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In which diseases have electronic patient diaries been applied ? | Parkinson's disease
COPD
Food hypersensitivity
Niacin induced flushing
Hemophilia
Heartburn
Headache | Attention needs to be given to how patients can capitalize on the benefits of
Personal Digital Assistant technology. The specific aims of this pilot study are
to compare the efficacy of diabetic patients documenting their health
maintece data (i.e. blood glucose levels, meal intake, and exercise) using an
electronic patient diary (ED) versus a traditional pen and paper (PD) diary; and
determine participants' satisfaction with each diary approach. On-demand or prophylactic home-treatment is currently the treatment of choice
for haemophilia patients. To allow physicians to monitor the amount of factor
concentrates administered, the patients document each factor injection in a
paper-diary. Nevertheless, because of the fact that most patients visit their
physicians only two to four times a year, there could be considerable delay in
detecting medication problems. The aim of this pilot study was to assess whether
an electronic documentation tool could successfully replace traditional
paper-diaries for haemophilia A patients and enable the physician to have a
timely overview of the patient's treatment. An electronic, hand-held
documentation tool, Haemoassist, was developed. In this study, patients using
prophylaxis and on-demand therapies documented their factor consumption both
electronically and on paper-diaries. Documentations were compared and
descriptively evaluated. Patients also completed a survey to evaluate the
feasibility and gather their opinions on the Haemoassist system. Ten patients
from two haemophilia treatment centres in Germany submitted a total of 548
records via hand-held device during the observation period, from March 2006 to
February 2007. Comparison of electronic and paper-based records showed differing
responses among patients with some patients entering more electronic and some
others more paper-based documentations. In the questionnaires on feasibility and
usefulness of Haemoassist, three patients preferred the electronic tool, two
patients wanted to continue using paper-based diaries, and one had no
preference. The study shows that an electronic documentation system is feasible
for haemophilia patients and provides the physician with the opportunity to more
closely monitor patients. However, not all patients seem to be qualified for
using an electronic tool, and the tool has to run reliably without major errors
for ensuring reliability and acceptability. In the future, Haemoassist might
support quality assurance in haemophilia treatment and improve guidance in the
home-care setting. BACKGROUND AND OBJECTIVE: A common adverse effect of niacin therapy is flushing,
manifested by cutaneous warmth, redness, itching and/or tingling. The Flushing
ASsessment Tool (FAST) was developed to assess flushing symptoms and their
impact on patients receiving niacin therapy. This study evaluated the
reliability, validity and responsiveness of the FAST. The minimal important
difference (MID) of the FAST was also examined.
METHODS: This was a prospective, randomized, double-blind, placebo-controlled,
parallel-group 8-week study conducted to evaluate the psychometric
characteristics of the FAST. The instrument is administered daily using an
electronic patient diary. The study was conducted at 41 clinical sites in the
US. 276 patients with dyslipidaemia were randomized to treatment and were at
least 18 years of age, with fasting laboratory values of low-density lipoprotein
cholesterol (LDL-C) <250 mg/dL and one of the following: high-density
lipoprotein cholesterol (HDL-C) <40 mg/dL for males or <50 mg/dL for females; or
triglycerides (TG) > or = 150 and < or = 400 mg/dL; or LDL-C > or = 70 mg/dL for
patients with a history of coronary heart disease (CHD) or CHD risk equivalents,
or > or = 100 mg/dL for subjects with two risk factors, or > or = 160 mg/dL for
subjects with 0-1 risk factors. Patients were randomized (1 : 1 : 1) to receive
niacin extended-release (NER) 500 mg/day in week 1, 1000 mg/day in week 2 and
2000 mg/day in weeks 3-6/aspirin (acetylsalicylic acid [ASA]), NER/ASA placebo,
or NER placebo/ASA placebo.
RESULTS: FAST test-retest reliability in stable patients during the first 2
weeks was demonstrated for overall flushing severity using patient and physician
overall treatment effect (OTE) ratings (intraclass correlation coefficients of
>0.7 for mean overall and individual flushing severity scores). Over the 6-week
treatment period, FAST scores demonstrated significant correlations with
individual symptoms, impact on daily activities and sleep, and dissatisfaction
related to flushing (p < 0.01). Changes in FAST scores were associated with
treatment satisfaction (p < 0.01) and patient- and physician-rated OTE (p <
0.01). Using patient-rated OTE, the mean maximum flushing severity scores
improved 1.85 points in responders and only 0.18 points in non-responders (p <
0.001); responders were defined by improved patient- or physician-rated OTE.
Among patients with flushing, mean maximum overall flushing scores differed
between patients who subsequently discontinued due to flushing (7.9 points) and
those who did not discontinue (4.7 points; p < 0.001). The probable range in
this study for a detectable change in flushing symptoms (MID) was 0.29-0.38
points for mean flushing severity and 0.66-0.86 points for maximum flushing
severity.
CONCLUSION: The FAST exhibited test-retest reliability, good evidence of
construct validity, and, overall, flushing severity was responsive to change
over time. The FAST is a reliable and valid instrument for assessing the impact
of niacin-induced flushing in patients with dyslipidaemia. Several studies have shown that the current prevalence of food allergy in
Western Europe is about 4% and will further increase. Because of missing
therapeutic alternatives, food allergy patients are required to identify
individual allergens in the daily food by carefully reading the product's
ingredient lists. Experiences with other chronic diseases show that a
combination of telemedicine and Disease Management (DM) could have a positive
impact on medical outcome and health related costs. A new concept of
telemedicine support for allergy patients and allergists has been elaborated
within the Luxembourgian MENSSANA project. Instead of measuring physiological
parameters, a Smartphone based Personal Allergy Assistant (PAA) allows patients
to keep an electronic patient diary by scanning the barcode of the consumed food
products. For diagnostic purpose, the diary is regularly transmitted to the
allergist's electronic patient record. To further support the individual diet
management, the PAA gives a warning before consumption of allergenic food.
Computer readable food ingredient lists are required for the PAA diet
management. To collect this kind of information, a dedicated web-based "virtual
community" of food consumers and producers (www.wikifood.eu) has been
established. This volunteer network complements an independent product database.
Up to now, more than 13.000 food descriptions are public available within
wikifood.eu. This research paper examines the challenges in the development and adoption of
an electronic patient diary within the Pathways Home for Respiratory Illness
Project. This project supported community-based patients suffering from chronic
obstructive pulmonary disease (COPD) to achieve increased levels of
self-management and self-efficacy using electronic-monitoring techniques and
mentoring by community health nurses. Participants had the option of voluntarily
adopting an electronic patient diary to support their self-monitoring, which
provided patients, nurses and clinicians with access to symptom and
psycho-social data. This aimed to improve the identification, comprehension and
initiation of early action in relation to alterations in their conditions. The
paper presents data on technology adoption, electronic diary usage and,
self-reported data quality, as well as examining the impact of the technology on
hospitalisations (frequency and duration). The participants who chose to use the
online patient diary continued their involvement with the project for the entire
trial period (85% vs 54% completion). Participants were more likely to maintain
use of the online patient diary than the paper diary. Both the groups
experienced a positive improvement in their self-efficacy to self-manage their
condition scores. The data highlight the problems implicit in some of the
assumptions underpinning existing information systems models, especially in
evaluating impact and the end-points presumed to be relevant in systems
development life cycles. Current clinical methods for the assessment of Parkinson's disease suffer from
inconvenience, infrequency and subjectivity. WiiPD is an approach for the
objective home based assessment of Parkinson's disease which utilizes the
intuitive and sensor rich Nintendo Wii Remote. Combined with an electronic
patient diary, a suite of mini-games, a metric analyzer, and a visualization
engine, we propose that this system can complement existing clinical practice by
providing objective metrics gathered frequently over extended periods of time.
In this paper we detail the approach and introduce a series of metrics deemed
capable of quantifying the severity of tremor and bradykinesia in those with
Parkinson's disease. The system has been tested on a 71 year old participant
with Parkinson's disease over a period of 15 days, a 72 year old control user
without Parkinson's disease, and a group of 8 young adults. Results indicate a
clear correlation between patient self rating scores of tremor severity and
metric values obtained, in addition to clear differences in metrics obtained
from each user group. These results suggest that this approach is capable of
indicating the presence and severity of the motor symptoms of Parkinson's
disease that affect arm motor control. |
Which type of myeloma is ixazomib being evaluated for? | The disease focus for the irreversible epoxyketone proteasome inhibitor ixazomib is multiple myeloma. | (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed
tomography (CT) are useful imaging modalities for evaluating tumor progression
and treatment responses in genetically engineered mouse models of solid human
cancers, but the potential of integrated FDG-PET/CT for assessing tumor
development and new interventions in transgenic mouse models of human blood
cancers such as multiple myeloma (MM) has not been demonstrated. Here we use
BALB/c mice that contain the newly developed iMyc(ΔEμ) gene insertion and the
widely expressed H2-L(d)-IL6 transgene to demonstrate that FDG-PET/CT affords an
excellent research tool for assessing interleukin-6- and MYC-driven plasma cell
tumor (PCT) development in a serial, reproducible and stage- and lesion-specific
manner. We also show that FDG-PET/CT permits determination of objective drug
responses in PCT-bearing mice treated with the investigational proteasome
inhibitor ixazomib (MLN2238), the biologically active form of ixazomib citrate
(MLN9708), that is currently in phase 3 clinical trials in MM. Overall survival
of 5 of 6 ixazomib-treated mice doubled compared with mice left untreated. One
outlier mouse presented with primary refractory disease. Our findings
demonstrate the utility of FDG-PET/CT for preclinical MM research and suggest
that this method will play an important role in the design and testing of new
approaches to treat myeloma. Multiple myeloma is still an incurable disease with pattern of regression and
remission followed by multiple relapses raising from the residual myeloma cells
surviving even in the patients who achieve complete clinical response to
treatment. New antimyeloma drugs such as thalidomide, lenalidomide, and
bortezomib have dramatically changed treatment paradigm leading to both tumor
reduction and tumor suppression. Much progress has been made, but still many
unsolved questions remain. In the mode of sequencing treatment for patients with
multiple myeloma, we are still using old drugs such as the alkylating agent
melphalan, which continues to play a central role in the transplantation
setting. Newer drugs are now emerging and are being tested: monoclonal
antibodies, histone deacetylase (romidespsin), MLN9708 (ixazomib) a new oral
proteasome inhibitor, carfilzomib, signal transduction modulator perifosine.
Many advances have been made, but there is still a long way to go. Inhibition of proteasome, a proteolytic complex responsible for the degradation
of ubiquitinated proteins, has emerged as a powerful strategy for treatment of
multiple myeloma (MM), a plasma cell maligcy. First-in-class agent,
bortezomib, has demonstrated great positive therapeutic efficacy in MM, both in
pre-clinical and in clinical studies. However, despite its high efficiency, a
large proportion of patients do not achieve sufficient clinical response.
Therefore, the development of a second-generation of proteasome inhibitors (PIs)
with improved pharmacological properties was needed. Recently, several of these
new agents have been introduced into clinics including carfilzomib, marizomib
and ixazomib. Further, new orally administered second-generation PI oprozomib is
being investigated. This review provides an overview of main mechanisms of
action of PIs in MM, focusing on the ongoing development and progress of novel
anti-proteasome therapeutics. Proteasome inhibition is an effective treatment strategy for multiple myeloma.
With improving survival, attention is increasingly focusing on ease of
administration and toxicity profile. Ixazomib is an investigational, orally
bioavailable 20S proteasome inhibitor. Sixty patients with relapsed and/or
refractory multiple myeloma were enrolled on this phase 1 trial to evaluate
safety and tolerability and determine the maximum tolerated dose (MTD) of
single-agent, oral ixazomib given weekly for 3 of 4 weeks. Upon MTD
determination, patients were enrolled to 4 different cohorts based on
relapsed/refractory status and prior bortezomib and carfilzomib exposure. The
MTD was determined to be 2.97 mg/m(2). Dose-limiting toxicities were grade 3
nausea, vomiting, and diarrhea in 2 patients, and grade 3 skin rash in 1
patient. Common drug-related adverse events were thrombocytopenia (43%),
diarrhea (38%), nausea (38%), fatigue (37%), and vomiting (35%). The observed
rate of peripheral neuropathy was 20%, with only 1 grade 3 event reported. Nine
(18%) patients achieved a partial response or better, including 8 of 30 (27%)
evaluable patients treated at the MTD. Pharmacokinetic studies suggested a long
terminal half-life of 3.6 to 11.3 days, supporting once-weekly dosing. This
trial was registered at www.clinicaltrials.gov as #NCT00963820. Ixazomib is the first investigational oral proteasome inhibitor to be studied
clinically. In this phase 1 trial, 60 patients with relapsed/refractory multiple
myeloma (median of 4 prior lines of therapy; bortezomib, lenalidomide,
thalidomide, and carfilzomib/marizomib in 88%, 88%, 62%, and 5%, respectively)
received single-agent ixazomib 0.24 to 2.23 mg/m(2) (days 1, 4, 8, 11; 21-day
cycles). Two dose-limiting toxicities (grade 3 rash; grade 4 thrombocytopenia)
occurred at 2.23 mg/m(2). The maximum tolerated dose was 2.0 mg/m(2), which 40
patients received in 4 expansion cohorts. Patients received a median of 4 cycles
(range, 1-39); 18% received ≥12 cycles. Eighty-eight percent had drug-related
adverse events, including nausea (42%), thrombocytopenia (42%), fatigue (40%),
and rash (40%); drug-related grade ≥3 events included thrombocytopenia (37%) and
neutropenia (17%). Grade 1/2 drug-related peripheral neuropathy occurred in 12%
(no grade ≥3). Two patients died on the study (both considered unrelated to
treatment). The terminal half-life of ixazomib was 3.3 to 7.4 days; plasma
exposure increased proportionally with dose (0.48-2.23 mg/m(2)). Among 55
response-evaluable patients, 15% achieved partial response or better (76% stable
disease or better). These findings have informed the subsequent clinical
development of ixazomib in multiple myeloma. This trial was registered at
www.clinicaltrials.gov as #NCT00932698. Proteasome inhibition represents one of the more important therapeutic targets
in the treatment of multiple myeloma (MM), since by suppressing nuclear
factor-κB activity, which promotes myelomagenesis, it makes plasma cells
susceptible to proapoptotic signals. Bortezomib, the first proteasome inhibitor
approved for MM therapy, has been shown to increase response rate and improve
outcome in patients with relapsed/refractory disease and in the frontline
setting, particularly when combined with immunomodulatory drugs and alkylating
agents. Among second-generation proteasome inhibitors, ixazomib (MLN9708) is the
first oral compound to be evaluated for the treatment of MM. Ixazomib has shown
improved pharmacokinetic and pharmacodynamic parameters compared with
bortezomib, in addition to similar efficacy in the control of myeloma growth and
prevention of bone loss. Ixazomib was found to overcome bortezomib resistance
and to trigger synergistic antimyeloma activity with dexamethasone,
lenalidomide, and histone deacetylase inhibitors. Phase I/II studies using
ixazomib weekly or twice weekly in relapsed/refractory MM patients suggested
antitumor activity of the single agent, but more promising results have been
obtained with the combination of ixazomib, lenalidomide, and dexamethasone in
newly diagnosed MM. Ixazomib has also been used in systemic amyloidosis as a
single agent, showing important activity in this difficult-to-treat plasma-cell
dyscrasia. More frequent side effects observed during administration of ixazomib
were thrombocytopenia, nausea, vomiting, diarrhea, fatigue, and rash, whereas
severe peripheral neuropathy was rare. Here, we review the chemical
characteristics of ixazomib, as well as its mechanism of action and results from
preclinical and clinical trials. BACKGROUND: The combination of bortezomib, lenalidomide, and dexamethasone is a
highly effective therapy for newly diagnosed multiple myeloma. Ixazomib is an
investigational, oral, proteasome inhibitor with promising anti-myeloma effects
and low rates of peripheral neuropathy. In a phase 1/2 trial we aimed to assess
the safety, tolerability, and activity of ixazomib in combination with
lenalidomide and dexamethasone in newly diagnosed multiple myeloma.
METHODS: We enrolled patients newly diagnosed with multiple myeloma aged 18
years or older with measurable disease, Eastern Cooperative Oncology Group
performance status 0-2, and no grade 2 or higher peripheral neuropathy, and
treated them with oral ixazomib (days 1, 8, 15) plus lenalidomide 25 mg (days
1-21) and dexamethasone 40 mg (days 1, 8, 15, 22) for up to 12 28-day cycles,
followed by maintece therapy with ixazomib alone. In phase 1, we gave
patients escalating doses of ixazomib (1·68-3·95 mg/m(2)) to establish the
recommended dose for phase 2. The primary endpoints were maximum tolerated dose
for phase 1, and the rate of very good partial response or better for phase 2.
Safety analyses were done in all patients who received at least one dose of
study drug; efficacy analyses were done in all patients who received at least
one dose of study drug at the phase 2 dose, had measurable disease at baseline,
and had at least one post-baseline response assessment. This study is registered
at ClinicalTrials.gov, number NCT01217957.
FINDINGS: Between Nov 22, 2010, and Feb 28, 2012, we enrolled 65 patients (15 to
phase 1 and 50 to phase 2). Four dose-limiting toxic events were noted in phase
1: one at a dose of ixazomib of 2·97 mg/m(2) and three at 3·95 mg/m(2). The
maximum tolerated dose of ixazomib was established as 2·97 mg/m(2) and the
recommended phase 2 dose was 2·23 mg/m(2), which was converted to a 4·0 mg fixed
dose based on population pharmacokinetic results. Grade 3 or higher adverse
events related to any drug were reported in 41 (63%) patients, including skin
and subcutaneous tissue disorders (11 patients, 17%), neutropenia (eight
patients, 12%), and thrombocytopenia (five patients, 8%); drug-related
peripheral neuropathy of grade 3 or higher occurred in four (6%) patients. Five
patients discontinued because of adverse events. In 64 response-evaluable
patients, 37 (58%, 95% CI 45-70) had a very good partial response or better.
INTERPRETATION: The all-oral combination of weekly ixazomib plus lenalidomide
and dexamethasone was generally well tolerated and appeared active in newly
diagnosed multiple myeloma. These results support the phase 3 trial development
of this combination for multiple myeloma.
FUNDING: Millennium Pharmaceuticals, a wholly owned subsidiary of Takeda
Pharmaceutical International Company. |
Which are the Atg8 homologs in human? | Autophagy (Autophagy-related protein 8 or Atg8p or APG8 or AUT7 or CVT5) is a yeast protein involved in cytoplasm to vacuole transport (Cvt) vesicles and autophagosomes formation. In yeast it is represented by a single gene, the ATG8 family in humans contains 6 members (microtubule-associated protein-1 light chain 3A (MAP1LC3A), MAP1LC3B, MAP1LC3C, GABA(A) receptor-associated protein (GABARAP), GABARAPL1, and GABARAPL2/GATE-16). | In yeast, phosphatidylethanolamine is a target of the Atg8 modifier in
ubiquitylation-like reactions essential for autophagy. Three human Atg8 (hAtg8)
homologs, LC3, GABARAP, and GATE-16, have been characterized as modifiers in
reactions mediated by hAtg7 (an E1-like enzyme) and hAtg3 (an E2-like enzyme) as
in yeast Atg8 lipidation, but their final targets have not been identified. The
results of a recent study in which COS7 cells were incubated with
[14C]ethanolamine for 48 h suggested that phosphatidylethanolamine is a target
of LC3. However, these results were not conclusive because of the long
incubation time. To identify the phospholipid targets of Atg8 homologs, we
reconstituted conjugation systems for mammalian Atg8 homologs in vitro using
purified recombit Atg proteins and liposomes. Each purified mutant Atg8
homolog with an exposed C-terminal Gly formed an E1-substrate intermediate with
hAtg7 via a thioester bond in an ATP-dependent manner and formed an E2-substrate
intermediate with hAtg3 via a thioester bond dependent on ATP and hAtg7. A
conjugated form of each Atg8 homolog was observed in the presence of hAtg7,
hAtg3, ATP, and liposomes. In addition to phosphatidylethanolamine, in vitro
conjugation experiments using synthetic phospholipid liposomes showed that
phosphatidylserine is also a target of LC3, GABARAP, and GATE-16. In contrast,
thin layer chromatography of phospholipids released on hAtg4B-digestion from
endogenous LC3-phospholipid conjugate revealed that phosphatidylethanolamine,
but not phosphatidylserine, is the predomit target phospholipid of LC3 in
vivo. The discrepancy between in vitro and in vivo reactions suggested that
there may be selective factor(s) involved in the endogenous LC3 conjugation
system. Autophagy is an important catabolic process with roles in cell survival and cell
death. It sequesters cytosol and organelles within double-membrane
autophagosomes that deliver their contents to lysosomes for degradation.
Autophagosome biogenesis is coordinated by the autophagy-related protein 4
(Atg4) family of C54 endopeptidases (Atg4A-Atg4D). These enzymes prime and then
later delipidate the autophagosome marker, Atg8. Here, we show that one family
member, Atg4D, is cleaved by caspase-3 in vitro and in apoptotic cells. Atg4D is
a poor priming and delipidation enzyme in vitro, but truncated DeltaN63 Atg4D
displays increased activity against the Atg8 paralogue, gamma-aminobutyric acid
receptor-associated protein-like 1 (GABARAP-L1). In living cells, DeltaN63 Atg4D
stimulates the delipidation of GABARAP-L1, whereas siRNA silencing of the gene
expressing Atg4D abrogates GABARAP-L1 autophagosome formation and sensitises
cells to starvation and staurosporine-induced cell death. Interestingly, Atg4D
overexpression induces apoptosis, which is preceded by the caspase-independent
recruitment of Atg4D to mitochondria and is facilitated by a putative C-terminal
Bcl-2 homology 3 (BH3) domain. Atg4D also acquires affinity for damaged
mitochondria in cells treated with hydrogen peroxide. These data suggest that
Atg4D is an autophagy regulator that links mitochondrial dysfunction with
apoptosis. ATG12, an ubiquitin-like modifier required for macroautophagy, has a single
known conjugation target, another autophagy regulator called ATG5. Here, we
identify ATG3 as a substrate for ATG12 conjugation. ATG3 is the E2-like enzyme
necessary for ATG8/LC3 lipidation during autophagy. ATG12-ATG3 complex formation
requires ATG7 as the E1 enzyme and ATG3 autocatalytic activity as the E2,
resulting in the covalent linkage of ATG12 onto a single lysine on ATG3.
Surprisingly, disrupting ATG12 conjugation to ATG3 does not affect
starvation-induced autophagy. Rather, the lack of ATG12-ATG3 complex formation
produces an expansion in mitochondrial mass and inhibits cell death mediated by
mitochondrial pathways. Overall, these results unveil a role for ATG12-ATG3 in
mitochondrial homeostasis and implicate the ATG12 conjugation system in cellular
functions distinct from the early steps of autophagosome formation. Glycogen, a branched polymer of glucose, acts as an intracellular carbon and
energy reserve in many tissues and cell types. An important pathway for its
degradation is by transport to lysosomes in an autophagy-like process. It has
been proposed that starch-binding domain-containing protein 1 (Stbd1) may
participate in this mechanism by anchoring glycogen to intracellular membranes.
In addition, Stbd1 has been reported to interact with a known autophagy protein,
GABARAPL1, a member of the Atg8 family. Here, we confirm this interaction and
identify an Atg8 interacting motif (AIM) in Stbd1 necessary for GABARAPL1
binding as judged by co-immunoprecipitation from cell extracts and
co-localization in cells as evidenced by immunofluorescence microscopy. The AIM
sequence of Stbd1 (200)HEEWEMV(206) lies within a predicted disordered region of
the molecule and fits the consensus of other AIM sequences in cargo-specifying
proteins such as p62 and Nix. Mutation of the AIM, including single point
mutations of either W203 or V206, eliminated the co-localization of Stbd1 with
both over-expressed and endogenous GABARAPL1. Stbd1 may therefore function as a
novel cargo binding protein that delivers glycogen to lysosomes in an autophagic
pathway that could be termed "glycophagy". Atg4 is required for cleaving Atg8, allowing it to be conjugated to
phosphatidylethanolamine on phagophore membranes, a key step in autophagosome
biogenesis. Deconjugation of Atg8 from autophagosomal membranes could be also a
regulatory step in controlling autophagy. Therefore, the activity of Atg4 is
important for autophagy and could be a target for therapeutic intervention. In
this study, a sensitive and specific method to measure the activity of two Atg4
homologs in mammalian cells, Atg4A and Atg4B, was developed using a fluorescence
resoce energy transfer (FRET)-based approach. Thus LC3B and GATE-16, two
substrates that could be differentially cleaved by Atg4A and Atg4B, were fused
with CFP and YFP at the N- and C-terminus, respectively, allowing FRET to occur.
The FRET signals decreased in proportion to the Atg4-mediated cleavage, which
separated the two fluorescent proteins. This method is highly efficient for
measuring the enzymatic activity and kinetics of Atg4A and Atg4B under in vitro
conditions. Applications of the assay indicated that the activity of Atg4B was
dependent on its catalytic cysteine and expression level, but showed little
changes under several common autophagy conditions. In addition, the assays
displayed excellent performance in high throughput format and are suitable for
screening and analysis of potential modulators. In summary, the FRET-based assay
is simple and easy to use, is sensitive and specific, and is suitable for both
routine measurement of Atg4 activity and high-throughput screening. Macroautophagy (hereafter referred to as autophagy) is an evolutionarily
conserved catabolic process necessary for normal recycling of cellular
constituents and for appropriate response to cellular stress. Although several
genes belonging to the core molecular machinery involved in autophagosome
formation have been discovered, relatively little is known about the nature of
signaling networks controlling autophagy upon intracellular or extracellular
stimuli. We discovered ATG8-like proteins (MAP1LC3B, GABARAP and GABARAPL1) as
novel interactors of MAPK15/ERK8, a MAP kinase involved in cell proliferation
and transformation. Based on the role of these proteins in the autophagic
process, we demonstrated that MAPK15 is indeed localized to autophagic
compartments and increased, in a kinase-dependent fashion, ATG8-like proteins
lipidation, autophagosome formation and SQSTM1 degradation, while decreasing
LC3B inhibitory phosphorylation. Interestingly, we also identified a conserved
LC3-interacting region (LIR) in MAPK15 responsible for its interaction with
ATG8-like proteins, for its localization to autophagic structures and,
consequently, for stimulation of the formation of these compartments.
Furthermore, we reveal that MAPK15 activity was induced in response to serum and
amino-acid starvation and that this stimulus, in turn, required endogenous
MAPK15 expression to induce the autophagic process. Altogether, these results
suggested a new function for MAPK15 as a regulator of autophagy, acting through
interaction with ATG8 family proteins. Also, based on the key role of this
process in several human diseases, these results supported the use of this MAP
kinase as a potential novel therapeutic target. Autophagy protects cellular homeostasis by capturing cytosolic components and
invading pathogens for lysosomal degradation. Autophagy receptors target cargo
to autophagy by binding ATG8 on autophagosomal membranes. The expansion of the
ATG8 family in higher eukaryotes suggests that specific interactions with
autophagy receptors facilitate differential cargo handling. However, selective
interactors of ATG8 orthologs are unknown. Here we show that the selectivity of
the autophagy receptor NDP52 for LC3C is crucial for innate immunity since cells
lacking either protein cannot protect their cytoplasm against Salmonella. LC3C
is required for antibacterial autophagy because in its absence the remaining
ATG8 orthologs do not support efficient antibacterial autophagy. Structural
analysis revealed that the selectivity of NDP52 for LC3C is conferred by a
noncanonical LIR, in which lack of an aromatic residue is balanced by
LC3C-specific interactions. Our report illustrates that specificity in the
interaction between autophagy receptors and autophagy machinery is of functional
importance to execute selective autophagy. |
To which family does the Zika virus belong? | The Zika virus belongs to the family Flaviviridae. | BACKGROUND: Zika virus (ZIKV; genus Flavivirus, family Flaviviridae) is
maintained in a zoonotic cycle between arboreal Aedes spp. mosquitoes and
nonhuman primates in African and Asian forests. Spillover into humans has been
documented in both regions and the virus is currently responsible for a large
outbreak in French Polynesia. ZIKV amplifications are frequent in southeastern
Senegal but little is known about their seasonal and spatial dynamics. The aim
of this paper is to describe the spatio-temporal patterns of the 2011 ZIKV
amplification in southeastern Senegal.
METHODOLOGY/FINDINGS: Mosquitoes were collected monthly from April to December
2011 except during July. Each evening from 18:00 to 21:00 hrs landing
collections were performed by teams of 3 persons working simultaneously in
forest (canopy and ground), savannah, agriculture, village (indoor and outdoor)
and barren land cover sites. Mosquitoes were tested for virus infection by virus
isolation and RT-PCR. ZIKV was detected in 31 of the 1,700 mosquito pools
(11,247 mosquitoes) tested: Ae. furcifer (5), Ae. luteocephalus (5), Ae.
africanus (5), Ae. vittatus (3), Ae. taylori, Ae. dalzieli, Ae. hirsutus and Ae.
metallicus (2 each) and Ae. aegypti, Ae. unilinaetus, Ma. uniformis, Cx.
perfuscus and An. coustani (1 pool each) collected in June (3), September (10),
October (11), November (6) and December (1). ZIKV was detected from mosquitoes
collected in all land cover classes except indoor locations within villages. The
virus was detected in only one of the ten villages investigated.
CONCLUSIONS/SIGNIFICANCE: This ZIKV amplification was widespread in the Kédougou
area, involved several mosquito species as probable vectors, and encompassed all
investigated land cover classes except indoor locations within villages. Aedes
furcifer males and Aedes vittatus were found infected within a village, thus
these species are probably involved in the transmission of Zika virus to humans
in this environment. |
Has the fungus Ashbya gossypii got many nuclei that share cytoplasm? | Yes, Ashbya gossypii has a budding yeast-like genome but grows exclusively as multinucleated hyphae. | We have followed the migration of GFP-labelled nuclei in multinucleate hyphae of
Ashbya gossypii. For the first time we could demonstrate that the mode of long
range nuclear migration consists of oscillatory movements of nuclei with, on
average, higher amplitudes in the direction of the growing tip. We could also
show that mitotic division proceeds at a constant rate of 0. 64 microm/minute
which differs from the biphasic kinetics described for the yeast Saccharomyces
cerevisiae. Furthermore we were able to identify the microtubule-based motor
dynein as a key element in the control of long range nuclear migration. For
other filamentous fungi it had already been demonstrated that inactivating
mutations in dynein led to severe problems in nuclear migration, i.e. generation
of long nuclei-free hyphal tips and clusters of nuclei throughout the hyphae.
This phenotype supported the view that dynein is important for the movement of
nuclei towards the tip. In A. gossypii the opposite seems to be the case. A
complete deletion of the dynein heavy chain gene leads to nuclear clusters
exclusively at the hyphal tips and to an essentially nucleus-free network of
hyphal tubes and branches. Anucleate hyphae and branches in the vicinity of
nuclear clusters show actin cables and polarized actin patches, as well as
microtubules. The slow growth of this dynein null mutant could be completely
reverted to wild-type-like growth in the presence of benomyl, which can be
explained by the observed redistribution of nuclei in the hyphal network. A few years ago, A. gossypii became recognized as an attractive model to study
the growth of long and multinucleated fungal cells (hyphae) because of its small
genome, haploid nuclei, and efficient gene targeting methods. It is generally
assumed that a better understanding of filamentous fungal growth will greatly
stimulate the development of novel fungicides. The use of Ashbya gossypii as a
model is particularly promising because of the high level of gene order
conservation (synteny) between the genomes of A. gossypii and the yeast
Saccharomyces cerevisiae. Thus, a similar set of genes seems to control the
surprisingly different growth modes of these two organisms, which predicts that
orthologous growth control genes might not play identical cellular roles in both
systems. Analyzing the phenotypes of A. gossypii mutants lacking factors with
known functions in yeast morphogenesis and nuclear dynamics confirm this
hypothesis. Comparative genomics of both organisms also reveals rare examples of
differences in the gene sets for some cellular processes, which as shown for
phosphate homeostasis can be associated with differences in control levels. Synchronous mitosis is common in multinucleated cells. We analyzed a unique
asynchronous nuclear division cycle in a multinucleated filamentous fungus,
Ashbya gossypii. Nuclear pedigree analysis and observation of GFP-labeled
spindle pole bodies demonstrated that neighboring nuclei in A. gossypii cells
are in different cell cycle stages despite close physical proximity. Neighboring
nuclei did not differ significantly in their patterns of cyclin protein
localization such that both G1 and mitotic cyclins were present regardless of
cell cycle stage, suggesting that the complete destruction of cyclins is not
occurring in this system. Indeed, the expression of mitotic cyclin lacking
NH(2)-terminal destruction box sequences did not block cell cycle progression.
Cells lacking AgSic1p, a predicted cyclin-dependent kinase (CDK) inhibitor,
however, showed aberrant multipolar spindles and fragmented nuclei that are
indicative of flawed mitoses. We hypothesize that the continuous cytoplasm in
these cells promoted the evolution of a nuclear division cycle in which CDK
inhibitors primarily control CDK activity rather than oscillating mitotic cyclin
proteins. Cyclin protein behavior has not been systematically investigated in
multinucleated cells with asynchronous mitoses. Cyclins are canonical
oscillating cell cycle proteins, but it is unclear how fluctuating protein
gradients can be established in multinucleated cells where nuclei in different
stages of the division cycle share the cytoplasm. Previous work in A. gossypii,
a filamentous fungus in which nuclei divide asynchronously in a common
cytoplasm, demonstrated that one G1 and one B-type cyclin do not fluctuate in
abundance across the division cycle. We have undertaken a comprehensive analysis
of all G1 and B-type cyclins in A. gossypii to determine whether any of the
cyclins show periodic abundance across the cell cycle and to examine whether
cyclins exhibit functional redundancy in such a cellular environment. We
localized all G1 and B-type cyclins and notably found that only AgClb5/6p varies
in subcellular localization during the division cycle. AgClb5/6p is lost from
nuclei at the meta-anaphase transition in a D-box-dependent manner. These data
demonstrate that efficient nuclear autonomous protein degradation can occur
within multinucleated cells residing in a common cytoplasm. We have shown that
three of the five cyclins in A. gossypii are essential genes, indicating that
there is minimal functional redundancy in this multinucleated system. In
addition, we have identified a cyclin, AgClb3/4p, that is essential only for
sporulation. We propose that the cohabitation of different cyclins in nuclei has
led to enhanced substrate specificity and limited functional redundancy within
classes of cyclins in multinucleated cells. Ashbya gossypii has a budding yeast-like genome but grows exclusively as
multinucleated hyphae. In contrast to budding yeast where positioning of nuclei
at the bud neck is a major function of cytoplasmic microtubules (cMTs), A.
gossypii nuclei are constantly in motion and positioning is not an issue. To
investigate the role of cMTs in nuclear oscillation and bypassing, we
constructed mutants potentially affecting cMT lengths. Hyphae lacking the plus
(+)end marker Bik1 or the kinesin Kip2 cannot polymerize long cMTs and lose
wild-type nuclear movements. Interestingly, hyphae lacking the kinesin Kip3
display longer cMTs concomitant with increased nuclear oscillation and
bypassing. Polymerization and depolymerization rates of cMTs are 3 times higher
in A. gossypii than in budding yeast and cMT catastrophes are rare. Growing cMTs
slide along the hyphal cortex and exert pulling forces on nuclei. Surprisingly,
a capture/shrinkage mechanism seems to be absent in A. gossypii. cMTs reaching a
hyphal tip do not shrink, and cMT +ends accumulate in hyphal tips. Thus,
differences in cMT dynamics and length control between budding yeast and A.
gossypii are key elements in the adaptation of the cMT cytoskeleton to much
longer cells and much higher degrees of nuclear mobilities. During filamentous fungus development, multinucleated hyphae employ a system for
long-range nuclear migration to maintain an equal nuclear density. A decade ago
the microtubule motor dynein was shown to play a central role in this process.
Previous studies with Ashbya gossypii revealed extensive bidirectional movements
and bypassings of nuclei, an autonomous cytoplasmic microtubule (cMT)
cytoskeleton emanating from each nucleus, and pulling of nuclei by sliding of
cMTs along the cortex. Here, we show that dynein is the sole motor for
bidirectional movements and bypassing because these movements are concomitantly
decreased in mutants carrying truncations of the dynein heavy-chain DYN1
promoter. The dynactin component Jnm1, the accessory proteins Dyn2 and Ndl1, and
the potential dynein cortical anchor Num1 are also involved in the dynamic
distribution of nuclei. In their absence, nuclei aggregate to different degrees,
whereby the mutants with dense nuclear clusters grow extremely long cMTs. As in
budding yeast, we found that dynein is delivered to cMT plus ends, and its
activity or processivity is probably controlled by dynactin and Num1. Together
with its role in powering nuclear movements, we propose that dynein also plays
(directly or indirectly) a role in the control of cMT length. Those combined
dynein actions prevent nuclear clustering in A. gossypii and thus reveal a novel
cellular role for dynein. We report the mechanistic basis guiding the migration pattern of multiple nuclei
in hyphae of Ashbya gossypii. Using electron tomography, we reconstructed the
cytoplasmic microtubule (cMT) cytoskeleton in three tip regions with a total of
13 nuclei and also the spindle microtubules of four mitotic nuclei. Each spindle
pole body (SPB) nucleates three cMTs and most cMTs above a certain length grow
according to their plus-end structure. Long cMTs closely align for several
microns along the cortex, presumably marking regions where dynein generates
pulling forces on nuclei. Close proximity between cMTs emanating from adjacent
nuclei was not observed. The majority of nuclei carry duplicated side-by-side
SPBs, which together emanate an average of six cMTs, in most cases in opposite
orientation with respect to the hyphal growth axis. Such cMT arrays explain why
many nuclei undergo short-range back and forth movements. Only occasionally do
all six cMTs orient in one direction, a precondition for long-range nuclear
bypassing. Following mitosis, daughter nuclei carry a single SPB with three
cMTs. The increased probability that all three cMTs orient in one direction
explains the high rate of nuclear bypassing observed in these nuclei. The A.
gossypii mitotic spindle was found to be structurally similar to that of
Saccharomyces cerevisiae in terms of nuclear microtubule (nMT) number, length
distribution and three-dimensional organization even though the two organisms
differ significantly in chromosome number. Our results suggest that two nMTs
attach to each kinetochore in A. gossypii and not only one nMT like in S.
cerevisiae. Ashbya gossypii grows as multinucleated and constantly elongating hyphae. Nuclei
are in continuous forward and backward motion, also move during mitosis, and
frequently bypass each other. Whereas these nuclear movements are well
documented, comparatively little is known about the density and morphology of
organelles which very likely influence these movements. To understand the
three-dimensional subcellular organization of hyphae at high resolution, we
performed large-scale electron tomography of the tip regions in A. gossypii.
Here, we present a comprehensive space-filling model in which most
membrane-limited organelles including nuclei, mitochondria, endosomes,
multivesicular bodies, vacuoles, autophagosomes, peroxisomes, and vesicles are
modeled. Nuclei revealed different morphologies and protrusions filled by the
nucleolus. Mitochondria are very abundant and form a tubular network with a
polarized spherical fraction. The organelles of the degradative pathways show a
clustered organization. By analyzing vesicle-like bodies, we identified three
size classes of electron-dense vesicles (∼200, ∼150, and ∼100 nm) homogeneously
distributed in the cytoplasm which most likely represent peroxisomes. Finally,
coated and uncoated vesicles with approximately 40-nm diameters show a polarized
distribution toward the hyphal tip with the coated vesicles preferentially
localizing at the hyphal periphery. |
What is the functionality of the Triplex R/bioconductor package? | Triplex is an R/Bioconductor package for identification and visualization of potential intramolecular triplex patterns in DNA sequences. The package provides functions that can be used to search Bioconductor genomes and other DNA sequence data for occurrence of nucleotide patterns capable of forming intramolecular triplexes (H-DNA). Functions producing 2D and 3D diagrams of the identified triplexes allow instant visualization of the search results. Leveraging the power of Biostrings and GRanges classes, the results get fully integrated into the existing Bioconductor framework, allowing their passage to other Genome visualization and annotation packages, such as GenomeGraphs, rtracklayer or Gviz. | |
Which is the molecular mechanism underlying K-ras alterations in carcinomas? | Activating point mutations most frequently in codon 12 | Mutations in the K-ras oncogene and in the p53 tumor suppressor gene are
commonly identified in sporadic cases of pancreatic adenocarcinoma. Although
these genes might serve as useful markers for early diagnosis of pancreatic
carcinoma in patients at risk for the development of this disease, familial
pancreatic carcinomas have not been studied for these mutations. We recently had
the opportunity to examine a pancreas prophylactically removed from a patient
with a strong family history of pancreatic carcinoma. This gave us the unique
opportunity to study the early events in the development of familial
adenocarcinoma of the pancreas. Histopathological examination of the pancreas
revealed multifocal papillary and nonpapillary mucinous duct hyperplasia. Seven
of these foci were microdissected and analyzed for K-ras and p53 mutations. The
K-ras mutations were detected by combined mutant-enriched polymerase chain
reaction-restriction fragment length polymorphism analysis and characterized
further by allele-specific oligonucleotide hybridization. Five of the seven duct
lesions harbored activating point mutations in codon 12 of K-ras; a G to A
transition was found in four and a G to C transversion in one. In contrast,
these lesions did not harbor detectable p53 mutations as determined by
denaturing gradient gel electrophoresis of exons 5 to 8, nor was there
overexpression of the p53 protein as determined by immunohistochemistry. These
findings suggest that mutations in K-ras represent an early event in the
pathogenesis of pancreatic carcinoma. In addition, monitoring of patients with a
strong family history of pancreatic carcinoma for K-ras mutations may identify
patients at risk for the development of invasive carcinoma. Activating K-ras mutations are found in approximately 90% of pancreatic
carcinomas and may contribute to the poor prognosis of these tumors. Because
radiotherapy is frequently used in pancreatic cancer treatment, we assessed the
contribution of oncogenic K-ras signaling to pancreatic cancer radiosensitivity.
Seven human pancreatic carcinoma lines with activated K-ras and two cell lines
with wild-type ras were used to examine clonogenic cell survival after Ras
inhibition. Ras inhibition was accomplished by small interfering RNA (siRNA)
knockdown of K-ras expression and by blocking Ras processing using a panel of
prenyltransferase inhibitors of differing specificity for the two
prenyltransferases that modify K-Ras. K-ras knockdown by siRNA or inhibition of
prenyltransferase activity resulted in radiation sensitization in vitro and in
vivo in tumors with oncogenic K-ras mutations. Inhibition of farnesyltransferase
alone was sufficient to radiosensitize most K-ras mutant tumors, although K-Ras
prenylation was not blocked. These results show that inhibition of activated
K-Ras can promote radiation killing of pancreatic carcinoma in a superadditive
manner. The finding that farnesyltransferase inhibition alone radiosensitizes
tumors with K-ras mutations implies that a farnesyltransferase
inhibitor-sensitive protein other than K-Ras may contribute to survival in the
context of mutant K-ras. Farnesyltransferase inhibitors could therefore be of
use as sensitizers for pancreatic carcinoma radiotherapy. BACKGROUND: Activating mutations in one allele of an oncogene (heterozygous
mutations) are widely believed to be sufficient for tumorigenesis. However,
mutant allele specific imbalance (MASI) has been observed in tumors and cell
lines harboring mutations of oncogenes.
METHODOLOGY/PRINCIPAL FINDINGS: We determined 1) mutational status, 2) copy
number gains (CNGs) and 3) relative ratio between mutant and wild type alleles
of KRAS, BRAF, PIK3CA and EGFR genes by direct sequencing and quantitative PCR
assay in over 400 human tumors, cell lines, and xenografts of lung, colorectal,
and pancreatic cancers. Examination of a public database indicated that
homozygous mutations of five oncogenes were frequent (20%) in 833 cell lines of
12 tumor types. Our data indicated two major forms of MASI: 1) MASI with CNG,
either complete or partial; and 2) MASI without CNG (uniparental disomy; UPD),
due to complete loss of wild type allele. MASI was a frequent event in mutant
EGFR (75%) and was due mainly to CNGs, while MASI, also frequent in mutant KRAS
(58%), was mainly due to UPD. Mutant: wild type allelic ratios at the genomic
level were precisely maintained after transcription. KRAS mutations or CNGs were
significantly associated with increased ras GTPase activity, as measured by
ELISA, and the two molecular changes were synergistic. Of 237 lung
adenocarcinoma tumors, the small number with both KRAS mutation and CNG were
associated with shortened survival.
CONCLUSIONS: MASI is frequently present in mutant EGFR and KRAS tumor cells, and
is associated with increased mutant allele transcription and gene activity. The
frequent finding of mutations, CNGs and MASI occurring together in tumor cells
indicates that these three genetic alterations, acting together, may have a
greater role in the development or maintece of the maligt phenotype than
any individual alteration. Somatic, gain-of-function mutations in ras genes were the first specific genetic
alterations identified in human cancer about 3 decades ago. Studies during the
last quarter century have characterized the Ras proteins as essential components
of signaling networks controlling cellular proliferation, differentiation, or
survival. The oncogenic mutations of the H-ras, N-ras, or K-ras genes frequently
found in human tumors are known to throw off balance the normal outcome of those
signaling pathways, thus leading to tumor development. Oncogenic mutations in a
number of other upstream or downstream components of Ras signaling pathways
(including membrane RTKs or cytosolic kinases) have been detected more recently
in association with a variety of cancers. Interestingly, the oncogenic Ras
mutations and the mutations in other components of Ras/MAPK signaling pathways
appear to be mutually exclusive events in most tumors, indicating that
deregulation of Ras-dependent signaling is the essential requirement for
tumorigenesis. In contrast to sporadic tumors, separate studies have identified
germline mutations in Ras and various other components of Ras signaling pathways
that occur in specific association with a number of different familial,
developmental syndromes frequently sharing common phenotypic
cardiofaciocutaneous features. Finally, even without being a causative force,
defective Ras signaling has been cited as a contributing factor to many other
human illnesses, including diabetes and immunological and inflammatory
disorders. We aim this review at summarizing and updating current knowledge on
the contribution of Ras mutations and altered Ras signaling to development of
various tumoral and nontumoral pathologies. |
Is microRNA(miRNA) 30 involved in post-ischemic cardiac remodeling? | Myocardial remodeling after an ischemic insult involves extracellular matrix proteins with increased fibrosis
Initial experimental data indicate that miRNA 30 decreases CTGF a key molecule in the process of fibrosis, by directly downregulating the production of CTGF | The myocardium of the failing heart undergoes a number of structural
alterations, most notably hypertrophy of cardiac myocytes and an increase in
extracellular matrix proteins, often seen as primary fibrosis. Connective tissue
growth factor (CTGF) is a key molecule in the process of fibrosis and therefore
seems an attractive therapeutic target. Regulation of CTGF expression at the
promoter level has been studied extensively, but it is unknown how CTGF
transcripts are regulated at the posttranscriptional level. Here we provide
several lines of evidence to show that CTGF is importantly regulated by 2 major
cardiac microRNAs (miRNAs), miR-133 and miR-30. First, the expression of both
miRNAs was inversely related to the amount of CTGF in 2 rodent models of heart
disease and in human pathological left ventricular hypertrophy. Second, in
cultured cardiomyocytes and fibroblasts, knockdown of these miRNAs increased
CTGF levels. Third, overexpression of miR-133 or miR-30c decreased CTGF levels,
which was accompanied by decreased production of collagens. Fourth, we show that
CTGF is a direct target of these miRNAs, because they directly interact with the
3' untranslated region of CTGF. Taken together, our results indicate that
miR-133 and miR-30 importantly limit the production of CTGF. We also provide
evidence that the decrease of these 2 miRNAs in pathological left ventricular
hypertrophy allows CTGF levels to increase, which contributes to collagen
synthesis. In conclusion, our results show that both miR-133 and miR-30 directly
downregulate CTGF, a key profibrotic protein, and thereby establish an important
role for these miRNAs in the control of structural changes in the extracellular
matrix of the myocardium. INTRODUCTION: Coronary artery disease (CAD) is still the leading cause of death
in industrialized nations. Even though revascularization strategies such as
percutaneous coronary intervention (PCI) and coronary artery bypass graft
surgery (CABG) as well as drug therapy have significantly reduced mortality,
about 30% of patients will develop chronic heart failure over time. Ischemic
heart disease and heart failure are characterized by an adverse remodeling of
the heart, featuring cardiomyocyte hypertrophy, increased fibrosis and capillary
rarification.
AREAS COVERED: Beside an assessment of current vector systems, this review
focuses on potential target genes affecting angiogenesis/arteriogenesis and
contractility. The potential of micro RNA (miRNA) modulation for the
de-repression of survival and pro-angiogenic genes is discussed. Since gene
therapy of the target region is preferable to avoid systemic contamination,
application routes are discussed.
EXPERT OPINION: miRNAs are a promising new development for successful gene
therapy, especially for acute myocardial infarction since their miRNA
antagonists are easy to apply and appear to be selectively absorbed by the
ischemic myocardial tissue. Rapid uptake and prolonged presence of known
antimirs and antagomirs support this notion. For ischemic heart disease the most
promising gene therapeutic approach seems to be the regional intravenous
application of suitable AAV vectors and vascular growth factors, providing the
full scope of angiogenesis, vessel maturation and collateral growth optionally
combined with genes enhancing contractility. Myocardial ischaemia/reperfusion (I/R)-induced remodelling generally includes
cell death (necrosis and apoptosis), myocyte hypertrophy, angiogenesis, cardiac
fibrosis, and myocardial dysfunction. It is becoming increasingly clear that
microRNAs (miRNAs or miRs), a group of highly conserved small (∼18-24
nucleotide) non-coding RNAs, fulfil specific functions in the reperfused
myocardium towards post-infarct remodelling. While miR-21, -133, -150, -195, and
-214 regulate cardiomyocyte hypertrophy, miR-1/-133 and miR-208 have been
elucidated to influence myocardial contractile function. In addition, miR-21,
-24, -133, -210, -494, and -499 appear to protect myocytes against I/R-induced
apoptosis, whereas miR-1, -29, -199a, and -320 promote apoptosis. Myocardial
fibrosis can be regulated by the miR-29 family and miR-21. Moreover, miR-126 and
miR-210 augment I/R-induced angiogenesis, but miR-24, -92a, and -320 suppress
post-infarct neoangiogenesis. In this review, we summarize the latest advances
in the identification of myocardial ischaemia-associated miRNAs and their
functional significance in the modulation of I/R-triggered remodelling.
Controversial effects of some miRNAs in post-infarct remodelling will be also
discussed. miRNAs are small non-coding RNAs that regulate post-transcriptionally gene
expression by degradation or translational repression of specific target mRNAs.
In the 90s, lin-4 and let-7 were firstly identified as small regulatory RNAs
able to control C. elegans larval development, by specifically targeting the
3'UTR of lin-14 and lin-28, respectively. These findings have introduced a novel
and wide layer of complexity in the regulation of mRNA and protein expression.
Lin-4 and let-7 are now considered the founding members of an abundant class of
small fine-tuned RNAs, called microRNAs (miRNAs), in viruses, green algae,
plants, flies, worms, and in mammals. In humans, the estimated number of genes
encoding for miRNAs is as high as 1000 and around 30% of the protein-coding
genes are post-transcriptionally controlled by miRNAs. This article reviews the
role of miRNAs in regulating several biological responses in muscle cells,
ranging from proliferation, differentiation and adaptation to stress cues.
Cardiac and skeletal muscles are powerful examples to summarize the activity of
miRNAs in cell fate specification, lineage differentiation and metabolic
pathways. Indeed, specific miRNAs control the number of proliferating muscle
progenitors to guarantee the proper formation of the heart and muscle fibers and
to assure the self-renewal of muscle progenitors during adult tissue
regeneration. On the other side, several other miRNAs promote the
differentiation of muscle progenitors into skeletal myofibers or into
cardiomyocytes, where metabolic activity, survival and remodeling process in
response to stress, injury and chronic diseases are also fine-tuned by miRNAs. |
List all clinical trials of the polypill. | 'Use of a Multidrug Pill In Reducing cardiovascular Events' (UMPIRE) trial, European Clinical Trials database, as EudraCT: 2009-016278-34 and the Clinical Trials Registry, India as CTRI/2010/091/000250.
'IMProving Adherence using Combination Therapy (IMPACT)', Australian New Zealand Clinical Trial Registry (ACTRN12606000067572).
'Kanyini Guidelines Adherence with the Polypill (Kanyini-GAP)'
Phase II study of the Polycap, double-blind, randomised trial, registered with ClinicalTrials.gov, number NCT00443794
Second Indian Polycap Study, TIPS-2
Cluster Randomized Usual Care vs Caduet Investigation Assessing Long-term-risk (CRUCIAL trial)
GEMINI trial, 14-week, open-label trial conducted in 1220 patients from the USA
GEMINI-Australia, Asia, Latin America, Africa/Middle East (AALA) study
JEWEL study program, with JEWEL 1 conducted among 1138 patients from the UK and Canada and JEWEL 2 conducted in 1107 patients from Europe
CAPABLE54, the Clinical Utility of Caduet in Simultaneously Achieving Blood Pressure and Lipid End Points , in the USA
CUSP (The Caduet® in an Untreated Subject Population trial)
TOGETHER trial
A randomised controlled trial in seven countries – Australia, Brazil, India, Netherlands , New Zealand , United Kingdom and United States. Australian New Zealand Clinical Trials Registry (ACTRN 12607000099426) | A "polypill" for the primary prevention of cardiovascular disease has been
proposed. We estimated the projected benefit of a secondary prevention
"poly-portfolio" strategy, including pharmacologic and lifestyle approaches for
those with coronary heart disease (CHD) or stroke. Based on recent clinical
trial results and clinical guidelines, combinations of a high-dose statin, low
to standard doses of antihypertensive therapy, aspirin, omega-3 fish oil,
cardiac rehabilitation, and diet were evaluated. Patients with CHD,
post-myocardial infarction (MI), or stroke were projected to experience 84%,
91%, and 77% reductions, respectively, in CHD events from a pharmacologic
approach. Numbers of those needed to treat (NNT) for 5 years were 9 to 11 to
prevent 1 CHD event, and 21 to prevent 1 stroke. Post-MI patients were projected
to experience a 93% reduction in the risk of CHD death (NNT 16) from a
pharmacologic approach and a 97% reduction in the risk of CHD death (NNT 15)
with the addition of lifestyle changes. A secondary prevention polyportfolio
holds great promise for reducing the burden of cardiovascular disease in the
highest risk patients. The reality of primary and secondary prevention of cardiovascular complications
in people with diabetes is alarming, even in developed countries with a
well-structured medical system. Even though therapeutic targets have been more
clearly defined during the last decades, their implementation is still
suboptimal. Ficial and structural reasons, insufficient information of
physicians and patients, along with a low compliance of the latter are only a
few reasons that have been incriminated. To eliminate some of these
inconveniences, attempts to standardize and simplify therapies have been made.
Treatment with aspirin and statin for every patient with diabetes has been
postulated. Some went even further, developing the concept of a "polypill," an
integrated pharmacological agent with up to six different compounds meant to
prevent cardiovascular disease in the broad population. Likewise, the idea of a
"polymeal" tries to implement healthy nutrients into the populations' lifestyle
in a standardized fashion. Our article highlights some of the advantages and
pitfalls of these concepts and reflects our point of view with regard to some
treatment aspects in people with diabetes. As part of a pro and contra
discussion, our article is arguing against the use of statins in all patients
with diabetes and especially against the indiscriminate use of a polypill. BACKGROUND: The combination of three blood-pressure-lowering drugs at low doses,
with a statin, aspirin, and folic acid (the polypill), could reduce
cardiovascular events by more than 80% in healthy individuals. We examined the
effect of the Polycap on blood pressure, lipids, heart rate, and urinary
thromboxane B2, and assessed its tolerability.
METHODS: In a double-blind trial in 50 centres in India, 2053 individuals
without cardiovascular disease, aged 45-80 years, and with one risk factor were
randomly assigned, by a central secure website, to the Polycap (n=412)
consisting of low doses of thiazide (12.5 mg), atenolol (50 mg), ramipril (5
mg), simvastatin (20 mg), and aspirin (100 mg) per day, or to eight other
groups, each with about 200 individuals, of aspirin alone, simvastatin alone,
hydrochlorthiazide alone, three combinations of the two blood-pressure-lowering
drugs, three blood-pressure-lowering drugs alone, or three
blood-pressure-lowering drugs plus aspirin. The primary outcomes were LDL for
the effect of lipids, blood pressure for antihypertensive drugs, heart rate for
the effects of atenolol, urinary 11-dehydrothromboxane B2 for the antiplatelet
effects of aspirin, and rates of discontinuation of drugs for safety. Analysis
was by intention to treat. This study is registered with ClinicalTrials.gov,
number NCT00443794.
FINDINGS: Compared with groups not receiving blood-pressure-lowering drugs, the
Polycap reduced systolic blood pressure by 7.4 mm Hg (95% CI 6.1-8.1) and
diastolic blood pressure by 5.6 mm Hg (4.7-6.4), which was similar when three
blood-pressure-lowering drugs were used, with or without aspirin. Reductions in
blood pressure increased with the number of drugs used (2.2/1.3 mm Hg with one
drug, 4.7/3.6 mm Hg with two drugs, and 6.3/4.5 mm Hg with three drugs). Polycap
reduced LDL cholesterol by 0.70 mmol/L (95% CI 0.62-0.78), which was less than
that with simvastatin alone (0.83 mmol/L, 0.72-0.93; p=0.04); both reductions
were greater than for groups without simvastatin (p<0.0001). The reductions in
heart rate with Polycap and other groups using atenolol were similar (7.0 beats
per min), and both were significantly greater than that in groups without
atenolol (p<0.0001). The reductions in 11-dehydrothromboxane B2 were similar
with the Polycap (283.1 ng/mmol creatinine, 95% CI 229.1-337.0) compared with
the three blood-pressure-lowering drugs plus aspirin (350.0 ng/mmol creatinine,
294.6-404.0), and aspirin alone (348.8 ng/mmol creatinine, 277.6-419.9) compared
with groups without aspirin. Tolerability of the Polycap was similar to that of
other treatments, with no evidence of increasing intolerability with increasing
number of active components in one pill.
INTERPRETATION: This Polycap formulation could be conveniently used to reduce
multiple risk factors and cardiovascular risk. BACKGROUND: The Polycap (polypill; aspirin [acetylsalicylic acid], ramipril,
simvastatin, atenolol, and hydrochlorothiazide) was found to be safe and
effective for reducing multiple cardiovascular risk factors in The Indian
Polycap Study (TIPS).
OBJECTIVE: We evaluated the bioavailability of each ingredient of the Polycap
and determined any drug-drug interactions relative to single component reference
preparations.
METHODS: The bioavailability of the ingredients of the Polycap (T; test) when
formulated as a single capsule was compared with that of identical capsules with
each of its ingredients administered separately (R; reference) in a five-arm,
randomized, single-dose, two-period, two-treatment, two-sequence, crossover
trial with at least a 2-week washout period in a total of 195 healthy
volunteers. Plasma concentrations of each drug and, where applicable, its active
metabolite were measured using validated liquid chromatography-tandem mass
spectrometry and ultra-performance liquid chromatography. Mean pharmacokinetic
parameters and their standard deviations were computed for each analyte.
RESULTS: Comparative bioavailability was computed and no drug-drug interactions
and no difference in comparative bioavailability were concluded for each
ingredient based on point estimates of the T/R ratio of the geometric means
falling within 80-125% for peak plasma concentration (C(max)), area under the
plasma concentration-time curve from time zero to the last measurable
concentration (AUC(t)), and AUC from time zero to infinity (AUC(infinity)). The
T/R ratio for C(max), AUC(t) and AUC(infinity) was within 80-125% for atenolol,
hydrochlorothiazide, ramipril, ramiprilat and dose-normalized salicylic acid.
However, for simvastatin, the T/R point estimates for C(max), AUC(t) and
AUC(infinity) for Ln-transformed data were significantly lower ( approximately
3-4%) than the lower bound of 80%. For its active metabolite, simvastatin acid,
these estimates were significantly higher ( approximately 25-35%) than the
higher bound of 125%. Thus, the increased bioavailability of active simvastatin
acid appeared to compensate for the loss of bioavailability of simvastatin.
CONCLUSION: The Polycap was found to be effective and safe in the previously
published TIPS trial. The present study in healthy volunteers establishes that
Polycap is safe (no serious adverse events) and well tolerated, and that there
is no indication of pharmacokinetic drug-drug interactions for any of the
ingredients, with their bioavailabilities being well preserved. BACKGROUND: There has been widespread interest in the potential of combination
cardiovascular medications containing aspirin and agents to lower blood pressure
and cholesterol ('polypills') to reduce cardiovascular disease. However, no
reliable placebo-controlled data are available on both efficacy and
tolerability.
METHODS: We conducted a randomised, double-blind placebo-controlled trial of a
polypill (containing aspirin 75 mg, lisinopril 10 mg, hydrochlorothiazide 12.5
mg and simvastatin 20 mg) in 378 individuals without an indication for any
component of the polypill, but who had an estimated 5-year cardiovascular
disease risk over 7.5%. The primary outcomes were systolic blood pressure (SBP),
LDL-cholesterol and tolerability (proportion discontinued randomised therapy) at
12 weeks follow-up.
FINDINGS: At baseline, mean BP was 134/81 mmHg and mean LDL-cholesterol was 3.7
mmol/L. Over 12 weeks, polypill treatment reduced SBP by 9.9 (95% CI: 7.7 to
12.1) mmHg and LDL-cholesterol by 0.8 (95% CI 0.6 to 0.9) mmol/L. The
discontinuation rates in the polypill group compared to placebo were 23% vs 18%
(RR 1.33, 95% CI 0.89 to 2.00, p = 0.2). There was an excess of side effects
known to the component medicines (58% vs 42%, p = 0.001), which was mostly
apparent within a few weeks, and usually did not warrant cessation of trial
treatment.
CONCLUSIONS: This polypill achieved sizeable reductions in SBP and
LDL-cholesterol but caused side effects in about 1 in 6 people. The halving in
predicted cardiovascular risk is moderately lower than previous estimates and
the side effect rate is moderately higher. Nonetheless, substantial net benefits
would be expected among patients at high risk.
TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry
ACTRN12607000099426. OBJECTIVE: Large randomized clinical trials have shown the efficacy of aspirin,
ACE (angiotensin converting enzyme) inhibitors and statins as secondary
prevention measures in patients after an acute coronary syndrome with and
without ST elevations. Therefore we aimed to determine the effect of a
combination therapy with these three drugs on 1-year mortality after acute
myocardial infarction (AMI).
METHODS: We prospectively followed 9998 survivors of acute myocardial infarction
treated with a beta-blocker for 1 year. Patients were divided into three groups
according to their therapy with aspirin, ACE inhibitors and statins: 3 drugs, 2
drugs or 0-1 drug.
RESULTS: The majority of patients (n = 6260, 62.6%) were treated with 3 drugs,
2986 (29.9%) with 2 drugs and 752 (7.5%) with 0-1 drug. In the univariate
analysis 1-year mortality was 4.9%, 9.7% and 13.6%, respectively. After
adjusting for confounding factors in the propensity score analysis the odds
ratios for 1-year mortality were significantly increased with 0-1 drug (odds
ratio 1.67, 95% CI 1.24-2.27) and with 2 drugs (odds ratio 1.54, 95% CI
1.26-1.87) in comparison with the group treated with all 3 drugs. However, in
the ACOS registry the treatment was left to the discretion of the physician.
This could lead to a selection bias, which cannot be fully eliminated by using
multiple regression analysis.
CONCLUSIONS: A combination therapy with aspirin, an ACE inhibitor and a statin
reduces 1-year mortality in patients after AMI. Therefore a polypill approach
with these three agents should be considered to increase drug compliance and
reduce mortality after acute myocardial infarction. BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death, and
principal reason for the large difference in life expectancy between indigenous
Māori and the non-indigenous population in New Zealand. CVD guidelines recommend
that people who are at high risk or who have had previous CVD should be offered
aspirin, blood pressure lowering and lipid lowering therapies. However,
prescribing and adherence rates are low and CVD events remain high.
AIM: To assess whether a medication strategy using a fixed dose combination pill
('polypill') could improve prescribing and adherence to recommended medications,
lower blood pressure and improve lipids compared with current care over 12
months.
METHODS: IMProving Adherence using Combination Therapy (IMPACT) is an open-label
randomised controlled trial comparing a once-daily polypill containing four
preventive medications with usual care. Six hundred participants who have had
previous CVD events or are at high risk of CVD will be enrolled, including 300
Māori. Participants are identified, enrolled and prescribed either the polypill
or current medications at their usual primary health care practice, with
medications (including the polypill) dispensed through local community
pharmacies. The polypill contains 75 mg aspirin, 40 mg simvastatin, 10mg
lisinopril and either 12.5mg hydrochlorothiazide or 50mg atenolol. Primary
outcomes are adherence to guidelines-recommended medications and changes in
systolic blood pressure and low density lipoprotein at 12 months. Secondary
outcomes include other lipids, medication dispensing, barriers to adherence, CVD
and other serious adverse events, quality of life and prescriber acceptability.
The trial is registered with the Australian New Zealand Clinical Trial Registry
(ACTRN12606000067572). Background Significant gaps exist between guidelines-recommended therapies for
cardiovascular disease prevention and current practice. Fixed-dose combination
pills ('polypills') potentially improve adherence to therapy. This study is a
preference study undertaken in conjunction with a clinical trial of a polypill
and seeks to examine the underlying reasons for variations in treatment
adherence to recommended therapy. Methods/design A preference study comprising:
(1) Discrete Choice Experiment for patients; and (2) qualitative study of
patients and providers. Both components will be conducted on participants in the
trial. A joint model combining the observed adherence in the clinical trial
(revealed preference) and the Discrete Choice Experiment data (stated
preference) will be estimated. Estimates will be made of the marginal effect
(importance) of each attribute on overall choice, the extent to which
respondents are prepared to trade-off one attribute for another and predicted
values of the level of adherence given a fixed set of attributes, and contextual
and socio-demographic characteristics. For the qualitative study, a thematic
analysis will be used as a means of exploring in depth the preferences and
ultimately provide important narratives on the experiences and perspectives of
individuals with regard to adherence behaviour. Ethics and dissemination Primary
ethics approval was received from Sydney South West Area Health Service Human
Research Ethics Committee (Royal Prince Alfred Hospital zone). In addition to
usual scientific forums, the findings will be reported back to the communities
involved in the studies through site-specific reports and oral presentations. Clinical guidelines now recognize the importance of a multifactorial approach to
managing cardiovascular (CV) risk. This idea was taken a step further with the
concept of the Polypill™. There are, however, considerable patent,
pharmacokinetic, pharmacodynamic, registration, and cost implications that will
need to be overcome before the Polypill™ or other single-pill combinations of CV
medications become widely available. However, a medication targeting blood
pressure (BP) and lipids provides much of the proposed benefits of the
Polypill™. A single-pill combination of the antihypertensive amlodipine besylate
and the lipid-lowering medication atorvastatin calcium (SPAA) is currently
available in many parts of the world. This review describes the rationale for
this combination therapy and the clinical trials that have demonstrated that
these two agents can be combined without the loss of efficacy for either agent
or an increase in the incidence of adverse events. The recently completed
Cluster Randomized Usual Care vs Caduet Investigation Assessing Long-term-risk
(CRUCIAL trial) is discussed in detail. CRUCIAL was a 12-month, international,
multicenter, prospective, open-label, parallel design, cluster-randomized trial,
which demonstrated that a proactive intervention strategy based on SPAA in
addition to usual care (UC) had substantial benefits on estimated CV risk, BP,
and lipids over continued UC alone. Adherence with antihypertensive and
lipid-lowering therapies outside of the controlled environment of clinical
trials is very low (~30%-40% at 12 months). Observational studies have
demonstrated that improving adherence to lipid-lowering and antihypertensive
medications may reduce CV events. One means of improving adherence is the use of
single-pill combinations. Real-world observational studies have demonstrated
that patients are more adherent to SPAA than co-administered antihypertensive
and lipid-lowering therapy, and this improved adherence translated to reduced CV
events. Taken together, these findings suggest that SPAA can play an important
role in helping physicians improve the management of CV risk in their patients. |
What is transvection? | An unusual feature of the Diptera is that homologous chromosomes are intimately synapsed in somatic cells. At a number of loci in Drosophila, this pairing can significantly influence gene expression. Such influences were first detected within the bithorax complex (BX-C) by E.B. Lewis, who coined the term transvection to describe them. Most cases of transvection involve the action of enhancers in trans. At several loci deletion of the promoter greatly increases this action in trans, suggesting that enhancers are normally tethered in cis by the promoter region. Transvection can also occur by the action of silencers in trans or by the spreading of position effect variegation from rearrangements having heterochromatic breakpoints to paired unrearranged chromosomes. Although not demonstrated, other cases of transvection may involve the production of joint RNAs by trans-splicing. Several cases of transvection require Zeste, a DNA-binding protein that is thought to facilitate homolog interactions by self-aggregation. Genes showing transvection can differ greatly in their response to pairing disruption. In several cases, transvection appears to require intimate synapsis of homologs. However, in at least one case (transvection of the iab-5,6,7 region of the BX-C), transvection is independent of synapsis within and surrounding the interacting gene. The latter example suggests that transvection could well occur in organisms that lack somatic pairing. In support of this, transvection-like phenomena have been described in a number of different organisms, including plants, fungi, and mammals. | Numerous genes contain regulatory elements located many tens of kilobases away
from the promoter they control. Specific mechanisms must be required to ensure
that such distant elements can find and interact with their proper targets but
not with extraneous genes. This review explores the connections between
transvection phenomena, the activation of domains of homeotic gene expression,
position effect variegation and silencers. These various examples of
long-distance effects suggest that, in all cases, related forms of chromatin
packaging may be involved. Enhancers have been defined operationally as cis-regulatory sequences that can
stimulate transcription of RNA polymerase-II-transcribed genes over large
distances and even when located downstream of the gene. Recently, it has become
evident that enhancers can also stimulate transcription in trans if they are
brought into close proximity to the promoter/gene. These reports provide clues
to the mechanism of remote enhancer action. In addition, the findings, together
with genetic studies in Drosophila, strongly suggest that enhancer action in
trans could underlie phenomena such as 'transvection', where one chromosome
affects gene expression in the paired homolog. The zeste locus of Drosophila melanogaster encodes a DNA-binding protein that
can influence transcription. A number of sites recognized by this protein fall
within genes associated with transvection, a phenomenon suggesting a form of
gene regulation that is responsive to the proximity of a gene to its homologous
allele on another chromosome. These recent observations continue a history of
studies concerning zeste and transvection which has inspired molecular models
linking chromosome structure and positioning to the modulation of gene
expression. Knowledge of fungal chromosome rearrangements comes primarily from N. crassa,
but important information has also been obtained from A. nidulans and S.
macrospora. Rearrangements have been identified in other Sordaria species and in
Cochliobolus, Coprinus, Magnaporthe, Podospora, and Ustilago. In Neurospora,
heterozygosity for most chromosome rearrangements is signaled by the appearance
of unpigmented deficiency ascospores, with frequencies and ascus types that are
characteristic of the type of rearrangement. Summary information is provided on
each of 355 rearrangements analyzed in N. crassa. These include 262 reciprocal
translocations, 31 insertional translocations, 27 quasiterminal translocations,
6 pericentric inversions, 1 intrachromosomal transposition, and numerous complex
or cryptic rearrangements. Breakpoints are distributed more or less randomly
among the seven chromosomes. Sixty of the rearrangements have readily detected
mutant phenotypes, of which half are allelic with known genes. Constitutive
mutations at certain positively regulated loci involve rearrangements having one
breakpoint in an upstream regulatory region. Of 11 rearrangements that have one
breakpoint in or near the NOR, most appear genetically to be terminal but are in
fact physically reciprocal. Partial diploid strains can be obtained as
recombit progeny from crosses heterozygous for insertional or quasiterminal
rearrangements. Duplications produced in this way precisely define segments that
cover more than two thirds of the genome. Duplication-producing rearrangements
have many uses, including precise genetic mapping by duplication coverage and
alignment of physical and genetic maps. Typically, fertility is greatly reduced
in crosses parented by a duplication strain. The finding that genes within the
duplicated segment have undergone RIP mutation in some of the surviving progeny
suggests that RIP may be responsible for the infertility. Meiotically generated
recessive-lethal segmental deficiencies can be rescued in heterokaryons. New
rearrangements are found in 10% or more of strains in which transforming DNA has
been stably integrated. Electrophoretic separation of rearranged chromosomal
DNAs has found useful applications. Synaptic adjustment occurs in inversion
heterozygotes, leading progressively to nonhomologous association of
synaptonemal complex lateral elements, transforming loop pairing into linear
pairing. Transvection has been demonstrated in Neurospora. Beginnings have been
made in constructing effective balancers. Experience has increased our
understanding of several phenomena that may complicate analysis. With some
rearrangements, nondisjunction of centromeres from reciprocal translocation
quadrivalents results in 3:1 segregation and produces asci with four deficiency
ascospores that occupy diagnostic positions in linear asci. Three-to-one
segregation is most frequent when breakpoints are near centromeres. With some
rearrangements, inviable deficiency ascospores become pigmented. Diagnosis must
then depend on ascospore viability. In crosses between highly inbred strains,
analysis may be handicapped by random ascospore abortion. This is minimized by
using noninbred strains as testers. Pairing-dependent interallelic complementation was first described for the
Ultrabithorax gene of the bithorax-complex in Drosophila by Lewis and cited as
an example of a new phenomenon that Lewis called the "trans-vection effect."
Several different kinds of pairing-dependent gene expression have been observed
in Drosophila, and it is now clear that a variety of different molecular
mechanisms probably underlie the changes in gene expression that are observed
after disrupting chromosome pairing. Transvection in the bithorax-complex
appears to result from the ability of cis-regulatory elements to regulate
transcription of the promoter on the homologous chromosome. The same phenomenon
appears to be responsible for pairing-dependent interallelic complementation at
numerous other genes in Drosophila. Some transvection effects are dependent on
the presence of wild-type or specific mutant forms of the protein encoded by the
zeste trans-regulatory gene, but other transvection effects are
zeste-independent. The ease with which chromosome aberrations can disrupt
transvection also varies widely among different genes. |
What is the role of probiotics in gastrointestinal disease? | Probiotics are live, microbial food supplements that benefit the host animal by improving intestinal microbial balance. Across all 11 probiotic species and eight different gastrointestinal diseases - Irritable Bowel Syndrome (IBS), Helicobacter pylori infection (HPP), Necrotizing Enterocolitis (NEC), Pouchitis (Pouch), Antibiotic Associated diarrhea (AAD), Clostridium difficile Disease (CDD), Infectious diarrhea (ID), and Travellers diarrhea (TD) - probiotics have been shown to have effect on prevention and treatment of gastrointestinal disease through enhancing the immune response, protection against abnormal invasive bacteria. Probiotics have a role in all age groups, incl. infants. | Probiotics are live, microbial food supplements that benefit the host animal by
improving intestinal microbial balance. Their major role in preventing and
treating gastrointestinal disease appears to be from their effect on the immune
process, protection against abnormal invasive bacteria, and in the production of
short-chain fatty acids from starch and non-starch polysaccharides. Probiotic
microorganisms are administered in food supplements and yogurts. They are also
now sold in the form of capsules and powders. There is great variation in the
microorganisms in the various supplements. It is important to understand that
all probiotic products are different. Some contain a single organism and others
contain multiple organisms. Therapeutic results have been achieved with various
probiotics in different diseases. In the treatment of inflammatory bowel
diseases (IBD), success has been reported with Escherichia coli Nissle strain in
ulcerative colitis, and with a multiple organism product, VSL#3 (VSL
Pharmaceuticals, Fort Lauderdale, FL), in Crohn's disease and pouchitis. Initial
reports in irritable bowel syndrome (IBS) have resulted in encouraging results
with the use of E. coli Nissle strain, and recently with multiple organism
probiotic supplements. However, caution must still apply to the use of
probiotics in IBD and IBS because the reports and the number of patients treated
are limited. OBJECTIVES: Probiotics may be useful in preventing acute infectious diarrhea.
Bifidobacteria are particularly attractive as probiotics agent because they
constitute the predomit colonic flora of breastfed infants and are thought to
play a role in the decreased incidence of diarrhea in breastfed infants.
METHODS: This was a multicenter, double-blind, controlled study to evaluate the
efficacy of a milk formula supplemented with viable Bifidobacterium lactis
strain Bb 12 (BbF) in the prevention of acute diarrhea in infants younger than 8
months living in residential nurseries or foster care centers.
RESULTS: Ninety healthy children received either the BbF or a conventional
formula (CF) daily. The mean duration of the stay in the residential center was
similar (137 v 148 days). At enrollment, there were no differences between the
two groups with respect to age (3.7 +/- 2.1 months), gender, anthropometric
data, history of allergy or gastrointestinal disease, frequency of
breast-feeding in the neonatal period or timing of introduction of solid food.
Altogether, 28.3% of the BbF infants had diarrhea during the study compared with
38.7% of controls (NS). There was a statistically insignificant trend for
shorter episodes of diarrhea in the BbF group (5.1 +/- 3.3 days v 7 +/- 5.5
days, NS). The number of days with diarrhea was 1.15 +/- 2.5 in the BbF group
with a daily probability of diarrhea of 0.84 versus 2.3 +/- 4.5 days and 1.55,
respectively, in the CF group (P = 0.0002 and 0.0014). Feeding infants with the
BbF reduced their risk of getting diarrhea by a factor of 1.9 (range, 1.33-2.6).
Analysis of the cumulative incidence of diarrheal episodes showed a trend that
the first onset of diarrhea occurred later in the BbF group.
CONCLUSION: These results provide some evidence that viable Bifidobacterium
lactis strain Bb 12, added to an acidified infant formula, has some protective
effect against acute diarrhea in healthy children. Gastrointestinal disease is a major cause of morbidity and mortality worldwide
each year. Treatment of chronic inflammatory gastrointestinal conditions such as
ulcerative colitis and Crohn's disease is difficult due to the ambiguity
surrounding their precise aetiology. Infectious gastrointestinal diseases, such
as various types of diarrheal disease are also becoming increasingly difficult
to treat due to the increasing dissemination of antibiotic resistance among
microorganisms and the emergence of the so-called 'superbugs'. Taking into
consideration these problems, the need for novel therapeutics is essential.
Although described for over a century probiotics have only been extensively
researched in recent years. Their use in the treatment and prevention of
disease, particularly gastrointestinal disease, has yielded many successful
results, some of which we outline in this review. Although promising, many
probiotics are hindered by inherent physiological and technological weaknesses
and often the most clinically promising strains are unusable. Consequently we
discuss various strategies whereby probiotics may be engineered to create
designer probiotics. Such innovative approaches include; a receptor mimicry
strategy to create probiotics that target specific pathogens and toxins, a
patho-biotechnology approach using pathogen-derived genes to create more robust
probiotic stains with increased host and processing-associated stress tolerance
profiles and meta-biotechnology, whereby, functional metagenomics may be used to
identify novel genes from diverse and vastly unexplored environments, such as
the human gut, for use in biotechnology and medicine. GOALS: The objective of this study was to determine how gastroenterologists
perceive and use probiotic-based therapies in practice.
BACKGROUND: In the United States, there has been a recent increase in research
investigating the therapeutic capacities of probiotics in human disease and an
accompanying increase in product availability and marketing. How medical care
providers have interpreted the available literature and incorporated it into
their practice has not been earlier assessed.
STUDY: A 16-question survey (see Survey, Supplemental Digital Content 1,
http://links.lww.com/JCG/A14) was distributed to practicing gastroenterologists
and physicians with a specific interest in GI disorders within a large
metropolitan area.
RESULTS: All physicians responded that they believed probiotics to be safe for
most patients and 98% responded that probiotics have a role in treating
gastrointestinal illnesses or symptoms. Currently 93% of physicians have
patients taking probiotics most often for irritable bowel syndrome. Commonly
used probiotics included yogurt-based products, Bifidobacterium infantis 35624
(Align), and VSL#3. Most surveyed physicians recommended probiotics for
irritable bowel syndrome, antibiotic, and Clostridium difficile-associated
diarrhea because they believed that the literature supports their usage for
these conditions. However, physician practice patterns did not consistently
correlate with published, expert-panel-generated recommendations for
evidence-based probiotic use.
CONCLUSIONS: This study suggests most gastrointestinal disease specialists
recognize a role for and have used probiotics as part of their therapeutic
armamentarium; however, the effective implementation of this practice will
benefit from additional supporting studies and the eventual development of
clinical practice guidelines supported by the major gastroenterology societies. Our intestinal microbiota serve many roles vital to the normal daily function of
the human gastrointestinal tract. Many probiotics are derived from our
intestinal bacteria, and have been shown to provide clinical benefit in a
variety of gastrointestinal conditions. Current evidence indicates that
probiotic effects are strain-specific, they do not act through the same
mechanisms, and nor are all probiotics indicated for the same health conditions.
However, they do share several common features in that they exert
anti-inflammatory effects, they employ different strategies to antagonize
competing microorganisms, and they induce cytoprotective changes in the host
either through enhancement of barrier function, or through the upregulation of
cytoprotective host proteins. In this review we focus on a few selected
probiotics - a bacterial mixture (VSL#3), a Gram-negative probiotic (E. coli
Nissle 1917), two Gram-positive probiotic bacteria (LGG, L. reuteri), and a
yeast probiotic (S. boulardii) - for which sound clinical and mechanistic data
is available. Safety of probiotic formulations is also discussed. Intestinal bacterial colonisation in pre-term infants is delayed compared with
full-term infants, leading to an increased risk of gastrointestinal disease.
Modulation of colonisation through dietary supplementation with probiotics or
prebiotics could decrease such a risk. The present study evaluated clinical
tolerance, the effects on gut microbiota, and inflammatory and immunological
mucosal responses to an infant formula adapted for pre-term infants that
included in its manufacturing process a fermentation step with two probiotic
strains, Bifidobacterium breve C50 and Streptococcus thermophilus 065,
inactivated by heat at the end of the process. A total of fifty-eight infants
(gestational age: 30-35 weeks), fed either the fermented pre-term formula or a
standard pre-term formula, were followed up during their hospital stay. Clinical
tolerance, faecal microbiota using a culture and a culture-independent method
(temporal temperature gel electrophoresis), faecal calprotectin and secretory
IgA were analysed weekly. No difference was observed regarding anthropometric
data and digestive tolerance, except for abdominal distension, the incidence of
which was lower in infants fed the fermented formula for 2 weeks. Bacterial
colonisation was not modified by the type of feeding, particularly for
bifidobacteria. Faecal calprotectin was significantly lower in infants fed the
fermented formula for 2 weeks, and secretory IgA increased with both mother's
milk and the fermented formula. The fermented formula was well tolerated and did
not significantly modulate the bacterial colonisation but had benefits on
inflammatory and immune markers, which might be related to some features of
gastrointestinal tolerance. |
What is the main symptom of Marfan syndrome patients? | The diagnosis and surgical treatment of patients with Marfan syndrome remain controversial. Pathohistological alterations of the aorta in patients with Marfan syndrome consisted in pronounced restructuring of the wall with deep irreversible alternative changes. The risk of aortic dissection, which is the most serious manifestation of the Marfan syndrome, increases as the aorta enlarges. Surgical replacement of the aortic root with a composite graft does not end the disease process. | For the first time Bernhard Marfan described the Marfan-Syndrome in 1896; it is
a meso- and ectodermed variety with the conducting symptom of "arachnodactyly".
Marfan-Syndrome is an autosomal domit hereditary disorder with high
penetrance and variable expressivity. In our opinion this case of a 41-year-old
patient with kidney cysts and aneurysma dissecans of the arteria ascendens by
Marfan-Syndrome was described in the literature only twice. The casuistics of
this Marfan-Syndrome patient shows a particular rare associated
organ-change--the kidney cysts--and illustrate the frequency of this hereditary
disease. Imaging and color flow Doppler echocardiography are an integral part of any
evaluation of a patient with the Marfan syndrome. The major cardiovascular
manifestations of this condition are aortic dilation, which may involve the
proximal and distal aorta, aortic regurgitation, aortic dissection, mitral valve
prolapse, and mitral regurgitation. Patients who have the Marfan syndrome should
have serial echocardiograms to measure aortic root diameter carefully at the
sinuses of Valsalva and subsequent levels (sinotubular junction, arch,
descending and abdominal aorta). Additionally, color Doppler echocardiography
assists in the diagnosis of aortic dissection and facilitates evaluation of the
severity of aortic and mitral regurgitation that commonly complicate the Marfan
syndrome. The risk of aortic dissection, which is the most serious manifestation
of the Marfan syndrome, increases as the aorta enlarges. Therefore, elective
composite graft surgery is recommended when the aortic root size reaches 60 mm,
regardless of symptom status, or 55 mm in the presence of severe aortic
regurgitation. Surgical replacement of the aortic root with a composite graft
does not end the disease process. Color flow Doppler is useful in the diagnosis
of dehiscence of the conduit sewing ring, coronary artery aneurysm, distal
aortic dissections, and prosthetic valve dysfunction. BACKGROUND: Cardiovascular disease is the main cause of morbidity and mortality
in patients with Marfan syndrome. Many patients with presumed Marfan syndrome do
not meet current diagnostic criteria. This study reviews the surgical aspects of
aortic disease in 300 patients referred with the diagnosis of Marfan syndrome.
METHODS: During a 16-year period, 300 patients with presumed Marfan syndrome
underwent 398 operations on the aorta and branch arteries, including 125 aortic
root operations, 59 aortic arch repairs, 31 descending thoracic aortic repairs,
and 178 thoracoabdominal aortic repairs. Based on medical record review,
patients were classified as confirmed Marfan syndrome if documented features
satisfied current diagnostic criteria; patients not meeting these criteria were
classified as suspected Marfan syndrome.
RESULTS: There were 17 operative deaths (4.3%) after the 398 operations.
Survival after the initial referral operation was 96.2% +/- 1.5% at 1 year,
82.7% +/- 2.4% at 5 years, and 74.6% +/- 3.1% at 10 years. Presentations,
operative details, and outcomes were remarkably similar in the 137 patients
(45.7%) with confirmed Marfan syndrome and the 163 patients (54.3%) with
suspected Marfan syndrome. Freedom from repair failure, however, was
significantly better in patients with confirmed Marfan syndrome (90.3% +/- 2.3%
at 10 years) than in those with suspected Marfan syndrome (82.0% +/- 3.1% at 10
years; p = 0.001).
CONCLUSIONS: Operative treatment of the full spectrum of aortic disease in
Marfan patients enables excellent long-term survival. Similarities in surgical
aspects of aortic disease suggest that patients with features of Marfan syndrome
who do not meet diagnostic criteria should be managed in the same manner as
patients with confirmed Marfan syndrome. This report describes successful treatment of an unusual case of concomitant
paraplegia and type 1 endoleak during the early postoperative course of
endovascular therapy of type B dissection in a patient with Marfan syndrome. PURPOSE: Aortic dissection (AoD) is one of the most common catastrophes
involving the aorta. Nevertheless, early diagnosis remains to be a challenge in
the Emergency Department (ED), particularly in young individuals. In this study,
we attempted to identify the characteristics of acute AoD among young
individuals, particular in patients with Marfan syndrome.
MATERIALS AND METHODS: This was an retrospective chart-review study conducted in
a tertiary referring hospital. The hospital database was queried for the
combination of AoD and patients under age of 40 years. The medical charts were
reviewed to obtain demographic data, clinical data and laboratory
characteristics by using a standardized data collection sheet. A comparison
between Marfan syndrome and non-Marfan syndrome patients was performed.
RESULTS: During the 10-years period, 18 of 344 patients with acute AoD were
younger than 40 years-old. Patients with Marfan syndrome developed acute AoD at
a younger age than patients without Marfan syndrome. The mean diastolic blood
pressure was significantly lower in patients with Marfan syndrome upon
presenting to the ED than those without. Patients with Marfan syndrome had
trends toward higher risk of development of type A AoD, increased recurrence
rate and higher mortality rate than those without. However, statistical
significance was not present.
CONCLUSION: ED physicians should have high alert to acute AoD in young patients
presenting with severe unexplained chest and back pain, particularly in those
patients with a history of heart diseases, hypertension, and Marfan syndrome or
featuring Marfanoid habitus. Acute coronary syndrome, unexplained abdominal
symptoms, and sudden cardiac arrest could be the initial manifestation of AoD in
young patients. A low threshold to perform enhanced computed tomography may
facilitate early diagnosis and timely treatment in this patient population. BACKGROUND: Marfan syndrome (MFS) is one of the most common systemic disorders
of connective tissue with the incidence of approximately 2-3 per 10 000
individuals. Aortic disease, leading to progressive aneurysmal dilatation and
dissection is the main cause of morbidity and mortality of Marfan patients.
Current treatment (e.g. beta blockers and elective surgery) does postpone but
cannot prevent aortic complications in these patients. Recent studies have found
transforming growth factor beta (TGF beta) to be involved in the aortic aneurysm
formation. Losartan, an angiotensin II type 1 receptor blocker inhibits TGFbeta
in a mouse model of Marfan syndrome leading to inhibition of aortic growth. The
main objective of this trial is to assess whether losartan treatment leads to a
clinically relevant decrease of aortic dilatation in adult patients with Marfan
syndrome.
METHODS/DESIGN: COMPARE study (COzaar in Marfan Patients Reduces aortic
Enlargement) is an open-label, randomized, controlled trial with blinded
end-points. Treatment with losartan will be compared with no additional
treatment after 3 years of follow-up. We will enroll 330 patients with MFS who
will be randomly assigned to receive losartan or not. Patients taking
beta-blockers will continue taking their standard treatment. The primary
end-point is the largest change in aortic diameter at any aortic level measured
by means of MRI. Secondary end-points are change in mortality, incidence of
dissection, elective aortic surgery, aortic volume, aortic stiffness and
ventricular function. We will also investigate gene and protein expression
change in the skin under losartan therapy and create prediction models for
losartan-treatment response and aortic dilatation.
DISCUSSION: The COMPARE study will provide important evidence of effects of
losartan treatment in adult Marfan patient population. We expect losartan to
significantly reduce the occurrence and progression of aortic dilatation. This
trial investigates a wide spectrum of clinical, genetic and biochemical effects
of losartan aiming to provide further insight in the pathogenesis and treatment
of Marfan syndrome.
TRIAL REGISTRATION: Netherlands Trial Register NTR1423. INTRODUCTION: Stanford type A aortic dissection is a rare phenomenon with high
short-term mortality and clinical manifestations that can make differential
diagnosis a lengthy process requiring several diagnostic examinations.
OBJECTIVES: Based on a case report, the aim is to highlight the importance of
physical examination in the initial management of these patients and of rapid
access to a surgical center. A brief review follows on the diagnosis and
treatment of ascending aortic dissection, and its specific nature in Marfan
syndrome.
CASE REPORT: A 33-year-old man was admitted to the emergency department of a
district hospital with chest and back pain associated with vomiting, 20 hours
after symptom onset. Initial physical examination revealed an aortic systolic
murmur and musculoskeletal morphological abnormalities compatible with Marfan
syndrome. Given suspected aortic dissection, a transthoracic echocardiogram was
immediately performed, which showed an extensive intimal flap originating at the
sinotubular junction. He was transferred to the cardiothoracic surgery
department of a referral hospital where he was treated by a Bentall procedure.
CONCLUSION: In this case, careful physical examination during initial assessment
raised the suspicion that this patient was in a high-risk group for aortic
dissection, thus avoiding unnecessary and lengthy exams. This diagnosis requires
emergent surgical treatment, and so direct contact in real time between those
making in the diagnosis and the surgeon is essential, as well as protocols
governing immediate access to a surgical center. PURPOSE: To assess the reproducibility of aortic volume estimates and to
serially test their use in patients with Marfan syndrome.
MATERIALS AND METHODS: The study was approved by the medical ethics committee
and all subjects gave written informed consent. In 81 patients with Marfan
syndrome and seven healthy control subjects, aortic volumes and diameters at
baseline were estimated by means of contrast material-enhanced magnetic
resoce (MR) imaging. At 3 years of follow-up, aortic expansion rate were
calculated in a subgroup of 22 patients with Marfan syndrome. Total aortic
volume was defined as volume measurement from the level of the aortic annulus to
the aortic bifurcation. Intra- and interobserver agreement of aortic volume were
calculated by using the intraclass correlation coefficient. Differences in
variables were analyzed with the Student t test and logistic regression. Effect
size was calculated.
RESULTS: Intra- and interobserver agreement of aortic volume calculation was
0.996 and 0.980, respectively. Mean aortic volume was significantly greater in
patients with Marfan syndrome than in control subjects (104 mL/m(2); 95%
confidence interval [CI]: 95, 114 mL/m(2) vs 74 mL/m(2); 95% CI: 62, 87 mL/m(2);
P < .001). In 22 patients with Marfan syndrome, mean aortic volume was increased
at 3 years of follow-up (17 mL; 95% CI: 8, 26 mL; P = .001; effect size, 0.29),
while mean aortic diameter did not increase significantly (0.4 mm; 95% CI: 0.0,
0.9 mm; P = .171; effect size, 0.13).
CONCLUSION: Assessment of aortic volume is highly reproducible and may be suited
for use in the detection of aortic expansion in patients with Marfan syndrome.
SUPPLEMENTAL MATERIAL:
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122310/-/DC1. BACKGROUND: The diagnosis and surgical treatment of patients with Marfan
syndrome remain controversial. It is of utmost importance to identify patients
at risk for acute aortic events to establish the correct surgical timing and the
appropriate surgical treatment.
METHODS: From May 2008 to December 2012, 500 patients were screened at the
Marfan Presidium of the Tor Vergata University Hospital of Rome (Italy).
Patients were evaluated by a cardiac surgeon, including echocardiographic,
orthopedic, ophthalmologic and dental examinations. All patients received
genetic counseling, and genetic sampling was performed if appropriate.
RESULTS: The diagnosis of Marfan syndrome was confirmed in 146 patients (29.2%).
Fifty-four patients (37%) underwent cardiac surgery on the aortic root, 4
patients had surgery on the mitral valve, 13 patients had combined surgery; 11
cases were emergent surgery for acute aortic dissection. Twenty-eight patients
(52%) were operated on at our Division: 13 underwent valve-sparing aortic root
replacement (David procedure), 1 underwent Yacoub remodeling procedure and 14
underwent Bentall procedure. Following the establishment of the Marfan Center,
the David aortic valve-sparing operation was the most frequently performed
procedure compared to the previous period of surgical activity (63 vs 22%,
p<0.0001).
CONCLUSIONS: Regular follow-up twice a year may allow to identify patients at
risk for acute aortic syndromes. Early surgical treatment is recommended in
these patients to achieve optimal results of valve-sparing procedures and
life-saving management, especially for patients who live far away from a cardiac
surgery center. CONTEXT: Meningeal abnormalities such as dural ectasia are seen in Marfan
syndrome, but spinal meningeal cysts are rarely seen. These cysts usually
asymptomatic and often found incidentally on magnetic resoce imaging, large
cysts may cause neurological deficits and pain secondary to nerve root
compression.
DESIGN: Case reports.
FINDINGS: Two patients with Marfan syndrome presented with urinary symptoms
secondary to dural ectasia and sacral cysts. Patient 1 had a history of low back
pain, erectile dysfunction, and occasional urinary incontinence and groin pain
with recent symptom worsening. He underwent L5 partial laminectomy and S1-S2
laminectomy with sacral cyst decompression. Nine weeks later, he underwent
drainage of a sacral pseudomeningocele. Pain and urinary symptoms resolved, and
he remains neurologically normal 2 years after surgery. Patient 2 presented
after a fall on his tailbone, complaining of low back pain and difficulty
urinating. Physical therapy was implemented, but after 4 weeks, urinary
retention had not improved. He then underwent resection of the sacral cyst and
S1-S3 laminectomy. Pain and paresthesias resolved and bowel function returned to
normal. Other than needing intermittent self-catheterization, all other
neurologic findings were normal 30 months after surgery.
CONCLUSION/CLINICAL RELEVANCE: Surgical goals for sacral cysts include resection
as well as closure of the dura, which can be challenging due to thinning from
ectasia. Neurosurgical intervention in Marfan syndrome is associated with a high
risk of dural tears and osseous complications, and should be performed only when
symptoms are severe. OBJECTIVE: To compare the clinical features of type A aortic dissection (AAD) in
patients with Marfan syndrome (MFS) and bicuspid aortic valves (BAV).
METHODS: Data from patients undergoing surgery for acute AAD between April 2008
and April 2012 at our institute were retrospectively collected. Patients were
categorized into MFS group (n = 39) and BAV group (n = 28) to investigate their
clinical and prognostic features.
RESULTS: Patients in MFS and BAV groups always experienced the sudden onset of
chest pain. MFS patients tended to have younger age [(35 ± 8) y vs (47 ± 13) y,
P < 0.001], wider aortic sinus [(55.4 ± 9.8) mm vs (42.6 ± 8.6) mm, P < 0.01]
and higher rate of moderate-to-severe aortic regurgitation (69.2% vs 32.1%, P =
0.003). Patients in BAV group were featured with higher rate of
moderate-to-severe aortic stenosis. Though the operation procedures were similar
in both groups, the 30-day postoperative mortality was significantly higher
among BAV patients (25.0% vs 5.1%, P = 0.020).
CONCLUSIONS: MFS and BAV represent unique subgroups of acute type A aortic
dissection. BAV-associated dissection demonstrated strikingly higher
postoperative mortality in our study population. The authors examined the state of patients suffering from Marfan syndrome (MS)
who endured operation for ascending aorta aneurysm with replacement of the
ascending aorta and aortic valve (Bentall operation), studying alterations of
the skeleton, face, heart and eyes, as well as pathomorphological restructurings
in the aortic wall. The study was carried out 7.0 ± 4.2 years after the
operation. We examined a total of 39 patients with MS - 27 (69.2%) men and 12
(30.8%) women aged from 22 to 70 years old (average age - 42.1 ± 13.4 years).
All patients were operated on for dissecting aneurysm of the ascending aorta
accompanied by a considerable degree of aortic valve insufficiency or aortic
ostium stenosis. The mean diameter of the aorta at the level of the sinuses of
Valsalva amounted to 7.0 ± 1.3 cm (minimal - 5.0 cm, maximal - 12.0 cm), the
Z-score prior to operation was 12.7 ± 6.5. The time form making the diagnosis of
MS to surgical intervention for aortic aneurysm amounted to 9.6 ± 5.9 years. The
condition after operative treatment in all patients was satisfactory, with the
haemodynamic indices stable: systolic AP - 133.5 ± 19.1 mm Hg, diastolic AP 85.1
± 12.9 mm Hg, heart rate 74.8 ± 7.2 bpm. The average systemic score for the
symptoms and tests of MS patients amounted to 8.2 ± 3.3 points.
Pathohistological alterations of the aorta in patients with Marfan syndrome
consisted in pronounced restructuring of the wall with deep irreversible
alternative changes. The pathological process extended in the middle aortic
layer all alone the length, but not only in the portions of rupture and
dissection. The main pathomorphological signs in MS were as follows: focal
accumulations of mucoid substances, dystrophic alterations of smooth-muscle
cells, ribbon-like anuclear zones, formation of cystlike cavities, alterations
of elastic fibres - fragmentation, hyperelastosis, multiplication, thinning and
straightening, zones of elastolysis. |
What species is associated with Tetrodotoxin? | Tetrodotoxin (TTX) is a low molecular weight (approximately 319 Da) neurotoxin found in a number of animal species, including pufferfish. TTX is originally produced by marine bacteria, and pufferfish are intoxicated through the food chain that starts with the bacteria. TTX is found in warm waters, especially of the Indian and Pacific Oceans. TTX poisoning due to marine snails has recently spread through Japan, China, Taiwan, and Europe. | Tetrodotoxin (TTX) and its deoxy analogs, 5-deoxyTTX, 11-deoxyTTX,
6,11-dideoxyTTX, and 5,6,11-trideoxyTTX, were quantified in the tissues of three
female and three male specimens of the marine puffer fish, Fugu niphobles, from
the southern coast of Korea, and in the whole body of the brackishwater puffer
fishes, Tetraodon nigroviridis (12 specimens) and Tetrodon biocellatus (three
specimens) from Southeast Asia using LC/MS in single ion mode (SIM).
Identification of these four deoxy analogs in the ovarian tissue of F. niphobles
were further confirmed by LC/MS/MS. TTX and 5,6,11-trideoxyTTX were detected in
all three puffer fish species as the major TTX analogs, similar to Japanese Fugu
pardalis. While 6,11-dideoxyTTX was also found to be a major analog in almost
all tissues of Korean F. niphobles, this analog was minor in the two Tetraodon
species and Japanese F. pardalis. Among the tissues of F. niphobles, the
concentrations of TTXs were highest in the ovaries (female) and skin (female and
male). The inhibitory effects of toxin extracted from muscle or liver of five different
puffer fishes (hereafter referred as puffer(s)) captured on the Japanese sea
coast were examined on voltage-dependent sodium current (I(Na)) recorded from
dissociated single rat hippocampal CA1 neurons. The inhibitory effects estimated
from IC(50) values of toxin extracts on I(Na) were in the order of Takifugu
vermicularis > Lagocephalus wheeleri > Canthigaster rivulata > Takifugu rubripes
> Arothron reticularis from muscle and T. vermicularis > T. rubripes > L.
wheeleri > A. reticularis > C. rivulata from liver, thereby indicating that the
amount of toxin in the liver or muscle differs between puffers. In addition, the
present results indicate that the muscle of T. vermicularis, which is eaten in
Japan, contains relatively higher amounts of toxin compared to those of T.
rubripes, also eaten. This observation suggests that caution should be taken
concerning the maximal edible amount of muscle prepared from T. rubripes. Suspected tetrodotoxin (TTX) poisoning was associated with eating unknown fish
in April 2009 in Taiwan. After ingestion of the fish, symptoms of the victim
included perioral paresthesia, nausea, vomiting, ataxia, weakness of all limbs,
respiration failure, and death within several hours. The toxicity in the
remaining fish was determined, with the mice exhibiting symptoms of neurotoxin
poisoning. The implicated fish and deceased victim tissues were analyzed for TTX
by liquid chromatography-tandem mass spectrometry. The urine, bile,
cerebrospinal fluid (spinal cord), pleural effusion, and pericardial effusion of
the victim contained TTX. In addition, the partial cytochrome b gene of the
implicated fish was determined by PCR. The DNA sequence in the partial 465-bp
cytochrome b gene identified the implicated fish as Chelonodon patoca (puffer
fish). These results indicate that people should avoid eating unknown fish
species from fish markets where harvested fish may include toxic species. Green toadfish Lagocephalus lunaris inhabits tropical and subtropical seas and
contains high tetrodotoxin (TTX) levels in the muscle as well as liver and
gonad. In 2008 to 2009, food poisoning due to ingesting L. lunais occurred in
Western Japan. Five specimens of green toadfish caught in Kyushu coast, Japan,
were analyzed for toxicity, toxins, and species identification. All five
specimens were toxic by bioassay. Comparing the maximum toxicity in tissues,
ovary contained the most toxin (1810 mouse unit [MU]/g), followed by liver
(341 MU/g), muscle (135 MU/g), skin (79 MU/g), and intestine (72 MU/g). Liquid
chromatography/mass spectrometry analysis revealed that TTX was the major toxin.
Nucleotide sequence analysis of the 16S rRNA gene fragment of muscle
mitochondrial DNA indicated that partial sequences of PCR products of four
specimens were identical with that of L. lunaris. The sequence of one specimen
was indistinguishable from that of the brown-backed toadfish Lagocephalus
wheeleri, a nontoxic species. A total of 155 puffers caught from two of Thailand's seas, the Gulf of Siam and
the Andaman seas, during April to July 2010 were included in this study. Among
125 puffers from the Gulf of Siam, 18 were Lagocephalus lunaris and 107 were L.
spadiceus which were the same two species found previously in 2000-2001. Thirty
puffers were collected from the Andaman seas, 28 Tetraodon nigroviridis and two
juvenile Arothron reticularis; the two new species totally replaced the nine
species found previously in 1992-1993. Conventional mouse bioassay was used to
determine the toxicity in all fish tissue extracts, i.e., liver, reproductive
tissue, digestive tissue and muscle. One of each of the species L. lunaris and
L. spadiceus (5.56 and 0.93%, respectively) were toxic. All 28 T. nigroviridis
and 2 A. reticularis (100%) from the Andaman seas were toxic. The toxicity
scores in T. nigroviridis tissues were much higher than in the respective
tissues of the other three fish species. Liquid chromatography/tandem mass
spectrometry (LC-MS/MS) revealed that the main toxic principle was tetrodotoxin
(TTX). This study is the first to report TTX in L. spadiceus. Our findings
raised a concern for people, not only Thais but also inhabitants of other
countries situated on the Andaman coast; consuming puffers of the Andaman seas
is risky due to potential TTX intoxication. Puffer fish, Takifugu niphobles, collected from the Hong Kong coastal waters
were screened for tetrodotoxin-producing bacteria. A Gram-negative,
non-acid-fast, non-sporing and rod shaped bacterial strain (designated as
gutB01) was isolated from the intestine of the puffer fish and was shown to
produce tetrodotoxin (TTX). Based on the Microbial Identification (MIDI) and
16S-23S rDNA internal transcribed spacer (ITS) phylogenetic analysis, the strain
was identified as Raoultella terrigena. The TTX production ability of the strain
was confirmed by mouse bioassay, ELISA and mass spectrometry (MALDI-TOF). Our
results reiterate that the TTX found in puffer fish was likely produced by the
associated bacteria and TTX are widely produced amongst a diversity of bacterial
species. Food poisoning due to ingestion of a puffer fish occurred in Nagasaki
Prefecture, Japan, in October 2008, causing neurotoxic symptoms similar to those
of tetrodotoxin (TTX) poisoning. In the present study, we identified the
species, toxicity, and toxins using the remaining samples of the causative
puffer fish. The puffer fish was identified as smooth-backed blowfish
Lagocephalus inermis by nucleotide sequence analysis of the 16S rRNA and
cytochrome b gene fragments of muscle mitochondrial DNA. The residual liver
sample showed toxicity as high as 1,230 mouse unit (MU)/g by bioassay and TTX
was detected by liquid chromatography/mass spectrometry analysis. We therefore
concluded that the food poisoning was due to TTX caused by consumption of the
toxic liver of L. inermis. This is the first report that the liver of L. inermis
caught in Japanese waters is strongly toxic, with levels exceeding 1,000 MU/g.
In this context, we re-examined the toxicity of L. inermis collected off the
coast of Japan. Of 13 specimens assayed, 12 were toxic, although the toxicity
varied markedly among individuals and tissues. Because the intestine and ovary
of L. inermis have been considered non-toxic, it is particularly noteworthy that
these organs were determined to be toxic, with a maximum toxicity of 43.6 MU/g
and 10.0 MU/g, respectively. Furthermore, kidney, gallbladder, and spleen, whose
toxicity has been unknown, were frequently found to be weakly toxic with levels
ranging from 10 to 99 MU/g. Therefore, further study is needed to re-examine the
toxicity of smooth-backed blowfish L. inermis in the coastal waters of Japan. Tetrodotoxin is a potent low weight marine toxin found in warm waters,
especially of the Indian and Pacific Oceans. Intoxications are usually linked to
the consumption of the puffer fish, although TTX was already detected in several
different edible taxa. Benthic organisms such as mollusks and echinoderms, with
different feeding habits, were collected monthly along the Portuguese coast from
the summer of 2009 until the end of 2010. The extraction and analysis techniques
were optimized and TTX and some analogues were detected for the first time in
two intertidal gastropod species-Gibbula umbilicalis and Monodonta lineata by
LC-MS/MS and UPLC-MS/MS. Although the levels are low, these findings suggest
that monitoring of TTX and analogues in North Atlantic species should be
implemented so as to detect potentially new toxin vectors and seasonal and/or
geographical patterns. Marine pufferfish generally contain a large amount of tetrodotoxin (TTX) in
their skin and viscera, and have caused many incidences of food poisoning,
especially in Japan. Edible species and body tissues of pufferfish, as well as
their allowable fishing areas, are therefore clearly stipulated in Japan, but
still 2 to 3 people die every year due to pufferfish poisoning. TTX is
originally produced by marine bacteria, and pufferfish are intoxicated through
the food chain that starts with the bacteria. Pufferfish become nontoxic when
fed TTX-free diets in a closed environment in which there is no possible
invasion of TTX-bearing organisms. On the other hand, TTX poisoning due to
marine snails has recently spread through Japan, China, Taiwan, and Europe. In
addition, TTX poisoning of dogs due to the ingestion of sea slugs was recently
reported in New Zealand. TTX in these gastropods also seems to be exogenous;
carnivorous large snails are intoxicated by eating toxic starfish, and
necrophagous small-to-medium snails, the viscera of dead pufferfish after
spawning. Close attention must be paid to the geographic expansion and/or
diversification of TTX-bearing organisms, and to the sudden occurrence of other
forms of TTX poisoning due to their ingestion. Marine pufferfish contain tetrodotoxin (TTX), an extremely potent neurotoxin.
All species of the genus Takifugu accumulate TTX in the liver and ovaries,
although the tissue(s) in which it is localized can differ among species. TTX is
the major defense strategy the pufferfish appears to use against predators. TTX
is also used as a male-attracting pheromone during spawning. Here we demonstrate
an additional (and unexpected) use of maternal TTX in the early larval stages of
the Takifugu pufferfish. Predation experiments demonstrated that juveniles of
all the species of fish used as predators ingested pufferfish larvae, but spat
them out promptly. Liquid Chromatography-Tandem Mass Spectrometry (LC-MSMS)
analysis revealed that the pufferfish larvae contain a small quantity of TTX,
which is not enough to be lethal to the predators. Immunohistochemical analysis
with anti-TTX monoclonal antibody revealed that the TTX is primarily localized
in the body surface of the larvae as a layer of protection. Our study showed the
female parent of the Takifugu pufferfish vertically transfers TTX to the larvae
through its accumulation in the ovaries, and subsequent localization on the body
surface of the larvae. The selling and importing of puffer fish species and their products was banned
in Thailand in 2002, because of possible neurotoxic effects. However, the sale
of their flesh is still happening in Thai markets. Standard methods for toxin
quantification (HPLC and LC-MS) have significant limitations, therefore a
lateral flow, immuno-chromatographic test (TTX-IC) was developed as a tool for
rapid detection of toxin. A total of 750 puffer fishes (387 Lagocephalus
lunaris(LL), and 363 Lagocephalus spadiceus (LS)) and 100 edible fishes were
caught in Thailand from June 2011-February 2012. Screening of TTX from their
flesh by TTX-IC revealed that 69 samples (17.8%) of LL possessed TTX at
dangerous levels but LS and edible fishes did not. A selected 339 samples were
quantified by LC-MS/MS, showing 50 LL possessed TTX at dangerous levels.
Comparison of results with LC-MS/MS showed the TTX-IC to have 94.0% sensitivity
and 92.4% specificity. The TTX-IC will be a useful tool for TTX screening of a
large number of samples, reducing the testing required by LC-MS/MS, thus
reducing costs. All positive cases found should be confirmed by standard
methods. |
How is myotonic dystrophy inherited? | Myotonic dystrophy (DM) is a heterogeneous neuromuscular disease with an autosomal dominant pattern of inheritance. | Dystrophic myotonia is a sufficiently rare disease inherited mainly by the
autosomal domit type. Clinical picture is characterized by the myotonic,
myopathic, and endocrine-autonomic syndrome. A clinical, genetic, and
electromyographic study was carried out to elucidate the problem of this
condition inheritance, its intra- and interfamilial clinical polymorphism, and
effects of environmental factors on its course and outcomes. Myotonic dystrophy type 1 (DM1) is an autosomal domit disorder, caused by an
expansion of a CTG triplet repeat in the DMPK gene. The aims of the present
study were to classify a cohort of children with DM1, to describe their
neuropsychiatric problems and cognitive level, to estimate the size of the CTG
expansion, and to correlate the molecular findings with the neuropsychiatric
problems. Fifty-seven children and adolescents (26 females; 31 males) with DM1
(CTG repeats > 40) were included in the study. The following instruments were
used: Autism Diagnostic Interview-Revised (ADI-R), 5-15, Griffiths Mental
Development Scales, and the Wechsler Scales. Based on age at onset and
presenting symptoms, the children were divided into four DM1 groups; severe
congenital (n = 19), mild congenital (n = 18), childhood (n = 18), and classical
DM1 (n = 2). Forty-nine percent had an autism spectrum disorder (ASD) and
autistic disorder was the most common diagnosis present in 35% of the subjects.
Eighty-six percent of the individuals with DM1 had mental retardation (MR), most
of them moderate or severe MR. ASD was significantly correlated with the DM1
form; the more severe the form of DM1, the higher the frequency of ASD. The
frequency of ASD increased with increasing CTG repeat expansions. ASD and/or
other neuropsychiatric disorders such as attention deficit hyperactivity
disorder, and Tourette's disorder were found in 54% of the total DM1 group. In
conclusion, awareness of ASD comorbidity in DM1 is essential. Further studies
are warranted to elucidate the molecular etiology causing neurodevelopmental
symptoms such as ASD and MR in DM1. BACKGROUND: Myotonic dystrophy type 2 (DM2) is an autosomal domit,
multisystem disorder caused by a CCTG tetranucleotide repeat expansion located
in intron 1 of the zinc finger protein 9 gene (ZNF9 gene) on chromosome 3q 21.3.
OBJECTIVES: To describe the clinical, electrophysiologic and pathologic findings
in patients with myotonic dystrophy 2.
METHODS: We evaluated 10 patients genetically, clinically and
electrophysiologically during the years 2007 to 2008.
RESULTS: All patients were of Jewish European ancestry. Among affected
individuals, eight patients had symptoms of proximal muscle weakness, two had
muscle pain, and two exhibited myotonia. On physical examination six patients
had severe weakness of hip flexor muscles. Seven individuals underwent cataract
surgery, and cardiac involvement was seen in one case. On the initial
electromyographic (EMG) examination five patients demonstrated myotonic
discharges; repeated studies showed these discharges in nine cases. Six muscle
biopsies showed non-specific pathological changes. Seven patients had an
affected first-degree relative with either a diagnosed or an undiagnosed
muscular disorder consistent with an autosomal domit trait.
CONCLUSIONS: DM2 may often present with proximal muscle weakness without
myotonia. EMG may initially fail to show myotonic discharges, but these
discharges may eventually show in most cases on repeated EMG. Thus, DM2 may be
underdiagnosed and should be included in the differential diagnosis of adult
patients of Jewish European ancestry presenting with proximal lower limb
weakness. |
How do HBS1L-MYB intergenic variants regulate fetal hemoglobin? | HBS1L-MYB intergenic variants modulate fetal hemoglobin via long-range MYB enhancers. Several HBS1L-MYB intergenic variants affect regulatory elements that are occupied by key erythroid transcription factors within this region. These elements interact with MYB, a critical regulator of erythroid development and HbF levels. Several HBS1L-MYB intergenic variants reduce transcription factor binding, affecting long-range interactions with MYB and MYB expression levels. | |
Which are the mammalian orthologs of Drosophila Yki? | There are two mammalian orthologs of Yki: YAP and TAZ | The mechanisms that regulate mammalian organ size are poorly understood. It is
unclear whether the pathways that control organ size also impinge on
stem/progenitor cells. A highly expressed gene in stem cells is YAP1, the
ortholog of Drosophila Yorkie, a downstream component of the Hippo pathway.
Mutations in components of this pathway produce tissue overgrowth phenotypes in
the fly whereas mammalian orthologs, like salvador, merlin, LATS, and YAP1, have
been implicated in tumorigenesis. We report here that YAP1 increases organ size
and causes aberrant tissue expansion in mice. YAP1 activation reversibly
increases liver size more than 4-fold. In the intestine, expression of
endogenous YAP1 is restricted to the progenitor/stem cell compartment, and
activation of YAP1 expands multipotent undifferentiated progenitor cells, which
differentiate upon cessation of YAP1 expression. YAP1 stimulates Notch
signaling, and administration of gamma-secretase inhibitors suppressed the
intestinal dysplasia caused by YAP1. Human colorectal cancers expressing higher
levels of YAP1 share molecular aspects with YAP1-induced dysplastic growth in
the mouse. Our data show that the Hippo signaling pathway regulates organ size
in mammals and can act on stem cell compartments, indicating a potential link
between stem/progenitor cells, organ size, and cancer. The Hippo pathway defines a novel signaling cascade regulating cell
proliferation and survival in Drosophila, which involves the negative regulation
of the transcriptional coactivator Yorkie by the kinases Hippo and Warts. We
have recently shown that the human ortholog of Yorkie, YAP, maps to a minimal
amplification locus in mouse and human cancers, and that it mediates dramatic
transforming activity in MCF10A primary mammary epithelial cells. Here, we show
that LATS proteins (mammalian orthologs of Warts) interact directly with YAP in
mammalian cells and that ectopic expression of LATS1, but not LATS2, effectively
suppresses the YAP phenotypes. Furthermore, shRNA-mediated knockdown of LATS1
phenocopies YAP overexpression. Because this effect can be suppressed by
simultaneous YAP knockdown, it suggests that YAP is the primary target of LATS1
in mammalian cells. Expression profiling of genes induced by ectopic expression
of YAP or by knockdown of LATS1 reveals a subset of potential Hippo pathway
targets implicated in epithelial-to-mesenchymal transition, suggesting that this
is a key feature of YAP signaling in mammalian cells. Hippo-Lats-Yorkie signaling regulates tissue overgrowth and tumorigenesis in
Drosophila. We show that the Mst1 and Mst2 protein kinases, the mammalian Hippo
orthologs, are cleaved and constitutively activated in the mouse liver. Combined
Mst1/2 deficiency in the liver results in loss of inhibitory Ser127
phosphorylation of the Yorkie ortholog, Yap1, massive overgrowth, and
hepatocellular carcinoma (HCC). Reexpression of Mst1 in HCC-derived cell lines
promotes Yap1 Ser127 phosphorylation and inactivation and abrogates their
tumorigenicity. Notably, Mst1/2 inactivates Yap1 in liver through an
intermediary kinase distinct from Lats1/2. Approximately 30% of human HCCs show
low Yap1(Ser127) phosphorylation and a majority exhibit loss of cleaved,
activated Mst1. Mst1/2 inhibition of Yap1 is an important pathway for tumor
suppression in liver relevant to human HCC. Genetic screens in the fruit fly Drosophila melanogaster have identified a class
of neoplastic tumor suppressor genes (endocytic nTSGs), which encode proteins
that localize to endosomes and facilitate the trafficking of membrane-bound
receptors and adhesion molecules into the degradative lysosome. Loss of
endocytic nTSGs transforms imaginal disc epithelia into highly proliferative,
invasive tissues that fail to differentiate and display defects in cellular
apicobasal polarity, adhesion and tissue architecture. As vertebrate homologs of
some Drosophila nTSGs are linked to tumor formation, identifying molecular
changes in signaling associated with nTSG loss could inform understanding of
neoplastic transformation in vertebrates. Here we show that mutations in genes
that act at multiple steps of the endolysosomal pathway lead to autonomous
activation of the Sav/Wts/Hpo (SWH) transcriptional effector Yki (YAP/TAZ in
vertebrates) and the Jun N-terminal kinase (JNK), which is known to promote Yki
activity in cells with disrupted polarity. Yki and JNK activity are elevated by
mutations at multiple steps in the endolysosomal pathway including mutations in
the AP-2σ gene, which encodes a component of the AP-2 adaptor complex that
recruits cargoes into clathrin-coated pits for subsequent internalization.
Moreover, reduction of JNK activity can decrease elevated Yki-signaling caused
by altered endocytosis. These studies reveal a broad requirement for components
of the endocytic pathway in regulating SWH and JNK outputs, and place Drosophila
endocytic nTSGs into a network that involving two major signaling pathways
implicated in oncogenesis. EGFR and Hippo signaling pathways both control growth and, when dysregulated,
contribute to tumorigenesis. We find that EGFR activates the Hippo pathway
transcription factor Yorkie and demonstrate that Yorkie is required for the
influence of EGFR on cell proliferation in Drosophila. EGFR regulates Yorkie
through the influence of its Ras-MAPK branch on the Ajuba LIM protein Jub. Jub
is epistatic to EGFR and Ras for Yorkie regulation, Jub is subject to
MAPK-dependent phosphorylation, and EGFR-Ras-MAPK signaling enhances Jub binding
to the Yorkie kinase Warts and the adaptor protein Salvador. An EGFR-Hippo
pathway link is conserved in mammals, as activation of EGFR or RAS activates the
Yorkie homolog YAP, and EGFR-RAS-MAPK signaling promotes phosphorylation of the
Ajuba family protein WTIP and also enhances WTIP binding to the Warts and
Salvador homologs LATS and WW45. Our observations implicate the Hippo pathway in
EGFR-mediated tumorigenesis and identify a molecular link between these
pathways. |
Is statin use associated with improved outcomes after aneurysmal subarachnoid hemorrhage? | Statin use after subarachnoid hemorrhage has been shown be associated with improved outcomes by some prospective clinical trials. It has been reported that statin use after subarachnoid hemorrhage reduced rates of vasospasm, delayed cerebral ischemia, and mortality. However, other authors have failed to find beneficial effect of statin use in subarachnoid hemorrhage patients. | OBJECTIVE: Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins),
which exhibit beneficial cerebrovascular effects by modulating inflammation and
nitric oxide production, have not been evaluated in acute aneurysmal
subarachnoid hemorrhage (SAH) patients. The effect of prior statin use on 14-day
functional outcome and on prevention of vasospasm-induced delayed cerebral
ischemia (DCI) or stroke during hospitalization was analyzed.
METHODS: We conducted a 1:2 matched (age, admission Hunt and Hess grade,
vascular disease/risk history) cohort study of 20 SAH patients on statins and 40
SAH controls. The primary outcome was functional outcome at 14 days (Modified
Lawton Physical Self-Maintece Scale and Barthel Index scale scores).
Secondary outcomes were 14-day mortality, Modified Rankin Scale score, DCI, DCI
supported by angiography/transcranial Doppler [TCD], cerebral infarctions of any
type, and TCD highest mean velocity elevation.
RESULTS: Statin users demonstrated a significant protective effect on 14-day
Barthel Index scale and Modified Lawton Physical Self-Maintece Scale scores
(77 +/- 10 versus 39 +/- 8, P = 0.003; 12 +/- 7 versus 19 +/- 9, P = 0.03,
respectively). Moreover, statin users demonstrated a significantly lower
incidence of DCI and DCI supported by angiography/TCD (10% versus 43%, P = 0.02;
5% versus 35%, P = 0.01, respectively), cerebral infarctions of any type (25%
versus 63%, P = 0.01), and baseline-to-final TCD highest mean velocity change of
50 cm/s or greater (18% versus 51%, P = 0.03).
CONCLUSION: SAH statin users demonstrated significant improvement in 14-day
functional outcome, a significantly lower incidence of DCI and cerebral
infarctions of any type, as well as prevention of TCD highest mean velocity
elevation. However, we did not find a significant statin impact on mortality or
global outcome (Modified Rankin Scale) in this small sample. This study provides
clinical evidence for the potential therapeutic benefit of statins after acute
SAH. BACKGROUND AND PURPOSE: Statins may improve cerebral vasomotor reactivity
through cholesterol-dependent and -independent mechanisms. A phase II randomized
controlled trial was conducted to examine the hypothesis that acute pravastatin
treatment could improve cerebrovascular autoregulation and reduce
vasospasm-related complications after aneurysmal subarachnoid hemorrhage (SAH).
METHODS: A total of 80 aneurysmal SAH (aSAH) patients (18 to 84 years of age)
within 72 hours from the ictus were randomized equally to receive either oral
pravastatin (40 mg) or placebo daily for up to 14 days. Primary end points were
the incidence, duration, and severity of cerebral vasospasm, and duration of
impaired autoregulation estimated from transcranial Doppler ultrasonography.
Secondary end points were the incidence of vasospasm-related delayed ischemic
deficits (DIDs) and disability at discharge.
RESULTS: Prerandomization characteristics were balanced between the 2 groups. No
treatment-related complication was observed. The incidences of vasospasm and
severe vasospasm were reduced by 32% (P=0.006) and 42% (P=0.044), respectively,
and the duration of severe vasospasm was shortened by 0.8 days (P=0.068) in the
pravastatin group. These measurements were maximal on the ipsilateral side of
ruptured aneurysms. The duration of impaired autoregulation was shortened
bilaterally (P< or =0.01), and the incidence of vasospasm-related DIDs and
mortality were decreased by 83% (P<0.001) and 75% (P=0.037), respectively, in
the pravastatin group.
CONCLUSIONS: Acute treatment with pravastatin after aSAH is safe and ameliorates
cerebral vasospasm, improves cerebral autoregulation, and reduces
vasospasm-related DID. Unfavorable outcome at discharge was reduced primarily
because of a reduction in overall mortality. This is the first demonstration of
clinical benefits with immediate statin therapy for an acute cerebrovascular
disorder. BACKGROUND AND PURPOSE: Cerebral vasospasm remains a major source of morbidity
after aneurysmal subarachnoid hemorrhage (SAH). We demonstrate that simvastatin
reduces serum markers of brain injury and attenuates vasospasm after SAH.
METHODS: Patients with angiographically documented aneurysmal SAH were
randomized within 48 hours of symptom onset to receive either simvastatin (80 mg
daily; n=19) or placebo (n=20) for 14 days. Plasma alanine aminotransferase,
aspartate aminotransferase, and creatine phosphokinase were recorded weekly to
evaluate laboratory evidence of hepatitis or myositis. Serum markers of brain
injury were recorded daily. The primary end point of vasospasm was defined as
clinical impression (delayed ischemic deficit not associated with rebleed,
infection, or hydrocephalus) in the presence of > or =1 confirmatory
radiographic test (angiography or transcranial Doppler demonstrating mean V(MCA)
>160 m/sec).
RESULTS: There were no significant differences in laboratory-defined
transaminitis or myositis between groups. No patients developed clinical
symptoms of myopathy or hepatitis. Plasma von Willebrand factor and S100beta
were decreased 3 to 10 days after SAH (P<0.05) in patients receiving simvastatin
versus placebo. Highest mean middle cerebral artery transcranial Doppler
velocities were significantly lower in the simvastatin-treated group (103+/-41
versus 149+/-47; P<0.01). In addition, vasospasm was significantly reduced
(P<0.05) in the simvastatin-treated group (5 of 19) compared with those who
received placebo (12 of 20).
CONCLUSIONS: The use of simvastatin as prophylaxis against delayed cerebral
ischemia after aneurysmal SAH is a safe and well-tolerated intervention. Its use
attenuates serum markers associated with brain injury and decreases the
incidence of radiographic vasospasm and delayed ischemic deficit. OBJECTIVE: To evaluate the evidence for use of hydroxymethylglutaryl coenzyme A
reductase inhibitors (statins) for the prevention and management of cerebral
vasospasm after aneurysmal subarachnoid hemorrhage (aSAH).
DATA SOURCES: Literature searches were conducted using MEDLINE (1966-July 2007)
and the Cochrane Database (2007, Issue 2). Search terms included HMG-CoA
reductase inhibitors, statins, subarachnoid hemorrhage, and vasospasm. Other
data sources were identified from select bibliographies.
STUDY SELECTION AND DATA EXTRACTION: All controlled trials evaluating statins
for the prevention and management of cerebral vasospasm after aSAH and published
in the English language were included for review. Clinical and surrogate markers
for cerebral vasospasm and outcomes were assessed.
DATA SYNTHESIS: Cerebral vasospasm, which may occur after aSAH, is associated
with serious morbidity and significant mortality. Evidence suggests that statins
have noteworthy biochemical effects through inhibition of nicotinamide adenine
dinucleotide phosphate oxidase and superoxide production and up-regulation and
activation of endothelial nitric oxidase synthase and nitric oxidase production
via inhibition of geranylgeranylation of RhoA and Rac1 guanosine
triphosphatases. Researchers have proposed that these effects may have a role in
preventing or reducing vasospasm after aSAH. One matched control study and 3
placebo-controlled trials (1 with an additional post hoc analysis) have
described use of statins for the prevention and management of cerebral vasospasm
after aSAH. These data focused on differing primary endpoints; however,
reductions in clinical vasospasm and middle cerebral artery transcranial doppler
velocity, improved functional outcomes, enhanced autoregulation indices
incidence, improvements in duration and time of impaired cerebral
autoregulation, and reductions in rescue therapy have been reported.
CONCLUSIONS: Current data suggest that statins may be a reasonable treatment
option for the prevention and management of cerebral vasospasm after aSAH.
However, results from large, well-controlled trials have not been published. OBJECTIVE: The development of delayed ischemia caused by cerebral vasospasm
remains a common cause of morbidity and mortality after aneurysmal subarachnoid
hemorrhage. Preliminary studies suggest that 3-hydroxy-3-methylglutaryl coenzyme
A reductase inhibitors (statins) may decrease the risk of vasospasm, but
additional study is required.
METHODS: Beginning in May 2006, our treatment protocol for patients presenting
with subarachnoid hemorrhage was altered to routinely include the use of 80 mg
of simvastatin per day for 14 days. Before this time, only patients with other
indications for statins were treated. The charts of 203 consecutive patients
over a period of 27 months were retrospectively reviewed, and 150 patients were
included in the analysis, of whom 71 patients received statins. These patients
were compared with 79 untreated patients to determine whether or not the use of
statins was associated with a reduction in the occurrence of vasospasm, delayed
infarction, or poor outcome (death, vegetative state, or severe disability).
RESULTS: Patients who were treated with statins and those who were not had
similar baseline characteristics, although more patients in the former group
were managed with endovascular coil embolization. There were no statistically
significant differences in the proportion of patients developing at least
moderate radiographic vasospasm (41% with statins versus 42% without, P = 0.91),
symptomatic vasospasm (32% with statins versus 25% without, P = 0.34), delayed
infarction (23% with statins versus 28% without, P = 0.46), or poor outcome (39%
with statins versus 35% without, P = 0.61). After adjustment for differences in
baseline characteristics, including the method of aneurysm treatment, statins
were still not significantly protective.
CONCLUSION: The addition of statins to standard care was not associated with any
reduction in the development of vasospasm or improvement in outcomes after
aneurysmal subarachnoid hemorrhage. If there is a benefit to statin use, it may
be smaller than suggested by previous studies. However, further randomized
controlled trials are awaited. BACKGROUND AND PURPOSE: Subarachnoid hemorrhage (SAH) is a relatively rare cause
of stroke with a high rate of morbidity and mortality, primarily due to the
occurrence of delayed vasospasm. To date, many therapies have been proposed to
help prevent vasospasm, but very few have been proven effective. The initiation
of statin therapy after SAH may be effective in reducing the incidence of
vasospasm; however, the only studies that have examined this effect have been
small. This meta-analysis attempted to determine whether statins reduce
morbidity and mortality after aneurysmal SAH.
METHODS: MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials
were searched for randomized, controlled trials relating to the use of statins
in SAH. Foreign language and abstract articles were included. Two independent
reviewers assessed studies for eligibility, data extraction, and quality.
Primary outcome was the incidence of radiographically confirmed clinical
vasospasm; secondary outcomes were incidence of delayed ischemic deficits and
mortality.
RESULTS: The incidence of vasospasm (relative risk [RR]=0.73; 95% CI, 0.54 to
0.99), delayed ischemic deficits (RR=0.38; 95% CI, 0.17 to 0.83), and mortality
(RR=0.22; 95% CI, 0.06 to 0.82) were significantly reduced in the statin group.
For these outcomes, we calculated a number needed to treat of 6.25, 5, and 6.7,
respectively.
CONCLUSIONS: Initiation of statin therapy after aneurysmal SAH significantly
reduces the incidence of vasospasm, delayed ischemic deficits, and mortality.
This is consistent with animal research and retrospective studies and supports
the routine use of statins in the care of patients with aneurysmal SAH. OBJECTIVE: To analyse the effect of the implementation of statin and magnesium
treatment on delayed cerebral ischemia (DCI) and 14 day mortality in patients
with subarachnoid hemorrhage (SAH).
METHODS: Retrospective, single-center, observational case control study. One
hundred SAH patients received either simvastatin and magnesium, solely statin or
no treatment.
RESULTS: Eighteen percent (n=5) of patients receiving statin and magnesium
treatment developed a DCI whereas 24% (n=5) in the statin group and 16% (n=8) in
the control group had DCI. Dead by day 14 was registered in 18% (n=5) of
patients in the statin and magnesium group, in 10% (n=2) in the statin group and
in 27% (n=14) in the control group. None of the results reached a statistical
significance level of 0.05.
CONCLUSION: A trend towards a lower mortality within 14 days in patients
receiving solely simvastatin and those receiving statin and magnesium as
compared with the control group was found. A higher incidence for DCI was found
in the statin group, whereas patients without statin and magnesium tended to
have less often DCI. None of the results was statistically significant. BACKGROUND AND STUDY AIMS: Spontaneous intracerebral hemorrhage (ICH) represents
the most fatal kind of stroke, and there is still no treatment available that
improves the outcome. Statins are cholesterol reducers, and during the last few
years many additional effects have been demonstrated that might be
neuroprotective. We designed a pilot clinical study in order to evaluate whether
the administration of statins is associated with a better outcome.
PATIENTS AND METHODS: From August to December 2006 we carried out a
prospective/retrospective non-randomized clinical study. The prospective group
was treated with rosuvastatin (20 mg) and the retrospective control group was
taken from our clinical records with a relation of 1:3. We included patients of
both sexes, aged > or =15 years with proven ICH in CT-scan. Exclusion criteria
were a history of neoplasm, head injury four weeks before admission,
non-hypertensive reasons, brainstem hemorrhage, steroid administration, cranial
surgery, initial hydrocephalus, and NIHSS > or =30.
RESULTS: We analyzed 18 patients treated with rosuvastatin and 57 controls with
similar basic characteristics. The mortality rate during hospitalization was 1
(5.6%) patient in the statin group and 9 (15.8%) in the control group; the
hazard ratio adjusted by the initial Glasgow Coma Scale (GCS), intubation,
admission in intensive care unit, disruption into the subarachnoid space was
0.20 (95% CI 0.02-1.67). The odds ratio for NIHSS > or =15 at release was 0.04
(95% CI 0.003-0.93).
CONCLUSIONS: The use of statins during the acute phase of ICH could be
associated with a better outcome. Further clinical trials are necessary to
confirm a possible therapeutic effect and evaluate the toxicity of statins. OBJECT: Vasospasm is the major cause of disability and death after aneurysmal
subarachnoid hemorrhage (aSAH). Although the results of 2 randomized clinical
trials demonstrated that statin decreases the incidence of symptomatic cerebral
vasospasm after aSAH, retrospective studies have failed to confirm this. The
authors conducted a prospective observational study to determine whether a
standardized regimen of simvastatin would reduce the incidence of cerebral
vasospasm and improve neurological outcomes in patients with aSAH.
METHODS: Since 1991, all patients with aSAH admitted to the authors' institution
have been prospectively followed up with standardized outcomes recording.
Starting in September 2005, all patients admitted with aSAH were given enteral
simvastatin (80 mg/day for 14 days) in addition to the standard care. The
incidence of symptomatic cerebral vasospasm, length of hospitalization,
in-hospital mortality rate, and discharge Glasgow Outcome Scale scores in these
170 patients were compared to data obtained in 170 consecutive patients who
underwent treatment in our unit prior to the introduction of statin therapy.
RESULTS: The 5-year study period included 340 consecutively treated patients
(170 who received statins and 170 who did not). Patients who received
simvastatin therapy were more frequently male (29 vs 20%) and had a smaller
median aneurysm diameter (6 vs 7 mm). Baseline characteristics were otherwise
similar between the cohorts. There were no differences in the incidence of
symptomatic vasospasm (25.3 vs 30.5%; p = 0.277), in-hospital mortality rate (18
vs 15%; p = 0.468), length of hospitalization (21 +/- 15 vs 19 +/- 12 days; p =
0.281), or poor outcome at discharge (Glasgow Outcome Scale Scores 1-2: 21.7 vs
18.2%; p = 0.416) between the simvastatin and nonstatin cohorts. There were no
statin-related complications.
CONCLUSIONS: The uniform introduction of simvastatin did not reduce the
incidence of symptomatic cerebral vasospasm, death, or poor outcome in patients
with aSAH. Simvastatin was well tolerated, but its benefit may be less than has
been previously reported. BACKGROUND: Aside from their cholesterol-lowering effects statins are known to
have a range of other 'pleiotropic' effects. We present an overview of the basic
science behind these effects and then review clinical trials and the current
role of statins relevant to modern surgical practice.
METHODS: A systematic review of the literature was performed using the keywords
surgery and the MeSH term for statins. All clinical studies relating to statin
use in surgical patients were evaluated. An overview of the literature on statin
use and cardiac outcomes was performed.
CONCLUSIONS: Statins are safe and have a wide range of pleiotropic effects
relevant to surgical practice. Strongest evidence for their clinical use comes
in primary cardiac risk reduction in many types of vascular surgery. There is a
large body of evidence showing their benefit perioperatively in high-risk
vascular and cardiac surgery but the picture is less clear for low-risk
patients. Further studies are needed to evaluate exact dosage regimes and timing
of administration. Novel uses of their anti-inflammatory properties in sepsis
and vasomotor properties in subarachnoid haemorrhage are being further
investigated by randomised trials. Recently, two randomized controlled phase II studies showed that acute
initiation of statin treatment directly after aneurysmal subarachnoid hemorrhage
(SAH) decreases the incidence of radiologic vasospasm and clinical signs of
delayed cerebral ischemia (DCI), and even reduces mortality. It was hypothesized
that the beneficial effect resulted from pleiotropic effects of statins. The
purpose of this study was to investigate the biologic effects of acute statin
treatment in patients with SAH. We performed an exploratory single-center,
prospective, randomized, double-blind, placebo-controlled trial. Patients were
randomized to simvastatin 80 mg or placebo once daily. A total of 32 patients
were included. There were no statistically significant differences in clinical
baseline characteristics. With regard to primary outcomes, there were
significant differences by treatment group for total cholesterol and low-density
lipoprotein (LDL) cholesterol (P<0.0001), but not for parameters of coagulation,
fibrinolysis, endothelium function, and inflammation. With regard to secondary
outcomes, no differences were observed in the incidence of transcranial Doppler
vasospasm, clinical signs of DCI, and poor outcome. We conclude that both the
primary and secondary outcome results of this study do not support a beneficial
effect of simvastatin in patients with SAH. BACKGROUND: Pre-treatment with cholesterol lowering drugs of the statin family
may exert protective effects in patients with ischaemic stroke and subarachnoid
haemorrhage but their effects are not clear in patients with intracerebral
haemorrhage (ICH).
METHODS: We recruited patients admitted to our University Hospital with an acute
ICH and analysed pre-admission demographic variables, pre-morbid therapy,
clinical and radiological prognostic markers and outcome variables including
90-day modified Rankin score and NIH stroke scale score (NIHSS).
RESULTS: We recruited 399 patients with ICH of which 101 (25%) were using
statins. Statin users more often had vascular risk factors, had significantly
lower haematoma volumes (P = 0.04) and had lower mortality rates compared with
non-users (45.6% vs. 56.1%; P = 0.11). However, statin treatment did not have a
statistically significant impact on mortality or functional outcome on multiple
logistic regression analysis.
CONCLUSIONS: Treatment with statins prior to ICH failed to show a significant
impact on outcome in this analysis despite lower haematoma volumes. BACKGROUND AND PURPOSE: A recent meta-analysis investigating the efficacy of
statin treatment in patients with aneurysmal subarachnoid hemorrhage reported a
reduced incidence of vasospasm, delayed cerebral ischemia, and mortality in
statin-treated patients. However, the meta-analysis was criticized for its
methodology, and several retrospective studies found no beneficial effect. We
present the results of a new systematic review, which differs from the previous
systematic review in its methodology, and by inclusion of the results of a
fourth randomized, placebo-controlled trial. Summary of Review- All randomized,
placebo-controlled trials investigating the effect of statins on vasospasm,
delayed cerebral ischemia, and functional outcome in patients with aneurysmal
subarachnoid hemorrhage were included. Outcomes were the number of patients with
transcranial Doppler vasospasm, delayed cerebral ischemia, poor outcome, and
mortality during follow-up. Effect sizes were expressed in (pooled) risk ratio
estimates. Data were pooled using random-effects models.
RESULTS: In 4 studies, a total of 190 patients were included. No statistically
significant effect was observed on transcranial Doppler vasospasm (pooled risk
ratio, 0.99 [95% CI, 0.66 to 1.48]), delayed cerebral ischemia (pooled risk
ratio, 0.57 [95% CI, 0.29 to 1.13]), poor outcome (pooled risk ratio, 0.92 [95%
CI, 0.68 to 1.24]), or mortality (pooled risk ratio, 0.37 [95% CI, 0.13 to
1.10]).
CONCLUSIONS: The results of the present systematic review do not lend
statistically significant support to the finding of a beneficial effect of
statins in patients with aneurysmal subarachnoid hemorrhage as reported in a
previous meta-analysis. BACKGROUND: the pathophysiology of delayed neurological deficits (DNDs)
following aneurysmal subarachnoid hemorrhage (SAH) is complex, and is not
limited to arterial narrowing (vasospasm) and classical ischemia. Thus, combined
drug approaches, or therapies with multiple effects, may have the greatest
potential for benefit. Statins are known to have pleiotropic vascular effects,
some of which may interrupt the pathogenesis of DNDs. Based on promising
preliminary reports, many clinicians routinely administer statins to prevent
DNDs.
METHODS: a systematic review was performed to identify and summarize all animal
research, observational studies, randomized controlled trials (RCTs) and
meta-analyses which have evaluated the use of statins in the management of SAH.
RESULTS: nine animal studies, nine observational (cohort and case-control)
studies, six RCTs and three meta-analyses were identified. Animal studies have
generally administered statin doses that, when adjusted for body weight, are
10-80 times larger than what is used in humans. Nevertheless, these models have
consistently reported statins to reduce vasospasm and to demonstrate additional
neuroprotective effects. However, observational studies have not revealed an
association between statin-use and reduced DNDs or improved neurological
outcomes. Results of RCTs have been inconsistent and limited by small sample
size, but together suggest that statins may reduce DNDs, with no clear impact on
mortality or neurological recovery. Optimal drug administration strategies
(timing of initiation, most effective dose and duration) have not been
clarified.
CONCLUSIONS: the role of statins in the management of patients with SAH remains
unclear. Although promising, statins should not, at this time, be considered
standard care. The HMG-CoA reductase inhibitors (statins) are used extensively in the treatment
of hyperlipidemia. They have also demonstrated a benefit in a variety of other
disease processes. These secondary actions are known as pleiotropic effects. Our
paper serves as a focused and updated discussion on the pleiotropy of statins
and emphasizes the importance of randomized placebo-controlled trials to further
elucidate this interesting phenomenon. OBJECTIVE: Statins, which improve the bioavailability of endogenous nitric oxide
and upregulate endothelial nitric oxide synthase, have been used to prevent
cerebral vasospasm after aneurysmal subarachnoid hemorrhage. The objective of
this study was to determine whether statin therapy diminished vasospasm-induced
ischemia as assessed using daily measurements of serum S100B, a biomarker for
cerebral ischemia, and computed tomography measurement of ischemic lesion
volume.
DESIGN: Single-center study of cases and historical controls.
SETTING: Neurointensive care unit in a university hospital.
PATIENTS: Consecutive patients with aneurysmal subarachnoid hemorrhage treated
with clipping or coiling within 96 hrs of symptom onset (n = 278) were included
from April 2004 to October 2007.
INTERVENTION: Oral atorvastatin, 40 mg/day for 21 days, was used routinely
starting on December 1, 2005, in 142 patients, who were compared with the 136
patients managed earlier.
MEASUREMENTS AND MAIN RESULTS: Ischemic lesion size was measured using computed
tomography on the last available scan and serum S100B was assayed daily for 15
days after admission. Angiographic narrowing was semiquantitatively assessed in
patients with vasospasm. In the overall population, cerebral vasospasm was
significantly less common in the statin-treated group. Severity of vasospasm, as
assessed on the most severe angiogram, was lowered with statin. Statins
significantly reduced volume of ischemia in patients with vasospasm and an
uncomplicated coiling procedure. S100B levels were significantly lower in
statin-treated patients, and the decrease was greatest among high-grade patients
(World Federation of Neurological Surgeons 3-5). No differences were found
between statin-treated and untreated groups regarding rescue therapy intensity
or 1-yr clinical outcomes.
CONCLUSIONS: Atorvastatin reduces the incidence, the severity and the ischemic
consequences of vasospasm as assessed on computed tomography. In high-grade
World Federation of Neurological Surgeons patients, atorvastatin decreases serum
levels of S100B, a biomarker of brain ischemia. Despite these positive effects
on biomarkers, no improvement of outcome was seen in the overall population,
although there was a tendency for a better clinical outcome in high-grade
patients. The use or misuse of statins in critically ill patients recently attracted the
attention of intensive care clinicians. Indeed, statins are probably the most
common chronic treatment before critical illness and some recent experimental
and clinical data demonstrated their beneficial effects during sepsis, acute
lung injury (ALI)/acute respiratory distress syndrome (ARDS), or after
aneurismal subarachnoidal hemorrhage (aSAH). Due to the heterogeneity of current
studies and the lack of well-designed prospective studies, definitive
conclusions for systematic and large-scale utilization in intensive care units
cannot be drawn from the published evidence. Furthermore, the extent of statins
side effects in critically ill patients is still unknown. For the intensive care
clinician, it is a matter of individually identifying the patient who can
benefit from this therapy according to the current literature. The purpose of
this review is to describe the mechanisms of actions of statins and to
synthesize the clinical data that underline the relevant effects of statins in
the particular setting of critical care, in an attempt to guide the clinician
through his daily practice. BACKGROUND: Experimental evidence has indicated the benefit of simvastatin in
the treatment of subarachnoid hemorrhage. However, no clinical data are
available to answer whether a high-dose regimen is more effective than a
normal-dose regimen, even though the biochemical actions and related
neuroprotective mechanisms are thought to be dose related.
OBJECTIVE: To determine whether 80 mg simvastatin daily (high dose) over 3 weeks
initiated within 96 hours of the ictus will reduce the incidence of delayed
ischemic deficits after subarachnoid hemorrhage compared with 40 mg simvastatin
daily (normal dose), leading to improvements in clinical outcomes and thus
cost-effectiveness.
METHODS: The study design is a randomized, controlled, double-blind clinical
trial (www.ClinicalTrials.gov; identifier: NCT01077206). Two hundred forty
patients with aneurysmal subarachnoid hemorrhage (presenting within 96 hours of
the ictus) from 6 neurosurgical centers are being recruited over 3 years. The
primary outcome measure is the presence of delayed ischemic deficits. Secondary
outcome measures include modified Rankin Disability Score at 3 months and
cost-effectiveness analysis.
EXPECTED OUTCOMES: This will be the first study to clarify whether high-dose
simvastatin is better than normal-dose simvastatin for patients with acute
aneurysmal subarachnoid hemorrhage in terms of neurological outcomes and
cost-effectiveness.
DISCUSSION: In the present trial, we compare high-dose and normal-dose
simvastatin; we know that another ongoing phase III multicenter trial
(Simvastatin in Aneurysmal Subarachnoid Haemorrhage;
http://www.stashtrial.com/home.html) is comparing normal-dose and no
simvastatin. When the results are interpreted together, the research question of
a possible beneficial effect of high-dose simvastatin in acute aneurysmal
subarachnoid hemorrhage could be answered. BACKGROUND: Cerebral vasospasm and related delayed ischaemic deficits (DIDs)
occur in about 17% to 40% of patients with aneurysmal subarachnoid haemorrhage
(SAH) and lead to a poor outcome. Cholesterol-reducing agents might improve
unfavourable outcomes.
OBJECTIVES: To assess the effects of cholesterol-reducing agents for improving
outcomes in patients with aneurysmal SAH.
SEARCH METHODS: We searched the Cochrane Stroke Group Trials Register (May
2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The
Cochrane Library 2012, Issue 5), MEDLINE (1948 to May 2012) and EMBASE (1980 to
May 2012). We also searched three Chinese databases: SinoMed, CNKI and VIP (May
2012). In an effort to identify further published, ongoing and unpublished
trials we searched relevant clinical trials and research registers (May 2012),
contacted pharmaceutical companies and investigators known to be involved in
previous trials and screened the reference lists of all relevant articles
identified.
SELECTION CRITERIA: We included randomised controlled trials (RCTs) that
compared cholesterol-reducing agents with control or placebo treatment in
participants with aneurysmal SAH.
DATA COLLECTION AND ANALYSIS: Two review authors independently applied the
inclusion criteria, reviewed the relevant trials and extracted data. We did not
perform meta-analysis as we only included one RCT in the review.
MAIN RESULTS: We included one study in which 39 patients received either
simvastatin (80 mg daily; n = 19) or placebo (n = 20) for 14 days. The incidence
of DIDs (secondary outcome) was 26% (5/19) in the simvastatin group versus 60%
(12/20) in the placebo group (risk ratio (RR) 0.44, 95% confidence interval (CI)
0.19 to 1.01, P = 0.05). This means that, in this study, simvastatin had no
effect on DIDs. Two patients in the simvastatin group and one patient in the
placebo group had elevated levels of aspartate transaminase or alanine
transaminase. One patient in the simvastatin group had a raised creatine
phosphokinase. There were no results from this trial for the primary outcome of
death or dependency at six months.
AUTHORS' CONCLUSIONS: We cannot draw any conclusions about the effectiveness and
safety of lowering cholesterol in aneurysmal SAH because of insufficient
reliable evidence from only one small trial. More RCTs are needed. Subarachnoid haemorrhage (SAH) causes early brain injury (EBI) that is mediated
by effects of transient cerebral ischaemia during bleeding plus effects of the
subarachnoid blood. Secondary effects of SAH include increased intracranial
pressure, destruction of brain tissue by intracerebral haemorrhage, brain shift,
and herniation, all of which contribute to pathology. Many patients survive
these phenomena, but deteriorate days later from delayed cerebral ischaemia
(DCI), which causes poor outcome or death in up to 30% of patients with SAH. DCI
is thought to be caused by the combined effects of angiographic vasospasm,
arteriolar constriction and thrombosis, cortical spreading ischaemia, and
processes triggered by EBI. Treatment for DCI includes prophylactic
administration of nimodipine, and current neurointensive care. Prompt
recognition of DCI and immediate treatment by means of induced hypertension and
balloon or pharmacological angioplasty are considered important by many
physicians, although the evidence to support such approaches is limited. This
Review summarizes the pathophysiology of DCI after SAH and discusses established
treatments for this condition. Novel strategies--including drugs such as
statins, sodium nitrite, albumin, dantrolene, cilostazol, and intracranial
delivery of nimodipine or magnesium--are also discussed. |
What is the typical outer diameter of microtubules (tubulin heterodimers)? | Microtubules are highly anisotropic structures built from tubulin heterodimers. They are hollow cylindrical shells with a ∼ 25 nm (24nm - 25nm) outer diameter. | Partial spinal cord ischaemia was induced in dogs, ranging from 1 to 3 years of
age, by ligature of the abdominal aorta just below the arteria coeliaca. The
changes of the lumbal sensitive ganglia neurons were studied. In addition to the
most often occurring changes, e.g., the vacuolization of the mitochondria, the
disaggregation of ribosomes, the dilatation of the Golgi complex, the
microtubular formations in the dilated cisterns of the endoplasmic reticulum
were observed. Modified cisterns of the granulated endoplasmic reticulum (GER)
occurred focally in relatively well preserved neurons. The individual
microtubules measured about 24 nm in outer diameter, and their walls were formed
by some subunits. Microtubules are hollow tubes some 25 nm in diameter participating in the
eukaryotic cytoskeleton. They are built from alphabeta-tubulin heterodimers that
associate to form protofilaments running lengthwise along the microtubule wall
with the beta-tubulin subunit facing the microtubule plus end conferring a
structural polarity. The alpha- and beta-tubulins are highly conserved. A third
member of the tubulin family, gamma-tubulin, plays a role in microtubule
nucleation and assembly. Other members of the tubulin family appear to be
involved in microtubule nucleation. Microtubule assembly is accompanied by
hydrolysis of GTP associated with beta-tubulin so that microtubules consist
principally of 'GDP-tubulin' stabilized at the plus end by a short 'cap'. An
important property of microtubules is dynamic instability characterized by
growth randomly interrupted by pauses and shrinkage. Many proteins interact with
microtubules within the cell and are involved in essential functions such as
microtubule growth, stabilization, destabilization, and interactions with
chromosomes during cell division. The motor proteins kinesin and dynein use
microtubules as pathways for transport and are also involved in cell division.
Crystallography and electron microscopy are providing a structural basis for
understanding the interactions of microtubules with antimitotic drugs, with
motor proteins and with plus end tracking proteins. Near-field optical techniques have enabled the trapping, transport, and handling
of oscopic materials much smaller than what can be manipulated with
traditional optical tweezers. Here we extend the scope of what is possible by
demonstrating angular orientation and rotational control of both biological and
nonbiological oscale rods using photonic crystal otweezers. In our
experiments, single microtubules (diameter 25 nm, length 8 μm) and multiwalled
carbon otubes (outer diameter 110-170 nm, length 5 μm) are rotated by the
optical torque resulting from their interaction with the evanescent field
emanating from these devices. An angular trap stiffness of κ = 92.8
pN·nm/rad(2)·mW is demonstrated for the microtubules, and a torsional spring
constant of 22.8 pN·nm/rad(2)·mW is measured for the otubes. We expect that
this new capability will facilitate the development of high precision
oassembly schemes and biophysical studies of bending strains of biomolecules. Revealing vibration characteristics of sub-cellular structural components such
as membranes and microtubules has a principal role in obtaining a deeper
understanding of their biological functions. Nevertheless, limitations and
challenges in biological experiments at this scale necessitates the use of
mathematical and computational models as an alternative solution. As one of the
three major cytoskeletal filaments, microtubules are highly anisotropic
structures built from tubulin heterodimers. They are hollow cylindrical shells
with a ∼ 25 nm outer diameter and are tens of microns long. In this study, a
mechanical model including the effects of the viscous cytosol and surrounding
filaments is developed for predicting the coupled oscillations of a single
microtubule immersed in cytoplasm. The first-order shear deformation shell
theory for orthotropic materials is used to model the microtubule, whereas the
motion of the cytosol is analyzed by considering the Stokes flow. The viscous
cytosol and the microtubule are coupled through the continuity condition across
the microtubule-cytosol interface. The stress and velocity fields in the cytosol
induced by vibrating microtubule are analytically determined. Finally, the
influences of the dynamic viscosity of the cytosol, filament network elasticity,
microtubule shear modulus, and circumferential wave-number on longitudinal,
radial, and torsional modes of microtubule vibration are elucidated. |
Does molindone affect body weight? | Yes, molindone has a tendency to cause weight loss or limited weight gain. | The weight-reducing property of molindone, a recently introduced antipsychotic
drug, was tested in 9 hospitalized chronic schizophrenic patients. There was an
average weight loss of 7.6 kg after 3 months on molindone; most of the loss
occurred during the first month. The mechanism producing this weight loss is
uncertain, but a central anorexigenic effect may be an important factor. Molindone hydrochloride, a dihydroindolone neuroleptic, is structurally distinct
from other classes of neuroleptics. Molindone exhibits many similarities to
other neuroleptics, including dopamine receptor blockade, antipsychotic
efficacy, and extrapyramidal side effects. Despite these similarities, molindone
also has atypical properties and inhibits the enzyme monoamine oxidase in vitro
and in vivo. Several studies have shown that molindone causes less dopamine
receptor supersensitivity than other neuroleptics and thus may be less likely to
cause tardive dyskinesia. It also appears to have a greater effect on mesolimbic
and mesocortical dopamine neurons than on those in the nigrostriatal dopamine
system. Clinically, molindone has a tendency to cause weight loss and may have
less effect on seizure threshold than conventional antipsychotic agents. The
authors review the laboratory and clinical data on molindone and discuss the
relevance of atypical research findings to the clinical characteristics of this
antipsychotic agent. In this article we review the empirical literature on weight gain associated
with neuroleptic drug use. Weight gain, which appears to be associated with an
increase in appetite, is variable but likely to be larger initially and then
plateau. Clozapine and low-potency phenothiazines are associated with the
largest gains and molindone with weight loss, but the mechanism is not known.
Amantadine and fenfluramine may reverse weight gain to some degree. Dietary fat
seems to play an important role in obesity, and research is needed to increase
the data base and elucidate possible mechanisms. Studies are also needed to
evaluate preventive strategies and to determine which drugs are least likely to
produce weight gain as well as which drugs could be added to a neuroleptic
regimen to control weight. Consenting schizophrenic patients ranging in age from 18 to 63 years were
withdrawn from antipsychotics for at least 1 week and randomly assigned to
receive identical capsules of thioridazine (n = 13), molindone (n = 10), or
haloperidol (n = 12) for a minimum of 6 weeks. Compared with the molindone- and
haloperidol-treated patients, the thioridazine-treated patients were
significantly improved over time as measured by Brief Psychiatric Rating Scale
(BPRS) and Hamilton Rating Scale for Depression (HAM-D) total scores.
Improvement in BPRS scores was due largely to improvement in symptoms of anxiety
and depression. Subjects did not differ significantly on other measures, with
the important exception of weight. On average, molindone patients lost 5 pounds
over the 6 weeks of treatment, whereas thioridazine patients gained 6 pounds.
Haloperidol-treated patients had no significant weight changes. A number of drugs are capable of changing bodyweight as an adverse effect of
their therapeutic action. Bodyweight gain is more of a problem than bodyweight
loss. As bodyweight gain during drug treatment for any kind of disease may be
the reflection of improvement of the disease itself, we will try to separate
these effects from those due to drug-induced alterations of the mechanisms
regulating bodyweight. Bodyweight gain may jeopardise patient compliance to the
prescribed regimen and it may pose health risks. The body mass index (BMI) is
determined by dividing bodyweight in kilograms by height in metres squared. A
BMI of > or = 27 kg/m2 warrants therapeutic action; nutritional counselling and
programmed physical exercise can be used as a basis. In general, if basic
therapeutic measures are unsuccessful at controlling bodyweight gain then a
change of drug might help. Finally, an anoretic drug may serve to support
dietary measures. However, safety and efficacy has been demonstrated for only a
few anorectic drugs when used as an adjunct to caloric restriction in the
treatment of drug-induced obesity. Bodyweight is determined by complex
mechanisms regulating energy balance. A number of neurotransmitter systems
acting in several hypothalamic nuclei are pivotal to the regulation of body fat
stores. Most drugs that are capable of changing bodyweight interfere with these
neurotransmitter systems. The increment is dependent on the type and dose of the
drug concerned. Some antidepressant drugs induce bodyweight gain, which may
amount to 20 kg over several months of treatment. Monoamine oxidase inhibitors
appear to cause less bodyweight change than tricyclic antidepressants. Selective
serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors cause bodyweight loss
instead of bodyweight gain. Lithium may cause large increases in bodyweight.
Generally speaking, the bodyweight change induced by antipsychotics is more
often of clinical significance than the bodyweight change associated with the
use of antidepressants. Again, the changes of bodyweight are dependent upon the
type and dose of the antipsychotic drug involved. Although almost all
antipsychotics induce bodyweight gain, molindone and loxapine appear to induce
bodyweight loss. Anticonvulsants, especially valproic acid (sodium valproate)
and carbamazepine, induce bodyweight gain in a considerable percentage of
patients. Treatment with corticosteroids is associated with dose-dependent
bodyweight gain in many patients. Corticosteroid-induced obesity aggravates
other corticosteroid-associated health risks. Insulin therapy in diabetic
patients usually increases bodyweight. Finally, sulphonurea derivatives,
antineoplastic agents used for the treatment of breast cancer and several drugs
used in migraine prophylaxis may cause bodyweight gain as well. Weight gain has been reported with nearly every antipsychotic drug on the market
(molindone is an exception). Weight gain occurs no matter what the patient's
age, sex, or race and is seen with both oral and depot drug formulations.
Numerous studies have found that patients gain weight when treated with a
conventional antipsychotic, such as chlorpromazine, fluphenazine, and
haloperidol. The newer, novel antipsychotics offer advantages over conventional
antipsychotics, especially a relative lack of extrapyramidal symptoms, but some
still have the disadvantage of causing weight gain. Clozapine and olanzapine in
particular appear to cause substantial weight gain, much more so than do most
conventional neuroleptics and novel agents such as risperidone. Given the risks
to health and treatment compliance associated with weight gain and obesity,
clinicians should monitor weight during the course of antipsychotic therapy and
consider switching agents if excessive weight gain occurs. OBJECTIVE: The purpose of this study was to estimate and compare the effects of
antipsychotics-both the newer ones and the conventional ones-on body weight.
METHOD: A comprehensive literature search identified 81 English- and
non-English-language articles that included data on weight change in
antipsychotic-treated patients. For each agent, a meta-analysis and random
effects metaregression estimated the weight change after 10 weeks of treatment
at a standard dose. A comprehensive narrative review was also conducted on all
articles that did not yield quantitative information but did yield important
qualitative information.
RESULTS: Placebo was associated with a mean weight reduction of 0.74 kg. Among
conventional agents, mean weight change ranged from a reduction of 0.39 kg with
molindone to an increase of 3.19 kg with thioridazine. Among newer antipsychotic
agents, mean increases were as follows: clozapine, 4.45 kg; olanzapine, 4.15 kg;
sertindole, 2.92 kg; risperidone, 2.10 kg; and ziprasidone, 0.04 kg.
Insufficient data were available to evaluate quetiapine at 10 weeks.
CONCLUSIONS: Both conventional and newer antipsychotics are associated with
weight gain. Among the newer agents, clozapine appears to have the greatest
potential to induce weight gain, and ziprasidone the least. The differences
among newer agents may affect compliance with medication and health risk. BACKGROUND: Typical antipsychotic drugs are widely used as the first line
treatment for people with schizophrenia. However, the atypical class of
antipsychotic drugs is making important inroads into this approach. 'Atypical'
is a term widely used to describe some antipsychotics which have a low
propensity to produce movement disorders, sedation and raised serum prolactin.
There is some suggestion that the different adverse effect profiles of the
atypical antipsychotic group make them more acceptable to people with
schizophrenia. Molindone has a similar profile to quetiapine (a novel atypical
antipsychotic), with very low binding to all receptors. Some authors have
suggested that molindone is safer than other 'typical' antipsychotics in that
extrapyramidal adverse effects are not usually seen at clinically effective
antipsychotic doses and that it should therefore be classed as an atypical
antipsychotic.
OBJECTIVES: To determine the effects of molindone compared with placebo, typical
and other atypical antipsychotic drugs for schizophrenia and related psychoses.
SEARCH STRATEGY: Electronic searches of Biological Abstracts (1980-1999), The
Cochrane Library CENTRAL (Issue 1, 1999), The Cochrane Schizophrenia Group's
Register (January 1999), CINAHL (1982-1999), EMBASE (1980-1999), MEDLINE
(1966-1999), LILACS (1982-1999), PSYNDEX (1977-1999), and PsycLIT (1974-1999)
were undertaken. In addition, pharmaceutical databases on the Dialog Corporation
Datastar and Dialog services were searched. References of all identified studies
were searched for further trials. The manufacturer of molindone and authors of
trials were contacted.
SELECTION CRITERIA: All randomised controlled trials that compared molindone to
other treatments for schizophrenia and schizophrenia-like psychoses were
included by independent assessment.
DATA COLLECTION AND ANALYSIS: Citations and, where possible, abstracts were
independently inspected by reviewers, papers ordered, re-inspected and quality
assessed. Data were independently extracted. Data were excluded if loss to
follow up was greater than 50%. For homogeneous dichotomous data the risk ratio
(RR), 95% confidence interval (CI) and, where appropriate, the number needed to
treat (NNT) were calculated on an intention-to-treat basis. For continuous data,
weighted mean differences (WMD) were calculated. All data were inspected for
heterogeneity.
MAIN RESULTS: Thirteen studies were included in the review. Data for this
compound range from very short (10 day) studies of the intramuscular preparation
to trials lasting over three months. For measures of global state available data
do not justify any conclusions on the comparative efficacy of molindone and
placebo. When compared to other typical antipsychotics no difference in
effectiveness was evidenced (doctors' RR 1.13, CI 0.69 to 1.86; nurses' RR 1.23,
CI 0.82 to 1.86). It is no more or less likely than typical drugs to cause
movement disorders, but causes significantly more weight loss (RR 2.78, CI 1.10
to 6.99).
REVIEWER'S CONCLUSIONS: The strength of the evidence relating to this compound
is limited, owing to small sample size, poor study design, limited outcomes and
incomplete reporting. Molindone may be an effective antipsychotic; however, its
adverse effect profile does not differ significantly from that of typical
antipsychotics, apart from the event of weight loss. At present there is no
evidence to suggest that it may have an atypical profile. Weight gain associated with neuroleptics or antipsychotic treatment is well
known by psychiatrists, but is too rarely considered as justifying a specific
treatment program. Overweight is a risk factor for somatic disorders and can
have a negative influence on self-esteem and self-confidence. This can lead to
poor observance, and relapse of psychotic symptoms. Some studies try to describe
the weight fluctuations according to the different neuroleptics and taking into
account other variables like treatment duration, age or sex. Mechanisms of
weight gain are less studied, in spite of evidence that neuroleptics interact
with receptors of dopamine, norepinephrine, serotonin, histamine and
acetylcholin, all implicated in a way or another, in weight regulation.
Antipsychotics, like clozapine and olanzapine, are more concerned with
neuroendocrine and neurovegetative interactions, and are responsible for the
most severe weight increases. Loxapine and molindone induce weight decreases,
and these exceptions are difficult to explain. The paper discusses the clinical
and the epidemiological data, and indicates the methodological problems for such
studies. Some hypotheses about the pathophysiological aspects of this side
effect are made, in regard to growing knowledge about the biological mechanisms
of weight regulation. Some solutions for a better consideration and caretaking
of patients with such problems or "at risk" treatment are proposed. Excessive body weight gain (BWG) is a common side effect of some typical and
atypical antipsychotic drugs (APs). Convergent evidence suggests a hierarchy in
the magnitude of BWG that may be induced by diverse agents, being very high for
clozapine and olanzapine; high for quetiapine, zotepin, chlorpromazine, and
thioridazine; moderate for risperidone and sertindole; and low for ziprazidone,
amisulpiride, haloperidol, fluphenazine, pimozide, and molindone. BWG may be
related to increased appetite that is due to drug interaction with the brain
monoaminergic and cholinergic systems and to the metabolic/endocrine effects of
hyperprolactinemia. Subjects with schizophrenia and bipolar disorders manifested
a significantly high prevalence of diabetes, even before the introduction of
atypical APs. However, clozapine and olanzapine appear to display a high
propensity to induce glucose dysregulation and dyslipidemia. Sudden BWG, insulin
resistance, increased appetite, and related endocrine changes also may be
involved in the development of glucose intolerance and dyslipidemia in
predisposed individuals. Patients should be informed of these side effects in
order to prevent excessive BWG, and their blood glucose and lipids should be
monitored before treatment and then at regular intervals. Nutritional advice
must be given and regular physical exercise recommended. An appropriate
selection of APs ought to be based on drug efficacy for specific patients and
assessment of relevant risk factors such as propensity to gain weight; family or
personal history of diabetes or hyperlipidemia; and elevated fasting serum
glucose, lipid, or insulin levels. At present, there is no standardized
pharmacological treatment for AP-induced BWG. Some studies have assessed the
effects of agents such as amantadine, orlistat, metformin, nizatidine, and
topiramate on AP-induced BWG. Further studies will provide tools to identify
patients at high risk for obesity and metabolic abnormalities during AP
administration. Excessive body weight gain (BWG), glucose intolerance, and
dyslipidemia during treatment with antipsychotic drugs (APs) were reported in
the late 1950s [14,101]. However, after 1990, interest in these problems
increased noticeably, mainly because of the high propensity of some new atypical
APs to induce these side effects (Fig.1). The APs are currently used in diverse
mental disorders. Hence, excessive BWG and metabolic dysfunction are not
exclusive of subjects with schizophrenia. In the case of bipolar disorders,
AP-induced BWG may be additive to that induced by mood stabilizers [14,48,101].
The clinical features [2,14,24,133,139,140] and mechanisms
[14,34,68,87,93,101,130] of BWG and metabolic dysfunction have been previously
reviewed. In this article, we focus on a unified theory to explain these side
effects, based on the interaction of APs with brain neurotransmitters involved
in appetite regulation. This review comprises the following sections: 1) the
clinical features of AP-induced BWG; 2) the effects of APs on carbohydrate and
lipid metabolism in humans and experimental animals; 3) mechanisms involved in
BWG, glucose, and lipid dysregulation; 4) strategies for prevention and
treatment of these side effects; and 5) research perspectives in the field. The
following sources were consulted: MEDLINE, Cochrane database system, and
PsychINFO. Numerous articles referred to in leading articles also were
consulted. The literature on this subject has increased so rapidly that it was
impossible to include all the data recently published. For the first two
sections, references that illustrate current controversies in the field were
selected. BACKGROUND: Antipsychotic therapy is the mainstay of treatment for people with
schizophrenia. In recent years new or atypical antipsychotics have been
introduced. These are less likely to produce movement disorders and raise serum
prolactin. Researchers have suggested that molindone should be classified as an
atypical antipsychotic.
OBJECTIVES: To determine the effects of molindone compared with placebo, typical
and other atypical antipsychotic drugs for schizophrenia and related psychoses.
SEARCH STRATEGY: For the original search we searched the following databases:
Biological Abstracts (1980-1999), The Cochrane Library CENTRAL (Issue 1, 1999),
The Cochrane Schizophrenia Group's Register (January 1999), CINAHL (1982-1999),
EMBASE (1980-1999), MEDLINE (1966-1999), LILACS (1982-1999), PSYNDEX
(1977-1999), and PsycLIT (1974-1999). We also searched pharmaceutical databases
on the Dialog Corporation Datastar and Dialog and the references of all
identified studies for further trials. Finally, we contacted the manufacturer of
molindone and the authors of any relevant trials. For the update of this review,
we searched The Cochrane Schizophrenia Group's Trials Register (August 2005).
SELECTION CRITERIA: We included all randomised controlled trials that compared
molindone to other treatments for schizophrenia and schizophrenia-like
psychoses.
DATA COLLECTION AND ANALYSIS: We extracted data independently and analysed on an
intention to treat basis calculating, for binary data, the fixed effect relative
risk (RR), their 95% confidence intervals (CI), and the number needed to treat
or harm (NNT or NNH). We excluded data if loss to follow up was greater than
50%.
MAIN RESULTS: We included fourteen studies. Duration ranged from very short (10
days) studies of the intramuscular preparation, to trials lasting over three
months. For measures of global assessment, available data do not justify any
conclusions on the comparative efficacy of molindone and placebo. When compared
to other typical antipsychotics we found no evidence of a difference in
effectiveness (doctors' 4 RCTs n=150, RR 1.13, CI 0.69 to 1.86; nurses 4RCTs
n=146, RR 1.23, CI 0.82 to 1.86). Molindone is no more or less likely than
typical drugs to cause movement disorders, but it does cause significantly more
weight loss (2RCTs n=60 RR 2.78, CI 1.10 to 6.99, NNH 5 CI 2 to 77).
AUTHORS' CONCLUSIONS: The strength of the evidence relating to this compound is
limited, owing to small sample size, poor study design, limited outcomes and
incomplete reporting. Molindone may be an effective antipsychotic but its
adverse effect profile does not differ significantly from that of typical
antipsychotics (apart from the event of weight loss). Data from this review
suggest, at present, there is no evidence to suggest that it may have an
atypical profile. OBJECTIVE: Atypical (second-generation) antipsychotics are considered standard
treatment for children and adolescents with early-onset schizophrenia and
schizoaffective disorder. However, the superiority of second-generation
antipsychotics over first-generation antipsychotics has not been demonstrated.
This study compared the efficacy and safety of two second-generation
antipsychotics (olanzapine and risperidone) with a first-generation
antipsychotic (molindone) in the treatment of early-onset schizophrenia and
schizoaffective disorder.
METHOD: This double-blind multisite trial randomly assigned pediatric patients
with early-onset schizophrenia and schizoaffective disorder to treatment with
either olanzapine (2.5-20 mg/day), risperidone (0.5-6 mg/day), or molindone
(10-140 mg/day, plus 1 mg/day of benztropine) for 8 weeks. The primary outcome
was response to treatment, defined as a Clinical Global Impression (CGI)
improvement score of 1 or 2 and >or=20% reduction in Positive and Negative
Syndrome Scale (PANSS) total score after 8 weeks of treatment.
RESULTS: In total, 119 youth were randomly assigned to treatment. Of these
subjects, 116 received at least one dose of treatment and thus were available
for analysis. No significant differences were found among treatment groups in
response rates (molindone: 50%; olanzapine: 34%; risperidone: 46%) or magnitude
of symptom reduction. Olanzapine and risperidone were associated with
significantly greater weight gain. Olanzapine showed the greatest risk of weight
gain and significant increases in fasting cholesterol, low density lipoprotein,
insulin, and liver transaminase levels. Molindone led to more self-reports of
akathisia.
CONCLUSIONS: Risperidone and olanzapine did not demonstrate superior efficacy
over molindone for treating early-onset schizophrenia and schizoaffective
disorder. Adverse effects were frequent but differed among medications. The
results question the nearly exclusive use of second-generation antipsychotics to
treat early-onset schizophrenia and schizoaffective disorder. The safety
findings related to weight gain and metabolic problems raise important public
health concerns, given the widespread use of second-generation antipsychotics in
youth for nonpsychotic disorders. Conflict of interest statement: Disclosure: Dr. Findling receives or has
received research support, served as a consultant for and/or served on the
speakers’ bureau for Abbott, Addrenex, AstraZeneca, Biovail, Bristol-Myers
Squibb, Forest, GlaxoSmithKline, Johnson and Johnson, KemPharm, Eli Lilly and
Company, Lundbeck, Neuropharm, Novartis, Organon, Otsuka, Pfizer,
Sanofi-Aventis, Sepracore, Shire, Solvay, Supernus Pharmaceuticals, Validus, and
Wyeth. Dr. Frazier receives research funding from or participates in clinical
trials with Bristol-Myers Squibb, GlaxoSmithKline, Janssen, Johnson and Johnson,
Neuropharm, Otsuka America Pharmaceutical, and Pfizer. Dr. Hamer, in the past
three years, received or has receives research support, served as a consultant
for and served on a data safety monitoring board (DSMB) / internal displacement
monitoring centre (IDMC) for Acadia, Allergan, Alpharma, AstraZeneca, Cenerx,
Corcept, EnabledMD, Epix, Johnson and Johnson, Novartis, Pepper-Hamilton,
Pfizer, SAS Institute, Schwartz, Solvay, Sanofi-Aventis, Takeda, Winston-Strawn
(a lawsuit involving Forest, Lundbeck, Sun, Caraco), and Wyeth. He and/or his
wife own stock in Bristol-Myers Squibb, Amgen, Eli Lilly and Company, Genentech,
Proctor and Gamble, and Sepracor. His wife is retired from Bristol-Myers Squibb.
Dr. Liberman serves on the advisory board of Bioline, GlaxoSmithKline,
Intracellular Therapies, Eli Lilly and Company, Psychogenics, and Wyeth. He does
not receive ficial compensation or salary support for his participating as an
advisor, except for Intracellular Therapies. He receives grant support from
Allon, Forest Labs, Merck, and Pfizer. He holds a patent from Repligen. Dr.
Sikick receives research funding or participates in clinical trials with
Janssen, Pfizer, Bristol-Myers Squibb, Neuropharm, Curemark, and Seaside
Pharmaceuticals. She has receives software for a computer intervention in
schizophrenia from Posit Science. In the past, Dr. Sikich received research
funding from Eli Lilly and Company, Janssen, Pfizer, Otsuka, and AstraZeneca.
She has served as a consultant for Sanofi Aventis and ABT Associates. Drs.
Johnson, McClellan, Vitiello, McNamara, Hlastala, and Maloney, and Ms. Ritz, Ms.
Lingler, Ms. Pierson, Ms. Puglia, Ms. Michael Kaufman, and Ms. Noyes report no
biomedical ficial interests or potential conflicts of interest. PURPOSE OF REVIEW: Treatment of children who develop schizophrenia in childhood
and early adolescence presents unique considerations. There has been increasing
attention to the importance of early intervention and whether treatment effects
may be affected by brain development.
RECENT FINDINGS: Several recent trials support the use of antipsychotics for
treatment of schizophrenia in children and adolescents. Clozapine shows greater
efficacy in children and adolescents than it has in adults. A large-scale trial
comparing a first-generation antipsychotic (molindone) with newer agents did not
find significant differences in treatment response, although the newer
antipsychotics were associated with more severe weight gain. Data regarding
effects of antipsychotics on brain development in children and young adolescents
with schizophrenia are sparse, although one report found no difference between
effects of clozapine and olanzapine on cortical thickness.
SUMMARY: Although psychosocial interventions are an important adjunctive
treatment, antipsychotic medications continue to be the mainstay of treatment.
Careful monitoring of metabolic side effects and age-appropriate intervention is
particularly important, as children and adolescents appear to be more likely to
develop metabolic abnormalities such as pronounced weight gain, which may
significantly impact adherence as well as lead to other health issues. OBJECTIVE: To evaluate safety and tolerability of four doses of
immediate-release molindone hydrochloride in children with
attention-deficit/hyperactivity disorder (ADHD) and serious conduct problems.
METHODS: This open-label, parallel-group, dose-ranging, multicenter trial
randomized children, aged 6-12 years, with ADHD and persistent, serious conduct
problems to receive oral molindone thrice daily for 9-12 weeks in four treatment
groups: Group 1-10 mg (5 mg if weight <30 kg), group 2-20 mg (10 mg if <30 kg),
group 3-30 mg (15 mg if <30 kg), and group 4-40 mg (20 mg if <30 kg). The
primary outcome measure was to evaluate safety and tolerability of molindone in
children with ADHD and serious conduct problems. Secondary outcome measures
included change in Nisonger Child Behavior Rating Form-Typical Intelligence
Quotient (NCBRF-TIQ) Conduct Problem subscale scores, change in Clinical Global
Impressions-Severity (CGI-S) and -Improvement (CGI-I) subscale scores from
baseline to end point, and Swanson, Nolan, and Pelham rating scale-revised
(SNAP-IV) ADHD-related subscale scores.
RESULTS: The study randomized 78 children; 55 completed the study. Treatment
with molindone was generally well tolerated, with no clinically meaningful
changes in laboratory or physical examination findings. The most common
treatment-related adverse events (AEs) included somnolence (n=9), weight
increase (n=8), akathisia (n=4), sedation (n=4), and abdominal pain (n=4). Mean
weight increased by 0.54 kg, and mean body mass index by 0.24 kg/m(2). The
incidence of AEs and treatment-related AEs increased with increasing dose.
NCBRF-TIQ subscale scores improved in all four treatment groups, with 34%, 34%,
32%, and 55% decreases from baseline in groups 1, 2, 3, and 4, respectively.
CGI-S and SNAP-IV scores improved over time in all treatment groups, and CGI-I
scores improved to the greatest degree in group 4.
CONCLUSIONS: Molindone at doses of 5-20 mg/day (children weighing <30 kg) and
20-40 mg (≥ 30 kg) was well tolerated, and preliminary efficacy results suggest
that molindone produces dose-related behavioral improvements over 9-12 weeks.
Additional double-blind, placebo-controlled trials are needed to further
investigate molindone in this pediatric population. |
What is the genetic basis of propionic acidemia? | Mutations in the PCCA or PCCB genes, encoding both subunits of propionyl-CoA carboxylase. | Propionic acidemia is an inherited disorder of organic acid metabolism that is
caused by deficiency of propionyl-CoA carboxylase (PCC; EC 6.4.1.3). Affected
patients fall into two complementation groups, pccA and pccBC (subgroups B, C,
and BC), resulting from deficiency of the nonidentical alpha and beta subunits
of PCC, respectively. We have detected an unusual insertion/deletion in the DNA
of patients from the pccBC and pccC subgroups that replaces 14 nucleotides in
the coding sequence of the beta subunit with 12 nucleotides unrelated to this
region of the gene. This results in elimination of an Msp I restriction site, a
2-base-pair (bp) deletion, a frameshift, and a stop codon in the new frame
approximately 100 amino acid residues proximal to the normal carboxyl terminus.
Among 14 unrelated Caucasian patients in the pccBC complementation group, this
unique mutation was found in 8 of 28 mutant alleles examined. Mutant
allele-specific oligonucleotide hybridization to amplified genomic DNAs revealed
that the inserted 12 nucleotides do not originate in an approximately 1000-bp
region around the mutation. In the course of our investigation, we identified
another mutation in the same exon: a 3-bp in-frame deletion that eliminates one
of two isoleucine codons immediately preceding the Msp I site. Two unrelated
patients were compound heterozygotes for this single-codon deletion and for the
insertion/deletion described above. We conclude that either there is a
propensity for the PCC beta-subunit gene to undergo mutations of this sort at
this position or, more likely, the mutations in all of the involved Caucasian
patients have a common origin in preceding generations. Propionic acidemia is an inborn error of metabolism resulting from a deficiency
of propionyl-CoA carboxylase activity. The alpha- and beta-subunits of the
enzyme are encoded by the PCCA and PCCB genes, respectively. Using direct
sequencing and restriction digests of amplified reverse transcripts and genomic
DNA, we have identified two mutations of the PCCB gene in a propionic acidemia
patient from the pccC complementation subgroup (the PCCB gene contains the major
complementation group pccBC and subgroups pccB and pccC). One of the proband
alleles contains an inframe 3-bp deletion inherited from the father which
results in the deletion of an isoleucine residue in the beta-subunit of the
enzyme. The other mutant allele, inherited from the mother, has a 14-bp deletion
and an addition of 12 bp of new sequence at the same site as the father's
allele. The inserted sequence is a partial duplication of a sequence just
upstream of the mutation site. The net result of this mutation generates a
frameshift and a downstream stop codon. Examination of fibroblast mRNA from the
patient showed that it consists essentially of the father's sequence, making it
effectively the only expressed allele for the beta-protein. A survey of
additional patient cell lines revealed the insertion/deletion rearrangement in
three additional patients, two from the pccBC group and one unclassified. The
3-bp deletion allele was unique to the proband. The identification of two
distinct alleles occurring at the same site in the PCCB gene underscores the
importance of this site in enzyme function or integrity. Deficiency of propionyl-CoA carboxylase (PCC; alpha 4 beta 4) results in the
rare, autosomal recessive disease propionic acidemia. Cell fusion experiments
have revealed two complementation groups, pccA and pccB, corresponding to
defects of the PCCA (alpha-subunit) and PCCB (beta-subunit) genes, respectively.
The pccBCC group includes subgroups, pccB and pccC, which are thought to reflect
interallelic complementation between certain mutations of the PCCB gene. In this
study, we have identified the mutations in two pccB, one pccC, and two pccBC
cell lines and have deduced those alleles participating in interallelic
complementation. One pccB line was a compound heterozygote of Pro228Leu and
Asn536Asp. The latter mutation was also detected in a noncomplementing pccBC
line. This leaves Pro228Leu responsible for complementation in the pccB cells.
The second pccB line contained an insertional duplication, dupKICK140-143, and a
splice mutation IVS + 1 G-->T, located after Lys466. We suggest that the dupKICK
mutation is the complementing allele, since the second allele is incompatible
with normal splicing. The pccC line studied was homozygous for Arg410Trp, which
is necessarily the complementing allele in that line. For a second pccC line, we
previously had proposed that delta Ile408 was the complementing allele. We now
show that its second allele, "Ins.Del," a 14-bp deletion replaced by a 12-bp
insertion beginning at codon 407, fails to complement in homozygous form. We
conclude that the interallelic complementation results from mutations in domains
that can interact between beta-subunits in the PCC heteromer to restore
enzymatic function. On the basis of sequence homology with the Propionibacterium
shermanii transcarboxylase 12S subunit, we suggest that the pccC domain, defined
by Ile408 and Arg410, may involve the propionyl-CoA binding site. Propionyl-CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme,
composed of an equal number of alpha and beta subunits, that functions in the
catabolism of branched-chain amino acids and other metabolites. Mutations of the
PCCA (alpha subunit) or PCCB (beta subunit) gene cause the inherited metabolic
disease, propionic acidemia. We report the cloning of a full-length cDNA
encoding the beta subunit of human PCC. The open reading frame encodes a
pre-beta polypeptide of 539 amino acids (58,205 Da). The cDNA was introduced
into the expression vector, pRc/CMV, and microinjected into the nucleus or, as
ribotranscripts, into the cytoplasm of fibroblast lines from patients with
defects of the beta subunit. The restoration of function was monitored by
autoradiography of PCC-dependent [14C]-propionate incorporation into cellular
protein. These results confirm the completeness of the clone and demonstrate the
capacity for beta subunits derived from the microinjected cDNA or RNA to be
transported into mitochondria and assembled with endogenously derived alpha
subunits to form functional PCC. Propionyl-CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme
involved in the catabolism of branched chain amino acids, odd chain fatty acids,
and other metabolites. PCC consists of non-identical subunits, alpha and beta,
encoded by the PCCA and PCCB genes, respectively. Inherited deficiency of PCC
due to mutations in either the PCCA or the PCCB gene results in propionic
acidemia (PA), a clinically heterogeneous disorder with a severe, often lethal,
neonatal form, and a mild, later onset form. To characterize PCCA gene mutations
responsible for PCC deficiency, we analyzed RT-PCR products obtained from
cultured fibroblasts from Spanish PCC-alpha deficient patients. In three
patients, smaller than normal PCR products were observed, and sequence analysis
revealed the deletion of a 54-bp exon in the cDNA. Sequencing of genomic DNA
from these three patients led to the identification of three novel mutations in
the PCCA gene, two short deletions and one small insertion, adjacent to short
direct repeats, and all of them affecting the consensus splice sites of the
skipped exon. These mutations, 1771IVS-2del9, 1824IVS+3del4, and 1824IVS+3insCT,
are the cause of the aberrant splicing of the PCCA pre-mRNA and result in an
in-frame deletion of 54 nucleotides in the cDNA, probably leading to an unstable
protein structure which is responsible for the lack of activity leading to PCC
deficiency in these patients. Propionic acidemia is an autosomal recessive disorder caused by a deficiency in
the mitochondrial enzyme propionyl-CoA carboxylase (PCC). PCC is composed of two
subunits, alpha and beta, encoded by the PCCA and PCCB genes, respectively. We
analyzed mutations of the PCCA gene using patients' fibroblasts diagnosed with
alpha subunit deficiency. By RT-PCR, four of 12 cell lines examined appeared to
have a larger transcript present at a level comparable with that of the expected
normal species. Sequencing of the larger transcriptrevealed an 84 bp insertion
at nt 1209 of the codingsequence. Its incorporation in the transcript results in
translation termination due to the presence of two in-frame stop codons. The 84
bp insertion was found to originate from the intron between nt 1209 and 1210.
Consensus splice donor and acceptor sites were found at the 3'- and 5'-ends of
the insertion, respectively. The insertion was also found in the remaining eight
cell lines as well as in normal cells, but at a muchreduced level compared with
the normal lengthsequence. Mutation analysis of the four cell lines showing
seemingly elevated levels of the insertion sequence revealed one nonsense
mutation (R288X), two frameshift deletions (700del5 and 1115del4) and one splice
mutation (1671IVS+5G-->C) as expressed alleles. We conclude that the common
characteristic of the four cell lines is that they contain mRNA destabilizing
mutations that reduce the mRNA level of the normal length sequence.
Consequently, the low levels of cryptic mRNAs become detectable at a level
similar to that of the residual level of the normal length mRNA. We suggest that
screening for an increased proportion of the 84 bp insertion by RT-PCR can be
used as a rapid assay for RNA destabilizing mutations. Our results suggest
caution in associating such mutations with aberrant mRNA species, such as
cryptic splice products, which may instead be part of the 'background noise' of
the splicing machinery. The inherited metabolic disease propionic acidemia (PA) can result from
mutations in either of the genes PCCA or PCCB, which encode the alpha and beta
subunits, respectively, of the mitochondrial enzyme propionyl CoA-carboxylase.
In this work we have analyzed the molecular basis of PCCA gene defects, studying
mRNA levels and identifying putative disease causing mutations. A total of 10
different mutations, none predomit, are present in a sample of 24 mutant
alleles studied. Five novel mutations are reported here for the first time. A
neutral polymorphism and a variant allele present in the general population were
also detected. To examine the effect of a point mutation (M348K) involving a
highly conserved residue, we have carried out in vitro expression of normal and
mutant PCCA cDNA and analyzed the mitochondrial import and stability of the
resulting proteins. Both wild-type and mutant proteins were imported into
mitochondria and processed into the mature form with similar efficiency, but the
mature mutant M348K protein decayed more rapidly than did the wild-type,
indicating a reduced stability, which is probably the disease-causing mechanism. Propionic acidemia is an inborn error of metabolism caused by a deficiency of
propionyl-CoA carboxylase, a heteropolymeric mitochondrial enzyme involved in
the catabolism of branched chain amino acids, odd-numbered chain length fatty
acids, cholesterol, and other metabolites. The enzyme is composed of alpha and
beta subunits which are encoded by the PCCA and PCCB genes, respectively.
Mutations in both genes can cause propionic acidemia. The identification of the
responsible gene, previous to mutation analysis, can be performed by
complementation assay or, in some instances, can be deduced from peculiarities
relevant to either gene, including obtaining normal enzyme activity in the
parents of many patients with PCCB mutations, observing combined absence of
alpha and beta subunits by Western blot of many PCCA patients, as well as
conventional mRNA-minus result of Northern blots for either gene or beta subunit
deficiency in PCCB patients. Mutations in both the PCCA and PCCB genes have been
identified by sequencing either RT-PCR products or amplified exonic fragments,
the latter specifically for the PCCB gene for which the genomic structure is
available. To date, 24 mutations in the PCCA gene and 29 in the PCCB gene have
been reported, most of them single base substitutions causing amino acid
replacements and a variety of splicing defects. A greater heterogeneity is
observed in the PCCA gene-no mutation is predomit in the populations
studied-while for the PCCB gene, a limited number of mutations is responsible
for the majority of the alleles characterized in both Caucasian and Oriental
populations. These two populations show a different spectrum of mutations, only
sharing some involving CpG dinucleotides, probably as recurrent mutational
events. Future analysis of the mutations identified, of their functional effect
and their clinical relevance, will reveal potential genotype-phenotype
correlations for this clinically heterogeneous disorder. Propionyl CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme
involved in the catabolism of amino acids, odd-chain fatty acids, and other
metabolites. PCC consists of two subunits, alpha and beta, encoded by the PCCA
and PCCB genes, respectively. Inherited PCC deficiency due to mutations in
either gene results in propionic acidemia (PA), an autosomal recessive disease.
Surprisingly, PA is highly prevalent among Inuits in Greenland. We have analyzed
reverse transcriptase-PCR products of the beta-subunit mRNA, to characterize the
responsible mutation(s). A 3-bp insertion, 1540insCCC, was found in homozygous
form in three patients and in compound heterozygous form in one patient. The
resulting PCC has no measurable activity, and the mutant beta-subunit appears to
be very unstable. To test the hypothesis that a common mutation is responsible
for PA in the Greenlandic Inuit population, 310 anonymous DNA samples of Inuit
origin were screened for 1540insCCC. We found a carrier frequency of 5%, which
is very high compared with those of most other autosomal recessive diseases.
Analysis of alleles of a very closely linked marker, D3S2453, revealed a high
degree of linkage disequilibrium between one specific allele and 1540insCCC,
suggesting that this mutation may be a founder mutation. Propionyl-CoA carboxylase (PCC, EC 6.4.1.3) is a mitochondrial, biotin-dependent
enzyme that functions in the catabolism of branched-chain amino acids, fatty
acids with odd-numbered chain lengths, and other metabolites. It catalyzes the
ATP-dependent carboxylation of propionyl-CoA to d-methylmalonyl-CoA. PCC is
composed of two types of subunits, likely as alpha4beta4 or alpha6beta6, with
the alpha subunit containing the covalently bound biotin prosthetic group. A
genetic deficiency of PCC activity causes propionic acidemia, a potentially
fatal disease with onset in severe cases in the newborn period. Affected
patients may have mutations of either the PCCA or PCCB gene. In this study, we
have determined the structure of the human PCCA gene which, at the present time,
is only partially represented in the databases. Based on reported ESTs and
confirmed by RT-PCR, we also redefine the translation initiation codon to a
position 75 nucleotides upstream of the currently accepted initiation codon. We
show the distribution of mutations, including three identified in this study,
and renumber all reported mutations to count from the new initiation codon. The
gene spans more than 360 kb and consists of 24 exons ranging from 37 to 335 bp
in length. The introns range in size from 104.bp to 66 kb. We have also
determined the nucleotide sequence of approximately 1 kb of the 5'-flanking
region upstream of the ATG translation initiation site. The proximal 400 bp of
the 5'-flanking region shows a high G + C content (67%) and is part of a
putative 1-kb CpG island that extends into exon 1 and part of intron 1. The
putative promoter lacks a TATA box but contains two AP-1 sites and a
conservatively defined consensus GC box, the latter characteristic of the core
binding sequence of the Sp1 transcription factor. Propionic acidemia is an inherited metabolic disorder caused by deficiency of
propionyl-CoA carboxylase, a dodecameric enzyme composed of alpha-PCC and
beta-PCC subunits (encoded by genes PCCA and PCCB) that have been associated
with a number of mutations responsible for this disease. To clarify the
molecular effect associated with gene alterations causing propionic acidemia, 12
different mutations affecting the PCCB gene (R67S, S106R, G131R, R165W, R165Q,
E168K, G198D, A497V, R512C, L519P, W531X, and N536D) were analyzed for their
involvement in alpha-beta heteromeric and beta-beta homomeric assembly. The
experiments were performed using the mammalian two-hybrid system, which was
assayed at two different temperatures to distinguish between mutations directly
involved in interaction and those probably affecting polypeptide folding, thus
indirectly affecting the correct assembly. Mutations R512C, L519P, W531X, and
N536D, located at the carboxyl-terminal end of the PCCB gene, were found to
inhibit alpha-beta heteromeric and/or the beta-beta homomeric interaction
independently of the cultivation temperature, reflecting their primary effect on
the assembly. Two mutations A497V and R165Q did not affect either heteromeric or
homomeric assembly. The remaining mutations (R67S, S106R, G131D, R165W, E168K,
and G198D), located in the amino-terminal region of the beta-polypeptide,
resulted in normal interaction levels only when expressed at the lower
temperature, suggesting that these changes could be considered as folding
defects. From these results and the clinical manifestations associated with
patients bearing the mutations described above, several genotype-phenotype
correlations may be established. In general, the temperature-sensitive mutations
are associated with a less severe, although variable phenotype. This could
correlate with the recent hypothesis that the effect of folding mutations can be
influenced by the capacity of the cellular protein quality control machinery,
which provides clues to our understanding of the variability of the clinical
symptoms observed among the patients bearing these mutations. Deficiency of propionyl-CoA carboxylase (PCC) results in propionic acidemia, an
autosomal recessive disorder characterized by ketoacidosis sufficiently severe
to cause neonatal death. PCC is involved in the catabolism of branched-chain
amino acids, odd-chain fatty acids, and cholesterol. The enzyme is a
biotin-dependent mitochondrial protein composed of two heterologous subunits
arranged into an 800-kDa alpha(6 )beta(6) dodecameric structure. Approximately
60 mutations have been reported in the nuclear genes PCCA and PCCB that encode
the two PCC subunits. The vast majority of these mutations have not been
examined at the protein level. We present an initial characterization of 13
mutations located in exons 1, 3-7, and 12-14 of PCCB. After expression in E.
coli, these recombit mutant enzymes were analyzed for stability,
biotinylation, alpha-beta subunit interaction, and activity. Our results show a
functional dichotomy in these PCCB mutations with some mutants (R44P, S106R,
G131R, G198D, V205D, I408del, and M442T) capable of varying degrees of assembly
but forming catalytically inactive PCC proteins. Other PCCB mutants (R165W,
E168K, D178H, P228L, and R410W) that are PCC deficient in patient-derived
fibroblasts, were found to be capable of expressing wild-type level PCC activity
when assembled in our chaperone-assisted E. coli expression system. This result
indicates that these mutations exert their pathogenic effect due to an inability
to assemble correctly in patients' cells. This initial screen has identified a
range of mutant PCC proteins that are sufficiently stable to be purified and
subsequently used for structure-function analysis to further elucidate the
complex relationship between genotype and phenotype in propionic acidemia. Propionic acidemia (PA, MIM 232000 and 232050) is caused by a deficiency of
mitochondrial biotin-dependent propionyl-CoA carboxylase (PCC, EC 6.4.1.3), a
heteropolymeric enzyme composed of alpha and beta subunits, which are encoded by
the PCCA and PCCB genes, respectively. The PCCA protein (alpha subunit) is
responsible for the formation of carboxybiotin upon hydrolysis of ATP and
contains a C-terminal biotin-binding domain and a biotin carboxylase domain,
defined by homology with other biotin-dependent carboxylases, some of them
characterized structurally. More than 24 mutations have been found in the PCCA
gene in patients with PA, among them 14 missense mutations and one in-frame
deletion, for which the precise molecular effect is unknown. In this study, we
have established the pathogenicity of 11 PCCA mutations (10 missense and an
in-frame deletion) by expression studies in deficient fibroblasts and in a
cell-free in vitro system, and analyzed the effect of each mutation on PCC
activity, protein stability and domain structure. The results show that most
mutant proteins show an increased turnover and are functionally deficient,
suggesting that the structural alterations they cause are incompatible with
normal assembly to produce a stable, functional PCC oligomer. These results are
discussed in the context of the genotype-phenotype correlations in
PCCA-deficient PA patients. Propionic acidemia (PA) is an autosomal recessive inborn error in the catabolism
of methionine, isoleucine, threonine, and valine, odd-numbered chain length
fatty acids and cholesterol. Clinical symptoms are very heterogeneous and
present as a severe neonatal-onset or a late-onset form. It is caused by a
deficiency of propionyl-CoA carboxylase (PCC, EC 6.4.1.3), a biotin-dependent
enzyme that catalyzes the carboxylation of propionyl-CoA to D-methylmalonyl-CoA.
PCC is a heteropolymeric enzyme composed of alpha- and beta-subunits. A greater
heterogeneity is observed in the PCCA gene, while for the PCCB gene, a limited
number of mutations is responsible for the majority of the alleles characterized
in both Caucasian and Oriental populations. We identified eight Korean patients
with PA by organic acid analysis confirmed in five patients by the PCC enzyme
assay in the lymphoblasts. Two neonatal-onset patients showed undetectable PCC
activities while three cases with residual enzyme activities had relatively late
manifestations. In the molecular analysis, we identified five novel mutations,
Y439C, 1527del3, 1357insT, IVS12-8T-->A, and 31del10, and one known mutation,
T428I in PCCB gene. Alleleic frequency of T428I in Korean patients with PA was
56.3% in this study. Two neonatal-onset patients with null enzyme activities
were homozygotes with 1527del3 and T428I, respectively. This finding implies
that T428I and 1527del3 mutation could be responsible for their severe clinical
courses and null enzyme activities. The mRNA of PCCB gene in T428I and 1527del3
homozygotes were normal but in Western blot analysis, the betaPCC-subunit was
only absent in 1527del3 homozygote patient suggesting different molecular
pathology. Propionic acidemia (PA) is a recessive disorder caused by a deficiency of
propionyl-CoA carboxylase (PCC), a dodecameric enzyme composed of two different
proteins alpha-PCC and beta-PCC, nuclear encoded by the PCCA and PCCB genes,
respectively. Mutations in either gene cause PA and to date, up to 47 different
allelic variations in the PCCB gene have been identified in different
populations. In this work, we describe the expression studies of 18 PCCB
sequence changes in order to elucidate their functional consequences. We have
used a PCCB-deficient transformed fibroblast cell line to target the wild-type
and mutant proteins to their physiological situation, analysing the effect of
the mutations on PCC activity and protein stability. Of the 18 mutant proteins
tested for activity, those carrying the L17M and A497V substitutions showed an
activity similar to the wild-type one, which proves that these changes do not
have any effect on protein activity. The other 16 mutant proteins exhibited two
different functional behaviours, 3 retained substantial activity (K218R, R410W
and N536D), and the remaining 13 proteins showed null or very low activity.
Western blot analysis demonstrated instability only for the L519P, R512C and
G112D mutant proteins. We have proved the pathogenicity of R67S, R165Q and G112D
mutation in PCCB gene, expressed for the first time in this work. The
information derived from the expression analysis is discussed in the phenotype
and genotype context in order to improve the knowledge of this complex disease. A 4 1/2-year-old girl with a so far unremarkable medical history became comatose
during a simple infection. She showed severe metabolic acidosis without
elevation of lactate. In blood the branched-chain amino acids were increased. In
urine ketone-bodies, increased 3-OH-isovaleric and 3-OH propionic acid excretion
were detected, while methylmalonate was not found. The profile of acylcarnitines
revealed increased propionylcarnitine. Despite restriction of protein supply,
high-caloric nutrition, correction of acidosis, and supplementation of biotin
and carnitine, the girl died 2 days after admission due to arrhythmia of the
heart. In skin fibroblasts the activity of propionyl-coenzyme A carboxylase
(PCC) was markedly decreased. Mutation analysis confirmed the diagnosis of
propionic acidemia (PA) with compound heterozygosity for 2 new missense
mutations L417W/Q293E in the PCCA gene, with the mother carrying the Q293E and
the father the L417W mutation. Late-onset PA should be included in the
differential diagnosis of unclear coma. Determination of the acylcarnitines
using tandem mass spectrometry as well as organic acids in urine is recommended. In this work we analyze splicing mutations identified in propionic acidemia
patients to clarify their functional effects and their involvement in the
disease phenotype. Two mutations in the PCCA gene detected in homozygous
patients and involving consensus splice sequences (IVS21+3del4 and IVS22-2A>G)
were shown to produce some normal splicing in patients' cells, at very low
levels, which were quantitated by real-time PCR methods, and which presumably
are sufficient to moderate the phenotype. We have also analysed the effect of
mutations c.653A>G and IVS10-11del6 in the PCCB gene present in heterozygous
patients with mild phenotype. The c.653A>G mutation is located in the last codon
of exon 6 and interferes with the correct spliceosomal assembly activating a
cryptic splice site within exon 6, which leads to an in-frame six-nucleotide
deletion (delV217-K218). Minigene analysis and sequence-specific hybridization
probes using real-time PCR methods showed that no normally spliced transcript is
detectable in the patients' fibroblasts. The IVS10-11del6 mutation shortens the
polypyrimidine tract of the 3'-splice site of exon 11, resulting in exon
skipping. Some normal transcript is detectable by allele-specific hybridization
probes. These analyses suggest that, in some cases, the regulation of gene
splicing can potentially play an important role in human disease influencing
phenotypic parameters. Mutations in the PCCA or PCCB genes coding for alpha and beta subunits of
propionyl CoA carboxylase can cause propionic acidemia. To understand the
molecular basis of the intragenic complementation previously reported at the
PCCB locus, we now examine the complementation behaviour of four
carboxy-terminal and 11 amino-terminal naturally occurring mutant alleles both
using cell fusion and reconstructing the complementation event by transfecting
the mutant cDNAs to generate multimeric hybrid proteins. Alleles carrying
mutations p.R410W and p.W531X are able to complement with 10 out of 11
amino-terminal mutations assayed. Only the unstable p.R512C, p.L519P and p.G112D
mutants fail to complement. The results analyzed in the framework of the crystal
structure of the homologous 12S transcarboxylase from Propionibacterium
shermanii show that all mutant alleles studied are located at beta subunits
interfaces, complementing alleles at the inter-trimer interface, where the
catalysis probably happens, and non-complementing alleles at the intra-trimer
interface, probably disrupting the trimer formation. Our results also show a
remarkable stabilization effect when p.R410W is cotransfected with p.G246V. We
propose a model for intragenic complementation requiring the production of two
different beta subunits carrying carboxy and amino-terminal mutations that allow
regenerating functional active sites and in which a stabilization effect between
subunits could be relevant to ameliorate the biochemical phenotype of each
mutation separately. Propionic acidemia results from mutations in either of the two genes, PCCA or
PCCB, that encode the two subunits of the propionyl-CoA carboxylase (PCC)
enzyme. In this study, we report the identification and analysis of seven novel
splicing mutations involving consensus donor and acceptor splice sites. Most of
them were identified in patients with a Central Asian origin, and some present
in several alleles, probably reflecting founder effects. The functional
consequences of the splicing mutations were analyzed in patients' fibroblasts,
as well as transcript quantification using real-time PCR methods. In the PCCA
gene, two mutations were demonstrated to affect 5' splice sites (c.231+1G>C and
c.1209+3A>G) and two 3' acceptor splice sites (c.1210delG and c.1430G>T), all
causing skipping of the exons involved, with no detectable levels of normally
spliced transcript. In the PCCB gene, all three mutations involved 5' donor
splice sites-two affected exon 1 splicing (c.154_183+17del46 and c.183+2T>C),
the latter activating a cryptic splice site in intron 1, and the remaining
mutation (c.1498+2T>C) resulted in exon 14 skipping. The results highlight the
necessity to perform transcript analysis in addition to genomic DNA sequencing
to characterize the effect of splicing mutations and add relevant information on
the genetic epidemiology of the disease. Propionic acidemia is a metabolic disorder (OMIM 606054) caused by deficiency of
the propionyl-coenzyme A (CoA) carboxylase, which subsequently results in
accumulation of propionic acid. Patients may initially present with poor
feeding, vomiting, loss of appetite, hypotonia, and lethargy. Later, most
children will show different degrees of motor, social and language delay even
more serious medical problems, including heart abnormalities, seizures, coma,
and possibly death. Two siblings affected with propionic acidemia were screened
for putative mutations in PCCA and PCCB genes coding alpha and beta subunits of
propionyl-coenzyme A (CoA) carboxylase, respectively. Both patients had a
mild-severe form of propionic acidemia. The investigations using PCR, long-PCR,
array comparative genomic hybridization (aCGH), and sequencing techniques showed
a approximately 73kb deletion extending from intron 16 to intron 19 and an 18bp
insertion at the distal end of the deletion in PCCA gene. The deletion so far is
the largest gross change reported in the literature for the PCCA gene. Propionic acidemia (PA) is a metabolic disorder that causes mental retardation
and that can be fatal if untreated. PA is inherited in an autosomal recessive
fashion involving mutations in PCCA or PCCB encoding the alpha and beta subunits
of propionyl-CoA carboxylase (PCC). Current treatment is based on dietary
restriction of substrate amino acids, which attenuates symptoms. However,
patients still experience episodes of hyperammonemia that can cause progressive
neurologic damage. In this paper, we have tested gene therapy approaches to PA
in a stringent mouse model of PCCA deficiency, in which homozygous knockout mice
are born but die within 36 hr. In this work, we have delivered first-generation
and helper-dependent adenovirus serotype 5 (Ad5) vectors expressing the human
PCCA cDNA by intraperitoneal injection into newborn mice. Unmodified Ad5 vectors
mediated extensive transduction of the peritoneum with weak liver transduction
as determined by luciferase imaging and dsRed expression. In contrast,
modification of Ad5 with polyethylene glycol detargeted the virus from the
peritoneum and retargeted it for transduction in the liver. When vectors
expressing PCCA were injected, significant increases in life span were observed
for both the unmodified and polyethylene glycol (PEG)-modified Ad5 vectors.
However, this rescue was transient. Similarly, adeno-associated virus serotype
8-mediated transduction also produced only transient rescue. These data show
first proof of principle for gene therapy of PA and demonstrate the potential
utility of PEG to modify viral tropism in an actual gene therapy application. Mutations in either the PCCA or PCCB genes are responsible for propionic
acidemia (PA), one of the most frequent organic acidemias inherited in autosomal
recessive fashion. Most of the mutations detected to date in both genes are
missense. In the case of PCCA deficient patients, a high number of alleles
remain uncharacterized, some of them suspected to carry an exonic deletion. We
have now employed multiplex ligation probe amplification (MLPA) and long-PCR in
some cases to screen for genomic rearrangements in the PCCA gene in 20 patients
in whom standard mutation detection techniques had failed to complete genotype
analysis. Eight different deletions were found, corresponding to a frequency of
21.3% of the total PCCA alleles genotyped at our center. Two of the exonic
deletions were frequent, one involving exons 3-4 and another exon 23 although in
the first case two different chromosomal breakpoints were identified. Absence of
exons 3 and 4 which is also the consequence of the novel splicing mutation
c.231+1g>c present in two patients, presumably results in an in-frame deletion
covering 39 aminoacids, which was expressed in a eukaryotic system confirming
its pathogenicity. This work describes for the first time the high frequency of
large genomic deletions in the PCCA gene, which could be due to the
characteristics of the PCCA gene structure and its abundance in intronic
repetitive elements. Our data underscore the need of using gene dosage analysis
to complement routine genetic analysis in PCCA patients. Deficiency of propionyl CoA carboxylase (PCC), a dodecamer of alpha and beta
subunits, causes inherited propionic acidemia. We have studied, at the molecular
level, PCC in 54 patients from 48 families comprised of 96 independent alleles.
These patients of various ethnic backgrounds came from research centers and
hospitals in Germany, Austria and Switzerland. The thorough clinical
characterization of these patients was described in the accompanying paper
(Grünert et al. 2012). In all 54 patients, many of whom originated from
consanguineous families, the entire PCCB gene was examined by genomic DNA
sequencing and in 39 individuals the PCCA gene was also studied. In three
patients we found mutations in both PCC genes. In addition, in many patients
RT-PCR analysis of lymphoblast RNA, lymphoblast enzyme assays, and expression of
new mutations in E.coli were carried out. Eight new and eight previously
detected mutations were identified in the PCCA gene while 15 new and 13
previously detected mutations were found in the PCCB gene. One missense
mutation, p.V288I in the PCCB gene, when expressed in E.coli, yielded 134% of
control activity and was consequently classified as a polymorphism in the coding
region. Numerous new intronic polymorphisms in both PCC genes were identified.
This study adds a considerable amount of new molecular data to the studies of
this disease. |
Which protein phosphatase has been found to interact with the heat shock protein, HSP20? | Protein phosphatase-1 activity is regulated by two binding partners, inhibitor-1 and the small heat shock protein 20, Hsp20. Cell fractionation, coimmunoprecipitation, and coimmunolocalization studies, revealed an association between Hsp20 and PP1. Small heat shock protein 20 interacts with protein phosphatase-1 and enhances sarcoplasmic reticulum calcium cycling. | |
What is the risk in G-CSF treatment for severe congenital neutropenia? | Severe congenital neutropenia is a rare hematological condition causing severe chronic neutropenia. Treatment with the myeloid growth factor, granulocyte-colony stimulating factor (G-CSF) is usually effective, but the dose of G-CSF required to normalize blood neutrophils varies greatly. Ten to thirty percent of the patients evolve to develop acute myeloid leukemia or myelodysplastic syndromes, necessitating careful clinical monitoring. | BACKGROUND AND OBJECTIVES: The two main complications of severe chronic
neutropenia are fatal sepsis and myelodysplasia/acute leukemia (MDS/AL).
Granulocyte colony-stimulating factor (G-CSF) therapy has significantly reduced
the frequency and severity of infections, but its possible influence on the risk
of maligcy is not known.
DESIGN AND METHODS: The French Severe Chronic Neutropenia (SCN) Registry has
prospectively collected data since 1994 on 231 patients with various forms of
SCN, namely severe congenital neutropenia (n=101), cyclic neutropenia (n=60),
glycogen storage disease type Ib (GSDIb) (n=15) and Shwachman-Diamond syndrome
(SDS)(n=55). The median overall follow-up is 11.1 years. Parameters of exposure
to G-CSF therapy, such as the time averaged dose, follow up after first use of
G-CSF, and the cumulative dose, have been recorded.
RESULTS: Eight septic deaths occurred, of which 6 among patients with severe
congenital neutropenia and 2 in patients with cyclic neutropenia; none of these
8 patients was receiving G-CSF therapy. No septic deaths occurred during G-CSF
therapy. Thirteen cases of MDS/AL were recorded. The cumulative incidence of
MDS/AL was 2.7% (SD 1.3%) at 10 years and 8.1% (SD 2.7%) at 20 years.
INTERPRETATION AND CONCLUSIONS: Risk factors for MDS/AL were the diagnostic
category, the severity of neutropenia, younger age at diagnosis, and strong
exposure to G-CSF. MDS/AL only occurred in patients with severe congenital
neutropenia and SDS. Owing to their particular susceptibility to infections,
patients with severe congenital neutropenia had the strongest exposure to G-CSF;
the risk of leukemia increased with the degree of G-CSF exposure in this
subgroup. Granulocyte colony-stimulating factor (G-CSF) has been used in the clinic for
more than 2 decades to treat congenital and acquired neutropenias and to reduce
febrile neutropenia before or during courses of intensive cytoreductive therapy.
In addition, healthy stem cell donors receive short-term treatment with G-CSF
for mobilization of hematopoietic stem cells. G-CSF has also been applied in
priming strategies designed to enhance the sensitivity of leukemia stem cells to
cytotoxic agents, in protocols aimed to induce their differentiation and
accompanying growth arrest and cell death, and in severe aplastic anemia and
myelodysplastic syndrome (MDS) to alleviate anemia. The potential adverse
effects of G-CSF administration, particularly the risk of maligt
transformation, have fueled ongoing debates, some of which can only be settled
in follow-up studies extending over several decades. This specifically applies
to children with severe congenital neutropenia who receive lifelong treatment
with G-CSF and in which the high susceptibility to develop MDS and acute myeloid
leukemia (AML) has now become a major clinical concern. Here, we will highlight
some of the controversies and challenges regarding the clinical application of
G-CSF and discuss a possible role of G-CSF in maligt transformation,
particularly in patients with neutropenia harboring mutations in the gene
encoding the G-CSF receptor. In severe congenital neutropenia (SCN), long-term therapy with granulocyte
colony-stimulating factor (G-CSF) has reduced mortality from sepsis, revealing
an underlying predisposition to myelodysplastic syndrome and acute myeloid
leukaemia (MDS/AML). We have reported the early pattern of evolution to MDS/AML,
but the long-term risk remains uncertain. We updated a prospective study of 374
SCN patients on long-term G-CSF enrolled in the Severe Chronic Neutropenia
International Registry. Long-term, the annual risk of MDS/AML attained a plateau
(2.3%/year after 10 years). This risk now appears similar to, rather than higher
than, the risk of AML in Fanconi anaemia and dyskeratosis congenita. 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. Severe congenital neutropenia (SCN) is a BM failure syndrome with a high risk of
progression to acute myeloid leukemia (AML). The underlying genetic changes
involved in SCN evolution to AML are largely unknown. We obtained serial
hematopoietic samples from an SCN patient who developed AML 17 years after the
initiation of G-CSF treatment. Next- generation sequencing was performed to
identify mutations during disease progression. In the AML phase, we found 12
acquired nonsynonymous mutations. Three of these, in CSF3R, LLGL2, and ZC3H18,
co-occurred in a subpopulation of progenitor cells already in the early SCN
phase. This population expanded over time, whereas clones harboring only CSF3R
mutations disappeared from the BM. The other 9 mutations were only apparent in
the AML cells and affected known AML-associated genes (RUNX1 and ASXL1) and
chromatin remodelers (SUZ12 and EP300). In addition, a novel CSF3R mutation that
conferred autonomous proliferation to myeloid progenitors was found. We conclude
that progression from SCN to AML is a multistep process, with distinct mutations
arising early during the SCN phase and others later in AML development. The
sequential gain of 2 CSF3R mutations implicates abnormal G-CSF signaling as a
driver of leukemic transformation in this case of SCN. |
Neurostimulation of which nucleus is used for treatment of dystonia? | Neurostimulation of globus pallidus internus is effective for treatment of dystonia. Ventral intermediate thalamic nucleus has also been tested for neurostimulation in dystonia patients. | We report on the effects of bilateral neurostimulation of the ventral
intermediate thalamic nucleus (VIM) in a patient with medically intractable and
progressing inherited myoclonus dystonia syndrome (IMDS). Postoperatively, the
patient improved by approximately 80% on the modified version of a myoclonus
score without any significant change in the dystonic symptoms. This suggests
that neurostimulation of the VIM may be an effective treatment for myoclonus in
pharmacologically intractable IMDS. Despite that deep brain stimulation (DBS) of the globus pallidus internus (GPi)
is emerging as the favored intervention for patients with medically intractable
dystonia, the pathophysiological mechanisms of dystonia are largely unclear. In
eight patients with primary dystonia who were treated with bilateral chronic
pallidal stimulation, we correlated symptom-related electromyogram (EMG)
activity of the most affected muscles with the local field potentials (LFPs)
recorded from the globus pallidus electrodes. In 5 dystonic patients with mobile
involuntary movements, rhythmic EMG bursts in the contralateral muscles were
coherent with the oscillations in the pallidal LFPs at the burst frequency. In
contrast, no significant coherence was seen between EMG and LFPs either for the
sustained activity separated out from the compound EMGs in those 5 cases, or in
the EMGs in 3 other cases without mobile involuntary movements and rhythmic EMG
bursts. In comparison with the resting condition, in both active and passive
movements, significant modulation in the GPi LFPs was seen in the range of 8-16
Hz. The finding of significant coherence between GPi oscillations and rhythmic
EMG bursts but not sustained tonic EMG activity suggests that the synchronized
pallidal activity may be directly related to the rhythmic involuntary movements.
In contrast, the sustained hypertonic muscle activity may be represented by less
synchronized activity in the pallidum. Thus, the pallidum may play different
roles in generating different components of the dystonic symptom complex. OBJECTIVE: To assess the effects of bilateral pallidal deep brain stimulation
(DBS) on mood and cognitive performance in patients with dystonia before surgery
(at baseline, while patients received their usual treatment) and 12 months
postoperatively (while patients received neurostimulation and their medications)
in a multicenter prospective study.
METHODS: Twenty-two patients with primary generalized dystonia were evaluated
with tests focused on executive functions. The authors considered the patients'
severe disability and selected the following tests: Raven Progressive Matrices
38, Similarities and Arithmetic subtests of the Wechsler Adult Intelligence
Scale-R, Grober and Buschke, Wisconsin Card Sorting Test (WCST), verbal fluency,
Trail Making Test, and the Beck Depression Inventory. Median age at surgery was
30 years (range = 14 to 54 years), median duration of disease was 18.5 years
(range = 4 to 37 years).
RESULTS: Before surgery, no patients showed cognitive decline or depression. The
surgical procedure appeared to be benign cognitively. One year after surgery,
free recall improved. There was a significant reduction in the number of errors
in the WCST. No behavioral or mood changes were found.
CONCLUSIONS: Bilateral pallidal stimulation has a good benefit-to-risk ratio as
it did not negatively affect cognitive performance and mood in primary dystonia,
while a significant motor improvement was obtained. Moreover, a significant mild
improvement in executive functions was observed, which may have been related
either to the surgical treatment or to the marked decrease in anticholinergic
drugs. BACKGROUND: Neurostimulation of the internal globus pallidus has been shown to
be effective in reducing symptoms of primary dystonia. We compared this surgical
treatment with sham stimulation in a randomized, controlled clinical trial.
METHODS: Forty patients with primary segmental or generalized dystonia received
an implanted device for deep-brain stimulation and were randomly assigned to
receive either neurostimulation or sham stimulation for 3 months. The primary
end point was the change from baseline to 3 months in the severity of symptoms,
according to the movement subscore on the Burke-Fahn-Marsden Dystonia Rating
Scale (range, 0 to 120, with higher scores indicating greater impairment). Two
investigators who were unaware of treatment status assessed the severity of
dystonia by reviewing videotaped sessions. Subsequently, all patients received
open-label neurostimulation; blinded assessment was repeated after 6 months of
active treatment.
RESULTS: Three months after randomization, the change from baseline in the mean
(+/-SD) movement score was significantly greater in the neurostimulation group
(-15.8+/-14.1 points) than in the sham-stimulation group (-1.4+/-3.8 points,
P<0.001). During the open-label extension period, this improvement was sustained
among patients originally assigned to the neurostimulation group, and patients
in the sham-stimulation group had a similar benefit when they switched to active
treatment. The combined analysis of the entire cohort after 6 months of
neurostimulation revealed substantial improvement in all movement symptoms
(except speech and swallowing), the level of disability, and quality of life, as
compared with baseline scores. A total of 22 adverse events occurred in 19
patients, including 4 infections at the stimulator site and 1 lead dislodgment.
The most frequent adverse event was dysarthria.
CONCLUSIONS: Bilateral pallidal neurostimulation for 3 months was more effective
than sham stimulation in patients with primary generalized or segmental
dystonia. (ClinicalTrials.gov number, NCT00142259 [ClinicalTrials.gov].). As part of the first randomized, sham-stimulation controlled trial on deep brain
stimulation (DBS) in primary segmental or generalized dystonia, health-related
quality of life (HRQoL) was assessed by SF-36. After the 3-month sham-controlled
phase, significant HRQoL improvement occurred only in the active-stimulation
group. The open-label extension phase resulted in a significant improvement in
all SF-36 domains following 6 months of neurostimulation. These results
demonstrate a favorable impact of DBS on HRQoL in primary dystonia. BACKGROUND: Cerebral palsy (CP) with dystonia-choreoathetosis is a common cause
of disability in children and in adults, and responds poorly to medical
treatment. Bilateral pallidal deep brain stimulation (BP-DBS) of the globus
pallidus internus (GPi) is an effective treatment for primary dystonia, but the
effect of this reversible surgical procedure on dystonia-choreoathetosis CP,
which is a subtype of secondary dystonia, is unknown. Our aim was to test the
effectiveness of BP-DBS in adults with dystonia-choreoathetosis CP.
METHODS: We did a multicentre prospective pilot study of BP-DBS in 13 adults
with dystonia-choreoathetosis CP who had no cognitive impairment, little
spasticity, and only slight abnormalities of the basal ganglia on MRI. The
primary endpoint was change in the severity of dystonia-choreoathetosis after 1
year of neurostimulation, as assessed with the Burke-Fahn-Marsden dystonia
rating scale. The accuracy of surgical targeting to the GPi was assessed masked
to the results of neurostimulation. Analysis was by intention to treat.
FINDINGS: The mean Burke-Fahn-Marsden dystonia rating scale movement score
improved from 44.2 (SD 21.1) before surgery to 34.7 (21.9) at 1 year
post-operatively (p=0.009; mean improvement 24.4 [21.1]%, 95% CI 11.6-37.1).
Functional disability, pain, and mental health-related quality of life were
significantly improved. There was no worsening of cognition or mood. Adverse
events were related to stimulation (arrest of the stimulator in one patient, and
an adjustment to the current intensity in four patients). The optimum
therapeutic target was the posterolateroventral region of the GPi. Little
improvement was seen when the neurostimulation diffused to adjacent structures
(mainly to the globus pallidus externus [GPe]).
INTERPRETATION: Bilateral pallidal neurostimulation could be an effective
treatment option for patients with dystonia-choreoathetosis CP. However, given
the heterogeneity of motor outcomes and the small sample size, results should be
interpreted with caution. The optimum placement of the leads seemed to be a
crucial, but not exclusive, factor that could affect a good outcome.
FUNDING: National PHRC; Cerebral Palsy Foundation: Fondation Motrice/APETREIMC;
French INSERM Dystonia National Network; Medtronic. OBJECTIVES: to provide a revised version of earlier guidelines published in
2006.
BACKGROUND: primary dystonias are chronic and often disabling conditions with a
widespread spectrum mainly in young people.
DIAGNOSIS: primary dystonias are classified as pure dystonia, dystonia plus or
paroxysmal dystonia syndromes. Assessment should be performed using a validated
rating scale for dystonia. Genetic testing may be performed after establishing
the clinical diagnosis. DYT1 testing is recommended for patients with primary
dystonia with limb onset before age 30, and in those with an affected relative
with early-onset dystonia. DYT6 testing is recommended in early-onset or
familial cases with cranio-cervical dystonia or after exclusion of DYT1.
Individuals with early-onset myoclonus should be tested for mutations in the
DYT11 gene. If direct sequencing of the DYT11 gene is negative, additional gene
dosage is required to improve the proportion of mutations detected. A levodopa
trial is warranted in every patient with early-onset primary dystonia without an
alternative diagnosis. In patients with idiopathic dystonia, neurophysiological
tests can help with describing the pathophysiological mechanisms underlying the
disorder.
TREATMENT: botulinum toxin (BoNT) type A is the first-line treatment for primary
cranial (excluding oromandibular) or cervical dystonia; it is also effective on
writing dystonia. BoNT/B is not inferior to BoNT/A in cervical dystonia.
Pallidal deep brain stimulation (DBS) is considered a good option, particularly
for primary generalized or cervical dystonia, after medication or BoNT have
failed. DBS is less effective in secondary dystonia. This treatment requires a
specialized expertise and a multidisciplinary team. Deep brain stimulation (DBS) is the technique of neurostimulation of deep brain
structures for the treatment of conditions such as essential tremor, dystonia,
Parkinson's disease and chronic pain syndromes. The procedure uses implanted
deep brain stimulation electrodes connected to extension leads and an
implantable pulse generator (IPG). Hardware failure related to the DBS procedure
is not infrequent, and includes electrode migration and disconnection. We
describe a patient who received bilateral globus pallidus internus DBS for
dystonia with initially good clinical response, but the device eventually
failed. Radiographs showed multiple twisting of the extension leads with
disconnection from the brain electrodes and a diagnosis of Twiddler's syndrome
was made. Twiddler's syndrome was first described in patients with cardiac
pacemakers. Patients with mental disability, elderly and obese patients are at
increased risk. Twiddler's syndrome should be suspected whenever there is a
failure of the DBS device to relieve symptoms previously responsive to
stimulation. Surgical correction is usually required. BACKGROUND: Severe forms of primary dystonia are difficult to manage medically.
We assessed the safety and efficacy of pallidal neurostimulation in patients
with primary generalised or segmental dystonia prospectively followed up for 5
years in a controlled multicentre trial.
METHODS: In the parent trial, 40 patients were randomly assigned to either sham
neurostimulation or neurostimulation of the internal globus pallidus for a
period of 3 months and thereafter all patients completed 6 months of active
neurostimulation. 38 patients agreed to be followed up annually after the
activation of neurostimulation, including assessments of dystonia severity,
pain, disability, and quality of life. The primary endpoint of the 5-year
follow-up study extension was the change in dystonia severity at 3 years and 5
years as assessed by open-label ratings of the Burke-Fahn-Marsden dystonia
rating scale (BFMDRS) motor score compared with the preoperative baseline and
the 6-month visit. The primary endpoint was analysed on an intention-to-treat
basis. The original trial is registered with ClinicalTrials.gov (NCT00142259).
FINDINGS: An intention-to-treat analysis including all patients from the parent
trial showed significant improvements in dystonia severity at 3 years and 5
years compared with baseline, which corresponded to -20·8 points (SD 17·1;
-47·9%; n=40) at 6 months; -26·5 points (19·7; -61·1%; n=31) at 3 years; and
-25·1 points (21·3; -57·8%; n=32). The improvement from 6 months to 3 years
(-5·7 points [SD 8·4]; -34%) was significant and sustained at the 5-year
follow-up (-4·3 [10·4]). 49 new adverse events occurred between 6 months and 5
years. Dysarthria and transient worsening of dystonia were the most common
non-serious adverse events. 21 adverse events were rated serious and were almost
exclusively device related. One patient attempted suicide shortly after the
6-month visit during a depressive episode. All serious adverse events resolved
without permanent sequelae.
INTERPRETATION: 3 years and 5 years after surgery, pallidal neurostimulation
continues to be an effective and relatively safe treatment option for patients
with severe idiopathic dystonia. This long-term observation provides further
evidence in favour of pallidal neurostimulation as a first-line treatment for
patients with medically intractable, segmental, or generalised dystonia.
FUNDING: Medtronic. BACKGROUND: Deep brain stimulation of the internal pallidum (GPi-DBS) is
effective for various types of drug-refractory primary dystonias. Rare clinical
forms as dystonic camptocormia may profit but available data are scarce.
METHODS: We here report on a retrospective clinical assessment of three patients
with primary dystonic camptocormia treated with GPi-DBS.
RESULTS: All three patients showed marked response to bilateral GPi-DBS within
days to weeks after surgery which was preserved in the long-term (38-45 months
after implantation: mean improvement 82% as rated on the Burke Fahn Marsden
Dystonia Rating Scale, 89% in the subitem "trunk"). Two patients developed mild
stimulation induced speech problems (stuttering or dysarthria) which resolved
with reprogramming or were acceptable in return for the control of dystonic
symptoms.
CONCLUSIONS: The diagnosis and treatment of camptocormia will continue to
require expert knowledge in movement and neuromuscular disorders, but DBS may
expand treatment options in this difficult patient population. Some neurological conditions require admission to an intensive care unit (ICU)
where deep sedation and mechanical ventilation are administered to improve the
patient's condition. Nevertheless, these treatments are not always helpful in
disease control. At this stage, deep brain stimulation (DBS) could become a
viable alternative in the treatment of critical neurological conditions with
long-lasting clinical benefit. The value of deep brain stimulation has been
investigated in the treatment of patients who had undergone surgical electrode
implants as an emergency procedure to treat acute life-threatening conditions
requiring admission to neurological ICU (NICU). A before-and-after perspective
study was examined of seven patients who were treated with DBS for status
dystonicus (SD) and post-stroke severe hemiballismus. Bilateral globus pallidus
internus (GPi) DBS was performed in five SD patients and unilateral ventralis
oralis anterior and posterior (Voa/Vop) nucleus of the thalamus DBS in two
post-stroke hemiballismus patients. Bilateral GPi-DBS allowed SD resolution in a
time lapse varying from 1 week to 3 months. No clear improvements compared to
the baseline clinical condition were observed. Unilateral Voa/Vop-DBS
intervention controlled hemiballismus after 10 h, and the patient was discharged
in 2 days. The other patient was transferred from the NICU to the neurosurgery
ward after 13 days. No surgical complications were observed in any of the above
procedures. Neurostimulation procedures could represent a valuable choice in
critical care conditions, when involuntary movements are continuous,
life-threatening and refractory to intensive care procedures. DBS is feasible,
safe and effective in selected cases. |
Which myosin isozymes are located within the pericuticular necklace of the hair cell? | The hair cell is located in the inner ear, a tissue that is particularly reliant on actin-rich structures and unconventional myosin isozymes. Within the pericuticular necklace, a domain of the hair cell, certain unconventional myosin isozymes are located, namely myosins-Ibeta, myosin-VI, and myosin-VIIa. | To understand how cells differentially use the dozens of myosin isozymes present
in each genome, we examined the distribution of four unconventional myosin
isozymes in the inner ear, a tissue that is particularly reliant on actin-rich
structures and unconventional myosin isozymes. Of the four isozymes, each from a
different class, three are expressed in the hair cells of amphibia and mammals.
In stereocilia, constructed of cross-linked F-actin filaments, myosin-Ibeta is
found mostly near stereociliary tips, myosin-VI is largely absent, and
myosin-VIIa colocalizes with crosslinks that connect adjacent stereocilia. In
the cuticular plate, a meshwork of actin filaments, myosin-Ibeta is excluded,
myosin-VI is concentrated, and modest amounts of myosin-VIIa are present. These
three myosin isozymes are excluded from other actin-rich domains, including the
circumferential actin belt and the cortical actin network. A member of a fourth
class, myosin-V, is not expressed in hair cells but is present at high levels in
afferent nerve cells that innervate hair cells. Substantial amounts of
myosins-Ibeta, -VI, and -VIIa are located in a pericuticular necklace that is
largely free of F-actin, squeezed between (but not associated with) actin of the
cuticular plate and the circumferential belt. Our localization results suggest
specific functions for three hair-cell myosin isozymes. As suggested previously,
myosin-Ibeta probably plays a role in adaptation; concentration of myosin-VI in
cuticular plates and association with stereociliary rootlets suggest that this
isozyme participates in rigidly anchoring stereocilia; and finally,
colocalization with cross-links between adjacent stereocilia indicates that
myosin-VIIa is required for the structural integrity of hair bundles. The proper expression and function of several unconventional myosins are
necessary for inner-ear function. Mutations in MYO7A and MYO15 cause deafness in
humans, and mice. Whereas mutations in Myo6 cause inner-ear abnormalities in
mice, as yet no human deafness has been found to the result of mutations in
MYO6. In the mammalian inner ear there are at least nine different
unconventional myosin isozymes expressed. Myosin 1 beta, VI, VIIa and probably
XV are all expressed within a single cell in the inner ear, the hair cell. The
myosin isozymes expressed in the hair cell all have unique domains of expression
and in some areas, such as the pericuticular necklace, several domains overlap.
This suggests that these myosins all have unique functions and that all are
individually targeted within the hair cell. The mouse is proving to be a useful
model organism for studying both human deafness and elucidating the normal
functions of unconventional myosins in vivo. Myosin isozymes are essential for hair cells, the sensory cells of the inner
ear. Because a myosin-I subfamily member may mediate adaptation of
mechanoelectrical transduction, we examined expression of all eight myosin-I
isozymes in rodent auditory and vestibular epithelia. Using RT-PCR, we found
prominent expression of three isozymes, Myo1b (also known as myosin-Ia or myr
1). Myo1c (myosin-Ib or myr 2). and Myo1e (myr 3). By contrast, Myo1a
(brush-border myosin-I), Myo1d (myosin lg or myr 4). Myo1f, Myo1g, and Myo1h
were less readily amplified. Because sequence analysis demonstrated that the
RT-PCR products encoded the appropriate isozymes, this represents the first
demonstration of expression of all eight mouse myosin-I genes. Using
immunocytochemistry with isozyme-selective antibodies, we found that Myo1b was
located at apical surfaces of supporting cells that surround hair cells in
auditory epithelia of postnatal rats. In vestibular epithelia, Myo1b was present
in a ring within the apical pole of the hair cell. In both cases, expression was
prominent only immediately after birth. Myo1e was found in hair cells of the
auditory and vestibular epithelia; this isozyme was enriched in the cuticular
plate, the actin meshwork that anchors the stereocilia. Myo1c was found in
hair-cell stereocilia, concentrated towards their tips; we confirmed this
localization by using adenovirus vectors to direct expression of a GFP-Myo1c
tail fusion protein; this fusion protein localized to plasma membranes, often
concentrating at stereociliary tips. Myo1c therefore remains the myosin isozyme
best localized to carry out transducer adaptation. Hair cells of the inner ear are damaged by intense noise, aging, and
aminoglycoside antibiotics. Gentamicin causes oxidative damage to hair cells,
inducing apoptosis. In mammals, hair cell loss results in a permanent deficit in
hearing and balance. In contrast, avians can regenerate lost hair cells to
restore auditory and vestibular function. This study examined the changes of
myosin VI and myosin VIIa, two unconventional myosins that are critical for
normal hair cell formation and function, during hair cell death and
regeneration. During the late stages of apoptosis, damaged hair cells are
ejected from the sensory epithelium. There was a 4-5-fold increase in the
labeling intensity of both myosins and a redistribution of myosin VI into the
stereocilia bundle, concurrent with ejection. Two separate mechanisms were
observed during hair cell regeneration. Proliferating supporting cells began DNA
synthesis 60 hours after gentamicin treatment and peaked at 72 hours
postgentamicin treatment. Some of these mitotically produced cells began to
differentiate into hair cells at 108 hours after gentamicin (36 hours after
bromodeoxyuridine (BrdU) administration), as demonstrated by the colabeling of
myosin VI and BrdU. Myosin VIIa was not expressed in the new hair cells until
120 hours after gentamicin. Moreover, a population of supporting cells expressed
myosin VI at 78 hours after gentamicin treatment and myosin VIIa at 90 hours.
These cells did not label for BrdU and differentiated far too early to be of
mitotic origin, suggesting they arose by direct transdifferentiation of
supporting cells into hair cells. |
Which is the treatment strategy followed in spinocerebellar ataxia type 3 for CAG removal? | The novel treatment strategy proposed for treatment of Spinocerebellar ataxia type 3 is the removal of the toxic polyglutamine repeat from the ataxin-3 protein through antisense oligonucleotide-mediated exon skipping while maintaining important wild type functions of the protein. | Spinocerebellar ataxia type 3 is caused by a polyglutamine expansion in the
ataxin-3 protein, resulting in gain of toxic function of the mutant protein. The
expanded glutamine stretch in the protein is the result of a CAG triplet repeat
expansion in the penultimate exon of the ATXN3 gene. Several gene silencing
approaches to reduce mutant ataxin-3 toxicity in this disease aim to lower
ataxin-3 protein levels, but since this protein is involved in deubiquitination
and proteasomal protein degradation, its long-term silencing might not be
desirable. Here, we propose a novel protein modification approach to reduce
mutant ataxin-3 toxicity by removing the toxic polyglutamine repeat from the
ataxin-3 protein through antisense oligonucleotide-mediated exon skipping while
maintaining important wild type functions of the protein. In vitro studies
showed that exon skipping did not negatively impact the ubiquitin binding
capacity of ataxin-3. Our in vivo studies showed no toxic properties of the
novel truncated ataxin-3 protein. These results suggest that exon skipping may
be a novel therapeutic approach to reduce polyglutamine-induced toxicity in
spinocerebellar ataxia type 3. |
Where is the angiogenin binding element located? | Angiogenin binds to CT repeats that are abundant in the nontranscribed region of the ribosomal RNA gene. An angiogenin-binding DNA sequence (CTCTCTCTCTCTCTCTCCCTC) has been identified and designated angiogenin-binding element (ABE). | Specific binding of angiogenin (ANG) to calf pulmonary artery endothelial cells
was demonstrated. Cellular binding at 4 degrees C of 125I-labeled human
recombit ANG was time and concentration dependent, reversible, and saturable
in the presence of increasing amounts of the unlabeled molecules. The
interaction was shown to be specific since a large excess of unlabeled ANG
reduced labeled ANG binding by 80%, whereas similar doses of RNase A, a
structurally related protein, had no effect. Scatchard analyses of binding data
revealed two apparent components. High-affinity sites with an apparent
dissociation constant of 5 x 10(-9) M were shown to represent cell-specific
interactions. The second component, comprising low-affinity/high-capacity sites
with an apparent dissociation constant of 0.2 x 10(-6) M, was essentially
associated with pericellular components. High-affinity ANG binding sites varied
with cell density and were found on other endothelial cells from bovine aorta,
cornea, and adrenal cortex capillary but not on Chinese hamster lung
fibroblasts. Divalent copper, a modulator of angiogenesis, was found to induce a
severalfold increase in specific cell-bound radioactivity. Placental
ribonuclease inhibitor, a tight-binding inhibitor of both ribonucleolytic and
angiogenic activities of ANG, abolished 125I-labeled human recombit ANG
binding only in the absence of copper. The base cleavage specificity of angiogenin toward naturally occurring
polyribonucleotides has been determined by using rapid RNA sequencing
technology. With 5S RNAs from Saccharomyces cerevisiae and Escherichia coli,
angiogenin cleaves phosphodiester bonds exclusively at cytidylic or uridylic
residues, preferably when the pyrimidines are followed by adenine. However, not
all of the existent pyrimidine bonds in the 5S RNAs are cleaved, likely owing to
elements of structure in the substrate. Despite the high degree of sequence
homology between angiogenin and ribonuclease A (RNase A), which includes all
three catalytic as well as substrate binding residues, the cleavage patterns
with natural RNAs are unique to each enzyme. Angiogenin significantly hydrolyzes
certain bonds that are not appreciably attacked by RNase A and vice versa. The
different cleavage specificities of angiogenin and RNase A may account for the
fact that the former is angiogenic while the latter is not. In earlier work, we demonstrated that 5'-CG-3' methylation inhibits the
transcriptional activity of human Alu elements associated with the alpha
1-globin and the angiogenin genes in a cell-free transcription system from HeLa
nuclear extracts. These studies have been extended to different Alu sequences
and to investigations on the mechanism involved in transcriptional silencing by
methylation. By comparing the results of DNase I and dimethyl sulfate (DMS) in
vitro footprinting on a consensus sequence in the RNA polymerase III promoter
control B region between the unmethylated and the 5'-CG-3' methylated B box,
evidence has been adduced for effects of 5'-CG-3' methylation on the interaction
of specific nuclear proteins with DNA sequences in the B control region of the
Alu elements. These results are consistent with the interpretation that the
5'-CG-3' methylation interferes with the binding of proteins that are essential
for the function of the B control region in these RNA polymerase III-transcribed
elements, and that promoter methylation thus inhibits transcription. Angiogenin undergoes nuclear translocation in endothelial and smooth muscle
cells where it accumulates in the nucleolus and binds to DNA. Nuclear
translocation of angiogenin is necessary for its biological activity and is
mediated by an endocytotic pathway that is independent of the microtubule system
and lysosomal processing. Because the nucleolus is a subnuclear organelle
containing clusters of transcriptionally active ribosomal RNA genes, we studied
the binding of angiogenin to the intergenic spacer of the ribosomal RNA gene
where many of the transcription regulatory elements are located. Here we report
that angiogenin binds to CT repeats that are abundant in the nontranscribed
region of the ribosomal RNA gene. An angiogenin-binding DNA sequence
(CTCTCTCTCTCTCTCTCCCTC) has been identified and designated angiogenin-binding
element (ABE). ABE binds angiogenin specifically and exhibits
angiogenin-dependent promoter activity in a luciferase reporter system. CT
repeats, or inverted GA box, which are abundantly distributed in the eukaryotic
genome and are often located in the 5'-flanking region, have been implicated in
regulating gene expression. We have previously shown that angiogenin stimulates
rRNA synthesis. The present results suggest that the nuclear function of
angiogenin may not only be related to rRNA production but also play a role in
regulating expression of genes containing CT repeats. Angiogenin (ANG) undergoes nuclear translocation and promotes ribosomal RNA
(rRNA) transcription thereby enhancing cell growth and proliferation. However,
the mode of action of ANG in stimulating rRNA transcription is unclear. Here, we
show that ANG enhances the formation of RNA polymerase I (Pol I) pre-initiation
complex at the ribosomal DNA (rDNA) promoter. ANG binds at the upstream control
element (UCE) of the promoter and enhances promoter occupancy of RNA Pol I as
well as the selectivity factor SL1 components TAFI 48 and TAFI 110. We also show
that ANG increases the number of actively transcribing rDNA by epigenetic
activation through promoter methylation and histone modification. ANG binds to
histone H3, inhibits H3K9 methylation, and activates H3K4 methylation as well as
H4 acetylation at the rDNA promoter. These data suggest that one of the
mechanisms by which ANG stimulates rRNA transcription is through an epigenetic
activation of rDNA promoter. |
Which proteins cause cytoplasmic sequestration of NF-kB? | In unstimulated cells, NF-kB transcription factors are retained in the cytoplasm with the inhibitory activity of I-kBs, Sef, NF-kB1 (p105) and NF-kB2 (p100). | The human T-cell leukemia virus type I Tax protein transforms T cells through
induced expression of many cellular genes, including those encoding the
growth-related proteins interleukin 2 and the alpha chain of its receptor.
Induction of these genes is mediated, at least in part, through Tax-dependent
posttranslational activation of NF-kappa B, typically heterodimers of p50
(NF-kappa B1) and p65 (RelA). The preexisting NF-kappa B proteins are retained
in the cytoplasm of cells by association with inhibitory
ankyrin-motif-containing I kappa B proteins, primarily I kappa B-alpha but also
including the precursor proteins p105 (NF-kappa B1) and p100 (NF-kappa B2). Here
we demonstrate the existence of a previously undescribed multimeric cytoplasmic
complex in which NF-kappa B dimers are associated with the p100 inhibitor in a
manner dependent on the precursor protein's ankyrin domain. We also demonstrate
an antagonistic effect of the Tax protein on the cytoplasmic sequestration
function of p100; this in turn leads to nuclear translocation of NF-kappa B
dimers liberated from multimeric complexes. Tax may exert these effects through
the physical association with p100. Tax also relieves the p100-mediated
inhibition of DNA binding by p50-p65 heterodimers in vitro. The results
demonstrate a mechanism by which Tax may activate NF-kappa B in T cells. The viral Tax protein, which is encoded by human T-cell leukaemia virus HTLV-I,
activates nuclear translocation of the NF-kappa B/Rel transcription factors and
relieves cytoplasmic sequestration of RelA and Rel by heterodimerization with
NF-kappa B1/p1O5 (refs 1,2). Proteolytic maturation of this precursor protein is
performed by the proteasome complex. Here we show that Tax binds specifically to
two subunits of the 20S proteasome, HsN3 and HC9. This interaction is weakened
with HsN3 and lost for HC9 when a mutant of Tax is substituted that is
selectively defective for NF-kappa B activation. Immunoprecipitation shows that
p1O5 binds weakly to HC9 and that this interaction is reinforced by Tax. No
bridging function of Tax between p1O5 and HsN3 was observed. From these results,
we propose that Tax accelerates the proteolytic maturation of P105 by favouring
its anchorage to the proteasome. The subunit proteins p50 and p65 of the transcription factor NF-kappa B
inhibitory protein were immunocytochemically identified and mapped in rat brain.
The p65 subunit was localized to the cytoplasm of neurons in the lateral
hypothalamus and colocalized with alpha-MSH in neurons identified as the alpha-2
component of the alpha-MSH system. The p50 subunit protein was distributed
throughout the neocortex, basal ganglia, thalamic, and hypothalamic nuclei, and
certain nuclei of the pons and medulla. The I-kappa B protein, which is
necessary for the cytoplasmic sequestration of the NF-kappa B transcription
factor complex, was identified specifically in regions of limbic, hypothalamic,
and autonomic nuclei. p105, also known as NF-kappaB1, is an atypical IkappaB molecule with a
multi-domain organization distinct from other prototypical IkappaBs, like
IkappaBalpha and IkappaBbeta. To understand the mechanism by which p105 binds
and inhibits NF-kappaB, we have used both p105 and its C-terminal inhibitory
segment known as IkappaBgamma for our study. We show here that one IkappaBgamma
molecule binds to NF-kappaB dimers wherein at least one NF-kappaB subunit is
p50. We suggest that the obligatory p50 subunit in IkappaBgamma.NF-kappaB
complexes is equivalent to the N-terminal p50 segment in all p105.NF-kappaB
complexes. The nuclear localization signal (NLS) of the obligatory p50 subunit
is masked by IkappaBgamma, whereas the NLS of the nonobligatory NF-kappaB
subunit is exposed. Thus, the global binding mode of all IkappaB.NF-kappaB
complexes seems to be similar where one obligatory (or specific) NF-kappaB
subunit makes intimate contact with IkappaB and the nonobligatory (or
nonspecific) subunit is bound primarily through its ability to dimerize. In the
case of IkappaBalpha and IkappaBbeta, the specific NF-kappaB subunit in the
complex is p65. In contrast to IkappaBalpha.NF-kappaB complexes, where the
exposed NLS of the nonspecific subunit imports the complex to the nucleus,
p105.NF-kappaB and IkappaBgamma.NF-kappaB complexes are cytoplasmic. We show
that the death domain of p105 (also of IkappaBgamma) is essential for the
cytoplasmic sequestration of NF-kappaB by p105 and IkappaBgamma. However, the
death domain does not mask the exposed NLS of the complex. We also demonstrate
that the death domain alone is not sufficient for cytoplasmic retention and
instead functions only in conjunction with other parts in the three-dimensional
scaffold formed by the association of the ankyrin repeat domain (ARD) and
NF-kappaB dimer. We speculate that additional cytoplasmic protein(s) may
sequester the entire p105.NF-kappaB complex by binding through the death domain
and other segments, including the exposed NLS. The inhibitor of NF-kappaB (IkappaB) family of proteins is believed to regulate
NF-kappaB activity by cytoplasmic sequestration. We show that in cells depleted
of IkappaBalpha, IkappaBbeta and IkappaBepsilon proteins, a small fraction of
p65 binds DNA and leads to constitutive activation of NF-kappaB target genes,
even without stimulation, whereas most of the p65 remains cytoplasmic. These
results indicate that although IkappaBalpha, IkappaBbeta and IkappaBepsilon
proteins could be dispensable for cytoplasmic retention of NF-kappaB, they are
essential for preventing NF-kappaB-dependent gene expression in the basal state.
We also show that in the absence of IkappaBalpha, IkappaBbeta and IkappaBepsilon
proteins, cytoplasmic retention of NF-kappaB by other cellular proteins renders
the pathway unresponsive to activation. NF-κB is a pivotal transcription factor that controls cell survival and
proliferation in diverse physiological processes. The activity of NF-κB is
tightly controlled through its cytoplasmic sequestration by specific inhibitors,
IκBs. Various cellular stimuli induce the activation of an IκB kinase, which
phosphorylates IκBs and triggers their proteasomal degradation, causing nuclear
translocation of activated NF-κB. Under normal conditions, the activation of
NF-κB occurs transiently, thus ensuring rapid but temporary induction of target
genes. Deregulated NF-κB activation contributes to the development of various
diseases, including cancers and immunological disorders. Accumulated studies
demonstrate that the NF-κB signaling pathway is a target of several human
oncogenic viruses, including the human T cell leukemia virus type 1, the Kaposi
sarcoma-associated herpesvirus, and the Epstein-Bar virus. These viruses encode
specific oncoproteins that target different signaling components of the NF-κB
pathway, leading to persistent activation of NF-κB. This chapter will discuss
the molecular mechanisms by which NF-κB is activated by the viral oncoproteins. The NF-κB transcription factor controls diverse biological processes. According
to the classical model, NF-κB is retained in the cytoplasm of resting cells via
binding to inhibitory, IκB proteins and translocates into the nucleus upon their
ligand-induced degradation. Here we reveal that Sef, a known tumor suppressor
and inhibitor of growth factor signaling, is a spatial regulator of NF-κB. Sef
expression is regulated by the proinflammatory cytokines tumor necrosis factor
and interleukin-1, and Sef specifically inhibits "classical" NF-κB (p50:p65)
activation by these ligands. Like IκBs, Sef sequesters NF-κB in the cytoplasm of
resting cells. However, contrary to IκBs, Sef continues to constrain NF-κB
nuclear entry upon ligand stimulation. Accordingly, endogenous Sef knockdown
markedly enhances stimulus-induced NF-κB nuclear translocation and consequent
activity. This study establishes Sef as a feedback antagonist of proinflammatory
cytokines and highlights its potential to regulate the crosstalk between
proinflammatory cytokine receptors and receptor tyrosine kinases. |
What is the mode of inheritance of Marchesani syndrome? | Marchesani syndrome is transmitted either by an autosomal dominant (mutations in FBN1) or an autosomal recessive (mutations in ADAMTS10) mode of inheritance | Weill-Marchesani syndrome is a rare, generalized disorder of connective tissue
manifested by short stature, brachymorphia, and spherophakia. Inheritance is
autosomal recessive. In the less than 50 reported cases, joint stiffness in the
hands and thenar atrophy have been noted in adults. A kindred is reported here
in which release of multiple trigger fingers and bilateral carpal tunnel
syndrome in childhood has improved hand function in a brother and sister. Weill-Marchesani syndrome comprises short stature, brachydactyly,
microspherophakia, glaucoma, and ectopia lentis is regarded as an autosomal
recessive trait (McKusick 277600). We present two families each with affected
individuals in 3 generations demonstrating autosomal domit inheritance of
Weill-Marchesani syndrome. Linkage analysis in these 2 families suggests a gene
for Weill-Marchesani syndrome maps to 15q21.1. The dislocated lenses and
connective tissue disorder in these families suggests that fibrillin-1 and
microfibril-associated protein 1, which both map to 15q21.1, are candidate genes
for Weill-Marchesani syndrome. Immunohistochemistry staining of skin sections
from family 1 showed an apparent decrease in fibrillin staining compared to
control individuals. BACKGROUND: Weill-Marchesani syndrome is a rare systemic connective tissue
disorder consisting of brachymorphy, brachydactyly, ectopia lentis, spherophakia
and glaucoma.
METHODS: We report 6 patients with Weill-Marchesani syndrome (with or without
ocular involvement) in three generations, identified by screening 26 members of
two families. This is the largest family in the literature showing an autosomal
domit pattern of inheritance.
RESULTS: Presenile vitreous liquefaction was present in all the younger cases.
Weill-Marchesani syndrome was full-blown in two cases in the third generation,
in which asymmetrical axial length and glaucomatous damage were present. To our
knowledge this is the first report regarding asymmetrical axial length and
glaucomatous damage, and presenile vitreous liquefaction in Weill-Marchesani
syndrome with or without ocular involvement.
CONCLUSIONS: The longer axial length might be the precursor of impending severe
glaucomatous damage. Presenile vitreous liquefaction in subtle young cases
should alert the physician to the diagnosis of Weill-Marchesani syndrome on
screening of the family members. Weill-Marchesani syndrome (WMS) is a rare disease characterized by short
stature, brachydactyly, joint stiffness, and characteristic eye abnormalities,
including microspherophakia, ectopia lentis, and glaucoma. Both autosomal
recessive and autosomal domit modes of inheritance have been described in
association with WMS. We have performed a genome-wide search in two large
consanguineous families of Lebanese and Saudian origin consistent with an
autosomal recessive mode of inheritance. Here, we report the linkage of the
disease gene to chromosome 19p13.3-p13.2 (Zmax=5.99 at theta=0 at locus
D19S906). A recombination event between loci D19S905 and D19S901 defines the
distal boundary, and a second recombination event between loci D19S221 and
D19S840 defines the proximal boundary of the genetic interval encompassing the
WMS gene (12.4 cM). We hope that our ongoing studies will lead to the
identification of the disease-causing gene. Weill-Marchesani syndrome (WMS) is a connective tissue disorder characterised by
short stature, brachydactyly, joint stiffness, and characteristic eye anomalies
including microspherophakia, ectopia of the lenses, severe myopia, and glaucoma.
Both autosomal recessive (AR) and autosomal domit (AD) modes of inheritance
have been described and a gene for AR WMS has recently been mapped to chromosome
19p13.3-p13.2. Here, we report on the exclusion of chromosome 19p13.3-p13.2 in a
large AD WMS family and show that, despite clinical homogeneity, AD and AR WMS
are genetically heterogeneous entities. Because two AD WMS families were
consistent with linkage to chromosome 15q21.1, the fibrillin-1 gene was
sequenced and a 24 nt in frame deletion within a latent transforming growth
factor-beta1 binding protein (LTBP) motif of the fibrillin-1 gene was found in a
AD WMS family (exon 41, 5074_5097del). This in frame deletion cosegregated with
the disease and was not found in 186 controls. This study strongly suggests that
AD WMS and Marfan syndrome are allelic conditions at the fibrillin-1 locus and
adds to the remarkable clinical heterogeneity of type I fibrillinopathies. Weill-Marchesani syndrome (WMS) is a rare condition characterized by short
stature, brachydactyly, joint stiffness, and characteristic eye abnormalities
including microspherophakia, ectopia of lens, severe myopia, and glaucoma. Both
autosomal recessive (AR) and autosomal domit (AD) modes of inheritance have
been described for WMS. A locus for AR WMS has recently been mapped to
chromosome 19p13.3-p13.2 while mutation within the fibrillin-1 gene (15q21.1)
was found in one AD WMS family. In order to answer the question of whether or
not genetic heterogeneity could be related to a clinical heterogeneity, we
reviewed 128 WMS patients from the literature (including 57 AR, 50 AD, and 21
sporadic cases), with a particular attention to clinical features. Statistical
analyses using Fischer exact test were used to compare the proportions of 12
clinical parameters between AR and AD patients. There was no significant
difference between both groups for myopia, glaucoma, cataract, short stature,
brachydactyly, thick skin, muscular build, and mental retardation. Significant
results were found for microspherophakia (94% in AR, 74% in AD, Fischer 0.007),
ectopia lentis (64% in AR, 84% in AD, Fischer 0.016), joint limitations (49% in
AR, 77% in AD, Fischer 0.010), and cardiac anomalies (39% in AR, 13% in AD,
Fischer 0.004). Nevertheless, we failed to distinguish AR from AD inheritance in
individual cases. These results support the clinical homogeneity but the genetic
heterogeneity of WMS. Weill-Marchesani syndrome (WMS) is a well-characterized disorder in which
patients develop eye and skeletal abnormalities. Autosomal-recessive and
autosomal-domit forms of WMS are caused by mutations in ADAMTS10 and FBN1
genes, respectively. Here we report on 13 patients from seven unrelated families
from the Arabian Peninsula. These patients have a constellation of features that
fall within the WMS spectrum and follow an autosomal-recessive mode of
inheritance. Individuals who came from two families and met the diagnostic
criteria for WMS were each found to have a different homozygous missense
mutation in ADAMTS10. Linkage analysis and direct sequencing of candidate genes
in another two families and a sporadic case with phenotypes best described as
WMS-like led to the identification of three homozygous mutations in the closely
related ADAMTS17 gene. Our clinical and genetic findings suggest that ADAMTS17
plays a role in crystalline lens zonules and connective tissue formation and
that mutations in ADAMTS17 are sufficient to produce some of the main features
typically described in WMS. |
Tumor-treating fields are effective for treatment of which cancers? | Clinical trials have shown that Tumor-treating fields are effective for treatment of non-small cell lung cancer and glioblastoma. Ongoing and future trials will evaluate TTFields in solid tumor brain metastases, and ovarian, pancreatic cancers and multidrug resistance cancer cells. | BACKGROUND: Exposure of cancer cells to chemotherapeutic agents may result in
reduced sensitivity to structurally unrelated agents, a phenomenon known as
multidrug resistance, MDR. The purpose of this study is to investigate cell
growth inhibition of wild type and the corresponding MDR cells by Tumor Treating
Fields--TTFields, a new cancer treatment modality that is free of systemic
toxicity. The TTFields were applied alone and in combination with paclitaxel and
doxorubicin.
METHODS: Three pairs of wild type/MDR cell lines, having resistivity resulting
from over-expression of ABC transporters, were studied: a clonal derivative
(C11) of parental Chinese hamster ovary AA8 cells and their emetine-resistant
sub-line EmtR1; human breast cancer cells MCF-7 and their mitoxantrone-resistant
sub lines MCF-7/Mx and human breast cancer cells MDA-MB-231 and their
doxorubicin resistant MDA-MB-231/Dox cells. TTFields were applied for 72 hours
with and without the chemotherapeutic agents. The numbers of viable cells in the
treated cultures and the untreated control groups were determined using the XTT
assay. Student t-test was applied to asses the significance of the differences
between results obtained for each of the three cell pairs.
RESULTS: TTFields caused a similar reduction in the number of viable cells of
wild type and MDR cells. Treatments by TTFields/drug combinations resulted in a
similar increased reduction in cell survival of wild type and MDR cells.
TTFields had no effect on intracellular doxorubicin accumulation in both wild
type and MDR cells.
CONCLUSIONS: The results indicate that TTFields alone and in combination with
paclitaxel and doxorubicin effectively reduce the viability of both wild type
and MDR cell sub-lines and thus can potentially be used as an effective
treatment of drug resistant tumors. INTRODUCTION: Local control is fundamental, both for the curative as well as the
palliative treatment of cancer. Tumor treating fields (TTFields) are low
intensity (1 ? 2 V/cm), intermediate frequency (100 ? 200 kHz) alternating
electric fields administered using insulated electrodes placed on the skin
surrounding the region of a maligt tumor. TTFields were shown to destroy
cells within the process of mitosis via apoptosis, thereby inhibiting tumor
growth. TTFields have no effect on non-dividing cells.
AREAS COVERED: This article reviews in vitro and in vivo preclinical studies,
demonstrating the activity of TTFields both as a monotherapy as well as in
combination with several cytotoxic agents. Furthermore, it summarizes the
clinical experience with TTFields, mainly in two indications: one in recurrent
glioblastoma multiforme: in a large prospective randomized Phase III trial
TTFields was compared with best standard care (including chemotherapy): TTFields
significantly improved median overall survival (OS) compared with standard
therapy (7.8 vs 6.1 months) for the patients treated per protocol. Importantly,
quality of life was also better in the TTFields group. The second indication was
a Phase II study in second-line non-small cell lung cancer, where TTFields was
administered concomitantly with pemetrexed. This combination resulted in an
excellent median OS of 13.8 months. Interestingly, the progression-free survival
(PFS) within the area of the TTFields was 28, however, outside the TTFields the
PFS was only 22 weeks.
EXPERT OPINION: The proof of concept of TTFields has been well demonstrated in
the preclinical setting, and the clinical data seem promising in various tumor
types. The side effects of TTFields were minimal and in general consisted of
skin reaction to the electrodes. There are a number of ways in which TTFields
could be further evaluated, for example, in combination with chemotherapy, as a
maintece treatment, or as a salvage therapy if radiotherapy or surgery is not
possible. While more clinical data are clearly needed, TTFields is an emerging
and promising novel treatment concept. Glioblastoma multiforme (GBM) is the most common and maligt primary
intracranial tumor, and has a median survival of only 10 to 14 months with only
3 to 5% of patients surviving more than three years. Recurrence (RGBM) is nearly
universal, and further decreases the median survival to only five to seven
months with optimal therapy. Tumor-treating fields (TTField) therapy is a novel
treatment technique that has recently received CE and FDA approval for the
treatment of RGBM, and is based on the principle that low intensity,
intermediate frequency electric fields (100 to 300 kHz) may induce apoptosis in
specific cell types. Our center was the first to apply TTField treatment to
histologically proven GBM in a small pilot study of 20 individuals in 2004 and
2005, and four of those original 20 patients are still alive today. We report
two cases of GBM and two cases of RGBM treated by TTField therapy, all in good
health and no longer receiving any treatment more than seven years after
initiating TTField therapy, with no clinical or radiological evidence of
recurrence. Tumor treating fields (TTFields) is a noninvasive, regional antimitotic
treatment modality that has been approved for the treatment of recurrent
glioblastoma by the U.S. FDA and has a CE mark in Europe. TTFields therapy
delivers low-intensity (1-3 V/cm), intermediate-frequency (100-300 kHz),
alternating electric fields to the tumor using transducer arrays placed on the
skin around the region of the body containing the tumor. TTFields therapy
affects metaphase, by disrupting mitotic spindle formation, and anaphase, by
dielectrophoretic dislocation of intracellular constituents, resulting in
apoptosis. TTFields therapy is frequency tuned to specific cancer cell types.
The antimitotic effect of TTFields therapy has been demonstrated in multiple
cell lines when the appropriate frequency was utilized. A phase III trial of
TTFields monotherapy compared to active chemotherapy in recurrent glioblastoma
patients established that TTFields therapy is associated with minimal toxicity,
better quality of life, and comparable efficacy to chemotherapy. Ongoing and
future trials will evaluate TTFields in newly diagnosed glioblastoma, solid
tumor brain metastases, nonsmall cell lung cancer, and ovarian and pancreatic
cancers. BACKGROUND: Low intensity, intermediate frequency, alternating electric fields
(Tumor Treating Fields; TTFields) exhibit anti-mitotic activity in cancer cells.
Promising preclinical data have led to a single arm phase I/II trial in NSCLC
patients.
METHODS: Forty-two inoperable stage IIIB (with pleural effusion) and IV NSCLC
patients who had had tumor progression received pemetrexed 500 mg/m(2) iv q3w
together with daily TTFields therapy until disease progression. The primary
endpoint was time to "in-field" progression.
RESULTS: Median age for all patients was 63 years, 76% had stage IV disease, 78%
had adenocarcinoma and 17% had performance status of 2. The median time to
in-field progression was 28 weeks and the median time to systemic progression
was 22 weeks. Six patients (14.6%) had a partial remission (PR) and 20 had
stable disease (SD) (48.8%). Median overall survival was 13.8 months and 1 year
survival rate was 57%. There were no TTFields-related serious adverse events.
CONCLUSIONS: The combination of TTFields and pemetrexed as a second line therapy
for NSCLC is safe and potentially more effective than pemetrexed alone. TTFields
improved disease control within the treatment field and a phase III study is
planned to further investigate its role as a novel treatment in NSCLC. Tumor treating fields (TTFs) are an evolving new anticancer modality. The U.S.
Food and Drug Administration has approved the first device, the NovoTTF-100A™,
that uses this technology and is indicated for use in progressive glioblastoma
multiforme after standard therapies have failed. Promising clinical trial
results will likely lead to expanded uses in primary brain tumors and other
cancer types. This article will review the concept of TTFs and their mechanism
of action, and overview the TTF device and its approved usage. OBJECTIVES: Tumor Treating Fields (TTFields) are a non-invasive cancer treatment
modality approved for the treatment of patients with recurrent glioblastoma. The
present study determined the efficacy and mechanism of action of TTFields in
preclinical models of pancreatic cancer.
METHODS: The effect of TTFields in vitro was assessed using cell counts,
clonogenic assays, cell cycle analysis and analysis of mitotic figures. The
effect in vivo effect was studied in the PC1-0 hamster pancreatic cancer model.
RESULTS: Application of TTFields in vitro showed a significant decrease in cell
count, an increase in cell volume and reduced clonogenicity. Further analysis
demonstrated significant increase in the number of abnormal mitotic figures, as
well as a decrease in G2-M cell population. In hamsters with orthotopic
pancreatic tumors, TTFields significantly reduced tumor volume accompanied by an
increase in the frequency of abnormal mitotic events. TTFields efficacy was
enhanced both in vitro and in vivo when combined with chemotherapy.
CONCLUSIONS: These results provide the first evidence that TTFields serve as an
effective antimitotic treatment in preclinical pancreatic cancer models and have
a long term negative effect on cancer cell survival. These results make TTFields
an attractive candidate for testing in the treatment of patients with pancreatic
cancer. Non-small cell lung cancer (NSCLC) is one of the leading causes of
cancer-related deaths worldwide. Common treatment modalities for NSCLC include
surgery, radiotherapy, chemotherapy, and, in recent years, the clinical
management paradigm has evolved with the advent of targeted therapies. Despite
such advances, the impact of systemic therapies for advanced disease remains
modest, and as such, the prognosis for patients with NSCLC remains poor.
Standard modalities are not without their respective toxicities and there is a
clear need to improve both efficacy and safety for current management
approaches. Tumor-treating fields (TTFields) are low-intensity,
intermediate-frequency alternating electric fields that disrupt proper spindle
microtubule arrangement, thereby leading to mitotic arrest and ultimately to
cell death. We evaluated the effects of combining TTFields with standard
chemotherapeutic agents on several NSCLC cell lines, both in vitro and in vivo.
Frequency titration curves demonstrated that the inhibitory effects of TTFields
were maximal at 150 kHz for all NSCLC cell lines tested, and that the addition
of TTFields to chemotherapy resulted in enhanced treatment efficacy across all
cell lines. We investigated the response of Lewis lung carcinoma and KLN205
squamous cell carcinoma in mice treated with TTFields in combination with
pemetrexed, cisplatin, or paclitaxel and compared these to the efficacy observed
in mice exposed only to the single agents. Combining TTFields with these
therapeutic agents enhanced treatment efficacy in comparison with the respective
single agents and control groups in all animal models. Together, these findings
suggest that combining TTFields therapy with chemotherapy may provide an
additive efficacy benefit in the management of NSCLC. Glioblastoma multiforme (GBM) is the most common form of primary maligt brain
cancer. Median overall survival (OS) for newly diagnosed patients is only about
12 to 18 months. GBM tumors invariably recur, and there is no widely recognized
and effective standard treatment for recurrent GBM. NovoTTF Therapy is a novel
and US Food and Drug Administration (FDA)-approved antimitotic treatment for
recurrent GBM with potential benefits compared with other options. Recurrent GBM
patients from two prior trials with demonstrated radiologic tumor response to
single-agent NovoTTF Therapy were analyzed to better characterize tumor response
patterns and evaluate the associations between response, compliance, and OS. In
addition, a compartmental tumor growth model was developed and evaluated for its
ability to predict GBM response to tumor-treating fields (TTFields). The overall
response rate across both trials was 15% (4% complete responses): 14% in the
phase III trial (14/120) and 20% (2/10) in a pilot study. Tumor responses to
NovoTTF Therapy developed slowly (median time to response, 5.2 months) but were
durable (median duration, 12.9 months). Response duration was highly correlated
with OS (r(2) = .92, P<.0001), and median OS for responders was 24.8 months.
Seven of 16 responders exhibited initial tumor growth on magnetic resoce
imaging. Compliance appeared to be linked with both improved response and
survival. The tumor growth model predicted tumor arrest and shrinkage only after
several weeks of continuous NovoTTF Therapy, consistent with the observed
clinical findings of initial transient tumor growth in some patients. NovoTTF
Therapy is a novel antimitotic treatment for recurrent GBM associated with
slowly developing but durable tumor responses in approximately 15% of patients.
Some responders exhibit initial tumor growth before shrinkage, indicating
treatment should not be terminated prior to allowing for the full effect of
NovoTTF Therapy to be realized. OS is longer in responders than in
nonresponders. High daily compliance rates may be associated with increased
likelihood of an objective response and are predictive of improved survival. |
Which event results in the acetylation of S6K1? | Using acetyl-specific K516 antibodies, we show that acetylation of endogenous S6K1 at this site is potently induced upon growth factor stimulation. We propose that K516 acetylation may serve to modulate important kinase-independent functions of S6K1 in response to growth factor signalling. Following mitogen stimulation, S6Ks interact with the p300 and p300/CBP-associated factor (PCAF) acetyltransferases. S6Ks can be acetylated by p300 and PCAF in vitro and S6K acetylation is detected in cells expressing p300 | The 70kDa ribosomal protein S6 kinases (S6K1 and S6K2) play important roles in
the regulation of protein synthesis, cell growth and survival. S6Ks are
activated in response to mitogen stimulation and nutrient sufficiency by the
phosphorylation of conserved serine and threonine residues. Here we show for the
first time, that in addition to phosphorylation, S6Ks are also targeted by
lysine acetylation. Following mitogen stimulation, S6Ks interact with the p300
and p300/CBP-associated factor (PCAF) acetyltransferases. S6Ks can be acetylated
by p300 and PCAF in vitro and S6K acetylation is detected in cells expressing
p300. Furthermore, it appears that the acetylation sites targeted by p300 lie
within the divergent C-terminal regulatory domains of both S6K1 and S6K2.
Acetylation of S6K1 and 2 is increased upon the inhibition of class I/II histone
deacetylases (HDACs) by trichostatin-A, while the enhancement of S6K1
acetylation by nicotinamide suggests the additional involvement of sirtuin
deacetylases in S6K deacetylation. Both expression of p300 and HDAC inhibition
cause increases in S6K protein levels, and we have shown that S6K2 is stabilized
in cells treated with HDAC inhibitors. The finding that S6Ks are targeted by
histone acetyltransferases uncovers a novel mode of crosstalk between mitogenic
signalling pathways and the transcriptional machinery and reveals additional
complexity in the regulation of S6K function. The 70kDa ribosomal protein S6 kinase 1 (S6K1) plays important roles in the
regulation of protein synthesis, cell growth and metabolism. S6K1 is activated
by the phosphorylation of multiple serine and threonine residues in response to
stimulation by a variety of growth factors and cytokines. In addition to
phosphorylation, we have recently shown that S6K1 is also targeted by lysine
acetylation. Here, using tandem mass spectrometry we have mapped acetylation of
S6K1 to lysine 516, a site close to the C-terminus of the kinase that is highly
conserved amongst vertebrate S6K1 orthologues. Using acetyl-specific K516
antibodies, we show that acetylation of endogenous S6K1 at this site is potently
induced upon growth factor stimulation. Although S6K1 acetylation and
phosphorylation are both induced by growth factor stimulation, these events
appear to be functionally independent. Indeed, experiments using inhibitors of
S6K1 activation and exposure of cells to various stresses indicate that S6K1
acetylation can occur in the absence of phosphorylation and vice versa. We
propose that K516 acetylation may serve to modulate important kinase-independent
functions of S6K1 in response to growth factor signalling. |
List angiocrine factors | Angiocrine factors are: Ccl4, neurotensin, vascular endothelial growth factor, metalloproteinases-1, thrombospondin 3, Slit2, hepatocyte growth factor, Wnt2. | The precise mechanisms whereby anti-angiogenesis therapy blocks tumour growth or
causes vascular toxicity are unknown. We propose that endothelial cells
establish a vascular niche that promotes tumour growth and tissue repair not
only by delivering nutrients and O2 but also through an 'angiocrine' mechanism
by producing stem and progenitor cell-active trophogens. Identification of
endothelial-derived instructive angiocrine factors will allow direct tumour
targeting, while diminishing the unwanted side effects associated with the use
of anti-angiogenic agents. It is well known that tumor-derived proangiogenic factors induce
neovascularization to facilitate tumor growth and maligt progression.
However, the concept of "angiocrine" signaling, in which signals produced by
endothelial cells elicit tumor cell responses distinct from vessel function, has
been proposed, yet remains underinvestigated. Here, we report that angiocrine
factors secreted from endothelium regulate tumor growth and motility. We found
that Slit2, which is negatively regulated by endothelial EphA2 receptor, is one
such tumor suppressive angiocrine factor. Slit2 activity is elevated in
EphA2-deficient endothelium. Blocking Slit activity restored angiocrine-induced
tumor growth/motility, whereas elevated Slit2 impaired growth/motility. To
translate our findings to human cancer, we analyzed EphA2 and Slit2 expression
in human cancer. EphA2 expression inversely correlated with Slit2 in the
vasculature of invasive human ductal carcinoma samples. Moreover, analysis of
large breast tumor data sets revealed that Slit2 correlated positively with
overall and recurrence-free survival, providing clinical validation for the
tumor suppressor function for Slit2 in human breast cancer. Together, these data
support a novel, clinically relevant mechanism through which EphA2 represses
Slit2 expression in endothelium to facilitate angiocrine-mediated tumor growth
and motility by blocking a tumor suppressive signal. Distinct families of multipotent heart progenitors play a central role in the
generation of diverse cardiac, smooth muscle and endothelial cell lineages
during mammalian cardiogenesis. The identification of precise paracrine signals
that drive the cell-fate decision of these multipotent progenitors, and the
development of novel approaches to deliver these signals in vivo, are critical
steps towards unlocking their regenerative therapeutic potential. Herein, we
have identified a family of human cardiac endothelial intermediates located in
outflow tract of the early human fetal hearts (OFT-ECs), characterized by
coexpression of Isl1 and CD144/vWF. By comparing angiocrine factors expressed by
the human OFT-ECs and non-cardiac ECs, vascular endothelial growth factor
(VEGF)-A was identified as the most abundantly expressed factor, and clonal
assays documented its ability to drive endothelial specification of human
embryonic stem cell (ESC)-derived Isl1+ progenitors in a VEGF receptor-dependent
manner. Human Isl1-ECs (endothelial cells differentiated from hESC-derived ISL1+
progenitors) resemble OFT-ECs in terms of expression of the cardiac endothelial
progenitor- and endocardial cell-specific genes, confirming their organ
specificity. To determine whether VEGF-A might serve as an in vivo cell-fate
switch for human ESC-derived Isl1-ECs, we established a novel approach using
chemically modified mRNA as a platform for transient, yet highly efficient
expression of paracrine factors in cardiovascular progenitors. Overexpression of
VEGF-A promotes not only the endothelial specification but also engraftment,
proliferation and survival (reduced apoptosis) of the human Isl1+ progenitors in
vivo. The large-scale derivation of cardiac-specific human Isl1-ECs from human
pluripotent stem cells, coupled with the ability to drive endothelial
specification, engraftment, and survival following transplantation, suggest a
novel strategy for vascular regeneration in the heart. Recent findings have shown that the blood vessels of different organs exert an
active role in regulating organ function. In detail, the endothelium that aligns
the vasculature of most organs is fundamental in maintaining organ homeostasis
and in promoting organ recovery following injury. Mechanistically, endothelial
cells (EC) of tissues such as the liver, lungs or the bone marrow (BM) have been
shown to produce "angiocrine" factors that promote organ recovery and restore
normal organ function. Controlled production of angiocrine factors following
organ injury is therefore essential to promote organ regeneration and to restore
organ function. However, the molecular mechanisms underlying the coordinated
production and function of such "angiocrine" factors are largely undisclosed and
were the subject of the present study. In detail, we identified for the first
time a microRNA (miRNA) expressed by BM EC that regulates the expression of
angiocrine genes involved in BM recovery following irradiation. Using a
microarray-based approach, we identified several miRNA expressed by irradiated
BMEC. After validating the variations in miRNA expression by semi-quantitative
PCR, we chose to study further the ones showing consistent variations between
experiments, and those predicted to regulate (directly or indirectly) angiogenic
and angiocrine factors. Of the mi-RNA that were chosen, miR-363-5p (previously
termed miR-363*) was subsequently shown to modulate the expression of numerous
EC-specific genes including some angiocrine factors. By luciferase reporter
assays, miR-363-5p is shown to regulate the expression of angiocrine factors
tissue inhibitor of metalloproteinases-1 (Timp-1) and thrombospondin 3 (THBS3)
at post-transcriptional level. Moreover, miR-363-5p reduction using anti-miR is
shown to affect EC angiogenic properties (such as the response to angiogenic
factors stimulation) and the interaction between EC and hematopoietic precursors
(particularly relevant in a BM setting). miR-363-5p reduction resulted in a
significant decrease in EC tube formation on matrigel, but increased
hematopoietic precursor cells adhesion onto EC, a mechanism that is shown to
involve kit ligand-mediated cell adhesion. Taken together, we have identified a
miRNA induced by irradiation that regulates angiocrine factors expression on EC
and as such modulates EC properties. Further studies on the importance of
miR-363-5p on normal BM function and in disease are warranted. Long-term, in vitro propagation of tumor-specific endothelial cells (TEC) allows
for functional studies and genome-wide expression profiling of clonally derived,
well-characterized subpopulations. Using a genetically engineered mouse model of
mammary adenocarcinoma, we have optimized an isolation procedure and defined
growth conditions for long-term propagation of mammary TEC. The isolated TEC
maintain their endothelial specification and phenotype in culture. Furthermore,
gene expression profiling of multiple TEC subpopulations revealed striking,
persistent overexpression of several candidate genes including Irx2 and Zfp503
(transcription factors), Alcam and Cd133 (cell surface markers), Ccl4 and
neurotensin (Nts) (angiocrine factors), and Gpr182 and Cnr2 (G protein-coupled
receptors). Taken together, we have developed an effective method for isolating
and culture-expanding mammary TEC, and uncovered several new TEC-selective genes
whose overexpression persists even after long-term in vitro culture. These
results suggest that the tumor microenvironment may induce changes in vascular
endothelium in vivo that are stably transmittable in vitro. |
What is protein carbamylation? | Protein carbamylation is a post-translational modification that can occur in the presence of urea. In solution, urea is in equilibrium with ammonium cyanate, and carbamylation occurs when cyanate ions react with the amino groups of lysines, arginines, protein N-termini, as well as sulfhydryl groups of cysteines. Protein carbamylation is one of the important post-translational modifications, which plays a pivotal role in a number of biological conditions, such as diseases, chronic renal failure and atherosclerosis. | Post-translational modification and functional impairment of proteins through
carbamylation is thought to promote vascular dysfunction during end-stage renal
disease. Cyanate, a reactive species in equilibrium with urea, carbamylates
protein lysine residues to form epsilon-carbamyllysine (homocitrulline),
altering protein structure and function. We now report the discovery of an
alternative and quantitatively domit mechanism for cyanate formation and
protein carbamylation at sites of inflammation and atherosclerotic plaque:
myeloperoxidase-catalyzed oxidation of thiocyanate, an anion abundant in blood
whose levels are elevated in smokers. We also show that
myeloperoxidase-catalyzed lipoprotein carbamylation facilitates multiple
pro-atherosclerotic activities, including conversion of low-density lipoprotein
into a ligand for macrophage scavenger receptor A1 recognition, cholesterol
accumulation and foam-cell formation. In two separate clinical studies (combined
n = 1,000 subjects), plasma levels of protein-bound homocitrulline independently
predicted increased risk of coronary artery disease, future myocardial
infarction, stroke and death. We propose that protein carbamylation is a
mechanism linking inflammation, smoking, uremia and coronary artery disease
pathogenesis. Carbamylation of proteins through reactive cyanate has been demonstrated to
predict an increased cardiovascular risk. Cyanate is formed in vivo by breakdown
of urea and at sites of inflammation by the phagocyte protein myeloperoxidase.
Because myeloperoxidase (MPO) associates with high-density lipoprotein (HDL) in
human atherosclerotic intima, we examined in the present study whether cyanate
specifically targets HDL. Mass spectrometry analysis revealed that protein
carbamylation is a major posttranslational modification of HDL. The
carbamyllysine content of lesion-derived HDL was more than 20-fold higher in
comparison with 3-chlorotyrosine levels, a specific oxidation product of MPO.
Notably, the carbamyllysine content of lesion-derived HDL was five- to eightfold
higher when compared with lesion-derived low-density lipoprotein (LDL) or total
lesion protein and increased with lesion severity. The carbamyllysine content of
HDL, but not of LDL, correlated with levels of 3-chlorotyrosine, suggesting that
MPO mediated carbamylation in the vessel wall. Remarkably, one carbamyllysine
residue per HDL-associated apolipoprotein A-I was sufficient to induce
cholesterol accumulation and lipid-droplet formation in macrophages through a
pathway requiring the HDL-receptor scavenger receptor class B, type I. The
present results raise the possibility that HDL carbamylation contributes to foam
cell formation in atherosclerotic lesions. AIM: Recent work has shown that humans are significantly exposed to isocyanic
acid/cyanate, which is generated when coal, biomass, or tobacco is burned. In
vivo, cyanate is formed by the phagocyte protein myeloperoxidase and by
breakdown of urea. Carbamylation of proteins through cyanate has been
demonstrated to predict cardiovascular risk and is thought to promote vascular
dysfunction; however, the underlying mechanisms remain unclear.
RESULTS: Here, we show that cyanate induces intercellular cell adhesion
molecule-1 (ICAM-1) expression with subsequently enhanced neutrophil adhesion in
human coronary artery endothelial cells. Cyanate triggers ICAM-1 expression
through a mechanism depending on activation of the mitogen-activated protein
kinase p38 and nuclear factor-kappaB. Endothelial ICAM-1 expression was not
induced when low-molecular-weight substances were removed from cell culture
medium, thus ruling out a role of carbamylated (lipo)proteins in ICAM-1
induction. In mice, oral administration of cyanate induced marked endothelial
ICAM-1 expression in the aorta. Moreover, in patients with end-stage renal
disease, the extent of plasma protein carbamylation (a marker for cyanate
exposure) significantly correlated with plasma levels of soluble ICAM-1.
INNOVATION: Here, we demonstrate for the first time that cyanate, rather than
carbamylated lipoproteins, induces vascular ICAM-1 expression in vivo.
CONCLUSION: Collectively, our data raise the possibility that cyanate amplifies
vascular inflammation, linking inflammation, smoking, and uremia. Carbamylation (carbamoylation) of lysine residues and protein N-termini is a
nonenzymatic PTM that has been related to protein ageing. In contrast to other
PTM, such as phosphorylation, carbamylation can be artificially introduced
during sample preparation with urea, thus affecting studies directed toward in
vivo carbamylation. In aqueous solution, urea-commonly used for denaturing
proteins-is in equilibrium with ammonium and isocyanate. Under alkaline
conditions, the latter can react with primary amines of free N-termini and
ε-amine groups of lysines to form carbamyl derivatives. Despite being a
relatively slow process, which is accelerated at elevated temperatures,
prolonged incubation of protein/peptide samples in urea buffers can induce
undesired carbamylation, hampering not only the proteolytic digestion with
trypsin and peptide identification by MS, but also interfering with stable
isotope-labeling techniques such as iTRAQ, tandem mass tags, and isotope-coded
protein labeling. Here, we evaluated the extent of urea-induced carbamylation
under commonly used sample preparation conditions. From our results, we can
deduce that carbamylation occurs in all cases involving urea, however with
varying degree: e.g. carbamidomethylation in the presence of 8.0 M urea induced
carbamylation of 17% of N-termini and 4% of Lys residues. Additionally,
researching a recently published large-scale dataset revealed a high degree of
urea-induced carbamylation in current proteomic samples. Protein carbamylation is one of the important post-translational modifications,
which plays a pivotal role in a number of biological conditions, such as
diseases, chronic renal failure and atherosclerosis. Therefore, recognition and
identification of protein carbamylated sites are essential for disease treatment
and prevention. Yet the mechanism of action of carbamylated lysine sites is
still not realized. Thus it remains a largely unsolved challenge to uncover it,
whether experimentally or theoretically. To address this problem, we have
presented a computational framework for theoretically predicting and analyzing
carbamylated lysine sites based on both the one-class k-nearest neighbor method
and two-stage feature selection. The one-class k-nearest neighbor method
requires no negative samples in training. Experimental results showed that by
using 280 optimal features the presented method achieved promising performances
of SN=82.50% for the jackknife test on the training set, and SN=66.67%,
SP=100.00% and MCC=0.8097 for the independent test on the testing set,
respectively. Further analysis of the optimal features provided insights into
the mechanism of action of carbamylated lysine sites. It is anticipated that our
method could be a potentially useful and essential tool for biologists to
theoretically investigate carbamylated lysine sites. Urea solution is one of the most commonly employed protein denaturants for
protease digestion in proteomic studies. However, it has long been recognized
that urea solution can cause carbamylation at the N termini of proteins/peptides
and at the side chain amino groups of lysine and arginine residues.
Protein/peptide carbamylation blocks protease digestion and affects protein
identification and quantification in mass spectrometry analysis by blocking
peptide amino groups from isotopic/isobaric labeling and changing peptide charge
states, retention times, and masses. In addition, protein carbamylation during
sample preparation makes it difficult to study in vivo protein carbamylation. In
this study, we compared the peptide carbamylation in urea solutions of different
buffers and found that ammonium-containing buffers were the most effective
buffers to inhibit protein carbamylation in urea solution. The possible
mechanism of carbamylation inhibition by ammonium-containing buffers is
discussed, and a revised procedure for the protease digestion of proteins in
urea and ammonium-containing buffers was developed to facilitate its application
in proteomic research. Carbamylation is a general process involved in protein molecular ageing due to
the nonenzymatic binding of isocyanic acid, mainly generated by urea
dissociation, to free amino groups. In vitro experiments and clinical studies
have suggested the potential involvement of carbamylated proteins (CPs) in
chronic kidney disease (CKD) complications like atherosclerosis, but their
metabolic fate in vivo is still unknown. To address this issue, we evaluated
protein carbamylation in the plasma and tissues of control and 75%
nephrectomised C57BL/6J mice by LC-MS/MS assay of homocitrulline, the major
carbamylation-derived product (CDP). A basal level of carbamylation was
evidenced under all conditions, showing that carbamylation is a physiological
process of protein modification in vivo. CP plasma concentrations increased in
nephrectomized vs. control mice over the 20 weeks of the experiment (e.g. 335 ±
43 vs. 167 ± 19 μmol homocitrulline/mol lysine (p<0.001) 20 weeks after
nephrectomy). Simultaneously, CP content increased roughly by two-fold in all
tissues throughout the experiment. The progressive accumulation of CPs was
specifically noted in long-lived extracellular matrix proteins, especially
collagen (e.g. 1264 ± 123 vs. 726 ± 99 μmol homocitrulline/mol lysine (p<0.01)
in the skin of nephrectomized vs. control mice after 20 weeks of evolution).
These results show that chronic increase of urea, as seen in CKD, increases the
carbamylation rate of plasma and tissue proteins. These results may be
considered in the perspective of the deleterious effects of CPs demonstrated in
vitro and of the correlation evidenced recently between plasma CPs and
cardiovascular risk or mortality in CKD patients. Protein carbamylation is a post-translational modification that can occur in the
presence of urea. In solution, urea is in equilibrium with ammonium cyanate, and
carbamylation occurs when cyanate ions react with the amino groups of lysines,
arginines, protein N-termini, as well as sulfhydryl groups of cysteines. The
concentration of urea is elevated in the renal inner medulla compared with other
tissues. Due to the high urea concentration, we hypothesized that carbamylation
can occur endogenously within the rat inner medulla. Using immunoblotting of rat
kidney cortical and medullary homogenates with a carbamyl-lysine specific
antibody, we showed that carbamylation is present in a large number of inner
medullary proteins. Using protein mass spectrometry (LC-MS/MS) of rat renal
inner medulla, we identified 456 unique carbamylated sites in 403 proteins,
including many that play important physiological roles in the renal medulla
[Data can be accessed at
https://helixweb.nih.gov/ESBL/Database/Carbamylation/Carbamylation_peptide_sorted.html].
We conclude that protein carbamylation occurs endogenously in the kidney,
modifying many physiologically important proteins. Carbamylation describes a nonenzymatic posttranslational protein modification
mediated by cyanate, a dissociation product of urea. When kidney function
declines and urea accumulates, the burden of carbamylation naturally increases.
Free amino acids may protect proteins from carbamylation, and protein
carbamylation has been shown to increase in uremic patients with amino acid
deficiencies. Carbamylation reactions are capable of altering the structure and
functional properties of certain proteins and have been implicated directly in
the underlying mechanisms of various disease conditions. A broad range of
studies has demonstrated how the irreversible binding of urea-derived cyanate to
proteins in the human body causes inappropriate cellular responses leading to
adverse outcomes such as accelerated atherosclerosis and inflammation. Given
carbamylation's relationship to urea and the evidence that it contributes to
disease pathogenesis, measurements of carbamylated proteins may serve as useful
quantitative biomarkers of time-averaged urea concentrations while also offering
risk assessment in patients with kidney disease. Moreover, the link between
carbamylated proteins and disease pathophysiology creates an enticing
therapeutic target for reducing the rate of carbamylation. This article reviews
the biochemistry of the carbamylation reaction, its role in specific diseases,
and the potential diagnostic and therapeutic implications of these findings
based on recent advances. |
What is the cause of episodic ataxia type 6? | Episodic ataxia type 6, is caused by mutations in the gene encoding a glial glutamate transporter, the excitatory amino acid transporter-1. Reduced glutamate uptake by mutant excitatory amino acid transporter-1 (EAAT1) has been thought to be the main pathophysiological process in episodic ataxia type 6. | Episodic ataxia is a human genetic disease characterized by paroxysmal
cerebellar incoordination. There are several genetically and clinically distinct
forms of this disease, and one of them, episodic ataxia type 6, is caused by
mutations in the gene encoding a glial glutamate transporter, the excitatory
amino acid transporter-1. So far, reduced glutamate uptake by mutant excitatory
amino acid transporter-1 has been thought to be the main pathophysiological
process in episodic ataxia type 6. However, excitatory amino acid transporter-1
does not only mediate secondary-active glutamate transport, but also functions
as an ion channel. Here, we examined the effects of a disease-associated point
mutation, P290R, on glutamate transport, anion current as well as on the
subcellular distribution of excitatory amino acid transporter-1 using
heterologous expression in mammalian cells. P290R reduces the number of
excitatory amino acid transporter-1 in the surface membrane and impairs
excitatory amino acid transporter-1-mediated glutamate uptake. Cells expressing
P290R excitatory amino acid transporter-1 exhibit larger anion currents than
wild-type cells in the absence as well as in the presence of external
l-glutamate, despite a lower number of mutant transporters in the surface
membrane. Noise analysis revealed unaltered unitary current amplitudes,
indicating that P290R modifies opening and closing, and not anion permeation
through mutant excitatory amino acid transporter-1 anion channels. These
findings identify gain-of-function of excitatory amino acid transporter anion
conduction as a pathological process in episodic ataxia. Episodic ataxia type 6
represents the first human disease found to be associated with altered function
of excitatory amino acid transporter anion channels and illustrates possible
physiological and pathophysiological impacts of this functional mode of this
class of glutamate transporters. |
What is the main role of Ctf4 in dna replication? | coupling MCM2-7 to replicative polymerases is an important feature of the regulation of chromosome replication in eukaryotes, and highlight a key role for Ctf4 in this processAnd-1/Ctf4 is therefore a new replication initiation factor that brings together the MCM2-7 helicase and the DNA pol alpha-primase complex, analogous to the linker between helicase and primase or helicase and polymerase that is seen in the bacterial replication machinery | Potential DNA replication accessory factors from the yeast Saccharomyces
cerevisiae have previously been identified by their ability to bind to DNA
polymerase alpha protein affinity matrices (J. Miles and T. Formosa, Proc. Natl.
Acad. Sci. USA 89:1276-1280, 1992). We have now used genetic methods to
characterize the gene encoding one of these DNA polymerase alpha-binding
proteins (POB1) to determine whether it plays a role in DNA replication in vivo.
We find that yeast cells lacking POB1 are viable but display a constellation of
phenotypes indicating defective DNA metabolism. Populations of cells lacking
POB1 accumulate abnormally high numbers of enlarged large-budded cells with a
single nucleus at the neck of the bud. The average DNA content in a population
of cells lacking POB1 is shifted toward the G2 value. These two phenotypes
indicate that while the bulk of DNA replication is completed without POB1,
mitosis is delayed. Deleting POB1 also causes elevated levels of both chromosome
loss and genetic recombination, enhances the temperature sensitivity of cells
with mutant DNA polymerase alpha genes, causes increased sensitivity to UV
radiation in cells lacking a functional RAD9 checkpoint gene, and causes an
increased probability of death in cells carrying a mutation in the MEC1
checkpoint gene. The sequence of the POB1 gene indicates that it is identical to
the CTF4 (CHL15) gene identified previously in screens for mutations that
diminish the fidelity of chromosome transmission. These phenotypes are
consistent with defective DNA metabolism in cells lacking POB1 and strongly
suggest that this DNA polymerase alpha-binding protein plays a role in
accurately duplicating the genome in vivo. We have used DNA polymerase alpha affinity chromatography to identify factors
involved in eukaryotic DNA replication in the yeast Saccharomyces cerevisiae.
Two proteins that bound to the catalytic subunit of DNA polymerase alpha (Pol1
protein) are encoded by the essential genes CDC68/SPT16 and POB3. The binding of
both proteins was enhanced when extracts lacking a previously characterized
polymerase binding protein, Ctf4, were used. This finding suggests that Cdc68
and Pob3 may compete with Ctf4 for binding to Pol1. Pol1 and Pob3 were
coimmunoprecipitated from whole-cell extracts with antiserum directed against
Cdc68, and Pol1 was immunoprecipitated from whole-cell extracts with antiserum
directed against the amino terminus of Pob3, suggesting that these proteins may
form a complex in vivo. CDC68 also interacted genetically with POL1 and CTF4
mutations; the maximum permissive temperature of double mutants was lower than
for any single mutant. Overexpression of Cdc68 in a pol1 mutant strain
dramatically decreased cell viability, consistent with the formation or
modulation of an essential complex by these proteins in vivo. A mutation in
CDC68/SPT16 had previously been shown to cause pleiotropic effects on the
regulation of transcription (J. A. Prendergrast et al., Genetics 124:81-90,
1990; E. A. Malone et al., Mol. Cell. Biol. 11:5710-5717, 1991; A. Rowley et
al., Mol. Cell. Biol. 11:5718-5726, 1991), with a spectrum of phenotypes similar
to those caused by mutations in the genes encoding histone proteins H2A and H2B
(Malone et al., Mol. Cell. Biol. 11:5710-5717, 1991). We show that at the
nonpermissive temperature, cdc68-1 mutants arrest as unbudded cells with a 1C
DNA content, consistent with a possible role for Cdc68 in the prereplicative
stage of the cell cycle. The cdc68-1 mutation caused elevated rates of
chromosome fragment loss, a phenotype characteristic of genes whose native
products are required for normal DNA metabolism. However, this mutation did not
affect the rate of loss or recombination for two intact chromosomes, nor did it
affect the retention of a low-copy-number plasmid. The previously
uncharacterized Pob3 sequence has significant amino acid sequence similarity
with an HMG1-like protein from vertebrates. Based on these results and because
Cdc68 has been implicated as a regulator of chromatin structure, we postulate
that polymerase alpha may interact with these proteins to gain access to its
template or to origins of replication in vivo. CTF4 and CTF18 are required for high-fidelity chromosome segregation. Both
exhibit genetic and physical ties to replication fork constituents. We find that
absence of either CTF4 or CTF18 causes sister chromatid cohesion failure and
leads to a preanaphase accumulation of cells that depends on the spindle
assembly checkpoint. The physical and genetic interactions between CTF4, CTF18,
and core components of replication fork complexes observed in this study and
others suggest that both gene products act in association with the replication
fork to facilitate sister chromatid cohesion. We find that Ctf18p, an RFC1-like
protein, directly interacts with Rfc2p, Rfc3p, Rfc4p, and Rfc5p. However, Ctf18p
is not a component of biochemically purified proliferating cell nuclear antigen
loading RF-C, suggesting the presence of a discrete complex containing Ctf18p,
Rfc2p, Rfc3p, Rfc4p, and Rfc5p. Recent identification and characterization of
the budding yeast polymerase kappa, encoded by TRF4, strongly supports a
hypothesis that the DNA replication machinery is required for proper sister
chromatid cohesion. Analogous to the polymerase switching role of the bacterial
and human RF-C complexes, we propose that budding yeast RF-C(CTF18) may be
involved in a polymerase switch event that facilities sister chromatid cohesion.
The requirement for CTF4 and CTF18 in robust cohesion identifies novel roles for
replication accessory proteins in this process. The fission yeast minichromosome loss mutant mcl1-1 was identified in a screen
for mutants defective in chromosome segregation. Missegregation of the
chromosomes in mcl1-1 mutant cells results from decreased centromeric cohesion
between sister chromatids. mcl1+ encodes a beta-transducin-like protein with
similarity to a family of eukaryotic proteins that includes Ctf4p from
Saccharomyces cerevisiae, sepB from Aspergillus nidulans, and AND-1 from humans.
The previously identified fungal members of this protein family also have
chromosome segregation defects, but they primarily affect DNA metabolism.
Chromosomes from mcl1-1 cells were heterogeneous in size or structure on
pulsed-field electrophoresis gels and had elongated heterogeneous telomeres.
mcl1-1 was lethal in combination with the DNA checkpoint mutations rad3delta and
rad26delta, demonstrating that loss of Mcl1p function leads to DNA damage.
mcl1-1 showed an acute sensitivity to DNA damage that affects S-phase
progression. It interacts genetically with replication components and causes an
S-phase delay when overexpressed. We propose that Mcl1p, like Ctf4p, has a role
in regulating DNA replication complexes. Cohesion establishment and maintece are carried out by proteins that modify
the activity of Cohesin, an essential complex that holds sister chromatids
together. Constituents of the replication fork, such as the DNA polymerase
alpha-binding protein Ctf4, contribute to cohesion in ways that are poorly
understood. To identify additional cohesion components, we analyzed a ctf4Delta
synthetic lethal screen performed on microarrays. We focused on a subset of
ctf4Delta-interacting genes with genetic instability of their own. Our analyses
revealed that 17 previously studied genes are also necessary for the maintece
of robust association of sisters in metaphase. Among these were subunits of the
MRX complex, which forms a molecular structure similar to Cohesin. Further
investigation indicated that the MRX complex did not contribute to metaphase
cohesion independent of Cohesin, although an additional role may be contributed
by XRS2. In general, results from the screen indicated a sister chromatid
cohesion role for a specific subset of genes that function in DNA replication
and repair. This subset is particularly enriched for genes that support the
S-phase checkpoint. We suggest that these genes promote and protect a chromatin
environment conducive to robust cohesion. Cohesion between sister chromatids mediated by a multisubunit complex called
cohesin is established during DNA replication and is essential for the orderly
segregation of chromatids during anaphase. In budding yeast, a specialized
replication factor C called RF-C(Ctf18/Dcc1/Ctf8) and the
DNA-polymerase-alpha-associated protein Ctf4 are required to maintain
sister-chromatid cohesion in cells arrested for long periods in mitosis. We show
here that CTF8, CTF4 and a helicase encoded by CHL1 are required for efficient
sister chromatid cohesion in unperturbed mitotic cells, and provide evidence
that Chl1 functions during S-phase. We also show that, in contrast to mitosis,
RF-C(Ctf18/Dcc1/Cft8), Ctf4 and Chl1 are essential for chromosome segregation
during meiosis and for the viability of meiotic products. Our finding that cells
deleted for CTF8, CTF4 or CHL1 undergo massive meiosis II non-disjunction
suggests that the second meiotic division is particularly sensitive to cohesion
defects. Using a functional as well as a cytological assay, we demonstrate that
CTF8, CHL1 and CTF4 are essential for cohesion between sister centromeres during
meiosis but dispensable for cohesin's association with centromeric DNA. Our
finding that mutants in fission yeast ctf18 and dcc1 have similar defects
suggests that the involvement of the alternative RF-C(Ctf18/Dcc1/Ctf8) complex
in sister chromatid cohesion might be highly conserved. Two identical sister copies of eukaryotic chromosomes are synthesized during S
phase. To facilitate their recognition as pairs for segregation in mitosis,
sister chromatids are held together from their synthesis onward by the
chromosomal cohesin complex. Replication fork progression is thought to be
coupled to establishment of sister chromatid cohesion, facilitating
identification of replication products, but evidence for this has remained
circumstantial. Here we show that three proteins required for sister chromatid
cohesion, Eco1, Ctf4, and Ctf18, are found at, and Ctf4 travels along
chromosomes with, replication forks. The ring-shaped cohesin complex is loaded
onto chromosomes before S phase in an ATP hydrolysis-dependent reaction.
Cohesion establishment during DNA replication follows without further cohesin
recruitment and without need for cohesin to re-engage an ATP hydrolysis motif
that is critical for its initial DNA binding. This provides evidence for
cohesion establishment in the context of replication forks and imposes
constraints on the mechanism involved. The MCM2-7 helicase complex is loaded on DNA replication origins during the G1
phase of the cell cycle to license the origins for replication in S phase. How
the initiator primase-polymerase complex, DNA polymerase alpha (pol alpha), is
brought to the origins is still unclear. We show that And-1/Ctf4 (Chromosome
transmission fidelity 4) interacts with Mcm10, which associates with MCM2-7, and
with the p180 subunit of DNA pol alpha. And-1 is essential for DNA synthesis and
the stability of p180 in mammalian cells. In Xenopus egg extracts And-1 is
loaded on the chromatin after Mcm10, concurrently with DNA pol alpha, and is
required for efficient DNA synthesis. Mcm10 is required for chromatin loading of
And-1 and an antibody that disrupts the Mcm10-And-1 interaction interferes with
the loading of And-1 and of pol alpha, inhibiting DNA synthesis. And-1/Ctf4 is
therefore a new replication initiation factor that brings together the MCM2-7
helicase and the DNA pol alpha-primase complex, analogous to the linker between
helicase and primase or helicase and polymerase that is seen in the bacterial
replication machinery. The discovery also adds to the connection between
replication initiation and sister chromatid cohesion. Mutations in the ELG1 gene of yeast lead to genomic instability, manifested in
high levels of genetic recombination, chromosome loss, and gross chromosomal
rearrangements. Elg1 shows similarity to the large subunit of the Replication
Factor C clamp loader, and forms a RFC-like (RLC) complex in conjunction with
the 4 small RFC subunits. Two additional RLCs exist in yeast: in one of them the
large subunit is Ctf18, and in the other, Rad24. Ctf18 has been characterized as
the RLC that functions in sister chromatid cohesion. Here we present evidence
that the Elg1 RLC (but not Rad24) also plays an important role in this process.
A genetic screen identified the cohesin subunit Mcd1/Scc1 and its loader Scc2 as
suppressors of the synthetic lethality between elg1 and ctf4. We describe
genetic interactions between ELG1 and genes encoding cohesin subunits and their
accessory proteins. We also show that defects in Elg1 lead to higher precocious
sister chromatid separation, and that Ctf18 and Elg1 affect cohesion via a joint
pathway. Finally, we localize both Ctf18 and Elg1 to chromatin and show that
Elg1 plays a role in the recruitment of Ctf18. Our results suggest that Elg1,
Ctf4, and Ctf18 may coordinate the relative movement of the replication fork
with respect to the cohesin ring. The eukaryotic replisome is a crucial determit of genome stability, but its
structure is still poorly understood. We found previously that many regulatory
proteins assemble around the MCM2-7 helicase at yeast replication forks to form
the replisome progression complex (RPC), which might link MCM2-7 to other
replisome components. Here, we show that the RPC associates with DNA polymerase
alpha that primes each Okazaki fragment during lagging strand synthesis. Our
data indicate that a complex of the GINS and Ctf4 components of the RPC is
crucial to couple MCM2-7 to DNA polymerase alpha. Others have found recently
that the Mrc1 subunit of RPCs binds DNA polymerase epsilon, which synthesises
the leading strand at DNA replication forks. We show that cells lacking both
Ctf4 and Mrc1 experience chronic activation of the DNA damage checkpoint during
chromosome replication and do not complete the cell cycle. These findings
indicate that coupling MCM2-7 to replicative polymerases is an important feature
of the regulation of chromosome replication in eukaryotes, and highlight a key
role for Ctf4 in this process. In eukaryotes, the activation of the prereplicative complex and assembly of an
active DNA unwinding complex are critical but poorly understood steps required
for the initiation of DNA replication. In this report, we have used bimolecular
fluorescence complementation assays in HeLa cells to examine the interactions
between Cdc45, Mcm2-7, and the GINS complex (collectively called the CMG
complex), which seem to play a key role in the formation and progression of
replication forks. Interactions between the CMG components were observed only
after the G(1)/S transition of the cell cycle and were abolished by treatment of
cells with either a CDK inhibitor or siRNA against the Cdc7 kinase. Stable
association of CMG required all three components of the CMG complex as well as
RecQL4, Ctf4/And-1, and Mcm10. Surprisingly, depletion of TopBP1, a homologue of
Dpb11 that plays an essential role in the chromatin loading of Cdc45 and GINS in
yeast cells, did not significantly affect CMG complex formation. These results
suggest that the proteins involved in the assembly of initiation complexes in
human cells may differ somewhat from those in yeast systems. Ctf4/AND-1 is a highly conserved gene product required for both DNA replication
and the establishment of sister chromatid cohesion. In this report, we examined
the mechanism of action of human Ctf4 (hCtf4) in DNA replication both in vitro
and in vivo. Our findings show that the purified hCtf4 exists as a dimer and
that the hCtf4 SepB domain likely plays a primary role determining the dimeric
structure. hCtf4 binds preferentially to DNA template-primer structures,
interacts directly with the replicative DNA polymerases (alpha, delta, and
epsilon), and markedly stimulates the polymerase activities of DNA polymerases
alpha and epsilon in vitro. Depletion of hCtf4 in HeLa cells by small
interfering RNA resulted in G(1)/S phase arrest. DNA fiber analysis revealed
that cells depleted of hCtf4 exhibited a rate of DNA replication slower than
cells treated with control small interfering RNA. These findings suggest that in
human cells, hCtf4 plays an essential role in DNA replication and its ability to
stimulate the replicative DNA polymerases may contribute to this effect. Ctf4p (chromosome transmission fidelity) has been reported to function in DNA
metabolism and sister chromatid cohesion in Saccharomyces cerevisiae. In this
study, a ctf4(S143F) mutant was isolated from a yeast genetic screen to identify
replication-initiation proteins. The ctf4(S143F) mutant exhibits plasmid
maintece defects which can be suppressed by the addition of multiple origins
to the plasmid, like other known replication-initiation mutants. We show that
both ctf4(S143F) and ctf4Delta strains have defects in S phase entry and S phase
progression at the restrictive temperature of 38 degrees C. Ctf4p localizes in
the nucleus throughout the cell cycle but only starts to bind chromatin at the
G1/S transition and then disassociates from chromatin after DNA replication.
Furthermore, Ctf4p interacts with Mcm10p physically and genetically, and the
chromatin association of Ctf4p depends on Mcm10p. Finally, deletion of CTF4
destabilizes Mcm10p and Pol alpha in both mcm10-1 and MCM10 cells. These data
indicate that Ctf4p facilitates Mcm10p to promote the DNA replication. DNA replication in eukaryotic cells is tightly regulated to ensure faithful
inheritance of the genetic material. While the replicators, replication origins
and many replication-initiation proteins in Saccharomyces cerevisiae have been
identified and extensively studied, the detailed mechanism that controls the
initiation of DNA replication is still not well understood. It is likely that
some factors involved in or regulating the initiation of DNA replication have
not been discovered. To identify novel DNA replication-initiation proteins and
their regulators, we developed a sensitive and comprehensive phenotypic screen
by combining several established genetic strategies including plasmid loss
assays with plasmids containing a single versus multiple replication origins and
colony color sectoring assays. We isolated dozen of mutants in previously known
initiation proteins and identified several novel factors, including Ctf1p Ctf3p,
Ctf4p, Ctf18p, Adk1p and Cdc60p, whose mutants lose plasmid containing a single
replication origin at high rates but lose plasmid carrying multiple replication
origins at lower rates. We also show that overexpression of replication
initiation proteins causes synthetic dosage lethality or growth defects in ctf1
and ctf18 mutants and that Ctf1p and Ctf18p physically interact with ORC, Cdt1p
and MCM proteins. Furthermore, depletion of both Ctf1p and Ctf18p prevents S
phase entry, retards S phase progression, and reduces pre-RC formation during
the M-to-G₁ transition. These data suggest that Ctf1p and Ctf18p together play
important roles in regulating the initiation of DNA replication. Cohesion between sister chromatids, mediated by the chromosomal cohesin complex,
is a prerequisite for their alignment on the spindle apparatus and segregation
in mitosis. Budding yeast cohesin first associates with chromosomes in G1. Then,
during DNA replication in S-phase, the replication fork-associated
acetyltransferase Eco1 acetylates the cohesin subunit Smc3 to make cohesin's DNA
binding resistant to destabilization by the Wapl protein. Whether stabilization
of cohesin molecules that happen to link sister chromatids is sufficient to
build sister chromatid cohesion, or whether additional reactions are required to
establish these links, is not known. In addition to Eco1, several other factors
contribute to cohesion establishment, including Ctf4, Ctf18, Tof1, Csm3, Chl1
and Mrc1, but little is known about their roles. Here, we show that each of
these factors facilitates cohesin acetylation. Moreover, the absence of Ctf4 and
Chl1, but not of the other factors, causes a synthetic growth defect in cells
lacking Eco1. Distinct from acetylation defects, sister chromatid cohesion in
ctf4Δ and chl1Δ cells is not improved by removing Wapl. Unlike previously
thought, we do not find evidence for a role of Ctf4 and Chl1 in Okazaki fragment
processing, or of Okazaki fragment processing in sister chromatid cohesion.
Thus, Ctf4 and Chl1 delineate an additional acetylation-independent pathway that
might hold important clues as to the mechanism of sister chromatid cohesion
establishment. Chromosome transmission fidelity 4 (Ctf4) is a conserved protein required for
DNA replication. In this report, interactions between human Ctf4 (hCtf4) and the
replicative helicase containing the cell division cycle 45
(Cdc45)/minichromosome maintece 2-7 (Mcm2-7)/Go, Ichi, Nii, and San (GINS)
(CMG) proteins [human CMG (hCMG) complex] were examined. The hCtf4-CMG complex
was isolated following in vitro interaction of purified proteins (hCtf4 plus the
hCMG complex), coinfection of Spodoptera frugiperda (Sf9) insect cells with
viruses expressing the hCMG complex and hCtf4, and from HeLa cell chromatin
after benzonase and immunoprecipitation steps. The stability of the hCtf4-CMG
complex depends upon interactions between hCtf4 and multiple components of the
hCMG complex. The hCtf4-CMG complex, like the hCMG complex, contains DNA
helicase activity that is more salt-resistant than the helicase activity of the
hCMG complex. We demonstrate that the hCtf4-CMG complex contains a homodimeric
hCtf4 and a monomeric hCMG complex and suggest that the homodimeric hCtf4 acts
as a platform linking polymerase α to the hCMG complex. The role of the hCMG
complex as the core of the replisome is also discussed. Efficient duplication of the genome requires the concerted action of helicase
and DNA polymerases at replication forks to avoid stalling of the replication
machinery and consequent genomic instability. In eukaryotes, the physical
coupling between helicase and DNA polymerases remains poorly understood. Here we
define the molecular mechanism by which the yeast Ctf4 protein links the
Cdc45-MCM-GINS (CMG) DNA helicase to DNA polymerase α (Pol α) within the
replisome. We use X-ray crystallography and electron microscopy to show that
Ctf4 self-associates in a constitutive disk-shaped trimer. Trimerization depends
on a β-propeller domain in the carboxy-terminal half of the protein, which is
fused to a helical extension that protrudes from one face of the trimeric disk.
Critically, Pol α and the CMG helicase share a common mechanism of interaction
with Ctf4. We show that the amino-terminal tails of the catalytic subunit of Pol
α and the Sld5 subunit of GINS contain a conserved Ctf4-binding motif that docks
onto the exposed helical extension of a Ctf4 protomer within the trimer.
Accordingly, we demonstrate that one Ctf4 trimer can support binding of up to
three partner proteins, including the simultaneous association with both Pol α
and GINS. Our findings indicate that Ctf4 can couple two molecules of Pol α to
one CMG helicase within the replisome, providing a new model for lagging-strand
synthesis in eukaryotes that resembles the emerging model for the simpler
replisome of Escherichia coli. The ability of Ctf4 to act as a platform for
multivalent interactions illustrates a mechanism for the concurrent recruitment
of factors that act together at the fork. |
Could Arimidex (anastrozole) cause hot flashes? | Yes. Hot flashes are one of the most common adverse effects of Arimidex. | With the development of highly effective, well-tolerated third-generation
aromatase inhibitors (AIs), these drugs will probably play an increasingly
important role in all phases of breast cancer treatment. As a result, the impact
of such hormonal agents on patients' quality of life bears rigorous
investigation. In a randomized, multicenter, single-blind cross-over study, the
AIs letrozole and anastrozole were evaluated for quality of life, toxicity, and
patient preference. A total of 72 patients were enrolled and were treated with
each drug for a 4-week period, with a 1-week drug-free washout period before
cross-over to the alternate agent. Assessments included the FACT-ES, toxicity,
and patient preference. The FACT-ES is a validated questionnaire designed to
measure quality of life of women with breast cancer who are being treated with
endocrine therapies. Letrozole was superior to anastrozole with respect to both
quality of life and toxicity evaluations. In addition, at the conclusion of the
trial, reduced nausea, hot flashes, and abdominal discomfort caused almost twice
as many patients to prefer to continue with letrozole therapy than with
anastrozole. Data from this recent trial indicate that letrozole is better
tolerated and provides better quality of life than anastrozole for women with
metastatic breast cancer. BACKGROUND: The first analysis of the ATAC (Arimidex, Tamoxifen Alone or in
Combination) trial (median follow-up, 33 months) demonstrated that in adjuvant
endocrine therapy for postmenopausal patients with early-stage breast cancer,
anastrozole was superior to tamoxifen in terms of disease-free survival (DFS),
time to recurrence (TTR), and incidence of contralateral breast cancer (CLBC).
In the current article, the results of the first efficacy update, based on a
median follow-up period of 47 months, are reported along with the results of an
updated safety analysis, performed 7 months after the first analysis (median
duration of treatment, 36.9 months).
METHODS: DFS, TTR, CLBC incidence, and safety were assessed in the same patient
group as in the first analysis of the ATAC trial.
RESULTS: DFS estimates at 4 years remained significantly more favorable (86.9%
vs. 84.5%, respectively) for patients receiving anastrozole compared with those
receiving tamoxifen (hazard ratio [HR], 0.86; 95% confidence interval [CI],
0.76-0.99; P = 0.03). The benefit generated by anastrozole in terms of DFS was
even greater in patients with hormone receptor-positive tumors (HR, 0.82; 95%
CI, 0.70-0.96; P = 0.014). The HR for TTR also indicated a significant benefit
for patients receiving anastrozole compared with those receiving tamoxifen (HR,
0.83; 95% CI, 0.71-0.96; P = 0.015), with additional benefit for patients with
hormone receptor-positive tumors (HR, 0.78; 95% CI, 0.65-0.93; P = 0.007). CLBC
incidence data also continued to favor anastrozole (odds ratio [OR], 0.62; 95%
CI, 0.38-1.02; P = 0.062), and statistical significance was achieved in the
hormone receptor-positive subgroup (OR, 0.56; 95% CI, 0.32-0.98; P = 0.042). The
updated safety analysis also confirmed the findings of the first analysis, in
that endometrial cancer (P = 0.007), vaginal bleeding and discharge (P < 0.001
for both), cerebrovascular events (P < 0.001), venous thromboembolic events (P <
0.001), and hot flashes (P < 0.001) all occurred less frequently in the
anastrozole group, whereas musculoskeletal disorders and fractures (P < 0.001
for both) continued to occur less frequently in the tamoxifen group. These
results indicated that the safety profile of anastrozole remained consistent.
CONCLUSIONS: After an additional follow-up period, anastrozole continues to show
superior efficacy, which is most apparent in the clinically relevant hormone
receptor-positive population. Furthermore, anastrozole has numerous noteworthy
advantages in terms of tolerability compared with tamoxifen. These findings
suggest that the benefits of anastrozole are likely to be maintained in the long
term and provide further support for the status of anastrozole as a valid
treatment option for postmenopausal women with hormone-sensitive early-stage
breast cancer. Endocrine treatments of breast cancer patients antagonize estrogen and may lead
to consequences of estrogen deprivation including menopausal symptoms. We
analyzed the changes in frequency and severity of menopausal symptoms in
patients receiving tamoxifen or aromatase inhibitors and identified factors
influencing these symptoms. One hundred and eighty-one consecutive
postmenopausal breast cancer patients scheduled to start endocrine treatment
were included in this prospective study. A menopause symptom questionnaire
covering vasomotor, atrophic, psychological, cognitive and somatic symptoms was
filled in at baseline, and after 1 and 3 months of therapy. Both first-line
tamoxifen and aromatase inhibitors induced an increase in the occurrence and
severity of hot flashes (p<0.0001 and p=0.014, respectively). Musculoskeletal
pain and dyspareunia significantly increased under first-line non-steroidal
aromatase inhibitors (p=0.0039 and p=0.001, respectively), while patients under
tamoxifen had significant decrease in sexual interest (p< or =0.0001). Younger
age was associated with more hot flashes and vaginal dryness at baseline, and
after 1 and 3 months of therapy (all p<0.02). We conclude that there are
significant differences between the early effects of tamoxifen and aromatase
inhibitors on menopausal symptoms of breast cancer patients. Our results
underscore the need for safe and effective non-hormonal interventions to
alleviate vasomotor and musculoskeletal symptoms which were the most prevalent
and severe symptoms. We reviewed therapeutic effects and harmful side effects in 33 patients with
advanced or recurrent breast cancer who underwent treatment with Anastrozole 1
mg/day in our department. The patients ranged in age from 40 to 83 years old
(median, 59). The Performance Status was 0-2, and there was 1 case of advanced
breast cancer and 32 cases of recurrent breast cancer. The duration of disease
was from 5 to 233 months (median, 50 months). The estrogen and/or progesterone
receptor-positive rate was 72.7%. Metastatic sites were in multiple organs in 9
cases, in the lung only in 1 case, in bone only in 12 cases, and in soft tissue
only in 10 cases. First-line therapy was used in 10 cases, second-line therapy
in 6 cases, and above third-line therapy in 17 cases. There was a complete
response in 3 cases, partial response in 5 cases, no long change in 13 cases, no
change in 9 cases, and progressive disease in 3 cases. The response rate was
24.3%, The response period ranged from 2 to 22 months (median, 8 months), and
clinical benefit was achieved in 63.7%. The clinical benefit rates for
first-line were 60%, second-line 83.3% and above third-line therapy 58.8%. The
response rate for patients with breast cancer resistant to Anthracyclines and/or
Taxanes was 20%. Time-to-progression ranged from 2 to 28 months (median, 11
months), and overall survival ranged from 7 to 30 months (median, 15 months).
The most frequent harmful side effects were rise in total cholesterol, general
fatigue, hot flashes and arthralgia (9.1%). In this study, we confirmed the
availability and safety of Anastrozole, which was suggested to be a useful drug
in salvage therapy for patients having resistance to Anthracyclines and/or
Taxanes, not only but also useful as a first- or second-line therapy. PURPOSE: Most male breast cancer tumours are hormone receptor-positive; the
patients therefore receive endocrine therapy. There is, however, a paucity of
published data on toxicities experienced by male breast cancer patients who are
prescribed endocrine therapy. In the present study, we examined rates of
adherence to and toxicity from endocrine treatments in male breast cancer
patients treated at a single institution.
PATIENTS AND METHODS: We conducted a retrospective study of male patients
diagnosed with breast cancer at The Ottawa Hospital Cancer Centre during
1981-2003. Data collected included patient age, hormone receptor status, therapy
adherence, self-reported toxicities, and type and duration of endocrine
therapies.
RESULTS: The review located 59 cases of early-stage and metastatic male breast
cancer. Median patient age was 68.0 years. Tamoxifen was given to 38 patients
(64.4%), anastrozole to 8 (13.6%), and letrozole to 5 (8.5%). Of patients who
received endocrine therapy, 10 (25%) received adjuvant systemic chemotherapy.
Toxicity was reported by 19 patients taking tamoxifen (50%), with hot flashes
being the most common complaint (18.4%). Decreased libido, weight gain, and
malaise were reported by 5 patients (13.2%). Rash and erectile dysfunction were
reported by 3 patients (7.9%). Increased liver enzymes, pulmonary embolism,
superficial thrombophlebitis, myalgia, depression, visual blurring, and loose
stools were each reported in 1 patient (2.6%). Tamoxifen therapy was
discontinued secondary to toxicity in 9 patients (23.7%). Of the patients
treated with anastrozole, 3 (37.5%) reported toxicity, with 1 report each of
decreased libido, leg swelling, and depression (12.5%). Toxicity was reported in
2 patients taking letrozole (40%), with both reporting peripheral edema, and 1
reporting hot flashes. No patient discontinued anastrozole or letrozole because
of toxicity.
CONCLUSIONS: Few studies specifically report data on adherence to and toxicities
from endocrine therapies in male breast cancer patients. The rate of
discontinuation at our institution because of toxicity (23.7%) is similar to
that reported in the female breast cancer population. Future prospective studies
should explore strategies to improve adherence to endocrine therapy in this
population. BACKGROUND: Poor prognosis is associated with estrogen- and/or progesterone
receptor-positive (ER(+), PGR(+)) premenopausal breast cancer (PM-BC) with high
Ki-67 labeling index and extensive axillary lymph node involvement. The role of
adjuvant chemotherapy (CT) and hormonal therapy have not yet been established in
these patients.
PATIENTS AND METHODS: Twenty-five PM-BC patients received, in sequence,
leuprorelin, taxane-anthracycline induction chemotherapy, radiation therapy, a
platinum-based intensification high-dose CT, followed by leuprorelin and
anastrazole for five years. Vascular endothelial growth factor (VEGF) levels
were measured as the primary end-point; secondary end-points were 10-year
relapse-free survival (RFS) and overall survival (OS) rates.
RESULTS: The median patient age was 44 years, and the mean number of positive
axillary nodes was 14. All patients were ER(+) and/or PGR(+), with a median
Ki-67 index of 33%. Five patients were Cerb-B2 positive. Grade 4 hematologic
toxicity was observed in all patients, no patient showed a decrease of cardiac
ejection fraction and hot flashes and arthralgias were of moderate intensity.
After a median follow-up of 70 months, VEGF levels significantly decreased
(p<0.001); 10-year RFS and OS were 76% and 78%, respectively.
CONCLUSION: Total estrogen blockade and high-dose CT in PM-BC patients is
feasible, has moderate toxicity, significantly reduces VEGF levels, and seems to
improve the expected RFS and OS. PURPOSE: To compare the effect of therapy with anastrozole versus a combination
of fulvestrant and anastrozole in women in first relapse of endocrine-responsive
breast cancer.
PATIENTS AND METHODS: Postmenopausal women, or premenopausal women receiving a
gonadotropin-releasing hormone agonist, with estrogen receptor- and/or
progesterone receptor-positive disease at first relapse after primary treatment
of localized disease were open-label randomly assigned to a fulvestrant loading
dose (LD) regimen followed by monthly injection plus 1 mg of anastrozole daily
or to 1 mg of anastrozole daily alone. The primary end point was time to
progression (TTP).
RESULTS: In all, 514 women were randomly assigned to fulvestrant plus
anastrozole (experimental arm; n = 258) or anastrozole (standard arm; n = 256).
Approximately two thirds had received adjuvant antiestrogens, but only eight
individuals had received an aromatase inhibitor. Median TTP was 10.8 and 10.2
months in the experimental versus standard arm, respectively (hazard ratio [HR]
= 0.99; 95% CI, 0.81 to 1.20; P = .91); median overall survival was 37.8 and
38.2 months, respectively (HR = 1.0; 95% CI, 0.76 to 1.32; P = 1.00). Incidences
of prespecified adverse events (AEs) were similar. Hot flashes were more common
in the experimental arm: 63 patients (24.6%) versus 35 patients (13.8%) in the
standard arm (P = .0023). Death owing to AEs was reported in 11 (4.3%) and five
patients (2.0%) in the experimental versus standard arm, respectively.
CONCLUSION: Fulvestrant (250 mg + LD regimen) in combination with anastrozole
offered no clinical efficacy advantage over anastrozole monotherapy in this
population of individuals with a relatively high proportion of previous adjuvant
antiestrogen exposure. We describe the case of a 56-year old woman with no prior psychiatric history
who was diagnosed with hormone receptor positive early-stage breast cancer and
who developed severe mood changes after administration of anastrozole, which
resolved after discontinuation of treatment. Aromatase inhibitors (AIs) are the
preferred hormonal approach for postmenopausal women with estrogen hormone
sensitive breast cancer. The third-generation agents (anastrozole, letrozole,
and exemestane) have been shown to be more effective and safer than the
selective estrogen receptor modulators tamoxifen and raloxifen. Treatment
strategies with these agents include the use of an AI as an upfront strategy for
5 years, as a sequential approach after 2-3 years of tamoxifen, or as extended
use after the classical 5 years of tamoxifen. The side effects of AIs, as
compared with selective estrogen receptor modulators, are different, reflecting
the specific mechanism of action of these drugs. AIs are well tolerated and
cause a lower incidence of gynecological symptoms (vaginal bleeding, discharge,
and endometrial neoplasia), venous thromboembolic events, and hot flashes
compared with tamoxifen. However, the use of AIs have been associated with loss
of bone density, arthralgia, myalgia, a negative effect on lipid metabolism, and
cardiovascular risk (Tomao et al., 2011). Mood disturbances, somnolence,
anxiety, fatigue, hot flashes, and memory impairment have been reported among
patients receiving anastrozole as adjuvant therapy. OBJECTIVES: Antiestrogen therapy can cause vasomotor symptoms similar to those
occurring during menopause, including hot flashes. Recent studies suggest that
acupuncture is effective in reducing vasomotor symptoms in patients with breast
cancer receiving tamoxifen. The purpose of this study was to assess the
feasibility and safety of acupuncture for treatment of hot flashes in Korean
patients with breast cancer receiving antiestrogen therapy.
DESIGN: This was a prospective single-arm observational study using before and
after measurements.
SETTINGS/LOCATION: The study was located at the East-West Medical Center at
Daegu Catholic University Medical Center, Daegu, Korea.
SUBJECTS: The subjects were 10 patients with breast cancer who were undergoing
antiestrogen therapy with tamoxifen or anastrozole and who were suffering from
hot flashes.
INTERVENTIONS: Acupuncture was administered 3 times a week for 4 consecutive
weeks, for 20±5 minutes at each session.
OUTCOME MEASURES: The outcome measure was severity of hot flashes assessed by
visual analogue scale (VAS) and total hot flash score.
RESULTS: During treatment, severity of hot flashes was reduced by 70%-95% in all
patients. Acupuncture significantly alleviated severity of hot flashes assessed
by a visual analogue scale (F=30.261; p<0.001) as well as the total hot flash
score (F=21.698; p=0.006). Four (4) weeks after the final treatment, symptoms
were not aggravated.
CONCLUSIONS: Acupuncture appeared to provide effective relief from hot flashes
among Korean women receiving antiestrogen therapy after surgery for breast
cancer, and the effects lasted for at least 1 month after termination of
treatment. A randomized controlled prospective study with a larger sample size
is required to clarify the role of acupuncture in the management of hot flashes
in Korean patients with breast cancer. |
What is the role of Inn1 in cytokinesis? | Inn1 associates with the contractile actomyosin ring at the end of mitosis and is needed for cytokinesis. Inn1 has a C2 domain at the amino terminus of the protein that is required for ingression of the plasma membrane during cytokinesis in budding yeast, whereas the remainder of the protein recruits Inn1 to the actomyosin ring | Cytokinesis in yeast can be achieved by plasma membrane ingression, which is
dependent on actomyosin ring constriction. Inn1 presumably couples these
processes by interaction with both the plasma membrane and the temporary
actomyosin ring component Hof1. In addition, an actomyosin ring independent
cytokinesis pathway exists in yeast. We here identified Cyk3, a key component of
the alternative pathway, as a novel interaction partner of Inn1. The
carboxy-terminal proline rich part of Inn1 binds the SH3 domains of either Cyk3
or Hof1. Strains with truncated proteins lacking either of these SH3 domains do
not display any severe phenotypes, but are synthetically lethal, demonstrating
their crucial role in cytokinesis. Overexpression of CYK3 leads to an actomyosin
ring independent recruitment of Inn1 to the bud neck, further supporting the
significance of this interaction in vivo. Moreover, overexpression of CYK3 in a
myo1 or an iqg1 deletion not only restores viability, but also the recruitment
of Inn1 to the bud neck. We propose that Cyk3 is part of an actomyosin ring
independent cytokinesis pathway, which acts as a rescue mechanism to recruit
Inn1 to the bud neck. In Saccharomyces cerevisiae the Cdc14 phosphatase plays a well-established role
in reverting phosphorylation events on substrates of the mitotic
cyclin-dependent kinase (M-Cdk1), thereby promoting mitotic exit and
downregulation of M-Cdk1 activity. Cdc14 localizes at the site of cell cleavage
after M-Cdk1 inactivation, suggesting that Cdc14 may perform a crucial, yet
ill-defined, role during cytokinesis. Here, we identified Inn1, as a novel
direct substrate of both M-Cdk1 and Cdc14. Cdc14 colocalizes with Inn1 at the
cell division site and interacts with the C-terminal proline-rich domain of Inn1
that mediates its binding to the SH3-domain-containing proteins Hof1 and Cyk3.
We show that phosphorylation of Inn1 by Cdk1 partially perturbs the interaction
of Inn1 with Cyk3 thereby reducing the levels of Cyk3 at the cell division site.
We propose that Cdc14 counteracts Cdk1 phosphorylation of Inn1 to facilitate
Inn1-Cyk3 complex formation and so promote cytokinesis. The chitin synthase that makes the primary septum during cell division in
budding yeasts is an important therapeutic target with an unknown activation
mechanism. We previously found that the C2-domain of the Saccharomyces
cerevisiae Inn1 protein plays an essential but uncharacterised role at the
cleavage site during cytokinesis. By combining a novel degron allele of INN1
with a point mutation in the C2-domain, we screened for mutations in other genes
that suppress the resulting defect in cell division. In this way, we identified
22 domit mutations of CHS2 (chitin synthase II) that map to two neighbouring
sites in the catalytic domain. Chs2 in isolated cell membranes is normally
nearly inactive (unless protease treatment is used to bypass inhibition);
however, the domit suppressor allele Chs2-V377I has enhanced activity in
vitro. We show that Inn1 associates with Chs2 in yeast cell extracts. It also
interacts in a yeast two-hybrid assay with the N-terminal 65% of Chs2, which
contains the catalytic domain. In addition to compensating for mutations in the
Inn1 C2-domain, the domit CHS2 alleles suppress cytokinesis defects produced
by the lack of the Cyk3 protein. Our data support a model in which the C2-domain
of Inn1 acts in conjunction with Cyk3 to regulate the catalytic domain of Chs2
during cytokinesis. These findings suggest novel approaches for developing
future drugs against important fungal pathogens. |
Which hormone deficiency is implicated in the Costello syndrome ? | Growth hormone deficiency is implicated in Costello syndrome. Growth hormone therapy should be administered with caution due to possible severe side effects. Cortisol and sex hormone deficiencies were also implicated in Costello syndrome. | The Costello syndrome is characterized by dwarfism, unique cutaneous lesions,
distinct facial gestalt, and mental retardation. We present a Japanese patient
with the Costello syndrome. She showed high serum IgM level during the early
infantile period. Nissen's fundplication was carried out to treat severe
gastroesophageal reflux. Endocrinological investigations revealed a partial
deficiency of growth hormone. We present the case of a boy with Costello syndrome who developed osteofibrous
dysplasia during a phase of growth hormone therapy. The lesion and the
accompanying pain disappeared after discontinuation of the therapy. Growth
hormone is a known mitogen for some neoplasms and osteofibrous dysplasia has
been reported to become aggressive. Thus, although osteofibrous dysplasia in
Costello syndrome has not been reported before, growth hormone therapy should be
used under close supervision in children with this syndrome. We report clinical findings in 17 adults with Costello syndrome ranging in age
from 16 to 40 years. Two patients in this series have had bladder carcinoma, the
only maligcy reported to affect adults with Costello syndrome. Benign tumors
included multiple ductal papillomata in two women, and a fourth ventricle mass
in one man, thought to be a choroid plexus papilloma. Endocrine problems in this
series were osteoporosis, central hypogonadism, and delayed puberty. Other
health problems were symptomatic Chiari malformations in three patients. Four
patients had adult-onset gastro-esophageal reflux, three of whom had Chiari
malformations. Fourteen adults had mild to moderate intellectual disability with
three individuals having severe intellectual disability; 15 individuals attained
some reading and writing skills and 14 showed ongoing acquisition of new skills
into adulthood. On the basis of this data, we recommend that neuro-imaging be
considered in adults with Costello syndrome if they develop symptoms suggestive
of a Chiari malformation. In the event of pubertal delay, endocrine
investigations are indicated and hormone treatment may be required. Bone density
assessments should be performed in adults with Costello syndrome, particularly
in those with pubertal abnormalities. Screening for microscopic hematuria as a
marker for bladder carcinoma may be indicated, although this requires further
evaluation. Costello syndrome is characterized by mental retardation, loose skin, coarse
facies, skeletal abnormalities, cardiovascular abnormalities (congenital heart
defects, cardiomyopathy, rhythm disturbances), and predisposition to neoplasia.
Endocrine abnormalities including growth hormone deficiency, adrenal
insufficiency, glucose intolerance, parathyroid adenoma with hyperprolactinemia
and hypoglycemia have been described. Hypoglycemia has been documented due to
growth hormone and cortisol deficiency. We report on two patients with Costello
syndrome and persistent hyperinsulinemic hypoglycemia and review the endocrine
manifestations of Costello syndrome. Both patients required diazoxide therapy to
stop the unregulated insulin secretion and maintain normoglycemia. The mechanism
of persistent hyperinsulinism in patients with Costello syndrome is unclear. Germline activation of H-RAS oncogenes is the primary cause of Costello syndrome
(CS), a neuro-cardio-facio-cutaneous developmental syndrome. Here we describe
the generation of a mouse model of CS by introduction of an oncogenic Gly12Val
mutation in the mouse H-Ras locus using homologous recombination in ES cells.
Germline expression of the endogenous H-RasG12V oncogene, even in homozygosis,
resulted in hyperplasia of the mammary gland. However, development of tumors in
these mice was rare. H-RasG12V mutant mice closely phenocopied some of the
abnormalities observed in patients with CS, including facial dysmorphia and
cardiomyopathies. These mice also displayed alterations in the homeostasis of
the cardiovascular system, including development of systemic hypertension,
extensive vascular remodeling, and fibrosis in both the heart and the kidneys.
This phenotype was age dependent and was a consequence of the abnormal
upregulation of the renin-Ang II system. Treatment with captopril, an inhibitor
of Ang II biosynthesis, prevented development of the hypertension condition,
vascular remodeling, and heart and kidney fibrosis. In addition, it partially
alleviated the observed cardiomyopathies. These mice should help in elucidating
the etiology of CS symptoms, identifying additional defects, and evaluating
potential therapeutic strategies. Costello syndrome (CS) is a rare congenital disorder characterized by failure to
thrive, craniofacial dysmorphisms, cardiac and skin abnormalities, mental
retardation, and predisposition to maligcies. CS is caused by heterozygous
gain-of-function mutations in HRAS that also occur as somatic alterations in
human tumors. HRAS is one of the three classical RAS proteins and cycles between
an active, GTP- and an inactive, GDP-bound conformation. We used primary human
skin fibroblasts from patients with CS as a model system to study the functional
consequences of HRAS mutations on endogenous signaling pathways. The GTP-bound
form of HRAS was significantly enriched in CS compared with normal fibroblasts.
Active HRAS is known to stimulate both the RAF-MEK-ERK and the PI3K-AKT
signaling cascade. Phosphorylation of MEK and ERK was normal in CS fibroblasts
under basal conditions and slightly prolonged after epidermal growth factor
(EGF) stimulation. Interestingly, basal phosphorylation of AKT was increased yet
more in CS fibroblasts. Moreover, AKT phosphorylation was diminished in the
early and enhanced in the late phase of EGF stimulation. Taken together, these
results document that CS-associated HRAS mutations result in prolonged signal
flux in a ligand-dependent manner. Our data suggest that altered cellular
response to growth factors rather than constitutive activation of HRAS
downstream signaling molecules may contribute to some of the clinical features
in patients with CS. Costello syndrome is characterized by severe failure-to-thrive, short stature,
cardiac abnormalities (heart defects, tachyarrhythmia, and hypertrophic
cardiomyopathy (HCM)), distinctive facial features, a predisposition to
papillomata and maligt tumors, postnatal cerebellar overgrowth resulting in
Chiari 1 malformation, and cognitive disabilities. De novo germline mutations in
the proto-oncogene HRAS cause Costello syndrome. Most mutations affect the
glycine residues in position 12 or 13, and more than 80% of patients share
p.G12S. To test the hypothesis that subtle genotype-phenotype differences exist,
we report the first cohort comparison between 12 Costello syndrome individuals
with p.G13C and individuals with p.G12S. The individuals with p.G13C had many
typical findings including polyhydramnios, failure-to-thrive, HCM, macrocephaly
with posterior fossa crowding, and developmental delay. Subjectively, their
facial features were less coarse. Statistically significant differences included
the absence of multifocal atrial tachycardia (P-value = 0.033), ulnar deviation
of the wrist (P < 0.001) and papillomata (P = 0.003), and fewer neurosurgical
procedures (P = 0.024). Fewer individuals with p.G13C had short stature (height
below -2 SD) without use of growth hormone (P < 0.001). The noteworthy absence
of maligt tumors did not reach statistical significance. Novel ectodermal
findings were noted in individuals with p.G13C, including loose anagen hair
resulting in easily pluckable hair with a matted appearance, different from the
tight curls typical for most Costello syndrome individuals. Unusually long eye
lashes requiring trimming are a novel finding we termed dolichocilia. These
distinctive ectodermal findings suggest a cell type specific effect of this
particular mutation. Additional patients are needed to validate these findings. The involvement of the Ras superfamily of GTPases in the pathogenesis of
rhabdomysarcoma (RMS) is not well understood. While mutant H-Ras leads to
embryonal RMS (ERMS) formation in experimental animals and in Costello syndrome
patients, no data exists on the potential role of Ras GTPases in the
pathogenesis of alveolar RMS (ARMS). To address this issue better, we focused on
the role of the GTP exchange factor RasGRF1 in this process. We observed that,
in comparison to normal skeletal muscle cells, RasGRF1 mRNA is upregulated in
the majority of human ARMS cell lines and subsequently confirmed its high
expression in patient samples. By employing confocal microscopy analysis, we
observed RasGRF1 accumulation in cell filopodia, which suggests its involvement
in ARMS cell migration. Furthermore, we observed that RasGRF1 becomes
phosphorylated in ARMS after stimulation by several pro-metastatic factors, such
as SDF-1 and HGF/SF, as well as after exposure to growth-promoting Igf-2 and
insulin. More importantly, activation of RasGRF1 expression correlated with
activation of p42/44 MAPK and AKT. When the expression of RasGRF1 was
down-regulated in ARMS cells by an shRNA strategy, these RasGRF1-kd RMS cells
did not respond to stimulation by SDF-1, HGF/SF, Igf-2 or insulin by
phosphorylation of p42/44 MAPK and AKT and lost their chemotactic
responsiveness; however, their adhesion was not affected. We also observed that
RasGRF1-kd ARMS cells proliferated at a very low rate in vitro, and, more
importantly, after inoculation into immunodeficient SCID/beige inbred mice they
formed significantly smaller tumors. We conclude that RasGRF1 plays an important
role in ARMS pathogenesis and is a new potential therapeutic target to inhibit
ARMS growth. Costello syndrome is caused by HRAS germline mutations affecting Gly(12) or
Gly(13) in >90% of cases and these are associated with a relatively homogeneous
phenotype. Rarer mutations in other HRAS codons were reported in patients with
an attenuated or mild phenotype. Disease-associated HRAS missense mutations
result in constitutive HRAS activation and increased RAF-MEK-ERK and PI3K-AKT
signal flow. Here we report on a novel heterozygous HRAS germline alteration,
c.266C>G (p.S89C), in a girl presenting with severe fetal hydrops and pleural
effusion, followed by a more benign postnatal course. A sibling with the same
mutation and fetal polyhydramnios showed a Dandy-Walker malformation; his
postnatal course was complicated by severe feeding difficulties. Their
apparently asymptomatic father is heterozygous for the c.266C>G change. By
functional analyses we identified reduced levels of active HRAS(S89C) and
diminished MEK, ERK and AKT phosphorylation in cells overexpressing HRAS(S89C) ,
which represent novel consequences of disease-associated HRAS mutations. Given
our patients' difficult neonatal course and presence of this change in their
asymptomatic father, we hypothesize that its harmful consequences may be time
limited, with the late fetal stage being most sensitive. Alternatively, the
phenotype may develop only in the presence of an additional as-yet-unknown
genetic modifier. While the pathogenicity of the HRAS c.266C>G change remains
unproven, our data may illustrate wide functional and phenotypic variability of
germline HRAS mutations. Costello syndrome is a rare condition due to heterozygous germline mutations in
the proto-oncogene HRAS. It affects multiple organ systems and includes severe
failure-to-thrive, short stature, and macrocephaly. The goal of this study was
to develop Costello syndrome-specific growth curves. We collected height,
weight, and head circumference (OFC) measurements from 94 individuals (45 males
and 49 females). Their HRAS mutation spectrum reflects previously published
cohorts, with p.G12S in 77.7%. Participants received medical care, therefore our
data does not reflect natural history per se, but rather growth with nutritional
support. Due to limited cohort size, we analyzed data from males and females
together. Weight-for-age data included 417 separate measurements from 80
individuals age 0-36 months, and 585 measurements from 82 individuals for age
0-10 years. Height-for-age data were derived from 391 measurements from 77
individuals age 0-36 months, and 591 measurements from 90 individuals age 0-10
years. Measurements obtained after growth hormone exposure in 15 individuals
were excluded in this analysis. The OFC curve was derived from 221 measurements
from 55 individuals age 0-36 months. Centiles (5th, 50th, and 95th) were
estimated across the age continuum for each growth parameter, and compared to
gender-specific curves for average stature individuals. The resulting curves
demonstrate very slow weight gain in the first 2 years. Short stature is seen in
many, but after age 4 years the 95th centile for height falls within the low
normal range for average stature children. Head circumference curves largely
overlap those for average stature, reflecting relative macrocephaly. |
List the components of a Replisome Progression Complex (RPC). | RPC components include the essential initiation and elongation factor, Cdc45, the checkpoint mediator Mrc1, the Tof1-Csm3 complex that allows replication forks to pause at protein-DNA barriers, the histone chaperone FACT (facilitates chromatin transcription) and Ctf4, which helps to establish sister chromatid cohesion. RPCs also interact with Mcm10 and topoisomerase I. | The components of the replisome that preserve genomic stability by controlling
the progression of eukaryotic DNA replication forks are poorly understood. Here,
we show that the GINS (go ichi ni san) complex allows the MCM (minichromosome
maintece) helicase to interact with key regulatory proteins in large
replisome progression complexes (RPCs) that are assembled during initiation and
disassembled at the end of S phase. RPC components include the essential
initiation and elongation factor, Cdc45, the checkpoint mediator Mrc1, the
Tof1-Csm3 complex that allows replication forks to pause at protein-DNA
barriers, the histone chaperone FACT (facilitates chromatin transcription) and
Ctf4, which helps to establish sister chromatid cohesion. RPCs also interact
with Mcm10 and topoisomerase I. During initiation, GINS is essential for a
specific subset of RPC proteins to interact with MCM. GINS is also important for
the normal progression of DNA replication forks, and we show that it is required
after initiation to maintain the association between MCM and Cdc45 within RPCs. The identity of the DNA helicase(s) involved in eukaryotic DNA replication is
still a matter of debate, but the mini-chromosome maintece (MCM) proteins are
the chief candidate. Six conserved MCM proteins, Mcm2-7, are essential for the
initiation and elongation stages of DNA replication, contain ATP binding pockets
and can form a hexameric structure resembling that of known prokaryotic and
viral helicases. However, biochemical proof of their presumed function has
remained elusive. Several recent reports confirm that the MCM complex is part of
the cellular machine responsible for the unwinding of DNA during S phase. In one
of these reports, the helicase activity of Mcm2-7 is finally revealed, when they
are purified in association with two partners: initiation factor Cdc45 and a
four-subunit complex called GINS. The Cdc45-MCM-GINS complex could constitute
the core of a larger macromolecular structure that has been termed the
"replisome progression complex". The eukaryotic replisome is a crucial determit of genome stability, but its
structure is still poorly understood. We found previously that many regulatory
proteins assemble around the MCM2-7 helicase at yeast replication forks to form
the replisome progression complex (RPC), which might link MCM2-7 to other
replisome components. Here, we show that the RPC associates with DNA polymerase
alpha that primes each Okazaki fragment during lagging strand synthesis. Our
data indicate that a complex of the GINS and Ctf4 components of the RPC is
crucial to couple MCM2-7 to DNA polymerase alpha. Others have found recently
that the Mrc1 subunit of RPCs binds DNA polymerase epsilon, which synthesises
the leading strand at DNA replication forks. We show that cells lacking both
Ctf4 and Mrc1 experience chronic activation of the DNA damage checkpoint during
chromosome replication and do not complete the cell cycle. These findings
indicate that coupling MCM2-7 to replicative polymerases is an important feature
of the regulation of chromosome replication in eukaryotes, and highlight a key
role for Ctf4 in this process. Yeast cells lacking Ctf18, the major subunit of an alternative Replication
Factor C complex, have multiple problems with genome stability. To understand
the in vivo function of the Ctf18 complex, we analyzed chromatin composition in
a ctf18Δ mutant using the quantitative proteomic technique of stable isotope
labeling by amino acids in cell culture. Three hundred and seven of the 491
reported chromosomal proteins were quantitated. The most marked abnormalities
occurred when cells were challenged with the replication inhibitor hydroxyurea.
Compared with wild type, hydroxyurea-treated ctf18Δ cells exhibited increased
chromatin association of replisome progression complex components including
Cdc45, Ctf4, and GINS complex subunits, the polymerase processivity clamp PCNA
and the single-stranded DNA-binding complex RPA. Chromatin composition
abnormalities observed in ctf18Δ cells were very similar to those of an mrc1Δ
mutant, which is defective in the activating the Rad53 checkpoint kinase in
response to DNA replication stress. We found that ctf18Δ cells are also
defective in Rad53 activation, revealing that the Ctf18 complex is required for
engagement of the DNA replication checkpoint. Inappropriate initiation of
replication at late origins, because of loss of the checkpoint, probably causes
the elevated level of chromatin-bound replisome proteins in the ctf18Δ mutant.
The role of Ctf18 in checkpoint activation is not shared by all Replication
Factor C-like complexes, because proteomic analysis revealed that cells lacking
Elg1 (the major subunit of a different Replication Factor C-like complex)
display a different spectrum of chromatin abnormalities. Identification of Ctf18
as a checkpoint protein highlights the usefulness of chromatin proteomic
analysis for understanding the in vivo function of proteins that mediate
chromatin transactions. BACKGROUND: Dia2 is an F-box protein found in the budding yeast, S. cerevisiae.
Together with Skp1 and Cul1, Dia2 forms the substrate-determining part of an E3
ubiquitin ligase complex, otherwise known as the SCF. Dia2 has previously been
implicated in the control of replication and genome stability via its
interaction with the replisome progression complex.
PRINCIPAL FINDINGS: We identified components of the RSC chromatin remodelling
complex as genetic interactors with Dia2, suggesting an additional role for Dia2
in the regulation of transcription. We show that Dia2 is involved in controlling
assembly of the RSC complex. RSC belongs to a group of ATP-dependent
nucleosome-remodelling complexes that controls the repositioning of nucleosomes.
The RSC complex is expressed abundantly and its 17 subunits are recruited to
chromatin in response to both transcription activation and repression. In the
absence of Dia2, RSC-mediated transcription regulation was impaired, with
concomitant abnormalities in nucleosome positioning.
CONCLUSIONS: Our findings imply that Dia2 is required for the correct assembly
and function of the RSC complex. Dia2, by controlling the RSC chromatin
remodeller, fine-tunes transcription by controlling nucleosome positioning
during transcriptional activation and repression. DNA unwinding at eukaryotic replication forks displaces parental histones, which
must be redeposited onto nascent DNA in order to preserve chromatin structure.
By screening systematically for replisome components that pick up histones
released from chromatin into a yeast cell extract, we found that the Mcm2
helicase subunit binds histones cooperatively with the FACT (facilitiates
chromatin transcription) complex, which helps to re-establish chromatin during
transcription. FACT does not associate with the Mcm2-7 helicase at replication
origins during G1 phase but is subsequently incorporated into the replisome
progression complex independently of histone binding and uniquely among histone
chaperones. The amino terminal tail of Mcm2 binds histones via a conserved motif
that is dispensable for DNA synthesis per se but helps preserve subtelomeric
chromatin, retain the 2 micron minichromosome, and support growth in the absence
of Ctf18-RFC. Our data indicate that the eukaryotic replication and
transcription machineries use analogous assemblies of multiple chaperones to
preserve chromatin integrity. |
What is the definition of minimal absent words? | An absent word of a word y of length n is a word that does not occur in y. It is a minimal absent word if all its proper factors occur in y. Minimal absent words have been computed in genomes of organisms from all domains of life; their computation also provides a fast alternative for measuring approximation in sequence comparison. | BACKGROUND: The problem of finding the shortest absent words in DNA data has
been recently addressed, and algorithms for its solution have been described. It
has been noted that longer absent words might also be of interest, but the
existing algorithms only provide generic absent words by trivially extending the
shortest ones.
RESULTS: We show how absent words relate to the repetitions and structure of the
data, and define a new and larger class of absent words, called minimal absent
words, that still captures the essential properties of the shortest absent words
introduced in recent works. The words of this new class are minimal in the sense
that if their leftmost or rightmost character is removed, then the resulting
word is no longer an absent word. We describe an algorithm for generating
minimal absent words that, in practice, runs in approximately linear time. An
implementation of this algorithm is publicly available at
ftp://www.ieeta.pt/~ap/maws.
CONCLUSION: Because the set of minimal absent words that we propose is much
larger than the set of the shortest absent words, it is potentially more useful
for applications that require a richer variety of absent words. Nevertheless,
the number of minimal absent words is still manageable since it grows at most
linearly with the string size, unlike generic absent words that grow
exponentially. Both the algorithm and the concepts upon which it depends shed
additional light on the structure of absent words and complement the existing
studies on the topic. An absent word (also called a forbidden word or an unword in other contexts) in
a sequence is a segment that does not appear in the given sequence. It is a
minimal absent word if all its proper factors occur in the given sequence. In
this article, we review the concept of minimal absent words, which includes the
notion of shortest absent words but is much stronger. We present an efficient
method for computing the minimal absent words of bounded length for DNA sequence
using a Trie of bounded depth, representing bounded length factors. This method
outputs the whole set of minimal absent words and furthermore our technique
provides a linear-time algorithm with less memory usage than previous solutions.
We also present an approach to distinguish sequences of different organisms
using their minimal absent words. Our solution applies a length-weighted index
to discriminate sequences and the results show that we can build phylogenetic
tree based on the patent collected information. |
What is the common feature in congenital central hypoventilation and Mowat-Wilson syndromes? | About 30% of Hirschsprung disease (HSCR) cases are syndromic. Hitherto, the disease causing gene has been identified for eight Mendelian syndromes with HSCR: congenital central hypoventilation (CCHS), Mowat-Wilson (MWS), Bardet-Biedl (BBS), Shah-Waardenburg (WS4), cartilage-hair-hypoplasia (CHH), Smith-Lemli-Opitz (SLO), Goldberg-Sprintzsen (GSS), and hydrocephalus due to congenital stenosis of the aqueduct of sylvius (HSAS). | BACKGROUND: In Hirschsprung's disease (HSCR), a hypomorphic allele of a major
gene, RET, accounts for most isolated (non-syndromic) cases, along with other
autosomal susceptibility loci under a multiplicative model. However, some
syndromic forms of HSCR are monogenic entities, for which the disease causing
gene is known.
OBJECTIVE: To determine whether RET could be considered a modifier gene for the
enteric phenotype on the background of a monogenic trait.
METHODS: The syndromic HSCR entities studied were congenital central
hypoventilation (CCHS) and Mowat-Wilson syndrome (MWS), caused by PHOX2B and
ZFHX1B gene mutations, respectively. The RET locus was genotyped in 143 CCHS
patients, among whom 44 had HSCR, and in 30 MWS patients, among whom 20 had
HSCR. The distribution of alleles, genotypes, and haplotypes was compared within
the different groups. To test the interaction in vivo, heterozygous mice were
bred for a null allele of Phox2b and Ret genes.
RESULTS: RET was shown to act as a modifier gene for the HSCR phenotype in
patients with CCHS but not with MWS. The intestine of double heterozygote mice
was indistinguishable from their littermates. A loss of over 50% of each gene
function seemed necessary in the mouse model for an enteric phenotype to occur.
CONCLUSIONS: In CCHS patients, the weak predisposing haplotype of the RET gene
can be regarded as a quantitative trait, being a risk factor for the HSCR
phenotype, while in MWS, for which the HSCR penetrance is high, the role of the
RET predisposing haplotype is not significant. It seems likely that there are
both RET dependent and RET independent HSCR cases. Hirschsprung's disease (HSCR) is a fairly frequent cause of intestinal
obstruction in children. It is characterized as a sex-linked heterogonous
disorder with variable severity and incomplete penetrance giving rise to a
variable pattern of inheritance. Although Hirschsprung's disease occurs as an
isolated phenotype in at least 70% of cases, it is not infrequently associated
with a number of congenital abnormalities and associated syndromes,
demonstrating a spectrum of congenital anomalies. Certain of these syndromic
phenotypes have been linked to distinct genetic sites, indicating underlying
genetic associations of the disease and probable gene-gene interaction, in its
pathogenesis. These associations with HSCR include Down's syndrome and other
chromosomal anomalies, Waardenburg syndrome and other Domit sensorineural
deafness, the Congenital Central Hypoventilation and Mowat-Wilson and other
brain-related syndromes, as well as the MEN2 and other tumour associations. A
number of other autosomal recessive syndromes include the Shah-Waardenburg, the
Bardet-Biedl and Cartilage-hair hypoplasia, Goldberg-Shprintzen syndromes and
other syndromes related to cholesterol and fat metabolism among others. The
genetics of Hirschsprung's disease are highly complex with the majority of known
genetic sites relating to the main susceptibility pathways (RET an EDNRB).
Non-syndromic non-familial, short-segment HSCR appears to represent a
non-Mendelian condition with variable expression and sex-dependent penetrance.
Syndromic and familial forms, on the other hand, have complex patterns of
inheritance and being reported as autosomal domit, recessive and polygenic
patterns of inheritance. The phenotypic variability and incomplete penetrance
observed in Hirschsprung's disease could also be explained by the involvement of
modifier genes, especially in its syndromic forms. In this review, we look at
the chromosomal and Mendelian associations and their underlying signalling
pathways, to obtain a better understanding of the pathogenetic mechanisms
involved in developing aganglionosis of the distal bowel. |
Which is the most common CFTR mutation in Caucasians? | The commonest CFTR mutation, deltaF508, is found in 74.1% of all CF chromosomes. In the Caucasian CF population, 57.5% are deltaF508 homozygotes but the UK ISC CF population with only 24.7%, has significantly fewer deltaF508 homozygotes patients (95% confidence interval (CI) 0.2-0.4). | To determine the nature and frequency of non-delta F508 cystic fibrosis (CF)
mutations among diverse populations, we have sequenced exons 9-12 and 19-23 of
the CF transmembrane conductance regulator (CFTR) gene from 128 CF chromosomes
(39 U.S. Caucasian, 27 African-American, 42 Northern Irish, and 20 Israeli
chromosomes). These regions were chosen because they encode the two putative
ATP-binding folds of CFTR, domains which appear to have functional significance.
In addition, CFTR exons 1 and 2 were analyzed in the American patients.
Mutations were found on 49 of the 128 CF chromosomes. Nineteen different
mutations were observed; six were novel, while the remaining 13 had been
reported previously by our group or by other investigators. Six of nine
different mutations found in African-American patients were unique to that
population. However, the vast majority of the mutations found in U.S. Caucasians
(eight of nine), Northern Irish (four of five), and Israelis (three of three)
also occurred in other Caucasian groups. The preponderance of previously
reported mutations in these three groups suggested that a subset of the
non-delta F508 mutations occur in common among Caucasians. A survey of mutation
frequencies in other Caucasian groups confirmed this observation. Unfortunately,
this subset accounts for less than half of non-delta F508 CF mutations in most
groups. These data suggest that screening for delta F508 and this select group
of mutations will efficiently and economically maximize the number of CF
mutations identified in Caucasian groups. However, it will be difficult to
detect more than 90% of mutant CFTR alleles except in ethnically and
geographically discrete populations where CF is the result of founder effect. Cystic fibrosis (CF) is a common genetic disorder in the Caucasian population.
The gene was identified in 1989 on the basis of its map location on chromosome
7. The encoded gene product, named cystic fibrosis transmembrane conductance
regulator (CFTR), corresponds to a cAMP-regulated chloride channel found almost
exclusively in the secretory epithelial cells. Although the major mutation that
results in a single amino acid deletion (F508) accounts for 70% of the disease
alleles, more than 550 additional mutant alleles of different forms have been
detected. Many of these mutations can be divided into five general classes in
terms of their demonstrated or presumed molecular consequences. In addition, a
good correlation has been found between CFTR genotype and one of the clinical
variables--pancreatic function status. An unexpected finding, however, is the
documentation of CFTR mutations in patients with atypical CF disease
presentations, including congenital absence of vas deferens and several
pulmonary diseases. Thus, the implication of CFTR mutation is more profound than
CF alone. In most epithelial tissues Cl(-) transport relies on the cystic fibrosis
transmembrane conductance regulator (CFTR) which has dual function as a Cl(-)
channel and as a regulator of other ion channels. More than 900 different
mutations in the CFTR gene are the cause for defective transport of Cl(-) and
Na(+) and impaired secretion or absorption of electrolytes in cystic fibrosis.
However, the CFTR mutation delta F508 is the most common reason for the
frequently inherited disease among the Caucasian population. Maturation and
processing of delta F508-CFTR is defective which leads to expression of only
very little but functional CFTR in the cell membrane. Understanding the
processing and trafficking of CFTR may give a clue to the question as to how the
expression and residual function of delta F508-CFTR can be enhanced, and may
lead to the development of new pharmacological tools for the treatment of cystic
fibrosis. The objective was to determine the composition of the Cystic Fibrosis (CF)
Population attending specialist UK CF centres in terms of age, gender, age at
diagnosis, genotype and ethnicity. With the planned introduction of the national
CF screening programme in the UK, cystic fibrosis transmembrane regulator (CFTR)
mutations were compared between different ethnic groups enabling a UK-specific
frequency of mutations to be defined. Data were analysed from the patient
biographies held in the UK CF Database (see www.cystic-fibrosis.org.uk). The
currently registered population of 5,274 CF patients is 96.3% Caucasian with a
male preponderance that significantly increases with age. The majority of the
196 non-Caucasian CF patients are from the Indian Subcontinent (ISC), of which
one in 84 UK CF patients are of Pakistani origin. The commonest CFTR mutation,
deltaF508, is found in 74.1% of all CF chromosomes. In the Caucasian CF
population, 57.5% are deltaF508 homozygotes but the UK ISC CF population with
only 24.7%, has significantly fewer deltaF508 homozygotes patients (95%
confidence interval (CI) 0.2-0.4). The distribution of Caucasian patients with
deltaF508/deltaF508, deltaF508/Other and Other/Other does not fit the expected
distribution with a Hardy-Weinberg model unless those patients without a
detected mutation are excluded (P<0.001). The UK CF Database has shown the UK CF
population to have distinct characteristics separate from the North American and
European CF Registries. The ISC group contains many mutations not recognised by
current genetic analysis, and one in four ISC patients have no CFTR mutations
identified. The CFTR analysis proposed for the screening programme would detect
96% of patients registered in the database, but is unlikely to achieve the
desired >80% detection rates in the ethnic minority groups. Screen-positive,
non-Caucasian infants without an identifiable CFTR mutation should be referred
for a sweat test and genetic counselling when serum trypsinogen concentrations
remain elevated after birth. Alveolar macrophages (AMs) play a major role in host defense against microbial
infections in the lung. To perform this function, these cells must ingest and
destroy pathogens, generally in phagosomes, as well as secrete a number of
products that signal other immune cells to respond. Recently, we demonstrated
that murine alveolar macrophages employ the cystic fibrosis transmembrane
conductance regulator (CFTR) Cl(-) channel as a determit in lysosomal
acidification (Di, A., Brown, M. E., Deriy, L. V., Li, C., Szeto, F. L., Chen,
Y., Huang, P., Tong, J., Naren, A. P., Bindokas, V., Palfrey, H. C., and Nelson,
D. J. (2006) Nat. Cell Biol. 8, 933-944). Lysosomes and phagosomes in murine
cftr(-/-) AMs failed to acidify, and the cells were deficient in bacterial
killing compared with wild type controls. Cystic fibrosis is caused by mutations
in CFTR and is characterized by chronic lung infections. The information about
relationships between the CFTR genotype and the disease phenotype is scarce both
on the organismal and cellular level. The most common disease-causing mutation,
DeltaF508, is found in 70% of patients with cystic fibrosis. The mutant protein
fails to fold properly and is targeted for proteosomal degradation. G551D, the
second most common mutation, causes loss of function of the protein at the
plasma membrane. In this study, we have investigated the impact of CFTR
DeltaF508 and G551D on a set of core intracellular functions, including
organellar acidification, granule secretion, and microbicidal activity in the
AM. Utilizing primary AMs from wild type, cftr(-/-), as well as mutant mice, we
show a tight correlation between CFTR genotype and levels of lysosomal
acidification, bacterial killing, and agonist-induced secretory responses, all
of which would be expected to contribute to a significant impact on microbial
clearance in the lung. BACKGROUND: Numerous studies have reported CFTR mutations in CBAVD (congenital
bilateral absence of the vas deferens) patients, but their results are not
completely consistent. Here, we present a systemic review and meta-analysis with
emphasis on clarifying further the genetic association of CFTR mutations with
CBAVD.
METHODS: We searched the MEDLINE database until March, 2011 for eligible
articles reporting CFTR mutations in CBAVD. Relevant data from each included
study were abstracted by two independent reviewers. The overall frequency of
CFTR mutations in CBAVD and the odds ratio (OR) for common specific alleles were
pooled under random-effect or fixed-effect model as appropriate. Subgroup
analysis was performed by ethnicity, and potential heterogeneity and bias were
both assessed.
RESULTS: Among CBAVD patients, 78% had at least one CFTR mutation, 46% having
two and 28% only one. Moreover, the common heterozygous F508del/5T and
F508del/R117H were observed in 17 and 4% of CBAVD cases respectively, and the
allele frequency in CBAVD was 17% for F508del, 25% for 5T and 3% for R117H.
Subgroup analysis indicated an increased frequency of cases with two mutations
in Caucasian patients than in Non-Caucasian (68 versus 50%, P= 0.012), but no
differences for cases with at least one mutation (88 versus 77%, P= 0.163) or
with only one mutation (17 versus 25%, P= 0.115). Caucasian patients had higher
F508del frequency, but lower 5T frequency, than Non-Caucasian (22 versus 8%, P=
0.001; 20 versus 31%, P= 0.009). Summary OR was 9.25 for 5T [95% confidence
interval (CI) 7.07-12.11, P= 0.000], with moderate heterogeneity (I(2)= 49.20%,
P= 0.019) and evident bias (Egger's test, P= 0.005), and it was 19.43 for
5T/(TG)12_13 (95% CI 10.48-30.03, P= 0.000) without any evidence of
heterogeneity (I(2)= 0.1%, P= 0.391) and bias (Egger's test, P= 0.160). The OR
for 5T/(TG)12_13 was significantly higher than that for 5T allele (P= 0.000).
CONCLUSIONS: In summary, our results demonstrate a high frequency of CFTR
mutations in CBAVD patients, and these exhibit evident ethnic differences. In
addition, 5T allele and 5T/(TG)12_13 may contribute to the increased risk for
CBAVD, with the 5T penetrance probably being modulated by adjacent (TG)12_13. Cystic fibrosis is the most common inherited lethal disease in Caucasians. It is
caused by mutations in the cystic fibrosis transmembrane conductance regulator
(CFTR), of which the cftr ΔF508 mutation is the most common. ΔF508 macrophages
are intrinsically defective in autophagy because of the sequestration of
essential autophagy molecules within unprocessed CFTR aggregates. Defective
autophagy allows Burkholderia cenocepacia (B. cepacia) to survive and replicate
in ΔF508 macrophages. Infection by B. cepacia poses a great risk to cystic
fibrosis patients because it causes accelerated lung inflammation and, in some
cases, a lethal necrotizing pneumonia. Autophagy is a cell survival mechanism
whereby an autophagosome engulfs non-functional organelles and delivers them to
the lysosome for degradation. The ubiquitin binding adaptor protein SQSTM1/p62
is required for the delivery of several ubiquitinated cargos to the
autophagosome. In WT macrophages, p62 depletion and overexpression lead to
increased and decreased bacterial intracellular survival, respectively. In
contrast, depletion of p62 in ΔF508 macrophages results in decreased bacterial
survival, whereas overexpression of p62 leads to increased B. cepacia
intracellular growth. Interestingly, the depletion of p62 from ΔF508 macrophages
results in the release of the autophagy molecule beclin1 (BECN1) from the mutant
CFTR aggregates and allows its redistribution and recruitment to the B. cepacia
vacuole, mediating the acquisition of the autophagy marker LC3 and bacterial
clearance via autophagy. These data demonstrate that p62 differentially dictates
the fate of B. cepacia infection in WT and ΔF508 macrophages. BACKGROUND: Cigarette smoking causes Chronic Obstructive Pulmonary Disease
(COPD), the 3rd leading cause of death in the U.S. CFTR ion transport
dysfunction has been implicated in COPD pathogenesis, and is associated with
chronic bronchitis. However, susceptibility to smoke induced lung injury is
variable and the underlying genetic contributors remain unclear. We hypothesized
that presence of CFTR mutation heterozygosity may alter susceptibility to
cigarette smoke induced CFTR dysfunction. Consequently, COPD patients with
chronic bronchitis may have a higher rate of CFTR mutations compared to the
general population.
METHODS: Primary human bronchial epithelial cells derived from F508del CFTR
heterozygotes and mice with (CFTR+/-) and without (CFTR+/+) CFTR heterozygosity
were exposed to whole cigarette smoke (WCS); CFTR-dependent ion transport was
assessed by Ussing chamber electrophysiology and nasal potential difference
measurements, respectively. Caucasians with COPD and chronic bronchitis, age 40
to 80 with FEV1/FVC < 0.70 and FEV1 < 60% predicted, were selected for genetic
analysis from participants in the NIH COPD Clinical Research Network's
Azithromycin for Prevention of Exacerbations of COPD in comparison to 32,900
Caucasian women who underwent prenatal genetic testing. Genetic analysis
involved an allele-specific genotyping of 89 CFTR mutations.
RESULTS: Exposure to WCS caused a pronounced reduction in CFTR activity in both
CFTR (+/+) cells and F508del CFTR (+/-) cells; however, neither the degree of
decrement (44.7% wild-type vs. 53.5% F508del heterozygous, P = NS) nor the
residual CFTR activity were altered by CFTR heterozygosity. Similarly, WCS
caused a marked reduction in CFTR activity measured by NPD in both wild type and
CFTR heterozygous mice, but the severity of decrement (91.1% wild type vs. 47.7%
CF heterozygous, P = NS) and the residual activity were not significantly
affected by CFTR genetic status. Five of 127 (3.9%) COPD patients with chronic
bronchitis were heterozygous for CFTR mutations which was not significantly
different from controls (4.5%) (P = NS).
CONCLUSIONS: The magnitude of WCS induced reductions in CFTR activity was not
affected by the presence of CFTR mutation heterozygosity. CFTR mutations do not
increase the risk of COPD with chronic bronchitis. CFTR dysfunction due to
smoking is primarily an acquired phenomenon and is not affected by the presence
of congenital CFTR mutations. |
Which CDK targets control cytokinesis? | Aip1, Ede1 and Inn1 are CDK targets whose dephosphorylation is required for cytokinesis. | The final event of the eukaryotic cell cycle is cytokinesis, when two new
daughter cells are born. How the timing and execution of cytokinesis is
controlled is poorly understood. Here, we show that downregulation of
cyclin-dependent kinase (Cdk) activity, together with upregulation of its
counteracting phosphatase Cdc14, controls each of the sequential steps of
cytokinesis, including furrow ingression, membrane resolution and cell
separation in budding yeast. We use phosphoproteome analysis of mitotic exit to
identify Cdk targets that are dephosphorylated at the time of cytokinesis. We
then apply a new and widely applicable tool to generate conditionally
phosphorylated proteins to identify those whose dephosphorylation is required
for cytokinesis. This approach identifies Aip1, Ede1 and Inn1 as cytokinetic
regulators. Our results suggest that cytokinesis is coordinately controlled by
the master cell cycle regulator Cdk together with its counteracting phosphatase
and that it is executed by concerted dephosphorylation of Cdk targets involved
in several cell biological processes. |
Are Alu elements transcribed? | A significant percentage of the more than 1 million copies of Alu elements was shown to be transrcribed. Free Alu RNAs are known to be transcribed by Pol III from their own promoter. On the other hand, embedded Alu RNAs are transcribed by Pol II as part of protein- and non-protein-coding RNAs. Recent studies have demonstrated that both free and embedded Alu RNAs play a major role in post transcriptional regulation of gene expression. | Alu and 7SL RNA gene sequences were tested for the potential to regulate
mammalian cell growth by introducing these sequences into HeLa cells in a
coupled DEAE-dextran transfection/affinity cell sorting system. Both Alu and 7SL
RNA genes mediated inhibition of [3H]thymidine and [35S]methionine incorporation
in recipient cells. In addition, short term growth curves were performed on
calcium phosphate/DNA cotransfected, affinity-purified cells. This second assay
revealed that transfected Alu and 7SL RNA can also cause suppression of HeLa
cell proliferation. To investigate whether transcription or polymerase III (pol
III) transcription factor binding was required for inhibitory activity,
mutations were introduced into RNA pol III B block promoter elements in each of
these genes. Suppression of [3H]thymidine incorporation was dependent on the
presence of this pol III element in both genes; likewise, 7SL RNA-mediated
growth suppression required the presence of the pol III B block promoter
element. The results of this study indicate that Alu and 7SL RNA gene sequences
interact with cellular factors that are important for HeLa cell proliferation
and suggest that these pol III-transcribed elements may be involved in the
regulation of cellular growth. The amplification of genomic Alu elements by retroposition, i.e. by
reintegration of reverse-transcribed RNA, suggests that Alu RNA plays an
important role in this process. We report enzymatic studies of the secondary
structure of Alu RNAs transcribed in vitro from two recently retroposed Alu
elements. These experiments show that the dimeric organization of an Alu
sequence is reflected in its RNA folding. Alu subunits fold independently,
conserving secondary structure motifs of their progenitor 7 SL RNA molecule.
Energy minimization analysis indicates that this folding pattern is also
characteristic of different Alu and Alu-like sequences and has been conserved
since primate divergence. By analogy to 7 SL RNA, the Alu RNA folding may be
important for specific interactions with proteins. This could indicate a
physiological function for Alu transcripts. However, this can be also seen as a
structural adaptation leading to efficient retroposition of these sequence
elements. The human genome is rich in sequences which are structurally related to the 7SL
RNA component of the signal recognition particle. The 7SL DNA sequence family
consists of four 7SL genes, 500 7SL pseudogenes (which are truncated at one or
both ends of the 7SL sequence) and 500,000 Alu sequences. Both 7SL genes and Alu
elements are transcribed by RNA polymerase III, and we show here that the
internal 7SL promoter lies within the Alu-like part of the 7SL gene. Why then
does RNA polymerase III transcribe the few 7SL genes so efficiently, while
transcripts from the far more abundant Alu elements are not readily detectable?
We find that a human 7SL gene and a synthetic Alu sequence derived from it are
expressed 50-100-fold more efficiently in vitro than either a representative Alu
element or two 7SL pseudogenes. 5' Deletion and insertion mutants of the 7SL
gene demonstrate that, in conjunction with the internal promoter, the first 37
nucleotides upstream from the transcription start site are essential for
efficient and accurate initiation in vitro. We suggest that the genomic
sequences upstream from most Alu elements and 7SL pseudogenes do not contain
this element, and consequently that only a small subset of such sequences can be
transcribed in vivo. This may help to explain the homogeneity of the Alu family
within each mammalian genome, as well as the species-specific differences
between mammalian Alu families. We previously demonstrated that pseudogenes complementary to the small nuclear
RNAs U1, U2 and U3 are dispersed and abundant in the human genome. Here we
report that three pseudogenes (U1.101, U2.13 and U3.5) are flanked by perfect
short direct repeats of 16 to 19 base pairs. In all three pseudogenes. the
upstream direct repeat abuts a DNA sequence corresponding to the 5' end of the
mature snRNA; in U2.13 and U3.5, the downstream direct repeat immediately
follows the truncated 3' end of the snRNA sequence, whereas in U1.101, the
downstream direct repeat is separated from the 3, end of the full-length snRNA
sequence by a short A-rich region. We consider the direct repeats to be an
indication that these three pseudogenes were created by insertion of snRNA
information into a new chromosomal locus. To explain why the upstream repeat
abuts a DNA sequence complementary to the 5' end of the mature snRNA, we propose
a model for insertion that uses a reverse transcript of the snRNA as an
intermediate. Furthermore, we note similarities between the structure of all
three pseudogene loci and the Alu family of middle repetitive DNA sequences.
These similarities suggest that some Alu family sequences are mobile genetic
elements that can transpose to new chromosomal loci using as an intermediate a
cDNA copy of an RNA transcribed from the Alu family element by RNA polymerase
III. Primate and rodent genomes are populated with hundreds of thousands copies of
Alu and B1 elements dispersed by retroposition, i.e., by genomic reintegration
of their reverse transcribed RNAs. These, as well as primate BC200 and rodent
4.5S RNAs, are ancestrally related to the terminal portions of 7SL RNA sequence.
The secondary structure of 7SL RNA (an integral component of the signal
recognition particle) is conserved from prokaryotes to distant eukaryotic
species. Yet only in primates and rodents did this molecule give rise to
retroposing Alu and B1 RNAs and to apparently functional BC200 and 4.5S RNAs. To
understand this transition and the underlying molecular events, we examined, by
comparative analysis, the evolution of RNA structure in this family of molecules
derived from 7SL RNA. RNA sequences of different simian (mostly human) and
prosimian Alu subfamilies as well as rodent B1 repeats were derived from their
genomic consensus sequences taken from the literature and our unpublished
results (prosimian and New World Monkey). RNA secondary structures were
determined by enzymatic studies (new data on 4.5S RNA are presented) and/or
energy minimization analyses followed by phylogenetic comparison. Although, with
the exception of 4.5S RNA, all 7SL-derived RNA species maintain the cruciform
structure of their progenitor, the details of 7SL RNA folding domains are
modified to a different extent in various RNA groups. Novel motifs found in
retropositionally active RNAs are conserved among Alu and B1 subfamilies in
different genomes. In RNAs that do not proliferate by retroposition these motifs
are modified further. This indicates structural adaptation of 7SL-like RNA
molecules to novel functions, presumably mediated by specific interactions with
proteins; these functions were either useful for the host or served the selfish
propagation of RNA templates within the host genome. More than one million copies of the approximately 300-bp Alu element are
interspersed throughout the human genome, with up to 75% of all known genes
having Alu insertions within their introns and/or UTRs. Transcribed Alu
sequences can alter splicing patterns by generating new exons, but other impacts
of intragenic Alu elements on their host RNA are largely unexplored. Recently,
repeat elements present in the introns or 3'-UTRs of 15 human brain RNAs have
been shown to be targets for multiple adenosine to inosine (A-to-I) editing.
Using a statistical approach, we find that editing of transcripts with embedded
Alu sequences is a global phenomenon in the human transcriptome, observed in
2674 ( approximately 2%) of all publicly available full-length human cDNAs (n =
128,406), from >250 libraries and >30 tissue sources. In the vast majority of
edited RNAs, A-to-I substitutions are clustered within transcribed sense or
antisense Alu sequences. Edited bases are primarily associated with retained
introns, extended UTRs, or with transcripts that have no corresponding known
gene. Therefore, Alu-associated RNA editing may be a mechanism for marking
nonstandard transcripts, not destined for translation. Alu elements are the most abundant repetitive elements in the human genome; they
emerged from the signal recognition particle RNA gene and are composed of two
related but distinct monomers (left and right arms). Alu RNAs transcribed from
these elements are present at low levels at normal cell growth but various
stress conditions increase their abundance. Alu RNAs are known to bind the
cognate proteins SRP9/14. We purified synthetic Alu RNP, composed of Alu RNA in
complex with SRP9/14, and investigated the effects of Alu RNPs and naked Alu RNA
on protein translation. We found that the dimeric Alu RNP and the monomeric left
and right Alu RNPs have a general dose-dependent inhibitory effect on protein
translation. In the absence of SRP9/14, Alu RNA has a stimulatory effect on all
reporter mRNAs. The unstable structure of sRight RNA suggests that the
differential activities of Alu RNP and Alu RNA may be explained by
conformational changes in the RNA. We demonstrate that Alu RNPs and Alu RNAs do
not stably associate with ribosomes during translation and, based on the
analysis of polysome profiles and synchronized translation, we show that Alu RNP
and Alu RNA regulate translation at the level of initiation. Alu elements are the most abundant repetitive elements in the human genome; they
have amplified by retrotransposition to reach the present number of more than
one million copies. Alu elements can be transcribed in two different ways, by
two independent polymerases. 'Free Alu RNAs' are transcribed by Pol III from
their own promoter, while 'embedded Alu RNAs' are transcribed by Pol II as part
of protein- and non-protein-coding RNAs. Recent studies have demonstrated that
both free and embedded Alu RNAs play a major role in post transcriptional
regulation of gene expression, for example by affecting protein translation,
alternative splicing and mRNA stability. These discoveries illustrate how a part
of the 'junk DNA' content of the human genome has been recruited to important
functions in regulation of gene expression. BACKGROUND: The vast majority of the 1.1 million Alu elements are
retrotranspositionally inactive, where only a few loci referred to as 'source
elements' can generate new Alu insertions. The first step in identifying the
active Alu sources is to determine the loci transcribed by RNA polymerase III
(pol III). Previous genome-wide analyses from normal and transformed cell lines
identified multiple Alu loci occupied by pol III factors, making them candidate
source elements.
FINDINGS: Analysis of the data from these genome-wide studies determined that
the majority of pol III-bound Alus belonged to the older subfamilies Alu S and
Alu J, which varied between cell lines from 62.5% to 98.7% of the identified
loci. The pol III-bound Alus were further scored for estimated
retrotransposition potential (ERP) based on the absence or presence of selected
sequence features associated with Alu retrotransposition capability. Our
analyses indicate that most of the pol III-bound Alu loci candidates identified
lack the sequence characteristics important for retrotransposition.
CONCLUSIONS: These data suggest that Alu expression likely varies by cell type,
growth conditions and transformation state. This variation could extend to where
the same cell lines in different laboratories present different Alu expression
patterns. The vast majority of Alu loci potentially transcribed by RNA pol III
lack important sequence features for retrotransposition and the majority of
potentially active Alu loci in the genome (scored high ERP) belong to young Alu
subfamilies. Our observations suggest that in an in vivo scenario, the
contribution of Alu activity on somatic genetic damage may significantly vary
between individuals and tissues. |
In what type(s) of plant organelles we can detect prolamellar bodies? | Prolamellar body (PLB) is a highly organized lipid structure, which is the main site of accumulation of the ternary light-harvesting POR complex LHPP (light-harvesting NADPH:protochlorophyllide oxidoreductase:protochlorophyllide). Prolamellar bodies have been discovered in etioplasts with the use of thin section electron microscopy. Etioplasts develop in the place of chloroplasts in the dark. During skotomorphogenesis in angiosperms, NADPH:protochlorophyllide oxidoreductase (POR) forms the photolabile NADPH-POR-protochlorophyllide (Pchlide) ternary complexes. Prolamellar bodies (PLBs) efficiently capture the light energy for photo conversion in etioplasts. Upon illumination, the etioplasts transformed into regular chloroplasts. PLBs are formed not only in etioplasts but also in chloroplasts in young developing leaves during the night. | We have identified a mutant of pea cultivar Alaska that has many of the
characteristics normally associated with light-grown seedlings even when grown
in complete darkness. We have designated this mutant lip1, for light independent
photomorphogenesis. Etiolated wild-type pea seedlings are white to slightly
yellow in color and have a distinct morphology characterized by elongated
epicotyls and buds containing unexpanded leaves with small, undifferentiated
cells. In contrast, mutant seedlings grown under the same conditions are yellow
in color and have short epicotyls and expanded leaves showing clear cellular
differentiation. Transmission electron microscopy revealed partially developed,
agranal plastids in the dark-grown mutant, unlike wild-type seedlings that
contain etioplasts with prolamellar bodies. The mutant also exhibits a much
shorter lag period for chlorophyll accumulation when etiolated seedlings are
transferred from darkness to white light. The dark-grown mutant has 10-fold less
spectrally detectable phytochrome, which can be attributed to a 10-fold
reduction in the level of the PHYA polypeptide. Cab, Fed1, and RbcS transcripts
are present in dark-grown mutant seedlings at levels comparable to those
produced in light-grown material. The levels of these transcripts show a normal
decrease when green plants grown for 15 days in a light/dark cycle are
transferred to continuous darkness. However, transcript levels remain high
during dark treatment of seedlings grown for 9 days in continuous light,
indicating that the dark adaptation response in this mutant is developmentally
plastic. The lip1 mutant has several features in common with the deetiolated
Arabidopsis mutants det1, det2, and cop1. However, there are also several
important differences, including varying effects on phytochrome levels,
organ-specific gene expression, plastid development, and response to dark
adaptation. The biosynthesis of chlorophyll is a strictly light-dependent multistep process
in higher plants. The light-dependent step is catalysed by
NADPH:protochlorophyllide oxidoreductase (POR, EC.1.6.99.1), which reduces
protochlorophyllide (Pchlide) to chlorophyllide (Chlide). POR is nucleus-encoded
and post-translationally imported into plastids. It has been proposed that the
import of a POR protein isozyme (PORA) is totally dependent on Pchlide and uses
a novel import pathway. This proposal is based on findings that PORA import only
occurs in the presence of Pchlide and that the presence of overexpressed
precursor of Rubisco small subunit (pSS), a protein which is known to use the
general import pathway, does not outcompete PORA import. Another study
demonstrated that POR precursor protein (pPOR) can be cross-linked to one of the
components in the translocation machinery, Toc75, in the absence of Pchlide, and
that its import can be outcompeted by the addition of the pSS. This indicates
that pSS and pPOR may use the same translocation mechanism. Thus, POR does not
necessarily need Pchlide for import--which is in contrast to earlier
observations--and the exact POR import mechanism remains unresolved. Once in the
stroma, the POR transit peptide is cleaved off and the mature POR protein is
associated to the plastid inner membranes. Formation of the correct
membrane-associated, thermolysin-protected assembly is strictly dependent of
NADPH. As a final step, the formation of the NADPH-Pchlide-POR complex occurs.
When POR accumulates in the membranes of proplastids, an attraction of
monogalactosyl diacylglycerol (MGDG) can occur, leading to the formation of
prolamellar bodies (PLBs) and the development of etioplasts in darkness. A mechanism for the formation of lamellar systems in the plant cell has been
proposed as a result of electron microscope observations of young and mature
cells of Nitella cristata and the plastids of Zea mays in normal plants,
developing plants, and certain mutant types. The results are compatible with the
concept that lamellar structures arise by the fusion or coalescence of small
vesicular elements, giving rise initially to closed double membrane Structures
(cisternae). In the chloroplasts of Zea, the cisternae subsequently undergo
structural transformations to give rise to a compound layer structure already
described for the individual chloroplast lamellae. During normal development,
the minute vesicles in the young chloroplast are aggregated into one or more
dense granular bodies (prolamellar bodies) which often appear crystalline.
Lamellae grow out from these bodies. In fully etiolated leaves lamellae are
absent and the prolamellar bodies become quite large, presumably because of
inhibition of the fusion step which appears to require chlorophyll. Lamellae
develop rapidly on exposure of the plant to light, and subsequent development
closely parallels that seen under normal conditions. The plastids of white and
very pale green mutants of Zea similarly lack lamellae and contain only
vesicular elements. A specialized peripheral zone immediately below the double
limiting membrane in Zea chloroplasts appears to be responsible for the
production of vesicles. These may be immediately converted to lamellae under
normal conditions, but accumulate to form a prolamellar body if lamellar
formation is prevented, as in the case of etiolation and chlorophyll-deficient
mutation, or when the rate of lamellar formation is slower than that of the
production of precursor material (as appears to be the case in the early stages
of normal development). NADPH:protochlorophyllide oxidoreductase (POR) catalyzes the light-dependent
reduction of protochlorophyllide. To elucidate the physiological function of
three differentially regulated POR isoforms (PORA, PORB and PORC) in Arabidopsis
thaliana, we isolated T-DNA tagged null mutants of porB and porC. The mature
seedlings of the mutants had normal photosynthetic competencies, showing that
PORB and PORC are interchangeable and functionally redundant in developed
plants. In etiolated seedlings, only porB showed a reduction in the photoactive
protochlorophyllide and the size of prolamellar bodies (PLBs), indicating that
PORB, as well as PORA, functioned in PLB assembly and photoactive
protochlorophyllide formation in etiolated seedlings. When illuminated, the
etiolated porB seedling was able to green to a similar extent as the wild type,
whereas the greening was significantly reduced under low light conditions.
During greening, high light irradiation increased the level of PORC protein, and
the greening of porC was repressed under high light conditions. The porB, but
not porC, etiolated seedling was more sensitive to the far-red block of greening
than the wild type, which is caused by depletion of endogenous POR proteins
resulting in photo-oxidative damage. These results suggest that, at the onset of
greening, PLBs are important for efficient capture of light energy for
photoconversion under various light conditions, and PORC, which is induced by
high light irradiation, contributes to photoprotection during greening of the
etiolated seedlings. The aim of the present investigation was to find factors critical for the
co-existence of prolamellar bodies and prothylakoids in etioplasts of wheat
(Triticum aestivum L. cv Starke II). The lipid composition of the prolamellar
body and prothylakoid fractions was qualitatively similar. However, the molar
ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol was higher
in the prolamellar body fraction (1.6 +/- 0.1), as was the lipid content on a
protein basis. Protochlorophyllide was present in both fractions. The dominating
protein of the prolamellar body fraction was protochlorophyllide oxidoreductase.
This protein was present also in prothylakoid fractions. The other major protein
of the prothylakoid fraction was the coupling factor 1, subunit of the
chloroplast ATPase. From the lipid and protein data, we conclude that
prolamellar bodies are formed when monogalactosyl diacylglycerol is present in
larger amounts than can be stabilized into planar bilayer prothylakoid membranes
by lamellar lipids or proteins. In angiosperms, chlorophyll biosynthesis is light dependent. A key factor in
this process is protochlorophyllide oxidoreductase (POR), which requires light
to catalyze the reduction of protochlorophyllide to chlorophyllide. It is
believed that this protein originated from an ancient cyanobacterial enzyme that
was introduced into proto-plant cells during the primary symbiosis. Here we
report that PORs from the cyanobacteria Gloeobacter violaceus PCC7421 and
Synechocystis sp. PCC6803 function in plastids. First, we found that the G.
violaceus POR shows a higher affinity to its substrate protochlorophyllide than
the Synechocystis POR but a similar affinity to plant PORs. Secondly, the
reduced size of prolamellar bodies caused by a knockdown mutation of one of the
POR genes, PORA, in Arabidopsis could be complemented by heterologous expression
of the cyanobacterial PORs. Photoactive protochlorophyllide in the etioplasts of
the complementing lines, however, was retained at a low level as in the parent
PORA knockdown mutant, indicating that the observed formation of prolamellar
bodies was irrelevant to the assembly of photoactive protochlorophyllide. This
work reveals a new view on the formation of prolamellar bodies and provides new
clues about the function of POR in the etioplast-chloroplast transition. In angiosperms the strictly light-dependent reduction of protochlorophyllide to
chlorophyllide is catalyzed by NADPH:protochlorophyllide oxidoreductase (POR).
The Arabidopsis thaliana genome encodes three structurally related but
differentially regulated POR genes, PORA, PORB and PORC. PORA is expressed
primarily early in development-during etiolation, germination and greening. In
contrast, PORB and PORC are not only expressed during seedling development but
also throughout the later life of the plant, during which they are responsible
for bulk chlorophyll synthesis. The Arabidopsis porB-1 porC-1 mutant displays a
severe xantha (highly chlorophyll-deficient) phenotype characterized by smaller
prolamellar bodies in etioplasts and decreased thylakoid stacking in
chloroplasts. Here we have demonstrated the ability of an ectopic PORA
overexpression construct to restore prolamellar body formation in the porB-1
porC-1 double mutant background. In response to illumination, light-dependent
chlorophyll production, thylakoid stacking and photomorphogenesis are also
restored in PORA-overexpressing porB-1 porC-1 seedlings and adult plants. An
Arabidopsis porB-1 porC-1 double mutant can therefore be functionally rescued by
the addition of ectopically expressed PORA, which suffices in the absence of
either PORB or PORC to direct bulk chlorophyll synthesis and normal plant
development. NYB (Nanchong Yellow Barley) is a Chl-less barley mutant, which is controlled by
a recessive nuclear gene. It is the only protochlorophyllide oxidoreductases
(POR)-less barley mutant known in the world. The putative mechanism of the
mutation and its Chl synthesis and plastid development are studied here. Neither
PORC nor an additional copy of porB could be detected in barley. porB mRNAs are
normally expressed and correctly spliced in the mutant. However, the import of
PORA, PORB, LHCIIb1 (light harvesting complex II b1) and SSU (small subunit of
ribulose-1,5-bisphosphate carboxylase/oxygenase) proteins to the plastid was
greatly hampered in the mutant. We presume that a common translocon is mutated
in NYB. The content of the supramolecular light-harvesting POR complex LHPP
(light-harvesting NADPH:protochlorophyllide oxidoreductase:protochlorophyllide)
and the density of prolamellar bodies in etioplasts are decreased in the mutant.
However, no further oxidative damage could be observed for the de-etiolated
mutant seedlings after a dark to light shift. Development of the plastid is
arrested (less stacking) in NYB, and the mutant becomes more yellowish in
high-light conditions, with dwarfing of seedlings and decreased yield. The
physiological significance and developmental roles of POR proteins and LHPP in
barley cells are discussed. In Angiosperms, the reduction of protochlorophyllide (Pchlide) to chlorophyllide
(Chlide), a penultimate reaction of chlorophyll biosynthesis, is catalyzed by a
photoenzyme Pchlide oxidoreductase (POR) and completely inhibited in darkness.
This reaction plays also a regulatory role in plant morphogenesis. In the case
of dark-grown Angiosperms, Pchlide is accumulated, mainly in the form of
complexes with NADPH and POR but also as an unbound pigment. Etioplasts that
develop in the place of chloroplasts in the dark contain a highly organized
lipid structure termed prolamellar body (PLB), which is the main site of
accumulation of the ternary Pchlide:POR:NADPH complexes. An illumination
triggers the photoreduction of Pchlide molecules which are bound to the ternary
complexes. This is followed by a set of biochemical reactions and structural
changes leading to Chl synthesis that can be monitored with fluorescence
techniques. This chapter describes the application of low-temperature
fluorescence spectroscopy and fluorescence lifetime measurements for monitoring
the Pchlide to Chlide conversion in isolated prolamellar bodies. These
techniques enable the analysis of heterogeneity of accumulated pigments: Pchlide
and Chlide that reflect the different organization of pigment-protein complexes. NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR) is the key enzyme in
the light-induced greening of higher plants. A unique light-harvesting
POR:Pchlide complexes (LHPP) has been found in barley etioplasts, but not in
other plant species. Why PORs from barley, but not from other plants, can form
LHPP? And its function is not well understood. We modeled the barley and
Arabidopsis POR proteins and compared molecular surface. The results confirm the
idea that barley PORA can form a five-unit oligomer that interacts with a single
PORB. Chemical treatment experiments indicated that POR complex may be formed by
dithiol oxidation of cysteines of two adjacent proteins. We further showed that
LHPP assembly was needed for barley POR functions and seedling greening. On the
contrary, Arabidopsis POR proteins only formed dimers, which were not related to
the functions or the greening. Finally, POR complex assembly (including LHPP and
POR dimers) did not affect the formation of prolamellar bodies (PLBs) that
function for efficient capture of light energy for photo conversion in
etioplasts. The transformation of desiccoplasts into etioplasts and the parallel appearance
of protochlorophyllide (Pchlide) forms were observed with transmission electron
microscopy and 77K fluorescence spectroscopy, when air-dried detached leaves of
the poikilochlorophyllous desiccation tolerant plant Xerophyta humilis were
floated in water in the dark. After 1 week of rehydration, pregranal plastids
with newly synthesized prothylakoid (PT) lamellae and mainly non-photoactive
Pchlide forms developed, while etioplasts with prolamellar bodies (PLBs) and
photoactive, 655nm emitting Pchlide form accumulated primarily in the basal leaf
regions after 2 weeks of regeneration. When these latter leaves were illuminated
with continuous light for 3 days, the etioplasts transformed into regular
chloroplasts and the fluorescence emission bands characteristic of green leaves
appeared. These results show that, upon rehydration, the dehydrated chlorenchyma
cells are able to regenerate pregranal plastids and etioplasts from
desiccoplasts in the dark, which can transform into regular chloroplasts when
they are illuminated. This means that the differentiation of pregranal plastids
and etioplasts and their greening process is a basic property of fully
differentiated cells of X. humilis. Consequently, these processes are not merely
characteristic for seedlings with meristematic and differentiating young
tissues. Prolamellar bodies (PLBs) isolated from etiolated wheat seedlings were studied
with the use of atomic force microscopy (AFM), transmission electron microscopy
(TEM) and fluorescence spectroscopy. With AFM, PLBs were seen as spherical
structures about 1-2μm in diameter, more elastic than mica and poly-l-lysine
substrate. TEM analyses confirmed that PLBs of wheat leaf etioplasts also had an
average diameter of appr. 1μm. Illumination induced the photoreduction of
photoactive protochlorophyllide (Pchlide), i.e. Pchlide bound to
protochlorophyllide oxidoreductase, which was shown in fluorescence spectra. The
photoreduction was followed by the disruption of PLB structures, which started
with the enlargement of PLB spheres and then their fragmentation into small
balls as seen with AFM. Light-induced vesicle formation and the outgrowth of
lamellar (pro)thylakoid membranes on the PLB surface were also confirmed by TEM
analyses, and resulted in the apparent enlargement of the PLB diameter. The
blue-shift of the fluorescence emission maximum of chlorophyllide observed for
PLBs at room temperature after Pchlide photoreduction was completed within
25min. However, structural changes in PLBs were still observed after the
completion of the blue-shift. The incubation of PLBs in darkness with HgCl2 also
resulted in PLB enlargement and a loosening of their structure. AFM provides a
unique opportunity to observe PLBs at a physiological temperature without the
necessity of fixation. Angiosperms require light for chlorophyll biosynthesis because one reaction in
the pathway, the reduction of protochlorophyllide (Pchlide) to chlorophyllide,
is catalyzed by the light-dependent protochlorophyllide oxidoreductase (POR).
Here, we report that Cell growth defect factor1 (Cdf1), renamed here as
chaperone-like protein of POR1 (CPP1), an essential protein for chloroplast
development, plays a role in the regulation of POR stability and function.
Cdf1/CPP1 contains a J-like domain and three transmembrane domains, is localized
in the thylakoid and envelope membranes, and interacts with POR isoforms in
chloroplasts. CPP1 can stabilize POR proteins with its holdase chaperone
activity. CPP1 deficiency results in diminished POR protein accumulation and
defective chlorophyll synthesis, leading to photobleaching and growth inhibition
of plants under light conditions. CPP1 depletion also causes reduced POR
accumulation in etioplasts of dark-grown plants and as a result impairs the
formation of prolamellar bodies, which subsequently affects chloroplast
biogenesis upon illumination. Furthermore, in cyanobacteria, the CPP1 homolog
critically regulates POR accumulation and chlorophyll synthesis under high-light
conditions, in which the dark-operative Pchlide oxidoreductase is repressed by
its oxygen sensitivity. These findings and the ubiquitous presence of CPP1 in
oxygenic photosynthetic organisms suggest the conserved nature of CPP1 function
in the regulation of POR. A fraction of highly purified prolamellar bodies was isolated from etioplasts of
wheat (Triticum aestivum L. cv. Starke II, Weibull), as previously described by
Ryberg and Sundqvist (1982, Physiol. Plant., 56, 125-132). Studies on the
protein composition revealed that only one major polypeptide of an apparent
molecular weight of 36000 is present in the fraction of prolamellar bodies. This
polypeptide was identified as the NADPH-protochlorophyllide oxidoreductase. The
highest specific activity of the enzyme in etiolated leaf tissue was confirmed
to be in the fraction of prolamellar bodies. |
What do mepolizumab and reslizumab have in common? | Mepolizumab and reslizumab are monoclonal antibodies that target and neutralize interleukin 5. They have been shown to reduce eosinophil counts and they are used for the treatment of refractory asthma (associated with eosiniphilia) and other eosinophilic diseases. | Eosinophil-associated gastrointestinal disorders (EGIDs), including eosinophilic
esophagitis (EE) and eosinophilic gastroenteritis (EG), are a spectrum of
increasingly recognized inflammatory diseases characterized by gastrointestinal
symptoms and eosinophilic infiltration of the gastrointestinal tract.
Significant morbidity is associated with the development of esophageal
strictures in some patients. Immune-mediated reactions to food allergens appear
to drive the inflammation in a subset of patients, especially those with
solitary EE, but dietary interventions remain difficult in EE and are less
effective in EG. Despite the increasing incidence of these disorders and their
increased recognition by physicians, there are currently no medications that
either United States or European Union regulatory agencies have specifically
approved for use in EGIDs. This lack of safe and effective therapies for EGIDs
is a major obstacle in the care of these patients and underscores the need for
new therapeutic approaches. This review briefly discusses the currently
available 'off label' drug treatments for EGIDs, most notably topical and
systemic corticosteroids. Pathogenesis studies of EGIDs suggest possible
therapeutic targets, and conversely, clinical trials of mechanistically-targeted
therapeutics give insight into disease pathogenesis. Thus, EGID pathogenesis is
discussed as an introduction to mechanistically-targeted immunotherapeutics. The
two biologic categories that have been used in EGIDs, anti-IgE (omalizumab) and
anti-IL-5 (SCH55700/reslizumab and mepolizumab), are discussed. Because there
are similarities in the pathogenesis of EGIDs with asthma and atopic dermatitis,
biologic therapeutics currently in early trials for asthma management are also
briefly discussed as potential therapeutic agents for EGIDs. Given the
deficiencies of current therapeutics and the rapidly advancing knowledge of the
pathogenesis of these disorders, EGIDs are an ideal model for translating recent
advances in understanding immunopathogenesis into mechanistically-based
therapeutics. Further understanding of the early events in pathogenesis is also
needed to develop preventive and disease-modifying treatments. 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. 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. 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: A small proportion of patients with asthma have severe
disease characterized by persistent airflow obstruction, airway
hyperresponsiveness and eosinophilic airway inflammation. This review focuses on
the clinical efficacy of inhibiting T helper 2-cytokine-mediated inflammatory
responses using monoclonal antibodies directed against immunoglobulin E (IgE),
interleukin (IL)-5, and IL-4/IL-13 in patients with severe refractory asthma.
RECENT FINDINGS: The heterogeneity of airway inflammation in severe asthma has
led to the recognition of multiple pathophysiologically distinct severe asthma
endotypes. Biomarkers are being developed and evaluated to identify these
endotypes and to guide the use of specific biologics in the appropriate patients
who remain uncontrolled on high doses of inhaled corticosteroids and long-acting
bronchodilators or oral corticosteroids. Examples include the efficacy of
omalizumab in patients with severe refractory atopic asthma characterized by
raised serum total IgE, mepolizumab, reslizumab, and benralizumab in patients
with recurrent eosinophilic exacerbations characterized by blood and sputum
eosinophilia despite high doses of corticosteroids, and lebrikizumab,
pitrakinra, dupilumab, and tralokinumab that target the IL-4/IL-13 signalling
pathways in patients with eosinophilic asthma or raised serum periostin.
SUMMARY: In severe refractory asthma, both an understanding of the underlying
pathophysiologic mechanisms driving airway inflammation and the identification
of appropriate biomarkers in individual patients are critical in guiding the use
of biologics and monoclonal antibodies that target the specific pathological
processes. Asthma is a chronic inflammatory disease that often features eosinophilia,
especially in its most severe forms. Monoclonal antibodies directed towards
interleukin-5, such as mepolizumab or reslizumab, were shown to be very
effective at reducing blood and airways eosinophilia. When administered monthly
by intravenous or subcutaneous injection in severe eosinophilic asthmatic
patients, they reduce severe exacerbation rate by 50 %, improve asthma control
and quality of life, and have an oral glucocorticoids sparing effect in those
requiring oral corticoids as maintece therapy. |
When are itaconic acid levels elevated? | Itaconic acid levels are elevetad in immune defence. | Immunoresponsive gene 1 (Irg1) is highly expressed in mammalian macrophages
during inflammation, but its biological function has not yet been elucidated.
Here, we identify Irg1 as the gene coding for an enzyme producing itaconic acid
(also known as methylenesuccinic acid) through the decarboxylation of
cis-aconitate, a tricarboxylic acid cycle intermediate. Using a
gain-and-loss-of-function approach in both mouse and human immune cells, we
found Irg1 expression levels correlating with the amounts of itaconic acid, a
metabolite previously proposed to have an antimicrobial effect. We purified IRG1
protein and identified its cis-aconitate decarboxylating activity in an
enzymatic assay. Itaconic acid is an organic compound that inhibits isocitrate
lyase, the key enzyme of the glyoxylate shunt, a pathway essential for bacterial
growth under specific conditions. Here we show that itaconic acid inhibits the
growth of bacteria expressing isocitrate lyase, such as Salmonella enterica and
Mycobacterium tuberculosis. Furthermore, Irg1 gene silencing in macrophages
resulted in significantly decreased intracellular itaconic acid levels as well
as significantly reduced antimicrobial activity during bacterial infections.
Taken together, our results demonstrate that IRG1 links cellular metabolism with
immune defense by catalyzing itaconic acid production. Current early pregcy screening tools to identify women at risk of developing
gestational diabetes mellitus lack both specificity and sensitivity. As a
result, the foetus and mother are often subjected to insult during disease
progression, prior to diagnosis and treatment in later pregcy. Metabolomics
is an analytical approach, which allows for appraisal of small molecular mass
compounds in a biofluid. The aim of this pilot study was to investigate the
relationship between the early gestation serum metabolite profile and the
subsequent development of gestational diabetes mellitus in the search for early
pregcy biomarkers and potential metabolic mechanisms. Our nested case-control
study analysed maternal serum at 20 weeks' gestation, obtained from the New
Zealand cohort of the Screening for Pregcy Endpoints study. Metabolomic
profiling was performed using gas chromatography coupled to mass spectrometry,
and metabolites were identified using R software and an in-house mass spectral
library. Statistical analysis was performed using SPSS version 21.0. Forty-eight
metabolites were identified in the serum samples. Itaconic acid (P = 0.0003),
with a false discovery rate of 0.012, was found to be significantly more
abundant in women who subsequently developed gestational diabetes mellitus, when
compared to controls with uncomplicated pregcies. The current pilot study
found that itaconic acid may have potential as a novel biomarker in early
pregcy to predict the subsequent development of gestational diabetes
mellitus. However, the findings from this pilot study require validation with a
larger, diverse population before translation into the clinical setting. Salmonella typhimurium is a bacterial pathogen that poses a great threat to
humans and animals. In order to discover hosts' responses to S. typhimurium
infection, we collected and analyzed biofluids and organ tissues from mice which
had ingested S. typhimurium. We employed (1)H NMR spectroscopy coupled with
multivariate data analysis and immunological techniques. The results indicate
that infection leads to a severe impact on mice spleen and ileum, which are
characterized by splenomegaly and edematous villi, respectively. We found that
increased levels of itaconic acid were correlated with the presence of
splenomegaly during infection and may play an important role in
Salmonella-containing vacuole acidification. In addition, metabonomic analyses
of urine displayed the development of salmonellosis in mice, which is
characterized by dynamic changes in energy metabolism. Furthermore, we found
that the presence of S. typhimurium activated an anti-oxidative response in
infected mice. We also observed changes in the gut microbial co-metabolites
(hippurate, TMAO, TMA, methylamine). This investigation sheds much needed light
on the host-pathogen interactions of S. typhimurium, providing further
information to deepen our understanding of the long co-evolution process between
hosts and infective bacteria. |
Are chromomethylases present in animal genomes? | No. Multiple lines of experimental evidence suggest that chromomethylases (CMTs) have been hitherto identified in plant genomes(Arabidopsis, maize, tomato). CMTs maintain CpNpG (N = A, T, C, or G) methylation and they are unique to the plant kingdom. The lack of CMT homologs in animal genomes could be explained based on the fact that, in contrast to plants, animals maintain primarily CG methylation. Therefore, the presence of CMTs is not required in the animal genomes. | Chromodomains are thought to mediate protein-protein interactions between
chromatin components. We have detected a chromodomain embedded within the
catalytic region of a predicted Arabidopsis DNA methyltransferase that is
diverged from other eukaryotic enzymes. The 791 residue "chromomethylase" (CMT1)
is encoded by a floral transcript that is spliced from 20 exons and is present
at only approximately 1/10(-7) of total mRNA. Genomic sequencing reveals an
ancient haplotype split at CMT1 between Col-0 + Metz and the other ecotypes
examined. In the Col-0 + Metz haplotype, alternative mRNA processing at intron
13 truncates the coding region. In Ler, RLD, and No-0, similar truncation is
caused by insertion of an intact retrotransposon, Evelknievel, which is present
as a single copy in Ler and RLD and is currently methylated and inactive.
Evelknievel is found at this site on a single branch that connects the Ler, RLD,
and No-0 ecotypes but is absent from the genomes of all other ecotypes examined.
A stop codon within exon 6 of the Metz ecotype confirms that CMT1 is
nonessential. Nevertheless, comparison to CMT1 of Cardaminopsis arenosa, an
outcrossing relative, indicates conservation for DNA methyltransferase function.
We discuss how allelic diversity of CMT1 may reflect loosened selective
constraints in a self-fertilizing species such as Arabidopsis thaliana. Plants maintain cytosine methylation at CG and non-CG residues to control gene
expression and genome stability. In a screen for Arabidopsis mutants that alter
methylation and silencing of a densely methylated endogenous reporter gene, we
recovered 11 loss-of-function alleles in the CMT3 chromomethylase gene. The cmt3
mutants displayed enhanced expression and reduced methylation of the reporter,
particularly at non-CG cytosines. CNG methylation was also reduced at repetitive
centromeric sequences. Thus, CMT3 is a key determit for non-CG methylation.
The lack of CMT homologs in animal genomes could account for the observation
that in contrast to plants, animals maintain primarily CG methylation. A cytosine DNA methyltransferase containing a chromodomain, Zea
methyltransferase2 (Zmet2), was cloned from maize. The sequence of ZMET2 is
similar to that of the Arabidopsis chromomethylases CMT1 and CMT3, with
C-terminal motifs characteristic of eukaryotic and prokaryotic DNA
methyltransferases. We used a reverse genetics approach to determine the
function of the Zmet2 gene. Plants homozygous for a Mutator transposable element
insertion into motif IX had a 13% reduction in methylated cytosines. DNA gel
blot analysis of these plants with methylation-sensitive restriction enzymes and
bisulfite sequencing of a 180-bp knob sequence showed reduced methylation only
at CpNpG sites. No reductions in methylation were observed at CpG or asymmetric
sites in heterozygous or homozygous mutant plants. Our research shows that
chromomethylase Zmet2 is required for in vivo methylation of CpNpG sequences. Proper DNA methylation patterning requires the complementary processes of de
novo methylation (the initial methylation of unmethylated DNA sequences) and
maintece methylation (the faithful replication of preexisting methylation).
Arabidopsis has two types of methyltransferases with demonstrated maintece
activity: MET1, which maintains CpG methylation and is homologous to mammalian
DNMT1, and CHROMOMETHYLASE 3 (CMT3), which maintains CpNpG (N = A, T, C, or G)
methylation and is unique to the plant kingdom. Here we describe
loss-of-function mutations in the Arabidopsis DOMAINS REARRANGED METHYLASE (DRM)
genes and provide evidence that they encode de novo methyltransferases. drm1
drm2 double mutants retained preexisting CpG methylation at the endogenous FWA
locus but blocked de novo CpG methylation that is normally associated with FWA
transgene silencing. Furthermore, drm1 drm2 double mutants blocked de novo CpNpG
and asymmetric methylation and gene silencing of the endogenous SUPERMAN (SUP)
gene, which is normally triggered by an inverted SUP repeat. However, drm1 drm2
double mutants did not show reactivation of previously established SUPERMAN
epigenetic silenced alleles. Thus, drm mutants prevent the establishment but not
the maintece of gene silencing at FWA and SUP, suggesting that the DRMs
encode the major de novo methylation enzymes affecting these genes. By data mining in the sequence of the Corynebacterium glutamicum ATCC 13032
genome, six putative mycolyltransferase genes were identified that code for
proteins with similarity to the N-terminal domain of the mycolic acid
transferase PS1 of the related C. glutamicum strain ATCC 17965. The genes
identified were designated cop1, cmt1, cmt2, cmt3, cmt4, and cmt5 ( cmt from
corynebacterium mycolyl transferases). cop1 encodes a protein of 657 amino
acids, which is larger than the proteins encoded by the cmt genes with 365, 341,
483, 483, and 411 amino acids. Using bioinformatics tools, it was shown that all
six gene products are equipped with signal peptides and esterase domains.
Proteome analyses of the cell envelope of C. glutamicum ATCC 13032 resulted in
identification of the proteins Cop1, Cmt1, Cmt2, and Cmt4. All six
mycolyltransferase genes were used for mutational analysis. cmt4 could not be
mutated and is considered to be essential. cop1 was found to play an additional
role in cell shape formation. A triple mutant carrying mutations in cop1, cmt1,
and cmt2 aggregated when cultivated in MM1 liquid medium. This mutant was also
no longer able to synthesize trehalose di coryno mycolate (TDCM). Since single
and double mutants of the genes cop1, cmt1, and cmt2 could form TDCM, it is
concluded that the three genes, cop1, cmt1, and cmt2, are involved in TDCM
biosynthesis. The presence of the putative esterase domain makes it highly
possible that cop1, cmt1, and cmt2 encode enzymes synthesizing TDCM from
trehalose monocorynomycolate. Tomato fruit cells are characterized by a strong increase in nuclear ploidy
during fruit development. Average ploidy levels increased to similar levels
(above 50C) in two distinct fruit tissues, pericarp and locular tissue. However,
ploidy profiles differed significantly between these two tissues suggesting a
tissue-specific control of endoreduplication in tomato fruit. To determine
possible relationships between endoreduplication and epigenetic mechanisms, the
methylation status of genomic DNA from pericarp and locular tissue of tomato
fruit was analysed. Pericarp genomic DNA was characterized by an increase of CG
and/or CNG methylation at the 5S and 18S rDNA loci and at gyspsy-like
retrotransposon sequences during fruit growth. A sharp decrease of the global
DNA methylation level together with a reduction of methylation at the rDNA loci
was also observed in pericarp during fruit ripening. Inversely, no major
variation of DNA methylation either global or locus-specific, was observed in
locular tissue. Thus, tissue-specific variations of DNA methylation are unlikely
to be triggered by the induction of endoreduplication in fruit tissues, but may
reflect tissue-specific ploidy profiles. Expression analysis of eight putative
tomato DNA methyltransferases encoding genes showed that one chromomethylase
(CMT) and two rearranged methyltransferases (DRMs) are preferentially expressed
in the pericarp during fruit growth and could be involved in the locus-specific
increase of methylation observed at this developmental phase in the pericarp. During embryogenesis there is a major switch from dependence upon
maternally-deposited products to reliance on products of the zygotic genome. In
animals, this so-called maternal-to-zygotic transition occurs following a period
of transcriptional quiescence. Recently, we have shown that the early embryo in
Arabidopsis is also quiescent, a state inherited from the female gamete and
linked to specific patterns of H3K9 dimethylation and TERMINAL FLOWER2 (TFL2)
localization. We also demonstrated that CHROMOMETHYLASE 3 (CMT3) is required for
H3K9 dimethylation in the egg cell and for normal embryogenesis during the first
few divisions of the zygote. Subsequent analysis of CMT3 mutants points to a key
role in egg cell reprogramming by controlling silencing in both transposon and
euchromatic regions. A speculative model of the CMT3-induced egg cell silencing
is presented here, based on these results and current data from the literature
suggesting the potential involvement of small RNAs targeted to the egg cell, a
process conceptually similar to the division of labor described in the male
gametophyte for which we show that H3K9 modifications and TFL2 localization are
reminiscent of the female gametophyte. DNA methylation and histone modification exert epigenetic control over gene
expression. CHG methylation by CHROMOMETHYLASE3 (CMT3) depends on histone H3K9
dimethylation (H3K9me2), but the mechanism underlying this relationship is
poorly understood. Here, we report multiple lines of evidence that CMT3
interacts with H3K9me2-containing nucleosomes. CMT3 genome locations nearly
perfectly correlated with H3K9me2, and CMT3 stably associated with
H3K9me2-containing nucleosomes. Crystal structures of maize CMT3 homolog ZMET2,
in complex with H3K9me2 peptides, showed that ZMET2 binds H3K9me2 via both bromo
adjacent homology (BAH) and chromo domains. The structures reveal an aromatic
cage within both BAH and chromo domains as interaction interfaces that capture
H3K9me2. Mutations that abolish either interaction disrupt CMT3 binding to
nucleosomes and show a complete loss of CMT3 activity in vivo. Our study
establishes dual recognition of H3K9me2 marks by BAH and chromo domains and
reveals a distinct mechanism of interplay between DNA methylation and histone
modification. |
Which genes are associated with autosomal dominant Charcot-Marie-Tooth? | The genes associated with the X-linked and the autosomal dominant forms of Charcot-Marie-Tooth disease are GJB1, MPZ, INF2, DNM2, YARS, GNB4, NEFL, MFN2, LRSAM1, GDAP1, PMP22, LITAF, and EGR2. Identification of these genes has not only been important for patients and families, but also provided new information about disease pathogenesis. | Autosomal domit Charcot-Marie-Tooth type-1A neuropathy (CMT1A) is a
demyelinating peripheral nerve disorder that is commonly associated with a
submicroscopic tandem DNA duplication of a 1.5-Mb region of 17p11.2p12 that
contains the peripheral myelin gene PMP22. Clinical features of CMT1A include
progressive distal muscle atrophy and weakness, foot and hand deformities, gait
abnormalities, absent reflexes, and the completely penetrant electrophysiologic
phenotype of symmetric reductions in motor nerve conduction velocities (NCVs).
Molecular and fluorescense in situ hybridization (FISH) analyses were performed
to determine the duplication status of the PMP22 gene in four patients with rare
cytogenetic duplications of 17p. Neuropathologic features of CMT1A were seen in
two of these four patients, in addition to the complex phenotype asociated with
17p partial trisomy. Our findings show that the CMT1A phenotype of reduced NCV
is specifically associated with PMP22 gene duplications, thus providing further
support for the PMP22 gene dosage mechanism for CMT1A. Charcot-Marie-Tooth (CMT) disease is the most-common form of inherited motor and
sensory neuropathy. The autosomal domit axonal form of the disease (CMT2) is
currently subdivided into seven types based on genetic localization. These are
CMT2A (1p35-p36), CMT2B (3q13-q22), CMT2C (unknown), CMT2D (7p14), CMT2E (8p21),
HMNSP (3q13.1), and CMT2F (7q11-q21). Two loci have thus far been identified for
autosomal recessive CMT2; ARCMT2A (1q21.1-q21.3) and ARCMT2B (19q13.3).
Mutations in four genes (connexin 32, myelin protein zero, neurofilament-light,
and kinesin) have been associated with the CMT2 phenotype. We identified a novel
neurofilament-light missense mutation (C64T) that causes the disease in a large
Slovenian CMT2 family. This novel mutation shows complete co-segregation with
the domitly inherited CMT2 phenotype in our family. BACKGROUND: Charcot-Marie-Tooth (CMT) neuropathy is a heterogeneous group of
inherited disorders of the peripheral nervous system. The authors recently
mapped an autosomal domit demyelinating form of CMT type 1 (CMT1C) to
chromosome 16p13.1-p12.3.
OBJECTIVE: To find the gene mutations underlying CMT1C.
METHODS: The authors used a combination of standard positional cloning and
candidate gene approaches to identify the causal gene for CMT1C. Western blot
analysis was used to determine relative protein levels in patient and control
lymphocyte extracts. Northern blotting was used to characterize gene expression
in 1) multiple tissues; 2) developing sciatic nerve; and 3) nerve-crush and
nerve-transection experiments.
RESULTS: The authors identified missense mutations (G112S, T115N, W116G) in the
LITAFgene (lipopolysaccharide-induced tumor necrosis factor-alpha factor) in
three CMT1C pedigrees. LITAF, which is also referred to as SIMPLE, is a widely
expressed gene encoding a 161-amino acid protein that may play a role in protein
degradation pathways. The mutations associated with CMT1C were found to cluster,
defining a domain of the LITAF protein having a critical role in peripheral
nerve function. Western blot analysis suggested that the T115N and W116G
mutations do not alter the level of LITAF protein in peripheral blood
lymphocytes. The LITAF transcript is expressed in sciatic nerve, but its level
of expression is not altered during development or in response to nerve injury.
This finding is in stark contrast to that seen for other known genes that cause
CMT1.
CONCLUSIONS: Mutations in LITAF may account for a significant proportion of CMT1
patients with previously unknown molecular diagnosis and may define a new
mechanism of peripheral nerve perturbation leading to demyelinating neuropathy. Mutations in the ganglioside-induced differentiation-associated protein 1 gene
cause either autosomal recessive demyelinating Charcot-Marie-Tooth disease type
4A or autosomal recessive axonal Charcot-Marie-Tooth disease with vocal cord
paresis. We sequenced the ganglioside-induced differentiation-associated protein
1 gene in 138 patients from 119 unrelated families diagnosed with either
demyelinating or axonal autosomal recessive Charcot-Marie-Tooth disease. We
detected six distinct mutant alleles in four families, four of which are novel.
Electrophysiological studies show severely slowed motor nerve conduction
velocities with severely reduced compound muscle action potentials. However, one
patient had a normal conduction velocity in the ulnar nerve. Based on the
electrophysiological tests, patients with ganglioside-induced
differentiation-associated protein 1 mutations will therefore be classified as
either axonal or demyelinating Charcot-Marie-Tooth disease. The
neuropathological aspect shows a divergent pattern; nerve biopsies taken from
two siblings at the same age and sharing the same ganglioside-induced
differentiation-associated protein 1 gene mutation showed a dissimilar severity
stage. Charcot-Marie-Tooth disease with deafness is a clinically distinct entity and is
associated with mutations or deletions in several genes including PMP22 gene.
Here, we report a large family showing characteristic phenotypes of
Charcot-Marie-Tooth type 1A along with deafness in an autosomal domit
fashion. We detected a sequence variation (c.68C>G) co-segregating with the
disease phenotype and leading to a T23R missense mutation in PMP22. Charcot-Marie-Tooth (CMT) disease is a clinically and genetically heterogeneous
group of peripheral neuropathies. Different chromosomal loci have been linked
with three autosomal domit, 'intermediate' types of CMT: DI-CMTA, DI-CMTB and
DI-CMTC. We refined the locus associated with DI-CMTB on chromosome 19p12-13.2
to 4.2 Mb in three unrelated families with CMT originating from Australia,
Belgium and North America. After screening candidate genes, we identified unique
mutations in dynamin 2 (DNM2) in all families. DNM2 belongs to the family of
large GTPases and is part of the cellular fusion-fission apparatus. In
transiently transfected cell lines, mutations of DNM2 substantially diminish
binding of DNM2 to membranes by altering the conformation of the beta3/beta4
loop of the pleckstrin homology domain. Additionally, in the Australian and
Belgian pedigrees, which carry two different mutations affecting the same amino
acid, Lys558, CMT cosegregated with neutropenia, which has not previously been
associated with CMT neuropathies. The neurofilament light chain (NF-L) is a major constituent of intermediate
filaments and plays a pivotal function in the assembly and maintece of axonal
cytoskeleton. Mutations in the NF-L gene (NEFL) cause autosomal domit
neuropathies that are classified either as axonal Charcot-Marie-Tooth (CMT) type
2E (CMT2E) or demyelinating CMT type 1F (CMT1F). The pathophysiological bases of
the disorder(s) are elusive. We performed a mutational analysis of NEFL in a
series of 177 index cases with CMT and without mutations in the genes for
peripheral myelin protein zero (MPZ), peripheral myelin protein 22 (PMP22) and
connexin 32 (GJB1); the motor nerve conduction velocity (MNCV) at the median
nerve was below 38 m/s in 76 cases and above 38 m/s in 101. We identified five
new pedigrees with four mutations in the head and rod domains of NF-L, including
a novel Leu268Pro substitution and a novel del322Cys_326Asn deletion. Several
examined affected members exhibited marked variability in the severity of
disease and age at onset. Nerve conduction alterations were consistent with an
axonal neuropathy often associated with demyelinating features, such as
prolonged distal latencies (DL). Pathological examination of sural nerve
biopsies in the probands detected in four cases a chronic axonal neuropathy
dominated by focal accumulations of NF with axonal swellings (giant axons) and
significant secondary demyelination; in the fifth case no NFs accumulations were
evident but many myelinated fibres consisted exclusively of microtubules with
few or absent NF. The pathological phenotype correlated with the pattern of
nerve conduction alterations and indicated that NEFL mutations cause a profound
alteration of the cytoskeleton possibly related to defective targeting of NF. BACKGROUND: Recently, mutations affecting different domains of dynamin-2 (DNM2)
were associated alternatively with autosomal domit centronuclear myopathy or
domit intermediate (demyelinating and axonal) Charcot-Marie-Tooth disease
(CMT) type B.
OBJECTIVE: To assess the etiologic role of DNM2 in CMT.
METHODS: We performed a mutational screening of DNM2 exons 13 through 16
encoding the pleckstrin homology domain in a large series of CMT patients with a
broad range of nerve conduction velocities and without mutations in more common
genes.
RESULTS: We identified two novel DNM2 mutations that cosegregated with purely
axonal CMT in two pedigrees without clinical evidence of primary myopathy.
CONCLUSION: Patients with axonal Charcot-Marie-Tooth disease type 2 neuropathy
without mutations in more common genes should undergo investigation for DNM2
pleckstrin homology. A wide range of phenotypes have been reported in autosomal recessive (AR)
Charcot-Marie-Tooth disease (CMT) patients carrying mutations in the
ganglioside-induced differentiation-associated protein 1 (GDAP1) gene, such as
axonal, demyelinating, and intermediate forms of AR CMT. There have been very
few reports of GDAP1 mutations in autosomal domit (AD) CMT. Here, we report
an AD CMT family with a novel Q218E mutation in the GDAP1 gene. The mutation was
located within the well-conserved glutathione S-transferase (GST) core region
and co-segregated with the affected members in the pedigree. The affected AD CMT
individuals had a later disease onset and much milder phenotypes than the AR CMT
patients, and the histopathologic examination revealed both axonal degeneration
and demyelination. Charcot-Marie-Tooth disease (CMT) constitutes a large group of genetically
heterogeneous disorders of the peripheral nervous system. Autosomal recessive
forms of CMT are less common in the general population but account for the vast
majority of CMT phenotypes in communities with a high prevalence of
consanguinity. At least 10 genetic loci cause autosomal recessive forms of CMT.
Mutations in the ganglioside-induced differentiation-associated protein 1
(GDAP1) gene are among the most frequent genetic causes of autosomal recessive
forms of CMT. To date, 28 mutations in GDAP1 gene have been linked with the
disease. Here, we report a novel GDAP1 mutation in an Old Order Amish family
with CMT. To ascertain the Amish CMT locus, we performed a genome-wide single
nucleotide polymorphism (SNP) analysis on one of three patients from a
consanguineous pedigree. Assuming mutation homogeneity, the analysis sought
large homozygous SNP blocks that also contained known CMT loci. The largest
homozygous SNP block in the patient was localized to chromosome 8q13.1-21.3 and
contained the GDAP1 gene. Sequence analysis revealed a novel homozygous
mutation, c.692C>T, at codon 231 (p.P231L) in exon 5 of GDAP1 in all patients.
Neither the unaffected individuals in the family nor the healthy control samples
were homozygous for this mutation. Our findings suggested that this novel
mutation in GDAP1 gene is associated with an autosomal recessive form of CMT in
Ohio Old Order Amish community. Mutations in the Dynamin 2 gene (DNM2) cause autosomal domit centronuclear
myopathy or autosomal domit (AD) Charcot-Marie-Tooth (CMT) disease. Here the
authors report one large Czech family with 15 members affected with an AD CMT
phenotype of extraordinary variability. Genetic linkage analysis using SNP
arrays revealed a locus of about 9.6 Mb on chromosome 19p13.1-13.2. In this
critical interval, 373 genes were located. The only gene herein known to be
associated with an intermediate type of CMT was Dynamin 2 (DNM2). Subsequent
sequence analysis of the DNM2 gene in the index patient revealed a novel
missense mutation p.Met580Thr. This missense mutation segregated with the
neuropathy, indicating the causal character of this mutation. The phenotype of
CMT in this family shows mild to moderate impairment with relatively preserved
upper limbs and a very broad range of the onset of clinical symptoms from an
early onset around the age of 12 to the late onset during the fifth decade.
Electrophysiology showed an intermediate type of peripheral neuropathy. The
motor median nerve conduction velocity varied from 36 m/s to normal values with
signs of asymmetrical affection of peripheral nerves. No additional symptoms
such as cranial nerve involvement, cataract, and signs of neutropenia or
myopathy syndrome were observed in any member of the family yet. The progression
was slow with no loss of ambulation. The authors suggest that the
characterization of clinical variability in a single family may help to direct
the genetic analysis directly to the rarely observed DNM2 mutations. The large GTPase dynamin 2 is a key player in membrane and cytoskeletal dynamics
mutated in centronuclear myopathy (CNM) and Charcot-Marie Tooth (CMT)
neuropathy, two discrete domit neuromuscular disorders affecting skeletal
muscle and peripheral nerves respectively. The molecular basis for the
tissue-specific phenotypes observed and the physiopathological mechanisms linked
to dynamin 2 mutations are not well established. In this study, we have analyzed
the impact of CNM and CMT implicated dynamin 2 mutants using ectopic expression
of four CNM and two CMT mutations, and patient fibroblasts harboring two dynamin
2 CNM mutations in established cellular processes of dynamin 2 action. Wild type
and CMT mutants were seen in association with microtubules whereas CNM mutants
lacked microtubules association and did not disrupt interphase microtubules
dynamics. Most dynamin 2 mutants partially decreased clathrin-mediated
endocytosis when ectopically expressed in cultured cells; however, experiments
in patient fibroblasts suggested that endocytosis is overall not defective.
Furthermore, CNM mutants were seen in association with enlarged clathrin stained
structures whereas the CMT mutant constructs were associated with clathrin
structures that appeared clustered, similar to the structures observed in Dnm1
and Dnm2 double knock-out cells. Other roles of dynamin 2 including its
interaction with BIN1 (amphiphysin 2), and its function in Golgi maintece and
centrosome cohesion were not significantly altered. Taken together, these mild
functional defects are suggestive of differences between CMT and CNM
disease-causing dynamin 2 mutants and suggest that a slight impairment in
clathrin-mediated pathways may accumulate over time to foster the respective
human diseases. Mutations in dynamin 2 (DNM2) lead to domit intermediate Charcot-Marie-Tooth
neuropathy type B, while a different set of DNM2 mutations cause autosomal
domit centronuclear myopathy. In this study, we aimed to elucidate the
disease mechanisms in domit intermediate Charcot-Marie-Tooth neuropathy type
B and to find explanations for the tissue-specific defects that are associated
with different DNM2 mutations in domit intermediate Charcot-Marie-Tooth
neuropathy type B versus autosomal domit centronuclear myopathy. We used
tissue derived from Dnm2-deficient mice to establish an appropriate peripheral
nerve model and found that domit intermediate Charcot-Marie-Tooth neuropathy
type B-associated dynamin 2 mutants, but not autosomal domit centronuclear
myopathy mutants, impaired myelination. In contrast to autosomal domit
centronuclear myopathy mutants, Schwann cells and neurons from the peripheral
nervous system expressing domit intermediate Charcot-Marie-Tooth neuropathy
mutants showed defects in clathrin-mediated endocytosis. We demonstrate that, as
a consequence, protein surface levels are altered in Schwann cells. Furthermore,
we discovered that myelination is strictly dependent on Dnm2 and
clathrin-mediated endocytosis function. Thus, we propose that altered
endocytosis is a major contributing factor to the disease mechanisms in domit
intermediate Charcot-Marie-Tooth neuropathy type B. Charcot-Marie-Tooth (CMT) disease is a common neurogenetic disorder and its
heterogeneity is a challenge for genetic diagnostics. The genetic diagnostic
procedures for a CMT patient can be explored according to the
electrophysiological criteria: very slow motor nerve conduction velocity (MNCV)
(<15 m/s), slow MNCV (15-25 m/s), intermediate MNCV (25-45 m/s), and normal MNCV
(>45 m/s). Based on the inheritance pattern, intermediate CMT can be divided
into domit (DI-CMT) and recessive types (RI-CMT). GJB1 is currently
considered to be associated with X-linked DI-CMT, and MPZ, INF2, DNM2, YARS,
GNB4, NEFL, and MFN2 are associated with autosomal DI-CMT. Moreover, GDAP1,
KARS, and PLEKHG5 are associated with RI-CMT. Identification of these genes is
not only important for patients and families but also provides new information
about pathogenesis. It is hoped that this review will lead to a better
understanding of intermediate CMT and provide a detailed diagnostic procedure
for intermediate CMT. Charcot-Marie-Tooth (CMT) disease caused by mutations in the GDAP1 gene has been
shown to be inherited via traits that may be either autosomal recessive (in the
majority of cases) [CMT4A] or autosomal domit [CMT2K]. CMT4A disease is
characterized by an early onset, and a severe clinical course often leading to a
loss of ambulation, whereas CMT2K is characterized by a mild clinical course of
benign axonal neuropathy beginning even in the 6th decade of life. Clinical data
from a GDAP1 mutated patient suggests that the presence of a particular mutation
is associated with a certain trait of inheritance. The association of a
particular GDAP1 gene mutation and a domit or recessive trait of inheritance
is of special importance for genetic counseling and the prenatal diagnostics as
regards severe forms of CMT. In the present study we report on two CMT families
in which a newly identified Glu222Lys mutation within the GDAP1 gene segregates
both in autosomal domit and recessive traits. Our study shows that at least
some GDAP1 gene mutations may segregate with the CMT phenotype as both domit
and recessive traits. Thus, genetic counseling for CMT4A/CMT2K families requires
more extensive data on GDAP1 phenotype-genotype correlations. |
Which transcription factors (TFs) participate in the formation of the interferon-beta (IFN-b) enhanceosome? | Transcriptional activation of the IFN beta gene in response to virus infection requires the assembly of an enhanceosome, consisting of the transcriptional activators NF-kappa B, IRF1, ATF2/c-Jun, and the architectural protein HMG I(Y). Transcriptional activation of the human interferon-beta (IFN-beta) gene by virus infection requires the assembly of a higher order nucleoprotein complex, the enhanceosome, which consists of the transcriptional activators NF-kappa B (p50/p65), ATF-2/c-jun, IRF-3 and IRF-7, architectural protein HMGI(Y), and the coactivators p300 and CBP. | We present evidence that transcriptional activation of the human interferon-beta
(IFN beta) gene requires the assembly of a higher order transcription enhancer
complex (enhanceosome). This multicomponent complex includes at least three
distinct transcription factors and the high mobility group protein HMG I(Y).
Both the in vitro assembly and in vivo transcriptional activity of this complex
require a precise helical relationship between individual transcription
factor-binding sites. In addition, HMG I(Y), which binds specifically to three
sites within the enhancer, promotes cooperative binding of transcriptional
factors in vitro and is required for transcriptional synergy between these
factors in vivo. Thus, HMG I(Y) plays an essential role in the assembly and
function of the IFN beta gene enhanceosome. The transcriptional activity of an in vitro assembled human interferon-beta gene
enhanceosome is highly synergistic. This synergy requires five distinct
transcriptional activator proteins (ATF2/c-JUN, interferon regulatory factor 1,
and p50/p65 of NF-kappaB), the high mobility group protein HMG I(Y), and the
correct alignment of protein-binding sites on the face of the DNA double helix.
Here, we investigate the mechanisms of enhanceosome-dependent transcriptional
synergy during preinitiation complex assembly in vitro. We show that the
stereospecific assembly of the enhanceosome is critical for the efficient
recruitment of TFIIB into a template-committed TFIID-TFIIA-USA (upstream
stimulatory activity complex) and for the subsequent recruitment of the RNA
polymerase II holoenzyme complex. In addition, we provide evidence that
recruitment of the holoenzyme by the enhanceosome is due, at least in part, to
interactions between the enhanceosome and the transcriptional coactivator CREB,
cAMP responsive element binding protein (CBP). These studies reveal a unique
role of enhanceosomes in the cooperative assembly of the transcription machinery
on the human interferon-beta promoter. Transcriptional activation of the human interferon-beta (IFN-beta) gene by virus
infection requires the assembly of a higher order nucleoprotein complex, the
enhanceosome, which consists of the transcriptional activators NF-kappa B
(p50/p65), ATF-2/c-jun, IRF-3 and IRF-7, architectural protein HMGI(Y), and the
coactivators p300 and CBP. In this report, we show that virus infection of cells
results in a dramatic hyperacetylation of histones H3 and H4 that is localized
to the IFN-beta promoter. Furthermore, expressing a truncated version of IRF-3,
which lacks a p300/CBP interaction domain, suppresses both histone
hyperacetylation and activation of the IFN-beta gene. Thus, coactivator-mediated
localized hyperacetylation of histones may play a crucial role in inducible gene
expression. Transcriptional activation of the virus inducible enhancer of the human
interferon-beta (IFN-beta) gene in response to virus infection requires the
assembly of an enhanceosome, consisting of the transcriptional activators
NF-kappaB, ATF-2/c-Jun, IRFs and the architectural protein of the mammalian high
mobility group I(Y) [HMG I(Y)]. Here, we demonstrate that the first step in
enhanceosome assembly, i.e. HMG I(Y)-dependent recruitment of NF-kappaB and
ATF-2/c-Jun to the enhancer, is facilitated by discrete regions of HMG I and is
mediated by allosteric changes induced in the DNA by HMG I(Y) and not by
protein-protein interactions between HMG I(Y) and these proteins. However, we
show that completion of the enhanceosome assembly process requires
protein-protein interactions between HMG I(Y) and the activators. Finally, we
demonstrate that once assembled, the IFN-beta enhanceosome is an unusually
stable nucleoprotein structure that can activate transcription at high levels by
promoting multiple rounds of reinitiation of transcription. Small molecules that modulate specific protein functions are valuable tools for
dissecting complex signaling pathways. Here, we identified a small molecule that
induces the assembly of the interferon-beta (IFN-beta) enhanceosome by
stimulating all the enhancer-binding activator proteins: ATF2/c-JUN, IRF3, and
p50/p65 of NF-kappaB. This compound stimulates mitogen-activated protein kinase
kinase kinase 1 (MEKK1), which is a member of a family of proteins involved in
stress-mediated signaling pathways. Consistent with this, MEKK1 activates IRF3
in addition to ATF2/c-JUN and NF-kappaB for the assembly of the IFN-beta
enhanceosome. MEKK1 activates IRF3 through the c-JUN amino-terminal kinase (JNK)
pathway but not the p38 and IkappaB kinase (IKK) pathway. Taken together with
previous observations, these results implicate that, for the assembly of an
IFN-beta enhanceosome, MEKK1 can induce IRF3 and ATF2/c-JUN through the JNK
pathway, whereas it can induce NF-kappaB through the IKK pathway. Thus, specific
MEKK family proteins may be able to integrate some of multiple signal
transduction pathways leading to the specific activation of the IFN-beta
enhanceosome. Transcriptional activation of the interferon-beta (IFN-beta) gene requires
assembly of an enhanceosome containing the transcription factors ATF-2/c-Jun,
IRF-3/IRF-7, NF-kappaB and HMGI(Y). These factors cooperatively bind a composite
DNA site and activate expression of the IFN-beta gene. The 3.0 A crystal
structure of the DNA-binding domains of ATF-2/c-Jun and two IRF-3 molecules in a
complex with 31 base pairs (bp) of the PRDIV-PRDIII region of the IFN-beta
enhancer shows that association of the four proteins with DNA creates a
continuous surface for the recognition of 24 bp. The structure, together with in
vitro binding studies and protein mutagenesis, shows that protein-protein
interactions are not critical for cooperative binding. Instead, cooperativity
arises mainly through nucleotide sequence-dependent structural changes in the
DNA that allow formation of complementary DNA conformations. Because the binding
sites overlap on the enhancer, the unit of recognition is the entire nucleotide
sequence, not the individual subsites. We have investigated beta interferon (IFN-beta) and IFN-alpha4 gene expression
and activation of related transcription factors in mouse cytomegalovirus
(MCMV)-infected fibroblasts. mRNA analysis demonstrated an initial phase of IFN
gene induction upon MCMV infection, which was followed by a sustained
MCMV-mediated simultaneous downregulation of IFN-beta and IFN-alpha4 gene
expression. The induction of IFN transcription resulted from the activation of
the components of the IFN-beta enhanceosome, i.e. IFN regulatory factor (IRF) 3,
nuclear factor (NF)-kappaB, activating transcription factor (ATF)-2 and c-Jun.
Activation of the transcription factors occurred rapidly and in a sequential
order upon infection, but only lasted a while. As a consequence, IFN-alpha/beta
gene expression became undetectable 6 h post-infection and throughout the MCMV
replication cycle. This effect is based on an active interference since
restimulation of IFN gene induction by further external stimuli (e.g. Sendai
virus infection) was completely abolished. This inhibition required MCMV gene
expression and was not observed in cells infected with UV-inactivated MCMV
virions. The efficiency of inhibition is achieved by a concerted blockade of
IkappaBalpha degradation and a lack of nuclear accumulation of IRF3 and
ATF-2/c-Jun. Using an MCMV mutant lacking pM27, a signal transducer and
activator of transcription (STAT) 2-specific inhibitor of Jak/STAT signalling,
we found that the initial phase of IFN induction and the subsequent inhibition
does not depend on the positive-IFN feedback loop. Our findings indicate that
the MCMV-mediated downregulation of IFN transcription in fibroblasts relies on a
large arsenal of inhibitory mechanisms targeting each pathway that contributes
to the multiprotein enhanceosome complex. The dimer formed by the ATF-2 and c-Jun transcription factors is one of the main
components of the human interferon-beta enhanceosome. Although these two
transcription factors are able to form two homodimers and one heterodimer, it is
mainly the heterodimer that participates in the formation of this enhanceosome,
binding specifically to the positive regulatory domain IV (PRDIV) site of the
enhancer DNA. To understand this surprising advantage of the heterodimer, we
investigated the association of these transcription factors using fragments
containing the basic DNA-recognition segment and the basic leucine zipper domain
(bZIP). It was found that the probability of forming the hetero-bZIP
significantly exceeds the probability of forming homo-bZIPs, and that the
hetero-bZIP interacts more strongly with the PRDIV site of the interferon-beta
enhancer, especially in the orientation that places the folded ATF-2 basic
segment in the upstream half of this asymmetric site. The effect of salt on the
formation of the ATF-2/c-Jun dimer and on its ability to bind the target PRDIV
site showed that electrostatic interactions between the charged groups of these
proteins and with DNA play an essential role in the formation of the asymmetric
ATF-2/c-Jun/PRDIV complex. |
Is low T3 syndrome related with high BNP in cardiac patients? | BNP and fT3 are independently associated in severely compromised HF patients.
NT-pro-BNP was significantly associated with low-T3 syndrome in cardiac patients.
Higher NT-pro BNP concentrations are related to lower total T3 concentrations in cardiac patients | This study was designed to examine the involvement of thyroid hormone in the
release of brain natriuretic peptide (BNP) from the heart. We measured plasma
immunoreactive BNP (ir-BNP) concentrations in patients with untreated
hyperthyroidism. We also measured BNP values in experimental rats with
hyperthyroidism induced by thyroxine (T4) and in rats with hypothyroidism
induced by propylthiouracil (PTU). The in vitro effects of triiodothyronine (T3)
and T4 on the release of BNP were examined in newborn rat atrial and ventricular
myocytes in primary culture. Plasma BNP levels were increased in hyperthyroid
patients compared with normal control subjects. Plasma BNP levels were increased
in hyperthyroid rats and decreased in hypothyroid rats compared with euthyroid
rats. Plasma BNP level was correlated with serum T4 level in hyperthyroid
patients and hyperthyroid rats. A major component of ir-BNP in plasma from
hyperthyroid patients was human BNP-32 and that in plasma from hyperthyroid rats
was rat BNP-45. T4 and T3 stimulated release of ir-BNP from both cultured atrial
and ventricular myocytes in a dose-dependent manner. Plasma BNP concentration is
frequently increased in hyperthyroidism, and thyroid hormone may regulate BNP
release from both atrial and ventricular myocytes. Pericardial effusion has recently been reported as a complication of anorexia
nervosa. A distinct pathophysiological cause of it could not be revealed. In
some reports, there was a probable correlation between weight gain and reduction
of pericardial effusion in anorexia nervosa cases. We encountered a case in
which pericardial effusion remitted completely along with body weight increase
and normalization of low T3 syndrome. These findings suggest that the reduction
of pericardial effusion may correlate with both weight gain and low T3
normalization. Plasma brain natriuretic peptide (BNP) levels were increased in
this case despite heart failure, and plasma BNP decreased as pericardial
effusion remitted. The measurement of serum BNP level may be a clinical
parameter in such a case of pericardial effusion. BACKGROUND: Increased rates of depression are reported in coronary artery
disease (CAD). In heart disease, depression increases disability, reduces
quality of life, and increases mortality.
HYPOTHESIS: The study was undertaken to examine the relationship between
depression and thyroid axis function in patients with CAD.
METHODS: In all, 73 patients with CAD, consecutively admitted to a cardiac
rehabilitation hospital, were assessed for depression using the Hospital Anxiety
and Depression scale (HADS). Blood was drawn for assessment of thyroid axis
hormones and the N-amino terminal fragment of the pro-B-type natriuretic peptide
(NT-pro BNP).
RESULTS: The patients with CAD with depressive symptoms had a higher prevalence
of cardiac failure (p = 0.04), higher NT-pro BNP concentrations (p = 0.02), and
lower free triiodothyronine (T3) concentrations (p = 0.04) than patients with
CAD but without depressive symptoms. They also showed a strong trend (p = 0.058)
toward a higher incidence of the low T3 syndrome. Higher NT-pro BNP
concentrations were related to lower total T3 concentrations (r = -0.294, p =
0.011) and to higher reverse T3 concentrations (r = 0.353, p = 0.002). In men,
higher scores of depression were related to lower total T3 concentration (r =
-0.289, p = 0.034) and to higher NT-pro BNP concentration (r = 0.380, p =
0.005).
CONCLUSION: These findings suggest that symptoms of depression in patients with
CAD are associated with changes in thyroid axis function and with cardiac
impairment, especially in men. BACKGROUND: Although an altered thyroid metabolism has been documented in
patients with overt heart failure, no evaluation has been made of a
heart-thyroid interaction in mildly symptomatic patients with idiopathic left
ventricular dysfunction (ILVD). We wanted to assess the thyroid state in
patients with ILVD.
METHODS AND RESULTS: Eighty-six patients (age 60 +/- 10 years) were enrolled
into the study. Thyroxine (T4), triiodothyronine (T3), thyrotropin, brain and
atrial natriuretic peptides (BNP, ANP), noradrenaline, aldosterone, renin
activity, and interleukin-6 were measured. Patients were divided into three
groups: Group N with LV ejection fraction (EF) > or = 50% (n = 28), Group I with
LVEF > 35%-< 50% (n = 34), Group II with LVEF < or = 35% (n = 24). There was a
significant correlation between T3 and LVEF (r = 0.25, P = .02) and a negative
correlation between T3 and BNP (r = -0.37, P < .0001). At univariate analysis T3
was a predictor of LV dysfunction, whereas BNP was the most important predictor
at multivariate analysis (P = .002). T3 was the only predictor of New York Heart
Association class at multivariate analysis.
CONCLUSION: An altered thyroid profile characterized by a reduction in
peripheral production of biologically active T3 is related to LV dysfunction and
early symptoms of heart failure in patients with ILVD. OBJECTIVES: A low T3 syndrome was described in patients with heart failure (HF),
and it appears to be associated with adverse outcome, representing an
independent predictor of mortality. However, it is not known if low T3 levels
contribute to the pathophysiology of HF. On the other hand, it has been seen
that an elevation of brain natriuretic peptides (BNP and NT-proBNP) may
represent a warning signal for future cardiovascular disease and may be an early
marker of diastolic dysfunction. Therefore we tested the hypothesis that low
levels of free-triiodothyronine (FT3) are sufficient to determine an increased
concentration of the amino-terminal fragment of pro-brain natriuretic peptide
(NT-proBNP), as the result of an initial and asymptomatic cardiac impairment.
METHODS: A total of 52 consecutive non-cardiac patients underwent thyroid
function profile evaluation and NT-proBNP determination. On the basis of FT3
values they were divided in two subgroups: a low T3 group (19 patients) and a
normal T3 group (33 patients).
RESULTS: The median NT-proBNP concentration of patients with low T3 syndrome was
significantly higher than in those with normal FT3 (370 vs. 120 pg/ml, P =
0.002). There is a strong and inverse correlation between FT3 and Log NT-proBNP
(R = -0.47, P < 0.001); this relation persists in a multivariable regression
analysis, after adjustment for other potentially confounding variables (P =
0.008).
CONCLUSION: In absence of overt cardiovascular disease, patients with low T3
syndrome present an increased concentration of NT-proBNP. These data suggest
that low FT3 levels may be a contributing factor for the development of cardiac
dysfunction. BACKGROUND: Low triiodothyronine (T3) has been associated with increased
short-term mortality in intensive care unit patients and long-term mortality in
patients with heart disease. The objective of this study was to investigate
possible associations of thyroid hormone status with clinical outcome in
patients admitted for acute stroke.
MATERIALS AND METHODS: A total of 737 consecutive patients with acute first ever
stroke who presented within 24 h from symptoms' onset were studied. Total T3,
thyroxin (T4) and thyroid-stimulating hormone (TSH) levels were assessed in the
morning following admission. Cases with T3 values < or = 78 ng dL(-1) (1.2 nmol
L(-1)) (median) were characterized as 'low T3'. Cases with T4 values < or = 4.66
microg dL(-1) (60 nmol L(-1)) were characterized as 'low T4'. Basic and clinical
characteristics, stroke risk factors, and brain imaging were evaluated.
Neurological impairment was assessed using the Scandinavian Stroke Scale.
RESULTS: Four hundred and seventeen (56%) patients had T3 values < or = 78 ng
dL(-1) and 320 had normal T3 values. The 1-year mortality was 27.34% for low T3
and 19.37% for normal T3 cases (P = 0.006). A smaller percentage of patients
with low T3 values were independent at 1 year compared to those with normal T3
values [54.2% vs. 68.7%, chi(2) = 12.09, P < 0.001, odds ratio (OR) = 0.53, 95%
confidence interval (CI) 0.37-0.76]. Cox regression analysis revealed that
increased age, haemorrhagic stroke, low Scandinavian Stroke Scale score,
increased glucose and low T3 values (hazards ratio 0.69, CI = 0.48-0.98, P =
0.041) were significant predictors of 1-year mortality.
CONCLUSIONS: A high proportion of patients with acute stroke were found soon
after the event with low T3 values. The low-T3 syndrome is an independent
predictor of early and late survival in patients with acute stroke, and predicts
handicap at 1 year. BACKGROUND: The effects of subclinical thyroid dysfunction on cardiac outcome
are not well defined.
METHODS: To assess the relationship between mild thyroid dysfunction and the
incidence of death in cardiac patients, we evaluated 3121 cardiac patients.
Cardiac and overall deaths were considered. Four groups were defined:
euthyroidism, subclinical hypothyroidism (SCH), subclinical hyperthyroidism
(SCT), and low triiodothyronine syndrome (low T3).
RESULTS: After mean follow-up of 32 months, there were 65 and 140 cardiac and
overall deaths (3.4% and 7.3%), respectively, in euthyroidism, 15 and 27 (7.2%
and 13.0%) in SCH, 8 and 9 (8.2% and 9.2%) in SCT, and 59 and 119 (6.5% and
13.1%) in low T3. Survival rates for cardiac death were lower in SCH, SCT, and
low T3 than in euthyroidism (log-rank test; chi2 = 19.46; P < .001). Survival
rates for overall death were lower in SCH and low T3 than in euthyroidism
(log-rank test; chi2 = 26.67; P < .001). After adjustment for several risk
factors, hazard ratios (HRs) for cardiac death were higher in SCH (HR, 2.40; 95%
confidence interval [CI], 1.36-4.21; P = .02), SCT (HR, 2.32; 95% CI, 1.11-4.85;
P = .02), and low T(3) (HR, 1.63; 95% CI, 1.14-2.33; P = .007) than in
euthyroidism; HRs for overall death were higher in SCH (HR, 2.01; 95% CI,
1.33-3.04; P < .001) and low T3 (HR, 1.57; 95% CI, 1.22-2.01; P < .001) but not
in SCT.
CONCLUSION: A mildly altered thyroid status is associated with an increased risk
of mortality in patients with cardiac disease. OBJECTIVE: Cardiac secretion of brain natriuretic peptide (BNP) increases with
the progression of congestive heart failure (CHF). The plasma measurement of BNP
emerged recently as a useful, cost-effective biomarker for the diagnosis and
prognosis of CHF.
METHODS: BNP assay is useful for evaluating patients with acute dyspnea, because
a low level can help rule out CHF in primary care settings and reduce the demand
for echocardiography. Equally, BNP level can be particularly useful in
recognizing heart failure in a patient with acute dyspnea and a history of
chronic obstructive pulmonary disease.
RESULTS: However, although the clinical use of BNP as a biomarker in CHF is
increasing, the specificity of BNP in CHF is not strong, suggesting that other
mechanisms beyond simple ventricular stretch stimulate BNP release. Multiple
disorders in the intensive care unit, apart from CHF, cause elevated BNP levels,
including cardiovascular disease states such as ischemia, arrhythmias, cardiac
hypertrophy, and coronary endothelial dysfunction, as well as disorders of no
cardiac origin, such as sepsis, septic shock, and acute respiratory distress
syndrome. Moreover, the impact of increased BNP in patients with sepsis is not
clear. The relationship between BNP and both left ventricular ejection fraction
and left-sided filling pressures is weak, and data on the prognostic impact of
high BNP levels in patients with sepsis are conflicting.
CONCLUSION: Nevertheless, this review highlights the potential benefits of BNP
in the recognition and management of heart failure, and defines the gray zones
of BNP levels; it also identifies conditions influencing BNP levels in relation
to a certain heart failure and describes conditions of no cardiac origin with
increased BNP. BACKGROUND: The value of routine aminoterminal pro type B natriuretic peptide
(NT-proBNP) measurements in outpatient clinics remains unknown.
OBJECTIVES: We sought to determine the accuracy with which heart failure (HF)
specialists can predict NT-proBNP levels in HF outpatients based on clinical
assessment.
METHODS: We prospectively studied 160 consecutive HF patients followed in an
outpatient multidisciplinary HF clinic. During a regular office visit, HF
specialists were asked to estimate a patient's current NT-proBNP level based
upon their clinical assessment and all available information from their chart,
including a previous NT-proBNP level (if available). NT-proBNP estimations were
grouped into prognostic categories (<125, 125-1000, 1000-4998, or >/=4999 pg/mL)
and comparisons made between actual and estimate values.
RESULTS: Overall, HF specialists estimated 67.5% of NT-proBNP levels correctly.
After adjusting for clinical characteristics, knowledge of a prior NT-proBNP
measurement was the only significant predictor of estimation accuracy (p=0.01).
Compared to patients with a prior NT-proBNP level <125 pg/mL, physicians were
95% less likely to get a correct estimation in patients with the highest prior
NT-proBNP level (>/=4999 pg/mL).
CONCLUSION: HF specialists are reasonably accurate at estimating current
NT-proBNP levels based upon clinical assessment and a previous NT-proBNP level,
if those levels were < 4999 pg/mL. Likely, initial but not routine NT-proBNP
measurements are useful in outpatient HF clinics. BACKGROUND: Both low free triiodothyronine (fT3) and high brain natriuretic
peptide (BNP) have been separately described as prognostic predictors for
mortality in heart failure (HF). We investigated whether their prognostic value
is independent.
METHODS AND RESULTS: From January of 2001 to December of 2006, we prospectively
evaluated 442 consecutive patients with systolic HF and no thyroid disease or
treatment with drugs affecting thyroid function (age 65+/-12 years, mean +/-
standard deviation, 75% were male, left ventricular ejection fraction 33% +/-
10%, New York Heart Association (NYHA) class I and II: 63%, NYHA class III and
IV: 37%). All patients underwent full clinical and echocardiographic evaluation
and assessment of BNP and thyroid function. Both cardiac and all-cause mortality
(cumulative) were considered as end points. During a median 36-month follow-up
(range 1-86 months), 110 patients (24.8%) died, 64 (14.4%) of cardiac causes.
Univariate Cox model predictors of all-cause mortality and cardiac death were
age, body mass index, creatinine, hemoglobin, ejection fraction, NYHA class,
BNP, fT3, and thyroxine level. Multivariate analysis selected age, NYHA class,
hemoglobin, BNP, and fT3 as independent predictors for all-cause mortality and
NYHA class, BNP, and fT3 as independent predictors for cardiac mortality.
Patients with low fT3 and higher BNP showed the highest risk of all-cause and
cardiac death (odds ratio 11.6, confidence interval, 5.8-22.9; odds ratio 13.8,
confidence interval, 5.4-35.2, respectively, compared with patients with normal
fT3 and low BNP).
CONCLUSION: fT3 and BNP hold an independent and additive prognostic value in HF. OBJECTIVE: This study aimed to investigate thyroid hormone (TH) status and its
relationship with myocardial function as well as clinical and biochemical
parameters in stress cardiomyopathy (CMP).
METHODS: Forty-five patients with stress CMP (the patient group), 31 patients
without stress CMP (the control II group), and 58 healthy subjects (the control
I group) were included. Sick euthyroid syndrome (SES) was defined as low total
triiodothyronine (T(3)) with normal TSH levels.
RESULTS: In the patient group at admission, prevalence of SES was 62.2%.
Compared with the control I group, the patient group had a decrease in left
ventricular ejection fraction (LVEF) and systolic blood pressure (BP) and an
increase in troponin-I, CK-MB, and B-type natriuretic peptide (BNP) levels.
Total T(3) levels were reduced, and anti-thyroid peroxidase antibody (anti-TPO
Ab) positivity, C-reactive protein (CRP) and cortisol levels were elevated.
Total T(3) levels were associated with acute physiology and chronic health
evaluation II (APACHE II) score, LVEF, systolic BP, and cortisol levels in
multivariate analysis. In the control II group, total T(3) levels were not
associated with any variables. In the SES (n=28) and myocardial dysfunction
(MDys, n=27) subgroups, increased APACHE II score and BNP levels as well as
decreased LVEF and systolic BP were significant. Total T(3) levels were reduced,
and CRP, cortisol and catecholamines levels were elevated. In the MDys subgroup,
anti-TPO Ab positivity and titer were increased.
CONCLUSION: These results suggest that total T(3) levels may be associated with
myocardial contractility, clinical severity, and cortisol levels. Thyroid
autoimmunity may influence myocardial contractility in stress CMP. OBJECTIVES: Low-T3 syndrome is highly prevalent and independently prognostic in
cardiovascular patients. The relationship and prognostic impact with the cardiac
marker NT-pro-BNP have not been thoroughly investigated.
METHODS: Thyroid hormone levels and NT-pro-BNP were assessed in 615 consecutive
patients hospitalized for cardiovascular disease. Patients with primary overt or
latent thyroid disorder, hormone replacement, thyreostatic and amiodarone
therapy were excluded. The association with and predictive impact on mortality
were examined.
RESULTS: 36 (7.1%) patients had low-T3 syndrome. After adjustment for known
confounders, NT-pro-BNP was significantly associated with fT3 and low-T3
syndrome. fT3 (HR 0.58, 95%CI 0.34-0.98) and low-T3 syndrome (HR 3.0, 95%CI
1.4-6.3) were predictive for mortality after adjustment for NT-pro-BNP levels
and other cardiovascular prognostic variables. In patients with fT3 levels
within the normal range, fT3 and NT-pro-BNP stratified by median values showed
complementary prognostic information with the highest risk for mortality in
patients with low normal fT3 and high NT-pro-BNP (HR 10.5, 95%CI 3.2-34.6).
CONCLUSIONS: fT3 and low-T3 syndrome are significantly related to NT-pro-BNP in
patients with cardiovascular disease, but are predictors of mortality
independently of NT-pro-BNP and other known cardiovascular risk parameters. BACKGROUND: B-type natriuretic peptide (BNP) concentrations are high in
cirrhosis, possibly related to volume status and cirrhotic cardiomyopathy. The
prognostic significance of BNP in cirrhosis is unknown.
AIMS: We aimed to evaluate (i) the influence of haemodynamic parameters and
volaemia, assessed by impedance cardiography (ICG), in BNP levels, (ii) the
performance of BNP as a prognostic marker, in a cohort of cirrhotic patients.
METHODS: Patients consecutively hospitalized with decompensated cirrhosis during
1 year were evaluated. At admission, ICG and BNP measurements were performed in
83 patients (median age 56 years; median Child-Pugh score=10). The 70 patients
discharged were followed for the occurrence of death within 6 months.
RESULTS: Median BNP levels were 130.3 (65.2-363.3) pg/ml. Independent BNP
predictors in multivariate linear regression analysis were cardiac output, age
and haemoglobin (R(2)=36.7%). The 24 patients with cardiac systolic dysfunction,
defined by low cardiac output, had higher BNP concentrations than the other
patients (230.8 vs 98.5 pg/ml, P=0.003). BNP levels above median were associated
with an increased occurrence of death within 6 months of discharge (log rank
P=0.023). Cardiac output and BNP were predictors of survival in univariate Cox
regression analysis. Only BNP remained independently related to the outcome in
multivariate analysis [hazard ratio=2.86 (1.11-7.38), P=0.03].
CONCLUSIONS: BNP levels in cirrhosis reflect cardiac systolic function and
non-cardiac variables that should be considered in their interpretation. BNP is
an independent predictor of medium-term survival in advanced cirrhosis,
suggesting its utility in risk stratification of decompensated cirrhotic
patients. BACKGROUND: Cardiopulmonary exercise test (CPT) has a prominent value in
assessing clinical severity in chronic heart failure (HF) patients. Reduced free
triiodothyronine (fT3) plasma level is associated with a more severe disease and
prognosis. The aim of this study was to evaluate the relationship between low
fT3 plasma level and reduced exercise capacity in chronic HF, and to determine
the influence of a low T3 status in subsets of patients with different
functional impairment.
METHODS AND RESULTS: 240 HF patients (79% males; age 62 ± 12 years, mean ±
standard deviation; left ventricular ejection fraction, EF, 30 ± 9%) underwent a
CPT, clinical and neurohormonal characterization (assay for plasma brain
natriuretic peptide, BNP, norepinephrine, aldosterone, renin activity, fT3, free
T4, thyroid-stimulating hormone). At multivariate analysis in the whole
population, age, gender and BNP level were independently associated with peak
VO2, whereas in patients with severe functional impairment (peak VO2 < 14
ml/min/kg) fT3 resulted independently related to peak VO2, together with gender
and BNP. When patients with peak VO2 < 14 ml/min/kg were divided according to
fT3 levels, patients with low T3 syndrome showed reduced exercise capacity and
worse ventilatory efficiency.
CONCLUSIONS: BNP and fT3 are independently associated with exercise capacity in
severely compromised HF patients. OBJECTIVE: The objective of this paper was to investigate the diagnostic and
prognostic value of plasma B type natriuretic peptide (BNP) and serum
triiodothyronine (T3) in chronic congestive heart failure (CHF).
METHODS: 156 cases of CHF patients and 75 cases of cardiac function I patients
hospitalized over the same period were utilized in this study. On admission, the
patient's BNP and T3 plasma concentrations were measured. The correlation
analysis of plasma BNP and T3 in CHF patients with cardiac function
classification was conducted.
RESULTS: According to the NYHA grading systems, the plasma BNP levels in
patients with II, III, and IV grade CHF were significantly higher than those
with cardiac function I (P < 0.05); BNP levels and NYHA grading of cardiac
function correlated positively. The BNP concentrations increased with CHF
progression (P < 0.01). The T3 level and NYHA grading of cardiac function
correlated negatively.TheT3 level decreased as the degree of heart failure
increased. Using CHF in combination with BNP to predict the occurrence of CHF
had a sensitivity value of 90.8% with 95.5% specificity, 86.3% accuracy, and a
negative predictive value of 87.7%.
CONCLUSIONS: Plasma BNP was more sensitive than T3 in the diagnosis of CHF. The
T3 was more meaningful than the BNP in the prognosis of CHF. The BNP and T3
combination detection was more valuable in determining the severity of CHF and
prognosis. |
List packages for transcription factor binding sites' (TFBS) analysis available in R/Bioconductor | Neighbourhood Consistent PC (NCPC) algorithms, MMDiff and cosmo. | Inferring the combinatorial regulatory code of transcription factors (TFs) from
genome-wide TF binding profiles is challenging. A major reason is that TF
binding profiles significantly overlap and are therefore highly correlated.
Clustered occurrence of multiple TFs at genomic sites may arise from chromatin
accessibility and local cooperation between TFs, or binding sites may simply
appear clustered if the profiles are generated from diverse cell populations.
Overlaps in TF binding profiles may also result from measurements taken at
closely related time intervals. It is thus of great interest to distinguish TFs
that directly regulate gene expression from those that are indirectly associated
with gene expression. Graphical models, in particular Bayesian networks, provide
a powerful mathematical framework to infer different types of dependencies.
However, existing methods do not perform well when the features (here: TF
binding profiles) are highly correlated, when their association with the
biological outcome is weak, and when the sample size is small. Here, we develop
a novel computational method, the Neighbourhood Consistent PC (NCPC) algorithms,
which deal with these scenarios much more effectively than existing methods do.
We further present a novel graphical representation, the Direct Dependence Graph
(DDGraph), to better display the complex interactions among variables. NCPC and
DDGraph can also be applied to other problems involving highly correlated
biological features. Both methods are implemented in the R package ddgraph,
available as part of Bioconductor
(http://bioconductor.org/packages/2.11/bioc/html/ddgraph.html). Applied to real
data, our method identified TFs that specify different classes of cis-regulatory
modules (CRMs) in Drosophila mesoderm differentiation. Our analysis also found
depletion of the early transcription factor Twist binding at the CRMs regulating
expression in visceral and somatic muscle cells at later stages, which suggests
a CRM-specific repression mechanism that so far has not been characterised for
this class of mesodermal CRMs. BACKGROUND: Cell-specific gene expression is controlled by epigenetic
modifications and transcription factor binding. While genome-wide maps for these
protein-DNA interactions have become widely available, quantitative comparison
of the resulting ChIP-Seq data sets remains challenging. Current approaches to
detect differentially bound or modified regions are mainly borrowed from RNA-Seq
data analysis, thus focusing on total counts of fragments mapped to a region,
ignoring any information encoded in the shape of the peaks.
RESULTS: Here, we present MMDiff, a robust, broadly applicable method for
detecting differences between sequence count data sets. Based on quantifying
shape changes in signal profiles, it overcomes challenges imposed by the highly
structured nature of the data and the paucity of replicates.We first use a
simulated data set to compare the performance of MMDiff with results obtained by
four alternative methods. We demonstrate that MMDiff excels when peak profiles
change between samples. We next use MMDiff to re-analyse a recent data set of
the histone modification H3K4me3 elucidating the establishment of this prominent
epigenomic marker. Our empirical analysis shows that the method yields
reproducible results across experiments, and is able to detect functional
important changes in histone modifications. To further explore the broader
applicability of MMDiff, we apply it to two ENCODE data sets: one investigating
the histone modification H3K27ac and one measuring the genome-wide binding of
the transcription factor CTCF. In both cases, MMDiff proves to be complementary
to count-based methods. In addition, we can show that MMDiff is capable of
directly detecting changes of homotypic binding events at neighbouring binding
sites. MMDiff is readily available as a Bioconductor package.
CONCLUSIONS: Our results demonstrate that higher order features of ChIP-Seq
peaks carry relevant and often complementary information to total counts, and
hence are important in assessing differential histone modifications and
transcription factor binding. We have developed a new computational method,
MMDiff, that is capable of exploring these features and therefore closes an
existing gap in the analysis of ChIP-Seq data sets. |
Simpson grading is used to describe resection of which brain tumor? | The Simpson grading system was used to assess the extent of surgical resection of meningioma. | PURPOSE: To compare tumor control rates after surgical resection or stereotactic
radiosurgery for patients with small- to medium-size intracranial meningiomas.
MATERIALS AND METHODS: Between 1990 and 1997, 198 adult meningioma patients
treated at our center underwent either surgical resection (n = 136) or
radiosurgery (n = 62) as primary management for benign meningiomas <35 mm in
average diameter. Tumor recurrence or progression rates were calculated by the
Kaplan-Meier method according to an independent radiographic review. The mean
follow-up was 64 months.
RESULTS: The tumor resections were Simpson Grade 1 in 57 (42%), Grade 2 in 57
(42%), and Grade 3-4 in 22 (16%). The mean margin and maximal radiation dose at
radiosurgery was 17.7 Gy and 34.9 Gy, respectively. Tumor recurrence/progression
was more frequent in the surgical resection group (12%) than in the
radiosurgical group (2%; p = 0.04). No statistically significant difference was
detected in the 3- and 7-year actuarial progression-free survival (PFS) rate
between patients with Simpson Grade 1 resections (100% and 96%, respectively)
and patients who underwent radiosurgery (100% and 95%, respectively; p = 0.94).
Radiosurgery provided a higher PFS rate compared with patients with Simpson
Grade 2 (3- and 7-year PFS rate, 91% and 82%, respectively; p <0.05) and Grade
3-4 (3- and 7-year PFS rate, 68% and 34%, respectively; p <0.001) resections.
Subsequent tumor treatments were more common after surgical resection (15% vs.
3%, p = 0.02). Complications occurred in 10% of patients after radiosurgery
compared with 22% of patients after surgical resection (p = 0.06).
CONCLUSIONS: The PFS rate after radiosurgery was equivalent to that after
resection of a Simpson Grade 1 tumor and was superior to Grade 2 and 3-4
resections in our study. If long-term follow-up confirms the high tumor control
rate and low morbidity of radiosurgery, this technique will likely become the
preferred treatment for most patients with small- to moderate-size meningiomas
without symptomatic mass effect. OBJECT: In 1957, Simpson published a seminal paper defining the risk factors for
recurrence following surgical treatment of intracranial meningiomas. Given that
Simpson's study was published more than 50 years ago, preceding image guidance
technology and MR imaging, the authors reviewed their own experience with
surgical treatment of Grade I meningiomas to determine if Simpson's grading
scale is still relevant to modern neurosurgical practice.
METHODS: From this cohort, the authors evaluated all patients undergoing
craniotomy for resection of a histologically proven WHO Grade I meningioma as
their initial therapy. Clinical information was retrospectively reconstructed
using patient medical records and radiological data. Recurrence analysis was
performed using the Kaplan-Meier method.
RESULTS: The 5-year recurrence/progression-free survival for all patients
receiving a Simpson Grade I, II, III, or IV resection was 95, 85, 88, and 81%,
respectively (p = not significant, log-rank test). Kaplan-Meier analysis
revealed no significant difference in recurrence-free survival between patients
receiving a Simpson Grade I, II, III, or IV resection. Analysis limited to
meningiomas arising from the skull base (excluding the cavernous sinus)
similarly found no significant benefit to Simpson Grade I or II resection, and
the survival curves were nearly superimposed.
CONCLUSIONS: In this study of a cohort of patients undergoing surgery for WHO
Grade I meningiomas, the authors demonstrate that the benefit of more aggressive
attempts to resect the tumor with dura and underlying bone was negligible
compared with simply removing the entire tumor, or even leaving small amounts of
tumor attached to critical structures. The authors believe that these data
reflect an evolution in the nature of meningioma surgery over the past 2
decades, and bring into question the relevance of using Simpson's grading system
as the sole predictor of recurrence. OBJECT: The completeness of meningioma resection depends on the resection of
dura mater invaded by the tumor. The pathological changes of the dura around the
tumor can be interpreted by evaluating the dural tail sign (DTS) on MRI studies.
The goal of this study was to clarify the pathological characteristics of the
DTSs, propose a classification based on the histopathological and radiological
correlation, and identify the invasive range of tumor cells in different types
of DTS.
METHODS: The authors retrospectively reviewed 179 patients with convexity
meningiomas who underwent Simpson Grade I resection. All patients underwent an
enhanced MRI examination preoperatively. The convexity meningiomas were
dichotomized into various subtypes in accordance with the 2007 WHO
classification of tumors of the CNS, and the DTS was identified based on the
Goldsher criteria. The range of resection of the involved dura was 3 cm from the
base of the tumor, which corresponded with the length of DTS on MRI studies.
Histopathological examination of dura at 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 cm
from the base of the tumor was conducted, and the findings were correlated with
the preoperative MRI appearance of the DTS.
RESULTS: A total of 154 (86%) of 179 convexity meningiomas were classified into
WHO Grade I subtype, including transitional (44 [28.6%] of 154), meningothelial
(36 [23.4%] of 154), fibrous (23 [14.9%] of 154), psammomatous (22 [14.3%] of
154), secretory (10 [6.5%] of 154), and angiomatous (19 [12.3%] of 154). The
other 25 (14%) were non-Grade I (WHO) tumors, including atypical (12 [48%] of
25), anaplastic (5 [20%] of 25), and papillary (8 [32%] of 25). The DTS was
classified into 5 types: smooth (16 [8.9%] of 179), nodular (36 [20.1%] of 179),
mixed (57 [31.8%] of 179), symmetrical multipolar (15 [8.4%] of 179), and
asymmetrical multipolar (55 [30.7%] of 179). There was a significant difference
in distribution of DTS type between Grade I and non-Grade I tumors (p = 0.004),
whereas the difference was not significant among Grade I tumors (0.841) or among
non-Grade I tumors (p = 0.818). All smooth-type DTSs were encountered in Grade I
tumors, and the mixed DTS (52 [33.8%] of 154) was the most common type in these
tumors. Nodular-type DTS was more commonly seen in non-Grade I tumors (12 [48%]
of 25). Tumor invasion was found in 88.3% (158 of 179) of convexity meningiomas,
of which the range of invasion in 82.3% (130 of 158) was within 2 cm and that in
94.9% (150 of 158) was within 2.5 cm. The incidence of invasion and the range
invaded by tumor cells varied in different types of DTS, and differences were
statistically significant (p < 0.001).
CONCLUSIONS: Nodular-type DTS on MRI studies might be associated with non-Grade
I tumors. The range of dural resection for convexity meningiomas should be 2.5
cm from the tumor base, and if this extent of resection is not feasible, the
type of DTS should be considered. However, for skull base meningiomas, in which
mostly Simpson Grade II resection is achieved, the use of this classification
should be further validated. The classification of DTS enables the surgeon to
predict preoperatively and then to achieve the optimal range of dural resection
that might significantly reduce the recurrence rate of meningiomas. OBJECT: Meningiomas treated by subtotal or partial resection are associated with
significantly shorter recurrence-free survival than those treated by gross-total
resection. The Simpson grading system classifies incomplete resections into a
single category, namely Simpson Grade IV, with wide variations in the volume and
location of residual tumors, making it complicated to evaluate the achievement
of surgical goals and predict the prognosis of these tumors. Authors of the
present study investigated the factors related to necessity of retreatment and
tried to identify any surgical nuances achievable with the aid of modern
neurosurgical techniques for meningiomas treated using Simpson Grade IV
resection.
METHODS: This retrospective analysis included patients with WHO Grade I
meningiomas treated using Simpson Grade IV resection as the initial therapy at
the University of Tokyo Hospital between January 1995 and April 2010.
Retreatment was defined as reresection or stereotactic radiosurgery due to
postoperative tumor growth.
RESULTS: A total of 38 patients were included in this study. Regrowth of
residual tumor was observed in 22 patients with a mean follow-up period of 6.1
years. Retreatment was performed for 20 of these 22 tumors with regrowth. Risk
factors related to significantly shorter retreatment-free survival were age
younger than 50 years (p = 0.006), postresection tumor volume of 4 cm(3) or more
(p = 0.016), no dural detachment (p = 0.001), and skull base location (p =
0.016). Multivariate analysis revealed that no dural detachment (hazard ratio
[HR] 6.42, 95% CI 1.41-45.0; p = 0.02) and skull base location (HR 11.6, 95% CI
2.18-218; p = 0.002) were independent risk factors for the necessity of early
retreatment, whereas postresection tumor volume of 4 cm(3) or more was not a
statistically significant risk factor.
CONCLUSIONS: Compared with Simpson Grade I, II, and III resections, Simpson
Grade IV resection includes highly heterogeneous tumors in terms of resection
rate and location of the residual mass. Despite the difficulty in analyzing such
diverse data, these results draw attention to the favorable effect of dural
detachment (instead of maximizing the resection rate) on long-term tumor
control. Surgical strategy with an emphasis on detaching the tumor from the
affected dura might be another important option in resection of high-risk
meningiomas not amenable to gross-total resection. BACKGROUND: The relevance of the Simpson grading system as a predictor of
meningioma progression or recurrence in modern neurosurgical practice has
recently been called into question. The aim of our study was to compare the risk
of progression/recurrence of tumours that had been treated with different
Simpson grade resections in a contemporary population of benign (WHO grade I)
meningioma patients.
METHOD: One hundred eighty-three patients with histologically confirmed WHO
grade I meningioma were retrospectively analysed. All patients underwent
first-time craniotomy as their initial therapy between 2004 and 2012. Univariate
analysis was performed using log-rank testing and Kaplan-Meier analysis for
progression/recurrence-free survival. Multivariate analysis was performed using
Cox proportional hazards regression modelling.
RESULTS: The three-year progression/recurrence-free survival rates for patients
receiving Simpson grade 1, 2 or 4 resections were 95 %, 87 % and 67 %,
respectively. Simpson grade 4 resections progressed/recurred at a significantly
greater rate than Simpson grade 1 resections (hazard ratio [HR] = 3.26,
P = 0.04), whereas Simpson grade 2 resections did not progress/recur at a
significantly greater rate than Simpson grade 1 resections (HR = 1.78,
P = 0.29). Subtotal resections progressed/recurred at a significantly greater
rate than gross-total resections (HR = 2.47, P = 0.03).
CONCLUSIONS: Tumours that undergo subtotal resection are at a significantly
greater risk of progression/recurrence than tumours that undergo gross-total
resection. Gross-total resection should therefore be the aim of surgery.
However, given modern access to follow-up imaging and stereotactic radiosurgery,
these results should not be used to justify overly 'heroic' tumour resection. BACKGROUND: The rarity and the inconsistent criteria for defining atypical
meningioma prior to the WHO 2007 classification made its management and
prognostic factors poorly understood. Only few articles have addressed the
survival rates of WHO-classified atypical meningiomas. The small number or the
disproportionate representation of irradiated patients was a weakness for these
articles. This study evaluated whether the extent of surgery and receiving
adjuvant radiotherapy after an initial operation along with other patient
characteristics influenced the recurrence and survival rates of atypical
meningiomas.
METHODS: The clinical and surgical notes of the 79 patients with grade II
atypical meningioma treated at our center over 13 years were retrospectively
evaluated. The histology grading was consistent with WHO 2007 classification.
The Simpson grading system was used to assess the extent of surgical resection.
Kaplan Meier analysis, Cox multivariate regression analysis, and the Log-rank
test were conducted using STATA® statistical package.
RESULTS: The average age at the time of initial operation was 58 years, and 54 %
were males. The mean follow-up period was 50 months. In Cox multivariate
analysis, only Simpson grading was predictive of recurrence (hazard ratio = 2.22
/ 1 increase in Simpson grade. p = 0.003). Simpson grade I patients had a
relapse-free survival rate of 97 and 74 % at one and five years, respectively,
compared with 88 and 32 % in the subtotal resection group (Simpson grades II to
IV). There was no statistically significant correlation between recurrence and
subjecting patients to postoperative radiotherapy. Apart from Simpson grade I
patients, there was a general trend for worse outcome in irradiated patients.
CONCLUSIONS: The most important prognostic factor in determining recurrence was
Simpson grading. There was no statistically significant impact of adjuvant
radiotherapy on the recurrence of atypical meningiomas. Meta-analysis for the
existing literature is needed. OBJECTIVE: We reviewed our series of olfactory groove meningiomas (OGMs) with
the aim to relate the surgical approach with outcome and to define clinical and
pathologic predictors of prognosis.
METHODS: Ninety-nine patients who underwent 113 craniotomies at our Institution
between 1984 and 2010 were entered this study. The relationship between surgical
approach (bifrontal, fronto-orbito-basal, and pterional) and either tumor
diameter, extent of tumor resection, complication rate, need of reoperation, and
Karnofsky Performance Status (KPS) was analyzed. The impact of age (≤ 70 vs. >
70 years), sex, tumor diameter (< 6 vs. ≥ 6 cm), pre- and postoperative KPS (<
80 vs. ≥ 80), Simpson grade (I-II vs. III-IV), and World Health Organization
(WHO) histologic grade (I vs. II-III) on survival was assessed. Kaplan-Meier
survival curves were plotted and differences in survival between groups of
patients were compared. A multivariate analysis adjusted for age, pre- and
postoperative KPS, Simpson grade, tumor diameter, and WHO histologic grade also
was performed.
RESULTS: The fronto-orbito-basal approach (n = 22) allowed a significantly
greater percentage of Simpson I-II removals than the bifrontal (n = 70) and
pterional approach (n = 21) (P = 0.0354 and P = 0.0485, respectively). The risk
of life-threatening complications trended to be lower in patients operated upon
either via the fronto-orbito-basal and via the pterional approach than in those
treated via the bifrontal approach. Retraction-related brain swelling did not
occur in any case after the fronto-orbito-basal approach (P = 0.0384); however,
this approach was associated with a greater rate of cerebrospinal fluid leak (P
= 0.0011). Among prognostic factors, age ≤ 70 years (P = 0.0044), tumor diameter
<6 cm (P = 0.0455), pre- and postoperative KPS ≥ 80 (both P < 0.0001), Simpson
grade I-II (P = 0.0096), and WHO histologic grade I (P = 0.0112) were
significantly associated with longer overall survival. Age (P = 0.0393) and WHO
histologic grade (P = 0.0418) emerged as independent prognostic factors for
overall survival on multivariate analysis.
CONCLUSION: In the largest series of OGMs published to date, the bifrontal
approach was associated with a greater risk of life-threatening complications
compared with the lateral pterional and fronto-orbito-basal approaches. The
fronto-orbito-basal approach provided greater chances of total tumor removal
than the bifrontal and pterional approaches. Two independent factors for overall
survival of patients with OGM were identified, namely age and WHO grade. BACKGROUND: Because of their rarity, outcomes regarding spinal atypical
meningiomas (AMs) remain unclear.
OBJECTIVE: To describe the recurrence rate and postoperative outcomes after
resection of spinal AMs, and to discuss an appropriate resection strategy and
adjuvant therapy for spinal AMs.
METHODS: Data from all patients who presented with spinal AMs to 2 tertiary
referral centers between 1998 and 2013 were obtained by chart review.
RESULTS: From 102 patients with spinal meningioma, 20 AM tumors (7 cervical, 11
thoracic, 2 thoracolumbar) were identified in 18 patients (median age, 50 years
[range, 19-75] at time of resection; 11% male; median follow-up, 32 months
[range, 1-179] after resection). Before resection, patients had sensory deficits
(70%), pain (70%), weakness (60%), ataxia (50%), spasticity (65%), and
incontinence (35%). One tumor presented asymptomatically. Simpson grade I, II,
III, and IV resection were achieved in 3 (15%), 13 (65%), 2 (10%), and 2 (10%)
tumors, respectively. One patient that underwent Simpson grade III resection
received adjuvant radiation therapy. After Simpson grade I-III or gross total
resection, no tumors recurred (0%; confidence interval, 0%-17.6%). After Simpson
grade IV resection, 1 tumor recurred (50%; confidence interval, 1.3%-98.7%).
With the exception of 1 patient who had bilateral paraplegia perioperatively,
all other patients experienced improvement of preoperative symptoms after
surgery (median time, 3.6 months [range, 1-13] after resection).
CONCLUSION: Despite published cases suggesting an aggressive clinical course for
spinal AMs, this series of spinal AMs reports that gross total resection without
adjuvant radiation therapy resulted in symptom resolution and low recurrence. |
Where in the cell do we find the protein Cep135? | centrosome | Cep135 is a 135-kDa, coiled-coil centrosome protein important for microtubule
organization in mammalian cells [Ohta et al., 2002: J. Cell Biol. 156:87-99]. To
identify Cep135-interacting molecules, we screened yeast two-hybrid libraries.
One clone encoded dynamitin, a p50 dynactin subunit, which localized at the
centrosome and has been shown to be involved in anchoring microtubules to
centrosomes. The central domain of p50 binds to the C-terminal sequence of
Cep135; this was further confirmed by immunoprecipitation and immunostaining of
CHO cells co-expressing the binding domains for Cep135 and p50. Exogenous p50
lacking the Cep 135-binding domain failed to locate at the centrosome,
suggesting that Cep135 is required for initial targeting of the centrosome.
Altered levels of Cep135 and p50 by RNAi and protein overexpression caused the
release of endogenous partner molecules from centrosomes. This also resulted in
dislocation of other centrosomal molecules, such as gamma-tubulin and
pericentrin, ultimately leading to disorganization of microtubule patterns.
These results suggest that Cep135 and p50 play an important role in assembly and
maintece of functional microtubule-organizing centers. Most animals have two centrioles in spermatids (the distal and proximal
centrioles), but insect spermatids seem to contain only one centriole (Fuller
1993), which functionally resembles the distal centriole. Using fluorescent
centriolar markers, we identified a structure near the fly distal centriole that
is reminiscent of a proximal centriole (i.e., proximal centriole-like, or PCL).
We show that the PCL exhibits several features of daughter centrioles. First, a
single PCL forms near the proximal segment of the older centriole. Second, the
centriolar proteins SAS-6, Ana1, and Bld10p/Cep135 are in the PCL. Third, PCL
formation depends on SAK/PLK4 and SAS-6. Using a genetic screen for PCL defect,
we identified a mutation in the gene encoding the conserved centriolar protein
POC1, which is part of the daughter centriole initiation site (Kilburn et al.
2007) in Tetrahymena. We conclude that the PCL resembles an early intermediate
structure of a forming centriole, which may explain why no typical centriolar
structure is observed under electron microscopy. We propose that, during the
evolution of insects, the proximal centriole was simplified by eliminating the
later steps in centriole assembly. The PCL may provide a unique model to study
early steps of centriole formation. Cilia and flagella play multiple essential roles in animal development and cell
physiology. Defective cilium assembly or motility represents the etiological
basis for a growing number of human diseases. Therefore, how cilia and flagella
assemble and the processes that drive motility are essential for understanding
these diseases. Here we show that Drosophila Bld10, the ortholog of
Chlamydomonas reinhardtii Bld10p and human Cep135, is a ubiquitous centriolar
protein that also localizes to the spermatid basal body. Mutants that lack Bld10
assemble centrioles and form functional centrosomes, but centrioles and
spermatid basal bodies are short in length. bld10 mutant flies are viable but
male sterile, producing immotile sperm whose axonemes are deficient in the
central pair of microtubules. These results show that Drosophila Bld10 is
required for centriole and axoneme assembly to confer cilium motility. Cancer cells frequently induce aberrant centrosomes, which have been implicated
in cancer initiation and progression. Human colorectal cancer cells, HCT116,
contain aberrant centrioles composed of disorganized cylindrical microtubules
and displaced appendages. These cells also express unique centrosome-related
structures associated with a subset of centrosomal components, including
gamma-tubulin, centrin and PCM1. During hydroxyurea treatment, these abnormal
structures become more abundant and undergo a change in shape from small dots to
elongated fibers. Although gamma-tubulin seems to exist as a ring complex, the
abnormal structures do not support microtubule nucleation. Several lines of
evidence suggest that the fibers correspond to a disorganized form of centriolar
microtubules. Plk4, a mammalian homolog of ZYG-1 essential for initiation of
centriole biogenesis, is not associated with the gamma-tubulin-specific abnormal
centrosomes. The amount of Plk4 at each centrosome was less in cells with
abnormal centrosomes than cells without gamma-tubulin-specific abnormal
centrosomes. In addition, the formation of abnormal structures was abolished by
expression of exogenous Plk4, but not SAS6 and Cep135/Bld10p, which are
downstream regulators required for the organization of nine-triplet
microtubules. These results suggest that HCT116 cells fail to organize the
ninefold symmetry of centrioles due to insufficient Plk4. The centriole and basal body (CBB) structure nucleates cilia and flagella, and
is an essential component of the centrosome, underlying eukaryotic
microtubule-based motility, cell division and polarity. In recent years,
components of the CBB-assembly machinery have been identified, but little is
known about their regulation and evolution. Given the diversity of cellular
contexts encountered in eukaryotes, but the remarkable conservation of CBB
morphology, we asked whether general mechanistic principles could explain CBB
assembly. We analysed the distribution of each component of the human
CBB-assembly machinery across eukaryotes as a strategy to generate testable
hypotheses. We found an evolutionarily cohesive and ancestral module, which we
term UNIMOD and is defined by three components (SAS6, SAS4/CPAP and
BLD10/CEP135), that correlates with the occurrence of CBBs. Unexpectedly, other
players (SAK/PLK4, SPD2/CEP192 and CP110) emerged in a taxon-specific manner. We
report that gene duplication plays an important role in the evolution of CBB
components and show that, in the case of BLD10/CEP135, this is a source of
tissue specificity in CBB and flagella biogenesis. Moreover, we observe extreme
protein divergence amongst CBB components and show experimentally that there is
loss of cross-species complementation among SAK/PLK4 family members, suggesting
species-specific adaptations in CBB assembly. We propose that the UNIMOD theory
explains the conservation of CBB architecture and that taxon- and
tissue-specific molecular innovations, gained through emergence, duplication and
divergence, play important roles in coordinating CBB biogenesis and function in
different cellular contexts. To study the mechanism of centrosome duplication in cycling cells, we
established a novel system of multiple centrosome formation in two types of
cells: CHO cells treated with RO3306, a Cyclin-dependent kinase 1 (Cdk1)
inhibitor and DT40 cells, in which Cdks were knocked out by chemical genetics.
Cdk1-inactivated cells initiated DNA replication and centrosome duplication at
the onset of S phase. They became arrested at the end of G2, but the centrosome
cycle continued to produce supernumerary centrioles/centrosomes without DNA
endoreplication in those cells. Centrosomes were amplified in a highly
synchronous and reproducible manner: all of them were located next to the
nucleus and spread widely apart from each other with several μm in distance.
Double knockout of Cdk1 and Cdk2 caused cell cycle arrest at G1/S and
centrosomes were no longer duplicated. However, cells continued to grow and
increased their volume over 10-fold during 48 hr of culture. Centrosome
components, including γ-tubulin and Cep135, were synthesized and accumulated
during the arrest, allowing rapid centrosome multiplication upon recovery from
the cell cycle arrest or expression of exogenous Plk4 in G1/S cells. Thus
centrosome amplification results from the discoordination of the centrosome
cycle from the progression of other cell cycle events, which is controlled by
different levels of Cdk activities. Cep135/Bld10 is a conserved centriolar protein required for the formation of the
central cartwheel, an early intermediate in centriole assembly. Surprisingly,
Cep135/Bld10 is not essential for centriole duplication in Drosophila,
suggesting either that Cep135/Bld10 is not essential for cartwheel formation, or
that the cartwheel is not essential for centriole assembly in flies. Using
electron tomography and super-resolution microscopy we show that centrioles can
form a cartwheel in the absence of Cep135/Bld10, but centriole width is
increased and the cartwheel appears to disassemble over time. Using 3D
structured illumination microscopy we show that Cep135/Bld10 is localized to a
region between inner (SAS-6, Ana2) and outer (Asl, DSpd-2 and D-PLP) centriolar
components, and the localization of all these component is subtly perturbed in
the absence of Cep135/Bld10, although the ninefold symmetry of the centriole is
maintained. Thus, in flies, Cep135/Bld10 is not essential for cartwheel assembly
or for establishing the ninefold symmetry of centrioles; rather, it appears to
stabilize the connection between inner and outer centriole components. Basal bodies nucleate, anchor, and organize cilia. As the anchor for motile
cilia, basal bodies must be resistant to the forces directed toward the cell as
a consequence of ciliary beating. The molecules and generalized mechanisms that
contribute to the maintece of basal bodies remain to be discovered.
Bld10/Cep135 is a basal body outer cartwheel domain protein that has established
roles in the assembly of nascent basal bodies. We find that Bld10 protein first
incorporates stably at basal bodies early during new assembly. Bld10 protein
continues to accumulate at basal bodies after assembly, and we hypothesize that
the full complement of Bld10 is required to stabilize basal bodies. We identify
a novel mechanism for Bld10/Cep135 in basal body maintece so that basal
bodies can withstand the forces produced by motile cilia. Bld10 stabilizes basal
bodies by promoting the stability of the A- and C-tubules of the basal body
triplet microtubules and by properly positioning the triplet microtubule blades.
The forces generated by ciliary beating promote basal body disassembly in bld10Δ
cells. Thus Bld10/Cep135 acts to maintain the structural integrity of basal
bodies against the forces of ciliary beating in addition to its separable role
in basal body assembly. Centrioles are essential for the formation of cilia and flagella. They also form
the core of the centrosome, which organizes microtubule arrays important for
cell shape, polarity, motility and division. Here, we have used super-resolution
3D-structured illumination microscopy to analyse the spatial relationship of 18
centriole and pericentriolar matrix (PCM) components of human centrosomes at
different cell cycle stages. During mitosis, PCM proteins formed extended
networks with interspersed γ-Tubulin. During interphase, most proteins were
arranged at specific distances from the walls of centrioles, resulting in ring
staining, often with discernible density masses. Through use of site-specific
antibodies, we found the C-terminus of Cep152 to be closer to centrioles than
the N-terminus, illustrating the power of 3D-SIM to study protein disposition.
Appendage proteins showed rings with multiple density masses, and the number of
these masses was strongly reduced during mitosis. At the proximal end of
centrioles, Sas-6 formed a dot at the site of daughter centriole assembly,
consistent with its role in cartwheel formation. Plk4 and STIL co-localized with
Sas-6, but Cep135 was associated mostly with mother centrioles. Remarkably, Plk4
formed a dot on the surface of the mother centriole before Sas-6 staining became
detectable, indicating that Plk4 constitutes an early marker for the site of
nascent centriole formation. Our study provides novel insights into the
architecture of human centrosomes and illustrates the power of super-resolution
microscopy in revealing the relative localization of centriole and PCM proteins
in unprecedented detail. |
Is delayed enhancement documented in patients with non-ischemic dilated cardiomyopathy? | Delayed enhancement is documented in almost 30% of patients with non-ischemic dilated cardiomyopathy and its pattern is characterized by mid-wall, patchy or diffuse location. | BACKGROUND: The dilated phase of hypertrophic cardiomyopathy (HCM) has a poor
prognosis. For correct recognition of such patients, we compared the findings in
cardiac delayed enhancement (DE)-magnetic resoce imaging (MRI) between HCM
and dilated cardiomyopathy (DCM) patients.
METHODS AND RESULTS: Sixty-five patients (HCM 39, DCM 26) underwent
gadolinium-DTPA-enhanced MRI. The HCM patients were divided into those with
preserved (HCM-P, n = 30) and those with impaired systolic function (HCM-I, n =
9). DE-MRI demonstrated focal or diffuse DE at the left ventricular (LV) wall in
60% of HCM-P and 100% of HCM-I, but in only 12% of DCM. The DE distributed
mainly septal to the anterior wall of LV, but the DE volume against whole LV
muscle volume was much larger in HCM-I than in HCM-P and DCM (4.1 +/- 6.1% in
HCM-P, 14.6 +/- 11.9% in HCM-I, and 0.8 +/- 2.4% in DCM, means +/- SD, P < .05).
In HCM, there were weak but significant correlations between DE volume, and LV
end-diastolic volume and LV end-systolic volume. In HCM-P, the percent of length
shortening in the segments with DE was lower than that without DE.
CONCLUSIONS: The HCM patients had more DE than the DCM patients, and DE volume
correlated to lower global and local LV function. DE-MRI may be useful to
evaluate myocardial damage in HCM patients, and to differentiate the dilated
phase of HCM from DCM. OBJECTIVES: Differentiation between primary dilated cardiomyopathy and ischemic
cardiomyopathy has an important clinical significance. Contrast-enhanced
cardiovascular magnetic resoce can play a role in this task, identifying
myocardial scarring or fibrosis as presence of delayed enhancement. The aim of
the present study was to evaluate the diagnostic potential of contrast-enhanced
cardiovascular magnetic resoce in differentiating dilated cardiomyopathy from
ischemic cardiomyopathy.
METHODS: Contrast-enhanced cardiovascular magnetic resoce was performed in
100 patients with left ventricular dilatation and reduced systolic function: 24
had normal coronary arteries (dilated cardiomyopathy group) and 76 had
significant coronary artery disease (ischemic cardiomyopathy group), with or
without previous myocardial infarction.
RESULTS: In the dilated cardiomyopathy group, only seven (29%) patients showed
delayed enhancement and its pattern was characterized by mid-wall, patchy or
diffuse location. All patients with ischemic cardiomyopathy and prior myocardial
infarction (54 subjects) showed delayed enhancement with subendocardial (n = 4)
or transmural (n = 50) extension. Among the 22 patients with ischemic
cardiomyopathy but without previous myocardial infarction, 13 (59%) showed
either subendocardial (n = 4) or transmural (n = 9) delayed enhancement.
CONCLUSIONS: Patterns of delayed enhancement are different in dilated
cardiomyopathy and ischemic cardiomyopathy, reflecting the presence of scarring
or various degrees of fibrosis in left ventricular myocardium. The presence of
subendocardial or transmural delayed enhancement at contrast-enhanced
cardiovascular magnetic resoce allowed distinction between dilated
cardiomyopathy and ischemic cardiomyopathy with high sensitivity (88%) and
specificity (100%). Integration of cardiovascular magnetic resoce results
with angiographic information can be useful in the identification of pathogenic
mechanisms underlying left ventricular dysfunction. PURPOSE: Delayed enhancement cardiovascular magnetic resoce (DE-CMR) can
detect cardiac scarring and has the potential to visualize the progression of
myocardial remodeling. We determined whether DE-CMR can predict cardiac events
in dilated cardiomyopathy patients.
MATERIALS AND METHODS: Transthoracic echocardiography, coronary arteriography,
and DE-CMR studies were performed in 60 consecutive dilated cardiomyopathy (DCM)
patients. Percent delayed enhancement (%DE) was determined as the ratio of the
area showing delayed enhancement to the total myocardial area in three
short-axis views. Patients were classified as advanced group (Group A) when %DE
was 10% or higher, and as non-advanced group (Group NA) when %DE was less than
10%. The incidence of cardiac events and the clinical history were compared
between Group A and Group NA.
RESULTS: There were 11 patients in Group A and 49 patients in Group NA. The
incidence of cardiac events was significantly higher in Group A (36%; 4/11
patients) than in Group NA (2.0%; 1/49 patients) (log rank, p=0.0001).
CONCLUSION: DE-CMR is a useful tool to predict cardiac events in DCM patients. OBJECTIVE: To compare the imaging characteristics of magnetic resoce (MR)
delayed enhancement between ischemic and nonischemic myocardial diseases.
METHODS: We retrospectively analyzed the imaging and clinical characteristics of
25 patients who had MR delayed enhancement.
RESULTS: Among the 25 cases, 19 cases were ischemic heart diseases, in which the
delayed enhancement was subendocardium, non-transmural or transmural; two cases
were hypertrophic cardiomyopathy, in which the delayed enhancement was midwall
in the hypertrophic myocardium, strip- and patch-shaped; one case was dilated
cardiomyopathy, in which the delayed enhancement was diffuse small midwall spots
two cases was restrictive cardiomyopathy, in which the delayed enhancement was
located in the area of the subendocardium both of the right and left ventricles;
and one case was a mass of the lateral wall of the left ventricle, in which the
delayed enhancement with a clumpy shape was shown.
CONCLUSIONS: MR myocardial delayed enhancement is not a specific sign of
myocardial infarction of ischeminc heart disease. The differentiation of the
etiology of the delayed enhancement relies upon both the MR images and the
clinical history. BACKGROUND: Delayed enhancement (DE) on cardiac magnetic resoce imaging (CMR)
is a marker of myocardial fibrosis. The absence of DE in CMR is a predictor of
left ventricular (LV) functional improvement in patients with non-ischemic
cardiomyopathy (NICM), so in the present study it was investigated whether
presence of DE has prognostic significance in patients with NICM at long-term
follow-up.
METHODS AND RESULTS: The 79 patients (56.4+/-13.5 years, 48 males) with NICM (LV
ejection fraction <35%, no significant coronary artery disease) were monitored
for occurrence of cardiac events. CMR was performed to assess DE. Cardiac events
were defined as rehospitalization (because of worsening of heart failure),
cardiac transplantation or death. There were 37 patients without and 42 patients
with DE. The mean follow-up duration was 19+/-10 months. There was 1 event
(2.7%, 1 rehospitalization) in the DE (-) group, whereas 13 events (30.9%, 1
death, 1 transplantation, 11 rehospitalizations) occurred in the DE (+) group.
The event-free survival was significantly longer in the DE (-) group than in the
DE (+) group (38.9+/-1.0 vs 28.4+/-2.7 months, P<0.01). Multivariate regression
analysis revealed that presence of DE was the most potent, independent predictor
of cardiac events (hazard ratio 8.06, confidence interval 1.03+/-63.41, P<0.05).
CONCLUSIONS: The presence of DE in CMR is a significant predictor of future
cardiac events in patients with NICM. OBJECTIVES: We investigated the prognostic role of myocardial fibrosis by
delayed enhancement (DE) cardiovascular magnetic resoce (CMR) in nonischemic
dilated cardiomyopathy (NICM) patients with no or mild symptoms of heart failure
(HF).
METHODS: A prospective cohort of 125 NICM patients (82 males, age 59±14years,
mean±SD) with echocardiographic evidence of left ventricular (LV) systolic
dysfunction (mean ejection-fraction 33±10%), without (stage B) or with history
of mild HF symptoms (stage C, NYHA classes I-II) was enrolled. The end-point was
a composite of cardiac death and HF hospitalization.
RESULTS: Fifty (40%) patients showed myocardial DE, representing 12±7% of LV
mass. During a median follow-up of 14.2months, 16 (32%) patients with DE
experienced a composite event versus only 6 (8%) patients without DE
(Kaplan-Meier survival curve, p=0.001). After correction for age, CMR-derived LV
and right ventricular volumes, echocardiographic measurements of LV diastolic
function and Doppler-estimated systolic pulmonary artery pressure, the presence
of DE remained a strong and independent predictor of cardiac death or HF
hospitalization (hazard ratio: 5.32, 95% confidence intervals 1.60 to 17.63,
p=0.006).
CONCLUSIONS: In NICM patients with no or mild HF symptoms, the presence of
myocardial DE is a strong predictor of worse clinical outcome even after
correction for other established prognostic determits. Contrast-enhanced CMR
may be useful in prognostic stratification from the early stages of NICM. INTRODUCTION: Dilated cardiomyopathy (DCM) is associated with significant
morbidity and mortality. Contrast-enhanced cardiac MRI (CE-CMR) can detect
potentially prognostic myocardial fibrosis in DCM. We investigated the role of
CE-CMR in New Zealand patients with DCM, both Maori and non-Maori, including the
characteristics and prognostic importance of fibrosis.
METHODS: One hundred and three patients (mean age 58 ± 13, 78 male) referred for
CMR assessment of DCM were followed for 660 ± 346 days. Major adverse cardiac
events (MACE) were defined as death, infarction, ventricular arrhythmias or
rehospitalisation. CE-CMR used cines for functional analysis, and delayed
enhancement to assess fibrosis.
RESULTS: Myocardial fibrosis was present in 30% of patients, the majority of
which was mid-myocardial (63%). Volumetric parameters were similar in patients
with or without fibrosis. At 2 years patients with fibrosis had an increased
rate of MACE (HR = 0.77, 95% CI 0.3-2.0). Patients with full thickness or
subendocardial fibrosis had the highest MACE, even in the absence of CAD). More
Maori had fibrosis on CE-CMR (40% vs. 28% for non-Maori), and the majority (75%)
was mid-myocardial. Maori and non-Maori had similar outcomes (25% vs. 24% with
events during follow-up).
CONCLUSIONS: DCM patients frequently have myocardial fibrosis detected on
CE-CMR, the majority of which is mid-myocardial. Fibrosis is associated with
worse outcome in the medium term. The information obtained using CE-CMR in DCM
may be of incremental clinical benefit. BACKGROUND: We determined the relationship between fragmented QRS (fQRS) on
electrocardiograms (ECG) as well as myocardial fibrosis measured by delayed
enhancement of cardiac magnetic resoce imaging (DE-CMR) and its prognostic
implication in patients with non-ischemic dilated cardiomyopathy (DCM).
METHODS: The ECGs of 86 subjects with dilated non-ischemic DCM who underwent
DE-CMR were analyzed. DCM was defined as LV end-diastolic dimension >55 mm with
LVEF <45% and chronic symptomatic heart failure for ≥ 9 months. Cardiac events
(re-hospitalization due to heart failure, arrhythmic event, cardiac death) were
reviewed retrospectively. fQRS was defined by the presence of an additional R
wave (R"), or notching of the S wave, or the presence of more than one R prime
in two contiguous leads.
RESULTS: In 86 patients, fQRS developed in 53 patients (61.6%) and delayed
enhancement was observed in 42 patients (48.8%). The mean ejection fraction was
25.0%. Baseline characteristics were similar in both groups. Analyses of
echocardiographic parameters revealed left ventricular end-diastolic and
end-systolic dimensions were significantly higher in the fQRS group, but that
the left ventricular ejection fraction was not significantly different. The
prevalence of delayed enhancement between two groups was not significantly
different (50.9% in fQRS vs. 45.5% in the non-fQRS group; p=0.62). MACE-free
survival was significantly decreased in the fQRS group compared with the
non-fQRS group.
CONCLUSION: There was no spatial relationship between fQRS and DE-CMR in
patients with non-ischemic DCM. fQRS was associated with lower event-free
survival for major cardiac events on long-term follow-up. Myocardial fibrosis (MF) is a common pathophysiologic endpoint in non-ischemic
cardiomyopathy and may be identified by late gadolinium enhancement (LGE) MRI.
While associated with future cardiovascular events in hypertrophic
cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) the influence of MF on
interim quality of life (QOL) has not been explored. In this study we
investigate for associations between MF and validated indices of QOL in patients
with HCM and DCM. Ninety-eight patients with known cardiomyopathy (n = 56-HCM/n
= 42-DCM) underwent LGE-MRI in addition to standardized testing for QOL using
the disease-specific Minnesota Living With Heart Failure (MLWHF) and the generic
SF-12 questionnaires. LGE-MRI images were blindly analyzed for the presence and
volume of MF using validated techniques. All analyses were stratified according
to cardiomyopathy sub-type. The mean age of the population was 56.8 ± 12.9
years. MF was identified in 82 % of patients with HCM and 74 % of patients with
DCM with respective mean MF burdens of 20.0 and 13.7 % of the left ventricular
mass (p = 0.008). QOL scores for those with HCM or DCM, as assessed by both
MLWHF and SF-12, were not significantly different between those with versus
those without MF, and showed no association with MF burden by quantitative
signal analysis. In this study we identified no association between QOL and MF
burden by LGE-MRI in patients with HCM or DCM. Therefore, the severity of
underlying myocardial tissue disease, a recognized substrate for ventricular
arrhythmia, cannot and should not be inferred from the patient's symptom status
or QOL. OBJECTIVES: The aim of this study was to determine whether left ventricular (LV)
midwall fibrosis, detected by midwall hyperenhancement (MWHE) on late gadolinium
enhancement cardiovascular magnetic resoce (CMR) imaging, predicts mortality
and morbidity in patients with dilated cardiomyopathy (DCM) undergoing cardiac
resynchronization therapy (CRT).
BACKGROUND: Midwall fibrosis predicts mortality and morbidity in patients with
DCM.
METHODS: Patients with DCM with (+) or without (-) MWHE (n = 20 and n = 77,
respectively) as well as 161 patients with ischemic cardiomyopathy (ICM)
undergoing CRT (n = 258) were followed up for a maximum of 8.7 years.
RESULTS: Among patients with DCM, +MWHE predicted cardiovascular mortality
(hazard ratio [HR]: 18.6; 95% confidence intervals [CI]: 3.51 to 98.5; p =
0.0008), total mortality or hospitalization for major adverse cardiovascular
events (HR: 7.57; 95% CI: 2.71 to 21.2; p < 0.0001), and cardiovascular
mortality or heart failure hospitalizations (HR: 9.56; 95% CI: 2.72 to 33.6; p =
0.0004), independent of New York Heart Association class, QRS duration, atrial
fibrillation, LV volumes, LV ejection fraction, and a CMR-derived measure of
dyssynchrony. Among patients with DCM and ICM, the risk of cardiovascular
mortality for DCM +MWHE (adjusted HR: 18.5; 95% CI: 3.93 to 87.3; p = 0.0002)
was similar to that for ICM (adjusted HR: 21.0; 95% CI: 5.06 to 87.2; p <
0.0001). Both DCM +MWHE and ICM were predictors of pump failure death as well as
sudden cardiac death. LV reverse remodeling was observed in DCM -MWHE and in ICM
but not in DCM +MWHE.
CONCLUSIONS: Midwall fibrosis is an independent predictor of mortality and
morbidity in patients with DCM undergoing CRT. The outcome of DCM with midwall
fibrosis is similar to that of ICM. This relationship is mediated by both pump
failure and sudden cardiac death. BACKGROUND: The prognostic implications of late gadolinium enhancement (LGE)
have been evaluated in ischemic and non-ischemic cardiomyopathies. The present
study analyzed LGE distribution in patients with end-stage hypertrophic
cardiomyopathy (ES-HCM) and with dilated cardiomyopathy (DCM), and tried to
identify high risk patients in DCM.
METHODS: Eleven patients with ES-HCM and 72 with DCM underwent cine- and
LGE-cardiac magnetic resoce and ultrasound cardiography. The patient outcome
was analyzed retrospectively for 5years of follow-up.
RESULTS: LGE distributed mainly in the inter-ventricular septum, but spread more
diffusely into other left ventricular segments in patients with ES-HCM and in a
certain part of patients with DCM. Thus, patients with DCM can be divided into
three groups according to LGE distribution; no LGE (n=24), localized LGE
(localized at septum, n=36), and extensive LGE (spread into other segments,
n=12). Reverse remodeling occurred after treatment in patients with no LGE and
with localized LGE, but did not in patients with extensive LGE and with ES-HCM.
The event-free survival rate for composite outcome (cardiac death,
hospitalization for decompensated heart failure or ventricular arrhythmias) was
lowest in patients with extensive LGE (92%, 74% and 42% in no LGE, localized
LGE, and extensive LGE, p=0.02 vs. no LGE), and was comparable to that in
patients with ES-HCM (42%).
CONCLUSIONS: In DCM, patients with extensive LGE showed no functional recovery
and the lowest event-free survival rate that were comparable to patients with
ES-HCM. The analysis of LGE distribution may be valuable to predict reverse
remodeling and to identify high-risk patients. |
Which enzyme is inhibited by Varespladib? | Varespladib is a secretory phospholipase A2 (sPLA2) inhibitor. It was tested in patients with acute coronary syndrome. | Varespladib methyl is an oral secretory phospholipase A2 inhibitor that is being
developed by Anthera Pharmaceuticals Inc for the potential treatment of coronary
artery disease, acute coronary syndrome and inflammation. Varespladib methyl is
a prodrug that is rapidly metabolized to varespladib, and both compounds are
able to potently inhibit the enzymes of the human secretory phospholipase groups
IIa, V and X, which play a pivotal role in atherosclerotic disease and
inflammation. Phase II clinical trials of varespladib methyl in patients with
coronary artery disease, rheumatoid arthritis, asthma and ulcerative colitis
revealed that the drug was well tolerated. Varespladib methyl did not
demonstrate a good efficacy profile in patients with rheumatoid arthritis,
asthma and ulcerative colitis, whereas in patients with coronary artery disease,
varespladib methyl consistently reduced LDL-cholesterol levels (elevated
LDL-cholesterol levels are a marker of increased cardiovascular risk). At the
time of publication, phase II trials were ongoing in patients with acute
coronary syndrome and in patients undergoing elective percutaneous coronary
intervention, and a phase III trial in patients with acute coronary syndrome was
planned. Varespladib methyl could represent a novel therapy for the treatment of
cardiovascular disease, although the efficacy, safety profile and advantages of
this drug compared with existing therapeutic options would need to be
established in upcoming phase III trials. OBJECTIVE: Several secreted phospholipases A2 (sPLA2s), including group IIA,
III, V, and X, have been linked to the development of atherosclerosis, which led
to the clinical testing of A-002 (varespladib), a broad sPLA2 inhibitor for the
treatment of coronary artery disease. Group X sPLA2 (PLA2G10) has the most
potent hydrolyzing activity toward phosphatidylcholine and is believed to play a
proatherogenic role.
METHODS AND RESULTS: Here, we show that Ldlr(-/-) mice reconstituted with bone
marrow from mouse group X-deficient mice (Pla2g10(-/-)) unexpectedly display a
doubling of plaque size compared with Pla2g10(+/+) chimeric mice. Macrophages of
Pla2g10(-/-) mice are more susceptible to apoptosis in vitro, which is
associated with a 4-fold increase of plaque necrotic core in vivo. In addition,
chimeric Pla2g10(-/-) mice show exaggerated T lymphocyte (Th)1 immune response,
associated with enhanced T-cell infiltration in atherosclerotic plaques.
Interestingly, overexpression of human PLA2G10 in murine bone marrow cells leads
to significant reduction of Th1 response and to 50% reduction of lesion size.
CONCLUSIONS: PLA2G10 expression in bone marrow cells controls a proatherogenic
Th1 response and limits the development of atherosclerosis. The results may
provide an explanation for the recently reported inefficacy of A-002
(varespladib) to treat patients with coronary artery disease. Indeed, A-002 is a
nonselective sPLA2 inhibitor that inhibits both proatherogenic (groups IIA and
V) and antiatherogenic (group X) sPLA2s. Our results suggest that selective
targeting of individual sPLA2 enzymes may be a better strategy to treat
cardiovascular diseases. The VISTA-16 trial of varespladib, a secretory phospholipase A2 (sPLA2)
inhibitor, in patients with an acute coronary syndrome was terminated
prematurely owing to futility and a signal towards harm. Despite these
discouraging results, therapies that target inflammation to modify pathways in
atherogenesis remain an area of active investigation. Atherothrombosis is no longer considered solely a disorder of lipoprotein
accumulation in the arterial wall. Rather, the initiation and progression of
atherosclerotic lesions is currently understood to have major inflammatory
influences that encompass components of both the innate and acquired immune
systems. Promising clinical data for 'upstream' biomarkers of inflammation such
as interleukin-6 (IL-6) as well as 'downstream' biomarkers such as C-reactive
protein, observations regarding cholesterol crystals as an activator of the
IL-1β generating inflammasome, and recent Mendelian randomization data for the
IL-6 receptor support the hypothesis that inflammatory mediators of
atherosclerosis may converge on the central IL-1, tumour necrosis factor
(TNF-α), IL-6 signalling pathway. On this basis, emerging anti-inflammatory
approaches to vascular protection can be categorized into two broad groups,
those that target the central IL-6 inflammatory signalling pathway and those
that do not. Large-scale Phase III trials are now underway with agents that lead
to marked reductions in IL-6 and C-reactive protein (such as canakinumab and
methotrexate) as well as with agents that impact on diverse non-IL-6-dependent
pathways (such as varespladib and darapladib). Both approaches have the
potential to benefit patients and reduce vascular events. However, care should
be taken when interpreting these trials as outcomes for agents that target IL-6
signalling are unlikely to be informative for therapies that target alternative
pathways, and vice versa. As the inflammatory system is redundant, compensatory,
and crucial for survival, evaluation of risks as well as benefits must drive the
development of agents in this class. |
Which protein does empagliflozin inhibit? | Empagliflozin (Jardiance) is a SGLT2 inhibitor. | This randomized, placebo-controlled within dose groups, double-blind, single
rising dose study investigated the safety, tolerability, pharmacokinetics and
pharmacodynamics of 1 mg to 100 mg doses of empagliflozin in 48 healthy Japanese
male subjects. Empagliflozin was rapidly absorbed, reaching peak levels in 1.25
to 2.50 h; thereafter, plasma concentrations declined in a biphasic fashion,
with mean terminal elimination half-life ranging from 7.76 to 11.7 h. Increase
in empagliflozin exposure was proportional to dose. Oral clearance was dose
independent and ranged from 140 to 172 mL/min. In the 24 h following 100 mg
empagliflozin administration, the mean (%CV) amount of glucose excreted in urine
was 74.3 (17.1) g. The amount and the maximum rate of glucose excreted via urine
increased with dose of empagliflozin. Nine adverse events, all of mild
intensity, were reported by 8 subjects (7 with empagliflozin and 1 with the
placebo). No hypoglycemia was reported. In conclusion, 1 mg to 100 mg doses of
empagliflozin had a good safety and tolerability profile in healthy Japanese
male subjects. Exposure to empagliflozin was dose proportional. The amount and
rate of urinary glucose excretion were higher with empagliflozin than with the
placebo, and increased with empagliflozin dose. OBJECTIVE: This open-label study investigated potential drug-drug interactions
between empagliflozin and metformin.
METHODS: 16 healthy men received treatment A (empagliflozin 50 mg q.d. for 5
days), treatment B (empagliflozin 50 mg q.d. for 4 days with metformin 1,000 mg
b.i.d. for 3 days and 1,000 mg q.d. on Day 4) and treatment C (metformin 1,000
mg b.i.d. for 3 days and 1,000 mg q.d .on Day 4) in the sequence AB then C, or C
then AB.
RESULTS: Metformin had no clinically relevant effect on the area under the
steady state plasma concentration-time curve (AUC(τ,ss) geometric mean ratio
(GMR): 96.9; 90% CI: 92.3 - 101.7) or the maximum plasma concentration at steady
state (C(max,ss) GMR: 100.5; 90% CI: 88.8 - 113.7) of empagliflozin. Similarly,
empagliflozin had no clinically relevant effect on AUC(τ,ss) (GMR: 100.7; 90%
CI: 95.9 - 105.6) or C(max,ss) (GMR: 103.6; 90% CI: 96.5 - 111.2) of metformin.
The renal clearance of empagliflozin and metformin were unaffected by
co-administration. Both drugs were well tolerated alone and in combination and
did not cause hypoglycemia.
CONCLUSIONS: These data support co-administration of empagliflozin and metformin
without dose adjustment. Sodium/glucose cotransporter 2 (SGLT2) inhibitors are oral hypoglycemic agents
used to treat patients with diabetes mellitus. SGLT2 inhibitors block
reabsorption of filtered glucose by inhibiting SGLT2, the primary glucose
transporter in the proximal tubular cell (PTC), leading to glycosuria and
lowering of serum glucose. We examined the renoprotective effects of the SGLT2
inhibitor empagliflozin to determine whether blocking glucose entry into the
kidney PTCs reduced the inflammatory and fibrotic responses of the cell to high
glucose. We used an in vitro model of human PTCs. HK2 cells (human kidney PTC
line) were exposed to control 5 mM, high glucose (HG) 30 mM or the profibrotic
cytokine transforming growth factor beta (TGFβ1; 0.5 ng/ml) in the presence and
absence of empagliflozin for up to 72 h. SGLT1 and 2 expression and various
inflammatory/fibrotic markers were assessed. A chromatin immunoprecipitation
assay was used to determine the binding of phosphorylated smad3 to the promoter
region of the SGLT2 gene. Our data showed that TGFβ1 but not HG increased SGLT2
expression and this occurred via phosphorylated smad3. HG induced expression of
Toll-like receptor-4, increased nuclear deoxyribonucleic acid binding for
nuclear factor kappa B (NF-κB) and activator protein 1, induced collagen IV
expression as well as interleukin-6 secretion all of which were attenuated with
empagliflozin. Empagliflozin did not reduce high mobility group box protein 1
induced NF-κB suggesting that its effect is specifically related to a reduction
in glycotoxicity. SGLT1 and GLUT2 expression was not significantly altered with
HG or empagliflozin. In conclusion, empagliflozin reduces HG induced
inflammatory and fibrotic markers by blocking glucose transport and did not
induce a compensatory increase in SGLT1/GLUT2 expression. Although HG itself
does not regulate SGLT2 expression in our model, TGFβ increases SGLT2 expression
through phosphorylated smad3. AIM: This Phase IIb, randomized, double-blind, placebo-controlled trial
evaluated the efficacy, safety, tolerability and pharmacokinetics of
empagliflozin in patients with type 2 diabetes.
METHODS: Four hundred and eight patients (treatment-naïve or after a 4-week
wash-out period) were randomized to receive empagliflozin 5, 10 or 25 mg once
daily, placebo or open-label metformin for 12 weeks. The primary endpoint was
change in haemoglobin A1c (HbA1c) after 12 weeks.
RESULTS: After 12 weeks' treatment, empagliflozin showed dose-dependent
reductions in HbA1c from baseline [5 mg: -0.4%, 10 mg: -0.5%, 25 mg: -0.6%; all
doses p < 0.0001 vs. placebo (+0.09%)]. Fasting plasma glucose (FPG) decreased
with empagliflozin [5 mg: -1.29 mmol/l, 10 mg: -1.61 mmol/l, 25 mg:
-1.72 mmol/l; all doses p < 0.0001 vs. placebo (+0.04 mmol/l)]. Body weight
decreased in all empagliflozin groups (all doses p < 0.001 vs. placebo). The
incidence of adverse events (AEs) was similar in the placebo (32.9%) and
empagliflozin (29.1%) groups. The most frequently reported AEs on empagliflozin
were pollakiuria (3.3% vs. 0% for placebo), thirst (3.3% vs. 0% for placebo) and
nasopharyngitis (2.0% vs. 1.2% for placebo). AEs consistent with urinary tract
infections (UTIs) were reported in four (1.6%) patients on empagliflozin vs. one
(1.2%) on placebo. Genital infections were reported in five (2%) patients on
empagliflozin vs. 0% on placebo. No UTIs or genital infections led to premature
discontinuation.
CONCLUSIONS: In patients with type 2 diabetes, empagliflozin resulted in
dose-dependent, clinically meaningful reductions in HbA1c and FPG, and
reductions in body weight compared with placebo. Empagliflozin was
well-tolerated with a favourable safety profile. BACKGROUND: Empagliflozin is a sodium glucose cotransporter 2 inhibitor in
clinical development as a treatment for type 2 diabetes mellitus.
OBJECTIVE: The goal of this study was to investigate potential drug-drug
interactions between empagliflozin and verapamil, ramipril, and digoxin in
healthy volunteers.
METHODS: The potential drug-drug interactions were evaluated in 3 separate
trials. In the first study, 16 subjects were randomized to receive single-dose
empagliflozin 25 mg alone or single-dose empagliflozin 25 mg with single-dose
verapamil 120 mg. In the second study, 23 subjects were randomized to receive
empagliflozin 25 mg once daily (QD) for 5 days, ramipril (2.5 mg on day 1 then 5
mg QD on days 2-5) for 5 days or empagliflozin 25 mg with ramipril (2.5 mg on
day 1 then 5 mg QD on days 2-5) for 5 days. In the third study, 20 subjects were
randomized to receive single-dose digoxin 0.5 mg alone or empagliflozin 25 mg QD
for 8 days with single-dose digoxin 0.5 mg on day 5.
RESULTS: Exposure of empagliflozin was not affected by coadministration with
verapamil (AUC0-∞: geometric mean ratio [GMR], 102.95%; 90% CI, 98.87-107.20;
Cmax: GMR, 92.39%; 90% CI, 85.38-99.97) or ramipril (AUC over a uniform dosing
interval τ at steady state [AUCτ,ss]: GMR, 96.55%; 90% CI, 93.05-100.18; Cmax at
steady state [Cmax,ss]: GMR, 104.47%; 90% CI 97.65-111.77). Empagliflozin had no
clinically relevant effect on exposure of ramipril (AUCτ,ss: GMR, 108.14%; 90%
CI 100.51-116.35; Cmax,ss: GMR, 103.61%; 90% CI, 89.73-119.64) or its active
metabolite ramiprilat (AUCτ,ss: GMR, 98.67%; 90% CI, 96.00-101.42; Cmax,ss: GMR,
98.29%; 90% CI, 92.67-104.25). Coadministration of empagliflozin had no
clinically meaningful effect on digoxin AUC0-∞ (GMR, 106.11%; 90% CI,
96.71-116.41); however, a slight increase in Cmax was observed that was not
considered clinically relevant (GMR, 113.94%; 90% CI, 99.33-130.70). All
treatments were well tolerated. There were no serious adverse events or adverse
events leading to discontinuation in any of the studies.
CONCLUSIONS: No dose adjustment of empagliflozin is required when coadministered
with ramipril or verapamil, and no dose adjustment of digoxin or ramipril is
required when coadministered with empagliflozin. ClinicalTrials.gov identifiers:
NCT01306175 (digoxin), NCT01276301 (verapamil), and NCT01284621 (ramipril). AIMS: Empagliflozin is a selective sodium glucose cotransporter 2 (SGLT2)
inhibitor that inhibits renal glucose reabsorption and is being investigated for
the treatment of type 2 diabetes mellitus (T2DM).
METHODS: In this open-label study, the effect of renal impairment on the
pharmacokinetics, pharmacodynamics and safety of a 50 mg dose of empagliflozin
was investigated in 40 subjects, grouped according to estimated glomerular
filtration rate (eGFR).
RESULTS: Maximum empagliflozin plasma concentrations were similar in subjects
with normal renal function and renal impairment. Area under the empagliflozin
concentration-time curve (AUC0 -∞ ) values increased by approximately 18, 20, 66
and 48% in subjects with mild, moderate, severe renal impairment and renal
failure/end stage renal disease (ESRD), respectively, in comparison to healthy
subjects. This was attributed to decreased renal clearance (CLR ). Urinary
glucose excretion (UGE) decreased with increasing renal impairment and
correlated with decreased eGFR and CLR . Empagliflozin was well tolerated, with
no increase in adverse events associated with renal impairment.
CONCLUSIONS: Renal insufficiency resulted in decreased CLR of empagliflozin,
moderately increased systemic exposure and decreased UGE. A single 50 mg dose of
empagliflozin was well tolerated in subjects with normal renal function and any
degree of renal impairment. The pharmacokinetic results of this study indicate
that no dose adjustment of empagliflozin is required in patients with renal
impairment. AIMS: This open-label, parallel-group study investigated the effect of various
degrees of hepatic impairment on the pharmacokinetics, safety and tolerability
of the sodium glucose cotransporter 2 inhibitor empagliflozin.
METHODS: Thirty-six subjects [8 each with mild, moderate or severe hepatic
impairment (Child-Pugh classification), and 12 matched controls with normal
hepatic function] received a single 50 mg dose of empagliflozin.
RESULTS: Empagliflozin was rapidly absorbed. After reaching peak levels, plasma
drug concentrations declined in a biphasic fashion. Compared with subjects with
normal hepatic function, geometric mean ratios (90% confidence interval) of
AUC(0-∞) and C(max) were 123.15% (98.89-153.36) and 103.81% (82.29-130.95),
respectively, in patients with mild hepatic impairment, 146.97% (118.02-183.02)
and 123.31% (97.74-155.55), respectively, in patients with moderate hepatic
impairment, and 174.70% (140.29-217.55) and 148.41% (117.65-187.23),
respectively, in patients with severe hepatic impairment. Adverse events, all
mild or moderate in intensity, were reported in three subjects with moderate
hepatic impairment, two subjects with severe hepatic impairment and six subjects
with normal hepatic function.
CONCLUSIONS: Empagliflozin was well tolerated in subjects with hepatic
impairment. Increases in empagliflozin exposure were less than twofold in
patients with hepatic impairment; therefore no dose adjustment of empagliflozin
is required in patients with hepatic impairment. AIMS: To evaluate the effects of the sodium glucose cotransporter 2 (SGLT2)
inhibitor empagliflozin added to metformin for 12 weeks in patients with type 2
diabetes.
METHODS: This dose-ranging, double-blind, placebo-controlled trial randomized
495 participants with type 2 diabetes inadequately controlled on metformin
[haemoglobin A1c (HbA1c) >7 to ≤10%] to receive 1, 5, 10, 25, or 50 mg
empagliflozin once daily (QD), or placebo, or open-label sitagliptin (100 mg
QD), added to metformin for 12 weeks. The primary endpoint was change in HbA1c
from baseline to week 12 (empagliflozin groups versus placebo).
RESULTS: Reductions in HbA1c of -0.09 to -0.56% were observed with empagliflozin
after 12 weeks, versus an increase of 0.15% with placebo (baseline: 7.8-8.1%).
Compared with placebo, empagliflozin doses from 5 to 50 mg resulted in
reductions in fasting plasma glucose (-2 to -28 mg/dl vs. 5 mg/dl with placebo;
p < 0.0001) and body weight (-2.3 to -2.9 kg vs. -1.2 kg; p < 0.01). Frequency
of adverse events was generally similar with empagliflozin (29.6-48.6%), placebo
(36.6%) and sitagliptin (35.2%). Hypoglycaemia rates were very low and balanced
among groups. Most frequent adverse events with empagliflozin were urinary tract
infections (4.0% vs. 2.8% with placebo) and pollakiuria (2.5% vs. 1.4% with
placebo). Genital infections were reported only with empagliflozin (4.0%).
CONCLUSIONS: Once daily empagliflozin as add-on therapy to metformin was well
tolerated except for increased genital infections and resulted in reductions in
HbA1c, fasting plasma glucose and body weight in patients with type 2 diabetes
inadequately controlled on metformin monotherapy. Data from five randomized, placebo-controlled, multiple oral dose studies of
empagliflozin in patients with type 2 diabetes mellitus (T2DM; N = 974; 1-100 mg
q.d.; ≤12 weeks) were used to develop a population pharmacokinetic (PK) model
for empagliflozin. The model consisted of two-compartmental disposition, lagged
first-order absorption and first-order elimination, and incorporated appropriate
covariates. Population estimates (interindividual variance, CV%) of oral
apparent clearance, central and peripheral volumes of distribution, and
inter-compartmental clearance were 9.87 L/h (26.9%), 3.02 L, 60.4 L (30.8%), and
5.16 L/h, respectively. An imposed allometric weight effect was the most
influential PK covariate effect, with a maximum effect on exposure of ±30%,
using 2.5th and 97.5th percentiles of observed weights, relative to the median
observed weight. Sex and race did not lend additional description to PK
variability beyond allometric weight effects, other than ∼25% greater oral
absorption rate constant for Asian patients. Age, total protein, and
smoking/alcohol history did not affect PK parameters. Predictive check plots
were consistent with observed data, implying an adequate description of
empagliflozin PKs following multiple dosing in patients with T2DM. The lack of
marked covariate effects, including weight, suggests that no exposure-based dose
adjustments were required within the study population and dose range. BACKGROUND: Sulfonylureas (SUs) are commonly used in the treatment of type 2
diabetes (T2DM), usually as second-line treatment after the failure of
metformin. However, SUs are associated with poor durability, hypoglycemia and
weight gain. Empagliflozin is a sodium glucose cotransporter 2 (SGLT2) inhibitor
in development for the treatment of T2DM. In Phase II/III trials, empagliflozin
reduced hyperglycemia, body weight and blood pressure, with a low incidence of
hypoglycemia. The aim of this Phase III study is to compare the effects of
empagliflozin and the SU glimepiride as second-line therapy in patients with
T2DM inadequately controlled with metformin immediate release (IR) and
diet/exercise.
METHOD: After a 2-week placebo run-in, patients were randomized to receive
empagliflozin 25 mg once daily (qd) or glimepiride 1-4 mg qd double-blind for 2
years, in addition to metformin IR. Patients who participate in the initial
2-year randomization period will be eligible for a 2-year double-blind
extension. The primary endpoint is change from baseline in HbA1c. Secondary
endpoints are change from baseline in body weight, the incidence of confirmed
hypoglycemia and changes in systolic and diastolic blood pressure. Exploratory
endpoints include markers of insulin secretion, body composition and responder
analyses. Safety endpoints include the incidence of adverse events (AEs)
(including macro- and microvascular adverse events) and changes from baseline in
clinical laboratory parameters.
RESULTS: Between August 2010 and June 2011, 1549 patients were randomized and
1545 patients were treated. At baseline, mean (SD) age was 55.9 (10.4) years,
HbA1c was 7.92 (0.84)%, body mass index was 30.11 (5.59) kg/m², systolic blood
pressure was 133.5 (15.9) mmHg and diastolic blood pressure was 79.5 (9.4) mmHg.
DISCUSSION: This is the largest study to compare the efficacy and safety of an
SGLT2 inhibitor with an SU in patients with T2DM inadequately controlled on
metformin to date. In addition to determining the effects of these treatments on
glycemic control over the long term, this study will investigate effects on
beta-cell function, cardiovascular risk factors and markers of renal
function/damage. The results will help to inform the choice of second-line
treatment in patients with T2DM who have failed on metformin.
TRIAL REGISTRATION: Clinicaltrials.gov NCT01167881. OBJECTIVES: Empagliflozin is an orally available, potent and highly selective
inhibitor of the sodium glucose cotransporter 2 (SGLT2). This study was
undertaken to investigate the effect of food on the pharmacokinetics of 25 mg
empagliflozin and to assess dose proportionality between 10 mg and 25 mg
empagliflozin under fasted conditions.
MATERIALS AND METHODS: In this open-label, 3-way, cross-over study, 18 healthy
volunteers received 3 single doses of empagliflozin in a randomized sequence (25
mg empagliflozin under fasted conditions, 25 mg empagliflozin after a high-fat,
high-calorie breakfast and 10 mg empagliflozin under fasted conditions), each
separated by a washout period of at least 7 days. Serial plasma samples were
collected at selected time points over a period of 72 hours.
RESULTS: Administration with food had no clinically relevant effect on the area
under the plasma concentration-time curve (AUC0-∞) of empagliflozin (geometric
mean ratio (GMR): 84.04, 90% confidence interval (CI): 80.86 - 87.34). The
decrease observed in the maximum plasma concentrations (Cmax) of empagliflozin
(GMR: 63.22, 90% CI: 56.74 - 70.44) when administered with food was not
considered clinically meaningful. The increases in AUC0-∞ and Cmax for 10 mg vs.
25 mg empagliflozin administered under fasting conditions were roughly
dose-proportional, as demonstrated by the slope β of the regression lines being
slightly less than 1 (slope β for AUC0-∞: 0.94, 95% CI: 0.90 - 0.97; slope β for
Cmax: 0.91, 95% CI: 0.80 - 1.01). Empagliflozin was well tolerated under fed and
fasting conditions.
CONCLUSIONS: The results support administration of empagliflozin tablets
independently of food. Increases in empagliflozin exposure under fasting
conditions were roughly dose-proportional between 10 mg and 25 mg empagliflozin. BACKGROUND: Sodium-glucose cotransporter 2 (SGLT2) inhibitors lower glycemia by
enhancing urinary glucose excretion. The physiologic response to
pharmacologically induced acute or chronic glycosuria has not been investigated
in human diabetes.
METHODS: We evaluated 66 patients with type 2 diabetes (62 ± 7 years, BMI = 31.6
± 4.6 kg/m(2), HbA1c = 55 ± 8 mmol/mol, mean ± SD) at baseline, after a single
dose, and following 4-week treatment with empagliflozin (25 mg). At each time
point, patients received a mixed meal coupled with dual-tracer glucose
administration and indirect calorimetry.
RESULTS: Both single-dose and chronic empagliflozin treatment caused glycosuria
during fasting (median, 7.8 [interquartile range {IQR}, 4.4] g/3 hours and 9.2
[IQR, 5.2] g/3 hours) and after meal ingestion (median, 29.0 [IQR, 12.5] g/5
hours and 28.2 [IQR, 15.4] g/5 hours). After 3 hours of fasting, endogenous
glucose production (EGP) was increased 25%, while glycemia was 0.9 ± 0.7 mmol/l
lower (P < 0.0001 vs. baseline). After meal ingestion, glucose and insulin AUC
decreased, whereas the glucagon response increased (all P < 0.001). While oral
glucose appearance was unchanged, EGP was increased (median, 40 [IQR, 14] g and
37 [IQR, 11] g vs. 34 [IQR, 11] g, both P < 0.01). Tissue glucose disposal was
reduced (median, 75 [IQR, 16] g and 70 [IQR, 21] g vs. 93 [IQR, 18] g, P <
0.0001), due to a decrease in both glucose oxidation and nonoxidative glucose
disposal, with a concomitant rise in lipid oxidation after chronic
administration (all P < 0.01). β Cell glucose sensitivity increased (median, 55
[IQR, 35] pmol • min(-1) • m(-2) • mM(-1) and 55 [IQR, 39] pmol • min(-1) •
m(-2) • mM(-1) vs. 44 [IQR, 32] pmol • min(-1) • m(-2) • mM(-1), P < 0.0001),
and insulin sensitivity was improved. Resting energy expenditure rates and those
after meal ingestion were unchanged.
CONCLUSIONS: In patients with type 2 diabetes, empagliflozin-induced glycosuria
improved β cell function and insulin sensitivity, despite the fall in insulin
secretion and tissue glucose disposal and the rise in EGP after one dose,
thereby lowering fasting and postprandial glycemia. Chronic dosing shifted
substrate utilization from carbohydrate to lipid. Trial registration.
ClinicalTrials.Gov NCT01248364 (EudraCT no. 2010-018708-99). Funding. This study
was funded by Boehringer Ingelheim. Diabetic nephropathy is the leading cause of end-stage renal disease in humans
in the Western world. The recent development of Na+-glucose cotransporter 2
(SGLT2) inhibitors offers a new antidiabetic therapy via enhanced glucose
excretion. Whether this strategy exerts beneficial effects on the development of
type 2 diabetic nephropathy is still largely unclear. We investigated the
effects of the specific SGLT2 inhibitor empagliflozin in BTBR.Cg-Lep<ob>/WiscJ
(BTBR ob/ob) mice, which spontaneously develop type 2 diabetic nephropathy. In
the first experiment, BTBR ob/ob mice received either a diet containing 300 ppm
empagliflozin or equicaloric placebo chow for 12 wk. In the second experiment,
BTBR ob/ob mice received 1 μg·kg body wt(-1)·day(-1) ANG II to induce arterial
hypertension and were separated into the same two diet groups for 6 wk. In both
experiments, empagliflozin treatment enhanced glucosuria, thereby lowering blood
glucose. Independently of hypertension, empagliflozin reduced albuminuria in
diabetic mice. However, empagliflozin treatment affected diabetes-related
glomerular hypertrophy, markers of renal inflammation, and mesangial matrix
expansion only in BTBR ob/ob mice without hypertension. In summary,
empagliflozin demonstrated significant antihyperglycemic effects, differentially
ameliorating early features of diabetic nephropathy in BTBR ob/ob mice with and
without hypertension. AIMS: To provide model-based clinical development decision support including
dose selection guidance for empagliflozin, an orally administered sodium glucose
cotransporter 2 inhibitor, through developed exposure-response (E-R) models for
efficacy and tolerability in patients with type 2 diabetes mellitus (T2DM).
METHODS: Five randomized, placebo-controlled, multiple oral dose studies of
empagliflozin in patients with T2DM (n = 974; 1-100 mg once daily, duration ≤12
weeks) were used to develop E-R models for efficacy (glycosylated haemoglobin
[HbA1c ], fasting plasma glucose [FPG] and urinary glucose excretion). Two
studies (n = 748, 12 weeks) were used to evaluate tolerability E-R.
RESULTS: The efficacy model predicted maximal decreases in FPG and HbA1c of 16%
and 0.6%, respectively, assuming a baseline FPG concentration of 8 mm
(144 mg dl(-1) ) and 10-25 mg every day empagliflozin targeted 80-90% of these
maximums. Increases in exposure had no effect on incidence rates of
hypoglycaemia (n = 4), urinary tract infection (n = 17) or
genital/vulvovaginal-related (n = 16) events, although low prevalence rates may
have precluded more accurate evaluation.
CONCLUSIONS: E-R analyses indicated that 10 and 25 mg once daily empagliflozin
doses achieved near maximal glucose lowering efficacy. Type 2 diabetes is characterized by impaired β-cell function associated with
progressive reduction of insulin secretion and β-cell mass. Evidently, there is
an unmet need for treatments with greater sustainability in β-cell protection
and antidiabetic efficacy. Through an insulin and β cell-independent mechanism,
empagliflozin, a specific sodium glucose cotransporter type 2 (SGLT-2)
inhibitor, may potentially provide longer efficacy. This study compared the
antidiabetic durability of empagliflozin treatment (10 mg/kg p.o.) against
glibenclamide (3 mg/kg p.o.) and liraglutide (0.2 mg/kg s.c.) on deficient
glucose homeostasis and β-cell function in Zucker diabetic fatty (ZDF) rats.
Empagliflozin and liraglutide led to marked improvements in fed glucose and
hemoglobin A1c levels, as well as impeding a progressive decline in insulin
levels. In contrast, glibenclamide was ineffective. Whereas the effects of
liraglutide were less pronounced at week 8 of treatment compared with week 4,
those of empagliflozin remained stable throughout the study period. Similarly,
empagliflozin improved glucose tolerance and preserved insulin secretion after
both 4 and 8 weeks of treatment. These effects were reflected by less reduction
in β-cell mass with empagliflozin or liraglutide at week 4, whereas only
empagliflozin showed β-cell sparing effects also at week 8. Although this study
cannot be used to dissociate the absolute antidiabetic efficacy among the
different mechanisms of drug action, the study demonstrates that empagliflozin
exerts a more sustained improvement of glucose homeostasis and β-cell protection
in the ZDF rat. In comparison with other type 2 diabetic treatments, SGLT-2
inhibitors may through insulin-independent pathways thus enhance durability of
β-cell protection and antidiabetic efficacy. INTRODUCTION: Despite the availability of numerous anti-diabetes drugs and
treatment guidelines, many patients with type 2 diabetes mellitus (T2DM) do not
reach recommended targets for glycemic control. There remains an unmet need for
effective and well-tolerated anti-diabetes agents that can be used as
monotherapy or in combination with other therapies to improve glycemic control
in patients with T2DM. Sodium glucose cotransporter 2 (SGLT2) inhibitors are a
new class of treatment for T2DM that reduce hyperglycemia by reducing renal
glucose reabsorption and thereby increasing urinary glucose excretion.
AREAS COVERED: This paper reviews the pharmacokinetic and pharmacodynamic
properties of the SGLT2 inhibitor empagliflozin , the results of clinical trials
investigating the efficacy of empagliflozin given as monotherapy or as add-on
therapy on glycemic control, body weight, and blood pressure in patients with
T2DM, and the safety and tolerability profile of empagliflozin.
EXPERT OPINION: Empagliflozin offers good glycemic efficacy, weight loss, blood
pressure reduction, and a low risk of hypoglycemia. These attributes, coupled
with the ability to be used in virtually any combination with other
anti-diabetes agents and at any stage in the disease process, provide a welcome
new agent to our armamentarium of drugs to help manage T2DM. BACKGROUND AND OBJECTIVE: Sodium glucose cotransporter 2 (SGLT2) is the main
luminal glucose transporter in the kidney. SGLT2 inhibition results in
glycosuria and improved glycaemic control. Drugs inhibiting this transporter
have recently been approved for clinical use and have been suggested to have
potential renoprotective benefits by limiting glycotoxicity in the proximal
tubule. We aimed to determine the renoprotective benefits of empagliflozin, an
SGLT2 inhibitor, independent of its glucose lowering effect.
RESEARCH DESIGN AND METHODS: We induced diabetes using a low dose streptozotocin
protocol in 7-8 week old endothelial nitric oxide (eNOS) synthase knockout mice.
We measured fasting blood glucose on a monthly basis, terminal urinary
albumin/creatinine ratio. Renal histology was assessed for inflammatory and
fibrotic changes. Renal cortical mRNA transcription of inflammatory and
profibrotic cytokines, glucose transporters and protein expression of SGLT2 and
GLUT1 were determined. Outcomes were compared to diabetic animals receiving the
angiotensin receptor blocker telmisartan (current best practice).
RESULTS: Diabetic mice had high matched blood glucose levels. Empagliflozin did
not attenuate diabetes-induced albuminuria, unlike telmisartan. Empagliflozin
did not improve glomerulosclerosis, tubular atrophy, tubulointerstitial
inflammation or fibrosis, while telmisartan attenuated these. Empagliflozin did
not modify tubular toll-like receptor-2 expression in diabetic mice.
Empagliflozin did not reduce the upregulation of macrophage chemoattractant
protein-1 (MCP-1), transforming growth factor β1 and fibronectin mRNA observed
in the diabetic animals, while telmisartan decreased transcription of MCP-1 and
fibronectin. Empagliflozin increased GLUT1 mRNA expression and telmisartan
increased SGLT2 mRNA expression in comparison to untreated diabetic mice.
However no significant difference was found in protein expression of GLUT1 or
SGLT2 among the different groups.
CONCLUSION: Hence SGLT2 inhibition does not have renoprotective benefits
independent of glucose lowering. 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. BACKGROUND: Treatment of type 2 diabetes mellitus invariably requires the use of
multiple daily medications which can impact negatively on patient adherence. As
a result, there is growing interest in the use of single-pill combinations that
can reduce the pill burden. Many such formulations incorporate metformin,
although this agent is not suitable for all patients. The single-pill
combination of the dipeptidyl peptidase-4 inhibitor linagliptin with the sodium
glucose co-transporter 2 inhibitor empagliflozin offers a new and attractive
option, given their complementary mechanisms of action.
SCOPE: Publications with titles containing the keywords 'linagliptin' or
'empagliflozin' were identified from a non-systematic search of PubMed without
date restrictions, together with abstracts presented at the annual meetings of
the American Diabetes Association and the European Association for the Study of
Diabetes 2012-2014. ClinicalTrials.gov was searched for entries containing these
two keywords. Additional references known to the author were included.
FINDINGS: The efficacy and safety of linagliptin and empagliflozin as
monotherapy or in combination with other oral antidiabetic drugs has been
established through extensive clinical trial programs. Studies specifically
evaluating the efficacy/safety of a dipeptidyl peptidase-4 inhibitor/sodium
glucose co-transporter 2 inhibitor in combination are limited, but do include
two studies of linagliptin/empagliflozin of up to 52 weeks in duration. These
studies show that the single-pill combination of linagliptin and empagliflozin
produced clinical improvements in glycemic control that were generally superior
to the improvements seen with linagliptin and empagliflozin alone, but with a
safety profile comparable to that of the individual constituents.
CONCLUSIONS: The single-pill combination of linagliptin and empagliflozin, with
their complementary mechanisms of action, is a promising treatment option for
patients with type 2 diabetes mellitus. It would reduce the daily pill burden in
this population, potentially improving adherence to, and optimizing the benefits
of, treatment of diabetes mellitus. |
What symptoms characterize the Muenke syndrome? | Muenke syndrome is an autosomal dominant disorder characterized by coronal suture craniosynostosis, hearing loss, developmental delay, carpal and tarsal fusions, and the presence of the Pro250Arg mutation in the FGFR3 gene. Muenke syndrome is characterized by coronal craniosynostosis (bilateral more often than unilateral), hearing loss, developmental delay, and carpal and/or tarsal bone coalition. Tarsal coalition is a distinct feature of Muenke syndrome and has been reported since the initial description of the disorder in the 1990s. | BACKGROUND: Muenke syndrome is a genetically determined craniosynostosis that
involves one or both coronal sutures. In some patients it is associated with
skeletal abnormalities such as thimble-like middle phalanges, coned epiphysis,
and/or neurological impairment, namely sensorineural hearing loss or mental
retardation. In spite of a variable phenotype, Muenke syndrome has been related
to a unique mutation on the FGFR3 gene, Pro 250 to Arg, which is characteristic
of this disease. Because of the incomplete penetrance of this anomaly, the
suspicion of Muenke syndrome must be raised in any child with uni- or bilateral
coronal craniosynostosis, and the genetic analysis propounded even in the
absence of extracranial features.
ILLUSTRATIVE CASES: We report the cases of two sisters who presented with Muenke
syndrome and whose affected mother did not have any form of craniosynostosis. Muenke syndrome is an autosomal domit disorder characterized by coronal
suture craniosynostosis, hearing loss, developmental delay, carpal and tarsal
fusions, and the presence of the Pro250Arg mutation in the FGFR3 gene. Reduced
penetrance and variable expressivity contribute to the wide spectrum of clinical
findings in Muenke syndrome. To better define the clinical features of this
syndrome, we initiated a study of the natural history of Muenke syndrome. To
date, we have conducted a standardized evaluation of nine patients with a
confirmed Pro250Arg mutation in FGFR3. We reviewed audiograms from an additional
13 patients with Muenke syndrome. A majority of the patients (95%) demonstrated
a mild-to-moderate, low frequency sensorineural hearing loss. This pattern of
hearing loss was not previously recognized as characteristic of Muenke syndrome.
We also report on feeding and swallowing difficulties in children with Muenke
syndrome. Combining 312 reported cases of Muenke syndrome with data from the
nine NIH patients, we found that females with the Pro250Arg mutation were
significantly more likely to be reported with craniosynostosis than males (P <
0.01). Based on our findings, we propose that the clinical management should
include audiometric and developmental assessment in addition to standard
clinical care and appropriate genetic counseling. The Muenke syndrome (MS) is characterized by unicoronal or bicoronal
craniosynostosis, midfacial hypoplasia, ocular hypertelorism, and a variety of
minor abnormalities associated with a mutation in the fibroblast growth factor
receptor 3 (FGFR3) gene. The birth prevalence is approximately one in 10,000
live births, accounting for 8-10% of patients with coronal synostosis. Although
MS is a relatively common diagnosis in patients with craniosynostosis syndromes,
with autosomal domit inheritance, there has been no report of MS, in an
affected Korean family with typical cephalo-facial morphology that has been
confirmed by molecular studies. Here, we report a familial case of MS in a
female patient with a Pro250Arg mutation in exon 7 (IgII-IGIII linker domain) of
the FGFR3 gene. This patient had mild midfacial hypoplasia, hypertelorism,
downslanting palpebral fissures, a beak shaped nose, plagio-brachycephaly, and
mild neurodevelopmental delay. The same mutation was confirmed in the patient's
mother, two of the mother's sisters and the maternal grandfather. The severity
of the cephalo-facial anomalies was variable among these family members. BACKGROUND: The facial features of children with FGFR3Pro250Arg mutation (Muenke
syndrome) differ from those with the other eponymous craniosynostotic disorders.
We documented midfacial growth and position of the forehead after fronto-orbital
advancement (FOA) in patients with the FGFR3 mutation.
METHODS: We retrospectively reviewed all patients who had an FGFR3Pro250Arg
mutation and craniosynostosis. Only patients who had FOA in infancy or early
childhood were included. The clinical records were evaluated for type of sutural
fusion; midfacial hypoplasia and other clinical data, including age at
operation; type of procedures and fixation (wire vs resorbable plate); frequency
of frontal readvancement, forehead augmentation, midfacial advancement; and
complications. Preoperative and postoperative sagittal orbital-globe
relationship was measured by direct anthropometry. Outcome of FOA was graded
according to the Whittaker classification as category I, no revision; category
II, minor revisions, that is, foreheadplasty; category III, alternative bony
work; category IV; redo of initial procedure (ie, secondary FOA). Midfacial
position was determined by clinical examination and lateral cephalometry.
RESULTS: A total of 21 study patients with Muenke syndrome (8 males and 13
females) were analyzed. The types of craniosynostosis were bilateral coronal
(n=15), of which 3 also had concurrent sagittal fusion, and unilateral coronal
(n=5). Two patients had early endoscopic suturectomy, but later required FOA.
Mean age at FOA was 22.9 months (range, 3-128 months). Secondary FOA was
necessary in 40% of patients (n=8), and secondary foreheadplasty in 25% (n=5) of
patients. No frontal revisions were needed in the remaining 35% of patients
(n=7). Mean age at initial FOA was significantly younger in the group requiring
repeat FOA or foreheadplasty compared with patients who did not require revision
(P<0.05). Location of synostosis, type of fixation, and bone grafting did not
significantly affect the need for revision. Only 30% (n=6) of patients developed
midfacial retrusion.
CONCLUSIONS: The frequency of frontal revision in patients with Muenke syndrome
who had FOA in infancy and early childhood is lower than previously reported.
Age at forehead advancement inversely correlated with the incidence of relapse
and need for secondary frontal procedures. Midfacial retrusion is relatively
uncommon in FGFR3Pro250Arg patients. OBJECTIVES: To determine syndrome-specific type, severity, and prevalence of
hearing loss to facilitate follow-up and treatment.
DESIGN: Tertiary pediatric hospital craniofacial clinic survey study. If
insufficient or no data were available for a child, he or she was referred to an
audiologist for pure-tone audiometry.
SETTING: Academic research facility.
PATIENTS: Information was gathered regarding 132 children and young adults with
craniosynostosis.
MAIN OUTCOME MEASURES: The primary outcome was hearing assessment of children
and young adults with various types of craniosynostosis. A secondary outcome was
inference regarding the incidence of otitis media among children and young
adults with craniosynostosis.
RESULTS: We found mild or moderate hearing loss in 44.0% of patients with Apert
syndrome, in 28.5% with Crouzon syndrome, in 62.1% with Muenke syndrome, in
28.6% with Saethre-Chotzen syndrome, and in 6.7% with complex craniosynostosis.
Hearing loss was conductive in most patients with Apert, Crouzon, and
Saethre-Chotzen syndromes and it was predomitly sensorineural in patients
with Muenke syndrome. Sensorineural hearing loss at lower frequencies was found
only in patients with Muenke syndrome.
CONCLUSIONS: Most patients with syndromic and complex craniosynostosis have
recurrent otitis media with effusion, causing episodes of conductive hearing
loss throughout their lives. Sensorineural hearing loss can occur in all 4
syndromes studied but is the primary cause of hearing loss in children and young
adults with Muenke syndrome. For patients with these syndromes, we recommend
routine visits to the general practitioner or otolaryngologist, depending on
national standards of care, to screen for otitis media with effusion throughout
life. We also advise early screening for sensorineural hearing loss among
children and young adults with these syndromes. Muenke syndrome caused by the FGFR3 Pro250Arg mutation is associated with
craniosynostosis, hearing loss, and various bony anomalies. Although this
mutation is involved in bone growth and development, bony tumors are rare in
this condition. We describe a patient with a molecular diagnosis of Muenke
syndrome who also presented with multiple osteochondromas of the upper and lower
extremities. This association has only been described once before in a patient
with an isolated osteochondroma of the proximal tibia. Altered expression of
FGFR3, an important mediator of chondrocyte proliferation and differentiation
during in the growth plates of long bones, may help to explain the development
of osteochondromatous lesions in this patient. Muenke syndrome is characterized by various craniofacial deformities and is
caused by an autosomal-domit activating mutation in fibroblast growth factor
receptor 3 (FGFR3(P250R) ). Here, using mice carrying a corresponding mutation
(FgfR3(P244R) ), we determined whether the mutation affects temporomandibular
joint (TMJ) development and growth. In situ hybridization showed that FgfR3 was
expressed in condylar chondroprogenitors and maturing chondrocytes that also
expressed the Indian hedgehog (Ihh) receptor and transcriptional target Patched
1(Ptch1). In FgfR3(P244R) mutants, the condyles displayed reduced levels of Ihh
expression, H4C-positive proliferating chondroprogenitors, and collagen type II-
and type X-expressing chondrocytes. Primary bone spongiosa formation was also
disturbed and was accompanied by increased osteoclastic activity and reduced
trabecular bone formation. Treatment of wild-type condylar explants with
recombit FGF2/FGF9 decreased Ptch1 and PTHrP expression in
superficial/polymorphic layers and proliferation in chondroprogenitors. We also
observed early degenerative changes of condylar articular cartilage, abnormal
development of the articular eminence/glenoid fossa in the TMJ, and fusion of
the articular disc. Analysis of our data indicates that the activating
FgfR3(P244R) mutation disturbs TMJ developmental processes, likely by reducing
hedgehog signaling and endochondral ossification. We suggest that a balance
between FGF and hedgehog signaling pathways is critical for the integrity of TMJ
development and for the maintece of cellular organization. PURPOSE: The Muenke syndrome mutation (FGFR3 (P250R)), which was discovered 15
years ago, represents the single most common craniosynostosis mutation. Muenke
syndrome is characterized by coronal suture synostosis, midface hypoplasia,
subtle limb anomalies, and hearing loss. However, the spectrum of clinical
presentation continues to expand. To better understand the pathophysiology of
the Muenke syndrome, we present collective findings from several recent studies
that have characterized a genetically equivalent mouse model for Muenke syndrome
(FgfR3 (P244R)) and compare them with human phenotypes.
CONCLUSIONS: FgfR3 (P244R) mutant mice show premature fusion of facial sutures,
premaxillary and/or zygomatic sutures, but rarely the coronal suture. The mice
also lack the typical limb phenotype. On the other hand, the mutant mice display
maxillary retrusion in association with a shortening of the anterior cranial
base and a premature closure of intersphenoidal and spheno-occipital
synchondroses, resembling human midface hypoplasia. In addition, sensorineural
hearing loss is detected in all FgfR3 (P244R) mutant mice as in the majority of
Muenke syndrome patients. It is caused by a defect in the mechanism of cell fate
determination in the organ of Corti. The mice also express phenotypes that have
not been previously described in humans, such as reduced cortical bone
thickness, hypoplastic trabecular bone, and defective temporomandibular joint
structure. Therefore, the FgfR3 (P244R) mouse provides an excellent opportunity
to study disease mechanisms of some classical phenotypes of Muenke syndrome and
to test novel therapeutic strategies. The mouse model can also be further
explored to discover previously unreported yet potentially significant
phenotypes of Muenke syndrome. Muenke syndrome is an autosomal domit craniosynostosis syndrome resulting
from a defining point mutation in the Fibroblast Growth Factor Receptor3 (FGFR3)
gene. Muenke syndrome is characterized by coronal craniosynostosis (bilateral
more often than unilateral), hearing loss, developmental delay, and carpal
and/or tarsal bone coalition. Tarsal coalition is a distinct feature of Muenke
syndrome and has been reported since the initial description of the disorder in
the 1990s. Although talocalcaneal coalition is the most common tarsal coalition
in the general population, it has never previously been reported in a patient
with Muenke syndrome. We present a 7-year-old female patient with Muenke
syndrome and symptomatic talocalcaneal coalition. She presented at the age of 7
with limping, tenderness and pain in her right foot following a fall and strain
of her right foot. She was treated with ibuprofen, shoe inserts, a CAM walker
boot, and stretching exercises without much improvement in symptoms. A computed
tomography (CT) scan revealed bilateral talocalcaneal coalitions involving the
middle facet. She underwent resection of the talocalcaneal coalitions, remaining
pain-free post-operatively with an improvement in her range of motion, gait, and
mobility. This report expands the phenotype of tarsal coalition in Muenke
syndrome to include talocalcaneal coalition. A literature review revealed a high
incidence of tarsal coalition in all FGFR related craniosynostosis syndromes
when compared to the general population, a difference that is statistically
significant. The most common articulation involved in all syndromic
craniosynostoses associated with FGFR mutations is the calcaneocuboid
articulation. |
List all reported treatment options for anxiety in autism spectrum disorder. | The predominant approach is to use versions of cognitive behavioural therapies, such as:
Mindfulness Based Therapy (MBT)
Multimodal Anxiety and Social Skills Intervention (MASSI) program
modified version of the Coping Cat program, (cognitive-behavioral therapy; CBT)
Family cognitive-behavioral therapy has been found to be more effective than Individual cognitive-behavioral therapy
Conflict management for couples, even when conflict and family distress is low
Drugtherapy:
Sertraline | A family-based, cognitive behavioural treatment for anxiety in 47 children with
comorbid anxiety disorders and High Functioning Autism Spectrum Disorder (HFA)
was evaluated. Treatment involved 12 weekly group sessions and was compared with
a waiting list condition. Changes between pre- and post-treatment were examined
using clinical interviews as well as child-, parent- and teacher-report
measures. Following treatment, 71.4% of the treated participants no longer
fulfilled diagnostic criteria for an anxiety disorder. Comparisons between the
two conditions indicated significant reductions in anxiety symptoms as measured
by self-report, parent report and teacher report. Discussion focuses on the
implications for the use of cognitive behaviour therapy with HFA children, for
theory of mind research and for further research on the treatment components. This study examines the potential impact of family conflict and cohesion, and
peer support/bullying on children with autism spectrum disorder (ASD). While
such impacts have been established for a range of non-ASD childhood disorders,
these findings may not generalize to children with ASD because of unique
problems in perspective-taking, understanding others' emotion, cognitive
rigidity, and social reasoning. A structural model-building approach was used to
test the extent to which family and peer variables directly or indirectly
affected ASD via child anxiety/depression. The sample (N = 322) consisted of
parents of children with ASD referred to two specialist clinics. The sample
contained parents of children with Autistic Disorder (n = 76), Asperger Disorder
(n = 188), Pervasive Disorder Not Otherwise Specified (n = 21), and children
with a non-ASD or no diagnosis (n = 37). Parents completed questionnaires
on-line via a secure website. The key findings were that anxiety/depression and
ASD symptomatology were significantly related, and family conflict was more
predictive of ASD symptomatology than positive family/peer influences. The
results point to the utility of expanding interventions to include conflict
management for couples, even when conflict and family distress is low. Further
research is needed on the potentially different meanings of family cohesion and
conflict for children with ASD relative to children without ASD. It is now well established that the prevalence of mental health difficulties in
individuals with autism spectrum disorders (ASD) is considerably higher than in
the general population. With recent estimates of the prevalence of autism
spectrum disorders being as high as one percent, increasing numbers of children
and young people are presenting to local and specialist services with mental
health problems in addition to a diagnosis of ASD. Many families report that the
impact of the mental health problems can be as or more impairing than the autism
spectrum difficulties themselves. Clinical services are frequently called upon
to treat these difficulties; however, there is limited evidence for the
effectiveness of treatments in this population. This paper reports a case series
of children and adolescents with ASD and an anxiety disorder who were treated
with a standard cognitive behaviour therapy (CBT) rationale adapted to take
account of the neuropsychological features of ASD. Common features of the
presentation of the disorders and also treatment processes are discussed. TOPIC: The intent of this article is to explore the efficacy of both the literal
and concrete externalization aspects within narrative therapy, and the
implementation of interactive metaphors as a combined psychotherapeutic approach
for decreasing anxiety with people who present with high-functioning autism.
PURPOSE: The purpose of this exploratory article is to propose the use of
externalizing metaphors as a treatment modality as a potentially useful way to
engage clients. Specifically, a three-step process of change is described, which
allows for concretizing affective states and experiences, and makes use of
visual strengths of people presenting with an autism spectrum disorder.
SOURCE: A selective review was conducted of significant works regarding the
process of change in narrative therapy, with particular emphasis on metaphors.
Works were selected based on their relevance to the current paper and included
both published works (searched via Psyc-INFO) and materials from narrative
training sessions.
CONCLUSIONS: Further research is needed to address the testable hypotheses
resulting from the current model. This line of research would not only establish
best practices in a population for which there is no broadly accepted treatment
paradigm, but would also contribute to the larger fields of abnormal psychology,
emotion regulation, and cognitive psychology by further elucidating the complex
ways these systems interact. The purpose of this pilot study was to evaluate whether a modified version of
the Coping Cat program could be effective in reducing anxiety in children with
autism spectrum disorder (ASD). Twenty-two children (ages 8-14; IQ ≥ 70) with
ASD and clinically significant anxiety were randomly assigned to 16 sessions of
the Coping Cat program (cognitive-behavioral therapy; CBT) or a 16-week
waitlist. Children in the CBT condition evidenced significantly larger
reductions in anxiety than those in the waitlist. Treatment gains were largely
maintained at two-month follow-up. Results provide preliminary evidence that a
modified version of the Coping Cat program may be a feasible and effective
program for reducing clinically significant levels of anxiety in children with
high-functioning ASD. Anxiety is common among adolescents with autism spectrum disorders (ASD) and may
amplify the core social disability, thus necessitating combined treatment
approaches. This pilot, randomized controlled trial evaluated the feasibility
and preliminary outcomes of the Multimodal Anxiety and Social Skills
Intervention (MASSI) program in a sample of 30 adolescents with ASD and anxiety
symptoms of moderate or greater severity. The treatment was acceptable to
families, subject adherence was high, and therapist fidelity was high. A 16 %
improvement in ASD social impairment (within-group effect size = 1.18) was
observed on a parent-reported scale. Although anxiety symptoms declined by 26 %,
the change was not statistically significant. These findings suggest MASSI is a
feasible treatment program and further evaluation is warranted. Research shows that depression and anxiety disorders are the most common
psychiatric concern in autism spectrum disorders (ASD). Mindfulness-based
therapy (MBT) has been found effective in reducing anxiety and depression
symptoms, however research in autism is limited. Therefore, we examined the
effects of a modified MBT protocol (MBT-AS) in high-functioning adults with ASD.
42 participants were randomized into a 9-week MBT-AS training or a wait-list
control group. Results showed a significant reduction in depression, anxiety and
rumination in the intervention group, as opposed to the control group.
Furthermore, positive affect increased in the intervention group, but not in the
control group. Concluding, the present study is the first controlled trial to
demonstrate that adults with ASD can benefit from MBT-AS. OBJECTIVES: The goal of this study was to examine rates of psychotropic
medication use and identify associated child and family characteristics among
children and adolescents with autism spectrum disorder (ASD) enrolled in an
autism registry maintained by the Autism Treatment Network (ATN).
METHODS: The sample, derived from the ATN registry, consists of 2853 children
aged 2 to 17 years with diagnoses of ASD supported by Diagnostic and Statistical
Manual of Mental Disorders, Fourth Edition, and the Autism Diagnostic
Observation Schedule with available data on medication use. As part of initial
enrollment in the registry, parents completed questionnaires on current
psychotropic medication use, psychiatric and medical conditions, and
demographics.
RESULTS: Of the 2853 children, 763 (27%) were taking ≥ 1 psychotropic
medication; 15% were prescribed 1 medication, 7.4% received 2 medications, and
4.5% received ≥ 3. Among children aged 3 to 5 years, 11% were taking ≥ 1
psychotropic medication; among 6- to 11-year-old children, 46%; and 66% of
adolescents aged 12 to 17 years were taking at ≥ 1 psychotropic medication. A
parent report of comorbid diagnosis of attention-deficit/hyperactivity disorder,
bipolar disorder, obsessive-compulsive disorder, depression, or anxiety was
associated with a high rate of use, with 80% receiving ≥ 1 psychotropic
medication. Only 15% of children with no comorbid psychiatric disorder were
taking psychotropic medication. Psychotropic medication use was also related to
sleep and gastrointestinal problems.
CONCLUSIONS: The prescription of psychotropic medications in this registry
sample is highly related to comorbid psychiatric disorder. Other factors
associated with use include medical comorbidities, race, ethnicity, and older
age. |
List adenosine A2A receptor antagonists that are used for Parkinson's disease treatment. | Istradefylline and preladenant are adenosine A2A receptor antagonists that are used for Parkinson's disease treatment. | Dopamine replacement therapy effectively treats the early motor symptoms of
Parkinson's disease (PD). However, its association with the development of motor
complications limits its usefulness in late stages of the disease. Adenosine
A(2A) receptors are localised to the indirect striatal output function and
control motor behaviour. They are active in predictive experimental models of PD
and appear to be promising as the first major non-dopaminergic therapy for PD.
Istradefylline is a novel adenosine A(2A) receptor antagonist currently in Phase
III clinical trials for efficacy in patients with PD; results from Phase II
clinical trials demonstrated that it provides a clinically meaningful reduction
in 'off' time and an increased 'on' time with non-troublesome dyskinesia in
levodopa-treated patients with established motor complications, and is safe and
well tolerated. Parkinson's disease (PD) is the second most prevalent neurodegenerative
disorder, affecting up to 10 million people worldwide. Current treatment
primarily involves symptom management with dopaminergic replacement therapy.
Levodopa remains the most effective oral treatment, although long-term use is
associated with complications such as wearing off, dyskinesias, and on-off
fluctuations. Non-dopaminergic medications that improve PD symptoms and motor
fluctuations are in demand. Adenosine A2A receptors are abundantly expressed
within the basal ganglia and offer a unique target to modify abnormal striatal
signaling associated with PD. Preclinical animal models have shown the ability
of adenosine A2A receptor antagonists to improve PD motor symptoms, reduce motor
fluctuations and dyskinesia, as well as protect against toxin-induced neuronal
degeneration. Both istradefylline and preladet have demonstrated moderate
efficacy in reducing off time in PD patients with motor fluctuations. The safety
and efficacy of this class of compounds continues to be defined and future
studies should focus on non-motor symptoms, dyskinesias, and neuroprotection. BACKGROUND: We evaluated the efficacy and safety of istradefylline, a selective
adenosine A2A receptor antagonist administered as adjunctive treatment to
levodopa for 12 weeks in a double-blind manner in Parkinson's disease patients
with motor complications in Japan.
METHODS: A total of 373 subjects were randomized to receive placebo (n=126),
istradefylline 20 mg/day (n=123), or istradefylline 40 mg/day (n=124). The
primary efficacy variable was the change in daily OFF time. Other secondary
variables were also evaluated.
RESULTS: The change in daily OFF time was significantly reduced in the
istradefylline 20 mg/day (-0.99 hours, P=.003) and istradefylline 40 mg/day
(-0.96 hours, P=.003) groups compared with the placebo group (-0.23 hours). The
most common adverse event was dyskinesia (placebo, 4.0%; istradefylline 20
mg/day, 13.0%; istradefylline 40 mg/day, 12.1%).
CONCLUSIONS: Istradefylline reduced daily OFF time and was well tolerated in
Japanese PD patients with motor complications on levodopa treatment. INTRODUCTION: Recent experimental and clinical research has shown that A2A
adenosine receptor antagonism can bring about an improvement in the motor
behavior of patients with Parkinson's disease. Istradefylline , a xanthine
derivative, has the longest half-life of all the currently available A2A
adenosine receptor antagonists; it can successfully permeate through the
blood-brain barrier and has a high human A2A adenosine receptor affinity.
AREAS COVERED: In this article, the author discusses the potential role of A2A
adenosine receptor antagonists in the treatment of Parkinson's disease through
the evaluation of istradefylline. Specifically, the article reviews the clinical
and pharmacokinetic information available to elucidate its therapeutic
potential.
EXPERT OPINION: A2A adenosine receptor antagonists are efficacious in
combination with l-dopa. l-dopa has a complex pharmacokinetic behavior and
causes long-term behavioral and metabolic side effects. Future research on A2A
adenosine receptor antagonism should consider compounds like istradefylline as
l-dopa and/or dopamine agonist-sparing treatment alternatives, since their
clinical handling, safety and side-effect profile are superior to l-dopa and/or
dopamine agonists. The current focus to demonstrate a specific
dyskinesia-ameliorating efficacy of A2A adenosine receptor antagonism in
clinical trials is risky, since the presentation of dyskinesia varies on a
day-to-day basis and is considerably influenced by peripheral l-dopa metabolism.
The demonstration of an antidyskinetic effect may convince authorities, but this
is far less relevant in clinical practice as patients generally better tolerate
dyskinesia than other phenomena and dopaminergic side effects. RATIONALE: Altered cognitive function is a common feature of both the early and
later stages of Parkinson's disease (PD) that involves alterations in cortical
dopamine content. Adenosine A2A antagonists, such as istradefylline, improve
motor function in PD, but their effect on cognitive impairment has not been
determined.
OBJECTIVE: The present study investigated whether impairment of working memory
due to the loss of dopaminergic input into the prefrontal cortex (PFC) is
reversed by administration of istradefylline. We also evaluated whether A2A
antagonist administration modulates dopamine levels in the PFC.
METHODS: Bilateral lesions of the dopaminergic input to the PFC were produced in
rats using 6-hydroxydopamine (6-OHDA). Cognitive performance was evaluated using
an object recognition task and delayed alternation task. The effects of
istradefylline, donepezil and methamphetamine on cognitive performance were
examined. In addition, the effect of istradefylline on extracellular dopamine
levels in the PFC was studied.
RESULTS: PFC dopamine levels and cognitive performance were significantly
reduced by 6-OHDA lesioning. Istradefylline, donepezil and methamphetamine
improved cognitive performance of PFC-lesioned rats. Istradefylline increased
dopamine levels in the PFC in both normal and PFC-lesioned rats.
CONCLUSIONS: PFC dopaminergic input plays an important role in working memory
performance. Blockade of A2A receptors using istradefylline reverses the changes
in cognitive function, and this may be due to an increase in PFC dopamine
content. Adenosine A2A receptor antagonists not only improve motor performance
in PD but may also lead to improved cognition. Neurotransmitters other than dopamine, such as norepinephrine,
5-hydroxytryptamine, glutamate, adenosine and acetylcholine, are involved in
Parkinson's disease (PD) and contribute to its symptomatology. Thus, the
progress of non-dopaminergic therapies for PD has attracted much interest in
recent years. Among new classes of drugs, adenosine A2A antagonists have emerged
as promising candidates. The development of new highly selective adenosine A2A
receptor antagonists, and their encouraging anti-parkinsonian responses in
animal models of PD, has provided a rationale for clinical trials to evaluate
the therapeutic potential and the safety of these agents in patients with PD. To
date, the clinical research regarding A2A antagonists and their potential
utilization in PD therapy continues to evolve between drugs just or previously
discontinued (preladet and vipadet), new derivatives in development
(tozadet, PBF-509, ST1535, ST4206 and V81444) and the relatively old drug
istradefylline, which has finally been licensed as an anti-parkinsonian drug in
Japan. All these compounds have been shown to have a good safety profile and be
well tolerated. Moreover, results from phase II and III trials also demonstrate
that A2A antagonists are effective in reducing off-time, without worsening
troublesome dyskinesia, and in increasing on-time with a mild increase of
non-troublesome dyskinesia, in patients at an advanced stage of PD treated with
L-DOPA. In addition, early findings suggest that A2A antagonists might also be
efficacious as monotherapy in patients at an early stage of PD. This review
summarizes pharmacological and clinical data available on istradefylline,
tozadet, PBF-509, ST1535, ST4206, V81444, preladet and vipadet. Adenosine A2A receptor antagonists represent a new way forward in the
symptomatic treatment of Parkinson's disease (PD) through a non-dopaminergic
mechanism. As a class, adenosine A2A antagonists are effective in reversing
motor deficits in haloperidol-treated rodents, 6-OHDA-lesioned rats, and
MPTP-treated primates when combined with low doses of l-dopa or dopamine agonist
drugs. Importantly, they improve motor function without worsening dyskinesia and
they may prevent the onset of involuntary movements. Adenosine A2A receptor
antagonists are active in animal models of reduced cognition, anxiety, and
depression and so this drug class may also be effective in controlling the
neuropsychiatric components of nonmotor symptoms in PD. Preclinical evidence has
shown that A2A antagonists can prevent neuronal loss in experimental models of
PD and their disease modifying activity needs to be explored in man.
Importantly, a number of A2A antagonists have been studied in PD in clinical
trial for their effects on motor function. So far, little evidence has emerged
of an effect of monotherapy with adenosine antagonists in early PD. However, in
later stage, patient populations already treated with dopaminergic drugs but
exhibiting "wearing off," adenosine antagonists have been demonstrated to reduce
"off" time without increasing troublesome dyskinesia in phase IIB trials.
However, in larger phase III evaluations, a consistent significant decrease in
"off" time has proved more difficult to demonstrate-due in part to trial
conduct. So far, only istradefylline has completed phase III development and it
is now marketed for the treatment of PD. Adenosine A2A antagonists are the first
non-dopaminergic approach to the treatment of PD to appear in the recent era.
They represent a novel way of approaching therapy that will provide additional
benefit to that achieved with dopaminergic medication, while avoiding common
side effects and may in addition, improve some nonmotor symptoms of PD that are
currently poorly treated. |
What is the clinical indication of cardiac T1 mapping magnetic resonance? | T1 mapping can quantitatively characterize myocardial tissue, in particular diffuse and interstitial fibrosis, edema in both overt and subclinical cardiophyopathies. However more research is required before a large-scale application for clinical decision-making can be recommended. | Pixel-by-pixel calculation of T1 values (T1 mapping) has been used in different
tissues to focus on T1 changes in a quantitative fashion. The aim of this study
was to establish T1 mapping of human myocardium on a 1.5 Tesla system and to
examine its diagnostic potential in patients with acute myocardial infarction
(AMI). 8 patients with reperfused AMI (day 3 +/- 1) underwent multi-breath-hold
MRI in a 1.5 Tesla system. Sets of five images with varying T1 weighting were
acquired prior to and after the administration of contrast agent to generate
images from calculated T1 values (T1 mapping). Prior to the contrast agent
administration, all patients showed T1 prolongation in the area of infarction,
which was identified in separate measurements using the delayed enhancement
approach. Compared to noninfarcted areas, T1 values in the infarcted areas were
increased by 18 +/- 7% (SE, p < 0.05). The spatial extent of the area of T1
prolongation was larger than that of the hyper-enhanced areas in conventional
contrast-enhanced images. T1 maps obtained after the application of
Gadolinium-DTPA revealed a T1 reduction of 27 +/- 4% in infarcted tissue
compared to noninfarcted areas (p < 0.05). The areas showing T1 reduction were
in agreement with the hyper-enhanced regions in conventional T1-weighted images.
T1 mapping visualizes changes in the longitudinal relaxation time induced by
AMI. T1 mapping can detect myocardial necrosis without the use of contrast
media. Information that can be extracted from a combination of pre- and
postcontrast T1 maps exceeds that from conventional contrast studies. PURPOSE: To optimize and validate a fully-integrated version of modified
Look-Locker inversion-recovery (MOLLI) for clinical single-breathhold cardiac T1
mapping.
MATERIALS AND METHODS: A MOLLI variant allowing direct access to all pulse
sequence parameters was implemented on a 1.5T MR system. Varying four critical
sequence parameters, MOLLI was performed in eight gadolinium-doped agarose gel
phantoms at different simulated heart rates. T1 values were derived for each
variant and compared to nominal T1 values. Based on the results, MOLLI was
performed in midcavity short-axis views of 20 healthy volunteers pre- and
post-Gd-DTPA.
RESULTS: In phantoms, a readout flip angle of 35 degrees , minimum TI of 100
msec, TI increment of 80 msec, and use of three pausing heart cycles allowed for
most accurate and least heart rate-dependent T1 measurements. Using this pulse
sequence scheme in humans, T1 relaxation times in normal myocardium were
comparable to data from previous studies, and showed narrow ranges both pre- and
postcontrast without heart rate dependency.
CONCLUSION: We present an optimized implementation of MOLLI for fast T1 mapping
with high spatial resolution, which can be integrated into routine imaging
protocols. T1 accuracy is superior to the original set of pulse sequence
parameters and heart rate dependency is avoided. OBJECTIVES: The purpose of this study was to investigate a noninvasive method
for quantifying diffuse myocardial fibrosis with cardiac magnetic resoce
imaging (CMRI).
BACKGROUND: Diffuse myocardial fibrosis is a fundamental process in pathologic
remodeling in cardiomyopathy and is postulated to cause increased cardiac
stiffness and poor clinical outcomes. Although regional fibrosis is easily
imaged with cardiac magnetic resoce, there is currently no noninvasive method
for quantifying diffuse myocardial fibrosis.
METHODS: We performed CMRI on 45 subjects (25 patients with heart failure, 20
control patients), on a clinical 1.5-T CMRI scanner. A prototype T(1) mapping
sequence was used to calculate the post-contrast myocardial T(1) time as an
index of diffuse fibrosis; regional fibrosis was identified by delayed contrast
enhancement. Regional and global systolic function was assessed by cine CMRI in
standard short- and long-axis planes, with echocardiography used to evaluate
diastology. An additional 9 subjects underwent CMRI and endomyocardial biopsy
for histologic correlation.
RESULTS: Post-contrast myocardial T(1) times correlated histologically with
fibrosis (R = -0.7, p = 0.03) and were shorter in heart failure subjects than
controls (383 +/- 17 ms vs. 564 +/- 23 ms, p < 0.0001). The T(1) time of heart
failure myocardium was shorter than that in controls even when excluding areas
of regional fibrosis (429 +/- 22 ms vs. 564 +/- 23 ms, p < 0.0001). The
post-contrast myocardial T(1) time shortened as diastolic function worsened (562
+/- 24 ms in normal diastolic function vs. 423 +/- 33 ms in impaired diastolic
function vs. 368 +/- 20 ms in restrictive function, p < 0.001).
CONCLUSIONS: Contrast-enhanced CMRI T(1) mapping identifies changes in
myocardial T(1) times in heart failure, which appear to reflect diffuse
fibrosis. BACKGROUND: Quantitative relaxation time measurements by cardiovascular magnetic
resoce (CMR) are of paramount importance in contrast-enhanced studies of
experimental myocardial infarction. First, compared to qualitative measurements
based on signal intensity changes, they are less sensitive to specific parameter
choices, thereby allowing for better comparison between different studies or
during longitudinal studies. Secondly, T1 measurements may allow for
quantification of local contrast agent concentrations. In this study, a recently
developed 3D T1 mapping technique was applied in a mouse model of myocardial
infarction to measure differences in myocardial T1 before and after injection of
a liposomal contrast agent. This was then used to assess the concentration of
accumulated contrast agent.
MATERIALS AND METHODS: Myocardial ischemia/reperfusion injury was induced in 8
mice by transient ligation of the LAD coronary artery. Baseline quantitative T1
maps were made at day 1 after surgery, followed by injection of a Gd-based
liposomal contrast agent. Five mice served as control group, which followed the
same protocol without initial surgery. Twenty-four hours post-injection, a
second T1 measurement was performed. Local ΔR1 values were compared with
regional wall thickening determined by functional cine CMR and correlated to ex
vivo Gd concentrations determined by ICP-MS.
RESULTS: Compared to control values, pre-contrast T1 of infarcted myocardium was
slightly elevated, whereas T1 of remote myocardium did not significantly differ.
Twenty-four hours post-contrast injection, high ΔR1 values were found in regions
with low wall thickening values. However, compared to remote tissue (wall
thickening > 45%), ΔR1 was only significantly higher in severe infarcted tissue
(wall thickening < 15%). A substantial correlation (r = 0.81) was found between
CMR-based ΔR1 values and Gd concentrations from ex vivo ICP-MS measurements.
Furthermore, regression analysis revealed that the effective relaxivity of the
liposomal contrast agent was only about half the value determined in vitro.
CONCLUSIONS: 3D cardiac T1 mapping by CMR can be used to monitor the
accumulation of contrast agents in contrast-enhanced studies of murine
myocardial infarction. The contrast agent relaxivity was decreased under in vivo
conditions compared to in vitro measurements, which needs consideration when
quantifying local contrast agent concentrations. Direct measurement of the longitudinal relaxation time T1 provides objective and
quantitative diagnostic information. However, current T1 mapping methods are
generally time consuming without the aid of fast imaging. This study used a
model-based compressed sensing method for fast cardiac T1 mapping in small
animals. Based on the physics of magnetization recovery, the aliasing artifact
associated with under-sampling was removed by exploiting the sparsity of the
signals in the T1 recovery direction. Simulation study was performed to evaluate
the reconstruction accuracy under various experimental conditions. Several
approaches that accounted for phase variations were compared for optimized
reconstruction in the phantom study. In vivo validation was performed on a
cardiac manganese-enhanced MRI study using mice. Accurate reconstruction of the
under-sampled images and the resulting T1 maps were achieved in both simulation
and MRI studies on phantom and in vivo mice. These results suggest that the
current compressed sensing method allows fast (<80 s) T1 mapping of the mouse
heart at high spatial resolution (234×469 μm2). BACKGROUND: Current cardiovascular magnetic resoce (CMR) methods, such as
late gadolinium enhancement (LGE) and oedema imaging (T2W) used to depict
myocardial ischemia, have limitations. Novel quantitative T1-mapping techniques
have the potential to further characterize the components of ischemic injury. In
patients with myocardial infarction (MI) we sought to investigate whether
state-of the art pre-contrast T1-mapping (1) detects acute myocardial injury,
(2) allows for quantification of the severity of damage when compared to
standard techniques such as LGE and T2W, and (3) has the ability to predict long
term functional recovery.
METHODS: 3T CMR including T2W, T1-mapping and LGE was performed in 41 patients
[of these, 78% were ST elevation MI (STEMI)] with acute MI at 12-48 hour after
chest pain onset and at 6 months (6M). Patients with STEMI underwent primary PCI
prior to CMR. Assessment of acute regional wall motion abnormalities, acute
segmental damaged fraction by T2W and LGE and mean segmental T1 values was
performed on matching short axis slices. LGE and improvement in regional wall
motion at 6M were also obtained.
RESULTS: We found that the variability of T1 measurements was significantly
lower compared to T2W and that, while the diagnostic performance of acute
T1-mapping for detecting myocardial injury was at least as good as that of
T2W-CMR in STEMI patients, it was superior to T2W imaging in NSTEMI. There was a
significant relationship between the segmental damaged fraction assessed by
either by LGE or T2W, and mean segmental T1 values (P < 0.01). The index of
salvaged myocardium derived by acute T1-mapping and 6M LGE was not different to
the one derived from T2W (P = 0.88). Furthermore, the likelihood of improvement
of segmental function at 6M decreased progressively as acute T1 values increased
(P < 0.0004).
CONCLUSIONS: In acute MI, pre-contrast T1-mapping allows assessment of the
extent of myocardial damage. T1-mapping might become an important complementary
technique to LGE and T2W for identification of reversible myocardial injury and
prediction of functional recovery in acute MI. BACKGROUND: Patients with myotonic muscular dystrophy (DM) are at risk for
atrioventricular block and left ventricular (LV) dysfunction. Noninvasive
detection of diffuse myocardial fibrosis may improve disease management in this
population.
OBJECTIVE: To define functional and postcontrast myocardial T1 time cardiac
magnetic resoce characteristics in patients with DM.
METHODS: Thirty-three patients with DM (24 with type 1 and 9 with type 2) and 13
healthy volunteers underwent cardiac magnetic resoce for the assessment of LV
indices and the evaluation of diffuse myocardial fibrosis by T1 mapping. The
association of myocardial T1 time with electrocardiogram abnormalities and LV
indices was examined among patients with DM.
RESULTS: Patients with DM had lower end-diastolic volume index (68.9 mL/m(2) vs
60.3 mL/m(2); P = .045) and cardiac index (2.7 L/min/m(2) vs 2.33 L/min/m(2); P
= .005) and shorter myocardial T1 time (394.5 ms vs 441.4 ms; P < .0001) than
did control subjects. Among patients with DM, there was a positive association
between higher T1 time and LV mass index (2.2 ms longer per g/m(2); P = .006),
LV end-diastolic volume index (1.3 ms longer per mL/m(2); P = .026), filtered
QRS duration (1.2 ms longer per unit; P = .005), and low-amplitude (<40 mcV)
late-potential duration (0.9 ms longer per unit; P = .01). Using multivariate
random effects regression, each 10-ms increase in myocardial T1 time of patients
with type 1 DM was independently associated with 1.3-ms increase in longitudinal
PR and QRS intervals during follow-up.
CONCLUSIONS: DM is associated with structural alterations on cardiac magnetic
resoce. Postcontrast myocardial T1 time was shorter in patients with DM than
in controls, likely reflecting the presence of diffuse myocardial fibrosis. BACKGROUND: T2w-CMR is used widely to assess myocardial edema. Quantitative
T1-mapping is also sensitive to changes in free water content. We hypothesized
that T1-mapping would have a higher diagnostic performance in detecting acute
edema than dark-blood and bright-blood T2w-CMR.
METHODS: We investigated 21 controls (55 ± 13 years) and 21 patients
(61 ± 10 years) with Takotsubo cardiomyopathy or acute regional myocardial edema
without infarction. CMR performed within 7 days included cine, T1-mapping using
ShMOLLI, dark-blood T2-STIR, bright-blood ACUT2E and LGE imaging. We analyzed
wall motion, myocardial T1 values and T2 signal intensity (SI) ratio relative to
both skeletal muscle and remote myocardium.
RESULTS: All patients had acute cardiac symptoms, increased Troponin I
(0.15-36.80 ug/L) and acute wall motion abnormalities but no LGE. T1 was
increased in patient segments with abnormal and normal wall motion compared to
controls (1113 ± 94 ms, 1029 ± 59 ms and 944 ± 17 ms, respectively; p < 0.001).
T2 SI ratio using STIR and ACUT2E was also increased in patient segments with
abnormal and normal wall motion compared to controls (all p < 0.02). Receiver
operator characteristics analysis showed that T1-mapping had a significantly
larger area-under-the-curve (AUC = 0.94) compared to T2-weighted methods,
whether the reference ROI was skeletal muscle or remote myocardium
(AUC = 0.58-0.89; p < 0.03). A T1 value of greater than 990 ms most optimally
differentiated segments affected by edema from normal segments at 1.5 T, with a
sensitivity and specificity of 92 %.
CONCLUSIONS: Non-contrast T1-mapping using ShMOLLI is a novel method for
objectively detecting myocardial edema with a high diagnostic performance.
T1-mapping may serve as a complementary technique to T2-weighted imaging for
assessing myocardial edema in ischemic and non-ischemic heart disease, such as
quantifying area-at-risk and diagnosing myocarditis. BACKGROUND: Diffuse myocardial fibrosis, and to a lesser extent global
myocardial edema, are important processes in heart disease which are difficult
to assess or quantify with cardiovascular magnetic resoce (CMR) using
conventional late gadolinium enhancement (LGE) or T1-mapping. Measurement of the
myocardial extracellular volume fraction (ECV) circumvents factors that confound
T1-weighted images or T1-maps. We hypothesized that quantitative assessment of
myocardial ECV would be clinically useful for detecting both focal and diffuse
myocardial abnormalities in a variety of common and uncommon heart diseases.
METHODS: A total of 156 subjects were imaged including 62 with normal findings,
33 patients with chronic myocardial infarction (MI), 33 with hypertrophic
cardiomyopathy (HCM), 15 with non-ischemic dilated cardiomyopathy (DCM), 7 with
acute myocarditis, 4 with cardiac amyloidosis, and 2 with systemic capillary
leak syndrome (SCLS). Motion corrected ECV maps were generated automatically
from T1-maps acquired pre- and post-contrast calibrated by blood hematocrit.
Abnormally-elevated ECV was defined as >2SD from the mean ECV in individuals
with normal findings. In HCM the size of regions of LGE was quantified as the
region >2 SD from remote.
RESULTS: Mean ECV of 62 normal individuals was 25.4 ± 2.5% (m ± SD), normal
range 20.4%-30.4%. Mean ECV within the core of chronic myocardial infarctions
(without MVO) (N=33) measured 68.5 ± 8.6% (p<0.001 vs normal). In HCM, the
extent of abnormally elevated ECV correlated to the extent of LGE (r=0.72,
p<0.001) but had a systematically greater extent by ECV (mean difference 19 ± 7%
of slice). Abnormally elevated ECV was identified in 4 of 16 patients with
non-ischemic DCM (38.1 ± 1.9% (p<0.001 vs normal) and LGE in the same slice
appeared "normal" in 2 of these 4 patients. Mean ECV values in other disease
entities ranged 32-60% for cardiac amyloidosis (N=4), 40-41% for systemic
capillary leak syndrome (N=2), and 39-56% within abnormal regions affected by
myocarditis (N=7).
CONCLUSIONS: ECV mapping appears promising to complement LGE imaging in cases of
more homogenously diffuse disease. The ability to display ECV maps in units that
are physiologically intuitive and may be interpreted on an absolute scale offers
the potential for detection of diffuse disease and measurement of the extent and
severity of abnormal regions. BACKGROUND: Noncontrast magnetic resoce T1 mapping reflects a composite of
both intra- and extracellular signal. We hypothesized that noncontrast T1
mapping can characterize the myocardium beyond that achieved by the
well-established late gadolinium enhancement (LGE) technique (which detects
focal fibrosis) in both hypertrophic (HCM) and dilated (DCM) cardiomyopathy, by
detecting both diffuse and focal fibrosis.
METHODS AND RESULTS: Subjects underwent Cardiovascular Magnetic Resoce
imaging at 3T (28 HCM, 18 DCM, and 12 normals). Matching short-axis slices were
acquired for cine, T1 mapping, and LGE imaging (0.1 mmol/kg). Circumferential
strain was measured in the midventricular slice, and (31)P magnetic resoce
spectroscopy was acquired for the septum of the midventricular slice. Mean T1
relaxation time was increased in HCM and DCM (HCM 1209±28 ms, DCM 1225±42 ms,
normal 1178±13 ms, P<0.05). There was a weak correlation between mean T1 and LGE
(r=0.32, P<0.001). T1 values were higher in segments with LGE than in those
without (HCM with LGE 1228±41 ms versus no LGE 1192±79 ms, P<0.01; DCM with LGE
1254±73 ms versus no LGE 1217±52 ms, P<0.01). However, in both HCM and DCM, even
in segments unaffected by LGE, T1 values were significantly higher than normal
(P<0.01). T1 values correlated with disease severity, being increased as wall
thickness increased in HCM; conversely, in DCM, T1 values were highest in the
thinnest myocardial segments. T1 values also correlated significantly with
circumferential strain (r=0.42, P<0.01). Interestingly, this correlation
remained statistically significant even for the slices without LGE (r=0.56,
P=0.04). Finally, there was also a statistically significant negative
correlation between T1 values and phosphocreatine/adenosine triphosphate ratios
(r=-0.59, P<0.0001).
CONCLUSIONS: In HCM and DCM, noncontrast T1 mapping detects underlying disease
processes beyond those assessed by LGE in relatively low-risk individuals. BACKGROUND: Cardiac magnetic resoce (CMR) T1 mapping has been used to
characterize myocardial diffuse fibrosis. The aim of this study is to determine
the reproducibility and sample size of CMR fibrosis measurements that would be
applicable in clinical trials.
METHODS: A modified Look-Locker with inversion recovery (MOLLI) sequence was
used to determine myocardial T1 values pre-, and 12 and 25min
post-administration of a gadolinium-based contrast agent at 3 Tesla. For 24
healthy subjects (8 men; 29 ± 6 years), two separate scans were obtained a) with
a bolus of 0.15mmol/kg of gadopentate dimeglumine and b) 0.1mmol/kg of
gadobenate dimeglumine, respectively, with averaged of 51 ± 34 days between two
scans. Separately, 25 heart failure subjects (12 men; 63 ± 14 years), were
evaluated after a bolus of 0.15mmol/kg of gadopentate dimeglumine. Myocardial
partition coefficient (λ) was calculated according to (ΔR1myocardium/ΔR1blood),
and ECV was derived from λ by adjusting (1-hematocrit).
RESULTS: Mean ECV and λ were both significantly higher in HF subjects than
healthy (ECV: 0.287 ± 0.034 vs. 0.267 ± 0.028, p=0.002; λ: 0.481 ± 0.052 vs. 442
± 0.037, p < 0.001, respectively). The inter-study ECV and λ variation were
about 2.8 times greater than the intra-study ECV and λ variation in healthy
subjects (ECV:0.017 vs. 0.006, λ:0.025 vs. 0.009, respectively). The estimated
sample size to detect ECV change of 0.038 or λ change of 0.063 (corresponding to
~3% increase of histological myocardial fibrosis) with a power of 80% and an
alpha error of 0.05 for heart failure subjects using a two group design was 27
in each group, respectively.
CONCLUSION: ECV and λ quantification have a low variability across scans, and
could be a viable tool for evaluating clinical trial outcome. PURPOSE: To develop an arrhythmia-insensitive rapid (AIR) cardiac T1 mapping
pulse sequence for quantification of diffuse fibrosis.
METHODS: An arrhythmia-insensitive cardiac T1 mapping pulse sequence was
developed based on saturation recovery T1 weighting, which is inherently
insensitive to heart rate and rhythm, and two single-shot balanced steady-state
free precession image acquisitions with centric k-space ordering, where T1
calculation is inherently insensitive to T2 effects. Its performance against
conventional cardiac T1 mapping based on inversion recovery (i.e., MOLLI) is
compared. Phantom experiments (T1 ranging from 535 to 2123 ms) were performed
with heart rate and rhythm simulated at 60 and 120 beats per minute (bpm) and
arrhythmia using an external triggering device. Ten human subjects and 17 large
animals were scanned precontrast and 5, 10, and 15 min after contrast agent
administration.
RESULTS: Compared with the reference T1 mapping, AIR yielded lower normalized
root-mean-square error than MOLLI (8% vs. 3%, respectively, at 60 bpm, 28% vs.
3%, respectively, at 120 bpm, and 22% vs. 3%, respectively, at arrhythmia). In
vivo studies showed that T1 measurements made by MOLLI and AIR were strongly
correlated (r = 0.99) but in poor agreement (mean difference = 161.8 ms, upper
and lower 95% limits of agreements = 347.5 ms and -24.0 ms).
CONCLUSION: Our AIR pulse sequence may be clinically useful for assessment of
diffuse myocardial fibrosis in patients. BACKGROUND: Aortic stenosis (AS) leads to diffuse fibrosis in the myocardium,
which is linked to adverse outcome. Myocardial T1 values change with tissue
composition.
OBJECTIVE: To test the hypothesis that our recently developed non-contrast
cardiac magnetic resoce (CMR) T1 mapping sequence could identify myocardial
fibrosis without contrast agent.
DESIGN, SETTING AND PATIENTS: A prospective CMR non-contrast T1 mapping study of
109 patients with moderate and severe AS and 33 age- and gender-matched
controls.
METHODS: CMR at 1.5 T, including non-contrast T1 mapping using a shortened
modified Look-Locker inversion recovery sequence, was carried out. Biopsy
samples for histological assessment of collagen volume fraction (CVF%) were
obtained in 19 patients undergoing aortic valve replacement.
RESULTS: There was a significant correlation between T1 values and CVF% (r=0.65,
p=0.002). Mean T1 values were significantly longer in all groups with severe AS
(972 ± 33 ms in severe asymptomatic, 1014 ± 38 ms in severe symptomatic) than in
normal controls (944 ± 16 ms) (p<0.05). The strongest associations with T1
values were for aortic valve area (r=-0.40, p=0.001) and left ventricular mass
index (LVMI) (r=0.36, p=0.008), and these were the only independent predictors
on multivariate analysis.
CONCLUSIONS: Non-contrast T1 values are increased in patients with severe AS and
further increase in symptomatic compared with asymptomatic patients. T1 values
lengthened with greater LVMI and correlated with the degree of biopsy-quantified
fibrosis. This may provide a useful clinical assessment of diffuse myocardial
fibrosis in the future. BACKGROUND: Increased systemic inflammation has been linked to myocardial
dysfunction and heart failure in patients with systemic lupus erythematosus
(SLE). Accurate detection of early myocardial changes may be able to guide
preventive intervention. We investigated whether multiparametric imaging by
cardiovascular magnetic resoce can detect differences between controls and
asymptomatic SLE patients.
METHODS AND RESULTS: A total of 33 SLE predomitly female patients (mean age,
40±9 years) underwent cardiovascular magnetic resoce for routine assessment
of myocardial perfusion, function, and late gadolinium enhancement. T1 mapping
was performed in single short-axis slice before and after 15 minutes of
gadolinium administration. Twenty-one subjects with a low pretest probability
and normal cardiovascular magnetic resoce served as a control group. Both
groups had similar left ventricular volumes and mass and normal global systolic
function. SLE patients had significantly reduced longitudinal strain (controls
versus SLE, -20±2% versus -17±3%; P<0.01) and showed intramyocardial and
pericardial late gadolinium enhancement. SLE patients had significantly
increased native myocardial T1 (1056±27 versus 1152±46 milliseconds; P<0.001)
and extracellular volume fraction (26±5% versus 30±6%; P=0.007) and reduced
postcontrast myocardial T1 (454±53 versus 411±62 milliseconds; P=0.01).
T1-derived indices were associated with longitudinal strain (r=0.37-0.47) but
not with the presence of late gadolinium enhancement. Native myocardial T1
values showed the greatest concordance with the presence of clinical diagnosis
of SLE.
CONCLUSIONS: In patients with SLE and free of cardiac symptoms, there is
evidence of subclinical perimyocardial impairment. We further demonstrate that
T1 mapping may have potential to detect subclinical myocardial involvement in
patients with SLE. Magnetic resoce as an imaging modality provides an excellent soft tissue
differentiation, which is an ideal choice for cardiac imaging. Cardiac magnetic
resoce (CMR) allows myocardial tissue characterization, as well as
comprehensive evaluation of the structures. Although late gadolinium enhancement
after injection of the gadolinium extracellular contrast agent has further
extended our ability to characterize the myocardial tissue, it also has
limitations in the quantification of enhanced myocardial tissue pathology, and
the detection of diffuse myocardial disease, which is not easily recognized by
enhancement contrast. Recently, the remarkable advances in CMR technique, such
as T1 mapping, which can quantitatively evaluate myocardial status, showed
potentials to overcome limitations of existing CMR sequences and to expand the
application of CMR. This article will review the technical and clinical points
to be considered in the practical use of pre- and post-contrast T1 mapping. OBJECTIVES: This study sought to explore the potential role of noncontrast
myocardial T1 mapping for detection of cardiac involvement in patients with
primary amyloid light-chain (AL) amyloidosis.
BACKGROUND: Cardiac involvement carries a poor prognosis in systemic AL
amyloidosis. Late gadolinium enhancement (LGE) cardiac magnetic resoce (CMR)
is useful for the detection of cardiac amyloid, but characteristic LGE patterns
do not always occur or they appear late in the disease. Noncontrast
characterization of amyloidotic myocardium with T1 mapping may improve disease
detection. Furthermore, quantitative assessment of myocardial amyloid load would
be of great value.
METHODS: Fifty-three AL amyloidosis patients (14 with no cardiac involvement, 11
with possible involvement, and 28 with definite cardiac involvement based on
standard biomarker and echocardiographic criteria) underwent CMR (1.5-T)
including noncontrast T1 mapping (shortened modified look-locker inversion
recovery [ShMOLLI] sequence) and LGE imaging. These were compared with 36
healthy volunteers and 17 patients with aortic stenosis and a comparable degree
of left ventricular hypertrophy as the cardiac amyloid patients.
RESULTS: Myocardial T1 was significantly elevated in cardiac AL amyloidosis
patients (1,140 ± 61 ms) compared to normal subjects (958 ± 20 ms, p < 0.001)
and patients with aortic stenosis (979 ± 51 ms, p < 0.001). Myocardial T1 was
increased in AL amyloid even when cardiac involvement was uncertain (1,048 ± 48
ms) or thought absent (1,009 ± 31 ms). A noncontrast myocardial T1 cutoff of
1,020 ms yielded 92% accuracy for identifying amyloid patients with possible or
definite cardiac involvement. In the AL amyloidosis cohort, there were
significant correlations between myocardial T1 time and indices of systolic and
diastolic dysfunction.
CONCLUSIONS: Noncontrast T1 mapping has high diagnostic accuracy for detecting
cardiac AL amyloidosis, correlates well with markers of systolic and diastolic
dysfunction, and is potentially more sensitive for detecting early disease than
LGE imaging. Elevated myocardial T1 may represent a direct marker of cardiac
amyloid load. Further studies are needed to assess the prognostic significance
of T1 elevation. OBJECTIVES: The aim of this study was to examine the value of native and
post-contrast T1 relaxation in the differentiation between healthy and diffusely
diseased myocardium in 2 model conditions, hypertrophic cardiomyopathy and
nonischemic dilated cardiomyopathy.
BACKGROUND: T1 mapping has been proposed as potentially valuable in the
quantitative assessment of diffuse myocardial fibrosis, but no studies to date
have systematically evaluated its role in the differentiation of healthy
myocardium from diffuse disease in a clinical setting.
METHODS: Consecutive subjects undergoing routine clinical cardiac magnetic
resoce at King's College London were invited to participate in this study.
Groups were based on cardiac magnetic resoce findings and consisted of
subjects with known hypertrophic cardiomyopathy (n = 25) and nonischemic dilated
cardiomyopathy (n = 27). Thirty normotensive subjects with low pre-test
likelihood of cardiomyopathy, not taking any regular medications and with normal
cardiac magnetic resoce findings including normal left ventricular mass
indexes, served as controls. Single equatorial short-axis slice T1 mapping was
performed using a 3-T scanner before and at 10, 20, and 30 minutes after the
administration of 0.2 mmol/kg of gadobutrol. T1 values were quantified within
the septal myocardium (T1 native), and extracellular volume fractions (ECV) were
calculated.
RESULTS: T1 native was significantly longer in patients with cardiomyopathy
compared with control subjects (p < 0.01). Conversely, post-contrast T1 values
were significantly shorter in patients with cardiomyopathy at all time points (p
< 0.01). ECV was significantly higher in patients with cardiomyopathy compared
with controls at all time points (p < 0.01). Multivariate binary logistic
regression revealed that T1 native could differentiate between healthy and
diseased myocardium with sensitivity of 100%, specificity of 96%, and diagnostic
accuracy of 98% (area under the curve 0.99; 95% confidence interval: 0.96 to
1.00; p < 0.001), whereas post-contrast T1 values and ECV showed lower
discriminatory performance.
CONCLUSIONS: This study demonstrates that native and post-contrast T1 values
provide indexes with high diagnostic accuracy for the discrimination of normal
and diffusely diseased myocardium. PURPOSE OF REVIEW: Myocardial fibrosis is a common feature of many
cardiomyopathies, including hypertrophic cardiomyopathy. Myocardial fibrosis has
been shown to be reversible and treatable with timely intervention. Although
early detection and assessment of fibrosis is crucial, adequate diagnostics are
still in development. Recent studies have shown progress on noninvasive imaging
methods of fibrosis using cardiovascular magnetic resoce (CMR) and nuclear
imaging modalities.
RECENT FINDINGS: T1 mapping and extracellular volume mapping (ECV) combined with
CMR imaging are cutting edge methods that have the potential to assess
interstitial myocardial fibrosis. Recent findings show that ECV measurement can
be correlated to the extent of diffuse fibrosis. Comparatively, molecular
imaging targets specific biomarkers in the fibrosis formation pathway and
provides enhanced sensitivity for imaging early disease. Biomarkers include
molecules involved in angiogenesis, ventricular remodeling, and fibrotic tissue
formation, whereas collagen targeted agents can directly identify fibrotic
tissue in the heart.
SUMMARY: This review introduces novel methods of fibrosis imaging that utilize
properties of extracellular matrix and its biomarkers. Changes in
characteristics and cellular biomarkers of the extracellular space can provide
significant information regarding fibrosis formation and its role in
cardiomyopathy. Ultimately, these findings may improve detection and monitoring
of disease and improve efficiency and effectiveness of the treatment. BACKGROUND: Cardiac magnetic resoce (CMR) T1 mapping is an emerging tool for
objective quantification of myocardial fibrosis.
OBJECTIVES: To (a) establish the feasibility of left atrial (LA) T1
measurements, (b) determine the range of LA T1 values in patients with atrial
fibrillation (AF) vs healthy volunteers, and (c) validate T1 mapping vs LA
intracardiac electrogram voltage amplitude measures.
METHODS: CMR imaging at 1.5 T was performed in 51 consecutive patients before AF
ablation and in 16 healthy volunteers. T1 measurements were obtained from the
posterior LA myocardium by using the modified Look-Locker inversion-recovery
sequence. Given the established association of reduced electrogram amplitude
with fibrosis, intracardiac point-by-point bipolar LA voltage measures were
recorded for the validation of T1 measurements.
RESULTS: The median LA T1 relaxation time was shorter in patients with AF (387
[interquartile range 364-428] ms) compared to healthy volunteers (459
[interquartile range 418-532] ms; P < .001) and was shorter in patients with AF
with prior ablation compared to patients without prior ablation (P = .035). In a
generalized estimating equations model, adjusting for data clusters per
participant, age, rhythm during CMR, prior ablation, AF type, hypertension, and
diabetes, each 100-ms increase in T1 relaxation time was associated with 0.1 mV
increase in intracardiac bipolar LA voltage (P = .025).
CONCLUSIONS: Measurement of the LA myocardium T1 relaxation time is feasible and
strongly associated with invasive voltage measures. This methodology may improve
the quantification of fibrotic changes in thin-walled myocardial tissues. BACKGROUND: Cardiovascular magnetic resoce (CMR) T1 mapping indices, such as
T1 time and partition coefficient (λ), have shown potential to assess diffuse
myocardial fibrosis. The purpose of this study was to investigate how scanner
and field strength variation affect the accuracy and precision/reproducibility
of T1 mapping indices.
METHODS: CMR studies were performed on two 1.5T and three 3T scanners. Eight
phantoms were made to mimic the T1/T2 of pre- and post-contrast myocardium and
blood at 1.5T and 3T. T1 mapping using MOLLI was performed with simulated heart
rate of 40-100 bpm. Inversion recovery spin echo (IR-SE) was the reference
standard for T1 determination. Accuracy was defined as the percent error between
MOLLI and IR-SE, and scan/re-scan reproducibility was defined as the relative
percent mean difference between repeat MOLLI scans. Partition coefficient was
estimated by ΔR1myocardium phantom/ΔR1blood phantom. Generalized linear mixed
model was used to compare the accuracy and precision/reproducibility of T1 and λ
across field strength, scanners, and protocols.
RESULTS: Field strength significantly affected MOLLI T1 accuracy (6.3% error for
1.5T vs. 10.8% error for 3T, p<0.001) but not λ accuracy (8.8% error for 1.5T
vs. 8.0% error for 3T, p=0.11). Partition coefficients of MOLLI were not
different between two 1.5T scanners (47.2% vs. 47.9%, p=0.13), and showed only
slight variation across three 3T scanners (49.2% vs. 49.8% vs. 49.9%, p=0.016).
Partition coefficient also had significantly lower percent error for precision
(better scan/re-scan reproducibility) than measurement of individual T1 values
(3.6% for λ vs. 4.3%-4.8% for T1 values, approximately, for pre/post blood and
myocardium values).
CONCLUSION: Based on phantom studies, T1 errors using MOLLI ranged from 6-14%
across various MR scanners while errors for partition coefficient were less
(6-10%). Compared with absolute T1 times, partition coefficient showed less
variability across platforms and field strengths as well as higher precision. OBJECTIVES: This study sought to test the diagnostic performance of native T1
mapping in acute myocarditis compared with cardiac magnetic resoce (CMR)
techniques such as dark-blood T2-weighted (T2W)-CMR, bright-blood T2W-CMR, and
late gadolinium enhancement (LGE) imaging.
BACKGROUND: The diagnosis of acute myocarditis on CMR often requires multiple
techniques, including T2W, early gadolinium enhancement, and LGE imaging. Novel
techniques such as T1 mapping and bright-blood T2W-CMR are also sensitive to
changes in free water content. We hypothesized that these techniques can serve
as new and potentially superior diagnostic criteria for myocarditis.
METHODS: We investigated 50 patients with suspected acute myocarditis (age 42 ±
16 years; 22% women) and 45 controls (age 42 ± 14 years; 22% women). CMR at
1.5-T (median 3 days from presentation) included: 1) dark-blood T2W-CMR
(short-tau inversion recovery); 2) bright-blood T2W-CMR (acquisition for cardiac
unified T2 edema); 3) native T1 mapping (shortened modified look-locker
inversion recovery); and 4) LGE. Image analysis included: 1) global T2 signal
intensity ratio of myocardium compared with skeletal muscle; 2) myocardial T1
relaxation times; and 3) areas of LGE.
RESULTS: Compared with controls, patients had significantly higher global T2
signal intensity ratios by dark-blood T2W-CMR (1.73 ± 0.27 vs. 1.56 ± 0.15, p <
0.01), bright-blood T2W-CMR (2.02 ± 0.33 vs. 1.84 ± 0.17, p < 0.01), and mean
myocardial T1 (1,010 ± 65 ms vs. 941 ± 18 ms, p < 0.01). Receiver-operating
characteristic analysis showed clear differences in diagnostic performance. The
areas under the curve for each method were: T1 mapping (0.95), LGE (0.96),
dark-blood T2 (0.78), and bright-blood T2 (0.76). A T1 cutoff of 990 ms had a
sensitivity, specificity, and diagnostic accuracy of 90%, 91%, and 91%,
respectively.
CONCLUSIONS: Native T1 mapping as a novel criterion for the detection of acute
myocarditis showed excellent and superior diagnostic performance compared with
T2W-CMR. It also has a higher sensitivity compared with T2W and LGE techniques,
which may be especially useful in detecting subtle focal disease and when
gadolinium contrast imaging is not feasible. BACKGROUND: The underlying pathophysiology of heart failure with preserved
ejection fraction (HFPEF) is incompletely understood, but myocardial
extracellular matrix accumulation is thought to play a major role. Our aims were
to estimate myocardial extracellular matrix using cardiac magnetic resoce T1
mapping and to assess the relationship between pathobiology/pathophysiology and
prognosis.
METHODS AND RESULTS: Patients with suspected HFPEF (n=100) were enrolled in this
prospective, observational study. Confirmatory diagnostic tests, cardiac
magnetic resoce imaging including T1 mapping, and invasive hemodynamic
assessments were performed at baseline. Sixty-one patients with confirmed HFPEF
entered a longitudinal outcome-monitoring phase (mean, 22.9±5.0 months), during
which 16 had a cardiac event. Cardiac magnetic resoce T1 time (hazard ratio,
0.99; 95% confidence interval, 0.98-0.99; P=0.046), left atrial area (hazard
ratio, 1.08; 95% confidence interval, 1.03-1.13; P<0.01), and pulmonary vascular
resistance (hazard ratio, 1.01; 95% confidence interval, 1.00-1.01; P=0.03) were
significantly associated with cardiac events. Patients with T1 times below the
median (<388.3 ms) were at greater risk of cardiac events than the rest of the
group (P<0.01). Extracellular matrix of left ventricular biopsies (n=9),
quantified by TissueFAXS technology correlated with T1 time (R=0.98; P<0.01). T1
time also correlated with right ventricular-pulmonary arterial coupling
(pulmonary vascular resistance: R=-0.36; P<0.01; right ventricular ejection
fraction: R=0.28; P=0.01).
CONCLUSIONS: In the present preliminary study, cardiac magnetic resoce
postcontrast T1 time is associated with prognosis in HFPEF, suggesting
postcontrast T1 as possible biomarker for HFPEF. The diagnosis of myocarditis can be challenging given that symptoms, clinical
exam findings, electrocardiogram results, biomarkers, and echocardiogram results
are often non-specific. Endocardial biopsy is an established method for
diagnosing myocarditis, but carries the risk of complications and false negative
results. Cardiac magnetic resoce imaging (MRI) has become the primary
non-invasive imaging tool in patients with suspected myocarditis. Myocarditis
can be diagnosed by using three tissue markers including edema,
hyperemia/capillary leak, and necrosis/fibrosis. The interpretation of cardiac
MR findings can be confusing, especially when the myocardium is diffusely
involved. Using T1 and T2 maps, the diagnosis of myocarditis can be made even in
cases of global myocarditis with the help of quantitative analysis. We herein
describe a case of acute global myocarditis which was diagnosed by using
quantitative T1 and T2 mapping. Late gadolinium enhancement is the technique of choice for detecting myocardial
fibrosis. Although this technique is used in a wide range of cardiovascular
pathologies, ischemic cardiomyopathy and the workup for myocarditis and other
cardiomyopathies make up a significant proportion of the total indications.
Multiple studies during the last decade have demonstrated its utility to
adequately characterize myocardial tissue and offer diagnostic and prognostic
information. Recent T1 mapping techniques aim to overcome the limitations of
late gadolinium enhancement to assess diffuse fibrosis. ¹⁹F magnetic resoce
has recently emerged as a promising technique for the assessment of
inflammation. In the following review we will discuss the basic aspects of
fibrosis assessment with MR and its utility for diagnostic and prognostic
evaluation. We will also address the topic of cardiovascular inflammation
imaging with ¹⁹F as a potential new development that may broaden the indications
for MR in the future. Rapid innovations in cardiovascular magnetic resoce (CMR) now permit the
routine acquisition of quantitative measures of myocardial and blood T1 which
are key tissue characteristics. These capabilities introduce a new frontier in
cardiology, enabling the practitioner/investigator to quantify biologically
important myocardial properties that otherwise can be difficult to ascertain
clinically. CMR may be able to track biologically important changes in the
myocardium by: a) native T1 that reflects myocardial disease involving the
myocyte and interstitium without use of gadolinium based contrast agents (GBCA),
or b) the extracellular volume fraction (ECV)-a direct GBCA-based measurement of
the size of the extracellular space, reflecting interstitial disease. The latter
technique attempts to dichotomize the myocardium into its cellular and
interstitial components with estimates expressed as volume fractions. This
document provides recommendations for clinical and research T1 and ECV
measurement, based on published evidence when available and expert consensus
when not. We address site preparation, scan type, scan planning and acquisition,
quality control, visualisation and analysis, technical development. We also
address controversies in the field. While ECV and native T1 mapping appear
destined to affect clinical decision making, they lack multi-centre application
and face significant challenges, which demand a community-wide approach among
stakeholders. At present, ECV and native T1 mapping appear sufficiently robust
for many diseases; yet more research is required before a large-scale
application for clinical decision-making can be recommended. BACKGROUND: Diffuse interstitial fibrosis is present in diverse cardiomyopathies
and associated with poor prognosis. We investigated whether magnetic resoce
imaging-based T1 mapping could quantify the induction and pharmacological
suppression of diffuse cardiac fibrosis in murine pressure-overload hypertrophy.
METHODS AND RESULTS: Mice were subjected to transverse aortic constriction or
sham surgery. The angiotensin receptor blocker losartan was given to half the
animals. Cine-magnetic resoce imaging performed at 7 and 28 days showed
hypertrophy and remodeling and systolic and diastolic dysfunction in transverse
aortic constriction groups as expected. Late gadolinium-enhanced magnetic
resoce imaging revealed focal signal enhancement at the inferior right
ventricular insertion point of transverse aortic constriction mice concordant
with the foci of fibrosis in histology. The extracellular volume fraction,
calculated from pre- and postcontrast T1 measurements, was elevated by
transverse aortic constriction and showed direct linear correlation with
picrosirius red collagen volume fraction, thus confirming the suitability of
extracellular volume fraction as an in vivo measure of diffuse fibrosis.
Treatment with losartan reduced left ventricular dysfunction and prevented
increased extracellular volume fraction, indicating that T1 mapping is sensitive
to pharmacological prevention of fibrosis.
CONCLUSIONS: Magnetic resoce imaging can detect diffuse and focal cardiac
fibrosis in a clinically relevant animal model of pressure overload and is
sensitive to pharmacological reduction of fibrosis by angiotensin receptor
blockade. Thus, T1 mapping can be used to assess antifibrotic therapeutic
strategies. OBJECTIVES: The purpose of this study was to use cardiac magnetic resoce
(CMR) imaging and invasive left ventricular (LV) pressure-volume (PV)
measurements to explore the relationship between diffuse myocardial fibrosis and
indexes of diastolic performance in a cohort of cardiac transplant recipients.
BACKGROUND: The precise mechanism of LV diastolic dysfunction in the presence of
myocardial fibrosis has not previously been established.
METHODS: We performed CMR with T1 mapping and obtained invasive LV PV
measurements via a conductance catheter in 20 cardiac transplant recipients at
the time of clinically-indicated coronary angiography.
RESULTS: Both post-contrast myocardial T1 time and extracellular volume fraction
correlated with β, the load-independent passive LV stiffness constant
(r = -0.71, p = 0.001, and r = 0.58, p = 0.04, respectively). After multivariate
analysis, post-contrast myocardial T1 time remained the only independent
predictor of β. No significant associations were observed between myocardial T1
time and τ, the active LV relaxation constant, or other load-dependent
parameters of diastolic function.
CONCLUSIONS: Diffuse myocardial fibrosis, assessed by post-contrast myocardial
T1 time, correlates with invasively-demonstrated LV stiffness in cardiac
transplant recipients. In patients with increased diffuse myocardial fibrosis,
abnormal passive ventricular stiffness is therefore likely to be a major
contributor to diastolic dysfunction. Author information:
(1)Department of Congenital Heart Disease and Pediatric Cardiology, Deutsches
Herzzentrum Berlin, Augustenburger Platz 1, Berlin 13353, Germany Division of
Imaging Sciences and Biomedical Engineering, St Thomas' Hospital, 4th Floor,
Lambeth Wing, Westminster Bridge Road, London SE1 7EH, UK [email protected].
(2)Department of Congenital Heart Disease and Pediatric Cardiology, Deutsches
Herzzentrum Berlin, Augustenburger Platz 1, Berlin 13353, Germany.
(3)Division of Imaging Sciences and Biomedical Engineering, St Thomas' Hospital,
4th Floor, Lambeth Wing, Westminster Bridge Road, London SE1 7EH, UK Institute
for Biomedical Engineering, University and ETH Zurich, Gloriastrasse 35, Zürich
8092, Switzerland.
(4)Department of Congenital Heart Disease and Pediatric Cardiology, Deutsches
Herzzentrum Berlin, Augustenburger Platz 1, Berlin 13353, Germany Department of
Internal Medicine/Cardiology, Deutsches Herzzentrum Berlin, Augustenburger Platz
1, Berlin 13353, Germany. Cardiac magnetic resoce (CMR) imaging is a well-established noninvasive
imaging modality in clinical cardiology. Its unsurpassed accuracy in defining
cardiac morphology and function and its ability to provide tissue
characterization make it well suited for the study of patients with cardiac
diseases. Late gadolinium enhancement was a major advancement in the development
of tissue characterization techniques, allowing the unique ability of CMR to
differentiate ischemic heart disease from nonischemic cardiomyopathies. Using
T2-weighted techniques, areas of edema and inflammation can be identified in the
myocardium. A new generation of myocardial mapping techniques are emerging,
enabling direct quantitative assessment of myocardial tissue properties in
absolute terms. This review will summarize recent developments involving
T1-mapping and T2-mapping techniques and focus on the clinical applications and
future potential of these evolving CMR methodologies. BACKGROUND: The impact of diffuse atrial fibrosis detected by T1 mapping on the
clinical outcome after atrial fibrillation (AF) ablation is unknown.
OBJECTIVE: This study aimed to validate and assess the impact of post-contrast
cardiac magnetic resoce (CMR) imaging atrial T1 mapping on the clinical
outcome after catheter ablation for AF.
METHODS: CMR imaging was performed in 3 groups by using a clinical 1.5-T
scanner: controls, patients with paroxysmal AF, and patients with persistent AF.
A T1 mapping sequence was used to calculate the post-contrast T1 relaxation time
(T1 time) at the interatrial septum as an index of diffuse atrial fibrosis. A
subset underwent left atrial endocardial bipolar voltage mapping for
electrophysiologic correlation. After AF ablation, patients underwent clinical
review and 7-day Holter monitoring at 6-month intervals.
RESULTS: One hundred thirty-two patients (20 controls, 71 (63%) patients with
paroxysmal AF, and 41 (37%) patients with persistent AF) underwent CMR imaging.
Post-contrast atrial T1 time was significantly shorter in AF groups (237 ± 42
ms) than in controls (280 ± 37 ms) (P < .001). Post-contrast atrial T1 time
correlated with mean septal voltage (R2 = .48; P < .001) and global left atrial
voltage (R(2) = .41; P < .001). A diagnosis of AF, AF duration, and left
ventricular end-diastolic volume independently predicted shortened post-contrast
atrial T1 time. The single procedure success rate was 74% at 12 ± 5 months
postablation. Post-contrast atrial T1 time was the only predictor of arrhythmia
recurrence in multivariate analysis (P = .015). A post-contrast atrial T1 time
of >230 ms was associated with freedom from AF in 85% relative to 62% with a
post-contrast atrial T1 time of <230 ms (P = .01).
CONCLUSION: Post-contrast atrial T1 time as measured using CMR imaging provides
an index of atrial fibrosis that correlates with tissue voltage, presence of AF,
and clinical outcomes after catheter ablation. Cardiac magnetic resoce (MR) imaging has grown over the past several decades
into a validated, noninvasive diagnostic imaging tool with a pivotal role in
cardiac morphologic and functional assessment and tissue characterization. With
traditional cardiac MR imaging sequences, assessment of various pathologic
conditions ranging from ischemic and nonischemic cardiomyopathy to cardiac
involvement in systemic diseases (eg, amyloidosis and sarcoidosis) is possible;
however, these sequences are most useful in focal myocardial disease, and image
interpretation relies on subjective qualitative analysis of signal intensity.
Newer T1 and T2 myocardial mapping techniques offer a quantitative assessment of
the myocardium (by using T1 and T2 relaxation times), which can be helpful in
focal disease, and demonstrate special utility in the evaluation of diffuse
myocardial disease (eg, edema and fibrosis). Altered T1 and T2 relaxation times
in disease states can be compared with published ranges of normal relaxation
times in healthy patients. In conjunction with traditional cardiac MR imaging
sequences, T1 and T2 mapping can limit the interpatient and interstudy
variability that are common with qualitative analysis and may provide clinical
markers for long-term follow-up. |
Which autophagy pathway is trigered by the KFERQ motif of cytosolic proteins? | Cytosolic proteins carrying the KFERQ motif (a specific lysosomal import consensus sequence) are directed to a selective form of lysosomal degradation, called chaperone-mediated autophagy (CMA), as chaperone protein Hsc73 and other chaperones are involved in this process. | Annexins are a family of proteins that bind phospholipids in a calcium-dependent
manner. Analysis of the sequences of the different members of the annexin family
revealed the presence of a pentapeptide biochemically related to KFERQ in some
annexins but not in others. Such sequences have been proposed to be a targeting
sequence for chaperone-mediated autophagy, a lysosomal pathway of protein
degradation that is activated in confluent cells in response to removal of serum
growth factors. We demonstrate that annexins II and VI, which contain KFERQ-like
sequences, are degraded more rapidly in response to serum withdrawal, while
annexins V and XI, without such sequences, are degraded at the same rate in the
presence and absence of serum. Using isolated lysosomes, only the annexins
containing KFERQ-like sequences are degraded by chaperone mediated-autophagy.
Annexins V and XI could associate with lysosomes but did not enter the lysosomes
and were not proteolytic substrates. Furthermore, four annexins containing
KFERQ-like sequences, annexins I, II, IV, and VI, are enriched in lysosomes with
high chaperone-mediated autophagy activity as expected for substrate proteins.
These results provide striking evidence for the importance of KFERQ motifs in
substrates of chaperone-mediated autophagy. PURPOSE OF REVIEW: Although the suppression of protein breakdown plays a major
role in the growth of the adult kidney in conditions that cause renal
hypertrophy, the pathways responsible for controlling proteolysis and the
substrates being destroyed have only recently been investigated. This review
focuses on the role of the ubiquitin-proteasome pathway in regulating specific
substrates during kidney growth, and the role of the lysosomal pathways in the
suppression of general protein breakdown and of the substrates of
chaperone-mediated autophagy.
RECENT FINDINGS: New insights into the regulation of specific ubiquitin ligases
demonstrate how the cell controls the destruction of particular substrates
important for growth, including hypoxia-inducible factors and the cell cycle
inhibitor, p27. In cell culture, growth factors suppress the lysosomal pathway
of chaperone-mediated autophagy leading to the accumulation of specific
cytoplasmic proteins containing KFERQ motifs. In a variety of systems, including
cultured renal tubular cells, phosphoinositol 3 kinase activity and its
downstream mediators control lysosomal proteolysis.
SUMMARY: Specific ubiquitin ligases and the pathways that control their
substrate recognition may be key signalling intermediaries for cell growth, but
global alterations in lysosomal pathways account for the decrease in general
proteolysis. Functional KFERQ motifs mark proteins that are important in renal
growth, including enzymes responsible for the characteristic shift to glycolytic
metabolism during growth, transcription factors, and signalling molecules. As
altering phosphoinositol 3 kinase changes patterns of vesicular trafficking, it
is possible that the regulation of intracellular trafficking may underlie the
changes seen in lysosomal proteolysis with growth. BACKGROUND: In the renal hypertrophy that occurs in diabetes mellitus, decreased
proteolysis may lead to protein accumulation, but it is unclear which proteins
are affected. Because the lysosomal proteolytic pathway of chaperone-mediated
autophagy is suppressed by growth factors in cultured cells, we investigated
whether the abundance of substrates of this pathway increase in diabetic
hypertrophy.
METHODS: Rats with streptozotocin (STZ)-induced diabetes were pair-fed with
vehicle-injected control rats. Proteolysis was measured as lysine release in
renal cortical suspensions and protein synthesis as phenylalanine incorporation.
Target proteins of chaperone-mediated autophagy were measured in cortical
lysates and nuclear extracts by immunoblot analysis. Proteins that regulate
chaperone-mediated autophagy [the lysosomal-associated membrane protein 2a
(LAMP2a) or the heat shock cognate protein of 73 kD (hsc-73)] were measured in
lysosomes isolated by density gradient centrifugation.
RESULTS: Proteolysis decreased by 41% in diabetic rats; protein synthesis
increased at 3 days, but returned to baseline by 7 days. The abundance of
proteins containing that chaperone-mediated autophagy KFERQ signal motif
increased 38% and individual KFERQ containing proteins [e.g., M2 pyruvate
kinase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and pax2] were more
abundant. LAMP2a and hsc73 decreased by 25% and 81%, respectively, in cortical
lysosomes from diabetic vs. control rats.
CONCLUSION: The decline in proteolysis in acute diabetes mellitus is associated
with an increase in proteins degraded by chaperone-mediated autophagy and a
decrease in proteins which regulate this pathway. This study provides the first
evidence that reduced chaperone-mediated autophagy contributes to accumulation
of specific proteins in diabetic-induced renal hypertrophy. The structure of several lysosomal membrane glycoproteins (lamp1, lamp2, limpI
and limpII) has been described. The significance of the receptor glycoprotein
lamp2a in the chaperone-mediated autophagy of cytosolic proteins with KFERQ
motif has been described in details as well as the chaperone protein Hsc73 and
other chaperones involved in this process. Several modulatory mechanisms of the
chaperone-mediated autophagy, which is activated in condition of stress and
starvation, were also outlined. Different mechanisms target intracellular components for their degradation into
lysosomes through what is known as autophagy. In mammals, three main forms of
autophagy have been described: macroautophagy, microautophagy, and
chaperone-mediated autophagy (CMA). CMA is the only autophagic pathway that
allows selective degradation of soluble proteins in lysosomes. In contrast to
the other mammalian forms of autophagy, CMA does not require vesicle formation
or major changes in the lysosomal membrane. Instead, substrate proteins directly
cross the lysosomal membrane to reach the lumen, where they are rapidly
degraded. The substrate proteins are targeted to the lysosomal membrane by
recognition of a targeting motif (a KFERQ-like motif), by a chaperone complex,
consisting of hsc70 and its cochaperones, in the cytoplasm. Once at the
lysosomal membrane, the protein interacts with a lysosomal receptor for this
pathway, lysosomal associated membrane protein type 2A (LAMP-2A), and it is
translocated across the membrane into the lysosomal lumen assisted by a lysosome
resident chaperone. These two characteristics--selectivity and direct substrate
translocation--determine the particular role of CMA in different physiological
and pathological conditions. In this chapter, we cover current findings on the
molecular mechanisms for CMA and the possible pathophysiological relevance of
this selective lysosomal degradation. Promoting the degradation of Hsp90 client proteins by inhibiting Hsp90, an
important protein chaperone, has been shown to be a promising new anticancer
strategy. In this study, we show that an oxazoline analogue of apratoxin A
(oz-apraA), a cyclodepsipeptide isolated from a marine cyanobacterium, promotes
the degradation of Hsp90 clients through chaperone-mediated autophagy (CMA). We
identify a KFERQ-like motif as a conserved pentapeptide sequence in the kinase
domain of epidermal growth factor receptor (EGFR) necessary for recognition as a
CMA substrate. Mutation of this motif prevents EGFR degradation by CMA and
promotes the degradation of EGFR through the proteasomal pathway in
oz-apraA-treated cells. Oz-apraA binds to Hsc70/Hsp70. We propose that apratoxin
A inhibits Hsp90 function by stabilizing the interaction of Hsp90 client
proteins with Hsc70/Hsp70 and thus prevents their interactions with Hsp90. Our
study provides the first examples for the ability of CMA to mediate degradation
of membrane receptors and cross talks of CMA and proteasomal degradation
mechanisms. A single cell has the potential to kill an entire human being. Efforts to cure
cancer are limited by survival of individual cancer cells despite immune
surveillance and toxic therapies. Understanding the intricate network of
pathways that maintain cellular homeostasis and mediate stress response or
default into cell death is critical to the development of strategies to
eradicate cancer. Autophagy, proteasomal degradation and the unfolded protein
response (UPR) are cellular pathways that degrade and recycle excess or damaged
proteins to maintain cellular homeostasis and survival. This review will discuss
autophagy and how it is integrated with proteasomal degradation and UPR to
govern cell fate through restoration of cellular homeostasis or default into the
apoptotic cell death pathway. The first response of autophagy is macroautophagy,
which sequesters cytoplasm including organelles inside double-membraned
autophagosome vesicles that fuse with lysosomes to degrade and recycle the
contents. Ubiquitination patterns on proteins targeted for degradation determine
whether adapter proteins will bring them to developing autophagosomes or to
proteasomes. Macroautophagy is followed by chaperone-mediated autophagy (CMA),
in which Hsc70 (Heat shock cognate 70) selectively binds proteins with exposed
KFERQ motifs and pushes them inside lysosomes through the LAMP-2A
(Lysosome-associated membrane protein type 2A) receptor. These two processes and
the lesser understood microautophagy, which involves direct engulfment of
proteins into lysosomes, occur at basal and induced levels. Insufficient
proteasome function or ER stress induction of UPR can induce autophagy, which
can mitigate damage and stress. If this network is incapable of repairing the
damage or overcoming continued stress, the default pathway of apoptosis is
engaged to destroy the cell. Induction of macroautophagy by cancer therapeutics
has led to clinical trials investigating combinations of HCQ
(hydroxychloriquine) suppression of autophagy with apoptosis-inducing agents.
Further study of the complex integration of autophagy, proteasomal degradation,
UPR and apoptosis is likely to provide additional targets for our fight against
cancer. This article is part of a Special Issue entitled "Apoptosis: Four
Decades Later". AIMS: Chaperone-mediated autophagy (CMA) is a selective mechanism for the
degradation of soluble cytosolic proteins bearing the sequence KFERQ. These
proteins are targeted by chaperones and delivered to lysosomes where they are
translocated into the lysosomal lumen and degraded via the lysosome-associated
membrane protein type 2A (LAMP-2A). Mutations in LAMP2 that inhibit autophagy
result in Danon disease characterized by hypertrophic cardiomyopathy. The
ryanodine receptor type 2 (RyR2) plays a key role in cardiomyocyte
excitation-contraction and its dysfunction can lead to cardiac failure. Whether
RyR2 is degraded by CMA is unknown.
METHODS AND RESULTS: To induce CMA, cultured neonatal rat cardiomyocytes were
treated with geldanamycin (GA) to promote protein degradation through this
pathway. GA increased LAMP-2A levels together with its redistribution and
colocalization with Hsc70 in the perinuclear region, changes indicative of CMA
activation. The inhibition of lysosomes but not proteasomes prevented the loss
of RyR2. The recovery of RyR2 content after incubation with GA by siRNA
targeting LAMP-2A suggests that RyR2 is degraded via CMA. In silico analysis
also revealed that the RyR2 sequence harbours six KFERQ motifs which are
required for the recognition Hsc70 and its degradation via CMA. Our data suggest
that presenilins are involved in RyR2 degradation by CMA.
CONCLUSION: These findings are consistent with a model in which oxidative damage
of the RyR2 targets it for turnover by presenilins and CMA, which could lead to
removal of damaged or leaky RyR2 channels. The transcription factor HIF1 is mostly regulated by the oxygen-dependent
proteasomal degradation of the labile subunit HIF1A. Recent data showed
degradation of HIF1A in the lysosome through chaperone-mediated autophagy (CMA).
However the molecular mechanism involved has not been elucidated. This study
shows that the KFERQ-like motif, that has been identified in all CMA substrates,
is required to mediate the interaction between HIF1A and the chaperone HSPA8.
Moreover, mutations in the KFERQ-like motif of HIF1A preclude the interaction
with the CMA receptor LAMP2A, thus inhibiting its lysosomal degradation.
Importantly, we show for the first time that the ubiquitin ligase STUB1 is
required for degradation of HIF1A in the lysosome by CMA. Indeed, mutations in
STUB1 that inhibit either the ubiquitin ligase activity or its ability to bind
to HSPA8, both prevent degradation of HIF1A by CMA. Moreover, we show that HIF1A
binds to and is translocated into intact lysosomes isolated from rat livers.
This new pathway for degradation of HIF1A does not depend on the presence of
oxygen and is activated in response to nutrient deprivation such that the levels
of HIF1A bound to CMA positive lysosomes significantly increase in starved
animal livers and the binding of HIF1A to LAMP2A increases in response to serum
deprivation. Moreover, excessive degradation of HIF1A by CMA compromises cells'
ability to respond to and survive under hypoxia, suggesting that this pathway
might be of pathophysiological importance in conditions that combine hypoxia
with starvation. Mutant N-terminal huntingtin (Htt) protein resulting from Huntington's disease
(HD) with expanded polyglutamine accumulates and forms aggregates in vulnerable
neurons. Both ubiquitin proteasomal and autophagic pathways contribute to the
degradation of mutant Htt. Here, we focus on the involvement of
chaperone-mediated autophagy (CMA), a selective form of autophagy in the
clearance of Htt. Selective catabolism in CMA is conferred by the presence of a
KFERQ-like targeting motif in the substrates, by which molecular chaperones
recognize the hydrophobic surfaces of the misfolded substrates, and transfer
them to the lysosomal membrane protein type-2A, LAMP-2A. The substrates are
taken into the lysosomes through LAMP-2A and are rapidly degraded by the
lysosomal enzymes. Taken together, we summarize the recent evidence to elucidate
that Htt is also a potential substrate of CMA. We propose that the manipulation
of CMA could be a therapeutic strategy for HD. |
Which are the clinical characteristics of TSC? | Tuberous sclerosis or tuberous sclerosis complex (TSC) is a rare multi-system genetic disease that causes benign tumors to grow in the brain and on other vital organs such as the kidneys, heart, eyes, lungs, and skin. A combination of symptoms may include seizures, intellectual disability, developmental delay, behavioral problems, skin abnormalities, lung and kidney disease. TSC is caused by a mutation of either of two genes, TSC1 and TSC2, which code for the proteins hamartin and tuberin respectively. These proteins act as tumor growth suppressors, agents that regulate cell proliferation and differentiation. | Three cases with unusual manifestations of phakomatosis are reported. The first
two had clinical symptoms of neurofibromatosis but CT disclosed nodular
subependymal calcifications as in tuberous sclerosis. The third one presented
with cerebral calcifications as found in both tuberous sclerosis and
Sturge-Weber syndrome, though he had no clinical symptoms of phakomatosis. Cardiac tumours have been frequently reported in patients with tuberous
sclerosis but their incidence at different ages has been evaluated in only a few
studies. We performed echocardiography in 47 children with tuberous sclerosis
and found tumours in 22 (47%). In none, except one newborn, did we observe any
clinical symptoms of heart failure. Tumours were more frequent in children below
2 years of age (91%) than in older children. As other signs of tuberous
sclerosis are often absent in infants, echocardiography may be regarded as the
most useful diagnostic test at this age. Follow up studies were done in 12
children and tumour regression occurred in 6 patients. Observation's analysis of 5 children in age from 9 months to 4 years 11 months
with tuberous sclerosis was performed. The initial manifestations of disease
were following: early children form of epilepsy exactly infantile spasms (West
syndrome) appearance, dermal alterations in the form of depigmented spots as
well as nonprogressive delay in psychoverbal development. Together with clinical
symptoms the main criterion in early form of tuberous sclerosis diagnosis
determination turned out to be brain's specific alterations (tubers) which were
revealed by computer tomography. The correlation was observed between epileptic
seizures polymorphism and frequency as well as brain's morphological
alterations. Derivatives of valproic acid were the basic drugs in treatment of
epileptic seizures in patients. The authors report their experience of 11 cases of renal angiomyolipoma over an
interval of 20 years, observed in 10 women (90.9%) and one man (9.1%) with a
mean age of 46 years (range: 21 to 63). Clinical symptoms were dominated by loin
pain (100%), haematuria (45.4%), lumbar mass (72.7%), fever (18%). In one woman,
AML was associated with "tuberous sclerosis". Preoperatively, the diagnosis was
established by ultrasound and CT scan in 45.4% of patients. The size of the
tumour varied from 7 to 14 cm in 10 patients and in one patient was only about
3.6 cm. Two women had bilateral tumours. Treatment consisted of total
nephrectomy in 7 patients, partial nephrectomy in 3 patients and tumourectomy in
one patient. The purpose of this study is to analyse the epidemiologic,
diagnostic and therapeutic aspects of this disease. Cytogenetic analysis of subependymal giant-cell astrocytomas (SEGAs) from two
patients presenting the clinical symptoms of tuberous sclerosis complex (TSC)
revealed clonal chromosomal changes, resulting in the partial loss of chromosome
22q in both tumors. Immunohistochemically, tumors exhibited features of glial
differentiation, while ultrastructural studies identified the characteristic
paracrystalline inclusions within the tumor cells. To our knowledge, it is the
first cytogenetic description of SEGAs associated with TSC. The morphology of pancreatic endocrine tumors (PETs) is similar to that of
endocrine tumors elsewhere in the body. PETs are usually encountered in adults.
They may be clinically functional and associated with various syndromes related
to hormone excess. However, it must be remembered that absence of obvious
clinical symptoms may not necessarily reflect true lack of clinical function,
and subtle clinical manifestations may be missed. Current thinking indicates
that PETs arise from totipotential stem cells as well as preexisting endocrine
cells. PETs may be hereditary or sporadic. The hereditary forms are associated
with multiple endocrine neoplasia type 1 (MEN-1), von Hippel-Lindau syndrome,
neurofibromatosis, and tuberous sclerosis. In sporadic PETs, the most consistent
and recurring chromosomal abnormality is allelic loss of chromosome 11q, which
includes the MEN-1 locus. Loss of a sex chromosome has been shown to be
associated with metastasis, local invasion, and poor survival. BACKGROUND: Tuberous sclerosis complex (TSC) is an autosomal, domitly
inherited neurocutaneous syndrome characterized by a wide range of neurological
abnormalities, tumors of different organs, and variable clinical symtomatology
and severity. TSC is caused by mutations in either of two tumor suppressor
genes: TSC1 or TSC2. The aim of this study was to analyze the clinical picture
of TSC in patients with an identical TSC2 mutation. We tried to discover to what
extent we may expect variability in the clinical set of symptoms in patients
with identical mutation of TSC2 gene.
MATERIAL/METHODS: Mutations were identified in 100 of 170 cases. There were only
4 patients with the same type of TSC2 mutation: 5238-5255 del 18bp, del 1746
HIKRLR. Their ages were 1.5, 9, 9, and 10 years. A standardized clinical
assessment of TSC symptoms was used.
RESULTS: Epilepsy, depigmented spots, and periventricular calcification and
cortical tubers were diagnosed in all the 4 patients, cardiac rhabdomyoma and
angiomyolipoma of the kidneys in 3, and mental retardation and forehead fibroma
in 2. Other symptoms occurred rarely or were absent. There was variability in
TSC symptoms in patients with the identical type of TSC2 mutation. The main
symptoms were present in all or in the majority of patients. Clinical picture
also differed with the age of patient.
CONCLUSIONS: There are many influencing factors contributing to the diversity of
the clinical picture and pathology of TSC. Obviously, a greater number of cases
are needed for further analysis and more precise conclusions. Sirolimus is one of the intensively investigated drugs with pluripotent
activities. It binds to its intracellular receptor FKBP12 (FK506-binding protein
12), a member of the family of FK506-binding proteins, and inhibits the activity
of mTOR, a serine/threonine kinase involved in numerous cell processes linked to
cell growth control. The drug is currently registered for the prophylaxis of
organ rejection and for use in coronary stents. However, unique characteristics
of sirolimus make it a good candidate for anti-cancer therapy. Indeed, phase II
and III clinical studies in humans with several types of neoplasms are already
under way. The review describes molecular activity of sirolimus and its analogs,
characteristic for specific applications, in view of very recent advances
involving tuberous sclerosis complex (TSC)-mediated signaling pathways. Current
studies with sirolimus performed in tuberous sclerosis animal models are
presented. Possible application of sirolimus for treating tuberous sclerosis,
disease caused by mutations of TSC proteins, is discussed. Mutations in one of two genes, TSC1 and TSC2, result in a similar disease
phenotype by disrupting the normal interaction of their protein products,
hamartin and tuberin, which form a functional signaling complex. Disruption of
these genes in the brain results in abnormal cellular differentiation,
migration, and proliferation, giving rise to the characteristic brain lesions of
tuberous sclerosis complex (TSC) called cortical tubers. The most devastating
complications of TSC affect the central nervous system and include epilepsy,
mental retardation, autism, and glial tumors. Relevant animal models, including
conventional and conditional knockout mice, are valuable tools for studying the
normal functions of tuberin and hamartin and the way in which disruption of
their expression gives rise to the variety of clinical features that
characterize TSC. In the future, these animals will be invaluable preclinical
models for the development of highly specific and efficacious treatments for
children affected with TSC. Two patients with typical tuberous sclerosis complex (TSC) associated with
cervical or dorsal-lumbar hydrosyringomielia are described for the first time.
Syringomielic cavities are small in extension in both cases, leading to
significant clinical symptoms as bilateral pes cavus and scoliosis in one
patient only. So far, tuberous sclerosis had not been reported to involve
primarily the spinal cord, and other factors directly linked to syringomiely are
not present in both these patients. We performed a genome-wide analysis of transcriptional start sites (TSSs) in
human genes by multifaceted use of a massively parallel sequencer. By analyzing
800 million sequences that were obtained from various types of transcriptome
analyses, we characterized 140 million TSS tags in 12 human cell types. Despite
the large number of TSS clusters (TSCs), the number of TSCs was observed to
decrease sharply with increasing expression levels. Highly expressed TSCs
exhibited several characteristic features: Nucleosome-seq analysis revealed
highly ordered nucleosome structures, ChIP-seq analysis detected clear RNA
polymerase II binding signals in their surrounding regions, evaluations of
previously sequenced and newly shotgun-sequenced complete cDNA sequences showed
that they encode preferable transcripts for protein translation, and RNA-seq
analysis of polysome-incorporated RNAs yielded direct evidence that those
transcripts are actually translated into proteins. We also demonstrate that
integrative interpretation of transcriptome data is essential for the selection
of putative alternative promoter TSCs, two of which also have protein
consequences. Furthermore, discriminative chromatin features that separate TSCs
at different expression levels were found for both genic TSCs and intergenic
TSCs. The collected integrative information should provide a useful basis for
future biological characterization of TSCs. BACKGROUND: Takotsubo cardiomyopathy (TSC) and its complications, such as
cardiac rupture (CR), are increasingly being reported in the literature. CR is
associated with rapid clinical decline and is uniformly fatal if not surgically
repaired. To identify patients who developed CR we performed an analysis of all
available indexed cases in the literature and compared them with a control group
of patients with TSC without rupture.
HYPOTHESIS: Takotsubo cardiomyopathy patients with cardiac rupture do not differ
significantly from those without rupture.
METHODS: MEDLINE (2009) was searched for all TSC case reports with CR. Eleven
case reports were identified. Using a random sampling method, we selected 12
case reports of TSC without rupture (control). We included our patient with TSC
with rupture as the 12th case of TSC cohort with CR (CR group). Demographic and
clinical characteristics were compared between CR group and control.
RESULTS: All patients in the TSC group with rupture were female and were
significantly older than controls. TSC group with rupture had significantly
higher frequency of ST elevation in lead II and absence of T-wave inversion in
lead V5 on hospital admission than controls. Mean ejection fraction, systolic
blood pressure, and double product, a measure of oxygen demand, was
significantly higher in the rupture group compared to controls. The CR group was
associated with less frequent use of β-blocker as compared to controls.
CONCLUSIONS: CR as a complication of TSC could be more common than recognized.
Higher double product and ejection fraction suggest higher fluctuation of
intracardiac pressure and may cause CR in TSC. Use of β blockers in TSC may
provide protection against CR. Tuberous sclerosis complex (TSC) is an autosomal domit disorder that is among
the most common genetic causes of epilepsy. Focal brain lesions in TSC, known as
cortical tubers, have been implicated in promoting epileptogenesis in TSC.
Histological, cellular, and molecular abnormalities in astrocytes are
characteristic features of tubers and perituberal cortex, suggesting that
astrocyte dysfunction may contribute to the pathophysiology of epilepsy in TSC.
Numerous astrocytes can be seen histologically in tubers expressing glial
fibrillary acidic and S100 proteins. In some analyses, astrocytes exhibit
enhanced activation of the mammalian target of rapamycin suggesting a link
between TSC1 and TSC2 mutations and astrocytic proliferation. Astrocytic
proliferation in subependymal giant cell astrocytoma is associated with
progressive growth and compression of surrounding brain structures by these
lesions. Increased numbers of enlarged astrocytes has been observed in several
TSC mouse models and may be intimately linked to epileptogenesis. Impairment of
astrocytic buffering mechanisms for glutamate and potassium has been identified
in TSC animal models and human tuber tissue and likely promotes neuronal
excitability and seizures in TSC. Targeting these defects in astrocytes may
represent a novel therapeutic strategy for epilepsy in patients with TSC. INTRODUCTION: Tuberous sclerosis complex (TSC) is one of the most frequent
neurocutaneous disorders. Cortical tubers are the most common pathological
changes in TSC and they are directly related to the disease's main clinical
manifestations: seizures, mental retardation, and autistic behaviour.
OBJECTIVE: The aim of this study is to establish a correlation between tuber
size and the severity of clinical features in TSC.
MATERIAL AND METHODS: We performed a retrospective study of the clinical and
imaging findings from 45 TSC patients (22 females and 23 males) and compared the
clinical features with the location, size, and number of the cortical tubers in
each patient.
RESULTS: Four patients had voluminous tubers located in 1 or both cerebral
hemispheres. All of these patients had intractable seizures and severe mental
retardation; 3 of these cases also presented with autistic behaviour, despite
tubers having been resected in all 4 patients. Thirteen patients had tubers of
large-to-average size, and all patients in this group showed intractable
seizures and mental retardation. Nine patients who had experienced infantile
spasms during the first year of life presented autistic behaviour. Multiple
tubers of small to average size were found in 28 patients. In general, this
group had seizures that responded well to antiepileptic drugs and a low
prevalence of autism. In 3 patients who all presented good seizure control and
normal intelligence, single cortical/subcortical tubers were located in the
frontal or occipital lobes. Of the total of 45 patients, 13 had cerebellar as
well as cerebral tubers; these were generally present in cases with more severe
clinical features.
CONCLUSIONS: Although large tubers are less common than small to medium-sized
ones, they are much more likely to be accompanied by severe clinical symptoms
(seizures, mental retardation and autistic behaviour), even when the smaller
tubers are quite numerous. Author information:
(1)Department of Endocrinology, Medwin Hospital, Hyderabad, Andhra Pradesh,
India. OBJECTIVE: To explore the diagnosis and treatment of tuberous sclerosis complex
complicated with renal angiomyolipoma.
METHODS: The clinical data of 22 patients with tuberous sclerosis complex
complicated with renal angiomyolipoma were analyzed retrospectively.
RESULTS: There were 12 males and 10 females with a mean age of 23 (1-46) years.
All of them had bilateral multiple renal angiomyolipomas. The mean tumor size
was 8.5 (0.7-18.0) cm in diameter. The presence or absence of clinical symptoms
showed a significant correlation with tumor size.Eight patients with
angiomyolipoma under 4 cm in diameter were continuously monitored at an
outpatient clinic. There were 8 patients with lesions of 4-10 cm.Five of them
underwent nephron-sparing surgeries and another 3 monitored at an outpatient
clinic. There were 6 patients with tumor over 10 cm. Three of them underwent
transcatheter arterial embolization and one case took rapamycin after
embolization.One patient with concurrent renal cell carcinoma underwent partial
nephrectomy. Chronic renal failure occurred in one case dying of pulmonary
lymphangiomyomatosis with serious hemoptysis. During a mean follow-up of 25
months, neither severe renal hemorrhage nor symptomatic aggravation was found.In
the case of rapamycin, there was 10% reduction in the size of angiomyolipoma.
CONCLUSIONS: Most cases of tuberous sclerosis complex are complicated with
bilateral multiple renal angiomyolipoma. The small lesions under 4 cm in
diameter may be monitored at an outpatient clinic.For those larger (>4 cm) or
symptomatic ones, medication, embolization or surgery is necessary. |
How does dabigatran therapy affect aPTT in patients with atrial fibrillation? | Dabigatran increases aPTT in patients with atrial fibrillation, although aPTT does not respond linearily to dabigatran therapy. | BACKGROUND: The distribution of activated partial thromboplastin time (APTT) in
nonvalvular atrial fibrillation (NVAF) patients under dabigatran therapy remains
to be clarified.
METHODS AND RESULTS: The study population was 196 NVAF patients who were treated
with dabigatran in 2011 (126 with 220 mg/day). The APTT values showed a wide
distribution among the patients, especially in those with a reduced dose, who
seemed to show a high value even in patients without contraindications.
CONCLUSIONS: We found a wide distribution of APTT in NVAF patients under
dabigatran treatment. High APTT might help screen for bleeding risks among
patients under dabigatran, but requires future investigation. We describe the use of intravenous thrombolysis with recombit tissue
plasminogen activator (IV-rtPA) in a patient with concomitant dabigatran use. A
64-year-old man with a history of coronary artery disease, pacemaker placement,
and atrial fibrillation developed acute right arm/face weakness and dysarthria.
He was unable to list his home medications. His platelet count was 167 × 10(9)/L
(normal 150-399 × 10(9)/L), and his activated partial thromboplastin time (aPTT)
was 37.6 seconds (normal 24.0-33.0 seconds). His international normalized ratio
(INR) was 1.1. He received IV-rtPA at 3 hours and 25 minutes after the onset of
symptoms. After IV-rtPA was administered, it was discovered that the patient had
been taking dabigatran for 2 months. After IV-rtPA, the patient developed severe
superficial left arm ecchymoses but remained without cerebral complications. On
poststroke day 1, his fibrinogen level was low at 63 mg % (normal 190-395 mg %),
his aPTT was normal at 33, and his INR was elevated at 1.72 but decreased to
1.18 on the following day. Repeat computed tomographic imaging of his brain
confirmed a left middle cerebral artery ischemic cortical infarct. We report a
case of an acute stroke patient taking dabigatran who received IV-rtPA. In the
acute stroke setting, clinicians should be aware of the increasing use of
dabigatran in patients with atrial fibrillation when considering IV-rtPA.
Although aPTT does not provide a linear response to dabigatran therapy, the
presence of a completely normal PTT may exclude therapeutic dabigatran
anticoagulation. BACKGROUND: Dabigatran etexilate is a new oral anticoagulant for the therapy and
prophylaxis of venous thromboembolism and stroke prevention in patients with
atrial fibrillation. To investigate the extent of interactions of this new
anticoagulant with frequently used coagulation assays, we completed a
multicenter in vitro trial with Conformité Européenne(CE)-labeled
dabigatran-spiked plasma samples.
METHODS: Lyophilized plasma samples with dabigatran concentrations ranging from
0.00 to 0.48 μg/mL were sent to the coagulation laboratories of six major
Austrian hospitals for evaluation. Coagulation assays were performed under
routine conditions using standard reagents and analyzer.
RESULTS: Dabigatran led to a dose-dependent prolongation of the clotting times
in coagulometric tests and influenced the majority of the parameters measured.
Statistically significant interference could be observed with the prothrombin
time (PT), activated partial thromboplastin time (aPTT) and PT/aPTT-based assays
(extrinsic/intrinsic factors, APC-resistance test) as well as lupus
anticoagulant testing. Even non-clotting tests, such as the colorimetric factor
XIII activity assay and to a minor extent the amidolytic antithrombin activity
assay (via factor IIa) were affected.
CONCLUSIONS: This multicenter trial confirms and also adds to existing data,
demonstrating that laboratories should expect to observe strong interferences of
coagulation tests with increasing concentrations of dabigatran. This finding
might become particularly important in the elderly and in patients with renal
impairment as well as patients whose blood is drawn at peak levels of
dabigatran. BACKGROUND: Dabigatran has demonstrated promising results for the prevention of
strokes in patients with non-valvular atrial fibrillation (NVAF). However, there
have been episodes of major bleeding, especially in elderly patients or those
with renal dysfunction. The purpose of this study was to retrospectively examine
the relationship between the bleeding events and activated partial
thromboplastin time (APTT) values under dabigatran usage in the everyday
clinical practice. Moreover, we investigated which factors would contribute to
the APTT values.
METHODS AND RESULTS: A total of 139 NVAF patients (112 men, 65 ± 11 years) were
included. We evaluated the influence of the putative etiological variables and
the bleeding score, HAS-BLED score, on APTT values: age greater than 70 years,
renal function, gender, dose of dabigatran, and the concomitant prescription of
a P-glycoprotein inhibitor. There were 50 patients with an age of ≥ 70 years
(36.0%). A P-glycoprotein inhibitor was administered in 18 patients. During the
observation period (median 120 days) there was 1 episode of asymptomatic
cerebral infarction. There were no intrinsic major bleeding events, however, 11
patients had minor hemorrhagic events. The results of the APTT measurements
exhibited a variety of values both among inter- and intra-individuals. On
multivariable analysis, significant associations were found between the
following risk factors and the APTT values: creatinine clearance, dose of
dabigatran, and concomitant use of a P-glycoprotein inhibitor. The minor
bleeding events did not correlate with the APTT values, nor HAS-BLED score.
CONCLUSIONS: The APTT values became prolonged under dabigatran usage and
exhibited a remarkable diversity. Although major bleeding did not occur unless
APTT was prolonged excessively, minor bleeding arose irrespective of the APTT
values even within the range of the APTT values not exceeding 80s. BACKGROUND: Dabigatran is an oral direct thrombin inhibitor for which routine
laboratory monitoring is currently not recommended. However, there are
situations in which measurements of the drug and its effect are desirable. We
therefore compared and validated different coagulation methods for assessments
of dabigatran in clinical samples in relation to measurements of plasma
dabigatran, without the purpose of establishing effective and safe
concentrations of dabigatran in plasma.
METHODS: Samples were obtained from 70 atrial fibrillation patients treated with
dabigatran etexilate. Plasma concentrations were measured using liquid
chromatography-tandem mass spectrometry (LC-MS/MS) and were compared with
coagulation methods Hemoclot thrombin inhibitors (HTI) and Ecarin clotting assay
(ECA), as well as with prothrombin time-international normalized ratio (PT-INR)
and activated partial thromboplastin time (aPTT).
RESULTS: A wide range of dabigatran concentrations was determined by LC-MS/MS
(<0.5-586 ng/mL). Correlations between LC-MS/MS results and estimated
concentrations were excellent for both HTI and ECA overall (r(2) = 0.97 and 0.96
respectively, p < 0.0001), but the precision and variability of these assays
were not fully satisfactory in the low range of dabigatran plasma
concentrations, in which ECA performed better than HTI. aPTT performed poorly,
and was normal (<40 s) even with dabigatran levels of 60 ng/mL. PT-INR was
normal even at supratherapeutic dabigatran concentrations.
CONCLUSION: LC-MS/MS is the gold standard for measurements of dabigatran in
plasma. Alternatively, either HTI or ECA assays may be used, but neither of
these assays is dependable when monitoring low levels or to infer total absence
of dabigatran. The aPTT assay is relatively insensitive to dabigatran, and
normal aPTT results may be observed even with therapeutic dabigatran
concentrations. Introduction. Dabigatran is an oral direct thrombin inhibitor which has been
approved for prophylaxis of stroke in patients with atrial fibrillation. The use
of dabigatran etexilate increased rapidly due to many benefits. However,
questions have been raised constantly regarding the safety of dabigatran
etexilate. Case. A 58-year-old Caucasian male with a history of recurrent
paroxysmal atrial fibrillation status after pacemaker and end-stage renal
disease on hemodialysis came to the Emergency Department with the complaint of
severe epistaxis. He had been started on dabigatran 150 mg twice a day about 4
months ago as an outpatient by his cardiologist. His prothrombin time (PT) was
63 seconds with international normalized ratio (INR) of 8.8 and his activated
partial thromboplastin time (aPTT) was 105.7 seconds. Otherwise, all labs were
unremarkable including the liver function test. Dabigatran was stopped
immediately. His INR and aPTT trended downward, reaching normal levels 5 days
after admission. Conclusion. Dabigatran is contraindicated in patients with
severe kidney insufficiency as it is predomitly excreted via the kidney
(~80%). Elderly patients over 75 and patients with chronic renal impairment
should be carefully evaluated before starting dabigatran. Despite studies
showing only mild increase in aPTT and PT/INR in patients receiving dabigatran,
close monitoring may be reasonable in patients with renal insufficiency. |
List fish anti-freeze proteins. | AFP-I
AFP-II
AFP-III
Anti-freeze glycoprotein
Thermal hysteresis protein | Winter flounder contains two distinct anti-freeze protein isoforms, which are
the liver-type extracellular anti-freeze proteins and the skin-type
intracellular anti-freeze protein. The skin-type anti-freeze proteins exhibit
lower anti-freeze activities than the liver-type isoforms and this might be due
to their lacking complete ice-binding motifs. One of the skin-type anti-freeze
proteins, skin-type anti-freeze protein-3, does contain putative overlapping
ice-binding motifs with the sequences '-K-DT-' and '-DT-K-'. Synthetic
anti-freezes containing 0-3 repeats of the '-DT-K-' motif were tested for
stability and activity. Loss of the single '-DT-K-' of skin-type anti-freeze
protein-3 increases the anti-freeze activity and increasing the number of motifs
to two or three lowers the activity. The decrease in activity with an increasing
frequency of the motif correlates with a decrease in the helical content of
these peptides at 0 degrees C. The recently published WHO/FAO guidelines on the assessment of allergenicity of
novel food proteins provide a strategy with which to approach the determination
of the potential of novel proteins in foods to be allergens. Key to this
strategy are the assessment of sequence similarity to known allergens and the
assessment of the resistance to pepsin hydrolysis. Ice structuring proteins
(also commonly referred to as anti-freeze or thermal hysteresis proteins) are a
group of naturally occurring proteins that bind to ice and structure ice crystal
formation. The amino acid sequence of the ice structuring protein (ISP) type III
HPLC 12 (ISP type III) was compared in silico with the sequences of known
allergens. Secondly, the resistance to pepsin hydrolysis of ISP type III and its
glycoconjugates (produced in recombit baker's yeast) was assessed. The
results indicate that ISP type III has no sequence similarity with known
allergenic proteins. Both ISP type III and ISP type III glycoconjugates
contained within the fermentation product were hydrolysed readily by pepsin (50%
loss in <10 min at pH 1.5) to give peptide fragments that were too small to be
allergenic or to trigger cross-linking to IgE. In an accompanying study, we
demonstrated that IgE from fish-allergic individuals did not bind ISP Type III.
Therefore, in accordance with the WHO/FAO strategy, the assessment of ISP type
III and ISP type III glycoconjugates by sequence analysis together with lack of
resistance to pepsin hydrolysis and the absence of IgE binding supports the
conclusion that both are unlikely to present a potential sensitisation hazard. The beta-clip fold includes a diverse group of protein domains that are unified
by the presence of two characteristic waist-like constrictions, which bound a
central extended region. Members of this fold include enzymes like deoxyuridine
triphosphatase and the SET methylase, carbohydrate-binding domains like the fish
antifreeze proteins/Sialate synthase C-terminal domains, and functionally
enigmatic accessory subunits of urease and molybdopterin biosynthesis protein
MoeA. In this study, we reconstruct the evolutionary history of this fold using
sensitive sequence and structure comparisons methods. Using sequence profile
searches, we identified novel versions of the beta-clip fold in the bacterial
flagellar chaperone FlgA and the related pilus protein CpaB, the StrU-like
dehydrogenases, and the UxaA/GarD-like hexuronate dehydratases (SAF
superfamily). We present evidence that these versions of the beta-clip domain,
like the related type III anti-freeze proteins and C-terminal domains of sialic
acid synthases, are involved in interactions with carbohydrates. We propose that
the FlgA and CpaB-like proteins mediate the assembly of bacterial flagella and
Flp pili by means of their interactions with the carbohydrate moieties of
peptidoglycan. The N-terminal beta-clip domain of the hexuronate dehydratases
appears to have evolved a novel metal-binding site, while their C-terminal
domain is likely to adopt a metal-binding TIM barrel-like fold. Using structural
comparisons, we show that the beta-clip fold can be further classified into two
major groups, one that includes the SAF, SET, dUTPase superfamilies, and the
other that includes the phage lambda head decoration protein, the beta subunit
of urease and the C-terminal domain of the molybdenum cofactor biosynthesis
protein MoeA. Structural comparisons also suggest the beta-clip fold was
assembled through the duplication of a three-stranded unit. Though the
three-stranded units are likely to have had a common origin, we present evidence
that complete beta-clip domains were assembled through such duplications,
independently on multiple occasions. There is also evidence for circular
permutation of the basic three-stranded unit on different occasions in the
evolution of the beta-clip unit. We also describe how assembly of this fold from
a basic three-stranded unit has been utilized to accommodate a variety of
activities in its different versions. BACKGROUND: Freeze-tolerant fish survive sub-zero temperatures by
non-colligatively lowering the freezing temperature of their body fluids using
anti-freeze proteins (AFPs). We sought to evaluate and compare the effects of
prolonged sub-zero cryopreservation of transplanted rat hearts using AFP I or
AFP III.
METHODS: Two heterotopic rat heart transplantation protocols were used. In
Protocol 1 (n = 104), hearts (n = 8/group) were preserved for 12, 18 and 24
hours in University of Wisconsin solution (UW) at 4 degrees C, UW at -1.3
degrees C, UW/AFP I at -1.3 degrees C and UW/AFP III at -1.3 degrees C, with and
without nucleation. Post-operative evaluation consisted of visual viability
scoring of the hearts after 60 minutes. Protocol 2 (n = 58) involved evaluation
of 24-hour post-transplant viability, echocardiography (fractional shortening
[FS], left ventricular end-systolic and -diastolic diameter [ESD, EDD] and
anterior and posterior wall systolic and diastolic thickness [AWT-S, AWT-D,
PWT-S, PWT-D]), TUNEL staining and electron microscopy (EM) findings for hearts
preserved for 18, 21 and 24 hours in UW at 4 degrees C or UW/AFP III at -1.3
degrees C.
RESULTS: Hearts preserved in UW at -1.3 degrees C with nucleation froze and
died. Three of 8 hearts preserved in UW at 4 degrees C for 24 hours died,
whereas all hearts preserved at -1.3 degrees C survived. Hearts preserved in
UW/AFP for 18 and 24 hours at -1.3 degrees C had superior viability scores
compared with those in UW at 4 degrees C. Hearts in AFP III at -1.3 degrees C
displayed greater AWT-S and AWT-D (3.5 +/- 0.2 vs 2.4 +/- 0.2, p < 0.05, and 3.5
+/- 0.2 vs 2.2 +/- 0.2, p < 0.05, respectively) after 18-hour preservation. In
the 21-hour preservation group, AFP-treated hearts displayed improved
echocardiographic systolic contraction indices, including: improved FS (27 +/-
3.7 vs 15 +/- 4, p = 0.04); diminished ESD (0.28 +/- 0.57 vs 0.47 +/- 0.6, p <
0.05); greater AWT-S (3.4 +/- 0.18 vs 2.8 +/- 0.2, p < 0.05); and fewer
positively TUNEL-stained nuclei per specimen (35 +/- 14 vs 5.3 +/- 2.7, p =
0.04). Also, improved EM scores were noted compared with UW at 4 degrees C.
CONCLUSIONS: In prolonged sub-zero cryopreservation, AFPs protect the heart from
freezing, improve survival and hemodynamics, and reduce apoptotic cell death. A thermodynamic analysis of a cold-adapted protein, type III anti-freeze protein
(AFP), was carried out. The results indicate that the folding equilibrium of
type III AFP is a reversible, unimolecular, two-state process with no populated
intermediates. Compared to most mesophilic proteins whose folding is two-state,
the psychrophilic type III AFP has a much lower thermodynamic stability at 25
degrees C, approximately 3 kcal/mol, and presents a remarkably downshifted
stability-temperature curve, reaching a maximum of 5 kcal/mol around 0 degrees
C. Type III AFPs contain few and non-optimally distributed surface charges
relative to their mesophilic homologs, the C-terminal domains of sialic acid
synthases. We used thermodynamic double mutant cycles to evaluate the energetic
role of every surface salt bridge in type III AFP. Two isolated salt bridges
provided no contribution to stability, while the Asp36-Arg39 salt bridge,
involved in a salt bridge network with the C-terminal carboxylate, had a
substantial contribution (approximately 1 kcal/mol). However, this contribution
was more than counteracted by the destabilizing effect of the Asp36 carboxylate
itself, whose removal led to a net 30% increase in stability at 25 degrees C.
This study suggests that type III AFPs may have evolved for a minimally
acceptable stability at the restricted, low temperature range (around 0 degrees
C) at which AFPs must function. In addition, it indicates that salt bridge
networks are used in nature also for the stability of psychrophilic proteins,
and has led to a type III AFP variant of increased stability that could be used
for biotechnological purposes. With the development of embryo technologies, such as in vitro fertilization,
cloning and transgenesis, cryopreservation of mammalian gametes and embryos has
acquired a particular interest. Despite a certain success, various
cryopreservation techniques often cause significant morphological and
biochemical alterations, which lead to the disruption of cell organelles,
cytoskeleton damages, cell death and loss of embryo viability. Ultrastructural
studies confirm high sensitivity of the cell membrane and organelle membrane to
freezing and thawing. It was found that many substances with low molecular
weights have a protective action against cold-induced damage. In this concern,
an anti-freeze protein (AFP) and anti-freeze glycoproteins (AFGPs), which occur
at extremely high concentrations in fish that live in Arctic waters and protect
them against freezing, may be of potential interest for cryostorage of animal
embryos at ultra-low temperatures. This mini-review briefly describes several
models of AFP/AFGP action to preserve cells against chilling-induced damages and
indicates several ways to improve post-thaw developmental potential of the
embryo. Site-specific characterisation of mucin-type O-linked glycosylation is an
analytical challenge due to glycan heterogeneity, lack of glycosylation site
consensus sequence and high density of occupied glycosylation sites. Here, we
report the use of electron transfer dissociation (ETD) for the site-specific
characterisation of densely glycosylated mucin-type O-linked glycopeptides using
ESI-IT-MS/MS. Synthetic glycopeptides from the human mucin-1 (MUC-1) tandem
repeat region containing a range of O-linked, tumour-associated carbohydrate
antigens, namely Tn, T and sialyl T, with different glycosylation site
occupancies and an increasing number of tandem repeats were studied. In
addition, a glycopeptide from the anti-freeze glycoprotein of Antarctic and
Arctic notothenoids, bearing four O-linked, per-acetylated T antigens was
characterised. ETD MS/MS of infused or capillary LC-separated glycopeptides
provided broad peptide sequence coverage (c/z·-type fragment ions) with intact
glycans still attached to the Ser/Thr residues. Thus, the glycosylation sites
were unambiguously determined, while simultaneously obtaining information about
the attached glycan mass and peptide identity. Highly sialylated O-glycopeptides
showed less efficient peptide fragmentation, but some sequence and glycosylation
site information was still obtained. This study demonstrates the capabilities of
ETD MS/MS for site-specific characterisation of mucin-type glycopeptides
containing high-density O-linked glycan clusters, using accessible and relative
low-resolution/low-mass accuracy IT MS instrumentation. Low temperature and drought are the main environmental factors threatening the
animals living in arctic area and cold temperate regions. To adapt the severe
environment, the animals should adopt appropriate strategies. As a group of
arthopods with freeze-avoiding strategy, soil springtails have the similar
ecological mechanisms and modes of cold resistance/tolerance as insects,
manifesting in the cold acclimation and drought tolerance to decrease the damage
of ice crystal formation. During cold acclimation, there are a rapid increase of
glycerol, a rapid decrease of fucose and glucose, and the production of
anti-freeze proteins (AFP) , and exists the inter-transformation of different
kinds of lipids to improve the flow of cell membrane to protect the cell from
low temperature injury. In addition, soil springtails have their own specific
modes and mechanisms to tolerate low temperature stress, mainly the vertical
migration under the protection of snow cover and the excretion of ice nucleator
from haemolymph, illustrating that it's of significance to research the
cryobiology of soil springtails. This paper summarized the modes and mechanisms
of soil springtails in tolerating low temperature environment, reviewed the
research progress on the eco-physiology of the springtails, discussed the
existing problems of the researches on the low temperature tolerance of the
springtails, and prospected the research directions of the springtails low
temperature ecology under the background of global change. |
Which is the phosphorylated residue in the promoter paused form of RNA polymerase II? | The promoter paused form of RNA polymerase II is phosphorylated on serine 5 residues of the C-terminal heptapeptide repeat domain (CTD) of the largest subunit. | The carboxy-terminal domain (CTD) of the large subunit of RNA polymerase II is
essential in vivo, and is found in either an unphosphorylated (IIa) or
hyperphosphorylated (IIo) form. The Drosophila uninduced hsp70 and hsp26 genes,
and the constitutively expressed beta-1 tubulin and Gapdh-2 genes, contain an
RNA polymerase II complex which pauses after synthesizing a short transcript. We
report here that, using an in vivo ultraviolet crosslinking technique and
antibodies directed against the IIa and IIo forms of the CTD, these paused
polymerases have an unphosphorylated CTD. For genes containing a 5' paused
polymerase, passage of the paused RNA polymerase into an elongationally
competent mode in vivo coincides with phosphorylation of the CTD. Also, the
level of phosphorylation of the CTD of elongating polymerases is shown not to be
related to the level of transcription, but is promoter specific. The carboxyl-terminal domain (CTD) of RNA polymerase II (Pol II) can be
phosphorylated at serine 2 (Ser-2) and serine 5 (Ser-5) of the CTD heptad repeat
YSPTSPS, and this phosphorylation is important in coupling transcription to RNA
processing, including 5' capping, splicing, and polyadenylation. The mammalian
endogenous dihydrofolate reductase and gamma-actin genes have been used to study
the association of Pol II with different regions of transcribed genes
(promoter-proximal compared to distal regions) and the phosphorylation status of
its CTD. For both genes, Pol II is more concentrated in the promoter-proximal
regions than in the interior regions. Moreover, different phosphorylation forms
of Pol II are associated with distinct regions. Ser-5 phosphorylation of Pol II
is concentrated near the promoter, while Ser-2 phosphorylation is observed
throughout the gene. These results suggest that the accumulation of paused Pol
II in promoter-proximal regions may be a common feature of gene regulation in
mammalian cells. The uninduced Drosophila hsp70 gene is poised for rapid activation. Here we
examine the rapid changes upon heat shock in levels and location of heat shock
factor (HSF), RNA polymerase II (Pol II) and its phosphorylated forms, and the
Pol II kinase P-TEFb on hsp70 in vivo by using both real-time PCR assays of
chromatin immunoprecipitates and polytene chromosome immunofluorescence. These
studies capture Pol II recruitment and progression along hsp70 and reveal
distinct spatial and temporal patterns of serine 2 and serine 5 phosphorylation:
in uninduced cells, the promoter-paused Pol II shows Ser5 but not Ser2
phosphorylation, and in induced cells the relative level of Ser2-P Pol II is
lower at the promoter than at regions downstream. An early time point of heat
shock activation captures unphosphorylated Pol II recruited to the promoter
prior to P-TEFb, and during the first wave of transcription Pol II and the
P-TEFb kinase can be seen tracking together across hsp70 with indistinguishable
kinetics. Pol II distributions on several other genes with paused Pol II show a
pattern of Ser5 and Ser2 phosphorylation similar to that of hsp70. These studies
of factor choreography set important limits in modeling transcription regulatory
mechanisms. The in vivo role of glucocorticoids in controlling prostaglandin endoperoxide
synthase-2 (PTGS2) expression in the human amnion is unclear despite extensive
studies using in vitro models. We addressed this issue by determining PTGS2 mRNA
levels and gene transcriptional activity, RNA polymerase-II (pol-II) binding,
pol-II C-terminal domain (CTD) phosphorylation, histone acetylation, and histone
methylation at the PTGS2 gene in fresh amnion and in amnion explants incubated
with dexamethasone for 24 h after delivery, when adaptation from in vivo to in
vitro conditions occurred. PTGS2 mRNA turnover changed during incubation
involving the initial rapid decrease and subsequent rebound of the transcription
rate and stabilization of mRNA. pol-II accumulated in the 5'-region of the gene,
which indicated postinitiation pausing. pol-II binding, 5'-accumulation,
C-terminal domain Ser-5 and Ser-2 phosphorylation, and histone acetylation
decreased rapidly and did not reverse during the transcriptional rebound,
suggesting that the transcriptional mechanism altered in vitro. Dexamethasone
decreased PTGS2 gene activity and mRNA levels. Glucocorticoid receptor-α (GRα)
was bound to the PTGS2 promoter but did not affect pol-II recruitment, pausing,
or the epigenetic marks. GRα binding, however, decreased initiating (Ser-5) and
elongating (Ser-2) pol-II phosphorylation. The ability of the PTGS2 promoter to
bind GRα in response to dexamethasone diminished during incubation. We conclude
that PTGS2 mRNA turnover is accelerated in vivo, but the underlying mechanisms
are not sustained beyond 24 h in explants. Glucocorticoids chronically
transrepress PTGS2 gene activity in vivo in part by interfering with
transcription initiation and elongation. Glucocorticoid transrepression of PTGS2
may be important for pregcy maintece and the timing of parturition. Somatic hypermutation (SHM) diversifies the V region of Ig genes and underlies
the process of affinity maturation, in which B lymphocytes producing
high-affinity Abs are generated and selected. SHM is triggered in activated B
cells by deamination of deoxycytosine residues mediated by activation-induced
deaminase (AID). Whereas mistargeting of SHM and AID results in mutations and
DNA damage in many non-Ig genes, they act preferentially at Ig loci. The
mechanisms responsible for preferential targeting of SHM and AID activity to Ig
loci are poorly understood. Using an assay involving an SHM reporter cassette
inserted into the Ig L chain locus (IgL) of chicken DT40 B cells, we have
identified a 1.9-kb DIVAC (diversification activator) element derived from
chicken IgL that supports high levels of AID-dependent mutation activity.
Systematic deletion analysis reveals that targeting activity is spread
throughout much of the sequence and identifies two core regions that are
particularly critical for function: a 200-bp region within the IgL enhancer, and
a 350-bp 3' element. Chromatin immunoprecipitation experiments demonstrate that
whereas DIVAC does not alter levels of several epigenetic marks in the mutation
cassette, it does increase levels of serine-5 phosphorylated RNA polymerase II
in the mutation target region, consistent with an effect on transcriptional
elongation/pausing. We propose that multiple, dispersed DNA elements collaborate
to recruit and activate the mutational machinery at Ig gene variable regions
during SHM. |
Has overexpression of sirtuins been reported to increase lifespan in budding yeast (Saccharomyces cerevisiae)? | Overexpression of sirtuins (NAD(+)-dependent protein deacetylases) has been reported to increase lifespan in budding yeast (Saccharomyces cerevisiae). | The yeast Sir2 protein mediates chromatin silencing through an intrinsic
NAD-dependent histone deacetylase activity. Sir2 is a conserved protein and was
recently shown to regulate lifespan extension both in budding yeast and worms.
Here, we show that SIRT1, the human Sir2 homolog, is recruited to the
promyelocytic leukemia protein (PML) nuclear bodies of mammalian cells upon
overexpression of either PML or oncogenic Ras (Ha-rasV12). SIRT1 binds and
deacetylates p53, a component of PML nuclear bodies, and it can repress
p53-mediated transactivation. Moreover, we show that SIRT1 and p53 co-localize
in nuclear bodies upon PML upregulation. When overexpressed in primary mouse
embryo fibroblasts (MEFs), SIRT1 antagonizes PML-induced acetylation of p53 and
rescues PML-mediated premature cellular senescence. Taken together, our data
establish the SIRT1 deacetylase as a novel negative regulator of p53 function
capable of modulating cellular senescence. Overexpression of sirtuins (NAD(+)-dependent protein deacetylases) has been
reported to increase lifespan in budding yeast (Saccharomyces cerevisiae),
Caenorhabditis elegans and Drosophila melanogaster. Studies of the effects of
genes on ageing are vulnerable to confounding effects of genetic background.
Here we re-examined the reported effects of sirtuin overexpression on ageing and
found that standardization of genetic background and the use of appropriate
controls abolished the apparent effects in both C. elegans and Drosophila. In C.
elegans, outcrossing of a line with high-level sir-2.1 overexpression abrogated
the longevity increase, but did not abrogate sir-2.1 overexpression. Instead,
longevity co-segregated with a second-site mutation affecting sensory neurons.
Outcrossing of a line with low-copy-number sir-2.1 overexpression also abrogated
longevity. A Drosophila strain with ubiquitous overexpression of dSir2 using the
UAS-GAL4 system was long-lived relative to wild-type controls, as previously
reported, but was not long-lived relative to the appropriate transgenic
controls, and nor was a new line with stronger overexpression of dSir2. These
findings underscore the importance of controlling for genetic background and for
the mutagenic effects of transgene insertions in studies of genetic effects on
lifespan. The life-extending effect of dietary restriction on ageing in
Drosophila has also been reported to be dSir2 dependent. We found that dietary
restriction increased fly lifespan independently of dSir2. Our findings do not
rule out a role for sirtuins in determination of metazoan lifespan, but they do
cast doubt on the robustness of the previously reported effects of sirtuins on
lifespan in C. elegans and Drosophila. Telomere dysfunction is linked with genome instability and premature aging.
Roles for sirtuin proteins at telomeres are thought to promote lifespan in yeast
and mammals. However, replicative lifespan of the budding yeast Saccharomyces
cerevisiae shortens upon deletion of Rif1, a protein that limits the recruitment
of the sirtuin histone deacetylase Sir2 to telomeres. Here we show that Rif1
maintains replicative lifespan by ultimately stabilizing another age-related
chromosomal domain harboring the ribosomal DNA (rDNA) repeats. Deletion of Rif1
increases Sir2 localization to telomeres and the silent mating-type loci, while
releasing a pool of the histone deacetylase from the intergenic spacer 1 (IGS1)
of rDNA. This is accompanied by a disruption of IGS1 silent chromatin assembly
and increases in aberrant recombination within rDNA repeats. Lifespan defects
linked with Rif1 deletion are abolished if rDNA repeats are forcibly stabilized
via deletion of the replication fork-blocking protein Fob1. In addition, Sir2
overexpression prevents Rif1 deletion from disrupting Sir2 at IGS1 and
shortening lifespan. Moreover, subjecting cells lacking Rif1 to caloric
restriction increases IGS1 histone deacetylation and lifespan, while uncovering
novel genetic interactions between RIF1 and SIR2. Our data indicate that Rif1
maintains lifespan-sustaining levels of Sir2 at rDNA by preventing excessive
recruitment of the histone deacetylase to telomeric and silent mating-type loci.
As sirtuin histone deacetylases, such as Sir2 or mammalian SIRT6, each operate
at multiple age-related loci, we propose that factors limiting the localization
of sirtuins to certain age-related loci can promote lifespan-sustaining roles of
these sirtuins elsewhere in the genome. |
Name the major classes of small non coding RNAs in mammalians? | microRNAs (miRNAs), small nuclear RNAs (snRNAs), small nucleolar RNAs (snoRNAs) are the major classes of small non coding RNAs. Recently, thanks mostly to massively parallel sequencing technologies, other classes of small RNAs have been discovered, such as piRNAs and scaRNAs. | |
Describe a diet that reduces the chance of kidney stones. | People can help prevent kidney stones by making changes in fluid intake and, depending on the type of kidney stone, changes in consumption of sodium, animal protein, calcium, and oxalate.
Drinking enough fluids each day is the best way to help prevent most types of kidney stones. Health care providers recommend that a person drink 2 to 3 liters of fluid a day. People with cystine stones may need to drink even more. Though water is best, other fluids may also help prevent kidney stones, such as citrus drinks. | Conventional medical thought several decades ago was to restrict the amount of
calcium intake in individuals with a history of calcium oxalate stones. In the
past decade, several studies have suggested that increasing the intake of
calcium may actually reduce the risk of calcium oxalate stone formation. The
largest randomized trial of diet and stone recurrence was recently completed.
Interestingly, individuals that had normal calcium intakes and lower intakes of
protein and salt had a significantly reduced rate of calcium oxalate stone
recurrence. This recent trial along with several past epidemiologic studies
should be discussed with patients at high risk of stone recurrence. Currently,
health professionals have a wealth of information that can be distributed to
individuals at high risk of nephrolithiasis, and simple dietary recommendations
may be one of the best ways to reduce the risk of calcium oxalate stones. Recent trends in weight loss diets have led to a substantial increase in protein
intake by individuals. As a result, the safety of habitually consuming dietary
protein in excess of recommended intakes has been questioned. In particular,
there is concern that high protein intake may promote renal damage by
chronically increasing glomerular pressure and hyperfiltration. There is,
however, a serious question as to whether there is significant evidence to
support this relationship in healthy individuals. In fact, some studies suggest
that hyperfiltration, the purported mechanism for renal damage, is a normal
adaptative mechanism that occurs in response to several physiological
conditions. This paper reviews the available evidence that increased dietary
protein intake is a health concern in terms of the potential to initiate or
promote renal disease. While protein restriction may be appropriate for
treatment of existing kidney disease, we find no significant evidence for a
detrimental effect of high protein intakes on kidney function in healthy persons
after centuries of a high protein Western diet. Nephrolithiasis is associated with a variety of abnormalities in urinary
composition. These abnormal urinary risk factors are due to dietary
indiscretions, physiological-metabolic disturbances or both. Stone disease is
morbid and costly, and the recurrence rates may be as high as 30-50% after 5
years. Efforts to prevent stone formation are, therefore, essential. Dietary
factors play an important role in kidney stone formation. Tailored dietary
recommendations based on metabolic evaluation should be offered to patients for
the prevention of recurrence of stone formation. Dietary intervention and
subsequent evaluations of therapeutic efficacy should be based on results from
multiple 24-h urine collections. Urine flow of >1 ml/kg/h almost eliminates the
risk of supersaturation for calcium oxalate, calcium phosphate and uric acid,
thus protecting from the formation of corresponding kidney stones. In patients
with cystenuria, the required urine flow may even be higher and, in cases such
as primary xanthinuria, high fluid intake is required. Milk intake in these
patients should be within the RDA of calcium and protein. In children,
recommendation of a high fluid intake has only limited success. Nevertheless,
each patient should be advised about adequate fluid intake to increase urine
volume in accordance with body size. Although children with hypocitraturia may
benefit from therapeutic agents that raise the urine citrate concentration, all
children bearing residual fragments should be counseled on adequate fluid intake
along with potassium citrate treatment to prevent stone regrowth or formation. Childhood urolithiasis is an evolving condition with an increasing incidence and
prevalence over the last 2 decades. Over that time the underlying cause has
shifted from predomitly infectious to metabolic in nature. This review
describes the pathophysiology, underlying metabolic abnormalities, clinical
presentation, evaluation, and management of childhood urolithiasis. A
comprehensive metabolic evaluation is essential for all children with renal
calculi, given the high rate of recurrence and the importance of excluding
inherited progressive conditions. AIMS: We aimed to determine whether there is an association between dietary zinc
intake (DZI) and prevalent kidney stone disease defined as self-report of any
previous episode of kidney stone.
METHODS: We examined The Third National Health and Nutrition Examination Survey
(NHANES III), a large US population-based cross-sectional study, and used
logistic regression analyses to determine the independent association between
DZI and prevalent kidney stone disease.
RESULTS: A total of 15,444 men and women over 18 years of age were eligible for
analysis. Among them, 710 participants reported a history of kidney stones.
Stone formers tended to have higher DZI than non-stone formers among NHANES III
participants, though this difference did not reach statistical significance (p =
0.1). Multivariate adjusted logistic regression analysis revealed that higher
DZI (log transformed) was associated with a significantly increased risk of
kidney stone disease (odds ratio, OR = 1.41, 95% confidence interval, CI:
1.10-1.81, p = 0.01). After categorizing zinc intake into three groups, those
with highest DZI (>15 mg/day) were also associated with a significantly
increased risk of kidney stone disease, compared to those with lower DZI (<7
mg/day; OR = 1.70, 95% CI: 1.13-2.57, p = 0.01).
CONCLUSIONS: Our study suggests that higher DZI is associated with increased
risk of kidney stone disease. Future prospective studies are needed to clarify
the causal relationship between zinc intake and kidney stone formation. PURPOSE: Because of high correlations between dairy intake and total dietary
calcium, previously reported associations between lower calcium intake and
increased kidney stone risk represent de facto associations between milk
products and risk. We examined associations between dietary calcium from
nondairy and dairy sources, and symptomatic nephrolithiasis.
MATERIALS AND METHODS: We performed prospective studies in the Health
Professionals Follow-up Study (HPFS) in 30,762 men, and in the Nurses' Health
Study (NHS) I and II in 94,164 and 101,701 women, respectively. We excluded men
60 years old or older because we previously reported inverse associations
between calcium intake and risk only in men younger than 60 years. Food
frequency questionnaires were used to assess calcium intake every 4 years. We
used Cox proportional hazards regression to adjust for age, body mass index,
supplemental calcium, diet and other factors.
RESULTS: We documented 5,270 incident kidney stones during the combined 56 years
of followup. In participants in the highest vs the lowest quintile of nondairy
dietary calcium the multivariate relative risk of kidney stones was 0.71 (95% CI
0.56-0.92, p for trend 0.007) in HPFS, 0.82 (95% CI 0.69-0.98, p trend 0.08) in
NHS I and 0.74 (95% CI 0.63-0.87, p trend 0.002) in NHS II. When comparing the
highest to the lowest quintile of dairy calcium, the multivariate relative risk
was 0.77 (95% CI 0.63-0.95, p trend 0.01) for HPFS, 0.83 (95% CI 0.69-0.99, p
trend 0.05) for NHS I and 0.76 (95% CI 0.65-0.88, p trend 0.001) for NHS II.
CONCLUSIONS: Higher dietary calcium from nondairy or dairy sources is
independently associated with a lower kidney stone risk. BACKGROUND: Optimum management to prevent recurrent kidney stones is uncertain.
PURPOSE: To evaluate the benefits and harms of interventions to prevent
recurrent kidney stones.
DATA SOURCES: MEDLINE, Cochrane, and other databases through September 2012 and
reference lists of systematic reviews and randomized, controlled trials (RCTs).
STUDY SELECTION: 28 English-language RCTs that studied treatments to prevent
recurrent kidney stones and reported stone outcomes.
DATA EXTRACTION: One reviewer extracted data, a second checked accuracy, and 2
independently rated quality and graded strength of evidence.
DATA SYNTHESIS: In patients with 1 past calcium stone, low-strength evidence
showed that increased fluid intake halved recurrent composite stone risk
compared with no treatment (relative risk [RR], 0.45 [95% CI, 0.24 to 0.84]).
Low-strength evidence showed that reducing soft-drink consumption decreased
recurrent symptomatic stone risk (RR, 0.83 [CI, 0.71 to 0.98]). In patients with
multiple past calcium stones, most of whom were receiving increased fluid
intake, moderate-strength evidence showed that thiazides (RR, 0.52 [CI, 0.39 to
0.69]), citrates (RR, 0.25 [CI, 0.14 to 0.44]), and allopurinol (RR, 0.59 [CI,
0.42 to 0.84]) each further reduced composite stone recurrence risk compared
with placebo or control, although the benefit from allopurinol seemed limited to
patients with baseline hyperuricemia or hyperuricosuria. Other baseline
biochemistry measures did not allow prediction of treatment efficacy.
Low-strength evidence showed that neither citrate nor allopurinol combined with
thiazide was superior to thiazide alone. There were few withdrawals among
patients with increased fluid intake, many among those with other dietary
interventions and more among those who received thiazide and citrate than among
control patients. Reporting of adverse events was poor.
LIMITATIONS: Most trial participants had idiopathic calcium stones. Nearly all
studies reported a composite (including asymptomatic) stone recurrence outcome.
CONCLUSION: In patients with 1 past calcium stone, increased fluid intake
reduced recurrence risk. In patients with multiple past calcium stones, addition
of thiazide, citrate, or allopurinol further reduced risk.
PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality. BACKGROUND AND OBJECTIVES: Sodium thiosulfate (STS) reduced calcium stone
formation in both humans and genetic hypercalciuric stone forming (GHS) rats. We
sought to measure urine chemistry changes resulting from STS administration in
people. DESIGN SETTING PARTICIPANTS MEASUREMENTS: STS was given to healthy and
hypercalciuric stone forming adults. Five normal non-stone forming adults (mean
age 33 years), and 5 people with idiopathic hypercalciuria and calcium kidney
stones (mean age 66 years) participated. Two baseline 24-hour urine collections
were performed on days 2 and 3 of 3 days of self-selected diets. Subjects then
drank STS 10 mmol twice a day for 7 days and did urine collections while
repeating the self-selected diet. Results were compared by non-parametric
Wilcoxon signed rank test. The primary outcome was the resulting change in urine
chemistry.
RESULTS: STS administration did not cause a significant change in urinary
calcium excretion in either group. In both groups, 24 hour urinary ammonium (P =
0.005) and sulfate excretion (P = 0.007) increased, and urinary pH fell (P =
0.005); citrate excretion fell (P<0.05) in hypercalciuric participants but not
in non-stone formers. Among stone formers with hypercalciuria, 3 of 5 patients
had measurement of serum HCO3 concentration after the STS period: it did not
change. The net effect was an increase in supersaturation of uric acid, and no
change in supersaturation of calcium oxalate or calcium phosphate.
CONCLUSIONS: The basis for studies demonstrating that STS prevented stones in
rats and people was not reflected by the changes in urine chemistry reported
here. Although serum HCO3 did not change, urine tests suggested an acid load in
both non-stone forming and hypercalciuric stone-forming participants. The long
term safety of STS needs to be determined before the drug can be tested in
humans for long-term prevention of stone recurrence. Idiopathic calcium nephrolithiasis is a multifactorial disease with a complex
pathogenesis due to genetic and environmental factors. The importance of social
and health effects of nephrolithiasis is further highlighted by the strong
tendency to relapse of the disease. Long-term prospective studies show a peak of
disease recurrence within 2-3 years since onset, 40-50% of patients have a
recurrence after 5 years and more than 50-60% after 10 years. International
nutritional studies demonstrated that nutritional habits are relevant in therapy
and prevention approaches of nephrolithiasis. Water, right intake of calcium,
low intake of sodium, high levels of urinary citrate are certainly important for
the primary and secondary prevention of nephrolithiasis. Potassium was identified as a shortfall nutrient by the Dietary Guidelines for
Americans 2010 Advisory Committee. The committee concluded that there was a
moderate body of evidence of the association between potassium intake and blood
pressure reduction in adults, which in turn influences the risk of stroke and
coronary heart disease. Evidence is also accumulating of the protective effect
of adequate dietary potassium on age-related bone loss and reduction of kidney
stones. These benefits depend on organic anions associated with potassium as
occurs in foods such as fruits and vegetables, in contrast to similar blood
pressure-lowering benefits of potassium chloride. Benefits to blood pressure and
bone health may occur at levels below current recommendations for potassium
intake, especially from diet, but dose-response trials are needed to confirm
this. Nevertheless, intakes considerably above current levels are needed for
optimal health, and studies evaluating small increases in fruit and vegetable
intake on bone and heart outcomes for short periods have had disappointing
results. In modern societies, Western diets have led to a decrease in potassium
intake with reduced consumption of fruits and vegetables with a concomitant
increase in sodium consumption through increased consumption of processed foods.
Consumption of white vegetables is associated with decreased risk of stroke,
possibly related to their high potassium content. Potatoes are the highest
source of dietary potassium, but the addition of salt should be limited. Low
potassium-to-sodium intake ratios are more strongly related to cardiovascular
disease risk than either nutrient alone. This relationship deserves further
attention for multiple target tissue endpoints. The composition of urine is influenced by diet and changes in dietary factors
have been proposed to modify the risk of recurrent nephrolithiasis. Nutrients
that have been implicated include calcium, oxalate, sodium, animal protein,
magnesium and potassium. There is significant evidence showing that a high
calcium diet is associated with a reduction of lithogenic risk. One of the
possible mechanisms to explain this apparent paradox is that the higher intake
of calcium in the intestine binds with dietary oxalate, reducing its absorption
and urinary excretion. Oxalate from the diet seems to provide only a small
contribution to excretion and dietary restriction is appropriate only in those
with hyperoxaluria and hyperabsorption. Observational studies have shown a
positive and independent association between sodium intake and the formation of
new kidney stones. Consumption of animal protein creates an acid load that
increases urinary excretion of calcium and uric acid and reduced citrate, all
factors that could participate in the genesis of stones. Potassium-rich foods
increase urinary citrate because of its alkali content. In prospective
observational studies, diets rich in magnesium were associated with a lower risk
of kidney stone formation in men. In conclusion, diet is a key element in the
management of the patient with kidney stones but always subordinated to present
metabolic risk factors. Current recommendations for calcium intake call for 1,000 mg per day for women
ages 19-50 and 1,200 mg per day for women over age 50 to ensure bone health.
Given recent concerns that calcium supplements may raise risk for cardiovascular
disease and kidney stones, women should aim to meet this recommendation
primarily by eating a calcium-rich diet and taking calcium supplements only if
needed to reach the RDA goal (often only approximately 500 mg per day in
supplements is required). Idiopathic uric acid nephrolithiasis is characterized by elevated urinary net
acid excretion and insufficient buffering by ammonium, resulting in excessively
acidic urine and titration of the relatively soluble urate anion to insoluble
uric acid. Patients with type 2 diabetes have similar changes in urinary pH, net
acid excretion, and ammonium in 24-h urine collections at baseline, even after
controlling for dietary factors, and are at increased risk for uric acid
nephrolithiasis. However, not all patients with type 2 diabetes develop kidney
stones, suggesting that uric acid stone formers may have additional urinary
defects, perhaps not apparent at baseline. We performed a metabolic study of 14
patients with idiopathic uric acid nephrolithiasis, 13 patients with type 2
diabetes, and 8 healthy control subjects of similar body mass index. After
equilibration on a fixed diet for 5 days, subjects were given a single oral acid
load (50 meq ammonium chloride), and urine was collected hourly for 4 h. Uric
acid stone formers had a lower ammonium excretory response to acute acid loading
compared with diabetic and nondiabetic nonstone formers, suggesting that an
ammonium excretory defect unique to uric acid stone formers was unmasked by the
acid challenge. The Zucker diabetic fatty rat also did not show impaired urinary
ammonium excretion in response to acute acid challenge. A blunted renal ammonium
excretory response to dietary acid loads may contribute to the pathogenesis of
idiopathic uric acid nephrolithiasis. OBJECTIVES: To investigate upper urinary tract stone composition rates in
Australia To investigate changes in stone composition in Australia over the past
30 years
PATIENTS AND METHODS: The Institute for Clinical Pathology and Medical Research
(ICPMR) database was used to obtain - stone composition statistics from
2009-2011 Historical comparisons of stone composition rates were obtained from
previous Australian studies; Rofe; 1981, and Baker; 1993 for epidemiological
data from the 1970s and 1980s respectively. Stone composition data was separated
into gender and age-groups
RESULTS: From the 791 stones analysed between 2009 and 2011, calcium oxalate
remains the domit type accounting for 64% of stones in our dataset, which
compares to 68% from both the 1970s and 1980s. Uric acid stones contributed 16%
of contemporary stone compositions, comparable to 16% in the 1970s and 17% in
the 1980s. Struvite stones showed a decreasing trend from 14% in the 1970s, to
12% in the 1980s and 7% in the current data. For struvite stones, while the
female 21-30 age-group was the most prolific for struvite stone formation in the
1980s, the peak group in contemporaneous records is 61-70 year-old men.
CONCLUSION: Stone composition in Australia has remained relatively static over
the past 30 years. Modifications in diet and body habitus have not resulted in
significant changes in the proportion of uric acid and calcium oxalate stones
detected. The decreasing trend in the proportion of struvite stones most likely
reflects improved management of urinary tract infections within the Australian
population. |
What pharmacological and non-pharmacological interventions can be considered as prophylactic therapies in Cluster Headache patients? | Verapamil, a calcium channel blocker, is considered the mainstay of prophylactic therapy of Cluster Headache patients. Lithium carbonate, topiramate, valproic acid, gabapentin, baclofen, methysergide, melatonin, ketoprofen and indomethacin can also be tried for prophylactic therapy of Cluster Headaches patients. Non-pharmacological prophylactic measures, such as peripheral (mostly occipital nerve) and central (hypothalamic) neurostimulation, ablative surgery, and botulinum toxin type-A (BTX-A) injection, can be also considered. | Headache is the most common complaint encountered in clinical practice.
Approximately 45 million people in the United States experience chronic
headaches. The management of migraine headache involves both pharmacologic and
nondrug therapy. Drug therapy for migraine involves the use of abortive and
prophylactic agents. Abortive agents, such as ergotamine tartrate and
ketoprofen, may be used to relieve the acute attack. Prophylactic therapy is
focused on reducing the frequency and severity of the attacks. beta-Adrenergic
blocking agents, such as propranolol, remain the primary agents for many
migraine patients, although other drugs, such as nonsteroidal anti-inflammatory
drugs (NSAIDs), including ketoprofen, or calcium-channel blocking agents, such
as verapamil, may be beneficial for many patients. For cluster headache and its
variants, methysergide and corticosteroids are usually the drugs of choice.
Patients with chronic cluster headache may achieve good results from long-term
treatment with other therapies, including lithium carbonate, verapamil, and
ketoprofen. We present a review of 60 cases of cluster headache. Most patients were males,
ranging from 19 to 65 years of age at the time of the first visit. Headaches
consisted of short-lasting (from 15 to 210 minutes), intense, unilateral pain
attacks, most frequently in the periorbital area, with ipsilateral autonomic
signs (rhinorrhea, ptosis, tearing and conjunctival injection). Between attacks,
patients were completely free of pain. The attacks occurred in bouts lasting 1
to 6 months, in which patients had daily headaches (one to three times a day).
Headaches responded well to oxygen or ergotamine. Prophylactic therapy in most
cases consisted of verapamil, also with a good response. We present this review
in order to draw attention to this relatively rare form of headache with a
specific therapy. OBJECTIVE: To assess the efficacy and tolerability of topiramate for prophylaxis
of migraine and cluster headache via a retrospective chart analysis.
BACKGROUND: Topiramate has multiple mechanisms of action that could potentially
contribute to migraine prophylaxis. We conducted a retrospective chart review to
assess the efficacy of topiramate as add-on therapy in patients with transformed
migraine or cluster headache, and as first-line therapy in patients with
episodic migraine.
METHODS: Patients diagnosed with transformed migraine, episodic migraine, or
cluster headache, who received topiramate either as add-on therapy or
monotherapy were selected via retrospective chart review. Patients had begun
topiramate therapy at 25 mg/day for the first week and increased their dosage by
25 mg/week to a maximum of 200 mg/day. Topiramate was used as add-on therapy for
patients with transformed migraine and cluster headache, and as a first-line
monotherapy in patients with episodic migraine who had no previous prophylactic
therapy. The outcome parameters examined included a mean 28-day migraine
frequency, migraine severity, number of headache days/month, number of abortive
medication tablets/month, patient global evaluation, and the MIDAS scale.
RESULTS: One hundred seventy-eight patients (transformed migraine: n = 96;
episodic migraine: n = 70; and cluster headache: n = 12) were included in the
retrospective analysis. The mean dose of topiramate for all patients was 87.5
mg/day. For patients with transformed migraine, mean migraine frequency
decreased from 6.3/28 days to 3.7 (P = 0.005). Mean severity decreased from 7.1
to 3.8 on a 10-point scale, with 10 representing the most severe pain (P =
0.003). The mean number of headache days/month decreased from 22.1 to 9.6 (P =
0.001), and the mean number of abortive medication tablets decreased from
28.7/month to 10.6 (P = 0.001). Patient global evaluation indicated substantial
or moderate improvement in 53% of patients with transformed migraine who used
topiramate as add-on therapy. Mean MIDAS scale values decreased from 90.2 to
24.9 (P< 0.0001). The 70 episodic migraine patients who were administered
topiramate as first-line therapy exhibited a decrease in mean migraine frequency
(5.8/28 days to 1.9, P = 0.001), while mean migraine severity decreased from 8.1
to 2.0 (P = 0.003). Sixty-one percent of patients reported marked improvement.
Nine of the 12 cluster headache patients exhibited substantial or moderate
improvement in symptoms, whereas three had no improvement. The most common
adverse effects were paresthesias (12%), cognitive effects (11%), and dizziness
(6%). Eight patients discontinued topiramate due to adverse effects; cognitive
effects were the most common reason. No patient discontinued topiramate
treatment due to lack of efficacy. Twelve percent of patients lost more than 5
lbs during treatment (a range of 5-120 lbs).
CONCLUSION: For both patients with transformed migraine (add-on therapy) and
patients with episodic migraine (first-line monotherapy), topiramate yielded
significant reductions in migraine frequency, migraine severity, number of
headache days/month, and use of abortive medications. Topiramate also appears to
be well tolerated and useful in the adjunctive treatment of cluster headache.
Prospective double-blind, placebo-controlled trials will be required to confirm
our results. Cluster headaches are characterized by strictly unilateral paroxysmal attacks of
severe pain with associated autonomic sign and symptom. Prevalence is 5 times
higher in men than in women in our cases. About 10-15% of patients have chronic
symptoms without remissions, but we estimated less frequent in Japanese (6.6% in
our series). Pain almost invariably recurs on the same side, but in some
patients (16.4%) the affected site switches. Cluster headache may be inherited
in about 5% of our cases. Attacks frequently occur at night (60.7%). The
patients (64.8%) are restless or agitated during an attack. Recent PET studies
elucidated that acute attacks causes activation of the posterior hypothalamic
grey matter. The excitement of the area might be responsible for peculiar
clinical characteristics of agitation. Some patients (66.0%) have also have
symptoms (especially a visual aura) usually attributed to migraine. Treatment of
cluster headache includes both acute therapy aimed at aborting individual
attacks and prophylactic therapy aimed at preventing recurrent attacks during
the cluster period. There are many choices using for both therapies. Based on
our clinical experience, we recommended the combination of nasal sumatriptan for
acute attacks and verapamil 240 mg/day for prophylaxis. Cluster headache is a well-known primary headache syndrome with a prevalence of
about 5/10,000 of the adult population, making it much less common than
migraine. Diagnostic terms such as histaminic cephalalgia, Horton's headache and
ciliary neuralgia have been used for what is now known as cluster headache. This
disorder can be differentiated from migraine by clinical and pathophysiologic
features. Cluster headache also exhibits a differing therapeutic response to
medications when compared with migraine. The pharmacologic treatment of cluster
is reviewed in this article. In contrast to migraine, men are 3-4 times more
likely to be diagnosed with cluster headache than women, and the cluster
headache population is older. Cluster attacks are known for their brief intense
unilateral excruciating pain during susceptible periods known as cluster
periods, which typically last weeks. Attack-free months generally follow. Pain
is experienced in the distribution of the trigeminal nerve, with unilateral
autonomic features. Most patients are successfully managed with medical therapy.
Medication management can be divided into abortive treatments for an ongoing
attack and prophylactic treatment. Prophylaxis aims to induce and maintain a
remission. There are a variety of different medications for abortive and
prophylactic therapy, accompanied by a variable amount of evidence-based
medicine. For patients refractory to medical management, interventional
procedures are available as a last resort. Most procedures are directed against
the sensory trigeminal nerve and associated ganglia, eg, anesthetizing the
sphenopalatine ganglion. The objective of this open single-centre study was to evaluate the efficacy and
tolerability of botulinum toxin type-A (BTX-A) as add-on in the prophylactic
treatment of cluster headache (CH). Twelve male patients with episodic (n=3) or
chronic (n=9) CH, unresponsive to common prophylactic medications, were treated
with a cumulative dose of 50 International Units (IU) BTX-A according to a
standardised injection scheme into the ipsilateral pericranial muscles. One
patient with chronic CH experienced a total cessation of attacks and in 2
patients attack intensity and frequency improved. In another patient with
chronic CH typical attacks were not influenced, but an ipsilateral continuous
occipital headache significantly improved. Patients with episodic CH did not
benefit from BTX-A treatment. Tolerability was excellent. These findings provide
evidence that BTX-A may be beneficial as an add-on prophylactic therapy for a
limited number of patients with chronic CH. Cluster headache is a rare yet exquisitely painful primary headache disorder
occurring in either episodic or chronic patterns. The unique feature of cluster
headache is the distinctive circadian and circannual periodicity in the episodic
forms. The attacks are stereotypic--they are of extreme intensity and short
duration, occur unilaterally, and are associated with robust signs and symptoms
of autonomic dysfunction. Although the pathophysiology of cluster headache
remains to be fully understood, there have been a number of recent seminal
observations. To exclude structural mimics, patients presenting with symptoms
suggestive of cluster headache warrant at least a brain magnetic resoce
imaging (MRI) scan in their work-up. The medical treatment of cluster headache
includes acute, transitional, and maintece prophylaxis. Agents used for acute
therapy include inhalation of oxygen, triptans, such as sumatriptan, and
dihydroergotamine. Transitional prophylaxis refers to the short-term use of
fast-acting agents. This typically involves either corticosteroids or an
occipital nerve block. The mainstay of prophylactic therapy is verapamil. Yet,
other medications, including lithium, divalproex sodium, topiramate,
methysergide, gabapentin, and even indomethacin, may be useful when the headache
fails to respond to verapamil. For medically refractory patients, surgical
interventions, occipital nerve stimulation, and deep brain stimulation remain an
option. As the sophistication of functional neuroimaging increases, better
insight into the pathophysiological mechanisms that underlie cluster headache is
expected. Cluster headache (CH) pain is the most severe of the primary headache syndromes.
It is characterized by periodic attacks of strictly unilateral pain associated
with ipsilateral cranial autonomic symptoms. The majority of patients have
episodic CH, with cluster periods that typically occur in a circannual rhythm,
while 10% suffer from the chronic form, with no significant remissions between
cluster periods. Sumatriptan injection or oxygen inhalation is the first-line
therapy for acute CH attacks, with the majority of patients responding to either
treatment. The calcium channel blocker verapamil is the drug of choice for CH
prevention. Other drugs that may be used for this purpose include lithium
carbonate, topiramate, valproic acid, gabapentin, and baclofen. Transitional
prophylaxis, most commonly using corticosteroids, helps to control the attacks
at the beginning of a cluster period. Peripheral neural blockade is effective
for short-term pain control. Recently, the therapeutic options for refractory CH
patients have expanded with the emergence of both peripheral (mostly occipital
nerve) and central (hypothalamic) neurostimulation. With the emergence of these
novel treatments, the role of ablative surgery in CH has declined. |
How does phospholamban affect the biological activity of the calcium ATPase SERCA? | SR calcium uptake is mediated by a Ca(2+)-ATPase (SERCA2), whose activity is reversibly regulated by phospholamban (PLN). Dephosphorylated PLN is an inhibitor of SERCA and phosphorylation of PLN relieves this inhibition. Phospholamban (PLN) is a small integral membrane protein, which binds and inhibits in a yet unknown fashion the Ca(2+)-ATPase (SERCA) in the sarcoplasmic reticulum. Based on structural and dynamics data, a model in which PLN undergoes allosteric activation upon encountering SERCA has been proposed. The allosteric regulation of SERCA depends on the conformational equilibrium of PLN, whose cytoplasmic regulatory domain interconverts between three different states: a ground T state (helical and membrane associated), an excited R state (unfolded and membrane detached), and a B state (extended and enzyme-bound), which is noninhibitory. Phosphorylation of PLN shifts the populations toward the B state, increasing SERCA activity. Phospholamban (PLN) regulates cardiac contractility via its modulation of sarco(endo)plasmic reticulum calcium ATPase (SERCA) activity. Impairment of this regulatory process causes heart failure. | We have used magnetic resoce to map the interaction surface of an integral
membrane protein for its regulatory target, an integral membrane enzyme.
Phospholamban (PLN) regulates cardiac contractility via its modulation of
sarco(endo)plasmic reticulum calcium ATPase (SERCA) activity. Impairment of this
regulatory process causes heart failure. To map the molecular details of the
PLN/SERCA interaction, we have functionally reconstituted SERCA with labeled PLN
in dodecylphosphocholine micelles for high-resolution NMR spectroscopy and in
both micelles and lipid bilayers for EPR spectroscopy. Differential
perturbations in NMR linewidths and chemical shifts, measured as a function of
position in the PLN sequence, provide a vivid picture of extensive SERCA
contacts in both cytoplasmic and transmembrane domains of PLN and provide
structural insight into previously reported functional mutagenesis data. NMR and
EPR data show clear and complementary evidence for a dynamic (micros-to-ms)
equilibrium between two conformational states in the cytoplasmic domain of PLN.
These results support the hypothesis that SERCA attracts the cytoplasmic domain
of PLN away from the lipid surface, shifting the preexisting equilibrium of PLN
conformers toward a structure that is poised to interact with the regulatory
target. EPR shows that this conformational switch behaves similarly in micelles
and lipid membranes. Based on structural and dynamics data, we propose a model
in which PLN undergoes allosteric activation upon encountering SERCA. Regulation of the SERCA calcium pump by phospholamban (PLB) is largely due to
interactions between their respective transmembrane domains. In spite of
numerous mutagenesis and kinetic studies, we still do not have a clear
mechanistic picture of how PLB influences the calcium transport cycle of SERCA.
Herein, we have created alanine mutants for each residue in the transmembrane
domain of PLB, we have co-reconstituted these mutants with SERCA into
proteoliposomes, and we have performed kinetic simulations of the
calcium-dependent ATPase activity isotherms. The PLB transmembrane mutants had a
variable effect on the calcium affinity, maximal activity, and cooperativity of
SERCA, such that a range of values was observed. Kinetic simulations using a
well-established reaction scheme for SERCA then allowed us to correlate the
effects on SERCA activity with changes in the reaction scheme rate constants.
Only three steps in the reaction scheme were affected by the presence of PLB,
namely, binding of the first calcium ion, a subsequent conformational change in
SERCA, and binding of the second calcium ion. The ability of wild-type and
mutant forms of PLB to alter the apparent calcium affinity of SERCA correlated
with a decreased rate of binding of the second calcium ion. In addition, the
ability of wild-type and mutant forms of PLB to alter the maximal activity of
SERCA correlated with a change in the forward rate constant for the slow
conformational change in SERCA following binding of the first calcium ion. Phospholamban (PLN) is a type II membrane protein that inhibits the sarcoplasmic
reticulum Ca(2+)-ATPase (SERCA), thereby regulating calcium homeostasis in
cardiac muscle. In membranes, PLN forms pentamers that have been proposed to
function either as a storage for active monomers or as ion channels. Here, we
report the T-state structure of pentameric PLN solved by a hybrid solution and
solid-state NMR method. In lipid bilayers, PLN adopts a pinwheel topology with a
narrow hydrophobic pore, which excludes ion transport. In the T state, the
cytoplasmic amphipathic helices (domains Ia) are absorbed into the lipid bilayer
with the transmembrane domains arranged in a left-handed coiled-coil
configuration, crossing the bilayer with a tilt angle of approximately 11° with
respect to the membrane normal. The tilt angle difference between the monomer
and pentamer is approximately 13°, showing that intramembrane helix-helix
association forces dominate over the hydrophobic mismatch, driving the overall
topology of the transmembrane assembly. Our data reveal that both topology and
function of PLN are shaped by the interactions with lipids, which fine-tune the
regulation of SERCA. Heart disease remains the leading cause of death and disability in the Western
world. Current therapies aim at treating the symptoms rather than the
subcellular mechanisms, underlying the etiology and pathological remodeling in
heart failure. A universal characteristic, contributing to the decreased
contractile performance in human and experimental failing hearts, is impaired
calcium sequestration into the sarcoplasmic reticulum (SR). SR calcium uptake is
mediated by a Ca(2+)-ATPase (SERCA2), whose activity is reversibly regulated by
phospholamban (PLN). Dephosphorylated PLN is an inhibitor of SERCA and
phosphorylation of PLN relieves this inhibition. However, the initial simple
view of a PLN/SERCA regulatory complex has been modified by our recent
identification of SUMO, S100 and the histidine-rich Ca-binding protein as
regulators of SERCA activity. In addition, PLN activity is regulated by 2
phosphoproteins, the inhibitor-1 of protein phosphatase 1 and the small heat
shock protein 20, which affect the overall SERCA-mediated Ca-transport. This
review will highlight the regulatory mechanisms of cardiac contractility by the
multimeric SERCA/PLN-ensemble and the potential for new therapeutic avenues
targeting this complex by using small molecules and gene transfer methods. |
List the components of mTOR Complex 2 (mTORC2). | Mammalian target of rapamycin complex 2 (mTORC2) is a kinase complex comprised of mTOR, Rictor, mSin1, mLST8/GβL and PRR5. | When rhegmatogenous retinal detachment occurs, tumor necrosis factor-alpha
(TNF-α) among other cytokines leaks into the subretinal space, induces resident
retinal pigment epithelial (RPE) cells to migrate, which is the initial step of
proliferative vitreoretinopathy (PVR). In the current study, we aim to
understand how this is regulated by focusing the cellular mechanisms involved.
Here we identified an Akt/Tuberous sclerosis protein 2 (TSC2)/mTOR complex1
(mTORC1) signaling pathway after TNF-α treatment to mediate RPE cell migration.
Suppression of mTORC1 activation, either by its inhibitor rapamycin, or by
activation of its suppressor AMP activated protein kinase (AMPK), inhibited
TNF-α-mediated RPE cell migration, while RNA interference (RNAi)-mediated
knocking-down of SIN1 or Rictor, two key components of mTOR complex 2 (mTORC2),
had no significant effect on TNF-α-induced RPE cell migration. Our data provide
initial evidence that TNF-α-mediated in vitro RPE cell migration mainly requires
Akt/mTORC1, but not mTORC2 signaling. The results of this study may lead to
indentify novel signaling targets against PVR. Mammalian Sin1 plays key roles in the regulation of mitogen-activated protein
kinase (MAPK) and mammalian target of rapamycin (mTOR) signaling. Sin1 is an
essential component of mTOR complex 2 (mTORC2). The functions of Sin1 and mTORC2
remain largely unknown in T cells. Here, we investigate Sin1 function in T cells
using mice that lack Sin1 in the hematopoietic system. Sin1 deficiency blocks
the mTORC2-dependent Akt phosphorylation in T cells during development and
activation. Sin1-deficient T cells exhibit normal thymic cellularity and
percentages of double-negative, double-positive, and single-positive CD4(+) and
CD8(+) thymocytes. Sin1 deficiency does not impair T-cell receptor (TCR) induced
growth and proliferation. Sin1 appears dispensable for in vitro CD4(+) helper
cell differentiation. However, Sin1 deficiency results in an increased
proportion of Foxp3(+) natural T-regulatory (nTreg) cells in the thymus. The
TGF-β-dependent differentiation of CD4(+) T cells in vitro is enhanced by the
inhibition of mTOR but not by loss of Sin1 function. Our results reveal that
Sin1 and mTORC2 are dispensable for the development and activation of T cells
but play a role in nTreg-cell differentiation. Tumor necrosis factor-alpha (TNF-α) promotes in vitro retinal pigment epithelial
(RPE) cell migration to initiate proliferative vitreoretinopathy (PVR). Here we
report that TNF-α promotes human RPE cell migration by inducing matrix
metallopeptidase 9 (MMP-9) expression. Inhibition of MMP-9 by its inhibitor or
its neutralizing antibody inhibited TNF-α-induced in vitro RPE cell migration.
Reversely, exogenously-added active MMP-9 promoted RPE cell migration.
Suppression Akt/mTOR complex 1(mTORC1) activation by LY 294002 and rapamycin
inhibited TNF-α-mediated MMP-9 expression. To introduce a constitutively active
Akt (CA-Akt) in cultured RPE cells increased MMP-9 expression, and to block
mTORC1 activation by rapamycin inhibited its effect. RNA interference
(RNAi)-mediated silencing of SIN1, a key component of mTOR complex 2 (mTORC2),
had no effect on MMP-9 expression or secretion. In conclusion, this study
suggest that TNF-α promotes RPE cell migration by inducing MMP-9 expression
through activation of Akt/ mTORC1, but not mTORC2 signaling. Our earlier work showed that mammalian target of rapamycin (mTOR) is essential
to the development of various hypertrophic responses, including cardiomyocyte
survival. mTOR forms two independent complexes, mTORC1 and mTORC2, by
associating with common and distinct cellular proteins. Both complexes are
sensitive to a pharmacological inhibitor, torin1, although only mTORC1 is
inhibited by rapamycin. Since mTORC2 is known to mediate the activation of a
prosurvival kinase, Akt, we analyzed whether mTORC2 directly mediates Akt
activation or whether it requires the participation of another prosurvival
kinase, PKCε (epsilon isoform of protein kinase-C). Our studies reveal that
treatment of adult feline cardiomyocytes in vitro with insulin results in Akt
phosphorylation at S473 for its activation which could be augmented with
rapamycin but blocked by torin1. Silencing the expression of Rictor
(rapamycin-insensitive companion of mTOR), an mTORC2 component, with a sh-RNA in
cardiomyocytes lowers both insulin-stimulated Akt and PKCε phosphorylation.
Furthermore, phosphorylation of PKCε and Akt at the critical S729 and S473 sites
respectively was blocked by torin1 or Rictor knockdown but not by rapamycin,
indicating that the phosphorylation at these specific sites occurs downstream of
mTORC2. Additionally, expression of DN-PKCε significantly lowered the
insulin-stimulated Akt S473 phosphorylation, indicating an upstream role for
PKCε in the Akt activation. Biochemical analyses also revealed that PKCε was
part of Rictor but not Raptor (a binding partner and component of mTORC1).
Together, these studies demonstrate that mTORC2 mediates prosurvival signaling
in adult cardiomyocytes where PKCε functions downstream of mTORC2 leading to Akt
activation. Tuberous sclerosis complex 1 (TSC1) and TSC2 are suppressors of mechanistic
target of rapamycin (mTOR). mTOR is the major component of two protein
complexes: mTOR complex 1 (mTORC1) and mTORC2. Inactive mutation of either TSC1
or TSC2 unleashes mTOR signaling and consequently causes TSC, a benign tumor
syndrome affecting multiple organs. We report here that expression of
αB-crystallin was upregulated in Tsc1-/- or Tsc2-/- mouse embryonic fibroblasts,
Eker rat uterine leiomyoma-derived Tsc2-deficient ELT3 cells, mutant
Tsc2-associated mouse kidney tumors, and human lung lymphangioleiomyomatosis
nodules. αB-crystallin was transcriptionally activated by mTOR complex 2
(mTORC2): nuclear factor-kappa B (NFκB) signaling cascade. The augmented
αB-crystallin was critical for the migration, invasion and apoptotic resistance
of Tsc2-defective cells. Disruption of αB-crystallin suppressed Tsc2-null cell
proliferation and tumorigenesis. Therefore, enhanced αB-crystallin has an
essential role in TSC1/2 complex deficiency-mediated tumorigenesis, and
inhibition of αB-crystallin may complement the current therapy for TSC. |
What is known about the Digit Ratio (2D:4D) cancer? | Digit ratio (2D:4D) is associated with gastric cancer, prostate cancer, breast cancer, cervical intraepithelial neoplasia and oral squamous cell carcinoma. 2D:4D was found to be higher in patients diagnosed with gastric cancer and prostate cancer patients relative to controls. Among prostate cancer patients, 2D:4D shows strong differences between African-Americans and Caucasians; however, it does not correlate with disease severity in men already diagnosed with prostate cancer. However, other authors did not find an association between 2D:4D and prostate cancer risk.
2D:4D is not associated with testicular germ cell tumors. | The androgen receptor gene (AR) contains a domain which includes a variable
number of CAG sequences and alleles with low numbers of CAG repeats show high
transactivation activity when complexed with testosterone. The ratio of 2nd and
4th digit length (2D:4D) is negatively correlated with phenotypic effects of
testosterone. Low numbers of CAG repeats and low 2D:4D are both associated with
high sperm numbers and protection against breast cancer. This suggests that CAG
number and 2D:4D are correlated i.e. low CAG number and low 2D:4D indicate high
activation of androgen-responsive genes. Findings from AR studies predict that
low 2D:4D will be associated with prostate and hepatocellular cancer,
urolithiasis, ADHD, ankylosing spondylitis, spontaneous abortion, and polycystic
ovaries, while high 2D:4D will be associated with motor neuron diseases and
endometrial cancer. Findings from 2D:4D studies predict that short CAG length
will be common in autism and Asperger's syndrome, while high numbers of CAG
repeats will be found in men who are prone to early myocardial infarction. OBJECTIVE: To investigate the relationships between the 2nd to 4th digit ratio
(digit ratio) and prostate volume, prostate-specific antigen (PSA) level, and
the presence of prostate cancer.
PATIENTS AND METHODS: Of the men that presented with lower urinary tract
symptoms (LUTS) at a single tertiary academic center, 366 men aged 40 or older
with a PSA level ≤ 40 ng/mL were prospectively enrolled. Right-hand 2nd and 4th
digit lengths were measured prior to the PSA determinations and transrectal
ultrasonography (TRUS). Prostate volumes were measured by TRUS without
information about digit length. Patients with a PSA level ≥ 3 ng/mL underwent
prostate biopsy.
RESULTS: No relationship was found between prostate volume and digit ratio
[correlation coefficient (r) = -0.038, P = 0.466]. But, significant negative
correlations were found between digit ratio and PSA (r = -0.140, P = 0.007).
When the patients were divided into two groups (Group A: digit ratio < 0.95, n =
184; Group B: digit ratio ≥ 0.95, n = 182), Group A had a higher mean PSA level
than Group B (3.26 ± 5.54 ng/mL vs 1.89 ± 2.24 ng/mL, P = 0.002) and had
significantly higher risks of prostate biopsy [odds ratio (OR) = 1.75, 95% CI =
1.07-2.84] and prostate cancer (OR = 3.22, 95% CI = 1.33-7.78).
CONCLUSIONS: Patients with a lower digit ratio have higher risks of prostate
biopsy and prostate cancer. BACKGROUND: The ratio of digit lengths is fixed in utero, and may be a proxy
indicator for prenatal testosterone levels.
METHODS: We analysed the right-hand pattern and prostate cancer risk in 1524
prostate cancer cases and 3044 population-based controls.
RESULTS: Compared with index finger shorter than ring finger (low 2D : 4D), men
with index finger longer than ring finger (high 2D : 4D) showed a negative
association, suggesting a protective effect with a 33% risk reduction (odds
ratio (OR) 0.67, 95% confidence interval (CI) 0.57-0.80). Risk reduction was
even greater (87%) in age group <60 (OR 0.13, 95% CI 0.09-0.21).
CONCLUSION: Pattern of finger lengths may be a simple marker of prostate cancer
risk, with length of 2D greater than 4D suggestive of lower risk. Finger length ratio has been proposed as a putative marker for prenatal hormone
exposure, as well as the action of HOX, AR, and a variant of the LIN28b genes.
These genes have been recently connected to carcinogenesis and digit ratio could
help to identify patients with this predisposition.
OBJECTIVES: The purpose of this study was to investigate the possible
correlations between digit ratio, oral squamous cell carcinoma (OSCC)-the most
common oral cancer-and oral premaligt lesions (OPLs) in tobacco-consuming
males, the main risk group for this disease.
METHODS: Digital images of the right hands of patients diagnosed with OSCC (n =
25), OPLs (n = 25), and age-matched controls (n = 25) were obtained. Fingers
were measured using Adobe Photoshop and the mean ratios between the 2nd and 4th
digits were compared. Data were analyzed by ANOVA (α = 0.05).
RESULTS: Risk factors (alcohol and tobacco consumption, familial history) were
similar between the three study groups. Males in the OSCC group presented
significantly higher digit ratio (P = 0.03) in comparison with males with OPLs
and individuals without oral lesions.
CONCLUSIONS: According to the results, males with the higher digit ratio seem to
be more prone to undergo malignization of lesions in the oral cavity. Similar
deleterious habits for the three groups allows us to infer that digit ratio
could add to the research of etiological factors and be a putative marker for
the screening of patients' susceptibility to develop oral squamous cell
carcinoma. BACKGROUND: We aimed to assess whether 2D:4D measures are associated with breast
cancer risk.
METHODS: We derived the ratio of the lengths of the index and ring fingers
(2D:4D), and right minus left 2D:4D (Δ(r-l)) from digit lengths measured from
photocopies of participants' hands collected during a recent follow-up of the
Melbourne Collaborative Cohort Study, a prospective study including 24 469
women. Of the 9044 women with available data, we identified 573 incident breast
cancer cases. Hazard ratios (HR) and 95% confidence intervals (CI) for a one
standard deviation difference in 2D:4D measures were obtained from Weibull
survival models, and linear regression models were used to examine potential
associations between 2D:4D measures and age at menarche and menopause.
RESULTS: We found a direct association between left 2D:4D and breast cancer
risk, an inverse association between Δ(r-l) and risk of breast cancer, but no
association between right 2D:4D and breast cancer risk. Among breast cancer
cases, both right 2D:4D and Δ(r-l) were inversely associated with age at
diagnosis. We also observed associations between both right 2D:4D and Δ(r-l) and
age at menopause, with increasing digit ratio measures related to earlier mean
age at menopause.
CONCLUSION: Digit ratio measures might be associated with breast cancer risk and
age at onset of breast cancer. If confirmed in other studies, this suggests that
lower exposure or sensitivity to prenatal testosterone might be associated with
lower risk of breast cancer. OBJECTIVE: To investigate the relationships between 2nd to 4th digit ratio
(digit ratio) and prostate cancer detection rate and biopsy findings, including
Gleason score.
MATERIALS AND METHODS: In 770 consecutive men aged 40 years or older that
presented with lower urinary tract symptoms (LUTS), right hand 2nd and 4th digit
lengths were measured prior to PSA determinations, DRE and transrectal
ultrasonography (TRUS). Among these, 166 men with a prostate specific antigen
(PSA) level ≥ 3 ng/mL or abnormal digit rectal examination (DRE) prospectively
underwent prostate biopsies. The relationship between digit ratio and prostate
cancer detection rate and biopsy findings was investigated.
RESULTS: The study subjects were allocated to two groups by digit ratio (group
A: digit ratio < 0.95; n = 420; group B: digit ratio ≥ 0.95; n = 350). Despite
similar biopsy rates (22.4% vs. 20.6%, p = 0.544), group A had higher cancer
detection rate (46.8% (44/94) vs. 23.6% (17/72), p = 0.002; OR = 2.847, 95% CI =
1.445-5.610). When we analyzed 408 positive biopsy cores (group A: digit ratio <
0.95, n = 282; group B: digit ratio ≥ 0.95, n = 126), group A had higher
percentage of core cancer volume (46.7% vs. 37.1%, p = 0.005) and more biopsy
cores with high Gleason score (sum of Gleason score ≥ 9: 18/282 (6.4%) vs. 1/126
(0.8%), p = 0.010; primary Gleason score = 5: 12/282 (4.3%) vs. 0/126 (0.0%), p
= 0.021).
CONCLUSIONS: A lower digit ratio is related to an increased detection rate of
prostate cancer, a high percentage of core cancer volume and a high Gleason
score. BACKGROUND: The ratio of the second to the fourth digit (2D:4D ratio) is a
sexually dimorphic trait established in utero that differs between ethnic
groups. It is associated with prenatal androgen exposure, and studies have
evaluated the ratio as a marker for certain traits and disease states known to
be associated with higher levels of in utero androgens, such as prostate cancer.
There are currently no screening tools that stratify men with prostate cancer
according to the severity of their disease. This study aims to investigate the
2D:4D ratio as a potential marker for prostate cancer severity. Our hypothesis
was that lower digit ratios, representing higher in utero androgen exposure,
would be associated with more severe disease.
METHODS: Measurements were taken of the second and fourth digits of the right
hand of male patients diagnosed with prostate cancer. Gleason score, presence of
metastasis, family history, age at diagnosis and race were recorded. The
distribution of demographic and other patient characteristics were compared with
digit ratios to determine relationships.
RESULTS: African-American men with prostate cancer are 3.70 times more likely to
have a low 2D:4D digit ratio than Caucasian men with prostate cancer (95%
confidence interval: 1.98, 6.92; P < 0.0001). There were no statistically
significant differences in the presence of metastasis, Gleason score, family
history or age at diagnosis by digit ratio.
CONCLUSION: 2D:4D ratio shows strong differences between African-Americans and
Caucasians; however, it does not correlate with disease severity in men already
diagnosed with prostate cancer. Although this is a small population sample with
possible confounding factors, it does not provide evidence to support the
hypothesis that prenatal androgens affect prostate cancer grade or progression. OBJECTIVES: To analyze the validity of the ratio between the second and fourth
finger (digit ratio; 2D/4D) of the left hand as a predictor for prostate cancer
(PCa) in a group of men undergoing prostate biopsy.
METHODS: We prospectively recruited 204 consecutive patients referred for
transrectal prostate biopsy due to PSA elevation or abnormal digital rectal
examination between January 2008 and June 2009. The same physician performed all
clinical examinations, digit ratio measurements and transrectal biopsy in all
cases. Digit ratio determination was done with a Vernier caliper in the left
hand. Patients underwent determination of hormone profile (testosterone and
sexual hormone binding globulin (SHBG)) between 7:00AM and 11:00AM. Age, digital
rectal examination, PSA, free PSA, PSA density, testosterone and SHBG,
pathological report and D2 and D4 measurements were recorded prospectively.
RESULTS: Variables age and SHBG were directly related to PCa. Prostate volume
was inversely related to neoplasia. 2D/4D ratio >0,95 (OR (CI 95%) 4,4
(1,491-13,107) was related to neoplasia. No differences in PCa were seen
regarding PSA, free PSA, PSA density, digital rectal examination and
testosterone.
CONCLUSION: High digit ratio predicts PCa in men undergoing prostate biopsy.
Digit ratio >0,95 has 4-fold risk of PCa compared to men with digit ratio ≤0.95. BACKGROUND: Sex steroid exposure during early human development may influence
disease susceptibility. Digit ratio (2D:4D) is a putative marker for prenatal
hormone exposure and sensitivity, as well as the action of genes closely related
to carcinogenesis. Digit ratio could act as a possible marker for cancer
predisposition.
AIMS: The aim of this study is to investigate the possible correlations between
right hand, left hand and right minus left (R-L) 2D:4D and gastric cancer (GCA)
in men and women and assess the correlations with tumor staging and histological
diagnosis.
METHODS: Digital images of the right and left hand palms of patients diagnosed
with GCA (n=57, 42 males, 15 females) and age and sex-matched controls (n=59, 41
males, 18 females) were obtained. Means for 2D:4D were compared. Data were
analyzed by repeated-measures one-way ANOVA and Student's t-test for finger
measurements and group comparisons and Pearson's and Spearman's tests for
correlations with tumor staging (α=0.05).
RESULTS: GCA group presented significantly higher left 2D:4D, but significantly
lower R-L in comparison to healthy controls, particularly so for males. Digit
ratio did not correlate to clinical staging or TNM staging. However, low R-L was
significantly related to adenocarcinomas.
CONCLUSIONS: Early developmental conditions, including prenatal testosterone
seem to play a role on the maligt transformation of gastric lesions. The
2D:4D pattern found for gastric cancer parallels that earlier described for
breast cancer. The findings suggest that 2D:4D could add to the list of
etiological factors and be a putative marker for the screening of patients'
susceptibility to develop gastric cancer. BACKGROUND: Research on early life exposures and testicular germ cell tumors
(TGCT) risk has focused on a possible perinatal etiology with a well-known
hypothesis suggesting that hormonal involvement during fetal life is associated
with risk. Second-to-fourth digit ratio (2D:4D) and left-hand domice have
been proposed as markers of prenatal hormone exposure.
AIM: To evaluate associations between 2D:4D digit ratio, right minus left 2D:4D
(ΔR-L), and left-hand domice and TGCT in the U.S. Servicemen's Testicular
Tumor Environmental and Endocrine Determits Study.
METHODS: A total of 246 TGCT cases and 236 non-testicular cancer controls
participated in the current study, and completed a self-administered
questionnaire. Associations between digit ratio, hand domice and TGCT were
estimated using unconditional logistic regression adjusting for identified
covariates.
RESULTS: Right 2D:4D was not associated with TGCT [odds ratio (OR) for a
one-standard deviation (SD) increase in right-hand 2D:4D: 1.12, 95% confidence
interval (CI): 0.93-1.34]. The results were consistent when evaluating the
association based on the left hand. The difference between right and left-hand
2D:4D was also not associated with TGCT risk [OR for a one-SD increase in ΔR-L:
1.03, 95% CI: 0.87-1.23]. Compared to men who reported right-hand domice,
ambidexterity [OR (95% CI)=0.65 (0.30-1.41)] and left-hand domice [OR (95%
CI)=0.79 (0.44-1.44)] were not associated with risk.
CONCLUSIONS: These results do not support the hypothesis that prenatal hormonal
imbalance is associated with TGCT risk. Given the limited sample size, further
evaluation of the relationship between TGCT and prenatal hormonal factors using
digit ratio, ΔR-L, or left-hand domice and larger sample size are warranted. OBJECTIVES: Digit ratio, especially second-to-fourth digit ratio (2D:4D) is
established in utero and is positively correlated with oestrogen in men and
women. It is a putative biomarker for prenatal hormone exposure and may
represent an individual predisposition to certain diseases (e.g., breast
cancer). The aim of the present study is to investigate whether there is a link
between digit ratio (2D:4D) and breast cancer in Chinese populations.
METHODS: The controls we chose were healthy subjects-age and -sex matched to the
patients diagnosed with breast cancer. Photocopies of the two hands of 218 women
(controls: 109; patients: 109) were collected. Left hand, right hand, mean hand,
and right minus left 2D:4D (Dr-l ) were analyzed.
RESULTS: The patients with breast cancer presented significantly higher 2D:4D
than controls (left: P < 0.01; right: P < 0.05; mean: P < 0.05). The mean values
of 2D:4D on the left hand were significantly higher than those on the right hand
in the two groups, respectively (controls: P < 0.05; patients: P ≤ 0.01). In
patients, there was a significantly negative correlation between 2D:4D (left
hand: P < 0.01; right hand, mean: P < 0.05) and the presented age with breast
cancer, but no association between Dr-l and age of presented disease.
CONCLUSIONS: Digit ratio (2D:4D) may correlate with the increased risk of breast
cancer. |
Is TREM2 associated with Alzheimer's disease? | A rare variant of the TREM2 gene, which encodes the triggering receptor encoded in myeloid cells 2 (rs75932628-T) causing a R47H substitution has been associated with both early and late onset Alzheimer's disease in various populations. Emerging evidence has demonstrated that TREM2 could suppress inflammatory response by repression of microglia-mediated cytokine production and secretion, which may prevent inflammation-induced bystander damage of neurons. Higher levels of TREM2 mRNA (p = 0.002) and protein (p < 0.001) were identified in AD patients which indicates that TREM2 might serve as a novel noninvasive biomarker for AD diagnosis. Based on the potential protective actions of TREM2 in AD pathogenesis, targeting TREM2 might provide new opportunities for AD treatment. | Triggering Receptor Expressed on Myeloid cells (TREM)2 deficiency originates a
genetic syndrome characterized by bone cysts and presenile dementia, named
Nasu-Hakola disease (NHD). Early onset dementia and marked involvement of
frontal regions are features characterizing both NHD and other kinds of
neurodegenerative disorders, such as Frontotemporal Lobar Degeneration (FTLD),
and, in some cases, Alzheimer's disease (AD). Three Single Nucleotide
Polymorphisms (SNPs) in TREM2 coding region were screened by allelic
discrimination in a population of probable AD patients as well as FTLD patients
as compared with age-matched controls. In addition, mutation scanning of the
coding region of TREM2 gene was carried out in 7 patients with early onset AD
(EOAD), 16 FTLD, and 20 controls. None of the SNPs analyzed was present, either
in patients or controls. Moreover, mutation scanning of the five exons of TREM2
failed to detect the presence of novel polymorphisms. These data demonstrate
that TREM2 coding region is highly conserved, implying a crucial role of this
receptor. Further studies, including a functional analysis, are certainly
required to clarify the role of TREM2 in neurodegenerative processes. BACKGROUND: Sequence variants, including the ε4 allele of apolipoprotein E, have
been associated with the risk of the common late-onset form of Alzheimer's
disease. Few rare variants affecting the risk of late-onset Alzheimer's disease
have been found.
METHODS: We obtained the genome sequences of 2261 Icelanders and identified
sequence variants that were likely to affect protein function. We imputed these
variants into the genomes of patients with Alzheimer's disease and control
participants and then tested for an association with Alzheimer's disease. We
performed replication tests using case-control series from the United States,
Norway, The Netherlands, and Germany. We also tested for a genetic association
with cognitive function in a population of unaffected elderly persons.
RESULTS: A rare missense mutation (rs75932628-T) in the gene encoding the
triggering receptor expressed on myeloid cells 2 (TREM2), which was predicted to
result in an R47H substitution, was found to confer a significant risk of
Alzheimer's disease in Iceland (odds ratio, 2.92; 95% confidence interval [CI],
2.09 to 4.09; P=3.42×10(-10)). The mutation had a frequency of 0.46% in controls
85 years of age or older. We observed the association in additional sample sets
(odds ratio, 2.90; 95% CI, 2.16 to 3.91; P=2.1×10(-12) in combined discovery and
replication samples). We also found that carriers of rs75932628-T between the
ages of 80 and 100 years without Alzheimer's disease had poorer cognitive
function than noncarriers (P=0.003).
CONCLUSIONS: Our findings strongly implicate variant TREM2 in the pathogenesis
of Alzheimer's disease. Given the reported antiinflammatory role of TREM2 in the
brain, the R47H substitution may lead to an increased predisposition to
Alzheimer's disease through impaired containment of inflammatory processes.
(Funded by the National Institute on Aging and others.). The rs75932628-T variant of the gene encoding the triggering receptor expressed
on myeloid cells 2 (TREM2) has recently been identified as a rare risk factor
for late-onset Alzheimer's disease (AD). In this study we examined the
association between TREM2 exon 2 variants and early-onset AD in a sample of
Caucasian subjects of French origin including 726 patients with age of onset ≤65
years and 783 controls. Only the rs75932628-T variant (predicted to cause an
R47H substitution) conferred a significant risk for early-onset AD (OR, 4.07;
95% CI, 1.3 to 16.9; p = 0.009). These results confirm the association between
this variant and AD and underline its involvement in early-onset cases. Two recent studies have reported the association of rs75932628-T in the TREM2
gene with the risk for Alzheimer's disease (AD). Rs75932628-T is a rare
nonsynonymous variant (p.R47H) that confers a high risk of AD with an effect
size similar to that of the APOE ɛ4 allele. However, this association has not
been replicated in any independent studies to date. The allelic frequency of
rs75932628 varies according to the population from 0.02% to 0.63% among healthy
controls. In an attempt to replicate the association between rs75932628-T and AD
risk, we genotyped rs75932628 in a cohort of 504 AD subjects and 550 healthy
controls from a Spanish population. Rs75932628-T showed a minor allele frequency
of 0.3% among this cohort. Interestingly, in our study, rs75932628-T was found
exclusively in 1.4% of AD cases (7/504), including 4 early-onset AD cases, and
in none of the controls (n = 0/550). Here, we report the first positive
replication study in a Spanish population and confirm that TREM2 rs75932628-T is
associated with the risk for AD. Recent works have demonstrated a rare functional variant (R47H) in triggering
receptor expressed on myeloid cells (TREM) 2 gene, encoding TREM2 protein,
increase susceptibility to late-onset Alzheimer's disease (AD), with an odds
ratio similar to that of the apolipoprotein E ε4 allele. The reduced function of
TREM2 was speculated to be the main cause in the pathogenic effects of this risk
variant, and TREM2 is highly expressed in white matter, as well as in the
hippocampus and neocortex, which is partly consistent with the pathological
features reported in AD brain, indicating the possible involvement of TREM2 in
AD pathogenesis. Emerging evidence has demonstrated that TREM2 could suppress
inflammatory response by repression of microglia-mediated cytokine production
and secretion, which may prevent inflammation-induced bystander damage of
neurons. TREM2 also participates in the regulation of phagocytic pathways that
are responsible for the removal of neuronal debris. In this article, we review
the recent epidemiological findings of TREM2 that related with late-onset AD and
speculate the possible roles of TREM2 in progression of this disease. Based on
the potential protective actions of TREM2 in AD pathogenesis, targeting TREM2
might provide new opportunities for AD treatment. BACKGROUND: Alzheimer's disease (AD) pathophysiology is mostly (>95%) not
inherited in a Mendelian fashion. Such sporadic AD (sAD) forms do not exhibit
familial aggregation and are characterized by complex genetic inheritance.
Growing evidence indicates that multiple genes contribute to sAD-characteristic
endophenotypes, molecular mechanisms, signaling pathways and biomarker
signatures either individually or through complex gene-gene interactions,
lifestyle and the environment.
DISCUSSION: Under the hypothesis that low-prevalence variants showing
moderate-to-high effect size may be associated with risk for sAD, two
independent research groups have demonstrated that a rare variant (rs75932628,
encoding a substitution of arginine by histidine at residue 47 (R47H), in the
TREM2 gene, which encodes the triggering receptor expressed on myeloid cells 2)
is significantly associated with an increased susceptibility to sAD. Another
study has provided intriguing evidence that a low-frequency variant (rs63750847)
in the APP gene is associated with a reduced risk of developing AD and a lower
likelihood of age-related cognitive decline in elderly subjects without AD.
SUMMARY: Recent years have witnessed tremendous development in genetics
technology that has allowed full individualized genome-wide or genomic screening
embracing all of the risk and protective variants for sAD, both across
populations and within individuals. Hopefully, the integration of neurogenetics
with systems biology and high-throughput genotyping will further pave the way to
decipher all of the related causes, mechanisms, and biomarkers across the
spectrum of distinct AD forms. After an almost lost apprentice decade in AD
therapy development, the epoch of individualized asymptomatic screening and
progress in primary and secondary prevention of sAD is probably at its dawn.
Even though we are more at the beginning than at the end of sAD genetics, there
is some reason for optimism given the recent identification of novel risk or
protective variants (such as rare TREM2 and APP mutations) showing strong
statistical associations with sAD. Alzheimer's disease (AD) is an age-related neurodegenerative disorder
characterized by a progressive loss of memory and cognitive skills. Although
much attention has been devoted concerning the contribution of the microscopic
lesions, senile plaques, and neurofibrillary tangles to the disease process,
inflammation has long been suspected to play a major role in the etiology of AD.
Recently, a novel variant in the gene encoding the triggering receptor expressed
on myeloid cells 2 (TREM2) has been identified that has refocused the spotlight
back onto inflammation as a major contributing factor in AD. Variants in TREM2
triple one's risk of developing late-onset AD. TREM2 is expressed on microglial
cells, the resident macrophages in the CNS, and functions to stimulate
phagocytosis on one hand and to suppress cytokine production and inflammation on
the other hand. The purpose of this paper is to discuss these recent
developments including the potential role that TREM2 normally plays and how loss
of function may contribute to AD pathogenesis by enhancing oxidative stress and
inflammation within the CNS. In this context, an overview of the pathways
linking beta-amyloid, neurofibrillary tangles (NFTs), oxidative stress, and
inflammation will be discussed. Recent studies have identified the rs75932628 (R47H) variant in TREM2 as an
Alzheimer's disease risk factor with estimated odds ratio ranging from 2.9 to
5.1. The Cache County Memory Study is a large, population-based sample designed
for the study of memory and aging. We genotyped R47H in 2974 samples (427 cases
and 2540 control subjects) from the Cache County study using a custom TaqMan
assay. We observed 7 heterozygous cases and 12 heterozygous control subjects
with an odds ratio of 3.5 (95% confidence interval, 1.3-8.8; p = 0.0076). The
minor allele frequency and population attributable fraction for R47H were 0.0029
and 0.004, respectively. This study replicates the association between R47H and
Alzheimer's disease risk in a large, population-based sample, and estimates the
population frequency and attributable risk of this rare variant. TREM2 has been reported to be associated with Alzheimer's disease (AD). Here, we
evaluated TREM2 mRNA and protein expressions in peripheral blood from AD
patients and healthy controls. Higher levels of TREM2 mRNA (p = 0.002) and
protein (p < 0.001) were identified in AD patients. We observed a significant
correlation between TREM2 expressions and MMSE score (mRNA: r = -0.482, protein:
r = -0.582; p < 0.01). According to ROC curve analysis, the diagnostic accuracy
for TREM2 protein levels on monocytes was 70%, with the sensitivity and
specificity 68% and 72%, respectively. Our results indicate that TREM2 might
serve as a novel noninvasive biomarker for AD diagnosis. A non-synonymous genetic rare variant, rs75932628-T (p.R47H), in the TREM2 gene
has recently been reported to be a strong genetic risk factor for Alzheimer's
disease (AD). Also, rare recessive mutations have been associated with
frontotemporal dementia (FTD). We aimed to investigate the role of p.R47H
variant in AD and FTD through a multi-center study comprising 3172 AD and 682
FTD patients and 2169 healthy controls from Spain. We found that 0.6% of AD
patients carried this variant compared to 0.1% of controls (odds ratio [OR] =
4.12, 95% confidence interval [CI] = 1.21-14.00, p = 0.014). A meta-analysis
comprising 32,598 subjects from 4 previous studies demonstrated the large effect
of the p.R47H variant in AD risk (OR = 4.11, 95% CI = 2.99-5.68, p =
5.27×10(-18)). We did not find an association between p.R47H and age of onset of
AD or family history of dementia. Finally, none of the FTD patients harbored
this genetic variant. These data strongly support the important role of p.R47H
in AD risk, and suggest that this rare genetic variant is not related to FTD. Homozygous mutations in exon 2 of TREM2, a gene involved in Nasu-Hakola disease,
can cause frontotemporal dementia (FTD). Moreover, a rare TREM2 exon 2 variant
(p.R47H) was reported to increase the risk of Alzheimer's disease (AD) with an
odds ratio as strong as that for APOEε4. We systematically screened the TREM2
coding region within a Belgian study on neurodegenerative brain diseases (1216
AD patients, 357 FTD patients, and 1094 controls). We observed an enrichment of
rare variants across TREM2 in both AD and FTD patients compared to controls,
most notably in the extracellular IgV-set domain (relative risk = 3.84 [95%
confidence interval = 1.29-11.44]; p = 0.009 for AD; relative risk = 6.19 [95%
confidence interval = 1.86-20.61]; p = 0.0007 for FTD). None of the rare
variants individually reached significant association, but the frequency of
p.R47H was increased ~ 3-fold in both AD and FTD patients compared to controls,
in line with previous reports. Meta-analysis including 11 previously screened AD
cohorts confirmed the association of p.R47H with AD (p = 2.93×10(-17)). Our data
corroborate and extend previous findings to include an increased frequency of
rare heterozygous TREM2 variations in AD and FTD, and show that TREM2 variants
may play a role in neurodegenerative diseases in general. |
Does the protein mTOR regulate autophagy? | mammalian target of rapamycin (mTOR) is a major negative regulator of autophagy. | BACKGROUND: The mTOR gene regulates cell growth by controlling mRNA translation,
ribosome biogenesis, autophagy, and metabolism. Abnormally increased expression
of mTOR was associated with carcinogenesis, and its functional single nucleotide
polymorphisms (SNPs) may regulate the expression of mTOR and thus contribute to
cancer risk.
METHODOLOGY/PRINCIPAL FINDINGS: In a hospital-based case-control study of 1004
prostate cancer (PCa) cases and 1051 cancer-free controls, we genotyped six
potentially functional SNPs of mTOR (rs2536 T>C, rs1883965 G>A, rs1034528 G>C,
rs17036508 T>C, rs3806317 A>G, and rs2295080 T>G) and assessed their
associations with risk of PCa by using logistic regression analysis.
CONCLUSIONS/SIGNIFICANCES: In the single-locus analysis, we found a
significantly increased risk of PCa associated with mTOR rs2536 CT/CC and
rs1034528 CG/CC genotypes [adjusted OR = 1.42 (1.13-1.78), P = 0.003 and 1.29
(1.07-1.55), P = 0.007), respectively], compared with their common homozygous
genotypes, whereas mTOR rs2295080 GT/GG genotypes were associated with a
decreased risk of PCa [adjusted OR = 0.76 (0.64-0.92), P = 0.003], compared with
wild-type TT genotypes. In the combined analysis of the six SNPs, we found that
individuals carrying two or more adverse genotypes had an increased risk of PCa
[adjusted OR = 1.24 (1.04-1.47), P = 0.016], compared with individuals carrying
less than two adverse genotypes. In the multiple dimension reduction analysis,
body mass index (BMI) was the best one-factor model with the highest CVC (100%)
and the lowest prediction error (42.7%) among all seven factors. The model
including an interaction among BMI, rs17036508, and rs2536 was the best
three-factor model with the highest CVC (100%) and the lowest prediction error
of 41.9%. These findings suggested that mTOR SNPs may contribute to the risk of
PCa in Eastern Chinese men, but the effect was weak and needs further validation
by larger population-based studies. The mTOR signaling pathway integrates inputs from a variety of upstream stimuli
to regulate diverse cellular processes including proliferation, growth,
survival, motility, autophagy, protein synthesis and metabolism. The mTOR
pathway is dysregulated in a number of human pathologies including cancer,
diabetes, obesity, autoimmune disorders, neurological disease and aging. Ongoing
clinical trials testing mTOR-targeted treatments number in the hundreds and
underscore its therapeutic potential. To date mTOR inhibitors are clinically
approved to prevent organ rejection, to inhibit restenosis after angioplasty,
and to treat several advanced cancers. In this review we discuss the
continuously evolving field of mTOR pharmacogenomics, as well as highlight the
emerging efforts in identifying diagnostic and prognostic markers, including
miRNAs, in order to assess successful therapeutic responses. In this study, we examined whether granulosa cell autophagy during follicular
development and atresia was regulated by the class I phosphoinositide-3
kinase/protein kinase B (AKT) pathway, which is known to control the activity of
mammalian target of rapamycin (mTOR), a major negative regulator of autophagy.
Ovaries and granulosa cells were obtained using an established
gonadotropin-primed immature rat model that induces follicular development and
atresia. Autophagy was evaluated by measuring the expression level of
microtubule-associated protein light chain 3-II (LC3-II) using western blots and
immunohistochemistry. The activity of AKT and mTOR was also examined by
observing the phosphorylation of AKT and ribosomal protein S6 kinase (S6K)
respectively. After gonadotropin injection, LC3-II expression was suppressed and
phosphorylation of AKT and S6K increased in rat granulosa cells. By contrast,
gonadotropin withdrawal by metabolic clearance promoted LC3-II expression and
decreased phosphorylation of AKT and S6K. In addition, in-vitro FSH treatment of
rat granulosa cells also indicated inhibition of LC3-II expression accompanied
by a marked increase in phosphorylation of AKT and S6K. Inhibition of AKT
phosphorylation using AKT inhibitor VIII suppressed FSH-mediated phosphorylation
of S6K, followed by an increase in LC3-II expression. Furthermore, co-treatment
with FSH and AKT inhibitor increased the levels of apoptosis and cell death of
granulosa cells compared with the single treatment with FSH. Taken together, our
findings indicated that AKT-mediated activation of mTOR suppresses granulosa
cell autophagy during follicular development and is involved in the regulation
of apoptotic cell death. AIM: To investigate the effects of mammalian target of rapamycin (mTOR)
inhibition on liver regeneration and autophagy in a surgical resection model.
METHODS: C57BL/6 mice were subjected to a 70% partial hepatectomy (PH) and
treated intraperitoneally every 24 h with a combination of the mTOR inhibitor
rapamycin (2.5 mg/kg per day) and the steroid dexamethasone (2.0 mg/kg per day)
in phosphate buffered saline (PBS) or with PBS alone as vehicle control. In the
immunosuppressant group, part of the group was treated subcutaneously 4 h prior
to and 24 h after PH with a combination of human recombit interleukin 6
(IL-6; 500 μg/kg per day) and hepatocyte growth factor (HGF; 100 μg/kg per day)
in PBS. Animals were sacrificed 2, 3 or 5 d after PH and liver tissue and blood
were collected for further analysis. Immunohistochemical staining for
5-Bromo-2'-deoxyuridine (BrdU) was used to quantify hepatocyte proliferation.
Western blotting was used to detect hepatic microtubule-associated protein 1
light chain 3 (LC3)-II protein expression as a marker for autophagy. Hepatic
gene expression levels of proliferation-, inflammation- and angiogenesis-related
genes were examined by real-time reverse transcription-polymerase chain reaction
and serum bilirubin and transaminase levels were analyzed at the clinical
chemical core facility of the Erasmus MC-University Medical Center.
RESULTS: mTOR inhibition significantly suppressed regeneration, shown by
decreased hepatocyte proliferation (2% vs 12% BrdU positive hepatocyte nuclei at
day 2, P < 0.01; 0.8% vs 1.4% at day 5, P = 0.02) and liver weight
reconstitution (63% vs 76% of initial total liver weight at day 3, P = 0.04),
and furthermore increased serum transaminase levels (aspartate aminotransferase
641 U/L vs 185 U/L at day 2, P = 0.02). Expression of the autophagy marker
LC3-II, which was reduced during normal liver regeneration, increased after mTOR
inhibition (46% increase at day 2, P = 0.04). Hepatic gene expression showed an
increased inflammation-related response [tumor necrosis factor (TNF)-α 3.2-fold
upregulation at day 2, P = 0.03; IL-1Ra 6.0-fold upregulation at day 2 and
42.3-fold upregulation at day 5, P < 0.01] and a reduced expression of cell
cycle progression and angiogenesis-related factors (HGF 40% reduction at day 2;
vascular endothelial growth factor receptor 2 50% reduction at days 2 and 5;
angiopoietin 1 60% reduction at day 2, all P ≤ 0.01). Treatment with the
regeneration stimulating cytokine IL-6 and growth factor HGF could overcome the
inhibitory effect on liver weight (75% of initial total liver weight at day 3, P
= 0.02 vs immunosuppression alone and P = 0.90 vs controls) and partially
reversed gene expression changes caused by rapamycin (TNF-α and IL-1Ra levels at
day 2 were restored to control levels). However, no significant changes in
hepatocyte proliferation, serum injury markers or autophagy were found.
CONCLUSION: mTOR inhibition severely impairs liver regeneration and increases
autophagy after PH. These effects are partly reversed by stimulation of the IL-6
and HGF pathways. Functional intracellular Ca(2+) signaling is essential for the upregulation of
the canonical mTOR-controlled autophagy pathway triggered by rapamycin or by
nutrient deprivation. Moreover, modifications in the Ca(2+)-signaling machinery
coincide with autophagy stimulation. This results in enhanced intracellular
Ca(2+) signaling essential for driving the autophagy process. Yet, the
mechanisms upstream (the players causing the changes in Ca(2+) signaling) and
downstream (the targets of the altered Ca(2+) signals) of this Ca(2+)-dependent
autophagy pathway remain elusive. Here, we speculate about these mechanisms
based on our current knowledge. The mammalian target of rapamycin complex 1 (mTORC1) is a master regulator of
cell growth and proliferation. Recent studies have suggested that constitutive
activation of mTORC1 in normal cells could lead to maligt tumor development
in several tissues. However, the mechanisms of mTORC1 hyperactivation to promote
the growth and metastasis of breast or other cancers are still not well
characterized. Here, using a new inducible deletion system, we show that
deletion of Tsc1 in mouse primary mammary tumor cells, either before or after
their transplantation, significantly increased their growth in vivo. The
increase in tumor growth was completely rescued by rapamycin treatment,
suggesting a major contribution from mTORC1 hyperactivation. Interestingly,
glucose starvation-induced autophagy, but not amino acid starvation-induced
autophagy, was increased significantly in Tsc1-null tumor cells. Further
analysis of these cells also showed an increased Akt activation but no
significant changes in Erk signaling. Together, these results provide insights
into the mechanism by which hyperactivation of mTORC1 promotes breast cancer
progression through increasing autophagy and Akt activation in vivo. Author information:
(1)Freiburg Institute for Advanced Studies (FRIAS); School of Life
Sciences-LifeNet; Freiburg, Germany; ZBSA Center for Biological Systems
Analysis; University of Freiburg; Freiburg, Germany.
(2)Freiburg Institute for Advanced Studies (FRIAS); School of Life
Sciences-LifeNet; Freiburg, Germany; ZBSA Center for Biological Systems
Analysis; University of Freiburg; Freiburg, Germany; Department of Dermatology;
University Freiburg Medical Center; Freiburg, Germany.
(3)BIOSS Centre for Biological Signaling Studies; University of Freiburg;
Freiburg, Germany.
(4)Freiburg Institute for Advanced Studies (FRIAS); School of Life
Sciences-LifeNet; Freiburg, Germany; ZBSA Center for Biological Systems
Analysis; University of Freiburg; Freiburg, Germany; BIOSS Centre for Biological
Signaling Studies; University of Freiburg; Freiburg, Germany.
(5)Centre for High-throughput Biology; Department of Biochemistry and Molecular
Biology; University of British Columbia; Vancouver, BC CA.
(6)Department of Biochemistry and Molecular Biology; University of Southern
Denmark; Odense, Denmark.
(7)Freiburg Institute for Advanced Studies (FRIAS); School of Life
Sciences-LifeNet; Freiburg, Germany; ZBSA Center for Biological Systems
Analysis; University of Freiburg; Freiburg, Germany; Department of Dermatology;
University Freiburg Medical Center; Freiburg, Germany; BIOSS Centre for
Biological Signaling Studies; University of Freiburg; Freiburg, Germany. Autophagy refers to the catabolic process in eukaryotic cells that delivers
cytoplasmic material to lysosomes for degradation. This highly conserved process
is involved in the clearance of long-lived proteins and damaged organelles.
Consequently, autophagy is important in providing nutrients to maintain cellular
function under starvation, maintaining cellular homeostasis, and promoting cell
survival under certain conditions. Several pathways, including mTOR, have been
shown to regulate autophagy. However, the impact of lysosomal function
impairment on the autophagy process has not been fully explored. Basic
lipophilic compounds can accumulate in lysosomes via pH partitioning leading to
perturbation of lysosomal function. Our hypothesis is that these types of
compounds can disturb the autophagy process. Eleven drugs previously shown to
accumulate in lysosomes were selected and evaluated for their effects on
cytotoxicity and autophagy using ATP depletion and LC3 assessment, respectively.
All eleven drugs induced increased staining of endogenous LC3 and exogenous
GFP-LC3, even at non toxic dose levels. In addition, an increase in the
abundance of SQSTM1/p62 by all tested compounds denotes that the increase in LC3
is due to autophagy perturbation rather than enhancement. Furthermore, the gene
expression profile resulting from in vitro treatment with these drugs revealed
the suppression of plentiful long-lived proteins, including structural
cytoskeletal and associated proteins, and extracellular matrix proteins. This
finding indicates a retardation of protein turnover which further supports the
notion of autophagy inhibition. Interestingly, upregulation of genes containing
antioxidant response elements, e.g. glutathione S transferase and NAD(P)H
dehydrogenase quinone 1 was observed, suggesting activation of Nrf2
transcription factor. These gene expression changes could be related to an
increase in SQSTM1/p62 resulting from autophagy deficiency. In summary, our data
indicate that lysosomal accumulation due to the basic lipophilic nature of
xenobiotics could be a general mechanism contributing to the perturbation of the
autophagy process. Several lines of evidence suggest that the mechanism underlying drug-induced
neuronal apoptosis is initiated by the increased production of reactive oxygen
species (ROS). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a
neurotoxin, has been shown to initiate an apoptotic cascade by increasing ROS in
the dopaminergic neurons of the substantia nigra, leading to the morphological
and physiological features associated with Parkinson's disease. Recently, it has
been reported that autophagy, a type of programmed cell death independent of the
apoptotic cascade, also plays a role in neuronal damage. Although autophagy is
negatively regulated by the mammalian target of rapamycin receptor (mTOR), there
is some evidence showing a novel function for the anti-apoptotic protein Bcl-2.
Bcl-2 is proposed to play a role in negatively regulating autophagy by blocking
an essential protein in the signaling pathway, Beclin 1. Nevertheless, it is
unclear whether autophagy is also correlated with apoptotic signaling in
1-methyl-4-phenylpyridinium (MPP(+)) toxicity. Therefore, we hypothesized that
the MPP(+) toxicity generally associated with initiating the apoptotic signaling
cascade also increases an autophagic phenotype in neuronal cells. Using the
SK-N-SH dopaminergic cell lines, we demonstrate that MPP(+) increases the
expression of microtubule-associated protein light chain 3 (LC3-II), an
autophagosome membrane marker and the mTOR signaling pathway, and Beclin 1 while
decreasing the Bcl-2 levels. Moreover, these expressions correlate with a
decreased binding ratio between Bcl-2 and Beclin 1, in effect limiting the
regulation of the downstream autophagic markers, such as LC3-II. Our results
indicate that MPP(+) can induce autophagy in SK-N-SH cells by decreasing the
Bcl-2/Beclin 1 complex. |
Which are the mains risk factors of metabolic syndrome? | Metabolic syndrome is a disorder of energy utilization and storage, diagnosed by a co-occurrence of three out of five of the following medical conditions: abdominal (central) obesity, elevated blood pressure, elevated fasting plasma glucose, high serum triglycerides, and low high-density cholesterol (HDL) levels. Metabolic syndrome increases the risk of developing cardiovascular disease, particularly heart failure, and diabetes. | Metabolic and non metabolic cardiovascular risk factors tend to cluster in the
same individual. The association of the cardiovascular risk factors is referred
as metabolic syndrome (MS). This syndrome is associated with an increased risk
of accelerated atherosclerosis and cardiovascular events. The cluster of
cardiovascular risk factors of the MS includes: insulin resistance with or
without glucose intolerance or diabetes, abdominal obesity, atherogenic
dyslipidemia, elevated blood pressure, a proinflammatory and prothrombotic
state. MS is one of the major issues in the management of cardiovascular disease
because of its epidemic proportion and its impact on increasing risk of
developing both cardiovascular disease and type 2 diabetes. The main therapeutic
goal in the management of patients with the MS is to reduce risk for clinical
cardiovascular events and to prevent type 2 diabetes. In particular, for
individuals with established diabetes, risk factors management must be
intensified to reduce their higher cardiovascular risk. Lifestyle changes have a
critical role in the clinical management of the risk factors predisposing to MS,
such as overweight/obesity, physical inactivity. A large body of evidence
suggests the use of Metformin and Acarbose for the treatment of the syndrome as
these drugs have consistently shown to reduce cardiovascular events and
mortality. Most anti-hypertensive drugs have unfavorable metabolic profile while
b-blockers, centrally acting agents and drugs targeting the renin angiotensin
system should always be considered for the treatment of hypertension in patients
with MS. INTRODUCTION: Metabolic syndrome is increasing among adolescents. We examined
the utility of body mass index (BMI) and waist circumference to identify
metabolic syndrome in adolescent girls.
METHODS: We conducted a cross-sectional analysis of 185 predomitly African
American girls who were a median age of 14 years. Participants were designated
as having metabolic syndrome if they met criteria for 3 of 5 variables: 1) high
blood pressure, 2) low high-density lipoprotein cholesterol level, 3) high
fasting blood glucose level, 4) high waist circumference, and 5) high
triglyceride level. We predicted the likelihood of the presence of metabolic
syndrome by using previously established cutpoints of BMI and waist
circumference. We used stepwise regression analysis to determine whether
anthropometric measurements significantly predicted metabolic syndrome.
RESULTS: Of total participants, 18% met the criteria for metabolic syndrome. BMI
for 118 (64%) participants was above the cutpoint. Of these participants, 25%
met the criteria for metabolic syndrome, whereas only 4% of participants with a
BMI below the cutpoint met the criteria for metabolic syndrome (P <.001). Girls
with a BMI above the cutpoint were more likely than girls with a BMI below the
cutpoint to have metabolic syndrome (P = .002). The waist circumference for 104
(56%) participants was above the cutpoint. Of these participants, 28% met the
criteria for metabolic syndrome, whereas only 1% of participants with a waist
circumference below the cutpoint met the criteria for metabolic syndrome (P
<.001). Girls with a waist circumference above the cutpoint were more likely
than girls with a waist circumference below the cutpoint to have metabolic
syndrome (P = .002). Stepwise regression showed that only waist circumference
significantly predicted metabolic syndrome.
CONCLUSION: Both anthropometric measures were useful screening tools to identify
metabolic syndrome. Waist circumference was a better predictor of metabolic
syndrome than was BMI in our study sample of predomitly African American
female adolescents living in an urban area. OBJECTIVE: The purpose of this study was to explore the association of metabolic
syndrome and each of its components with all-cause and cardiovascular mortality
in a general Italian elderly population.
RESEARCH DESIGN AND METHODS: Metabolic syndrome, diagnosed by National
Cholesterol Education Program Adult Treatment Panel III criteria, all-cause
mortality, and cardiovascular mortality, was evaluated in 2,910 subjects aged >
or =65 years of the Progetto Veneto Anziani (Pro.V.A.) Study during a mean
follow-up time of 4.4 years.
RESULTS: After multivariable adjustment, metabolic syndrome was associated with
increased all-cause mortality in all subjects (hazard ratio 1.41 [95% CI
1.16-1.72], P = 0.001), among men (1.42 [1.06-1.89], P = 0.017), and among women
(1.47 [1.13-1.91], P = 0.004). High glucose in all subjects (1.27 [1.02-1.59], P
= 0.037) and in women (1.61 [1.16-2.24], P = 0.005) and low HDL cholesterol in
women (1.48 [1.08-2.02], P = 0.014) were predictors of all-cause mortality, even
independently of the interactions of different metabolic syndrome components.
After multivariable adjustment, metabolic syndrome was also associated with
increased cardiovascular mortality in all subjects (1.60 [1.17-2.19], P =
0.003), among men (1.66 [1.00-2.76], P = 0.051), and among women (1.60
[1.06-2.33], P = 0.025). High glucose (2.17 [1.28-3.68], P = 0.004) and low HDL
cholesterol (1.78 [1.07-2.95], P = 0.026) among women predicted higher
cardiovascular mortality.
CONCLUSIONS: In this general Italian elderly population, among metabolic
syndrome components, all-cause mortality is better predicted by high glucose in
all subjects and in women and by low HDL cholesterol in women, whereas
cardiovascular mortality is better predicted by high glucose and low HDL
cholesterol in women. BACKGROUND: The availability of several definitions of the metabolic syndrome
has created potential confusion concerning its prognostic utility. At present,
little data exist about the risk factors associated with metabolic syndrome in
diabetic patients.
AIM: To identify risk factors associated with metabolic syndrome in patients
with type 2 diabetes mellitus according to three diagnostic criteria: World
Health Organization (WHO), Third Report of the National Cholesterol Education
Program Expert Panel on Detection, Evaluation, and Treatment of High Blood
Cholesterol in Adults - Adult Treatment Panel III (NCEP-ATP III), and
International Diabetes Federation (IDF).
SUBJECTS AND METHODS: A logistic regression model was used to identify
demographic, clinical, and lifestyle variables related with metabolic syndrome
(N = 1259).
RESULTS: Hypertension, dyslipidemia, and glycosylated hemoglobin (HbA(1c)) ≥7%
were associated with increased risk of WHO-defined metabolic syndrome (odds
ratio [OR], 2.33; 95% confidence interval [CI]: 1.60-3.40; OR, 1.79 95% CI:
1.25-2.55; and OR, 1.58; 95% CI: 1.12-2.22, respectively). The risk of
presenting metabolic syndrome according to NCEP-ATP III criteria was increased
in female patients (OR, 2.02; 95% CI: 1.37-2.97), elevated fasting glucose
levels (OR, 5.99; 95% CI: 3.56-10.07), dyslipidemia (OR, 2.28; 95% CI:
1.57-3.32), hypertension (OR, 2.36; 95% CI: 1.59-3.53), and endocrine disorders
(OR, 1.64; 95% CI: 1.06-2.57). For the IDF criteria, female patients and
patients with left ventricular hypertrophy or insulin treatment were at higher
risk of metabolic syndrome (OR, 4.00; 95% CI: 2.35-6.80; OR, 2.72 95% CI:
1.22-6.04; and OR, 1.96 95% CI: 1.24-3.11, respectively).
CONCLUSIONS: The risk factors for metabolic syndrome in type 2 diabetes mellitus
patients are highly dependent on the criteria used to define the syndrome,
supporting the need for a single clinically useful and epidemiologically useful
definition. OBJECTIVE: Although African American adolescents have the highest prevalence of
obesity, they have the lowest prevalence of metabolic syndrome across all
definitions used in previous research. To address this paradox, we sought to
develop a model of the metabolic syndrome specific to African American
adolescents.
RESEARCH DESIGN AND METHODS: Data from the National Health and Nutrition
Examination Survey (2003-2010) of 822 nonpregt, nondiabetic, African American
adolescents (45% girls; aged 12 to 17 years) who underwent physical examinations
and fasted at least 8 h were analyzed. We conducted a confirmatory factor
analysis to model metabolic syndrome and then used latent profile analysis to
identify metabolic syndrome risk groups among African American adolescents. We
compared the risk groups on probability of prediabetes.
RESULTS: The best-fitting metabolic syndrome model consisted of waist
circumference, fasting insulin, HDL, and systolic blood pressure. We identified
three metabolic syndrome risk groups: low, moderate, and high risk (19% boys;
16% girls). Thirty-five percent of both boys and girls in the high-risk groups
had prediabetes, a significantly higher prevalence compared with boys and girls
in the low-risk groups. Among adolescents with BMI higher than the 85th
percentile, 48 and 36% of boys and girls, respectively, were in the high-risk
group.
CONCLUSIONS: Our findings provide a plausible model of the metabolic syndrome
specific to African American adolescents. Based on this model, approximately 19
and 16% of African American boys and girls, respectively, are at high risk for
having the metabolic syndrome. Decrements in cognitive functioning have been linked to the metabolic syndrome
(MetS), a risk factor for cardiovascular disease defined by the presence of
three of the following: elevated blood pressure, increased waist circumference,
elevated blood glucose, elevated triglycerides, and low high-density lipoprotein
cholesterol. We examined the relationship between four measures of executive
functioning (EF) and MetS as diagnosed by National Heart, Lung, and Blood
Institute-American Heart Association criteria. MetS was examined in a rural
population of 395 persons with a mean age of 61.3 years, 71.4% women, 37.0%
Hispanic, 53.7% White non-Hispanic. There was a 61.0% prevalence of MetS. We
derived a factor score from the four executive function measures which was used
to compare those with and without the syndrome, as well as any additive effects
of components of the syndrome. Those with MetS exhibited significantly poorer
performance than those without the syndrome. However, there was no additive
effect, having more components of the syndrome was not related to lower
performance. The presence of MetS was associated with poorer EF in this rural
cohort of community dwelling volunteers. Prior studies evaluating metabolic syndrome (MetS) and incident peripheral
artery disease (PAD) have been limited by use of modified MetS criteria and
restriction to clinical PAD end points. We investigated MetS and risk of
developing a low ankle-brachial index (ABI) and clinical PAD in the
Cardiovascular Health Study, a population-based cohort of adults aged ≥65 years.
Participants with MetS met at least 3 of 5 Adult Treatment Panel III criteria.
Baseline C-reactive protein-MetS or fibrinogen-MetS were defined as presence of
3 of 6 components, with elevated C-reactive protein (>3 mg/L) or fibrinogen
(>341 mg/dL) as a sixth component. Incident low ABI, defined as ABI <0.9 and
decline of ≥0.15, was assessed among a subset of 1899 individuals with 2 ABI
measurements 6 years apart. Over a median follow-up of 13.7 years, 4632
individuals were followed up for clinical PAD, defined as revascularization or
diagnosed claudication. Adult Treatment Panel III MetS was associated with both
incident low ABI (risk ratio, 1.26; 95% confidence interval [CI], 1.00-1.58) and
clinical PAD (hazard ratio, 1.47; 95% CI, 1.11-1.94). Incorporating C-reactive
protein or fibrinogen into Adult Treatment Panel III criteria identified an
additional 16% to 20% of individuals as having MetS, and both C-reactive
protein-MetS and fibrinogen-MetS were associated with incident low ABI (risk
ratio, 1.36; 95% CI, 1.07-1.72 and risk ratio, 1.43; 95% CI, 1.13-1.81,
respectively) and clinical PAD (hazard ratio, 1.56; 95% CI, 1.17-2.08 and hazard
ratio, 1.55; 95% CI, 1.17-2.07, respectively). Among Adult Treatment Panel III
MetS criteria, risk of PAD was most strongly associated with hypertension. AIM: Charcot neuroarthropathy is a very rare form of diabetic foot syndrome
occurring among others in patients with diabetes mellitus. Charcot
neuroarthropathy leads to bone tissue destruction and may result in foot
amputation. The aim of the study was to identify risk factors of Charcot
neuroarthropathy occurrence in patients with diabetic foot and type 2 diabetes.
MATERIALS: The study included 144 patients with type 2 diabetes; 33 with Charcot
neuroarthropathy and 111 with diabetic foot of neuropathic origin without
neuroarthropathy. The study was perform in Gastroenterology and Metabolic
Diseases Department, Medical University of Warsaw, Poland.
RESULTS: The regression analysis showed that Charcot neuroarthropathy occurrence
risk factors were: male gender (OR=4.94, 95% CI:1.63-15.03, p=0.003), age
(OR=0.92, 95% CI:0.87-0.96, p=0.0001), diabetic foot duration (OR=1.19,
95% CI:1.08-1.32, p=0.00002) and height (OR=1.078, 95% CI:1.019-1.140, p=0.007).
A positive effect on Charcot neuroarthropathy presence was exerted by body
weight (OR=1.027, 95% CI:1.003-1.051, p=0.03) and hips circumference (OR=1.034,
95% CI:0.997-1.072, p=0.04).
CONCLUSIONS: The existence of the specific factors influencing Charcot
neuroarthropathy development may result in earlier identification of patients at
risk of its development. There is a necessity to take special care for patients
prone to develop Charcot neuroarthropathy in order to prevent its occurrence and
severe complications. Recent genome-wide association studies have identified several single nucleotide
polymorphisms (SNPs) associated with body mass index (BMI)/obesity. In this
study, we aim to examine the associations of obesity related loci with risk of
metabolic syndrome (MetS) in a children population from China. A total of 431
children with MetS and 3046 controls were identified based on the modified
ATPIII definition. 11 SNPs (FTO rs9939609, MC4R rs17782313, GNPDA2 rs10938397,
BDNF rs6265, FAIM2 rs7138803, NPC1 rs1805081, SEC16B rs10913469, SH2B1
rs4788102, PCSK1rs6235, KCTD15 rs29941, BAT2 rs2844479) were genotyped by TaqMan
7900. Of 11 SNPs, GNPDA2 rs10938397, BDNF rs6265, and FAIM2 rs7138803 were
nominally associated with risk of MetS (GNPDA2 rs10938397: odds ratio (OR)=1.21,
95% confidence interval (CI)=1.04-1.40, P=0.016; BDNF rs6265: OR=1.19, 95%
CI=1.03-1.39, P=0.021; FAIM2 rs7138803: OR=1.20, 95% CI=1.02-1.40, P=0.025);
genetic risk score (GRS) was significantly associated with risk of MetS
(OR=1.09, 95% CI=1.04-1.15, P=5.26×10(-4)). After further adjustment for BMI,
none of SNPs were associated with risk of MetS (all P>0.05); the association
between GRS and risk of MetS remained nominally (OR=1.02, 95%CI=0.96-1.08,
P=0.557). However, after correction for multiple testing, only GRS was
statistically associated with risk of MetS in the model without adjustment for
BMI. The present study demonstrated that there were nominal associations of
GNPDA2 rs10938397, BDNF rs6265, and FAIM2 rs7138803 with risk of MetS. The SNPs
in combination have a significant effect on risk of MetS among Chinese children.
These associations above were mediated by adiposity. Alcoholic liver disease (ALD) remains a major cause of chronic liver diseases
and liver failure. Population-based prospective studies and patient cohort
studies have demonstrated that obesity and the metabolic syndrome exacerbate
progression of ALD and increase hepatocellular carcinoma (HCC) incidence and
mortality. Emerging evidence also suggests a synergism between alcohol and
obesity in mortality and HCC incidence. Recognition of these increased risks and
detection of early-stage liver disease may offer the opportunity to address
these modifiable risk factors and prevent disease progression in these patients. China is gradually taking its place as one of the world's economic giants and
concurrently learning to understand how to bear the burdens of diseases that are
more common in the fully developed world, such as pediatric obesity, metabolic
syndrome, and type 2 diabetes mellitus. The purpose of this review is to
consolidate the available information regarding these and draw the focus toward
their sequential progression and increasing prevalence in Chinese children.
Studies were collected in both English and Chinese, and the data were reviewed
on the basis of disease prevalence and risk factors that are known from
scientific literature that has been published to date. The majority of studies
with appropriate content for inclusion here have been conducted within the last
15 years and up to date information from recent local and international research
has also been included. Several factors have been implicated for the rise in
obesity, most notably, the progressing economic expansion and exposure of local
Chinese populations to Western influences. With this, metabolic syndrome has
become a growing concern, as it is a precursor to cardiovascular disease and
type 2 diabetes, leading to the alarmingly rapid development of deleterious
consequences in children. The International Diabetes Federation proposed a
definition for metabolic syndrome in 2007 (MS-IDF2007) worldwide, but whether it
is also suitable for the Chinese population remains uncertain, so we have
created the Chinese definition of metabolic syndrome upon the IDF framework.
This MS-CHN2012 definition is based on multicenter studies to simplify and
standardize primary care screening methods and is the first of its kind in
China. Juvenile type 2 diabetes is the most worrisome result of obesity and
metabolic syndrome, and studies have shown that the prevalence has doubled
within 5 years-surpassing the prevalence of juvenile type 1 diabetes. Because of
the extremely low number of studies currently published on these topics in
China, emphasis needs to be placed on the assessment of the health status of the
population. Screening methods are imperative because lifestyle interventions can
reduce and even reverse the pathologic consequences of this disease, if detected
early. Cardiometabolic disorders have been associated with primary hyperparathyroidism
(PHPT), while the relationship of cardiovascular risk score (CRS) and metabolic
syndrome (MS) with different clinical presentation of PHPT remains undefined.
Our aim was to evaluate CRS, MS and its components in PHPT looking for their
correlation to different clinical forms. In 68 consecutive PHPT patients and 68
matched controls, CRS, MS and its components were assessed to perform an
observational case-control study at an ambulatory referral center for Bone
Metabolism Diseases. Patients were stratified in symptomatic and asymptomatic
PHPT; these latter were divided in high-risk and low-risk subgroups for
end-organ damage. An increased proportion of PHPT patients had intermediate-high
CRS and MS (mean, 95 % Confidence Interval (CI) 51.5 %, 39.6-63.3 and 20.6 %,
11.0-30.2, respectively, p < 0.02 vs. controls). Intermediate-high CRS was
prevalent both in symptomatic and low-risk asymptomatic PHPT while MS resulted
prevalent in low-risk asymptomatic but not in symptomatic PHPT. Type 2 DM, IFG,
mixed dyslipidemia, hypertriglyceridemia, HDL-hypocholesterolemia, and
LDL-hypercholesterolemia predominated in low-risk asymptomatic, while only
LDL-hypercholesterolemia prevailed also in symptomatic PHPT. In patients and
controls without cardiometabolic risk factors, HOMA-IR index was significantly
increased in PHPT vs. controls (p < 0.03) and associated to total calcium (R =
0.73; p < 0.001). By multivariate analysis low-risk asymptomatic PHPT predicted
MS after adjusting for age, sex, and BMI. Our data show an increased frequency
of intermediate-high CRS both in symptomatic and low-risk asymptomatic PHPT
while MS prevails in low-risk asymptomatic PHPT, supporting the potential for
cardiovascular morbidity and mortality also in this form. OBJECTIVE: The metabolic syndrome (MetS) is typically diagnosed based on
abnormalities in specific clustered clinical measures that are associated with
increased risk for coronary heart disease (CHD) and Type 2 diabetes mellitus
(T2DM). However, current MetS criteria result in racial/ethnic discrepancies.
Our goals were to use confirmatory factor analysis (CFA) to delineate
differential contributions to MetS by sub-group, and if contributions were
discovered, develop sex and racial/ethnic-specific equations to calculate MetS
severity.
RESEARCH DESIGN AND METHODS: Using data on adults from the National Health and
Nutrition Examination Survey 1999-2010, we performed a CFA of a single MetS
factor that allowed differential loadings across groups, resulting in a sex and
race/ethnicity-specific continuous MetS severity score.
RESULTS: Loadings to the single MetS factor differed by sub-group for each MetS
component (p<0.001), with lower factor loadings among non-Hispanic-blacks for
triglycerides and among Hispanics for waist circumference. Systolic blood
pressure exhibited low factor loadings among all groups. MetS severity scores
were correlated with biomarkers of future disease (high-sensitivity
C-reactive-protein, uric acid, insulin resistance). Non-Hispanic-black-males
with diabetics had a low prevalence of MetS but high MetS severity scores that
were not significantly different from other racial/ethnic groups.
CONCLUSIONS: This analysis among adults uniquely demonstrated differences
between sexes and racial/ethnic groups regarding contributions of traditional
MetS components to an assumed single factor. The resulting equations provide a
clinically-accessible and interpretable continuous measure of MetS for potential
use in identifying adults at higher risk for MetS-related diseases and following
changes within individuals over time. These equations hold potential to be a
powerful new outcome for use in MetS-focused research and interventions. Dietary patterns contribute to cardiovascular disease (CVD) risk. Asian Indians
have earlier onset, more severe, and more prevalent CVD than many other
racial/ethnic groups. We aimed to characterize dietary patterns in Asian Indians
living in the United States and examine associations with cardiometabolic risk
factors. One hundred fifty Asian Indians, aged 45 to 84 years, without known
CVD, living in the San Francisco Bay, CA, area between August 2006 and October
2007 were enrolled into the Metabolic syndrome and Atherosclerosis in South
Asians Living in America study. A food frequency questionnaire validated in
Asian Indians, fasting blood samples, and computed tomography scans were
obtained for all participants. Principal component analysis with varimax
rotation was used to determine prevalent dietary patterns. Linear regression
analyses were performed for associations between dietary patterns and metabolic
factors, adjusting initially for age and sex, then additionally for BMI, income,
education, metabolic equivalent of task-minutes of exercise, alcohol
consumption, and smoking. Two distinct dietary patterns were identified that we
termed "Western," and "Vegetarian." Compared with the Western diet, the
Vegetarian diet was associated with lower homeostasis model of
assessment-insulin resistance (-1.12 mmol/L × mU/L; P=0.05) and lower
high-density lipoprotein cholesterol (-4.77 mg/dL; P=0.09). Given that the
Western and Vegetarian dietary patterns were each associated with adverse
metabolic changes, healthful diet choices may help Asian Indians improve risk
factors for CVD. INTRODUCTION: Although mortality rates from cardiovascular diseases have shown a
remarkable decline in many western countries, cardiovascular mortality in
Lithuania has remained high. It is widely accepted that half of the decline in
cardiovascular mortality can be attributed to favourable changes in modifiable
risk factors.
METHODS: In 2006, the Lithuanian High Cardiovascular Risk Programme was started.
A two-level approach--primary health care institutions and specialised
cardiovascular prevention units--was applied. The cardiovascular risk profile
was evaluated for a group of 17,031 middle-aged subjects enrolled into the
programme at a primary level and 2908 at a specialised level.
RESULTS: Among the persons examined, 61.8% (10,519) were female. Arterial
hypertension was present in 60.2% of the subjects. Dyslipidaemia was present in
88.8%. Total cholesterol was 6.02 ± 1.23 mmol/L, LDL cholesterol 3.74 ± 1.09
mmol/L, HDL cholesterol 1.53 ± 0.52 mmol/L, and triglycerides 1.61 ± 1.27
mmol/L. Diabetes mellitus was found in 10.3%, abdominal obesity in 45.4%, and
metabolic syndrome in 43.8% of cases. These values were even greater in
high-risk subjects.
CONCLUSIONS: In middle-aged subjects the prevalence of dyslipidaemia, arterial
hypertension, diabetes, and metabolic syndrome was found to be high. We can
roughly state that almost nine out of ten middle-aged subjects in Lithuania have
established dyslipidaemia, every second one has established arterial
hypertension, and four out of ten are obese. Hence, these are the main risk
factors that should be considered first of all in daily clinical practice. Peroxisome proliferator activated receptor-gamma (PPARG) and lipoprotein lipase
(LPL) play important role in lipid homeostasis, insulin resistance and
adipogenesis, and their gene variability could be considered as predictive
genetic markers for metabolic syndrome (MetSy). The aim of the study was to
estimate possible associations of PPARG (Pro12Ala) and LPL PvuII (+/-)
polymorphisms with MetSy and its traits. Study included 527 subjects. According
to the modified National Cholesterol Education Program Adult Treatment Panel III
definitions, subjects were classified into the metabolic syndrome group and
control group. Genotyping was performed using polymerase chain
reaction-restriction fragment length polymorphism methods. In the total sample,
LPL variants were associated with waist circumference (chi2 = 7.263, d.f = 2, p
= 0.026) and with BMI (chi2 = 6.549, d.f = 2, p = 0.038), where PvuII (+/+)
genotype carriers had the highest risk for increased waist circumference
(specific PvuII (+/+) vs. others analysis chi2 = 7.033, p = 0.008) and increased
BMI (specific PvuII( +/+) vs. others analysis chi2 = 5.154, p = 0.023). LPL gene
variants were also associated with HDL-C levels (chi2 = 6.901, d.f = 2, p =
0.032), where PvuII (-/-) genotype carriers had higher HDL-C values in
comparison to others (specific Pvu (+/+) vs. others analysis chi2 = 6.504, p =
0.011). Furthermore, PvuII (-) allele carriers had significantly lower glucose
(allele based analysis Add Value = -0.0878, chi2 = 5.878, d.f. = 1, p = 0.015).
Significant interaction was detected between PPARG and LPL that affected HDL-C
levels in male population (chi2 = 11.790, d.f = 1, p = 0.0006) in the manner
that Ala/PvuII(+) contributed to the lowest HDL-C values (Specific Ala/ Pvu(+)
vs. others analysis was chi2 = 11.750, p = 0.0006). According to obtained
results LPL and PPARG gene variants could be susceptibility factors of obesity
and lipid status, contributing to development of MetSy, particularly in males.
Because of antiatherogenic function of HDL-C, the identification of genetic
variants associated with HDL-C can provide useful information related to
genotype-phenotype relationships. Since the interplay between PPARG and LPL gene
and gender seems to be significant it could point to the personalized
behavioural recommendations for prevention of metabolic and cardiovascular
diseases. OBJECTIVE: Serum uric acid (SUA) levels correlate with many recognized
cardiovascular risk factors, including age, male sex, hypertension, diabetes
mellitus, hypertriglyceridemia, obesity, and insulin resistance. The aim of our
study was to verify in a large well characterized population sample the
relationship between SUA values, hypertension, arterial stiffness and
subclinical atherosclerosis.
METHODS: For this study, we selected 248 men and 371 women adult patients
enrolled in the last Brisighella Heart Study population survey for which a full
set of data were available and not consuming antihypertensive, antidiabetic,
lipid-lowering and uric acid-lowering drugs. SUA and other available variables
were related to blood pressure level, carotid-femoral pulse wave velocity
(cfPWV) and carotid intima-media thickness (cIMT).
RESULTS: Hypertension prevalence was strongly related to SUA quartiles: we found
significant differences between the 2nd (23.0%) and the 3rd quartiles (36.4%; P
vs. 2nd < 0.05), and between the 3rd and the 4th quartile (56.3%; P vs.
3rd < 0.05). Similarly, the metabolic syndrome prevalence increased
significantly at 39.5% in the 3rd SUA quartile (P < 0.05 vs. 2nd) and at 58.9%
in the 4th quartile (P < 0.05 vs. 3rd). Intima-media thickness gradually and
significantly rose along quartiles of SUA (P for trend < 0.0001), in particular,
it was 0.86 mm in the 1st quartile, 0.90 in the 2nd, 0.94 in the 3rd, and 0.97
in the last quartile, with significant differences between each quartiles (all
P < 0.05). In multivariate regression analyses, SUA resulted to be significantly
associated to hypertension and metabolic syndrome prevalence, and IMT. Even if a
significant association between SUA and cfPWV was found in univariate analysis
(P = 0.002), when adjusting for age, the trend became nonsignificant (0.20).
CONCLUSION: In the studied population sample, after adjustment for a large
number of parameters, SUA appears to be significantly correlated to hypertension
and IMT, but not to aortic stiffness. OBJECTIVES: To evaluate the possible association between pressure pain
sensitivity of the chest bone (PPS) and cardiovascular physiological factors
related to persistent stress in connection with a three-month PPS-guided
stress-reducing experimental intervention programme.
METHODS: Forty-two office workers with an elevated PPS (≥ 60 arbitrary units) as
a sign of increased level of persistent stress, completed a single-blinded
cluster randomized controlled trial. The active treatment was a PPS
(self-measurement)-guided stress management programme. Primary endpoints: Blood
pressure (BP), heart rate (HR) and work of the heart measured as
Pressure-Rate-Product (PRP); Secondary endpoints: Other features of the
metabolic syndrome.
RESULTS: PPS decreased and changes in PPS after the intervention period were
significantly associated with HR, PRP, body mass index (BMI) and visceral fat
index (all correlation coefficients > 0.2, p < 0.05). Compared to the control
cluster group, the active cluster group obtained a significant reduction in PPS,
Low-density lipoprotein (LDL) cholesterol and total number of elevated risk
factors (p < 0.05). On an individual level, significant and clinically relevant
between-group reductions were observed in respect to BP, HR, PRP, total and LDL
cholesterol, and total number of elevated risk factors (p < 0.05).
CONCLUSIONS: The stress intervention method applied in this study induced a
decrease in PPS which was associated with a clinically relevant decrease in
resting blood pressure, heart rate, work of the heart and serum cholesterols. INTRODUCTION: The metabolic syndrome (MS) components, such as dyslipidemia,
prothrombotic status, and increased blood pressure, are risk factors for
patients with renal disease. Visceral fat mass is closely related to the MS and
atherosclerosis. We investigated the effects of body compositions and MS on
anemia parameters and recombit human erythropoietin (rHuEPO) requirements in
maintece hemodialysis patients.
METHODS: Body composition (body mass index and bioimpedance analysis) and
laboratory data were obtained from 110 dialysis patients. The MS was identified
according to ATP-III criteria. Anemia parameters, hemoglobin (Hgb), albumin,
C-reactive protein (CRP), calcium, phosphorus, parathormone levels, and rHuEPO
requirements over the last 6 months were retrospectively analyzed.
RESULTS: Patients with the MS seem to reach target Hgb levels more frequently
(10-12 g/dL; 66.3% vs 84.8%; P = .03) without any difference in total
intravenous iron therapy dosage. MS patients also required lower rHuEPO for
reaching similar Hgb levels compared with patients without MS (2679.3 ± 1936.1
vs 3702.5 ± 2213.0 U/kg/6 mo; P = .02). There were no differences in serum CRP,
albumin, or Hgb levels between the 2 groups (P > .05). We observed that patients
with MS had significantly higher fat mass and visceral fat ratio, but similar
muscle mass values compared with no-MS counterparts (P = .0001 and .001,
respectively). However, when we compared the ratios of these parameters we
observed a significant reduction in muscle ratios and a significant increase in
fat ratios of MS patients (P = .0001).
CONCLUSION: Our results indicate that MS might be an advantage for reaching
higher Hgb levels with lower rHuEPO dosages. The possible reason for this might
be the good nutritional state and increased fat mass of patients with MS. AIM: Individual components of the metabolic syndrome (MS), especially obesity
and hypertension, have a deleterious effect on renal graft outcome. Whether MS
is better than its individual components in predicting the decline of renal
function is unknown. We studied the presence of MS and its individual components
at 12 months post-transplantation according to the Adult Treatment Panel III
classification and their influence on measured graft function.
METHODS: A cohort of 322 patients who underwent transplantation between 1996 and
2003 and who agreed to have their glomerular filtration rate (GFR) measured by
urinary clearance of technetium 99m (Tc*-DTPA) (measured GFR [mGFR]) at 3, 12,
48, 60, and 96 months after transplantation were included. The patients were
followed up until patient death, graft loss, or December 2009 (mean follow-up: 3
± 2.8 years). The linear mixed effect model for longitudinal repeated measures
was applied. To compare MS versus its components we used the Akaike information
Criterion (AIC) to determine the best model according to the Anderson and
Burnham method.
RESULTS: Univariate and multivariate analyses models using MS were more
efficient than those using the individual components, which consisted of waist
circumference, low high-density lipoprotein-cholesterol, hypertriglyceridemia,
hyperglycemia, and systolic and diastolic blood pressure. The AIC was the lowest
with MS models indicating better prediction on graft function than the
individual components.
CONCLUSION: MS is a better predictor of mGFR decline than its individual
components. It is a valid and precious tool to assess outcomes. The prevalence of the metabolic syndrome (MetS), a cluster of cardiovascular
risk factors associated with obesity and insulin resistance, is dramatically
increasing in Western and developing countries. This disorder is not only
associated with a higher risk of appearance of type 2 diabetes and
cardiovascular events, but impacts on the liver in different ways. Nonalcoholic
fatty liver disease (NAFLD) is considered the hepatic manifestation of MetS, and
is characterized by triglyceride accumulation and a variable degree of hepatic
injury, inflammation, and repair. In the presence of significant hepatocellular
injury and inflammation, the picture is defined 'nonalcoholic steatohepatitis'
(NASH), that has the potential to progress to advanced fibrosis and cirrhosis.
Diagnosis of NASH is based on a liver biopsy, and active search for noninvasive
tests is ongoing. Progression of steatohepatitis to advanced fibrosis or
cirrhosis has been shown in at least one third of patients followed with paired
biopsies. Presence of NASH is associated with lower life expectancy, both due to
liver-related death and to an increase in cardiovascular events. The appearance
of NAFLD is mainly dependent on increased flow of fatty acids derived from an
excess of lipolysis from insulin-resistant adipose tissue. Development of NASH
is based on lipotoxicity and is influenced by signals derived from outside the
liver and from intrahepatic activation of inflammatory and fibrogenic pathways.
The presence of the MetS is also associated with worse outcomes in patients with
cirrhosis due to any causes, and has complex interactions with hepatitis C virus
infection. Moreover, MetS poses a higher risk of development of hepatocellular
carcinoma, not necessarily through the development of NASH-related cirrhosis. In
conclusion, the presence of metabolic alterations has a severe and multifaceted
impact on the liver, and is responsible for a higher risk of liver-dependent and
-independent mortality. The metabolic syndrome (MetS) is characterized by a cluster of risk factors
including central obesity, hypertension, dyslipidemia and insulin resistance,
The MetS is associated with an increased risk for cardiovascular disease (CVD)
and type 2 diabetes mellitus (T2DM). Several international organizations have
defined MetS using different diagnostic criteria that produced discrepancies in
the results of previous studies, thus leading to the latest Joint Interim
Societies (JIS) MetS definition. Other risk factors than the diagnostic criteria
that have been associated with MetS include lipid abnormalities, uric acid,
liver function, prothrombotic factors, cytokines, adipokines, vitamin D,
arterial stiffness, polycystic ovary syndrome and obstructive sleep apnea. Apart
from CVD and T2DM, MetS has been related to non-cardiac vascular diseases and in
particular to stroke, carotid artery disease, peripheral artery disease, chronic
kidney disease, atherosclerotic renal artery stenosis and abdominal aortic
aneurysms. In this narrative review, the associations of these diseases with
MetS and its components will be discussed. These associations may further
increase CVD risk in MetS patients, highlighting the importance of treating such
high-risk individuals early and "to target". In this context, multifactorial
treatment including a statin has been proven beneficial, and thus should be
considered, in MetS patients. Although the association between alopecia areata (AA), psoriasis, and other
autoimmune diseases has been well reported in the literature, an association
with metabolic syndrome has not been reported. We present two young women with
the combination of severe psoriasis, androgen excess, metabolic syndrome,
thyroiditis, and AA. Both women ultimately progressed to treatment-resistant
alopecia universalis. This constellation of autoimmunity and metabolic syndrome
presents a therapeutic challenge while highlighting the need for full laboratory
assessment of AA patients. Careful selection of biological treatment regimens
may offer therapeutic benefit for both their psoriasis and AA while giving us
experience with the newer biologics in AA. We investigated the association between circulating levels of 60 and 70 kDa
heat-shock proteins (HSP60 and 70) and cardiovascular risk factors in
postmenopausal women with or without metabolic syndrome (MetS). This
cross-sectional study included 311 Brazilian women (age ≥45 years with
amenorrhea ≥12 months). Women showing three or more of the following diagnostic
criteria were diagnosed with MetS: waist circumference (WC) ≥88 cm, blood
pressure ≥130/85 mmHg, triglycerides ≥150 mg/dl, high-density lipoprotein (HDL)
<50 mg/dl, and glucose ≥100 mg/dl. Clinical, anthropometric, and biochemical
parameters were collected. HSP60, HSP70, antibodies to HSP60 and HSP70, and
C-reactive protein (CRP) levels were measured in serum. Student's t test,
Kruskal-Wallis test, chi-square test, and Pearson correlation were used for
statistical analysis. Of the 311 women, 30.9 % (96/311) were diagnosed with
MetS. These women were, on average, obese with abdominal fat deposition and had
lower HDL values as well as higher triglycerides and glucose levels. Homeostasis
model assessment-insulin resistant (HOMA-IR) test values in these women were
compatible with insulin resistance (P < 0.05). CRP and HSP60 concentrations were
higher in women with MetS than in women without MetS (P < 0.05). HSP60,
anti-HSP70, and CRP concentrations increased with the number of features
indicative of MetS (P < 0.05). There was a significant positive correlation
between anti-HSP70 and WC, blood pressure and HOMA-IR, and between CRP and WC,
blood pressure, glucose, HOMA-IR, and triglycerides (P < 0.05). In
postmenopausal women, serum HSP60 and anti-HSP70 concentrations increased with
accumulating features of the metabolic syndrome. These results suggest a greater
immune activation that is associated with cardiovascular risk in postmenopausal
women with metabolic syndrome. |
Which multiple kinase inhibitors are used in cancer therapy? | Multiple kinase inhibitors used in cancer therapy include ZD6474, SU11248, AEE 788, sorafenib, vatalanib, and AG-013736. | Growth factor signals are propagated from the cell surface to intracellular
processes that control critical functions such as growth, differentiation,
angiogenesis, and inhibition of apoptosis via sequential kinase signaling. These
kinases are receptor kinases, which are transmembrane proteins such as epidermal
growth factor receptor or cytoplasmic kinases such as Src kinase. In
maligcies, these signaling pathways are often exploited to optimize tumor
growth and metastasis. Thus, they represent attractive targets for cancer
therapy. This review will summarize current knowledge of the small-molecule
multiple-kinase inhibitors in lung cancer therapy. These inhibitors generally
hinder the phosphorylation of several protein kinases of membrane receptors,
such as vascular endothelial growth factor receptors, platelet-derived growth
factor receptors, the human epidermal growth factor receptor family, and
cytoplasmic receptors such as c-Kit, Raf kinase, and FLT3. These inhibitors
include ZD6474, SU11248, AEE 788, sorafenib, vatalanib, and AG-013736. |
Has proteomics been used in the study of Pick's disease? | Yes, proteomics has been used in the study of Pick's disease. | Histamine-N-methyltransferase (HMT) inactivates the neurotransmitter histamine.
Central histaminergic deficits may contribute to the cognitive impairment of
neurodegenerative disorders including Alzheimer's disease (AD) and Down syndrome
(DS). However, there is no evidence for histaminergic deficits in Pick's disease
(PiD). HMT levels were measured in the frontal cortex and cerebellum of brains
of patients with AD, DS, and PiD, and normal aged subjects using proteomics
techniques. In frontal cortex, HMT was significantly decreased in DS, but
significantly increased in PiD compared with controls. HMT levels were
comparable in cerebellum of all groups. Elevated HMT in PiD could lead to
increased histamine degradation that in turn would be in agreement with impaired
cognitive functions of PiD. Decreased HMT in DS would be compatible with
findings of decreased histamine synthesis, thus reflecting a compensation
mechanism to antagonize reduced synthesis by decreased degradation. An increasing body of evidence indicates that oxidative stress and damage play a
role in the pathogenesis of a number of diseases associated with
neurodegeneration, including Down syndrome (DS), Alzheimer's disease (AD) and
Pick's disease (PD). Although oxidative stress is a common element in these
diseases, specific clinico-pathological phenotypes have been described for each
disorder. Development of these phenotypes might be linked, among others, to
differences in antioxidant response. The present study is designed to
investigate expression of peroxiredoxins (Prxs), the newly characterized family
of highly conserved antioxidant enzymes, and other antioxidant enzymes in
frontal cortex and cerebellum of DS, AD and PD patients using the technique of
proteomics. Levels of Prx I, Mn superoxide dismutase (SOD2) and
glutathione-S-transferase omega1 in DS, AD and PD were not significantly
different from that of controls in both brain regions investigated. In contrast,
Prx II was significantly increased (P<0.05) in frontal cortex of DS, AD and PD,
whereas Prx III was decreased in frontal cortex of DS (P<0.01) and PD (P<0.001).
Interestingly, Prx VI displayed a significant increase (P<0.05) only in PD
frontal cortex. The present data indicate that differential regulation of
antioxidant enzymes exist in DS, AD and PD, suggestive of the diversity as well
as distinct functional roles of these proteins. Moreover, while up-regulation of
Prx II appears to provide evidence for the existence of compensatory response in
increased cell loss, up-regulation of Prx VI may be used to discriminate PD from
AD as well as DS. Proteomics technologies have been widely used in the investigation of
neurodegenerative and psychiatric disorders, and in particular in the detection
of differences between healthy individuals and patients suffering from such
diseases. Thus, brain and cerebrospinal fluid (CSF) samples from patients with
Alzheimer's disease, Down syndrome, Pick's disease, Parkinson's disease,
schizophrenia, and other disorders as well as brain and CSF from animals serving
as models of neurological disorders have been analyzed by proteomics. 2-DE
followed by MALDI-TOF-MS has been mainly applied as this proteomics approach
provides the possibility of convenient quantification of protein levels and
detection of post-translational modifications. About 330 unique proteins with
deranged levels and modifications have been detected by proteomics approaches to
be related to neurodegeneration and psychiatric disorders. They are mainly
involved in metabolism pathways, cytoskeleton formation, signal transduction,
guidance, detoxification, transport, and conformational changes. In this
article, we provide a summary of the major contributions of proteomics
technologies in the study of neurodegenerative and psychiatric diseases, in
particular, in the detection of changes in protein levels and modifications
related to these disorders. Pick's disease is a subset of fronto-temporal dementia characterised by severe
atrophy of the temporal and frontal lobes due to marked neuronal loss
accompanied by astrocytic gliosis enriched in glial acidic protein. The
remaining neurones have intracytoplasmic inclusions composed of
hyperphosphorylated tau, called Pick bodies, in addition to hyperphosphorylated
tau in astrocytes and oligodendrocytes. Gel electrophoresis and western blotting
using markers of glycoxidation (advanced glycation end products,
N-carboxyethyl-lysine and N-carboxymethyl-lysine: AGE, CEL, CML, respectively)
and lipoxidation (4-hydroxy-2-nonenal: HNE, and malondialdehyde-lysine: MDAL)
were used in the frontal and occipital cortex in three Pick's disease cases and
three age-matched controls. In Pick's disease, increased AGE, CML, CEL, HNE and
MDAL bands of about 50 kDa were observed in the frontal cortex (but not in the
occipital cortex) in association with increased density of glial acidic protein
bands. Bi-dimensional gel electrophoresis and western blotting also disclosed
increased amounts and numbers of glial acidic protein isoforms in the frontal
cortex in Pick's disease. Moreover, redox proteomics showed glycoxidation, as
revealed with anti-CEL antibodies and lipoxidation using anti-HNE antibodies, of
at least three glial acidic protein isoforms. The present results demonstrate
that glial acidic protein is a target of oxidative damage in the frontal cortex
in Pick's disease. |
Are there any urine biomarkers for bladder cancer diagnosis? | Bladder cancer is any of several types of malignancy arising from the epithelial lining of the urinary bladder. Rarely the bladder is involved by non-epithelial cancers, such as lymphoma or sarcoma. It is a disease in which abnormal cells multiply without control in the bladder.The bladder is a hollow, muscular organ that stores urine; it is located in the pelvis. The most common type of bladder cancer recapitulates the normal histology of the urothelium and is known as transitional cell carcinoma or more properly urothelial cell carcinoma. It is estimated that there are 383,000 cases of bladder cancer worldwide | The natural history of non-muscle invasive bladder cancer is characterized by a
high probability of recurrence and in the case of high-grade tumors, progression
to muscle invasive cancer. This mandates a follow-up strategy designed to
identify recurrences in the bladder early in their evolution in order to
facilitate early intervention and ablation. Urine cytology is considered the
gold standard urine biomarker. Although specificity exceeds 90% to 95%, its
overall sensitivity ranges from 40% to 60% in expert hands and is both tumor
grade and operator dependent. While cytology is an excellent test for detection
of high-grade disease, the sensitivity is particularly weak for the detection of
low grade tumors. This has spawned an entire field of research of in vitro
diagnostic tests and cell-based assays in order to improve the diagnostic
accuracy for detection of incident or recurrent disease. To date, the US Food
and Drug Administration approved dipstick and immunoassays marketed as
point-of-care tests. The point-of-care tests are intended for use as an adjunct
to cystoscopy and cytology, and may have a role in the office evaluation of
hematuria patients. Monoclonal antibody-based tests combined with cytology may
improve the diagnostic accuracy and are superior to cytology alone. A recently
approved cell-based assay, utilizing fluorescent in situ hybridization
technology, may help resolve suspicious cytologies, and provide early and
additional information about the biology of the bladder urothelium beyond that
provided by cytology, a marker of disease relatively late in evolution. Novel
promising markers are in various stages of clinical testing, and a panel of
biomarkers may serve in the future as a feasible alternative to urine cytology
and cystoscopy for the screening, detection, and follow-up of non-muscle
invasive bladder cancer. Bladder cancer has a very high frequency of recurrence and therefore requires
lifelong surveillance, traditionally consisting of serial cystoscopy and
cytology. These tests are both invasive and expensive, with considerable
inter-user and inter-institutional variability. In addition, the sensitivity of
cytology in detecting low-grade tumors is low. Therefore, there has been active
investigation into urinary biomarkers that can either supplement or supplant
these tests. At this point there are only six urine-based tests that are
FDA-approved in bladder cancer surveillance, but a wide variety of other
biomarkers are being studied. In this review, we examine the natural history of
bladder cancer as well as the rationale and performance of an ideal urinary
biomarker. The authors describe the FDA-approved biomarkers such as Bladder
Tumor Antigen, ImmunoCyt, Nuclear Matrix Protein-22, and Fluorescent In Situ
Hybridization, as well as the most promising investigational tests (i.e.,
Urinary bladder cancer test, BLCA-1, BLCA-4, hyaluronic acid, hyaluronidase,
Lewis X antigen, microsatellite analysis, Quanticyt, soluble Fas, Survivin, and
telomerase). The biological foundation, methodologies, and diagnostic
performance of the biomarkers are discussed. The characteristics of the
biomarkers are compared to urine cytology. At this time, urine biomarkers are
utilized in a variety of clinical situations but their role is not well defined.
The goal of identifying an optimal marker that will replace cystoscopy and/or
cytology is still ongoing. OBJECTIVES: To identify a better set of DNA methylation markers to detect
superficial, low grade cancer cell in urine sediment for improving cancer
treatment, morbidity, and mortality.
MATERIALS AND METHODS: Methylation-specific PCR (MSP) assay was used to detect
promoter hypermethylation in 4 genes (E-cadherin, p16, p14, and RASSF1A) to
identify reliable biomarkers for bladder cancer diagnosis in primary tumor DNA
and urine sediment DNA from 57 bladder cancer patients. Urine DNA was compared
with 20 healthy controls.
RESULTS: Fifty-one (90%) tumor DNA and 47 urine DNA (83%) samples from bladder
cancer patients revealed hypermethylation in at least 1 of the 4 analyzed genes,
whereas all urine samples from normal controls were negative. The sensitivity of
MSP assay for detecting E-cadherin, p16, p14 and RASSF1A in tumor cells in
voided urine was 35%, 35%, 33%, and 65%, respectively. Diagnostic sensitivity
was 75% for combining RASSF1A and p14, and 83% for RASSF1A, p14 and E-cadherin.
Urine cytology, however, detect only 13 (28%) cases of cancer or suspicious
cancer. For detecting superficial and invasive bladder tumor, urine cytology
revealed a sensitivity of 23% (6/26) and 35% (7/20), respectively. In contrast,
MSP detected hypermethylation in the urine of 80% (37/46) bladder cancer
patients. Moreover, hypermethylation analysis of E-cadherin, p14 or RASSF1A
genes in urine sediment DNA detected in 85% (22/26) of superficial, 85% (11/13)
of low grade, 75% (15/20) of invasive and 79% (26/33) of high grade bladder
cancers. Importantly, hypermethylation was detected in the urine DNA of 90%
(18/20) superficial tumors with negative or atypia cytology.
CONCLUSIONS: Hypermethylation of E-cadherin, p14 or RASSF1A in urine sediment
DNA is a potential biomarker for detecting superficial, low grade cancer.
Besides, hypermethylation of these 3 genes is a valuable adjunct diagnostic
marker to urine cytology, which can enhance the diagnostic accuracy and
follow-up treatment of bladder cancer patients. PURPOSE: A 11-gene set by methylation-specific PCR in urine sediments for
sensitive/specific detection of bladder cancer has been identified previously.
In this study, we have evaluated 10 DNA methylation biomarkers that have been
reported informative in western countries for bladder cancer diagnosis for a
better set.
MATERIALS AND METHODS: The promoter CpG Islands of the following 10 genes: CDH1,
FANCF, LOXL1, LOXL4, p16INK4, SFRP1, SOX9, TIG1, TIMP3, and XAF1 have been
subjected to methylation-specific PCR analysis in the DNA of 2 bladder cancer
cell lines, 2 normal bladder tissues and urine sediments of 82 bladder cancer
patients, 15 non-cancerous urogenital patients and 5 healthy volunteers.
RESULTS: Both XAF1 and LOXL1 genes were heterozygously methylated in the normal
bladder tissues, showing no cancer state specificity. While the hypermethylated
states were detected in urine sediments of bladder cancer at a frequency not
less than 2.4% (2/82 cases), nine genes were also methylated in the patients of
the non-cancerous urogenital diseases. The methylated SFRP1 was detected in
36.6% (30/82 cases) of bladder cancer and 6.7% (1/15 cases) of non-cancerous
urogenital diseases, showing the bladder cancer specificity.
CONCLUSIONS: Inclusion of the SFRP1 gene into a set of 11 genes has improved the
bladder cancer detection. The insufficiency of predicting disease onset in this
study with the previously recommended targets in western countries suggests a
possible disease disparity between these two populations. Alternatively, the
tissue-specific methylation might be mistaken as the cancer specific in the
studies where no non-cancerous lesion controls were involved. OBJECTIVE: To assess the clinical effectiveness and cost-effectiveness of
photodynamic diagnosis (PDD) compared with white light cystoscopy (WLC), and
urine biomarkers [fluorescence in situ hybridisation (FISH), ImmunoCyt, NMP22]
and cytology for the detection and follow-up of bladder cancer.
DATA SOURCES: Major electronic databases including MEDLINE, MEDLINE In-Process,
EMBASE, BIOSIS, Science Citation Index, Health Management Information Consortium
and the Cochrane Controlled Trials Register were searched until April 2008.
REVIEW METHODS: A systematic review of the literature was carried out according
to standard methods. An economic model was constructed to assess the
cost-effectiveness of alternative diagnostic and follow-up strategies for the
diagnosis and management of patients with bladder cancer.
RESULTS: In total, 27 studies reported PDD test performance. In pooled estimates
[95% confidence interval (CI)] for patient-level analysis, PDD had higher
sensitivity than WLC [92% (80% to 100%) versus 71% (49% to 93%)] but lower
specificity [57% (36% to 79%) versus 72% (47% to 96%)]. Similar results were
found for biopsy-level analysis. The median sensitivities (range) of PDD and WLC
for detecting lower risk, less aggressive tumours were similar for patient-level
detection [92% (20% to 95%) versus 95% (8% to 100%)], but sensitivity was higher
for PDD than for WLC for biopsy-level detection [96% (88% to 100%) versus 88%
(74% to 100%)]. For more aggressive, higher-risk tumours the median sensitivity
of PDD for both patient-level [89% (6% to 100%)] and biopsy-level [99% (54% to
100%)] detection was higher than those of WLC [56% (0% to 100%) and 67% (0% to
100%) respectively]. Four RCTs comparing PDD with WLC reported effectiveness
outcomes. PDD use at transurethral resection of bladder tumour resulted in fewer
residual tumours at check cystoscopy [relative risk, RR, 0.37 (95% CI 0.20 to
0.69)] and longer recurrence-free survival [RR 1.37 (95% CI 1.18 to 1.59)]
compared with WLC. In 71 studies reporting the performance of biomarkers and
cytology in detecting bladder cancer, sensitivity (95% CI) was highest for
ImmunoCyt [84% (77% to 91%)] and lowest for cytology [44% (38% to 51%)], whereas
specificity was highest for cytology [96% (94% to 98%)] and lowest for ImmunoCyt
[75% (68% to 83%)]. In the cost-effectiveness analysis the most effective
strategy in terms of true positive cases (44) and life-years (11.66) [flexible
cystoscopy (CSC) and ImmunoCyt followed by PDD in initial diagnosis and CSC
followed by WLC in follow-up] had an incremental cost per life-year of over
270,000 pounds. The least effective strategy [cytology followed by WLC in
initial diagnosis (average cost over 20 years 1403 pounds, average life
expectancy 11.59)] was most likely to be considered cost-effective when
society's willingness to pay was less than 20,000 pounds per life-year. No
strategy was cost-effective more than 50% of the time, but four of the eight
strategies in the probabilistic sensitivity analysis (three involving a
biomarker or PDD) were each associated with a 20% chance of being considered
cost-effective. In sensitivity analyses the results were most sensitive to the
pretest probability of disease (5% in the base case).
CONCLUSIONS: The advantages of PDD's higher sensitivity in detecting bladder
cancer have to be weighed against the disadvantages of a higher false-positive
rate. Taking into account the assumptions made in the model, strategies
involving biomarkers and/or PDD provide additional benefits at a cost that
society might be willing to pay. Strategies replacing WLC with PDD provide more
life-years but it is unclear whether they are worth the extra cost. PURPOSE OF REVIEW: Reduce the burden of follow-up for patients and healthcare
providers in noninvasive bladder cancer (NIBC). The evolution of intraoperative
tumor detection, imaging modalities, urinary markers, and intravesical
instillation regimens as a possibility to improve tumor eradication, enhance
noninvasive tumor monitoring and thus to reduce costs is reviewed.
RECENT FINDINGS: On the basis of current evidence, the recurrence and
progression of patients with NIBC can significantly be improved by
fluorescence-guided transurethral resection and perioperative chemoinstillation.
Virtual cystoscopic modalities based on computed tomography or magnetic
resoce imaging as well as a combination of urine biomarkers, which improve
the sensitivity of conventional urine cytology, has the potential to reduce
discomfort and pain associated with conventional cystoscopy. Recent
meta-analyses have furthermore demonstrated that risk-adapted instillation
regimens for immediate, induction and maintece therapy using
immuno-instillation and chemoinstillation therapy improve significantly
recurrence-free and progression-free survival rates.
SUMMARY: Emerging technologies in the field of tumor visualization in
combination with urinary markers and effective instillation regimens can
significantly reduce the risk of recurrence and progression in the long-term
whilst providing less patient discomfort and simplifying the follow-up in
patients of NIBC. Altered microRNA (miRNA) expression may occur early in bladder cancer and may
play a role in carcinogenesis and tumor behavior. We evaluated whether
alterations in miRNA expression could improve disease stratification and outcome
prognosis in bladder tumors and noninvasive diagnosis in urinary samples.
miR-143, miR-222, and miR-452 expression levels were analyzed by quantitative
RT-PCR (RT-qPCR) in paired urinary and matching tumors and in two independent
prospective series of tumors and urinary specimens. Differential expression of
miR-143, miR-222, and miR-452 in urine were verified by in situ hybridization in
matching tumors. Tumor miRNA expression by RT-qPCR correlated with tumor grade,
size, and presence of carcinoma in situ for miR-222, recurrence (miR-222 and
miR-143), progression (miR-222 and miR-143), disease-specific survival
(miR-222), and overall survival (miR-222). Protein expression patterns of
potential miRNA targets, including vascular endothelial growth factor, BCL2,
v-erb-b2 erythroblastic leukemia viral oncogene (ERBB) homolog 3, and ERBB4,
were evaluated by IHC in tissue arrays containing tumors for which miRNAs were
assessed by RT-qPCR. Target expression correlated with expression of their
predicted regulatory miRNAs, recurrence (ERBB3), progression (ERBB4),
disease-specific survival (ERBB3 and ERBB4), and overall survival (ERBB3 and
ERBB4). Furthermore, RT-qPCR of miR-452 (area under the curve, 0.848) and
miR-222 (area under the curve, 0.718) in urine provided high accuracies for
bladder cancer diagnosis. Thus, bladder tumors were characterized by changes in
miRNA expression that could aid in tumor stratification and clinical outcome
prognosis, and miRNAs were detected in urinary specimens for noninvasive
diagnosis. BACKGROUND: Current urine-based assays for bladder cancer (BCa) diagnosis lack
accuracy, so the search for improved biomarkers continues. Through genomic and
proteomic profiling of urine, we have identified a panel of biomarkers
associated with the presence of BCa. In this study, we evaluated the utility of
three of these biomarkers, interleukin 8 (IL-8), Matrix metallopeptidase 9
(MMP-9) and Syndecan in the diagnosis of BCa through urinalysis.
METHODS: Voided urines from 127 subjects, cancer subjects (n = 64), non-cancer
subjects (n = 63) were analyzed. The protein concentrations of IL-8, MMP-9, and
Syndecan were assessed by enzyme-linked immunosorbent assay (ELISA). Data were
also compared to a commercial ELISA-based BCa detection assay (BTA-Trak©) and
urinary cytology. We used the area under the curve of a receiver operating
characteristic (AUROC) to compare the performance of each biomarker.
RESULTS: Urinary protein concentrations of IL-8, MMP-9 and BTA were
significantly elevated in BCa subjects. Of the experimental markers compared to
BTA-Trak©, IL-8 was the most prominent marker (AUC; 0.79; 95% confidence
interval [CI], 0.72-0.86). Multivariate regression analysis revealed that only
IL-8 (OR; 1.51; 95% CI, 1.16-1.97, p = 0.002) was an independent factor for the
detection of BCa.
CONCLUSIONS: These results suggest that the measurement of IL-8 in voided
urinary samples may have utility for urine-based detection of BCa. These
findings need to be confirmed in a larger, prospective cohort. Although, increased oxidative stress and hypomethylation of long interspersed
nuclear element-1 (LINE-1) associate with bladder cancer (BCa) development, the
relationship between these alterations is unknown. We evaluated the oxidative
stress and hypomethylation of the LINE-1 in 61 BCa patients and 45 normal
individuals. To measure the methylation levels and to differentiate the LINE-1
loci into hypermethylated, partially methylated and hypomethylated, peripheral
blood cells, urinary exfoliated cells and cancerous tissues were evaluated by
combined bisulfite restriction analysis PCR. The urinary total antioxidant
status (TAS) and plasma protein carbonyl content were determined. The LINE-1
methylation levels and patterns, especially hypomethylated loci, in the blood
and urine cells of the BCa patients were different from the levels and patterns
in the healthy controls. The urinary TAS was decreased, whereas the plasma
protein carbonyl content was increased in the BCa patients relative to the
controls. A positive correlation between the methylation of LINE-1 in the
blood-derived DNA and urinary TAS was found in both the BCa and control groups.
The urinary hypomethylated LINE-1 loci and the plasma protein carbonyl content
provided the best diagnostic potential for BCa prediction. Based on
post-diagnostic samples, the combination test improved the diagnostic power to a
sensitivity of 96% and a specificity of 96%. In conclusion, decreased LINE-1
methylation is associated with increased oxidative stress both in healthy and
BCa subjects across the various tissue types, implying a dose-response
association. Increases in the LINE-1 hypomethylation levels and the number of
hypomethylated loci in both the blood- and urine-derived cells and increase in
the oxidative stress were found in the BCa patients. The combination test of the
urinary hypomethylated LINE-1 loci and the plasma protein carbonyl content may
be useful for BCa screening and monitoring of treatment. Bladder cancer has increased incidence during last decades. For those patients
with nonmuscle involved tumors, noninvasive diagnosis test and surveillance
methods must be designed to avoid current cystoscopies that nowadays are done
regularly in a lot of patients. Novel urine biomarkers have been developed
during last years. Telomerase is important in cancer biology, improving the
division capacity of cancer cells. Even urinary telomerase could be a
potentially useful urinary tumor marker; its use for diagnosis of asymptomatic
and symptomatic patients or its impact during surveillance is still unknown.
Moreover, there will need to be uniformity and standardization in the assays
before it can become useful in clinical practice. It does not seem to exist a
real difference between the most classical assays for the detection of urine
telomerase (TRAP and hTERT). However, the new detection methods with modified
TeloTAGGG telomerase or with gold oparticles must also be taken into
consideration for the correct development of this diagnosis method. Maybe the
target population would be the high-risk groups within screening programs. To
date there is no enough evidence to use it alone and to eliminate cystoscopies
from the diagnosis and surveillance of these patients. The combination with
cytology or FISH is still preferred. Accurate urinary assays for bladder cancer (BCa) detection would benefit both
patients and healthcare systems. Through genomic and proteomic profiling of
urine components, we have previously identified a panel of biomarkers that can
outperform current urine-based biomarkers for the non-invasive detection of BCa.
Herein, we report the diagnostic utility of various multivariate combinations of
these biomarkers. We performed a case-controlled validation study in which
voided urines from 127 patients (64 tumor bearing subjects) were analyzed. The
urinary concentrations of 14 biomarkers (IL-8, MMP-9, MMP-10, SDC1, CCL18,
PAI-1, CD44, VEGF, ANG, CA9, A1AT, OPN, PTX3, and APOE) were assessed by
enzyme-linked immunosorbent assay (ELISA). Diagnostic performance of each
biomarker and multivariate models were compared using receiver operating
characteristic curves and the chi-square test. An 8-biomarker model achieved the
most accurate BCa diagnosis (sensitivity 92%, specificity 97%), but a
combination of 3 of the 8 biomarkers (IL-8, VEGF, and APOE) was also highly
accurate (sensitivity 90%, specificity 97%). For comparison, the commercial
BTA-Trak ELISA test achieved a sensitivity of 79% and a specificity of 83%, and
voided urine cytology detected only 33% of BCa cases in the same cohort. These
data show that a multivariate urine-based assay can markedly improve the
accuracy of non-invasive BCa detection. Further validation studies are under way
to investigate the clinical utility of this panel of biomarkers for BCa
diagnosis and disease monitoring. PURPOSE: Accurate urine assays for bladder cancer detection would benefit
patients and health care systems. Through extensive genomic and proteomic
profiling of urine components we previously identified a panel of 8 biomarkers
that can facilitate the detection of bladder cancer in voided urine samples. In
this study we confirmed this diagnostic molecular signature in a diverse
multicenter cohort.
MATERIALS AND METHODS: We performed a case-control, phase II study in which we
analyzed voided urine from 102 subjects with bladder cancer and 206 with varying
urological disorders. The urinary concentration of 8 biomarkers (IL-8, MMP-9 and
10, PAI-1, VEGF, ANG, CA9 and APOE) was assessed by enzyme-linked immunosorbent
assay. Diagnostic performance of the panel of tested biomarkers was evaluated
using ROCs and descriptive statistical values, eg sensitivity and specificity.
RESULTS: Seven of the 8 urine biomarkers were increased in subjects with bladder
cancer relative to those without bladder cancer. The 7 biomarkers were assessed
in a new model, which had an AUROC of 0.88 (95% CI 0.84-0.93), and 74%
sensitivity and 90% specificity. In contrast, the sensitivity of voided urine
cytology and the UroVysion® cytogenetic test in this cohort was 39% and 54%,
respectively. Study limitations include analysis performed on banked urine
samples and the lack of voided urine cytology and cytogenetic test data on
controls.
CONCLUSIONS: The study provides further evidence that the reported panel of
diagnostic biomarkers can reliably achieve the noninvasive detection of bladder
cancer with higher sensitivity than currently available urine based assays. Bladder cancer is a common cancer in the Western world. The current
prognosticators such as tumor grade, stage, size, and multifocality do not
accurately reflect the clinical outcome. It is of clinical interest to identify
biomarkers that could improve diagnostic and/or prognostic predictions. The
objectives of this study were to identify deregulated miRNAs in bladder cancer
samples and evaluate their potential as diagnostic and prognostic biomarkers. We
screened 723 miRNAs by microarray and selected a subset of 15 distinctively
deregulated miRNAs for further validation by real-time quantitative RT-(q)PCR.
Seven miRNAs (miR-20a, miR-106b, miR-130b, miR-141, miR-200a, miR-200a*, and
miR-205) were found to be up-regulated and eight miRNAs (miR-100, miR-125b,
miR-130a, miR-139-5p, miR-145*, miR-199a-3p, miR-214, and miR-222) were found to
be down-regulated in maligt bladder tissue samples compared to healthy
tissue. Four miRNAs that have already been described in the literature (miR-141,
miR-199a-3p, miR-205, and miR-214) were significantly differentially expressed
between nonmuscle-invasive and muscle-invasive bladder cancer. Furthermore,
real-time RT-qPCR of all miRNAs provided high overall correct classification
(>75%) of bladder cancer diagnosis. Two miRNAs (miR-141 and miR-205) were
associated with overall survival time. The verification of tumor-specific miRNA
expression profile, together with the observed association of miR-141 and
miR-205 expression with overall survival, underline the potential of miRNAs to
function as diagnostic and/or prognostic markers of bladder cancer. The incidence and rate of recurrence of bladder cancer is high, particularly in
developed countries, however current methods for diagnosis are limited to
detecting high-grade tumours using often invasive methods. A panel of biomarkers
to characterise tumours of different grades that could also distinguish between
patients exhibiting the disease with first incidence or recurrence could be
useful for bladder cancer diagnostics. In this study, potential metabolic
biomarkers have been discovered through mass spectrometry based metabolomics of
urine. Pre-treatment urine samples were collected from 48 patients diagnosed of
urothelial bladder cancer. Patients were followed-up through the hospital
pathological charts to identify whether and when the disease recurred or
progressed. Subsequently, they were classified according to whether or not they
suffered a tumour recurrence (recurrent or stable) as well as their risk group
according to tumour grade and stage. Identified metabolites have been analysed
in terms of disease characteristics (tumour stage and recurrence) and have
provided an insight into bladder cancer progression. Using both liquid
chromatography and capillary electrophoresis-mass spectrometry, a total of 27
metabolite features were highlighted as significantly different between patient
groups. Some, for example histidine, phenylalanine, tyrosine and tryptophan have
been previously linked with bladder cancer, however until now their connection
with bladder cancer progression has not been previously reported. The candidate
biomarkers revealed in this study could be useful in the clinic for diagnosis of
bladder cancer and, through characterising the stage of the disease, could also
be useful in prognostics. OBJECTIVE: Noninvasive biomarkers are used routinely in the clinical management
of several cancers but bladder cancer detection and surveillance remains
dependent on invasive procedures such as cystoscopy. No validated biomarker
currently exists in routine clinical practice other than cytology. Gene-based
testing has shown great promise for biomarker profiling and this review
addresses the current state of biomarker research in bladder cancer.
MATERIALS AND METHODS: A comprehensive review of all published literature on
urinary biomarkers from 1970 - 2012 was conducted in PubMed. Keywords used alone
or in combination were bladder cancer, diagnosis, surveillance, urinary
biomarker, molecular biomarkers, methylation, gene expression, single nucleotide
polymorphism and microRNA. The cited references of the manuscripts included in
the review were also screened.
RESULTS: We have reviewed various strategies currently used for gene-based
biomarker profiling of bladder cancer. We have comprehensively summarized the
performance of several biomarkers in the diagnosis and surveillance of bladder
cancer. Finally we have identified biomarkers that have shown potential and now
deserve the opportunity to be validated in the clinical setting.
CONCLUSION: Several gene-based urinary biomarkers have demonstrated promise in
initial studies, which now need to be rigorously validated in the clinical
setting for them to be translated into clinically useful tests in diagnosis,
surveillance or risk-stratification of bladder cancer. OBJECTIVE: To develop a gold oparticle (AuNP) assay for direct detection of
unamplified HURP RNA in urine.
DESIGN AND METHODS: HURP RNA was extracted from urine samples (50 bladder
carcinoma patients, 25 benign bladder lesions, and 25 controls) and further
purified using magnetic oparticles (MNPs), functionalized with HURP
RNA-specific oligonucleotides, and then detected by RT-PCR or gold
oparticles.
RESULTS: The developed HURP RNA AuNP assay has a sensitivity and a specificity
of 88.5% and 94%, respectively, and a detection limit of 2.4 nmol/L. The
concordance between the HURP AuNP assay with RT-PCR after RNA purification using
functionalized MNPs was 97%.
CONCLUSIONS: The developed colorimetric HURP RNA AuNP assay is sensitive,
simple, and can aid noninvasive diagnosis of bladder cancer. A biomarker is a characteristic that is objectively measured and evaluated as an
indicator of normal biologic processes, pathogenic processes, or pharmacologic
responses to a therapeutic intervention. In cancer, a biomarker refers to a
substance or process that is indicative of the presence of cancer in the body. A
biomarker might be either a molecule secreted by a tumor or it can be a specific
response of the body to the presence of cancer. Genetic, epigenetic, proteomic,
glycomic, and imaging biomarkers can be used for cancer diagnosis, prognosis and
epidemiology. These markers can be assayed in non-invasively collected
biofluids. However, few cancer biomarkers are highly sensitive and specific for
cancer detection at the present time. Consequently, biomarkers are not yet ready
for routine use due to challenges in their clinical validation for early disease
detection, diagnosis and monitoring to improve long-term survival of patients. Histopathological grading of papillary urothelial tumors (PUTs) of the urinary
bladder is subjective and poorly reproducible. We investigated the relationship
between the expression of frequently deregulated microRNAs (miRNAs) as well as
their target genes (ZEB1/ZEB2) and bladder cancer histopathological grade in an
attempt to find a miRNA that might allow more reliable grading of PUTs. We
measured the expression levels of four miRNAs (miR-145, miR-205, miR-125b, and
miR-200c) in 120 formalin-fixed, paraffin-embedded bladder tumor tissue samples
using real-time PCR assays. ZEB1 and ZEB2 expression was assessed in the same
bladder tissues by immunohistochemistry. MiR-205 distinguished low-grade
papillary urothelial carcinoma (LG) from high-grade papillary urothelial
carcinoma (HG), and miR-145 distinguished HG from infiltrating carcinoma (CA)
with an area under the receiver operator characteristic curve (AUC) of 0.992 and
0.997, respectively (sensitivity/specificity of 95.8/96.7 % and 100/91.7 %,
respectively; p < 0.05). The expression level of miR-125b was significantly
lower in LG than in PUNLMP, with an AUC value of 0.870 (93.3 % sensitivity and
84.2 % specificity; p < 0.05). ZEB1 immunoreactivity was more frequently
detected in HG than in LG (57 % vs 13 %, p < 0.01) and in HG than in CA (57 % vs
17 %, p < 0.01). ZEB2 immunoreactivity was more frequent in CA than in HG (83 %
vs 54 %, p < 0.05). ZEB1/ZEB2 and miRNAs expression seems to reliably
distinguish between different grades of PUTs of the urinary bladder. They might
well serve as useful complementary diagnostic biomarkers for grading of
papillary urothelial tumors. INTRODUCTION: Bladder cancer (BC) is a serious medical problem. The high rate of
recurrence and progression demands the development of new methods, such as
genetic markers, which allow diagnosis and patient follow-up.
OBJECTIVES: The aim of this study was to compare expression of HIF-1, GLUT1,
endoglin, and BRIC5 in patients without and those with BC. The second group was
divided into sub-groups: those without a history of PDD (photodynamic diagnosis)
in the diagnostic process and those after PDD.
METHODS: Patients with BC were diagnosed using the PDD method using
hexaminolevulinate (Hexvix(®)). The expressions of HIF-1, GLUT1, endoglin, and
BRIC5 genes were established in urine specimens by real-time quantitative
polymerase chain reaction (PCR).
RESULTS: The expressions of all tested genes were higher in the group of
patients with BC than in the group without BC. In the group after PDD, a
statistically significant overexpression of HIF-1 was observed. In this group,
changes were not observed in cases of the other three tested genes.
CONCLUSIONS: The differences between the group with PDD and the group without it
can be connected with the direct influence of PDD on maligt tissue, which can
cause overexpression of HIF-1 only. This is, however, only a hypothesis and
needs further study. |
List types of avoided words in bacterial genomes | Short palindromic sequences (4, 5 and 6 bp palindromes) are avoided at a statistically significant level in the genomes of several bacteria, including the completely sequenced Haemophilus influenzae and Synechocystis sp. genomes and in the complete genome of the archaeon Methanococcus jannaschii. Palindromes corresponding to sites for restriction enzymes from other species are also avoided, albeit less significantly, suggesting that in the course of evolution bacterial DNA has been exposed to a wide spectrum of restriction enzymes, probably as the result of lateral transfer mediated by mobile genetic elements, such as plasmids and prophages. Palindromic words appear to accumulate in DNA once it becomes isolated from restriction-modification systems, as demonstrated by the case of organellar genomes. | Recognition sites for type II restriction and modification enzymes in genomes of
several bacteria are recognized as semi-palindromic motifs and are avoided at a
significant degree. The key idea of contrast word analysis with respect to RMS
recognition sites, is that under-represented words are likely to be selected
against. Starting from over- or underrepresented words corresponding to RMS
recognition sites in specific clades, the specificity of unknown R-M systems can
be highlighted. Among the known restriction enzymes, that are described in the
REBASE database of restriction and modification systems, many of their
recognition sites are still uncharacterized. Eventually, this motivates studies
aimed at assessing horizontal transferring events of RMS in micro-organisms
through the analysis of word usage biases in well-determined genomic regions. A
probabilistic model is built on a first-order Markovian chain. Statistics on the
k-neighborhood of a word is carried out to assess the biological significance of
a genomic motif. Efficient word counting procedures have been implemented and
statistics are used for the assessment of the significance of individual words
in large sequences. On the basis of the set of most avoided words, and in
accordance to the IUPAC coding standards, suggestions are made regarding
potential recognition sequences. In certain cases, a comparison of avoided
palindromic words in taxonomically related bacteria shows a pattern of
relatedness of their R-M systems. For strengthening this analysis, the primary
protein structure of all type II R-M systems known in REBASE have been blasted
against the nr-GENBANK database. The combination of these analyses has revealed
some interesting examples of possible horizontal transfer events of R-M systems. |
Which gene(s) should be genotyped in order to prescribe the drug Cetuximab (anti-EGFR)? | KRAS mutation has been unambiguously identified as a marker of resistance to cetuximab-based treatment in metastatic colorectal cancer (mCRC) patients.
Other genes are such as EGFR, BRAF and T53 have also been suggested to be genotyped in order to evaluate the drug responsivness. | Colorectal cancer (CRC) is the second most common cancer in Germany; there are
more than 70,000 new cases annually. It is most commonly a disease of the
elderly, and its relative and absolute frequency has risen during the last
decades. CRC remains a major clinical and health economy challenge. Progress has
been made in patient management and CRC treatment. Screening colonoscopy was
introduced in Germany in 2002, and five new therapeutic agents have been
approved since 2001, i.e. capecitabine, oxaliplatin, cetuximab, bevacizumab and
panitumumab; guidelines have been published, and 48 interdisciplinary CRC
centres have been certified in Germany in compliance with DIN EN ISO 9001:2000.
Despite these advancements, targeted treatment of CRC is still in its infancy.
Until 2007, no predictive biomarkers were used to tailor the adjuvant or
palliative chemotherapy of CRC. KRAS genotyping was recently introduced as
predictive biomarker, since only tumors carrying a wildtype were found to
respond to treatment with panitumumab. Among the tumors with KRAS wildtype, only
40-53% (equivalent to 20-30% of all CRC patients) will benefit from treatment,
and the remainder are still enrolled for "non-targeted" treatment. Thus there is
still a great need for predictive biomarkers that are able to tailor patient
treatment at different stages of the disease. INTRODUCTION: Irinotecan has an important place in the treatment of metastatic
colorectal cancer. It was initially administered as monotherapy, but is now
generally used in combination with 5-fluorouracil or targeted therapies
(cetuximab or bevacizumab), with various doses.
METHODS: We here review the main studies assessing irinotecan doses escalation,
and discuss the potent advantages of this escalation.
RESULTS: Several studies have demonstrated a dose-intensity relationship for
irinotecan, and high doses (up to 600 mg/m2 as monotherapy, 260 mg/m2 in
combination therapy) have been used with satisfactory safety and higher
objective response rates. It is possible that, in practice, some patients
receive insufficient doses of irinotecan. Dose escalation could be considered in
carefully selected patients: young patients with a good performance status and
normal liver function. This approach could be useful in patients with liver
metastases, which may become resectable in the case of a major tumour response.
It is wise to perform UGT1A1 genotyping prior to dose escalation to detect
patients at high risk of toxicity (genotype 7/7). The role of another laboratory
parameter, which needs to be evaluated is the KRAS status of the tumour. A KRAS
mutation confers resistance to cetuximab, which reduces treatment options,
especially in first-line. However, in the CRYSTAL trial comparing FOLFIRI to
FOLFIRI-cetuximab as first-line therapy, the presence of a KRAS mutation did not
appear to influence the efficacy of FOLFIRI. The value of irinotecan dose
escalation needs to be determined in this setting.
CONCLUSION: Irinotecan dose escalation is potentially of interest in highly
selected patients, but this concept is only based on phase I or II trials and
must be validated by a randomized trial. Its value regarding other regimens such
as FOLFIRINOX or combinations with targeted therapies also needs to be
determined. BACKGROUND: Following the discovery that mutant KRAS is associated with
resistance to anti-epidermal growth factor receptor (EGFR) antibodies, the
tumours of patients with metastatic colorectal cancer are now profiled for seven
KRAS mutations before receiving cetuximab or panitumumab. However, most patients
with KRAS wild-type tumours still do not respond. We studied the effect of other
downstream mutations on the efficacy of cetuximab in, to our knowledge, the
largest cohort to date of patients with chemotherapy-refractory metastatic
colorectal cancer treated with cetuximab plus chemotherapy in the pre-KRAS
selection era.
METHODS: 1022 tumour DNA samples (73 from fresh-frozen and 949 from
formalin-fixed, paraffin-embedded tissue) from patients treated with cetuximab
between 2001 and 2008 were gathered from 11 centres in seven European countries.
773 primary tumour samples had sufficient quality DNA and were included in
mutation frequency analyses; mass spectrometry genotyping of tumour samples for
KRAS, BRAF, NRAS, and PIK3CA was done centrally. We analysed objective response,
progression-free survival (PFS), and overall survival in molecularly defined
subgroups of the 649 chemotherapy-refractory patients treated with cetuximab
plus chemotherapy.
FINDINGS: 40.0% (299/747) of the tumours harboured a KRAS mutation, 14.5%
(108/743) harboured a PIK3CA mutation (of which 68.5% [74/108] were located in
exon 9 and 20.4% [22/108] in exon 20), 4.7% (36/761) harboured a BRAF mutation,
and 2.6% (17/644) harboured an NRAS mutation. KRAS mutants did not derive
benefit compared with wild types, with a response rate of 6.7% (17/253) versus
35.8% (126/352; odds ratio [OR] 0.13, 95% CI 0.07-0.22; p<0.0001), a median PFS
of 12 weeks versus 24 weeks (hazard ratio [HR] 1.98, 1.66-2.36; p<0.0001), and a
median overall survival of 32 weeks versus 50 weeks (1.75, 1.47-2.09; p<0.0001).
In KRAS wild types, carriers of BRAF and NRAS mutations had a significantly
lower response rate than did BRAF and NRAS wild types, with a response rate of
8.3% (2/24) in carriers of BRAF mutations versus 38.0% in BRAF wild types
(124/326; OR 0.15, 95% CI 0.02-0.51; p=0.0012); and 7.7% (1/13) in carriers of
NRAS mutations versus 38.1% in NRAS wild types (110/289; OR 0.14, 0.007-0.70;
p=0.013). PIK3CA exon 9 mutations had no effect, whereas exon 20 mutations were
associated with a worse outcome compared with wild types, with a response rate
of 0.0% (0/9) versus 36.8% (121/329; OR 0.00, 0.00-0.89; p=0.029), a median PFS
of 11.5 weeks versus 24 weeks (HR 2.52, 1.33-4.78; p=0.013), and a median
overall survival of 34 weeks versus 51 weeks (3.29, 1.60-6.74; p=0.0057).
Multivariate analysis and conditional inference trees confirmed that, if KRAS is
not mutated, assessing BRAF, NRAS, and PIK3CA exon 20 mutations (in that order)
gives additional information about outcome. Objective response rates in our
series were 24.4% in the unselected population, 36.3% in the KRAS wild-type
selected population, and 41.2% in the KRAS, BRAF, NRAS, and PIK3CA exon 20
wild-type population.
INTERPRETATION: While confirming the negative effect of KRAS mutations on
outcome after cetuximab, we show that BRAF, NRAS, and PIK3CA exon 20 mutations
are significantly associated with a low response rate. Objective response rates
could be improved by additional genotyping of BRAF, NRAS, and PIK3CA exon 20
mutations in a KRAS wild-type population.
FUNDING: Belgian Federation against Cancer (Stichting tegen Kanker). Colorectal cancer (CCR), which is one of the most common causes of cancer, has
benefited from the major advances in the understanding of the intracellular
signaling pathways implicated in the initiation, growing and local and
metastasis dissemination of tumor, which have occurred during the 20 past years.
The pharmacogenomics approach, especially the determination of the genetic
polymorphisms, tries to find prognosis and predictive biomarkers permitting to
identify patients who could benefit from a particular treatment or those
exhibiting higher risks of toxicity. Among the numerous biomarkers, which have
been studied, few are currently in use in clinical practice. The phenotyping of
DPD and UGT1A1 activities, and to a lesser extent, its genotyping, appears as
the most useful tool in terms of prediction of toxicities induced by two major
drugs: 5-FU and irinotecan. For oxaliplatin, the determination of the
polymorphisms of reparases and detoxification systems such as GSTpi seems
interesting, but its exact place should be more defined. It is in the field of
targeted therapies that the pharmacogenomics approach seems to be the more
relevant. KRAS mutation is a dramatic example of single nucleotide polymorphism,
which is able to identify a priori patients that could receive or not an
anti-EGFR monoclonal antibody such as cetuximab or panitumumab. It is obvious
that pre-clinical identification of molecular biomarkers predictive of the
sensitivity of the drug targets, which subsequently implicate the selection of
patients and the rational evaluation of responses, will be the cornerstone of
any clinical trials concerning targeted therapies. Besides the determination of
drug target polymorphisms, it is also important to consider those related to the
distribution and metabolism. In this area, the determination of enzymatic
activities should recover its place besides the genomic profiling. Numerous clinical studies have shown that anti-EGFR therapies are effective only
in a subset of patients with colorectal cancer. Even though mutations in the
KRAS gene have been confirmed as negative predictors of the response to
EGFR-targeted therapies, not all KRAS wild-type (wt-KRAS) patients will respond
to treatment. Recent studies have demonstrated that additionally wild-type BRAF
(wt-BRAF) genotype is required for response to panitumumab or cetuximab,
suggesting that BRAF genotype criteria should be used together with KRAS
genotype for selecting the patients who are about to benefit from the anti-EGFR
therapy. In this study, 239 samples obtained from 215 patients with metastatic
colorectal cancer were tested for the presence of the seven most common
mutations in the KRAS gene and the V600E mutation in the BRAF gene. Among the
tested patients, 53.8% of patients had wt-KRAS genotype and 46.2% were KRAS
mutants. Around five percent (5.1%) of the tested patients bore the V600E
mutation in BRAF gene. All the patients showing to have the V600E mutation in
BRAF were wt-KRAS. The concordance of KRAS and BRAF mutational status between
primary and metastatic tumor tissue samples was 100%. We have shown that the
proportions of mutated and non-mutated KRAS in Slovene patients, as well as the
proportion of V600E mutations in BRAF is similar to genotyping results reported
by other authors. The tested seven KRAS mutations on codons 12 and 13 were
mutually exclusive with the V600E mutation in the BRAF gene. Summing up the
results about the KRAS and the BRAF mutation carriers from our study, the
portion of potentially non-responsive patients for the anti-EGFR treatment is
51.3%. BACKGROUND: To test whether intratumoral gene expression levels and germline
polymorphisms predict clinical outcome in metastatic colorectal cancer (mCRC)
patients treated with cetuximab and bevacizumab plus irinotecan (CBI) vs.
cetuximab and bevacizumab (CB)(BOND2).
PATIENTS AND METHODS: Genomic DNA was extracted for genotyping from 65 patients
(31: CBI arm and 34: CB arm). Thirty five patients had tissue samples available
for the gene expression assay (18: CBI arm and 17: CB arm).
RESULTS: High intratumoral gene expression levels of EGFR, VEGFR2 and NRP1 were
associated with longer overall survival (OS) in patients receiving combined
monoclonal antibodies with or without irinotecan. FCGR3A V158F, CyclinD1 A870G
and EGFR R497K polymorphisms are associated with clinical outcome in patients
received combined cetuximab and bevacizumab.
CONCLUSIONS: Intratumoral gene expression levels of EGFR, VEGFR2 and NRP as well
as polymorphisms in FCGR3A, CyclinD1 and EGFR could predict clinical outcome in
mCRC patients enrolled in BOND2, independent of KRAS mutation status. BACKGROUND: Cetuximab has shown significant clinical activity in metastatic
colon cancer. However, cetuximab-containing neoadjuvant chemoradiation has not
been shown to improve tumor response in locally advanced rectal cancer patients
in recent phase I/II trials. We evaluated functional germline polymorphisms of
genes involved in epidermal growth factor receptor pathway, angiogenesis,
antibody-dependent cell-mediated cytotoxicity, DNA repair, and drug metabolism,
for their potential role as molecular predictors for clinical outcome in locally
advanced rectal cancer patients treated with preoperative cetuximab-based
chemoradiation.
METHODS: 130 patients (74 men and 56 women) with locally advanced rectal cancer
(4 with stage II, 109 with stage III, and 15 with stage IV, 2 unknown) who were
enrolled in phase I/II clinical trials treated with cetuximab-based
chemoradiation in European cancer centers were included. Genomic DNA was
extracted from formalin-fixed paraffin-embedded tumor samples and genotyping was
done by using PCR-RFLP assays. Fisher's exact test was used to examine
associations between polymorphisms and complete pathologic response (pCR) that
was determined by a modified Dworak classification system (grade III vs. grade
IV: complete response).
RESULTS: Patients with the epidermal growth factor (EGF) 61 G/G genotype had pCR
of 45% (5/11), compared with 21% (11/53) in patients heterozygous, and 2% (1/54)
in patients homozygous for the A/A allele (P < 0.001). In addition, this
association between EGF 61 G allele and pCR remained significant (P = 0.019) in
the 59 patients with wild-type KRAS.
CONCLUSION: This study suggested EGF A+61G polymorphism to be a predictive
marker for pCR, independent of KRAS mutation status, to cetuximab-based
neoadjuvant chemoradiation of patients with locally advanced rectal cancer. KRAS mutation has been unambiguously identified as a marker of resistance to
cetuximab-based treatment in metastatic colorectal cancer (mCRC) patients.
However, most studies of KRAS mutation analysis have been performed using
homogenously archived CRC specimens, and studies that compare freshly frozen
specimens and formalin-fixed paraffin-embedded (FFPE) specimens of CRC are
lacking. The aim of the present study was to evaluate the impact of tissue
preservation on the determination of KRAS mutational status. A series of 131
mCRC fresh-frozen tissues were first analyzed using both high-resolution melting
(HRM) and direct sequencing. KRAS mutations were found in 47/131 (35.8%) using
both approaches. Out of the 47 samples that were positive for KRAS mutations, 33
had available matched FFPE specimens. Using HRM, 2/33 (6%) demonstrated
suboptimal template amplification, and 2/33 (6%) expressed an erroneous
wild-type KRAS profile. Using direct sequencing, 6/33 (18.1%) displayed a
wild-type KRAS status, and 3/33 (9.1%) showed discordant mutations. Finally, the
detection of KRAS mutations was lower among the FFPE samples compared with the
freshly frozen samples, demonstrating that tissue processing clearly impacts the
accuracy of KRAS genotyping. AIM: Associations between polymorphisms of the epidermal growth factor receptor
(EGFR) and overall survival in patients with advanced carcinoma of the head and
neck (HNSCC) receiving cetuximab based palliative treatment, were evaluated.
MATERIALS AND METHODS: HNSCC patients (n=48) received cetuximab +/-
chemotherapy. Samples for DNA extraction and clinical data were collected
prospectively. Genotyping of four EGF(R) polymorphisms was performed using
PCR-based restriction fragment length polymorphism (RFLP).
RESULTS: The median overall survival was 10.6 months. The EGFR-R497K
polymorphism was significantly associated with overall survival. The presence of
at least one K-allele was associated with shorter overall survival. The median
survival in these patients was 6.7 months compared to 13.3 months in the
patients homozygous for the wild type allele EGFR-497R (p=0.009). Addition of
chemotherapy to cetuximab, age and EGFR-R497K polymorphism were independent
predictors of overall survival. Multivariate analysis revealed a hazard ratio
(HR) for patients with at least one EGFR-497K allele of 3.03 when compared with
EGFR-497R homozygous patients (p=0.045).
CONCLUSION: The EGFR-R497K polymorphism is a potential predictor for overall
survival in HNSCC patients treated with cetuximab based therapy in the
palliative setting. KRAS status is now a mandatory prerequisite in order to treat metastatic
colorectal patients with anti-Epidermal Growth Factor Receptor (EGFR)
antibodies, such as cetuximab or panitumumab. KRAS mutations are unambiguously
linked to a lack of response to these targeted therapies. Because of the major
clinical impact of KRAS status, an observational study has been designed in
France, focusing on the ability to perform KRAS testing between october 2008 and
october 2009. The study was retro-prospective, national, multicentric,
descriptive and non interventional, concerning public and private institutions
and KRAS non mutated patients treated with panitumumab. The primary objective of
this study was to evaluate delays between the genotyping KRAS request and the
result. Secondary objectives were: type of genotyping requests
(systematic/prospective or specific/retrospective), prevalence of the different
genotyping techniques, delays between the genotyping KRAS request and therapy
with panitumumab. Overall, 329 patients from 66 centres have been included.
About half of them belonged to private institutions. The results were obtained
with a mean delay of 33.4 ± 39.8 days (CI 95%: [28.8; 37.9] days; median: 24
days). Most of KRAS genotyping tests were performed on specific requests
(65.3%), from a primary tumor (80.4%) and from a surgical specimen (73.9%). The
more frequently used techniques for KRAS genotyping were: real time PCR (36.2%),
sequencing (24.8%) and pyrosequencing (13.2%). This study emphasizes the
functionality of cancer molecular genetic platforms dedicated to KRAS
genotyping, which allow the use of molecular predictive biomarkers by different
medical institutions. This study also underlines the broad spectrum of
genotyping techniques (no consensus). The delays of response are still longer
than expected but might be improved by optimizing the procedures. BACKGROUND: KRAS, BRAF and PIK3CA mutations are frequently observed in
colorectal cancer (CRC). In particular, KRAS mutations are strong predictors for
clinical outcomes of EGFR-targeted treatments such as cetuximab and panitumumab
in metastatic colorectal cancer (mCRC). For mutation analysis, the current
methods are time-consuming, and not readily available to all oncologists and
pathologists. We have developed a novel, simple, sensitive and fully automated
molecular diagnostic system (AMDS) for point of care testing (POCT). Here we
report the results of a comparison study between AMDS and direct sequencing (DS)
in the detection of KRAS, BRAF and PI3KCA somatic mutations.
METHODOLOGY/PRINCIPAL FINDING: DNA was extracted from a slice of either frozen
(n = 89) or formalin-fixed and paraffin-embedded (FFPE) CRC tissue (n = 70), and
then used for mutation analysis by AMDS and DS. All mutations (n = 41 among
frozen and 27 among FFPE samples) detected by DS were also successfully (100%)
detected by the AMDS. However, 8 frozen and 6 FFPE samples detected as wild-type
in the DS analysis were shown as mutants in the AMDS analysis. By
cloning-sequencing assays, these discordant samples were confirmed as true
mutants. One sample had simultaneous "hot spot" mutations of KRAS and PIK3CA,
and cloning assay comfirmed that E542K and E545K were not on the same allele.
Genotyping call rates for DS were 100.0% (89/89) and 74.3% (52/70) in frozen and
FFPE samples, respectively, for the first attempt; whereas that of AMDS was
100.0% for both sample sets. For automated DNA extraction and mutation detection
by AMDS, frozen tissues (n = 41) were successfully detected all mutations within
70 minutes.
CONCLUSIONS/SIGNIFICANCE: AMDS has superior sensitivity and accuracy over DS,
and is much easier to execute than conventional labor intensive manual mutation
analysis. AMDS has great potential for POCT equipment for mutation analysis. BACKGROUND: Tumour growth in colorectal cancer and other solid cancers is
frequently supported by activating mutations in the epidermal growth factor
receptor (EGFR) signaling pathway (Patholog Res Int 2011:932932, 2011).
Treatment of metastatic colorectal cancer with targeted anti-EGFR therapeutics
such as cetuximab extends survival in only 25% of patients who test wild-type
for KRAS, while the majority of patients prove resistant (J Clin Oncol
28(7):1254-1261, 2010).Prediction of cetuximab responsiveness for KRAS wild-type
colorectal cancers is currently not well defined, and prognostic biomarkers
would help tailor treatment to individual patients. Somatic mutation of the EGFR
signalling pathway is a prevalent mechanism of resistance to cetuximab (Nature
486(7404):532-536, 2012). If the human genome harbours variants that influence
susceptibility of the EGFR pathway to oncogenic mutation, such variants could
also be prognostic for cetuximab responsiveness.
METHODS: We assessed whether patient genetic variants may associate with somatic
mutation of the EGFR signalling pathway. We combined tumour mutation data from
the Cancer Genome Atlas with matched patient genetic data, and tested for
germline variants that associate with somatic mutation of the EGFR pathway
(including EGFR, KRAS, BRAF, PTEN and PIK3CA).
RESULTS: Two single nucleotide polymorphisms (SNPs) located 90 kb upstream of
the TERT oncogene associated with somatic mutation of the EGFR pathway beyond
the threshold of genome-wide significance: rs7736074 (P = 4.64 × 10-9) and
rs4975596 (P = 5.69 × 10-9). We show that allelic variants of rs7736074 and
rs4975596 modulate TERT expression levels in multiple cancer types, and exhibit
preliminary prognostic value for response to cetuximab.
CONCLUSIONS: We have identified two germline SNPs that associate with somatic
mutation of the EGFR pathway, and may be prognostic for cetuximab
responsiveness. These variants could potentially contribute to a panel of
prognostic biomarkers for assessing whether metastatic colorectal cancer
patients are likely to derive benefit from cetuximab treatment. Genotyping of a
large cohort of cetuximab-treated colorectal cancer patients is called for to
further clarify the association. |
Is signal transducer and activator of transcription-3 (STAT3) critical for tumor angiogenesis progression? | (STAT3) is a latent cytoplasmic transcription factor, originally discovered as a transducer of signal from cell surface receptors to the nucleus. It is activated by tyrosine phosphorylation at position 705 leading to its dimerization, nuclear translocation, DNA binding, and activation of gene transcription. Under normal physiological conditions, STAT3 activation is tightly regulated. However, compelling evidence suggests that STAT3 is constitutively activated in many cancers and plays a pivotal role in tumor growth and metastasis. It regulates cellular proliferation, invasion, migration, and angiogenesis that are critical for cancer metastasis | Cytokine and growth factor receptor engagement leads to the rapid
phosphorylation and activation of latent, cytosolic signal transducers and
activators of transcription (STAT) proteins, which then translocate to the
nucleus where they regulate transcriptional events from specific promoter
sequences. STAT3 expression in particular has been associated with Abl, Src, and
HTLV-1 transformation of normal cells. B-1 lymphocytes are self-renewing, CD5+ B
cells that display a propensity for maligt transformation and are the normal
counterpart to human chronic lymphocytic leukemias. Further, B-1 cells are
characterized by aberrant intracellular signaling, including hyperresponsiveness
to phorbol ester PKC agonists. Here we demonstrate that B-1 lymphocytes
constitutively express nuclear activated STAT3, which is not expressed by
unmanipulated conventional (B-2) lymphocytes. In contrast, STAT3 activation is
induced in B-2 cells after antigen receptor engagement in a delayed fashion
(after 3 h). Induction of STAT3 is inhibited by both the serine/threonine
protein kinase inhibitor H-7 and the immunosuppressive drug rapamycin and
requires de novo protein synthesis, demonstrating novel coupling between sIg and
STAT proteins that differs from the classical paradigm for STAT induction by
cytokine receptors. The inability of prolonged stimulation of conventional B-2
cells with anti-Ig, a treatment sufficient to induce CD5 expression, to result
in sustained STAT3 activation suggests that STAT3 is a specific nuclear marker
for B-1 cells. Thus, STAT3 may play a role in B cell antigen-specific signaling
responses, and its constitutive activation is associated with a normal cell
population exhibiting intrinsic proliferative behavior. Signal transducer and activator of transcription (STAT) 3 is overexpressed or
activated in most types of human tumors and has been classified as an oncogene.
In the present study, we investigated the contribution of the STAT3s to the
proinvasive activity of trefoil factors (TFF) and vascular endothelial growth
factor (VEGF) in human colorectal cancer cells HCT8/S11 expressing VEGF
receptors. Both intestinal trefoil peptide (TFF3) and VEGF, but not pS2 (TFF1),
activate STAT3 signaling through Tyr(705) phosphorylation of both STAT3alpha and
STAT3beta isoforms. Blockade of STAT3 signaling by STAT3beta, depletion of the
STAT3alpha/beta isoforms by RNA interference, and pharmacologic inhibition of
STAT3alpha/beta phosphorylation by cucurbitacin or STAT3 inhibitory peptide
abrogates TFF- and VEGF-induced cellular invasion and reduces the growth of
HCT8/S11 tumor xenografts in athymic mice. Differential gene expression analysis
using DNA microarrays revealed that overexpression of STAT3beta down-regulates
the VEGF receptors Flt-1, neuropilins 1 and 2, and the inhibitor of DNA
binding/differentiation (Id-2) gene product involved in the neoplastic
transformation. Taken together, our data suggest that TFF3 and the essential
tumor angiogenesis regulator VEGF(165) exert potent proinvasive activity through
STAT3 signaling in human colorectal cancer cells. We also validate new
therapeutic strategies targeting STAT3 signaling by pharmacologic inhibitors and
RNA interference for the treatment of colorectal cancer patients. Signal transducer and activator of transcription 3 (STAT3) is a transcription
factor that plays a critical role in cytokine and growth factor signaling and is
frequently activated in human tumors. Human telomerase reverse transcriptase
(hTERT) is also often overexpressed in tumor cells and mediates cellular
immortalization. Here we report that STAT3 directly regulates the expression of
hTERT in a variety of human cancer cells. Moreover, STAT3 activity is required
for the survival of many human tumors, and hTERT expression contributes to the
survival of STAT3-dependent tumor cells. In addition, we find that growth
factors and cytokines stimulate hTERT expression in primary human cells in a
STAT3-dependent manner. Thus, STAT3 is a key regulator of hTERT expression in
both normal and tumor cells. Signal transducer and activator of transcription 3 (Stat3) is one of a family of
cytoplasmic proteins that participate in normal cellular responses to cytokines
and growth factors as transcription factors. Stat3 modulates various
physiological functions including cell survival, cell-cycle regulation, and
angiogenesis through regulation of gene expression, and its constitutive
activation is associated with a number of human epithelial cancers. Recent
studies with skin-specific gain and loss of Stat3 function transgenic mice have
shown that Stat3 plays critical roles in skin carcinogenesis. Multistage skin
carcinogenesis bioassays performed with these transgenic mice clearly
demonstrate that Stat3 is required for both tumor initiation and promotion
through regulation of genes involved in survival and proliferation,
respectively. Stat3 also plays a role in maligt progression of skin tumors by
regulating genes that are involved in angiogenesis and invasion. Further studies
have revealed that Stat3 plays a critical role in epidermal cell proliferation
and survival following exposure to ultraviolet B (UVB) irradiation. In addition,
Stat3 is constitutively active in UVB-induced skin tumors from both mice and
humans. Collectively, these studies suggest that Stat3 may be a potential target
for both the prevention and treatment of human epithelial cancers including skin
cancer. BACKGROUND: RET/PTC (rearranged in transformation/papillary thyroid carcinomas)
gene rearrangements are the most frequent genetic alterations identified in
papillary thyroid carcinoma. Although it has been established that RET/PTC
kinase plays a crucial role in intracellular signaling pathways that regulate
cellular transformation, growth, and proliferation in thyroid epithelial cells,
the upstream signaling that leads to the activation of RET/PTC is largely
unknown. Based on the observation of high levels of PLD expression in human
papillary thyroid cancer tissues, we investigated whether PLD plays a role in
the regulating the RET/PTC-induced STAT3 activation.
METHODS: Cancer tissue samples were obtained from papillary thyroid cancer
patients (n = 6). The expression level of PLD was examined using
immunohistochemistry and western blotting. Direct interaction between RET/PTC
and PLD was analyzed by co-immunoprecipitation assay. PLD activity was assessed
by measuring the formation of [3H]phosphatidylbutanol, the product of
PLD-mediated transphosphatidylation, in the presence of n-butanol. The
transcriptional activity of STAT3 was assessed by m67 luciferase reporter assay.
RESULTS: In human papillary thyroid cancer, the expression levels of PLD2
protein were higher than those in the corresponding paired normal tissues. PLD
and RET/PTC could be co-immunoprecipitated from cells where each protein was
over-expressed. In addition, the activation of PLD by pervanadate triggered
phosphorylation of tyrosine 705 residue on STAT-3, and its phosphorylation was
dramatically higher in TPC-1 cells (from papillary carcinoma) that have an
endogenous RET/PTC1 than in ARO cells (from anaplastic carcinoma) without
alteration of total STAT-3 expression. Moreover, the RET/PTC-mediated
transcriptional activation of STAT-3 was synergistically increased by
over-expression of PLD, whereas the PLD activity as a lipid hydrolyzing enzyme
was not affected by RET/PTC.
CONCLUSION: These findings led us to suggest that the PLD synergistically
functions to activate the STAT3 signaling by interacting directly with the
thyroid oncogenic kinase RET/PTC. BACKGROUND INFORMATION: STAT3 (signal transducer and activator of transcription
3) is an important transcription factor involved in many biological events,
including apoptosis, tumorigenesis, angiogenesis and epithelial-to-mesenchymal
transition. However, no direct evidence for a role of STAT3 in 3T3-L1 adipocyte
differentiation has been reported.
RESULTS: In the present study, we found that rapid activation of STAT3, lasting
for more than 48 h, was elicited upon induction of adipogenesis. Both the
STAT3-selective inhibitor stattic and the JAK2 (Janus kinase 2)/STAT3-selective
inhibitors AG490 and Gö6976 inhibited STAT3 activation, leading to the
suppression of adipocyte differentiation. Adipocyte differentiation was also
suppressed by STAT3 siRNA (small interfering RNA) or domit-negative STAT3.
Interestingly, the PPARgamma (peroxisome-proliferator-activated receptor gamma)
agonist TAZ (troglitazone) abolished the STAT3-inhibitor- and RNAi (RNA
interference)-mediated suppression of adipogenesis. However, TAZ treatment had
no effect on the stattic- and AG490-mediated down-regulation of STAT3
activation, suggesting that STAT3 regulates adipocyte differentiation through
signalling that occurs upstream of PPARgamma.
CONCLUSION: These data indicate that STAT3 functions as a critical factor for
adipogenesis via a mechanism involving the PPARgamma activation pathway. The use of targeted cancer therapies in combination with conventional
chemotherapeutic agents and/or radiation treatment has increased overall
survival of cancer patients. However, longer survival is accompanied by
increased incidence of comorbidities due, in part, to drug side effects and
toxicities. It is well accepted that inflammation and tumorigenesis are linked.
Because peroxisome proliferator-activated receptor (PPAR)-gamma agonists are
potent mediators of anti-inflammatory responses, it was a logical extension to
examine the role of PPARgamma agonists in the treatment and prevention of
cancer. This paper has two objectives: first to highlight the potential uses for
PPARgamma agonists in anticancer therapy with special emphasis on their role
when used as adjuvant or combined therapy in the treatment of hematological
maligcies found in the vasculature, marrow, and eyes, and second, to review
the potential role PPARgamma and/or its ligands may have in modulating
cancer-associated angiogenesis and tumor-stromal microenvironment crosstalk in
bone marrow. PURPOSE: Eupatilin is an antioxidative flavone and a phytopharmaceutical derived
from Artemisia asiatica. It has been reported to possess anti-tumor activity in
some types of cancer including gastric cancer. Eupatilin may modulate the
angiogenesis pathway which is part of anti-inflammatory effect demonstrated in
gastric mucosal injury models. Here we investigated the anti-tumor effects of
eupatilin on gastric cancer cells and elucidated the potential underlying
mechanism whereby eupatilin suppresses angiogenesis and tumor growth.
MATERIALS AND METHODS: The impact of eupatilin on the expression of angiogenesis
pathway proteins was assessed using western blots in MKN45 cells. Using a
chromatin immunoprecipitation assay, we tested whether eupatilin affects the
recruitment of signal transducer and activator of transcription 3 (STAT3), aryl
hydrocarbon receptor nuclear translocator (ARNT) and hypoxia-inducible factor-1α
(HIF-1α) to the human VEGF promoter. To investigate the effect of eupatilin on
vasculogenesis, tube formation assays were conducted using human umbilical vein
endothelial cells (HUVECs). The effect of eupatilin on tumor suppression in
mouse xenografts was assessed.
RESULTS: Eupatilin significantly reduced VEGF, ARNT and STAT3 expression
prominently under hypoxic conditions. The recruitment of STAT3, ARNT and HIF-1α
to the VEGF promoter was inhibited by eupatilin treatment. HUVECs produced much
foreshortened and severely broken tubes with eupatilin treatment. In addition,
eupatilin effectively reduced tumor growth in a mouse xenograft model.
CONCLUSIONS: Our results indicate that eupatilin inhibits angiogenesis in
gastric cancer cells by blocking STAT3 and VEGF expression, suggesting its
therapeutic potential in the treatment of gastric cancer. In the canonical STAT3 signaling pathway, binding of agonist to receptors
activates Janus kinases that phosphorylate cytoplasmic STAT3 at tyrosine 705
(Y705). Phosphorylated STAT3 dimers accumulate in the nucleus and drive the
expression of genes involved in inflammation, angiogenesis, invasion, and
proliferation. Here, we demonstrate that human cytomegalovirus (HCMV) infection
rapidly promotes nuclear localization of STAT3 in the absence of robust
phosphorylation at Y705. Furthermore, infection disrupts interleukin-6
(IL-6)-induced phosphorylation of STAT3 and expression of a subset of
IL-6-induced STAT3-regulated genes, including SOCS3. We show that the HCMV
72-kDa immediate-early 1 (IE1) protein associates with STAT3 and is necessary to
localize STAT3 to the nucleus during infection. Furthermore, expression of IE1
is sufficient to disrupt IL-6-induced phosphorylation of STAT3, binding of STAT3
to the SOCS3 promoter, and SOCS3 gene expression. Finally, inhibition of STAT3
nuclear localization or STAT3 expression during infection is linked to
diminished HCMV genome replication. Viral gene expression is also disrupted,
with the greatest impact seen following viral DNA synthesis. Our study
identifies IE1 as a new regulator of STAT3 intracellular localization and IL-6
signaling and points to an uticipated role of STAT3 in HCMV infection. OBJECTIVE: Temporal bone squamous cell carcinoma (SCC) accounts for less than
0.2% of all head and neck tumors. Although some progress has been made in
treating this aggressive tumor, the prognosis in advanced cases remains poor.
More effective therapeutic strategies need to be considered, including
receptor-mediated carcinoma-targeted therapy. Phosphorylated STAT3 (pSTAT3)
regulates many genes that are necessarily expressed in cancer initiation,
development, and progression, being involved in proliferation, anti-apoptosis,
invasion, angiogenesis, and immune surveillance evasion. The aim of the present
study was to preliminarily investigate the potential prognostic role of pSTAT3
expression in temporal bone SCC.
STUDY DESIGN: Retrospective clinicopathologic investigation.
SETTING: Tertiary referral centers.
PATIENTS: Twenty-five consecutively operated patients with primary temporal bone
SCC.
INTERVENTION: pSTAT3 immunohistochemical expression in primary temporal bone
SCCs was assessed with the aid of computer-based image analysis.
MAIN OUTCOME MEASURES: Conventional clinicopathologic parameters and pSTAT3
expression were correlated with SCC prognosis.
RESULTS: pT, stage, and surgical margin status were significantly related with
recurrence rate (p = 0.002, p = 0.01, and p = 0.047, respectively) and
disease-free survival (DFS) (p = 0.0049, p = 0.031, and p = 0.035,
respectively). pT classification was also related with disease-specific survival
(DSS) (p = 0.035). The SCC recurrence rate did not correlate with pSTAT3
expression. Statistical analyses ruled out any significant difference in DFS or
DSS when patients were stratified by pSTAT3 expression (>80.0% or ≤80.0%).
CONCLUSION: Despite our preliminary results, the role of pSTAT3 in temporal bone
SCC warrants further investigation in larger series because there is increasing
evidence in preclinical models to indicate that inhibiting STAT3 phosphorylation
can be a useful addition to different anticancer strategies. Angiogenesis plays a critical role in the development of solid tumors by
supplying nutrients and oxygen to support continuous growth of tumor as well as
providing an avenue for hematogenous metastasis. Tumor angiogenesis is highly
regulated by multiple intracellular signaling transduction cascades such as
Hedgehog, STAT3, Akt and p70S6K pathways that are known to malfunction in many
types of cancer including colorectal cancer (CRC). Therefore, suppression of
tumor angiogenesis through targeting these signaling pathways has become a
promising strategy for cancer chemotherapy. Ursolic acid (UA) is a major active
compound present in many medicinal herbs that have long been used in China for
the clinical treatment of various types of cancer. Although previous studies
have demonstrated an antitumor effect for UA, the precise mechanisms of its
anti-angiogenic activity are not well understood. To further elucidate the
mechanism(s) of the tumorcidal activity of UA, using a CRC mouse xenograft
model, chick embryo chorioallantoic membrane (CAM) model, the human colon
carcinoma cell line HT-29 and human umbilical vein endothelial cells (HUVECs),
in the present study we evaluated the efficacy of UA against tumor growth and
angiogenesis in vivo and in vitro and investigated the underlying molecular
mechanisms. We found that administration of UA significantly inhibited tumor
volume but had no effect on body weight changes in CRC mice, suggesting that UA
can suppress colon cancer growth in vivo without noticeable signs of toxicity.
In addition, UA treatment reduced intratumoral microvessel density (MVD) in CRC
mice, decreased the total number of blood vessels in the CAM model, and dose and
time-dependently inhibited the proliferation, migration and tube formation of
HUVECs, demonstrating UA's antitumor angiogenesis in vivo and in vitro.
Moreover, UA treatment inhibited the expression of critical angiogenic factors,
such as VEGF-A and bFGF. Furthermore, UA suppressed the activation of sonic
hedgehog (SHH), STAT3, Akt and p70S6K pathways. Collectively, our findings
suggest that inhibition of tumor angiogenesis via suppression of multiple
signaling pathways might be one of the mechanisms whereby UA can be effective in
cancer treatment. Herein we review our progress on the development of phosphopeptide-based
prodrugs targeting the SH2 domain of STAT3 to prevent recruitment to cytokine
and growth factor receptors, activation, nuclear translocation and transcription
of genes involved in cancer. We developed high affinity phosphopeptides (K I =
46-200 nM). Corresponding prodrugs inhibited constitutive and IL-6 induced
Tyr705 phosphorylation at 0.5-1 μM in a variety of human cancer cell lines. They
were not cytotoxic at 5 μM in vitro but they inhibited tumor growth in a human
xenograft breast cancer model in mice, accompanied by reduced VEGF expression
and angiogenesis. OBJECTIVE: The aim of this study was to determine the correlation between human
adrenocortical carcinoma and the proteins involved in tumor angiogenesis, and to
evaluate the angiogenic status of adrenocortical carcinoma.
METHODS: The expression of signal transducer and activator of transcription 3
and insulin-like growth factor 2 as well as microvessel density was measured in
a series of tissue samples from 44 human sporadic adrenocortical tumors by
immunohistochemistry. These specimens were classified as adenomas (n = 20) and
carcinomas (n = 24) according to the histological criteria defined by Weiss.
RESULTS: A total of 19 of 24 (79.17 %) maligt cases showed positive staining
for signal transducer and activator of transcription 3 and 4 of 20 (20.00 %)
benign cases showed positive, the difference of signal transducer and activator
of transcription 3 expression between adrenocortical adenomas and adrenocortical
carcinomas was statistically significant (P < 0.001). Similarly, insulin-like
growth factor 2 staining was seen in 70.83 % (17/24) of the maligt cases
versus 25.00 % (5/20) of the benign, the difference of insulin-like growth
factor 2 expression among two groups was statistically significant (P = 0.002).
Maligt cases showed higher microvessel density compared to benign tumors
(84.70 ± 12.44 vs 21.05 ± 8.07, P < 0.001). Signal transducer and activator of
transcription 3 and insulin-like growth factor 2 expression were positively
correlated with microvessel density in all specimens (r_s = 0.832, P < 0.001;
r_s = 0.703, P = 0.001).
CONCLUSIONS: This study has confirmed that adrenocortical carcinoma overexpress
signal transducer and activator of transcription 3 and insulin-like growth
factor 2; these results suggest that angiogenesis of human adrenocortical
carcinoma may be mediated by these proteins and they could represent selective
targets for the molecularly targeted treatments of adrenocortical carcinoma. Signal transducer and activator of transcription 3 (STAT3) is a latent
cytoplasmic transcription factor, originally discovered as a transducer of
signal from cell surface receptors to the nucleus. It is activated by tyrosine
phosphorylation at position 705 leading to its dimerization, nuclear
translocation, DNA binding, and activation of gene transcription. Under normal
physiological conditions, STAT3 activation is tightly regulated. However,
compelling evidence suggests that STAT3 is constitutively activated in many
cancers and plays a pivotal role in tumor growth and metastasis. It regulates
cellular proliferation, invasion, migration, and angiogenesis that are critical
for cancer metastasis. In this paper, we first describe the mechanism of STAT3
regulation followed by how STAT3 is involved in cancer metastasis, then we
summarize the various small molecule inhibitors that inhibit STAT3 signaling. Lung cancer is the most fatal cancer and development of agents that suppress
lung tumorigenesis is a crucial strategy to reduce mortality related to this
disease. In the present study, we showed, using an in vitro model of lung
tumorigenesis, that dimethylamino-parthenolide (DMAPT), a water soluble
parthenolide analog, selectively inhibited the growth and survival of
premaligt and maligt cells with minimal effects on parental immortalized
cells. These effects were paralleled by suppression of pSTAT3, Mcl-1 and cyclin
D1 and PARP cleavage, suggesting that the antiproliferative and apoptotic
effects of DMAPT could be mediated, at least in part, via suppression of the
STAT3 signaling pathway. Moreover, in tobacco smoke carcinogen-induced lung
tumor bioassay in mice, intranasal instillation of low doses of DMAPT
significantly reduced the overall lung tumor multiplicity by 39%. Interestingly,
the drug was specifically effective (62% reduction) against bigger lung tumors
(> 2 mm), which have a higher potential to develop into lung adenocarcinoma.
Western immunoblotting analyses of mouse lung tissues indicated significantly
lower level of pSTAT3 and Mcl-1 in the carcinogen plus DMAPT group relative to
the group treated with the carcinogen only. Given the evidence that STAT3 is
activated in more than half of lung cancers and it regulates genes involved in
cell proliferation, survival and angiogenesis, DMAPT is a promising agent for
lung cancer chemoprevention in subjects who are at high risk of developing this
devastating disease. BACKGROUND: Interleukin-27 signaling is mediated by the JAK-STAT pathway via
activation of STAT1 and STAT3, which have tumor suppressive and oncogenic
activities, respectively. Epithelial-mesenchymal transition (EMT) and
angiogenesis are key processes in carcinogenesis. Although IL-27 has been shown
to have potent anti-tumor activity in various cancer models, the role of IL-27
in EMT and angiogenesis is poorly understood. In this study, we investigated the
role of IL-27 in regulating EMT and angiogenesis through modulation of the STAT
pathways in human non-small cell lung carcinoma (NSCLC) cells.
METHODS: STAT activation following IL-27 exposure was measured in human NSCLC
cell lines. Expression of epithelial (E-cadherin, γ-catenin) and mesenchymal
(N-cadherin, vimentin) markers were assessed by Western blot analysis.
Production of pro-angiogenic factors (VEGF, IL-8/CXCL8, CXCL5) were examined by
ELISA. Cell motility was examined by an in vitro scratch and transwell migration
assays. Selective inhibitors of STAT1 (STAT1 siRNAs) and STAT3 (Stattic) were
used to determine whether both STAT1 and STAT3 are required for IL-27 mediated
inhibition of EMT and secretion of angiogenic factors.
RESULTS: Our results demonstrate that IL-27 stimulation in NSCLC resulted in 1)
STAT1 and STAT3 activation in a JAK-dependent manner, 2) development of
epithelial phenotypes, including a decrease in the expression of a
transcriptional repressor for E-cadherin (SNAIL), and mesenchymal marker
(vimentin) with a reciprocal increase in the expression of epithelial markers,
3) inhibition of cell migration, and 4) reduced production of pro-angiogenic
factors. STAT1 inhibition in IL-27-treated cells reversed the IL-27 effect with
resultant increased expression of Snail, vimentin and the pro-angiogenic
factors. The inhibition of STAT3 activation had no effect on the development of
the epithelial phenotype.
CONCLUSION: IL-27 induces mesenchymal to epithelial transition and inhibits the
production of pro-angiogenic factors in a STAT1-domit pathway. These findings
highlight the importance of STAT1 in repressing lung carcinogenesis and describe
a new anti-tumor mechanism of IL-27. Lung cancer is a heterogeneous disease encompassing a wide array of genetic
abnormalities. The MET receptor tyrosine kinase is altered in many lung cancers,
especially non-small cell lung cancer (NSCLC), and clinical trials of MET
inhibitors that are under way are documenting cases of acquired resistance. On
the basis of the evidence that the RON tyrosine kinase receptor can also be
overexpressed in NSCLC, we evaluated the potent MET/RON dual kinase inhibitor
LY2801653 in this setting. LY2801653 was more efficacious than the
MET/ALK/RON/ROS inhibitor crizotinib with a distinct pattern of downstream
signaling effects. Using the PamGene platform, we found that inhibition of MET
and RON was associated with decreased phosphorylation of CBL, PI3K, and STAT3.
In classic and orthotopic mouse xenograft models of lung cancer, LY2801653
decreased tumor growth, dramatically inhibiting mitotic events and angiogenesis.
Taken together, our results argued that specific targeting of the MET/RON
kinases could provide robust inhibition of cell proliferation and tumor
outgrowth in multiple in vitro and in vivo models of NSCLC. These findings offer
a robust preclinical proof of concept for MET/RON targeting by LY2801653 as a
promising small-molecule modality to treat NSCLC. Radioresistance is a frustrating obstacle for patients with colorectal cancers
(CRCs) undergoing radiotherapy. There is an urgent need to find an effective
agent to increase the sensitivity of CRCs to radiation. Honokiol, an active
compound purified from Magnolia, was found to radiosensitize colorectal cancer
cells both in vitro and in vivo. However, the mechanisms control important
signaling that enhances radiosensitivity is currently unknown. In this study, we
have reviewed important signaling pathways that are closely related to
radiosensitization, such as cell cycle arrest, tumor angiogenesis, JAK/STAT3
signaling pathway and Mismatch repair. Studies show that honokiol can interfere
with these pathways at different levels. With overall analysis, it may bring
light on finding the possible mechanism by which honokiol acts as a
radiosensitizing agent for CRCs. Signal transducer and activator of transcription-3 (STAT3) is critical for
cancer progression by regulating tumor cell survival, proliferation, and
angiogenesis. Herein, we investigated the regulation of STAT3 activation and the
therapeutic effects of Icaritin, a prenyl flavonoid derivative from Epimedium
Genus, in renal cell carcinoma (RCC). Icaritin showed significant anti-tumor
activity in the human and mouse RCC cell lines, 786-O and Renca, respectively.
Icaritin inhibited both constitutive and IL-6-induced phospho-STAT3
(STAT3(Y705)) and reduced the level of STAT3-regulated proteins Bcl-xL, Mcl-1,
Survivin, and CyclinD1 in a dose-dependent manner. Icaritin also inhibited
activation of Janus-activated kinase-2 (JAK2), while it showed minimal effects
on the activation of other key signaling pathways, including AKT and MAPK.
Expression of the constitutively active form of STAT3 blocked Icaritin-induced
apoptosis, while siRNA directed against STAT3 potentiated apoptosis. Finally,
Icaritin significantly blunted RCC tumor growth in vivo, reduced STAT3
activation, and inhibited Bcl-xL and Cyclin E, as well as VEGF expression in
tumors, which was associated with reduced tumor angiogenesis. Overall, these
results suggest that Icaritin strongly inhibits STAT3 activation and is a
potentially effective therapeutic option for the treatment of renal cell
carcinoma. |
Which is the physiological target for LeuRS translational quality control? | QUALITY CONTROL | The fidelity of protein synthesis depends on the capacity of aminoacyl-tRNA
synthetases (AARSs) to couple only cognate amino acid-tRNA pairs. If amino acid
selectivity is compromised, fidelity can be ensured by an inherent AARS editing
activity that hydrolyses mischarged tRNAs. Here, we show that the editing
activity of Escherichia coli leucyl-tRNA synthetase (EcLeuRS) is not required to
prevent incorrect isoleucine incorporation. Rather, as shown by kinetic,
structural and in vivo approaches, the prime biological function of LeuRS
editing is to prevent mis-incorporation of the non-standard amino acid
norvaline. This conclusion follows from a reassessment of the discriminatory
power of LeuRS against isoleucine and the demonstration that a LeuRS
editing-deficient E. coli strain grows normally in high concentrations of
isoleucine but not under oxygen deprivation conditions when norvaline
accumulates to substantial levels. Thus, AARS-based translational quality
control is a key feature for bacterial adaptive response to oxygen deprivation.
The non-essential role for editing under normal bacterial growth has important
implications for the development of resistance to antimicrobial agents targeting
the LeuRS editing site. |
Is sumoylation implicated in myogenesis? | Yes, sumoylation is implicated in myogenesis. | The transcriptional modulator SnoN controls a diverse set of biological
processes, including cell proliferation and differentiation. The mechanisms by
which SnoN regulates these processes remain incompletely understood. Recent
studies have shown that SnoN exerts positive or negative regulatory effects on
transcription. Because post-translational modification of proteins by small
ubiquitin-like modifier (SUMO) represents an important mechanism in the control
of the activity of transcriptional regulators, we asked if this modification
regulates SnoN function. Here, we show that SnoN is sumoylated. Our data
demonstrate that the SUMO-conjugating E2 enzyme Ubc9 is critical for SnoN
sumoylation and that the SUMO E3 ligase PIAS1 selectively interacts with and
enhances the sumoylation of SnoN. We identify lysine residues 50 and 383 as the
SUMO acceptor sites in SnoN. Analyses of SUMO "loss-of-function" and
"gain-of-function" SnoN mutants in transcriptional reporter assays reveal that
sumoylation of SnoN contributes to the ability of SnoN to repress gene
expression in a promoter-specific manner. Although this modification has little
effect on SnoN repression of the plasminogen activator inhibitor-1 promoter and
only modestly potentiates SnoN repression of the p21 promoter, SnoN sumoylation
robustly augments the ability of SnoN to suppress transcription of the
myogenesis master regulatory gene myogenin. In addition, we show that the SnoN
SUMO E3 ligase, PIAS1, at its endogenous levels, suppresses myogenin
transcription. Collectively, our findings suggest that SnoN is directly
regulated by sumoylation leading to the enhancement of the ability of SnoN to
repress transcription in a promoter-specific manner. Our study also points to a
physiological role for SnoN sumoylation in the control of myogenin expression in
differentiating muscle cells. How multisite posttranslational modification coordinates dynamic regulation of
protein function is an issue fundamental to many biological processes. Related
to this, a composite sequence motif has recently been identified that couples
phosphorylation, sumoylation, and perhaps also deacetylation to control
transcriptional repression in stress response, mitogen and nuclear hormone
signaling, myogenesis, and neuronal differentiation. This motif is present in
many proteins, integrates cellular signals from diverse pathways, and serves as
a valuable signature for in silico identification of proteins regulated by
adjacent phosphorylation and sumoylation. Recent progress has been made on the role of oncoproteins c-Ski and related SnoN
in the control of cellular transformation. c-Ski/SnoN potently repress
transforming growth factor-beta (TGF-beta) antiproliferative signaling through
physical interaction with signal transducers called Smads. Overexpression of
c-Ski/SnoN also induces skeletal muscle differentiation, but how c-Ski/SnoN
function in myogenesis is largely unknown. During our investigation on the role
of sumoylation in TGF-beta signaling, we inadvertently found that SnoN is
modified by small ubiquitin-like modifier-1 (SUMO-1). Here, we biochemically
characterize SnoN sumoylation in detail and report the physiological function of
the modification. Sumoylation occurs primarily at lysine 50 (Lys-50). PIAS1 and
PIASx proteins physically interact with SnoN to stimulate its sumoylation, thus
serving as SUMO-protein isopeptide ligases (E3) for SnoN sumoylation. SnoN
sumoylation does not alter its metabolic stability or its ability to repress
TGF-beta signaling. Notably, loss of sumoylation in the Lys-50 site (via a
Lys-to-Arg point mutation) potently activates muscle-specific gene expression
and enhances myotube formation. Our study suggests a novel role for SUMO
modification in the regulation of myogenic differentiation. Regulatory transcription factors of the Pax family play fundamental roles in the
function of multipotent cells during vertebrate development, post-natal
regeneration, and cancer. Pax7 and its homologue Pax3 are important players in
neural crest and muscle development. Both genes are coexpressed in various
tissues and are thought to provide similar, but not identical, functions. The
mechanisms that allow specific regulation of Pax7 remain largely unknown. Here,
we report for the first time that Pax7 is regulated by SUMOylation. We identify
the interaction of Pax7 with Ubc9, the SUMO conjugating enzyme, and reveal that
SUMOylation machinery is enriched in neural crest precursors and plays a
critical role in NC development. We demonstrate that Pax7 becomes SUMOylated and
identify an essential role for lysine 85 (K85) in Pax7-SUMOylation. Despite high
conservation surrounding K85 amongst Pax genes, we were unable to identify
SUMOylation of other Pax proteins tested, including Pax3. Using a
non-SUMOylatable Pax7 variant (K85 X R), we demonstrate that SUMOylation is
essential for the function of Pax7 in neural crest development, C2C12 myogenic
differentiation, and transcriptional transactivation. Our study provides new
mechanistic insight into the molecular regulation of Pax7's function by
SUMOylation in neural crest and muscle development. Sumoylation is an important post-translational modification that alters the
activity of many transcription factors. However, the mechanisms that link
sumoylation to alterations in chromatin structure, which culminate in tissue
specific gene expression, are not fully understood. In this study, we
demonstrate that SUMO modification of the transcription factor Sharp-1 is
required for its full transcriptional repression activity and function as an
inhibitor of skeletal muscle differentiation. Sharp-1 is modified by sumoylation
at two conserved lysine residues 240 and 255. Mutation of these SUMO acceptor
sites in Sharp-1 does not impact its subcellular localization but attenuates its
ability to act as a transcriptional repressor and inhibit myogenic
differentiation. Consistently, co-expression of the SUMO protease SENP1 with
wild type Sharp-1 abrogates Sharp-1-dependent inhibition of myogenesis.
Interestingly, sumoylation acts as a signal for recruitment of the co-repressor
G9a. Thus, enrichment of G9a, and histone H3 lysine 9 dimethylation (H3K9me2), a
signature of G9a activity, is dramatically reduced at muscle promoters in cells
expressing sumoylation-defective Sharp-1. Our findings demonstrate how
sumoylation of Sharp-1 exerts an impact on chromatin structure and
transcriptional repression of muscle gene expression through recruitment of G9a. Ubiquitin Specific Protease 25 (USP25), a member of the deubiquitinase family,
is involved in several disease-related signal pathways including myogenesis,
immunity and protein degradation. It specially catalyzes the hydrolysis of the
K48-linked and K63-linked polyubiquitin chains. USP25 contains one
ubiquitin-associated domain and two ubiquitin-interacting motifs (UIMs) in its
N-terminal region, which interact with ubiquitin and play a role in substrate
recognition. Besides, it has been shown that the catalysis activity of USP25 is
either impaired by sumoylation or enhanced by ubiquitination within its UIM. To
elucidate the structural basis of the cross-regulation of USP25 function by
non-covalent binding and covalent modifications of ubiquitin and SUMO2/3, a
systematic structural biology study of USP25 is required. Here, we report the
(1)H, (13)C and (15)N backbone and side-chain resoce assignments of the
N-terminal ubiquitin binding domains (UBDs) of USP25 with BMRB accession number
of 19111, which is the first step of the systematic structural biology study of
the enzyme. |
What do studies show about the effect of Induced hypothermia in premature babies? | Randomised studies have demonstrated the efficacy of hypothermia for the treatment of perinatal hypoxic-ischaemic encephalopathy (HIE) in reducing rate of death or neurodevelopmental disabilities in term or late preterm infants. It remains unclear to what degree preterm infants were included in these studies.
A prospective non-randomised pilot study reported that mild hypothermia for 48 hours in preterm neonates with severe NEC (necrotising enterocolitis) seems both feasible and safe. | OBJECTIVE: To relate volumetric magnetic resoce imaging (MRI) findings to
hypothermia therapy and neurosensory impairments.
STUDY DESIGN: Newborns > or =36 weeks' gestation with hypoxic-ischemic
encephalopathy who participated in the National Institute of Child Health and
Human Development hypothermia randomized trial at our center were eligible. We
determined the relationship between hypothermia treatment and usual care
(control) to absolute and relative cerebral tissue volumes. Furthermore, we
correlated brain volumes with death or neurosensory impairments at 18 to 22
months.
RESULT: Both treatment groups were comparable before randomization. Total brain
tissue volumes did not differ in relation to treatment assignment. However,
relative volumes of subcortical white matter were significantly larger in
hypothermia-treated than control infants. Furthermore, relative total brain
volumes correlated significantly with death or neurosensory impairments.
Relative volumes of the cortical gray and subcortical white matter also
correlated significantly with Bayley Scales psychomotor development index.
CONCLUSION: Selected volumetric MRI findings correlated with hypothermia therapy
and neurosensory impairments. Larger studies using MRI brain volumes as a
secondary outcome measure are needed. OBJECTIVES: Necrotizing enterocolitis (NEC) with multiple organ dysfunction
syndrome (MODS) carries significant morbidity and mortality. There is extensive
experimental evidence to support investigation of therapeutic hypothermia in
infants with these conditions. We aimed to establish the feasibility and safety
of mild hypothermia in preterm neonates with NEC and MODS as a prelude to a
randomized trial.
METHODS: This was a prospective, nonrandomized pilot study of 15 preterm infants
who were referred for surgical intervention of advanced NEC and failure of at
least 3 organs. Whole-body cooling was achieved by ambient temperature
adjustment with or without cooling mattress. Three groups (n = 5 per group) were
cooled to core temperatures of 35.5 degrees C (+/-0.5 degrees C), 34.5 degrees
C, and 33.5 degrees C, respectively, for 48 hours before rewarming to 37 degrees
C. Infants were carefully assessed to identify adverse effects that potentially
were related to cooling and rewarming. A noncooled group (n = 10) with advanced
surgical NEC and MODS was used for comparison. Data are medians (interquartile
range).
RESULTS: Gestational age at birth was 27 weeks (26-30), admission weight was 1.1
kg (1.0-1.7), and admission age was 31 days (12-45). Core temperature was
maintained within target range for 90% (88%-97%) of the intended time.
Statistically significant relationships were identified between core temperature
and heart rate (P < .0001), pH (P < .0001), base excess (P = .003), and blood
clot dynamics (longer time to initial clot formation, slower rate of clot
formation, and decrease in clot strength; all P < .001) as assessed by
thromboelastography. No major clinical problems or adverse events were noted
during cooling or rewarming. Comparison with the noncooled group revealed no
increase in mortality, bleeding, infection, or need for inotropes in infants who
were cooled.
CONCLUSIONS: Mild hypothermia for 48 hours in preterm neonates with severe NEC
seems both feasible and safe. Additional investigation of the efficacy of this
therapeutic intervention in this population is warranted. INTRODUCTION: Randomised studies have demonstrated the efficacy of hypothermia
for the treatment of perinatal hypoxic-ischaemic encephalopathy (HIE) in term or
late preterm infants. In August 2006, the Neonatology Department at
Rigshospitalet, Copenhagen, introduced total body cooling for infants born at
term with HIE.
MATERIAL AND METHODS: This retrospective study comprises data from medical
records of newborn children born with HIE during a period of 32 months. Relevant
data for cooling were recorded. Structured neurological examinations were
carried out on survivors when they were ten and or 18 months old.
RESULTS: A total of 32 infants fulfilled the criteria for cooling, the incidence
being 0.4/1000 births. Twenty infants were cooled for 72 hours. Eleven infants
had cooling discontinued before 72 hours because of their grave prognosis. One
infant had cooling discontinued because of pulmonary hypertension. Most infants
were cooled before six hours of age (median four hours). The mortality rate was
41%. A total of 45% were cooled without being placed in a ventilator. The side
effects were of no major concern. Eight children had a neurological follow-up.
One child had developed cerebral palsy and two children suffered delayed
development.
CONCLUSION: Total body cooling was carried out before six hours of age in the
vast majority of infants born with HIE. Side effects were of less concern.
Respiratory support with a ventilator could be avoided in 45% of the infants
cooled for 72 hours. The mortality rate was 41%. Therapeutic hypothermia is a recognized treatment for term infants with
hypoxic-ischemic encephalopathy (HIE) in reducing rate of death or
neurodevelopmental disabilities. Little is known about applications of this
treatment to preterm newborns. Studies in animal experimental models
demonstrated the efficacy of hypothermia in preterm fetuses but clinical
application to newborn infants are limited to restricted cases, as severe
necrotizing enterocolitis (NEC). We present a case of therapeutic whole body
cooling in a baby at 34 weeks and 6 days of gestational age with HIE. |
Describe what is the advantage of using a stain free protein gel in a Western Blot experiment? | Stain-Free technology can be used as a normalization tool in Western blot analysis. | Western blots are used to specifically measure the relative quantities of
proteins of interest in complex biological samples. Quantitative measurements
can be subject to error due to process inconsistencies such as uneven protein
transfer to the membrane. These non-sample-related variations need to be
compensated for by an approach known as normalization. Two approaches to data
normalization are commonly employed: housekeeping protein (HKP) normalization
and total protein normalization (TPN). In this study, we evaluated the
performance of Stain-Free technology as a novel TPN tool for Western blotting
experiments in comparison with glyceraldehyde-3-phosphate dehydrogenase (GAPDH)
as a representative of the HKP normalization strategy. The target protein (TP)
used for this study was MCM7, a DNA licensing replication factor, which was
shown previously to be down-regulated by 20% in irradiated lymphoblastoid cell
lines (LCLs). We studied the regulation of MCM7 with a multiplex Western
blotting approach based on fluorescently labeled secondary antibodies and found
that Stain-Free technology appears to be more reliable, more robust, and more
sensitive to small effects of protein regulation when compared with HKP
normalization with GAPDH. Stain-Free technology offers the additional advantages
of providing checkpoints throughout the Western blotting process by allowing
rapid visualization of gel separation and protein transfer. The western blot is a very useful and widely adopted lab technique, but its
execution is challenging. The workflow is often characterized as a "black box"
because an experimentalist does not know if it has been performed successfully
until the last of several steps. Moreover, the quality of western blot data is
sometimes challenged due to a lack of effective quality control tools in place
throughout the western blotting process. Here we describe the V3 western
workflow, which applies stain-free technology to address the major concerns
associated with the traditional western blot protocol. This workflow allows
researchers: 1) to run a gel in about 20-30 min; 2) to visualize sample
separation quality within 5 min after the gel run; 3) to transfer proteins in
3-10 min; 4) to verify transfer efficiency quantitatively; and most importantly
5) to validate changes in the level of the protein of interest using total
protein loading control. This novel approach eliminates the need of stripping
and reprobing the blot for housekeeping proteins such as β-actin, β-tubulin,
GAPDH, etc. The V3 stain-free workflow makes the western blot process faster,
transparent, more quantitative and reliable. |
Which is the target of the drug Denosumab? | Denosumab (Dmab) is a fully human monoclonal antibody against the receptor activator of nuclear factor-κB ligand (RANKL). | Denosumab is a human monoclonal antibody which specifically blocks receptor
activator of nuclear factor κB ligand and is a very potent antiresorptive drug.
Its efficacy in reducing the risk of vertebral, hip and nonskeletal fracture has
been proven in a large prospective, randomized multicenter study of 7808
postmenopausal women with osteoporosis [Fracture Reduction Evaluation of
Denosumab in Osteoporosis Every 6 Months (FREEDOM) trial]. Denosumab causes
somewhat greater increases in bone mineral density (BMD) than the class of
bisphosphonate antiresorptives. Denosumab also causes an increase in bone mass
and bone strength in the spine, ultradistal and diaphysis of the radius,
proximal tibia and the hip. Recently long-term treatment with denosumab has been
shown to cause a continued almost linear increase in total hip and femoral neck
BMD beyond 3 years up to 8 years. In this respect, denosumab seems to differ
from the bisphosphonate group in which the rate of improvement of BMD diminishes
and for some drugs becomes negative after 3-4 years when the process of
secondary mineralization flattens out. This unique property of an antiresorptive
drug points towards mechanisms of action which differ from the bisphosphonate
group. Both types of antiresorptives decrease cortical porosity but contrary to
bisphosphonates the reduction in cortical porosity continues with denosumab
which, in addition, also seems to cause a slight continuous modeling-based
formation of new bone despite suppression of bone remodeling. The net effect is
an increase in cortical thickening and bone mass, and increased strength of
cortical bone. This may contribute substantially to the significant further
reduction of the nonvertebral fracture risk which was found in the long-term
denosumab arm of the FREEDOM extension trial during years 4-7. Author information:
(1)Pneumology-Allergy Department, Puerta del Mar University Hospital, Cádiz,
Spain.
(2)Servei de Pneumologia, Hospital Universitari Vall d'Hebron, Passeig Vall
d'Hebron, 119, 08035 Barcelona, Spain.
(3)Joaquín Pece Primary Care Centre, San Ferdo, Cádiz Spain.
(4)Allergy Department, Hospital Nuestra Señora del Prado, Talavera de la Reina,
Toledo Spain.
(5)Hospital Pharmacy, Puerta del Mar University Hospital, Cádiz, Spain.
(6)Unidad de Gestión Clínica Aparato Locomotor, Rheumatology Department, Puerta
del Mar University Hospital, Cádiz, Spain.
(7)Unidad de Gestión Clínica Aparato Locomotor, Orthopaedic Surgery and
Traumatology Department, Puerta del Mar University Hospital, Cádiz, Spain. Patient adherence to many osteoporosis treatments, primarily bisphosphonates, is
generally poor, thus leading to a significant reduction in antifracture
efficacy. Patient perceptions about the necessity of the prescribed medication
to treat osteoporosis and the concerns about the potential adverse effects are
important and potentially modifiable determits of adherence, in addition to
other factors, such as difficult dosing regimens and high dosing frequency.
Denosumab (Dmab) is a fully human monoclonal antibody against the receptor
activator of nuclear factor-κB ligand (RANKL), which, through the prevention of
the RANKL/RANK interaction, inhibits osteoclast-mediated bone resorption and
significantly reduces the risk of vertebral, nonvertebral, and hip fractures. It
is administered subcutaneously every 6 months for the treatment of
postmenopausal osteoporosis. Preference and adherence to Dmab treatment were
assessed in various clinical trials. Although with some limitations, available
data suggest that Dmab is preferred to bisphosphonates, produces greater
satisfaction than bisphosphonates, and would be preferentially chosen for
long-term treatment. Moreover, patient perceptions about the necessity of Dmab
treatment clearly outweigh the concerns about the injections, and positive
beliefs about treatment positively influence medication-taking behavior.
According to these data, Dmab may represent a reasonable alternative to
bisphosphonates, particularly for osteoporotic women in whom a suboptimal or
even poor adherence to oral treatments is expected. |
Which enzyme is inhibited by a drug fostamatinib? | Fostamatinib (R788) acts by inhibiting spleen tyrosine kinase. Fostamatinib (R788) is a prodrug rapidly converted to its active metabolite on oral administration. This (known as R406) is a potent inhibitor of spleen tyrosine kinase that is required for the expression of a number of proinflammatory cytokines. Fostamatinib has been shown to be effective in patients with rheumatoid arthritis, leukemia, lymphoma, bronchial asthma and thrombocytopenic purpura. | Rigel Pharmaceuticals Inc is developing fostamatinib, a prodrug of the spleen
tyrosine kinase (Syk) inhibitor R-406, for the potential treatment of autoimmune
diseases such as rheumatoid arthritis (RA), idiopathic thrombocytopenic purpura
(ITP) and B-cell lymphomas. Syk is a key mediator of Fc and B-cell receptor
signaling in inflammatory cells, such as B-cells, mast cells, macrophages and
neutrophils. Preclinical studies of R-406 or fostamatinib demonstrated a
significant reduction in major inflammatory mediators such as TNFalpha, IL-1,
IL-6 and IL-18, leading to reduced inflammation and bone degradation in models
of RA. In a phase II clinical trial, fostamatinib treatment effectively improved
American College of Rheumatology response rates in patients with RA. Preclinical
studies and phase II trials also suggested the potential of using fostamatinib
for the treatment of ITP and B-cell lymphomas, by increasing platelet counts and
inducing response rates, respectively. Fostamatinib is orally bioavailable and
was well tolerated in phase I and II trials, with the most common side effect
being gastrointestinal symptoms. At the time of publication, phase II trials for
fostamatinib were ongoing in patients with RA, ITP and B-cell lymphomas. The Syk
inhibitor appears to be a promising therapeutic for immunological diseases, but
further data are required to establish the efficacy and long-term safety of the
drug in humans. Antibody-mediated glomerulonephritis, including that resulting from immune
complexes, is an important cause of renal failure and is in need of more
specific and effective treatment. Binding of antibody or immune complexes to Fc
receptors activates intracellular signal transduction pathways, including spleen
tyrosine kinase (Syk), leading to the production of inflammatory cytokines. We
examined the effect of R788 (fostamatinib disodium), an oral prodrug of the
selective Syk inhibitor R406, in nephrotoxic nephritis in Wistar-Kyoto rats.
Treatment with R788 reduced proteinuria, tissue injury, glomerular macrophage
and CD8+ cell numbers, and renal monocyte chemoattractant protein-1 (MCP-1) and
IL-1beta, even when we started treatment after the onset of glomerulonephritis.
When we administered R788 from days 4 to 10, glomerular crescents reduced by
100% (P < 0.01) compared with the vehicle group. When we administered R788
treatment from days 7 to 14, established glomerular crescents reversed (reduced
by 21%, P < 0.001), and renal function was better than the vehicle group (P <
0.001). In vitro, R406 downregulated MCP-1 production from mesangial cells and
macrophages stimulated with aggregated IgG. These results suggest that Syk is an
important therapeutic target for the treatment of glomerulonephritis. Certain maligt B cells rely on B-cell receptor (BCR)-mediated survival
signals. Spleen tyrosine kinase (Syk) initiates and amplifies the BCR signal. In
in vivo analyses of B-cell lymphoma cell lines and primary tumors, Syk
inhibition induces apoptosis. These data prompted a phase 1/2 clinical trial of
fostamatinib disodium, the first clinically available oral Syk inhibitor, in
patients with recurrent B-cell non-Hodgkin lymphoma (B-NHL). Dose-limiting
toxicity in the phase 1 portion was neutropenia, diarrhea, and thrombocytopenia,
and 200 mg twice daily was chosen for phase 2 testing. Sixty-eight patients with
recurrent B-NHL were then enrolled in 3 cohorts: (1) diffuse large B-cell
lymphoma (DLBCL), (2) follicular lymphoma (FL), and (3) other NHL, including
mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), mucosa-associated
lymphoid tissue lymphoma, lymphoplasmacytic lymphomas, and small lymphocytic
leukemia/chronic lymphocytic leukemia (SLL/CLL). Common toxicities included
diarrhea, fatigue, cytopenias, hypertension, and nausea. Objective response
rates were 22% (5 of 23) for DLBCL, 10% (2 of 21) for FL, 55% (6 of 11) for
SLL/CLL, and 11% (1/9) for MCL. Median progression-free survival was 4.2 months.
Disrupting BCR-induced signaling by inhibiting Syk represents a novel and active
therapeutic approach for NHL and SLL/CLL. This trial was registered at
www.clinicaltrials.gov as #NCT00446095. Reperfusion injury to tissue following an ischemic event occurs as a consequence
of an acute inflammatory response that can cause significant morbidity and
mortality. Components of both the innate (complement, immunoglobulin, monocytes,
and neutrophils) and adaptive (B and T lymphocytes) immune systems have been
demonstrated to mediate tissue injury. Spleen tyrosine kinase (Syk) is
responsible for membrane-mediated signaling in various cell types including B
lymphocytes, macrophages, and T cells. We investigated the ability of a small
drug Syk inhibitor, R788, to protect mice against mesenteric
ischemia-reperfusion (I/R)-induced local (intestine) and remote lung injury.
Mice were fed with chow containing a Syk inhibitor for 6 days before the
performance of intestinal I/R, which resulted in silencing of the expression of
the active phosphorylated Syk. Syk inhibition significantly suppressed both
local and remote lung injury. The beneficial effect was associated with reduced
IgM and complement 3 deposition in the tissues and significant reduction of
polymorphonuclear cell infiltration. Our data place Syk upstream of events
leading to the binding of natural antibodies to the ischemia-conditioned tissues
and urge the consideration of the use of Syk inhibitors in the prevention or
improvement of tissue injury of organs exposed to ischemia or hypoperfusion. In APCs, the protein tyrosine kinase Syk is required for signaling of several
immunoreceptors, including the BCR and FcR. We show that conditional ablation of
the syk gene in dendritic cells (DCs) abrogates FcgammaR-mediated cross priming
of diabetogenic T cells in RIP-mOVA mice, a situation phenocopied in wild-type
RIP-mOVA mice treated with the selective Syk inhibitor R788. In addition to
blocking FcgammaR-mediated events, R788 also blocked BCR-mediated Ag
presentation, thus broadly interrupting the humoral contributions to T
cell-driven autoimmunity. Indeed, oral administration of R788 significantly
delayed spontaneous diabetes onset in NOD mice and successfully delayed
progression of early-established diabetes even when treatment was initiated
after the development of glucose intolerance. At the DC level, R788 treatment
was associated with reduced insulin-specific CD8 priming and decreased DC
numbers. At the B cell level, R788 reduced total B cell numbers and total Ig
concentrations. Interestingly, R788 increased the number of IL-10-producing B
cells, thus inducing a tolerogenic B cell population with immunomodulatory
activity. Taken together, we show by genetic and pharmacologic approaches that
Syk in APCs is an attractive target in T cell-mediated autoimmune diseases such
as type 1 diabetes. Inhibition of antigen-dependent B-cell receptor (BCR) signaling is considered a
promising therapeutic approach in chronic lymphocytic leukemia (CLL), but
experimental in vivo evidence to support this view is still lacking. We have now
investigated whether inhibition of BCR signaling with the selective Syk
inhibitor fostamatinib disodium (R788) will affect the growth of the leukemias
that develop in the Eμ-TCL1 transgenic mouse model of CLL. Similarly to human
CLL, these leukemias express stereotyped BCRs that react with autoantigens
exposed on the surface of senescent or apoptotic cells, suggesting that they are
antigen driven. We show that R788 effectively inhibits BCR signaling in vivo,
resulting in reduced proliferation and survival of the maligt B cells and
significantly prolonged survival of the treated animals. The growth-inhibitory
effect of R788 occurs despite the relatively modest cytotoxic effect in vitro
and is independent of basal Syk activity, suggesting that R788 functions
primarily by inhibiting antigen-dependent BCR signals. Importantly, the effect
of R788 was found to be selective for the maligt clones, as no disturbance in
the production of normal B lymphocytes was observed. Collectively, these data
provide further rationale for clinical trials with R788 in CLL and establish the
BCR-signaling pathway as an important therapeutic target in this disease. BACKGROUND: Spleen tyrosine kinase (Syk) is an important modulator of immune
signaling. The objective of this phase 2 study was to evaluate the efficacy and
safety of R788, an oral inhibitor of Syk, in patients with active rheumatoid
arthritis despite methotrexate therapy.
METHODS: We enrolled 457 patients who had active rheumatoid arthritis despite
long-term methotrexate therapy in a 6-month, double-blind, placebo-controlled
trial. The primary outcome was the American College of Rheumatology (ACR) 20
response (which indicates at least a 20% reduction in the number of both tender
and swollen joints and improvement in at least three of five other criteria) at
month 6.
RESULTS: R788, at a dose of 100 mg twice daily and at a dose of 150 mg once
daily, was significantly superior to placebo at month 6 (ACR 20 response rates
of 67% and 57%, respectively, vs. 35%; P<0.001 for the comparison of both doses
with placebo). It was also significantly superior with respect to ACR 50, which
indicates at least a 50% improvement (43% and 32% vs. 19%; P<0.001 for the
comparison of the 100-mg dose with placebo, P=0.007 for the comparison of the
150-mg dose with placebo) and ACR 70 (28% and 14% vs. 10%; P<0.001 for the
comparison of the 100-mg dose with placebo, P=0.34 for the comparison of the
150-mg dose with placebo). A clinically significant effect was noted by the end
of the first week of treatment. Adverse effects included diarrhea (in 19% of
subjects taking the 100-mg dose of R788 vs. 3% of those taking placebo), upper
respiratory infections (14% vs. 7%), and neutropenia (6% vs. 1%). R788 was
associated with an increase in systolic blood pressure of approximately 3 mm Hg
between baseline and month 1, as compared with a decrease of 2 mm Hg with
placebo; 23% of the patients taking R788 vs. 7% of the patients receiving
placebo required the initiation of or a change in antihypertensive therapy.
CONCLUSIONS: In this phase 2 study, a Syk inhibitor reduced disease activity in
patients with rheumatoid arthritis; adverse events included diarrhea,
hypertension, and neutropenia. Additional studies will be needed to further
assess the safety and efficacy of Syk-inhibition therapy in patients with
rheumatoid arthritis. (Funded by Rigel; ClinicalTrials.gov number, NCT00665925.) Current research in lymphoma is focused on two areas of lymphoma biology-the
signal transduction pathways used to maintain the growth of maligt
lymphocytes and the role of the tumor microenvironment in lymphoma growth and
survival. This review focuses on three signaling pathways: the
phosphatidylinositol 3-kinase/mammalian target of rapamycin (PI3K/mTOR) pathway,
the B-cell receptor/spleen tyrosine kinase (BCR/Syk) pathway, and the protein
kinase C-beta (PKC-β) pathway, known to be important to lymphoma cells. The mTOR
inhibitors temsirolimus and everolimus have demonstrated antitumor activity in
all types of lymphoma, the Syk inhibitor fostamatinib has activity in diffuse
large B-cell lymphoma and chronic lymphocytic leukemia, and the PKC-β inhibitor
enzastaurin is being used as consolidation therapy after remission in diffuse
large B-cell lymphoma. This review discusses the biology behind the development
of each new agent and the results of initial clinical trials. The goal is to
provide the hematologist/oncologist background information on these new agents
and understand their current and potential role in the management of patients. OBJECTIVE: To assess the efficacy and safety of R788 (fostamatinib disodium), an
inhibitor of spleen tyrosine kinase (Syk), in patients with active rheumatoid
arthritis (RA) that did not respond to biologic therapies.
METHODS: A total of 219 patients with active RA in whom treatment with biologic
agents had failed were enrolled in a 3-month multicenter, randomized,
double-blind, placebo-controlled trial of R788. The primary end point was the
percentage of patients who met the American College of Rheumatology 20%
improvement criteria (achieved an ACR20 response) at month 3. Secondary end
points included changes in inflammation and damage, as assessed by magnetic
resoce imaging (MRI), and changes in the Disease Activity Score.
RESULTS: The ACR20 response in the R788 100 mg twice daily group was 38%, versus
37% in the placebo group, at month 3. No significant differences were achieved
in the ACR20, ACR50, or ACR70 response levels at 3 months. There were
differences between the groups from baseline to month 3 in the secondary end
points C-reactive protein (CRP) level and synovitis score on MRI. There were
baseline differences in steroid use, prior biologic use, and synovitis score on
MRI between the R788 group and the placebo group that may have affected the
outcomes. A high placebo response rate was seen in this trial, and exploratory
analysis suggested that this may in part have been driven by patients who
entered the trial with an elevated erythrocyte sedimentation rate but normal CRP
level.
CONCLUSION: Our findings indicate that there were no differences in the primary
end point between the R788 and placebo groups. Differences were observed between
the R788 and placebo groups in secondary end points, particularly in those
patients who entered the study with an elevated CRP level. In patients with active rheumatoid arthritis despite therapy with DMARDS,
treatment with a spleen tyrosine kinase inhibitor has achieved similar response
rates to those achieved in clinical trials of other drugs, including biologic
agents. Where might these agents fit in the current armamentarium against this
disease? BACKGROUND: Mantle cell lymphoma (MCL) is currently an incurable entity, and new
therapeutic approaches are needed. We have applied a high-throughput
phospho-proteomic technique to MCL cell lines to identify activated pathways and
we have then validated our data in both cell lines and tumor tissues.
METHODS: PhosphoScan analysis was performed on MCL cell lines. Results were
validated by flow cytometry and western blotting. Functional validation was
performed by blocking the most active pathway in MCL cell lines.
RESULTS: PhosphoScan identified more than 300 tyrosine-phosporylated proteins,
among which many protein kinases. The most abundant peptides belonged to
proteins connected with B-cell receptor (BCR) signaling. Active BCR signaling
was demonstrated by flow cytometry in MCL cells and by western blotting in MCL
tumor tissues. Blocking BCR signaling by Syk inhibitor piceatannol induced
dose/time-dependent apoptosis in MCL cell lines, as well as several
modifications in the phosphorylation status of BCR pathway members and a
collapse of cyclin D1 protein levels.
CONCLUSION: Our data support a pro-survival role of BCR signaling in MCL and
suggest that this pathway might be a candidate for therapy. Our findings also
suggest that Syk activation patterns might be different in MCL compared to other
lymphoma subtypes. INTRODUCTION: The B-cell receptor (BCR) delivers antigen-dependent and
-independent signals that have been implicated in the pathogenesis of several
common B-cell maligcies. Agents that can efficiently block BCR signaling have
recently been developed and are currently being evaluated as novel targeted
therapies. Among these, agents that inhibit the Syk kinase appear particularly
promising in preclinical and early clinical studies.
AREAS COVERED: The manuscript provides an overview of recent findings that
implicate Syk and the BCR signaling pathway in the pathogenesis of several
common lymphoid maligcies. It outlines preclinical and early clinical
experiences with the Syk inhibitor fostamatinib disodium (R788) and discusses
various options for further clinical development of this compound.
EXPERT OPINION: Inhibitors of Syk or other components of the BCR signaling
pathway are emerging as an exciting novel class of agents for the treatment of
common B-cell maligcies. Future efforts should focus on defining the disease
entities that are most likely to benefit from these agents, although
considerable evidence is already available to pursue such studies in patients
with chronic lymphocytic leukemia. Combinations with chemo-immunotherapy,
treatment of early-stage disease and consolidation therapy should all be
explored and could lead to the development of novel therapeutic approaches with
improved efficacy, tolerability and toxicity profiles. OBJECTIVE: Spleen tyrosine kinase (SYK) has come into focus as a potential
therapeutic target in chronic inflammatory diseases, such as rheumatoid
arthritis and asthma, as well as in B-cell lymphomas. SYK has also been involved
in the signaling of immunoreceptors, cytokine receptors, and integrins. We
therefore hypothesized that inhibition of SYK attenuates the inflammatory
process underlying atherosclerosis and reduces plaque development.
METHODS AND RESULTS: Low-density lipoprotein receptor-deficient mice consuming a
high-cholesterol diet supplemented with 2 doses of the orally available SYK
inhibitor fostamatinib for 16 weeks showed a dose-dependent reduction in
atherosclerotic lesion size by up to 59±6% compared with the respective
controls. Lesions of fostamatinib-treated animals contained fewer macrophages
but more smooth muscle cells and collagen-characteristics associated with more
stable plaques in humans. Mechanistically, fostamatinib attenuated adhesion and
migration of inflammatory cells and limited macrophage survival. Furthermore,
fostamatinib normalized high-cholesterol diet -induced monocytosis and
inflammatory gene expression.
CONCLUSIONS: We present the novel finding that the SYK inhibitor fostamatinib
attenuates atherogenesis in mice. Our data identify SYK inhibition as a
potentially fruitful antiinflammatory therapeutic strategy in atherosclerosis. Spleen tyrosine kinase (Syk) is a cytoplasmic tyrosine kinase involved in
signalling in many of the cells that drive immune inflammation. The development
of small molecules that inhibit Syk kinase may change the way we treat disorders
such as rheumatoid arthritis (RA), as well as a range of other inflammatory
diseases. Fostamatinib (R-788) is an orally bioavailable small molecule. It is
the prodrug of R406, which is a potent Syk inhibitor. Fostamatinib was developed
because it has more favourable physiochemical properties. It is rapidly
converted to R406 by intestinal enterocytes. It has been evaluated in
experimental models of RA, such as collagen-induced arthritis. In these models,
fostamatinib suppressed clinical arthritis, bone erosions, pannus formation and
synovitis. A phase II programme with fostamatinib has largely been completed.
Three key trials have been published, lasting 12-26 weeks and each enrolling
189-457 patients (875 in total). All these trials involved placebo therapy and
patients continued to receive methotrexate in addition to active treatment with
fostamatinib. The first dose-ranging trial evaluated three treatment doses in RA
patients who had not fully responded to methotrexate therapy. The second trial
compared two treatment doses in patients who had not responded to methotrexate
therapy. The third trial compared a single treatment dose with placebo in
patients who had not responded to biological therapy. The primary outcome
measure was the number of patients achieving American College of Rheumatology
(ACR) 20% (ACR20) responses. Placebo ACR20 response rates in all three trials
were similar (35-38%). All three trials involved one treatment arm receiving
fostamatinib 100 mg twice daily; ACR20 responses with this active treatment
ranged from 38% to 67%. A meta-analysis of ACR responses in these trials, using
responses to the highest dose in each trial for comparisons with placebo therapy
in a random effects model, showed a borderline benefit with ACR20 responses.
There were more significant differences with ACR50 and ACR70 responses. The
reason that this meta-analysis was not more strongly positive is that the third
trial, which evaluated patients who had failed to respond to biological
treatments, gave negative results. Individual ACR response components, such as
changes in swollen joint counts, showed significant differences in the first two
trials, but there were no definite treatment benefits in the third trial.
Overall, the differences were significant in a meta-analysis of all three
trials. The most important adverse reactions were diarrhoea, neutropenia and
raised ALT levels, which all showed significant excesses with active treatment
compared with placebo. Too few patients have been studied for a definitive
safety profile to be known. Overall, the results of the phase II trials were
sufficiently encouraging for a phase III programme to be initiated. It will be
some years before their definitive results are available. Three major advances over the last decade have impacted the way we treat
rheumatoid arthritis; early and aggressive treatment, use of disease activity
measures leading to treat to target, and availability of biologic agents. No
oral biologic agents are available at this time but promising data is emerging
for two drugs, tofacitinib and fostamatinib, inhibitors of JAK and Syk kinases,
respectively. This paper will review some of the relevant published data for
these agents and discuss where they may be placed in our treatment options for
RA. While target-based small-molecule discovery has taken centre-stage in the
pharmaceutical industry, there are many cancer-promoting proteins not easily
addressed with a traditional target-based screening approach. In order to
address this problem, as well as to identify modulators of biological states in
the absence of knowing the protein target of the state switch, alternative
phenotypic screening approaches, such as gene expression-based and high-content
imaging, have been developed. With this renewed interest in phenotypic
screening, however, comes the challenge of identifying the binding protein
target(s) of small-molecule hits. Emerging technologies have the potential to
improve the process of target identification. In this review, we discuss the
application of genomic (gene expression-based), genetic (short hairpin RNA and
open reading frame screening), and proteomic approaches to protein target
identification. Cell signaling initiated by the B cell receptor is critical to normal
development of B lymphocytes, most notably at the transitional B cell stage.
Inhibition of this signaling pathway with the syk inhibitor, fostamatinib, has
produced significant efficacy in lymphoid maligcies and autoimmune
conditions. Here, we demonstrate that short-term use of fostamatinib impairs B
lymphocyte development at the transitional stage without affecting mature B cell
populations. Additionally, IL-10 producing B cells remained relatively constant
throughout the treatment period. These findings provide insight into the
mechanism of action of B cell receptor inhibition in autoimmune disease. As the
development of agents targeting B cell receptor signaling proceeds, monitoring
for long-term consequences as well as functional evaluation of B cell subsets
may further improve our understanding of this rapidly growing class of novel
agents. Acute graft-versus-host disease (GvHD) limits the applicability of allogeneic
hematopoietic cell transplantation for the treatment of leukemia. GvHD occurs as
a consequence of multiple activating events in antigen-presenting cells (APCs)
and T cells (Tcs). Spleen tyrosine kinase (Syk) is an intracellular non-receptor
tyrosine kinase involved in multiple signaling events of immune cells.
Therefore, we hypothesized that Syk may be a promising target to inhibit GvHD,
which involves activation of different immune cell populations. In vivo
expansion of luciferase(+) donor Tcs in mice developing GvHD was reduced by
treatment with the Syk inhibitor Fostamatinib, which led to increased survival
and reduced histologically confirmed GvHD severity. Importantly, in vivo and in
vitro cytotoxicity against leukemia target cells and anti-murine cytomegalovirus
immune responses were not impacted by Fostamatinib. In APCs Syk inhibition
reduced the expression of costimulatory molecules and disrupted cytoskeletal
organization with consecutive APC migratory defects in vitro and in vivo while
phagocytic activity remained intact. On the basis of these immunomodulatory
effects on different cell populations, we conclude that Syk targeting in
alloantigen-activated Tcs and APCs with pharmacologic inhibitors, already
applied successfully in anti-lymphoma therapy, has clinical potential to reduce
GvHD, especially as anti-leukemia and anti-viral immunity were preserved. PURPOSE OF REVIEW: Since the introduction of biologic therapies into the
treatment paradigm of rheumatoid arthritis (RA), there has been hope that oral
small molecule immune modulators would be developed that would have a
risk : benefit profile at least similar to biologic therapies, be more
convenient for the patient and, hopefully, be less expensive. This article
reviews the progress made in the development of these compounds over the past
year.
RECENT FINDINGS: Additional information has become available in the past year on
five oral compounds including kinase inhibitors (tofacitinib, fostamatinib,
VX-509), an S1P lyase inhibitor (LX 3305) and a chemokine receptor-1 antagonist
(CCX354-C). Efficacy has been shown in phase III with tofacitinib and in phase
II with fostamatinib and VX-509; safety was the primary endpoint of the trials
of CCX354-C and LX3305. Regarding side effects, liver test elevation and
neutropenia occurred with tofacitinib, VX-509 and fostamatinib; lipid elevation
with tofacitinib and VX-509; creatinine elevation and anemia with tofacitinib,
and hypertension and diarrhea with fostamatinib.
SUMMARY: Compounds that inhibit tyrosine kinase pathways involved in cellular
signalling have been shown to be effective in the treatment of RA with a
reasonable risk : benefit ratio. It is too early to tell about inhibitors of
other pathways. Syk is a protein tyrosine kinase that couples B-cell receptor (BCR) activation
with downstream signaling pathways, affecting cell survival and proliferation.
Moreover, Syk is involved in BCR-independent functions, such as B-cell migration
and adhesion. In chronic lymphocytic leukemia (CLL), Syk becomes activated by
external signals from the tissue microenvironment, and was targeted in a first
clinical trial with R788 (fostamatinib), a relatively nonspecific Syk inhibitor.
Here, we characterize the activity of two novel, highly selective Syk
inhibitors, PRT318 and P505-15, in assays that model CLL interactions with the
microenvironment. PRT318 and P505-15 effectively antagonize CLL cell survival
after BCR triggering and in nurse-like cell-co-cultures. Moreover, they inhibit
BCR-dependent secretion of the chemokines CCL3 and CCL4 by CLL cells, and
leukemia cell migration toward the tissue homing chemokines CXCL12, CXCL13, and
beneath stromal cells. PRT318 and P505-15 furthermore inhibit Syk and
extracellular signal-regulated kinase phosphorylation after BCR triggering.
These findings demonstrate that the selective Syk inhibitors PRT318 and P505-15
are highly effective for inhibition of CLL survival and tissue homing circuits,
and support the therapeutic development of these agents in patients with CLL,
other B-cell maligcies and autoimmune disorders. Registries estimate that one third of patients with psoriatic arthritis (PsA)
are "resistant" to of TNF-alpha blockers. Therefore, the search for new
approaches to treatment of this disease may be justified. Currently the
treatment options that have proven effective are associated with inhibition of
the T cell costimulatory pathway (abatacept and alefacept) and blocking the P40
fraction of IL-12 and IL-23 (ustekinumab). A novel pathway inhibition, which
deserves special attention is offered by apremilast. This molecule inhibits
phosphodiesterase IV, responsible for hydrolyzing cyclic adenosine monophosphate
to adenosine monophosphate, which causes an increase in cAMP. This metabolite is
associated with decreased TNF-alpha. It has a modest efficacy (ACR 20 response
of 43%), and subsequent studies have shown an improvement in visual analog scale
and the SF36 compared to placebo. Currently there are five clinical trials in
phase III to assess its effectiveness in parameters of inflammation and
radiographic progression. The spectrum of possibilities before treatment failure
with anti-TNF alpha, is augmented by the appearance of several reports that show
efficacy with the individual use of CD20 inhibitors and IL-1. In patients with
rheumatoid arthritis (RA) the effectiveness of molecules that inhibit signal
transduction of cytokines (Anti-JAK) has been proven, so it is possible that in
the future they may be used in patients with PsA. Tissue injury following ischemia-reperfusion (I/R) occurs as a consequence of
actions of soluble factors and immune cells. Growing evidence supports a role
for platelets in the manifestation of tissue damage following I/R. Spleen
tyrosine kinase has been well documented to be important in lymphocyte
activation and more recently in platelet activation. We performed experiments to
evaluate whether inhibition of platelet activation through inhibition of spleen
tyrosine kinase prevents tissue damage after mesenteric I/R injury. Platelets
isolated from C57BL/6J mice fed with R788 for 10 days were transfused into
C57BL/6J mice depleted of platelets 2 days before mesenteric I/R injury.
Platelet-depleted mice transfused with platelets from R788-treated mice before
mesenteric I/R displayed a significant reduction in the degree of remote lung
damage, but with little change in the degree of local intestinal damage compared
with control I/R mice. Transfusion of R788-treated platelets also decreased
platelet sequestration, C3 deposition, and immunoglobulin deposition in lung,
but not in the intestine, compared with control groups. These findings
demonstrate that platelet activation is a requisite for sequestration in the
pulmonary vasculature to mediate remote tissue injury after mesenteric I/R. The
use of small-molecule inhibitors may be valuable to prevent tissue damage in
remote organs following I/R injury. INTRODUCTION: In the last few years, several tyrosine kinase inhibitors (TKIs)
have been synthesized and become available for preclinical studies and clinical
trials. This article summarizes recent achievements in the mechanism of action,
pharmacological properties, and clinical activity and toxicity, as well as the
emerging role of TKIs in lymphoid maligcies, allergic diseases, and
autoimmune disorders.
AREAS COVERED: A literature review was conducted of the MEDLINE database PubMed
for articles in English. Publications from 2000 through January 2012 were
scrutinized. The search terms used were Bruton's tyrosine kinase (Btk)
inhibitors, PCI-32765, GDC-0834, LFM-A13, AVL-101, AVL-292, spleen tyrosine
kinase (Syk) inhibitors, R343, R406, R112, R788, fostamatinib, BAY-61-3606,
C-61, piceatannol, Lyn, imatinib, nilotinib, bafetinib, dasatinib, GDC-0834,
PP2, SU6656 in conjunction with lymphoid maligcy, NHL, CLL, autoimmune
disease, allergic disease, asthma, and rheumatoid arthritis. Conference
proceedings from the previous 5 years of the American Society of Hematology,
European Hematology Association, American Society of Clinical Oncology, and
ACR/ARHP Annual Scientific Meetings were searched manually. Additional relevant
publications were obtained by reviewing the references from the chosen articles.
EXPERT OPINION: The use of TKIs, especially inhibitors of Btk, Syk, and Lyn, is
a promising new strategy for targeted treatment of B-cell lymphoid maligcies,
autoimmune disorders and allergic diseases. However, definitive data from
ongoing and future clinical trials will aid in better defining the status of
TKIs in the treatment of these disorders. Protein kinases (PKs) and lipid kinases (LKs) are good choices for targets of
signal transduction therapy as these enzymes are involved in signaling pathways,
and are often related to the pathogenesis of lymphoid maligcies. The
attractiveness of PKs and LKs as drug able targets is enhanced by the fact that
they are enzymes whose biological activity can be turned off by drugs that block
their catalytic site. In the last few years small molecular kinase inhibitors
(KIs) have been synthesized and become available for preclinical studies and
clinical trials. The first KI, introduced into clinical practice in 1998, was
imatinib mesylate, which became the first choice drug in chronic myeloid
leukemia. More recently, several KIs have been developed to target the proximal
B-cell receptor (BCR) signaling pathway including spleen tyrosine kinase
inhibitor (Fostamatinib) and Bruton's tyrosine kinase inhibitors (Ibrutinib,
AVL-263). These agents are currently evaluated in early clinical trials in
chronic lymphocytic leukemia (CLL) and other diseases. Cyclin-dependent kinase
(Cdk) inhibitors, flavopiridol (alvocidib), BMS-387032 (SNS-032), sunitinib and
sorafenib are currently under evaluation in clinical trials for
relapsed/refractory CLL. Multi-tyrosine kinase inhibitors including vandetanib
(ZD6474) bosutinib (SKI-606), TKI258 (CHIR-258), pazopanib (GW786034) and
axitinib (AG013736) have been also developed for the treatment of lymphoid
maligcies. Phosphatidylinositol 3-kinases (PI3K ) are a family of lipid
kinases that mediate signals from cell surface receptors. CAL-101 (GS-1101) is
an oral PI3Kδ-specific inhibitor which has shown preclinical and clinical
activity against CLL. This article summarizes recent achievements in the
mechanism of action, pharmacological properties and clinical activity and
toxicity of PK and LK inhibitors in CLL. Chronic lymphocytic leukemia (CLL) is a maligcy of mature B cells that depend
on host factors in the tissue microenvironment for survival and proliferation.
In vitro, CLL cells rapidly undergo apoptosis unless microenvironmental factors
are provided that support their survival. Signaling pathways activated in the
microenvironment in vivo include the B-cell receptor (BCR) and NF-κB pathways.
Thus, CLL is a disease "addicted to the host" and is dependent on pathways that
promote normal B-cell development, expansion, and survival; this is particularly
true in the case of the BCR signaling cascade. Small-molecule inhibitors of
kinases that are essential for BCR signal transduction abrogate the stimulating
effects of the microenvironment on CLL cells. The orally administered tyrosine
kinase inhibitors fostamatinib and ibrutinib and the phosphatidylinositol
3-kinase inhibitor GS-1101 have induced impressive responses in relapsed and
refractory CLL patients, mostly with moderate side effects. Reductions in
lymphadenopathy and splenomegaly are seen within weeks and are frequently
accompanied by a transient rise in absolute lymphocyte count that is
asymptomatic and probably the result of changes in CLL cell trafficking. This
review discusses the biologic basis for kinase inhibitors as targeted therapy of
CLL and summarizes the exciting early clinical experience with these agents. Fostamatinib (R788) is a prodrug rapidly converted to its active metabolite on
oral administration. This (known as R406) is a potent inhibitor of spleen
tyrosine kinase, required for the expression of a number of proinflammatory
cytokines. Fostamatinib has shown significantly superior efficacy (when compared
with placebo) in the control of patients with rheumatoid arthritis not
responding to methotrexate in Phase II clinical trials. Treatment emergent
adverse events with a higher frequency than in those on placebo included
diarrhea, hypertension, urinary tract infections, neutropenia and elevated
transaminases. The studied doses have shown a linear pharmacokinetic pattern and
the administration of methotrexate does not affect it. Fostamatinib may have a
role in the therapy of patients with rheumatoid arthritis with poor response to
conventional therapy. If these results are confirmed once Phase III studies are
completed, it may find a place in the evolving treatment algorithm for
rheumatoid arthritis. Genetic factors play an important role in determining the risk of multiple
sclerosis (MS). The strongest genetic association in MS is located within the
major histocompatibility complex class II region (MHC), but more than 50 MS loci
of modest effect located outside the MHC have now been identified. However, the
relative candidate genes that underlie these associations and their functions
are largely unknown. We conducted a protein-protein interaction (PPI) analysis
of gene products coded in loci recently reported to be MS associated at the
genome-wide significance level and in loci suggestive of MS association. Our aim
was to identify which suggestive regions are more likely to be truly associated,
which genes are mostly implicated in the PPI network and their expression
profile. From three recent independent association studies, SNPs were considered
and divided into significant and suggestive depending on the strength of the
statistical association. Using the Disease Association Protein-Protein Link
Evaluator tool we found that direct interactions among genetic products were
significantly higher than expected by chance when considering both significant
regions alone (p<0.0002) and significant plus suggestive (p<0.007). The number
of genes involved in the network was 43. Of these, 23 were located within
suggestive regions and many of them directly interacted with proteins coded
within significant regions. These included genes such as SYK, IL-6, CSF2RB,
FCLR3, EIF4EBP2 and CHST12. Using the gene portal BioGPS, we tested the
expression of these genes in 24 different tissues and found the highest values
among immune-related cells as compared to non-immune tissues (p<0.001). A gene
ontology analysis confirmed the immune-related functions of these genes. In
conclusion, loci currently suggestive of MS association interact with and have
similar expression profiles and function as those significantly associated,
highlighting the fact that more common variants remain to be found to be
associated to MS. Chemokines and their ligands play a critical role in enabling chronic
lymphocytic leukaemia (CLL) cells access to protective microenvironmental niches
within tissues, ultimately resulting in chemoresistance and relapse: disruption
of these signaling pathways has become a novel therapeutic approach in CLL. The
tyrosine kinase inhibitor dasatinib inhibits migration of several cell lines
from solid-organ tumours, but effects on CLL cells have not been reported. We
studied the effect of clinically achievable concentrations of dasatinib on
signaling induced by the chemokine CXCL12 through its' receptor CXCR4, which is
highly expressed on CLL cells. Dasatinib pre-treatment inhibited Akt and ERK
phosphorylation in CLL cells upon stimulation with CXCL12. Dasatinib also
significantly diminished the rapid increase in actin polymerisation observed in
CLL cells following CXCL12 stimulation. Moreover, the drug significantly
inhibited chemotaxis in a transwell assay, and reduced the percentage of cells
able to migrate beneath a CXCL12-expressing murine stromal cell line. Dasatinib
also abrogated the anti-apoptotic effect of prolonged CXCL12 stimulation on
cultured CLL cells. These data suggest that dasatinib, akin to other small
molecule kinase inhibitors targeting the B-cell receptor signaling pathway, may
redistribute CLL cells from protective tissue niches to the peripheral blood,
and support the investigation of dasatinib in combination strategies. A novel approach to design selective spleen tyrosine kinase (Syk) inhibitors is
described. Inhibition of spleen tyrosine kinase has attracted much attention as
a mechanism for the treatment of autoimmune diseases such as asthma, rheumatoid
arthritis, and SLE. Fostamatinib, a Syk inhibitor that successfully completed
phase II clinical trials, also exhibits some undesirable side effects. More
selective Syk inhibitors could offer safer, alternative treatments. Through a
systematic evaluation of the kinome, we identified Pro455 and Asn457 in the Syk
ATP binding site as a rare combination among sequence aligned kinases and
hypothesized that optimizing the interaction between them and a Syk inhibitor
molecule would impart high selectivity for Syk over other kinases. We report the
structure-guided identification of three series of selective spleen tyrosine
kinase inhibitors that support our hypothesis and offer useful guidance to other
researchers in the field. Chronic lymphocytic leukemia (CLL) is a maligcy of mature B cells that depend
on host factors in the tissue microenvironment for survival and proliferation.
In vitro, CLL cells rapidly undergo apoptosis unless microenvironmental factors
are provided that support their survival. Signaling pathways activated in the
microenvironment in vivo include the B-cell receptor (BCR) and NF-κB pathways.
Thus, CLL is a disease "addicted to the host" and is dependent on pathways that
promote normal B-cell development, expansion, and survival; this is particularly
true in the case of the BCR signaling cascade. Small-molecule inhibitors of
kinases that are essential for BCR signal transduction abrogate the stimulating
effects of the microenvironment on CLL cells. The orally administered tyrosine
kinase inhibitors fostamatinib and ibrutinib and the phosphatidylinositol
3-kinase inhibitor GS-1101 have induced impressive responses in relapsed and
refractory CLL patients, mostly with moderate side effects. Reductions in
lymphadenopathy and splenomegaly are seen within weeks and are frequently
accompanied by a transient rise in absolute lymphocyte count that is
asymptomatic and probably the result of changes in CLL cell trafficking. This
review discusses the biologic basis for kinase inhibitors as targeted therapy of
CLL and summarizes the exciting early clinical experience with these agents. The clearest evidence that B cells play an important role in human autoimmunity
is that immunotherapies that deplete B cells are very effective treatments for
many autoimmune diseases. All people, healthy or ill, have autoreactive B cells,
but not at the same frequency. A number of genes influence the level of these
autoreactive B cells and whether they are eliminated or not during development
at a central checkpoint in the bone marrow (BM) or at a later checkpoint in
peripheral lymphoid tissues. These genes include those encoding proteins that
regulate signaling through the B-cell receptor complex such as Btk and PTPN22,
proteins that regulate innate signaling via Toll-like receptors (TLRs) such as
MyD88 and interleukin-1 receptor-associated kinase 4, as well as the gene
encoding the activation-induced deaminase (AID) essential for B cells to undergo
class switch recombination and somatic hypermutation. Recent studies have
revealed that TLR signaling elements and AID function not only in peripheral B
cells to help mediate effective antibody responses to foreign antigens, but also
in the BM to help remove autoreactive B-lineage cells at a very early point in
B-cell development. Newly arising B cells that leave the BM and enter the blood
and splenic red pulp can express both AID and TLR signaling elements like TLR7,
and thus are fully equipped to respond rapidly to antigens (including
autoantigens), to isotype class switch, and to undergo somatic hypermutation.
These red pulp B cells may thus be an important source of autoantibody-producing
cells arising particularly in extrafollicular sites, and indeed may be as
significant a source of autoantibody-producing cells as B cells arising from
germinal centers. OBJECTIVE: To assess the influence of fostamatinib on patient-reported outcomes
(PRO) in patients with active rheumatoid arthritis and an inadequate response to
methotrexate (MTX).
METHODS: Patients taking background MTX (N = 457) were enrolled in a phase II
clinical trial (NCT00665925) and randomized equally to placebo, fostamatinib 100
mg twice daily (bid), or fostamatinib 150 mg once daily (qd) for 24 weeks.
Self-administered PRO measures included pain, patient's global assessment (PtGA)
of disease activity, physical function, health-related quality of life (HRQOL),
and fatigue. Mean change from baseline and a responder analysis of the
proportion of patients achieving a minimal clinically important difference were
determined.
RESULTS: At Week 24, there were statistically significant improvements in pain,
PtGA, physical function, fatigue, and the physical component summary of the
Medical Outcomes Study Short Form-36 (SF-36) for fostamatinib 100 mg bid
compared with placebo. Mean (standard error) changes from baseline in the
fostamatinib 100 mg bid group versus the placebo group were -31.3 (2.45) versus
-17.8 (2.45), p < 0.001 for pain; -29.1 (2.26) versus -16.7 (2.42), p < 0.001
for PtGA; -0.647 (0.064) versus -0.343 (0.062), p < 0.001 for physical function;
7.40 (1.00) versus 4.50 (0.94), p < 0.05 for fatigue; 8.52 (0.77) versus 4.90
(0.78), p < 0.01 for SF-36 physical component score; and 3.99 (0.93) versus 3.71
(0.99), p = 0.83 for SF-36 mental component score. Patients receiving
fostamatinib 150 mg qd showed improvements in some PRO, including physical
function.
CONCLUSION: Patients treated with fostamatinib 100 mg bid showed significant
improvements in HRQOL outcomes. Posttransplant lymphoproliferative disorder (PTLD)-associated Epstein-Barr virus
(EBV)+ B cell lymphomas are serious complications of solid organ and bone marrow
transplantation. The EBV protein LMP2a, a B cell receptor (BCR) mimic, provides
survival signals to virally infected cells through Syk tyrosine kinase.
Therefore, we explored whether Syk inhibition is a viable therapeutic strategy
for EBV-associated PTLD. We have shown that R406, the active metabolite of the
Syk inhibitor fostamatinib, induces apoptosis and cell cycle arrest while
decreasing downstream phosphatidylinositol-3'-kinase (PI3K)/Akt signaling in
EBV+ B cell lymphoma PTLD lines in vitro. However, Syk inhibition did not
inhibit or delay the in vivo growth of solid tumors established from
EBV-infected B cell lines. Instead, we observed tumor growth in adjacent
inguinal lymph nodes exclusively in fostamatinib-treated animals. In contrast,
direct inhibition of PI3K/Akt significantly reduced tumor burden in a xenogeneic
mouse model of PTLD without evidence of tumor growth in adjacent inguinal lymph
nodes. Taken together, our data indicate that Syk activates PI3K/Akt signaling
which is required for survival of EBV+ B cell lymphomas. PI3K/Akt signaling may
be a promising therapeutic target for PTLD, and other EBV-associated
maligcies. After two decades of research and development activity focussed on orally active
kinase inhibitors, the first such drug (the JAK inhibitor Xeljanz, tofacitinib)
was approved by the FDA in November 2012 for the treatment of rheumatoid
arthritis (RA). There is an intense activity in many companies both on expanding
the utility of JAK inhibitors in other auto-immune indications and in
discovering inhibitors of the JAK family with different and more selective
profiles. Progress is also being made with orally active Syk inhibitors. One
such inhibitor (fostamatinib) is currently in large-scale phase 3 trials, and
there are others in clinical development. The last two to three years have been
transformative for kinase inhibitors in auto-immune diseases, as several
inhibitors have finally progressed beyond phase 2 trials after so many failures
on other targets. Thus, there are new treatment options for RA patients beyond
existing oral DMARDs and parenteral biologics. Normal B lymphocytes receive signals from B-cell antigen receptor (BCR) that are
triggered by binding of the BCR to an external antigen. Tonic signaling through
the BCR provides growth and signals to chronic lymphocytic leukemia (CLL) cells,
and plays an important role in the pathogenesis and progression of the disease.
Antigen engagement of BCR is followed by intracellular recruitment and
activation of BCR-associated kinases including spleen tyrosine kinase (Syk),
Bruton's tyrosine kinase (Btk) and phosphatidylinositol 3-kinases (PI3K).
Inhibition of signaling pathways downstream of the BCR induces disruption of
chemokine-mediated CLL cell migration and cell killing. BCR signal transduction
inhibitors represent a promising new strategy for targeted CLL treatment. A
number of therapeutic agents have recently been developed with significant
activity in CLL. The compounds that are currently investigated in patients with
CLL include ibrutinib -inhibitor of Btk, fostamatinib-inhibitor of Syk and
idelalisib (GS-1101) -a specific isoform of the PI3K (PI3K) inhibitor. The
clinical activity of ibrutinib, GS-1101 and fostamatinib in patients with CLL is
associated with marked lymphocytosis due to release of tumor cells from the
lymph nodes into the peripheral blood. Further studies are ongoing with single
agents and their combinations with other targeted and conventional therapies.
This article will review the preclinical rationale of BCR signaling inhibitors
in the treatment of CLL, and the clinical evidence supporting the use of these
agents in CLL patients. Conventional immunosuppressive therapies have radically transformed patient
survival in systemic lupus erythematosus (SLE), but their use is associated with
considerable toxicity and a substantial proportion of patients remain refractory
to treatment. A more comprehensive understanding of the complexity of SLE
immunopathogenesis has evolved over the past decade and has led to the testing
of several biologic agents in clinical trials. There is a clear need for new
therapeutic agents that overcome these issues, and biologic agents offer
exciting prospects as future SLE therapies.An array of promising new therapies
are currently emerging or are under development including B-cell depletion
therapies, agents targeting B-cell survival factors, blockade of T-cell
co-stimulation and anti-cytokine therapies, such as monoclonal antibodies
against interleukin-6 and interferon-α. The pathogenesis of RA is a complex and ever-changing landscape but amid the
chaos of the disease process we have found effective treatment regimes. However,
our current therapeutics, although targeting various components of both the
innate and adaptive immune response, do not result in disease remission. Protein
kinase inhibitors are attractive targets due to their ability to influence
downstream signalling and their oral bioavailability. Fostamatinib (R788)
inhibits spleen tyrosine kinase (Syk) and has been in clinical trials involving
both MTX inadequate responders (MTX-IRs) and biologic inadequate responders.
Studies on the MTX-IR population revealed ACR20 responses of 67-72% at higher
doses (150 mg bd and 100 mg bd), ACR50 responses of 43-57% and ACR70 responses
of 28-40%. The trial in the biologic non-responder population showed no
efficacy, however, post hoc analyses of the data suggested that a further trial
in this population is warranted. The most common adverse events included
gastrointestinal effects, hypertension, neutropenia and transaminitis. Many
adverse effects were dose responsive and hypertension was amenable to treatment.
Upper respiratory tract infections were more likely at higher doses, but no
serious infections with tuberculosis, fungi or opportunistic infections were
reported. The oral availability of these agents makes them attractive treatment
options for our patients, although the literature from the oncology field
suggests that patients will only choose the oral route if efficacy is
equivalent. Long-term follow-up studies are ongoing and will be critical for
rare side effects. The role of these agents in our current arsenal is unclear
and economic analyses are awaited. Mantle cell lymphoma is a relatively rare B-cell lymphoma with a specific
genetic lesion and a typical immunophenotypic profile. The median age is 65
years. There is no curative treatment, except allogeneic stem cell
transplantation for a selected group of patients. For the majority of patients,
especially the elderly, the aim of therapy should therefore be a long
progression-free survival. Age and comorbidity may hamper the use of the most
active treatment regimen, such as high dose cytarabine and autologous stem cell
transplantation. Therefore, it is a challenge to select the most appropriate
therapy for an elderly patient. Studies specifically designed for elderly
patients are rare. A recently performed large randomized study for elderly
patients, however, has shown that R-CHOP (rituximab with cyclophosphamide,
doxorubicin, vincristine, and prednisone) chemotherapy followed by maintece
rituximab can result in a long progression-free survival. For patients too frail
for R-CHOP chemotherapy, a treatment should be offered that benefits the patient
in reducing the symptoms of the disease without causing too many side effects.
Progression or relapse will occur in all patients sooner or later. Second-line
treatment should again be carefully selected. Several options are mentioned. New
drugs are being developed, and new combinations are investigated. Further
improvement in the outcome of patients with mantle cell lymphoma is expected.
Participation in well-designed clinical trials, also by elderly patients, is
important to find the real benefit that can be achieved, and to get information
on the tolerability of these treatments in this age group. Multiple advances have been made in our understanding of pathobiology of chronic
lymphocytic leukemia (CLL). These developments in the laboratory include new
prognostic markers, risk stratification of the disease and newer therapeutic
agents in CLL. These advances in CLL have come a long way in the past three
decades since the development of Rai and Binet clinical staging systems.
Important strides in the pathobiology, from defining mutational status of IGHV,
to B-cell receptor (BCR) signaling pathways and CLL microenvironment have made a
major difference in our understanding of this disease. Mutational status of
immunoglobulin heavy chain genes (IGHV), CD38 and Zap-70, chromosomal
aberrations and newer mutations, are the most clinically relevant prognostic
markers. Chemoimmunotherapy (CIT) has become the treatment of choice for young
and fit CLL patients. Various inhibitors of BCR signaling pathways and
immunomodulatory drugs have shown efficacy in clinical trials. The most recent
advance is the use of chimeric antigen receptor therapy (CAR) based on
autologous T-lymphocytes. Nevertheless, CLL remains an incurable disease today.
Coordinated developments between laboratory and clinic will hopefully translate
into a cure for CLL. This short review focuses on advances in prognostication
and therapy in CLL. |
Is the Miller-Fisher syndrome considered to be a variant of Guillain-Barré? | Miller Fisher syndrome is a variant of Guillain-Barre syndrome characterized by the classic triad of ophthalmoplegia, ataxia, and areflexia | The syndrome of ataxia, areflexia and ophthalmoplegia, or Miller-Fisher
syndrome, has been considered to be a variant of Guillain-Barré syndrome with
pathology restricted to the peripheral nervous system. A patient with
Miller-Fisher syndrome and bilateral demyelinating optic neuropathy suggesting
associated central nervous system pathology is presented. Clinical and
experimental evidence regarding the association of central and peripheral
nervous system demyelination is reviewed. A recent report described serum anti-GQ1b ganglioside antibodies in Miller
Fisher syndrome (MFS), a clinical variant of Guillain-Barré syndrome (GBS). Four
consecutive cases of MFS all had high titre anti-GQ1b antibodies which were
absent from all control sera including those of patients with GBS. OBJECTIVES: To estimate the incidence rate of Guillain-Barré syndrome variants
in an unselected population and to describe their clinical features and
prognosis.
METHODS: A two year prospective multicentre study on the incidence and prognosis
of Guillain-Barré syndrome was performed in Emilia-Romagna, northern Italy
(3,909,512 inhabitants). A surveillance system was instituted within the study
area, which comprised all the neurological departments, private and public
general hospitals, and practising neurologists. The international classification
of diseases (ICD) codes 357.XX (any peripheral neuropathy) of hospital
discharges were also reviewed.
RESULTS: Data were separately analysed for Miller Fisher syndrome and other
Guillain-Barré syndrome variants. During the study period 18 patients with
Guillain-Barré syndrome variants including seven with Miller Fisher syndrome
were recruited; the incidence rates were 0.14/100000/year (95% confidence
interval (95% CI) 0.07-0.25) for Guillain-Barré syndrome variants (excluding
Miller Fisher syndrome) and 0.09/100000/year (95% CI 0.04-0.18) for Miller
Fisher syndrome. Guillain-Barré syndrome variants alone (excluding Miller Fisher
syndrome) accounted for 10.5% of total cases. Death and relapses were not found.
Details of clinical, electrophysiological, and CSF findings of Guillain-Barré
syndrome variants are provided.
CONCLUSIONS: Guillain-Barré syndrome variants other than Miller Fisher syndrome,
as obtained through a population based study, account for about 10% of total
cases of Guillain-Barré syndrome and, as a whole, have a good prognosis. Their
clinical features are heterogeneous; bifacial weakness (associated with other
signs, mainly sensory disturbances) represents the most frequent finding. Some patients developed Guillain-Barré syndrome after the administration of
bovine brain ganglioside. Patients with Guillain-Barré syndrome subsequent to
Campylobacter jejuni enteritis frequently have IgG antibody to GM1 ganglioside.
Miller Fisher syndrome, a variant of Guillain-Barré syndrome, is associated with
IgG antibody to GQ1b ganglioside. My colleagues and I showed the existence of
molecular mimicry between GM1 and lipopolysaccharide of C. jejuni isolated from
a patient with Guillain-Barré syndrome, and that between GQ1b and C. jejuni
lipopolysaccharides from patients with Miller Fisher syndrome. The glycotope
mimicry between infectious agents and gangliosides may function in the
production of antiganglioside antibodies and the development of Guillain-Barré
syndrome and Miller Fisher syndrome. Miller Fisher syndrome (MFS), characterized as ataxia, areflexia and
ophthalmoplegia, is generally considered as a variant of Guillain-Barré syndrome
(GBS). However, some investigators believed that the syndrome could be explained
by a central origin. To obtain more information about MFS for comparison with
GBS, we conducted a retrospective study by analyzing the clinical data of MFS
patients admitted to our hospital over a period of 11 years. The calibrated
male/female ratio was 1.65. A seasonal clustering in winter was noted. The
percentage of MFS among GBS was especially high (18%, 11/60) in Taiwan when
compared with other series. Involvement of limb muscle strength, autonomic
function and cranial nerves, except ocular motor nerves, was rarely found in our
patients. When MFS is accompanied by limb weakness, it might represent a
transitional form between MFS and GBS. Bulbar palsy and dysautonomia might
predict a relatively poor prognosis. To obtain more reliable information, lumbar
puncture should be done 1 week after disease onset, and electrophysiological
tests should be done serially in every MFS patient. Eighty percent (80%, 4/5) of
our patients were positive for IgG anti-GQ(1b) antibody activity. In our study,
there is more evidence indicating that MFS is a peripheral nervous system
disorder; however, no definite conclusion could be made as to whether MFS is
exclusively a peripheral or central nervous system disorder. We think MFS is an
immune-mediated clinical entity which mainly involves the peripheral nervous
system with rare involvement of other parts of the central nervous system. Controversy exists concerning whether Miller Fisher syndrome (MFS) is the result
of a predomitly axonal or demyelinating polyneuropathy and whether the
Guillain-Barré syndrome variant of acute ataxia and areflexia without
ophthalmoplegia, ataxic Guillain-Barré syndrome (atxGBS), has a distinct
pathophysiology. We explored these issues by reviewing the electrophysiologic
features of 6 patients with MFS and 2 patients with atxGBS. EMG laboratory
records were reviewed and electrophysiologic findings were categorized as axonal
or demyelinating neuropathy using previously defined criteria. Of the 6 patients
with MFS, 5 had electrophysiologic evidence suggestive of an axonal,
predomitly sensory polyneuropathy; only 1 patient met criteria for
demyelinating polyneuropathy. Both patients with atxGBS had demyelinating
sensorimotor polyneuropathy. Electrophysiologic abnormalities in MFS typically
suggest a predomitly axonal, sensory polyneuropathy, though demyelinating
forms occur and may be under-diagnosed using current criteria. AtxGBS, in our
experience, is a predomitly demyelinating polyneuropathy. BACKGROUND AND OBJECTIVE: Miller-Fisher syndrome (MFS) is considered the most
common variant of Guillain-Barré syndrome (GBS) and is characterized by the
clinical triad of ophthalmoplegia, ataxia and areflexia. Respiratory involvement
and relapses are unusual. Patients with MFS usually have a good recovery and no
residual deficits. We describe the clinical features, associated infections and
evolution in eight patients with MFS.
PATIENTS AND METHOD: Eight cases of MFS and sixty-one of GBS were studied
between 1994 and 2003. All cases showed the clinical triad of MFS without major
limb weakness or other signs suggestive of CNS involvement.
RESULTS: The proportion of MFS with respect to GBS during the same period was
13.1%. Four had a positive serology for Epstein-Barr virus, Salmonella
enteritidis, Chlamydia pneumoniae and Mycoplasma pneumoniae. Our cases showed
facial palsy (75%), dysphagia (75%), pupillary abnormalities (37.5%) and
ventilation support (37.5%). Antiganglioside antibodies, determined in three
cases (4 episodes), were positive [GQ1b (50%) and GD1b (50%)]. In all cases,
there was a markedly reduced amplitude of the distal sensory as well as frequent
axonal degeneration signs. The oldest three patients relapsed and required
ventilation support.
CONCLUSIONS: We report for the first time an association between S. enteritidis
and C. pneumoniae and MFS. Older patients in our series suffered a faster
disease progression with need of ventilation support. We conclude that an older
age correlates with poor prognosis and relapses. BACKGROUND: Miller-Fisher syndrome is characterised by the clinical triad of
ophthalmoplegia, ataxia and areflexia and is considered a variant form of
Guillain-Barré syndrome. In western countries the incidence is reported to be
approximately 1-5% that of Guillain-Barré syndrome. Approximately 90% of
patients have antibodies against the ganglioside GQ1b, which is of diagnostic
and pathogenic importance.
MATERIAL AND METHODS: We present two patients with Miller-Fisher syndrome and
describe clinical features and possible mechanisms of GQ1b antibodies.
RESULTS AND INTERPRETATION: Both patients presented with the classical triad of
symptoms and GQ1b antibodies after upper respiratory tract infections. One of
the patients had a more severe form with additional bulbar signs and was treated
with plasma exchange. Both made almost complete recoveries within a few months. A large body of clinical and experimental data indicate that complement
activation is an important mechanism for neuronal and glial injury in
Guillain-Barré syndromes. Inhibition of complement activation therefore might be
expected to limit the progression of the disease. Using in vitro and in vivo
models of the Guillain-Barré syndrome variant, Miller Fisher syndrome, we have
shown previously that anti-GQ1b ganglioside antibodies target the presynaptic
motor nerve terminal axon and surrounding perisynaptic Schwann cells, thereby
mediating destructive injury through deposition of membrane attack complex.
Here, we have used this model to investigate the effects of a novel therapeutic
inhibitor of complement activation, APT070 (Mirococept), both in vitro and in
vivo. In these models, APT070 completely prevents membrane attack complex
formation, and thereby has a major neuroprotective effect at the nerve terminal,
as assessed by immunohistology of perisynaptic Schwann cell and axonal
integrity. These data provide a rationale for considering clinical trials of
APT070 in Guillain-Barré syndrome, its variant forms, and other complement
dependent neuromuscular disorders. PURPOSE OF REVIEW: Miller Fisher syndrome is a localized variant of
Guillain-Barré syndrome, characterized by ophthalmoplegia, areflexia and ataxia.
Bickerstaff's brainstem encephalitis is a related syndrome in which upper motor
neurone features accompany the classic triad. Anti-GQ1b antibodies are uniquely
found in both conditions and are believed to be pathogenic.
RECENT FINDINGS: Infectious illnesses usually precede Miller Fisher syndrome.
The clearest associations have been described with Haemophilus influenzae and
Campylobacter jejuni infection. Raised cerebrospinal fluid protein is seen in
60% of patients, but clinical features and anti-GQ1b antibody testing are
diagnostically more informative. Experimental studies demonstrating
complement-dependent neuromuscular block may be relevant to the clinical
pathophysiology of Miller Fisher syndrome. Recent neurophysiological studies
suggest abnormal neuromuscular transmission occurs in some cases of Miller
Fisher syndrome and Guillain-Barré syndrome. Recent mouse models have
demonstrated that presynaptic neuronal membranes and perisynaptic Schwann cells
are targets for anti-GQ1b antibody attack. The elimination of antiganglioside
antibodies from the circulation through specific immunoadsorption therapy has
the potential to ameliorate the course of Miller Fisher syndrome. This condition
is typically a benign, self-limiting illness. Both plasmapheresis and
intravenous immunoglobulin may be employed as treatment, especially in cases of
Bickerstaff's brainstem encephalitis or those with overlapping Guillain-Barré
syndrome.
SUMMARY: Anti-GQ1b antibody testing has allowed clinicians to develop a greater
understanding of the spectrum of Miller Fisher syndromes and to refine clinical
diagnoses in patients with unusual presentations. Experimental studies strongly
suggest anti-GQ1b antibodies are pathogenic, which in principle should direct
treatments towards antibody neutralization or elimination. INTRODUCTION: Wernicke's encephalopathy is an acute neuropsychiatric syndrome
resulting from a thiamine deficit, which is defined by the characteristic triad
of confusion, ophthalmoparesis and ataxia, although rare presentations have been
reported that delay its diagnosis. Miller Fisher syndrome is characterised by
the triad ophthalmoparesis, ataxia and areflexia and is considered to be a
variant of Guillain-Barré syndrome; its differential diagnosis includes
Wernicke's encephalopathy.
CASE REPORT: A 75-year-old female with chronic digestive disorders, who
developed an acute picture of bilateral internuclear ophthalmoplegia, ataxia and
areflexia, with proteinocytologic dissociation in cerebrospinal fluid;
accordingly, an initial diagnosis of Miller Fisher syndrome was proposed.
Results of the neurophysiological studies were normal; anti-GQ1b antibodies were
negative; and magnetic resoce imaging of the brain suggested Wernicke's
encephalopathy. The response to thiamine was spectacular.
CONCLUSIONS: The similarities in the distribution of the lesions of the two
conditions, in the signs and symptoms and the lab findings, as well as the
influence of certain misleading factors (hyponatremia, advanced age), went to
make up a typical syndrome that favoured a wrong presumptive aetiological
diagnosis. This was corrected at an early stage, however, in light of the
results of certain diagnostic tests and after observing the therapeutic
response. In addition to being an atypical presentation for Wernicke's
encephalopathy, this case highlights the fact that for there to be an agreement
between the syndromic and aetiological diagnoses it is necessary to carry out a
correct differential diagnosis based on details from the patient's history, on
appropriate complementary tests and on the follow-up study of how the patients
progress, even when we come across typical syndromes that are usually related to
a predomit aetiopathogenesis. Miller Fisher syndrome is a variant of Guillain-Barré syndrome, characterized by
ophthalmoplegia, ataxia and areflexia. The antiGQ1b immunoglobulin G antibody is
a specific marker of Miller Fisher syndrome and related disorders, such as
Guillain-Barré syndrome with ophthalmoplegia, atypical Miller Fisher syndrome
characterized by acute ophthalmoplegia or acute ataxia and Bickerstaff's
brainstem encephalitis. The antiGQ1b immunoglobulin G antibody may play some
important roles in the pathogenesis of Miller Fisher syndrome and related
disorders. Possible mechanisms are discussed. Molecular mimicry between an
infectious agent of the antecedent infection and the ganglioside may be a
mechanism of the antibody production. Plasmapheresis or intravenous
immunoglobulin therapy may be warranted for Miller Fisher syndrome and
Bickerstaff's brainstem encephalitis, as well as Guillain-Barré syndrome with
ophthalmoplegia. Miller Fisher syndrome is an acute inflammatory polyradiculoneuropathy that is
generally considered a variant of Guillain-Barré syndrome and is characterized
by the clinical triad of ataxia, areflexia, and ophthalmoplegia. Several reports
of familial Guillain-Barré syndrome have been reported, indicating a possible
underlying genetic and/or environmental predisposition to the development of
Guillain-Barré syndrome. A familial association in Miller Fisher syndrome has
not previously been described in the literature. We report 2 cases of Miller
Fisher syndrome presenting simultaneously in siblings, with a review of recent
relevant literature. Miller Fisher syndrome (MFS), a variant of Guillain-Barré syndrome, is a rare
disorder typically characterized by a triad of ataxia, areflexia, and
ophthalmoplegia, which may have a highly variable clinical presentation. We
report a case of MFS in a 45-year-old female presenting with sphenoid sinusitis
and sixth nerve palsy. She underwent endoscopic sphenoid sinusotomy without
improvement, had postoperative deterioration, was diagnosed with MFS, and was
treated with intravenous immunoglobulin with complete response. Because of the
potential severity of Guillain-Barré syndrome, great vigilance should be taken
when examining sixth nerve palsies to prevent misdiagnosis and delay in
treatment of the MFS variant of this disease. Miller-Fisher syndrome is defined as ophthalmoplegia, ataxia and areflexia.
Considered as a variant of Guillain-Barré syndrome, it differs in its clinical
presentation and by anti-GQ1b antibody positivity. The authors report a case of
Miller-Fisher syndrome characterized by ataxia and complete ophthalmoplegia.
Through this example, the range of ophthalmologic clinical manifestations are
discussed. Guillain-Barré syndrome (GBS) and its variant, Miller Fisher syndrome (MFS),
exist as several clinical subtypes with different neurological features and
presentations. Although the typical clinical features of GBS and MFS are well
recognized, current classification systems do not comprehensively describe the
full spectrum of either syndrome. In this Perspectives article, GBS and MFS are
classified on the basis of current understanding of the common
pathophysiological profiles of each disease phenotype. GBS is subclassified into
classic and localized forms (for example, pharyngeal-cervical-brachial weakness
and bifacial weakness with paraesthesias), and MFS is divided into incomplete
(for example, acute ophthalmoparesis, acute ataxic neuropathy) and CNS subtypes
(Bickerstaff brainstem encephalitis). Diagnostic criteria based on clinical
characteristics are suggested for each condition. We believe this approach to be
more inclusive than existing systems, and argue that it could facilitate early
clinical diagnosis and initiation of appropriate immunotherapy. Systemic lupus erythematosus (SLE) is an autoimmune systemic disease with
multiple organ involvement with high morbidity and mortality rate. Among the
severe potential fatal complications are those of the central and peripheral
nervous system which usually develop during the course of the disease and very
rarely from the outset of the disease. We are reporting a rare case of
Miller-Fisher (MFS) variant of Guillain-Barré syndrome (GBS) as the first
manifestation of SLE in a 41-year-old female who progressed to flaccid paralysis
with no neurological improvement with initial immunosuppressive therapy,
plasmapheresis, and first cycle of intravenous immunoglobulin (IVIG) but with
remarkable and complete recovery after the second 5-day course of IVIG. Miller Fisher syndrome is a variant of Guillain-Barre syndrome characterized by
the classic triad of ophthalmoplegia, ataxia, and areflexia. Pupillary
involvement is common in MFS and has been reported in 35-42% of MFS patients.
Although case reports have discussed isolated ophthalmoplegia as a presentation
of MFS, anisocoria and rapid fluctuation of pupillary diameter have not been
reported in anti-GQ1b antibody positive individuals. Here we describe an
individual who presented with diplopia and was found to have progressive
internal and external ophthalmoplegia with frequent fluctuations in pupillary
diameter and anisocoria. These exam findings are not commonly described even in
atypical presentations of MFS. The onset of symptoms was preceded by an upper
respiratory infection but no gastrointestinal symptoms. Imaging and CSF studies
were unremarkable; however serum levels of immunoglobulin G anti-GQ1b antibody
and anti-GAD antibody were elevated confirming the diagnosis of MFS. The patient
was treated with IVIG and intravenous steroids with mild resolution of external
ophthalmoplegia. He did not go on to develop more typical features of MFS such
as ataxia or areflexia. This demonstrates that isolated external and internal
ophthalmoparesis with rapidly fluctuating pupillary diameter and associated
anisocoria can be the sole manifestation of atypical MFS. |
Is Ctf4 involved in sister chromatid cohesion establishment? | Yes. Ctf4 is associated with the replisome and is required for proper establishment of cohesion by facilitating cohesin acetylation. | CTF4 and CTF18 are required for high-fidelity chromosome segregation. Both
exhibit genetic and physical ties to replication fork constituents. We find that
absence of either CTF4 or CTF18 causes sister chromatid cohesion failure and
leads to a preanaphase accumulation of cells that depends on the spindle
assembly checkpoint. The physical and genetic interactions between CTF4, CTF18,
and core components of replication fork complexes observed in this study and
others suggest that both gene products act in association with the replication
fork to facilitate sister chromatid cohesion. We find that Ctf18p, an RFC1-like
protein, directly interacts with Rfc2p, Rfc3p, Rfc4p, and Rfc5p. However, Ctf18p
is not a component of biochemically purified proliferating cell nuclear antigen
loading RF-C, suggesting the presence of a discrete complex containing Ctf18p,
Rfc2p, Rfc3p, Rfc4p, and Rfc5p. Recent identification and characterization of
the budding yeast polymerase kappa, encoded by TRF4, strongly supports a
hypothesis that the DNA replication machinery is required for proper sister
chromatid cohesion. Analogous to the polymerase switching role of the bacterial
and human RF-C complexes, we propose that budding yeast RF-C(CTF18) may be
involved in a polymerase switch event that facilities sister chromatid cohesion.
The requirement for CTF4 and CTF18 in robust cohesion identifies novel roles for
replication accessory proteins in this process. Cohesion establishment and maintece are carried out by proteins that modify
the activity of Cohesin, an essential complex that holds sister chromatids
together. Constituents of the replication fork, such as the DNA polymerase
alpha-binding protein Ctf4, contribute to cohesion in ways that are poorly
understood. To identify additional cohesion components, we analyzed a ctf4Delta
synthetic lethal screen performed on microarrays. We focused on a subset of
ctf4Delta-interacting genes with genetic instability of their own. Our analyses
revealed that 17 previously studied genes are also necessary for the maintece
of robust association of sisters in metaphase. Among these were subunits of the
MRX complex, which forms a molecular structure similar to Cohesin. Further
investigation indicated that the MRX complex did not contribute to metaphase
cohesion independent of Cohesin, although an additional role may be contributed
by XRS2. In general, results from the screen indicated a sister chromatid
cohesion role for a specific subset of genes that function in DNA replication
and repair. This subset is particularly enriched for genes that support the
S-phase checkpoint. We suggest that these genes promote and protect a chromatin
environment conducive to robust cohesion. Cohesion between sister chromatids mediated by a multisubunit complex called
cohesin is established during DNA replication and is essential for the orderly
segregation of chromatids during anaphase. In budding yeast, a specialized
replication factor C called RF-C(Ctf18/Dcc1/Ctf8) and the
DNA-polymerase-alpha-associated protein Ctf4 are required to maintain
sister-chromatid cohesion in cells arrested for long periods in mitosis. We show
here that CTF8, CTF4 and a helicase encoded by CHL1 are required for efficient
sister chromatid cohesion in unperturbed mitotic cells, and provide evidence
that Chl1 functions during S-phase. We also show that, in contrast to mitosis,
RF-C(Ctf18/Dcc1/Cft8), Ctf4 and Chl1 are essential for chromosome segregation
during meiosis and for the viability of meiotic products. Our finding that cells
deleted for CTF8, CTF4 or CHL1 undergo massive meiosis II non-disjunction
suggests that the second meiotic division is particularly sensitive to cohesion
defects. Using a functional as well as a cytological assay, we demonstrate that
CTF8, CHL1 and CTF4 are essential for cohesion between sister centromeres during
meiosis but dispensable for cohesin's association with centromeric DNA. Our
finding that mutants in fission yeast ctf18 and dcc1 have similar defects
suggests that the involvement of the alternative RF-C(Ctf18/Dcc1/Ctf8) complex
in sister chromatid cohesion might be highly conserved. DNA replication depends critically upon chromatin structure. Little is known
about how the replication complex overcomes the nucleosome packages in chromatin
during DNA replication. To address this question, we investigate factors that
interact in vivo with the principal initiation DNA polymerase, DNA polymerase
alpha (Polalpha). The catalytic subunit of budding yeast Polalpha (Pol1p) has
been shown to associate in vitro with the Spt16p-Pob3p complex, a component of
the nucleosome reorganization system required for both replication and
transcription, and with a sister chromatid cohesion factor, Ctf4p. Here, we show
that an N-terminal region of Polalpha (Pol1p) that is evolutionarily conserved
among different species interacts with Spt16p-Pob3p and Ctf4p in vivo. A
mutation in a glycine residue in this N-terminal region of POL1 compromises the
ability of Pol1p to associate with Spt16p and alters the temporal ordered
association of Ctf4p with Pol1p. The compromised association between the
chromatin-reorganizing factor Spt16p and the initiating DNA polymerase Pol1p
delays the Pol1p assembling onto and disassembling from the late-replicating
origins and causes a slowdown of S-phase progression. Our results thus suggest
that a coordinated temporal and spatial interplay between the conserved
N-terminal region of the Polalpha protein and factors that are involved in
reorganization of nucleosomes and promoting establishment of sister chromatin
cohesion is required to facilitate S-phase progression. The stabilization and processing of stalled replication forks is required to
maintain genome integrity in all organisms. In an effort to identify novel
proteins that might be involved in stabilizing stalled replication forks,
Saccharomyces cerevisiae mutant wss1Delta was isolated from a high-throughput
screening of approximately 5000 deletion strains for genes involved in the
response to continuous, low-intensity UV irradiation. Disruption of WSS1
resulted in synergistic increases in UV sensitivity with null mutants of genes
involved in recombination (RAD52) and cell cycle control (RAD9 and RAD24). WSS1
was also found to interact genetically with SGS1, TOP3, SRS2 and CTF4, which are
involved in recombination, repair of replication forks and the establishment of
sister chromatid cohesion. A yeast two-hybrid screen identified a potential
physical interaction between Wss1 and both Psy2 and Tof1. Genetic interactions
were also detected between PSY2 and TOF1, as well as between each gene and RAD52
and SRS2, and between WSS1 and TOF1. Tof1 is known to be involved in stabilizing
stalled replication forks and our data suggest that Wss1 and Psy2 similarly
function to stabilize or process stalled or collapsed replication forks. Two identical sister copies of eukaryotic chromosomes are synthesized during S
phase. To facilitate their recognition as pairs for segregation in mitosis,
sister chromatids are held together from their synthesis onward by the
chromosomal cohesin complex. Replication fork progression is thought to be
coupled to establishment of sister chromatid cohesion, facilitating
identification of replication products, but evidence for this has remained
circumstantial. Here we show that three proteins required for sister chromatid
cohesion, Eco1, Ctf4, and Ctf18, are found at, and Ctf4 travels along
chromosomes with, replication forks. The ring-shaped cohesin complex is loaded
onto chromosomes before S phase in an ATP hydrolysis-dependent reaction.
Cohesion establishment during DNA replication follows without further cohesin
recruitment and without need for cohesin to re-engage an ATP hydrolysis motif
that is critical for its initial DNA binding. This provides evidence for
cohesion establishment in the context of replication forks and imposes
constraints on the mechanism involved. Deletion mutants of CHL1 or CTF4, which are required for sister chromatid
cohesion, showed higher sensitivity to the DNA damaging agents methyl
methanesulfonate (MMS), hydroxyurea (HU), phleomycin, and camptothecin, similar
to the phenotype of mutants of RAD52, which is essential for recombination
repair. The levels of Chl1 and Ctf4 associated with chromatin increased
considerably after exposure of the cells to MMS and phleomycin. Although the
activation of DNA damage checkpoint did not affected in chl1 and ctf4 mutants,
the repair of damaged chromosome was inefficient, suggesting that Chl1 and Ctf4
act in DNA repair. In addition, MMS-induced sister chromatid recombination in
haploid cells, and, more importantly, MMS-induced recombination between
homologous chromosomes in diploid cells were impaired in these mutants. Our
results suggest that Chl1 and Ctf4 are directly involved in homologous
recombination repair rather than acting indirectly via the establishment of
sister chromatid cohesion. Sister-chromatid cohesion, the process of pairing replicated chromosomes during
mitosis and meiosis, is mediated through the essential cohesin complex and a
number of nonessential cohesion genes, but the specific roles of these
nonessential genes in sister-chromatid cohesion remain to be clarified. We
analyzed sister-chromatid cohesion in double mutants of mrc1Delta, tof1Delta,
and csm3Delta and identified additive cohesion defects that indicated the
existence of at least two pathways that contribute to sister-chromatid cohesion.
To understand the relationship of other nonessential cohesion genes with respect
to these two pathways, pairwise combinations of deletion and
temperature-sensitive alleles were tested for cohesion defects. These data
defined two cohesion pathways, one containing CSM3, TOF1, CTF4, and CHL1, and
the second containing MRC1, CTF18, CTF8, and DCC1. Furthermore, we found that
the nonessential genes are not important for the maintece of cohesion at
G(2)/M. Thus, our data suggest that nonessential cohesion genes make critical
redundant contributions to the establishment of sister-chromatid cohesion and
define two cohesion pathways, thereby establishing a framework for understanding
the role of nonessential genes in sister-chromatid cohesion. Ctf4/AND-1 is a highly conserved gene product required for both DNA replication
and the establishment of sister chromatid cohesion. In this report, we examined
the mechanism of action of human Ctf4 (hCtf4) in DNA replication both in vitro
and in vivo. Our findings show that the purified hCtf4 exists as a dimer and
that the hCtf4 SepB domain likely plays a primary role determining the dimeric
structure. hCtf4 binds preferentially to DNA template-primer structures,
interacts directly with the replicative DNA polymerases (alpha, delta, and
epsilon), and markedly stimulates the polymerase activities of DNA polymerases
alpha and epsilon in vitro. Depletion of hCtf4 in HeLa cells by small
interfering RNA resulted in G(1)/S phase arrest. DNA fiber analysis revealed
that cells depleted of hCtf4 exhibited a rate of DNA replication slower than
cells treated with control small interfering RNA. These findings suggest that in
human cells, hCtf4 plays an essential role in DNA replication and its ability to
stimulate the replicative DNA polymerases may contribute to this effect. Cohesion between sister chromatids, mediated by the chromosomal cohesin complex,
is a prerequisite for their alignment on the spindle apparatus and segregation
in mitosis. Budding yeast cohesin first associates with chromosomes in G1. Then,
during DNA replication in S-phase, the replication fork-associated
acetyltransferase Eco1 acetylates the cohesin subunit Smc3 to make cohesin's DNA
binding resistant to destabilization by the Wapl protein. Whether stabilization
of cohesin molecules that happen to link sister chromatids is sufficient to
build sister chromatid cohesion, or whether additional reactions are required to
establish these links, is not known. In addition to Eco1, several other factors
contribute to cohesion establishment, including Ctf4, Ctf18, Tof1, Csm3, Chl1
and Mrc1, but little is known about their roles. Here, we show that each of
these factors facilitates cohesin acetylation. Moreover, the absence of Ctf4 and
Chl1, but not of the other factors, causes a synthetic growth defect in cells
lacking Eco1. Distinct from acetylation defects, sister chromatid cohesion in
ctf4Δ and chl1Δ cells is not improved by removing Wapl. Unlike previously
thought, we do not find evidence for a role of Ctf4 and Chl1 in Okazaki fragment
processing, or of Okazaki fragment processing in sister chromatid cohesion.
Thus, Ctf4 and Chl1 delineate an additional acetylation-independent pathway that
might hold important clues as to the mechanism of sister chromatid cohesion
establishment. |
What states the second parity rule (PR2)? | The second parity rule (PR2), also known as Chargaff' s second parity rule, is an intra-strand rule which states that, when there are no biases between the two complementary strands of DNA in mutation and selection rates (substitution rates), complementary nucleotides are expected to have almost equal frequencies within single stranded DNA, namely A = T and G = C at equilibrium, without regard to the G + C content of the DNA. | The relative contribution of mutation and selection to the G+C content of DNA
was analyzed in bacterial species having widely different G+C contents. The
analysis used two methods that were developed previously. The first method was
to plot the average G+C content of a set of nucleotides against the G+C content
of the third codon position for each gene. This method was used to present the
G+C distribution of the third codon position and to assess the relative
neutrality of a set of nucleotides to that of the G+C content of the third codon
position. The second method was to plot the intrastrand bias of the third codon
position from Parity Rule 2 (PR2), where A = T and G = C. It was found that
whereas intragenomic distributions of the DNA G+C content of these bacteria are
narrow in the majority of species, in some species the G+C content of the minor
class of genes distributes over wider ranges than the major class of genes. On
the other hand, ubiquitous PR2 biases are amino acid specific and independent of
the G+C content of DNA, so that when averaged over the amino acids, the biases
are small and not correlated with the DNA G+C content. Therefore, translation
coupled PR2-biases are unlikely to explain the wide range of G+C contents among
different species. Considering all data available, it was concluded that the
amino acid-specific PR2 bias has only a minor effect, if any, on the average G+C
content. In addition, PR2 bias patterns of different species show phylogenetic
relationships, and the pattern can be as a taxal fingerprint. The genome of higher eukaryotes consists of genes having a widely heterogeneous
base composition at the third codon position. Ubiquitous variability of the DNA
base composition has the following two aspects: intragenomic heterogeneity of
the G+C content and the amino-acid-specific translation-coupled biases from the
Parity Rule 2 (PR2). PR2 is an intrastrand rule where A = T and G = C are
expected if there is no bias in mutation and selection between the two
complementary strands of DNA. To examine whether or not the biases from PR2 are
responsible for the wide heterogeneity of the DNA G+C content in human, the
third codon position of 846 human genes was analyzed. Genes were separated into
six groups according to their G+C content of the third codon position, and each
group was examined for the translation-coupled PR2 biases in the nucleotide
composition of the third codon position for two- and four-codon amino acids. The
results show that genes in the different G+C content groups have similar PR2
biases, indicating that the intragenomic heterogeneity of the G+C content is not
correlated with translation-coupled biases from the PR2. Therefore, the
heterogeneity of the G+C content is likely to be determined by some other
mechanism (e.g. locally variable directional mutation pressures) than
amino-acid-specific selections for the codon preference. In the absence of bias between the two DNA strands for mutation and selection,
the base composition within each strand should be such that A = T and C = G
(this state is called Parity Rule type 2, PR2). At a genome scale, i.e. when
considering the base composition of a whole genome, PR2 is a good approximation,
but there are local and systematic deviations. The question is whether these
deviations are a consequence of an underlying bias in mutation or selection. We
have tried to review published hypotheses to classify them within the mutational
or selective group. This dichotomy is, however, too crude because there is at
least one hypothesis based simultaneously upon mutation and selection. The human genome, as in other eukaryotes, has a wide heterogeneity in the DNA
base composition. The evolutionary basis for this heterogeneity has been
unknown. A previous study of the human genome (846 genes analyzed) has shown
that, in the major range of the G+C content in the third codon position
(0.25-0.75), biases from the Parity Rule 2 (PR2) among the synonymous codons of
the four-codon amino acids are similar except in the highest G+C range (Sueoka,
N., 1999. Translation-coupled violation of Parity Rule 2 in human genes is not
the cause of heterogeneity of the DNA G+C content of third codon position. Gene
238, 53-58.). PR2 is an intra-strand rule where A=T and G=C are expected when
there are no biases between the two complementary strands of DNA in mutation and
selection rates (substitution rates). In this study, 14,026 human genes were
analyzed. In addition, the third codon positions of two-codon amino acids were
analyzed. New results show the following: (a) The G+C contents of the third
codon position of human genes are scattered in the G+C range of 0.22-0.96 in the
third codon position. (b) The PR2 biases are similar in the range of 0.25-0.75,
whereas, in the high G+C range (0.75-0.96; 13% of the genes), the PR2-bias
fingerprints are different from those of the major range. (c) Unlike the PR2
biases, the G+C contents of the third codon position for both four-codon and
two-codon amino acids are all correlated almost perfectly with the G+C content
of the third codon position over the total G+C ranges. These results support the
notion that the directional mutation pressure, rather than the directional
selection pressure, is mainly responsible for the heterogeneity of the G+C
content of the third codon position. Genes of a multicellular organism are heterogeneous in the G+C content, which is
particularly true in the third codon position. The extent of deviation from
intra-strand equality rule of A = T and G = C (Parity Rule 2, or PR2) is
specific for individual amino acids and has been expressed as the PR2-bias
fingerprint. Previous results suggested that the PR2-bias fingerprints tend to
be similar among the genes of an organism, and the fingerprint of the organism
is specific for different taxa, reflecting phylogenetic relationships of
organisms. In this study, using coding sequences of a large number of human
genes, we examined the intragenomic heterogeneity of their PR2-bias fingerprints
in relation to the G+C content of the third codon position (P3). Result shows
that the PR2-bias fingerprint is similar in the wide range of the G+C content at
the third codon position (0.30-0.80). This range covers approximately 89% of the
genes, and further analysis of the high G+C range (0.80-1.00), where genes with
normal PR2-bias fingerprints and those with anomalous fingerprints are mixed,
shows that the total of 95% of genes have the similar finger prints. The result
indicates that the PR2-bias fingerprint is a unique property of an organism and
represents the overall characteristics of the genome. Combined with the previous
results that the evolutionary change of the PR2-bias fingerprint is a slow
process, PR2-bias fingerprints may be used for the phylogenetic analyses to
supplement and augment the conventional methods that use the differences of the
sequences of orthologous proteins and nucleic acids. Potential advantages and
disadvantages of the PR2-bias fingerprint analysis are discussed. The intra-strand Parity Rule 2 of DNA (PR2) states that A=T and G=C within each
strands. Useful corollaries of PR2 are G/(G+C)=A/(A+T)=0.5, G/(G+A)=C/(C+T)=G+C,
G/(G+T)=C/(C+A)=G+C. Here. A, T, G, and C represent relative contents of the
four nucleotide residues in a specific strand of DNA, so that A+T+G+C=1. Thus,
deviations from the PR2 is a sign of strand-specific (or asymmetric) mutation
and/or selection pressures. The present study delineates the symmetric and
asymmetric effects of mutations on the intra-genomic heterogeneity of the G+C
content in the human genome. The results of this study on the human genome are:
(1) When both two- and four-codon amino acids were combined, only slight
departures from the PR2 were observed in the total ranges of G+C content of the
third-codon position. Thus, the G+C heterogeneity is likely to be caused by
symmetric mutagenesis between the two strands. (2) The above result makes the
deamination of cytosine due to double-strand breathing of DNA [Mol. Biol. Evol.
17 (2000) 1371] and/or incorporation of the oxidized guanine (8-oxo-guanine)
opposite adenine during DNA replication (dGTP-oxidation hypothesis) as the most
likely candidates for the major cause of the diversities of the G+C content. (3)
Patterns of amino acid-specific PR2-biases detected by plotting PR2 corollaries
against the G+C content of third codon position revealed that eight four-codon
amino acids can be divided into three types by the second codon letter: (a)
C(2)-type (Ala, Pro, Ser4, and Thr), (b) G(2)-type (Arg4 and Gly), and (c)
T(2)-type (Leu4 and Val). (4) Most of the asymmetric plot patterns of the above
three classes in PR2 biases can be explained by C(2)-->T(2) deamination of
C(2)pG(3) of C(2)-type to T(2)pG(3) (T(2)-type) in both human and chicken. This
explains the existence of some preferred codons in human and chicken. However,
these biases (asymmetric) hardly contribute to the overall G+C content diversity
of the third codon position. Sueoka and Lobry declared respectively that, in the absence of bias between the
two DNA strands for mutation and selection, the base composition within each
strand should be A=T and C=G (this state is called Parity Rule type 2, PR2).
However, the genome sequences of many bacteria, vertebrates and viruses showed
asymmetries in base composition and gene direction. To determine the
relationship of base composition skews with replication orientation, gene
function, codon usage biases and phylogenetic evolution, in this paper a program
called DNAskew was developed for the statistical analysis of strand asymmetry
and codon composition bias in the DNA sequence. In addition, the program can
also be used to predict the replication boundaries of genome sequences. The
method builds on the fact that there are compositional asymmetries between the
leading and the lagging strand for replication. DNAskew was written in Perl
script language and implemented on the LINUX operating system. It works quickly
with annotated or unotated sequences in GBFF (GenBank flatfile) or fasta
format. The source code is freely available for academic use at
http://www.epizooty.com/pub/stat/DNAskew. Chargaff's rule of intra-strand parity (ISP) between complementary
mono/oligonucleotides in chromosomes is well established in the scientific
literature. Although a large numbers of papers have been published citing works
and discussions on ISP in the genomic era, scientists are yet to find all the
factors responsible for such a universal phenomenon in the chromosomes. In the
present work, we have tried to address the issue from a new perspective, which
is a parallel feature to ISP. The compositional abundance values of
mono/oligonucleotides were determined in all non-overlapping sub-chromosomal
regions of specific size. Also the frequency distributions of the
mono/oligonucleotides among the regions were compared using the
Kolmogorov-Smirnov test. Interestingly, the frequency distributions between the
complementary mono/oligonucleotides revealed statistical similarity, which we
named as intra-strand frequency distribution parity (ISFDP). ISFDP was observed
as a general feature in chromosomes of bacteria, archaea and eukaryotes.
Violation of ISFDP was also observed in several chromosomes. Chromosomes of
different strains belonging a species in bacteria/archaea (Haemophilus
influenza, Xylella fastidiosa etc.) and chromosomes of a eukaryote are found to
be different among each other with respect to ISFDP violation. ISFDP correlates
weakly with ISP in chromosomes suggesting that the latter one is not entirely
responsible for the former. Asymmetry of replication topography and composition
of forward-encoded sequences between the strands in chromosomes are found to be
insufficient to explain the ISFDP feature in all chromosomes. This suggests that
multiple factors in chromosomes are responsible for establishing ISFDP. The second parity rule of Chargaff (A≈T and G≈C within one strand) holds all
over the living world with minor exceptions. It is maintained with higher
accuracy for long sequences. The question addressed in the article is how
different sequence types, with different biases from the parity, contribute to
the general effect. It appears that the sequence segments with biases of
opposite sign are intermingled, so that with sufficient sequence lengths the
parity is established. The parity rule seems to be a cumulative result of a
number of independent processes in the genome evolution, with the parity as
their intrinsic property. Symmetrical appearance of simple repeats and of Alu
sequences in the human DNA strands, and other contributions to the Chargaff
parity II rule are discussed. |
Are retroviruses used for gene therapy? | Gene therapy is one of the most promising and active fields in therapeutic research. Gene therapy is a treatment option that introduces genetic material in vivo or ex vivo into the cells of an affected organism in order to: exchange a defective gene; manipulate a disease-related gene; or introduce an additional gene copy for overexpression of the encoded protein to generate a curative biological effect. Somatic gene therapy is gene transfer by a specific vector to a somatic cell; in contrast to germline gene therapy, the modification of the cell is restricted to the recipient and cannot be passed to her/his progeny. High efficiency of gene transfer, high specificity for the target cells, long-lasting expression of the transgene and safety without adverse reactions are the desired characteristics of an ideal vector for gene transfer.
Retroviral (gretroviral and lentiviral) vectors have now been used in more than 350 gene-therapy studies. Retroviral vectors are particularly suited for gene-correction of cells due to long-term and stable expression of the transferred transgene(s), and also because little effort is required for their cloning and production. Several monogenic inherited diseases, mostly immunodeficiencies, can now be successfully treated. | The theoretical possibility of applying gene transfer methodologies to the human
germline is explored. Transgenic methods for genetically manipulating embryos
may in principle be applied to humans. In particular, microinjection of
retroviral vector appears to hold the greatest promise, with transgenic primates
already obtained from this approach. Sperm-mediated gene transfer offers
potentially the easiest route to the human germline, however the requisite
methodology is presently underdeveloped. Nuclear transfer (cloning) offers an
alternative approach to germline genetic modification, however there are major
health concerns associated with current nuclear transfer methods. It is
concluded that human germline gene therapy remains for all practical purposes a
future possibility that must await significant and important advances in gene
transfer technology. Though the field has moved with glacial speed, gene therapies have been carried
out successfully in patients with bone marrow disorders including immune
deficiencies. The field may be poised to move forward more rapidly, but many
barriers have yet to be surmounted. The past 15 years opened new avenues for retrovirus and retroelement research.
Not surprisingly, they stemmed from essential knowledge collected in the past,
which remains the ground of the present and therefore should be remembered.
However, a short supplement of new break-through discoveries and ideas should be
recollected. Using selected examples of recent works, I tried to extend and
supplement my original article published in Folia Biologica (1996). Mucopolysaccharidosis VII (MPS VII) is due to deficient activity of the
lysosomal enzyme β-glucuronidase (GUSB) and results in the accumulation of
glycosaminoglycans (GAGs). This study determined the long-term effect of
neonatal intravenous injection of a gamma retroviral vector (RV) on cardiac
valve disease in MPS VII dogs. Transduced hepatocytes secreted GUSB into the
blood for up to 11 years at levels similar to or greater than those achieved
with enzyme replacement therapy (ERT). Valve regurgitation and thickening were
scored from 0 (normal) to +4 (severely abnormal). At 1 year, untreated MPS VII
dogs had mitral regurgitation, mitral valve thickening, aortic regurgitation,
and aortic valve thickening scores of 2.3 ± 0.7, 2.3 ± 0.6, 1.8 ± 0.5, and 1.6 ±
0.7, respectively, which were higher than the values of 0.6 ± 0.1, 0.1 ± 0.4,
0.3 ± 0.8, and 0.1 ± 0.4, respectively, in treated MPS VII dogs. Treated MPS VII
dogs maintained low aortic regurgitation and aortic valve thickening scores in
their lifetime. Although mitral regurgitation and mitral valve thickening scores
increased to 2.0 at ≥ 8 years of age in the treated MPS VII dogs, older normal
dogs from the colony had similar scores, making it difficult to assess mitral
valve disease. Older treated dogs had calcification within the mitral and the
aortic valve annulus, while GUSB staining demonstrated enzyme activity within
the mitral valve. We conclude that neonatal RV-mediated gene therapy reduced
cardiac valve disease in MPS VII dogs for up to 11 years, and propose that
neonatal initiation of ERT should have a similar effect. Different types of endothelial cells (EC) fulfill distinct tasks depending on
their microenvironment. ECs are therefore difficult to genetically manipulate ex
vivo for functional studies or gene therapy. We assessed lentiviral vectors
(LVs) targeted to the EC surface marker CD105 for in vivo gene delivery. The
mouse CD105-specific vector, mCD105-LV, transduced only CD105-positive cells in
primary liver cell cultures. Upon systemic injection, strong reporter gene
expression was detected in liver where mCD105-LV specifically transduced liver
sinusoidal ECs (LSECs) but not Kupffer cells, which were mainly transduced by
nontargeted LVs. Tumor ECs were specifically targeted upon intratumoral vector
injection. Delivery of the erythropoietin gene with mCD105-LV resulted in
substantially increased erythropoietin and hematocrit levels. The human
CD105-specific vector (huCD105-LV) transduced exclusively human LSECs in mice
transplanted with human liver ECs. Interestingly, when applied at higher dose
and in absence of target cells in the liver, huCD105-LV transduced ECs of a
human artery transplanted into the descending mouse aorta. The data demonstrate
for the first time targeted gene delivery to specialized ECs upon systemic
vector administration. This strategy offers novel options to better understand
the physiological functions of ECs and to treat genetic diseases such as those
affecting blood factors. BACKGROUND: Double-suicide gene therapy is a promising strategy for the
treatment of advanced cancer. It has become an important research line in the
development of gene therapy to overcome the drawbacks of single-gene therapy.
OBJECTIVE: The aim of this study was to investigate the usefulness of
double-suicide gene therapy with the two suicide genes, gef and apoptin, in
colon carcinoma.
METHODS: gef and apoptin genes were cloned into a doxycycline-regulated
retrovirus-mediated gene expression system. Expression of both genes in the
DLD-1 cell line was confirmed by reverse transcriptase polymerase chain reaction
(RT-PCR). Cell viability was determined with the sulforhodamine B colorimetric
assay, and the cell cycle was studied by propidium iodide (PI) staining. Annexin
V-FITC and PI assays were used to evaluate apoptosis, and the results were
confirmed by electron microscopy. The mitochondrial membrane potential was
measured by JC-1 assay.
RESULTS: Our results showed that the combined expression of gef and apoptin
genes was strikingly more effective than the expression of either gene alone.
Co-expression of gef and apoptin synergistically enhanced the decrease in cell
viability, increasing necrosis and inducing apoptosis in colon cancer cells via
the mitochondrial pathway, which can be deficient in advanced or metastatic
colon cancer.
CONCLUSIONS: Double-suicide gene therapy based on gef and apoptin genes may be a
candidate for the development of new colon cancer strategies, and further
studies are warranted to establish the usefulness of double-suicide gene therapy
in vivo. Current viral gene delivery vectors for gene therapy are inefficient due to
short-lived transgene expression attributed to the cytosine-phosphate-guanine
(CpG) motifs in the transgene. Here we assessed the effects of CpG motif
reduction in lentiviral (LV) gene delivery context on the level and duration of
reporter gene expression in Chinese Hamster Ovary (CHO) cells, Human
Immortalized Myelogenous Leukemia (K562) cells and hematopoietic stem cells
(HSCs). The cells were transduced with LV carrying Zero-CpG green fluorescent
protein (ZGFP) reporter gene, LV/CMV/ZGFP. The GFP expression was compared to
its non CpG-depleted GFP reporter gene LV (LV/CMV/GFP) counterpart. The
LV/CMV/ZGFP exhibited prolonged transgene expression in CHO cells and HSCs up to
10 days and 14 days, in the respective cells. This effect was not seen in the
transduced K562 cells, which may be due to the DNA hypomethylation status of the
cancer cell line. Transgene copy number analysis verified that the GFP
expression was not from pseudo-transduction and the transgene remained in the
genome of the cells throughout the period of the study. The modest positive
effects from the LV/CMV/ZGFP suggest that the reduction of CpG in the LV
construct was not substantial to generate higher and more prolonged transgene
expression. |
Do lincRNAs play a role in human cancer? | Long non-coding RNAs (lncRNAs) are pervasively transcribed in the genome and are emerging as new players in tumorigenesis due to their various functions in transcriptional, posttranscriptional and epigenetic mechanisms of gene regulation. The best-studied examples include HOTAIR, a negative prognostic factor that exhibits pro-oncogenic activity in a variety of human cancers, CRNDE the gene symbol for Colorectal Neoplasia Differentially Expressed (non-protein-coding), a long non-coding RNA (lncRNA) gene that expresses multiple splice variants and displays a very tissue-specific pattern of expression and ANRIL, a lincRNA that is required for the PRC2 recruitment to and silencing of p15(INK4B) tumor suppressor gene. | Large intervening non-coding RNAs (lincRNAs) are pervasively transcribed in the
genome yet their potential involvement in human disease is not well understood.
Recent studies of dosage compensation, imprinting, and homeotic gene expression
suggest that individual lincRNAs can function as the interface between DNA and
specific chromatin remodelling activities. Here we show that lincRNAs in the HOX
loci become systematically dysregulated during breast cancer progression. The
lincRNA termed HOTAIR is increased in expression in primary breast tumours and
metastases, and HOTAIR expression level in primary tumours is a powerful
predictor of eventual metastasis and death. Enforced expression of HOTAIR in
epithelial cancer cells induced genome-wide re-targeting of Polycomb repressive
complex 2 (PRC2) to an occupancy pattern more resembling embryonic fibroblasts,
leading to altered histone H3 lysine 27 methylation, gene expression, and
increased cancer invasiveness and metastasis in a manner dependent on PRC2.
Conversely, loss of HOTAIR can inhibit cancer invasiveness, particularly in
cells that possess excessive PRC2 activity. These findings indicate that
lincRNAs have active roles in modulating the cancer epigenome and may be
important targets for cancer diagnosis and therapy. A 42 kb region on human chromosome 9p21 encodes for three distinct tumor
suppressors, p16(INK4A), p14(ARF) and p15(INK4B), and is altered in an estimated
30-40% of human tumors. The expression of the INK4A-ARF-INK4B gene cluster is
silenced by polycomb during normal cell growth and is activated by oncogenic
insults and during aging. How the polycomb is recruited to repress this gene
cluster is unclear. Here, we show that expression of oncogenic Ras, which
stimulates the expression of p15(INK4B) and p16(INK4A), but not p14(ARF),
inhibits the expression of ANRIL (antisense non-coding RNA in the INK4 locus), a
3.8 kb-long non-coding RNA expressed in the opposite direction from
INK4A-ARF-INK4B. We show that the p15(INK4B) locus is bound by SUZ12, a
component of polycomb repression complex 2 (PRC2), and is H3K27-trimethylated.
Notably, depletion of ANRIL disrupts the SUZ12 binding to the p15(INK4B) locus,
increases the expression of p15(INK4B), but not p16(INK4A) or p14(ARF), and
inhibits cellular proliferation. Finally, RNA immunoprecipitation demonstrates
that ANRIL binds to SUZ12 in vivo. Collectively, these results suggest a model
in which ANRIL binds to and recruits PRC2 to repress the expression of
p15(INK4B) locus. Long non-coding RNA urothelial carcinoma associated 1 (UCA1) promotes human
bladder cancer cell proliferation, but the underlying mechanism remains unknown.
After knocking down of UCA1 in BLZ-211 cells, several cell cycle-related genes
(CDKN2B, EP300 and TGFβ-2) were screened by microarray assay and validated by
real-time PCR. Interestingly, in western blot analysis, p300 (encoded by EP300)
and its coactivator cAMP response element-binding protein (CREB) level were
significantly down-regulated. Both suppression of UCA1 expression by shRNA in
BLZ-211 cells and ectopic expression of UCA1 in UMUC-2 cells showed that UCA1
alteration paralleled to the expression and phosphorylation of CREB, and UCA1
obviously influenced AKT expression and activity. Furthermore, in BLZ-211 cells,
cell cycle progression was greatly reduced after PI3-K pathway was blocked by
LY294002, indicating that UCA1 affected cell cycle progression through CREB.
Taken together, we concluded that UCA1 regulated cell cycle through CREB via
PI3K-AKT dependent pathway in bladder cancer. Long non-coding RNAs (ncRNAs) have been shown to regulate important biological
processes that support normal cellular functions. Aberrant regulation of these
essential functions can promote tumor development. In this review, we underscore
the importance of the regulatory role played by this distinct class of ncRNAs in
cancer-associated pathways that govern mechanisms such as cell growth, invasion,
and metastasis. We also highlight the possibility of using these unique RNAs as
diagnostic and prognostic biomarkers in maligcies. OBJECTIVE: To screen long non-coding RNA which influences radiosensitivity of
colorectal carcinoma cell lines and investigate the mechanism.
METHODS: Under different doses of radiation, colony formation assay and
single-hit multi-target model were conducted to draw dose-survival curve and SF2
value of colorectal carcinoma cell lines(RKO, Lovo) was calculated.
High-throughput lncRNA/mRNA chips were used to screen lncRNA genes and protein
coding genes with expression differences more than 2 folds between RKO, Lovo
cell lines and RKO cell line receiving 2Gy radiation. The main action pathway
was computed by Gene Ontology analysis combined with Pathway analysis in order
to explore the mechanism which induces the effect of lncRNA on radiosensitivity
of colorectal carcinoma cell lines. Further experiment on P53, P21, cyclin D1
expression contents of RKO cell line was confirmed by real-time RT-PCR.
RESULTS: Lovo(SF2=0.47) was more sensitivity to radiation than RKO(SF2=0.53)
according to the outcome of colony formation assay. High-throughput lncRNA/mRNA
chips identified a total of 268 lncRNA genes and 270 protein coding genes. Gene
Ontology analysis showed that the expression of genes associated with cell cycle
process were significantly different (38.6%). There was a significant
relationship between expression of several lncRNAs and CCND1 gene. Real-time
RT-PCR showed no significant differences of P53 and P21 expression in RKO and
Lovo cell lines(P>0.05), while cyclin D1 expression of RKO cell line was higher
than that of Lovo cell lines(P<0.05). After exposed to 2 Gy doses of radiation,
there was an obvious decrease of cyclin D1 expression in RKO cell lines(P<0.05),
while P53 and P21 expressions were not different(P>0.05).
CONCLUSION: The possible mechanism is that lncRNAs compose transcription
compound to combine with CCND1 gene and influence radiosensitivity of colorectal
carcinoma cell lines by regulating expression of cyclin D1, which is independent
of P53-P21-cyclin D1 pathway. BACKGROUND: Recently, several studies have demonstrated that two long non-coding
RNAs (lncRNAs), HULC and MALAT1, may participate in hepatocellular carcinoma
(HCC) development and progression. However, genetic variations in the two
lncRNAs and their associations with HCC susceptibility have not been reported.
In this study, we hypothesized that single nucleotide polymorphisms (SNPs) in
HULC and MALAT1 may contribute to HCC risk.
METHODS: We conducted a case-control study and genotyped two SNPs, rs7763881 in
HULC and rs619586 in MALAT1, in 1300 HBV positive HCC patients, 1344 HBV
persistent carriers and 1344 subjects with HBV natural clearance to test the
associations between the two SNPs and susceptibility to HCC and HBV chronic
infection.
RESULTS: The variant genotypes of rs7763881 were significantly associated with
decreased HCC risk in a domit genetic model [AC/CC vs. AA: adjusted odds
ration (OR) = 0.81, 95% confidence intervals (CIs) = 0.68-0.97, P =
0.022]. Furthermore, the variant genotypes of rs619586 was associated with
decreased HCC risk with a borderline significance (AG/GG vs. AA: adjusted OR =
0.81, 95% CIs = 0.65-1.01, P = 0.057). However, no significant association
was found between the two SNPs and HBV clearance.
CONCLUSIONS: The variant genotypes of rs7763881 in HULC may contribute to
decreased susceptibility to HCC in HBV persistent carriers. HOTAIR is a long intervening non-coding RNA (lincRNA) that associates with the
Polycomb Repressive Complex 2 (PRC2) and overexpression is correlated with poor
survival for breast, colon and liver cancer patients. In this study, we show
that HOTAIR expression is increased in pancreatic tumors compared with non-tumor
tissue and is associated with more aggressive tumors. Knockdown of HOTAIR
(siHOTAIR) by RNA interference shows that HOTAIR has an important role in
pancreatic cancer cell invasion, as reported in other cancer cell lines. In
contrast, HOTAIR knockdown in Panc1 and L3.6pL pancreatic cancer cells that
overexpress this lincRNA decreased cell proliferation, altered cell cycle
progression and induced apoptosis, demonstrating an expanded function of HOTAIR
in pancreatic cancer cells compared with other cancer cell lines. Results of
gene array studies showed that there was minimal overlap between
HOTAIR-regulated genes in pancreatic cells and breast cancer cells, and HOTAIR
uniquely suppressed several interferon-related genes and gene sets related to
cell cycle progression in pancreatic cancer cells and tumors. Analysis of
selected genes suppressed by HOTAIR in Panc1 and L3.6pL cells showed by
knockdown of EZH2 and chromatin immunoprecipitation assays that HOTAIR-mediated
gene repression was both PRC2-dependent and -independent. HOTAIR knockdown in
L3.6pL cells inhibited tumor growth in mouse xenograft model, further
demonstrating the pro-oncogenic function of HOTAIR in pancreatic cancer. A major function of long non-coding RNAs (lncRNAs) is regulating gene expression
through changes in chromatin state. Experimental evidence suggests that in
cancer, they can influence Polycomb Repressive Complexes (PRC) to retarget to an
occupancy pattern resembling that of the embryonic state. We have previously
demonstrated that the expression level of lncRNA in the HOX locus, including
HOTAIR, is a predictor of breast cancer metastasis. In this current project, RNA
in situ hybridization of probes to three different lncRNAs (HOTAIR, ncHoxA1, and
ncHoxD4), as well a immunohistochemical staining of EZH2, is undertaken in
formalin-fixed paraffin-embedded breast cancer tissues in a high throughput
tissue microarray format to correlate expression with clinicopathologic
features. Though overall EZH2 and HOTAIR expression levels were highly
correlated, the subset of cases with strong HOTAIR expression correlated with ER
and PR positivity, while the subset of cases with strong EZH2 expression
correlated with an increased proliferation rate, ER and PR negativity, HER2
underexpression, and triple negativity. Co-expression of HOTAIR and EZH2 trended
with a worse outcome. In matched primary and metastatic cancers, both HOTAIR and
EZH2 had increased expression in the metastatic carcinomas. This is the first
study to show that RNA in situ hybridization of formalin fixed paraffin-embedded
clinical material can be used to measure levels of long non-coding RNAs. This
approach offers a method to make observations on lncRNAs that may influence the
cancer epigenome in a tissue-based technique. OBJECTIVE: To study the expression patterns of long noncoding ribonucleic acid
(RNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and the
cell proliferation inhibition, apoptosis, and motility changes induced by
silencing MALAT1 in urothelial carcinoma of the bladder.
MATERIALS AND METHODS: The expression levels of MALAT1 were determined using
real-time quantitative polymerase chain reaction in cancerous tissues and paired
normal tissues in a total of 36 patients with urothelial carcinoma of the
bladder. Expression differences were analyzed according to the grade and stage.
Bladder urothelial carcinoma T24 and 5637 cells were transfected with MALAT1
small interfering RNA or negative control small interfering RNA. The cell
proliferation changes of the transfected bladder urothelial carcinoma cells were
determined using the MTT assay. Apoptosis caused by silencing MALAT1 was
evaluated using the flow cytometry assay and enzyme-linked immunosorbent assay.
The motility changes induced by silencing MALAT1 were measured using the wound
healing assay.
RESULTS: MALAT1 was upregulated in bladder urothelial carcinoma compared with
matched normal urothelium (P=.008). The MALAT1 expression levels were greater in
high-grade carcinomas than in low-grade carcinoma (P=.001). The MALAT1
expression levels were greater in invasive carcinoma than in noninvasive
carcinoma (P=.018). Cell proliferation inhibition, increased apoptosis, and
decreased motility were observed in MALAT1 small interfering RNA-transfected
bladder urothelial carcinoma T24 and 5637 cells.
CONCLUSION: MALAT1 plays an oncogenic role in urothelial carcinoma of the
bladder. Silencing MALAT1 is a potential novel therapeutic approach for this
cancer. It is well known that upon stress, the level of the tumor suppressor p53 is
remarkably elevated. However, despite extensive studies, the underlying
mechanism involving important inter-players for stress-induced p53 regulation is
still not fully understood. We present evidence that the human lincRNA-RoR (RoR)
is a strong negative regulator of p53. Unlike MDM2 that causes p53 degradation
through the ubiquitin-proteasome pathway, RoR suppresses p53 translation through
direct interaction with the heterogeneous nuclear ribonucleoprotein I (hnRNP I).
Importantly, a 28-base RoR sequence carrying hnRNP I binding motifs is essential
and sufficient for p53 repression. We further show that RoR inhibits
p53-mediated cell cycle arrest and apoptosis. Finally, we demonstrate a RoR-p53
autoregulatory feedback loop where p53 transcriptionally induces RoR expression.
Together, these results suggest that the RoR-hnRNP I-p53 axis may constitute an
additional surveillance network for the cell to better respond to various
stresses. CRNDE is the gene symbol for Colorectal Neoplasia Differentially Expressed
(non-protein-coding), a long non-coding RNA (lncRNA) gene that expresses
multiple splice variants and displays a very tissue-specific pattern of
expression. CRNDE was initially identified as a lncRNA whose expression is
highly elevated in colorectal cancer, but it is also upregulated in many other
solid tumors and in leukemias. Indeed, CRNDE is the most upregulated lncRNA in
gliomas and here, as in other cancers, it is associated with a "stemness"
signature. CRNDE is expressed in specific regions within the human and mouse
brain; the mouse ortholog is high in induced pluripotent stem cells and
increases further during neuronal differentiation. We suggest that CRNDE is a
multifunctional lncRNA whose different splice forms provide specific functional
scaffolds for regulatory complexes, such as the polycomb repressive complex 2
(PRC2) and CoREST chromatin-modifying complexes, which CRNDE helps pilot to
target genes. Recent high-throughput transcript discoveries have yielded a growing recognition
of long intergenic non-coding RNAs (lincRNAs), a class of arbitrarily defined
transcripts (>200 nt) that are primarily produced from the intergenic space.
lincRNAs have been increasingly acknowledged for their expressional dynamics and
likely functional associations with cancers. However, differential gene dosage
of lincRNA genes between cancer genomes is less studied. By using the
high-density Human Omni5-Quad BeadChips (Illumina), we investigated genomic copy
number aberrations in a set of seven tumor-normal paired primary human mammary
epithelial cells (HMECs) established from patients with invasive ductal
carcinoma. This Beadchip platform includes a total of 2,435,915 SNP loci
dispersed at an average interval of ~700 nt throughout the intergenic region of
the human genome. We mapped annotated or putative lincRNA genes to a subset of
332,539 SNP loci, which were included in our analysis for lincRNA-associated
copy number variations (CNV). We have identified 122 lincRNAs, which were
affected by somatic CNV with overlapped aberrations ranging from 0.14% to 100%
in length. lincRNA-associated aberrations were detected predomitly with copy
number losses and preferential clustering to the ends of chromosomes.
Interestingly, lincRNA genes appear to be less susceptible to CNV in comparison
to both protein-coding and intergenic regions (CNV affected segments in
percentage: 1.8%, 37.5%, and 60.6%, respectively). In summary, our study
established a novel approach utilizing high-resolution SNP array to identify
lincRNA candidates, which could functionally link to tumorigenesis, and provide
new strategies for the diagnosis and treatment of breast cancer. Identification of new nasopharyngeal carcinoma (NPC) biomarkers is of great
clinical value for the diagnosis and treatment of NPC. HOTAIR, a cancer-related
long non-coding RNA, was tested and its prognostic value for NPC was evaluated.
As determined using in situ hybridization (ISH), 91 of 160 (56.87%)
paraffin-embedded NPC biopsies showed high expression levels of HOTAIR (staining
index score ≥ 6). HOTAIR was upregulated in tumors with a large size
(P = 0.021), more advanced clinical stage (P = 0.012) and increased lymph node
tumor burden (P = 0.005). Quantified using real-time PCR, HOTAIR expression
levels in fresh tissue and paraffin-embedded samples were 5.2 ~ 48.4-fold higher
compared with non-cancer tissue samples. Moreover, HOTAIR expression levels
increased with clinical stage progression, which was consistent with ISH
findings in the paraffin-embedded tissue. Most importantly, NPC patients with
higher HOTAIR levels had a poor prognosis for overall survival using univariate
and multivariate analysis. In addition, HOTAIR mediated the migration, invasion
and proliferation of NPC cells in vitro. HOTAIR is a potential biomarker for the
prognosis of NPC, and dysregulation of HOTAIR might play an important role in
NPC progression. lncRNA H19 is essential for human tumor growth. However, little is known about
whether H19 regulates bladder cancer metastasis. Here we found that H19 levels
are remarkably increased in bladder cancer tissues, and upregulated H19 promotes
bladder cancer cell migration in vitro and in vivo. H19 is associated with
enhancer of zeste homolog 2 (EZH2), and that this association results in
Wnt/β-catenin activation and subsequent downregulation of E-cadherin. A
significant negative correlation is also observed between H19 levels and E-cad
levels in vivo. These data suggest that upregulated H19 enhances bladder cancer
metastasis by associating with EZH2 and inhibiting E-cad expression. Recently, long noncoding RNAs (lncRNAs) were found to be dysregulated in a
variety of tumors. However, it remains unknown how and through what molecular
mechanisms the expression of lncRNAs is controlled. In this study, we found that
the lncRNA Low Expression in Tumor (lncRNA-LET) was generally downregulated in
hepatocellular carcinomas, colorectal cancers, and squamous-cell lung
carcinomas. We demonstrated that hypoxia-induced histone deacetylase 3 repressed
lncRNA-LET by reducing the histone acetylation-mediated modulation of the
lncRNA-LET promoter region. Interestingly, the downregulation of lncRNA-LET was
found to be a key step in the stabilization of nuclear factor 90 protein, which
leads to hypoxia-induced cancer cell invasion. Moreover, the relationship among
hypoxia, histone acetylation disorder, low lncRNA-LET expression level, and
metastasis was found in clinical hepatocellular carcinoma samples. These results
advance our understanding of the role of lncRNA-LET as a regulator of hypoxia
signaling and offer new avenues for therapeutic intervention against cancer
progression. |
Explain the concept proteostasis. | Protein homeostasis, or proteostasis, refers to a proper balance between synthesis, maturation, and degradation of cellular proteins. Disruption of proteostasis is implicated in aging and the pathogenesis of numerous degenerative diseases. | Protein homeostasis, proteostasis, is essential to understand cell function.
Protein degradation is a crucial component of the proteostatic mechanisms of the
cell. Experiments on protein degradation are nowadays present in many
investigations in the field of molecular and cell biology. In the present paper,
we focus on the different experimental approaches to study protein degradation
and present a critical appraisal of the results derived from steady-state and
kinetic experiments using detection of unlabelled and labelled protein
methodologies with a proteostatic perspective. This perspective allows
pinpointing the limitations in interpretation of results and the need of further
experiments and/or controls to establish "definitive evidence" for the role of
protein degradation in the proteostasis of a given protein or the entire
proteome. We also provide a spreadsheet for simple calculations of mRNA and
protein decays for mimicking different experimental conditions and a checklist
for the analysis of experiments dealing with protein degradation studies that
may be useful for researchers interested in the area of protein turnover. Although the sequence of a protein largely determines its function, proteins can
adopt different folding states in response to changes in the environment, some
of which may be deleterious to the organism. All organisms--Bacteria, Archaea
and Eukarya--have evolved a protein homeostasis, or proteostasis, network
comprising chaperones and folding factors, degradation components, signalling
pathways and specialized compartmentalized modules that manage protein folding
in response to environmental stimuli and variation. Surveying the origins of
proteostasis networks reveals that they have co-evolved with the proteome to
regulate the physiological state of the cell, reflecting the unique stresses
that different cells or organisms experience, and that they have a key role in
driving evolution by closely managing the link between the phenotype and the
genotype. Maintaining correct cellular function is a fundamental biological process for
all forms of life. A critical aspect of this process is the maintece of
protein homeostasis (proteostasis) in the cell, which is largely performed by a
group of proteins, referred to as the protein quality control (PQC) network.
This network of proteins, comprised of chaperones and proteases, is critical for
maintaining proteostasis not only during favourable growth conditions, but also
in response to stress. Indeed proteases play a crucial role in the clearance of
unwanted proteins that accumulate during stress, but more importantly, in the
activation of various different stress response pathways. In bacteria, the cells
response to stress is usually orchestrated by a specific transcription factor
(sigma factor). In Escherichia coli there are seven different sigma factors,
each of which responds to a particular stress, resulting in the rapid expression
of a specific set of genes. The cellular concentration of each transcription
factor is tightly controlled, at the level of transcription, translation and
protein stability. Here we will focus on the proteolytic regulation of two sigma
factors (σ(32) and σ(S)), which control the heat and general stress response
pathways, respectively. This review will also briefly discuss the role
proteolytic systems play in the clearance of unwanted proteins that accumulate
during stress. The biological functions of proteins are governed by their three-dimensional
fold. Protein folding, maintece of proteome integrity, and protein
homeostasis (proteostasis) critically depend on a complex network of molecular
chaperones. Disruption of proteostasis is implicated in aging and the
pathogenesis of numerous degenerative diseases. In the cytosol, different
classes of molecular chaperones cooperate in evolutionarily conserved folding
pathways. Nascent polypeptides interact cotranslationally with a first set of
chaperones, including trigger factor and the Hsp70 system, which prevent
premature (mis)folding. Folding occurs upon controlled release of newly
synthesized proteins from these factors or after transfer to downstream
chaperones such as the chaperonins. Chaperonins are large, cylindrical complexes
that provide a central compartment for a single protein chain to fold unimpaired
by aggregation. This review focuses on recent advances in understanding the
mechanisms of chaperone action in promoting and regulating protein folding and
on the pathological consequences of protein misfolding and aggregation. Misfolding and aggregation of proteins have a negative impact on all living
organisms. In recent years, aggregation has been studied in detail due to its
involvement in neurodegenerative diseases, including Alzheimer's, Parkinson's
and Huntington's diseases, and type II diabetes--all associated with
accumulation of amyloid fibrils. This research highlighted the central
importance of protein homeostasis, or proteostasis for short, defined as the
cellular state in which the proteome is both stable and functional. It
implicates an equilibrium between synthesis, folding, trafficking, aggregation,
disaggregation and degradation. In accordance with the eukaryotic systems, it
has been documented that protein aggregation also reduces fitness of bacterial
cells, but although our understanding of the cellular protein quality control
systems is perhaps most detailed in bacteria, the use of bacterial proteostasis
as a drug target remains little explored. Here we describe protein aggregation
as a normal physiological process and its role in bacterial virulence and we
shed light on how bacteria defend themselves against the toxic threat of
aggregates. We review the impact of aggregates on bacterial viability and look
at the ways that bacteria use to maintain a balance between aggregation and
functionality. The proteostasis in bacteria can be interrupted via
overexpression of proteins, certain antibiotics such as aminoglycosides, as well
as antimicrobial peptides--all leading to loss of cell viability. Therefore
intracellular protein aggregation and disruption of proteostatic balance in
bacteria open up another strategy that should be explored towards the discovery
of new antimicrobials. Maintaining the dynamic proteome of a living cell in the face of an
ever-changing environment depends on a fine-tuned balance of protein synthesis
and protein degradation. Molecular chaperones exert key functions during protein
homeostasis (proteostasis). They associate with nonnative client proteins
following synthesis or damage and facilitate client sorting and folding. When
client proteins are terminally misfolded, chaperones cooperate with protein
degradation systems to dispose of such clients. This dual proteostasis activity
of chaperones is essential for maintaining cell function under normal growth
conditions and becomes even more important under stress conditions such as heat
and oxidative stress. The recent identification of chaperone-assisted selective
autophagy (CASA) as a tension-induced autophagy pathway highlights the critical
role of molecular chaperones in mechanically strained cells and tissues. The
CASA complex, assembled by the cochaperone BAG3, coordinates protein degradation
and protein synthesis in response to mechanical force. Here we describe the
composition and function of this chaperone complex in mammals and discuss its
relevance for tissue homeostasis and the regulation of cell adhesion, migration
and proliferation. We provide a unifying concept for the function of BAG3, which
integrates its involvement in muscle maintece, tumor formation and virus
infection. 1. Protein homeostasis, or proteostasis, refers to a proper balance between
synthesis, maturation, and degradation of cellular proteins. A growing body of
evidence suggests that the ribosome serves as a hub for co-translational
folding, chaperone interaction, degradation, and stress response. Accordingly,
in addition to the chaperone network and proteasome system, the ribosome has
emerged as a major factor in protein homeostasis. Recent work revealed that high
rates of elongation of translation negatively affect both the fidelity of
translation and the co-translational folding of nascent polypeptides.
Accordingly, by slowing down translation one can significantly improve protein
folding. In this review, we discuss how to target translational processes to
improve proteostasis and implications in treating protein misfolding diseases. |
Which gene test can be used for the X-linked myotubular myopathy? | Genetic testing of the MTM1 gene can be used for the X-linked myotubular myopathy. | The research work presented at this the 2nd Workshop of the International
Consortium on X-linked Myotubular Myopathy has clearly shown the benefits to be
gained from a multinational research consortium with a common interest in
identifying and cloning the MTM1 gene. The clinicians have rapid access to
knowledge about the current state of the detailed physical map encompassing the
disease gene, which is of particular importance when asked to carry out a
linkage-based carrier risk assessment in such families, and the molecular
geneticists benefit by having access to a large panel of samples from clinically
well-documented XMTM patients, and their families, for the rapid testing of any
new potential candidate genes. Strategies for the rapid exchange of information
and material between members of the consortium to facilitate the cloning of the
MTM gene were generated in the hope that the next Workshop will see the
consortium discussing the clinical and histological implications of the
mutations found. To this end it was decided to set up a Register, based in
Cardiff, of all XMTM patients from whom tissue and DNA samples had been made
available to the consortium. A decision was also made to collect samples from
the very rare families with possible autosomal MTM for future study. X-linked recessive myotubular myopathy (XLMTM; MTM1) is a severe neonatal
disorder often causing perinatal death of the affected males. The responsible
gene, designated MTM1, was localized to proximal Xq28 and recently isolated. The
characterization of MTM1 allowed us to screen for causing mutations in three
families, previously investigated by linkage analysis. Using exon amplification,
single strand conformation polymorphism, and subsequent sequencing analysis,
three new mutations and their mutational origin were characterized by analyzing
10 exons. An acceptor splice site and a frameshift mutation were correlated with
the concurrent appearance of XLMTM in two families. A third intronic mutation
was also analyzed by reverse transcription PCR and revealed a cryptic splice
site mutation cosegregating with the presumed XLMTM haplotype in the third
family. These results further support the implication of the MTM1 gene in XLMTM
and allow efficient and reliable carrier and prenatal diagnosis in these
families. Direct mutational diagnosis of families at risk in combination with
haplotype analysis avoid the drawbacks using only linkage analysis, make genetic
counselling far more reliable, and early clinical management of this disease
more appropriate. Moreover, pedigree analyses provide first information on de
novo mutation frequency in this newly identified human disease gene. X-linked myotubular myopathy (XLMTM) is a severe congenital muscle disorder due
to mutations in the MTM1 gene. The corresponding protein, myotubularin, contains
the consensus active site of tyrosine phosphatases (PTP) but otherwise shows no
homology to other phosphatases. Myotubularin is able to hydrolyze a synthetic
analogue of tyrosine phosphate, in a reaction inhibited by orthovanadate, and
was recently shown to act on both phosphotyrosine and phosphoserine. This gene
is conserved down to yeast and strong homologies were found with human ESTs,
thus defining a new dual specificity phosphatase (DSP) family. We report the
presence of novel members of the MTM gene family in Schizosaccharomyces pombe,
Caenorhabditis elegans, zebrafish, Drosophila, mouse and man. This represents
the largest family of DSPs described to date. Eight MTM-related genes were found
in the human genome and we determined the chromosomal localization and
expression pattern for most of them. A subclass of the myotubularin homologues
lacks a functional PTP active site. Missense mutations found in XLMTM patients
affect residues conserved in a Drosophila homologue. Comparison of the various
genes allowed construction of a phylogenetic tree and reveals conserved residues
which may be essential for function. These genes may be good candidates for
other genetic diseases. X-linked recessive myotubular myopathy (XLMTM) is a very severe congenital
muscular disease characterised by an impaired maturation of muscle fibres, and
caused by defects in the MTM1 gene. This gene defines a new family of putative
tyrosine phosphatases conserved through evolution. We have determined intronic
flanking sequences for all the 15 exons to facilitate the detection of mutations
in patients and genetic counselling. We characterised a new polymorphic marker
in the immediate vicinity of the gene, which might prove useful for linkage
analysis. Sequencing of the TATA-less predicted promoter provides the basis for
transcriptional regulatory studies. X-linked myotubular myopathy (XLMTM) is a congenital muscular disease
characterized by severe hypotonia and generalized muscle weakness, leading in
most cases to early postnatal death. The gene responsible for the disease, MTM1,
encodes a dual specificity phosphatase, named myotubularin, which is highly
conserved throughout evolution. To date, 139 MTM1 mutations in independent
patients have been reported, corresponding to 93 different mutations. In this
report we describe the identification of 21 mutations (14 novel) in XLMTM
patients. Seventeen mutations are associated with a severe phenotype in males,
with death occurring mainly before the first year of life. However, four
mutations-three missense (R241C, I225T, and novel mutation P179S) and one
single-amino acid deletion (G294del)-were found in patients with a much milder
phenotype. These patients, while having a severe hypotonia at birth, are still
alive at the age of 4, 7, 13, and 15 years, respectively, and display mild to
moderate muscle weakness. Mutations in the MTM1 gene cause X-linked recessive myotubular myopathy (XLMTM;
MIM310400). Myotubularin, the implicated protein, is a phosphoinositide
phosphatase that belongs to a large protein family conserved through evolution
that also includes the antiphosphatase Sbfl and the protein hMTMR2 mutated in
Charcot-Marie-Tooth type 4B. Myotubularin is detectable in a variety of cell
lines by immunoprecipitation followed by Western blotting. We screened 29
independant patients with XLMTM phenotype and four with centronuclear myopathy.
87% (21/24) of patients with known MTM1 mutations showed abnormal myotubularin
levels, including some with missense mutations. Moreover, myotubularin was also
undetectable in a patient for whom no mutation could be identified by SSCP
screening. The centronuclear cases investigated have a normal level of protein,
suggesting that the centronuclear form is not the result of a decrease in
myotubularin level. Thus, immunoprecipitation of myotubularin from cultured
cells represents a rapid and helpful method for classifying those cases where no
mutation was found. On the other hand, the amount of expression may be of
diagnostic value for disease course in patients with a mutation. Myotubularin is a ubiquitously expressed phosphatase that acts on
phosphatidylinositol 3-monophosphate [PI(3)P], a lipid implicated in
intracellular vesicle trafficking and autophagy. It is encoded by the MTM1 gene,
which is mutated in X-linked myotubular myopathy (XLMTM), a muscular disorder
characterized by generalized hypotonia and muscle weakness at birth leading to
early death of most affected males. The disease was proposed to result from an
arrest in myogenesis, as the skeletal muscle from patients contains hypotrophic
fibers with centrally located nuclei that resemble fetal myotubes. To understand
the physiopathological mechanism of XLMTM, we have generated mice lacking
myotubularin by homologous recombination. These mice are viable, but their
lifespan is severely reduced. They develop a generalized and progressive
myopathy starting at around 4 weeks of age, with amyotrophy and accumulation of
central nuclei in skeletal muscle fibers leading to death at 6-14 weeks.
Contrary to expectations, we show that muscle differentiation in knockout mice
occurs normally. We provide evidence that fibers with centralized myonuclei
originate mainly from a structural maintece defect affecting
myotubularin-deficient muscle rather than a regenerative process. In addition,
we demonstrate, through a conditional gene-targeting approach, that skeletal
muscle is the primary target of murine XLMTM pathology. These mutant mice
represent animal models for the human disease and will be a valuable tool for
understanding the physiological role of myotubularin. Myotubular myopathy is a well-defined entity within the centronuclear myopathy
subgroup of congenital myopathies. The authors present a patient with the most
severe X-linked recessive type (XLMTM). A baby boy presented at birth with
severe hypotonia, weak spontaneous movements, arthrogryposis, and respiratory
insufficiency. Muscle biopsy showed features of myotubular myopathy. The
diagnosis was confirmed and further specified by genetic analysis, revealing a
novel frameshift mutation (1314-1315insT) of the myotubularin-coding MTM1 gene.
This case underlines the importance of interdisciplinary analysis of congenital
muscle diseases, including histomorphological and genetic investigations. INTRODUCTION: X-linked myotubular myopathy (XLMTM), a recessive disorder, is
caused by mutations affecting the myotubulatin (MTM1) gene located on the X
chromosome. Most of the affected males die in the early postnatal period whereas
female carriers are usually asymptomatic.
CASE REPORTS: We report a family in which two females (45 and 27 years old) in
two different generations, presented unilateral weakness which had worsened
since adolescence, and one 48-year-old woman presented minimal symptoms. In
agreement with the computed tomography and magnetic resoce imaging findings,
the EMG was compatible with myopathy. Serum creatine kinase was elevated in the
second patient. The histological study showed centronuclear myopathy aspects,
more severe in the second patient. Both presented c.1420C>T, p.Arg474X in exon
13 of the MTM1 gene, whereas the third patients with less pronounced
manifestation, had a skewed pattern of X chromosome inactivation.
DISCUSSION: Symptomatic female carriers of XLMTM can present with asymmetric
malformations, which must be distinguished from an autosomal-domit
centronuclear myopathy.
CONCLUSION: Unilateral presentation of weakness cannot rule out a diagnosis of
myopathy. Detection of symptomatic female carriers of an X linked recessive
disease, with a severe presentation in males, is important for genetic
counselling. Myotubular myopathy (XLMTM, OMIM 310400) is a severe congenital muscular disease
due to mutations in the myotubularin gene (MTM1) and characterized by the
presence of small myofibers with frequent occurrence of central nuclei.
Myotubularin is a ubiquitously expressed phosphoinositide phosphatase with a
muscle-specific role in man and mouse that is poorly understood. No specific
treatment exists to date for patients with myotubular myopathy. We have
constructed an adeno-associated virus (AAV) vector expressing myotubularin in
order to test its therapeutic potential in a XLMTM mouse model. We show that a
single intramuscular injection of this vector in symptomatic Mtm1-deficient mice
ameliorates the pathological phenotype in the targeted muscle. Myotubularin
replacement in mice largely corrects nuclei and mitochondria positioning in
myofibers and leads to a strong increase in muscle volume and recovery of the
contractile force. In addition, we used this AAV vector to overexpress
myotubularin in wild-type skeletal muscle and get insight into its localization
and function. We show that a substantial proportion of myotubularin associates
with the sarcolemma and I band, including triads. Myotubularin overexpression in
muscle induces the accumulation of packed membrane saccules and presence of
vacuoles that contain markers of sarcolemma and T-tubules, suggesting that
myotubularin is involved in plasma membrane homeostasis of myofibers. This study
provides a proof-of-principle that local delivery of an AAV vector expressing
myotubularin can improve the motor capacities of XLMTM muscle and represents a
novel approach to study myotubularin function in skeletal muscle. Mutations in the gene encoding the phosphoinositide phosphatase myotubularin 1
protein (MTM1) are usually associated with severe neonatal X-linked myotubular
myopathy (XLMTM). However, mutations in MTM1 have also been recognized as the
underlying cause of "atypical" forms of XLMTM in newborn boys, female infants,
female manifesting carriers and adult men. We reviewed systematically the
biopsies of a cohort of patients with an unclassified form of centronuclear
myopathy (CNM) and identified four patients presenting a peculiar histological
alteration in some muscle fibers that resembled a necklace ("necklace fibers").
We analyzed further the clinical and morphological features and performed a
screening of the genes involved in CNM. Muscle biopsies in all four patients
demonstrated 4-20% of fibers with internalized nuclei aligned in a basophilic
ring (necklace) at 3 microm beneath the sarcolemma. Ultrastructurally, such
necklaces consisted of myofibrils of smaller diameter, in oblique orientation,
surrounded by mitochondria, sarcoplasmic reticulum and glycogen granules. In the
four patients (three women and one man), myopathy developed in early childhood
but was slowly progressive. All had mutations in the MTM1 gene. Two mutations
have previously been reported (p.E404K and p.R241Q), while two are novel; a
c.205_206delinsAACT frameshift change in exon 4 and a c.1234A>G mutation in exon
11 leading to an abnormal splicing and the deletion of nine amino acids in the
catalytic domain of MTM1. Necklace fibers were seen neither in DNM2- or
BIN1-related CNM nor in males with classical XLMTM. The presence of necklace
fibers is useful as a marker to direct genetic analysis to MTM1 in CNM. Skeletal muscle contraction is triggered by the excitation-contraction (E-C)
coupling machinery residing at the triad, a membrane structure formed by the
juxtaposition of T-tubules and sarcoplasmic reticulum (SR) cisternae. The
formation and maintece of this structure is key for muscle function but is
not well characterized. We have investigated the mechanisms leading to X-linked
myotubular myopathy (XLMTM), a severe congenital disorder due to loss of
function mutations in the MTM1 gene, encoding myotubularin, a phosphoinositide
phosphatase thought to have a role in plasma membrane homeostasis and
endocytosis. Using a mouse model of the disease, we report that Mtm1-deficient
muscle fibers have a decreased number of triads and abnormal longitudinally
oriented T-tubules. In addition, SR Ca(2+) release elicited by voltage-clamp
depolarizations is strongly depressed in myotubularin-deficient muscle fibers,
with myoplasmic Ca(2+) removal and SR Ca(2+) content essentially unaffected. At
the molecular level, Mtm1-deficient myofibers exhibit a 3-fold reduction in type
1 ryanodine receptor (RyR1) protein level. These data reveal a critical role of
myotubularin in the proper organization and function of the E-C coupling
machinery and strongly suggest that defective RyR1-mediated SR Ca(2+) release is
responsible for the failure of muscle function in myotubular myopathy. X-linked myotubular myopathy (MTM) is a severe neuromuscular disease of infancy
caused by mutations of MTM1, which encodes the phosphoinositide lipid
phosphatase, myotubularin. The Mtm1 knockout (KO) mouse has a severe phenotype
and its short lifespan (8 weeks) makes it a challenge to use as a model in the
testing of certain preclinical therapeutics. Many MTM patients succumb early in
life, but some have a more favorable prognosis. We used human genotype-phenotype
correlation data to develop a myotubularin-deficient mouse model with a less
severe phenotype than is seen in Mtm1 KO mice. We modeled the human c.205C>T
point mutation in Mtm1 exon 4, which is predicted to introduce the p.R69C
missense change in myotubularin. Hemizygous male Mtm1 p.R69C mice develop early
muscle atrophy prior to the onset of weakness at 2 months. The median survival
period is 66 weeks. Histopathology shows small myofibers with centrally placed
nuclei. Myotubularin protein is undetectably low because the introduced c.205C>T
base change induced exon 4 skipping in most mRNAs, leading to premature
termination of myotubularin translation. Some full-length Mtm1 mRNA bearing the
mutation is present, which provides enough myotubularin activity to account for
the relatively mild phenotype, as Mtm1 KO and Mtm1 p.R69C mice have similar
muscle phosphatidylinositol 3-phosphate levels. These data explain the basis for
phenotypic variability among human patients with MTM1 p.R69C mutations and
establish the Mtm1 p.R69C mouse as a valuable model for the disease, as its less
severe phenotype will expand the scope of testable preclinical therapies. X-linked myotubular myopathy (XLMTM) is a rare congenital myopathy, usually
characterized by severe hypotonia and respiratory insufficiency at birth, in
affected, male infants. The disease is causally associated with mutations in the
MTM1 gene, coding for phosphatase myotubularin. We report a severe case of XLMTM
with a novel mutation, at a donor splicing site (c.1467+1G) previously
associated with severe phenotype. The mutation was also identified in the
patient's mother, providing an opportunity for sound genetic counseling. INTRODUCTION: We established a colony of dogs that harbor an X-linked MTM1
missense mutation.Muscle from affected male dogs exhibits reduction and altered
localization of the MTM1 gene product, myotubularin, and provides a model
analogous to X-linked myotubular myopathy (XLMTM).
METHODS: We studied hindlimb muscle function in age-matched canine XLMTM
genotypes between ages 9 and 18 weeks.
RESULTS: By the end of the study, affected dogs produce only ∼15% of the torque
generated by normals or carriers (0.023 ± 0.005 vs. 0.152 ± 0.007 and 0.154 ±
0.003 N-m/kg body mass, respectively, P < 0.05) and are too weak to stand
unassisted. At this age, XLMTM dogs also demonstrate an abnormally low
twitch:tetanus ratio, a right-shifted torque-frequency relationship and an
increase in torque during repetitive stimulation (P < 0.05).
CONCLUSIONS: We hypothesize that muscle weakness results from impaired
excitation-contraction (E-C) coupling. Interventions that improve E-C coupling
might be translated from the XLMTM dog model to patients. BACKGROUND: Myotubular myopathy (MTM) is a congenital myopathy characterized by
centrally placed nuclei in muscle fibers. Mutations in the myotubularin 1 gene
(MTM1) have been identified in the most of the patients with the X-linked
recessive form.
CASE REPORT: This report describes two male infants with X-linked MTM (XLMTM).
Both patients presented with generalized hypotonia and respiratory difficulties
since birth. We did not perform a muscle biopsy in either patient, but their
conditions were diagnosed by genetic testing of MTM1. One splicing mutation,
c.63+1G>C, and a frame-shift mutation, c.473delA (p. Lys158SerfxX28), were
identified. Neither mutation has been reported previously.
CONCLUSIONS: Genetic testing for MTM1 is helpful for the differential diagnosis
of floppy male infants. We suggest that advanced molecular genetic testing may
permit a correct diagnosis while avoiding invasive procedures. Manipulation of the mouse genome by site-specific mutagenesis has been
extensively used to study gene function and model human disorders. Mouse models
of myotubular myopathy (XLMTM), a severe congenital muscular disorder due to
loss-of-function mutations in the MTM1 gene, have been generated by homologous
recombination and shown that myotubularin is essential for skeletal muscle.
However, since the Mtm1 deletion occurred constitutively or shortly after birth
in these mice, it is not known whether myotubularin is required during
adulthood, an important issue in the context of not only muscle biology but also
therapies. To delete the Mtm1 gene in adult muscle fibers, we constructed a
recombit adeno-associated vector (AAV) that expresses the Cre recombinase
under the muscle-specific desmin promoter. We report that a single injection of
this vector into muscles of 3-month-old Mtm1 conditional mice leads to a
myotubular myopathy phenotype with myofiber atrophy, disorganization of
organelle positioning, such as mitochondria and nuclei, T-tubule defects and
severe muscle weakness. In addition, our results show that MTM1-related atrophy
and dysfunction correlate with abnormalities in satellite cell number and
markers of autophagy, protein synthesis and neuromuscular junction transmission.
The expression level of atrogenes was also analyzed. Therefore, we provide a
valuable tissue model that recapitulates the main features of the disease, and
it is useful to study pathogenesis and evaluate therapeutic strategies. We
establish the proof-of-concept that myotubularin is required for the proper
function of skeletal muscle during adulthood, suggesting that therapies will be
required for the entire life of XLMTM patients. |
Is there a phylogenetic analysis for HIV? | In biology, phylogenetics is the study of evolutionary relationships among groups of organisms (e.g. species, populations), which are discovered through molecular sequencing data and morphological data matrices. The result of phylogenetic studies is a hypothesis about the evolutionary history of taxonomic groups: their phylogeny.
Phylogenetic analysis examines small differences in HIV’s genes using computational methods to calculate the genetic distance between strains. Unlike
human DNA, which remains stable for a lifetime, HIV’s RNA changes very rapidly, leading to a huge amount of genetic diversity. This diversity means that scientists, using phylogenetic analysis, have been able to ascertain where HIV comes from, as well as track the various strains of HIV that exist worldwide.
Based on results, there are found many studies on HIV phylogenetic analysis. | The South American human immunodeficiency virus type 1 (HIV-1) epidemic is
driven by several subtypes (B, C, and F1) and circulating and unique recombit
forms derived from those subtypes. Those variants are heterogeneously
distributed around the continent in a country-specific manner. Despite some
inconsistencies mainly derived from sampling biases and analytical constrains,
most of studies carried out in the area agreed in pointing out specificities in
the evolutionary dynamics of the circulating HIV-1 lineages. In this paper, we
covered the theoretical basis, and the application of bioinformatics methods to
reconstruct the HIV spatial-temporal dynamics, unveiling relevant information to
understand the origin, geographical dissemination and the current molecular
scenario of the HIV epidemic in the continent, particularly in the countries of
Southern Cone. To investigate the subtype distribution of human immunodeficiency virus-1(HIV-1)
infection among men who have sex with men (MSM) in Zhengzhou, He Province,
forty blood samples were collected from HIV-1 carriers, who acknowledged to have
sex with men. The complete gag gene was amplified by RT-PCR and nested-PCR and
sequenced. All sequences were edited by BioEdit and subtyped by genotyping
software. Phylogenetic analysis of gag gene were then performed using the MEGA
3.1 software, the gene distances were calculated by Distance program. There were
three different HIV-1 subtypes including B, CRF01-AE and CRF07-BC present among
twenty four MSMs in Zhengzhou. Genotyping results showed that 33.33% (8/24) were
B, 41.67% (10/24) were CRF01-AE and 25% (6/24) were CRF07-BC, and subtype
CRF01-AE had become the most prevalent HIV-1 subtype in Zhengzhou, He
province. In conclusion, recombit HIV-1 strains are circulating in He
province and the epidemiology is complicated. BACKGROUND: In Western Europe, a previously subtype B HIV-1 restricted area, BC
recombits have been rarely reported.
OBJECTIVE: To describe an outbreak of HIV-1 BC recombits in southern Italy.
STUDY DESIGN: We analyzed pol (protease/reverse transcriptase) sequences from
135 newly diagnosed HIV-1-infected patients during the years 2009-2011. For
phylogenetic relationships, sequences were aligned to the most recent reference
data set from the Los Alamos database using BioEdit (version 7.1.3). The
resulting alignment was analyzed with the Phylip package (version 3.67) building
a neighbor-joining tree based on the Kimura two-parameter substitution model.
The reliability of the tree topology was assessed through bootstrapping using
1000 replicates. The recombination pattern was characterized using SimPlot 3.5.1
and SplitsTree 4.
RESULTS: At phylogenetic analysis, 22 (16.2%) isolates whose sequences were not
unequivocally assigned to a pure subtype or known CRF, formed a distinct
monophyletic clade (100% of bootstrap value). For these isolates, the
recombination analysis identified a BC mosaic pattern with two breakpoints at
positions 2778±5 and 3162±8 (HXB2 numbering) which differed from those of known
BC CRFs. All patients from whom these sequences were derived were highly
educated youth Italians, 91% males and 82% MSM. Sequences of pol integrase,
gp120 and gp41 from these same patients were classified as C subtype.
CONCLUSIONS: This outbreak which further reflects the increasing heterogeneity
of HIV epidemic in our country is the first report of an Italian outbreak of a
BC recombit, possibly a novel candidate CRF. Viral quasispecies population dynamics between monocytes and T-lymphocytes were
analyzed in patients after highly active antiretroviral therapy (HAART)
interruption, during a follow-up of 3-6 months. V3 env region underwent
ultra-deep pyrosequencing. Co-receptor usage prediction was performed by
Position Specific Score Matrix Analysis. Phylogenetic trees were constructed to
evaluate the relationships between the variants. Gene flow was also
investigated. Even though at the moment of therapy interruption monocyte-derived
HIV-1 genomes presented higher genetic heterogeneity than that of T-lymphocytes,
at subsequent times, this difference in genetic heterogeneity disappeared, due
to different waves of expansion and reduction of quasispecies variability
associated with monocytes and T-lymphocytes. Phylogenetic analysis and gene flow
evaluation supported the hypothesis of extensive interchange of variants between
cellular compartments of the infection. A spread of proviral X4 lineages hidden
in monocytes to T cells was observed, but this was not associated with an
overall shift towards CXCR4 using variants during the observation period. In sub-Saharan Africa, cryptococcal meningitis (CM) continues to be a
predomit cause of AIDS-related mortality. Understanding virulence and
improving clinical treatments remain important. To characterize the role of the
fungal strain genotype in clinical disease, we analyzed 140 Cryptococcus
isolates from 111 Ugandans with AIDS and CM. Isolates consisted of 107
nonredundant Cryptococcus neoformans var. grubii strains and 8 C. neoformans
var. grubii/neoformans hybrid strains. Multilocus sequence typing (MLST) was
used to characterize genotypes, yielding 15 sequence types and 4 clonal
clusters. The largest clonal cluster consisted of 74 isolates. The results of
Burst and phylogenetic analysis suggested that the C. neoformans var. grubii
strains could be separated into three nonredundant evolutionary groups (Burst
group 1 to group 3). Patient mortality was differentially associated with the
different evolutionary groups (P = 0.04), with the highest mortality observed
among Burst group 1, Burst group 2, and hybrid strains. Compared to Burst group
3 strains, Burst group 1 strains were associated with higher mortality (P =
0.02), exhibited increased capsule shedding (P = 0.02), and elicited a more
pronounced Th(2) response during ex vivo cytokine release assays with
strain-specific capsule stimulation (P = 0.02). The results of these analyses
suggest that cryptococcal strain variation can be an important determit of
human immune responses and mortality.
IMPORTANCE: Cryptococcus neoformans is a common life-threatening human fungal
pathogen that is responsible for an estimated 1 million cases of meningitis in
HIV-infected patients annually. Virulence factors that are important in human
disease have been identified, yet the impacts of the fungal strain genotype on
virulence and outcomes of human infection remain poorly understood. Using an
analysis of strain variation based on in vitro assays and clinical data from
Ugandans living with AIDS and cryptococcal infection, we report that strain
genotype predicts the type of immune response and mortality risk. These studies
suggest that knowledge of the strain genotype during human infections could be
used to predict disease outcomes and lead to improved treatment approaches aimed
at targeting the specific combination of pathogen virulence and host response. BACKGROUND: HIV transmitted drug resistance (TDR) surveillance is usually
conducted by sampling from a large population. However, overall TDR prevalence
results may be inaccurate for many individual clinical setting. We analyzed HIV
genotypes at a tertiary care setting in Ottawa, Ontario in order to evaluate
local TDR patterns among sub-populations.
METHOD: Genotyping reports were digitized from ART naïve patients followed at
the Immunodeficiency Clinic at the Ottawa Hospital, between 2008 and 2010.
Quality controlled, digitized sequence data were assessed for TDR using the
Stanford HIV Database. Patient characteristics were analyzed according to TDR
patterns. Finally, a phylogenetic tree was constructed to elucidate the observed
pattern of HIV TDR.
RESULTS: Among the 155 clinic patients there was no statistically significantly
difference in demographics as compared to the Ontario provincial HIV population.
The clinic prevalence of TDR was 12.3%; however, in contrast to the data from
Ontario, TDR patterns were inverted with a 21% prevalence among MSM and 5.5%
among IDU. Furthermore, nearly 80% of the observed TDR was a D67N/K219Q pattern
with 87% of these infections arising from a distinct phylogenetic cluster.
CONCLUSIONS: Local patterns of TDR were distinct to what had been observed
provincially. Phylogenetic analysis uncovered a cluster of related infections
among MSM that appeared more likely to be recent infections. Results support a
paradigm of routine local TDR surveillance to identify the sub-populations under
care. Furthermore, the routine application of phylogenetic analysis in the TDR
surveillance context provides insights into how best to target prevention
strategies; and how to correctly measure outcomes. We report a novel HIV-1 circulating recombit form (CRF64_BC) that was
isolated from five epidemiologically unlinked HIV-infected persons in Yun
province. CRF64_BC was composed of subtype B and subtype C, with five short
subtype B segments inserted into the subtype C backbone. Phylogenetic analysis
demonstrated that the C subregion was correlated with the India C lineage, which
was transmitted into China in the early 1990s. The evolutionary history of the B
subregion was not as clear as the C subregion, as the short length of this
region yielded poor phylogenetic results. Dehong is considered the epicenter of
HIV-1 in China, and recombit strains such as CRF07_BC and CRF08_BC, which
also originated from this region, have spread widely in China. The newly emerged
CRF64_BC increases the complexity of the HIV epidemic in China and complicates
the development of subtype-specific tools against HIV transmission. BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) dual infection (DI) has
been associated with decreased CD4 T-cell counts and increased viral loads;
however, the frequency of intrasubtype DI is poorly understood. We used
ultradeep sequencing (UDS) to estimate the frequency of DI in a primary
infection cohort of predomitly men who have sex with men (MSM).
METHODS: HIV-1 genomes from longitudinal blood samples of recently infected,
therapy-naive participants were interrogated with UDS. DI was confirmed when
maximum sequence divergence was excessive and supported by phylogenetic
analysis. Coinfection was defined as DI at baseline; superinfection was
monoinfection at baseline and DI at a later time point.
RESULTS: Of 118 participants, 7 were coinfected and 10 acquired superinfection.
Superinfection incidence rate was 4.96 per 100 person-years (95% confidence
interval [CI], 2.67-9.22); 6 occurred in the first year and 4 in the second.
Overall cumulative prevalence of intrasubtype B DI was 14.4% (95% CI,
8.6%-22.1%). Primary HIV-1 incidence was 4.37 per 100 person-years (95% CI,
3.56-5.36).
CONCLUSIONS: Intrasubtype DI was frequent and comparable to primary infection
rates among MSM in San Diego; however, superinfection rates declined over time.
DI is likely an important component of the HIV epidemic dynamics, and
development of stronger immune responses to the initial infection may protect
from superinfection. |
What is the association between adiponectin and migraine? | There is evidence to suggest that adiponectin plays a role in migraine. Increase in body fat elevates adiponectin and leptin secretion which in turn impair inflammatory processes that could be contributing to migraine risk. In episodic migraine patients, adiponectin was associated with migraine severity and predictive of acute treatment response. Serum adiponectin levels are increased in women chronic daily headache sufferers. | Migraine is a common disorder, characterized by recurrent episodes of headache
and associated symptoms. The full pathophysiology of migraine is incompletely
delineated. Current theories suggest that it is a neurovascular disorder
involving cortical depression, neurogenic inflammation and vasodilation. Various
neuropeptides and cytokines have been implicated in the pathophysiology of
migraine including calcitonin gene-related peptide, interleukin (IL)-1, IL-6 and
tumour necrosis factor (TNF)-alpha. There is evidence demonstrating an
association between migraine and processes associated with inflammation,
atherosclerosis, immunity and insulin sensitivity. Similarly, adiponectin, an
adipocytokine secreted by adipose tissue, has protective roles against the
development of insulin resistance, dyslipidaemia and atherosclerosis and
exhibits anti-inflammatory properties. The anti-inflammatory activities of
adiponectin include inhibition of IL-6 and TNF-induced IL-8 formation, as well
as induction of the anti-inflammatory cytokines IL-10 and IL-1 receptor
antagonist. Adiponectin levels are also inversely correlated with C-reactive
protein (CRP), TNF-alpha and IL-6 levels. Likewise, recent studies have shown a
possible correlation between CRP, TNF-alpha and IL-6 and migraine attacks. In
addition, insulin sensitivity is impaired in migraine and obesity is a risk
factor for the transformation from episodic to chronic migraine. In this review
we discuss the basic science of adiponectin and its potential connection to the
pathophysiology of migraine. Future research may focus on how adiponectin levels
are potentially altered during migraine attacks, and how that information can be
potentially translated into migraine therapy. Migraine and obesity are associated in several ways. First, both are prevalent
and disabling disorders influenced by genetic and environmental risk factors.
Second, migraine with aura, as obesity, seems to be a risk factor for
cardiovascular events. Finally, large population-based studies suggest that
obesity is a risk factor for chronic migraine after adjusting for comorbidities.
In this article, we discuss plausible mechanisms that may account for this
association. Several of the inflammatory mediators that are increased in obese
individuals are important in migraine pathophysiology, including interleukins
and calcitonin gene-related peptide (CGRP). These mediators may increase the
frequency, severity, and duration of migraine attacks per se, which in turn
would cause central sensitization. Repeated central sensitization may be
associated with permanent neuronal damage close to the periaqueductal gray area,
with poor modulation to pain. Obesity is also a state of sympathetic activation,
which may contribute to increase in headache frequency. Furthermore, the levels
of adiponectin are decreased in obesity. At low but not normal levels,
adiponectin is nociceptive. Shared biologic predisposition may also play a major
role. Orexins modulate both pain and metabolism. Dysfunction in the orexins
pathways seems to be a risk factor for both conditions. Finally, conditions that
are comorbid to both states (e.g., depression, sleep apnea) may also make the
relationship between both diseases more complex. Although it has long been known that fasting or the consumption of certain foods
can trigger headaches, abdominal and total body obesity have only recently been
linked to migraine. Several adipocytokines appear to play an integral role in
feeding and obesity--and have also been linked to pain. Among these proteins are
adiponectin and leptin. The author reviews the regulation of adipose tissue and
feeding and provides an in-depth examination of adiponectin and leptin and their
association with migraine. Adipose tissue is a dynamic neuroendocrine organ that is involved in multiple
physiological and pathological processes, and when excessive, results in
obesity. Clinical and population-based data suggest that migraine and chronic
daily headache are associated with obesity, as estimated by anthropometric
indices. In addition, translational and basic science research shows multiple
areas of overlap between migraine pathophysiology and the central and peripheral
pathways regulating feeding. Specifically, neurotransmittors such as serotonin,
peptides such as orexin, and adipocytokines such as adiponectin and leptin have
been suggested to have roles in both feeding and migraine. In this article, we
first review the definition and ascertainment of obesity. This is followed by a
review of the clinical and population-based studies evaluating the associations
between obesity and chronic daily headache and migraine. We then discuss the
central and peripheral pathways involved in the regulation of feeding, where it
overlaps with migraine pathophysiology, and where future research may be headed
in light of these data. Metabolic syndrome (MetS) are consist of central obesity, diabetes, dyslipidemia
and hypertension. Previous studies have reported possible association of
migraine and MetS were reviewed. Migraine is a prevalent disabling disorder and
have been regarded as an episodic and functional disorder. However, recent
evidence suggests that in some cases, the disease may follow a chronic and
progressive course. On the basis of available evidence, obesity is considered to
be associated with migraine frequency and progression. The association between
diabetes and migraine is unclear. Similarly, association of migraine with
hypertension is also unclear. Female migraineurs commonly have an unfavorable
cholesterol profile, i.e. one with high total cholesterol and low HDL levels.
Obesity can be considered as a proinflammatory state in which increased
inflammatory mediators, vascular hyperreactivity, plasma calcitonin gene-related
peptide (CGRP) concentrations and decreased adiponectin concentrations are
observed. These alterations can cause an increase in the frequency of migraine
attacks developed of central sensitization, and thereafter, chronic migraine.
Migraine and obesity may share some neurobiological abnormalities. Orexins
modulate both pain and metabolism. Dysfunction in the orexin pathways seems to
be a risk factor for both conditions. The methylene-tetrahydrofolate reductase
(MTHFR) gene and the angiotensin converting enzyme (ACE) gene exhibit
polymorphism. C677Tmutation in the MTHFR gene and the D-allele of the ACE gene
are the shared risk factors for the development of migraine and cardiovascular
disease. Certain beta-blockers, Ca blockers, ACE inhibitors, and angionten II
receptor blocker (ARB) have excellent efficacy in migraine prophylaxis. The
pharmacological mechanism of these agents do not seem to stand on their
antihypertensive effect, but the other mechanism of action. Appropriate meal,
sleep, and exercise are important for the management of MetS and migraine
headaches. Topiramate is an anticonvulsant agent effective in the prophylaxis of migraine,
which also induces weight reduction by an unknown mechanism. We investigated the
effect of topiramate on metabolic and endocrine parameters in patients with
migraine independently of any intention to lose body weight. Six patients (26-61
years old, body mass indices [BMI] 20.9-32.1 kg/m(2)) with migraine were treated
with an average dose of 100 mg topiramate/day over a period of 20 weeks. The
following parameters were measured every 4-8 weeks: BMI, body fat proportion,
waist and hip circumference, HOMA insulin resistance, fasting serum-/plasma
concentrations of adiponectin, leptin, ghrelin, vascular endothelial growth
factor (VEGF), cortisol, interleukin-6 and tumor necrosis factor (TNF)-alpha.
Profound metabolic changes were observed for the whole treatment period.
Compared with the baseline value, 20 weeks of treatment reduced the BMI by
7.2+/-1.4%, body fat proportion by 11.6+/-3.6%, waist circumference by
4.2+/-1.2%, leptin by 39.2+/-6.5% and HOMA insulin resistance by 37.3+/-5%,
while adiponectin was increased by 69.9+/-17.3% (P<0.05, respectively). VEGF
concentrations increased during the week 2-4 by 177.4+/-39.4% (P<0.05) followed
by a continuous decrease. There were trends for a reduction in ghrelin
concentration, whereas cortisol, interleukin-6 and TNF-alpha values were
unchanged. In summary, in this small sample of migraine patients topiramate
treatment was associated with increased insulin sensitivity, increased
adiponectin concentration and a reduction of body fat in all treated patients.
The role of increased VEGF concentrations prior to these metabolic changes is
not clear and might, hypothetically, involve a centrally mediated effect of
topiramate on body weight regulation. AIM: To determine a possible relationship between migraine and body mass index.
METHODS: Migraine shows a wide spectrum of comorbidities, including
cardiocerebral, vascular, psychiatric, metabolic, neurological as well as other
pathologies. Recent researches suggest that obesity was significantly correlated
with migraine frequency and disability in children, as well as in adult
population studies. We reviewed data from the literature to clarify this
possible relationship.
RESULTS: Translational and basic science research shows multiple areas of
overlap between migraine pathophysiology and the central and peripheral pathways
regulating feeding. Specifically, neurotransmittors such as serotonin, peptides
such as orexin, and adipocytokines such as adiponectin and leptin have been
suggested to have roles in both feeding and migraine. A relationship between
migraine and body mass index exists, and therefore, interventions to modify body
mass index may provide a useful treatment model for investigating whether modest
weight loss reduces headache frequency and severity in obese migraineurs.
CONCLUSION: The effect of obesity and weight change on headache outcomes may
have important implications for clinical care. OBJECTIVE: To assess ictal adiponectin (ADP) levels before and after acute
abortive treatment in women episodic migraineurs.
METHODS: Peripheral blood specimens were collected from women episodic
migraineurs before and after acute abortive treatment with sumatriptan/naproxen
sodium vs placebo. Univariate and multivariate models were utilized to examine
the relationship between serum total ADP (T-ADP), ADP oligomers (high molecular
weight [HMW], middle molecular weight, and low molecular weight [LMW]-ADP), and
ADP ratio levels and pain severity. Paired t-tests and random intercept
longitudinal models were utilized to assess the mean changes in T-ADP, ADP
oligomers, and ratios over time in treatment responders and nonresponders.
RESULTS: Twenty participants (11 responders, 9 nonresponders) have been studied
to date. In all participants, increases in the HMW : LMW ADP ratio were
associated with an increase in pain severity. For every 1 point increase in the
HMW : LMW ratio, pain severity increased by 0.22 (Confidence Interval [CI]:
0.07, 0.37; P = .004). In contrast, for every 0.25 μg/mL increase in LMW-ADP,
pain severity decreased by 0.20 (CI: -0.41, -0.002; P = .047). In treatment
responders, T-ADP levels were reduced at 30 minutes (12.52 ± 3.4; P = .03), 60
minutes (12.32 ± 3.2; P = .017), and 120 minutes (12.65 ± 3.2; P = .016) after
treatment as compared with onset (13.48 ± 3.8). Additionally, in responders, the
HMW : LMW ratio level was greater at pain onset (3.70 ± 1.9 μg/mL) as compared
with nonresponders (2.29 ± 0.71 μg/mL), P = .050. Responders also showed a
decrease in the HMW : LMW ratio at 60 minutes (2.37 ± 1.1; P = .002) and 120
minutes (2.76 ± 1.4; P = .02) after treatment as compared with onset
(3.70 ± 1.9). These changes in responders remained significant after adjusting
for covariates, including measured body mass index (m-BMI). Although
nonresponders showed no significant changes in unadjusted T-ADP or ADP oligomer
or ratio levels, the HMW : LMW ratio was increased in nonresponders after
adjustments (P = .025).
CONCLUSION: In this pilot study of women episodic migraineurs, the HMW : LMW ADP
ratio level was associated with migraine severity and predictive of acute
treatment response. ADP and the HMW : LMW ratio of ADP represent potential novel
biomarkers and drug targets for episodic migraine. BACKGROUND: Obesity seems to be associated to migraine headache. Increase in
body fat, especially in gluteofemoral region, elevates adiponectin and leptin
secretion which in turn impair inflammatory processes that could be contributing
to migraine risk. This study was designed to assess the relationship between
body composition and risk of migraine for the first time.
METHODS: In this cross-sectional study, 1510 middle-aged women who were visited
in a weight reduction clinic of university were recruited. Migraine was
diagnosed with HIS criteria. Body composition parameters including total fat
mass (FATM), total fat free mass (FFM), truncal fat mass (TFATM), and truncal
fat free mass (TFFM) was assessed using bioelectric impedance. We further
assessed cardiovascular risk factors and smoking as confounding factors. To
determine the real association between different variables and risk of migraine,
the associations were adjusted by multivariate logistic regression analysis.
RESULTS: Elevation in fasting blood sugar, total cholesterol, LDL cholesterol,
FFM, TFFM, and waist-to-hip ratio increased the risk of migraine. When the
associations were adjusted for other factors, only the association between
migraine and FFM remained statistically significant.
CONCLUSION: Lower FFM increased the risk of migraine in overweight and obese
individuals. In the other words, higher fat free mass could be a protective
factor for migraine. Although the pathogenesis of migraine is very complex and has not been
thoughtfully elucidated, general consensus exists to date that this condition
should be considered a primary neurovascular disorder with an important
inflammatory component. Owing to epidemiological evidence of increased risk of
migraine in overweight and obese subjects and to the inverse relationship that
exists between serum adiponectin concentration and obesity, we performed an
electronic search on Medline, Scopus and Web of Science, using the keywords
"migraine" and "adiponectin" with no language or date restriction to explore the
existence of an association between serum adiponectin and migraine. According to
our search criteria, five studies were finally included in this systematic
review, four cross-sectional (totaling 300 patients with migraine and 177
controls) and one interventional. Collectively, the results of our analysis
suggest that a link between serum adiponectin and migraine remains elusive, at
the best. The four cross-sectional studies failed to find any significant
association, whereas the outcome of the single interventional study reported a
rather modest variation of serum adiponectin concentration in a very limited
sample size. Further larger studies are needed to firmly establish the existence
of a relationship between adiponectin metabolism and migraine. BACKGROUND AND OBJECTIVES: Inflammatory mediators, including adipokines, have
been studied in migraine pathophysiology; however, their role is not yet well
established. The aim of the present study was to investigate adiponectin (ADP)
and its association with clinical parameters and psychiatric comorbidities in
migraine patients compared with controls.
METHODS: This was a cross sectional study including migraine patients and
controls. Beck depression and anxiety inventories, Headache impact test, and
Allodynia symptom checklist were recorded. Adiponectin was measured by ELISA.
RESULTS: Sixty-eight migraine patients and sixty-five controls without headache
were included. The ADP levels were significantly higher among patients with
migraine (43.6±11.8 versus 36.6±9.7 ng/mL, P<0.0001). Adiponectin levels were
not correlated with depression and anxiety scores, as well as with migraine
severity and allodynia scores.
CONCLUSION: ADP levels were raised in migraine, independently of psychiatric
comorbidities, migraine impact, and allodynia. Obesity and migraine are both highly prevalent disorders in the general
population, influenced by genetic and environmental risk factors. In recent
studies, obesity was found to be a strong risk factor for transformed migraine
and, among migraineurs, obesity was associated with frequent headaches and
higher disability scores. Suggested mechanisms included: (i) obesity as a
pro-inflammatory state may be associated with neurovascular inflammation in
patients with migraine; (ii) elevated levels of plasma calcitonin gene-related
peptide (CGRP) in obese individuals may play a role as an important
post-synaptic mediator of trigeminovascular inflammation in migraine; (iii)
dismodulation in the hypothalamic neuropeptide, orexin, in obese persons may be
associated with increased susceptibility to neurogenic inflammation causing
migraine attacks; and (iv) leptin and adiponectin can activate proinflammatory
cytokine release that is involved in the pathogenesis of migraine. In addition,
both conditions are associated with psychiatric co-morbidities, such as
depression and anxiety, that can further increase headache frequency and
disability. Therefore, the effect of obesity on migraine outcome is important.
Weight and BMI should be measured and calculated in all children presenting with
migraine, and weight control should be a part of the treatment. Author information:
(1)From the Department of Neurology (J.L.D.), Yale University School of
Medicine, New Haven, CT; the Department of Epidemiology (A.L.C.S.), Johns
Hopkins University School of Public Health; the Department of Neurology (R.F.G.,
B.L.P.), Johns Hopkins University School of Medicine, Baltimore, MD; Team
Neuroepidemiology (T.K.), INSERM Research Center for Epidemiology and
Biostatistics (U897), Bordeaux; France College of Health Sciences (T.K.),
University of Bordeaux; the School of Public Health, Division of Epidemiology
and Community Health (J.S.P.), University of Minnesota, Minneapolis; the
Departments of Biostatistics (D.J.C.) and Epidemiology (K.M.R.), University of
North Carolina at Chapel Hill; Social and Scientific Systems, Inc. (K.M.R.),
Durham, NC; and the Department of Epidemiology (M.A.W.), Harvard School of
Public Health, Boston, MA.
(2)From the Department of Neurology (J.L.D.), Yale University School of
Medicine, New Haven, CT; the Department of Epidemiology (A.L.C.S.), Johns
Hopkins University School of Public Health; the Department of Neurology (R.F.G.,
B.L.P.), Johns Hopkins University School of Medicine, Baltimore, MD; Team
Neuroepidemiology (T.K.), INSERM Research Center for Epidemiology and
Biostatistics (U897), Bordeaux; France College of Health Sciences (T.K.),
University of Bordeaux; the School of Public Health, Division of Epidemiology
and Community Health (J.S.P.), University of Minnesota, Minneapolis; the
Departments of Biostatistics (D.J.C.) and Epidemiology (K.M.R.), University of
North Carolina at Chapel Hill; Social and Scientific Systems, Inc. (K.M.R.),
Durham, NC; and the Department of Epidemiology (M.A.W.), Harvard School of
Public Health, Boston, MA. [email protected]. |
Which phenomenon is described as oncogene addiction? | Oncogene addiction describes the curious acquired dependence of tumor cells on an activated oncogene for their survival and/or proliferation, a phenomenon that has important implications for the success of targeted cancer therapies. However, the mechanisms explaining oncogene addiction remain elusive. We propose that addiction may be an illusion generated as a consequence of differential attenuation rates of prosurvival and proapoptotic signals emanating from an oncoprotein acutely following its inactivation. According to this model, which we call oncogenic shock, prosurvival signals dissipate quickly on oncoprotein inactivation whereas proapoptotic signals linger sufficiently long to commit the cell to an apoptotic death. | "Oncogene addiction" describes the curious acquired dependence of tumor cells on
an activated oncogene for their survival and/or proliferation, a phenomenon that
has important implications for the success of targeted cancer therapies.
However, the mechanisms explaining oncogene addiction remain elusive. We propose
that "addiction" may be an illusion generated as a consequence of differential
attenuation rates of prosurvival and proapoptotic signals emanating from an
oncoprotein acutely following its inactivation. According to this model, which
we call "oncogenic shock," prosurvival signals dissipate quickly on oncoprotein
inactivation whereas proapoptotic signals linger sufficiently long to commit the
cell to an apoptotic death. This mechanism may contribute to the rapid and
dramatic clinical responses observed in some cancer patients treated with
selective tyrosine kinase inhibitors and could yield additional drug targets
that determine the balance of signaling outputs from activated oncoproteins. Oncogene addiction is a phenomenon that the survival of cancer cells depends on
an activated oncogene or inactivation of tumor suppressor gene, and is regarded
as the 'Achilles heel' of the successful molecular targeted therapies in cancer.
However, the role of oncogene addiction in gliomas has not been elucidated
systematically. In this review, we summarize the current experimental and
clinical evidence for the concept of oncogene addiction and describe the
mechanisms explaining oncogene addiction in gliomas. And the clinical
implications for oncogene addiction in molecular targeted therapy are further
emphasized. In addition, we discuss future direction for defining complex
"oncogene addiction network" through the integrated analysis of multiple
platforms in the flow of genetic information in gliomagenesis. Although human cancers have complex genotypes and are genomically unstable, they
often remain dependent on the continued presence of single-driver mutations-a
phenomenon dubbed "oncogene addiction." Such dependencies have been demonstrated
in mouse models, where conditional expression systems have revealed that
oncogenes able to initiate cancer are often required for tumor maintece and
progression, thus validating the pathways they control as therapeutic targets.
Here, we implement an integrative approach that combines genetically defined
mouse models, transcriptional profiling, and a novel inducible RNAi platform to
characterize cellular programs that underlie addiction to MLL-AF9-a fusion
oncoprotein involved in aggressive forms of acute myeloid leukemia (AML). We
show that MLL-AF9 contributes to leukemia maintece by enforcing a
Myb-coordinated program of aberrant self-renewal involving genes linked to
leukemia stem cell potential and poor prognosis in human AML. Accordingly,
partial and transient Myb suppression precisely phenocopies MLL-AF9 withdrawal
and eradicates aggressive AML in vivo without preventing normal myelopoiesis,
indicating that strategies to inhibit Myb-dependent aberrant self-renewal
programs hold promise as effective and cancer-specific therapeutics. Together,
our results identify Myb as a critical mediator of oncogene addiction in AML,
delineate relevant Myb target genes that are amenable to pharmacologic
inhibition, and establish a general approach for dissecting oncogene addiction
in vivo. The suppression of oncogenic levels of MYC is sufficient to induce sustained
tumor regression associated with proliferative arrest, differentiation, cellular
senescence, and/or apoptosis, a phenomenon known as oncogene addiction. However,
after prolonged inactivation of MYC in a conditional transgenic mouse model of
Eμ-tTA/tetO-MYC T-cell acute lymphoblastic leukemia, some of the tumors recur,
recapitulating what is frequently observed in human tumors in response to
targeted therapies. Here we report that these recurring lymphomas express either
transgenic or endogenous Myc, albeit in many cases at levels below those in the
original tumor, suggesting that tumors continue to be addicted to MYC. Many of
the recurring lymphomas (76%) harbored mutations in the tetracycline
transactivator, resulting in expression of the MYC transgene even in the
presence of doxycycline. Some of the remaining recurring tumors expressed high
levels of endogenous Myc, which was associated with a genomic rearrangement of
the endogenous Myc locus or activation of Notch1. By gene expression profiling,
we confirmed that the primary and recurring tumors have highly similar
transcriptomes. Importantly, shRNA-mediated suppression of the high levels of
MYC in recurring tumors elicited both suppression of proliferation and increased
apoptosis, confirming that these tumors remain oncogene addicted. These results
suggest that tumors induced by MYC remain addicted to overexpression of this
oncogene. Cancers can exhibit marked tumor regression after oncogene inhibition through a
phenomenon called "oncogene addiction." The ability to predict when a tumor will
exhibit oncogene addiction would be useful in the development of targeted
therapeutics. Oncogene addiction is likely the consequence of many cellular
programs. However, we reasoned that many of these inputs may converge on
aggregate survival and death signals. To test this, we examined conditional
transgenic models of K-ras(G12D)--or MYC-induced lung tumors and lymphoma
combined with quantitative imaging and an in situ analysis of biomarkers of
proliferation and apoptotic signaling. We then used computational modeling based
on ordinary differential equations (ODEs) to show that oncogene addiction could
be modeled as differential changes in survival and death intracellular signals.
Our mathematical model could be generalized to different imaging methods
(computed tomography and bioluminescence imaging), different oncogenes
(K-ras(G12D) and MYC), and several tumor types (lung and lymphoma). Our ODE
model could predict the differential dynamics of several putative prosurvival
and prodeath signaling factors [phosphorylated extracellular signal-regulated
kinase 1 and 2, Akt1, Stat3/5 (signal transducer and activator of transcription
3/5), and p38] that contribute to the aggregate survival and death signals after
oncogene inactivation. Furthermore, we could predict the influence of specific
genetic lesions (p53⁻/⁻, Stat3-d358L, and myr-Akt1) on tumor regression after
oncogene inactivation. Then, using machine learning based on support vector
machine, we applied quantitative imaging methods to human patients to predict
both their EGFR genotype and their progression-free survival after treatment
with the targeted therapeutic erlotinib. Hence, the consequences of oncogene
inactivation can be accurately modeled on the basis of a relatively small number
of parameters that may predict when targeted therapeutics will elicit oncogene
addiction after oncogene inactivation and hence tumor regression. Despite complex genomic and epigenetic abnormalities, many cancers are
irrevocably dependent on an initiating oncogenic lesion whose restoration to a
normal physiological activation can elicit a dramatic and sudden reversal of
their neoplastic properties. This phenomenon of the reversal of tumorigenesis
has been described as oncogene addiction. Oncogene addiction had been thought to
occur largely through tumour cell-autonomous mechanisms such as proliferative
arrest, apoptosis, differentiation and cellular senescence. However, the immune
system plays an integral role in almost every aspect of tumorigenesis, including
tumour initiation, prevention and progression as well as the response to
therapeutics. Here we highlight more recent evidence suggesting that oncogene
addiction may be integrally dependent upon host immune-mediated mechanisms,
including specific immune effectors and cytokines that regulate tumour cell
senescence and tumour-associated angiogenesis. Hence, the host immune system is
essential to oncogene addiction. An important assumption of our current understanding of the mechanisms of
carcinogenesis has been the belief that clarification of the cancer process
would inevitably reveal some of the crucial mechanisms of normal human gene
regulation. Since the momentous work of Bishop and Varmus, both the molecular
and the biochemical processes underlying the events in the development of cancer
have become increasingly clear. The identification of cellular signaling
pathways and the role of protein kinases in the events leading to gene
activation have been critical to our understanding not only of normal cellular
gene control mechanisms, but also have clarified some of the important molecular
and biochemical events occurring within a cancer cell. We now know that
oncogenes are dysfunctional proto-oncogenes and that dysfunctional tumor
suppressor genes contribute to the cancer process. Furthermore, Weinstein and
others have hypothesized the phenomenon of oncogene addiction as a distinct
characteristic of the maligt cell. It can be assumed that cancer cells,
indeed, become dependent on such vital oncogenes. The products of these vital
oncogenes, such as c-myc, may well be the Achilles heel by which targeted
molecular therapy may lead to truly personalized cancer therapy. The remaining
problem is the need to introduce relevant molecular diagnostic tests such as
genome microarray analysis and proteomic methods, especially protein kinase
identification arrays, for each individual patient. Genome wide association
studies on cancers with gene analysis of single nucleotide and other mutations
in functional proto-oncogenes will, hopefully, identify dysfunctional
proto-oncogenes and allow the development of more specific targeted drugs
directed against the protein products of these vital oncogenes. In 1984 Willis
proposed a molecular and biochemical model for eukaryotic gene regulation
suggesting how proto-oncogenes might function within the normal cell. That model
predicted the existence of vital oncogenes and can now be used to hypothesize
the biochemical and molecular mechanisms that drive the processes leading to
disruption of the gene regulatory machinery, resulting in the transformation of
normal cells into cancer. BACKGROUND: A given tumor is usually dependent on the oncogene that is activated
in the respective tumor entity. This phenomenon called oncogene addiction
provides the rationale for attempts to target oncogene products in a therapeutic
manner, be it by small molecules, by small interfering RNAs (siRNA) or by
antigen-specific T cells. As the proto-oncogene product is required also for the
function of normal cells, this raises the question whether there is a
therapeutic window between the adverse effects of specific inhibitors or T cells
to normal tissue that may limit their application, and their beneficial
tumor-specific therapeutic action. To address this crucial question, suitable
mouse strains need to be developed, that enable expression of the human
proto-oncogene not only in tumor but also in normal cells. The aim of this work
is to provide such a mouse strain for the human proto-oncogene product c-MYC.
PRINCIPAL FINDINGS: We generated C57BL/6-derived embryonic stem cells that are
transgenic for a humanized c-Myc gene and established a mouse strain (hc-Myc)
that expresses human c-MYC instead of the murine ortholog. These transgenic
animals harbor the humanized c-Myc gene integrated into the endogenous murine
c-Myc locus. Despite the lack of the endogenous murine c-Myc gene, homozygous
mice show a normal phenotype indicating that human c-MYC can replace its murine
ortholog.
CONCLUSIONS: The newly established hc-Myc mouse strain provides a model system
to study in detail the adverse effects of therapies that target the human c-MYC
protein. To mimic the clinical situation, hc-Myc mice may be cross-bred to mice
that develop tumors due to overexpression of human c-MYC. With these double
transgenic mice it will be possible to study simultaneously the therapeutic
efficiency and adverse side effects of MYC-specific therapies in the same mouse. The clinical efficacy of tyrosine kinase inhibitors supports the dependence of
distinct subsets of cancers on specific driver mutations for survival, a
phenomenon called "oncogene addiction." We demonstrate that PUMA and BIM are the
key apoptotic effectors of tyrosine kinase inhibitors in breast cancers with
amplification of the gene encoding human epidermal growth factor receptor 2
(HER2) and lung cancers with epidermal growth factor receptor (EGFR) mutants.
The BH3 domain containing proteins BIM and PUMA can directly activate the
proapoptotic proteins BAX and BAK to permeabilize mitochondria, leading to
caspase activation and apoptosis. We delineated the signal transduction pathways
leading to the induction of BIM and PUMA by tyrosine kinase inhibitors.
Inhibition of the mitogen-activated or extracellular signal-regulated protein
kinase kinase (MEK)-extracellular signal-regulated kinase (ERK) pathway caused
increased abundance of BIM, whereas antagonizing the phosphoinositide 3-kinase
(PI3K)-AKT pathway triggered nuclear translocation of the FOXO transcription
factors, which directly activated the PUMA promoter. In a mouse breast tumor
model, the abundance of PUMA and BIM was increased after inactivation of HER2.
Moreover, deficiency of Bim or Puma impaired caspase activation and reduced
tumor regression caused by inactivation of HER2. Similarly, deficiency of Puma
impeded the regression of EGFR(L858R)-driven mouse lung tumors upon inactivation
of the EGFR-activating mutant. Overall, our study identified PUMA and BIM as the
sentinels that interconnect kinase signaling networks and the
mitochondrion-dependent apoptotic program, which offers therapeutic insights for
designing novel cell death mechanism-based anticancer strategies. Tumor cell growth and survival can often be impaired by inactivating a single
oncogen- a phenomenon that has been called as "oncogene addiction." It is in
such scenarios that molecular targeted therapies may succeed. among known
oncogenes, the epidermal growth factor receptor (EGFR) has become the target of
different cancer therapies. So far, however, the clinical benefit from
EGFR-targeted therapies has been rather limited. a critical review of the large
amount of clinical data obtained with anti-EGFR agents, carried out from the
perspective of the oncogene addiction concept, may help to understand the causes
of the unsatisfactory results. In this article we intend to do such an exercise
taking as basis for the analysis a few case studies of anti-EGFR agents that are
currently in the clinic. There, the "EGFR addiction" phenomenon becomes apparent
in high-responder patients. We further discuss how the concept of oncogene
addiction needs to be interpreted on the light of emerging experimental
evidences and ideas; in particular, that EGFR addiction may reflect the
interconnection of several cellular pathways. In this regard we set forth
several hypotheses; namely, that requirement of higher glucose uptake by hypoxic
tumor cells may reinforce EGFR addiction; and that chronic use of EGFR-targeted
antibodies in EGFR-addicted tumors would induce stable disease by reversing the
maligt phenotype of cancer stem cells and also by sustaining an anti-tumor T
cell response. Finally, we discuss possible reasons for the failure of certain
combinatorial therapies involving anti-EGFR agents, arguing that some of these
agents might produce either a negative or a positive trans-modulation effect on
other oncogenes. It becomes evident that we need operational definitions of EGFR
addiction in order to determine which patient populations may benefit from
treatment with anti-EGFR drugs, and to improve the design of these therapies. |
Are there randomised controlled trials on sevoflurane? | Yes. There are < 10 studies reported, answering questions like : how to improve speed of recovery, relationship to dreaming and anesthetic experience, effect on cardiac troponin release, effect on myocardial injury, postoperative delirium, haemodynamics & emergence and recovery characteristics of total intravenous anaesthesia, costs of postoperative nausea and vomiting, pediatric conscious sedation for dental procedures | We studied 411 children aged 3-10 years who were referred for dental treatment.
They were randomly allocated to have inhalation conscious sedation with either
sevoflurane/nitrous oxide mixture or nitrous oxide alone. Dental treatment was
satisfactorily completed in 215/241 children who were given sevoflurane/nitrous
oxide mixture (89%) compared with 89/170 who were given nitrous oxide alone
(52%) (Chi square 70.3, p < 0.0001). All children remained conscious and
responsive to verbal contact throughout the treatment and in the recovery room.
No adverse side-effects were recorded in either group and there were no
significant differences in oxygen saturation, heart rate, recovery profile, or
time to discharge home between the groups. The study concluded that, for every
100 children treated with sevoflurane/nitrous oxide mixture, 37 children would
be saved a general anaesthetic if given combined sevoflurane and nitrous oxide
mixture rather than nitrous oxide alone. The use of sevoflurane in low
concentrations 0.1-0.3% to supplement nitrous oxide and oxygen for inhalation
conscious sedation is safe, practical, and significantly more effective than
nitrous oxide alone in children having dental treatment. We compared the haemodynamics, emergence and recovery characteristics of total
intravenous anaesthesia using propofol/remifentanil with
sevoflurane/remifentanil anaesthesia, under bispectral index guidance, in 103
patients undergoing surgical procedures lasting > 3.5 h. Time to tracheal
extubation was significantly shorter in the propofol group than in the
sevoflurane group (mean (SD) 8.3 (3.5) min vs 10.8 (4.6) min, respectively; p =
0.0024), but further recovery was comparable in both groups. There were no
significant differences in haemodynamic parameters, intensity of pain or
postoperative nausea and vomiting. During and after anaesthesia of comparable
depth for long lasting surgical procedures, both propofol/remifentanil and
sevoflurane/remifentanil enable haemodynamic stability and fast emergence. The
shorter time to extubation in the propofol group does not offer a relevant
clinical advantage. This randomised controlled trial compared the effect of equipotent anaesthetic
doses of sevoflurane (S group) versus propofol (P group), during
remifentanil-based anaesthesia for off-pump coronary artery bypass surgery, on
myocardial injury. Either sevoflurane or propofol was titrated to maintain
bispectral index values between 40 and 50. In both groups, a targeted
concentration of remifentanil 20 ng x ml(-1) was maintained during anaesthesia.
The concentrations of creatine kinase MB and troponin I were measured before the
start of surgery, on admission to the intensive care unit, and at 12 and 24
hours after intensive care unit admission. The postoperative values of creatine
kinase MB (S group: 15.08 +/- 18.97, 20.78 +/- 20.92, 12.76 +/- 12.82 vs 2.09
+/- 1.54 ng x ml(-1); P group: 10.99 +/- 13.15 27.16 +/- 56.55 11.88 +/- 18.80
vs 1.84 +/- 1.67 ng x ml(-1)) and troponin I (S group: 3.56 +/- 5.19, 566 +/-
7.89, 3.35 +/- 4.55 vs 0.52 +/- 1.90 ng x ml(-1); P group: 2.42 +/- 3.33, 4.11
+/- 6.01, 3.04 +/- 5.31 vs 0.43 +/- 1.28 ng x ml(-1)) were significantly higher
than preoperative values in both groups but there were no significant
differences between the two groups. There were no significant differences in
time to extubation (S group, 476 +/- 284 minutes; P group, 450 +/- 268 minutes)
and intensive care unit length of stay (S group, 2775 +/- 1449 minutes; P group,
2797 +/- 1534 minutes) between the two groups. In conclusion, sevoflurane and
propofol at equipotent doses guided by bispectral index with remifentanil 20 ng
x ml(-1) had similar creatine kinase MB and troponin I values. BACKGROUND: Myocardial ischemic damage is reduced by volatile anaesthetics in
patients undergoing low-risk coronary artery bypass graft surgery; few and
discordant results exist in other settings. We therefore performed a randomised
controlled trial (sevoflurane vs. propofol) to compare cardiac troponin release
in patients with coronary disease undergoing mitral surgery.
METHODS: Patients with coronary artery disease undergoing mitral surgery were
randomly allocated to receive either sevoflurane (50 patients) or propofol (50
patients) as main hypnotic. The primary endpoint of the study was peak
post-operative cardiac troponin release defined as the maximum value among the
post-operative values measured at intensive care unit arrival, 4 h later, on the
first and second post-operative day.
RESULTS: There was no significant difference in post-operative peak troponin
release, the median (25th-75th percentiles) values being 14.9 (10.1-22.1) ng/ml
and 14.5 (8.8-17.6) ng/ml in the sevoflurane and propofol groups, respectively
(P = 0.4). Fentanyl administration was different between the two groups: 1347 ±
447 μg in patients receiving sevoflurane and 1670 ± 469 μg in those receiving
propofol, P = 0.002. The 1-year follow-up identified two patients who died in
the propofol group (one myocardial infarction and one low cardiac output
syndrome) and one in the sevoflurane group (myocardial infarction).
CONCLUSION: In this study, patients with coronary artery disease undergoing
mitral surgery did not benefit from the cardioprotective properties of
halogenated anaesthetics. Sevoflurane anaesthesia was not associated to lower
cardiac troponin release when compared with propofol anaesthesia. Prior reports suggest that dreaming during anaesthesia is dependent on recovery
time. Dreaming during sedation may impact patient satisfaction. The current
study explores the incidence and content of dreaming during short-term sedation
with sevoflurane or propofol and investigates whether dreaming is affected by
recovery time. A total of 200 women undergoing first trimester abortion
(American Society of Anesthesiologists physical status I) participated in the
study. Patients were randomly assigned to receive either sevoflurane or propofol
for short-term sedation. Patients were interviewed upon emergence with the
modified Brice questionnaire. The results showed the incidence of dreaming was
significantly different between anaesthesia groups with 60% (60/100) of the
sevoflurane group and 33% (33/100) of the propofol group (P=0.000). However,
recovery time did not significantly differ between groups. In the sevoflurane
group, a greater number of dreamers could not recall what they had dreamed about
(P=0.02) and more patients reported dreams that had no sound (P=0.03) or
movement (P=0.001) compared with dreamers in the propofol group. Most
participants reported dreams with positive emotional content and this did not
significantly differ between groups. Anaesthesia administered had no effect on
patient satisfaction. The results suggest that the incidence of dreaming was not
affected by recovery time. Patient satisfaction was not influenced by choice of
sedative and/or by the occurrence of dreaming during sevoflurane or propofol
short-term sedation. |
In which cells are gasdermins expressed? | Members of the novel gene family Gasdermin (Gsdm) are exclusively expressed in a highly tissue-specific manner in the epithelium of skin and the gastrointestinal tract. | Defolliculated (Dfl) is a spontaneous mouse mutant with a hair-loss phenotype
that includes altered sebaceous gland differentiation, short hair shafts,
aberrant catagen stage of the hair cycle, and eventual loss of the hair
follicle. Recently a similar mutant, finnegan (Fgn), with an identical phenotype
was discovered during a phenotypic screen for mutations induced by chemical
mutagenesis. The gene underlying the phenotype of both finnegan and
defolliculated has been mapped to chromosome 11 and here we show that both mice
harbor mutations in gasdermin 3 (Gsdm3), a gene of unknown function. Gsdm3(Dfl)
is a B2 insertion near the 3' splice site of exon 7 and Gsdm3(Fgn) is a point
mutation T278P. To investigate the role of the gasdermin gene family an
antiserum was raised to a peptide highly homologous to all three mouse
gasdermins and human gasdermin. Immunohistochemical analysis revealed that
gasdermins are expressed specifically in cells at advanced stages of
differentiation in the upper epidermis, the differentiating inner root sheath
and hair shaft and in the most mature sebocytes of the sebaceous gland and
preputial, meibomium, ceruminous gland, and anal glands. This expression pattern
suggests a role for gasdermins in differentiation of the epidermis and its
appendages. Members of the novel gene family Gasdermin (Gsdm) are exclusively expressed in a
highly tissue-specific manner in the epithelium of skin and the gastrointestinal
tract. Based on their expression patterns and the phenotype of the Gsdma3
spontaneous mutations, it is inferred that the Gsdm family genes are involved in
epithelial cell growth and/or differentiations in different tissues. To
investigate possible roles of the Gsdm gene family in the development of
intestinal tracts, we generated a Gsdmd mutant mouse, which is a solitary member
of the Gsdmd subfamily and which is predomitly expressed in the intestinal
tract by means of targeted disruption. In the mutant homozygotes, we found no
abnormality of intestinal tract morphology. Moreover, in mutant mice, there was
normal differentiation of all constituent cell types of the intestinal
epithelium. Thus, this study clearly shows that Gsdmd is not essential for
development of mouse intestinal tract or epithelial cell differentiation. Gasdermin (GSDM or GSDMA), expressed in the upper gastrointestinal tract but
frequently silenced in gastric cancers (GCs), regulates apoptosis of the gastric
epithelium. It has three human homologs, GSDMB, GSDMC, and GSDMD (GSDM family)
and they are considered to be involved in the regulation of epithelial apoptosis
but not yet known. We investigated the expression pattern of the family genes in
the upper gastrointestinal epithelium and cancers. Reverse
transcriptase-polymerase chain reaction revealed that, unlike GSDMA expressed in
differentiated cells, GSDMB is expressed in proliferating cells and GSDMD in
differentiating cells. GSDMC, meanwhile, is expressed in both differentiating
and differentiated cells. Colony formation assay showed that GSDMB, closely
related to GSDMA, has no cell-growth inhibition activity in gastric cancer
cells, and that GSDMC and GSDMD, respectively, exhibit the activity with
different strengths from that of GSDMA. Expression analyses of the four family
genes in esophageal and GCs suggested that GSDMC and GSDMD as well as GSDMA are
tumor suppressors and that GSDMB, which was amplified and overexpressed in some
GCs, could be an oncogene. The results of the expression analysis and colony
formation assay suggest that each family gene may have a distinct function in
the upper gastrointestinal epithelium. |
Where in a protein can a signal sequence be found? | Proteins have signal sequences typically resent at the most N-terminal end. | The 605 amino acid E1 protein of bovine papillomavirus type 1 (BPV-1) is a
multifunctional nuclear protein required for viral DNA replication. A nuclear
localization signal (NLS) sequence was previously defined by point mutations in
three short adjacent clusters of basic amino acids located in the amino-terminal
region of the E1 protein. In this study, we used a fusion protein approach to
evaluate the contribution of other regions of the E1 protein to nuclear
transport. The nearly full-length E1 gene and six non-overlapping subfragments
were each fused in-frame with the lacZ gene in a eukaryotic expression vector.
Each clone was electroporated into COS-1 cells, and the intracellular location
of the E1-beta-galactosidase fusion proteins was determined by
immunofluorescence. Only the constructs containing the full-length E1 or a
single subregion (E1-259; amino acids 84 to 166) produced fusion proteins that
entered the nucleus. Point mutations in the NLS sequences of the E1-259-lacZ
construct prevented nuclear translocation of the corresponding fusion protein.
This confirms the previous result that the cluster of basic amino acids is
critical for nuclear transport. Furthermore, the data obtained in this
investigation indicated that the region of E1 containing the NLS sequence was
not only necessary, but was also sufficient for nuclear localization. No other
region of E1 contained independent nuclear localization activity. The transient axonal glycoprotein (TAG-1) is a cell adhesion molecule that
promotes neurite outgrowth and belongs to the immunoglobulin superfamily. We
have isolated cDNAs encoding TAX1, the human homologue of TAG-1. Human TAX1
shows a high degree of homology to rat TAX1 and less to its chick counterpart,
axonin-1, with 91 and 75% identity at the amino acid level, respectively. The
numbers of immunoglobulin (IgC2) domains and fibronectin repeats present in
TAG-1 are conserved among the three species. The highest degree of conservation
occurs in the second IgC2 domain (98% with the rat and 82% with the chick). The
human homologue also contains a putative N-terminal signal sequence and a
C-terminal hydrophobic sequence, suggestive of linkage to the cell membrane via
phosphatidylinositol. In addition, the two mammalian TAG-1 proteins share the
RGD tripeptide, a motif known to mediate recognition of fibronectin by
integrins. In situ hybridization to human metaphase chromosomes maps the TAX1
gene encoding human TAG-1 to a single location on chromosome 1q32. We report the characterization of a gene encoding a novel flocculin related to
the STA genes of yeast, which encode secreted glucoamylase. The STA genes
comprise sequences that are homologous to the sporulation-specific glucoamylase
SGA and to two other sequences, S2 and S1. We find that S2 and S1 are part of a
single gene which we have named FLO11. The sequence of FLO11 reveals a 4,104-bp
open reading frame on chromosome IX whose predicted product is similar in
overall structure to the class of yeast serine/threonine-rich GPI-anchored cell
wall proteins. An amino-terminal domain containing a signal sequence and a
carboxy-terminal domain with homology to GPI (glycosyl-phosphatidyl-inositol)
anchor-containing proteins are separated by a central domain containing a highly
repeated threonine- and serine-rich sequence. Yeast cells that express FLO11
aggregate in the calcium-dependent process of flocculation. Flocculation is
abolished when FLO11 is disrupted. The product of STA1 also is shown to have
flocculating activity. When a green fluorescent protein fusion of FLO11 was
expressed from the FLO11 promoter on a single-copy plasmid, fluorescence was
observed in vivo at the periphery of cells. We propose that FLO11 encodes a
flocculin because of its demonstrated role in flocculation, its structural
similarity to other members of the FLO gene family, and the cell surface
location of its product. FLO11 gene sequences are present in all yeast strains
tested, including all standard laboratory strains, unlike the STA genes which
are present only in the variant strain Saccharomyces cerevisiae var.
diastaticus. FLO11 differs from all other yeast flocculins in that it is located
near a centromere rather than a telomere, and its expression is regulated by
mating type. Repression of FLO11-dependent flocculation in diploids is conferred
by the mating-type repressor al/alpha2. The complete primary structure of the mouse type XIII collagen chain was
determined by cDNA cloning. Comparison of the mouse amino acid sequences with
the previously determined human sequences revealed a high identity of 90%.
Surprisingly, the mouse cDNAs extended further in the 5' direction than the
previously identified human clones. The 5' sequences contained a new in-frame
ATG codon for translation initiation which resulted in elongation of the
N-terminal noncollagenous domain by 81 residues. These N-terminal sequences lack
a typical signal sequence but include a highly hydrophobic segment that clearly
fulfills the criteria for a transmembrane domain. The sequence data thus
unexpectedly suggested that type XIII collagen may be located on the plasma
membrane, with a short cytosolic N-terminal portion and a long collagenous
extracellular portion. These sequence data prompted us to generate antipeptide
antibodies against type XIII collagen in order to study the protein and its
subcellular location. Western blotting of human tumor HT-1080 cell extract
revealed bands of over 180 kDa. These appeared to represent disulfide-bonded
multimeric polypeptide forms that resolved upon reduction into 85-95-kDa bands
that are likely to represent a mixture of splice forms of monomeric type XIII
collagen chains. These chains were shown to contain the predicted N-terminal
extension and thus also the putative transmembrane segment. Immunoprecipitation
of biotinylated type XIII collagen from surface-labeled HT-1080 cells,
subcellular fractionation, and immunofluorescence staining were used to
demonstrate that type XIII collagen molecules are indeed located in the plasma
membranes of these cells. The recently characterized human serine protease, Testisin, is expressed on
premeiotic testicular germ cells and is a candidate type II tumor suppressor for
testicular cancer. Here we report the cloning, characterization and expression
of the gene encoding mouse Testisin, Prss21. The murine Testisin gene comprises
six exons and five introns and spans approximately 5 kb of genomic DNA with an
almost identical structure to the human Testisin gene, PRSS21. The gene was
localized to murine chromosome 17 A3.3-B; a region syntenic with the location of
PRSS21 on human chromosome 16p13.3. Northern blot analyses of RNA from a range
of adult murine tissues demonstrated a 1.3 kb mRNA transcript present only in
testis. The murine Testisin cDNA shares 65% identity with human Testisin cDNA
and encodes a putative pre-pro-protein of 324 amino acids with 80% similarity to
human Testisin. The predicted amino-acid sequence includes an N-terminal signal
sequence of 27 amino acids, a 27 amino-acid pro-region, a 251 amino-acid
catalytic domain typical of a serine protease with trypsin-like specificity, and
a C-terminal hydrophobic extension which is predicted to function as a membrane
anchor. Immunostaining for murine Testisin in mouse testis demonstrated specific
staining in the cytoplasm and on the plasma membrane of round and elongating
spermatids. Examination of murine Testisin mRNA expression in developing sperm
confirmed that the onset of murine Testisin mRNA expression occurred at
approximately day 18 after birth, corresponding to the appearance of spermatids
in the testis, in contrast to the expression of human Testisin in spermatocytes.
These data identify the murine ortholog to human Testisin and demonstrate that
the murine Testisin gene is temporally regulated during murine spermatogenesis. thi1 has been recently isolated from Arabidopsis thaliana and is probably
involved in both thiamine biosynthesis and as protection of organellar DNA from
damage. Studies of thiamine biosynthesis in plants suggests a plastid location
for the pathway, which is in agreement with the predicted THI1 N-terminal
chloroplastic transit peptide (TP). On the other hand, thiamine is synthesized
in mitochondria in yeast cells. Interestingly, A. thaliana thi1 cDNA complements
a yeast strain disrupted for the homologous gene. Analysis of THI1 amino acid
sequence revealed the presence of a putative amphiphilic alpha-helix, which is
typical for mitochondrial presequences, located downstream of the chloroplast
transit peptide. To define the putative role of the two predicted targeting
sequences in tandem, we produced two chimeric genes encompassing the
chloroplastic THI1 TP and either 4 or 27 (including the putative mitochondrial
presequence) N-terminal residues of the mature THI1, both linked to the reporter
(gusA) gene. Analysis of GUS distribution in subcellular fractions of transgenic
plants revealed that in the construct retaining only 4 residues of mature THI1,
GUS was found in the chloroplastic fraction. Extension of the THI1 transit
peptide to 27 residues of the mature protein allowed import and processing of
GUS into both mitochondria and chloroplasts. Direct analysis by
immunogold-labeling with an anti-THI1 polyclonal antibody identified THI1 in
both organelles in Arabidopsis. We also provide evidence that the precursors of
both organellar isoforms are encoded by a single nuclear transcript. Thus, THI1
is targeted simultaneously to mitochondria and chloroplasts by a post
transcriptional mechanism. Metal ion homeostasis mechanisms in the food-borne human pathogen Campylobacter
jejuni are poorly understood. The Cj1516 gene product is homologous to the
multicopper oxidase CueO, which is known to contribute to copper tolerance in
Escherichia coli. Here we show, by optical absorbance and electron paramagnetic
resoce spectroscopy, that purified recombit Cj1516 contains both T1 and
trinuclear copper centers, which are characteristic of multicopper oxidases.
Inductively coupled plasma mass spectrometry revealed that the protein contained
approximately six copper atoms per polypeptide. The presence of an N-terminal
"twin arginine" signal sequence suggested a periplasmic location for Cj1516,
which was confirmed by the presence of p-phenylenediamine (p-PD) oxidase
activity in periplasmic fractions of wild-type but not Cj1516 mutant cells.
Kinetic studies showed that the pure protein exhibited p-PD, ferroxidase, and
cuprous oxidase activities and was able to oxidize an analogue of the bacterial
siderophore anthrachelin (3,4-dihydroxybenzoate), although no iron uptake
impairment was observed in a Cj1516 mutant. However, this mutant was very
sensitive to increased copper levels in minimal media, suggesting a role in
copper tolerance. This was supported by increased expression of the Cj1516 gene
in copper-rich media. A mutation in a second gene, the Cj1161c gene, encoding a
putative CopA homologue, was also found to result in copper hypersensitivity,
and a Cj1516 Cj1161c double mutant was found to be more copper sensitive than
either single mutant. These observations and the apparent lack of alternative
copper tolerance systems suggest that Cj1516 (CueO) and Cj1161 (CopA) are major
proteins involved in copper homeostasis in C. jejuni. Ammonia monooxygenase (AMO) of Nitrosomonas europaea is a metalloenzyme that
catalyzes the oxidation of ammonia to hydroxylamine. This study shows that AMO
resides in the cytoplasm of the bacteria in addition to its location in the
membrane and is distributed approximately equally in both subcellular fractions.
AMO in both fractions catalyzes the oxidation of ammonia and binds
[(14)C]acetylene, a mechanism-based inhibitor which specifically interacts with
catalytically active AMO. Soluble AMO was purified 12-fold to electrophoretic
homogeneity with a yield of 8%. AMO has a molecular mass of approximately 283
kDa with subunits of ca. 27 kDa (alpha-subunit, AmoA), ca. 42 kDa (beta-subunit,
AmoB), and ca. 24 kDa (gamma-subunit, cytochrome c(1)) in an
alpha(3)beta(3)gamma(3) sub-unit structure. Different from the beta-subunit of
membrane-bound AMO, AmoB of soluble AMO possesses an N-terminal signal sequence.
AMO contains Cu (9.4+/-0.6 mol per mol AMO), Fe (3.9+/-0.3 mol per mol AMO), and
Zn (0.5 to 2.6 mol per mol AMO). Upon reduction the visible absorption spectrum
of AMO reveals absorption bands characteristic of cytochrome c. Electron
para-magnetic resoce spectroscopy of air-oxidized AMO at 50 K shows a
paramagnetic signal originating from Cu(2+) and at 10 K a paramagnetic signal
characteristic of heme-Fe. The neuregulins (NRGs) play important roles in animal development and
homeostasis, and their deregulation has been linked to diseases such as cancer
and schizophrenia. The NRGs belong to the epidermal growth factor (EGF) family
of transmembrane growth factors. Although NRGs may be synthesized as
transmembrane proteins (the pro-NRGs), some of them lack an N-terminal signal
sequence, raising the question of how these pro-NRGs are directed to the plasma
membrane. Here we have explored the domains of pro-NRGs that are required for
their membrane anchoring, cell surface exposure, and biological activity. We
show that an internal hydrophobic region acts as a membrane-anchoring domain,
but other regions of pro-NRG are required for proper sorting to the plasma
membrane. Using mutants that are located in different subcellular compartments,
we show that only plasma membrane-exposed pro-NRG is biologically active. At
this location, the pro-NRGs may act as transautocrine molecules (i.e. as
membrane factors able to activate receptors present in cells that are in
physical contact with the pro-NRG-producing cells (in trans) or capable of
activating receptors present in the pro-NRG-producing cells (in cis)). A transmembrane domain (TMD) at the N-terminus of a membrane protein is a signal
sequence that targets the protein to the endoplasmic reticulum (ER) membrane.
Proline is found more frequently in TM helices compared to water-soluble
helices. To investigate the effects of proline on protein translocation and
integration in mammalian cells, we made proline substitutions throughout the TMD
of dipeptidyl peptidase IV, a type II membrane protease with a single TMD at its
N-terminus. The proteins were expressed and their capacities for targeting and
integrating into the membrane were measured in both mammalian cells and in vitro
translation systems. Three proline substitutions in the central region of the
TMD resulted in various defects in membrane targeting and/or integration. The
replacement of proline with other amino acids of similar hydrophobicity rescued
both the translocation and anchoring defects of all three proline mutants,
indicating that conformational change caused by proline is a determining factor.
Increasing hydrophobicity of the TMD by replacing other residues with more
hydrophobic residues also effectively reversed the translocation and integration
defects. Intriguingly, increasing hydrophobicity at the C-terminal end of the
TMD rescued much more effectively than it did at the N-terminal end. Thus, the
effect of proline on translocation and integration of the TMD is not determined
solely by its conformation and hydrophobicity, but also by the location of
proline in the TMD, the location of highly hydrophobic residues, and the
relative position of the proline to other proline residues in the TMD. |