2,222 research outputs found
Uncertainties in CMIP5 climate projections due to carbon cycle feedbacks
Final published version of article.© 2014 American Meteorological SocietyIn the context of phase 5 of the Coupled Model Intercomparison Project, most climate simulations use prescribed atmospheric CO2 concentration and therefore do not interactively include the effect of carbon cycle feedbacks. However, the representative concentration pathway 8.5 (RCP8.5) scenario has additionally been run by earth system models with prescribed CO2 emissions. This paper analyzes the climate projections of 11 earth system models (ESMs) that performed both emission-driven and concentration-driven RCP8.5 simulations.When forced by RCP8.5 CO2 emissions, models simulate a large spread in atmospheric CO2; the simulated 2100 concentrations range between 795 and 1145 ppm. Seven out of the 11 ESMs simulate a larger CO2 (on average by 44 ppm, 985 ± 97ppm by 2100) and hence higher radiative forcing (by 0.25Wm-2) when driven by CO2 emissions than for the concentration-driven scenarios (941 ppm). However, most of these models already overestimate the present-day CO2, with the present-day biases reasonably well correlated with future atmospheric concentrations' departure from the prescribed concentration. The uncertainty in CO2 projections is mainly attributable to uncertainties in the response of the land carbon cycle. As a result of simulated higher CO2 concentrations than in the concentration-driven simulations, temperature projections are generally higher when ESMs are driven with CO2 emissions. Global surface temperature change by 2100 (relative to present day) increased by 3.9° ± 0.9°C for the emission-driven simulations compared to 3.7° ± 0.7°C in the concentration-driven simulations. Although the lower ends are comparable in both sets of simulations, the highest climate projections are significantly warmer in the emission-driven simulations because of stronger carbon cycle feedbacks. © 2014 American Meteorological Society.Department for Environment, Food and Rural Affairs (DEFRA)Department of Energy & Climate Change (DECC
Hyaluronan derived nanoparticle for simvastatin delivery: evaluation of simvastatin induced myotoxicity in tissue engineered skeletal muscle
Statins are currently the most prescribed hypercholesterolemia-lowering drugs worldwide, with estimated usage approaching one-sixth of the population. However, statins are known to cause pleiotropic skeletal myopathies in 1.5% to 10% of patients and the mechanisms by which statins induce this response, are not fully understood. In this study, a 3D collagen-based tissue-engineered skeletal muscle construct is utilised as a screening platform to test the efficacy and toxicity of a new delivery system. A hyaluronic acid derived nanoparticle loaded with simvastatin (HA-SIM-NPs) is designed and the effect of free simvastatin and HA-SIM-NPs on cellular, molecular and tissue response is investigated. Morphological ablation of myotubes and lack of de novo myotube formation (regeneration) was evident at the highest concentrations (333.33 μM), independent of delivery vehicle (SIM or HA-SIM-NP). A dose-dependent disruption of the cytoskeleton, reductions in metabolic activity and tissue engineered (TE) construct tissue relaxation was evident in the free drug condition (SIM, 3.33 μM and 33.33 nM). However, most of these changes were ameliorated when SIM was delivered via HA-SIM-NPs. Significantly, homogeneous expressions of MMP2, MMP9, and myogenin in HA-SIM-NPs outlined enhanced regenerative responses compared to SIM. Together, these results outline statin delivery via HA-SIM-NP as an effective delivery mechanism to inhibit deleterious myotoxic side-effects
Coronary-artery bypass surgery in patients with ischemic cardiomyopathy
BACKGROUND
The survival benefit of a strategy of coronary-artery bypass grafting (CABG) added to
guideline-directed medical therapy, as compared with medical therapy alone, in patients
with coronary artery disease, heart failure, and severe left ventricular systolic
dysfunction remains unclear.
METHODS
From July 2002 to May 2007, a total of 1212 patients with an ejection fraction of 35%
or less and coronary artery disease amenable to CABG were randomly assigned to
undergo CABG plus medical therapy (CABG group, 610 patients) or medical therapy
alone (medical-therapy group, 602 patients). The primary outcome was death from any
cause. Major secondary outcomes included death from cardiovascular causes and death
from any cause or hospitalization for cardiovascular causes. The median duration of
follow-up, including the current extended-follow-up study, was 9.8 years.
RESULTS
A primary outcome event occurred in 359 patients (58.9%) in the CABG group and in
398 patients (66.1%) in the medical-therapy group (hazard ratio with CABG vs. medical
therapy, 0.84; 95% confidence interval [CI], 0.73 to 0.97; P=0.02 by log-rank test). A
total of 247 patients (40.5%) in the CABG group and 297 patients (49.3%) in the
medical-therapy group died from cardiovascular causes (hazard ratio, 0.79; 95% CI,
0.66 to 0.93; P=0.006 by log-rank test). Death from any cause or hospitalization for
cardiovascular causes occurred in 467 patients (76.6%) in the CABG group and in 524
patients (87.0%) in the medical-therapy group (hazard ratio, 0.72; 95% CI, 0.64 to 0.82;
P<0.001 by log-rank test).
CONCLUSIONS
In a cohort of patients with ischemic cardiomyopathy, the rates of death from any
cause, death from cardiovascular causes, and death from any cause or hospitalization
for cardiovascular causes were significantly lower over 10 years among patients who
underwent CABG in addition to receiving medical therapy than among those who received
medical therapy alone. (Funded by the National Institutes of Health; STICH [and
STICHES] ClinicalTrials.gov number, NCT00023595.
Recurrent De Novo NAHR Reciprocal Duplications in the ATAD3 Gene Cluster Cause a Neurogenetic Trait with Perturbed Cholesterol and Mitochondrial Metabolism.
Recent studies have identified both recessive and dominant forms of mitochondrial disease that result from ATAD3A variants. The recessive form includes subjects with biallelic deletions mediated by non-allelic homologous recombination. We report five unrelated neonates with a lethal metabolic disorder characterized by cardiomyopathy, corneal opacities, encephalopathy, hypotonia, and seizures in whom a monoallelic reciprocal duplication at the ATAD3 locus was identified. Analysis of the breakpoint junction fragment indicated that these 67 kb heterozygous duplications were likely mediated by non-allelic homologous recombination at regions of high sequence identity in ATAD3A exon 11 and ATAD3C exon 7. At the recombinant junction, the duplication allele produces a fusion gene derived from ATAD3A and ATAD3C, the protein product of which lacks key functional residues. Analysis of fibroblasts derived from two affected individuals shows that the fusion gene product is expressed and stable. These cells display perturbed cholesterol and mitochondrial DNA organization similar to that observed for individuals with severe ATAD3A deficiency. We hypothesize that the fusion protein acts through a dominant-negative mechanism to cause this fatal mitochondrial disorder. Our data delineate a molecular diagnosis for this disorder, extend the clinical spectrum associated with structural variation at the ATAD3 locus, and identify a third mutational mechanism for ATAD3 gene cluster variants. These results further affirm structural variant mutagenesis mechanisms in sporadic disease traits, emphasize the importance of copy number analysis in molecular genomic diagnosis, and highlight some of the challenges of detecting and interpreting clinically relevant rare gene rearrangements from next-generation sequencing data
Notes on Operator Equations of Supercurrent Multiplets and the Anomaly Puzzle in Supersymmetric Field Theories
Recently, Komargodski and Seiberg have proposed a new type of supercurrent
multiplet which contains the energy-momentum tensor and the supersymmetry
current consistently. In this paper we study quantum properties of the
supercurrent in renormalizable field theories. We point out that the new
supercurrent gives a quite simple resolution to the classic problem, called the
anomaly puzzle, that the Adler-Bardeen theorem applied to an R-symmetry current
is inconsistent with all order corrections to functions. We propose an
operator equation for the supercurrent in all orders of perturbation theory,
and then perform several consistency checks of the equation. The operator
equation we propose is consisitent with the one proposed by Shifman and
Vainshtein, if we take some care in interpreting the meaning of non-conserved
currents.Comment: 28 pages; v2:clarifications and references added, some minor change
Completion of fit notes by GPs: a mixed methods study
Aims: The aim of this study was to investigate the completion of fit notes by UK general practitioners (GPs). A series of actual fit notes issued to employed patients were examined, and their GPs’ reflections and experiences of fit note completion explored.
Methods: A mixed-methods design was used. Data were collected from copies of 94 fit notes issued to employed patients by 11 GPs, and from 86 questionnaires completed by these GPs reflecting on the fit notes they had issued. Face-to-face interviews were then conducted with each GP.
Results: Fit note completion is not meeting expectations for a number of reasons. These include the following: limited knowledge and awareness of the guidance in fit note completion; problems with the fit note format; lack of mandatory training in completing fit notes; lack of incentive to change practice; incomplete implementation of the electronic fit note; GPs’ lack of confidence in, and doubts about the appropriateness of performing this role.
Conclusion: If UK GPs are to continue their contractual responsibility for completing fit notes, further consideration of their education and training needs is urgently required. Weaknesses in the design and format of the fit note and the availability of the electronic version also need to be addressed
A donor-specific epigenetic classifier for acute graft-versus-host disease severity in hematopoietic stem cell
Background Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for many hematological conditions. Acute graft-versus-host disease (aGVHD) is a prevalent immune-mediated complication following HSCT. Current diagnostic biomarkers that correlate with aGVHD severity, progression, and therapy response in graft recipients are insufficient. Here, we investigated whether epigenetic marks measured in peripheral blood of healthy graft donors stratify aGVHD severity in human leukocyte antigen (HLA)-matched sibling recipients prior to T cell-depleted HSCT. Methods We measured DNA methylation levels genome-wide at single-nucleotide resolution in peripheral blood of 85 HSCT donors, matched to recipients with various transplant outcomes, with Illumina Infinium HumanMethylation450 BeadChips. Results Using genome-wide DNA methylation profiling, we showed that epigenetic signatures underlying aGVHD severity in recipients correspond to immune pathways relevant to aGVHD etiology. We discovered 31 DNA methylation marks in donors that associated with aGVHD severity status in recipients, and demonstrated strong predictive performance of these markers in internal cross-validation experiments (AUC = 0.98, 95 % CI = 0.96–0.99). We replicated the top-ranked CpG classifier using an alternative, clinical DNA methylation assay (P = 0.039). In an independent cohort of 32 HSCT donors, we demonstrated the utility of the epigenetic classifier in the context of a T cell-replete conditioning regimen (P = 0.050). Conclusions Our findings suggest that epigenetic typing of HSCT donors in a clinical setting may be used in conjunction with HLA genotyping to inform both donor selection and transplantation strategy, with the ultimate aim of improving patient outcome
Treatment outcomes of new tuberculosis patients hospitalized in Kampala, Uganda: a prospective cohort study.
BACKGROUND: In most resource limited settings, new tuberculosis (TB) patients are usually treated as outpatients. We sought to investigate the reasons for hospitalisation and the predictors of poor treatment outcomes and mortality in a cohort of hospitalized new TB patients in Kampala, Uganda. METHODS AND FINDINGS: Ninety-six new TB patients hospitalised between 2003 and 2006 were enrolled and followed for two years. Thirty two were HIV-uninfected and 64 were HIV-infected. Among the HIV-uninfected, the commonest reasons for hospitalization were low Karnofsky score (47%) and need for diagnostic evaluation (25%). HIV-infected patients were commonly hospitalized due to low Karnofsky score (72%), concurrent illness (16%) and diagnostic evaluation (14%). Eleven HIV uninfected patients died (mortality rate 19.7 per 100 person-years) while 41 deaths occurred among the HIV-infected patients (mortality rate 46.9 per 100 person years). In all patients an unsuccessful treatment outcome (treatment failure, death during the treatment period or an unknown outcome) was associated with duration of TB symptoms, with the odds of an unsuccessful outcome decreasing with increasing duration. Among HIV-infected patients, an unsuccessful treatment outcome was also associated with male sex (P = 0.004) and age (P = 0.034). Low Karnofsky score (aHR = 8.93, 95% CI 1.88 - 42.40, P = 0.001) was the only factor significantly associated with mortality among the HIV-uninfected. Mortality among the HIV-infected was associated with the composite variable of CD4 and ART use, with patients with baseline CD4 below 200 cells/µL who were not on ART at a greater risk of death than those who were on ART, and low Karnofsky score (aHR = 2.02, 95% CI 1.02 - 4.01, P = 0.045). CONCLUSION: Poor health status is a common cause of hospitalisation for new TB patients. Mortality in this study was very high and associated with advanced HIV Disease and no use of ART
Mindfulness-based interventions in epilepsy: a systematic review
Mindfulness based interventions (MBIs) are increasingly used to help patients cope with physical and mental long-term conditions (LTCs). Epilepsy is associated with a range of mental and physical comorbidities that have a detrimental effect on quality of life (QOL), but it is not clear whether MBIs can help. We systematically reviewed the literature to determine the effectiveness of MBIs in people with epilepsy. Medline, Cochrane Central Register of Controlled Trials, EMBASE, CINAHL, Allied and Complimentary Medicine Database, and PsychInfo were searched in March 2016. These databases were searched using a combination of subject headings where available and keywords in the title and abstracts. We also searched the reference lists of related reviews. Study quality was assessed using the Cochrane Collaboration risk of bias tool. Three randomised controlled trials (RCTs) with a total of 231 participants were included. The interventions were tested in the USA (n = 171) and China (Hong Kong) (n = 60). Significant improvements were reported in depression symptoms, quality of life, anxiety, and depression knowledge and skills. Two of the included studies were assessed as being at unclear/high risk of bias - with randomisation and allocation procedures, as well as adverse events and reasons for drop-outs poorly reported. There was no reporting on intervention costs/benefits or how they affected health service utilisation. This systematic review found limited evidence for the effectiveness of MBIs in epilepsy, however preliminary evidence suggests it may lead to some improvement in anxiety, depression and quality of life. Further trials with larger sample sizes, active control groups and longer follow-ups are needed before the evidence for MBIs in epilepsy can be conclusively determined
VEZF1 elements mediate protection from DNA methylation
There is growing consensus that genome organization and long-range gene regulation involves partitioning of the genome into domains of distinct epigenetic chromatin states. Chromatin insulator or barrier elements are key components of these processes as they can establish boundaries between chromatin states. The ability of elements such as the paradigm β-globin HS4 insulator to block the range of enhancers or the spread of repressive histone modifications is well established. Here we have addressed the hypothesis that a barrier element in vertebrates should be capable of defending a gene from silencing by DNA methylation. Using an established stable reporter gene system, we find that HS4 acts specifically to protect a gene promoter from de novo DNA methylation. Notably, protection from methylation can occur in the absence of histone acetylation or transcription. There is a division of labor at HS4; the sequences that mediate protection from methylation are separable from those that mediate CTCF-dependent enhancer blocking and USF-dependent histone modification recruitment. The zinc finger protein VEZF1 was purified as the factor that specifically interacts with the methylation protection elements. VEZF1 is a candidate CpG island protection factor as the G-rich sequences bound by VEZF1 are frequently found at CpG island promoters. Indeed, we show that VEZF1 elements are sufficient to mediate demethylation and protection of the APRT CpG island promoter from DNA methylation. We propose that many barrier elements in vertebrates will prevent DNA methylation in addition to blocking the propagation of repressive histone modifications, as either process is sufficient to direct the establishment of an epigenetically stable silent chromatin stat
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