in the intravenous and subcutaneous mepolizumab groups, respectively,
than in the placebo group (minimal clinically important change, 4 points), and
the improvement in the ACQ-5 score was 0.42 points and 0.44 points greater in
the two mepolizumab groups, respectively, than in the placebo group (minimal
clinically important change, 0.5 points) (P<0.001 for all comparisons). The
safety profile of mepolizumab was similar to that of placebo.
CONCLUSIONS: Mepolizumab administered either intravenously or subcutaneously
significantly reduced asthma exacerbations and was associated with improvements
in markers of asthma control. (Funded by GlaxoSmithKline; MENSA
ClinicalTrials.gov number, NCT01691521.). BACKGROUND: Many patients with severe asthma require regular treatment with oral
glucocorticoids despite the use of high-dose inhaled therapy. However, the
regular use of systemic glucocorticoids can result in serious and often
irreversible adverse effects. Mepolizumab, a humanized monoclonal antibody that
binds to and inactivates interleukin-5, has been shown to reduce asthma
exacerbations in patients with severe eosinophilic asthma.
METHODS: In a randomized, double-blind trial involving 135 patients with severe
eosinophilic asthma, we compared the glucocorticoid-sparing effect of
mepolizumab (at a dose of 100 mg) with that of placebo administered
subcutaneously every 4 weeks for 20 weeks. The primary outcome was the degree of
reduction in the glucocorticoid dose (90 to 100% reduction, 75 to less than 90%
reduction, 50 to less than 75% reduction, more than 0 to less than 50%
reduction, or no decrease in oral glucocorticoid dose, a lack of asthma control
during weeks 20 to 24, or withdrawal from treatment). Other outcomes included
the rate of asthma exacerbations, asthma control, and safety.
RESULTS: The likelihood of a reduction in the glucocorticoid-dose stratum was
2.39 times greater in the mepolizumab group than in the placebo group (95%
confidence interval, 1.25 to 4.56; P=0.008). The median percentage reduction
from baseline in the glucocorticoid dose was 50% in the mepolizumab group, as
compared with no reduction in the placebo group (P=0.007). Despite receiving a
reduced glucocorticoid dose, patients in the mepolizumab group, as compared with
those in the placebo group, had a relative reduction of 32% in the annualized
rate of exacerbations (1.44 vs. 2.12, P=0.04) and a reduction of 0.52 points
with respect to asthma symptoms (P=0.004), as measured on the Asthma Control
Questionnaire 5 (in which the minimal clinically important difference is 0.5
points). The safety profile of mepolizumab was similar to that of placebo.
CONCLUSIONS: In patients requiring daily oral glucocorticoid therapy to maintain
asthma control, mepolizumab had a significant glucocorticoid-sparing effect,
reduced exacerbations, and improved control of asthma symptoms. (Funded by
GlaxoSmithKline; SIRIUS ClinicalTrials.gov number, NCT01691508.). |
Which is the major symptom of the Doose syndrome? | Myoclonic astatic epilepsy is the major symptom of the Doose syndrome, which is a difficult to treat idiopathic generalized epilepsy of early childhood. | We studied 36 drop seizures in 5 patients with myoclonic astatic epilepsy of
early childhood (MAEE) with simultaneous split-screen video recording and
polygraph. Sixteen were falling attacks and 20 were either less severe attacks
exhibiting only deep head nodding or seizures equivalent to drop attacks in
terms of ictal pattern but recorded in the supine position. All seizures except
those that occurred in patients in the supine position showed sudden momentary
head dropping or collapse of the whole body downward. Recovery to the preictal
position was observed in 0.3-1 s. As a result of carefully repeated
observations, the 36 seizures were classified as myoclonic flexor type in 9,
myoclonic atonic type in 2, and atonic type, with and without transient
preceding symptoms in the remaining 25. The MF seizure was characterized by
sudden forward flexion of the head and trunk as well as both arms, which caused
the patient to fall. In the myoclonic atonic seizure, patients showed brief
myoclonic flexor spasms, immediately followed by atonic falling. The AT seizure
showed abrupt atonic falling, with and without transient preceding facial
expression change and/or twitching of extremities. The ictal EEGs of all 36
seizures exhibited generalized bilaterally synchronous single or multiple
spike(s) and wave discharges. Atonic drop attacks appear to be a common cause of
ictal epileptic falling in MAEE. Among 62 children with myoclonic epilepsy who had first seizures between 1 and
10 years, without clinical or radiological evidence of brain lesion, we selected
the 16 patients who had exhibited several types of fits and had stopped having
seizures for over two years. First seizures occurred between 18 months and 4
years, and they were generalized clonic, tonic-clonic or tonic. After a mean 3
months' period, patients started also to have absence and myoclonic fits. During
the period with various types of seizures, that lasted a mean 10 months,
patients were ataxic and hyperkinetic, and 11 of them suffered myoclonic absence
status for several hours or days. The EEG showed a high voltage rhythmic
slow-wave activity with spikes, differing from the slow spike wave tracing of
the Lennox-Gastaut syndrome, and there was no photosensitivity. The mean
duration of the epilepsy was 1 year and 4 months and the last seizures were
convulsive, occurring mainly during sleep. The clinical and EEG pattern, the
high familial incidence are shared by the Doose syndrome, of which the present
series seems to be a subgroup, as are other well-defined syndromes: benign and
severe myoclonic epilepsies of infancy. A study of epileptic drop attacks (EDA) by simultaneous video-polygraphic
recordings was carried out in one epileptic patient with myoclonic astatic
seizures (Doose syndrome). EDA was shown to correspond to a burst of generalized
bilaterally synchronous spike and wave complexes (GBSSW) at 3 Hz. Absence
seizures were also observed with a burst of GBSSW with similar characteristics.
The amplitudes of the corresponding slow wave component of GBSSW among the three
intensities of atonia, i.e. complete atonia, minor atonia and no discernible
atonia (control), was compared. A high amplitude was demonstrated to correspond
with more pronounced atonia and a lower amplitude with reduced or absent atonia.
These findings suggest that EDA corresponding to GBSSW have a neurophysiological
mechanism in common with absence seizures, and that if the GBSSW is intense, it
may be sufficient to cause immediate loss of global muscle tone. PURPOSE: Before 1986, the spectrum of childhood epilepsies, including
Lennox-Gastaut syndrome (LGS) and Doose syndrome (DS), known collectively as
"epilepsia myoclonica astatica," was believed to represent a single disease.
More recently, some investigators have considered these syndromes to be parts of
a continuum. To clarify these theories, neurobiologic factors of the syndromes
were studied to determine which qualities were shared and which were unique.
METHODS: A retrospective (1975-1985), community-based (Helsinki metropolitan
area and the province of Uusimaa) study was designed to seek children with
features of LGS and DS. It was assumed that recall bias and the selection of
documented history would be similar throughout the group. Ranks of increasing
pathology were assigned to different seizure types, EEG results, and drug
treatments. A similar procedure was applied to epidemiologic data. Spearman
rank-order correlations were calculated to determine which features correlated
with LGS and which correlated with less severe epilepsy.
RESULTS: The survey comprised 75 patients with broadly defined LGS. The annual
incidence was 2 in 100,000 children aged 0 to 14 years. Prenatal or perinatal
abnormalities did not correlate with severity of epilepsy. As compared with the
relatively favorable ranks, the severe epilepsy ranks were more often associated
with an early onset of epilepsy, an infectious disease at the onset, delayed
development before epilepsy, abnormalities in neurologic or neuroradiologic
examinations, and a deteriorating course of the condition.
CONCLUSIONS: Patients with LGS are more likely than patients with less severe
epilepsy to have a younger age at onset of epilepsy, an infection or both, and a
deteriorating course of the condition. One of the most important achievement of contemporary epileptology has been a
concept of epileptic syndromes. According to the Commission on Classification
and Terminology of the International League Against Epilepsy there are many
epileptic syndromes which differ from each other not only by prognosis but also
by reaction to pharmacotherapy. Nevertheless the differentation between the some
of epileptic syndromes may be difficult in spite of quite precise clinical and
electrophysiological criteria. Good example of this problem may be the course of
disease of the boy who is now eleven years old. His refractory epilepsy which
started 7 years ago shares symptoms and signs of both epilepsy with
myoclonic-astatic seizures (Doose Syndrome) and Lennox-Gastaut Syndrome.
Felbamate therapy was consider to be the turning-point in both therapeutic and
diagnostic meaning. Myoclonic astatic epilepsy (MAE) belongs to the epilepsies with generalized
seizures. MAE occurs in 1-2% of all childhood epilepsies up to age 9. This
disease is characterized by various clinical and EEG criteria. The course of
this epileptic syndrome is variable but influenced by an early diagnosis and by
a specific treatment. The purpose of this article is to present a short review of the natural history
of myoclonic astatic epilepsy (MAE; Doose syndrome) and the Lennox-Gastaut
syndrome (LGS). In the 1989 classification of the International League Against
Epilepsy (ILAE, 1989), MAE and LGS were initially included in group 2.2:
"Cryptogenic or symptomatic generalized epilepsies and syndromes." The
subsequent classification of the Proposed Diagnostic Scheme for People with
Epileptic Seizures and with Epilepsy (see Ref. 8) placed MAE in axis 3 in the
"generalized epilepsy" group and LGS, severe myoclonic epilepsy of infancy (SMEI
or Dravet syndrome) and atypical benign partial epilepsy/pseudo-Lennox syndrome
(ABPE/PLS) in the "epileptic encephalopathy" group. The semiology of MAE and LGS
and their differential diagnosis from SMEI and ABPE/PLS are described. Before
the onset of SMEI, MAE, and ABPE/PLS, the development of the child is usually
normal. In contrast, in LGS, development is frequently retarded at the onset,
depending on the etiopathogenesis of the underlying brain disease. The course of
MAE is highly variable with regard to seizure outcome (complete remission in
some cases, persistent epilepsy in others) and cognitive development (normal or
delayed). The course of LGS and SMEI is generally poor, both with regard to the
epilepsy and to the cognitive development whereas the course and seizure outcome
of ABPE/PLS is favorable; the patients will be seizure-free at puberty. However,
the neuropsychological outcome is less favorable; most patients remain mentally
retarded. The ketogenic diet (KD) has been used successfully in a variety of epilepsy
syndromes. This includes syndromes with multiple etiologies, including
Lennox-Gastaut syndrome and infantile spasms; developmental syndromes of unknown
etiology, such as Landau-Kleffner syndrome; and idiopathic epilepsies, such as
myoclonic-astatic (Doose) epilepsy. It also includes syndromes where genetics
play a major role, such as Dravet syndrome, tuberous sclerosis, and Rett
syndrome. Study of the KD in humans and animals harboring various genetic
mutations may yield insights into the diet's mechanisms. Comparison of the
diet's effectiveness with other treatments in specific syndromes may be another
useful tool for mechanistic studies. The diet's utility in epilepsy syndromes of
various etiologies and in some neurodegenerative disorders suggests it may have
multiple mechanisms of action. The antiepileptic drug felbamate has demonstrated efficacy against a variety of
seizure types in the pediatric population, particularly seizures associated with
Lennox-Gastaut syndrome. Postmarketing experience, however, revealed serious
idiosyncratic adverse effects not observed during clinical trials, including
aplastic anemia and liver failure. As a result, many physicians have been
hesitant to prescribe felbamate. This retrospective study evaluated the efficacy
of felbamate in a pediatric population with intractable epilepsy. Of 38
patients, 22 had Lennox-Gastaut syndrome (58%); 6 had myoclonic-astatic epilepsy
of Doose (16%); 5 had symptomatic generalized epilepsy, not otherwise specified
(13%); and 5 had symptomatic localization-related epilepsy (13%). Most patients
had multiple seizure types and had been tried on a variety of antiepileptic
medications. With felbamate treatment, 6 patients (16%) became seizure free,
including 4 of the 6 patients with myoclonic-astatic epilepsy of Doose; 24
patients (63%) had a greater than 50% reduction in seizure frequency. In this
population felbamate appeared to be safe, with minimal adverse effects. The
study is limited by the small number of patients and by its retrospective
nature, but nonetheless adds to the evidence that felbamate is an important
antiepileptic drug for medically refractory epilepsy in children and is well
tolerated with few adverse effects. Doose syndrome, otherwise traditionally known as myoclonic-astatic epilepsy, was
first described as a unique epilepsy syndrome by Dr Hermann Doose in 1970. In
1989, the International League Against Epilepsy classified it formally as a
symptomatic generalized epilepsy, and 20 years later it was renamed 'epilepsy
with myoclonic-atonic seizures'. In this review, we discuss the components of
this unique disorder including its incidence, clinical features, and
electroencephalographic findings. Recent evidence has suggested possible genetic
links to the GEFS+ (generalized epilepsy with febrile seizures plus) family,
and, additionally, some children with structural brain lesions can mimic the
Doose syndrome phenotype. Treatment strategies such as corticosteroids,
ethosuximide, and valproate have been described as only partially effective, but
newer anticonvulsants, such as levetiracetam and zonisamide, may provide
additional seizure control. The most effective treatment reported to date
appears to be the ketogenic diet. Prognosis is quite varied in this disorder;
however, many children can have a remarkably normal neurodevelopmental outcome. Mutations in SCN1A gene, encoding the voltage-gated sodium channel α1-subunit,
are found to be associated with severe myoclonic epilepsy in infancy or Dravet
syndrome (DS), but only rarely with the myoclonic astatic epilepsy (MAE, or
Doose syndrome). We report on two patients with SCN1A mutations and severe
epilepsy within the spectrum of generalized epilepsy with febrile seizures plus
syndrome (GEFS+), the phenotypes being consistent with DS and MAE, respectively.
Analysis of SCN1A revealed a heterozygous de novo frameshift mutation
(c.4205_4208delGAAA) in the patient with DS, and a recurrent missense mutation
(c.3521C>G) in that suffering from MAE. The missense mutation has been reported
in patients with neurological diseases of various manifestations, which suggests
that this variability is likely to result from the modifying effects of other
genetic or environmental factors. DS phenotype has been mainly found associated
with truncation mutations, while predomitly missense mutations and very few
prematurely terminating substitutions have been reported in GEFS+ patients. PURPOSE OF REVIEW: Despite myriad anticonvulsants available and in various
stages of development, there are thousands of children and adults with epilepsy
worldwide still refractory to treatment and not candidates for epilepsy surgery.
Many of these patients will now turn to dietary therapies such as the ketogenic
diet, medium-chain triglyceride diet, modified Atkins diet, and low glycemic
index treatment.
RECENT FINDINGS: In the past several years, neurologists are finding new
indications to use these dietary treatments, perhaps even as first-line therapy,
including infantile spasms, myoclonic-astatic epilepsy (Doose syndrome), Dravet
syndrome, and status epilepticus (including FIRES syndrome). Adults are also one
of the most rapidly growing populations being treated nowadays; this group of
patients previously was not typically offered these treatments. In 2009, two
controlled trials of the ketogenic diet were published, as well as an
International Expert Consensus Statement on dietary treatment of epilepsy.
Ketogenic diets are also now being increasingly studied for neurological
conditions other than epilepsy, including Alzheimer's disease and cancer.
Insights from basic science research have helped elucidate the mechanisms by
which metabolism-based therapy may be helpful, in terms of both an
anticonvulsant and possibly a neuroprotective effect.
SUMMARY: Dietary therapy for epilepsy continues to grow in popularity worldwide,
with expanding use for adults and conditions other than epilepsy. PURPOSE: Myoclonic astatic epilepsy (MAE, Doose syndrome) is a difficult to
treat idiopathic generalized epilepsy of early childhood. MAE frequently shows
the course of an epileptic encephalopathy and may result in permanent cognitive
impairment. Systematic analyses on clinical effects of different AED
combinations are still needed. The purpose of our study was to analyze the
therapeutic effect of adjunctive lamotrigine (LTG) in pharmacoresistant MAE
patients.
PATIENTS AND METHODS: In an exploratory, retrospective study, 10
pharmacoresistant MAE patients were included who had been admitted to the
Northern German Epilepsy Center between 07/2007 and 12/2010 and had been treated
with LTG. Documentation was performed with the electronic seizure diary
Epivista. A total observation period of 32 weeks was defined: 8-week 'pre LTG
treatment phase' (before starting with LTG), 16-week 'titration phase' (starting
with very low LTG doses), 8-week 'follow-up phase'. Seizure frequency,
medication and adverse events were extracted from the electronic diary and
evaluated in each particular patient. The individual reduction of seizure
frequency per day was defined as primary outcome variable. Additionally, a
dose-effect-relationship was analyzed for each patient.
RESULTS: Six out of ten patients were seizure free during the follow-up phase.
Statistical analysis indicated a significant seizure reduction in seven patients
at follow-up compared to the pre LTG treatment phase. Seizure frequency did not
significantly decrease in two patients and increased in one patient. A
significant relationship between seizure frequency per day and LTG dosage during
titration and follow-up phase could be demonstrated in nine patients. Group
statistics using the exact Wilcoxon test revealed a significant reduction in
seizure frequency (p = 0.049, two-sided).
CONCLUSION: Our data provide evidence that adjunctive LTG is an eligible
therapeutic option for the treatment of pharmacoresistant MAE and encourage
further prospective studies to verify this observation. OBJECTIVE: To investigate the effect of ketogenic diet (KD) on the clinical and
electroencephalogram features in children with pharmacoresistant epileptic
encephalopathy.
METHOD: Thirty-one children (19 boys, 12 girls) aged 7 months to 7 years (mean 2
years 5 month) with epilepsy refractory to conventional antiepileptic drugs
(AEDs) were included in this study. In addition to their original AED treatment,
the children were assigned to different ketogenic diets based on their age. The
prospective electro-clinical assessment was performed prior to the KD and then
one week, one month and again 3 months after the initiation of therapy,
respectively.
RESULT: The reduction of seizure frequency in 52%, 68% and 71% of all patients
exceeded 50% one week, one month and three months after KD treatment
respectively. KD is particularly effective in myoclonic astatic epilepsy (MAE;
Doose Syndrome) and West syndrome with 100% and 81.25% of the patients having a
greater than 50% seizure reduction, respectively. After 3 months of KD
treatment, more than 2/3 patients experienced a reduction in interictal
epileptiform discharges (IEDs) and improvement in EEG background.
CONCLUSION: The clinical and electroencephalographic improvement confirms that
KD is beneficial in children with refractory epilepsy. OBJECTIVE: To identify neuronal networks underlying generalized spike and wave
discharges (GSW) in myoclonic astatic epilepsy (MAE).
METHODS: Simultaneous EEG-fMRI recordings were performed in 13 children with
MAE. Individual GSW-associated blood oxygenation level-dependent (BOLD) signal
changes were analyzed in every patient. A group analysis was performed to
determine common syndrome-specific hemodynamic changes across all patients.
RESULTS: GSW were recorded in 11 patients, all showing GSW-associated BOLD
signal changes. Activation was detected in the thalamus (all patients), premotor
cortex (6 patients), and putamen (6 patients). Deactivation was found in the
default mode areas (7 patients). The group analysis confirmed activations in the
thalamus, premotor cortex, putamen, and cerebellum and deactivations in the
default mode network.
CONCLUSIONS: In addition to the thalamocortical network, which is commonly found
in idiopathic generalized epilepsies, GSW in patients with MAE are characterized
by BOLD signal changes in brain structures associated with motor function. The
results are in line with animal studies demonstrating that somatosensory cortex,
putamen, and cerebellum are involved in the generation of myoclonic seizures.
The involvement of these structures might predispose to the typical seizure
semiology of myoclonic jerks observed in MAE. |
Have mutations in the GARS gene been identified to cause Charcot-Marie-Tooth Disease Type 2D (CMT2D)? | Charcot-Marie-Tooth disease type 2D (CMT2D) is caused by missense mutations in the glycyl-tRNA synthetase gene (GARS). | We describe clinical, electrophysiological, histopathological and molecular
features of a unique disease caused by mutations in the glycyl-tRNA synthetase
(GARS) gene. Sixty patients from five multigenerational families have been
evaluated. The disease is characterized by adolescent onset of weakness, and
atrophy of thenar and first dorsal interosseus muscles progressing to involve
foot and peroneal muscles in most but not all cases. Mild to moderate sensory
deficits develop in a minority of patients. Neurophysiologically confirmed
chronic denervation in distal muscles with reduced compound motor action
potentials were features consistent with both motor neuronal and axonal
pathology. Sural nerve biopsy showed mild to moderate selective loss of small-
and medium-sized myelinated and small unmyelinated axons, although sensory nerve
action potentials were not significantly decreased. Based on the presence or
absence of sensory changes, the disease phenotype was initially defined as
distal spinal muscular atrophy type V (dSMA-V) in three families,
Charcot-Marie-Tooth disease type 2D (CMT2D) in a single family, and as either
dSMA-V or CMT2D in patients of another large family. Linkage to chromosome 7p15
and the presence of disease-associated heterozygous GARS mutations have been
identified in patients from each of the five studied families. We conclude that
patients with GARS mutations present a clinical continuum of predomitly motor
distal neuronopathy/axonopathy with mild to moderate sensory involvement that
varies between the families and between members of the same family. Awareness of
these overlapping clinical phenotypes associated with mutations in GARS will
facilitate identification of this disorder in additional families and direct
future research toward better understanding of its pathogenesis. Of the many inherited Charcot-Marie-Tooth peripheral neuropathies, type 2D
(CMT2D) is caused by domit point mutations in the gene GARS, encoding glycyl
tRNA synthetase (GlyRS). Here we report a domit mutation in Gars that causes
neuropathy in the mouse. Importantly, both sensory and motor axons are affected,
and the domit phenotype is not caused by a loss of the GlyRS aminoacylation
function. Mutant mice have abnormal neuromuscular junction morphology and
impaired transmission, reduced nerve conduction velocities, and a loss of
large-diameter peripheral axons, without defects in myelination. The mutant
GlyRS enzyme retains aminoacylation activity, and a loss-of-function allele,
generated by a gene-trap insertion, shows no domit phenotype in mice. These
results indicate that the CMT2D phenotype is caused not by reduction of the
canonical GlyRS activity and insufficiencies in protein synthesis, but instead
by novel pathogenic roles for the mutant GlyRS that specifically affect
peripheral neurons. Sporadic juvenile muscular atrophy of the distal upper extremity or Hirayama's
disease (HD) and autosomal domit motor distal neuronopathy/axonopathy
(CMT2D/dSMA-V), produced by glycyl-tRNA synthetase (GARS) gene mutations, share
some clinical features including: young age of onset, predilection for the
distal upper extremity, asymmetry, sparing of proximal muscles and unusual cold
sensitivity. However, incomplete penetrance of GARS gene mutations may account
for apparently non-familial cases. In order to inquire whether GARS gene
mutations are associated with HD we studied seven patients fulfilling the
clinical and electrodiagnostic criteria for HD. All patients underwent MRI of
cervical spine that excluded compressive myelopathy in neutral position and
intramedullary pathology. Each patient was tested for the presence of mutations
in GARS by sequencing all coding exons amplified from genomic DNA. No pathogenic
mutations were found, excluding the role of GARS gene as a possible factor in
the aetiology of HD in this cohort. Mutations in the GARS gene cause Charcot-Marie-Tooth 2D and distal spinal
muscular atrophy type V - allelic disorders characterized by predomitly
distal upper extremity weakness and atrophy, typically beginning during the
second decade of life. We report monozygotic twin girls with onset of weakness
in infancy and a previously reported GARS mutation within the anticodon-binding
domain. The severity and remarkable similarity in phenotypes of these girls and
the reported case suggest that mutations within the anticodon-binding domain are
more damaging to aminoacyl tRNA synthetase function than those within other
domains of GARS. Charcot-Marie-Tooth disease type 2D is a hereditary axonal and glycyl-tRNA
synthetase (GARS)-associated neuropathy that is caused by a mutation in GARS.
Here, we report a novel GARS-associated mouse neuropathy model using an
adenoviral vector system that contains a neuronal-specific promoter. In this
model, we found that wild-type GARS is distributed to peripheral axons, dorsal
root ganglion (DRG) cell bodies, central axon terminals, and motor neuron cell
bodies. In contrast, GARS containing a G240R mutation was localized in DRG and
motor neuron cell bodies, but not axonal regions, in vivo. Thus, our data
suggest that the disease-causing G240R mutation may result in a distribution
defect of GARS in peripheral nerves in vivo. Furthermore, a distributional
defect may be associated with axonal degradation in GARS-associated
neuropathies. |
Which treatment leads to an increase in neutrophil counts in severe congenital neutropenia? | In phase I/II/III studies in patients with severe congenital and cyclic neutropenia, treatment with recombinant human granulocyte colony-stimulating factor (r-metHuG-CSF) resulted in a rise in the absolute neutrophil counts (ANC) and a reduction in infections | Severe congenital neutropenia (SCN) is a disorder of myelopoiesis characterized
by severe neutropenia or absence of blood neutrophils secondary to a
maturational arrest at the level of promyelocytes. We examined peripheral blood
mononuclear cells (PBMC) of SCN patients who demonstrated normalization of their
blood neutrophil counts in a phase II clinical study with recombit human
granulocyte colony-stimulating factor (rhG-CSF). When stimulated in vitro with
bacterial lipopolysaccharides (LPS), PBMC of those SCN patients produced G-CSF
activity, as judged by proliferation induction of the murine leukemia cell line,
NFS-60. Western and Northern blot analysis showed G-CSF protein and G-CSF-mRNA
indistinguishable in size from those of normal controls. We conclude that PBMC
of the SCN patients tested are capable of synthesizing and secreting
biologically active G-CSF in vitro. STUDY OBJECTIVE: To define the clinical and hematologic effects of recombit
human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on patients
with chronic severe neutropenia.
DESIGN: Open-label, phase II study of rhGM-CSF.
SETTING: Inpatient hematology and surgery clinic at a university medical center.
PATIENTS: Four consecutive patients with chronic severe neutropenia, which in
two cases was complicated by severe infection, in one case by perianal fistula,
and in one case by complete rectal prolapse. Two patients had chronic idiopathic
neutropenia; one patient had congenital neutropenia (myelokathexis); and one
patient had autoimmune neutropenia.
INTERVENTIONS: The rhGM-CSF was given intravenously or subcutaneously at
starting dosages of 150 to 1000 micrograms/m2 body surface area.d for 12 to 14
consecutive days. Two patients received a second course of daily rhGM-CSF
treatment after a nontreatment interval of 14 to 20 days.
MEASUREMENTS AND MAIN RESULTS: In all four patients, the absolute neutrophil
counts increased from less than 0.25 x 10(9)/L to 3.2 to 19.2 x 10(9)/L within 2
weeks of beginning rhGM-CSF therapy. Two patients had life-threatening
infections that resolved during therapy. The two other patients had major
ano-rectal surgery during rhGM-CSF treatment and had no postoperative
infections.
CONCLUSIONS: In patients with chronic neutropenia, rhGM-CSF may increase
neutrophil counts. This therapy may be a useful adjunct to antibiotic therapy
for patients with infection and perioperatively for patients having anorectal
surgery. Congenital neutropenias include a heterogenous group of diseases characterized
by a decrease in circulating neutrophils. In phase I/II/III studies in patients
with severe congenital and cyclic neutropenia, treatment with recombit human
granulocyte colony-stimulating factor (r-metHuG-CSF) resulted in a rise in the
absolute neutrophil counts (ANC) and a reduction in infections. We report the
effects of long-term safety of subcutaneous r-metHuG-CSF administration in 54
patients (congenital n = 44. cyclic n = 10) treated for 4-6 years. A sustained
ANC response was seen in 40/44 severe congenital neutropenia patients and 10/10
cyclic neutropenia patients. Two patients required an increase of > 25% in dose
to maintain a clinical response; one patient became refractory to therapy. A
significant decrease in the incidence of severe infections and the need for
intravenous antibiotics was noted. Significant adverse events noted which may or
may not be related to therapy included: osteopenia (n = 15), splenomegaly (n =
12), hypersplenism (n = 1), vasculitis (n = 2), glomerulonephritis (n = 1), BM
fibrosis (n = 2), MDS/leukaemia (n = 3), and transient inverted chromosome 5q
with excess blasts (n = 1). R-metHuG-CSF has been well tolerated in the majority
of patients and resulted in a long-term improvement in their clinical status. Severe congenital neutropenia (SCN) or Kostmann syndrome is a disorder of
myelopoiesis characterized by a maturation arrest at the stage of promyelocytes
or myelocytes in bone marrow and absolute neutrophil counts less than 200/microL
in peripheral blood. Treatment of these patients with granulocyte
colony-stimulating factor (G-CSF) leads to a significant increase in circulating
neutrophils and a reduction in infection-related events in more than 95% of the
patients. To date, little is known regarding the underlying pathomechanism of
SCN. G-CSF-induced neutrophils of patients with SCN are functionally defective
(eg, chemotaxis, superoxide anion generation, Ca(++ )mobilization). Two
guanosine triphosphatases (GTPases), Rac2 and RhoA, were described to be
involved in many neutrophil functions. The expression of these GTPases and their
regulation in patients' neutrophils were of interest. This study determined that
the guanosine diphosphate (GDP)-dissociation inhibitor RhoGDI is overexpressed
at the protein level in patients' neutrophils and that overexpression is a
result of G-CSF treatment. RhoA and LyGDI are expressed at similar levels,
whereas Rac2 shows a decreased expression. In addition, association of Rac2 and
RhoGDI or LyGDI is abrogated or not detectable based on the low Rac2 expression
in patients' neutrophils. (Blood. 2000;95:2947-2953) Severe congenital neutropenia (CN) includes a variety of hematologic disorders
characterized by severe neutropenia, with absolute neutrophil counts (ANC) below
0.5 x 10(9)/L, and associated with severe systemic bacterial infections from
early infancy. One subtype of CN, Kostmann syndrome, is an autosomal recessive
disorder, characterized histopathologically by early-stage maturation arrest of
myeloid differentiation. CN with similar clinical features occurs as an
autosomal domit disorder and many sporadic cases also have been reported.
This genetic heterogeneity suggests that several pathophysiological mechanisms
may lead to this common clinical phenotype. Recent studies on the genetic bases
of CN have detected inherited or spontaneous point mutations in the neutrophil
elastase gene (ELA 2) in about 60% to 80% of patients and, less commonly,
mutations in other genes. Acquisition of additional genetic defects during the
course of the disease, for example, granulocyte colony-stimulating factor
(G-CSF) receptor gene mutations and cytogenetic aberrations, indicates an
underlying genetic instability as a common feature for all congenital
neutropenia subtypes. Data on more than 600 patients with CN collected by the
Severe Chronic Neutropenia International Registry (SCNIR) demonstrate that,
regardless of the particular CN subtype, more than 95% of these patients respond
to recombit human (rHu)G-CSF with ANCs that can be maintained above 1.0 x
10(9)/L. Adverse events include mild splenomegaly, osteoporosis, and maligt
transformation into myelodysplasia (MDS)/leukemia. If and how G-CSF treatment
impacts on these adverse events is not fully understood. In recent analyses the
influence of the G-CSF dose required to achieve neutrophil response (ANC
>1,000/microL) in the risk of developing acute myeloid leukemia (AML) has been
reported. Hematopoietic stem cell transplantation (HSCT) is still the only
treatment available for patients who are refractory to G-CSF treatment. Patients with severe chronic neutropenia have blood neutrophil level <0.5 ×
10(9)/L, predisposing them to increased susceptibility to life-threatening
bacterial infections. This chapter focuses on cyclic and congenital neutropenia,
two very interesting and rare hematological conditions causing severe chronic
neutropenia. Both disorders respond well to treatment with the myeloid growth
factor, granulocyte colony-stimulating factor (G-CSF). This chapter describes
the basic features of these diseases and addresses several current clinical
issues regarding their diagnosis and management. Cyclic neutropenia is a rare,
inherited autosomal domit disorder due to mutations in the gene for
neutrophil elastase (ELA-2 or ELANE). Usually these patients have regular
oscillation of blood neutrophil counts with periods of severe neutropenia
occurring every 21 days. During these periods, they have painful mouth ulcers,
fevers, and bacterial infections. The most severe consequences are gangrene,
bacteremia, and septic shock. Cyclic neutropenia patients respond well to
treatment with granulocyte colony-stimulating factor (G-CSF) given by
subcutaneous injections on a daily or alternate-day basis. Severe congenital
neutropenia is also a rare hematological disease, but it is probably more common
than cyclic neutropenia. Blood neutrophils are extremely low on a continuing
basis; the levels may be <0.2 × 10(9)/L, and the risk of severe bacterial
infections is even greater than in cyclic neutropenia. The majority of cases are
due to autosomal domit inheritance of mutations in the ELA-2 or ELANE gene.
Less commonly, mutations in HAX-1, G6PC3, and other genes cause this disorder.
Treatment with G-CSF is usually effective, but the dose of G-CSF required to
normalize blood neutrophils varies greatly. Ten to thirty percent of severe
congenital neutropenia patients evolve to develop acute myeloid leukemia,
necessitating careful clinical monitoring. |
Which genes are affected in ROMANO-WARD syndrome? | The genes involved in ROMANO-WARD syndrome are KCNQ1, KCNE1, KCNE2, KCNH2, SCN5A, CAV3, SCN4B, AKAP9, SNTA1, KCNJ5 and Ankyrin-B. | Once limited to discussions of the Jervell and Lange-Nielsen syndrome and
Romano-Ward syndrome, the long QT syndrome (LQTS) is now understood to be a
collection of genetically distinct arrhythmogenic cardiovascular disorders
resulting from mutations in fundamental cardiac ion channels that orchestrate
the action potential of the human heart. Our understanding of this genetic
"channelopathy" has increased dramatically from electrocardiographic depictions
of marked QT interval prolongation and torsades de pointes and clinical
descriptions of people experiencing syncope and sudden death to molecular
revelations in the 1990s of perturbed ion channel genes. More than 35 mutations
in four cardiac ion channel genes--KVLQT1 (voltage-gated K channel gene causing
one of the autosomal domit forms of LQTS) (LQT1), HERG (human ether-a-go-go
related gene.) (LQT2), SCN5A (LQT3), and KCNE1 (minK, LQT5)--have been
identified in LQTS. These genes encode ion channels responsible for three of the
fundamental ionic currents in the cardiac action potential. These exciting
molecular break-throughs have provided new opportunities for translational
research with investigations into genotype-phenotype correlations and
gene-targeted therapies. BACKGROUND: The congenital long-QT syndrome (LQTS) is a genetically
heterogeneous disease characterized by prolonged ventricular repolarization and
life-threatening arrhythmias. Mutations of the KVLQT1 gene, a cardiac potassium
channel, generate two allelic diseases: the Romano-Ward syndrome, inherited as a
domit trait, and the Jervell and Lange-Nielsen syndrome, inherited as an
autosomal recessive trait.
METHODS AND RESULTS: A consanguineous family with the clinical phenotype of LQTS
was screened for mutations in the KVLQT1 gene. Complementary RNAs for injection
into Xenopus oocytes were prepared, and currents were recorded with the double
microelectrode technique. A homozygous missense mutation, leading to an
alanine-to-threonine substitution at the beginning of the pore domain of the
KVLQT1 channel, was found in the proband, a 9-year-old boy with normal hearing,
a prolonged QT interval, and syncopal episodes during physical exercise. The
parents of the proband were heterozygous for the mutation and had a normal QT
interval. The functional evaluation of the mutant channel activity showed
reduction in total current, a hyperpolarizing shift in activation, and a faster
activation rate consistent with a mild mutation likely to require homozygosity
to manifest the phenotype.
CONCLUSIONS: These findings provide the first evidence for a recessive form of
the Romano-Ward long-QT syndrome and indicate that homozygous mutations on
KVLQT1 do not invariably produce the Jervell and Lange-Nielsen syndrome. The
implications of this observation prompt a reconsideration of the penetrance of
different mutations responsible for LQTS and suggest that mild mutations in LQTS
genes may be present among the general population and may predispose to
drug-induced ventricular arrhythmias. Recent discoveries of genes involved in long-QT syndrome (LQTS) have led to
extensive progress in understanding the molecular basis for this disorder of
syncope and sudden cardiac death secondary to ventricular arrhythmias. The
emerging unifying theme is that all genes identified to date encode either
structural or regulatory subunits for ion channels involved in cardiac
repolarization. Defects have been identified in the KCNQ1, HERG, and KCNE1
genes, whose proteins form the K+ channels for the slowly and rapidly inwardly
rectifying K+ currents IKs and IKr. Depending on their location and copy number,
mutations of KCNQ1 and KCNE1 can cause either autosomal domit Romano-Ward
syndrome or autosomal recessive Jervell and Lange-Nielsen syndrome. The cardiac
sodium channel gene, SCN5A, is also mutated in some Romano-Ward cases to produce
defects in INa, the cardiac inward Na+ current. The fact that multiple genes are
involved and that most LQTS mutations are "private" or "family-specific"
complicates molecular diagnosis of LQTS which, currently, is limited to a small
number of research laboratories. In future, genotypic determination of LQTS
patients and their family members will hopefully lead to improved gene-specific
prognostic determinations and therapeutic interventions. Romano-Ward syndrome is an autosomal domit long-QT syndrome (LQTS) that
predisposes affected individuals to sudden death from tachyarrhythmias. We
investigated the molecular basis of LQTS in a Taiwanese kindred. Clinical and
genetic analyses revealed that a mutation was linked to the human
ether-a-go-go-related gene (HERG). The coding sequences and exon-intron borders
of HERG were amplified by means of polymerase chain reaction and subjected to
single-strand conformation polymorphism (SSCP) analysis. An exon with an
aberrant SSCP pattern was cloned and sequenced to study the molecular lesion. A
C-->T transition in codon 614, leading to substitution of a valine for an
alanine residue in the pore region of the HERG protein, was identified. Analysis
with Bsp12861 endonuclease digestion showed the mutation to be present in all
affected family members. Given that an unaffected paternal uncle had inherited
the same allele from the grandfather as the proband's father, a de novo mutation
had apparently occurred in the father and was transmitted to his offspring. In
addition to offering presymptomatic genetic diagnosis, identification of the
disease-causing mutation may suggest new therapeutic approaches for treatment
and prevention of this cardiovascular disease. It is becoming clear that mutations in the KVLQT1, human "ether-a-go-go" related
gene, cardiac voltage-dependent sodium channel gene, minK and MiRP1 genes,
respectively, are responsible for the LQT1, LQT2, LQT3, LQT5 and LQT6 variants
of the Romano-Ward syndrome, characterized by autosomal domit transmission
and no deafness. The much rarer Jervell-Lange-Nielsen syndrome (with marked QT
prolongation and sensorineural deafness) arises when a child inherits mutant
KVLQT1 or minK alleles from both parents. In addition, some families are not
linked to the known genetic loci. Cardiac voltage-dependent sodium channel gene
encodes the cardiac sodium channel, and long QT syndrome (LQTS) mutations
prolong action potentials by increasing inward plateau sodium current. The other
mutations cause a decrease in net repolarizing current by reducing potassium
currents through "domit negative" or "loss of function" mechanisms.
Polymorphic ventricular tachycardia (torsade de pointes) is thought to be
initiated by early after-depolarizations in the Purkinje system and maintained
by reentry in the myocardium. Clinical presentations vary with the specific gene
affected and the specific mutation. Nevertheless, patients with identical
mutations can also present differently, and some patients with LQTS mutations
may have no manifest baseline phenotype. The question of whether the latter
situation is one of high risk for administration of QT prolonging drugs or
during myocardial ischemia is under active investigation. More generally, the
identification of LQTS genes has provided tremendous new insights for our
understanding of normal cardiac electrophysiology and its perturbation in a wide
range of conditions associated with sudden death. It seems likely that the
approach of applying information from the genetics of uncommon congenital
syndromes to the study of common acquired diseases will be an increasingly
important one in the next millennium. INTRODUCTION: Progress in molecular genetics contributed to the discovery of
pathophysiologic mechanisms of hereditary diseases as well as better diagnostics
and efficient therapy. Several defective ge- nes have been discovered on
different chromosomes (3,4,7,11 and 21 pair of chromosomes), and also their
relationship with some types of LQTS (long QT syndrome). Gene dysfunction leads
to the dysfunction of ion channels, which consequently causes prolonged duration
of repolarization in cardiac muscle. These changes are manifested on
electrocardiogram with prolonged duration of QT interval (over 0.44 sec.).
Familial forms of LQTS are inherited as autosomal domit (Roman Ward syndrome)
and autosomal recessive (Jervell Lange-Neilsen syndrome). The final form of LQTS
is defined even with hearing loss. Clinical survey: maligt ventricular
arrhythmia, syncope and sudden death. MOLECULAR ARCHITECTURE OF VOLTAGE-GATED
ION CHANNELS: Duration of voltage-gated ion can be regulated by Na and K
channels. Cardiac action potential plateau is an indicator of the balance of
inward and outward ionic currents. During this process of voltage-gated
potential two currents are activated: depolarized inward current (it happens in
the Na channels) and repolarized outward current (it happens in the K channels).
Na channels are polypeptides incorporated in cell membrane. Their main function
is to control excitability in myocardial cell. They consist of two subunits:
alpha and beta. Class Ib of anty-arrhythmics (Lidocaine, Mexiletine and
Tocainide) as well as Diphenylhydantoin blocks Na channels in the state of
inactivation, in fact, during the depolarization of the cell. For controlling
the cardiac voltage-gated potential the most important are voltage-sensitive K
channels. For appearance of K ions delayed refraction of K channels (Kv) is of
importance. Depending on the velocity of activation, Kv are divided into two
groups: channels with rapid activation (Kvr) and channels with slow activation
(Kvs). By activation of these delayed rectification channels (Kv) beta agonists
shorten the action potential of the heart.
GENETIC ASPECTS OF LQTS: Five loci which are connected with Romano Ward's
familial form of LQTS have been described up to now. Specific mutant gene is
responsible for function of K channels and it is located on short branch (part)
of the 11-th pair of chromosome 11p15.5 (KVLQT-LQT1), long branch of the 7-th
pair of chromosomes 7q35-36 (K- HERG-LQT2), as well as on the 21-st pair of
chromosome (KCNE1-LQT5). Defective gene which is responsible for the function of
Na channels is located on the short branch of chromosome 3p21-24 (SCN5A-LQT3).
The gene which is located on the long branch of the 4-th pair of chromosome
4q25-27 (LQT4) has not been examined sufficiently. Persons with Jevell
Lange-Neilsen syndrome inherit pathological allele from both parents (KvLQT1 or
LQT5-minK).
CONNECTION BETWEEN ION CHANNELS AND GENE MUTATION: Among all genes which are
responsible for LQTS the most examined one is the so-called HERG gene located on
the 7-th pair of chromosome (LQT2). Mutation of this gene leads to reduction in
strength of outward K currents or to the dysfunction of K channel proteins.
Mutant gene causes so-called missense mutation, in fact wrong change of amino
acid in the protein chain. Among all described LQTS the most frequent and the
most maligt form is LQT1. In 99% cases psychophysical stress can cause
arrhythmia, syncope or sudden death. LQT3 and LQT5 are very rare.
CONCLUSION: Genetic screening in LQTS patients provides discovery of risk
population which demands anti-arrhythmic therapy with beta-blockers. A lot of
arguments speak in favour of genetic screening in cases with LQTS. It is
considered that if the diagnosis is known, genetic testing is not necessary, but
it is useful. Moreover, it is obligatory in symptomatic cases as well as in
those with suspected diagnosis of LQTS. OBJECTIVES: We took advantage of the genetic isolate of Finns to characterize a
common long QT syndrome (LQTS) mutation, and to estimate the prevalence of LQTS.
BACKGROUND: The LQTS is caused by mutations in different ion channel genes,
which vary in their molecular nature from family to family.
METHODS: The potassium channel gene KCNQ1 was sequenced in two unrelated Finnish
patients with Jervell and Lange-Nielsen syndrome (JLNS), followed by genotyping
of 114 LQTS probands and their available family members. The functional
properties of the mutation were studied using a whole-cell patch-damp technique.
RESULTS: We identified a novel missense mutation (G589D or KCNQ1-Fin) in the
C-terminus of the KCNQ1 subunit. The voltage threshold of activation for the
KCNQ1-Fin channel was markedly increased compared to the wild-type channel. This
mutation was present in homozygous form in two siblings with JLNS, and in
heterozygous form in 34 of 114 probands with Romano-Ward syndrome (RWS) and 282
family members. The mean (+/- SD) rate-corrected QT intervals of the
heterozygous subjects (n = 316) and noncarriers (n = 423) were 460 +/- 40 ms and
410 +/- 20 ms (p < 0.001), respectively.
CONCLUSIONS: A single missense mutation of the KCNQ1 gene accounts for 30% of
Finnish cases with LQTS, and it may be associated with both the RWS and JLNS
phenotypes of the syndrome. The relative enrichment of this mutation most likely
represents a founder gene effect. These circumstances provide an excellent
opportunity to examine how genetic and nongenetic factors modify the LQTS
phenotype. KCNQ1 (formerly called KVLQT1) is a Shaker-like voltage-gated potassium channel
gene responsible for the LQT1 sub-type of LQTS. In general, heterozygous
mutations in KCNQ1 cause Romano-Ward syndrome (LQT1 only), while homozygous
mutations cause JLNS (LQT1 and deafness). To date, more than 100 families with
mutations in this gene have been reported, most with their own novel 'private'
mutations. The majority of these mutations are missense. However, other types of
mutations, such as deletions, frame-shifts and splice-donor errors have also
been reported. There is one frequently reported mutated region (the 'hot-spot').
KCNQ1 is now believed to be the most commonly mutated gene in LQTS. The
combination of normal and mutant KCNQ1 alpha-subunits has been found to form
abnormal IKS channels, hence mutations associated with the KCNQ1 gene are also
believed to act mainly through a domit-negative mechanism (the mutant form
interferes with the function of the normal wild-type form through a 'poison
pill' type mechanism) or loss of function mechanism. Even in the case of
carriers of the same mutation, it is currently unknown why there are significant
clinical phenotype variations in LQT1 patients. This question could be answered
by increasing the number of patient genotypes studied. LQT1 patients experience
a majority of their cardiac events (62%) during exercise, and only 3% occur
during rest or sleep. Of the patients who experienced cardiac events while
swimming, 99% were LQT1. Auditory stimuli are rare and occur in only 2% of
patients. However, both lethal and non-lethal events follow the same pattern. The congenital long QT syndrome (LQTS) is characterized by a prolonged QT
interval on the surface electrocardiogram and an increased risk of recurrent
syncope and sudden cardiac death. Mutations in seven genes have been identified
as the molecular basis of LQTS. beta-blockers are the treatment of choice to
reduce cardiac symptoms. However, long-term follow-up of genotyped families with
LQTS has been rarely reported. We have clinically followed a four-generation
family with LQTS being treated with beta-blocker therapy over a period of 23
years. Seven family members were carriers of two amino acid alterations in cis
(V254M-V417M) in the cardiac potassium channel gene KCNQ1. Voltage-clamp
recordings of mutant KCNQ1 protein in Xenopus oocytes showed that only the V254M
mutation reduced the IKs current and that the effect of the V417M variant was
negligible. The family exhibited the complete clinical spectrum of the disease,
from asymptomatic patients to victims of sudden death before beta-blocker
therapy. There was no significant reduction in QTc (556 +/- 40 ms(1/2) before
therapy, 494 +/- 20 ms(1/2) during 17 years of treatment; n = 5 individuals). Of
nine family members, one female died suddenly before treatment, three females of
the second generation were asymptomatic, and four individuals of the third and
fourth generation were symptomatic. All mutation carriers were treated with
beta-blockers and remained asymptomatic for a follow-up up to 23 years.
Long-term follow-up of a LQT1 family with a common mutation (V254M) being on
beta-blocker therapy was effective and safe. This study underscores the
importance of long-term follow-up in families with specific LQT mutations to
provide valuable information for clinicians for an appropriate antiarrhythmic
treatment. Romano-Ward syndrome (RWS), the autosomal domit form of the congenital long
QT syndrome, is characterised by prolongation of the cardiac repolarisation
process associated with ventricular tachyarrhythmias of the torsades de pointes
type. Genetic studies have identified mutations in six ion channel genes, KCNQ1,
KCNH2, SCN5A, KCNE1 and KCNE2 and the accessory protein Ankyrin-B gene, to be
responsible for this disorder. Single-strand conformation polymorphism (SSCP)
analysis and subsequent DNA sequence analysis have identified a KCNQ1 mutation
in a family that were clinically conspicuous due to several syncopes and
prolonged QTc intervals in the ECG. The mutant subunit was expressed and
functionally characterised in the Xenopus oocyte expression system. A novel
heterozygous missense mutation with a C to T transition at the first position of
codon 343 (CCA) of the KCNQ1 gene was identified in three concerned family
members (QTc intervals: 500, 510 and 530 ms, respectively). As a result, proline
343 localised within the highly conserved transmembrane segment S6 of the KCNQ1
channel is replaced by a serine. Co-expression of mutant (KCNQ1-P343S) and
wild-type (KCNQ1) cRNA in Xenopus oocytes produced potassium currents reduced by
approximately 92%, while IKs reconstitution experiments with a combination of
KCNQ1 mutant, wild-type and KCNE1 subunits yielded currents reduced by
approximately 60%. A novel mutation (P343S) identified in the KCNQ1 subunit gene
of three members of a RWS family showed a domit-negative effect on native IKs
currents leading to prolongation of the heart repolarisation and possibly
increases the risk of malign arrhythmias with sudden cardiac death. OBJECTIVE: Hereditary long QT syndrome (LQTS) is a genetically heterogeneous
disease characterized by prolonged QT intervals and an increased risk for
ventricular arrhythmias and sudden cardiac death. Mutations in the voltage-gated
potassium channel subunit KCNQ1 induce the most common form of LQTS. KCNQ1 is
associated with two different entities of LQTS, the autosomal-domit
Romano-Ward syndrome (RWS), and the autosomal-recessive Jervell and
Lange-Nielsen syndrome (JLNS) characterized by bilateral deafness in addition to
cardiac arrhythmias. In this study, we investigate and discuss domit-negative
I(Ks) current reduction by a KCNQ1 deletion mutation identified in a RWS family.
METHODS: Single-strand conformation polymorphism analysis and direct sequencing
were used to screen LQTS genes for mutations. Mutant KCNQ1 channels were
heterologously expressed in Xenopus oocytes, and potassium currents were
recorded using the two-microelectrode voltage clamp technique.
RESULTS: A heterozygous deletion of three nucleotides (CTT) identified in the
KCNQ1 gene caused the loss of a single phenylalanine residue at position 339
(KCNQ1-deltaF339). Electrophysiological measurements in the presence and absence
of the regulatory beta-subunit KCNE1 revealed that mutant and wild type forms of
an N-terminal truncated KCNQ1 subunit (isoform 2) caused much stronger
domit-negative current reduction than the mutant form of the full-length
KCNQ1 subunit (isoform 1).
CONCLUSION: This study highlights the functional relevance of the truncated
KCNQ1 splice variant (isoform 2) in establishment and mode of inheritance in
long QT syndrome. In the RWS family presented here, the autosomal-domit trait
is caused by multiple domit-negative effects provoked by heteromultimeric
channels formed by wild type and mutant KCNQ1-isoforms in combination with
KCNE1. OBJECTIVE: Hereditary long QT syndrome (LQTS) is a cardiac disorder
characterized by prolongation of QT interval on electrocardiograms (ECGs) and
syncope and sudden death caused by a specific multi-polymorphic ventricular
tachyarrhythmia known as torsade de pointes. LQTS is caused by mutations in
cardiac sodium channel gene SCN5A; potassium channel subunit genes KCNQ1, KCNH2,
KCNE1, KCNE2, KCNJ2; calcium channel gene Cav2.1. and ankyrin-B gene ANK2.
METHODS: We characterized 77 Chinese LQTS patients with clinical manifestations
and mutations in the main LQTS genes, KCNQ1 and KCNH2 using PCR and sequence
analysis.
RESULTS: The spectrum of ST-T-wave patterns of 24 (31.2%) probands were
considered as LQT1, 42 (54.5%) as LQT2 and 3 (3.9%) as LQT3. The remaining 8
(10.3%) could not be characterized. The average age for this population of LQTS
patients was (27.6 +/- 16.4) years and the average QTc (561 +/- 70) ms, and the
age of the first syncopal attack was (17.6 +/- 14.7) years. The triggering
factors for cardiac events happening in these mutation carriers included
physical exercise, emotional excitement and auditory irritation. We identified 4
KCNQ1 mutations and 7 KCNH2 mutations. Six of them were first identified with
some data already shown. In this paper we showed the data of 6 other mutations.
CONCLUSIONS: LQT2 is the most common type of LQTS in Chinese; 2 mutations of
KCNQ1 and KCNH2 were first identified in this report; there are some differences
between Chinese and North American or European LQTS patients in clinical
characters and ECG. BACKGROUND: Anesthesia in patients with long QT syndrome (LQTS) is a matter of
concern. Congenital LQTS is most frequently caused by mutations in KCNQ1
(Kv7.1), whereas drug-induced LQTS is a consequence of HERG (human
ether-a-go-go-related gene) channel inhibition. The aim of this study was to
investigate whether the LQT1 mutation A344V in the S6 region of KCNQ1, at a
position corresponding to the local anesthetic binding site in HERG, may render
drug insensitive KCNQ1 channels into a toxicologically relevant target of these
pharmacologic agents. This may suggest that LQTS constitutes not only a
nonspecific but also a specific pharmacogenetic risk factor for anesthesia.
METHODS: The authors examined electrophysiologic and pharmacologic properties of
wild-type and mutant KCNQ1 channels. The effects of bupivacaine, ropivacaine,
and mepivacaine were investigated using two-electrode voltage clamp and whole
cell patch clamp recordings.
RESULTS: The mutation A344V induced voltage-dependent inactivation in homomeric
KCNQ1 channels and shifted the voltage dependence of KCNQ1/KCNE1 channel
activation by +30 mV. The mutation furthermore increased the sensitivity of
KCNQ1/KCNE1 channels for bupivacaine 22-fold (KCNQ1wt/KCNE1: IC50 = 2,431 +/-
582 microM, n = 20; KCNQ1A344V/KCNE1: IC50 = 110 +/- 9 microM, n = 24).
Pharmacologic effects of the mutant channels were domit when mutant and
wild-type channels were coexpressed. Simulation of cardiac action potentials
with the Luo-Rudy model yielded a prolongation of the cardiac action potential
duration and induction of early afterdepolarizations by the mutation A344V that
were aggravated by local anesthetic intoxication.
CONCLUSIONS: The results indicate that certain forms of the LQTS may constitute
a specific pharmacogenetic risk factor for regional anesthesia. In a 7-year-old boy with normal hearing suffering from repeated syncope an
extremely prolonged QTc interval (up to 700 ms) was found. The mother was
completely asymptomatic and the father had an intermittently borderline QTc
interval (maximum 470 ms) but no symptoms. In the proband a mutation analysis of
KCNQ1 gene revealed a homozygous 1893insC mutation. The parents were
heterozygous for this mutation. There was no consanguineous marriage in the
family. The clinical relevance of these findings is that apparently normal
individuals may have a latent reduction of repolarizing currents, a "reduced
repolarization reserve," because they are carriers of latent ion channel genes
mutations. Mutations in the KCNQ1, HERG, SCN5A, minK and MiRP1 genes cause long QT syndrome
(LQTS), of which there are two forms: the Romano Ward syndrome and the Jervell
and Lange-Nielsen syndrome. We have performed DNA sequencing of the
LQTS-associated genes in 169 unrelated patients referred for genetic testing
with respect to Romano Ward syndrome and in 13 unrelated patients referred for
genetic testing with respect to Jervell and Lange-Nielsen syndrome. A total of
37 different mutations in the 5 genes, of which 20 were novel, were identified.
Among patients with the most stringent clinical criteria of Romano Ward
syndrome, a mutation was identified in 71%. Twelve of the 13 unrelated patients
referred for genetic testing with respect to Jervell and Lange-Nielsen syndrome
were provided with a molecular genetic diagnosis. Cascade genetic screening of
505 relatives of index patients with molecularly defined LQTS identified 251
mutation carriers. The observed penetrance was 41%. Although caution must be
exerted, the prevalence of heterozygotes for mutations in the LQTS-associated
genes in Norway could be in the range 1/100-1/300, based on the prevalence of
patients with Jervell and Lange-Nielsen syndrome. Hereditary long QT syndrome (LQTS) is a cardiovascular disorder characterized by
prolongation of the QT interval on the surface ECG and a high risk for
arrhythmia-related sudden death. Mutations in a cardiac voltage-gated potassium
channel, KCNQ1, account for the most common form of LQTS, LQTS1. The objective
of this study was the characterization of a novel KCNQ1 mutation linked to LQTS.
Electrophysiological properties and clinical features were determined and
compared to characteristics of a different mutation at the same position.
Single-strand conformation polymorphism analysis followed by direct sequencing
was performed to screen LQTS genes for mutations. A novel missense mutation in
the KCNQ1 gene, KCNQ1 P320H, was identified in the index patient presenting with
recurrent syncope and aborted sudden death triggered by physical stress and
swimming. Electrophysiological analyses of KCNQ1 P320H and the previously
reported KCNQ1 P320A mutation indicate that both channels are non-functional and
suppress wild type I(Ks) in a domit-negative fashion. Based on homology
modeling of the KCNQ1 channel pore region, we speculate that the proline residue
at position 320 limits flexibility of the outer pore and is required to maintain
the functional architecture of the selectivity filter/pore helix arrangement.
Our observations on the KCNQ1 P320H mutation are consistent with previous
studies indicating that pore mutations in potassium channel alpha-subunits are
associated with more severe electrophysiological and clinical phenotypes than
mutations in other regions of these proteins. This study emphasizes the
significance of mutation screening for diagnosis, risk-assessment, and
mutation-site specific management in LQTS patients. BACKGROUND: Loss-of-function mutations in the gene KCNQ1 encoding the Kv7.1 K(+)
channel cause long QT syndrome type 1 (LQT1), whereas gain-of-function mutations
are associated with short QT syndrome as well as familial atrial fibrillation
(FAF). However, KCNQ1 mutation pleiotropy, which is capable of expressing both
LQT1 and FAF, has not been demonstrated for a discrete KCNQ1 mutation. The
genotype-phenotype relationship for a family with FAF suggests a possible
association with the LQT1 p.Arg231Cys-KCNQ1 (R231C-Q1) mutation.
OBJECTIVE: The purpose of this study was to determine whether R231C-Q1 also can
be linked to FAF.
METHODS: The R231C-Q1 proband with AF underwent genetic testing for possible
mutations in 10 other AF-linked genes plus KCNH2 and SCN5A. Sixteen members from
five other R231C-positive LQT1 families were genetically tested for 21 single
nucleotide polymorphisms (SNPs) to determine if the FAF family had
discriminatory SNPs associated with AF. R231C-Q1 was expressed with KCNE1 (E1)
in HEK293 cells, and Q1E1 currents (I(Q1E1)) were analyzed using the whole-cell
patch-clamp technique.
RESULTS: Genetic analyses revealed no additional mutations or discriminatory
SNPs. Cells expressing WT-Q1 and R231C-Q1 exhibited some constitutively active
I(Q1E1) and smaller maximal I(Q1E1) compared to cells expressing WT-Q1.
CONCLUSION: Constitutively active I(Q1E1) and a smaller peak I(Q1E1) are common
features of FAF-associated and LQT1-associated mutations, respectively. These
data suggest that the mixed functional properties of R231C-Q1 may predispose
some families to LQT1 or FAF. We conclude that R231C is a pleiotropic missense
mutation capable of LQT1 expression, AF expression, or both. This report describes a three-generation family with a severe phenotype of
long-QT syndrome-1 (LQTS-1) caused by a single nucleotide mutation in the
KQT-like, voltage-gated potassium channel-1 gene (KCNQ1; MIM 607542). Two
members of the family died suddenly in their childhood, and all eight surviving
members with prolonged QT have a heterozygous missense mutation resulting in a
glycine-to-glutamate amino acid substitution at position 316 of the potassium
channel. In this family, the newly reported mutation, guanine-to-adenosine at
position 947 in the KCNQ1 gene, exhibits a domit trait of LQTS with complete
penetrance, in contrast to the relatively reduced clinical penetrance found in
most LQTS cases. The Department of Pediatric Cardiology, Medical University of Silesia in
Katowice-Ligota, studied 24 patients with clinically diagnosed (using ECG)
long-QT syndrome (LQTS) in 18 cases. Nine patients were diagnosed with LQT1 and
nine with LQT2. The other six individuals were healthy, with no symptoms
characteristic for prolonged QT syndrome, but came from families with confirmed
disease occurrence. The study was conducted on members of four families. In
order to search for mutations (using mSSCP and sequencing), genomic DNA was
obtained from patients to determine the expression levels of the genes KCNQ1 and
KCNH2 (HERG), involved in the occurrence of clinical signs of disease. Total RNA
was extracted from peripheral blood. Consent to the use of blood samples of
patients had been given by the Bioethics Commission of the Medical University of
Silesia. mSSCP analysis and sequencing did not confirm the occurrence of
mutations in KCNQ1 and HERG associated with the occurrence of LQTS. Analysis of
gene expression profile of KCNQ1 and HERG confirmed the presence of disease in
people with a known clinical diagnosis. Overexpression, as well as reduced
expression, was observed for the examined genes. KCNQ1 was inhibited in two
families, whereas HERG was reduced in one and overexpressed in the other. Gene
expression profile analysis showed abnormal expressions of KCNQ1 and HERG in
healthy subjects, which may be a sign of predisposition to develop the disease.
The novelty of our study involved the use of total mRNA isolated from human
peripheral blood, and the very limited evidence in the literature to date
regarding the assessment of gene expression profile of HERG and KCNQ1 in
relation to the presence of prolonged QT syndrome. Long QT syndrome (LQTS) 1 is the most common type of inherited LQTS and is
linked to mutations in the KCNQ1 gene. We identified a KCNQ1 missense mutation,
KCNQ1 G325R, in an asymptomatic patient presenting with significant QT
prolongation (QTc, 448-600ms). Prior clinical reports revealed phenotypic
variability ranging from the absence of symptoms to syncope among KCNQ1 G325R
mutation carriers. The present study was designed to determine the G325R ion
channel phenotype and its association with the clinical LQTS presentation.
Electrophysiological testing was performed using the Xenopus oocyte expression
system. KCNQ1 G325R channels were non-functional and suppressed wild type (WT)
currents by 71.1%. In the presence of the native cardiac regulatory ß-subunit,
KCNE1, currents conducted by G325R and WT KCNQ1 were reduced by 52.9%.
Co-expression of G325R and WT KCNQ1 with KCNE1 shifted the voltage-dependence of
I(Ks) activation by 12.0mV, indicating co-assembly of mutant and WT subunits.
The dysfunctional biophysical phenotype validates the pathogenicity of the KCNQ1
G325R mutation and corresponds well with the severe clinical presentation
revealed in some reports. However, the index patient and other mutation carriers
were asymptomatic, highlighting potential limitations of risk assessment schemes
based on ion channel data. |
Does melanoma occur in people of African origin ? | Yes. Africans with dark skin have a reduced risk of getting all types of skin cancer as compared with Caucasians. The incidence of malignant melanoma in Johannesburg Black was 1,2 per 100 000 and accounted for 2% of all cancers. The largest number of cases occurred in the 50- 70-year age group and there was a female preponderance. As in previous studies, the sites predominantly affected were the foot and the hand, mainly on the plantar and palmar surfaces. | The incidences of maligt melanoma recorded by 59 population-based cancer
registries were investigated to determine the effects of racial and skin-colour
differences. White populations exhibited a wide range of melanoma incidences and
females commonly, though not invariably, had a higher incidence than males.
Non-white populations experienced in general a much lower incidence of melanoma
although there was some overlap of white and non-white rates. No predomit sex
difference emerged among non-whites. Populations of African descent were found
to have a higher incidence than those of Asiatic origin, but it was concluded
that this was due largely to the high frequency of tumours among Africans on the
sole of the foot. A clear negative correlation between degree of skin
pigmentation and melanoma incidence emerged for the exposed body sites. These
data provide strong support for the hypotheses that UV radiation is a major
cause of maligt melanoma and that melanin pigmentation protects against it.
Further research is required to elucidate the aetiology of melanoma of the sole
of the foot. Hutchinson's melanotic freckle (lentigo maligna) is a well-known pigmented
lesion, usually seen on the face of white patients. It may be associated with
invasive maligt melanoma. This paper reports the incidence of this lesion in
association with invasive maligt melanomas of the feet and hands of Black
Africans. In Blacks, as in Whites, maligt melanoma with adjacent Hutchinson's
melanotic freckle carries a considerably better prognosis than other
histogenetic patterns of maligt melanoma. Maligt melanoma of the skin in Blacks in formidable and sinister tumour. This
study is concerned with the epidemiology of maligt melanoma, as seen in both
urban and rural Black Africans. A smaller series in which follow-up on the
patients was available is included. To our knowledge, this is the first study of
its kind in which follow-up, and hence survival figures, can be quoted. Although
the numbers are relatively small, they provide a valuable indication of the
behaviour of melanomas in this group. The difficulties of follow-up cannot be
overemphasised, and follow-up on 79 cases out of 100 could be obtained only by
the employment of an able and enthusiastic Black social worker for 3 years. The
first recorded survival figures in a Black population show a 3-year survival
rate of only 28,4%. Prognosis is related to the size and extent of the tumour
with larger and more widespread tumours faring worse than others. The incidence
of maligt melanoma in Johannesburg Black was 1,2 per 100 000 and accounted
for 2% of all cancers. The largest number of cases occurred in the 50- 70-year
age group and there was a female preponderance. As in previous studies, the
sites predomitly affected were the foot and the hand, mainly on the plantar
and palmar surfaces. Follow-up data (over a 3-year period) and the histological appearances of
primary lesion were studied and related in 40 Black patients with maligt
melanoma. This to our knowledge is the first study in Black African patients. It
was found that they present with large deeply invasive lesions, particularly on
the foot. The prognosis is poor, with an over-all 3-year survival rate of 35%.
The histological features used to assess the prognosis of maligt melanoma in
Whites, that is histogenetic pattern, size and shape of the lesion, level of
invasion, presence of ulceration and mitotic activity would seem to be equally
applicable in Black patients. In addition, marked cellular pleomorphism,
haemorrhage, necrosis and fibrosis within the tumour are bad signs. In this
series lymphocytic infiltration, either within the tumour or at the edge,
possibly indicative of an immune response, seemed to be of favourable prognostic
import. Surprisingly, a lesion histologica-ly that of lentigo maligna melanoma
was found on the feer of some blacks and could be related to much more
favourable survival figures. Skin cancers, although uncommon, do occur in black Africans. Available
literature on this subject from black African populations is scant, suggesting
diminished interest. Eighteen cases of maligt skin tumors seen at the
University of Port Harcourt Teaching Hospital over 3 years (1984 to 1987) were
analyzed for diagnoses, site of tumors, sex, and age. Seven patients (39%) had
maligt melanomas affecting only the soles of the feet, while the same number
had squamous cell carcinomas widely distributed in various parts of the body.
Basal cell carcinomas were found in four (22%) patients with face lesions. Only
three albinos were in the series, and all three had squamous cell carcinomas.
Melanin protection against sun-induced skin cancers gives a false sense of
well-being. The need for renewed interest of the subject is emphasized. A case of leptomeningeal melanoma in an African child of 7 years is presented
together with a survey of pigmentation in the normal African brain. There is a
direct relationship between the depth of pigment of the leptomeninges and the
skin in Ugandan Africans, suggesting that similar factors operate in the control
of melanocytes in these two sites. BACKGROUND: Scant data exists on melanoma in blacks from Africa. This study was
undertaken to define factors affecting outcome of blacks from South Africa with
melanoma.
STUDY DESIGN: A retrospective analysis of the management and outcome of 63 black
patients with maligt melanoma treated at a major referral center during a 14
year period is presented. Data evaluated included patient demographic and
clinical characteristics, stage at presentation, tumor site, histologic type,
treatment, and subsequent cure. Survival curves were calculated for stage and
site of disease.
RESULT: The mean age at presentation of the 39 women and 24 men was 60.5 years
(range of 30 to 85 years), with a peak incidence in the sixth decade. The foot
was the most common site of disease (45 patients). Seven patients had subungual
melanoma, seven had primary mucosal lesions, and in six, the primary lesion
could not be found. Thirty patients presented with stage I disease, two with
stage II, 23 with stage III, and nine with disseminated metastatic disease.
Acral lentiginous melanoma was the most common histogenetic type (34 patients),
nodular melanoma occurred in ten patients, and superficial spreading melanoma
occurred in three patients. The mean Breslow depth was 6.15 mm (range of 1 to 25
mm). Patients with localized disease were treated by wide local excision and
split skin graft, while patients with melanoma in the nailbed were treated by
amputation of the involved digit. Sixteen patients are alive after a mean
follow-up period of 82.1 months, 44 have died after a mean of 12.7 months, and
five patients have been unavailable for follow-up evaluation.
CONCLUSIONS: The poor prognosis in black patients in South Africa is the result
of delayed presentation with thick primary lesions and advanced disease. An
active education program may reduce mortality by detecting the disease earlier. A review of 775 normally pigmented Africans and 18 African albinos with
maligt skin tumours showed that squamous cell carcinoma was the most common
tumour type, in contrast to Caucasians, in whom basal cell carcinoma is most
frequent. In African albinos squamous cell carcinoma of the head and neck region
was most frequent. However, the proportion of basal cell carcinomas was low also
among albinos but higher than among normally pigmented patients. In contrast to
the normally pigmented patients, there were no squamous cell carcinomas on the
limbs in albino patients. We suggest that this difference was due to
environmental factors, such as chronic leg ulcers, which might have been less
influential in the albinos, who seldom lived more than 30 years. No cases of
cutaneous melanoma or Kaposi sarcoma were found in the albino group. The outcome of treatment in 40 black patients (27 women, 13 men; mean age 62.9
years) with plantar melanoma over a 13-year period was analysed to evaluate the
efficacy of wide local excision with split skin grafting. Substantial delay in
seeking medical attention occurred in 35 patients. At presentation, 20 patients
had stage I disease, one stage II, 15 stage III and four stage IV. Acral
lentiginous melanoma (27 patients) was the most common histological type. The
mean Breslow depth was 6.9 mm and 35 patients had lesions of Clark level IV or
V. The mean surface area or plantar lesions was 13.3 cm2. Wide local excision
with split skin grafting was used in 29 patients; four patients with neglected
advanced plantar lesions had below-knee amputation and seven with metastatic
disease did not undergo surgery. Graft sepsis occurred in six patients and local
recurrence in two. Nine patients were alive at follow-up; the 5-year survival
rate was 25 per cent. Delay in presentation and locally advanced disease may
explain the poor prognosis of plantar melanoma in black South Africans. Maligt melanomas in black Africans are predomitly located on the lower
extremities. Since their biological features have not been well focused, we
studied 28 such cases with special reference to proliferative activity (Ki-67
expression), p16 and p53 staining, as well as microvessel density, all known to
be involved in the progression of melanomas among whites. The findings were
related to clinico-pathological characteristics. The tumours had a median
thickness of 6.4 mm, ulceration was present in 71%, and vascular invasion in
36%, indicating the presence of advanced and aggressive melanomas. Further, loss
of p16 protein expression was found in 50%, and high proliferative activity was
present (median 41%). In contrast, strong p53 staining was rare (11%), although
most tumours showed low-level positivity. Angiogenesis, as estimated by
microvessel density, was significantly associated with vascular invasion (p =
0.022), supporting its role in the progression of these tumours. Thus, our
findings indicate that melanomas located on the lower extremities in black
Africans show several features of aggressiveness; in particular, the
proliferative activity was high, and p16 alterations was frequent as evidenced
by loss of protein staining. Our findings also indicated that the diagnosis is
delayed among black Africans. Little is known about the behaviour of melanoma in patients of mixed ancestry. A
retrospective analysis of 844 consecutive patients presenting with melanoma over
a 12-year period was performed. Forty patients (4.8%) were of mixed ancestry.
The data evaluated included patient age, gender, delay in presentation,
presenting stage, anatomical distribution, histology, management and outcome.
The mean age at presentation was 52.8 years. Twenty-seven patients were female.
The mean delay in presentation was 1.54 years. Seventy per cent of melanomas
were confined to the extremities, of which one-third were plantar in origin. The
most common histological variant, affecting 13 patients (32.5%), was acral
lentiginous melanoma; 12.5% of patients presented with in situ (Stage 0)
disease, 17.5% with Stage I disease, 22.5% with Stage II disease, 27.5% with
Stage III disease and 7.5% with Stage IV disease. Twenty-seven patients (67.5%)
remained alive at the end of the study after a median follow-up of 5.58 years,
whilst 11 (27.5%) died after a median of 2.42 years. The median survival was
3.92 years. Although the histological type and anatomical distribution reflect
the disease pattern of black populations, the overall 5-year survival of 74% is
similar to that seen in white populations. An education programme is needed to
improve melanoma awareness in mixed race populations. Maligt melanoma (MM) remains a pediatric rarity world-wide, but perhaps more
so in black Africans. To the best of our knowledge, the current report of MM in
a two-and-a-half-year-old Nigerian who had a pre-existing congenital giant hairy
nevus is probably the first (in an accessible literature) in a black African
child. Primary neoplastic transformation and metastatic spread were suggested by
the appearance of multiple swellings over the "garment" precursor nevus at the
posterior trunk, multiple ipsilateral axillary nodal enlargement, and fresh
occipital swellings postadmission. Smaller-sized hyperpigmented lesions with
irregular, nonlobulated, and frequently hairy surfaces were also discernible
over the upper and lower extremities, but the face, anterior trunk, and mucosal
surfaces were relatively spared. A diagnosis of MM was confirmed by the
subsequent histopathologic findings from the fine-needle aspirate and biopsy
specimens. Chemotherapy was initiated but was truncated shortly after by
parent-pressured discharge. Despite the rarity of MM in a tropical African
setting where management options are few, the current case underscores the need
for a high clinical index of diagnostic suspicion, an early pursuit of
investigative confirmation, and prophylactic excision in children with the
predisposing skin lesions, like congenital giant hairy nevus. An expounded
discourse of the possible precursors and management options of MM is provided.
We emphasize the need for institutional cost subsidy for anticancer care in
tropical children. Earlier studies have shown frequent mutations in the BRAF and NRAS genes in
cutaneous melanoma, but these alterations have not been examined in the rare
category of melanoma from black Africans. Moreover, the frequency of epidermal
growth factor receptor (EGFR) mutations in melanocytic tumors is not known. We
therefore examined 165 benign and maligt melanocytic lesions (including 118
invasive melanomas and 18 metastases collected as consecutive cases from various
time periods and from two different pathology departments; the 51 nodular
melanomas were randomly selected from a larger, consecutive, population-based
series of nodular melanomas) with respect to alterations in the EGFR, BRAF and
NRAS genes. Mutations in EGFR (exons 18-21) were not detected. EGFR protein
expression was observed in a subgroup of melanomas, but without associations
with clinicopathologic phenotype or prognosis. Cytoplasmic EGFR expression was,
however, significantly increased from benign nevi to melanomas. Mutations in
BRAF and NRAS were detected in superficial melanoma (25 and 29%, respectively),
nodular melanoma (29 and 28%, respectively) and lentigo maligna melanoma (15 and
16%, respectively). In a series of melanomas from black Africans (n=26), only
two BRAF mutations (8%) were found, both being different from the common T1799A
substitution. Moreover, melanomas from black Africans exhibited mutations in
NRAS exon 1 only (12%), whereas NRAS exon 2 mutations were predomit in
melanomas from Caucasians. Thus, the frequencies of BRAF and NRAS mutations were
particularly low in melanomas from black Africans, supporting a different
pathogenesis of these tumors. Globally, cutaneous cancers are among the most common form of cancer. Among
Africans, there are significant differences in the types of skin cancer compared
to those documented in patients from other countries. We evaluated all the
patients with a histological diagnosis of skin cancer presenting to the
University of Calabar Teaching Hospital from January 2005 through December 2006.
Twenty-nine patients (18 males and 11 females) with skin cancer were identified
and these accounted for 8.0 percent of total maligcies. Their ages ranged
from 16 to 70 years (mean 43.5 years). Kaposi sarcoma (KS) was the most common
skin cancer. Kaposi sarcoma associated with HIV represented 81.8 percent of KS
cases found. Squamous cell carcinoma (SCC) ranked second and maligt melanoma
third. Of the skin cancers in our series, the most common site was the lower
limb (55.2%), followed by the head and neck (24%). The 4 albinos accounted for
13.8 percent of the skin cancers found. Immunosuppression (KS), chronic ulcer,
inflammation, albinism, and solar radiation were identified risk factors. Public
education strategies on prevention, with an emphasis on early identification and
surgical treatment of skin cancers are urged. In addition, treatment of and
close observation of chronic ulcers are recommended. BACKGROUND: Albinism is an established risk factor for skin cancer in black
Africans, and high levels of ultraviolet radiation increase the risk of the
three major forms of skin cancer.
METHODS: We present four albinos with histologic diagnoses of skin cancer who
were seen at the University of Calabar Teaching Hospital, Calabar, Nigeria from
January 2005 to December 2006. Skin cancer in these cases was compared with the
total skin cancer affecting 29 patients during the study period.
RESULTS: Twenty-nine patients presented with skin cancer during the study
period. Four Nigerian albinos (two men and two women) with skin cancer accounted
for 13.8% of the skin cancers observed during the 2-year period. They ranged in
age from 22 to 40 years (mean, 27.8 years). The sites of the lesions included
the head [squamous cell carcinoma (SCC) in two patients and basal cell carcinoma
(BCC) in one patient] and the upper limb (melanoma). All tumors were excised; in
addition, patients with SCC and melanoma received adjuvant chemotherapy. Two
patients, one woman with SCC and the patient with melanoma, showed residual
tumor because of inadequate excision. During the evaluation period between 14
and 18 months, the sites appeared to be healed with no evidence of recurrence in
the male with SCC and female with BCC.
CONCLUSION: Albinism and solar radiation are risk factors for skin cancer. Early
implementation of public education strategies on prevention should improve
outcome. |
What is the effect of resveratrol on mTOR activity? | Resveratrol (RSV) inhibits leucine-stimulated mTORC1 activation by promoting mTOR/DEPTOR. | Here we demonstrated that, at cytostatic, near-toxic concentrations, resveratrol
inhibited S6 phosphorylation and prevented the senescence morphology in human
cells. Using a sensitive functional assay, we found that resveratrol partially
prevented loss of the proliferative potential associated with cellular
senescence. Resveratrol was less effective than rapamycin, because
aging-suppression by resveratrol was limited by its toxicity at high
concentrations. We discuss whether concentrations of resveratrol that inhibit
mTOR (target of rapamycin) and suppress cellular senescence are clinically
achievable and whether partial inhibition of mTOR by resveratrol might be
sufficient to affect organismal aging. Resveratrol (trans-3,4', 5-trihydroxystilbene) is a naturally occurring
polyphenolic compound that has antiinflammatory, antioxidant, neuroprotective
properties and acts as a chemopreventive agent. Resveratrol causes cell cycle
arrest and induces apoptotic cell death in various types of cancer cells. In the
current studies, the effect of resveratrol on phosphoinositide kinase-3
(PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling
pathway was examined in human U251 glioma cells. Resveratrol decreased both the
expression and phosphorylation of Akt. Inhibitors of PI3K (LY294002) and Akt
(SH-6) enhanced resveratrol-induced LDH release and caspase-3 activation.
Resveratrol reduced phosphorylation of ribosomal protein S6 and the mTOR
inhibitor rapamycin further enhanced resveratrol-induced cell death. These
results suggest that the downregulation of PI3K/Akt/mTOR signaling pathways may
be an important mediator in resveratrol-induced apoptosis in glioma cells. Resveratrol (RSV) is a naturally occurring polyphenol that has been found to
exert antioxidant, anti-inflammatory, and neuroprotective properties. However,
how RSV exerts its beneficial health effects remains largely unknown. Here, we
show that RSV inhibits insulin- and leucine-stimulated mTOR signaling in C2C12
fibroblasts via a Sirt1-independent mechanism. Treating C2C12 cells with RSV
dramatically inhibited insulin-stimulated Akt, S6 kinase, and 4E-BP1
phosphorylation but had little effect on tyrosine phosphorylation of the insulin
receptor and activation of the p44/42 MAPK signaling pathway. RSV treatment also
partially blocked mTOR and S6 kinase phosphorylation in TSC1/2-deficient mouse
embryonic fibroblasts, suggesting the presence of an inhibitory site downstream
of TSC1/2. Knocking out PDK1 or suppressing AMP-activated protein kinase had
little effect on leucine-stimulated mTOR signaling. On the other hand, RSV
significantly increased the association between mTOR and its inhibitor, DEPTOR.
Furthermore, the inhibitory effect of RSV on leucine-stimulated mTOR signaling
was greatly reduced in cells in which the expression levels of DEPTOR were
suppressed by RNAi. Taken together, our studies reveal that RSV inhibits
leucine-stimulated mTORC1 activation by promoting mTOR/DEPTOR interaction and
thus uncover a novel mechanism by which RSV negatively regulates mTOR activity. The anti-tumor activity of rapamycin is compromised by the
feedback-loop-relevant hyperactive PI3K and ERK-MAPK pathway signaling. In
breast cancer cells treated with rapamycin, we observed a moderate increase of
AKT phosphorylation (P-AKT) in a rapamycin resistant cell line, MDA-MB-231, as
well as a slight increase of P-AKT in a rapamycin sensitive cell line, MCF-7. We
found that resveratrol, a natural phytoalexin, suppressed the phosphorylation
and activation of the PI3K/AKT pathway in all the three breast cancer cell lines
that we tested. It also had a weak inhibitory effect on the activation of the
mTOR/p70S6K pathway in two cell lines expressing wildtype PTEN, MCF-7 and
MDA-MB-231. The combined use of resveratrol and rapamycin resulted in modest
additive inhibitory effects on the growth of breast cancer cells, mainly through
suppressing rapamycin-induced AKT activation. We, therefore, reveal a novel
combination whereby resveratrol potentiates the growth inhibitory effect of
rapamycin, with the added benefit of preventing eventual resistance to
rapamycin, likely by suppressing AKT signaling. We also present data herein that
PTEN is an important contributor to resveratrol's growth suppressive effects and
its potentiation of rapamycin in this therapeutic scenario, as resveratrol's
suppression of rapamycin-mediated induction of P-AKT is both PTEN-dependent and
-independent. Thus, the resveratrol-rapamycin combination may have therapeutic
value in treating breast cancer and perhaps other processes where mTOR is
activated. BACKGROUND: Resveratrol, a naturally occurring phytopolyphenol compound, has
attracted extensive interest in recent years because of its diverse
pharmacological characteristics. Although resveratrol possesses chemopreventive
properties against several cancers, the molecular mechanisms by which it
inhibits cell growth and induces apoptosis have not been clearly understood. The
present study was carried out to examine whether PI3K/AKT/FOXO pathway mediates
the biological effects of resveratrol.
METHODOLOGY/PRINCIPAL FINDINGS: Resveratrol inhibited the phosphorylation of
PI3K, AKT and mTOR. Resveratrol, PI3K inhibitors (LY294002 and Wortmannin) and
AKT inhibitor alone slightly induced apoptosis in LNCaP cells. These inhibitors
further enhanced the apoptosis-inducing potential of resveratrol. Overexpression
of wild-type PTEN slightly induced apoptosis. Wild type PTEN and PTEN-G129E
enhanced resveratrol-induced apoptosis, whereas PTEN-G129R had no effect on
proapoptotic effects of resveratrol. Furthermore, apoptosis-inducing potential
of resveratrol was enhanced by domit negative AKT, and inhibited by wild-type
AKT and constitutively active AKT. Resveratrol has no effect on the expression
of FKHR, FKHRL1 and AFX genes. The inhibition of FOXO phosphorylation by
resveratrol resulted in its nuclear translocation, DNA binding and
transcriptional activity. The inhibition of PI3K/AKT pathway induced FOXO
transcriptional activity resulting in induction of Bim, TRAIL, p27/KIP1, DR4 and
DR5, and inhibition of cyclin D1. Similarly, resveratrol-induced FOXO
transcriptional activity was further enhanced when activation of PI3K/AKT
pathway was blocked. Over-expression of phosphorylation deficient mutants of
FOXO proteins (FOXO1-TM, FOXO3A-TM and FOXO4-TM) induced FOXO transcriptional
activity, which was further enhanced by resveratrol. Inhibition of FOXO
transcription factors by shRNA blocked resveratrol-induced upregulation of Bim,
TRAIL, DR4, DR5, p27/KIP1 and apoptosis, and inhibition of cyclin D1 by
resveratrol.
CONCLUSION/SIGNIFICANCE: These data suggest that FOXO transcription factors
mediate anti-proliferative and pro-apoptotic effects of resveratrol, in part due
to activation of extrinsic apoptosis pathway. Resveratrol (RSV, trans-3,4,5-Trihydroxystilbene), a type of polyphenol
originally found in red wines, shows a great promise for the treatment of
cancer, aging, type 2 diabetes and cardiovascular diseases. Recent studies
suggest that suppressing the signaling pathway mediated by mTOR, a well-known
energy sensor that integrates various hormonal, nutrient and environmental
signals to regulate cell growth, metabolism and survival, could play an
important role in mediating the beneficial effect of RSV. The underlying
mechanisms by which RSV inhibits mTOR signaling remain elusive, but our recent
studies show that RSV inhibits amino acid-stimulated mTOR signaling in C2C12
fibroblasts via a Sirt1- and AMPK-independent mechanism. RSV treatment has no
effect on the expression levels of mTOR, raptor and DEPTOR, but greatly promotes
the interaction between mTOR and its inhibitor DEPTOR. Our results reveal a
novel mechanism by which RSV inhibits mTOR signaling and its function. BACKGROUND: Prostate cancer (PrCa) displays resistance to radiotherapy (RT) and
requires radiotherapy dose escalation which is associated with greater toxicity.
This highlights a need to develop radiation sensitizers to improve the efficacy
of RT in PrCa. Ionizing radiation (IR) stimulates pathways of IR-resistance and
survival mediated by the protein kinase Akt but it also activates the metabolic
energy sensor and tumor suppressor AMP-Activated Protein Kinase (AMPK). Here, we
examined the effects of the polyphenol resveratrol (RSV) on the IR-induced
inhibition of cell survival, modulation of cell cycle and molecular responses in
PrCa cells.
METHODS: Androgen-insensitive (PC3), sensitive (22RV1) PrCa and PNT1A normal
prostate epithelial cells were treated with RSV alone (2.5-10 μM) or in
combination with IR (2-8 Gy). Clonogenic assays, cell cycle analysis, microscopy
and immunoblotting were performed to assess survival, cell cycle progression and
molecular responses.
RESULTS: RSV (2.5-5 μM) inhibited clonogenic survival of PC3 and 22RV1 cells but
not of normal prostate PNT1A cells. RSV specifically sensitized PrCa cells to
IR, induced cell cycle arrest at G1-S phase and enhanced IR-induced nuclear
aberrations and apoptosis. RSV enhanced IR-induced expression of DNA damage
(γH2Ax) and apoptosis (cleaved-caspase 3) markers as well as of the cell cycle
regulators p53, p21(cip1) and p27(kip1). RSV enhanced IR-activation of ATM and
AMPK but inhibited basal and IR-induced phosphorylation of Akt.
CONCLUSIONS: Our results suggest that RSV arrests cell cycle, promotes apoptosis
and sensitizes PrCa cells to IR likely through a desirable dual action to
activate the ATM-AMPK-p53-p21(cip1)/p27(kip1) and inhibit the Akt signalling
pathways. Resveratrol is a plant-derived polyphenol that extends lifespan and healthspan
in model organism. Despite extensive investigation, the biological processes
mediating resveratrol's effects have yet to be elucidated. Because repression of
translation shares many of resveratrol's beneficial effects, we hypothesized
that resveratrol was a modulator of protein synthesis. We studied the effect of
the drug on the H4-II-E rat hepatoma cell line. Initial studies showed that
resveratrol inhibited global protein synthesis. Given the role of the mammalian
Target of Rapamycin (mTOR) in regulating protein synthesis, we examined the
effect of resveratrol on mTOR signaling. Resveratrol inhibited mTOR
self-phosphorylation and the phosphorylation of mTOR targets S6K1 and eIF4E-BP1.
It attenuated the formation of the translation initiation complex eIF4F and
increased the phosphorylation of eIF2α. The latter event, also a mechanism for
translation inhibition, was not recapitulated by mTOR inhibitors. The effects on
mTOR signaling were independent of effects on AMP-activated kinase or AKT. We
conclude that resveratrol is an inhibitor of global protein synthesis, and that
this effect is mediated through modulation of mTOR-dependent and independent
signaling. Resveratrol is indicated to be involved in neuroprotection and anti-inflammation
in epileptic rats. The molecular mechanism is still not fully understood. In
this study, we investigated the role of resveratrol in nuclear factor-kappa B
associated inflammatory responses induced by status epilepticus. Our data showed
that seizures activated mammalian target of rapamycin (mTOR), increased the
activity of nuclear factor-kappa B and promoted the expressions of inflammatory
molecules including inducible nitric oxide synthase, cyclooxygenase-2 and
interleukin-1β. Futhermore, resveratrol significantly inhibited the activation
of nuclear factor-kappa B and the production of proinflammatory molecules via
mTOR pathway. Additionally, we also proved that the inhibition of mTOR signal by
resveratrol was mostly attributed to AMP-activated kinase (AMPK) activation.
Altogether, our results suggest that resveratrol suppresses inflammatory
responses induced by seizures partially via AMPK/mTOR pathway. SIRT1 (mammalian ortholog of the yeast silent information regulator 2) is a
NAD-dependent histone deacetylase belonging to the multigene family of sirtuins.
Anecdotal and epidemiologic observations provide evidence for beneficial effects
of the calorie restriction mimetic resveratrol (RES), a SIRT1 activator in
preventing cardiovascular diseases and cancer. Although SIRT1 possesses both
tumorigenic and antitumorigenic potential, the molecular mechanisms underlying
SIRT1-mediated tumor progression or inhibition are poorly understood. In this
study, we investigated the role of SIRT1 in multiple human prostate cancer cell
lines and prostate-specific PTEN knockout mouse model using resveratrol.
Androgen-independent prostate cancer cell lines (C42B, PC3, and DU145) express
higher levels of SIRT1 than androgen-responsive (LNCaP) and nontumorigenic
prostate cells (RWPE-1). Resveratrol enhanced this expression without any
significant effect on SIRT1 enzymatic activity. Inhibition of SIRT1 expression
using shRNA enhanced cell proliferation and inhibited autophagy by repressing
phosphorylation of S6K and 4E-BP1. These biologic correlates were reversed in
the presence of resveratrol. Analysis of prostates from dietary intervention
with resveratrol showed a significant reduction in prostate weight and reduction
in the incidence of high-grade prostatic intraepithelial neoplastic (HGPIN)
lesions by approximately 54% with no significant change in body weight.
Consistent with the in vitro findings, resveratrol intervention in the PTEN
knockout mouse model was associated with reduction in the prostatic levels of
mTOR complex 1 (mTORC1) activity and increased expression of SIRT1. These data
suggest that SIRT1/S6K-mediated inhibition of autophagy drives prostate
tumorigenesis. Therefore, modulation of SIRT1/S6K signaling represents an
effective strategy for prostate cancer prevention. Resveratrol (3,4',5-trihydroxystilbene; RSV), a natural polyphenol found in a
variety of daily food including grapes and red wine, has long been suspected to
have multifaceted health beneficial properties, including anti-inflammation,
anti-oxidant, and anticancer activities. Over the past few years, numerous
studies have suggested that suppressing the activity of mammalian target of
rapamycin (mTOR), a critical regulator of cell metabolism, growth, and
proliferation, may provide a key mechanism underlying the anticarcinogenic
properties of resveratrol. It has been found that resveratrol targets multiple
components of the phosphatidylinositol 3- kinase(PI3K)/Akt and mTOR signaling
pathways, including PI3K, Akt, PTEN, and DEPTOR, suggesting that this natural
compound and its derivatives may offer a promising new cancer treatment. In the
current review, we discuss recent findings on the molecular mechanisms
regulating mTOR signaling and the therapeutic potential of resveratrol for
cancer treatment by targeting mTOR. Resveratrol has many biological effects, including anti-tumor, antiviral
activities, and vascular protection. Recent studies have suggested that
resveratrol exert its antitumor effects through induction of autophagy by an
unknown mechanism. In this study, we investigated the involvement of autophagy
in resveratrol-induced cell death and its potential molecular mechanisms in A549
human lung adnocarcinoma cells. Resveratrol-induced growth inhibition and cell
death was assessed by MTT and clonogenic assays. Activation of autophagy was
characterized by monodansylcadaverine, transmission electron microscopy, and
expression of autophagy marker protein LC3. Western blot analysis was used to
study the cell signals involved in the mechanisms of autophagic death.
Intracellular free calcium was detected with Fura2-AM staining. Our results
indicated that resveratrol induced A549 cell death was mediated by autophagy.
3-methyladenine, an inhibitor of autophagy, suppressed resveratrol-induced
autophagic cell death, and knockdown of autophagy-related genes Atg5 and
Beclin-1 with siRNAs reversed RSV-induced cell death. Intracellular free calcium
accumulated immediately following resveratrol addition, which led to the
activation of phospho-AMPK and phospho-Raptor, and a reduction in the amount of
phospho-p70S6K. These effects could be reversed by the AMPK inhibitor compound
C, and the calcium ion-chelating agent EGTA. In conclusion, we demonstrate that
resveratrol-induced A549 cell death was mediated by the process of autophagic
cell death via Ca(2+)/AMPK-mTOR signaling pathway. Resveratrol (RSV) is a natural polyphenol produced by plants and is proposed to
have multiple beneficial effects on health. In recent years, the interest in
this molecule has increased nearly exponentially following the major findings
that RSV (I) is chemo-preventive in some cancer models, (II) is
cardio-protective and (III) has positive effects on metabolism in mammals and
increases lifespan in lower organisms. Mechanistic target of rapamycin (mTOR) is
a central controller of cell growth, proliferation, metabolism and angiogenesis.
As a part of the mTORC1 and mTORC2 complexes, the mTOR kinase plays a key role
in several pathways involved in cancer and metabolic diseases. Recent studies
suggest that modulation of the mTOR signalling pathway could play an important
role in mediating the beneficial effects of RSV. Therefore, this review
summarises the current findings regarding RSV and its inhibition/activation of
the proteins in the mTOR pathway, and thereby propose the proteins of the mTOR
cascade to be primary targets for RSV. RSV affects many different targets
related to mTOR, and it is not clear which is most relevant. However, most
frequently, RSV is found to inhibit the activity of the mTOR pathway proteins,
and to activate AMPK and LKB1, which can suppress mTOR signalling. Thus, it
appears that RSV plays a role in modulation of proteins of the mTOR pathway
although more research is still needed to fully understand the interaction. In breast cancer cells, overexpression of human epidermal growth factor receptor
2 (HER2) increases the translation of fatty acid synthase (FASN) by altering the
activity of PI3K/Akt signaling pathways. Cancer chemotherapy causes major side
effects and is not effective enough in slowing down the progression of the
disease. Earlier studies showed a role for resveratrol in the inhibition of
FASN, but the molecular mechanisms of resveratrol-induced inhibition are not
known. In the present study, we examined the novel mechanism of resveratrol on
Her2-overexpressed breast cancer cells. The effect of resveratrol on the growth
of breast cancer cells was assessed as percent cell viability by
cytotoxicity-based MTT assay and the induction of apoptosis was determined by
cell-death detection ELISA and flow cytometric analysis of Annexin-V-PI binding.
Western immunobloting was used to detect signaling events in human breast cancer
(SKBR-3) cells. Data showed that resveratrol-mediated down-regulation of FASN
and HER2 genes synergistically induced apoptotic death in SKBR-3 cells. This
concurrently caused a prominent up-regulation of PEA3, leads to down-regulation
of HER2 genes. Resveratrol also alleviated the PI3K/Akt/mTOR signaling by
down-regulation of Akt phosphorylation and up-regulation of PTEN expression.
These findings suggest that resveratrol alters the cell cycle progression and
induce cell death via FASN inhibition in HER2 positive breast cancer. |
Are people with blood group O protected against severe Malaria? | It appears that individuals who are of blood-group O are relatively resistant to the severe disease caused by P. falciparum infection. | Although the ABO blood group of the human host has been reported to influence
malarial infection, there have been few clinical observations on this effect. A
hospital-based, comparative study was therefore performed to investigate the
relationship between blood-group type and severe disease i nPlasmodium
falciparum malaria. Overall, 243 cases of malaria (163 uncomplicated and 80
severe) and 65 patients with severe, non-malarial infections were studied. In
terms of ABO-blood-group composition, the patients with severe malaria were
significantly different from the patients with the uncomplicated disease
(P<0.001) and also from a population control described previously (P<0.0001).
The patients with uncomplicated malaria or severe but non-malarial disease were,
however, similar to the population control. The cases of severe malaria were
significantly less likely to be of blood group O (P=0.0003), and significantly
more likely to be of group AB (P<0.0001), than the patients with nonsevere
malaria. It appears that individuals who are of blood-group O are relatively
resistant to the severe disease caused by P. falciparum infection. Malaria has been a major selective force on the human population, and several
erythrocyte polymorphisms have evolved that confer resistance to severe malaria.
Plasmodium falciparum rosetting, a parasite virulence phenotype associated with
severe malaria, is reduced in blood group O erythrocytes compared with groups A,
B, and AB, but the contribution of the ABO blood group system to protection
against severe malaria has received little attention. We hypothesized that blood
group O may confer resistance to severe falciparum malaria through the mechanism
of reduced rosetting. In a matched case-control study of 567 Malian children, we
found that group O was present in only 21% of severe malaria cases compared with
44-45% of uncomplicated malaria controls and healthy controls. Group O was
associated with a 66% reduction in the odds of developing severe malaria
compared with the non-O blood groups (odds ratio 0.34, 95% confidence interval
0.19-0.61, P < 0.0005, severe cases versus uncomplicated malaria controls). In
the same sample set, P. falciparum rosetting was reduced in parasite isolates
from group O children compared with isolates from the non-O blood groups (P =
0.003, Kruskal-Wallis test). Statistical analysis indicated a significant
interaction between host ABO blood group and parasite rosette frequency that
supports the hypothesis that the protective effect of group O operates through
the mechanism of reduced P. falciparum rosetting. This work provides insights
into malaria pathogenesis and suggests that the selective pressure imposed by
malaria may contribute to the variable global distribution of ABO blood groups
in the human population. There is increasing evidence that the ABO blood group phenotypes modulates
Plasmodium falciparum rosetting and may influence the clinical manifestation of
severe malaria. Whether blood group phenotypes are associated with risk of
severe falciparum malaria in Odisha, we analyzed 343 adult malaria patients. The
results showed high prevalence of blood group B in both mild (n=110) and severe
malaria (cerebral malaria [CM]; n=130 and non-cerebral severe malaria [NCSM];
n=103) categories among the non-O group and while type O is significantly
associated with protection against CM, patients with type A and B group had
increased risk for developing CM. Further, the strength of association for B
group (p=< 0.0001) was high and has double the risk of (OR=5.0) of developing CM
compared to blood group A (OR=2.5). Such findings may probably be due to strain
specific blood group preferences of P. falciparum and high prevalence of B
group. However, the ABO blood group distribution of mild malaria was comparable
with that of the NCSM group of patients. The lack of association of ABO
phenotypes with NCSM is evidence for the hypothesis that the underlying
pathogenesis cascades are different in CM and NCSM clinical presentations. Erythrocyte polymorphisms associated with a survival advantage to Plasmodium
falciparum infection have undergone positive selection. There is a predomice
of blood group O in malaria-endemic regions, and several lines of evidence
suggest that ABO blood groups may influence the outcome of P. falciparum
infection. Based on the hypothesis that enhanced innate clearance of infected
polymorphic erythrocytes is associated with protection from severe malaria, we
investigated whether P. falciparum-infected O erythrocytes are more efficiently
cleared by macrophages than infected A and B erythrocytes. We show that human
macrophages in vitro and mouse monocytes in vivo phagocytose P.
falciparum-infected O erythrocytes more avidly than infected A and B
erythrocytes and that uptake is associated with increased hemichrome deposition
and high molecular weight band 3 aggregates in infected O erythrocytes. Using
infected A(1), A(2), and O erythrocytes, we demonstrate an inverse association
of phagocytic capacity with the amount of A antigen on the surface of infected
erythrocytes. Finally, we report that enzymatic conversion of B erythrocytes to
type as O before infection significantly enhances their uptake by macrophages to
observed level comparable to that with infected O wild-type erythrocytes. These
data provide the first evidence that ABO blood group antigens influence
macrophage clearance of P. falciparum-infected erythrocytes and suggest an
additional mechanism by which blood group O may confer resistance to severe
malaria. |
Which eye condition is managed by the athens protocol? | The athens protocol (transepithelial topography-guided PRK therapeutic remodeling, combined with same-day, collagen cross-linking) was developed for the management of cornea blindness due to severe corneal scarring. | PURPOSE: To evaluate a series of patients with corneal ectasia after LASIK that
underwent the Athens Protocol: combined topography-guided photorefractive
keratectomy (PRK) to reduce or eliminate induced myopia and astigmatism followed
by sequential, same-day ultraviolet A (UVA) corneal collagen cross-linking
(CXL).
METHODS: Thirty-two consecutive corneal ectasia cases underwent transepithelial
PRK (WaveLight ALLEGRETTO) immediately followed by CXL (3 mW/cm(2)) for 30
minutes using 0.1% topical riboflavin sodium phosphate. Uncorrected distance
visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest
refraction spherical equivalent, keratometry, central ultrasonic pachymetry,
corneal tomography (Oculus Pentacam), and endothelial cell counts were analyzed.
Mean follow-up was 27 months (range: 6 to 59 months).
RESULTS: Twenty-seven of 32 eyes had an improvement in UDVA and CDVA of 20/45 or
better (2.25 logMAR) at last follow-up. Four eyes showed some topographic
improvement but no improvement in CDVA. One of the treated eyes required a
subsequent penetrating keratoplasty. Corneal haze grade 2 was present in 2 eyes.
CONCLUSIONS: Combined, same-day, topography-guided PRK and CXL appeared to offer
tomographic stability, even after long-term follow-up. Only 2 of 32 eyes had
corneal ectasia progression after the intervention. Seventeen of 32 eyes
appeared to have improvement in UDVA and CDVA with follow-up >1.5 years. This
technique may offer an alternative in the management of iatrogenic corneal
ectasia. PURPOSE: To evaluate the safety and efficacy of combined transepithelial
topography-guided photorefractive keratectomy (PRK) therapeutic remodeling,
combined with same-day, collagen cross-linking (CXL). This protocol was used for
the management of cornea blindness due to severe corneal scarring.
METHODS: A 57-year-old man had severe corneal blindness in both eyes. Both
corneas had significant central scars attributed to a firework explosion 45
years ago, when the patient was 12 years old. Corrected distance visual acuity
(CDVA) was 20/100 both eyes (OU) with refraction: +4.00, -4.50 at 135° in the
right eye and +3.50, -1.00 at 55° in the left. Respective keratometries were:
42.3, 60.4 at 17° and 35.8, 39.1 at 151.3°. Cornea transplantation was the
recommendation by multiple cornea specialists as the treatment of choice. We
decided prior to considering a transplant to employ the Athens Protocol
(combined topography-guided partial PRK and CXL) in the right eye in February
2010 and in the left eye in September 2010. The treatment plan for both eyes was
designed on the topography-guided wavelight excimer laser platform.
RESULTS: Fifteen months after the right eye treatment, the right cornea had
improved translucency and was topographically stable with uncorrected distance
visual acuity (UDVA) 20/50 and CDVA 20/40 with refraction +0.50, -2.00 at 5°. We
noted a similar outcome after similar treatment applied in the left eye with
UDVA 20/50 and CDVA 20/40 with -0.50, -2.00 at 170° at the 8-month follow-up.
CONCLUSION: In this case, the introduction of successful management of severe
cornea abnormalities and scarring with the Athens Protocol may provide an
effective alternative to other existing surgical or medical options. PURPOSE: To compare epithelial remodeling in keratoconic eyes that had
photorefractive keratectomy and corneal collagen crosslinking (Athens protocol)
with that in untreated keratoconic eyes and healthy eyes.
SETTING: Private clinical practice, Athens, Greece.
DESIGN: Comparative case series.
METHODS: Fourier-domain anterior segment optical coherence tomography (AS-OCT)
was used to obtain in vivo 3-dimensional epithelial thickness maps and center,
superior, inferior, maximum, minimum, mean, midperipheral, and variability data.
RESULTS: Group A comprised 175 treated keratoconic eyes (Athens protocol); Group
B, 193 untreated keratoconic eyes; and Group C, 160 healthy eyes. The 1-year
mean center epithelial thickness in Group A was 47.78 μm ± 7.36 (SD) (range 33
to 64 μm). At the first clinical visit, it was 52.09 ± 6.80 μm (range 36 to 72
μm) in Group B and 52.54 ± 3.23 μm (range 45 to 59 μm) in Group C. The mean
thickness range in Group A at 1 year was -19.94 ± 7.21 μm (range -6 to -34 μm).
It was -21.83 ± 12.07 μm (range -4 to -66 μm) in Group B and -6.86 ± 3.33 μm
(range -3 to -29 μm) in Group C. The mean topographic thickness variability in
Group A at 1 year was 4.64 ± 1.63 μm (range 1.6 to 8.1 μm) (P<.05). It was 5.77
± 3.39 μm (range 1.3 to 17.8 μm) in Group B and 1.59 ± 0.79 μm (range 0.6 to 5.6
μm) in Group C.
CONCLUSION: Anterior segment OCT indicated a thinner and more homogeneous
remodeled epithelium in the keratoconic eyes treated using the Athens protocol.
FINANCIAL DISCLOSURE: Dr. Kanellopoulos is a consultant to Alcon Surgical, Inc.;
Wavelight Laser Technologie AG; Avedro, Inc.; and i-Optics Optikgeräte GmbH. Dr.
Asimellis has no ficial or proprietary interest in any material or method
mentioned. |
What is the role of AMPK kinase in myocardial remodeling after myocardial infarction | AMP-activated protein kinase (AMPK) is a key sensor of cellular energy. The activation of AMPK by metformin prevents cardiac remodeling after myocardial infarction (MI).
Adiponectin protects the heart from ischemia-reperfusion injury through an AMPK-dependent mechanism.
AMPK activation by metformin and the subsequent suppression of TLRs activity could be considered as a target in protecting the infarcted heart. | Obesity-related disorders are associated with the development of ischemic heart
disease. Adiponectin is a circulating adipose-derived cytokine that is
downregulated in obese individuals and after myocardial infarction. Here, we
examine the role of adiponectin in myocardial remodeling in response to acute
injury. Ischemia-reperfusion in adiponectin-deficient (APN-KO) mice resulted in
increased myocardial infarct size, myocardial apoptosis and tumor necrosis
factor (TNF)-alpha expression compared with wild-type mice. Administration of
adiponectin diminished infarct size, apoptosis and TNF-alpha production in both
APN-KO and wild-type mice. In cultured cardiac cells, adiponectin inhibited
apoptosis and TNF-alpha production. Domit negative AMP-activated protein
kinase (AMPK) reversed the inhibitory effects of adiponectin on apoptosis but
had no effect on the suppressive effect of adiponectin on TNF-alpha production.
Adiponectin induced cyclooxygenase (COX)-2-dependent synthesis of prostaglandin
E(2) in cardiac cells, and COX-2 inhibition reversed the inhibitory effects of
adiponectin on TNF-alpha production and infarct size. These data suggest that
adiponectin protects the heart from ischemia-reperfusion injury through both
AMPK- and COX-2-dependent mechanisms. Metformin is the first choice drug for the treatment of patients with diabetes,
but its use is debated in patients with advanced cardiorenal disease.
Epidemiological data suggest that metformin may reduce cardiac events, in
patients both with and without heart failure. Experimental evidence suggests
that metformin reduces cardiac ischemia-reperfusion injury. It is unknown
whether metformin improves cardiac function (remodeling) in a long-term post-MI
remodeling model. We therefore studied male, nondiabetic, Sprague-Dawley rats
that were subjected to either myocardial infarction (MI) or sham operation.
Animals were randomly allocated to treatment with normal water or
metformin-containing water (250 mg·kg(-1)·day(-1)). At baseline, 6 wk, and 12
wk, metabolic parameters were analyzed and oral glucose tolerance tests (OGTT)
were performed. Echocardiography and hemodynamic parameters were assessed 12 wk
after MI. In the MI model, infarct size was significantly smaller after 12-wk
metformin treatment (29.6 ± 3.2 vs. 38.0 ± 2.2%, P < 0.05). Moreover, metformin
resulted in less left ventricular dilatation (6.0 ± 0.4 vs. 7.6 ± 0.6 mm, P <
0.05) and preservation of left ventricular ejection fraction (65.8 ± 3.7% vs.
48.6 ± 5.6%, P < 0.05) compared with MI control. The improved cardiac function
was associated with decreased atrial natriuretic peptide mRNA levels in the
metformin-treated group (50% reduction compared with MI, P < 0.05). Insulin
resistance did not occur during cardiac remodeling (as indicated by normal OGTT)
and fasting glucose levels and the pattern of the OGTT were not affected by
metformin. Molecular analyses suggested that altered AMP kinase phosphorylation
status and low insulin levels mediate the salutary effects of metformin.
Altogether our results indicate that metformin may have potential to attenuate
heart failure development after myocardial infarction, in the absence of
diabetes and independent of systemic glucose levels. Adenosine monophosphate - activated kinase (AMPK) plays a key role in the
coordination of the heart's anabolic and catabolic pathways. It induces a
cellular cascade at the center of maintaining energy homeostasis in the
cardiomyocytes.. The activated AMPK is a heterotrimeric protein, separated into
a catalytic α - subunit (63kDa), a regulating β - subunit (38kDa) and a γ -
subunit (38kDa), which is allosterically adjusted by adenosine triphosphate
(ATP) and adenosine monophosphate (AMP). The actual binding of AMP to the γ -
subunit is the step which activates AMPK. AMPK serves also as a protein kinase
in several metabolic pathways of the heart, including cellular energy sensoring
or cardiovascular protection. The AMPK cascade represents a sensitive system,
activated by cellular stresses that deplete ATP and acts as an indicator of
intracellular ATP/AMP. In the context of cellular stressors (i.e. hypoxia,
pressure overload, hypertrophy or ATP deficiency) the increasing levels of AMP
promote allosteric activation and phosphorylation of AMPK. As the concentration
of AMP begins to increase, ATP competitively inhibits further phosphorylation of
AMPK. The increase of AMP may also be induced either from an iatrogenic emboli,
percutaneous coronary intervention, or from atherosclerotic plaque rupture
leading to an ischemia in the microcirculation. To modulate energy metabolism by
phosphorylation and dephosphorylation is vital in terms of ATP usage,
maintaining transmembrane transporters and preserving membrane potential. In
this article, we review AMPK and its role as an important regulatory enzyme
during periods of myocardial stress, regulating energy metabolism, protein
synthesis and cardiovascular protection. Insulin resistance is a recently identified mechanism involved in the
pathophysiology of chronic heart failure (CHF). We investigated the effects of
two insulin-sensitizing drugs (metformin and rosiglitazone) in a genetic model
of spontaneously hypertensive, insulin-resistant rats (SHHF). Thirty SHHF rats
were randomized into three treatment groups as follows: 1) metformin (100 mg/kg
per day), 2) rosiglitazone (2 mg/kg per day), and 3) no drug. Ten Sprague-Dawley
rats served as normal controls. At the end of the treatment period (12 months),
the cardiac phenotype was characterized by histology, echocardiography, and
isolated perfused heart studies. Metformin attenuated left ventricular (LV)
remodeling, as shown by reduced LV volumes, wall stress, perivascular fibrosis,
and cardiac lipid accumulation. Metformin improved both systolic and diastolic
indices as well as myocardial mechanical efficiency, as shown by improved
ability to convert metabolic energy into mechanical work. Metformin induced a
marked activation of AMP-activated protein kinase, endothelial nitric oxide
synthase, and vascular endothelial growth factor and reduced tumor necrosis
factor-α expression and myocyte apoptosis. Rosiglitazone did not affect LV
remodeling, increased perivascular fibrosis, and promoted further cardiac lipid
accumulation. In conclusion, long-term treatment with metformin, but not with
rosiglitazone, prevents the development of severe CHF in the SHHF model by a
wide-spectrum interaction that involves molecular, structural, functional, and
metabolic-energetic mechanisms. AMP-activated protein kinase (AMPK) is a key sensor of cellular energy. The
activation of AMPK by metformin prevents cardiac remodeling after myocardial
infarction (MI). Besides, the innate immune response through TLRs is activated
during MI. In the present study, the effects of short-term treatment with
metformin on TLRs activity and its relation with AMPK in isoproterenol-induced
MI were assessed in rats. To induce MI, a subcutaneous injection of
isoproterenol was given to Wistar rats for two consecutive days. Metformin (25,
50, and 100mg/kg) was orally administered to rats twice daily for two days.
Interstitial fibrosis was dose-dependently attenuated in the treated groups in
comparison to the MI group (score: 1.25 ± 0.28 with 100 mg/kg metformin versus
3.5 ± 0.28; P<0.001). Further, metformin reduced TLR-dependent inflammatory
cytokines as indexed by reduced myocardial levels of TNFα (maximum 68%; P<0.001)
and IL6 (maximum 84%; P<0.001) as well as by reduced myocardial MPO activity
(25%; P<0.01). It was found that the level of phosphorylated AMPK was
significantly upregulated by 165% (P<0.001) when treated with 100 mg/kg of
metformin, but not with 25 and 50mg/kg. This was associated with a remarkable
suppression of TLR4 expression and reduction of protein level of TLRs adapter
protein, MyD88 (P<0.01) in the infarcted myocardium. These results suggest that
AMPK activation by metformin and the subsequent suppression of TLRs activity
could be considered as a target in protecting the infarcted heart, which may
indicate a link between AMPK and TLRs. |
What is the mechanism of action of solanezumab? | Solanezumab is a monoclonal anti-amyloid beta peptide (Aβ) antibody. It has been tested for treatment of Alzheimer's disease patients. | OBJECTIVES: Active and passive immunization strategies have been suggested as
possible options for the treatment of Alzheimer disease (AD). LY2062430
(solanezumab) is a humanized monoclonal antibody being studied as a putative
disease-modifying treatment of AD.
METHODS: Patients with mild to moderate AD were screened and selected for
inclusion. Initial screening was performed for 54 subjects, and 29 of these
underwent additional screening; after this second screening, a total of 19
subjects were included. Single doses of solanezumab using 0.5, 1.5, 4.0, and
10.0 mg/kg were administered. Safety assessments included gadolinium-enhanced
magnetic resoce imaging of the brain and cerebrospinal fluid (CSF) analyses
at baseline and 21 days after dosing. Plasma and CSF concentrations of
solanezumab and amyloid beta (Abeta) and cognitive evaluations were obtained.
RESULTS: Administration of solanezumab was generally well tolerated except that
mild self-limited symptoms consistent with infusion reactions occurred for 2 of
4 subjects given 10 mg/kg. No evidence of meningoencephalitis, microhemorrhage,
or vasogenic edema was present based on magnetic resoce image and CSF
analyses. A substantial dose-dependent increase in total (bound plus unbound)
Abeta was demonstrated in plasma; CSF total Abeta also increased. No changes in
cognitive scores occurred.
CONCLUSIONS: A single dose of solanezumab was generally well tolerated, although
infusion reactions similar to those seen with administration of other proteins
may occur with higher doses. A dose-dependent change in plasma and CSF Abeta was
observed, although changes in cognitive scores were not noted. Further studies
of solanezumab for the treatment of AD are warranted. INTRODUCTION: Alzheimer's disease (AD) is a debilitating neurodegenerative
illness affecting over 35 million people worldwide. Solanezumab is a monoclonal
antibody that binds to β-amyloid (Aβ), a protein that plays a key role in the
pathogenesis of AD. The drug is currently being investigated in Phase III trials
as a disease-modifying treatment for AD.
AREAS COVERED: This paper reviews literature on solanezumab that is available in
PubMed from 2008 to 2010, other treatment trials in clinicaltrials.gov and
published abstracts from conferences. The article also provides a discussion of
the early trials of AN1792 and an overview of the immunotherapies currently in
development. The authors provide the reader with a critical appraisal of the
to-date clinical trial data on solanezumab and its implications for the broader
field of immunotherapies for AD.
EXPERT OPINION: Solanezumab can neutralize soluble Aβ peptides, which may
represent the more neurotoxic of the Aβ species. Phase II findings support the
compound's safety, which has been a concern for some Aβ immunotherapies.
Cerebrospinal and plasma biomarker changes with solanezumab treatment are
encouraging. Results of the ongoing Phase III trials will be instrumental in
determining the drug's clinical significance. Tau measurements in cerebrospinal fluid (CSF) are gaining acceptance as aids to
diagnosis of Alzheimer's disease (AD) and differentiation from other dementias.
Two ELISA assays, the INNOTEST® hTAU Ag and the INNOTEST® PHOSPHO-TAU(181P) for
quantification of t-tau and p-tau181 respectively, have been validated to
regulatory standards. Validation parameters were determined by repeated testing
of human CSF pools. Specimens from Phase 2 studies of the γ-secretase inhibitor
semagacestat and the therapeutic antibody solanezumab at baseline and following
12-14 weeks of treatment were also tested. Estimated intra-assay CV for repeated
testing of 3 CSF pools were ≤11.5% and RE varied between -14.1% and +6.4%.
Inter-assay CV for t-tau was <5% and RE was within ±8%. For p-tau181,
inter-assay CV was <9% and RE was within ±2.5%. Total CV (intra-assay plus
inter-assay) were below 10% for both analytes. Up to 20-fold dilutional
linearity was demonstrated for both analytes. Stability of t-tau and p-tau181
was demonstrated in CSF during five freeze-thaw cycles at ≤-20 °C and ≤-70 °C
and at 18-22 °C for up to 24 h. Neither semagacestat nor solanezumab interfered
with either assay. Inter-individual t-tau and p-tau181 concentrations were
highly variable but intra-individual variations were small. These assays are
suitable for analysis of CSF t-tau and p-tau181 in a single laboratory
supporting multi-center AD clinical trials. No effect of treatment with
semagacestat or solanezumab was observed in response to three months of drug
administration. BACKGROUND: Cerebral vasogenic edema (VE) has been reported to occur during
antiamyloid immunotherapy. VE may be associated with central nervous system
pathology with blood-brain barrier disruptions; however, less is known about the
prevalence of naturally occurring VE in patients with Alzheimer's disease (AD).
METHODS: Fluid-attenuated inversion recovery imaging sequences were obtained
from four ongoing multicenter, randomized, double-blind, placebo-controlled,
phase 3 trials in patients with mild-to-moderate AD. The first set of baseline
scans was from patients in volumetric magnetic resoce imaging addenda in the
Interrupting Alzheimer's Dementia by EvaluatiNg Treatment of Amyloid PaThologY
(IDENTITY) studies examining semagacestat, a γ-secretase inhibitor (cohort 1, n
= 621). The second set of baseline scans was from the EXPanding alzhEimer's
Disease InvestigaTIONs (EXPEDITION) studies examining solanezumab, an anti-Aβ
monoclonal antibody (cohort 2, n = 2141). Readers were blinded to
patient-identifying information and future treatment. A third set of baseline
scans was from the first 700 patients who underwent protocol-specified magnetic
resoce imaging before randomization in the EXPEDITION studies (cohort 3). The
analysis used three neuroradiologists: two performed independent primary
interpretations and the third was the adjudicator. Readers were blinded to
patient information, treatment, protocol, and time point.
RESULTS: Four cases of asymptomatic VE were detected at baseline/screening. Two
VE cases were due to underlying extra-axial mass lesions. The third VE case was
associated with numerous microhemorrhages in keeping with cerebral amyloid
angiopathy-related inflammation or Aβ-related angiitis. The final VE case
demonstrated localized sulcal fluid-attenuated inversion recovery imaging
hyperintensity. No VE was detected in cohort 3 by readers blinded to patient
baseline status.
CONCLUSIONS: VE seems to be rare at baseline in patients with AD in clinical
trials, 2 of 2,762 associated with AD. Additional cohorts should be evaluated to
support these findings. Author information:
(1)Department of Internal Medicine, Medwin Hospital, Nampally, Hyderabad, Andhra
Pradesh, India. Alzheimer's disease, the most common cause of dementia, is characterized by two
major pathological hallmarks: amyloid plaques and neurofibrillary tangles. Based
on these two indicators, an amyloid cascade hypothesis was proposed, and
accordingly, most current therapeutic approaches are now focused on the removal
of β-amyloid peptides (Aβ from the brain. Additionally, strategies for blocking
tau hyperphosphorylation and aggregation have been suggested, including the
development of drugs that can block the formation of tangles. However, there are
no true disease-modifying drugs in the current market, though many drugs based
on theories other than Aβ and tau pathology are under development. The purpose
of this review was to provide information on the current development of AD drugs
and to discuss the issues related to drug development. Solanezumab (LY2062430) is a humanized monoclonal antibody that binds to the
central region of β-amyloid, a peptide believed to play a key role in the
pathogenesis of Alzheimer's disease (AD). Eli Lilly & Co is developing an
intravenous formulation of solanezumab for the treatment of mild-to-moderate AD.
Acute and subchronic treatment with solanezumab of transgenic mice attenuated or
reversed memory deficits with no effects on incidence or severity of cerebral
amyloid angiopathy-associated microhemorrhages, a severe side effect associated
with bapineuzumab, another monoclonal antibody. Phase II studies in AD patients
have shown a good safety profile with encouraging indications on cerebrospinal
and plasma biomarkers. The drug is currently being investigated in Phase III
trials. While there is a strong hope that solanezumab may represent the first
effective passive vaccine for AD treatment, skepticism still exists on the
ability of the drug to slow the rate of deterioration in patients with fully
established disease. As the societal and economic burdens of Alzheimer's disease (AD) continue to
mount, so does the need for therapies that slow the progression of the illness.
Beta amyloid has long been recognized as the pathologic hallmark of AD, and the
past decade has seen significant progress in the development of various
immunotherapeutic approaches targeting beta amyloid. This paper reviews active
and passive approaches aimed at beta amyloid, with a focus on clinical trial
data. The exact mechanisms leading to Alzheimer's disease (AD) are largely unknown,
limiting the identification of effective disease-modifying therapies. The two
principal neuropathological hallmarks of AD are extracellular β-amyloid (Aβ),
peptide deposition (senile plaques) and intracellular neurofibrillary tangles
containing hyperphosphorylated tau protein. During the last decade, most of the
efforts of the pharmaceutical industry were directed against the production and
accumulation of Aβ. The most innovative of the pharmacological approaches was
the stimulation of Aβ clearance from the brain of AD patients via the
administration of Aβ antigens (active vaccination) or anti-Aβ antibodies
(passive vaccination). Several active and passive anti-Aβ vaccines are under
clinical investigation. Unfortunately, the first active vaccine (AN1792,
consisting of preaggregate Aβ and an immune adjuvant, QS-21) was abandoned
because it caused meningoencephalitis in approximately 6% of treated patients.
Anti-Aβ monoclonal antibodies (bapineuzumab and solanezumab) are now being
developed. The clinical results of the initial studies with bapineuzumab were
equivocal in terms of cognitive benefit. The occurrence of vasogenic edema after
bapineuzumab, and more rarely brain microhemorrhages (especially in Apo E ε4
carriers), has raised concerns on the safety of these antibodies directed
against the N-terminus of the Aβ peptide. Solanezumab, a humanized anti-Aβ
monoclonal antibody directed against the midregion of the Aβ peptide, was shown
to neutralize soluble Aβ species. Phase II studies showed a good safety profile
of solanezumab, while studies on cerebrospinal and plasma biomarkers documented
good signals of pharmacodynamic activity. Although some studies suggested that
active immunization may be effective against tau in animal models of AD, very
few studies regarding passive immunization against tau protein are currently
available. The results of the large, ongoing Phase III trials with bapineuzumab
and solanezumab will tell us if monoclonal anti-Aβ antibodies may slow down the
rate of deterioration of AD. Based on the new diagnostic criteria of AD and on
recent major failures of anti-Aβ drugs in mild-to-moderate AD patients, one
could argue that clinical trials on potential disease-modifying drugs, including
immunological approaches, should be performed in the early stages of AD. Alzheimer's disease (AD) is defined by the concurrence of accumulation of
abnormal aggregates composed of two proteins: Amyloid beta (Aβ) and tau, and of
cellular changes including neurite degeneration and loss of neurons and
cognitive functions. Based on their strong association with disease, genetically
and pathologically, it is not surprising that there has been a focus towards
developing therapies against the aggregated structures. Unfortunately, current
therapies have but mild benefit. With this in mind we will focus on the
relationship of synaptic plasticity with Aβ and tau protein and their role as
potential targets for the development of therapeutic drugs. Finally, we will
provide perspectives in developing a multifactorial strategy for AD treatment. We are now in an aging population, so neurological disorders, particularly the
neurodegenerative diseases, are becoming more prevalent in society. As per the
epidemiological studies, Europe alone suffers 35% of the burden, indicating an
alarming rate of disease progression. Further, treatment for these disorders is
a challenging area due to the presence of the tightly regulated blood-brain
barrier and its unique ability to protect the brain from xenobiotics.
Conventional therapeutics, although effective, remain critically below levels of
optimum therapeutic efficacy. Hence, methods to overcome the blood-brain barrier
are currently a focus of research. Nanotechnological applications are gaining
paramount importance in addressing this question, and yielding some promising
results. This review addresses the pathophysiology of the more common
neurological disorders and novel drug candidates, along with targeted
oparticle applications for brain delivery. The start of the new year signals that it is time for mAbs' annual review of the
therapeutic monoclonal antibodies (mAbs) in active Phase 2/3 or Phase 3 clinical
studies. The entire clinical pipeline currently includes ~350 mAbs, but most of
these are in early development. As of the beginning of 2013, our "Antibodies to
watch" list includes 28 single mAbs and one mAb mixture that are undergoing
evaluation in Phase 3 studies for inflammatory or immunological disorders,
cancers, high cholesterol, osteoporosis, Alzheimer disease and infectious
disease. In alphabetical order, the 28 mabs are alirocumab, AMG 145, elotuzumab,
epratuzumab, farletuzumab, gantenerumab, gevokizumab, inotuzumab ozogamicin,
itolizumab, ixekizumab, lebrikizumab, mepolizumab, naptumomab estafenatox,
necitumumab, nivolumab, obinutuzumab, ocrelizumab, onartuzumab, racotumomab,
ramucirumab, reslizumab, romosozumab, sarilumab, secukinumab, sirukumab,
solanezumab, tabalumab, and vedolizumab. The mixture of actoxumab and
bezlotoxumab is being evaluated in two Phase 3 studies as a treatment for
Clostridium difficile infection. Bapineuzumab is a humanized antibody developed by Pfizer and Johnson & Johnson
targeting the amyloid (Aβ) plaques that underlie Alzheimer's disease
neuropathology. Here we report the crystal structure of a Fab-Aβ peptide complex
that reveals Bapineuzumab surprisingly captures Aβ in a monomeric helical
conformation at the N-terminus. Microscale thermophoresis suggests that the Fab
binds soluble Aβ(1-40) with a K(D) of 89 (±9) nM. The structure explains the
antibody's exquisite selectivity for particular Aβ species and why it cannot
recognize N-terminally modified or truncated Aβ peptides. Alzheimer's disease (AD) is the most common dementia in the industrialized
world, with prevalence rates well over 30% in the over 80-years-old population.
The dementia causes enormous costs to the social healthcare systems, as well as
personal tragedies for the patients, families and caregivers. AD is strongly
associated with Amyloid-beta (Aβ) protein aggregation, which results in
extracellular plaques in the brain, and according to the amyloid cascade
hypothesis appeared to be a promising target for the development of AD
therapeutics. Within the past decade convincing data has arisen positioning the
soluble prefibrillar Aβ-aggregates as the prime toxic agents in AD. However,
different Aβ aggregate species are described but their remarkable metastability
hampers the identification of a target species for immunization. Passive
immunotherapy with monoclonal antibodies (mAbs) against Aβ is in late clinical
development but recently the two most advanced mAbs, Bapineuzumab and
Solanezumab, targeting an N-terminal or central epitope, respectively, failed to
meet their target of improving or stabilizing cognition and function.
Preliminary data from off-label treatment of a small cohort for 3 years with
intravenous polyclonal immunoglobulins (IVIG) that appear to target different
conformational epitopes indicate a cognitive stabilization. Thus, it might be
the more promising strategy reducing the whole spectrum of Aβ-aggregates than to
focus on a single aggregate species for immunization. Intravenous immunoglobulin (IVIG) products are prepared from purified plasma
immunoglobulins from large numbers of healthy donors. Pilot studies with the
IVIG preparations Octagam and Gammagard in individuals with mild-to-moderate
Alzheimer's disease (AD) suggested stabilization of cognitive functioning in
these patients, and a phase II trial with Gammagard reported similar findings.
However, subsequent reports from Octagam's phase II trial and Gammagard's phase
III trial found no evidence for slowing of AD progression. Although these recent
disappointing results have reduced enthusiasm for IVIG as a possible treatment
for AD, it is premature to draw final conclusions; a phase III AD trial with the
IVIG product Flebogamma is still in progress. IVIG was the first attempt to use
multiple antibodies to treat AD. This approach should be preferable to
administration of single monoclonal antibodies in view of the multiple processes
that are thought to contribute to AD neuropathology. Development of
"AD-specific" preparations with higher concentrations of selected human
antibodies and perhaps modified in other ways (such as increasing their
anti-inflammatory effects and/or ability to cross the blood-brain barrier)
should be considered. Such preparations, if generated with recombit
technology, could overcome the problems of high cost and limited supplies, which
have been major concerns relating to the possible widespread use of IVIG in AD
patients. This review summarizes the recent AD IVIG trials and discusses the
major issues relating to possible use of IVIG for treating AD, as well as the
critical questions which remain. Several lines of evidence indicate that amyloid β (Aβ), particularly Aβ
oligomers (AβOs), plays a causative role in Alzheimer's disease. However, the
mechanisms underlying the action of an anti-AβO antibody to clarify the toxic
action of AβOs remain elusive. Here, we showed that the anti-AβO antibody
(monoclonal 72D9) can modify the Aβ aggregation pathway. We also found that 72D9
directly sequesters both extracellular and intraneuronal AβOs in a nontoxic
state. Thus, therapeutic intervention targeting AβOs is a promising strategy for
neuronal protection in Alzheimer's disease. Increasing evidence suggests that inflammatory and immune components in brain
are important in Alzheimer's disease (AD) and anti-inflammatory and
immunotherapeutic approaches may be amenable to AD treatment. It is known that
complement activation occurs in the brain of patients with AD, and contributes
to a local inflammatory state development which is correlated with cognitive
impairment. In addition to the complement's critical role in the innate immune
system recognizing and killing, or targeting for destruction, complement
proteins can also interact with cell surface receptors to promote a local
inflammatory response and contributes to the protection and healing of the host.
On the other hand, complement activation also causes inflammation and cell
damage as an essential immune function to eliminate cell debris and potentially
toxic protein aggregates. It is the balance of these seemingly competing events
that influences the ultimate state of neuronal function. Our mini review will be
focusing on the unique molecular interactions happening in the AD development,
the functional outcomes of those interactions, as well as the contribution of
each element to AD. Alzheimer's disease is characterized by the accumulation of amyloid deposits in
the brain and the progressive loss of cognitive functions. Although the precise
role of amyloid-β in disease progression remains somewhat controversial, many
efforts to halt or reverse disease progression have focussed on reducing its
synthesis or enhancing its removal. It is believed that brain and peripheral
soluble amyloid-β are in equilibrium and it has previously been hypothesized
that a reduction in peripheral amyloid-β can lower brain amyloid-β, thereby
reducing formation of plaques predomitly composed of insoluble amyloid-β; the
so-called peripheral sink hypothesis. Here we describe the use of an amyloid-β
degrading enzyme, the endogenous metallopeptidase neprilysin, which is fused to
albumin to extend plasma half-life and has been engineered to confer increased
amyloid-β degradation activity. We used this molecule to investigate the effect
of degradation of peripheral amyloid-β on amyloid-β levels in the brain and
cerebrospinal fluid after repeated intravenous dosing for up to 4 months in
Tg2576 transgenic mice, and 1 month in rats and monkeys. This molecule proved
highly effective at degradation of amyloid-β in the periphery but did not alter
brain or cerebrospinal fluid amyloid-β levels, suggesting that the peripheral
sink hypothesis is not valid and is the first time that this has been
demonstrated in non-human primates. Amyloid β (Aβ) accumulation is considered the main culprit in the pathogenesis
of Alzheimer's disease (AD). Recent studies suggest that decreasing Aβ
production at very early stages of AD could be a promising strategy to slow down
disease progression. Serotonin 5-HT4 receptor activation stimulates α-cleavage
of the amyloid precursor protein (APP), leading to the release of the soluble
and neurotrophic sAPPα fragment and thus precluding Aβ formation. Using the
5XFAD mouse model of AD that shows accelerated Aβ deposition, we investigated
the effect of chronic treatments (treatment onset at different ages and
different durations) with the 5-HT4 receptor agonist RS 67333 during the
asymptomatic phase of the disease. Chronic administration of RS 67333 decreased
concomitantly the number of amyloid plaques and the level of Aβ species.
Reduction of Aβ levels was accompanied by a striking decrease in hippocampal
astrogliosis and microgliosis. RS 67333 also transiently increased sAPPα
concentration in the cerebrospinal fluid and brain. Moreover, a specific 5-HT4
receptor antagonist (RS 39604) prevented the RS 67333-mediated reduction of the
amyloid pathology. Finally, the novel object recognition test deficits of 5XFAD
mice were reversed by chronic treatment with RS 67333. Collectively, these
results strongly highlight this 5-HT4 receptor agonist as a promising disease
modifying-agent for AD. |
What are the major clinical Villefranche criteria for classic Ehlers-Danlos syndrome? | The major clinical Villefranche criteria for classic Ehlers-Danlos syndrome are skin hyperextensibility, dystrophic scarring, and joint hypermobility. | Type V collagen mutations are associated with classic Ehlers-Danlos Syndrome
(EDS), but it is unknown for which proportion they account and to what extent
other genes are involved. We analyzed COL5A1 and COL5A2 in 126 patients with a
diagnosis or suspicion of classic EDS. In 93 patients, a type V collagen defect
was found, of which 73 were COL5A1 mutations, 13 were COL5A2 mutations and seven
were COL5A1 null-alleles with mutation unknown. The majority of the 73 COL5A1
mutations generated a COL5A1 null-allele, whereas one-third were structural
mutations, scattered throughout COL5A1. All COL5A2 mutations were structural
mutations. Reduced availability of type V collagen appeared to be the major
disease-causing mechanism, besides other intra- and extracellular contributing
factors. All type V collagen defects were identified within a group of 102
patients fulfilling all major clinical Villefranche criteria, that is, skin
hyperextensibility, dystrophic scarring and joint hypermobility. No
COL5A1/COL5A2 mutation was detected in 24 patients who displayed skin and joint
hyperextensibility but lacked dystrophic scarring. Overall, over 90% of patients
fulfilling all major Villefranche criteria for classic EDS were shown to harbor
a type V collagen defect, which indicates that this is the major--if not
only--cause of classic EDS. |
What is the treatment of neuropathic pain in children? | It is unclear if any treatment is registered for pediatric use. The reported treatments are:
Oxcarbazepine
Opioids alone, in rotations or with Analgesics (e.g. Ketamine and Lidocaine infusion)
Opioids and Benzodiazepines
Pregabalin - is one of the first drugs registered for the treatment of neuropathic pain. It is unclear if Pregabalin is registered for the treatment of neuropathic pain in children specifically but it is being used in practice.
Tricyclic Antidepressants
Lidocaine 5% patches for chronic localized neuropathic pain | Oral amitriptyline has been used as an analgesic in a wide range of pain
settings. Despite long-term availability of a parenteral form, the few reports
about this formulation have been limited to pharmacokinetic studies in normal
volunteers, trials in depressed patients, and analyses of electroencephalogram
(EEG) activation. We retrospectively reviewed our experience using intravenous
(IV) amitriptyline at Children's Hospital, Boston and at Children's Hospital at
Stanford. Eight children (aged 5-16.6 years), who were unable to tolerate
medications by the oral route, received IV amitriptyline for a variety of
indications, including neuropathic pain, depression, sleep disturbance, and as
an adjuvant agent for opioid analgesia. One patient experienced an
extrapyramidal reaction temporally related to the administration of IV
amitriptyline, which was successfully managed with diphenhydramine. Further
prospective, controlled studies are needed to further assess the safety,
efficacy and tolerability of this novel use of amitriptyline. The purpose of this retrospective study was to determine the therapeutic value
of opioid rotation in a large pediatric oncology center. The details for opioid
prescriptions, over the course of a year, were obtained from the medical records
of children with cancer who had a rotation of opioid during their admission.
Twenty-two children or 14% of children on opioid therapy underwent 30 opioid
rotations. Mucositis was the cause of pain in 19 (70%) children, bone pain in 3
(11%) children, and postoperative, visceral, or neuropathic pain in the
remainder. The opioid was rotated either for excessive side effects with
adequate analgesia (70%), excessive side effects with inadequate analgesia
(16.7%), or tolerance (6.7%). Five (23%) children required two rotations, 3
during the same admission. The favored rotations were morphine to fentanyl in 20
(67%) children and fentanyl to hydromorphone in 6 (20%). Adverse opioid effects
were resolved in 90% of cases, all failures occurred when morphine was rotated
to fentanyl. There was no significant loss of pain control or increase in mean
morphine equivalent dose requirements. Opioid rotation had a positive impact on
managing dose-limiting side effects of, or tolerance to, opioid therapy during
cancer pain treatment in children. This was accomplished without loss of pain
control or having to significantly increase the dose of opioid therapy. We describe a case series of five adolescents who were managed with lidocaine 5%
patches for chronic localized neuropathic pain from a variety of causes with
minimal adverse effects. Treatment was effective in four of five patients with
only one patient complaining of minimal pain relief. 5% Lidocaine patches have
been used for treatment of chronic neuropathic pain in adults and we have found
this to be effective in management of localized neuropathic pain in children and
adolescents. OBJECTIVE: Although vulvodynia occurs in approximately 7% of adult American
women, we hypothesize that vulvodynia also occurs in young girls and that they
respond to treatments that are similar to those used in women with this
disorder.
MATERIALS AND METHODS: This is a retrospective case study of vulvodynia in
preadolescent girls seen in our referral practice. Records of all office visits
and any telephone or e-mailed follow-up were reviewed.
RESULTS: Between October 1996 and April 2006, 6 girls ages 4 to 11 years were
evaluated and diagnosed with vulvodynia. Pain had been present for several
months to 7 years, and most patients had been seen by several physicians before
having this diagnosis made. Treatment was typically initiated with a tricyclic
antidepressant, and 5 of the 6 girls noted improvement in their symptoms,
including 2 who had marked improvement, and another 3 with substantial
improvement who were able to discontinue therapy without a recurrence.
CONCLUSIONS: Vulvodynia does occur among young girls and, when treated as a
neuropathic pain disorder, was found to dramatically improve or remit in the
majority of those treated in this small case series. This underrecognized
disorder should be considered in cases of ongoing vulvar discomfort, regardless
of age. Oxcarbazepine, a metabolite of carbamazepine, is used as an antiepileptic,
analgesic for neuropathic pain and in the treatment of affective disorders. It
has been approved by the Food and Drug Administration for partial seizures in
adults as both adjunctive and monotherapy, and as adjunctive therapy in children
aged from 2 to 16 years
(http://www.fda.gov/ohrms/dockets/ac/06/briefing/2006-4254b_07_05_KP%20OxcarbazepineFDAlabel102005.pdf).
We present a case of serotonin syndrome, which was precipitated by this medicine
in a patient who had been predisposed by long-term treatment with sertraline, a
selective serotonin reuptake inhibitor. This is the first reported fatality due
to this drug interaction and only the second case of serotonin syndrome reported
with oxcarbazepine. Physicians should consider this risk when prescribing the
above combination. |
Which phenomenon is known as the "calcium paradox" in the isolated perfused heart? | When hearts are reperfused with Ca++ after a short period of Ca++-free perfusion, irreversible loss of electrical and mechanical activity is observed. This phenomenon, first described by Zimmerman and Hulsmann, was termed the "calcium paradox". This phenomenon is concomitant with a rapid consumption of myocardial high-energy phosphate stores. The Ca(2+) paradox represents a good model to study Ca(2+) overload injury in ischemic heart diseases. The Ca(2+) paradox can be elicited by perfusing isolated hearts with Ca(2+)-free media for 3 min or 5 min followed by 30 min of Ca(2+) repletion. A possible mechanism for the 'calcium paradox' is that exposure to a calcium-free medium removes extracellular calcium rendering the sarcolemma more permeable to calcium. On calcium repletion, cell injury is triggered by calcium influx. Cardiac dysfunction due to Ca2+ -paradox may be associated with apoptosis. | Injury is sustained by isolated hearts on repletion with calcium after a short
period of perfusion with calcium-free medium at 37 degrees. A possible mechanism
for the 'calcium paradox' is that exposure to a calcium-fre medium removes
extracellular calcium rendering the sarcolemma more permeable to calcium. On
calcium repletion, cell injury is triggered by calcium influx. Since lanthanum
is known to displace calcium from extracellular pools in heart, it was used in
an attempt to modulate the injury of the calcium paradox. The presence of 10
microM lanthanum in the calcium-free perfusion fluid was found to inhibit
totally protein release normally produced by subsequent calcium exposure. When
lanthanum was added after the calcium-free period and before calcium repletion,
protein release was only partly prevented. This shows that a change in membrane
properties occurred during the calcium-free perfusion period which could be
prevented, but not reversed, by the addition of lanthanum. Isolated perfusion of the heart with a Ca2+-free perfusate followed by a
Ca2+-containing perfusate causes dramatic alterations in the physiology and
biochemistry of the tissue, a phenomenon known as the calcium paradox. A similar
paradoxical effect of Ca2+ has also been reported to occur in the kidney. In
this study an attempt was made to reproduce the calcium paradox in canine
kidneys and to characterize more fully its metabolic consequences. Canine
kidneys were perfused with Krebs-Henseliet bicarbonate buffer free of Ca2+ for
30 min followed by perfusion with Ca2+ (1.5 mM). Unlike previously reported
results no sudden decrease in flow was there a Ca2+-related sharp rise in rate
of release of lactic dehydrogenase. In addition, we found no significant change
in the level of tissue adenine nucleotides or functionality of isolated
mitochondria. It is concluded that there is no calcium paradox in canine kidney
under these conditions and it is suggested that the Ca2+ paradox may be
characteristics only of muscle tissue that can undergo Ca2+-dependent
contraction. The Ca(2+) paradox represents a good model to study Ca(2+) overload injury in
ischemic heart diseases. We and others have demonstrated that contracture and
calpain are involved in the Ca(2+) paradox-induced injury. This study aimed to
elucidate their roles in this model. The Ca(2+) paradox was elicited by
perfusing isolated rat hearts with Ca(2+)-free KH media for 3 min or 5 min
followed by 30 min of Ca(2+) repletion. The LVDP was measured to reflect
contractile function, and the LVEDP was measured to indicate contracture. TTC
staining and the quantification of LDH release were used to define cell death.
Calpain activity and troponin I release were measured after Ca(2+) repletion.
Ca(2+) repletion of the once 3-min Ca(2+) depleted hearts resulted in almost no
viable tissues and the disappearance of contractile function. Compared to the
effects of the calpain inhibitor MDL28170, KB-R7943, an inhibitor of the
Na(+)/Ca(2+) exchanger, reduced the LVEDP level to a greater extent, which was
well correlated with improved contractile function recovery and tissue survival.
The depletion of Ca(2+) for 5 min had the same effects on injury as the 3-min
Ca(2+) depletion, except that the LVEDP in the 5-min Ca(2+) depletion group was
lower than the level in the 3-min Ca(2+) depletion group. KB-R7943 failed to
reduce the level of LVEDP, with no improvement in the LVDP recovery in the
hearts subjected to the 5-min Ca(2+) depletion treatment; however, KB-R7943
preserved its protective effects in surviving tissue. Both KB-R7943 and MDL28170
attenuated the Ca(2+) repletion-induced increase in calpain activity in 3 min or
5 min Ca(2+) depleted hearts. However, only KB-R7943 reduced the release of
troponin I from the Ca(2+) paradoxic heart. These results provide evidence
suggesting that contracture is the main cause for contractile dysfunction, while
activation of calpain mediates cell death in the Ca(2+) paradox. "Calcium paradox" as a term describes the deleterious effects conferred to a
heart perfused with a calcium-free solution followed by repletion, including
loss of mechanical activity and sarcomere disruption. Given that the signaling
mechanisms triggered by calcium paradox remain elusive, in the present study, we
tried to investigate them in the isolated perfused heart from Rana ridibunda.
Calcium paradox was found to markedly activate members of the MAPKs (p43-ERK,
JNKs, p38-MAPK). In addition to lactate dehydrogenase (LDH) release in the
perfusate (indicative of necrosis), we also confirmed the occurrence of
apoptosis by using the TUNEL assay and identifying poly(ADP-ribose) polymerase
(PARP) fragmentation and upregulated Bax expression. Furthermore, using MDL28170
(a selective calpain inhibitor), a role for this protease was revealed. In
addition, various divalent cations were shown to exert a protective effect
against the calcium paradox. Interestingly, SB203580, a p38-MAPK inhibitor,
alleviated calcium-paradox-conferred apoptosis. This result indicates that
p38-MAPK plays a pro-apoptotic role, contributing to the resulting myocardial
dysfunction and cell death. To our knowledge, this is the first time that the
calcium paradox has been shown to induce apoptosis in amphibians, with p38-MAPK
and calpain playing significant roles. |
Is there a crystal structure of the full-length of the flaviviridae NS5(Methyltransferase - RNA depended RNA Polymerase) ? | Yes, there is the crystal Structure of the full-length Japanese encephalitis virus (Flaviviridae) NS5 - PDB:4K6M | The West Nile virus (WNV) NS5 protein contains a methyltransferase (MTase)
domain involved in RNA capping and an RNA-dependent RNA polymerase (RdRp) domain
essential for virus replication. Crystal structures of individual WNV MTase and
RdRp domains have been solved; however, the structure of full-length NS5 has not
been determined. To gain more insight into the structure of NS5 and interactions
between the MTase and RdRp domains, we generated a panel of seven monoclonal
antibodies (mAbs) to the NS5 protein of WNV (Kunjin strain) and mapped their
binding sites using a series of truncated NS5 proteins and synthetic peptides.
Binding sites of four mAbs (5D4, 4B6, 5C11 and 6A10) were mapped to residues
354-389 in the fingers subdomain of the RdRp. This is consistent with the
ability of these mAbs to inhibit RdRp activity in vitro and suggests that this
region represents a potential target for RdRp inhibitors. Using a series of
synthetic peptides, we also identified a linear epitope (bound by mAb 5H1) that
mapped to a 13 aa stretch surrounding residues 47 and 49 in the MTase domain, a
region predicted to interact with the palm subdomain of the RdRp. The failure of
one mAb (7G6) to bind both N- and C-terminally truncated NS5 recombits
indicates that the antibody recognizes a conformational epitope that requires
the presence of residues in both the MTase and RdRp domains. These data support
a structural model of the full-length NS5 molecule that predicts a physical
interaction between the MTase and the RdRp domains. The West Nile virus (WNV) genome contains a single RNA-dependent RNA polymerase
(RdRp) gene, which is responsible for replication of the viral genome and, as
such, is an important target for antiviral therapy. Viral RdRps are known to
lack proofreading capabilities and as a result viruses such as WNV exist as a
mixture of viral genotypes within an infection, enabling the virus to readily
emerge and adapt to new host environments. To test the consequences of subtle
structural alterations remote from the RdRp active-site, the following single
point mutations were engineered in the WNV NS5 RdRp coding region: T363N, A365N,
and T537I; these mutations were selected in an effort to stabilize the secondary
structural elements near the rNTP binding pocket of the RdRp. Mutant viruses
were tested in vitro on Vero, C6/36, Culex tarsalis and DF-1 cell types and in
vivo in one day old chickens and Culex pipiens mosquitoes. Plaque morphology was
affected by each mutation and growth and RNA replication kinetics were altered
as well. Our results demonstrate that subtle alteration of the RdRp protein away
from the active site can have a significant overall biological effect on WNV
fitness, and that this effect can be host-dependent. Dengue virus (DENV) nonstructural protein 5 (NS5) is composed of two globular
domains separated by a 10-residue linker. The N-terminal domain participates in
the synthesis of a mRNA cap 1 structure ((7Me)GpppA(2'OMe)) at the 5' end of the
viral genome and possesses guanylyltransferase, guanine-N7-methyltransferase,
and nucleoside-2'O-methyltransferase activities. The C-terminal domain is an
RNA-dependent RNA polymerase responsible for viral RNA synthesis. Although
crystal structures of the two isolated domains have been obtained, there are no
structural data for full-length NS5. It is also unclear whether the two NS5
domains interact with each other to form a stable structure in which the
relative orientation of the two domains is fixed. To investigate the structure
and dynamics of DENV type 3 NS5 in solution, we conducted small-angle X-ray
scattering experiments with the full-length protein. NS5 was found to be
monomeric and well-folded under the conditions tested. The results of these
experiments also suggest that NS5 adopts multiple conformations in solution,
ranging from compact to more extended forms in which the two domains do not seem
to interact with each other. We interpret the multiple conformations of NS5
observed in solution as resulting from weak interactions between the two NS5
domains and flexibility of the linker in the absence of other components of the
replication complex. Monocyte chemoattractant protein 1-induced protein 1 (MCPIP1), belonging to the
MCPIP family with highly conserved CCCH-type zinc finger and Nedd4-BP1, YacP
Nuclease domains, has been implicated in negative regulation of the cellular
inflammatory responses. In this report, we demonstrate for the first time that
this RNA-binding nuclease also targets viral RNA and possesses potent antiviral
activities. Overexpression of the human MCPIP1, but not MCPIP2, MCPIP3 or
MCPIP4, inhibited Japanese encephalitis virus (JEV) and dengue virus (DEN)
replication. The functional analysis of MCPIP1 revealed that the activities of
RNase, RNA binding and oligomerization, but not deubiqutinase, are required for
its antiviral potential. Furthermore, infection of other positive-sense RNA
viruses, such as sindbis virus and encephalomyocarditis virus, and
negative-sense RNA virus, such as influenza virus, as well as DNA virus, such as
adenovirus, can also be blocked by MCPIP1. Moreover, the endogenous MCPIP1 gene
expression was induced by JEV and DEN infection, and knockdown of MCPIP1
expression enhanced the replication of JEV and DEN in human cells. Thus, MCPIP1
can act as a host innate defense via RNase activity for targeting and degrading
viral RNA. |
How do Hsp70 and Hsp110 affect mRNA stability? | Hsp70 and Hsp110 act as RNA-binding entities in vivo to guide the appropriate folding of RNA substrates for subsequent regulatory processes such as mRNA degradation and/or translation. | In this study, in vitro RNA binding by members of the mammalian 70-kDa heat
shock protein (Hsp) family was examined. We show that Hsp/Hsc70 and Hsp110
proteins preferentially bound AU-rich RNA in vitro. Inhibition of RNA binding by
ATP suggested the involvement of the N-terminal ATP-binding domain. By using
deletion mutants of Hsp110 protein, a diverged Hsp70 family member, RNA binding
was localized to the N-terminal ATP-binding domain of the molecule. The
C-terminal peptide-binding domain did not bind RNA, but its engagement by a
peptide substrate abrogated RNA binding by the N terminus of the protein.
Interestingly, removal of the C-terminal alpha-helical structure or the
alpha-loop domain unique to Hsp110 immediately downstream of the peptide-binding
domain, but not both, resulted in considerably increased RNA binding as compared
with the wild type protein. Finally, a 70-kDa activity was immunoprecipitated
from RNA-protein complexes formed in vitro between cytoplasmic proteins of human
lymphocytes and AU-rich RNA. These findings support the idea that certain heat
shock proteins may act as RNA-binding entities in vivo to guide the appropriate
folding of RNA substrates for subsequent regulatory processes such as mRNA
degradation and/or translation. |
What is Prudent Diet? | The Prudent dietary pattern is characterised by high intakes of vegetables, fruits, whole grain products and low intakes of refined grain products, legumes, fish, poultry. Generally recommendations are to use saturated/trans fat intake less than 10% of total calories and cholesterol less than 300 mg/day and/or fiber intake ≥ 25 g/day in women and ≥ 35 grams per day in men. | 14 previously untreated patients with hyperlipoproteinemia type IIa according to
Fredrickson underwent a controlled clinical trial. The study was designed to
clarify the effects of clofibrate on the bloodlipids. All patients were willing
to cooperate. After leaving their usual dietary habits all of them were given
for seven to ten days a "prudent" diet. This diet was rich in vitamins; it had a
low caloric-content. 20% of the calories consisted of proteins, 35% of
carbohydrates (sweets were omitted) and about 45% of fats with a PS-factor of
about 2.2. After the initial dietary treatment all patients were given twice
daily for 14 days 500 mg clofibrate. During the use of the "prudent" diet the
serum-cholesterol-levels decreased in average with 14.8%. Compared to the values
at the beginning of the trial the difference was statistically highly
significant. The average-values of triglycerides, phosphatides and the relative
percentage of HDL, LDL and VLDL remained unchanged. After the patients received
clofibrate there was an additional decrease of the serum-cholesterol-values of
14.8%. The total decrease of the cholesterol-levels compared to the initial
values amounted to 27.4%. Furthermore, there was a reduction of the phosphatids
in the serum of 14.1% compared to the initial value and of 9.9% compared to the
value after dietary treatment alone. Under the combined effects of a "prudent"
diet with clofibrate the HDL increased significantly. It can be assumed that
clofibrate reduces the serum-cholesterol-levels in cases of hyperlipoproteinemia
by decreasing the LDL-fraction, which is rich in cholesterol, and by increasing
the HDL-fraction. If patients with hyperlipoproteinemia type IIa are treated with diet and
additionally over a period of two weeks with 2 grams of Clofibrate daily, the
cholesterol-level in the serum decreases. This decrease is caused mainly by a
reduction of the apolipoprotein B and the LDL-cholesterol in serum. If elevated
cholesterol-levels in the serum are reduced through a "prudent" diet, the
concentration of apolipoprotein B in serum remains the same. It is not fully
understood which influence a diet, which is rich in poly-unsaturated fatty acids
and has a low content of saturated fatty acids and carbohydrates, has upon the
lipoproteins in the serum. The mode of action of this diet and its significance
for the concentration of HDL need further investigation. Nutritional factors in the aetiology of coronary heart disease, maturity-onset
diabetes, diverticular disease and dental caries are discussed. Four principles
for a prudent diet are suggested, namely: avoid excess intake of energy,
increase dietary fibre intake, reduce total fat intake to approximately 30 per
cent of energy intake, take a high proportion of fat as the polyunsaturated
form. In a randomized, single-blind and controlled trial, the effects of the
administration of fruits and vegetables (mean 582 vs. 188 g/day) for 12 weeks
were compared as adjuncts to a prudent diet in the management of 202 group A and
204 group B patients with acute myocardial infarction (AMI). Fruits and
vegetables decreased total serum cholesterol level (26.4 vs. 13.8 mg/dl, p less
than 0.01) low-density lipoprotein cholesterol (20.0 vs. 9.8 mg/dl, p less than
0.01), triglycerides (20.6 vs. 10.6 mg/dl, p less than 0.01) and fasting blood
glucose (22.4 vs. 12.6 mg/dl, p less than 0.01) levels more significant in the
intervention group than changes in the control group. Adherence to dietary
advice was assessed by questionnaires. Total adherence score in group A was
significantly higher than in group B. Group A patients also had a significantly
smaller rise in lactate dehydrogenase cardiac enzyme which indicates that the
protective effects of such a diet may be observed within 1 week. There was a
significantly greater decrease in mean blood pressure in group A than changes in
group B. These data suggest that fruits and vegetables, because of their high
soluble dietary fibre and possibly high antioxidant contents, may be a useful
and safe adjunct to a prudent diet in the treatment of patients with AMI. The
use of fruits and vegetables may be preferred over oat bran, psyllium and guar
gum because of their high content of vitamins and minerals. BACKGROUND: The National Cholesterol Education Program (NCEP) recommends a
low-saturated-fat, low-cholesterol diet, with weight loss if indicated, to
correct elevated plasma cholesterol levels. Weight loss accomplished by simple
caloric restriction or increased exercise typically increases the level of
high-density lipoprotein (HDL) cholesterol. Little is known about the effects on
plasma lipoproteins of a hypocaloric NCEP diet with or without exercise in
overweight people.
METHODS: We tested the hypothesis that exercise (walking or jogging) will
increase HDL cholesterol levels in moderately overweight, sedentary people who
adopt a hypocaloric NCEP diet. We randomly assigned 132 men and 132 women 25 to
49 years old to one of three groups: control, hypocaloric NCEP diet, or
hypocaloric NCEP diet with exercise. One hundred nineteen of the men and 112 of
the women returned for testing after one year.
RESULTS: After one year, the subjects in both intervention groups had reached or
closely approached NCEP Step 1 dietary goals and reduced their mean body fat
significantly (range of reduction in mean fat weight, 4.0 to 7.8 kg). Weight
loss on the NCEP diet alone did not significantly change HDL cholesterol levels
in either the men or the women as compared with the subjects in the control
group. Plasma levels of HDL cholesterol increased significantly more in the men
who exercised and dieted (mean [+/- SE] change, +13 +/- 3 percent) than in the
men who only dieted (+2 +/- 3 percent, P less than 0.01) or the men who acted as
controls (-4 +/- 2 percent, P less than 0.001). HDL cholesterol levels remained
about the same in the women who exercised and dieted (+1 +/- 2 percent); they
were higher than in the women who only dieted (-10 +/- 3 percent, P less than
0.01), but not higher than in the controls (-3 +/- 3 percent).
CONCLUSIONS: Regular exercise in overweight men and women enhances the
improvement in plasma lipoprotein levels that results from the adoption of a
low-saturated-fat, low-cholesterol diet. Soluble-fiber breakfast cereals were examined for their cholesterol-lowering
ability in 58 male patients with mild to moderate hypercholesterolemia in a
randomized, double-blind, placebo-controlled study. Patients followed a step 1
diet for a minimum of 6 wk, then were randomly assigned to groups incorporating
either corn flakes or one of two soluble-fiber cereals (pectin enriched or
psyllium enriched) in the diet for an additional 6 wk. During the diet-only
phase, total cholesterol dropped 3.8%. During the cereal-plus-diet phase, total
and LDL cholesterol values of the pectin-enriched cereal group dropped an
additional 2.1% (P = 0.243) and 3.9% (P = 0.16), respectively, and they dropped
5.9% (P = 0.005) and 5.7% (P = 0.034), respectively, in the psyllium-enriched
cereal group. During the cereal-plus-diet phase, no significant effects on HDL
cholesterol, triglyceride, or body weight were found within or between any
cereal groups. These results support use of soluble-fiber cereals as an
effective and well-tolerated part of a prudent diet in the treatment of mild to
moderate hypercholesterolemia. To evaluate the effect on longevity of a diet that is concurrent with common
dietary guidelines, a simple diet scoring system was developed and applied in a
follow-up study of 2,820 middle-aged Dutch civil servants and their spouses. In
the early 1950s those civil servants were seen for a health examination that
included a dietary survey. Consumption frequency data of the quantitatively most
important food items at that time were used for the diet scoring. Overall
survival after 25 years was 46.8% among men and 68.6% among women. In men, a
significant positive association between prudent diet score and 25-year,
age-adjusted survival could be demonstrated. Of the 10 food items that
constituted the diet score, a higher intake of brown bread, porridge and/or
yogurt, vegetables, fish, and fruit was associated with a slightly better
survival. In a separate analysis we had found a significant inverse relationship
between coffee consumption and survival. A similar trend, which, however, was
not significant, was observed for alcohol intake. In women, the results for the
separate food items were inconsistent, and no effect of a prudent diet score on
longevity was observed. The proposed diet scoring system provides a means for
evaluating the effects of the individual's food choice behavior on subsequent
health and longevity. Risk factor status for cardiovascular disease is affected by life style.
Adolescence is a time during which long term life-style habits, including
dietary habits, are established. Physicians who treat adolescent patients have a
responsibility to be aware of the scientific evidence on the diet-heart question
so that they can provide their patients with sound dietary advice. The American
Heart Association has recommended that Americans consume a "prudent diet" in
which daily consumption of cholesterol is no more than 300 mg with up to 30-35%
of calories derived from fat, and less than 10% of calories derived from
saturated fat and less than 10% from polyunsaturated fat. This paper reviews
this recommendation with particular reference to studies of adolescents. This
review centers around four main issues: 1) the estimated effect on serum
cholesterol levels of a switch from the usual American diet to the prudent diet;
2) the effect of a predicted decrease in serum cholesterol on the risk of
developing cardiovascular disease; 3) evaluation of the evidence of possible
adverse effects of the prudent diet; 4) feasibility of the prudent diet. Based
on a review of these four issues, the authors feel that the American Heart
Association's prudent diet should be strongly recommended for all healthy
adolescents. The differential effect of two diets, taken in synchrony with the menstrual
cycles for 2 wk each, on serum and bile lipids was investigated in young healthy
women. The "normal" diet was high in cholesterol and total fat, and low in
polyunsaturated fat and fiber; the "prudent" diet contained a high proportion of
polyunsaturated fat and fiber, but was low in cholesterol and total fat; there
was little difference in energy content. Both in whole serum and in low-density
lipoprotein the concentrations of cholesterol and apolipoprotein B were almost
30% lower with the "prudent" than with the "normal" diet; HDL-cholesterol was
16.3% lower. Triglycerides were increased, only in the very-low-density
lipoproteins while cholesterol and apolipoprotein B did not change much in this
fraction. The risk to acquire cholesterol gallstones was not less with the use
of the "prudent" diet as originally expected. While using the "prudent" diet
five of the women had slightly higher lithogenic indices, in two there were much
higher values (greater than 25%), and only in three the lithogenic index was
unchanged or slightly lower than with the "normal" diet. "Product sampling" is an effective marketing strategy which lowers consumer
buying resistance by providing a free sample of the product for the consumer to
test. We used this strategy to demonstrate the palatability of the prudent diet
(30-35% of calories from total fats, less than 10% from saturated fats, less
than 3 g sodium, and increased fiber) to physicians attending a 5-day family
practice continuing medical education conference. The effect of the intervention
was evaluated with pre- and postintervention questionnaires and a 20% random
sample of participants was surveyed 1 year later. The proportion of physicians
who reported that they considered the diet to be "very palatable" rose from 26%
before the demonstration to 64% after the demonstration. Only 5% of the
physicians did not report a favorable response to the demonstration. Sixty-two
percent of the physicians reported that the diet was better than expected, and
82% reported that the demonstration encouraged them to recommend the diet to
their patients. One year after the intervention 60% considered the diet "very
palatable" and 55% reported that the demonstration stimulated them to increase
their dietary intervention activities. These data suggest that serving the
prudent diet at continuing medical education programs helps to remove prejudices
about the diet and encourages physicians to recommend the diet to their
patients. The effects of fruit and vegetables in conjunction with low-energy diet as
adjuncts to a prudent diet were compared for 6 months in a randomized, single
blind trial in the management of 202 group A and 204 group B patients with acute
myocardial infarction. Dietary intakes were obtained based on weighing of fruit,
vegetable and legume intake and weekly diet diaries. After 6 months of
follow-up, mean body weight, waist/hip ratio and glucose intolerance fell
significantly in patients in group A compared with those in group B. Body weight
declined by 5.3 kg in group A versus 2.2 kg in group B (95% confidence interval
of difference (CI) 1.28-4.92), waist/hip ratio decreased by 0.05 in group A and
0.02 in group B (95% CI 0.01-0.10), and glucose intolerance decreased by 0.85
mmol/l in group A versus 0.19 mmol/l in group B (95% CI 0.19-1.21). There was a
significant net decrease in serum triglycerides (0.18 mmol/l), systolic and
diastolic blood pressures (7.9/4.7 mmHg), and a net increase in high-density
lipoprotein cholesterol (0.10 mmol/l). Underlying these changes, group A
patients had 393 g/day net increase in the consumption of fruit and vegetables
and 1,160 kJ/day net decrease in energy intake compared to these changes in
groups. Those who made greater changes in diet also had greater improvements in
central obesity, glucose intolerance and in other associated disturbances. BACKGROUND: Although substantial information on individual nutrients or foods
and risk of coronary heart disease (CHD) is available, little is known about the
role of overall eating pattern.
METHODS: Using dietary information from a food frequency questionnaire in 1984
from the Nurses' Health Study, we conducted factor analysis and identified 2
major dietary patterns-"prudent" and "Western"-and calculated factor scores of
each pattern for individuals in the cohort. We used logistic regression to
examine prospectively the associations between dietary patterns and CHD risk
among 69 017 women aged 38 to 63 years in 1984 without history of major chronic
diseases.
RESULTS: The prudent pattern was characterized by higher intakes of fruits,
vegetables, legumes, fish, poultry, and whole grains, while the Western pattern
was characterized by higher intakes of red and processed meats, sweets and
desserts, french fries, and refined grains. Between 1984 and 1996, we documented
821 CHD cases. After adjusting for coronary risk factors, the prudent diet score
was associated with a relative risk (RR) of 0.76 (95% confidence interval (CI),
0.60-0.98; P for trend test,.03) comparing the highest with lowest quintile.
Extreme quintile comparison yielded an RR of 1.46 (95% CI, 1.07-1.99; P for
trend test,.02) for the Western pattern. Those who were jointly in the highest
prudent diet quintile and lowest Western diet quintile had an RR of 0.64 (95%
CI, 0.44-0.92) compared with those with the opposite pattern profile.
CONCLUSION: A diet high in fruits, vegetables, whole grains, legumes, poultry,
and fish and low in refined grains, potatoes, and red and processed meats may
lower risk of CHD. In this two-phase crossover study, 39 hypercholesterolemic subjects followed a
prudent diet with either lean red meat or fish and skinless chicken (treatment
groups), and 13 subjects (reference group) followed their habitual diet. Fasting
blood samples were analyzed for plasma total cholesterol, triacylglycerol (TAG),
high density lipoprotein cholesterol (HDL-C), low density lipoprotein one- and
two-cholesterol, apolipoprotein-B, very low density lipoprotein cholesterol, and
very low density lipoprotein TAG, and fatty acid composition of plasma TAG and
cholesteryl ester (CE). Body mass and blood pressure were determined. Seven-day
dietary records were kept once at baseline and twice during the treatment
periods. Significant differences were observed in dietary intake between the
baseline and treatment diets and between the two treatment diets. HDL-C (P <
0.05) and diastolic blood pressure (P < 0.01) were higher in patients on the red
meat diet than in those on the chicken-fish diet. No other significant
differences in lipoproteins were observed between the effects of the two
treatment diets. The linoleic acid (%), eicosapentaenoic acid (%), and the
eicosapentaenoic acid/arachidonic acid ratios in TAG and CE were higher (P <
0.01) in subjects on the chicken-fish diet than in those on the red meat diet.
In conclusion, this study showed that the effect of two lipid-lowering diets
containing either lean red meat or skinless chicken and fish on the atherogenic
lipoproteins did not differ significantly. A prudent diet with skinless chicken
and fish, however, had a more favorable effect on the fatty acid composition of
the plasma TAG and the CE than did the lean red meat diet. INTRODUCTION: Epidemiological studies have shown that dietary behaviour is an
important aetiological factor in various chronic diseases. We used principal
component factor analysis to identify dietary patterns and to examine the
associations of these patterns with health-related variables in a sample of
elderly (> or =60 years) Italians participating in the European Prospective
Investigation into Cancer and Nutrition (EPIC).
METHODS AND RESULTS: Exploratory factor analysis was applied to the intake of
food groups as estimated by semi-quantitative food questionnaires. Individual
participants were assigned factor scores, indicating the extent to which their
diet conformed to each of the four dietary patterns identified: prudent (cooked
vegetables, pulses, cabbage, seed oil and fish); pasta & meat (pasta, tomato
sauce, red meat, processed meat, bread and wine); olive oil & salad (raw
vegetables, olive oil, soup and chicken); and sweet & dairy (sugar, cakes, ice
cream, coffee and dairy). Highly educated people had high scores on prudent and
low scores on pasta & meat. The pasta & meat and prudent patterns were strongly
positively associated with body mass index (BMI) and waist-to-hip ratio (WHR) in
men and women. Hyperlipidaemic men and women consumed more of the prudent and
olive oil & salad patterns and less of the sweet & dairy pattern than those with
normal lipids. The olive oil & salad was significantly higher and the pasta &
meat and sweet & dairy patterns significantly lower in men and women who had
dieted over the previous year, suggesting awareness of the health consequences
of these patterns.
CONCLUSIONS: Dietary pattern analysis provides a characterization of recurrent
dietary behaviour in elderly people, and can be used to provide tangible dietary
advice to elderly people. BACKGROUND: Familial history of obesity (FHO) and certain dietary habits are
risk factors for obesity. The objectives of this cross-sectional study were 1)
to derive dietary patterns using factor analysis in a population of men and
women with and without FHO; 2) to compare mean factor scores for each dietary
pattern between individuals with and without FHO; and 3) to examine the
association between these patterns and anthropometric, lifestyle and
sociodemographic variables.
METHODS: A total of 197 women and 129 men with a body mass index <30 kg/m2 were
recruited. A positive FHO (FHO+) was defined as having at least one obese
first-degree relative and a negative FHO (FHO-) as no obese first-degree
relative. Dietary data were collected from a food frequency questionnaire.
Factor analysis was performed to derive dietary patterns. Mean factor scores
were compared using general linear model among men and women according to FHO.
Regression analyses were performed to study the relationship between
anthropometric, lifestyle and sociodemographic variables, and each dietary
pattern.
RESULTS: Two dietary patterns were identified in both men and women : the
Western pattern characterized by a higher consumption of red meats, poultry,
processed meats, refined grains as well as desserts, and the Prudent pattern
characterized by greater intakes of vegetables, fruits, non-hydrogenated fat,
and fish and seafood. Similar Western and Prudent factor scores were observed in
individual with and without FHO. In men with FHO+, the Western pattern is
negatively associated with age and positively associated with physical activity,
smoking, and personal income. In women with FHO-, the Prudent pattern is
negatively associated with BMI and smoking and these pattern is positively
associated with age and physical activity.
CONCLUSION: Two dietary patterns have been identified among men and women with
and without FHO. Although that FHO does not seem to influence the adherence to
dietary patterns, results of this study suggest that anthropometric, lifestyle
and sociodemographic variables associated with dietary patterns differ according
to FHO and gender. OBJECTIVE: To evaluate the impact of combinations of lifestyle factors on
mortality in middle aged women.
DESIGN: Prospective cohort study.
SETTING: Nurses' health study, United States.
PARTICIPANTS: 77 782 women aged 34 to 59 years and free from cardiovascular
disease and cancer in 1980.
MAIN OUTCOME MEASURE: Relative risk of mortality during 24 years of follow-up in
relation to five lifestyle factors (cigarette smoking, being overweight, taking
little moderate to vigorous physical activity, no light to moderate alcohol
intake, and low diet quality score).
RESULTS: 8882 deaths were documented, including 1790 from cardiovascular disease
and 4527 from cancer. Each lifestyle factor independently and significantly
predicted mortality. Relative risks for five compared with zero lifestyle risk
factors were 3.26 (95% confidence interval 2.45 to 4.34) for cancer mortality,
8.17 (4.96 to 13.47) for cardiovascular mortality, and 4.31 (3.51 to 5.31) for
all cause mortality. A total of 28% (25% to 31%) of deaths during follow-up
could be attributed to smoking and 55% (47% to 62%) to the combination of
smoking, being overweight, lack of physical activity, and a low diet quality.
Additionally considering alcohol intake did not substantially change this
estimate.
CONCLUSIONS: These results indicate that adherence to lifestyle guidelines is
associated with markedly lower mortality in middle aged women. Both efforts to
eradicate cigarette smoking and those to stimulate regular physical activity and
a healthy diet should be intensified. OBJECTIVE: Dietary habits have been associated with the prevalence of the
metabolic syndrome and limited data are available in this field for individuals
with impaired glucose tolerance. This study focused on the association between
major dietary patterns and prevalence of the metabolic syndrome in individuals
with impaired glucose tolerance.
METHODS: This cross-sectional study was done in 425 subjects 35 to 55 y of age.
Dietary data were collected using a food-frequency questionnaire. Blood
pressure, waist circumference, glucose, triacylglycerols, and high-density
lipoprotein cholesterol were measured and metabolic syndrome was defined based
on Adult Treatment Panel III guidelines.
RESULTS: Five major dietary patterns were found: a western pattern (high in
sweets, butter, soda, mayonnaise, sugar, cookies, tail of a lamb, hydrogenated
fat, and eggs), a prudent pattern (high in fish, peas, honey, nuts, juice, dry
fruits, vegetable oil, liver and organic meat, and coconuts and low in
hydrogenated fat and non-leafy vegetables), a vegetarian pattern (high in
potatoes, legumes, fruits rich in vitamin C, rice, green leafy vegetables, and
fruits rich in vitamin A), a high-fat dairy pattern (high in high-fat yogurt and
high-fat milk and low in low-fat yogurt, peas, and bread), and a chicken and
plant pattern (high in chicken, fruits rich in vitamin A, green leafy
vegetables, and mayonnaise and low in beef, liver, and organic meat). After
adjusting for confounding variables, the western pattern was associated with
greater odds of having increased triacylglycerol (odds ratio 1.76, 95%
confidence interval 1.01-3.07) and blood pressure (odds ratio 2.62, 95%
confidence interval 1.32-5.23). The prudent pattern was positively associated
with a prevalence of low high-density lipoprotein cholesterol levels (odds ratio
0.55, 95% confidence interval 0.31-0.96). The vegetarian dietary pattern was
inversely associated with a risk of an abnormal fasting blood glucose level
(odds ratio 2.26, 95% confidence interval 1.25-4.06).
CONCLUSION: Major dietary patterns were significantly associated with the risk
of metabolic syndrome. BACKGROUND: Studies addressing the effects of aerobic exercise and a prudent
diet on lipid and lipoprotein concentrations in adults have reached conflicting
conclusions. The purpose of this study was to determine the effects of aerobic
exercise combined with a prudent diet on lipid and lipoprotein concentrations in
adults.
METHODS: Studies were located by searching nine electronic databases,
cross-referencing, and expert review. Two independent reviewers selected studies
that met the following criteria: (1) randomized controlled trials, (2) aerobic
exercise combined with diet recommendations (saturated/trans fat intake less
than 10% of total calories and cholesterol less than 300 mg/day and/or fiber
intake ≥ 25 g/day in women and ≥ 35 grams per day in men), (3) intervention ≥ 4
weeks, (4) humans ≥ 18 years of age, (5) published studies, including
dissertations and Master's theses, (6) studies published in any language, (7)
studies published between January 1, 1955 and May 1, 2009, (8) assessment of one
or more of the following lipid and lipoprotein concentrations: total cholesterol
(TC), high-density lipoprotein cholesterol (HDL-C), ratio of TC to HDL-C,
non-HDL-C, low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG).
Two reviewers independently extracted all data. Random-effects models that
account for heterogeneity and 95% confidence intervals were used to pool
findings.
RESULTS: Of the 1,401 citations reviewed, six studies representing 16 groups (8
intervention, 8 control) and up to 559 men and women (282 intervention, 277
control) met the criteria for analysis. Statistically significant intervention
minus control reductions were found for TC (-15.5 mg/dl, 95% CI, -20.3 to
-10.7), TC:HDL-C (-0.4 mg/dl, 95% CI, -0.7 to -0.2), LDL-C (-9.2 mg/dl, 95% CI,
-12.7 to -5.8) and TG (-10.6 mg/dl, 95% CI, -17.2 to -4.0) but not HDL-C (-0.5
mg/dl, 95% CI, -4.0 to 3.1). Changes were equivalent to reductions of 7.5%,
6.6%, 7.2% and 18.2% respectively, for TC, TC:HDL-C, LDL-C and TG. Because of
missing variance statistics, non-HDL-C was excluded.
CONCLUSIONS: Aerobic exercise combined with a prudent diet is highly efficacious
for improving TC, TC:HDL-C, LDL-C and TG, but not HDL-C concentrations, in
adults. However, additional studies are needed, including effectiveness studies
using intention-to-treat analysis. We aimed to evaluate the effect of the Mediterranean diet (MD) compared with a
prudent diet (PD) combined with physical activity on obese obstructive sleep
apnoea syndrome (OSAS) patients who were treated with continuous positive airway
pressure. 900 patients were evaluated and 40 obese patients (body mass index ≥
30.0 kg · m(-2)) who met the inclusion criteria, with moderate-to-severe OSAS
(apnoea-hypopnoea index (AHI) >15 events · h(-1) and Epworth Sleepiness Scale
score >10) based on overnight attended polysomnography, were included in the
study. After randomisation, 20 patients followed the MD and 20 a PD for a
6-month period. All patients were counselled to increase their physical
activity. Concerning sleep parameters, only AHI during rapid eye movement (REM)
sleep was reduced to a statistically significant degree, by mean ± SD 18.4 ±
17.6 events · h(-1) in the MD group and by 2.6 ± 23.7 events · h(-1) in the PD
group (p<0.05). The MD group also showed a greater reduction in waist
circumference (WC) (-8.7 ± 3.6 cm), WC/height ratio (-0.04 ± 0.02 cm · m(-1))
and WC/hip ratio (-0.04 ± 0.03 cm · cm(-1)), compared with the other group (-2.6
± 1.7 events · h(-1), -5.7 ± 3.8 cm, -0.03 ± 0.02 cm · m(-1) and 0.02 ± 0.02 cm
· cm(-1), respectively; p<0.05). Our results showed that the MD combined with
physical activity for a 6-month period was effective in reducing the AHI during
REM sleep without any statistically significant effect in the other sleep
parameters, compared with a PD in obese adults with moderate-to-severe OSAS. OBJECTIVE: To review the epidemiological evidence for vegetarian diets, low-meat
dietary patterns and their association with health status in adults.
DESIGN: Published literature review focusing primarily on prospective studies
and meta-analyses examining the association between vegetarian diets and health
outcomes.
RESULTS: Both vegetarian diets and prudent diets allowing small amounts of red
meat are associated with reduced risk of diseases, particularly CHD and type 2
diabetes. There is limited evidence of an association between vegetarian diets
and cancer prevention. Evidence linking red meat intake, particularly processed
meat, and increased risk of CHD, cancer and type 2 diabetes is convincing and
provides indirect support for consumption of a plant-based diet.
CONCLUSIONS: The health benefits of vegetarian diets are not unique. Prudent
plant-based dietary patterns which also allow small intakes of red meat, fish
and dairy products have demonstrated significant improvements in health status
as well. At this time an optimal dietary intake for health status is unknown.
Plant-based diets contain a host of food and nutrients known to have independent
health benefits. While vegetarian diets have not shown any adverse effects on
health, restrictive and monotonous vegetarian diets may result in nutrient
deficiencies with deleterious effects on health. For this reason, appropriate
advice is important to ensure a vegetarian diet is nutritionally adequate
especially for vulnerable groups. Stroke is the fourth leading cause of mortality in the United States, yet it is
80% preventable by addressing lifestyle factors including nutrition. Evaluating
the impact of nutrition at the food group and dietary pattern level will provide
greater insight into the role of nutrition in stroke. For this purpose, a review
of the literature was conducted using the PubMed, Web of Science, and CINAHL
Plus online databases. While fruits, vegetables, and soy demonstrated a
protective effect, variable findings were observed for fish, animal products,
and whole grains. Adherence to DASH, Mediterranean, and prudent dietary patterns
reduced the risk of stroke, whereas the Western dietary pattern was associated
with increased stroke risk. Low-fat diet was not found to have a protective
effect. Additional epidemiological evidence is needed to elucidate the impact of
specific dietary patterns and food groups on stroke. Future research should
consider developing dietary recommendations for stroke prevention, which are
based on clinical trials and have an emphasis on food groups and dietary
patterns that are palatable to the general public. BACKGROUND: Diet regulates gene expression profiles by several mechanisms. The
objective of this study was to examine gene expression in relation with dietary
patterns.
METHODS: Two hundred and fifty four participants from the greater Quebec City
metropolitan area were recruited. Two hundred and ten participants completed the
study protocol. Dietary patterns were derived from a food frequency
questionnaire (FFQ) by factor analysis. For 30 participants (in fasting state),
RNA was extracted from peripheral blood mononuclear cells (PBMCs) and expression
levels of 47,231 mRNA transcripts were assessed using the Illumina Human-6 v3
Expression BeadChips®. Microarray data was pre-processed with Flexarray software
and analysed with Ingenuity Pathway Analysis (IPA).
RESULTS: Two dietary patterns were identified. The Prudent dietary pattern was
characterised by high intakes of vegetables, fruits, whole grain products and
low intakes of refined grain products and the Western dietary pattern, by high
intakes of refined grain products, desserts, sweets and processed meats. When
individuals with high scores for the Prudent dietary pattern where compared to
individuals with low scores, 2,083 transcripts were differentially expressed in
men, 1,136 transcripts in women and 59 transcripts were overlapping in men and
women. For the Western dietary pattern, 1,021 transcripts were differentially
expressed in men with high versus low scores, 1,163 transcripts in women and 23
transcripts were overlapping in men and women. IPA reveals that genes
differentially expressed for both patterns were present in networks related to
the immune and/or inflammatory response, cancer and cardiovascular diseases.
CONCLUSION: Gene expression profiles were different according to dietary
patterns, which probably modulate the risk of chronic diseases.
TRIAL REGISTRATION: NCT: NCT01343342. BACKGROUND: Declines in gastric cancer (GC) incidence and mortality have been
related to improvements in diet. It is therefore important to consider dietary
patterns.
DESIGN: We conducted a systematic review and meta-analysis of the literature
through Medline and Embase databases.
RESULTS: We identified 16 papers, of these 9 derived dietary patterns through an
a posteriori method, 5 through a priori scores, and 2 used both approaches.
Eight studies that used the a posteriori approach were considered for the
meta-analysis. A favorable role on GC emerged for the 'Prudent/healthy', with an
odds ratio (OR) of 0.75 [95% confidence interval (CI): 0.63-0.90], for the
highest versus the lowest category. Similar results emerged for separate
anatomical subtypes. An unfavorable role on GC emerged for the
'Western/unhealthy' dietary pattern, with an OR of 1.51 (95% CI: 1.21-1.89).
This association was weaker for the distal/NOS (not otherwise specified)
category (OR = 1.36) compared with the cardia GC (OR = 2.05). Among the a priori
scores, the ORs ranged from 0.2 to 0.7 for the favorable and from 1.8 to 6.9 for
the unfavorable ones.
CONCLUSION: There is a ~2-fold difference in GC risk between a 'Prudent/healthy'
diet-rich in fruits and vegetables, and a 'Western/unhealthy' diet-rich in
starchy foods, meat and fats. In the time period 1996-2004, we conducted a case-control study in Montevideo,
Uruguay with the objective of exploring the role of foods and alcoholic
beverages in the etiology of cancers of the upper aerodigestive tract (UADT). In
brief, 563 male cases and 1099 male controls were frequency matched on age and
residence using random sampling. All the participants were drawn from the 4
major public hospitals in Montevideo. We used exploratory factor analysis among
controls. Through Scree plot test, the model retained 4 factors, which were
labeled as prudent, starchy plants, Western, and drinker. These dietary patterns
explained 34.8% of the total variance. Whereas the prudent pattern was inversely
associated with UADT cancer [odds ratios (OR) for the upper tertile vs. the
lowest one 0.52, 95% confidence intervals 0.32-0.76, P value for trend =
0.0005), the remaining patterns were significantly and positively associated
with UADT cancers. We conclude that these patterns were similar among the oral
and laryngeal cancers, both in the direction of the ORs and in the magnitude of
the associations, suggesting that these cancer sites share the effect of dietary
patterns in the etiology of cancer of the upper aerodigestive tract. Studying empirically derived dietary patterns is useful in understanding dietary
practice. We classified women by their dietary patterns using latent class
analysis of 66 foods and studied the association of these patterns with neural
tube defects (NTDs) and congenital heart defects (CHDs) in the U.S. National
Birth Defects Prevention Study (1997-2005). Logistic regression models used data
from 1,047 with an NTD, 6,641 with a CHD, and 6,123 controls that were adjusted
for maternal characteristics and tested the effect modification of multivitamin
supplement use. Four latent dietary patterns were identified: prudent, Western,
low-calorie Western, and Mexican. Among participants who did not use
supplements, those in the Mexican, Western, and low-calorie Western classes were
significantly more likely (odds ratios of 1.6, 1.5, and 1.4, respectively) to
have offspring born with NTDs than were those in the prudent class after
adjustment of for dietary folic acid intake. In contrast, among supplement
users, there was no difference in the incidence of NTDs between classes.
Associations between dietary class and CHD subgroups were not modified by
supplement use except for tetralogy of Fallot; among supplement users, those in
the Western class were twice as likely (95% confidence interval: 1.4, 2.8) as
the prudent class to have offspring with tetralogy of Fallot. Women who adhered
to a Western diet were 1.2 (95% confidence interval: 1.03, 1.35) times more
likely to have an infant with septal heart defect than were women who adhered to
a prudent diet. A prudent dietary pattern, even with folate fortification, may
decrease the risk of NTDs and some heart defects. Comment on
Microbiological profile and nutritional quality of raw foods for neutropenic
patients under hospital care. :94–98. BACKGROUND: Although individual nutrients have been investigated in relation to
depression risk, little is known about the overall role of diet in depression.
OBJECTIVE: We examined whether long-term dietary patterns derived from a
food-frequency questionnaire (FFQ) predict the development of depression in
middle-aged and older women.
DESIGN: We conducted a prospective study in 50,605 participants (age range:
50-77 y) without depression in the Nurses' Health Study at baseline (1996) who
were followed until 2008. Long-term diet was assessed by using FFQs every 4 y
since 1986. Prudent (high in vegetables) and Western (high in meats) patterns
were identified by using a principal component analysis. We used 2 definitions
for clinical depression as follows: a strict definition that required both a
reported clinical diagnosis and use of antidepressants (3002 incident cases) and
a broad definition that further included women who reported either a clinical
diagnosis or antidepressant use (7413 incident cases).
RESULTS: After adjustment for age, body mass index, and other potential
confounders, no significant association was shown between the diet patterns and
depression risk under the strict definition. Under the broad definition, women
with the highest scores for the Western pattern had 15% higher risk of
depression (95% CI: 1.04, 1.27; P-trend = 0.01) than did women with the lowest
scores, but after additional adjustment for psychological scores at baseline,
results were no longer significant (RR: 1.09; 95% CI: 0.99, 1.21; P-trend =
0.08).
CONCLUSION: Overall, results of this large prospective study do not support a
clear association between dietary patterns from factor analysis and depression
risk. BACKGROUND: During the year after the Great East Japan Earthquake on March 11,
2011, the health conditions and lifestyles of survivors were extensively
surveyed. We examined the relationship between living conditions and dietary
pattern among survivors.
METHODS: A total of 10 466 survivors aged 18 years or older (25% of the
population of that age in the area) participated in a survey of Iwate
Prefecture. The average frequency of daily consumption of 8 food groups was
determined by questionnaire. After excluding staple foods, which were consumed 3
times a day by 85% of participants, factor analysis was performed on 7 food
groups among 9789 people (3795 men, 5994 women).
RESULTS: Factor analysis identified 2 dietary patterns-prudent and meat. The
prudent dietary pattern is characterized by high intakes of fish and shellfish,
soybean products, vegetables, fruit, and dairy products and was more evident
among older participants and women. The meat dietary pattern is characterized by
high intakes of meat and eggs and was more evident among younger participants
and men. Age-adjusted multiple logistic regression analyses showed that male and
female current smokers and men and women living in difficult conditions were
likely to have a lower prudent dietary pattern score; male current smokers and
male daily alcohol drinkers were likely to have a higher meat dietary pattern
score.
CONCLUSIONS: During the year after the earthquake, the prudent dietary pattern
was associated with better living conditions among survivors, whereas the meat
dietary pattern was not. |
What is the role of necroptosis in cancer therapy? | Necroptosis, a novel form of programmed cell death (PCD), is caspase independent but RIPK and RIPK3 dependent. The apoptotic, autophagic and necroptotic pathways of PCD were shown to be interconnected, with molecules such as FLIP acting as a bridge between them. Therefore, simultaneous activation of the three PCD pathways would make cancer therapy more effective, whereas induction of necroptosis could be an alternative, in cases where apoptosis-inducing cancer chemotherapy is not effective. For example, inhibition of GSK3B was found to bypass drug resistance of p53-null colon carcinomas by enabling necroptosis in response to 5-FU treatment. | Cancerous growth is one of the most difficult diseases to target as there is no
one clear cause, and targeting only one pathway does not generally produce
quantifiable improvement. For a truly effective cancer therapy, multiple
pathways must be targeted at the same time. One way to do this is to find a gene
that is associated with several pathways; this approach expands the
possibilities for disease targeting and enables multiple points of attack rather
than one fixed point, which does not allow treatment to evolve over time as
cancer does. Inducing programmed cell death (PCD) is a promising method to
prevent or inhibit the progression of tumor cells. Intricate cross talk among
various programmed cell death pathways including cell death by apoptosis,
necroptosis or autophagy plays a critical role in the regulation of PCD. In
addition, the complex and overlapping patterns of signaling and lack of
understanding of such networks between these pathways generate hurdles for
developing effective therapeutic approaches. This review article focuses on
targeting FLIP (Fas-associated death domain-like interleukin-1-converting
enzyme-like inhibitory protein) signaling as a bridge between various PCD
processes as an effective approach for cancer management. PURPOSE: Evasion from chemotherapy-induced apoptosis due to p53 loss strongly
contributes to drug resistance. Identification of specific targets for the
treatment of drug-resistant p53-null tumors would therefore increase the
effectiveness of cancer therapy.
EXPERIMENTAL DESIGN: By using a kinase-directed short hairpin RNA library and
HCT116p53KO drug-resistant colon carcinoma cells, glycogen synthase kinase 3
beta (GSK3B) was identified as a target whose silencing bypasses drug resistance
due to loss of p53. p53-null colon cancer cell lines with different sets of
mutations were used to validate the role of GSK3B in sustaining resistance and
to characterize cell death mechanisms triggered by chemotherapy when GSK3B is
silenced. In vivo xenograft studies were conducted to confirm resensitization of
drug-resistant cells to chemotherapy upon GSK3 inhibition. Colon cancer samples
from a cohort of 50 chemotherapy-treated stage II patients were analyzed for
active GSK3B expression.
RESULTS: Downregulation of GSK3B in various drug-resistant p53-null colon cancer
cell lines abolished cell viability and colony growth after drug addition
without affecting cell proliferation or cell cycle in untreated cells. Cell
death of 5-fluorouracil (5FU)-treated p53-null GSK3B-silenced colon carcinoma
cells occurred via PARP1-dependent and AIF-mediated but RIP1-independent
necroptosis. In vivo studies showed that drug-resistant xenograft tumor mass was
significantly reduced only when 5FU was given after GSK3B inhibition. Tissue
microarray analysis of colon carcinoma samples from 5FU-treated patients
revealed that GSK3B is significantly more activated in drug-resistant versus
responsive patients.
CONCLUSIONS: Targeting GSK3B, in combination with chemotherapy, may represent a
novel strategy for the treatment of chemotherapy-resistant tumors. Programmed cell death plays an important role in animal development, tissue
homeostasis and eliminating harmful or virally infected cells. Necroptosis, a
novel form of programmed cell death, is caspase independent but RIPK and RIPK3
dependent. Moreover, it is suggested that necroptosis can be specifically
inhibited by small molecular inhibitors such as necrostatin-1. Its signaling
pathways have something in common with apoptosis, although the molecular
mechanisms of necroptosis need to be further elucidated. Previous evidences
suggest that necroptosis has significant effects in regulating various
physiological processes and disease, such as ischemic brain injury, immune
system disorders and cancer. In this review, the molecular mechanism of
necroptosis is described and how it could be manipulated in the treatment of
cancer is summarized. |
Can venlafaxine block NET and SERT? | Yes, venlafaxine inhibits both the NET and SERT. | Venlafaxine hydrochloride (Effexor) is a structurally novel antidepressant that
inhibits reuptake of 5-hydroxytryptamine and noradrenaline, but unlike the older
antidepressants, has few side-effects. The objective of this study was to
determine whether venlafaxine relieves thermal hyperalgesia in rats with
neuropathic pain due to chronic constriction injury (CCI) of the sciatic nerve.
Paw withdrawal latency (PWL) to heat was tested for each hind paw. A painful
neuropathy was induced in 24 male Sprague-Dawley rats (Group 1) as described by
Bennett and Xie. Rats randomly received either oral venlafaxine (22 mg/kg) or
placebo via gavage feeding beginning the day after surgery. Postoperative PWL
testing began 3 days after CCI (Time 0). A second group of 12 rats (Group 2) was
used to confirm that venlafaxine reverses hyperalgesia in rats with a fully
developed neuropathic lesion. These animals began to receive oral venlafaxine
(22 mg/kg) starting on the third postoperative day, after the presence of
thermal hyperalgesia was verified through PWL testing. Testing was continued for
5 days, during venlafaxine administration. A third group of 12 rats (Group 3)
had activity measured before and after treatment with venlafaxine (22 mg/kg).
Rats in the placebo group developed thermal hyperalgesia while those that
received venlafaxine did not. Venlafaxine also appeared to have a mild
non-specific analgesic effect that increased PWL in the sham limb. In Group 2,
thermal hyperalgesia was present on day 3, but following treatment with
venlafaxine, thermal hyperalgesia resolved. Activity measurements confirmed that
venlafaxine was not sedating in this rat model. Venlafaxine is a newly introduced antidepressant agent. The drug causes
selective inhibition of neuronal reuptake of serotonine and norepinephrine with
little effect on other neurotransmitter systems. Cases of seizures, tachycardia,
and QRS prolongation have been observed following drug overdose in humans. The
clinical manifestations of cardiac toxicity suggest that venlafaxine may exhibit
cardiac electrophysiological effects on fast conducting cells. Consequently,
studies were undertaken to characterize effects of venlafaxine on the fast
inward sodium current (I(Na)) of isolated guinea pig ventricular myocytes.
Currents were recorded with the whole-cell configuration of the patch-clamp
technique in the presence of Ca(2+) and K(+) channel blockers. Results obtained
demonstrated that venlafaxine inhibits peak I(Na) in a concentration-dependent
manner with an estimated IC(50) of 8. 10(-6) M. Inhibition was exclusively of a
tonic nature and rate-independent. Neither kinetics of inactivation (tau(inac)=
0.652 +/- 0.020 ms, under control conditions; tau(inac)= 0.636 +/- 0.050, in the
presence of 10(-5) M venlafaxine; n = 5 cells isolated from five animals) nor
kinetics of recovery from inactivation of the sodium channels (tau(re)= 58.7 +/-
1.6 ms, under control conditions; tau(re)= 54.4 +/- 1.8, in the presence of
10(-5) M venlafaxine; n = 10 cells isolated from six animals) were significantly
altered by 10(-5) M venlafaxine. These observations led us to conclude that
venlafaxine blocks I(Na) following its binding to the resting state of the
channel. Thus, the characteristics of block of I(Na) by venlafaxine are
different from those usually observed with most tricyclic antidepressants or
conventional class I antiarrhythmic drugs. The effect of a 21-day treatment with the dual 5-HT and NE reuptake blocker
venlafaxine (delivered s.c. by osmotic minipumps) was assessed on the time
required for a 50% recovery (RT(50)) of the firing activity of dorsal
hippocampus CA(3) pyramidal neurons from the suppression induced by
microiontophoretic applications of 5-HT and NE. The RT(50) values for 5-HT were
increased by both 10 and 40 mg/kg/day regimens of venlafaxine, whereas those for
NE were increased only by the 40 mg/kg/day regimen, indicative of a greater
potency of venlafaxine in blocking 5-HT reuptake. The sensitivity of the
postsynaptic 5-HT(1A) and alpha(2)-adrenergic receptors was altered by neither
regimen of venlafaxine. Using a paradigm by which the 5-HT(1A) antagonist WAY
100635 can induce a disinhibition of firing activity of CA(3) pyramidal neurons,
it was demonstrated that the high, but not the low, dose of venlafaxine led to
an enhanced tonic activation of postsynaptic 5-HT(1A) receptors in the dorsal
hippocampus. The duration of the suppressant effect of the firing activity of
CA(3) hippocampus pyramidal neurons produced by the electrical stimulation of
the ascending 5-HT pathway was significantly reduced when the frequency of the
stimulation was enhanced from 1 Hz to 5 Hz in control rats and in rats treated
with 10 mg/kg/day, but not with 40 mg/kg/day of venlafaxine. Hence, venlafaxine
induced a desensitization of the terminal 5-HT(1B) autoreceptor only at the high
dose. A 2-day treatment with 10 mg/kg/day of venlafaxine induced a suppression
of the firing activity of 5-HT neurons of the dorsal raphe. The firing activity
of these neurons was back to control level in rats that had been treated for 21
days with the same dose of venlafaxine. The suppressant effect of the i.v.
administration of the 5-HT autoreceptor agonist LSD on the firing activity of
dorsal raphe 5-HT neurons was reduced in rats that had been treated for 21 days
with 10 mg/kg/day of venlafaxine. A 2-day treatment with 40 mg/kg/day of
venlafaxine, unlike the 10 mg/kg/day regimen, induced a marked suppression of
the firing activity of locus coeruleus NE neurons. However, in contrast to 5-HT
neurons, NE neurons did not recover their firing activity after a 21-day
treatment. Taken together, the results from this study indicate that the low
dose of venlafaxine blocked selectively the reuptake of 5-HT, whereas the high
dose blocked the reuptake of both 5-HT and NE. Moreover, an enhancement of
serotonergic neurotransmission by venlafaxine was only achieved under conditions
whereby the desensitization of the terminal 5-HT(1B) autoreceptor is appended to
that of the somatodendritic 5-HT(1A) receptor. S33005 displayed marked affinity for native, rat, and cloned human serotonin
(5-HT) transporters (SERT) and less pronounced affinity for norepinephrine (NE)
transporters (NET), while its affinity at dopamine (DA) transporters and >50
other sites was negligible. Reuptake of 5-HT and (less potently) NE into
cerebral synaptosomes was inhibited by S33005, whereas DA reuptake was little
affected. In vivo, S33005 prevented depletion of cerebral pools of 5-HT by
parachloroamphetamine. Furthermore, it decreased electrical activity of
raphe-localized serotonergic neurones, an action abolished by the 5-HT1A
antagonist WAY100,635. At higher doses, S33005 blocked firing of locus
ceruleus-localized adrenergic neurones, an action abolished by the
alpha2-adrenergic antagonist idazoxan. In contrast, S33005 did not inhibit
ventrotegmental dopaminergic neurones. In frontal cortex of freely moving rats,
S33005 dose dependently elevated dialysate levels of 5-HT, NE, and DA. In
hippocampus, levels of 5-HT and NE were similarly elevated, while in nucleus
accumbens and striatum, levels of 5-HT were increased whereas DA was unaffected.
Upon chronic (2 weeks) administration, basal levels of NE were elevated in
frontal cortex and, therein, 5-HT2A receptor density was decreased. Comparative
studies with clinically used antidepressants showed that venlafaxine possessed a
profile similar to S33005 but was less potent. Clomipramine likewise interacted
with SERTs and NETs but also with several other receptors types, while
citalopram and reboxetine were preferential ligands of SERTs and NETs,
respectively. In conclusion, S33005 interacts potently with SERTs and, less
markedly, with NETs. It enhances extracellular levels of 5-HT and NE throughout
corticolimbic structures and selectively elevates dialysis levels of DA in
frontal cortex versus subcortical regions. Weight-restored patients with anorexia nervosa (AN) respond favorably to the
selective serotonin reuptake inhibitor fluoxetine, which justifies association
studies of the serotonin transporter gene (SLC6A4, alias SERT) and AN.
Case-control studies suggest that the least transcriptionally active allele of
the SERT gene promoter polymorphism (5-HTTLPR) has an increased frequency in AN
patients. However, this finding was not replicated with 55 trios (AN
child+parents) and the transmission disequilibrium test (TDT). To clarify the
role of the 5-HTTLPR in susceptibility to AN, we used the TDT and 106 Australian
trios to provide 93% power to detect a genotypic relative risk (GRR) of 2.0. Our
results were negative for this GRR (McNemar's chi(2)=0.01, df=1, p=0.921, odds
ratio 1.0, 95% CI 0.7-1.5). Additionally, we found no association with AN
females, AN subtype, age at onset, or minimum BMI. We then performed the first
reported investigation of epistasis between the SERT gene and norepinephrine
transporter gene (SLC6A2, alias NET) in AN, as an earlier study suggested that
atypical AN responds to the dual serotonin-norepinephrine reuptake inhibitor
venlafaxine. We observed no epistasis between the 5-HTTLPR and a polymorphism
within the NET gene promoter polymorphic region (NETpPR) (chi(2)=0.48, df=1,
p=0.490). Although 5-HTTLPR modulates serotonin reuptake by the serotonin
transporter, our analyses provide no evidence that susceptibility to AN is
modified by 5-HTTLPR alone, nor in concert with as yet undetermined functional
effects of the NETpPR polymorphism. BACKGROUND: Venlafaxine blocks both serotonin and norepinephrine transporters
(SERT and NET), with higher affinity for SERT. Serotonergic effects occur with
lower doses, whereas both serotonergic and noradrenergic effects occur with
higher doses of venlafaxine. Chronic treatment of rats with selective serotonin
reuptake inhibitors decreases SERT binding sites, whereas similar treatment with
selective norepinephrine reuptake inhibitors decreases NET binding sites. We
hypothesized that venlafaxine would affect monoamine transporters
dose-dependently, with low doses causing selective reduction of SERT binding
sites and higher doses reducing both SERT and NET binding sites.
METHODS: Rats were treated for 21 days with a low (15 mg/kg/day) or high (70
mg/kg/day) dose of venlafaxine, vehicle, or other antidepressants. The SERT and
NET density was determined by quantitative autoradiography.
RESULTS: Neither dose of venlafaxine nor amitriptyline reduced binding to either
the SERT or NET. In rats with noradrenergic terminals destroyed by
6-hydroxydopamine, venlafaxine still failed to reduce SERT binding. Also, rats
treated simultaneously with sertraline plus desipramine exhibited reductions in
both SERT and NET binding.
CONCLUSIONS: Chronic venlafaxine treatment affected SERT and NET binding
differently from paroxetine or desipramine. The inability of venlafaxine to
reduce SERT or NET binding sites is not due to its dual uptake inhibiting
properties. Paroxetine and venlafaxine are potent serotonin transporter (SERT) antagonists
and weaker norepinephrine transporter (NET) antagonists. However, the relative
magnitude of effect at each of these sites during treatment is unknown. Using a
novel blood assay that estimates CNS transporter occupancy we estimated the
relative SERT and NET occupancy of paroxetine and venlafaxine in human subjects
to assess the relative magnitude of SERT and NET inhibition. Outpatient subjects
(N=86) meeting criteria for major depression were enrolled in a multicenter, 8
week, randomized, double-blind, parallel group, antidepressant treatment study.
Subjects were treated by forced-titration of paroxetine CR (12.5-75 mg/day) or
venlafaxine XR (75-375 mg/day) over 8 weeks. Blood samples were collected weekly
to estimate transporter inhibition. Both medications produced dose-dependent
inhibition of the SERT and NET. Maximal SERT inhibition at week 8 for paroxetine
and venlafaxine was 90% (SD 7) and 85% (SD 10), respectively. Maximal NET
inhibition for paroxetine and venlafaxine at week 8 was 36% (SD 19) and 60% (SD
13), respectively. The adjusted mean change from baseline (mean 28.6) at week 8
LOCF in MADRS total score was -16.7 (SE 8.59) and -17.3 (SE 8.99) for the
paroxetine and venlafaxine-treated patients, respectively. The magnitudes of the
antidepressant effects were not significantly different from each other (95%CI
-3.42, 4.54, p=0.784). The results clearly demonstrate that paroxetine and
venlafaxine are potent SERT antagonists and less potent NET antagonists in vivo.
NET antagonism has been posited to contribute to the antidepressant effects of
these compounds. The clinical significance of the magnitude of NET antagonism by
both medications remains unclear at present. The goal of this study was to develop and validate ex vivo binding assays for
serotonin (SERT), norepinephrine (NET) and dopamine (DAT) transporters, and to
use these assays to evaluate the binding site occupancy of triple and double
monoamine reuptake inhibitors in rat brains. This study demonstrated that while
autoradiographic methods provided anatomic precision and regional resolution,
the homogenate binding method for site occupancy assessment yielded comparable
sensitivity with markedly improved throughput. For ex vivo binding assays, the
reduction of temperature and time during the in vitro process (primarily
incubation with a radioligand) markedly decreased the dissociation of test
agents from binding sites in brain tissues. This reduction, in turn, minimized
the potential for underestimation of site occupancy in vivo especially for test
compounds with affinity >10nM. The ratios of measured occupancy ED(50) values
(doses at which 50% occupancy occurs) among SERT, NET and DAT sites for
duloxetine, venlafaxine, nomifensine, indatraline, DOV 21,947 and DOV 216,303
were consistent with the ratios of the in vitro affinities between these target
binding sites. The biological relevance of the monoamine transporter occupancy
for these compounds is discussed. Previous work has shown that repeated desipramine treatment causes
downregulation of the norepinephrine transporter (NET) and persistent
antidepressant-like effects on behavior, ie effects observed 2 days after
discontinuation of drug treatment when acute effects are minimized. The present
study examined whether this mechanism generalizes to other antidepressants and
also is evident for the serotonin transporter (SERT). Treatment of rats for 14
days with 20 mg/kg per day protriptyline or 7.5 mg/kg per day sertraline reduced
NET and SERT expression, respectively, in cerebral cortex and hippocampus; these
treatments also induced a persistent antidepressant-like effect on forced-swim
behavior. Increased serotonergic neurotransmission likely mediated the
behavioral effect of sertraline, as it was blocked by inhibition of serotonin
synthesis with p-chlorophenylalanine; a parallel effect was observed previously
for desipramine and noradrenergic neurotransmission. Treatment with 20 mg/kg per
day reboxetine for 42, but not 14, days reduced NET expression;
antidepressant-like effects on behavior were observed for both treatment
durations. Treatment for 14 days with 70 mg/kg per day venlafaxine, which
inhibits both the NET and SERT, or 10 mg/kg per day phenelzine, a monoamine
oxidase inhibitor, produced antidepressant-like effects on behavior without
altering NET or SERT expression. For all drugs tested, reductions of NET and
SERT protein were not accompanied by reduced NET or SERT mRNA in locus coeruleus
or dorsal raphe nucleus, respectively. Overall, the present results suggest an
important, though not universal, role for NET and SERT regulation in the
long-term behavioral effects of antidepressants. Understanding the mechanisms
underlying transporter regulation in vivo may suggest novel targets for the
development of antidepressant drugs. INTRODUCTION: Serotonin and norepinephrine reuptake inhibitors (SNRIs) are
antidepressants which have high affinity to both serotonin transporter (SERT)
and norepinephrine transporter (NET). In studies in vitro, SNRIs have been
reported to show a large variability in the affinity ratio between SERT and NET.
For instance, the reported affinity ratio is about 30 for venlafaxine and 1.6
for milnacipran. In this study in nonhuman primates, we aimed to investigate the
relationship between SERT and NET affinity by measuring the in vivo occupancy at
both transporters of venlafaxine and milnacipran.
METHODS: PET measurements with [(11)C]MADAM and [(18)F]FMeNER-D(2) were
performed in two female cynomolgus monkeys at baseline and after pretreatment
with venlafaxine and milnacipran, respectively. Relationships between dose,
plasma concentration, and transporter occupancy were evaluated by saturation
analysis using a hyperbolic function. Binding affinity (Kd(plasma)) was
expressed by the dose or plasma concentration at which 50 % of the transporter
was occupied.
RESULTS: SERT and NET occupancy by venlafaxine and milnacipran increased in a
dose and plasma concentration-dependent manner. The Kd(plasma) ratio of SERT to
NET was 1.9 for venlafaxine and 0.6 for milnacipran.
CONCLUSIONS: In this nonhuman primate PET study, the affinity in vivo for SERT
and NET, respectively, was shown to be at a similar level for venlafaxine and
milnacipran. Both drugs were found to produce balanced inhibition of SERT and
NET binding. This observation is not consistent with previous in vitro binding
data and illustrates the need to characterize antidepressants at in vivo
condition. |
Is Rheumatoid Arthritis more common in men or women? | Disease patterns in RA vary between the sexes; the condition is more commonly seen in women, who exhibit a more aggressive disease and a poorer long-term outcome. | The present case-control study was conducted to investigate the relationship
between smoking and rheumatoid arthritis, and to investigate formally the
interaction between sex, smoking, and risk for developing rheumatoid arthritis.
The study was performed in the Central District of Finland. Cases were patients
with rheumatoid arthritis and the control group was a random sample of the
general population. Logistic regression models were used to evaluate the effect
of smoking on risk for rheumatoid arthritis, after adjusting for the effects of
age, education, body mass index, and indices of general health and pain.
Overall, 1095 patients with rheumatoid arthritis and 1530 control individuals
were included. Patients were older, less well educated, more disabled, and had
poorer levels of general health as compared with control individuals (all P <
0.01). Preliminary analyses revealed the presence of substantial statistical
interaction between smoking and sex (P < 0.001). In separate multivariable
analyses, past history of smoking was associated with increased risk for
rheumatoid arthritis overall in men (odds ratio 2.0, 95% confidence interval
1.2-3.2) but not in women. Among men, this effect was seen only for rheumatoid
factor-positive rheumatoid arthritis. There were significant interactions
between smoking and age among women but not among men. We conclude that sex is a
biologic effect modifier in the association between smoking and rheumatoid
arthritis. The role of menopause in the etiology of rheumatoid arthritis merits
further research. OBJECTIVE: To investigate whether gender is an independent factor associated
with disease expression in early rheumatoid arthritis (RA) patients.
METHODS: 438 patients with early RA (disease duration less than one year) were
studied. They all were patients with early RA who presented at the Rheumatology
Clinic of the University Hospital of Ioannina during the period 1991-2000. All
patients fulfilled the American College of Rheumatology criteria for RA. The
demographic, clinical, laboratory, radiological and therapeutic characteristics
of the disease at diagnosis, and at the last follow-up were analyzed according
to gender.
RESULTS: We studied 312 women and 126 men with early RA. The female to male
ratio was 2.5:1 and the mean age at diagnosis was 49.4 +/- 14.9 years for women
and 55.3 +/-15.6 years for men (P < 0.0003). Women had a longer duration of
follow-up (P < 0.0003). There were no differences between genders in the general
symptoms or the simmetricity of joint involvement at at disease onset. However
at disease onset women had a higher erythrocyte sedimentation rate (ESR) (> 30
mm/1st hour), although there were no significant differences between the two
groups concerninig the rest of the clinical, laboratory and radiological
findings. At the last follow-up women still had a higher ESR (>30 min/1st hour),
but no significant differences were found between the two groups concerning the
rest of the parameters investigated independently of the follow-up duration.
Finally, women and men showed the same degree of radiological changes and
functional ability and were treated similarly except for the more frequent use
of hydroxychloroquine in women.
CONCLUSION: It seems that gender does not signficantly influence the expression
of RA. Emotion regulation has been associated with perceived health in rheumatoid
arthritis, which is diagnosed three times more often in women than men. Our aim
was to examine gender differences in styles of emotion regulation (ambiguity,
control, orientation, and expression) and gender-specificity of the associations
between emotion regulation and perceived health (psychological well-being,
social functioning, physical functioning, and disease activity) in 244 female
and 91 male patients with rheumatoid arthritis. Women reported more emotional
orientation than men, but did not differ from men with regard to ambiguity,
control, and expression. Structural equation modelling showed that relationships
between emotion regulation and perceived health were more frequent and stronger
for women than men. This held especially for the affective dimension of health,
while associations were similar for both women and men with regard to social and
physical functioning. Only for women, the association between ambiguity and
disease activity was significant, which appeared to be mediated by affective
functioning. The observations that women are more emotionally oriented than men
and that emotion regulation is more interwoven with psychological health in
women than men, support the usefulness of a gender-sensitive approach in
research and health care of patients with rheumatoid arthritis. OBJECTIVES: To investigate the influence of age and gender on the components of
the 28-joint Disease Activity Score (DAS28) in patients with rheumatoid
arthritis (RA), and to clarify whether a high DAS28 can be equally interpreted
in all age groups, independent of gender.
METHODS: A prospective cohort of 553 patients with RA was studied for
approximately 20 years after diagnosis. The single measures of disease activity
and the share of different components of the DAS28 (eg, erythrocyte
sedimentation rate; ESR) were analysed and compared between three age groups
(<45, 45-65 and >65 years) and per gender, using analysis of variance (ANOVA).
The performance of the DAS28 and its components was explored in moderate to high
and low DAS28 categories. Linear mixed model analysis was used to design the
models best predicting ESR and the share of ESR.
RESULTS: ESR significantly increased with age, independent of other variables of
disease activity. This increase was more pronounced in male than in female
patients. Nevertheless, the share of ESR increased with age only in male
patients with a low DAS28 (<3.2). If the DAS28 score was >3.2, age and gender
did not have a significant effect on any components of the DAS28. C-reactive
protein (CRP) and DAS28(CRP) were not influenced by age.
CONCLUSIONS: A high DAS28 was found to perform equally in all age groups, in men
and women, despite the elevating effect of age on ESR. In elderly men with low
disease activity, remission rate could be underestimated by an elevated ESR. OBJECTIVE: To determine whether the Simplified Disease Activity Index (SDAI) and
the Clinical Disease Activity Index (CDAI) are equally applicable for the total
population with rheumatoid arthritis (RA).
METHODS: Five hundred and fifty-seven outpatients with RA [432 females, 125
males; median age 64 years (range 18-85); median disease duration 48 months
(range 2-548)] were enrolled consecutively in this cross-sectional study. SDAI,
CDAI, patient's assessment of pain on the visual analogue scale (VAS) 0-100,
rheumatoid factor (RF), and disease duration were recorded. Linear regression
analysis was performed for each confounding factor.
RESULTS: The median SDAI for all 557 patients was 11.6 (range 0.07-46.60) and
the median CDAI was 10.7 (0.00-42.10). The median SDAI was 12.2 (0.07-46.60) in
females and 8.0 (0.10-35.20) in males. The respective medians for the CDAI were
11.3 (0.00-42.10) and 7.1 (0.00-32.00). These differences were highly
statistically significant (p<0.001). Patient's assessment of pain on the VAS
0-100 scale had a median value of 32 mm. Regression analysis revealed a highly
significant relationship between SDAI/CDAI levels and patient's pain rating
(SDAI: r = 0.660, p<0.001; CDAI: r = 0.671, p<0.001). On multiple regression
analysis, pain exerted a highly significant influence on SDAI and CDAI levels
(p<0.001), whereas age, disease duration, and RF were not correlated with either
level.
CONCLUSION: SDAI and CDAI values are highly dependent on the patient's pain
perception and gender. The effects of patient's age, disease duration, and RF
were inconclusive with respect to the values of the respective disease activity
indexes. OBJECTIVE: To evaluate gender differences in score on 28-joint Disease Activity
Score (DAS28), Health Assessment Questionnaire (HAQ) and Signals Of Functional
Impairment (SOFI) and to relate these scores to radiographic joint destruction.
METHODS: In all, 549 patients with early RA (62% women) from the BARFOT (for
"Better Anti-Rheumatic FarmacOTherapy") study were included. At baseline, 1, 2
and 5 years DAS28, HAQ and SOFI scoring, and radiographs of hands and feet were
performed. The radiographs were scored using the van der Heijde-Sharp score.
RESULTS: In women the DAS28 was significantly higher than in men due to higher
scores for general health and tender joints. Likewise, HAQ and VAS pain were
rated significantly higher in women. The SOFI score was worse in men during the
first 2 years, depending on higher upper limb scores. Total Sharp score
(TotSharp), erosion score and joint space narrowing score did not differ between
the sexes at any time point. The DAS28 area under the curve (AUC) correlated
significantly with TotSharp at 5 years in both genders (r = 0.316, r = 0.313)
mainly owing to swollen joints and erythrocyte sedimentation rate (ESR). The
SOFI AUC correlated significantly with TotSharp in women (r = 0.135 to 0.220)
but not in men.
CONCLUSIONS: Despite a similar degree of radiographic joint destruction women
had, compared with men, worse scores for DAS28 and HAQ, possibly due to higher
pain perception and less muscular strength and perhaps because men overestimate
their functional capacity. OBJECTIVE: To assess gender differences in disease characteristics and treatment
responses over time in a disease-modifying antirheumatic drug (DMARD)-naive
seropositive early rheumatoid arthritis (RA) cohort.
METHODS: Patients with polyarticular disease who were DMARD-naive and had
seropositive early RA (< 14 months) were recruited by the Western Consortium of
Practicing Rheumatologists. Each patient was examined at study entry, after 6
and 12 months, and yearly thereafter. Clinical and demographic data were
collected. We investigated gender differences in baseline disease
characteristics and treatment using chi-squared, Mann-Whitney U, and t tests. We
used generalized estimating equations (GEE) models for repeated measures to
examine whether the rate of change of specific disease outcomes during the first
2 years after DMARD initiation was significantly influenced by gender.
RESULTS: At baseline, men (n = 67) and women (n = 225) had similar disease
activity and radiographic damage; men, however, had significantly worse erosion,
while women had worse joint space narrowing. Despite similar treatment, women
had worse disease progression over the 2-year followup, as assessed by trends in
Disease Activity Score 28/erythrocyte sedimentation rate (DAS28-ESR4), physician
global scores, and tender joint counts. In the GEE model, gender was
significantly associated with the rate of change of DAS28-ESR4 scores (p =
0.009), although not independently associated with disease activity.
Self-reported measures (Health Assessment Questionnaire-Disability Index,
patient global scores, fatigue, pain) were worse among women at baseline and
throughout the study period. Men were more likely to achieve remission.
CONCLUSION: At baseline, men and women had similar disease activity and joint
damage. Responses to treatment over time were better among men in this
prebiologic era; women had worse progression despite similar treatment. BACKGROUND: Rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and
psoriasis are immune-mediated inflammatory diseases with similarities in
pathophysiology, and all can be treated with similar biological agents. Previous
studies have shown that there are gender differences with regard to disease
characteristics in RA and IBD, with women generally having worse scores on pain
and quality of life measurements. The relationship is less clear for psoriasis.
Because treatment differences between men and women could explain the
dissimilarities, we investigated gender differences in the disease
characteristics before treatment initiation and in the biologic treatment
prescribed.
METHODS: Data on patients with RA or IBD were collected from two registries in
which patients treated with biologic medication were enrolled. Basic demographic
data and disease activity parameters were collected from a time point just
before the initiation of the biologic treatment. For patients with psoriasis,
the data were taken from the 2010 annual report of the Swedish Psoriasis
Register for systemic treatment, which included also non-biologic treatment. For
all three diseases, the prescribed treatment and disease characteristics were
compared between men and women.
RESULTS: In total, 4493 adult patients were included in the study (1912 with RA,
131 with IBD, and 2450 with psoriasis). Most of the treated patients with RA
were women, whereas most of the patients with IBD or psoriasis were men. There
were no significant differences between men and women in the choice of
biologics. At treatment start, significant gender differences were seen in the
subjective disease measurements for both RA and psoriasis, with women having
higher (that is, worse) scores than men. No differences in objective
measurements were found for RA, but for psoriasis men had higher (that is,
worse) scores for objective disease activity measures. A similar trend to RA was
seen in IBD.
CONCLUSIONS: Women with RA or psoriasis scored significantly higher on
subjective, but not on objective, disease activity measures than men, and the
same trend was seen in IBD. This indicates that at the same level of treatment,
the disease has a greater effect in women. These findings might suggest that in
all three diseases, subjective measures are discounted to some extent in the
therapeutic decision-making process, which could indicate undertreatment in
female patients. BACKGROUND: Data on the effect of gender in rheumatoid arthritis (RA) in
non-Caucasian populations is scarce. Latin America and the Caribbean (LAC) is a
large population with unique characteristics, including high admixture.
OBJECTIVE: Our aim was to examine the effect of gender in patients with RA in
LAC.
METHODS: This was a 2-phase study. First we conducted a cross-sectional and
analytical study in which 1128 consecutive Colombian patients with RA were
assessed. Second, a systematic review of the literature was done to evaluate the
effect of gender in LAC patients with RA.
RESULTS: Our results show a high prevalence of RA in LAC women with a ratio of
5.2 women per man. Colombian women with RA are more at risk of having an early
age at onset and developing polyautoimmunity and abdominal obesity, and they
perform more household duties than their male counterparts. However, male gender
was associated with the presence of extra-articular manifestations. Of a total
of 641 potentially relevant articles, 38 were considered for final analysis, in
which several factors and outcomes related to gender were identified.
CONCLUSIONS: RA in LAC women is not only more common but presents with some
clinical characteristics that differ from RA presentation in men. Some of those
characteristics could explain the high rates of disability and worse prognosis
observed in women with RA in LAC. |
What is FINDbase? | Frequency of INherited Disorders database (FINDbase) (http://www.findbase.org) is a relational database, derived from the ETHNOS software, recording frequencies of causative mutations leading to inherited disorders worldwide. Database records include the population and ethnic group, the disorder name and the related gene, accompanied by links to any corresponding locus-specific mutation database, to the respective Online Mendelian Inheritance in Man entries and the mutation together with its frequency in that population. The initial information is derived from the published literature, locus-specific databases and genetic disease consortia. FINDbase offers a user-friendly query interface, providing instant access to the list and frequencies of the different mutations. Query outputs can be either in a table or graphical format, accompanied by reference(s) on the data source. Registered users from three different groups, namely administrator, national coordinator and curator, are responsible for database curation and/or data entry/correction online via a password-protected interface. Database access is free of charge and there are no registration requirements for data querying. FINDbase provides a simple, web-based system for population-based mutation data collection and retrieval and can serve not only as a valuable online tool for molecular genetic testing of inherited disorders but also as a non-profit model for sustainable database funding, in the form of a 'database-journal'. | Frequency of INherited Disorders database (FIND base; http://www.findbase.org)
records frequencies of causative genetic variations worldwide. Database records
include the population and ethnic group or geographical region, the disorder
name and the related gene, accompanied by links to any related external
resources and the genetic variation together with its frequency in that
population. In addition to the regular data content updates, we report the
following significant advances: (i) the systematic collection and thorough
documentation of population/ethnic group-specific pharmacogenomic markers allele
frequencies for 144 markers in 14 genes of pharmacogenomic interest from
different classes of drug-metabolizing enzymes and transporters, representing
150 populations and ethnic groups worldwide; (ii) the development of new data
querying and visualization tools in the expanded FINDbase data collection, built
around Microsoft's PivotViewer software (http://www.getpivot.com), based on
Microsoft Silverlight technology (http://www.silverlight.net) that facilitates
querying of large data sets and visualizing the results; and (iii) the
establishment of the first database journal, by affiliating FINDbase with Human
Genomics and Proteomics, a new open-access scientific journal, which would serve
as a prime example of a non-profit model for sustainable database funding. |
Can vitamin B1 deficiency cause encephalopathy? | Wernicke's encephalopathy (WE) is a severe neurological syndrome caused by thiamine (vitamin B1) deficiency and clinically characterized by the sudden onset of mental status changes, ocular abnormalities, and ataxia. It is commonly associated with heavy alcohol consumption. Other clinical associations are with hyperemesis gravidarum (HG), starvation, and prolonged intravenous feeding. | Wernicke's encephalopathy is a serious neurological manifestation of vitamin B1
deficiency. We report a case occurring secondary to hyperemesis gravidarum. The classic signs of vitamin deficiency only occur in states of extreme
depletion and are unreliable indicators for early treatment or prophylaxis of
alcoholic patients at risk. Post-mortem findings demonstrate that thiamine
(vitamin B1) deficiency sufficient to cause irreversible brain damage is not
diagnosed ante mortem in 80-90% of these patients. The causes of vitamin
deficiency are reviewed with special attention to the inhibition of oral
thiamine hydrochloride absorption in man caused by malnutrition present in
alcoholic patients or by the direct effects of ethanol on intestinal transport.
As the condition of the patient misusing alcohol progresses, damage to brain,
liver, gastrointestinal tract, and pancreas continue (with other factors
discussed) to further compromise the patient. Decreased intake, malabsorption,
reduced storage, and impaired utilization further reduce the chances of unaided
recovery. Failure of large oral doses of thiamine hydrochloride to provide an
effective treatment for Wernicke's encephalopathy emphasizes the need for
adequate and rapid replacement of depleted brain thiamine levels by repeated
parenteral therapy in adequate doses. Acute Wernicke's encephalopathy (WE) is caused by profound vitamin B1 (thiamine)
deficiency and commonly presents with the classic clinical triad of mental
confusion, ataxia, and ophthalmoplegia. This characteristic presentation results
from the propensity of acute thiamine deficiency to preferentially injure
specific brain regions: the dorsomedial thalamus, periaqueductal gray, and
mamillary bodies. In these regions, abnormal magnetic resoce signaling on
conventional sequences has been well described; however, diffusion restriction
has only recently been reported. The authors demonstrate diffusion-weighted
imaging (DWI) abnormalities of the splenium of the corpus callosum in a patient
with acute WE, which has not been reported previously, and suggest a potential
pathological mechanism. With the recent addition of DWI, MRI is becoming more
sensitive to the changes in acute WE. Furthermore, the use of apparent diffusion
coefficient mapping to evaluate the extent of likely underlying cytotoxic injury
may help determine long-term response to vitamin therapy and, thus, disability. INTRODUCTION: Wernicke's encephalopathy caused by thiamine deficiency is
typically characterised by a mental-status change, oculomotor dysfunction and an
ataxia. Pellagra is the clinical presentation of niacin deficiency comprising
cutaneous, gastrointestinal and neuropsychiatric manifestations.
OBSERVATION: We report a case of encephalopathy due to dual vitamin deficiency
of both thiamine (vitamin B1) and niacin (vitamin PP) in an 80-year-old women,
hospitalized for severe sepsis caused by aspiration pneumonia. Severe
malnutrition and alcohol consumption pointed to a diagnosis of vitamin
deficiency. The clinical presentation and magnetic resoce imaging (MRI) were
compatible with Wernicke's encephalopathy that remained irreversible despite
vitamin B1 supplementation. Niacin supplementation allowed for complete
regression of the observed symptoms compatible with niacin deficiency.
CONCLUSION: Malnourished and alcoholic patients showing signs of encephalopathy
should receive supplemental multivitamins including niacin. Wernicke's encephalopathy is a neurological disorder caused by thiamine (vitamin
B1) deficiency characterized by vertigo, ataxia, and mental confusion.
Wernicke's encephalopathy has a causative association with alcoholism but
recently there has been an increased prevalence also in other clinical
conditions. In literature potentially fatal Wernicke's encephalopathy onset in
an advanced achalasia has been previously reported only once. We describe for
the first time an improvement of achalasic symptoms in a young patient affected
by end-stage achalasia and anorexia nervosa (coming from ineffective Heller-Dor
myotomy) after vitamin B1 supplementation. This case report suggest a potential
positive impact of B1 supplementation on end-stage achalasic patients and
requires systematic studies to confirm this observation. BACKGROUND: Thiamine deficiency in patients who abuse alcohol can cause
Wernicke's encephalopathy (WE). Thiamine supplements are given to prevent this
complication. Guidelines exist for giving thiamine supplementation in the
inpatient population. However, similar guidelines are not available for
clinicians detoxifying patients in the community, and consequently, assessment
of risk of WE and prophylaxis can be inconsistent.
METHODS: A scoring system to assess risk of WE was developed and evaluated by
comparing practice before and after introduction of the system. One hundred and
twenty-six cases requiring alcohol detoxification were examined: 94 before
introduction of the scoring system and 32 afterward.
RESULTS: Before introduction of the scoring system, a risk assessment for
developing WE was performed in 30% of patients and parenteral thiamine
prescribed in 32%. After introduction of the scoring system, risk assessment and
administration of parenteral thiamine increased to 100 and 75%, respectively.
There was 1 probable case of WE before introduction of the scoring system and
none afterward.
CONCLUSIONS: We conclude that assessment of WE is often inadequate, leading to
inadequate thiamine administration. The new scoring system allows simple,
structured risk assessment for WE and thus guides appropriate thiamine
administration. This is of most value to clinicians treating the consequences of
alcohol dependence in the community. Introduction. Wernicke's encephalopathy is a well-described syndrome
characterized by the classic triad of confusion, ataxia, and ophthalmoplegia.
Wernicke's encephalopathy results from thiamine (vitamin B1) deficiency. Common
causes include alcoholism and gastric disorders. Wernicke's has been described
in patients with acquired immune deficiency syndrome (AIDS); however, given
these patients' immunosuppressed state, the diagnosis of Wernicke's
encephalopathy is not apparent. Case Presentation. A 31-year-old previously
healthy male presented to the ER complaining of progressive dyspnea. Workup
revealed HIV/AIDS and PCP pneumonia. He was treated and improved. On day 14 he
became confused and developed nystagmus and ataxia. Considering his
immunocompromised state, infectious and neoplastic etiologies topped the
differential diagnosis. CT head was negative. Lumbar puncture was unremarkable.
Brain MRI revealed increased T2 signal in the medial thalamus bilaterally.
Intravenous thiamine was administered resulting in resolution of symptoms.
Discussion. The classic triad of Wernicke's encephalopathy occurs in 10% of
cases. When immunosuppressed patients develop acute neurologic symptoms
infectious or neoplastic etiologies must be excluded. However, given the
relative safety of thiamine supplementation, there should be a low threshold for
initiating therapy in order to reverse the symptoms and prevent progression to
Korsakoff dementia, which is permanent. BACKGROUND: Wernicke's encephalopathy-Korsakoff syndrome (WE-KS) is common in
alcoholics, caused by thiamine deficiency (TD; vitamin B1) and associated with
lesions to the thalamus (THAL). Although TD alone can cause WE, the high
incidence in alcoholism suggests that TD and ethanol (EtOH) interact.
METHODS: Mice in control, TD, or EtOH groups alone or combined were studied
after 5 or 10 days of treatment. THAL and entorhinal cortex (ENT) histochemistry
and mRNA were assessed.
RESULTS: Combined EtOH-TD treatment for 5 days (EtOH-TD5) showed activated
microglia, proinflammatory gene induction and THAL neurodegeneration that was
greater than that found with TD alone (TD5), whereas 10 days resulted in marked
THAL degeneration and microglial-neuroimmune activation in both groups. In
contrast, 10 days of TD did not cause ENT degeneration. Interestingly, in ENT,
TD10 activated microglia and astrocytes more than EtOH-TD10. In THAL, multiple
astrocytic markers were lost consistent with glial cell loss. TD blocks glucose
metabolism more than acetate. Acetate derived from hepatic EtOH metabolism is
transported by monocarboxylic acid transporters (MCT) into both neurons and
astrocytes that use acetyl-CoA synthetase (AcCoAS) to generate cellular energy
from acetate. MCT and AcCoAS expression in THAL is lower than ENT prompting the
hypothesis that focal THAL degeneration is related to insufficient MCT and
AcCoAS in THAL. To test this hypothesis, we administered glycerin triacetate
(GTA) to increase blood acetate and found it protected the THAL from TD-induced
degeneration.
CONCLUSIONS: Our findings suggest that EtOH potentiates TD-induced THAL
degeneration through neuroimmune gene induction. The findings support the
hypothesis that TD deficiency inhibits global glucose metabolism and that a
reduced ability to process acetate for cellular energy results in THAL focal
degeneration in alcoholics contributing to the high incidence of
Wernicke-Korsakoff syndrome in alcoholism. Wernicke's encephalopathy (WE) is a potentially reversible yet serious
neurological manifestation caused by vitamin B1(thiamine) deficiency. It is
commonly associated with heavy alcohol consumption. Other clinical associations
are with hyperemesis gravidarum (HG), starvation, and prolonged intravenous
feeding. Most patients present with the triad of ocular signs, ataxia, and
confusion. It can be associated with life-threatening complication like central
pontine myelinolysis (CPM). We report two cases of WE following HG, with two
different outcomes. Thiamine (vitamin B1) deficiency, associated with a variety of conditions,
including chronic alcoholism and bariatric surgery for morbid obesity, can
result in the neurological disorder Wernicke's encephalopathy (WE). Recent work
building upon early observations in animal models of thiamine deficiency has
demonstrated an inflammatory component to the neuropathology observed in
thiamine deficiency. The present, multilevel study including in vivo magnetic
resoce imaging (MRI) and spectroscopy (MRS) and postmortem quantification of
chemokine and cytokine proteins sought to determine whether a combination of
these in vivo neuroimaging tools could be used to characterize an in vivo MR
signature for neuroinflammation. Thiamine deficiency for 12days was used to
model neuroinflammation; glucose loading in thiamine deficiency was used to
accelerate neurodegeneration. Among 38 animals with regional brain tissue
assayed postmortem for cytokine/chemokine protein levels, three groups of rats
(controls+glucose, n=6; pyrithiamine+saline, n=5; pyrithiamine+glucose, n=13)
underwent MRI/MRS at baseline (time 1), after 12days of treatment (time 2), and
3h after challenge (glucose or saline, time 3). In the thalamus of
glucose-challenged, thiamine deficient animals, correlations between in vivo
measures of pathology (lower levels of N-acetyle aspartate and higher levels of
lactate) and postmortem levels of monocyte chemotactic protein-1 (MCP-1, also
known as chemokine ligand 2, CCL2) support a role for this chemokine in thiamine
deficiency-related neurodegeneration, but do not provide a unique in vivo
signature for neuroinflammation. Wernicke's encephalopathy (WE) is a severe neurological syndrome caused by
thiamine (vitamin B1) deficiency and clinically characterized by the sudden
onset of mental status changes, ocular abnormalities, and ataxia. Apart from
chronic alcoholism, the most common cause of WE, a lot of other conditions
causing malnutrition and decreasing thiamine absorption such as gastrointestinal
surgical procedures and hyperemesis gravidarum must be considered as
predisposing factors. Due to its low prevalence and clinical heterogeneity, WE
is often misdiagnosed, leading to persistent dysfunctions and, in some cases, to
death. Nowadays, MR imaging of the brain, showing T2 and FLAIR hyperintensities
in typical (thalami, mammillary bodies, tectal plate, and periaqueductal area)
and atypical areas (cerebellum, cranial nerve nuclei, and cerebral cortex), is
surely the most important and effective tool in the diagnostic assessment of WE.
The aim of this paper is to propose a state of the art of the role of MR imaging
in the early diagnosis of this complex disease. BACKGROUND: Wernicke encephalopathy is caused by thiamine (vitamin B1)
deficiency. It is generally considered to be a disease of adult alcoholics.
However, it is known to occur in the pediatric population and in non-alcoholic
conditions.
DATA SOURCES: We searched PubMed with the key words Wernicke, thiamine,
pediatric, children and adolescents and selected publications that were deemed
appropriate.
RESULTS: The global prevalence rates of hunger, poverty and resultant nutrient
deprivation have decreased in the 21st century. However, several scenarios which
may predispose to Wernicke encephalopathy may be increasingly prevalent in
children and adolescents such as maligcies, intensive care unit stays and
surgical procedures for the treatment of obesity. Other predisposing conditions
include magnesium deficiency and defects in the SLC19A3 gene causing thiamine
transporter-2 deficiency. The classic triad consists of encephalopathy,
oculomotor dysfunction and gait ataxia but is not seen in a majority of
patients. Treatment should be instituted immediately when the diagnosis is
suspected clinically without waiting for laboratory confirmation. Common
magnetic resoce findings include symmetric T2 hyperintensities in dorsal
medial thalamus, mammillary bodies, periaqueductal gray matter, and tectal
plate.
CONCLUSIONS: Wernicke encephalopathy is a medical emergency. Delay in its
recognition and treatment may lead to significant morbidity, irreversible
neurological damage or even death. This article aims to raise the awareness of
this condition among pediatricians. |
Which methyl-CpG-binding protein when mutant becomes the hallmark for Rett syndrome? | Rett syndrome (RTT) was shown to be caused by mutations in the methyl-CpG-binding protein 2 (MECP2) gene, with molecular studies identifying MECP2 mutations in up to 80% of classic RTT patients. MECP2 protein was found to assist in the transcriptional silencing process via DNA methylation. We therefore hypothesize that disruption of this gene alters the normal developmental expression of various other genes, some of which must account for the peculiar neurologic phenotype of RTT. | Rett syndrome (RTT) is an X-linked domit neurodevelopmental disorder that
manifests in females, typically after the first year of life. It is a leading
cause of mental retardation and autistic behavior in girls and women; a hallmark
of the disease is incessant hand movements in the form of wringing, twisting, or
clapping. It was recently discovered that RTT is caused by mutations in the
methyl-CpG-binding protein 2 (MECP2) gene. MECP2 assists in the transcriptional
silencing process via DNA methylation; we hypothesize that disruption of this
gene alters the normal developmental expression of various other genes, some of
which must account for the peculiar neurologic phenotype of RTT. Molecular
studies have identified MECP2 mutations in up to 80% of classic RTT patients;
mutation type has some effect on the phenotypic manifestation of RTT, but the
pattern of X inactivation seems to determine phenotypic severity. Favorable
(skewed) X inactivation can so spare a patient from the effects of mutant MECP2
that they display only the mildest learning disability or no phenotype at all.
The unmitigated impact of mutant MECP2 can be inferred from the few males who
have been born into RTT kindreds with such severe neonatal encephalopathy that
they did not survive their second year. MECP2 mutations thus manifest in a far
broader array of phenotypes than classic RTT. This discovery should prove
helpful in diagnosing cases of mild learning disability or severe neonatal
encephalopathies of unknown cause and also should provide insight into the
pathogenesis of RTT. Severely arrhythmic breathing is a hallmark of Rett syndrome (RTT) and
profoundly affects quality of life for patients and their families. The last
decade has seen the identification of the disease-causing gene,
methyl-CpG-binding protein 2 (Mecp2) and the development of mouse models that
phenocopy many aspects of the human syndrome, including breathing dysfunction.
Recent studies have begun to characterize the breathing phenotype of Mecp2
mutant mice and to define underlying electrophysiological and neurochemical
deficits. The picture that is emerging is one of defects in synaptic
transmission throughout the brainstem respiratory network associated with
abnormal expression in several neurochemical signaling systems, including
brain-derived neurotrophic factor (BDNF), biogenic amines and
gamma-amino-butyric acid (GABA). Based on such findings, potential therapeutic
strategies aimed at improving breathing by targeting deficits in neurochemical
signaling are being explored. This review details our current understanding of
respiratory dysfunction and underlying mechanisms in RTT with a particular focus
on insights gained from mouse models. Rett syndrome (RTT) results from loss-of-function mutations in the gene encoding
the methyl-CpG-binding protein 2 (MeCP2) and is characterized by abnormal motor,
respiratory and autonomic control, cognitive impairment, autistic-like behaviors
and increased risk of seizures. RTT patients and Mecp2-null mice exhibit reduced
expression of brain-derived neurotrophic factor (BDNF), which has been linked in
mice to increased respiratory frequency, a hallmark of RTT. The present study
was undertaken to test the hypotheses that BDNF deficits in Mecp2 mutants are
associated with reduced activation of the BDNF receptor, TrkB, and that
pharmacologic activation of TrkB would improve respiratory function. We
characterized BDNF protein expression, TrkB activation and respiration in
heterozygous female Mecp2 mutant mice (Het), a model that recapitulates the
somatic mosaicism for mutant MECP2 found in typical RTT patients, and evaluated
the ability of a small molecule TrkB agonist, LM22A-4, to ameliorate biochemical
and functional abnormalities in these animals. We found that Het mice exhibit
(1) reduced BDNF expression and TrkB activation in the medulla and pons and (2)
breathing dysfunction, characterized by increased frequency due to periods of
tachypnea, and increased apneas, as in RTT patients. Treatment of Het mice with
LM22A-4 for 4 weeks rescued wild-type levels of TrkB phosphorylation in the
medulla and pons and restored wild-type breathing frequency. These data provide
new insight into the role of BDNF signaling deficits in the pathophysiology of
RTT and highlight TrkB as a possible therapeutic target in this disease. |
Are epigenetic modifications implicated in cardiovascular development and disease? | Genetic and epigenetic factors are of great importance in cardiovascular biology and disease. Aberrant epigenetic mechanisms may lead to pathological consequences such as cardiovascular disease (CAD).Recent studies have greatly expanded our understanding of the regulation of cardiovascular development at the chromatin level, including the remodeling of chromatin and the modification of histones. Thus, understanding chromatin-level regulation will allow for a better appreciation of gene regulation as a whole and may set a fundamental basis for cardiovascular disease. | Cellular commitment to a specific lineage is controlled by differential
silencing of genes, which in turn depends on epigenetic processes such as DNA
methylation and histone modification. During early embryogenesis, the mammalian
genome is 'wiped clean' of most epigenetic modifications, which are
progressively re-established during embryonic development. Thus, the epigenome
of each mature cellular lineage carries the record of its developmental history.
The subsequent trajectory and pattern of development are also responsive to
environmental influences, and such plasticity is likely to have an epigenetic
basis. Epigenetic marks may be transmitted across generations, either directly
by persisting through meiosis or indirectly through replication in the next
generation of the conditions in which the epigenetic change occurred.
Developmental plasticity evolved to match an organism to its environment, and a
mismatch between the phenotypic outcome of adaptive plasticity and the current
environment increases the risk of metabolic and cardiovascular disease. These
considerations point to epigenetic processes as a key mechanism that underpins
the developmental origins of chronic noncommunicable disease. Here, we review
the evidence that environmental influences during mammalian development lead to
stable changes in the epigenome that alter the individual's susceptibility to
chronic metabolic and cardiovascular disease, and discuss the clinical
implications. Despite advances in the prevention and management of cardiovascular disease
(CVD), this group of multifactorial disorders remains a leading cause of
mortality worldwide. CVD is associated with multiple genetic and modifiable risk
factors; however, known environmental and genetic influences can only explain a
small part of the variability in CVD risk, which is a major obstacle for its
prevention and treatment. A more thorough understanding of the factors that
contribute to CVD is, therefore, needed to develop more efficacious and
cost-effective therapy. Application of the 'omics' technologies will hopefully
make these advances a reality. Epigenomics has emerged as one of the most
promising areas that will address some of the gaps in our current knowledge of
the interaction between nature and nurture in the development of CVD. Epigenetic
mechanisms include DNA methylation, histone modification, and microRNA
alterations, which collectively enable the cell to respond quickly to
environmental changes. A number of CVD risk factors, such as nutrition, smoking,
pollution, stress, and the circadian rhythm, have been associated with
modification of epigenetic marks. Further examination of these mechanisms may
lead to earlier prevention and novel therapy for CVD. Epigenetics refers to a heritable change in the pattern of gene expression that
is mediated by a mechanism specifically not due to alterations in the primary
nucleotide sequence. Well-known epigenetic mechanisms encompass DNA methylation,
chromatin remodeling (histone modifications), and RNA interference.
Functionally, epigenetics provides an extra layer of transcriptional control and
plays a crucial role in normal physiological development, as well as in
pathological conditions. Aberrant DNA methylation is implicated in immune
dysfunction, inflammation, and insulin resistance. Epigenetic changes may be
responsible for 'metabolic memory' and development of micro- and macrovascular
complications of diabetes. MicroRNAs are critical in the maintece of
glomerular homeostasis and hence RNA interference may be important in the
progression of renal disease. Recent studies have shown that epigenetic
modifications orchestrate the epithelial-mesenchymal transition and eventually
fibrosis of the renal tissue. Oxidative stress, inflammation,
hyperhomocysteinemia, and uremic toxins could induce epimutations in chronic
kidney disease. Epigenetic alterations are associated with inflammation and
cardiovascular disease in patients with chronic kidney disease. Reversible
nature of the epigenetic changes gives a unique opportunity to halt or even
reverse the disease process through targeted therapeutic strategies. Epigenetic control mechanisms play a key role in the regulation of embryonic
development and tissue homeostasis and modulate cardiovascular diseases.
Increasing evidence suggests that lineage commitment of stem/progenitor cells is
tightly regulated by epigenetic mechanisms. These epigenetic control mechanisms
include DNA and histone modifications, which modulate the chromatin structure
thereby regulating access of transcription factors. Particularly, the
modification of histone acetylation and methylation, which is controlled by
families of histone acetylases/deacetylases and methyltransferases/demethylases,
respectively, controls stem cell maintece, differentiation, and function.
This review article summarizes our current understanding of epigenetic
mechanisms regulating the differentiation of cardiovascular cells, specifically
endothelial cells and cardiac muscle lineages. In particular, the article will
focus on the enzymes which modify histones and are involved in chromatin
remodelling. Several studies indicate that impaired foetal growth, and in utero exposure to
risk factors, especially maternal hypercholesterolaemia, may be relevant for the
early onset of cardiovascular damage. The exact molecular mechanisms of such
foetal programming are still unclear. Epigenetics may represent one of the
possible scientific explanations of the impact of such intrauterine risk factors
for the subsequent development of cardiovascular disease (CVD) during adulthood.
Translational studies support this hypothesis; however, a direct causality in
humans has not been ascertained. This hypothesis could be investigated in
primates and in human post-mortem foetal arteries. Importantly, some studies
also suggest the transgenerational transmission of epigenetic risk. The recently
launched International Human Epigenome Consortium and the NIH Roadmap
Epigenomics Mapping Consortium will provide the rationale for a useful clinical
scenario for primary prevention and therapy of CVD. Despite the heritable nature
of epigenetic modification, the clinically relevant information shows that it
could be reversible through therapeutic approaches, including histone
deacetylase inhibitors, histone acetyltransferase inhibitors, and commonly used
drugs such as statins. The cardiovascular system is broadly composed of the heart, which pumps blood,
and the blood vessels, which carry blood to and from tissues of the body. Heart
malformations are the most serious common birth defect, affecting at least 2% of
newborns and leading to significant morbidity and mortality. Severe heart
malformations cause heart failure in fetuses, infants, and children, whereas
milder heart defects may not trigger significant heart dysfunction until early
or midadulthood. Severe vasculogenesis or angiogenesis defects in embryos are
incompatible with life, and anomalous arterial patterning may cause vascular
aberrancies that often require surgical treatment. It is therefore important to
understand the underlying mechanisms that control cardiovascular development.
Understanding developmental mechanisms will also help us design better
strategies to regenerate cardiovascular tissues for therapeutic purposes. An
important mechanism regulating genes involves the modification of chromatin, the
higher-order structure in which DNA is packaged. Recent studies have greatly
expanded our understanding of the regulation of cardiovascular development at
the chromatin level, including the remodeling of chromatin and the modification
of histones. Chromatin-level regulation integrates multiple inputs and
coordinates broad gene expression programs. Thus, understanding chromatin-level
regulation will allow for a better appreciation of gene regulation as a whole
and may set a fundamental basis for cardiovascular disease. This review focuses
on how chromatin-remodeling and histone-modifying factors regulate gene
expression to control cardiovascular development. Epigenetics represents a phenomenon of altered heritable phenotypic expression
of genetic information occurring without changes in DNA sequence. Epigenetic
modifications control embryonic development, differentiation and stem cell
(re)programming. These modifications can be affected by exogenous stimuli (e.g.,
diabetic milieu, smoking) and oftentimes culminate in disease initiation. DNA
methylation has been studied extensively and represents a well-understood
epigenetic mechanism. During this process cytosine residues preceding a
guanosine in the DNA sequence are methylated. CpG-islands are short-interspersed
DNA sequences with clusters of CG sequences. The abnormal methylation of CpG
islands in the promoter region of genes leads to a silencing of genetic
information and finally to alteration of biological function. Emerging data
suggest that these epigenetic modifications also impact on the development of
cardiovascular disease. Histone modifications lead to the modulation of the
expression of genetic information through modification of DNA accessibility. In
addition, RNA-based mechanisms (e.g., microRNAs and long non-coding RNAs)
influence the development of disease. We here outline the recent work pertaining
to epigenetic changes in a cardiovascular disease setting. Consolidated knowledge is accumulating as to the role of epigenetic regulatory
mechanisms in the physiology of vascular development and vascular tone as well
as in the pathogenesis of cardiovascular disease. The modulation of gene
expression through modification of the epigenome by structural changes of the
chromatin architecture without alterations of the associated genomic DNA
sequence is part of the cellular response to environmental changes. Such
environmental conditions, which are finally being translated into adaptations of
the cardiovascular system, also comprise pathological conditions such as
atherosclerosis or myocardial infarction. This review summarizes recent findings
on the epigenetics of vascular regulation and disease and presents nutritional
and pharmacological approaches as novel epigenetic strategies in the prevention
and treatment of cardiovascular disease. Epigenetic phenomena are defined as heritable mechanisms that establish and
maintain mitotically stable patterns of gene expression without modifying the
base sequence of DNA. The major epigenetic features of mammalian cells include
DNA methylation, post-translational histone modifications and RNA-based
mechanisms including those controlled by small non-coding RNAs (miRNAs). The
impact of epigenetic mechanisms in cardiovascular pathophysiology is now
emerging as a major player in the interface between genotype to phenotype
variability. This topic of research has strict implications on disease
development and progression, and opens up possible novel preventive strategies
in cardiovascular disease. An important aspect of epigenetic mechanisms is that
they are potentially reversible and may be influenced by
nutritional-environmental factors and through gene-environment interactions, all
of which have an important role in complex, multifactorial diseases such as
those affecting the cardiovascular system. Gene expression regulation through
the interplay of DNA methylation and histone modifications is well-established,
although the knowledge about the function of epigenetic signatures in
cardiovascular disease is still largely unexplored. The study of epigenetic
markers is, therefore, a very promising frontier of science which may aid in a
deeper understanding of molecular mechanisms underlying the modulation of gene
expression in the biomolecule pathways linked to cardiovascular diseases. This
review focuses on up-to-date knowledge pertaining to the role of epigenetics,
from DNA methylation to miRNAs, in major cardiovascular diseases such as
ischemic heart disease, hypertension, heart failure and stroke. A commonly-assumed paradigm holds that the primary genetic determit of
cardiovascular disease resides within the DNA sequence of our genes. This
paradigm can be challenged. For example, how do sequence changes in the
non-coding region of the genome influence phenotype? Why are all diseases not
shared between identical twins? Part of the answer lies in the fact that the
environment or exogenous stimuli clearly influence disease susceptibility, but
it was unclear in the past how these effects were signalled to the static DNA
code. Epigenetics is providing a newer perspective on these issues. Epigenetics
refers to chromatin-based mechanisms important in the regulation of gene
expression that do not involve changes to the DNA sequence per se. The field can
be broadly categorized into three areas: DNA base modifications (including
cytosine methylation and cytosine hydroxymethylation), post-translational
modifications of histone proteins, and RNA-based mechanisms that operate in the
nucleus. Cardiovascular disease pathways are now being approached from the
epigenetic perspective, including those associated with atherosclerosis,
angiogenesis, ischemia-reperfusion damage, and the cardiovascular response to
hypoxia and shear stress, among many others. With increasing interest and
expanding partnerships in the field, we can expect new insights to emerge from
epigenetic perspectives of cardiovascular health. This paper reviews the
principles governing epigenetic regulation, discusses their presently-understood
importance in cardiovascular disease, and considers the growing significance we
are likely to attribute to epigenetic contributions in the future, as they
provide new mechanistic insights and a host of novel clinical applications. Genetic and epigenetic factors are of great importance in cardiovascular biology
and disease. Tobacco-smoking, one of the most important cardiovascular risk
factors, is itself partially determined by genetic background and is associated
with altered epigenetic patterns. This could render the genetics and epigenetics
of smoking-related cardiovascular disease a textbook example of environmental
epigenetics and modern approaches to multimodal data analysis. A pronounced
association of smoking-related methylation patterns in the F2RL3 gene with
prognosis in patients with stable coronary heart disease has recently been
described. Nonetheless, surprisingly little concrete knowledge on the role of
specific genetic variants and epigenetic modifications in the development of
cardiovascular diseases in people who smoke has been accumulated. Beyond the
current knowledge, the present review briefly outlines some chief challenges and
priorities for moving forward in this field. Our understanding of congenital heart defects has been recently advanced by
whole exome sequencing projects, which have identified de novo mutations in many
genes encoding epigenetic regulators. Notably, multiple subunits of switching
defective/sucrose non-fermenting (SWI/SNF) chromatin-remodeling complexes have
been identified as strong candidates underlying these defects because they
physically and functionally interact with cardiogenic transcription factors
critical to cardiac development, such as TBX5, GATA-4, and NKX2-5. While these
studies indicate a critical role of SWI/SNF complexes in cardiac development and
congenital heart disease, many exciting new discoveries have identified their
critical role in the adult heart in both physiological and pathological
conditions involving multiple cell types in the heart, including cardiomyocytes,
vascular endothelial cells, pericytes, and neural crest cells. This review
summarizes the role of SWI/SNF chromatin-remodeling complexes in cardiac
development, congenital heart disease, cardiac hypertrophy, and vascular
endothelial cell survival. Although the clinical relevance of SWI/SNF mutations
has traditionally been focused primarily on their role in tumor suppression,
these recent studies illustrate their critical role in the heart whereby they
regulate cell proliferation, differentiation, and apoptosis of cardiac derived
cell lines. |
Which deiodinases are present in skeletal muscle? | Type 2 and Type 3 deiodinases are expressed in skeletal muscle and their expression is modulated by disease state and fasting. | The relative roles of the types 1 and 2 iodothyronine deiodinases (D1 and D2) in
extrathyroidal 3,5,3'-triiodothyronine (T3) production in humans are unknown. We
calculated the rate of thyroxine (T4) to T3 conversion by intact cells
transiently expressing D1 or D2 at low (2 pM), normal (20 pM), and high (200 pM)
free T4 concentrations. Deiodinase activities were then assayed in cell
sonicates. The ratio of T3 production in cell sonicates (catalytic efficiency)
was multiplied by the tissue activities reported in human liver (D1) and
skeletal muscle (D2). From these calculations, we predict that in euthyroid
humans, D2-generated T3 is 29 nmol/d, while that of D1-generated T3 is 15
nmol/d, from these major deiodinase-expressing tissues. The total estimated
extrathyroidal T3 production, 44 nmol/d, is in close agreement with the 40 nmol
T3/d based on previous kinetic studies. D2-generated T3 production accounts for
approximately 71% of the peripheral T3 production in hypothyroidism, but D1 for
approximately 67% in thyrotoxic patients. We also show that the intracellular
D2-generated T3 has a greater effect on T3-dependent gene transcription than
that from D1, which indicates that generation of nuclear T3 is an intrinsic
property of the D2 protein. We suggest that impairment of D2-generated T3 is the
major cause of the reduced T3 production in the euthyroid sick syndrome. OBJECTIVE: Septic shock is one of various causes of nonthyroidal illness
syndrome (NTIS). In humans, the molecular mechanisms involved in NTIS are mostly
unknown. The aim of this study was to investigate, in patients with NTIS
secondary to septic shock, changes in the expression of genes involved in the
actions of thyroid hormones and in the activity of deiodinase enzymes, in two
tissues important for protein and energy metabolism, skeletal muscle (SM) and
subcutaneous adipose tissue (SAT).
DESIGN: Hospitalized patients were divided into a control and a septic shock
NTIS group.
MEASUREMENT: Serum collection for biochemical measurements, and SM and SAT
biopsies for mRNA expression analysis of thyroid hormone receptors (THRB1,
THRA1), retinoid X receptors (RXRA, RXRB, RXRG), nuclear receptor corepressor
(NCOR1), silencing mediator of retinoid and thyroid hormone receptor (SMRT),
steroid receptor coactivator (SRC1), type 1 and 2 deiodinases (D1, D2),
monocarboxylate transporter 8 (MCT8), SECIS binding protein 2 (SBP2) and
uncoupling protein 3 (UCP3) as well as D1, D2 and D3 enzyme activity
measurements.
RESULTS: The NTIS group had lower serum TSH, and free T3 and higher rT3 than
controls. D1 and D3 were detected in SAT, with no differences found between the
two groups; SM had very low D2 activity and again no differences were found
between groups; D3 activity in SM was higher in NTIS than controls. SM
expression of THRB1, RXRG and D2 was lower and RXRA higher in NTIS than
controls. SAT from NTIS patients had lower MCT8, THRB1, THRA1, RXRG and SMRT,
and higher UCP3 expression than controls.
CONCLUSIONS: In patients with septic shock NTIS tissue responses are orientated
to decrease production and increase degradation (muscle) or decrease uptake
(adipose tissue) of T3, as well as to decrease thyroid hormone actions. CONTEXT: The iodothyronine deiodinases D1, D2, and D3 enable tissue-specific
adaptation of thyroid hormone levels in response to various conditions, such as
hypothyroidism or fasting. The possible expression of D2 mRNA in skeletal muscle
is intriguing because this enzyme could play a role in systemic as well as local
T3 production.
OBJECTIVE: We determined D2 activity and D2 mRNA expression in human skeletal
muscle biopsies under control conditions and during hypothyroidism, fasting, and
hyperinsulinemia.
DESIGN: This was a prospective study.
SETTING: The study was conducted at a university hospital.
PATIENTS: We studied 11 thyroidectomized patients with differentiated thyroid
carcinoma (DTC) on and after 4 wk off T4( replacement and six healthy lean
subjects in the fasting state and during hyperinsulinemia after both 14 and 62 h
of fasting.
MEAN OUTCOME MEASURES: D2 activity and D2 mRNA levels were measured in skeletal
muscle samples.
RESULTS: No differences were observed in muscle D2 mRNA levels in DTC patients
on and off T4 replacement therapy. In healthy subjects, muscle D2 mRNA levels
were lower after 62 h compared to 14 h of fasting. Insulin increased mRNA
expression after 62 h, but not after 14 h of fasting. Skeletal muscle D2
activities were very low and not influenced by hypothyroidism and fasting.
CONCLUSION: Human skeletal muscle D2 mRNA expression is modulated by fasting and
insulin, but not by hypothyroidism. The lack of a clear effect of D2 mRNA
modulation on the observed low D2 activities questions the physiological
relevance of D2 activity in human skeletal muscle. The proliferation and differentiation of muscle precursor cells require myogenic
regulatory factors and chromatin modifiers whose concerted action dynamically
regulates access to DNA and allows reprogramming of cells towards terminal
differentiation. Type 2 deiodinase (D2), the thyroid hormone (TH)-activating
enzyme, is sharply upregulated during myoblast differentiation, whereas type 3
deiodinase (D3), the TH-inactivating enzyme, is downregulated. The molecular
determits controlling synchronized D2 and D3 expression in muscle
differentiation are completely unknown. Here, we report that the histone H3
demethylating enzyme (LSD-1) is essential for transcriptional induction of D2
and repression of D3. LSD-1 relieves the repressive marks (H3-K9me2-3) on the
Dio2 promoter and the activation marks (H3-K4me2-3) on the Dio3 promoter. LSD-1
silencing impairs the D2 surge in skeletal muscle differentiation while inducing
D3 expression thereby leading to a global decrease in intracellular TH
production. Furthermore, endogenous LSD-1 interacts with FoxO3a, and abrogation
of FoxO3-DNA binding compromises the ability of LSD-1 to induce D2. Our data
reveal a novel epigenetic control of reciprocal deiodinases expression and
provide a molecular mechanism by which LSD-1, through the opposite regulation of
D2 and D3 expression, acts as a molecular switch that dynamically finely tunes
the cellular needs of active TH during myogenesis. |
Which genes are involved in patient response to warfarin? | The following genes have been associated with patient response to warfarin: CYP2C9, VKORC1, ORM1, CYP4F2, EPHX1, CYP2C18, CYP2C19, CYP3A5, protein S, clotting factor V, PROC, GGCX. | Warfarin is an anticoagulant available as a racemic mixture. The R- and
S-isomers differ with respect to relative plasma concentrations, clearance,
potency, sites of metabolism, and cytochrome P450 (CYP) isoenzymes responsible
for metabolism. S-Warfarin, the more potent isomer, is metabolized primarily by
CYP2C9. Genetic polymorphisms resulting from single amino acid substitutions
reduce the metabolic capability of 2C9. A reduction in warfarin metabolism due
to genetic polymorphism may explain the increased warfarin response and bleeding
episodes in some patients. Clinical studies showed an increased plasma level of
S-warfarin, decreased clearance of S-warfarin, increased frequency of bleeding,
and prolongation of hospitalization in patients with variant CYP2C9 alleles.
Adverse outcomes associated with warfarin possibly could be avoided by
identifying patients with variant alleles before therapy and starting therapy at
low dosages. Warfarin is the most widely used oral anticoagulant in the world for patients
with venous thrombosis, pulmonary embolism, chronic atrial fibrillation, and
prosthetic heart valves. Approximately 30 genes contribute to therapeutic
effects of warfarin, and genetic polymorphisms in these genes may modulate its
anticoagulant activity. In contrast to monogenic pharmacogenetic traits,
warfarin drug response is a polygenic trait, and development of diagnostic tools
predictive of adverse reactions to warfarin requires a novel approach. A
combination of two strategies, biochemical isolation of allelic variants and
linkage disequilibrium association studies, was used to find an association
between genetic polymorphisms in the candidate genes and warfarin response. A
strong association was found between genetic polymorphisms in six genes,
including VKORC1, CYP2C9, PROC, EPHX1, GGCX, and ORM1, and interindividual
variability in the anticoagulant effect of warfarin; the strongest predictors
were VKORC1 and CYP2C9. Generation of single nucleotide polymorphism (SNP)-based
dense genetic maps made it possible to identify haplotypes associated with
drugresponse phenotypes. Discrimination between haplotypes associated with
warfarin dose phenotypes can be achieved by a limited set of informative
polymorphisms (tag SNPs). The use of tag SNPs in pharmacogenomic analysis
provides a promising tool for dissecting polygenic traits of drug response. INTRODUCTION: African-Americans are under-represented in studies assessing
contributors to warfarin response. Our primary objective was to determine
whether the genes for cytochrome P450 (CYP) 2C9, nicotinamide adenine
dinucleotide phosphate, reduced, quinone oxidoreductase (NQO1) and vitamin K
epoxide reductase complex subunit 1 (VKORC1) are associated with warfarin dose
requirements in African-Americans.
PATIENTS AND METHODS: The following factors were assessed: demographics;
clinical data; the CYP2C9 Arg144Cys (*2), Ile358Leu (*3) and Asp360Glu (*5);
NQO1 Pro187Ser (*1/*2); and VKORC1 G6853C genotypes were analyzed in 115
African-Americans on stable warfarin doses.
RESULTS: Allele frequencies were 0.05 for the CYP2C9 *2, *3 or *5 alleles; 0.20
for NQO1 *2; and 0.25 for VKORC1 6853C. Possession of a CYP2C9*2, *3 or *5
allele was associated with a 38% lower warfarin dose compared with the *1/*1
genotype (30 +/- 13 vs 48 +/- 18 mg/week; p = 0.003). Neither the NQO1 *1/*2 nor
VKORC1 G6853C genotype was associated with warfarin dose requirements in the
population as a whole or in CYP2C9*1 allele homozygotes. Multiple regression
analysis revealed that CYP2C9 genotype (p = 0.015), age (p < 0.001) and body
surface area (p < 0.001) were jointly associated with warfarin dose
requirements, and together explained 33% of the variability in warfarin dose
requirements among African-Americans.
DISCUSSION: Our data suggest that CYP2C9 genotype, age and body size are
important determits of warfarin dose requirements in African-Americans. Our
data further suggest that the VKORC1 G6853C polymorphism alone may not be useful
for predicting warfarin dose requirements in this racial group. Significant interest in the pharmacogenetics of warfarin therapy has been
triggered with the recent package insert update that highlights the potential
role of pharmacogenetics in improving the safety and effectiveness of warfarin.
We review the evidence of the influence of the two key genes of interest, the
cytochrome P450 2C9 gene, CYP2C9, and the vitamin K epoxide reductase complex 1
gene, VKORC1, on warfarin response and discuss the implications of current
knowledge for clinical practice. The influence of CYP2C9 and VKORC1 genotypes on
warfarin dose requirements has been consistently demonstrated in diverse racial
and ethnic patient groups in observational studies and randomized clinical
trials. Dosing algorithms have been developed that incorporate clinical,
demographic, and genetic information to help select a warfarin starting dose.
Furthermore, CYP2C9 variant genotypes have been associated with a significantly
increased risk of serious bleeding events. However, evidence to date from
prospective, controlled studies has not demonstrated an added benefit of
incorporating genotype-guided therapy in improving anticoagulation control or in
preventing or reducing the risk of hemorrhagic or thromboembolic complications.
Research efforts designed to evaluate the effectiveness of genotype-guided
therapy in improving outcomes are under way. However, the routine use of CYP2C9
and VKORC1 genotyping in the general patient population who begin warfarin
therapy is not supported by evidence currently available. Warfarin is the mainstay of anticoagulation therapy worldwide. Its clinical use,
however, is complicated by the fact that it has a narrow therapeutic index with
potential bleeding complications. The dosage requirement of warfarin to produce
therapeutic anticoagulation varies widely among patients. Recently genetic
factors such as the CYP2C9 and VKORC1 genes have been demonstrated to be
determits of warfarin response. CYP2C9 is the enzyme primarily responsible
for the metabolic clearance of the S-etiomer of warfarin. VKORC1 is the
target protein of warfarin which recycles the reduced form of vitamin K, an
essential cofactor in the formation of the vitamin K-dependent clotting factors.
There is strong evidence to support an association between these genetic
variants and a therapeutic dose of warfarin. On the basis of these observations,
the Food and Drug Administration (FDA) approved a labeling change for warfarin
that includes the genetic information of VKORC1 and CYP2C9 as factors
influencing interindividual variability in warfarin dosing. The package insert
as of August 2007 states that "lower initiation doses should be considered for
patients with certain genetic variations in CYP2C9 and VKORC1 enzymes." The FDA
has also approved clinical tests for these genetic variants. However, at this
time, validated dosing algorithm and evidence to support the clinical utility of
genotyping and reliable economic analysis are lacking to recommend for routine
CYP2C9 and VKORC1 testing in every patiens before the initiation of warfarin
therapy. In this review, we present the results of several prospective
randomised controlled trials conducted to test the impact of genotype-guided
warfarin dosing in Caucasian and Asian patients initiating warfarin. Warfarin and other coumarin anticoagulants are widely used clinically, but
currently dosing is determined individually on the basis of patient response.
There is increasing evidence that genetic factors, together with several
non-genetic patient-specific factors, are important determits of stable dose
requirement for these compounds. Genotype for CYP2C9, which encodes the main
cytochrome P450 enzyme that metabolizes warfarin, and VKORC1, the gene encoding
the warfarin target vitamin K epoxide reductase, together account for
approximately 30% of the variability in dose requirement. The past two years
have seen several advances in the area of genetic factors affecting coumarin
anticoagulant response. In particular, prospective studies have taken place to
analyze whether earlier small retrospective studies can be confirmed, and the
question of whether genes other than CYP2C9 and VKORC1 are important in
determining dose requirement has been examined. So far, no strong evidence that
other genes contribute to dose requirement has been found, apart from a minor
but novel role for another cytochrome P450 gene, CYP4F2. A recently published
whole genome association study confirms that the main genes important in
warfarin response are CYP2C9 and VKORC1. Clinical trials comparing
genotype-guided and conventional warfarin initiation have suggested that
genotyping may be of value, but larger studies are still needed to show clear
clinical benefit. Current knowledge of genetic factors affecting other coumarin
anticoagulants is more limited and this area requires further study, as does the
impact of ethnic variation in genes relevant to coumarin responses. Here we
review recent advances in the area of coumarin anticoagulant genetics and its
potential clinical application. BACKGROUND: The Azorean population presents the highest standardized mortality
rate for cardiovascular diseases (CVD) when compared to mainland Portugal and
other populations. Since thrombosis is a common cause of CVD, we assessed four
polymorphisms in three thrombotic risk genes - F5 (G1691A), F2 (G20210A) and
MTHFR (C677T, A1298C), in 469 healthy blood donors from São Miguel Island
(Azores). We also analysed the CYP2C9 (C430T, A1075C) and VKORC1 (G1639A)
variants in fifty-eight individuals with predisposition to thrombosis
(possessing at least one variation in F5 or F2 genes and one in MTHFR) to
evaluate their warfarin drug response genetic profiles.
RESULTS: Among the 469 individuals, the data showed that thrombotic risk allele
frequencies - 1691A (4.9%), 20210A (1.8%), 677T (41.7%) and 1298C (24.8%) - were
similar to other Caucasians, but significantly different from mainland
Portuguese (chi2, p < 0.001). The combined analysis of these variants identified
twenty-two different genetic profiles (genotype order: F5, F2, MTHFR C677T and
A1298C). Complete homozygosity for all wild-type alleles (GG GG CC AA) was
present in 11.7%, being GG GG CT AA (22.4%) the most frequent profile. The
results also demonstrated that 12.4% (58 out of 469) of São Miguel islanders
have increased genetic predisposition to thrombosis. Subsequently, we evaluated
these individuals for their warfarin response genetic profiles. The data showed
that seven out of fifty-eight individuals are poor metabolizers (two with
CYP2C9*2/*2 and five with CYP2C9*2/*3 genotypes). VKORC1 polymorphism analysis
identified twelve individuals (20.7%) with AA genotype, who probably will
require lower doses of warfarin. The joint analysis of CYP2C9 and VKORC1
revealed that 79.3% (46 out of 58) of the individuals carry at least one
polymorphism in these genes. Within these, twenty-five individuals (43.1%) need
intermediate and/or low doses of warfarin, if treatment is started.
CONCLUSION: The present study demonstrated, for the first time, that São Miguel,
and possibly the Azores population, shows significant differences on allele
frequencies of thrombotic risk factors when compared to mainland Portugal. This
research constitutes a primary approach for future studies on CVD, as well as
for the implementation of warfarin dosing protocols using the patient's
genotypic information. Determining the optimal dose of warfarin for frail elderly patients is a
challenging task because of the low dose requirements in such patients, the wide
interindividual variability of response, and the associated risk of bleeding.
The objective of this study was to address the influence of 13 common variations
in eight genes on the maintece dose of warfarin in a cohort of frail elderly
inpatients. For our study, we enrolled 300 Caucasian subjects who were hospital
inpatients, with a mean age of 86.7 +/- 6 years. In addition to age, genetic
variants of VKORC1, CYP2C9, CYP4F2, and EPHX1 were found to be significant
predictor variables for the maintece dose of warfarin, explaining 26.6% of
dose variability. Among 132 patients in whom warfarin therapy was initiated with
the same low-dose regimen, we studied the relative influences of genetic and
nongenetic factors. The time to first international normalized ratio (INR) > or
=2 was influenced by VKORC1 and CYP2C9 genotypes (P = 0.0003 and P = 0.0016,
respectively); individuals with multiple variant alleles were at highest risk
for overanticoagulation (INR >4) (odds ratio, 12.8; 95% confidence interval,
2.73-60.0). In this special population of frail elderly patients with multiple
comorbidities and polypharmacy, we demonstrated the main impact of genetic
factors on warfarin response. PURPOSE: This study was designed to delineate the relative frequency of CYP2C9
and VKORC1 polymorphisms known to affect warfarin response in the highly
heterogeneous Israeli population.
METHODS: Frequencies of CYP2C9 allelic variants CYP2C9*2, CYP2C9*3 and of VKORC1
single nucleotide polymorphisms (snps) -1639G>A and D36Y were determined in
genomic DNA of 438 healthy unrelated Israeli volunteers of Jewish, Druze and
Arab Moslem descent, using allele specific PCR-RFLP. Genotyping results obtained
were confirmed by probe free High Resolution Melt (HRM) Technology.
RESULTS: Arab Moslems had a higher frequency of warfarin "sensitive" CYP2C9*2,
CYP2C9*3 and VKROC1 -1639G>A alleles (0.21, 0.07 and 0.58, respectively) than
both Jews (0.13, 0.11 and 0.57, respectively) and Druze (0.12, 0.06 and 0.53,
respectively). Statistically significant differences were found in CYP2C9*2
between Druze and Moslems (p=0.01) and between Jews and Moslems (p=0.016) and in
CYP2C9*3 between Druze and Jews (p=0.0086). VKORC1(-1639G>A) was the major gene
polymorphism associated with warfarin sensitivity in all 3 subpopulations. In
contrast, the warfarin "resistant" VKORC1 D36Y allele was very rare in the
Israeli population (0-0.015). The results presented demonstrate that allelic
variants in CYP2C9 and VKORC1 are very common in Israel with approximately 95%
of Jews, approximately 84% of Druze and approximately 91% of Arab Moslems
manifesting at least one known warfarin "sensitive" or "resistant" allele.
CONCLUSIONS: Individualized genotype based warfarin therapy is highly relevant
in the Israeli population due to the high incidence of genetic variations
associated with warfarin sensitivity in all 3 non-mixing subpopulations tested. Warfarin-based anticoagulant therapy is associated with large variability in
dose response. Genetic variability in the VKORC1 and CYP2C9 genes is associated
with increased warfarin sensitivity. In addition, rare coding region mutations
in VKORC1 have been associated with resistance to warfarin. VKORC1 and CYP2C9
variability associated with altered warfarin response is less well characterized
in African and mixed-raced populations such as Brazilians. To determine genetic
variability associated with altered warfarin response among Brazilian patients,
sixty-two adult patients with extreme resistance or sensitivity to warfarin were
genotyped for variants in CYP2C9 and VKORC1. Of the 51 patients on low doses of
warfarin, the VKORC1--1639 (3673) G>A polymorphism associated with warfarin
sensitivity was present in 48 (94.1%), including 97% of Caucasians, 82% of
African-descent patients, and all 7 (100%) patients of Indian descent.
Additionally, 52.9% of warfarin sensitive patients had at least one CYP2C9*2 or
CYP2C9*3 decreased metabolism allele, 63.6% of Caucasians and 54% of
African-descent patients. Of the 11 patients on high doses of warfarin,
sequencing of VKORC1 revealed a nonsynonymous V66M mutation in two warfarin
resistant patients, both of African-descent. Brazilian patients requiring low
doses of warfarin have a high frequency of VKORC1 and CYP2C9 variants associated
with warfarin sensitivity. The presence of the rare VKORC1 V66M in two warfarin
high dose outlier patients implies that this variant may be more frequent among
African Brazilians and has implications for future warfarin studies in other
populations of African descent. BACKGROUND: The response to the anticoagulant drug warfarin is greatly affected
by genetic polymorphisms in the VKORC1 and CYP2C9 genes. Genotyping these
polymorphisms has been shown to be important in reducing the time of the trial
and error process for finding the maintece dose of warfarin thus reducing the
risk of adverse effects of the drug.
METHOD: We developed a real-time isothermal DNA amplification system for
genotyping three single nucleotide polymorphisms (SNPs) that influence warfarin
response. For each SNP, real-time isothermal Helicase Dependent Amplification
(HDA) reactions were performed to amplify a DNA fragment containing the SNP.
Amplicons were detected by fluorescently labeled allele specific probes during
real-time HDA amplification.
RESULTS: Fifty clinical samples were analyzed by the HDA-based method,
generating a total of 150 results. Of these, 148 were consistent between the
HDA-based assays and a reference method. The two samples with unresolved
HDA-based test results were repeated and found to be consistent with the
reference method.
CONCLUSION: The HDA-based assays demonstrated a clinically acceptable
performance for genotyping the VKORC1 -1639G>A SNP and two SNPs (430C>T and
1075A>C) for the CYP2C9 enzyme (CYP2C9*2 and CYP2C9*3), all of which are
relevant in warfarin pharmacogenentics. BACKGROUND: Polymorphisms in the genes encoding the cytochrome P450 2C9 enzyme
(CYP2C9) and the vitamin K epoxide reductase (VKORC1) are known to contribute to
variability in sensitivity to coumarins. Patients with certain common genetic
variants of CYP2C9 (*2 & *3) or a VKORC1 polymorphism (-1639A Allele) require a
lower dose of coumarin and are also at higher risk for over-anticoagulation and
serious bleeding. In August 2007, the FDA label for warfarin was updated to
highlight the benefit of genetic testing to predict warfarin response.
AIM: Since the prevalence of these variants in the Lebanese population has not
yet been reported, our aim was to determine the genotypes of CYP2C9 and VKORC1
in our population and to compare allele frequencies with previous findings from
other ethnic groups.
MATERIALS AND METHODS: CYP2C9 (*1/*2/*3) and VKORC1 (*A/*G) allelic variants
were assessed by polymerase chain reaction-restriction fragment length
polymorphism assays in a diversified sample of 161 unrelated healthy Lebanese
volunteers.
RESULTS: The allele frequencies of CYP2C9 *2 and *3 were 0.112 and 0.096
respectively, whereas VKORC1-1639A was 0.528. Carriers of the CYP2C9 *2 or *3
represented 34.2% of the subjects, whereas those of the VKORC1-1639A represented
73.9%.
CONCLUSION: Our data show no significant difference in the frequency of CYP2C9
allelic variants when compared to the Caucasian population, whereas the allelic
frequency of VKORC1-1639A was very high. Over 50% of the Lebanese population
seem to be carrying more than two independent risk alleles, and is therefore
potentially at high risk of over-anticoagulation. INTRODUCTION: Warfarin is an anticoagulant that is difficult to administer
because of its narrow therapeutic margin and the numerous factors that influence
patient response.
OBJECTIVE: Demographic, clinical and genetic variables were characterized to
establish the appropriate maintece dosages of warfarin.
MATERIALS AND METHODS: The Colombian patients consisted of 145 adults of both
sexes. They were in stable anticoagulation status with international normalized
ratio between 2 and 3 for at least two months, and without changes in the
warfarin commercial preparation or in the dosage. After signing the informed
consent, the following data was recorded for each volunteer: age, gender,
weight, height, smoker status, co-morbidity, co-medication, International
Normalized Ratio (INR), warfarin dose, and commercial brand. Each patient was
typed for genes CYP2C9, VKORC1, CYP4F2 and PROC; for 59 patients, the serum
levels of warfarin were quantified. The genotyping and the blood quantification
were performed by mini-sequencing and HPLC methods, respectively.
RESULTS: Age, co-medication with enzymatic inhibitors (amiodarone, sertraline,
fluoxetine) or inducers (phenytoin, carbamazepine), and the alleles rs1799853
(*2) and rs1057910 (*3) of the CYP2C9 gene, as well as rs9923231 of the VKORC1
gene were associated with warfarin dose required to achieve anticoagulation with
INR of 2-3. These variables were included in a multiple linear regression model
for predicting the optimum dose/week of warfarin. This resulted in an algorithm
that explained 47.4% of the variability in the dose responses.
CONCLUSION: Clinical and pharmacogenetic variables provided a basis for
improving the safety and effective dosage of warfarin; however, the use of a
pharmacogenetic algorithm will require patient data obtained during clinical
trials. Warfarin is a commonly used oral anticoagulant with a narrow therapeutic range
and large interindividual variability in daily dose. Compared with Caucasians,
Chinese are known to require lower doses of warfarin. Differences between
Caucasians and Chinese in the allelic frequencies of two genes, CYP2C9 and
VKORC1, largely explain the difference in dose requirement. There are other
genetic polymorphisms that may further explain the response to warfarin. The
VKORC1 genotype is an important determit of response to warfarin in Chinese,
but some genetic variants found in other ethnic groups that have a large effect
on warfarin response and dosing are not commonly found in Chinese. Therefore, it
is important to recognize and beware of ethnic differences in the
pharmacogenetics of the response to warfarin, especially in the design of
algorithms to aid dosing in clinical practice. OBJECTIVE: To investigate potential contributions of genetic variants of
cytochrome P-450 2C9 (CYP2C9) and vitamin K expoxide reductase (VKORC1) to the
anticoagulation response during the initiation of warfarin therapy in the Han
Chinese population.
METHODS: A total of 798 Han Chinese patients received long-term warfarin
anticoagulant therapy orally after valve replacement in our hospital between
2000 and 2008 were included in this study. Nine single nucleotide polymorphism
(SNP) loci [rs12572351 G > A, rs9332146 G > A, rs4917639 G > T, rs1057910 A > C
(CYP2C9(*)3), rs1934967 G > T, rs1934968 G > A, rs9923231 C > T (VKORC1-1639 G >
A), rs2359612 G > A and rs10871454 C > T] in 2 genes including CYP2C9 and
VKORC1, which were possibly correlated with warfarin pharmacokinetics and
pharmacodynamics through literature retrieval, were selected and analyzed.
Warfarin steady-state dose requirement, time to the INR (the international
normalized ratio) within the therapeutic range and percent of the INR of more
than 3.5 were compared among genotype subgroups. SNaPshot technique was used to
detect gene SNPs; Hardy-Weinberg genetic equilibrium test was used to test
population representativeness.
RESULTS: CYP2C9(*)3 genotype did not affect the required warfarin dose while it
was associated with increased risk of bleeding when treated with routine dosage
regimen during the initiation of treatment. The allelic mutation frequency at
VKORC1 gene rs10871454G > A and VKORC1-1639G > A SNP loci was 92.04% and 88.03%,
respectively and rs10871454 was in perfect linkage disequilibrium with-1639.
Patients with VKORC1 rs10871454 genetic mutation required lower warfarin dose in
the first 28 days of therapy. VKORC1-1639 genetic polymorphism was also
associated with shorter time to the INR within the therapeutic range and
increased risk of over-anticoagulation.
CONCLUSION: Detecting genetic polymorphism of CYP2C9 and VKORC1 could guide
clinical use of warfarin to reduce the risk of adverse reactions including
bleeding in patients receiving chronic anticoagulation therapy. BACKGROUND: Warfarin is a highly effective anticoagulant however its
effectiveness relies on maintaining INR in therapeutic range. Finding the
correct dose is difficult due to large inter-individual variability. Two genes,
CYP2C9 and VKORC1, have been associated with this variability, leading to
genotype-guided dosing tables in warfarin labeling. Nonetheless, it remains
unclear how genotypic information should be used in practice. Navigating the
literature to determine how genotype will influence warfarin response in a
particular patient is difficult, due to significant variation in patient
ethnicity, outcomes investigated, study design, and methodological rigor. Our
systematic review was conducted to enable fair and accurate interpretation of
which variants affect which outcomes, in which patients, and to what extent.
METHODOLOGY/PRINCIPAL FINDINGS: A comprehensive search strategy was applied and
117 studies included. Primary outcomes were stable dose, time to stable dose and
bleeding events. Methodological quality was assessed using criteria of Jorgensen
and Williamson and data synthesized in meta-analyses using advanced methods.
Pooled effect estimates were significant in most ethnic groups for CYP2C9*3 and
stable dose (mutant types requiring between 1.1(0.7-1.5) and 2.3
(1.6-3.0)mg/day). Effect estimates were also significant for VKORC1 and stable
dose for most ethnicities, although direction differed between asians and
non-asians (mutant types requiring between 0.8(0.4-1.3) and 1.5(1.1-1.8)mg/day
more in asians and between 1.5(0.7-2.2) and 3.1(2.7-3.6)mg/day less in
non-asians). Several studies were excluded due to inadequate data reporting.
Assessing study quality highlighted significant variability in methodological
rigor. Notably, there was significant evidence of selective reporting, of
outcomes and analysis approaches.
CONCLUSIONS/SIGNIFICANCE: Genetic associations with warfarin response vary
between ethnicities. In order to achieve unbiased estimates in different
populations, a high level of methodological rigor must be maintained and studies
should report sufficient data to enable inclusion in meta-analyses. We propose
minimum reporting requirements, suggest methodological guidelines and provide
recommendations for reducing the risk of selective reporting. PURPOSE: ORM1 is a plasma drug binding protein. Its polymorphism rs17650 (S>F)
has been reported to be an important factor affecting the binding ability and
effect of antiretroviral protease inhibitors. The aim of this study was to
determine whether the ORM1 rs17650 polymorphism also influences warfarin
therapy.
METHODS: A total of 191 Chinese patients with steady-dose warfarin therapy were
enrolled in this study. The patients were studied for warfarin maintece dose,
the ORM1 rs17650 polymorphism, and two polymorphisms previously demonstrated to
affect warfarin response [CYP2C9 rs1057910 (3) and VKORC1 rs7294 (-1639 G>A)].
RESULTS: Warfarin dose was partially correlated with the VKORC1 rs7294, CYP2C9
rs1057910 and ORM1 rs17650 polymorphisms. Patients carrying the wild-type of
these three genes (n = 96) took a mean dose of 3.0 ± 1.1 mg warfarin, which was
significantly higher than that taken by the 52 S patients (2.7 ± 0.7) and 11 S S
patients (2.5 ± 0.6 mg) (p = 0.048).
CONCLUSION: We identified ORM1 as another polymorphic gene affecting warfarin
dose requirements. ORM1 S carriers require lower maintece doses to achieve
and maintain an optimal level of anticoagulation. Warfarin is a frequently prescribed anticoagulant in rehabilitation patients.
Adverse drug reactions of warfarin were reported as bleeding and cutaneous
microvascular thrombosis. Major bleeding, such as intracranial hemorrhage and
psoas hematoma, in patients receiving anticoagulation therapy is a rare
condition, but sometimes very serious complication that can even be fatal.
Patient-specific factors (eg, age, body size, race, concurrent diseases, and
medications) explain some of the individual variability in warfarin dose, but
genetic factors, which influence warfarin response, explain a significantly
higher proportion of the variability in the dose. There are two identified genes
that are responsible for the main proportion of the genetic effect: CYP2C9,
which codes for the enzyme cytochrome P450 2C9 that metabolizes S-warfarin, and
VKORC1, which codes for warfarin's target, vitamin K epoxide reductase. We
report a case of intolerance to warfarin dosing, due to impaired drug metabolism
in a patient with CYP2C9(*)1/(*)3 and VKORC 1173TT. Fortunately, there are no
severe complications. |
Which is the molecular weight of the protein angiogenin? | The molecular weight of angiogenin is 14,120 Da. The bovine angiogenin is 14,595 Da | Angiogenin is a potent blood-vessel-inducing polypeptide with a molecular weight
of 14,000 that has a unique ribonucleolytic activity. First isolated from the
conditioned medium of tumour cells, angiogenin has since been purified from
normal plasma, which suggested that its propensity to induce neovascularization
should be strictly controlled. Modulation of that activity might involve
interaction of angiogenin with cell-surface receptors and extracellular matrix
of endothelial cells, tight-binding inhibition of both its ribonucleolytic
activity and cell binding property by ribonuclease inhibitor, as well as the
overall influence of divalent copper, a modulator of angiogenesis. The amino acid sequence and disulfide bridges of bovine plasma derived
angiogenin were determined by sequencer analysis of the intact protein and
fragments derived by enzymatic and chemical digestion. Bovine angiogenin is a
single-chain protein of 125 amino acids; it contains six cysteines and has a
calculated molecular weight of 14,595. In contrast to the human protein its
amino terminus is unblocked. It has the following sequence:
H2N-Ala1-Gln-Asp-Asp-Tyr-Arg-Tyr-Ile-His-Phe10-Leu-Thr-Gln-His-Tyr -Asp-Ala-Lys-
Pro-Lys20-Gly-Arg-Asn-Asp-Glu-Tyr-Cys-Phe-Asn-Met30-Met-Lys- Asn-Arg-Arg-Leu-Thr
- Arg-Pro-Cys40-Lys-Asp-Arg-Asn-Thr-Phe-Ile-His-Gly-Asn50-Lys-
Asn-Asp-Ile-Lys-Ala -
Ile-Cys-Glu-Asp60-Arg-Asn-Gly-Gln-Pro-Tyr-Arg-Gly-Asp-Leu70- Arg-Ile-Ser-Lys-Ser
- Glu-Phe-Gln-Ile-Thr80-Ile-Cys-Lys-His-Lys-Gly-Ser-Ser-Arg90-
Pro-Pro-Cys-Arg-Tyr -
Gly-Ala-Thr-Glu-Asp100-Ser-Arg-Val-Ile-Val-Val-Gly-Cys-Glu-Asn1 10-Gly-Leu-Pro-
Val-His-Phe-Asp-Glu-Ser-Phe120-Ile-Thr-Pro-Arg-His-OH. Disulfide bonds link
Cys(27)-Cys(82), Cys(40)-Cys(93), and Cys(58)-Cys(108). Bovine angiogenin is 64%
identical with human angiogenin; like the human protein, it is homologous to the
pancreatic ribonucleases, with conservation of active site residues. Two
regions, 6-22 and 65-75, are highly conserved between the angiogenins but are
significantly different from those of the ribonucleases, suggesting a possible
role in the molecules' biological activity. The first human tumor derived protein with in vivo angiogenic activity to be
obtained in pure form has been isolated from serum-free supernatants of an
established human adenocarcinoma cell line (HT-29) and named angiogenin. It was
purified by cation-exchange and reversed-phase high-performance liquid
chromatography; the yield was approximately 0.5 microgram/L of medium.
Biological activity of angiogenin was monitored throughout purification by using
the chick embryo chorioallantoic membrane assay. Statistical evaluation
demonstrates that it displays activity in this system with as little as 35 fmol
per egg. Moreover, only 3.5 pmol is required to induce extensive blood vessel
growth in the rabbit cornea. The amino acid composition of this basic
(isoelectric point greater than 9.5), single-chain protein of molecular weight
approximately 14 400 has been determined. The amino terminus is blocked, and the
carboxyl-terminal residue is proline. Infectious complications are frequent and often lethal in patients with uremia.
Serious alterations in neutrophil function, e.g., phagocytosis, mononuclear cell
activation, cytokine production, complement activation, T-cell function, and
adhesion molecule expression, have been documented in uremic patients. Uremia
per se is a cause of some of these derangements, but much evidence now exists
that blood-membrane interaction during dialysis is responsible for many of these
abnormalities. This is particularly true when bio-incompatible cellulose-based
membranes are used. In many of these patients, newly described granulocyte
inhibitory proteins (GIP) can be demonstrated. These two proteins, GIP I and II
(28 kD and 9.5 kD, respectively, in molecular weight), block effective bacterial
killing, chemotaxis, and oxygen metabolism. It appears that GIP I is a member of
the lightchain family, and GIP II is the advanced glycosilation end product of
beta 2-microglobulin. Another inhibitory protein, degranulation inhibitory
protein (DIP), has been isolated. This protein is 14 kD in molecular weight, and
is identical to the angioplastic factor angiogenin. DIP levels are significantly
elevated in patients undergoing dialysis. Much still needs to be learned about
the interactions of these inhibitory proteins with other soluble inflammatory
mediators and, in particular, cytokines. It is clear, however, that profound
derangements in immune function take place during uremia and dialytic therapy.
Such derangements are likely to play an important role in determining the rate
of recovery of renal function and the patient's ability to respond to septic
insults. Further insights into the pathogenesis of uremic-dialytic immune
dysfunction are already yielding improved patient management and decreased
infection rates. The crystal structure of ribonuclease A (RNase A) in complex with pdUppA-3'-p
[5'-phospho-2'-deoxyuridine-3'-pyrophosphate (P'-->5') adenosine 3'-phosphate]
has been determined at 1.7 A resolution. This dinucleotide is the most potent
low molecular weight inhibitor of RNase A reported to date (K(i) = 27 nM) and is
also effective against two major nonpancreatic RNases: eosinophil-derived
neurotoxin and RNase-4; in all cases, tight binding in large part derives from
the unusual 3',5'-pyrophosphate internucleotide linkage [Russo, N., and Shapiro,
R. (1999) J. Biol. Chem. 274, 14902-14908]. The design of pdUppA-3'-p was based
on the crystal structure of RNase A complexed with 5'-diphosphoadenosine
3'-phosphate (ppA-3'-p) [Leonidas, D. D., Shapiro, R., Irons, L. I., Russo, N.,
and Acharya, K. R. (1997) Biochemistry 36, 5578-5588]. The adenosine of
pdUppA-3'-p adopts an atypical syn conformation not observed for standard
adenosine nucleotides bound to RNase A. This conformation, which allows
extensive interactions with Asn 67, Gln 69, Asn 71, and His 119, is associated
with the placement of the 5'-beta-phosphate of the adenylate, rather than
alpha-phosphate, at the site where substrate phosphodiester bond cleavage
occurs. The contacts of the deoxyuridine 5'-phosphate portion of pdUppA-3'-p
appear to be responsible for the 9-fold increased affinity of this compound as
compared to ppA-3'-p: the uracil base binds to Thr 45 in the same manner as
previous pyrimidine inhibitors, and the terminal 5'-phosphate is positioned to
form medium-range Coulombic interactions with Lys 66. The full potential benefit
of these added interactions is not realized because of compensatory losses of
hydrogen bonds of Lys 7 and Gln 11 with the terminal 3'-phosphate and the
adenylate 5'-alpha-phosphate, which were not predicted by modeling. The results
reported here have important implications for the design of improved inhibitors
of RNase A and for the development of therapeutic agents to control the
activities of RNase homologues such as eosinophil-derived neurotoxin and
angiogenin that have roles in human pathologies. This paper reports the isolation and characterization from bovine milk of two
proteins: angiogenin-1, a recently discovered angiogenin, and lactogenin, a
novel protein. Both proteins were adsorbed on and eluted closely from
CM-Sepharose and Mono S. Lactogenin possessed a molecular weight (17 kDa)
slightly higher than that of angiogenin-1 (15 kDa). Lactogenin had a higher
ribonucleolytic (RNase) activity than angiogenin-1 towards yeast transfer RNA
(tRNA). The Km values estimated for the RNase activities of angiogenin-1 and
lactogenin were 51 microM and 40 microM respectively. Both were specific for
poly C. The optimal pH for the RNase activities of angiogenin-1 and lactogenin
was 7.75 and 7.5 respectively. Comparison of the amino acid sequences of
cyanogen bromide fragments and the pyroglutaminase-treated N-terminal fragment
of lactogenin with the sequence of bovine liver RNase (RNase BL4) revealed
identity in residues 3-22, 24, 26-27, 37, 41-44, 46-50, 54, 56, 63, 72-80, and
83. Considerable similarity to the N-terminal sequence of angiogenin-2 was also
noted. Both lactogenin and angiogenin-1 inhibited cell-free translation in a
rabbit reticulocyte lysate system with an IC(50) below 100 nM. Human angiogenin is a 14-kDa plasma protein with angiogenic and ribonucleolytic
activities. Angiogenin binds specifically to aortic smooth muscle cells,
activates second messenger pathways, and inhibits their proliferation. Human and
bovine aortic smooth muscle cells were used to study the internalization and
intracellular fate of human angiogenin at 37 degrees C. Using a specific
antibody against angiogenin, we found that the internalized native protein was
localized in the perinuclear region at 30 min and then dispersed throughout the
cytoplasm. In conditions favoring receptor-mediated endocytosis, internalization
of iodinated angiogenin showed a first peak at 5 min and then further increased
for up to 24 h. The half-life of the molecule, calculated as 12 h in chase
experiments, could contribute to its intracellular accumulation. In cell
extracts, in addition to the 14-kDa protein, a 8.7-kDa fragment was observed at
24 h, and three fragments with molecular mass of 10.5, 8.7, and 6. 1 kDa were
detected at 48 h. Our data point to a specific internalization and processing of
human angiogenin by aortic smooth muscle cells. |
List sodium glucose co-transporter-2 (SGLT2) inhibitors that have been FDA approved for type 2 diabetes mellitus treatment. | Canagliflozin, along with dapagliflozin and empagliflozin, are SGLT2 inhibitors approved by the US FDA for use in the treatment of type 2 diabetes. | OBJECTIVE: To review the literature and describe the pharmacologic,
pharmacokinetic, and pharmacodynamic properties; clinical safety; and efficacy
of dapagliflozin, a new drug currently under review by the Food and Drug
Administration (FDA) for the treatment of type 2 diabetes.
DATA SOURCES: A MEDLINE (1995-November 2011) and ClinicalTrials.gov search was
conducted using the terms dapagliflozin, sodium-glucose cotransporter 2
inhibitor, and SGLT2 inhibitor. Reference citations from publications identified
were also reviewed.
STUDY SELECTION AND DATA EXTRACTION: All English-language studies, including
abstracts, evaluating dapagliflozin use in humans were included in this review.
DATA SYNTHESIS: Dapagliflozin is the first-in-class oral sodium-glucose
cotransporter 2 (SGLT2) inhibitor that represents a new potential therapeutic
option for the treatment of type 2 diabetes mellitus. Its mechanism of action is
insulin- and insulin-sensitivity independent. Preliminary data suggest that
dapagliflozin decreases hemoglobin A(1c), fasting plasma glucose, and
postprandial plasma glucose, while also promoting weight loss. In Phase 1, 2,
and 3 clinical trials, dapagliflozin has exhibited a safety and tolerability
profile similar to that of placebo.
CONCLUSIONS: Dapagliflozin is a novel oral antihyperglycemic agent that has
demonstrated promise as monotherapy and as synergistic combination therapy with
currently available agents in Phase 3 clinical trials. On January 19, 2012, the
FDA issued a complete response letter to AstraZeneca and Bristol-Myers Squibb
regarding the new drug application for dapagliflozin. The FDA is requesting
additional clinical data-from ongoing studies and potentially new clinical
trials-to better describe the risk-benefit profile of the drug. Both
manufacturers remain committed to the development of dapagliflozin, and there
are currently 8 Phase 3 trials ongoing. Dapagliflozin has the potential to be
the next new oral agent in the diabetes drug armamentarium. OBJECTIVE: To examine the effects of canagliflozin, a sodium glucose
co-transporter 2 inhibitor that lowers blood glucose by increasing urinary
glucose excretion (UGE), on asymptomatic bacteriuria and urinary tract
infections (UTIs).
RESEARCH DESIGN AND METHODS: In a randomized, double-blind, placebo-controlled,
multicenter, dose-ranging phase 2 study, subjects with type 2 diabetes with
inadequate glycemic control while receiving metformin were enrolled and
randomized to one of seven arms - placebo; canagliflozin doses 50 mg, 100 mg,
200 mg, 300 mg daily, or 300 mg twice daily; and sitagliptin 100 mg daily - for
12 weeks.
CLINICAL TRIAL REGISTRATION: This study is registered under Clinicaltrials.gov
identification number NCT00642278.
RESULTS: Canagliflozin increased renal glucose excretion by 35.4-61.6 mg/mg
creatinine in the five dose groups. In the placebo group renal glucose excretion
was increased by 1.9 mg/mg creatinine, and in the sitagliptin group it decreased
by 1.9 mg/mg creatinine. Asymptomatic bacteriuria (ASB) were present in 6.4% of
canagliflozin and 6.5% of placebo/sitagliptin (control) subjects at
randomization and, at 12 weeks, in 7.7% and 6.3% of subjects, respectively (odds
ratio [OR] 1.23; 95% confidence interval [CI], 0.45-3.89). For subjects with
initially negative urine cultures at baseline, 3 out of 82 (3.7%) who received
controls and 10 out of 207 (4.8%) who received canagliflozin developed
bacteriuria (p = 0.76) at week 12. There were 21 adverse event (AE) reports of
UTI; 16 (5.0%) in canagliflozin subjects and 5 (3.8%) in control subjects (OR
1.31; 95% CI, 0.45-4.68).
CONCLUSIONS: In this trial, when compared with control subjects, canagliflozin
increased UGE but was not associated with increased bacteriuria or AE reports of
UTI. However, further studies enrolling larger numbers of subjects with longer
term exposure to canagliflozin will be necessary to more fully understand the
impact of this agent on the risk of developing UTI. INTRODUCTION: Maintece of glucose homeostasis in healthy individuals involves
SGLT2 (sodium glucose co-transporter 2)-mediated recovery of glucose from the
glomerular filtrate which otherwise would be excreted in urine. Clinical studies
indicate that SGLT2 inhibitors provide an insulin-independent means to reduce
the hyperglycemia that is the hallmark of type 2 diabetes mellitus (T2DM) with
minimal risk of hypoglycemia.
AREAS COVERED: The pharmacophore common to the SGLT2 inhibitors currently in
development is a diarylmethane C-glucoside which is discussed in this review.
The focus is how this pharmacophore was further modified as inferred from the
patents publishing from 2009 to 2011. The emphasis is on the strategy that each
group employed to circumvent the constraints imposed by prior art and how the
resulting SGLT2 potency and selectivity versus SGLT1 compared with that of the
lead clinical compound dapagliflozin.
EXPERT OPINION: SGLT2 inhibitors offer a new fundamentally different approach
for treatment of diabetes. To date, the clinical results suggest that for
non-renally impaired patients this class of inhibitors could be safely used at
any stage of T2DM either alone or in combination with other marketed
antidiabetic medications. BACKGROUND/OBJECTIVE: Women with type 2 diabetes mellitus (T2DM) are at
increased risk for vaginal Candida colonization, perhaps because of glucosuria.
Sodium glucose co-transporter 2 (SGLT2) inhibitors, in development for the
treatment of T2DM, improve glycemic control by increasing urinary glucose
excretion. Vaginal Candida colonization and symptomatic vulvovaginal adverse
events (VVAE) were assessed in females with T2DM treated with canagliflozin, a
SGLT2 inhibitor.
METHODS: In a double-blind study, subjects with T2DM and inadequate glycemic
control on metformin were randomized to placebo; canagliflozin 50, 100, 200,
300 mg daily or 300 mg twice daily; or sitagliptin 100 mg daily for 12 weeks.
Vaginal swabs for Candida culture were collected from 198 female subjects at
baseline and week 12, and during the trial if symptoms consistent with
vulvovaginal candidiasis occurred.
RESULTS: At baseline, 23/198 (12%) females had vaginal cultures positive for
Candida (C. glabrata: 14; C. albicans: 5; other: 4), with age ≤55 years
associated with increased risk (odds ratio [OR], 3.5; 95% confidence interval
[CI], 1.1-10.7). Of those with negative cultures at baseline, 31% of
canagliflozin and 14% of placebo/sitagliptin subjects converted to positive at
week 12 (OR, 2.8; 95% CI, 1.0-7.3 for canagliflozin vs. placebo/sitagliptin).
Two placebo/sitagliptin (3%) and 16 canagliflozin subjects (10%) experienced
VVAE. Positive vaginal culture for Candida species at baseline was a risk factor
for VVAE (OR, 9.1; 95% CI, 2.4-34.0). All 9/9 subjects in the canagliflozin
group with a vaginal culture taken at the time of the VVAE were positive for
Candida species. Most VVAE were treated with antifungal therapy and resolved
without study drug interruption; none led to discontinuation. Study limitations
include small population, short duration, and not obtaining cultures in all
women with VVAE.
CONCLUSION: Canagliflozin treatment was associated with an increase in vaginal
colonization with Candida species and in VVAE in women with T2DM. Canagliflozin (Invokana™), an oral selective sodium-glucose co-transporter 2
(SGLT2) inhibitor, is under global development with Mitsubishi Tanabe Pharma and
Janssen Pharmaceuticals, a subsidiary of Johnson and Johnson, for the treatment
of type 2 diabetes mellitus. SGLT2 are mainly located in the proximal tubule of
the kidney and are involved in the reabsorption of filtered glucose from the
glomeruli into the body. Inhibition of SGLT2 lowers blood glucose in an insulin
independent manner as a consequence of blocking reabsorption of filtered glucose
in the glomeruli, thereby increasing urinary excretion of glucose and, in turn,
potentially reducing bodyweight. Canagliflozin is the first SGLT2 inhibitor to
be approved in the USA and is under regulatory review in the EU. This article
summarizes the milestones in the development of canagliflozin, leading to its
first approval for use in adults with type 2 diabetes. The sodium glucose cotransporter 2 (SGLT2) is expressed primarily in the kidneys
and is involved in the reabsorption of filtered glucose in the renal tubule.
Clinical trials of SGLT2 inhibitors in patients with type 2 diabetes mellitus
demonstrate a significant clinical effect in decreasing serum glucose,
hemoglobin A1C, body weight, systolic blood pressure, improving β-cell function,
and minimizing the risk of hypoglycemia. This report reviews the potentially
beneficial effects of SGLT2 inhibitors in type 2 diabetes mellitus, specifically
focusing on canagliflozin, the only SGLT2 inhibitor approved for use in the
United States. Sodium-glucose co-transporters (SGLT2) are mainly expressed in the kidneys and
are responsible for the renal handling of glucose load. SGLT2 inhibitors
represent the latest oral agents for diabetes treatment. Their unique mechanism
of action, which practically spares the insulin secretion or insulin
utilization, differentiates the SGLT2 inhibitors from any existing antidiabetic
agent. Thus, it is hypothesized that SGLT2 inhibitors can be effectively (and
probably safely) combined with any existing antidiabetic agent (including
insulin), either as monotherapy, or in dual or triple combinations. All these
hypotheses are currently tested in many clinical trials. Currently
dapagliflozin, one of the three most advanced SGLT2 inhibitors in the
development (along with canagliflozin and empagliflozin), is already in the
market in few European countries and canagliflozin has been approved from the
Food and Drug Administration (FDA) in US. The evidence so far shows that SGLT2
inhibitors are equally effective to established antidiabetic agents such as
metformin or sulfonylureas in their ability to lower HbA1c. On the other hand,
SGLT2 inhibitors increase the possibility of genitourinary infections in type 2
diabetic individuals. Their potency in different populations and with different
background therapy, but more importantly their short and long term safety
remains to be seen. Acetylcholinesterase (AChE) is a primary target for Alzheimer's therapy while
recently sodium glucose cotransporter 2 (SGLT2) has gained importance as a
potential target for Type 2 Diabetes Mellitus (T2DM) therapy. The present study
emphasizes the molecular interactions between a new Food and Drug Administration
(FDA) approved antidiabetic drug 'Invokana' (chemically known as Canagliflozin)
with AChE and SGLT2 to establish a link between the treatment of T2DM and
Alzheimer's Disease (AD). Docking study was performed using 'Autodock4.2'. Both
hydrophobic and π-π interactions play an important role in the correct
positioning of Canagliflozin within SGLT2 and catalytic site (CAS) of AChE to
permit docking. Free energy of binding (ΔG) for 'Canagliflozin-SGLT2'
interaction and 'Canagliflozin - CAS domain of AChE' interaction were found to
be -10.03 kcal/mol and -9.40 kcal/mol, respectively. During
'Canagliflozin-SGLT2' interaction, Canagliflozin was found to interact with the
most important amino acid residue Q457 of SGLT2. This residue is known for its
interaction with glucose during reabsorption in kidney. However,
'Canagliflozin-CAS domain of AChE' interaction revealed that out of the three
amino acids constituting the catalytic triad (S203, H447 and E334), two amino
acid residues (S203 and H447) interact with Canagliflozin. Hence, Invokana
(Canagliflozin) might act as a potent dual inhibitor of AChE and SGLT2. However,
scope still remains in the determination of the three-dimensional structure of
SGLT2-Canagliflozin and AChE-Canagliflozin complexes by X-ray crystallography to
validate the described data. Since the development of diabetes is associated
with AD, the design of new AChE inhibitors based on antidiabetic drug scaffolds
would be particularly beneficial. Moreover, the present computational study
reveals that Invokana (Canagliflozin) is expected to form the basis of a future
dual therapy against diabetes associated neurological disorders. Treatment of type 2 diabetes (T2DM) continues to present challenges, with
significant proportion of patients failing to achieve and maintain glycemic
targets. Despite the availability of many oral antidiabetic agents, therapeutic
efficacy is offset by side effects such as weight gain and hypoglycemia.
Therefore, the search for novel therapeutic agents with an improved benefit-risk
profile continues. Recent research has focused on the kidney as a potential
therapeutic target, especially because maximal renal glucose reabsorption is
increased in T2DM. Under normal physiological conditions, nearly all filtered
glucose is reabsorbed in the proximal tubule of the nephron, principally via the
sodium-glucose cotransporter 2 (SGLT2). SGLT2-inhibitors are a new class of oral
antidiabetics, which reduce hyperglycemia by increasing urinary glucose
excretion independently of insulin secretion or action. Clinical results are
promising with significant lowering of HbA1c without increased risk of
hypoglycemia, reduction of body weight and reduction of systolic blood pressure.
Dapagliflozin is the first highly selective SGLT2-inhibitor approved by the
European Medecine Agency. Canagliflozin and empagliflozin are undergoing phase
III trials. Actual safety issues are an increased risk for genital- and urinary
tract infections and a possible increased risk for bladder and breast cancer.
This led to refusal of dapagliflozin by the Food and Drug Administration (FDA).
A large randomized control trial is therefore warranted by the FDA. This review
provides an overview of the current evidence available so far on the therapeutic
potential of the SGLT2-inhibitors for the treatment of T2DM. AIMS/HYPOTHESIS: In rodent models of diabetes, treatment with sodium glucose
co-transporter 2 (SGLT2) inhibitors improves beta cell function. This analysis
assessed the effects of the SGLT2 inhibitor, canagliflozin, on model-based
measures of beta cell function in patients with type 2 diabetes.
METHODS: Data from three Phase 3 studies were analysed, in which: (Study 1)
canagliflozin 100 and 300 mg were compared with placebo as monotherapy for 26
weeks; (Study 2) canagliflozin 100 and 300 mg were compared with placebo as
add-on to metformin + sulfonylurea for 26 weeks; or (Study 3) canagliflozin 300
mg was compared with sitagliptin 100 mg as add-on to metformin + sulfonylurea
for 52 weeks. In each study, a subset of patients was given mixed-meal tolerance
tests at baseline and study endpoint, and model-based beta cell function
parameters were calculated from plasma glucose and C-peptide.
RESULTS: In Studies 1 and 2, both canagliflozin doses increased beta cell
glucose sensitivity compared with placebo. Placebo-subtracted least squares mean
(LSM) (SEM) changes were 23 (9) and 18 (9) pmol min(-1) m(-2) (mmol/l)(-1) with
canagliflozin 100 and 300 mg, respectively (p < 0.002, Study 1), and 16 (8) and
10 (9) pmol min(-1) m(-2) (mmol/l)(-1) (p < 0.02, Study 2). In Study 3, beta
cell glucose sensitivity was minimally affected, but the insulin secretion rate
at 9 mmol/l glucose increased to similar degrees from baseline with
canagliflozin and sitagliptin [LSM (SEM) changes 38 (8) and 28 (9) pmol min(-1)
m(-2), respectively; p < 0.05 for both].
CONCLUSIONS/INTERPRETATION: Treatment with canagliflozin for 6 to 12 months
improved model-based measures of beta cell function in three separate Phase 3
studies.
TRIAL REGISTRATION: Clinicaltrials.gov NCT01081834 (Study 1); NCT01106625 (Study
2); NCT01137812 (Study 3). Diabetes mellitus is a greatly challenging disease of the 21 century, and the
mortality rate due to this insidious disease is increasing worldwide in spite of
availability of effective oral hypoglycemic agents. Satisfactory management of
glycemic control in patients afflicted with type 2 diabetes mellitus (T2DM)
remains a major clinical challenge. Identification of potential pharmacological
target sites is therefore continuing as an integral part of the diabetic
research. The sodium-glucose co-transporter type 2 (SGLT2) expressed in the
renal proximal tubule plays an essential role in glucose reabsorption.
Pharmacological blockade of SGLT2 prevents glucose reabsorption and subsequently
induces the elimination of filtered glucose via urine, the process is known as
'glucuresis'. Dapagliflozin is a selective inhibitor of SGLT2. The US FDA
approved dapagliflozin in January 2014 to improve glycemic control along with
diet and exercise in adult patients afflicted with T2DM. It has a potential to
decrease glycated hemoglobin and to promote weight loss. Although the mechanism
of action of dapagliflozin is not directly linked with insulin or insulin
sensitivity, reduction of plasma glucose by dapagliflozin via induction of
glucosuria could improve muscle insulin sensitivity. Moreover, dapagliflozin
could cause diuresis and subsequently fall in blood pressure. In addition to
general discussion on the pharmacology of dapagliflozin, we propose in this
review the possibilities of dual antidiabetic effect of dapagliflozin and its
possible additional beneficial actions in hypertensive-obese-T2DM patients
through its indirect blood pressure-lowering action and reduction of body
calories and weight. Long-term clinical studies are however needed to clarify
this contention. Treatment of type 2 diabetes mellitus (T2DM) continues to present challenges,
with many patients failing to achieve glycemic targets. Despite the availability
of many oral and injectable anti-diabetic agents, therapeutic efficacy is often
offset by undesirable side effects such as hypoglycemia, weight gain and
cardiovascular complications. Therefore, the search for new therapeutic agents
with an improved benefit-risk profile continues. Recent research has focused on
the kidney as a potential therapeutic target, especially because maximal renal
glucose reabsorption is increased in T2DM. Under normal physiological
conditions, nearly all filtered glucose is reabsorbed in the proximal tubule of
the nephron via the sodium/glucose co-transporter 2 (SGLT2). SGLT2-inhibitors
are a new class of oral anti-diabetes, which reduce hyperglycemia by increasing
urinary glucose excretion independently of insulin secretion or action.
Canagliflozin and dapagliflozin in US market, and ipragliflozin and
luseogliflozin in Japan market are now available for glycemic control in type 2
diabetics. There are several phase III clinical ongoing trials involving this
new class of medications. This review examines some of the key efficacy and
safety data from clinical trials of the SGLT2 inhibitors approved, and their
future perspectives in the treatment of T2DM. BACKGROUND/AIMS: Some sodium glucose co-transporter 2 (SGLT2) inhibitors are
approved for the treatment of patients with type 2 diabetes mellitus (T2DM) with
an estimated glomerular filtration rate (eGFR) of ≥45 ml/min/1.73 m(2). The
efficacy and safety of canagliflozin, an approved SGLT2 inhibitor, was evaluated
in patients with stage 3 chronic kidney disease (CKD; eGFR ≥30 to <60
ml/min/1.73 m(2)).
METHODS: This analysis used integrated data from four randomized,
placebo-controlled, phase 3 studies that enrolled patients with T2DM and stage 3
CKD. RESULTS are presented for the overall population as well as subgroups with
stage 3a CKD (eGFR ≥45 and <60 ml/min/1.73 m(2)) and stage 3b CKD (eGFR ≥30 and
<45 ml/min/1.73 m(2)).
RESULTS: Among all subjects studied with stage 3 CKD, placebo-subtracted
reductions in HbA1c (-0.38 and -0.47%; p < 0.001), body weight (-1.6 and -1.9%;
p < 0.001), and systolic blood pressure (-2.8 and -4.4 mm Hg; p < 0.01) were
seen with canagliflozin 100 and 300 mg, respectively. Decreases in HbA1c, body
weight, and systolic blood pressure were examined in the stage 3a and 3b CKD
subgroups, with greater decreases in HbA1c, -0.47% (-0.61, -0.32) and body
weight in subjects in stage 3a CKD, -1.8% (-2.3, -1.2) with canagliflozin 100
mg. Initial declines in eGFR were seen early following treatment initiation with
canagliflozin, but trended towards baseline over time. The most common adverse
events with canagliflozin included genital mycotic infections and adverse events
related to reduced intravascular volume likely secondary to osmotic diuresis.
CONCLUSION: In subjects with T2DM and stage 3 CKD, canagliflozin reduced HbA1c,
body weight, and blood pressure, and was generally well tolerated. The kidney plays a key role in glucose homeostasis and the pathophysiology of
type 2 diabetes mellitus (T2DM). Sodium glucose co-transporter 2 (SGLT2)
inhibitors are a new class of antihyperglycemic agents for the treatment of T2DM
with a novel insulin-independent mechanism of action that targets the kidney.
The SGLT2 inhibitors decrease renal glucose reabsorption, thereby increasing
urinary glucose excretion and lowering plasma glucose levels in patients with
hyperglycemia. SGLT2 inhibitor canagliflozin has demonstrated efficacy in
improving glycemic control and reducing body weight and blood pressure as
monotherapy or as add-on to other antihyperglycemic agents across a broad range
of patients with T2DM. Canagliflozin is generally well tolerated, with increased
incidences of specific adverse events that are related to the mechanism of SGLT2
inhibition. Findings suggest that canagliflozin is a useful treatment option for
patients with T2DM. Inhibitors of sodium-glucose co-transporter type 2 (SGLT2) are proposed as a
novel approach for the management of type 2 diabetes mellitus (T2DM). Several
compounds are already available in many countries (dapagliflozin, canagliflozin,
empagliflozin and ipragliflozin) and some others are in a late phase of
development. The available SGLT2 inhibitors share similar pharmacokinetic
characteristics, with a rapid oral absorption, a long elimination half-life
allowing once-daily administration, an extensive hepatic metabolism mainly via
glucuronidation to inactive metabolites, the absence of clinically relevant
drug-drug interactions and a low renal elimination as parent drug. SGLT2
co-transporters are responsible for reabsorption of most (90 %) of the glucose
filtered by the kidneys. The pharmacological inhibition of SGLT2 co-transporters
reduces hyperglycaemia by decreasing renal glucose threshold and thereby
increasing urinary glucose excretion. The amount of glucose excreted in the
urine depends on both the level of hyperglycaemia and the glomerular filtration
rate. Results of numerous placebo-controlled randomised clinical trials of
12-104 weeks duration have shown significant reductions in glycated haemoglobin
(HbA1c), resulting in a significant increase in the proportion of patients
reaching HbA1c targets, and a significant lowering of fasting plasma glucose
when SGLT2 inhibitors were administered as monotherapy or in addition to other
glucose-lowering therapies including insulin in patients with T2DM. In
head-to-head trials of up to 2 years, SGLT2 inhibitors exerted similar
glucose-lowering activity to metformin, sulphonylureas or sitagliptin. The
durability of the glucose-lowering effect of SGLT2 inhibitors appears to be
better; however, this remains to be more extensively investigated. The risk of
hypoglycaemia was much lower with SGLT2 inhibitors than with sulphonylureas and
was similarly low as that reported with metformin, pioglitazone or sitagliptin.
Increased renal glucose elimination also assists weight loss and could help to
reduce blood pressure. Both effects were very consistent across the trials and
they represent some advantages for SGLT2 inhibitors when compared with other
oral glucose-lowering agents. The pharmacodynamic response to SGLT2 inhibitors
declines with increasing severity of renal impairment, and prescribing
information for each SGLT2 inhibitor should be consulted regarding dosage
adjustments or restrictions in moderate to severe renal dysfunction. Caution is
also recommended in the elderly population because of a higher risk of renal
impairment, orthostatic hypotension and dehydration, even if the absence of
hypoglycaemia represents an obvious advantage in this population. The overall
effect of SGLT2 inhibitors on the risk of cardiovascular disease is unknown and
will be evaluated in several ongoing prospective placebo-controlled trials with
cardiovascular outcomes. The impact of SGLT2 inhibitors on renal function and
their potential to influence the course of diabetic nephropathy also deserve
more attention. SGLT2 inhibitors are generally well-tolerated. The most
frequently reported adverse events are female genital mycotic infections, while
urinary tract infections are less commonly observed and generally benign. In
conclusion, with their unique mechanism of action that is independent of insulin
secretion and action, SGLT2 inhibitors are a useful addition to the therapeutic
options available for the management of T2DM at any stage in the natural history
of the disease. Although SGLT2 inhibitors have already been extensively
investigated, further studies should even better delineate the best place of
these new glucose-lowering agents in the already rich armamentarium for the
management of T2DM. Although several treatment options are available to reduce hyperglycemia, only
about half of individuals with diagnosed diabetes mellitus (DM) achieve
recommended glycemic targets. New agents that reduce blood glucose
concentrations by novel mechanisms and have acceptable safety profiles are
needed to improve glycemic control and reduce the complications associated with
type 2 diabetes mellitus (T2DM). The renal sodium-glucose co-transporter 2
(SGLT2) is responsible for reabsorption of most of the glucose filtered by the
kidney. Inhibitors of SGLT2 lower blood glucose independent of the secretion and
action of insulin by inhibiting renal reabsorption of glucose, thereby promoting
the increased urinary excretion of excess glucose. Canagliflozin, dapagliflozin,
and empagliflozin are SGLT2 inhibitors approved as treatments for T2DM in the
United States, Europe, and other countries. Canagliflozin, dapagliflozin, and
empagliflozin increase renal excretion of glucose and improve glycemic
parameters in patients with T2DM when used as monotherapy or in combination with
other antihyperglycemic agents. Treatment with SGLT2 inhibitors is associated
with weight reduction, lowered blood pressure, and a low intrinsic propensity to
cause hypoglycemia. Overall, canagliflozin, dapagliflozin, and empagliflozin are
well tolerated. Cases of genital infections and, in some studies, urinary tract
infections have been more frequent in canagliflozin-, dapagliflozin-, and
empagliflozin-treated patients compared with those receiving placebo. Evidence
from clinical trials suggests that SGLT2 inhibitors are a promising new
treatment option for T2DM. OBJECTIVE: To review available studies of empagliflozin, a sodium glucose
co-transporter-2 (SGLT2) inhibitor approved in 2014 by the European Commission
and the United States Food and Drug Administration for the treatment of type 2
diabetes mellitus (T2DM).
DATA SOURCES: PubMed was searched using the search terms empagliflozin, BI
10773, and BI10773, for entries between January 1, 2000, and December 1, 2014.
Reference lists from retrieved articles were searched manually for additional
peer-reviewed publications.
STUDY SELECTION AND DATA EXTRACTION: All publications reporting clinical trials
of empagliflozin were eligible for inclusion.
DATA SYNTHESIS: Empagliflozin is a new once-daily oral SGLT2 inhibitor with a
mechanism of action that is independent of β-cell function and the insulin
pathway. Data from a comprehensive phase III clinical trial program have
demonstrated its efficacy as monotherapy, as add-on to other glucose-lowering
agents, and in different patient populations. In these studies, empagliflozin
resulted in improvements in blood glucose levels as well as reductions in body
weight and blood pressure. Empagliflozin was well tolerated and was not
associated with an increased risk of hypoglycemia versus placebo.
CONCLUSION: The oral antidiabetes agent, empagliflozin, can be used as
monotherapy or alongside other glucose-lowering treatments, including insulin,
to treat T2DM. |
What is the gene mutated in the Gaucher disease? | The glucocerebrosidase gene (GBA) | Gaucher disease is inherited in an autosomal recessive manner and is the most
prevalent lysosomal storage disease. Gaucher disease has marked phenotypic
variation and molecular heterogeneity, and several simple and complex alleles of
the acid beta-glucosidase gene have been identified as causal to this disease.
Certain combinations of alleles have been shown to correlate well with the
severity of the disease, but many Gaucher disease patients exist whose disease
is not explained by any of the published mutations. This study was undertaken to
identify mutant alleles in such incompletely characterized Gaucher disease, in
an attempt to find further correlations between clinical phenotype and the
presence of acid beta-glucosidase alleles. RNA was isolated from Gaucher cell
lines and converted to cDNA, the cDNA was amplified by PCR and cloned, and
several clones for each allele were sequenced. Several new singly mutated and
multiply mutated alleles were identified, and sequence-specific oligonucleotide
hybridization was used to verify the presence of these mutations in the genome
of these patients. All newly identified mutations occurred only rarely in the
Gaucher disease population, making it difficult to determine whether inheritance
of a particular combination of alleles always correlates with the clinical
manifestations seen in the test patients. Three of the newly described alleles
were single missense mutations in exon 8, one was a single missense mutation in
exon 5, and the fifth was a complex allele, comprising a series of different
point mutations scattered throughout exons 5 and 6.(ABSTRACT TRUNCATED AT 250
WORDS) Seven members of an Ashkenazi Jewish family with Gaucher disease in 3 successive
generations were tested for the presence of the 2 common mutations known to
occur in the glucocerebrosidase gene. Genomic DNA from blood or skin fibroblasts
of relatives was amplified by using the PCR technique and individual mutations
identified by oligonucleotides specific to the mutated sequences. Four
individuals were homozygous for a mutation at amino acid 370 (370 mutation)
known to occur only in type 1 disease. The other 3 affected relatives were
compound heterozygotes for this mutation and for a mutation at amino acid 444
(NciI mutation) which, in the homozygous state, is associated with neurological
disease. Clinical severity was more marked in the compound heterozygotes than in
the homozygotes. Since the mutation is present in Ashkenazim, molecular
diagnosis in families which carry the NciI mutation should prove useful in
assessing their risk of the neurologic forms of Gaucher disease. In the Portuguese population the most frequent form of Gaucher disease is type
1. The N370S glucocerebrosidase gene mutation accounts for 63% of mutated
alleles. The frequency of this mutation was accurately determined in the
Portuguese population, which does not present an Ashkenazi Jewish genetic
background. A gene frequency of 0.0043, with 95% confidence limits between
0.0023 and 0.0063, was obtained studying the genomic DNA of 2000 blood cards
randomly sampled from the national neonatal screening program. On the basis of
this frequency a significantly high number of homozygotes for the N370S mutation
should be expected in the Portuguese population. This finding supports the idea
that the majority of homozygotes for this mutation present a very mild clinical
phenotype and remain undiagnosed. The mutation N370S accounts for 63% of the mutated glucocerebrosidase alleles of
Portuguese type 1 Gaucher patients. It has been shown previously that this
mutation is linked to the Pv1.1- form of the PvuII polymorphism and suggested
that the N370S mutation in glucocerebrosidase alleles has an Ashkenazi Jewish
origin. We have found that in Portuguese type 1 Gaucher patients this mutation
is also invariably associated with the Pv1.1- haplotype, despite the fact that
there is no evidence of Ashkenazi Jewish background in this population. The frequency of nine different mutated alleles known to occur in the
glucocerebrosidase gene was determined in 247 Gaucher patients, of whom 176 were
of Jewish extraction, 2 were Jewish with one converted parent, and 69 were of
non-Jewish origin. DNA was prepared from peripheral blood, active
glucocerebrosidase sequences were amplified by using the PCR technique, and the
mutations were identified by using the allele-specific oligonucleotide
hybridization method. The N37OS mutation appeared in 69.77% of the mutated
alleles in Jewish patients and in 22.86% of the mutated alleles in non-Jews. The
84GG mutation, which has not been found so far among non-Jewish patients,
existed in 10.17% of the disease alleles among Jewish patients. The IVS + 1
mutation constituted 2.26% of the disease alleles among Jewish patients and
1.43% among the non-Jewish patients. RecTL, a complex allele containing four
single-base-pair changes, occurred in 2.26% of the alleles in Jewish patients
and was found in two (1.43%) of the patients of non-Jewish extraction. Another
complex allele, designated "RecNciI" and containing three single-point
mutations, appeared in 7.8% of alleles of non-Jewish patients and in only two
(0.56%) of the Jewish families. The prevalence of the L444P mutation among
non-Jewish Gaucher patients was 31.43%, while its prevalence among Jewish
patients was only 4.24%. The prevalence of two other point mutations--D409H and
R463C--was 5.00% and 3.57%, respectively, among non-Jewish patients and was not
found among the Jewish Gaucher patient population. The prevalence of the R496H
mutation, found so far only among Jewish patients, was 1.13%. The results
presented demonstrate that seven mutations identify 90.40% of the mutations
among Jewish patients and that these seven mutations allow diagnosis of only
73.52% of the non-Jewish patients. Identification of additional mutant alleles
will enhance the accuracy of carrier detection. Mutation screening of the glucocerebrosidase gene by SSCP analysis revealed an
abnormal pattern of exon 10 in two unrelated Italian Gaucher patients. Direct
sequencing of the mutated samples identified a G6490-->A transition. The same
mutation has been described before in a Japanese patient with Gaucher disease
type III. The clinical phenotype of our patients was type I in one whose second
allele carried the N370S mutation and type II in the other one with a L444P
mutation. In this latter the G6490-->A substitution cancels a normal Msp I site,
while on the opposite chromosome the T6433-->C mutation (L444P) introduces a new
Msp I site. Thus, digestion with Msp I of the amplified exon 10 is a useful
method for identifying the two mutations simultaneously. Gaucher disease, resulting from the decreased activity of the lysosomal enzyme
glucocerebrosidase, is the most prevalent sphingolipid storage disease. Due to
considerable heterogeneity of phenotypic expression, it has been subdivided into
the nonneurological type 1 disease, and types 2 and 3, the neurological types.
We describe homozygosity for the D409H mutation within the glucocerebrosidase
gene associated with a unique form of type 3 Gaucher disease. Twelve patients,
originating from three Arab sibships, were found to be homozygous for the D409H
mutation. They all presented with oculomotor apraxia and a progressive cardiac
valve defect with minimal organomegaly. When expressed in human cells in tissue
culture, using the T7/EMC/vaccinia virus hybrid expression system, we were able
to demonstrate that the mRNA carrying the D409H mutation was less stable than
the normal counterpart. Pulse-chase experiments demonstrated that the mutated
protein exhibited lower stability than the normal counterpart. Its activity
toward the artificial substrate 4-methyl umbelliferyl glucopyranoside was
similar to that of the mutated enzymes carrying the N370S or the L444P
mutations. However, in loading experiments using lissamine-rhodamine conjugated
glucosyl ceramide as a substrate, the recombit mutated protein carrying the
D409H mutation exhibited 28.63 +/- 6.05% of the activity exhibited by the normal
enzyme. L444P and N370S mutations exhibited 51.90 +/- 7.16 and 115.75 +/- 12.64%
of normal enzyme activity, respectively. Loading of cells homozygous for the
D409H mutation demonstrated 10. 05% of the activity shown by normal cells. L444P
and N370S homozygous cells demonstrated 25.3 and 98.5% of foreskin fibroblast
glucocerebrosidase activity, respectively. We demonstrate that homozygosity for
the D409H mutation is a unique case of a peculiar phenotype associated with a
specific intracellular glucocerebrosidase activity. Gaucher disease is a heterogeneous disease characterized by impaired activity of
the lysosomal enzyme glucocerebrosidase. This heterogeneity is attributed to a
large number of mutations in the corresponding gene. In order to test the
biochemical properties of some mutations prevalent among Israeli populations,
the normal human glucocerebrosidase cDNA and cDNAs carrying mutations N370S,
L444P, D409H, recTL, recNcil, P415R and 84GG were coupled to the T7 RNA
polymerase promoter in a vaccinia virus-derived expression vector (pTM-1).
Recombit viruses were produced and used to infect human tissue culture cells.
RNA and protein stability, recognition by anti-glucocerebrosidase monoclonal
antibodies and intracellular enzymatic activity were measured. The results
demonstrated that the D409H allele directed synthesis of cytoplasmic RNA with
decreased stability compared with its normal counterpart or other mutated forms.
The D409H and L444P mutated proteins had lower stability than that of their
normal counterpart, while the recNcil-mutated protein was more stable. Only
glucocerebrosidase forms harboring leucine at position 444 were recognized by
the anti-glucocerebrosidase monoclonal antibodies used (8E4 and 2C7).
Measurements of enzymatic activity of the recombit proteins in cells loaded
with a fluorescent glucosylceramide demonstrated that the N370S mutated enzyme
had activity similar to that of the normal enzyme. The other mutated enzymes
exhibited varying degrees of activities, generally corresponding to the
phenotypes with which they are associated. The results presented demonstrate the
use of the vaccinia virus-derived expression system and of loading living cells
with fluorescent substrate as efficient tools for studying mutants in Gaucher
disease and in other lysosomal diseases. Gaucher disease is the most common lysosomal storage disease with a high
prevalence in the Ashkenazi Jewish population but it is also present in other
populations. The presence of eight mutations (1226G, 1448C, IVS2+1. 84GG, 1504T,
1604T, 1342C and 1297T) and the complete deletion of the beta-glucocerebrosidase
gene was investigated in 25 unrelated non-Jewish patients with Gaucher's disease
in Germany. In the Jewish population, three of these mutations account for more
than 90% of all mutated alleles. In addition, relatives of two patients were
included in our study. Restriction fragment length polymorphism analysis and
sequencing of PCR products obtained from DNA of peripheral blood leukocytes was
performed for mutation analysis. Gene deletion was detected by comparison of
radioactively labelled PCR fragments of both the functional
beta-glucocerebrosidase gene and the pseudogene. Among the unrelated patients,
50 alleles were investigated and the mutations identified in 35 alleles (70%),
whereas 15 alleles (30%) remained unidentified. The most prevalent mutation in
our group of patients was the 1226G (370Asn-->Ser) mutation, accounting for 18
alleles (36%), followed by the 1448C (444Lcu-->Pro) mutation, that was found in
12 alleles (24%). A complete gene deletion was present in two alleles (4%). The
IVS1+2 (splicing mutation), the 1504T (463Arg-->Cys) as well as the 1342C
(409Asp-->His) mutations were each present in one allele (2%). None of the
alleles carried the 84GG (frame-shift), 1604A (496Arg-->His) or the 1297T
(394Val-->Leu) mutation. This distribution is different from the Ashkenazi
Jewish population but is similar to other Caucasian groups like the Spanish and
Portuguese populations. Our results confirm the variability of mutation patterns
in Gaucher patients of different ethnic origin. All patients were divided into
nine groups according to their genotype and their clinical status was related to
the individual genotype. Genotype/phenotype characteristics of the 1226G, 1448C,
and 1342C mutations of previous studies were confirmed by our results. Gaucher disease results, in most patients, from mutations in the gene encoding
glucocerebrosidase. Mutation D409H is the third most frequent in Spanish
patients, accounting for 5.7% of all mutated alleles. This allele is associated
mainly with the neurological forms of the disease. Recently, homozygosity for
the D409H mutation has been associated with a particular phenotype, including
specific cardiovascular symptoms. Here we report a second Spanish patient
bearing the D409H/D409H genotype with a very early manifestation of the disease.
The patient started enzyme replacement therapy at 3 months of age. A common
origin for the Spanish D409H alleles was ruled out by haplotype analysis using
an internal polymorphism of the glucocerebrosidase gene and two external
microsatellite markers. SHORT INTRODUCTION: Gaucher's disease (GD) is an autosomal recessive disease
produced by mutations of the Glucocerebrosidase gene. Carriers are considered to
be healthy subjects because there is no manifestation of the disease, but they
show signs of macrophage disfunction. The aim of the study was to determine if
GD patients and non affected carriers risk suffering other diseases when
compared to healthy non-carrier relatives.
DESIGN: Epidemiologic study of historic cohorts. The fact that they have one or
two mutated alleles has been considered to be the risk factor leading to other
conditions (Dementia, Parkinson disease, Ischemic stroke, Ischemic heart
disease, Non rheumatic valvular disease, Cancer hematological and
non-hematological, Pulmonary fibrosis, Tuberculosis, Gallstones and
Schizophrenia). All people, patients, carriers and healthy controls shared the
same genetical background and environmental influence. - Patients and relatives
enrolled on the Spanish Gaucher Disease Registry were evaluated.
STATISTICS: For the Relative-Risk calculation the Mantel-Haenszel test was
applied. Yates' correction was used when size sample was too small. A value of p
<0.05 was accepted for statistical significance.
RESULTS: 370 people, from 79 different families, were surveyed. We received
evaluable information from 45 families (56%), totalling 258 people (69%): 59
healthy subjects (Mean age 32. 20, RANGE: 10-85; M 57.63%/F 42.37%), 132
carriers (Mean age 35.91, RANGE: 1-79; M 56.82%/F 43.18%) and 67 patients (Mean
age 32.16, Range: 1-76; M 44.78%/F 55.22%. - Relative Risk of suffering any
disease with regard to Gaucher's status: Patient vs Healthy 9.69 (95% Confidence
interval [CI] 2.00-63.99; p 0.0006). Patient vs Carrier 3.74 (CI 1.53-9.27; p
0.001); Carrier vs Healthy 2.59 (CI 0. 52-12.50; p 0.21). Relative Risk of
suffering any disease with regard to sex was 3.96 for female patients (CI
1.01-16.75; p 0.02) and 1.34 for female carriers (CI 0.27-6.75; p = 0.68).
CONCLUSION: As a group, Gaucher's patients seem to have a greater risk of
suffering other common unrelated diseases than carriers or healthy relatives.
This excess of risk is particularly higher among female patients and can not be
explained in terms of differences in age. Carrier status doesn't seem to highten
the risk of suffering other diseases. We have compared the substitution pattern of the glucocerebrosidase gene (GBA)
and the glucocerebrosidase pseudogene (psGBA), two highly homologous regions
under different selective pressures and within the same genomic background.
Mutations in GBA may lead to Gaucher disease, an inborn metabolic disorder.
Disease-causing mutations and neutral variation in the gene have been compared
to neutral variation in the pseudogene. This comparison offers a unique
opportunity to better understand the action of purifying selection, since the
differences between mutational patterns can be attributed to different selective
pressures. A similar frequency of CpG dinucleotides was observed in GBA and in
psGBA, and CpG pairs were mutated with the same high frequency in both regions.
However, nucleotides not in CpG pairs were more likely to contribute to
disease-causing mutation than to accepted polymorphisms. This pattern, which
resulted in a lower transition to transversion ratio in the gene, may be due to
CpG avoidance on critical regions within exons. BACKGROUND: Gaucher disease (GD) is a heterogeneous disease characterized by an
impaired activity of the lysosomal glucocerebrosidase. This heterogeneity is
attributed in part to the existence of a large number of mutations in the
corresponding gene.
SUBJECTS AND METHODS: To establish genotype-phenotype relationships, we analyzed
the residual enzyme activities of six naturally occurring mutations found in
Spanish population in the glucocerebrosidase gene [c.160G > A (V15M), c.485T>C
(M123T), c.914C>T (P266L), c.1124T>C (L336P), c.1207A>C (S364R) and
c.1510-1512delTCT (S465del)]. The mutated genes were subcloned into the
mammalian expression vector pCR 3.1 and expressed by transient transfection in
COS cells. The enzymatic activity of the expressed protein were measured and
compared with the wild-type human glucocerebrosidase cDNA. Also, two previously
alleles, c.1226A>G (N370S) and c.1448T>C (L444P), were used for comparative
purposes.
RESULTS: The residual activity of the expressed proteins using the synthetic
substrate (4-methylumbelliferyl-beta-D-glucopyranoside, 4MU-Glu) ranged from
5.5% (for the 3-bp deletion) to 42.7% (for S364R mutation) of the activity of
the wild-type enzyme.
CONCLUSION: The present analyses may help to better understand the molecular
basis and the pathogenesis of Gaucher disease. However, results of expression of
mutated enzymes are necessary but not sufficient to explain the ultimate
clinical outcome of Gaucher disease. Gaucher disease (GD) is a disorder of glycosphinglipid metabolism caused by
deficiency of lysosomal acid beta-glucosidase (GC), resulting in progressive
deposition of glucosylceramide in macrophages. The glucose analogue,
N-butyl-deoxynojirimycin (NB-DNJ, Miglustat), is an inhibitor of the
ceramide-specific glucosyltransferase (CSG) which catalyzes the first step of
glycosphingolipids biosynthesis and is currently approved for the oral treatment
of type 1 GD. Using site-directed mutagenesis, we constructed plasmids
containing wild-type and several mutations in glucocerebrosidase (GBA) gene. The
plasmids were transfected into COS-7 cells and stable transfected cell lines
were obtained by geneticin (G418) selection. Cells were cultured during 6 days
with medium with or without 10 microM NB-DNJ. The addition of NB-DNJ to COS-7
cell medium leads to 1.3-, 2.1-, 2.3-, 3.6-, and 9.9-fold increase in the
activity of S364R, wild-type, N370S, V15M, and M123T GC, respectively. However,
no significant changes were observed in the activity of the L444P, L336P, and
S465del mutated proteins, but a small decrease in the rare P266L variant was
observed. These results suggest that NB-DNJ, in addition to the inhibitory
effect on CSG, also works as a "chemical chaperone", increasing the activity of
acid beta-glucosidase of wild-type and several GC mutated proteins, including
the most frequent N370S mutation. The specific location of the Miglustat binding
site in GC is unknown. Potential binding sites in the enzyme have been searched
for using computational molecular docking. The searching strategy identified
three potential GC binding sites for Miglustat, one being the substrate-binding
site of the enzyme, which was the best-ranked site by AutoDock program.
Therefore, it is possible that Miglustat exerts its chaperoning activity on acid
beta-glucosidase by acting as an inhibitor bound at the active site. This
increase on the activity of the acid beta-glucosidase would imply that Miglustat
is not only a substrate reducer but also an inhibitor of the GC degradation,
with very promising clinical implications for the treatment of GD patients. In Gaucher disease (GD), the inherited deficiency of glucocerebrosidase results
in the accumulation of glucocerebroside within lysosomes. Although almost 300
mutations in the glucocerebrosidase gene (GBA) have been identified, the ability
to predict phenotype from genotype is quite limited. In this study, we sought to
examine potential GBA transcriptional regulatory elements for variants that
contribute to phenotypic diversity. Specifically, we generated the genomic
sequence for the orthologous genomic region ( approximately 39.4kb) encompassing
GBA in eight non-human mammals. Computational comparisons of the resulting
sequences, using human sequence as the reference, allowed the identification of
multi-species conserved sequences (MCSs). Further analyses predicted the
presence of two putative clusters of transcriptional regulatory elements
upstream and downstream of GBA, containing five and three transcription
factor-binding sites (TFBSs), respectively. A firefly luciferase (Fluc) reporter
construct containing sequence flanking the GBA gene was used to test the
functional consequences of altering these conserved sequences. The predicted
TFBSs were individually altered by targeted mutagenesis, resulting in enhanced
Fluc expression for one site and decreased expression for seven others sites.
Gel-shift assays confirmed the loss of nuclear-protein binding for several of
the mutated constructs. These identified conserved non-coding sequences flanking
GBA could play a role in the transcriptional regulation of the gene contributing
to the complexity underlying the phenotypic diversity seen in GD. Pseudogenes, resulting from duplications of functional genes, contribute to the
functional complexity of their parental genes. The glucocerebrosidase gene
(GBA), located in a gene-rich region on chromosome 1q 21, is mutated in Gaucher
disease. The presence of contiguous, highly homologous pseudogenes for both GBA
and metaxin 1 at this locus increases the likelihood of DNA rearrangement. We
describe a facile method to identify and analyze recombit alleles in patients
with Gaucher disease. Genomic DNA from 20 patients with recombit GBA alleles
and five controls was evaluated to identify DNA rearrangements or copy number
variation using six probes specific for either the GBA gene or pseudogene.
Quantitative real-time PCR was performed on genomic DNA, and Southern blot
analyses using HincII together with sequencing confirmed the real-time results.
Both GBA fusions and duplications could be detected. Different sites of
crossover were identified, and alleles resulting from gene conversion could be
distinguished from reciprocal recombit alleles. Quantitative real-time PCR is
a sensitive and rapid method to detect fusions and duplications in patients with
recombit GBA alleles. This technique is more sensitive, faster, and cheaper
than Southern blot analysis, and can be used in diagnostic laboratories, and to
detect other recombit alleles within the genome. Gaucher's disease (GD) results from a deficiency of the lysosomal enzyme
glucocerebrosidase and, in very rare occasions, a deficiency of its activator,
the saposin C. The complexity of identification and characterization of
mutations in the gene of glucocerebrosidase (GBA1) is caused by a great amount
of mutated alleles, the existence of a highly homologous pseudogene and its
location in a very rich zone in genes, which promotes the presence of complex
alleles. Although genotype-phenotype correlations in EG are not completely
established, there are a series of generalities, as the mutation c.1226A>G
(N370S) is often associated with a certain degree of neuroprotection and the
homozygosity for the c.1448T>C (L444P) mutation presents with neurological
symptoms. Gaucher disease (GD) is the most common of the lysosomal storage disorders and
is caused by defects in the GBA gene encoding glucocerebrosidase (GlcCerase).
The accumulation of its substrate, glucocylceramide (GlcCer) is considered the
main cause of GD. We found here that the expression of human mutated GlcCerase
gene (hGBA) that is associated with neuronopathy in GD patients causes
neurodevelopmental defects in Drosophila eyes. The data indicate that
endoplasmic reticulum (ER) stress was elevated in Drosophila eye carrying
mutated hGBAs by using of the ER stress markers dXBP1 and dBiP. We also found
that Ambroxol, a potential pharmacological chaperone for mutated hGBAs, can
alleviate the neuronopathic phenotype through reducing ER stress. We demonstrate
a novel mechanism of neurodevelopmental defects mediated by ER stress through
expression of mutants of human GBA gene in the eye of Drosophila. |
Why does the prodrug amifostine (ethyol) create hypoxia? | After the administration of Prodrug amifostine the cells of the tissue prefer anaerobic glycolysis rather than regular cellular aerobic respiration. By the beggining of anaerobic glycolysis the inducible by hypoxia proteins are induced and by all these molecules the hypoxic conditions consist of. | Controlled clinical trials indicate that amifostine (WR-2721, Ethyol) confers
protection from the cumulative hematologic toxicities associated with alkylating
agents and organoplatinums. To determine whether amifostine protects primitive
hematopoietic progenitors from the cytotoxicity of functionally diverse
antineoplastics, formation of the multipotent hematopoietic progenitors
colony-forming units-granulocyte-erythroid, macrophage, megakaryocyte (CFU-GEMM)
and erythroid burst-forming units (BFU-E) was evaluated using a clonogenic
progenitor inhibition assay. Bone marrow mononuclear cells from normal donors
were subjected to a 15-minute exposure of medium, amifostine (500 micromol/L),
or WR-1065 (100 micromol/L at concentrations approximating peak plasma levels,
washed twice, then treated with the antineoplastic for 1 to 6 hours. Colony
growth was scored after 14 days of incubation. Amifostine conferred protection
against a broader range of antineoplastics than did WR-1065. Amifostine
protected CFU-GEMM against cytotoxicity from daunorubicin, mitoxantrone, and
paclitaxel (range, 1.29- to 9.57-fold) (P < .05) but did not afford protection
against cisplatin, diaziquone, or thiotepa. Similarly, amifostine protected
BFU-E against toxicity from doxorubicin, mitoxantrone, paclitaxel, cisplatin,
and diaziquone, yielding 3.4- to 65-fold greater colony recovery compared with
controls. The high degree of cytoprotection afforded by amifostine derived
largely from stimulation of progenitor growth at sublethal chemotherapy
concentrations. In the absence of antineoplastic exposure, preincubation with
amifostine or WR-1065 enhanced the colony-forming capacity of bone marrow
progenitors from six normal donors, increasing recovery of CFU-GEMM and BFU-E up
to sevenfold. We conclude that amifostine protects primitive hematopoietic
progenitors from a wide range of antineoplastics. This broad hemoprotective
effect derives in part from inherent trophic effects on progenitor growth and
survival. Amifostine (Ethyol) administered to cancer patients is rapidly cleared from
plasma by a biphasic decay with an alpha half-life (T1/2 alpha) of 0.88 min and
a T1/2 beta of 8.8 min. The result is that more than 90% of the drug has
disappeared from the plasma compartment 6 min after intravenous (i.v.)
administration. Only approximately 1% of the dose appears in the ascites. Animal
studies indicate that amifostine is primarily excreted in urine-approximately 6%
of the dose is excreted in the urine as amifostine and its metabolites WR-1065
and disulphides-which means that a large percentage of the dose is taken up by
the tissues. Maximal tissue concentrations of WR-1065 and the disulphides were
obtained between 10 and 30 min after an intraperitoneal injection of amifostine
in mice, with the lowest concentrations in tumour tissues. Because WR-1065 gives
protection to normal tissues rather than rescue, the pharmacokinetic data
indicate that amifostine must be given shortly before administration of the
cytostatic drug or radiation from which protection is required. For these
reasons, amifostine is given to patients as a 15-min i.v. infusion before
cisplatin and carboplatin to protect against their dose-limiting toxicities. In
some regimens carboplatin is combined with three doses of amifostine because of
the high concentration of the active carboplatin species during the first 4 h
after administration. When carboplatin was administered as a 15-min i.v.
infusion of 400 mg/m2 and amifostine as a 15-min i.v. infusion of 740 mg/m2 just
before and 2 and 4 h after carboplatin, the area under the plasma
concentration-time curve for ultrafilterable platinum increased from 253 +/- 45
microM.h (n = 6) for carboplatin alone to 305 +/- 63 microM.h (n = 11) for
carboplatin+three doses of amifostine. Experiments in nude mice bearing OVCAR-3
xenografts showed that amifostine, given once before cisplatin or three times in
combination with carboplatin, did not affect the antitumour effect of these
drugs. When amifostine was only given just before carboplatin, it even
stimulated the antitumour effect of carboplatin significantly. Conclusive research has shown that regions of acute/chronic hypoxia, which exist
within the majority of solid tumours, have a profound influence on the
therapeutic outcome of cancer chemotherapy and radiotherapy and are a strong
prognostic factor of disease progression and survival. A strong argument
therefore exists for assessing the hypoxic fraction of tumours, prior to patient
treatment, and to tailor this treatment accordingly. Tumour hypoxia also
provides a powerful physiological stimulus that can be exploited as a
tumour-specific condition, allowing for the rationale design of
hypoxia-activated anticancer drugs or novel hypoxia-regulated gene therapy
strategies. Intrinsic radioresistance, tumor hypoxia and ability of cancer cells to undergo
rapid repopulation during radiotherapy are associated with failure of
radiotherapy. Tumors with low alpha/beta-ratio values or hypoxic tumors unable
to undergo re-oxygenation, are unlikely to be eradicated with standard
radiotherapy. Although the therapeutic efficacy of accelerated regimens based on
low-dose per fraction may be high since they minimize the adverse role of rapid
tumor repopulation, the cellular compartment with low alpha/beta-ratio values
(i.e. hypoxic cells) remains a limiting factor. Accelerated hypofractionation,
which may be more effective in such tumors, cannot be safely applied unless
normal tissues are protected. In the present study we assessed the feasibility
of hypofractionated and accelerated radiotherapy supported by cytoprotection
(HypoARC) with high dose daily amifostine. Fifteen breast cancer patients with
locally advanced disease entered radiation-dose escalation protocoL Twelve
consecutive fractions of 3.5-4Gy (5 fractions/week) were given to the
breast/chest wall, supraclavicular and axillary area, within 17 days. A high
dose of amifostine, at 1,000 mg flat dose, was given 20 minutes before each
radiotherapy fraction. Amifostine administration was well- tolerated with minor
side-effects (vomiting in 6 out of 15 and hypotention in 2 out of 15 patients).
Radiation induced acute skin toxicity was negligible (grade 3 in 1 out of 15
patients). Ten out of 15 patients survived more than 12 months and 7 out of 15
more than 18 months following HypoARC. None of these patients showed any signs
of late sequellae, such as lung and myoskeletal fibrosis, or brachial
plexopathy. Complete and partial responses were obtained in 11 out of 15 (73%)
and in 4 out of 15 (27%) patients, respectively. High dose daily amifostine
during hypofractionated radiotherapy is feasible. HypoARC regimen is
well-tolerated, effective and has minimal acute and late toxicity to normal
breast, chest and axillary tissues. Amifostine (Ethyol), an inorganic thiophosphate, is a selective broad-spectrum
cytoprotector of normal tissues that provides cytoprotection against ionizing
radiation and chemotherapeutic agents, thus preserving the efficacy of
radiotherapy and chemotherapy. This review summarizes the preclinical data and
clinical experience with amifostine, and provides insight into future clinical
directions. Amifostine, an inactive pro-drug, is transformed to an active thiol
after dephosphorylation by alkaline phosphatase found in the normal endothelium.
The absence of alkaline phosphatase in the tumoral endothelium and stromal
components, and the hypovascularity and acidity of the tumor environment, may
explain its cytoprotective selectivity. The cytoprotective mechanism of
amifostine is complicated, involving free radical scavenging, DNA protection and
repair acceleration, and induction of cellular hypoxia. Intravenous
administration of amifostine 740-900 mg/m(2) before chemotherapy and 250-350
mg/m(2) before each radiotherapy fraction are widely used regimens. The US Food
and Drug Administration has approved the use of amifostine as a cytoprotector
for cisplatin chemotherapy and for radiation-induced xerostomia. Ongoing trials
are being conducted to determine the efficacy of amifostine in reducing
radiation-induced mucositis and other toxicities. Novel schedules and routes of
administration are under investigation, and may further simplify the use of
amifostine and considerably broaden its applications. PURPOSE: The cytoprotective mechanism of amifostine (WR-2721) implies free
radical scavenging and DNA repair activities. We investigated additional
cytoprotective pathways involving intracellular hypoxia and the activation of
the hypoxia-inducible factor (HIF) pathway, a key transcription factor
regulating glycolysis, angiogenesis and apoptosis, which is also linked with
radioresistance.
MATERIALS AND METHODS: The glucose and oxygen levels in the peripheral blood of
patients receiving 1000 mg amifostine were determined at various time-points in
order to investigate the metabolic changes induced by amifostine. MDA468 breast
tumor cell lines were incubated with a high amifostine concentration (10 m M) to
overcome the natural resistance of cancer cells to influx of the non-hydrolyzed
WR-2721, and the HIF1 alpha protein levels were determined by Western blot
analysis. In vivo experiments with Wistar rats were performed in order to assess
immunohistochemically changes in the intracellular accumulation of HIF1 alpha
induced by amifostine (200 mg/kg).
RESULTS: By 30 min following amifostine administration, the hemoglobin oxygen
saturation and pO(2) levels had increased in the peripheral blood while glucose
levels had reduced, providing evidence that normal tissue metabolism switches to
glycolytic pathways. Incubation of cell lines with amifostine resulted in HIF1
alpha induction. In Wistar rats administration of amifostine resulted in
increased HIF1 alpha accumulation in normal tissues.
CONCLUSIONS: Since it is doubtful whether dephosphorylation of amifostine to the
active metabolite WR-1065 occurs within tumoral tissues (an acidic environment
that lacks vascular alkaline phosphatase activity), intracellular hypoxia and
upregulation of HIF1 alpha represents an additional, normal tissue-specific,
amifostine cytoprotective pathway. After several decades of preclinical and clinical research, the first approved
radioprotective drug, amifostine, is being used in clinical practice. Amifostine
has been shown to specifically protect normal tissues from damage caused by
radiation and chemotherapy. An inactive prodrug, amifostine is converted to an
active thiol by dephosphorylation by alkaline phosphatase in the normal
endothelium. The hypovascularity and acidity of the tumor environment and the
differential expression of alkaline phosphatase in normal and neoplastic tissues
contribute to its cytoprotective selectivity. The cytoprotective mechanism of
amifostine is complicated, involving free-radical scavenging, DNA protection and
repair acceleration, and induction of cellular hypoxia. The U.S. Food and Drug
Administration has approved the i.v. use of amifostine to reduce the cumulative
renal toxicity associated with repeated administration of cisplatin in patients
with advanced ovarian cancer and to reduce the incidence of moderate to severe
xerostomia in patients undergoing postoperative radiation treatment for head and
neck cancer, where the radiation port includes a substantial portion of the
parotid glands. Nonetheless, amifostine has potential applications in many other
oncologic settings. Novel schedules and routes of administration are under
investigation and may further simplify the use of amifostine, reduce any
undesired effects, and considerably broaden its applications. This review
summarizes the clinical experience with amifostine and provides insight into
future clinical directions. PURPOSE: Tumor hypoxia and low intrinsic radiosensitivity may counteract the
efficacy of standard radiotherapy for locally advanced head and neck cancer
(HNC). We investigated the involvement of hypoxia-regulated proteins (Hypoxia
inducible factors HIF1alpha, HIF2alpha and carbonic anhydrase CA9) in HNC
resistance to accelerated and hypofractionated radiotherapy.
MATERIALS AND METHODS: Thirty-nine patients with locally advanced HNC received
15 daily fractions of 3.4 Gy amounting to a total tumor dose of 51 Gy
(equivalent to 63 Gy in four weeks--one week split); this was combined with
platinum chemotherapy and amifostine cytoprotection administered subcutaneously.
Immunohistochemical analysis of hypoxia-regulated proteins, namely HIF1alpha,
HIF2alpha and CA9, was performed in formalin-fixed paraffin-embedded tissues
obtained prior to radio-chemotherapy.
RESULTS: HIF1alpha and HIF2alpha were expressed in the nuclei and cytoplasm of
cancer cells, while CA9 had a membrane reactivity. A high expression of
HIF1alpha, HIF2alpha and CA9 was noted in 21/39 (53.8%), 20/39 (51.3%) and 23/39
(58.9%) cases, respectively. Complete response was obtained in 85.2% of patients
and HIF1alpha was marginally related with persistent disease after RT (p =
0.05). HIF1alpha was significantly associated with poor local relapse free
survival (LRFS) (p = 0.006) and overall survival (p = 0.008), whilst HIF2alpha
was not. A significant association of CA9 expression with poor LRFS was noted (p
= 0.01).
CONCLUSION: In accord with previously reported studies, high levels of the
hypoxia regulated proteins HIF1alpha and CA9 in HNC predict resistance to
platinum based radio-chemotherapy. Whether HIF2alpha expressing tumors are more
sensitive to larger radiotherapy fractions, compared to standard radiotherapy
fractionation, is an issue that deserves further investigation. BACKGROUND: Radioprotective modalities such as dose fractionation and
pharmacologic agents such as amifostine have been used to protect bone and other
types of normal tissue from the damaging effects of ionizing radiation without
significantly impacting tumor kill. To better understand the cellular mechanism
of radioprotection of osseous tissue, the authors sought to determine the effect
of dose fractionation and amifostine on isolated osteoblasts.
METHODS: Isolated primary rat calvarial osteoblasts were exposed to single or
fractionated doses of ionizing radiation both with and without amifostine
pretreatment. Endpoints included cell growth (n = 4), vascular endothelial
growth factor production as measured by enzyme-linked immunosorbent assay (n =
3), and early osteodifferentiation as measured by a quantitative alkaline
phosphatase assay (n = 3).
RESULTS: Both dose fractionation and amifostine protect osteoblasts from the
growth inhibitory effects of ionizing radiation. Fractionation but not
amifostine was protective for hypoxia-induced vascular endothelial growth factor
production (used as a surrogate marker of normal osteoblast function). Neither
fractionation nor amifostine could prevent the inhibitory effect of ionizing
radiation on normal osteoblast osteodifferentiation as measured by alkaline
phosphatase production.
CONCLUSIONS: Both dose fractionation and amifostine have valid roles as
radioprotectants for osteoblasts and can act in an additive fashion.
Radioprotection of cell growth and viability does not necessarily correlate with
preservation of normal cellular function. Combination protocols involving dose
fractionation and amifostine may be effective in radioprotection of osteoblasts
and normal osseous tissue. BACKGROUND: Amifostine (WR-2721, delivered as Ethyol) is a phosphorylated
aminothiol compound clinically used in addition to cis-platinum to reduce the
toxic side effects of therapeutic treatment on normal cells without reducing
their efficacy on tumour cells. Its mechanism of action is attributed to the
free radical scavenging properties of its active dephosphorylated metabolite
WR-1065. However, amifostine has also been described as a potent hypoxia-mimetic
compound and as a strong p53 inducer; both effects are known to potently
modulate vascular endothelial growth factor (VEGF-A) expression. The angiogenic
properties of this drug have not been clearly defined.
METHODS: Cancer cell lines and endothelial cells were used in culture and
treated with Amifostine in order to study (i) the expression of angiogenesis
related genes and proteins and (ii) the effects of the drug on VEGF-A induced in
vitro angiogenesis.
RESULTS: We demonstrated that the treatment of several human cancer cell lines
with therapeutical doses of WR-1065 led to a strong induction of different
VEGF-A mRNA isoforms independently of HIF-1alpha. VEGF-A induction by WR-1065
depends on the activation of the eIF2alpha/ATF4 pathway. This up-regulation of
VEGF-A mRNA was accompanied by an increased secretion of VEGF-A proteins fully
active in stimulating vascular endothelial cells (EC). Nevertheless, direct
treatment of EC with amifostine impaired their ability to respond to exogenous
VEGF-A, an effect that correlated to the down-regulation of VEGFR-2 expression,
to the reduction in cell surface binding of VEGF-A and to the decreased
phosphorylation of the downstream p42/44 kinases.
CONCLUSIONS: Taken together, our results indicate that amifostine treatment
modulates tumour angiogenesis by two apparently opposite mechanisms - the
increased VEGF-A expression by tumour cells and the inhibition of EC capacity to
respond to VEGF-A stimulation. Placental extracts have been reported to have anti-oxidative and
anti-inflammatory activities. Because there is increasing evidence that ionizing
radiation induces the release of reactive oxygen species (ROS) and inflammatory
cytokines, we examined the protective effects of a placental extract against
radiation injury. C57BL/6 mice were exposed to 1 Gy of γ-ray radiation every day
for 5 days, and placental extract (1 mg/day) was administrated orally soon after
each exposure. At 2 days after the last irradiation, mice were euthanized to
examine the numbers, colony-forming capacity, and DNA damage of stem/progenitor
cells in the peripheral blood and bone marrow. To understand the related
mechanisms, we also measured the levels of intracellular and mitochondrial ROS,
and 8-OHdG in the plasma and urine, and IL-6 and TNF-α in the plasma. Compared
with the placebo treatment, oral administration of placental extract
significantly increased the number and colony-forming capacity, but decreased
the DNA damage of bone marrow stem/progenitor cells. However, neither the levels
of intracellular and mitochondrial ROS in bone marrow cells, nor the levels of
8-OHdG in the urine and plasma significantly differed between groups.
Interestingly, in comparison with the placebo treatment, placental extract
significantly decreased the levels of the inflammatory cytokines IL-6 and TNF-α
in the plasma. Placental extract significantly attenuated the acute radiation
injury to bone marrow-derived stem/progenitor cells, and this protection is
likely to be related to the anti-inflammatory activity of the placental extract. |
What is considered a reliable technique for the definitive cytogenetic diagnosis of Fanconi anemia homozygosity? | In vitro enhancement of chromosome breakage by diepoxybutane (DEB) and mitomycin C (MMC) are reliable techniques for the definitive cytogenetic diagnosis of Fanconi anemia homozygosity. | BACKGROUND: Patients with bone marrow failure and undiagnosed underlying Fanconi
anemia may experience major toxicity if given standard-dose conditioning
regimens for hematopoietic stem cell transplant. Due to clinical variability
and/or potential emergence of genetic reversion with hematopoietic somatic
mosaicism, a straightforward Fanconi anemia diagnosis can be difficult to make,
and diagnostic strategies combining different assays in addition to classical
breakage tests in blood may be needed.
DESIGN AND METHODS: We evaluated Fanconi anemia diagnosis on blood lymphocytes
and skin fibroblasts from a cohort of 87 bone marrow failure patients (55
children and 32 adults) with no obvious full clinical picture of Fanconi anemia,
by performing a combination of chromosomal breakage tests,
FANCD2-monoubiquitination assays, a new flow cytometry-based mitomycin C
sensitivity test in fibroblasts, and, when Fanconi anemia was diagnosed,
complementation group and mutation analyses. The mitomycin C sensitivity test in
fibroblasts was validated on control Fanconi anemia and non-Fanconi anemia
samples, including other chromosomal instability disorders.
RESULTS: When this diagnosis strategy was applied to the cohort of bone marrow
failure patients, 7 Fanconi anemia patients were found (3 children and 4
adults). Classical chromosomal breakage tests in blood detected 4, but analyses
on fibroblasts were necessary to diagnose 3 more patients with hematopoietic
somatic mosaicism. Importantly, Fanconi anemia was excluded in all the other
patients who were fully evaluated.
CONCLUSIONS: In this large cohort of patients with bone marrow failure our
results confirmed that when any clinical/biological suspicion of Fanconi anemia
remains after chromosome breakage tests in blood, based on physical examination,
history or inconclusive results, then further evaluation including fibroblast
analysis should be made. For that purpose, the flow-based mitomycin C
sensitivity test here described proved to be a reliable alternative method to
evaluate Fanconi anemia phenotype in fibroblasts. This global strategy allowed
early and accurate confirmation or rejection of Fanconi anemia diagnosis with
immediate clinical impact for those who underwent hematopoietic stem cell
transplant. We report on a male newborn with multiple congenital abnormalities consistent
with the diagnosis of VACTERL association (vertebral, anal, cardiac,
tracheo-esophageal fistula, renal, and limb anomalies), who had Fanconi anemia
(complementation group B) recognized by the detection of a deletion in
chromosome Xp22.2 using an oligonucleotide array. The diagnosis of Fanconi
anemia was confirmed by increased chromosomal breakage abnormalities observed in
cultured cells that were treated with cross-linking agents. This is the first
report in the literature of Fanconi anemia complementation group B detected by
oligonucleotide array testing postnatally. |
Can exosomes be detected in urine? | Yes, urinary exosomes can be detected in urine. | Exosomes are ovesicles secreted into the extracellular environment upon
internal vesicle fusion with the plasma membrane. The molecular content of
exosomes is a fingerprint of the releasing cell type and of its status. For this
reason, and because they are released in easily accessible body fluids such as
blood and urine, they represent a precious biomedical tool. A growing body of
evidence suggests that exosomes may be used as biomarkers for the diagnosis and
prognosis of maligt tumors. This article focuses on the exploitation of
exosomes as diagnostic tools for human tumors and discusses possible
applications of the same strategies to other pathologies, such as
neurodegenerative diseases. Urinary exosomes have been proposed as potential diagnostic tools. TNF
superfamily cytokines and receptors may be present in exosomes and are expressed
by proximal tubular cells. We have now studied the expression of selected TNF
superfamily proteins in exosome-like vesicles from cultured human proximal
tubular cells and human urine and have identified additional proteins in these
vesicles by LC-MS/MS proteomics. Human proximal tubular cells constitutively
released exosome-like vesicles that did not contain the TNF superfamily
cytokines TRAIL or TWEAK. However, exosome-like vesicles contained
osteoprotegerin (OPG), a TNF receptor superfamily protein, as assessed by
Western blot, ELISA or selected reaction monitoring by nLC-(QQQ)MS/MS.
Twenty-one additional proteins were identified in tubular cell exosome-like
vesicles, including one (vitamin D binding protein) that had not been previously
reported in exosome-like vesicles. Twelve were extracellular matrix proteins,
including the basement membrane proteins type IV collagen, nidogen-1, agrin and
fibulin-1. Urine from chronic kidney disease patients contained a higher amount
of exosomal protein and exosomal OPG than urine from healthy volunteers.
Specifically OPG was increased in autosomal domit polycystic kidney disease
urinary exosome-like vesicles and expressed by cystic epithelium in vivo. In
conclusion, OPG is present in exosome-like vesicles secreted by proximal tubular
epithelial cells and isolated from Chronic Kidney Disease urine. Exosomes are vesicles that are released from the kidney into urine. They contain
protein and RNA from the glomerulus and all sections of the nephron and
represent a reservoir for biomarker discovery. Current methods for the
identification and quantification of urinary exosomes are time consuming and
only semi-quantitative. Nanoparticle tracking analysis (NTA) counts and sizes
particles by measuring their Brownian motion in solution. In this study, we
applied NTA to human urine and identified particles with a range of sizes. Using
antibodies against the exosomal proteins CD24 and aquaporin 2 (AQP2), conjugated
to a fluorophore, we could identify a subpopulation of CD24- and AQP2-positive
particles of characteristic exosomal size. Extensive pre-NTA processing of urine
was not necessary. However, the intra-assay variability in the measurement of
exosome concentration was significantly reduced when an ultracentrifugation step
preceded NTA. Without any sample processing, NTA tracked exosomal AQP2
upregulation induced by desmopressin stimulation of kidney collecting duct
cells. Nanoparticle tracking analysis was also able to track changes in exosomal
AQP2 concentration that followed desmopressin treatment of mice and a patient
with central diabetes insipidus. When urine was stored at room temperature, 4°C
or frozen, oparticle concentration was reduced; freezing at -80°C with the
addition of protease inhibitors produced the least reduction. In conclusion,
with appropriate sample storage, NTA has potential as a tool for the
characterization and quantification of extracellular vesicles in human urine. Urinary extracellular vesicles (uEVs) are released by cells throughout the
nephron and contain biomolecules from their cells of origin. Although
uEV-associated proteins and RNA have been studied in detail, little information
exists regarding uEV glycosylation characteristics. Surface glycosylation
profiling by flow cytometry and lectin microarray was applied to uEVs enriched
from urine of healthy adults by ultracentrifugation and centrifugal filtration.
The carbohydrate specificity of lectin microarray profiles was confirmed by
competitive sugar inhibition and carbohydrate-specific enzyme hydrolysis.
Glycosylation profiles of uEVs and purified Tamm Horsfall protein were compared.
In both flow cytometry and lectin microarray assays, uEVs demonstrated surface
binding, at low to moderate intensities, of a broad range of lectins whether
prepared by ultracentrifugation or centrifugal filtration. In general,
ultracentrifugation-prepared uEVs demonstrated higher lectin binding intensities
than centrifugal filtration-prepared uEVs consistent with lesser amounts of
co-purified non-vesicular proteins. The surface glycosylation profiles of uEVs
showed little inter-individual variation and were distinct from those of Tamm
Horsfall protein, which bound a limited number of lectins. In a pilot study,
lectin microarray was used to compare uEVs from individuals with autosomal
domit polycystic kidney disease to those of age-matched controls. The lectin
microarray profiles of polycystic kidney disease and healthy uEVs showed
differences in binding intensity of 6/43 lectins. Our results reveal a complex
surface glycosylation profile of uEVs that is accessible to lectin-based
analysis following multiple uEV enrichment techniques, is distinct from
co-purified Tamm Horsfall protein and may demonstrate disease-specific
modifications. Urinary exosome-like vesicles (ELVs) are a heterogenous mixture (diameter
40-200 nm) containing vesicles shed from all segments of the nephron including
glomerular podocytes. Contamination with Tamm-Horsfall protein (THP) oligomers
has hampered their isolation and proteomic analysis. Here we improved ELV
isolation protocols employing density centrifugation to remove THP and albumin,
and isolated a glomerular membranous vesicle (GMV)-enriched subfraction from 7
individuals identifying 1830 proteins and in 3 patients with glomerular disease
identifying 5657 unique proteins. The GMV fraction was composed of
podocin/podocalyxin-positive irregularly shaped membranous vesicles and
podocin/podocalyxin-negative classical exosomes. Ingenuity pathway analysis
identified integrin, actin cytoskeleton, and Rho GDI signaling in the top three
canonical represented signaling pathways and 19 other proteins associated with
inherited glomerular diseases. The GMVs are of podocyte origin and the density
gradient technique allowed isolation in a reproducible manner. We show many
nephrotic syndrome proteins, proteases, and complement proteins involved in
glomerular disease are in GMVs and some were only shed in the disease state
(nephrin, TRPC6, INF2 and phospholipase A2 receptor). We calculated sample sizes
required to identify new glomerular disease biomarkers, expand the ELV proteome,
and provide a reference proteome in a database that may prove useful in the
search for biomarkers of glomerular disease. Exosomes are small (30-150 nm) vesicles containing unique RNA and protein cargo,
secreted by all cell types in culture. They are also found in abundance in body
fluids including blood, saliva, and urine. At the moment, the mechanism of
exosome formation, the makeup of the cargo, biological pathways, and resulting
functions are incompletely understood. One of their most intriguing roles is
intercellular communication--exosomes function as the messengers, delivering
various effector or signaling macromolecules between specific cells. There is an
exponentially growing need to dissect structure and the function of exosomes and
utilize them for development of minimally invasive diagnostics and therapeutics.
Critical to further our understanding of exosomes is the development of
reagents, tools, and protocols for their isolation, characterization, and
analysis of their RNA and protein contents. Here we describe a complete exosome
workflow solution, starting from fast and efficient extraction of exosomes from
cell culture media and serum to isolation of RNA followed by characterization of
exosomal RNA content using qRT-PCR and next-generation sequencing techniques.
Effectiveness of this workflow is exemplified by analysis of the RNA content of
exosomes derived from HeLa cell culture media and human serum, using Ion Torrent
PGM as a sequencing platform. Recent studies indicate that microRNA (miRNA) is contained within exosome. Here
we sought to optimize the methodologies for the isolation and quantification of
urinary exosomal microRNA as a prelude to biomarker discovery studies. Exosomes
were isolated through ultracentrifugation and characterized by immunoelectron
microscopy. To determine the RNA was confined inside exosomes, the pellet was
treated with RNase before RNA isolation. The minimum urine volume, storage
conditions for exosomes and exosomal miRNA was evaluated. The presence of miRNAs
in patients with various kidney diseases was validated with real-time PCR. The
result shows that miRNAs extracted from the exosomal fraction were resistant to
RNase digestion and with high quality confirmed by agarose electrophoresis. 16
ml of urine was sufficient for miRNA isolation by absolute quantification with
4.15×10(5) copies/ul for miR-200c. Exosomes was stable at 4℃ 24h for shipping
before stored at -80℃ and was stable in urine when stored at -80°C for 12
months. Exosomal miRNA was detectable despite 5 repeat freeze-thaw cycles. The
detection of miRNA by quantitative PCR showed high reproducibility (>94% for
intra-assay and >76% for inter-assay), high sensitivity (positive call 100% for
CKD patients), broad dynamic range (8-log wide) and good linearity for
quantification (R(2)>0.99). miR-29c and miR-200c showed different expression in
different types of kidney disease. In summary, the presence of urinary exosomal
miRNA was confirmed for patients with a diversity of chronic kidney disease. The
conditions of urine collection, storage and miRNA detection determined in this
study may be useful for future biomarker discovery efforts. End-stage renal disease (ESRD) requires for its treatment permanent dialysis or
kidney transplantation (KT). KT is the best clinical treatment, however, the
early function of the allograft varies depending on multiple factors associated
with cold ischemia time (CIT) and the allograft rejection process. It is known
that serum creatinine is an insensitive and late marker for predicting graft
recovery after KT, mainly in patients with delayed graft function (DGF).
Neutrophil gelatinase-associated lipocalin (NGAL) is produced in the distal
nephron and it is one of the most promising novel biomarkers for acute kidney
injury (AKI) and chronic kidney disease (CKD). NGAL has been proposed to be a
predictor of organ recovery from DGF after KT from donors after cardiac death.
Because nonrenal diseases can also induce NGAL, more information is necessary to
validate the sensitivity and specificity of urine and plasma NGAL in clinical
samples. The exosomes are vesicles released into the urine from the kidney
epithelium and they have been proposed as better source to explore as biomarker
of renal dysfunction. The molecular composition of the urinary exosomes could be
representative of the physiological or physiopathologic condition of the urinary
system. We propose that determination of NGAL in urinary exosomes is a better
predictor of kidney dysfunction after KT than other urinary fractions. We
analyzed 15 kidney allograft recipients, with a mean age of 36 years (range,
16-60 years) and 75% were male: 11 living donors (LD) and 4 deceased donors
(DD). The average length of CIT was 14 hours in DD and less than 1 hour in LD.
Three patient developed DGF. Using Western blot analysis, NGAL was detectable in
the cellular and exosomal fraction of the urine. The exosomes expressed higher
levels of NGAL than the cellular fraction. The expression of NGAL was observed
from the first day after transplantation. In the cellular fraction of the urine,
no significant differences of NGAL were observed between the patients. However,
the median of NGAL expression in the exosomes fraction was significantly higher
in DD patient, from the first day after KT (P < .05). Moreover, we noticed that
NGAL expression in exosomes remained elevated in the patients with DGF compared
with non-DGF patients (P < .05). Considering the highest abundance of NGAL in
the urinary exosomes and its correlation with DGF patients, we suggest the
exosomal fraction as a more sensitive substrate to evaluate early biomarkers of
DGF after KT. |
What is the role of lysine-specific demethylase 1 (LSD1) in hematopoiesis? | LSD1 represents a central regulator of hematopoietic stem and progenitor cells. LSD1 knockdown (LSD1-kd) expanded progenitor numbers by enhancing their proliferative behavior. LSD1-kd led to an extensive expansion of granulomonocytic, erythroid and megakaryocytic progenitors. In contrast, terminal granulopoiesis, erythropoiesis and platelet production were severely inhibited. The only exception was monopoiesis, which was promoted by LSD1 deficiency. Importantly, we showed that peripheral blood granulocytopenia, monocytosis, anemia and thrombocytopenia were reversible after LSD1-kd termination. Extramedullary splenic hematopoiesis contributed to the phenotypic reversion, and progenitor populations remained expanded. LSD1-kd was associated with the upregulation of key hematopoietic genes, including Gfi1b, Hoxa9 and Meis1, which are known regulators of the HSC/progenitor compartment. We also demonstrated that LSD1-kd abrogated Gfi1b-negative autoregulation by crossing LSD1-kd with Gfi1b:GFP mice. There is also epigenetic regulation of hematopoietic differentiation by Gfi-1 and Gfi-1b that is mediated by the cofactors CoREST and LSD1. A short Gfi-1B isoform controls erythroid differentiation by recruiting the LSD1-CoREST complex through the dimethylation of its SNAG domain. The enzymatic domain of LSD1 plays an important role in repressing the TAL1-directed transcription of GAL4 reporter linked to a thymidine kniase minimal promoter. Furthermore, the TAL1-associated LSD1, HDAC1, and their enzymatic activities are coordinately down-regulated during the early phases of erythroid differentiation. Consistent with the rapid changes of TAL1-corepressor complex during differentiation, TAL1 recruits LSD1 to the silenced p4.2 promoter in undifferentiated, but not in differentiated, murine erythroleukemia (MEL) cells. ShRNA-mediated knockdown of LSD1 in MEL cells resulted in derepression of the TAL1 target gene accompanied by increasing dimeH3K4 at the promoter region. Thus, it appears that histone lysine demethylase LSD1 may negatively regulate TAL1-mediated transcription and that the dynamic regulation of TAL1-associated LSD1/HDAC1 complex may determine the onset of erythroid differentiation programs. Furthermore, RUNX1 has been shown to be part of a large transcription factor complex, together with LDB1, GATA1, TAL1, and ETO2 in erythroid cells. RUNX1 interacts with LSD1 and MYEF2 in erythroid cells. MYEF2 is bound in undifferentiated cells and is lost upon differentiation, whereas LSD1 is bound in differentiated cells. Finally, LSD1 also participates in the trans-repressive effects of SALL4. Based on luciferase assays, the amine oxidase domain of LSD1 is important in suppressing SALL4-mediated reporter transcription. In freshly isolated adult mouse bone marrows, both SALL4 and LSD1 proteins are preferentially expressed in undifferentiated progenitor cells and co-localize in the nuclei. Further sequential chromatin immunoprecipitation assay confirmed that these two factors share the same binding sites at the promoter regions of important hematopoietic regulatory genes including EBF1, GATA1, and TNF. | Gfi-1 and Gfi-1b are homologous transcriptional repressors involved in diverse
developmental contexts, including hematopoiesis and oncogenesis. Transcriptional
repression by Gfi proteins requires the conserved SNAG domain. To elucidate the
function of Gfi proteins, we purified Gfi-1b complexes and identified
interacting proteins. Prominent among these is the corepressor CoREST, the
histone demethylase LSD1, and HDACs 1 and 2. CoREST and LSD1 associate with
Gfi-1/1b via the SNAG repression domain. Gfi-1b further recruits these cofactors
to the majority of target gene promoters in vivo. Inhibition of CoREST and LSD1
perturbs differentiation of erythroid, megakaryocytic, and granulocytic cells as
well as primary erythroid progenitors. LSD1 depletion derepresses Gfi targets in
lineage-specific patterns, accompanied by enhanced histone 3 lysine 4
methylation at the respective promoters. Overall, we show that chromatin
regulatory proteins CoREST and LSD1 mediate transcriptional repression by Gfi
proteins. Lineage-restricted deployment of these cofactors through interaction
with Gfi proteins controls hematopoietic differentiation. TAL1/SCL (hereafter referred to as TAL1) is a critical transcription factor
required for hematopoiesis in which hematopoietic stem cells commit and
differentiate to different lineages. During this process, transcription of many
genes is turned on and off in part by epigenetic mechanisms. TAL1 has recently
been shown to differentially recruit LSD1 and other histone modifying complexes
to regulate its target genes. Here, we focus primarily on epigenetic mechanisms
that are regulated by TAL1 during normal and maligt hematopoiesis. We discuss
how different histone modifying enzymes are recruited by TAL1 and how these
enzymatic activities mediate the activating or repressive function of TAL1.
Finally, we further explore the possible mechanisms by which dysregulation of
the recruitment and activity of histone modifying enzymes contribute to
leukemogenesis. TAL1/SCL is a hematopoietic-specific oncogene and its activity is regulated by
associated transcriptional co-activators and corepressors. Dysregulation of TAL1
activity has been associated with T-cell leukemogenesis. However, it remains
unclear how the interactions between TAL1 and corepressors versus co-activators
are properly regulated. Here, we reported that protein kinase A (PKA)-mediated
phosphorylation regulates TAL1 interaction with the lysine-specific demethylase
(LSD1) that removes methyl group from methylated Lys 4 on histone H3 tails.
Phosphorylation of serine 172 in TAL1 specifically destabilizes the TAL1-LSD1
interaction leading to promoter H3K4 hypermethylation and activation of target
genes that have been suppressed in normal and maligt hematopoiesis. Knockdown
of TAL1 or LSD1 led to a derepression of the TAL1 target genes in T-cell acute
lymphoblast leukemia (T-ALL) Jurkat cells, which is accompanied by elevating
promoter H3K4 methylation. Similarly, treatment of PKA activator forskolin
resulted in derepression of target genes by reducing its interaction with LSD1
while PKA inhibitor H89 represses them by suppressing H3K4 methylation levels.
Consistent with the dual roles of TAL1 in transcription, TAL1-associated LSD1 is
decreased while recruitment of hSET1 is increased at the TAL1 targets during
erythroid differentiation. This process is accompanied by a dramatic increase in
H3K4 methylation. Thus, our data revealed a novel interplay between PKA
phosphorylation and TAL1-mediated epigenetic regulation that regulates
hematopoietic transcription and differentiation programs during hematopoiesis
and leukemogenesis. Lysine (K)-specific demethylase 1A (LSD1/KDM1A) has been identified as a
potential therapeutic target in solid cancers and more recently in acute myeloid
leukemia. However, the potential side effects of a LSD1-inhibitory therapy
remain elusive. Here, we show, with a newly established conditional in vivo
knockdown model, that LSD1 represents a central regulator of hematopoietic stem
and progenitor cells. LSD1 knockdown (LSD1-kd) expanded progenitor numbers by
enhancing their proliferative behavior. LSD1-kd led to an extensive expansion of
granulomonocytic, erythroid and megakaryocytic progenitors. In contrast,
terminal granulopoiesis, erythropoiesis and platelet production were severely
inhibited. The only exception was monopoiesis, which was promoted by LSD1
deficiency. Importantly, we showed that peripheral blood granulocytopenia,
monocytosis, anemia and thrombocytopenia were reversible after LSD1-kd
termination. Extramedullary splenic hematopoiesis contributed to the phenotypic
reversion, and progenitor populations remained expanded. LSD1-kd was associated
with the upregulation of key hematopoietic genes, including Gfi1b, Hoxa9 and
Meis1, which are known regulators of the HSC/progenitor compartment. We also
demonstrated that LSD1-kd abrogated Gfi1b-negative autoregulation by crossing
LSD1-kd with Gfi1b:GFP mice. Taken together, our findings distinguish LSD1 as a
critical regulator of hematopoiesis and point to severe, but reversible, side
effects of a LSD1-targeted therapy. The stem cell protein SALL4 plays a critical role in hematopoiesis by regulating
the cell fate. In primitive hematopoietic precursors, it activates or represses
important genes via recruitment of various epigenetic factors such as DNA
methyltransferases, and histone deacylases. Here, we demonstrate that LSD1, a
histone lysine demethylase, also participates in the trans-repressive effects of
SALL4. Based on luciferase assays, the amine oxidase domain of LSD1 is important
in suppressing SALL4-mediated reporter transcription. In freshly isolated adult
mouse bone marrows, both SALL4 and LSD1 proteins are preferentially expressed in
undifferentiated progenitor cells and co-localize in the nuclei. Further
sequential chromatin immunoprecipitation assay confirmed that these two factors
share the same binding sites at the promoter regions of important hematopoietic
regulatory genes including EBF1, GATA1, and TNF. In addition, studies from both
gain- and loss-of-function models revealed that SALL4 dynamically controls the
binding levels of LSD1, which is accompanied by a reversely changed histone 3
dimethylated lysine 4 at the same promoter regions. Finally, shRNA-mediated
knockdown of LSD1 in hematopoietic precursor cells resulted in altered SALL4
downstream gene expression and increased cellular activity. Thus, our data
revealed that histone demethylase LSD1 may negatively regulate SALL4-mediated
transcription, and the dynamic regulation of SALL4-associated epigenetic factors
cooperatively modulates early hematopoietic precursor proliferation. |
For the treatment of which conditions can atypical neuroleptic drugs be used? | Atypical neuroloeptic drugs are antipsychotics used in patients with schizophrenia, schizoaffective disorder, delusional disorder, psychotic disorders, psychotic relapse in neuroleptic malignant syndrome and attention deficit hyperactivity disorder when presenting with negativism and conduct disorder. | Acute and late onset movement disorders frequently complicate the treatment of
psychosis with typical neuroleptic drugs like haloperidol, but not with atypical
neuroleptic drugs like clozapine. Although the neural mechanisms underlying
neuroleptic-induced movement disorders remain unknown, alterations in basal
ganglia function are likely involved. A potential role for the endogenous opiate
peptides in neuroleptic-induced movement disorders is suggested by the
immunocytochemical localization of met5-enkephalin (ME) in the striatopallidal
projection pathway, and by the increased levels of ME measured by
radioimmunoassay in the rat caudate-putamen nuclei (CPN) following haloperidol
treatment. We sought to determine whether met5-enkephalin-like immunoreactivity
(MELI) in terminal fields within globus pallidus and in perikarya in CPN was
differentially altered in rats chronically treated with haloperidol or
clozapine. Acrolein-fixed forebrain sections were collected from cohorts of
adult rats receiving 21-day oral administration of haloperidol, clozapine, or
water. Sections from the three treatment groups were collectively processed for
immunocytochemical labeling using varying dilutions of ME antiserum and the
avidin-biotin peroxidase method. In globus pallidus, densitometry measures
revealed significantly increased levels of immunoperoxidase labeling for ME in
haloperidol-treated, but not in clozapine-treated animals. In CPN, optical
densitometry as well as cell counting measurements also showed a significant
increase in MELI only in the haloperidol-treated group. These results support
the concept that alterations in endogenous opiate peptides in basal ganglia may
contribute to movement disorders seen in patients receiving typical neuroleptic
drugs.(ABSTRACT TRUNCATED AT 250 WORDS) Neuroleptic maligt syndrome (NMS) was first recognized as a life-threatening
complication of dopamine receptor antagonists characterized by extrapyramidal
disturbances, hyperthermia, and elevated serum creatine kinase levels. Concepts
of NMS have changed because medications other than classic neuroleptic drugs
have been implicated as triggering agents and because syndromes identical to NMS
have been observed in patients with Parkinson's disease withdrawn from their
medication or suffering akinetic hyperthermic parkinsonian crisis. The
neurochemical key features in all these conditions are probably functional
dopamine deficiency and ensuing hyperactivity of excitatory amino acid
neurotransmission in the basal ganglia and hypothalamus. Recognition of NMS is
the most important step in its management; the outcome is good if causative
drugs are discontinued or if parkinsonian therapy is readjusted. Supportive care
includes management of hyperthermia and fluid replacement. Controversial
therapeutic measures include the application of dopamine receptor agonists,
excitatory amino acid antagonists, or dantrolene. Psychiatric patients with a
history of NMS and psychotic relapse necessitating neuroleptic drugs do not
commonly redevelop NMS when reexposed to dopamine receptor antagonists but may
be treated most safely with atypical neuroleptic drugs such as clozapine. Recent studies suggest that clozapine is more effective than typical
neuroleptics for patients with treatment-resistant schizophrenia. Although other
investigations suggest that clozapine may also be at least as effective, and
probably more so, than typical neuroleptics for individuals with acute
psychosis, the toxicity of this drug has caused its use to be restricted to
patients who have demonstrated resistance to previous treatment. The hypothesis
behind this article, however, is that clozapine may not only be more effective
than typical neuroleptics for individuals with "first-episode" schizophrenia but
may also lead to a better long-term course in such patients. This hypothesis is
based on the clinical literature concerning clinical and biological response to
typical and atypical neuroleptic drugs, as well as on preliminary findings from
studies of clinical, neuroendocrine, and biochemical effects that occur during
treatment with haloperidol but not with clozapine. When examined in light of
Wyatt's recent proposal that each period of symptom exacerbation may lay the
groundwork for further symptoms and for increasing syndrome severity, the data
suggest that clozapine, despite its disturbing side-effect profile, should be
studied in controlled double-blind clinical trials during patients' first
episode of schizophrenia. If such investigations show that clozapine is more
effective than typical neuroleptics for patients with first-episode
schizophrenia and results in a better long-term course, then its benefits and
risk as a routine first-line treatment for schizophrenia can be considered. The
findings of these studies may also lead us to the regular clinical use of new
agents that are less toxic than clozapine but have similar clinical and
biological profiles. During clinical experience with the "atypical" neuroleptic drugs clozapine,
risperidone, and zotepine, some patients have shown a marked weight gain. To
prove whether weight gain is a relevant side effect of atypical neuroleptics,
the charts of all patients admitted with DSM-III-R diagnoses of schizophrenia,
schizoaffective disorder, or delusional disorder in the years 1991 to 1995 were
evaluated. A retrospective chart review was performed, which included all
patients who were treated longer than 2 weeks with a single neuroleptic. The
data analysis showed that weight gain must be considered as a common side effect
of atypical neuroleptics (clozapine, risperidone, sulpiride, or zotepine). The
mean weight gain (3.1, 1.5, 1.9, or 4.3 kg, respectively) was significantly
higher than that of patients treated with "classic" neuroleptics (mean, 0.0-0.5
kg) (Kruskal-Wallis, p = 0.01). Young and not obese patients show the highest
weight increase. Because weight gain occurs in the first weeks of treatment,
particularly in previously untreated subjects, this side effect has to be
considered in view of compliance with long-term neuroleptic medication. While the treatment of positive symptoms of patients with schizophrenic
psychosis appeared until recently to be solely pharmacotherapeutic, new research
findings show the efficacy of cognitive-behavioural psychotherapy (CBT) on
positive symptoms in chronic psychotic patients. In addition, the effectiveness
even in acute and recent-onset psychosis could be shown in some studies. The
effects of CBT and standard care in psychosis compared to standard care alone
and to other psychosocial interventions plus standard care are reviewed. The
results of several studies and one meta-analysis show that CBT in schizophrenia
patients has a direct effect on psychotic symptoms such as hallucinations as
well as on relapse prevention. In routine settings,however,CBT has until now
only rarely been delivered to these patients. In so-called large pragmatic
trials, which might be subsumed as phase IIIb studies, the effects are tested.
The therapeutic approach with the components of CBT for psychosis are described:
building a therapeutic relationship, cognitive-behavioural coping strategies,
developing an understanding of the experience of psychosis,working on
hallucinations and delusions, addressing negative self-evaluations, anxiety, and
depression,managing risk of relapse and social disability. Further clinical
implications are described (capability of learning the therapeutic strategies,
deliverability in broader clinical settings, acceptability by patients,
combination with atypical neuroleptic drugs,and treatment of choice in risk
populations). The study examines the effect of different types of antipsychotic treatment on
the health related quality of life (HRQL) of people with schizophrenia under
naturalistic outpatient treatment conditions. In a prospective study design, 307
schizophrenic patients were followed over a period of 2.5 years. HRQL, clinical
characteristics, and type of antipsychotic medication were assessed five times
every 6 months. HRQL was assessed by the SF-36. Random effect regression models
were computed for the SF-36 mental (MCS) and physical (PCS) component scores.
Propensity scores were included in the regression models to reduce a possible
sample selection bias. Monotherapeutic treatment with new atypical neuroleptic
drugs had a more positive effect on the mental health related quality of life
(MCS) in comparison to treatment with polypharmacological treatment but not with
oral conventional antipsychotics. Monopharmaceutical treatment with
depot-antipsychotic drugs had a more positive effect on the physical health
related quality of life (PCS) in comparison to polypharmacological treatment.
Study results indicate that atypical antipsychotic drugs are not superior to
conventional antipsychotics with regard to the effect on QOL. However,
monopharmaceutical treatment can be assumed to be more effective in improving
mental and physical related QOL than polypharmaceutical treatment. INTRODUCTION: Attention deficit hyperactivity disorder (ADHD) is a
neurobiological condition essentially characterised by inattention,
hyperactivity and impulsiveness, and has a prevalence of around 5%. Because it
is a biological disorder, both boys and girls with ADHD display these same
symptoms, but more boys are diagnosed with ADHD (in a ratio of 3 to 1).
AIM: To examine the differences between the two sexes, their prevalence and
possible female subtypes in ADHD.
PATIENTS AND METHODS: We conducted a retrospective study of 172 patients of both
sexes who were attended as hospital neuropaediatric outpatients in the year 2004
according to Diagnostic and statistical manual of mental disorders (DSM-IV-TR)
criteria. Their ages ranged between 4 and 14 years and they were divided into
three groups: under 6, between 6 and 10, and from 11 to 14 years old. The girls
were subdivided into four subtypes, in order of greater to lesser prevalence:
shy, hypersociable, hyperactive and changeable.
RESULTS: Both sexes showed the same response to methylphenidate. Only the group
of boys presented other comorbidities such as negativism and conduct disorders;
approximately 25% of them required treatment with atypical neuroleptic drugs.
CONCLUSIONS: a) Girls have certain specific clinical manifestations within the
three common symptoms; b) methylphenidate is equally effective in both sexes; c)
only boys display other disorders such as negativism and conduct disorders; and
d) the brains of males and females are quite similar, but symptoms are expressed
differently depending on environments and levels. |
Which are the characteristics of Andersen syndrome? | the characteristics of Andersen syndrome are abnormal QT-U complex, ventricular arrhythmia, periodic paralysis, and facial and skeletal dysmorphisms | Andersen's syndrome is a clinically distinct form of potassium-sensitive
periodic paralysis associated with cardiac dysrhythmias. The subtle nature of
the cardiac and dysmorphic features may delay the recognition of this syndrome
and its potentially lethal cardiac dysrhythmias. The genetic defect in
Andersen's syndrome is not genetically linked to other forms of
potassium-sensitive periodic paralysis and is probably distinct from the long QT
syndrome locus. Andersen syndrome is a rare entity and comprises potassium sensitive periodic
paralysis, ventricular arrhythmia, and an unusual facial appearance; syncope and
sudden death have also been reported. The recognition of the characteristic face
permits an early diagnosis in order to detect the severe systemic manifestations
that are associated with this syndrome. The genetic defect is not linked to any
other form of potassium sensitive periodic paralysis nor is it related to that
of the long QT syndrome; nevertheless, a prolonged QT interval can be detected
in a significant proportion of the cases. Sixteen cases of this syndrome have
been described. We report on a three-generation family with 10 affected members.
To our knowledge, this is the largest number of cases reported in one family. We
noted some additional minor anomalies such as broad forehead and malar
hypoplasia. Our patients had variable expression in the classical triad and of
the severity of the systemic manifestations. Five of 8 affected studied members
did not have a long QTc, which has been suggested as a constant finding in this
syndrome. Evaluation of candidate loci culminated in the identification of a heterozygous
missense mutation (R67W) in KCNJ2, the gene encoding the inward-rectifying
potassium current, Kir2.1, in 41 members of a kindred in which ventricular
arrhythmias (13 of 16 female members [81%]) and periodic paralysis (10 of 25
male members [40%]) segregated as autosomal domit traits with sex-specific
variable expressivity. Some mutation carriers exhibited dysmorphic features,
including hypertelorism, small mandible, syndactyly, clinodactyly, cleft palate,
and scoliosis, which, together with cardiodysrhythmic periodic paralysis, have
been termed "Andersen syndrome." However, no individual exhibited all
manifestations of Andersen syndrome, and this diagnosis was not considered in
the proband until other family members were examined. Other features seen in
this kindred included unilateral dysplastic kidney and cardiovascular
malformation (i.e., bicuspid aortic valve, bicuspid aortic valve with
coarctation of the aorta, or valvular pulmonary stenosis), which have not been
previously associated. Nonspecific electrocardiographic abnormalities were
identified in some individuals, but none had a prolonged QT interval.
Biophysical characterization of R67W demonstrated loss of function and a
domit-negative effect on Kir2.1 current. These findings support the
suggestion that, in addition to its recognized role in function of cardiac and
skeletal muscle, KCNJ2 plays an important role in developmental signaling. INTRODUCTION: Recent advances in molecular genetic research have provided new
insights into severe ventricular arrhythmias related to channelopathies.
CASE REPORT: A case of Andersen's syndrome followed during fourteen years is
reported. This rare familial periodic paralysis is characterized by its
association with dysmorphic features (micrognatia) and ventricular arrhythmias.
COMMENTS: Andersen's syndrome has been attributed to a mutation in the KCNJ2
gene which is involved not only in stabilizing cardiac rhythm, but also in
modulating the excitability of skeletal muscle and in morphogenesis. This
disease must be distinguished from hyperkalemic periodic paralysis due to a
mutation in the skeletal muscle sodium channel gene (SCN4A) and from hypokalemic
periodic paralysis related to dihydropyridine receptor mutation (CACNL1A3).
Furthermore, it may not be confused with others rhythmic channelopathies (long
QT syndromes, catecholaminergic polymorphic ventricular tachycardia and
Brugada's syndrome). OBJECTIVE: The Andersen's syndrome is a hereditary disease, which is
characterized by cardiac arrhythmias, periodic paralysis and dysmorphic
features. Recently, mutations of the KCNJ2 gene, which encodes the inward
rectifying potassium channel subunit Kir2.1, have been identified in affected
individuals. However, the functional effects of these mutations have not yet
been fully elucidated.
METHODS AND RESULTS: To clarify this situation we generated known Andersen
disease mutants of KCNJ2 which did not yield any measurable K(+) currents in CHO
cells indicating that the Andersen mutants failed to form functional
homomultimeric complexes. EGFP-tagged KCNJ2 wild-type and mutant channels
distributed in a similar homogeneous pattern in the cell membrane suggesting
that protein trafficking was not altered by the Andersen mutations but rather
implicating that the mutations rendered the KCNJ2 channel non-functional. In
heterologous coexpression experiments the Andersen mutants exerted a
domit-negative effect on wild-type KCNJ2. However, the extent of suppression
varied between the different KCNJ2 mutants. Given our results in CHO cells, we
expressed the disease mutant KCNJ2-S136F in neonate rat cardiomyocytes using
adenoviral gene transfer to test the effect of Andersen mutants on native I(K1).
I(K1) density was indeed significantly reduced in KCNJ2-S136F-infected cells
(n=9) compared to control cells (n=9) over a voltage range from -70 to -150 mV
(P<0.05).
CONCLUSION: These results support that Kir2.x channels are a critical component
of native I(K1) in neonate rat cardiomyocytes and that a domit-negative
suppression of I(K1) in native cells is the pathophysiological correlate of the
Andersen's syndrome. Andersen syndrome includes a clinical triad with periodic paralysis, cardiac
arrhythmia and dysmorphic features most often mild but relevant. It is a
potassium channelopathy due to mutation of KCJN2 gene coding for Kir 2.1
protein. We report a familial case with mutation R218W of Kir 2.1 and discuss
the main phenotypic and genetic aspects of Andersen syndrome. Muscle
manifestations are essentially a periodic paralysis most often of hypokaliemic
type. Muscle biopsy reveals tubular aggregates but can be normal as it is shown
in the same patient in our kindred. Our proband complained of paralytic attacks
since childhood and at adult age she demonstrated a mild permanent deficit of
pelvic girdle muscles as it has been described in other types of periodic
paralysis after a long duration course. Cardiac manifestations may include in a
variable manner a long QT syndrome, premature ventricular contractions, complex
ventricular ectopy, polymorphic or bidirectional ventricular tachycardia.
Imipramine had a positive effect on arrhythmia in our case. Dysmorphic features
are often mild and have to be cautiously looked for as a clue to the diagnosis
of Andersen syndrome. They can be easily overlooked if not systematically looked
for. Clinical expressivity is variable including in the same family. In our
observation, the daughter showed a complete triad, early expressed, which
allowed the diagnosis. Her father was late diagnosed on ventricular dysrhytmia
but without muscle manifestations and dysmorphic features. Since KCJN2 gene
mutation identification, locus heterogeneity of Andersen syndrome was shown.
Andersen syndrome kindreds without mutations in KCNJ2 were clinically
indistinguishable from KCNJ2-associated subjects. KCNJ2 gene encodes the inward
rectifier K+ channel Kir2.1 which plays an important role in maintaining
membrane potential and during the terminal phase of cardiac action potential
repolarization. Several studies showed a domit negative effect of the
mutation on Kir 2.1 channel function. BACKGROUND: Andersen-Tawil syndrome (ATS) is a rare inherited disorder,
characterised by periodic paralysis, cardiac dysarrhythmias, and dysmorphic
features, and is caused by mutations in the gene KCNJ2, which encodes the inward
rectifier potassium channel, Kir2.1. This study sought to analyse KCNJ2 in
patients with familial ATS and to determine the functional characteristics of
the mutated gene.
METHODS AND RESULTS: We screened a family with inherited ATS for the mutation in
KCNJ2, using direct DNA sequencing. A missense mutation (T75R) of Kir2.1,
located in the highly conserved cytoplasmic N-terminal domain, was identified in
three affected members of this family. Using the Xenopus oocyte expression
system and whole cell voltage clamp analyses, we found that the T75R mutant was
non-functional and possessed a strong domit negative effect when co-expressed
with the same amount of wild type Kir2.1. Transgenic (Tg) mice expressing the
mutated form of Kir2.1 in the heart had prolonged QTc intervals compared with
mice expressing the wild type protein. Ventricular tachyarrhythmias were
observed in 5 of 14 T75R-Tg mice compared with 1 of 7 Wt-Tg and none of 6
non-transgenic littermates. In three of five T75R-Tg mice with ventricular
tachycardia, their ECG disclosed bidirectional tachycardia as in our proband.
CONCLUSIONS: The in vitro studies revealed that the T75R mutant of Kir2.1 had a
strong domit negative effect in the Xenopus oocyte expression system. It
still preserved the ability to co-assemble and traffic to the cell membrane in
mammalian cells. For in vivo studies, the T75R-Tg mice had bidirectional
ventricular tachycardia after induction and longer QT intervals. In this report we describe the case of a 42-year-old woman who experienced an
episode of near drowning during recreational swimming. A diagnosis of
Andersen-Tawil syndrome was made based on the patient's dysmorphic features,
characteristic T-U-wave patterns and ventricular arrhythmias. To our knowledge,
this is the first report of a swimming-triggered cardiac event in a patient with
Andersen-Tawil syndrome. Andersen syndrome (AS) is a rare disease characterized by the presence of
periodic paralysis (PP), cardiac arrhythmia and dysmorphic abnormalities. We
report herein the first Brazilian patient presenting AS who also had obesity,
obstructive sleep apnea (OSA) and daytime sleepiness. Clinical and genetic
evaluation of six family members demonstrated that four had dysmorphic
abnormalities but none had PP or cardiac arrhythmia. Sequencing of KCNJ2
revealed the R218W mutation in the index patient and her 6-year-old daughter,
who presented dysmorphic abnormalities (micrognathia, clinodactyly of fourth and
fifth fingers, short stature) and OSA. Three relatives had clinodactyly as the
only manifestation but the R218W mutation was absent, suggesting that this
characteristic may be influenced by another gene. OSA accompanied by dysmorphic
features may be related to AS. Andersen-Tawil syndrome (ATS) is a multisystem inherited disease exhibiting
periodic paralysis, cardiac arrhythmias, and dysmorphic features. In this study,
we characterized the KCNJ2 channels with an ATS mutation (T75M) which is
associated with cardiac phenotypes of bi-directional ventricular tachycardia,
syncope, and QT(c) prolongation. Confocal imaging of GFP-KCNJ2 fusion proteins
showed that the T75M mutation impaired membrane localization of the channel
protein, which was restored by co-expression of WT channels with T75M channels.
Whole-cell patch-clamp experiments in CHO-K1 cells showed that the T75M mutation
produced a loss-of-function of the channel. When both WT and the T75M were
co-expressed, the T75M mutation showed domit-negative effects on inward
rectifier K+ current densities, with prominent suppression of outward currents
at potentials between 0 mV and +80 mV over the E(K). Inside-out patch
experiments in HEK293T cells revealed that co-expression of WT and the T75M
channels enhanced voltage-dependent block of the channels by internal Mg2+,
resulting in enhanced inward rectification at potentials 50 mV more positive
than the E(K). We suggest that the T75M mutation causes domit-negative
suppression of the co-expressed WT KCNJ2 channels. In addition, the T75M
mutation caused alteration of gating kinetics of the mutated KCNJ2 channels,
i.e., increased sensitivity to intracellular Mg2+ and resultant enhancement of
inward rectification. The data presented suggest that the mutation may influence
clinical features, but it does not directly show this. Andersen-Tawil syndrome (ATS) is characterized by ventricular arrhythmias,
hypokalemic periodic paralysis and developmental anomalies. It is caused by
mutations in the KCNJ2 gene that encodes for the alpha-subunit of Kir2.1, a K(+)
channel responsible for cardiac repolarization. Providing effective therapy to
reduce arrhythmia burden and risk of sudden death is challenging, especially in
the context of pregcy and childbirth. We report a case of a pregt
27-year-old woman with an R218W mutation in the C-terminal interaction domain of
KCNJ2 causing ATS. Regular cardiac and obstetric assessments were performed for
the duration of the pregcy, which carried to term and delivered successfully
with potassium replacement and intravenous beta blockade. ATS is a rare and
potentially lethal condition in which there is considerable genetic and
phenotypic heterogeneity. Effective management strategies are directed at
reducing symptoms, arrhythmia burden and sudden cardiac death. This case
illustrates the challenges and approach to management of patients with ATS who
are pregt and undergo childbirth. Andersen-Tawil syndrome includes a clinical triad consisting of periodic
paralysis, cardiac arrhythmia, and usually mild but diagnostically useful
dysmorphic features. This potassium channelopathy is due to mutation of the
KCNJ2 gene encoding the protein Kir 2.1. The main muscular manifestation is
periodic paralysis, usually of the hypokalemic type. Muscle biopsy may reveal
tubular aggregates or be normal, as in our patient. Cardiac manifestations are
variable and may include a long QT syndrome, premature ventricular contractions,
complex ventricular ectopy, and polymorphic or bidirectional ventricular
tachycardia. Imipramine therapy had a positive effect on arrhythmia in our
patient. Dysmorphic features provide a diagnostic clue but may be difficult to
identify and should thus be methodically sought. Clinical expression is
variable, even within the same family. Since the culprit gene KCNJ2 was
identified, locus heterogeneity has been shown in Andersen-Tawil syndrome.
Kindreds without KCNJ2 mutations are clinically indistinguishable from those
with mutations. Kir2.1 is an inward rectifier K+ channel with important roles in
maintaining membrane potential and during the terminal phase of cardiac action
potential repolarization. Several studies show a domit negative effect of
KCNJ2 mutation on Kir 2.1 channel function. Andersen's syndrome is a rare disorder that has been defined with a triad:
periodic paralysis, cardiac arrhythmia, and development anomalies. Muscle
weakness has been reported in two-thirds of the patients. KCNJ2 remains the only
gene linked to Andersen's syndrome; this gene encodes for the alpha-subunit of
the strong inward-rectifier K+ channel Kir2.1. Several studies have shown that
Andersen's syndrome mutations lead to a loss of function of the K+ channel
activity in vitro. However, ex vivo studies on isolated patient muscle tissue
have not been reported. We have performed muscle biopsies of controls and
patients presenting with clinically and genetically defined Andersen's syndrome
disorder. Myoblasts were cultured and characterized morphologically and
functionally using the whole cell patch-clamp technique. No morphological
difference was observed between Andersen's syndrome and control myoblasts at
each passage of the cell culture. Cellular proliferation and viability were
quantified in parallel with direct cell counts and showed no difference between
control and Andersen's syndrome patients. Moreover, our data show no significant
difference in myoblast fusion index among Andersen's syndrome and control
patients. Current recordings carried out on myotubes revealed the absence of an
inwardly rectifying Ba2+-sensitive current in affected patient cells. One
consequence of the Ik1 current loss in Andersen's syndrome myotubes is a shift
of the resting membrane potential toward depolarizing potentials. Our data
describe for the first time the functional consequences of Andersen's syndrome
mutations ex vivo and provide clues to the K+ channel pathophysiology in
skeletal muscle. Andersen cardiodysrhythmic periodic paralysis or Andersen-Tawil syndrome
includes the distinct clinical features of periodic paralysis, cardiac
arrhythmia, and facial and skeletal dysmorphisms and exhibits autosomal domit
inheritance. Mutations in the KCNJ2 gene, which encodes the human inward
rectifier potassium channel Kir2.1, have been identified in the majority of
cases. Despite well-established clinical and molecular characteristics,
treatment is still case oriented, and timely diagnosis could be delayed because
of the low incidence and phenotypic heterogeneity of this disease. This article
describes the clinical and molecular features of 3 cases of Andersen-Tawil
syndrome in 2 families. One of the mutations (G144D) was located in the pore
selectivity filter residue (which is mutated recurrently) and was considered
novel. Intermittent muscle weakness in childhood warrants careful evaluation of
cardiac dysrhythmia and skeletal anomalies. Andersen-Tawil syndrome is an uncommon inherited autosomal disorder
characterized by a prolonged QT interval, periodic paralysis, and dysmorphic
features. The deleterious effects of cardioplegia on periodic paralysis and
cardiac arrhythmia are unknown, and no studies have reported the performance of
cardiac surgery in patients with Andersen-Tawil syndrome. We present a case of
successful cardiac surgery in a patient with Andersen-Tawil syndrome, without
using cardioplegia. Andersen Tawil syndrome is a rare type of channelopathy characterized by the
presence of periodic paralysis, cardiac arrhythmia (prolonged QT interval or
ventricular arrhythmia) and distinct dysmorphic abnormalities. It is a type of
potassium channelopathy that occurs sporadically or by autosomal domit
inheritance. We report a 14 year old boy with Andersen-Tawil syndrome. BACKGROUND: Mutations of KCNJ2, the gene encoding the human inward rectifier
potassium channel Kir2.1, cause Andersen-Tawil syndrome (ATS), a disease
exhibiting ventricular arrhythmia, periodic paralysis, and dysmorphic features.
However, some KCNJ2 mutation carriers lack the ATS triad and sometimes share the
phenotype of catecholaminergic polymorphic ventricular tachycardia (CPVT). We
investigated clinical and biophysical characteristics of KCNJ2 mutation carriers
with "atypical ATS."
METHODS AND RESULTS: Mutational analyses of KCNJ2 were performed in 57 unrelated
probands showing typical (≥2 ATS features) and atypical (only 1 of the ATS
features or CPVT) ATS. We identified 24 mutation carriers. Mutation-positive
rates were 75% (15/20) in typical ATS, 71% (5/7) in cardiac phenotype alone,
100% (2/2) in periodic paralysis, and 7% (2/28) in CPVT. We divided all carriers
(n=45, including family members) into 2 groups: typical ATS (A) (n=21, 47%) and
atypical phenotype (B) (n=24, 53%). Patients in (A) had a longer QUc interval
[(A): 695 ± 52 versus (B): 643 ± 35 ms] and higher U-wave amplitude (0.24 ± 0.07
versus 0.18 ± 0.08 mV). C-terminal mutations were more frequent in (A) (85%
versus 38%, P<0.05). There were no significant differences in incidences of
ventricular tachyarrhythmias. Functional analyses of 4 mutations found in (B)
revealed that R82Q, R82W, and G144D exerted strong domit negative suppression
(current reduction by 95%, 97%, and 96%, respectively, versus WT at -50 mV) and
T305S moderate suppression (reduction by 89%).
CONCLUSIONS: KCNJ2 gene screening in atypical ATS phenotypes is of clinical
importance because more than half of mutation carriers express atypical
phenotypes, despite their arrhythmia severity. Andersen-Tawil syndrome (ATS) is characterized by dysmorphic features, periodic
paralyses and abnormal ventricular repolarization. After genotyping a large set
of patients with congenital long-QT syndrome, we identified two novel,
heterozygous KCNJ2 mutations (p.N318S, p.W322C) located in the C-terminus of the
Kir2.1 subunit. These mutations have a different localization than classical ATS
mutations which are mostly located at a potential interaction face with the
slide helix or at the interface between the C-termini. Mutation carriers were
without the key features of ATS, causing an isolated cardiac phenotype. While
the N318S mutants regularly reached the plasma membrane, W322C mutants primarily
resided in late endosomes. Co-expression of N318S or W322C with wild-type Kir2.1
reduced current amplitudes only by 20-25 %. This mild loss-of-function for the
heteromeric channels resulted from defective channel trafficking (W322C) or
gating (N318S). Strikingly, and in contrast to the majority of ATS mutations,
neither mutant caused a domit-negative suppression of wild-type Kir2.1,
Kir2.2 and Kir2.3 currents. Thus, a mild reduction of native Kir2.x currents by
non domit-negative mutants may cause ATS with an isolated cardiac phenotype. |
How are induced pluripotent stem cells used in the study and treatment of cardiovascular diseases? | The major goal within the field of cardiovascular regenerative medicine is to replace lost or damaged cardiac muscle and coronaries following ischaemic disease. At present, de novo cardiomyocytes can be generated either in vitro, using directed differentiation of embryonic stem cells or induced pluripotent stem cells, or in vivo via direct reprogramming of resident adult cardiac fibroblast or ectopic stimulation of resident cardiac stem or progenitor cells. The production of human cardiac progenitor cells and cardiomyocytes from human pluripotent stem cells provides an amenable source of cells for applications in drug discovery, disease modeling, regenerative medicine, and cardiotoxicity screening. In addition, the ability to derive human-induced pluripotent stem cells from somatic tissues, combined with current high-throughput screening and pharmacogenomics, may help realize the use of these cells to fulfill the potential of personalized medicine. Human induced pluripotent stem cells (iPSC) provide a unique opportunity to study "disease in a dish" within a defined genetic and environmental background. Patient-derived iPSCs have been successfully used to model cardiomyopathies, rhythm disorders and vascular disorders. Long-QT syndrome and catecholaminergic polymorphic ventricular tachycardia are two heart rhythm disorders that have been already successfully modeled by several groups using this approach, which will likely serve to model other mono- or polygenetic cardiovascular disorders in the future. The use of iPSC-derived cardiomyocytes to study genetic cardiovascular disorders will enable a deeper and more applicable understanding of the molecular mechanisms of human disease, as well as improving our ability to achieve successful cell-based therapies. | PURPOSE OF REVIEW: The development of induced pluripotent stem cell (iPSC)
technology has led to many advances in the areas of directed cell
differentiation and characterization. New methods for generating iPSC-derived
cardiomyocytes provide an invaluable resource for the study of certain
cardiovascular disorders. This review highlights the current technology in this
field, its application thus far to the study of genetic disorders of the
RAS/MAPK pathway and long-QT syndrome (LQTS), and future directions for the
field.
RECENT FINDINGS: Enhanced methods increase the efficiency of generating and
stringently purifying iPSC-derived cardiomyocytes. The use of cardiomyocytes
derived from patients with LEOPARD syndrome and LQTS has shed light on the
molecular mechanisms of disease and validated their use as reliable human
disease models.
SUMMARY: The use of iPSC-derived cardiomyocytes to study genetic cardiovascular
disorders will enable a deeper and more applicable understanding of the
molecular mechanisms of human disease, as well as improving our ability to
achieve successful cell-based therapies. Methods to efficiently generate these
cells are improving and provide promise for future applications of this
technology. The successful derivation of human induced pluripotent stem cells (hiPSCs) by
dedifferentiation of somatic cells offers significant potential to overcome
obstacles in the field of cardiovascular disease. hiPSC derivatives offer
incredible potential for new disease models and regenerative medicine therapies.
However, many questions remain regarding the optimal starting materials and
methods to enable safe, efficient derivation of hiPSCs suitable for clinical
applications. Initial reprogramming experiments were carried out using
lentiviral or retroviral gene delivery methods. More recently, various nonviral
methods that avoid permanent and random transgene insertion have emerged as
alternatives. These include transient DNA transfection using plasmids or
minicircles, protein transduction, or RNA transfection. In addition, several
small molecules have been found to significantly augment hiPSC derivation
efficiency, allowing the use of a fewer number of genes during pluripotency
induction. We review these various methods for the derivation of hiPSCs,
focusing on their ultimate clinical applicability, with an emphasis on their
potential for use as cardiovascular therapies and disease-modeling platforms. Human induced pluripotent stem (iPS) cells potentially provide a unique resource
for generating patient-specific cardiomyocytes to study cardiac disease
mechanisms and treatments. However, existing approaches to cardiomyocyte
production from human iPS cells are inefficient, limiting the application of iPS
cells in basic and translational cardiac research. Furthermore, strategies to
accurately record changes in iPS cell-derived cardiomyocyte action potential
duration (APD) are needed to monitor APD-related cardiac disease and for rapid
drug screening. We examined whether modulation of the bone morphogenetic protein
4 (BMP-4) and Wnt/β-catenin signaling pathways could induce efficient cardiac
differentiation of human iPS cells. We found that early treatment of human iPS
cells with BMP-4 followed by late treatment with small molecule Wnt inhibitors
led to a marked increase in production of cardiomyocytes compared to existing
differentiation strategies. Using immunocytochemical staining and real-time
intracellular calcium imaging, we showed that these induced cardiomyocytes
expressed typical sarcomeric markers, exhibited normal rhythmic Ca(2+)
transients, and responded to both β-adrenergic and electric stimulation.
Furthermore, human iPS cell-derived cardiomyocytes demonstrated characteristic
changes in action potential duration in response to cardioactive drugs
procainamide and verapamil using voltage-sensitive dye-based optical recording.
Thus, modulation of the BMP-4 and Wnt signaling pathways in human iPS cells
leads to highly efficient production of cardiomyocytes with typical
electrophysiological function and pharmacologic responsiveness. The use of human
iPS cell-derived cardiomyocytes and the application of calcium- and
voltage-sensitive dyes for the direct, rapid measurement of iPS cell-derived
cardiomyocyte activity promise to offer attractive platforms for studying
cardiac disease mechanisms and therapeutics. Cardiovascular disease remains the leading cause of morbidity and mortality in
the developed countries. This review summarizes current pre-clinical and
clinical evidence for the potential role and mechanisms of action of stem and
progenitor cells in vascular and cardiac repair and regeneration. Apart from
cell transplantation strategies, approaches to maintain stem cell niche function
and targeting mobilization/recruitment of specific stem/progenitor cell
populations may aid in preserving vascular and cardiac function. Moreover, with
the use of patient-derived induced pluripotent stem cells, the field of
regenerative medicine is entering a new era. Potential applications of induced
pluripotent stem cells and direct reprogrammed cells as well as recent
developments in tissue engineering are discussed. The discovery that somatic cells can be reprogrammed to induced pluripotent stem
cells (iPSC) by overexpression of a combination of transcription factors bears
the potential to spawn a wealth of new applications in both preclinical and
clinical cardiovascular research. Disease modeling, which is accomplished by
deriving iPSC lines from patients affected by heritable diseases and then
studying the pathophysiology of the diseases in somatic cells differentiated
from these patient-specific iPSC lines, is the so far most advanced of these
applications. Long-QT syndrome and catecholaminergic polymorphic ventricular
tachycardia are two heart rhythm disorders that have been already successfully
modeled by several groups using this approach, which will likely serve to model
other mono- or polygenetic cardiovascular disorders in the future. Test systems
based on cells derived from iPSC might prove beneficial to screen for novel
cardiovascular drugs or unwanted drug side effects and to individualize medical
therapy. The application of iPSC for cell therapy of cardiovascular disorders,
albeit promising, will only become feasible if the problem of biological safety
of these cells will be mastered. Drug attrition rates have increased in past years, resulting in growing costs
for the pharmaceutical industry and consumers. The reasons for this include the
lack of in vitro models that correlate with clinical results and poor
preclinical toxicity screening assays. The in vitro production of human cardiac
progenitor cells and cardiomyocytes from human pluripotent stem cells provides
an amenable source of cells for applications in drug discovery, disease
modeling, regenerative medicine, and cardiotoxicity screening. In addition, the
ability to derive human-induced pluripotent stem cells from somatic tissues,
combined with current high-throughput screening and pharmacogenomics, may help
realize the use of these cells to fulfill the potential of personalized
medicine. In this review, we discuss the use of pluripotent stem cell-derived
cardiomyocytes for drug discovery and cardiotoxicity screening, as well as
current hurdles that must be overcome for wider clinical applications of this
promising approach. Human induced pluripotent stem cell-derived endothelial cells (hiPSC-ECs) are
promising for treatment of vascular diseases. However, hiPSC-ECs purified based
on CD31 expression are comprised of arterial, venous, and lymphatic subtypes. It
is unclear whether hiPSC-ECs are heterogeneous in nature, and whether there may
be functional benefits of enriching for specific subtypes. Therefore, we sought
to characterize the hiPSC-ECs and enrich for each subtype, and demonstrate
whether such enrichment would have functional significance. The hiPSC-ECs were
generated from differentiation of hiPSCs using vascular endothelial growth
factor (VEGF)-A and bone morphogenetic protein-4. The hiPSC-ECs were purified
based on positive expression of CD31. Subsequently, we sought to enrich for each
subtype. Arterial hiPSC-ECs were induced using higher concentrations of VEGF-A
and 8-bromoadenosine-3':5'-cyclic monophosphate in the media, whereas lower
concentrations of VEGF-A favored venous subtype. VEGF-C and angiopoietin-1
promoted the expression of lymphatic phenotype. Upon FACS purification based on
CD31+ expression, the hiPSC-EC population was observed to display typical
endothelial surface markers and functions. However, the hiPSC-EC population was
heterogeneous in that they displayed arterial, venous, and to a lesser degree,
lymphatic lineage markers. Upon comparing vascular formation in matrigel plugs
in vivo, we observed that arterial enriched hiPSC-ECs formed a more extensive
capillary network in this model, by comparison to a heterogeneous population of
hiPSC-ECs. This study demonstrates that FACS purification of CD31+ hiPSC-ECs
produces a diverse population of ECs. Refining the differentiation methods can
enrich for subtype-specific hiPSC-ECs with functional benefits of enhancing
neovascularization. Cardiovascular progenitor cells (CVPCs) derived from human pluripotent stem
cells (hPSCs), including human embryonic stem cells (hESCs) and human induced
pluripotent stem cells (hiPSCs), hold great promise for the study of
cardiovascular development and cell-based therapy of heart diseases, but their
applications are challenged by the difficulties in their efficient generation
and stable maintece. This study aims to develop chemically defined systems
for robust generation and stable propagation of hPSC-derived CVPCs by modulating
the key early developmental pathways involved in human cardiovascular
specification and CVPC self-renewal. Herein we report that a combination of bone
morphogenetic protein 4 (BMP4), glycogen synthase kinase 3 (GSK3) inhibitor
CHIR99021 and ascorbic acid is sufficient to rapidly convert monolayer-cultured
hPSCs, including hESCs and hiPSCs, into homogeneous CVPCs in a chemically
defined medium under feeder- and serum-free culture conditions. These CVPCs
stably self-renewed under feeder- and serum-free conditions and expanded over
10(7)-fold when the differentiation-inducing signals from BMP, GSK3 and
Activin/Nodal pathways were simultaneously eliminated. Furthermore, these CVPCs
exhibited expected genome-wide molecular features of CVPCs, retained potentials
to generate major cardiovascular lineages including cardiomyocytes, smooth
muscle cells and endothelial cells in vitro, and were non-tumorigenic in vivo.
Altogether, the established systems reported here permit efficient generation
and stable maintece of hPSC-derived CVPCs, which represent a powerful tool to
study early embryonic cardiovascular development and provide a potentially safe
source of cells for myocardial regenerative medicine. Induced pluripotent stem cells (iPSCs) can be generated from adult somatic
tissues by the forced expression of a few defined transcription factors,
including Oct4, Sox2, Klf4, and c-Myc. iPSC technology holds tremendous promises
for therapeutic cardiovascular regeneration because of the cells' unlimited
capacity for proliferation and differentiation into all cell lineages. The iPSCs
can be generated from somatic cells of patients with a genetic basis for their
disease so as to understand the pathobiology of the disorder. This disease
modeling can be adapted to high-throughput screens to discover new therapeutic
molecules. Finally, the iPSC technology may enable personalized cell therapies,
while avoiding the ethical concerns surrounding human embryonic stem cells.
Intensive efforts are underway to develop reliable methods to guide stem cell
differentiation into cardiovascular lineages in the treatment of peripheral
artery disease and heart diseases. Studies of disease pathogenesis and drug
discovery using iPSC technology shall advance the discovery of novel treatments
for cardiovascular diseases. |
Which disease is included as an additional feature in the Goldberg-Shprintzen syndrome? | Shprintzen-Goldberg syndrome (SGS) is characterized by: craniosynostosis of the coronal, sagittal, or lambdoid sutures; dolichocephaly; distinctive craniofacial features; skeletal changes (dolichostenomelia, arachnodactyly, camptodactyly, pes planus, pectus excavatum or carinatum, scoliosis, joint hypermobility or contractures and C1/C2 spine malformation); neurologic abnormalities; intellectual disability; and brain anomalies (hydrocephalus, dilatation of the lateral ventricles, and Chiari 1 malformation). Cardiovascular anomalies may include mitral valve prolapse, mitral regurgitation/incompetence, aortic regurgitation and aortic root dilatation. Minimal subcutaneous fat, abdominal wall defects, myopia, and cryptorchidism in males, are also characteristic findings.Shprintzen-Goldberg syndrome (SGS) is characterized by craniosynostosis and marfanoid habitus. | We describe a brother and sister with Hirschsprung disease, hypotonia, and
ptosis. Their condition resembles that in 2 sibs reported by Goldberg and
Shprintzen. We conclude that the clinical characteristics in 8 reported cases
with similar clinical manifestations represent a distinct autosomal recessive
syndrome, Goldberg-Shprintzen syndrome. A 5-year-old girl with Hirschsprung disease, unusual facial appearance,
psychomotor retardation, epilepsy, and congenital heart disease is reported.
Patients with similar clinical features have been reported and they appear to
exhibit the recently identified Goldberg-Shprintzen syndrome. It is believed
that this girl also exhibits this new syndrome. Cranial computed tomography
demonstrated abnormal findings that may suggest defective neuronal migration
and/or dysgenesis of the brain. These findings were considered to cause
psychomotor retardation and epilepsy in this patient. Recent reports have described a distinct and recurrent pattern of systemic
malformation that associates craniosynostosis and neurodevelopmental
abnormalities with many clinical features of the Marfan syndrome (MFS), an
autosomal domit disorder of the extracellular microfibril caused by defects
in the gene encoding fibrillin-1, FBN1 (ref. 8). Additional common findings
include other craniofacial anomalies, hypotonia, obstructive apnea, foot
deformity, and congenital weakness of the abdominal wall. So far, only 11 cases
have been reported precluding the assignment of definitive diagnostic criteria.
While it remains unclear whether these cases represent a discrete clinical
entity with a single aetiology, they have been pragmatically grouped under the
rubric Marfanoid-craniosynostosis or Shprintzen-Goldberg syndrome (SGS). Because
of the significant clinical overlap between MFS and SGS, we proposed that they
may be caused by allelic mutations. We now report two SGS patients who harbour
mutations in FBN1. While it remains unclear whether these mutations are
sufficient for the clinical expression of the entire SGS phenotype, these data
suggest a role for fibrillin-1 in early craniofacial and central nervous system
development. Our recent observation that FBN1 transcript is expressed as early
as the 8-cell stage of human embryogenesis is consistent with this hypothesis. We report the case of a Japanese boy whose dysmorphic features were consistent
with those of Shprintzen-Goldberg syndrome. The radiological features were
characterized by late-onset craniosynostosis, arachnodactyly, undermodeling of
short tubular bones, mildly undermodeled and slightly bowed long bones, twisted
ribs and tall vertebral bodies with elongated neural arches. Apart from the
craniosynostosis, these skeletal changes resembled those of frontometaphyseal
dysplasia, a well-known craniotubular dysplasia. Shprintzen-Goldberg syndrome
also shares many clinical features with frontometaphyseal dysplasia. Annuloaortic ectasia due to Shprintzen-Goldberg syndrome (SGS) is reported. A
10-year-old boy was admitted to our hospital for evaluation of chest pain. On
admission, he was diagnosed as SGS on the basis of his various anomalies.
Two-dimensional echocardiography showed a bicuspid aortic valve and marked
annular dilatation, Doppler flow studies revealed severe aortic regurgitation,
and retrograde aortography showed severe aortic regurgitation with annular
dilatation. Successful aortic root replacement was performed; subsequent
histologic examination of the ascending aorta demonstrated cystic medial
necrosis. In conclusion, SGS is a generalized connective tissue dysplasia, with
clinical manifestations of cardiovascular lesions similar to those in Marfan
syndrome. Aortic root replacement was successfully performed; however,
recurrence of aortic aneurysms outside of the ascending aorta should be
carefully observed. Surgical treatment for cardiovascular disorders may be
necessary to save the life of patients with SGS. Shprintzen-Goldberg syndrome is one of a group of disorders characterized by
craniosynostosis and marfanoid habitus. Eleven cases were reported previously.
We present 4 new patients and review one of the patients of the original report
of Shprintzen and Goldberg [1982: J Craniofac Genet Dev Biol 2:65-74], 15 years
later. The clinical and radiologic findings on our patients are compared with
those of the previously reported patients and also with those of Furlong et al.
[1987: Am J Med Genet 26:599-604] and Lacombe and Battin [1993: Clin Dysmorphol
2: 220-224], who share many of the characteristics of Shprintzen-Goldberg
syndrome. Some of the clinical data are helpful in determining if the patients
of Furlong et al. [1987: Am J Med Genet 26:599-604] and Lacombe and Battin
[1993: Clin Dysmorphol 2: 220-224] have a separate syndrome or represent a
variant of Shprintzen-Goldberg syndrome. However, radiologic investigations
appear to be more specific, since an abnormality of the first and second
cervical vertebrae, hydrocephalus, dilatation of the lateral ventricles, and a
Chiari-I malformation of the brain were found only in the patients with
Shprintzen-Goldberg syndrome. The apparently diagnostic findings of the 15
patients with this syndrome may be helpful in differentiating between
Shprintzen-Goldberg syndrome and other syndromes with craniosynostosis and
marfanoid habitus. In 1981, Goldberg and Shprintzen described siblings with short-segment
Hirschsprung disease, cleft palate, microcephaly, mild mental retardation, short
stature and distinctive facial appearance. There have been several subsequent
reports which broaden the phenotype. This paper describes a further family,
reviews the literature and stresses the intra-familial variability. The Shprintzen-Goldberg syndrome is an extremely rare syndrome with a
characteristic face. This is one of a group of disorders characterized by
craniosynostosis and marfanoid features. The aim of this study was to present a
new sporadic case of the syndrome and describe in detail the findings at the
maxillofacial region. Neurocristopathies are a group of diverse disorders resulting from defective
growth, differentiation, and migration of the neural crest cells. Hirschsprung's
disease, namely aganglionic megacolon, is the consequence of defective migration
of neural crest cells on to the colonic submucosa and is therefore considered a
neurocristopathy. We report on four children in whom was diagnosed a
neurocristopathy, associating Hirschsprung's disease with a wide spectrum of
neurologic abnormalities. The patients included two children presenting the
phenotypic features of the Goldberg-Shprintzen syndrome: distinct dysmorphic
facial features, microcephaly, and mental retardation, along with agenesis of
the corpus callosum and cortical malformations associated with intractable
seizures in one child. The third newborn presented with the Haddad syndrome:
short-segment Hirschsprung's disease associated with the congenital central
hypoventilation syndrome requiring permanent artificial ventilation. In the
fourth child, absence of the corpus callosum was associated with mild dysmorphic
features, borderline cognitive abilities, and attention-deficit disorder.
Therefore, awareness of a possible neurocristopathy associated with neurologic
abnormalities should be taken into account in any patient newly diagnosed with
Hirschsprung's disease to detect the abnormalities early and promptly manage
them. A thorough neurologic examination and a developmental assessment,
including magnetic resoce imaging of the brain and electroencephalography,
should be performed for any child presenting with an aganglionic megacolon,
especially those presenting with seizures, developmental delay, or even
congenital hypoventilation. We identified, by homozygosity mapping, a novel locus on 10q21.3-q22.1 for
Goldberg-Shprintzen syndrome (GOSHS) in a consanguineous Moroccan family.
Phenotypic features of GOSHS in this inbred family included microcephaly and
mental retardation, which are both central nervous system defects, as well as
Hirschsprung disease, an enteric nervous system defect. Furthermore, since
bilateral generalized polymicogyria was diagnosed in all patients in this
family, this feature might also be considered a key feature of the syndrome. We
demonstrate that homozygous nonsense mutations in KIAA1279 at 10q22.1, encoding
a protein with two tetratrico peptide repeats, underlie this syndromic form of
Hirschsprung disease and generalized polymicrogyria, establishing the importance
of KIAA1279 in both enteric and central nervous system development. The Shprintzen-Goldberg syndrome (SGS) is a disorder of unknown cause comprising
craniosynostosis, a marfanoid habitus and skeletal, neurological,
cardiovascular, and connective-tissue anomalies. There are no pathognomonic
signs of SGS and diagnosis depends on recognition of a characteristic
combination of anomalies. Here, we describe 14 persons with SGS and compare
their clinical findings with those of 23 previously reported individuals,
including two families with more than one affected individual. Our analysis
suggests that there is a characteristic facial appearance, with more than two
thirds of all individuals having hypertelorism, down-slanting palpebral
fissures, a high-arched palate, micrognathia, and apparently low-set and
posteriorly rotated ears. Other commonly reported manifestations include
hypotonia in at least the neonatal period, developmental delay, and inguinal or
umbilical hernia. The degree of reported intellectual impairment ranges from
mild to severe. The most common skeletal manifestations in SGS were
arachnodactyly, pectus deformity, camptodactyly, scoliosis, and joint
hypermobility. None of the skeletal signs alone is specific for SGS. Our study
includes 14 mainly German individuals with SGS evaluated over a period of 10
years. Given that only 23 other persons with SGS have been reported to date
worldwide, we suggest that SGS may be more common than previously assumed. Shprintzen-Goldberg syndrome is a rare connective tissue disorder characterized
by marfanoid habitus and additional dysmorphic stigmata. Craniocervical
anomalies occur in fewer than 30% of cases. Serious vertebral instability can
also occur, albeit rarely. The authors report on the first patient treated with
surgical fusion at the craniocervical junction because of a C-1 dysplasia and
severe instability. The skeletal and cardiovascular anomalies that can pose
additional problems for surgical treatment and perioperative care are discussed
in detail. OBJECTIVE: Recognition of the phenotypic spectrum and prognosis of a genetic
disorder is critical to proper patient care. A 7-year-old boy with
Sphrintzen-Goldberg syndrome (SGS) was studied to investigate speech, language
and voice patterns associated with this syndrome.
METHODS: The child's language (expressive and receptive) and speech was
characterized with regard to overall intelligibility, articulation (phonetic and
phonological errors), voice (flexible videolaryngostroboscopy, quality, pitch
and loudness) and resoce (type of disorders).
RESULTS: Based on this detailed study the most striking communication
characteristics in this child with SGS appear to be a delayed speech and
language onset, an expressive and receptive language disorder, a moderately
impaired speech intelligbility, relatively good phonetic but poorer phonological
abilities, an oral hypotonia, a high-pitched soft voice and a slight
hypernasality.
CONCLUSIONS: The explanation for this communication disorder is not completely
straightforward. It is not clear either to what extent the present case can be
considered as typical for SGS. Only more data will allow to determine whether or
not SGS is associated with a typical syndrome specific pattern of communication
disorders. Not only detailed speech and language analyses of additional cases of
SGS are necessary, but also studies that compare the speech and language of
individuals with SGS with that of individuals with other genetic syndrome. Shprintzen-Goldberg syndrome (SGS) is a rare disorder characterized by a
Marfan-like habitus, mental retardation and craniosynostosis. Cardiac
abnormalities, such as aortic root dilation have also been noted as well as
several skeletal abnormalities. Its nosological status is unclear as it is hard
to delineate SGS from similar disorders, such as Furlong, Marfan type II,
Camurati-Engelmann and Loeys-Dietz syndromes. It has been suggested that these
conditions represent a phenotypical spectrum associated with aberrant TGF-beta
signalling. In support of this notion, we found a novel TGFBR2 missense mutation
in a patient with features of SGS. Goldberg-Shprintzen syndrome (GOSHS) is a rare clinical disorder characterized
by central and enteric nervous system defects. This syndrome is caused by
inactivating mutations in the Kinesin Binding Protein (KBP) gene, which encodes
a protein of which the precise function is largely unclear. We show that KBP
expression is up-regulated during neuronal development in mouse cortical
neurons. Moreover, KBP-depleted PC12 cells were defective in nerve growth
factor-induced differentiation and neurite outgrowth, suggesting that KBP is
required for cell differentiation and neurite development. To identify KBP
interacting proteins, we performed a yeast two-hybrid screen and found that KBP
binds almost exclusively to microtubule associated or related proteins,
specifically SCG10 and several kinesins. We confirmed these results by
validating KBP interaction with one of these proteins: SCG10, a microtubule
destabilizing protein. Zebrafish studies further demonstrated an epistatic
interaction between KBP and SCG10 in vivo. To investigate the possibility of
direct interaction between KBP and microtubules, we undertook co-localization
and in vitro binding assays, but found no evidence of direct binding. Thus, our
data indicate that KBP is involved in neuronal differentiation and that the
central and enteric nervous system defects seen in GOSHS are likely caused by
microtubule-related defects. BACKGROUND: Shprintzen-Goldberg syndrome (SGS) is characterized by
craniosynostosis and marfanoid habitus. The clinical findings of SGS include
neurological, cardiovascular, connective tissue, and skeletal abnormalities.
Among these skeletal findings, developmental scoliosis is recognized in half of
all patients with SGS. However, no earlier reports have described the surgical
treatment of scoliosis associated with SGS.
METHODS: Four patients (2 boys and 2 girls; mean age at the time of surgery,
7.3±4.4 y) with SGS who underwent surgical treatment for progressive scoliosis
were reviewed. The radiologic findings, operative findings, and perioperative
complications were evaluated.
RESULTS: The mean preoperative Cobb angle was 102.8±16.9 degrees. The curve
patterns were a double curve in 2 cases and a triple curve in 2 cases. Local
kyphosis at the thoracolumbar area was recognized in all the cases with a mean
kyphosis angle of 49±16 degrees. Growing rod procedures were performed in 2
patients, and posterior correction and fusion were performed in 2 patients. The
mean correction rate was 45% in the patients who underwent the growing rod
procedures at the time of growing rod placement and 51% in the patients who
underwent posterior correction and fusion. Dislodgement of the proximal anchors
occurred in 3 of the 4 patients. One patient developed pseudoarthrosis. Two
patients developed deep wound infections, and implant removal was necessary in 1
patient.
CONCLUSIONS: Surgical treatment for scoliosis in patients with SGS was
associated with a high incidence of perioperative and postoperative
complications including implant dislodgements and deep wound infections
attributable to poor bone quality and a thin body habitus, which are
characteristic clinical features of this syndrome. Careful preoperative surgical
planning and postoperative care are critical for the surgical treatment of
scoliosis associated with SGS, especially in infants requiring multiple
surgeries.
LEVEL OF EVIDENCE: Level IV. Elevated transforming growth factor (TGF)-β signaling has been implicated in the
pathogenesis of syndromic presentations of aortic aneurysm, including Marfan
syndrome (MFS) and Loeys-Dietz syndrome (LDS). However, the location and
character of many of the causal mutations in LDS intuitively imply diminished
TGF-β signaling. Taken together, these data have engendered controversy
regarding the specific role of TGF-β in disease pathogenesis.
Shprintzen-Goldberg syndrome (SGS) has considerable phenotypic overlap with MFS
and LDS, including aortic aneurysm. We identified causative variation in ten
individuals with SGS in the proto-oncogene SKI, a known repressor of TGF-β
activity. Cultured dermal fibroblasts from affected individuals showed enhanced
activation of TGF-β signaling cascades and higher expression of TGF-β-responsive
genes relative to control cells. Morpholino-induced silencing of SKI paralogs in
zebrafish recapitulated abnormalities seen in humans with SGS. These data
support the conclusions that increased TGF-β signaling is the mechanism
underlying SGS and that high signaling contributes to multiple syndromic
presentations of aortic aneurysm. |
Which protein is causing Netherton syndrome? | Netherton syndrome (NS) is a serious inherited skin disorder caused by mutations in the gene SPINK5 (serine protease inhibitor Kazal type 5) which encodes for a serine protease inhibitor LEKTI (lymphoepithelial Kazal type-related inhibitor) | Deficiency in the serine protease inhibitor LEKTI is the etiological origin of
Netherton syndrome, which causes detachment of the stratum corneum and chronic
inflammation. Here we show that the membrane protease matriptase initiates
Netherton syndrome in a LEKTI-deficient mouse model by premature activation of a
pro-kallikrein cascade. Auto-activation of pro-inflammatory
pro-kallikrein-related peptidases that are associated with stratum corneum
detachment was either low or undetectable, but they were efficiently activated
by matriptase. Ablation of matriptase from LEKTI-deficient mice dampened
inflammation, eliminated aberrant protease activity, prevented detachment of the
stratum corneum, and improved the barrier function of the epidermis. These
results uncover a pathogenic matriptase-pro-kallikrein pathway that could
operate in several human skin and inflammatory diseases. Lympho-epithelial Kazal-type-related inhibitor (LEKTI) is the defective protein
of the ichthyosiform condition Netherton syndrome (NS). Strongly expressed in
the most differentiated epidermal layers, LEKTI is a serine protease inhibitor
synthesized as three different high-molecular-weight precursors, which are
rapidly processed into shorter fragments and secreted extracellularly. LEKTI
polypeptides interact with several proteases to regulate skin barrier
homeostasis as well as inflammatory and/or immunoallergic responses. Here, by
combining antibody mapping, N-terminal sequencing, and site-specific
mutagenesis, we defined the amino-acid sequence of most of the LEKTI
polypeptides physiologically generated in human epidermis. We also identified
three processing intermediates not described so far. Hence, a proteolytic
cascade model for LEKTI activation is proposed. We then pinpointed the most
effective fragments against the desquamation-related kallikreins (KLKs) and we
proved that LEKTI is involved in stratum corneum shedding as some of its
polypeptides inhibit the KLK-mediated proteolysis of desmoglein-1. Finally, we
quantified the individual LEKTI fragments in the uppermost epidermis, showing
that the ratios between LEKTI polypeptides and active KLK5 are compatible with a
fine-tuned inhibition. These findings are relevant both to the understanding of
skin homeostasis regulation and to the design of novel therapeutic strategies
for NS. Gene-modified skin grafts, produced through gene transfer to human keratinocyte
stem cells, offer the possibility of therapeutic benefit for inherited skin
diseases. We have previously described efficient lentiviral vector-mediated gene
transfer to keratinocyte stem cells and the generation of human skin grafts for
the inherited skin disease, Netherton syndrome, which arises due to mutations in
serine protease inhibitor Kazal-type 5 (SPINK5). Vectors incorporating an
internal murine retroviral-derived promoter [spleen focus-forming virus (SFFV)]
in combination with a codon-optimized SPINK5 transgene supported high levels of
reconstitution and robust correction of skin architecture. Subsequent
longer-term experiments have uncovered uticipated silencing phenomena, with
loss of SPINK5 gene expression over time. The inadvertent introduction of CpG
sites during codon optimization appears to have rendered vectors susceptible to
silencing due to methylation across the promoter-transgene boundary.
Substitution of the methylation-susceptible SFFV promoter with a 572-bp minimal
human involucrin promoter (INVOp), which encodes very few CpG sites, prevented
repression of the SPINK5 transgene and resulted in durable and highly
compartment-specific reconstitution of lympho-epithelial Kazal-type-related
inhibitor (LEKTI) in human skin grafted onto immunodeficient mice. We conclude
that skin grafts modified with lentiviral vectors encoding INVOp offer a
suitable platform for therapeutic gene therapy in Netherton syndrome, and our
experience highlights uticipated effects of transgene codon optimization. Netherton syndrome (NS) is a rare autosomal recessive skin disease with severe
skin inflammation and scaling, a specific hair shaft defect and constant
allergic manifestations. NS is caused by loss-of-function mutations in SPINK5
(serine protease inhibitor of kazal type 5) encoding LEKTI-1 (lympho-epithelial
kazal type related inhibitor type 5) expressed in stratified epithelia. In vitro
and in vivo studies in murine models and in NS patients have cast light on the
pathogenesis of the disease and shown that LEKTI deficiency results in unopposed
kallikrein-related peptidase 5 (KLK5) and KLK7 activities and to the
overactivity of a new epidermal protease, elastase 2 (ELA2). Two main cascades
initiated by KLK5 activity have emerged. One results in desmoglein 1 degradation
and desmosome cleavage leading to stratum corneum detachment. KLK5 also
activates KLK7 and ELA2, which contribute to a defective skin barrier. This
facilitates allergen and microbe penetration and generates danger signals
leading to caspase 1 activation and the production of active interleukin-1β. In
parallel, KLK5 activates a specific cascade of allergy and inflammation by
activating protease-activated receptor-2 (PAR-2) receptors. PAR-2 activation
triggers the production of the major pro-Th2 cytokine TSLP (thymic stromal
lymphopoietin) and several inflammatory cytokines, including tumour necrosis
factor-α. Levels of thymus and activation-regulated chemokine (TARC) and
macrophage-derived chemokine (MDC) also contribute to allergy in a
PAR-2-independent manner. Patient investigations have confirmed these
abnormalities and revealed a wide spectrum of disease expression, sometimes
associated with residual LEKTI expression. These results have demonstrated that
the tight regulation of epidermal protease activity is essential for skin
homeostasis and identified new targets for therapeutic intervention. They also
provide a link with atopic dermatitis through deregulated protease activity, as
recently supported by functional studies of the E420K LEKTI variant. OBJECTIVES: Netherton's syndrome (NS) is a rare autosomal recessive condition,
first described in 1958, which involves a complex immunological dysfunction,
ichthyosiform dermatitis, and erythroderma, characteristic defects of the hair
shaft and atopy. Recurrent bacterial infection in the skin of patients with NS
is frequent.
METHODS: This paper represents the first case report of leprosy and concurrent
NS.
DISCUSSION: This case merits discussion among doctors in endemic and non-endemic
areas to evaluate the chronic use of systemic corticosteroids as a risk factor
for leprosy. The present patient came from an endemic area of leprosy and was
treated chronically with systemic corticosteroids for erythroderma. This
treatment, along with the immunodeficiency related to the syndrome and caused by
a genetic mutation in SPINK5, may be a facilitating factor for the infection. Netherton syndrome (NS, OMIM 256500) is a rare autosomal recessive disorder
manifesting with congenital ichthyosis, a specific hair shaft abnormality named
trichorrhexis invaginata, and atopic manifestations. Because of severe
complications frequently occurring in the neonatal period, NS prognosis can be
poor in infancy. NS is due to loss-of-function mutations in the SPINK5 gene and
to the consequent lack of expression of its encoded protein LEKTI in the skin
and all stratified epithelial tissues. Following the identification of the NS
causative gene and protein, specific diagnostic tools have been developed, thus
breaking up the challenge of distinguishing NS from other congenital ichthyoses
with overlapping features, and from severe, early-onset forms of atopic
dermatitis or psoriasis. Intensive efforts to extend the knowledge into the
pathomechanisms of NS have also been made. However, NS management is still
problematic due to the lack of specific treatment and unmet needs. This overview
summarizes the current state of the art in NS research with an emphasis on the
progress made toward disease-specific innovative therapy development. Netherton syndrome (NS) is a rare autosomal recessive disorder characterized by
ichthyosiform scaling, hair abnormalities, and variable atopic features.
Mutations in the serine protease inhibitor Kazal type 5 (SPINK5) gene leading to
lymphoepithelial Kazal-type-related inhibitor (LEKTI) deficiency cause NS.
Growth retardation is a classic feature of NS, but growth hormone (GH)
deficiency with subsequent response to GH therapy is not documented in the
literature. It is proposed that a lack of inhibition of proteases due to a
deficiency of LEKTI in the pituitary gland leads to the overprocessing of human
GH in NS. Herein we report three patients with NS who had growth retardation
associated with GH deficiency and responded well to GH therapy. Netherton syndrome (NS) is a serious inherited skin disorder caused by mutations
in the gene SPINK5 (serine protease inhibitor Kazal type 5) which encodes for a
serine protease inhibitor LEKTI (lymphoepithelial Kazal type-related inhibitor).
Patients with NS have defective keratinization, hair shaft defects, recurrent
infections, atopy and a predisposition to skin maligcies. Historically, one
in ten infants has died before their first birthday. Currently there are no
proven treatments to cure this condition. A SIN-lentiviral vector encoding the
codon optimized SPINK5 gene under the control of a 572bp element derived from
the human involucrin promoter (INVO) can confer compartment specific LEKTI
expression in NS keratinocytes with restoration of normal skin architecture.
Here we detail a study protocol for a phase I trial for feasibility and safety
evaluations of autologous epidermal sheets generated from ex-vivo gene corrected
keratinocyte stem cells, which will be grafted onto patients with mutation
proven NS. Netherton syndrome (NTS) is a rare genetic skin disease caused by mutations in
the serine protease inhibitor Kazal-type 5 gene, which encodes the
lympho-epithelial Kazal-type-related inhibitor. NTS patients have profoundly
impaired skin barrier function. As stratum corneum (SC) lipids have a crucial
role in the skin barrier function, we investigated the SC lipid composition and
organization in NTS patients. We studied the SC lipid composition by means of
mass spectrometry, and the lipid organization was examined by infrared
spectroscopy and X-ray diffraction. Decreased free fatty acid (FFA) chain length
and increased levels of monounsaturated FFAs were observed in the SC of NTS
patients compared with controls. Furthermore, the level of short-chain ceramides
(CERs) was enhanced in NTS patients and a strong reduction in long-chain CER
levels was seen in several patients. The changes in lipid composition modified
the lipid organization leading to an increased disordering of the lipids
compared with the controls. In addition, in a subgroup of patients the
organization of the lipid layers changed dramatically. The altered FFA and CER
profiles in NTS patients corresponded to changes in the expression of enzymes
involved in SC lipid processing. The observed changes in lipid composition,
lipid organization, and enzyme expression are likely to contribute to the
barrier dysfunction in NTS. |
Mutations in which gene and which protein are associated with Netherton syndrome? | NS is due to loss-of-function mutations in the SPINK5 gene and to the consequent lack of expression of its encoded protein LEKTI in the skin and all stratified epithelial tissues. | We describe here eleven different mutations in SPINK5, encoding the serine
protease inhibitor LEKTI, in 13 families with Netherton syndrome (NS,
MIM256500). Most of these mutations predict premature termination codons. These
results disclose a critical role of SPINK5 in epidermal barrier function and
immunity, and suggest a new pathway for high serum IgE levels and atopic
manifestations. Netherton syndrome is a severe autosomal recessive skin disorder characterized
by congenital erythroderma, a specific hair-shaft abnormality, and atopic
manifestations with high IgE levels. Recently, we identified SPINK5, which
encodes the serine protease inhibitor Kazal-type 5 protein (LEKTI), as the
defective gene in Netherton syndrome. Here we describe the intron-exon
organization of the gene and characterize the SPINK5 mutations in patients from
21 families of different geographic origin, using denaturing high performance
liquid chromatography and direct sequencing. We identified 18 mutations, of
which 13 were novel and seven (39%) were recurrent. The majority of the
mutations were clustered between exons 1-8 and exons 21-26. They comprised four
nonsense mutations (22%), eight frameshift insertions or deletions (44%), and
six splice-site defects (33%). All mutations predict the formation of premature
termination codons. Northern blot analysis showed variable reduction of SPINK5
mutant transcript levels, suggesting variable efficiency of nonsense-mediated
mRNA decay. Seven patients were homozygotes, eight were compound heterozygotes,
and five were heterozygotes with only one identifiable SPINK5 mutation. Five
mutations, one of which resulted in perinatal lethal disease in three families,
were associated with certain ethnic groups. We also describe 45 intragenic
polymorphisms in the patients studied. The clinical features of erythroderma,
trichorrhexis invaginata, and atopic manifestations were present in the majority
of affected individuals and ichthyosis linearis circumflexa was seen in 12 out
of 24 patients. Interfamilial and intrafamilial variation in disease severity
was observed, with no clear correlation between mutations and phenotype,
suggesting that the degree of severity may be affected by other factors. BACKGROUND: Several skin diseases and atopic disorders including Netherton
syndrome and atopic dermatitis have been associated with mutations and
deviations of expression of SPINK5, the gene encoding the human 15-domain serine
proteinase inhibitor LEKTI. The biochemical mechanisms underlying this
phenomenon have not yet been fully clarified.
OBJECTIVES: To identify target proteinases of LEKTI important for processes of
desquamation and inflammation of the skin which will enable the development of
specific drugs.
METHODS: The inhibitory activities of LEKTI domains 6 and 15 were tested on a
number of commercially available serine proteinases and also on the purified
kallikreins hK5 and hK7. In addition, recombit hK5 was used.
RESULTS: LEKTI domain 6 is a potent inhibitor of hK5 and hK7, whereas LEKTI
domain 15 exhibits inhibitory activity on plasmin. hK5 and hK7 in particular are
relevant to skin disorders.
CONCLUSIONS: The inhibition of hK5 and hK7 by LEKTI domain 6 indicates an
important regulatory role of LEKTI in processes of skin desquamation and
inflammation, which may explain the severe pathological symptoms associated with
abnormalities of SPINK5 and/or its expression. Thus, LEKTI represents a
potential drug for the treatment of these disorders. Netherton syndrome is a rare disorder inherited in an autosomal recessive
pattern consisting of ichthyosiform dermatosis, hair shaft abnormalities
(trichorrhexis invaginata), and an atopic diathesis. Patients with Netherton
syndrome have been found to have a mutation on chromosome 5q32 in a gene named
SPINK5 (serine protease inhibitor, Kazal type-5), which encodes an inhibitor of
serine proteases called LEKTI. We report a female patient with previously
undiagnosed Netherton syndrome who presented to participate in a clinical
research trial investigating the benefit of topical tacrolimus 0.03% ointment
[Protopic (Fujisawa Pharmaceutical Co. Ltd., Japan)] for the treatment of atopic
dermatitis. This patient was confirmed to have a gene mutation in SPINK5.
Current literature suggests a relative contraindication for use of topical
tacrolimus in patients with Netherton syndrome owing to concern for increased
systemic absorption of the drug. Our patient was not able to tolerate topical
tacrolimus owing to local irritation, and did not derive any benefit from
therapy. Though rare, when evaluating patients with a possible diagnosis of
atopic dermatitis, an index of suspicion for Netherton Syndrome must be
maintained. History and overall clinical findings, especially in regards to
examination of the hair, will aid in diagnosis. Netherton's syndrome is a rare autosomal recessive disorder caused by mutations
of the SPINK5 gene, which encodes the lymphoepithelial Kazal-type-related
inhibitor (LEKTI) protein. We observed microstructural changes and detected
LEKTI activity and SPINK5 gene mutation in three Chinese patients with
Netherton's syndrome. Decreased LEKTI activity was found in the skin of
patients. Lamellar bodies and foci of electron-dense material were detected in
the intercellular spaces of the stratum corneum. A novel homozygous splicing
mutation of 1430+2 T-->G was found in the SPINK5 gene in one proband. No
mutation was found in the other family. Netherton syndrome (NS) is a congenital ichthyosiform dermatosis caused by
serine protease inhibitor Kazal-type 5 (SPINK5) mutations. Tissue kallikreins
(KLKs) and lymphoepithelial Kazal-type-related inhibitor (LEKTI) (SPINK5
product) may contribute to the balance of serine proteases/inhibitors in skin
and influence skin barrier function and desquamation. SPINK5 mutations, causing
NS, lead to truncated LEKTI; each NS patient possesses LEKTI of a different
length, depending on the location of mutations. This study aims to elucidate
genotype/phenotype correlations in Japanese NS patients and to characterize the
functions of each LEKTI domain. Since we were unable to demonstrate truncated
proteins in tissue from patients with NS, we used recombit protein to test
the hypothesis that the length of LEKTI correlated with protease inhibitory
activity. Genotype/phenotype correlations were observed with cutaneous severity,
growth retardation, skin infection, stratum corneum (SC) protease activities,
and KLK levels in the SC. Predomit inhibition by LEKTI domains against
overall SC protease activities was trypsin-like (Phe-Ser-Arg-) activity by LEKTI
domains 6-12, plasmin- and trypsin-like (Pro-Phe-Arg-) activities by domains
12-15, chymotrypsin-like activity by all domains, and furin-like activity by
none. KLK levels were significantly elevated in the SC and serum of NS patients.
These data link LEKTI domain deficiency and clinical manifestations in NS
patients and pinpoints to possibilities for targeted therapeutic interventions. BACKGROUND: Loss-of-function mutations in the Kazal-type serine protease
inhibitor, LEKTI, encoded by the SPINK5 gene cause the rare autosomal recessive
skin disease Netherton syndrome (NS). G1258A polymorphism in SPINK5 may be
associated with atopic dermatitis, which shares several clinical features with
NS.
OBJECTIVES: To determine if the phenotype of NS can be caused by a single null
mutation in SPINK5 combined with the homozygous G1258A polymorphism.
METHODS: We screened mutations in the gene SPINK5 by direct DNA sequencing and
position cloning and examined the expressions of the SPINK5-encoded protein
LEKTI and other relevant proteins by immunostaining and immunoblot.
RESULTS: We describe here a patient who was clinically diagnosed with NS and
carried a single null mutation in SPINK5 combined with the homozygous G1258A
polymorphism. SPINK5 mRNA was present at normal levels and LEKTI was expressed
in the epidermis. Nonetheless, the putative downstream LEKTI substrates stratum
corneum trypsin-like enzyme (SCTE), desmoglein 1 and protein markers of
keratinocyte differentiation were expressed abnormally, similar to that seen in
NS if two null mutant alleles are present.
CONCLUSION: This finding indicates that haploinsufficiency of SPINK5 can cause
the NS phenotype in the presence of one null mutation with homozygous G1258A
polymorphisms in SPINK5, and this could impair the function of LEKTI and
therefore acts as a true mutation. Netherton syndrome (NS) is a debilitating congenital skin disorder caused by
mutations in the SPINK5 gene encoding the lymphoepithelial Kazal-type-related
inhibitor (LEKTI). It is characterized by defective keratinization, recurrent
infections, and hypernatraemic dehydration with a mortality rate of about 10% in
the first year of life. Currently, there are no curative treatments for NS. We
have developed a HIV-1 based, self-inactivating lentiviral vector to express
SPINK5 in keratinocytes as part of an ex-vivo gene therapy strategy for NS. High
transduction efficiency was achieved in NS keratinocytes and reconstitution of
LEKTI expression was confirmed in previously deficient cells. These genetically
corrected keratinocytes were further tested in an in vitro organotypic culture
(OTC) system and in vivo mouse/human skin engraftment model. Results showed
correction of epidermal architecture in both OTCs and regenerated skin grafts.
Importantly, the results from corrected skin grafts indicated that even where
detectable LEKTI expression was restored to a limited numbers of cells, a wider
bystander benefit occurred around these small populations. As LEKTI is a
secreted protein, the genetically modified graft may provide not only an
immediate local protective barrier, but also act as a source of secreted LEKTI
providing a generalized benefit following ex-vivo gene therapy. BACKGROUND: Netherton syndrome (NS, MIM 256500) is a potential live threatening
autosomal-recessive skin disorder clinically characterized by the trias of
congenital erythroderma, hair shaft anomalies and atopic diathesis. It is caused
by mutations in the gene SPINK5 resulting in a deficiency of its processed
protein named lympho-epithelial Kazal-type related inhibitor (LEKTI). LEKTI
controls the activity of several serine proteases in the skin that are involved
in terminal differentiation. Loss of LEKTI results in protease hyperactivity,
increased degradation of intercellular junctions, reduced stratum corneum
adhesion and impaired skin barrier function. Today NS can only be treated
symptomatically.
OBJECTIVE: Does gene transfer offer a therapeutic option for NS in the future?
METHODS: A recombit adeno-associated virus type 2 vector was constructed
containing the full length cDNA (rAAV2/C-SPINK5) of functional human LEKTI.
Infectious virus particles were used for transfection of
LEKTI-deficient-keratinocytes of NS patients in vitro.
RESULTS: Gene transfer of SPINK5 in NS-keratinocytes led to a five-fold increase
in mRNA expression of SPINK5 reaching almost 75% of normal value. The
functionality of the expressed LEKTI was proven in a hydrolytic activity assay
demonstrating that the activity of LEKTI after gene transfer increased closely
to the level seen in keratinocytes of healthy individuals.
CONCLUSION: The results provide first evidence that gene transfer of SPINK5
results in increased LEKTI activity in NS-keratinocytes, thus offering a
rational to further pursue such a gene therapy approach for NS. Netherton syndrome is a rare autosomal recessive disorder characterized by the
triad of ichthyosiform erythrodermia, typical hair dysplasia, and severe atopic
features. The broad range of variable expression of this disease is well
described and 20% of complications occur during the neonatal period such as
hypernatremic dehydration, electrolyte imbalances, recurrent or severe
infections, and failure to thrive. Mutation of the SPINK5 gene has been
identified as disease-causing in Netherton syndrome, but the pathophysiology
still remains unclear. Almost all SPINK5 mutations result in the absence of the
serine-protease inhibitor LEKTI protein in both keratinocytes and lymphocytes.
In this study, we report on a severe form of Netherton syndrome observed in
three patients within a large inbred Rom family. All of them died in the first
months of life despite early treatment. They were found to be homozygous for the
c.1431-12G>A SPINK5 gene mutation, which has not been associated with a lethal
form of the disease thus far. This family illustrates the extreme phenotype of
Netherton disease of neonatal onset. Molecular diagnosis allowed further genetic
counseling and prenatal testing during other pregcies. Netherton syndrome (NS, OMIM 256500) is a rare autosomal recessive disorder
manifesting with congenital ichthyosis, a specific hair shaft abnormality named
trichorrhexis invaginata, and atopic manifestations. Because of severe
complications frequently occurring in the neonatal period, NS prognosis can be
poor in infancy. NS is due to loss-of-function mutations in the SPINK5 gene and
to the consequent lack of expression of its encoded protein LEKTI in the skin
and all stratified epithelial tissues. Following the identification of the NS
causative gene and protein, specific diagnostic tools have been developed, thus
breaking up the challenge of distinguishing NS from other congenital ichthyoses
with overlapping features, and from severe, early-onset forms of atopic
dermatitis or psoriasis. Intensive efforts to extend the knowledge into the
pathomechanisms of NS have also been made. However, NS management is still
problematic due to the lack of specific treatment and unmet needs. This overview
summarizes the current state of the art in NS research with an emphasis on the
progress made toward disease-specific innovative therapy development. Netherton syndrome (NS) is a rare autosomal recessive disorder characterized by
ichthyosiform scaling, hair abnormalities, and variable atopic features.
Mutations in the serine protease inhibitor Kazal type 5 (SPINK5) gene leading to
lymphoepithelial Kazal-type-related inhibitor (LEKTI) deficiency cause NS.
Growth retardation is a classic feature of NS, but growth hormone (GH)
deficiency with subsequent response to GH therapy is not documented in the
literature. It is proposed that a lack of inhibition of proteases due to a
deficiency of LEKTI in the pituitary gland leads to the overprocessing of human
GH in NS. Herein we report three patients with NS who had growth retardation
associated with GH deficiency and responded well to GH therapy. |
Which disease of the central nervous system is characterized by the presence of Lewy bodies? | Parkinson s disease (PD) is one of the most common degenerative disorders of the central nervous system that produces motor and non-motor symptoms. The majority of cases are idiopathic and characterized by the presence of Lewy bodies containing fibrillar α-synuclein | A number of neurodegenerative diseases including Parkinson's disease, dementia
with Lewy bodies (DLB) and multiple system atrophy are characterized by the
formation and intraneuronal accumulation of fibrillar aggregates of
alpha-synuclein (alpha-syn) protein in affected brain regions. These and other
findings suggest that the accumulation of alpha-syn in the brain plays an
important role in the pathogenesis of these diseases. However, more recently it
has been reported that early amyloid aggregates or 'soluble oligomers' are the
pathogenic species that lead to neurodegeneration and neuronal cell death rather
than the later 'mature fibrils'. In this study, we investigated the presence of
alpha-syn oligomers in brain lysates prepared from frozen post-mortem brains of
normal, Alzheimer's disease and DLB patients. The brain extracts were subjected
to high speed centrifugation, to remove insoluble alpha-syn aggregates, followed
by specific detection of soluble oligomers in the supernatants by employing
FILA-1, an antibody that specifically binds to alpha-syn aggregates, but not to
alpha-syn monomers, or to tau or beta-amyloid aggregates. Using this novel
enzyme-linked immunosorbent assay (ELISA) method to quantify the amounts of
alpha-syn oligomers in the brain extracts, our data clearly show an increase in
the levels of soluble oligomers of alpha-syn in the DLB brains compared to those
with Alzheimer's disease and the controls (P < 0.0001). Our findings provide
strong evidence to support the contention that elevated soluble oligomers of
alpha-syn are involved in the pathogenesis of DLB. Furthermore, these findings
establish FILA-1 as a very sensitive tool for the detection of oligomeric forms
of alpha-syn in human brain lysates. Although Parkinson's disease with later dementia (PDD) and dementia with Lewy
bodies (DLB) are pathologically characterized by the presence of intraneuronal
Lewy inclusion bodies, amyloid deposition is also associated to varying degrees
with both these disorders. Fibrillar amyloid load can now be quantitated in vivo
with positron emission tomography (PET) using imaging biomarkers. Here the
reported findings of 11C-PIB PET studies concerning the amyloid load associated
with PD and its influence on dementia are reviewed. It is concluded that the
presence of amyloid acts to accelerate the dementia process in Lewy body
disorders, though has little influence on its nature. Anti-amyloid strategies
could be a relevant approach for slowing dementia in a number of DLB and PDD
cases. Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are characterized
by abnormal deposition of α-synuclein aggregates in many regions of the central
and peripheral nervous systems. Accumulating evidence suggests that the
α-synuclein pathology initiates in a few discrete regions and spreads to larger
areas in the nervous system. Recent pathological studies of PD patients have
raised the possibility that the enteric nervous system is one of the initial
sites of α-synuclein aggregation and propagation. Here, we evaluated the
induction and propagation of α-synuclein aggregates in the enteric nervous
system of the A53T α-synuclein transgenic mice after injection of human brain
tissue extracts into the gastric walls of the mice. Western analysis of the
brain extracts showed that the DLB extract contained detergent-stable
α-synuclein aggregates, but the normal brain extract did not. Injection of the
DLB extract resulted in an increased deposition of α-synuclein in the myenteric
neurons, in which α-synuclein formed punctate aggregates over time up to 4
months. In these mice, inflammatory responses were increased transiently at
early time points. None of these changes were observed in the A53T mice injected
with saline or the normal brain extract, nor were these found in the wild type
mice injected with the DLB extract. These results demonstrate that pathological
α-synuclein aggregates present in the brain of DLB patient can induce the
aggregation of endogenous α-synuclein in the myenteric neurons in A53T mice,
suggesting the transmission of synucleinopathy lesions in the enteric nervous
system. Protein aggregation within the central nervous system has been recognized as a
defining feature of neurodegenerative diseases since the early 20th century.
Since that time, there has been a growing list of neurodegenerative disorders,
including Parkinson disease, which are characterized by inclusions of specific
pathogenic proteins. This has led to the long-held dogma that these
characteristic protein inclusions, which are composed of large insoluble
fibrillar protein aggregates and visible by light microscopy, are responsible
for cell death in these diseases. However, the correlation between protein
inclusion formation and cytotoxicity is inconsistent, suggesting that another
form of the pathogenic proteins may be contributing to neurodegeneration. There
is emerging evidence implicating soluble oligomers, smaller protein aggregates
not detectable by conventional microscopy, as potential culprits in the
pathogenesis of neurodegenerative diseases. The protein α-synuclein is well
recognized to contribute to the pathogenesis of Parkinson disease and is the
major component of Lewy bodies and Lewy neurites. However, α-synuclein also
forms oligomeric species, with certain conformations being toxic to cells. The
mechanisms by which these α-synuclein oligomers cause cell death are being
actively investigated, as they may provide new strategies for diagnosis and
treatment of Parkinson disease and related disorders. Here we review the
possible role of α-synuclein oligomers in cell death in Parkinson disease and
discuss the potential clinical implications. Parkinson's disease, also known as paralysis agitans, is a progressive
degenerative disorder of the central nervous system, with onset usually between
the ages of 50 and 65 years, and is associated with loss of dopaminergic neurons
in the subsantia nigra and the presence of Lewy bodies. It is characterized by
the triad of resting tremor, muscular rigidity and bradykinesia.
Often-accompanying abnormalities include disorders of equilibrium, posture and
autonomic function, including micturition. Symptoms from the lower urinary tract
add a significant comorbidity factor in these patients. The incidence and
prevalence of lower urinary tract dysfunction rise with increasing progression
of the underlying neurological disease. They present a troublesome and difficult
to treat health issue with a profound impact on the patient's quality of life.
Storage symptoms seem to predominate. In the long term, renal function might be
compromised, mainly as a result of elevated intravesical pressure. Various
conservative, minimally-invasive and surgical treatment options are available to
prevent harmful sequelae, and to improve the quality of life of these patients.
We present an overview of current and prospective treatment strategies. Parkinson's disease is characterized by neuronal death in the substantia nigra
and the presence of intracellular inclusions of α-synuclein in the Lewy bodies.
Several lines of data support a role for iron in Parkinson's disease: iron is
present in Lewy bodies, iron accumulates in the dopaminergic neurons in the
substantia nigra, and Parkinson's disease is correlated with polymorphisms of
several genes implicated in iron metabolism. Furthermore, iron can compromise
the solubility of α-synuclein through direct interaction and can induce
neurotoxicity in vitro. Here, we investigate the possible neuroprotective effect
of the iron chelator deferoxamine in vivo to elucidate whether iron chelation
can provide meaningful therapy for Parkinson's disease. Hence, we used a
Parkinson's disease animal model based on unilateral injection of a recombit
adeno-associated viral vector encoding α-synuclein in the rat midbrain. Rats
were treated with a novel deferoxamine delivery approach: 6 mg of the compound
was administered intranasally three times a week for 3 or 7 weeks. The behavior
of the animals and histopathological changes in the brain were analyzed. Our
data show that although intranasal administration of deferoxamine in rats did
not protect them from dopaminergic cell death, it did decrease the number of the
pathological α-synuclein formations at the terminal level. In addition, this
treatment resulted in changes in the immune response and an overall partial
improvement in motor behavior. Taken together, our data show that in vivo iron
chelation can modulate α-synuclein-induced pathology in the central nervous
system. Our data suggest that chronic administration of intranasal deferoxamine
may be a valid approach to limiting the mishandling of α-synuclein in the
central nervous system observed in Parkinson's disease and slowing disease
progression. It is well known that autonomic failure is severer in patients with dementia
with Lewy bodies (DLB) compared with patients with Parkinson's disease (PD).
According to the Braak's hypothesis, Lewy bodies first appear in the olfactory
bulb or peripheral autonomic nervous system. Lewy bodies in the peripheral
autonomic nervous system ascend to dorsal motor nuclei of vagus nerve, while
those in the olfactory bulb expand to the limbic system. Lewy bodies later
attain the substantia nigra. However, it seems that Braak staging can not
explain difference in severity of autonomic failure between DLB and PD. As a
possibility, in DLB patients with significant autonomic failure, Lewy bodies may
have been localized to the peripheral autonomic nervous system in a long time
before onset of dementia or parkinsonism, and propagation of Lewy bodies into
the central nervous system may be initiated by apparition of certain promotion
factor, such as ageing and amyloid-β. Parkinson's disease (PD) and related Lewy body diseases are characterized by
deposition of α-synuclein aggregates in both the central nervous system and
peripheral nervous system. Synucleinopathy lesions spread to larger brain areas
as the disease progresses, and prion-like cell-to-cell transmission of
aggregated α-synuclein is thought to be the underlying mechanism for this
pathological spreading. LRRK2 is another protein linked to the pathogenesis of
PD, and its presence in Lewy bodies has attracted much attention as to whether
LRRK2 and α-synuclein interplay during the pathogenesis of PD. However, the
relationship between these two crucial proteins still remains unclear. In this
review article, we will discuss the current state of knowledge in terms of how
these proteins cause the disease and provide the hypothetical mechanisms by
which LRRK2 might modify the generation and progression of synucleinopathy. Parkinson's disease (PD) is the second most common neurodegenerative disorder
that is characterized by two major neuropathological hallmarks: the degeneration
of dopaminergic neurons in the substantia nigra (SN) and the presence of Lewy
bodies in the surviving SN neurons, as well as other regions of the central and
peripheral nervous system. Animal models have been invaluable tools for
investigating the underlying mechanisms of the pathogenesis of PD and testing
new potential symptomatic, neuroprotective and neurorestorative therapies.
However, the usefulness of these models is dependent on how precisely they
replicate the features of clinical PD with some studies now employing combined
gene-environment models to replicate more of the affected pathways. The rotenone
model of PD has become of great interest following the seminal paper by the
Greenamyre group in 2000 (Betarbet et al., 2000). This paper reported for the
first time that systemic rotenone was able to reproduce the two pathological
hallmarks of PD as well as certain parkinsonian motor deficits. Since 2000, many
research groups have actively used the rotenone model worldwide. This paper will
review rotenone models, focusing upon their ability to reproduce the two
pathological hallmarks of PD, motor deficits, extranigral pathology and
non-motor symptoms. We will also summarize the recent advances in
neuroprotective therapies, focusing on those that investigated non-motor
symptoms and review rotenone models used in combination with PD genetic models
to investigate gene-environment interactions. |
Which deiodinase is known to be present in liver? | High D1 and D3 activities are present in fetal human liver, and high D1 and mostly absent D3 activities are present in adult human liver. | In systemic nonthyroidal illness (NTI), peripheral production of T3 from T4 is
decreased, resulting in a decreased serum T3 concentration. We investigated
whether factors in serum of NTI patients may play a role in this energy-saving
adaptation mechanism. Metabolism of T4 and T3 by rat hepatocytes in primary
culture was measured in the presence of 10% serum of normal subjects or of
patients with NTI and related to the severity of disease. Patients with NTI were
grouped according to serum thyroid hormone abnormalities: group I, serum rT3,
T3, and T4 normal; group III, rT3 elevated, T3 decreased, T4 normal; group IV,
rT3 elevated, T3 and T4 decreased. Compared with metabolism in the presence of
normal serum, metabolism of T4 and to a lesser extent of T3 was progressively
decreased in the presence of serum of patients of groups I-IV. A decreased net
deiodination of T4 and T3 (corrected for differences in free hormone
concentration) without an increase in conjugated T4 and T3 (corrected for
differences in free hormone concentration) was observed, similar to results in
experiments with compounds inhibiting transport into the cells and not the
metabolic processes (5' deiodination) per se. Deiodination of T4 in vitro was
correlated with serum T3 concentration of the patient (r = 0.69). Serum of
patients with NTI influences thyroid hormone handling by hepatocytes comparable
to the effect of transport inhibitors and not to that of the 5'-deiodinase
inhibitor propylthiouracil, suggesting that decreased thyroid hormone transport
over the cell membrane may play a role in lowered T3 production in NTI. The uptake and metabolism of T3 and rT3 was studied in human liver-derived HepG2
cells. The results showed a saturable, time-dependent, and ouabain-sensitive
increase in nuclear bound T3. The effects of ouabain (0.5 mmol/L) and unlabeled
T3 (10 nmol/L and 10 mumol/L) were much more pronounced at the nuclear level,
suggesting the presence of a nonspecific component in total cellular binding.
Nuclear binding of rT3 remained below the detection limit in all experiments.
Comparison of rT3 metabolism in HepG2 cells and primary cultures of rat
hepatocytes showed an approximately 10-fold lower iodide production in HepG2
cells. Iodide production was decreased in the presence of ouabain and almost
absent in the presence of propylthiouracil (100 mumol/L). Our data confirmed the
presence of a carrier-mediated uptake system for both T3 and rT3. Metabolism
data indicated functional type I deiodinase activity in HepG2 cells, the
presence of glucuronidating enzymes, and the absence of thyroid hormone
sulfotransferase activity. Based on these data, we propose that HepG2 cells
provide an appropriate model for thyroid hormone handling by human liver. In
addition, we suggest that in human liver sulfation of thyroid hormone, and
therefore deiodination of T3 is of only minor importance. In embryonic chicken liver (ECL) two types of iodothyronine deiodinases are
expressed: D1 and D3. D1 catalyzes the activation as well as the inactivation of
thyroid hormone by outer and inner ring deiodination, respectively. D3 only
catalyzes inner ring deiodination. D1 and D3 have been cloned from mammals and
amphibians and shown to contain a selenocysteine (Sec) residue. We characterized
chicken D1 and D3 complementary DNAs (cDNAs) and studied the expression of
hepatic D1 and D3 messenger RNAs (mRNAs) during embryonic development.
Oligonucleotides based on two amino acid sequences strongly conserved in the
different deiodinases (NFGSCTSecP and YIEEAH) were used for reverse
transcription-PCR of poly(A+) RNA isolated from embryonic day 17 (E17) chicken
liver, resulting in the amplification of two 117-bp DNA fragments. Screening of
an E17 chicken liver cDNA library with these probes led to the isolation of two
cDNA clones, ECL1711 and ECL1715. The ECL1711 clone was 1360 bp long and lacked
a translation start site. Sequence alignment showed that it shared highest
sequence identity with D1s from other vertebrates and that the coding sequence
probably lacked the first five nucleotides. An ATG start codon was engineered by
site-directed mutagenesis, generating a mutant (ECL1711M) with four additional
codons (coding for MGTR). The open reading frame of ECL1711M coded for a
249-amino acid protein showing 58-62% identity with mammalian D1s. An in-frame
TGA codon was located at position 127, which is translated as Sec in the
presence ofa Sec insertion sequence (SECIS) identified in the 3'-untranslated
region. Enzyme activity expressed in COS-1 cells by transfection with ECL1711M
showed the same catalytic, substrate, and inhibitor specificities as native
chicken D1. The ECL1715 clone was 1366 bp long and also lacked a translation
start site. Sequence alignment showed that it was most homologous with D3 from
other species and that the coding sequence lacked approximately the first 46
nucleotides. The deduced amino acid sequence showed 62-72% identity with the D3
sequences from other species, including a putative Sec residue at a
corresponding position. The 3'-untranslated region of ECL1715 also contained a
SECIS element. These results indicate that ECL1711 and ECL1715 are
near-full-length cDNA clones for chicken D1 and D3 selenoproteins, respectively.
The ontogeny of D1 and D3 expression in chicken liver was studied between E14
and 1 day after hatching (C1). D1 activity showed a gradual increase from E14
until C1, whereas D1 mRNA level remained relatively constant. D3 activity and
mRNA level were highly significantly correlated, showing an increase from E14 to
E17 and a strong decrease thereafter. These results suggest that the regulation
of chicken hepatic D3 expression during embryonic development occurs
predomitly at the pretranslational level. The role of the deiodinases D1, D2, and D3 in the tissue-specific and
time-dependent regulation of thyroid hormone bioactivity during fetal
development has been investigated in animals but little is known about the
ontogeny of these enzymes in humans. We analyzed D1, D2, and D3 activities in
liver microsomes from 10 fetuses of 15-20 weeks gestation and from 8 apparently
healthy adult tissue transplant donors, and in liver homogenates from 2 fetuses
(20 weeks gestation), 5 preterm infants (27-32 weeks gestation), and 13 term
infants who survived up to 39 weeks postnatally. D1 activity was determined
using 1 microM [3',5'-125I]rT3 as substrate and 10 mM dithiothreitol (DTT) as
cofactor, D2 activity using 1 nM [3',5'-125I]T4 and 25 mM DTT in the presence of
1 mM 6-propyl-2-thiouracil (to block D1 activity) and 1 microM T3 (to block D3
activity), and D3 activity using 10 nM [3,5-125I]T3 and 50 mM DTT, by
quantitation of the release of 125I. The assays were validated by high
performance liquid chromatography of the products, and kinetic analysis
[Michaelis-Menten constant (Km) of rT3 for D1: 0.5 microM; Km of T3 for D3: 2
nM]. In liver homogenates, D1 activity was not correlated with age, whereas D3
activity showed a strong negative correlation with age (r -0.84), with high D3
activities in preterm infants and (except in 1 infant of 35 weeks) absent D3
activity in full-term infants. In microsomes, D1 activities amounted to 4.3-60
pmol/min/mg protein in fetal livers and to 170-313 pmol/min/mg protein in adult
livers, whereas microsomal D3 activities were 0.15-1.45 pmol/min/mg protein in
fetuses and <0.1 pmol/min/mg protein in all but one adult. In the latter sample,
D3 activity amounted to 0.36 pmol/min/mg protein. D2 activity was negligible in
both fetal and adult livers. These findings indicate high D1 and D3 activities
in fetal human liver, and high D1 and mostly absent D3 activities in adult human
liver. Therefore, the low serum T3 levels in the human fetus appear to be caused
by high hepatic (and placental) D3 activity rather than caused by low hepatic D1
activity. The occasional expression of D3 in adult human liver is intriguing and
deserves further investigation. |
Which proteins participate in the formation of the Notch transcriptional activation complex? | The Notch intracellular domain (NICD) forms a transcriptional activation complex with the DNA-binding factor CSL and a transcriptional co-activator of the Mastermind family (MAML). ICN binds to a highly conserved DNA-binding transcription factor called CSL (also known as RBP-Jkappa, CBF1, Suppressor of Hairless, and Lag-1) and recruits Mastermind-like transcriptional co-activators to form a transcriptional activation complex. | Mastermind (Mam) is a component of Notch pathway signaling. In combination with
the intracellular domain of Notch and Suppressor of Hairless, Mam forms a
transcriptional activation complex. We have initiated a genetic approach to
identify other loci involved in Mam function. The screen utilizes engineered
mutations in Mam that derive from GAL4-UAS-directed expression of domit
negative constructs. When driven at the wing margin, truncated versions of Mam
phenocopy Notch pathway mutations. Correlated with these phenotypes is
depression of Notch pathway target expression. Strains expressing truncated
versions of Mam were tested for genetic interactions with a large collection of
chromosomal deficiencies. Genomic segments that enhanced and suppressed the
domit wing phenotype were identified. These regions may contain
uncharacterized loci involved in Notch pathway function. In the developing central nervous system (CNS), Notch signaling preserves
progenitor pools and inhibits neurogenesis and oligodendroglial differentiation.
It has recently been postulated that Notch instructively drives astrocyte
differentiation. Whether the role of Notch signaling in promoting astroglial
differentiation is permissive or instructive has been debated. We report here
that the astrogliogenic role of Notch is in part mediated by direct binding of
the Notch intracellular domain to the CSL DNA binding protein, forming a
transcriptional activation complex onto the astrocyte marker gene, glial
fibrillary acidic protein (GFAP). In addition, we found that, in CSL-/- neural
stem cell cultures, astrocyte differentiation was delayed but continued at a
normal rate once initiated, suggesting that CSL is involved in regulating the
onset of astrogliogenesis. Importantly, although the classical CSL-dependent
Notch signaling pathway is intact and able to activate the Notch canonical
target promoter during the neurogenic phase, it is unable to activate the GFAP
promoter during neurogenesis. Therefore, the effect of Notch signaling on target
genes is influenced by cellular context in regulation of neurogenesis and
gliogenesis. Ligand binding by Notch receptors triggers a series of proteolytic cleavages
that liberate the intracellular portion of Notch (ICN) from the cell membrane,
permitting it to translocate to the nucleus. Nuclear ICN binds to a highly
conserved DNA-binding transcription factor called CSL (also known as RBP-Jkappa,
CBF1, Suppressor of Hairless, and Lag-1) and recruits Mastermind-like
transcriptional co-activators to form a transcriptional activation complex.
Using bioinformatics tools, we identified a Rel homology region (RHR) within CSL
that was used as a guide to determine the minimal protein requirements for
ternary complex formation. The RHR of CSL contains both the N- and C-terminal
beta-sheet domains (RHR-n and RHR-c) of typical Rel transcription factors, as
judged by circular dichroism spectra. Binding of monomeric CSL to DNA requires
the entire RHR of CSL and an additional 125-residue N-terminal sequence, whereas
binding to ICN requires only the RHR-n domain. Although the RAM (RBP-Jkappa
(recombination-signal-sequence-binding protein for Jkappa genes)-associated
molecule) domain of ICN is flexible and relatively unstructured as an isolated
polypeptide in solution, it associates stably with CSL on DNA. Recruitment of
Mastermind-like 1 (MAML1) to CSL.ICN complexes on DNA requires inclusion of the
ankyrin repeat domain of ICN, and N- and C-terminal sequences of CSL extending
beyond the DNA-binding region. The requirement for cooperative assembly of the
MAML1.ICN.CSL.DNA complex suggests that a primary function of ICN is to render
CSL competent for MAML loading. On the basis of our results, we present a
working structural model for the organization of the MAML1.ICN.CSL.DNA complex. Notch receptors transduce essential developmental signals between neighboring
cells by forming a complex that leads to transcription of target genes upon
activation. We report here the crystal structure of a Notch transcriptional
activation complex containing the ankyrin domain of human Notch1 (ANK), the
transcription factor CSL on cognate DNA, and a polypeptide from the coactivator
Mastermind-like-1 (MAML-1). Together, CSL and ANK create a groove to bind the
MAML-1 polypeptide as a kinked, 70 A helix. The composite binding surface likely
restricts the recruitment of MAML proteins to promoters on which Notch:CSL
complexes have been preassembled, ensuring tight transcriptional control of
Notch target genes. The Notch pathway is a short-range signaling mechanism between neighboring cells
that results in changes in gene expression. Extracellular interactions between
Notch receptors and ligands trigger proteolytic cleavage of the receptor Notch.
Following cleavage, the freed intracellular domain of Notch (NotchIC) moves from
the cytoplasm to the nucleus, engaging the DNA-binding transcription factor
CBF-1, Su(H), Lag-1 (CSL)--the nuclear effector of the pathway. NotchIC,
together with the transcriptional coactivator Mastermind, form a ternary complex
with CSL that activates transcription from genes that are responsive to Notch
signaling. Illuminating the molecular details that underlie formation of the
transcriptionally active CSL-NotchIC-Mastermind ternary complex is key for
understanding how genes are turned on in response to a Notch signal. Recently,
several studies using biophysical and computational methods have scrutinized how
the CSL-NotchIC-Mastermind ternary complex forms and the role individual domains
play in this process. These detailed analyses have provided a wealth of
molecular insights into the assembly of a Notch pathway active transcription
complex but have also raised several intriguing, yet confounding questions. This
review will focus on the findings of these recent biophysical studies and
provide speculative models that address these uswered questions. The Notch signalling pathway has a crucial function in determining cell fates in
multiple tissues within metazoan organisms. On binding to ligands, the Notch
receptor is cleaved proteolytically and releases its intracellular domain
(NotchICD). The NotchICD enters the nucleus and acts cooperatively with other
factors to stimulate the transcription of target genes. High levels of
Notch-mediated transcriptional activation require the formation of a ternary
complex consisting of NotchICD, CSL (CBF-1, suppressor of hairless, LAG-1) and a
Mastermind family member. However, it is still not clear how the formation of
the ternary complex is regulated. Here we show that Nemo-like kinase (NLK)
negatively regulates Notch-dependent transcriptional activation by decreasing
the formation of this ternary complex. Using a biochemical screen, we identified
Notch as a new substrate of NLK. NLK-phosphorylated Notch1ICD is impaired in its
ability to form a transcriptionally active ternary complex. Furthermore,
knockdown of NLK leads to hyperactivation of Notch signalling and consequently
decreases neurogenesis in zebrafish. Our results both define a new function for
NLK and reveal a previously unidentified mode of regulation in the Notch
signalling pathway. Ligand-induced proteolysis of Notch produces an intracellular effector domain
that transduces essential signals by regulating the transcription of target
genes. This function relies on the formation of transcriptional activation
complexes that include intracellular Notch, a Mastermind co-activator and the
transcription factor CSL bound to cognate DNA. These complexes form higher-order
assemblies on paired, head-to-head CSL recognition sites. Here we report the
X-ray structure of a dimeric human Notch1 transcription complex loaded on the
paired site from the human HES1 promoter. The small interface between the Notch
ankyrin domains could accommodate DNA bending and untwisting to allow a range of
spacer lengths between the two sites. Cooperative dimerization occurred on the
human and mouse Hes5 promoters at a sequence that diverged from the CSL-binding
consensus at one of the sites. These studies reveal how promoter organizational
features control cooperativity and, thus, the responsiveness of different
promoters to Notch signaling. BACKGROUND: Canonical Notch signaling is initiated when ligand binding induces
proteolytic release of the intracellular part of Notch (ICN) from the cell
membrane. ICN then travels into the nucleus where it drives the assembly of a
transcriptional activation complex containing the DNA-binding transcription
factor CSL, ICN, and a specialized co-activator of the Mastermind family. A
consensus DNA binding site motif for the CSL protein was previously defined
using selection-based methods, but whether subsequent association of Notch and
Mastermind-like proteins affects the DNA binding preferences of CSL has not
previously been examined.
PRINCIPAL FINDINGS: Here, we utilized protein-binding microarrays (PBMs) to
compare the binding site preferences of isolated CSL with the preferred binding
sites of CSL when bound to the CSL-binding domains of all four different human
Notch receptors. Measurements were taken both in the absence and in the presence
of Mastermind-like-1 (MAML1). Our data show no detectable difference in the DNA
binding site preferences of CSL before and after loading of Notch and MAML1
proteins.
CONCLUSIONS/SIGNIFICANCE: These findings support the conclusion that accrual of
Notch and MAML1 promote transcriptional activation without dramatically altering
the preferred sites of DNA binding, and illustrate the potential of PBMs to
analyze the binding site preferences of multiprotein-DNA complexes. Notch transmembrane receptors direct essential cellular processes, such as
proliferation and differentiation, through direct cell-to-cell interactions.
Inappropriate release of the intracellular domain of Notch (N(ICD)) from the
plasma membrane results in the accumulation of deregulated nuclear N(ICD) that
has been linked to human cancers, notably T-cell acute lymphoblastic leukemia
(T-ALL). Nuclear N(ICD) forms a transcriptional activation complex by
interacting with the coactivator protein Mastermind-like 1 and the DNA binding
protein CSL (for CBF-1/Suppressor of Hairless/Lag-1) to regulate target gene
expression. Although it is well understood that N(ICD) forms a transcriptional
activation complex, little is known about how the complex is assembled. In this
study, we demonstrate that N(ICD) multimerizes and that these multimers function
as precursors for the stepwise assembly of the Notch activation complex.
Importantly, we demonstrate that the assembly is mediated by N(ICD) multimers
interacting with Skip and Mastermind. These interactions form a preactivation
complex that is then resolved by CSL to form the Notch transcriptional
activation complex on DNA. The Notch intracellular domain (NICD) forms a transcriptional activation complex
with the DNA-binding factor CSL and a transcriptional co-activator of the
Mastermind family (MAML). The "RAM" region of NICD recruits Notch to CSL,
facilitating the binding of MAML at the interface between the ankyrin (ANK)
repeat domain of NICD and CSL. Here, we report the X-ray structure of a human
MAML1/RAM/ANK/CSL/DNA complex, and probe changes in component dynamics upon
stepwise assembly of a MAML1/NICD/CSL complex using HX-MS. Association of CSL
with NICD exerts remarkably little effect on the exchange kinetics of the ANK
domain, whereas MAML1 binding greatly retards the exchange kinetics of ANK
repeats 2-3. These exchange patterns identify critical features contributing to
the cooperative assembly of Notch transcription complexes (NTCs), highlight the
importance of MAML recruitment in rigidifying the ANK domain and stabilizing its
interface with CSL, and rationalize the requirement for MAML1 in driving
cooperative dimerization of NTCs on paired-site DNA. |
How is the sequence variability defined in antibodies? | The variability at each position of the polypeptide chain is defined as:
Variability = number of different amino acids at a given position / frequency of the most common amino acid at given position. | Five murine epitopes were defined and mapped within IgA1 protease produced by
Neisseria meningitidis. Epitopes 1 and 2 were present in IgA1 protease from all
strains, and from Neisseria gonorrhoeae. Epitopes 3 through to 5 varied between
subgroups of serogroup A meningococci, but have remained constant over decades
within the subgroups, except for epitope 4, which changed between 1983 and 1987
during the spread of subgroup III meningococci from Asia to Africa. Binding of
monoclonal antibodies to epitopes 1, 4 and 5 neutralized enzymatic function.
Human sera containing antibodies to IgA1 protease as a result of natural
infection inhibited binding of monoclonal antibodies to epitope 4 but not to the
other epitopes. A glutathione-dependent formaldehyde dehydrogenase (class III alcohol
dehydrogenase) has been characterized from Arabidopsis thaliana. This plant
enzyme exhibits kinetic and molecular properties in common with the class III
forms from mammals, with a K(m) for S-hydroxymethylglutathione of 1.4 microM, an
anodic electrophoretic mobility (pI: 5.3-5.6) and a cross-reaction with
anti-(rat class III alcohol dehydrogenase) antibodies. The enzyme structure,
deduced from the cDNA sequence, fits into the complex system of alcohol
dehydrogenases and shows that all life forms share the class III protein type.
The corresponding mRNA is 1.4 kb and present in all plant organs; a single copy
of the gene is found in the genome. The class III structural variability is
different from that of the ethanol-active enzyme types in both vertebrates
(class I) and plants (class P), although class P conserves more of the class III
properties than class I does. Also the enzymatic properties differ between the
two ethanol-active classes. Active-site variability and exchanges at essential
residues (Leu/Gly57, Asp/Arg115) may explain the distinct kinetics. These
patterns are consistent with two different metabolic roles for the
ethanol-active enzymes, a more constant function, reduction of acetaldehyde
during hypoxia, for class P, and a more variable function, the detoxication of
alcohols and participation in metabolic conversions, for class I. A sequence
motif, Pro-Xaa-Ile/Val-Xaa-Gly-His-Glu-Xaa-Xaa-Gly, common to all medium-chain
alcohol dehydrogenases is defined. More than 20.8 million people are infected with HIV in sub-Saharan Africa, with
South Africa having one of the fastest growing HIV-1 epidemics, where an
estimated 2.4 million people were infected. Thirty-two sera from 25 patients
were tested for their ability to neutralize HTLV-IIIB (IIIB) and four primary
isolates representing subtypes B, C, D, and a recombit gag C/env B type. A
CEM-SS cell line-based assay was used and the neutralizing titer was defined as
the reciprocal of the highest dilution giving a 50% reduction in p24 antigen
production. All isolates were neutralized better by subtype-specific sera,
except for the C4714 strain, which was neutralized by both subtype B and C sera.
C4714 was neutralized by 18/25 (72%) sera, IIIB by 19/32 (59%) sera, D482 by
7/31(23%) sera, B3245 by 6/29 (21%) sera, and the recombit B/C1491 isolate by
4/25 (16%) sera. Five sera were unable to neutralize any of the isolates. The V3
region of the isolates used in the neutralization assay was amplified by PCR,
directly sequenced, and analyzed to reveal variability between the consensus
HIV-1 sequences and the isolates. HIV-1 strain C4714 was neutralized more
effectively with the sera tested than the IIIIB laboratory strain. Variability
in the amino acid sequence of the V3 region, which can alter the conformation of
the V3 loop secondary structure, can influence the neutralization of a
particular viral isolate. Vaccine formulations should be broadened to include
multiple subtypes, especially C subtypes, which is rapidly spreading worldwide. The rickettsial pathogen Anaplasma marginale expresses a variable immunodomit
outer membrane protein, major surface protein 2 (MSP2), involved in antigenic
variation and long-term persistence of the organism in carrier animals. MSP2
contains a central hypervariable region of about 100 amino acids that encodes
immunogenic B-cell epitopes that induce variant-specific antibodies during
infection. Previously, we have shown that MSP2 is encoded on a polycistronic
mRNA transcript in erythrocyte stages of A. marginale and defined the structure
of the genomic expression site for this transcript. In this study, we show that
the same expression site is utilized in stages of A. marginale infecting tick
salivary glands. We also analyzed the variability of this genomic expression
site in Oklahoma strain A. marginale transmitted from in vitro cultures to
cattle and between cattle and ticks. The structure of the expression site and
flanking regions was conserved except for sequence that encoded the MSP2
hypervariable region. At least three different MSP2 variants were encoded in
each A. marginale population. The major sequence variants did not change on
passage of A. marginale between culture, acute erythrocyte stage infections, and
tick salivary glands but did change during persistent infections of cattle. The
variant types found in tick salivary glands most closely resembled those present
in bovine blood at the time of acquisition of infection, whether infection was
acquired from an acute or from a persistent rickettsemia. These variations in
structure of an expression site for a major, immunoprotective outer membrane
protein have important implications for vaccine development and for obtaining an
improved understanding of the mechanisms of persistence of ehrlichial infections
in humans, domestic animals, and reservoir hosts. We have analyzed the unique epitope for the broadly neutralizing human
monoclonal antibody (MAb) 2G12 on the gp120 surface glycoprotein of human
immunodeficiency virus type 1 (HIV-1). Sequence analysis, focusing on the
conservation of relevant residues across multiple HIV-1 isolates, refined the
epitope that was defined previously by substitutional mutagenesis (A. Trkola, M.
Purtscher, T. Muster, C. Ballaun, A. Buchacher, N. Sullivan, K. Srinivasan, J.
Sodroski, J. P. Moore, and H. Katinger, J. Virol. 70:1100-1108, 1996). In a
biochemical study, we digested recombit gp120 with various glycosidase
enzymes of known specificities and showed that the 2G12 epitope is lost when
gp120 is treated with mannosidases. Computational analyses were used to position
the epitope in the context of the virion-associated envelope glycoprotein
complex, to determine the variability of the surrounding surface, and to
calculate the surface accessibility of possible glycan- and polypeptide-epitope
components. Together, these analyses suggest that the 2G12 epitope is centered
on the high-mannose and/or hybrid glycans of residues 295, 332, and 392, with
peripheral glycans from 386 and 448 on either flank. The epitope is mannose
dependent and composed primarily of carbohydrate, with probably no direct
involvement of the gp120 polypeptide surface. It resides on a face orthogonal to
the CD4 binding face, on a surface proximal to, but distinct from, that
implicated in coreceptor binding. Its conservation amidst an otherwise highly
variable gp120 surface suggests a functional role for the 2G12 binding site,
perhaps related to the mannose-dependent attachment of HIV-1 to DC-SIGN or
related lectins that facilitate virus entry into susceptible target cells. The utility of immunohistochemistry (IHC) as a screening method for the
identification of persons with mutations in the DNA mismatch repair (MMR) genes
in hereditary nonpolyposis colorectal cancer (HNPCC) remains to be defined. In
this study, we analyzed the value of IHC versus that of microsatellite
instability (MSI) testing in predicting mutation status of the MLH1, MSH2, and
MSH6 genes in colorectal carcinomas and adenomas, and explored the frequency and
significance of immunohistochemical staining variability. The study samples
included 83 carcinomas and 29 adenomas derived from 110 patients who had strong
family histories of colorectal cancer. Our results showed that IHC correctly
predicted MSI status in 76% of the cases with a specificity of 100%. The overall
sensitivity of IHC in predicting a germline mutation was 79% (30 of 38) with a
specificity of 89% (48 of 54), whereas that of MSI testing was 97% (30 of 31)
with a specificity of 83% (35 of 42). Six of 31 analyzable cases that had a
disease-causing mutation and exhibited MSI showed normal IHC. The lower
sensitivity of IHC was caused mainly by its low sensitivity in detecting MLH1
gene mutation (4 of 9). Coexisting adenomas and carcinomas observed in the same
slide (n=12) showed a similar or identical staining pattern for all three
proteins. No significant difference was detected in the sensitivity of IHC or
MSI in detecting a germline mutation between isolated adenomas and carcinomas.
In IHC-positive cases, heterogeneous staining was noted in 30% to 40% of the
cases with the three different antibodies, and cytoplasmic staining in 5% to
13%. Weak IHC (defined as positive staining in <10% of the tumor with weak
intensity) was noted in 14 tumors: 5 for the MLH1 antibody, 1 for MSH2, and 8
for MSH6. One of the 5 MLH1 cases exhibited MSI and had an MLH1 germline
mutation. Five of the 8 MSH6 cases exhibited MSI and had MSH2 germline
mutations. In conclusion, our study shows that 1) IHC identifies a significant
portion of colorectal tumors derived from MMR gene germline mutation carriers
and can be used as an adjunct measure in the identification of HNPCC families,
but IHC cannot replace MSI testing; 2) adenomas have similar MMR protein
expression patterns as carcinomas and may serve as an adequate sample for
screening purposes in the identification of patients with MMR mutations; 3) not
all IHC-positive cases show uniform positivity throughout the tumor; and 4) weak
and focal staining of an MMR protein may be associated with MSI or gene mutation
or both, suggesting the need to incorporate staining intensity in further IHC
studies. The envelope glycoprotein of small rumit lentiviruses (SRLV) is a major
target of the humoral immune response and contains several linear B-cell
epitopes. We amplified and sequenced the genomic segment encoding the SU5
antigenic site of the envelope glycoprotein of several SRLV field isolates. With
synthetic peptides based on the deduced amino acid sequences of SU5 in an
enzyme-linked immunosorbent assay (ELISA), we have (i) proved the
immunodomice of this region regardless of its high variability, (ii) defined
the epitopes encompassed by SU5, (iii) illustrated the rapid and peculiar
kinetics of seroconversion to this antigenic site, and (iv) shown the rapid and
strong maturation of the avidity of the anti-SU5 antibody. Finally, we
demonstrated the modular diagnostic potential of SU5 peptides. Under Swiss field
conditions, the SU5 ELISA was shown to detect the majority of infected animals
and, when applied in a molecular epidemiological context, to permit rapid
phylogenetic classification of the infecting virus. BACKGROUND & AIMS: Broadly reactive neutralizing antibodies (nAbs) and
multispecific T-cell responses are generated during chronic hepatitis C virus
(HCV) infection and yet fail to clear the virus. This study investigated the
development of autologous nAb and HCV-glycoprotein-specific T-cell responses and
their effects on viral sequence evolution during chronic infection in order to
understand the reasons for their lack of effectiveness.
METHODS: Numerous E1E2 sequences were amplified and sequenced from serum samples
collected over a 26-year period from patient H, a uniquely well-characterized,
chronically infected individual. HCV pseudoparticles (HCVpp) expressing the
patient-derived glycoproteins were generated and tested for their sensitivity to
neutralization by autologous and heterologous serum antibodies.
RESULTS: A strain-specific nAb response developed early in infection (8 weeks
postinfection), whereas cross-reactive antibodies able to neutralize
HCVpp-bearing heterologous glycoproteins developed late in infection (>33 wk
postinfection). The humoral response continuously failed to neutralize viruses
bearing autologous glycoprotein sequences that were present in the serum at a
given time. The amplified glycoprotein sequences displayed high variability,
particularly in regions corresponding to defined linear B-cell epitopes.
Mutations in defined neutralizing epitopes were associated with a loss of
recognition by monoclonal antibodies against these epitopes and with decreased
neutralization of corresponding HCVpp. Viral escape from CD4 and CD8 T-cell
responses also was shown for several novel epitopes throughout the glycoprotein
region.
CONCLUSIONS: During chronic infection HCV is subjected to selection pressures
from both humoral and cellular immunity, resulting in the continuous generation
of escape variants. Respiratory pathogens, such as Neisseria meningitidis, secrete site-specific
proteases able to cleave human immunoglobulin A1 (IgA1), the first line of
defense at mucosal membranes. Bacterial isolates show wide variability in IgA1
protease activity, and those isolated from patients with clinical infection
possess the highest levels of activity. A feature of this enzyme is the
self-cleavage required for secretion of the mature extracellular form. Known
cleavage targets contain a proline-rich consensus recognition sequence,
Pro-Pro-Ser-Pro, residing in the variable linker region that connects the
protease and translocator domains. Here, we report the sequence of the NMB IgA1
protease and the unexpected self-cleavage and subsequent extracellular release
of mature IgA1 protease from mutants lacking the previously defined consensus
cleavage site. We investigated the possible link between enzyme secretion and
variability in the linker sequence segment using site-directed mutagenesis and
linker domain swapping to construct mutated and chimeric forms of the IgA1
protease from N. meningitidis strain NMB. The observed change in secreted
activity levels compared to the wild-type clone indicated that the precise amino
acid sequence of the intervening region, between mature IgA1 protease and the
beta-core translocator domain, influences the efficacy of autoproteolytic
processing. The broader specificity uncovered for the NMB IgA1 protease suggests
that it could cleave a far wider range of human proteins than previously
appreciated. IgA is the most abundantly produced antibody and plays an important role in the
mucosal immune system. Human IgA is represented by two isotypes, IgA1 and IgA2.
The major structural difference between these two subclasses is the presence of
nine potential sites of O-glycosylation in the hinge region between the first
and second constant region domains of the heavy chain. Thr(225), Thr(228),
Ser(230), Ser(232) and Thr(236) have been identified as the predomit sites of
O-glycan attachment. The range and distribution of O-glycan chains at each site
within the context of adjacent sites in this clustered region create a complex
heterogeneity of surface epitopes that is incompletely defined. We previously
described the analysis of IgA1 O-glycan heterogeneity by use of high resolution
LC-MS and electron capture dissociation tandem MS to unambiguously localize all
amino acid attachment sites in IgA1 (Ale) myeloma protein. Here, we report the
identification and elucidation of IgA1 O-glycopeptide structural isomers that
occur based on amino acid position of the attached glycans (positional isomers)
and the structure of the O-glycan chains at individual sites (glycan isomers).
These isomers are present in a model IgA1 (Mce1) myeloma protein and occur
naturally in normal human serum IgA1. Variable O-glycan chains attached to
Ser(230), Thr(233) or Thr(236) produce the predomit positional isomers,
including O-glycans composed of a single GalNAc residue. These findings
represent the first definitive identification of structural isomeric IgA1
O-glycoforms, define the single-site heterogeneity for all O-glycan sites in a
single sample, and have implications for defining epitopes based on clustered
O-glycan variability. Designing proteins that reflect the natural variability of a pathogen is
essential for developing novel vaccines and drugs. Flaviviruses, including
Dengue (DENV) and West Nile (WNV), evolve rapidly and can "escape" neutralizing
monoclonal antibodies by mutation. Designing antigens that represent many
distinct strains is important for DENV, where infection with a strain from one
of the four serotypes may lead to severe hemorrhagic disease on subsequent
infection with a strain from another serotype. Here, a DENV physicochemical
property (PCP)-consensus sequence was derived from 671 unique sequences from the
Flavitrack database. PCP-consensus proteins for domain 3 of the envelope protein
(EdomIII) were expressed from synthetic genes in Escherichia coli. The ability
of the purified consensus proteins to bind polyclonal antibodies generated in
response to infection with strains from each of the four DENV serotypes was
determined. The initial consensus protein bound antibodies from DENV-1-3 in
ELISA and Western blot assays. This sequence was altered in 3 steps to
incorporate regions of maximum variability, identified as significant changes in
the PCPs, characteristic of DENV-4 strains. The final protein was recognized by
antibodies against all four serotypes. Two amino acids essential for efficient
binding to all DENV antibodies are part of a discontinuous epitope previously
defined for a neutralizing monoclonal antibody. The PCP-consensus method can
significantly reduce the number of experiments required to define a multivalent
antigen, which is particularly important when dealing with pathogens that must
be tested at higher biosafety levels. |