3,131 research outputs found

    A comparative study of herbage intake, ingestive behaviour and diet selection, and effects of condensed tannins upon body and wool growth in lambs grazing Yorkshire fog (Holcus lanatus) and annual ryegrass (Lolium multiflorum) dominant swards

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    An experiment was carried out from August to early November 1994 to examine differences in diet selection, herbage intake, grazing behaviour and animal performance between weaned lambs rotationally grazing swards of annual ryegrass (Lolium multiflorum)/white clover (Trifolium repens) and Yorkshire fog (Holcus lanatus)/T. repens with or without Lotus corniculatus. There were four replicate groups of six lambs per treatment. The effects of condensed tannins (CT) on lamb production were assessed by twice-daily oral administration of 10g polyethylene glycol (PEG; molecular weight 4000) to half the lambs on each sward. The Lotus content of all swards was very low, and results are presented here for main sward comparisons meaned over lotus treatments. Overall mean estimates of pre-grazing herbage mass and sward surface height for the annual ryegrass and Yorkshire fog swards respectively, were 5820 v. 4360 +/- 190 kg DM/ha (P , P < 0.01) and liveweight gain (141 v. 120 +/- 4.3 g per lamb per day, P < 0.01), although differences in carcass weight (17.9 v. 18.2 +/- 0.3 kg) and FEC transformed values (9.6 v. 11.0 +/- 06 eggs/g fresh faeces) were not significant. The effects of CT on animal performance were greater in Yorkshire fog swards. CT had no significant effects on diet selection, herbage intake and grazing behaviour patterns

    Predicting success in graduate entry medical students undertaking a graduate entry medical program (GEM)

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    Background: Success in undergraduate medical courses in the UK can be predicted by school exit examination (A level) grades. There are no documented predictors of success in UK graduate entry medicine (GEM) courses. This study looks at the examination performance of GEM students to identify factors which may predict success; of particular interest was A level score. Methods: Data was collected for students graduating in 2004, 2005 and 2006, including demographic details (age and gender), details of previous academic achievement (A level total score and prior degree) and examination results at several points during the degree course. Results: Study group comprised 285 students. Statistical analyses identified no significant variables when looking at clinical examinations. Analysis of pass/fail data for written examinations showed no relationship with A level score. However, both percentage data for the final written examination and the analysis of the award of honours showed A level scores of AAB or higher were associated with better performance (p < 0.001). Discussion: A prime objective of introducing GEM programs was to diversify admissions to medical school. In trying to achieve this, medical schools have changed selection criteria. The findings in this study justify this by proving that A level score was not associated with success in either clinical examinations or passing written examinations. Despite this, very high achievements at A level do predict high achievement during medical school. Conclusions: This study shows that selecting graduate medical students with the basic requirement of an upper-second class honours degree is justifiable and does not disadvantage students who may not have achieved high scores in school leaver examinations

    PLAUR polymorphisms and lung function in UK smokers

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    <p>Abstract</p> <p>Background</p> <p>We have previously identified Urokinase Plasminogen Activator Receptor (<it>PLAUR</it>) as an asthma susceptibility gene. In the current study we tested the hypothesis that <it>PLAUR </it>single nucleotide polymorphisms (SNPs) determine baseline lung function and contribute to the development of Chronic Obstructive Pulmonary Disease (COPD) in smokers.</p> <p>Methods</p> <p>25 <it>PLAUR </it>SNPs were genotyped in COPD subjects and individuals with smoking history (n = 992). Linear regression was used to determine the effects of polymorphism on baseline lung function (FEV<sub>1</sub>, FEV<sub>1</sub>/FVC) in all smokers. Genotype frequencies were compared in spirometry defined smoking controls (n = 176) versus COPD cases (n = 599) and COPD severity (GOLD stratification) using logistic regression.</p> <p>Results</p> <p>Five SNPs showed a significant association (p < 0.01) with baseline lung function; rs2302524(Lys220Arg) and rs2283628(intron 3) were associated with lower and higher FEV<sub>1 </sub>respectively. rs740587(-22346), rs11668247(-20040) and rs344779(-3666) in the 5'region were associated with increased FEV<sub>1</sub>/FVC ratio. rs740587 was also protective for COPD susceptibility and rs11668247 was protective for COPD severity although no allele dose relationship was apparent. Interestingly, several of these associations were driven by male smokers not females.</p> <p>Conclusion</p> <p>This study provides tentative evidence that the asthma associated gene <it>PLAUR </it>also influences baseline lung function in smokers. However the case-control analyses do not support the conclusion that <it>PLAUR </it>is a major COPD susceptibility gene in smokers. PLAUR is a key serine protease receptor involved in the generation of plasmin and has been implicated in airway remodelling.</p

    Implication of a retrovirus-like glycoprotein peptide in the immunopathogenesis of Ebola and Marburg viruses

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    Ebola and Marburg viruses can cause hemorrhagic fever (HF) outbreaks with high mortality in primates. Whereas Marburg (MARV), Ebola Zaire (ZEBOV), and Ebola Sudan (SEBOV) viruses are pathogenic in humans, apes, and monkeys, Ebola Reston (REBOV) is pathogenic only in monkeys. Early immunosuppression may contribute to pathogenesis by facilitating viral replication. Lymphocyte depletion, intravascular apoptosis, and cytokine dysregulation are prominent in fatal cases. Here we functionally characterize a 17 amino acid domain in filoviral glycoproteins that resembles an immunosuppressive motif in retroviral envelope proteins. Activated human or rhesus peripheral blood mononuclear cells (PBMC) were exposed to inactivated ZEBOV or a panel of 17mer peptides representing all sequenced strains of filoviruses, then analyzed for CD4+ and CD8+ T cell activation, apoptosis, and cytokine expression. Exposure of human and rhesus PBMC to ZEBOV, SEBOV, or MARV peptides or inactivated ZEBOV resulted in decreased expression of activation markers on CD4 and CD8 cells; CD4 and CD8 cell apoptosis as early as 12 h postexposure; inhibition of CD4 and CD8 cell cycle progression; decreased interleukin (IL)-2, IFN-gamma, and IL12-p40 expression; and increased IL-10 expression. In contrast, only rhesus T cells were sensitive to REBOV peptides. These findings are consistent with the observation that REBOV is not pathogenic in humans and have implications for understanding the pathogenesis of filoviral HF

    Insulin-stimulated phosphorylation of endothelial nitric oxide synthase at serine-615 contributes to nitric oxide synthesis

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    Insulin stimulates endothelial NO (nitric oxide) synthesis via PKB (protein kinase B)/Akt-mediated phosphorylation and activation of eNOS (endothelial NO synthase) at Ser-1177. In previous studies, we have demonstrated that stimulation of eNOS phosphorylation at Ser-1177 may be required, yet is not sufficient for insulin-stimulated NO synthesis. We therefore investigated the role of phosphorylation of eNOS at alternative sites to Ser-1177 as candidate parallel mechanisms contributing to insulin-stimulated NO synthesis. Stimulation of human aortic endothelial cells with insulin rapidly stimulated phosphorylation of both Ser-615 and Ser-1177 on eNOS, whereas phosphorylation of Ser-114, Thr-495 and Ser-633 was unaffected. Insulin-stimulated Ser-615 phosphorylation was abrogated by incubation with the PI3K (phosphoinositide 3-kinase) inhibitor wortmannin, infection with adenoviruses expressing a dominant-negative mutant PKB/Akt or pre-incubation with TNFα (tumour necrosis factor α), but was unaffected by high culture glucose concentrations. Mutation of Ser-615 to alanine reduced insulin-stimulated NO synthesis, whereas mutation of Ser-615 to aspartic acid increased NO production by NOS in which Ser-1177 had been mutated to an aspartic acid residue. We propose that the rapid PKB-mediated stimulation of phosphorylation of Ser-615 contributes to insulin-stimulated NO synthesis

    The epigenetic clock is correlated with physical and cognitive fitness in the Lothian Birth Cohort 1936

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    Background: The DNA methylation-based 'epigenetic clock' correlates strongly with chronological age, but it is currently unclear what drives individual differences. We examine cross-sectional and longitudinal associations between the epigenetic clock and four mortality-linked markers of physical and mental fitness: lung function, walking speed, grip strength and cognitive ability. Methods: DNA methylation-based age acceleration (residuals of the epigenetic clock estimate regressed on chronological age) were estimated in the Lothian Birth Cohort 1936 at ages 70 (n=920), 73 (n=299) and 76 (n=273) years. General cognitive ability, walking speed, lung function and grip strength were measured concurrently. Cross-sectional correlations between age acceleration and the fitness variables were calculated. Longitudinal change in the epigenetic clock estimates and the fitness variables were assessed via linear mixed models and latent growth curves. Epigenetic age acceleration at age 70 was used as a predictor of longitudinal change in fitness. Epigenome-wide association studies (EWASs) were conducted on the four fitness measures. Results: Cross-sectional correlations were significant between greater age acceleration and poorer performance on the lung function, cognition and grip strength measures (r range: -0.07 to -0.05, P range: 9.7 x 10 to 0.024). All of the fitness variables declined over time but age acceleration did not correlate with subsequent change over 6 years. There were no EWAS hits for the fitness traits. Conclusions: Markers of physical and mental fitness are associated with the epigenetic clock (lower abilities associated with age acceleration). However, age acceleration does not associate with decline in these measures, at least over a relatively short follow-up

    Clustered Cardiometabolic Risk, Cardiorespiratory Fitness and Physical Activity in 10-11 Year-Old Children. The CHANGE! Project Baseline

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    Objectives: The primary objective of this cross sectional pilot study was to report clustered risk scores combining traditional invasive with non invasive cardiometabolic risk markers in 10-11 year old children participating in the CHANGE! project at baseline. A secondary objective was to determine the relationship between clustered risk score and objectively measured physical activity (PA) and cardiorespiratory fitness (CRF). Methods: Habitual PA was measured using accelerometry and CRF (VO2peak) was assessed using an individually calibrated treadmill based protocol. Twenty-nine participants had valid data for all components of the clustered risk score, calculated using total cholesterol: high density lipoprotein-cholesterol (TC:HDL-C), glucose, systolic blood pressure (BP), LV Mass Index (g/m2.7), and trunk fat mass (g). Participants with a clustered risk score greater than 1SD above the mean, were categorised as ‘higher’ risk (n=6); all others were categorised as ‘normal’ risk. \ud \ud Results: Clustered risk score, controlling for somatic maturity and gender, was negatively correlated with VPA (r= -0.51, p=0.01), MVPA (r= -0.44, p=0.03) and VO2peak (r= -0.57, p<0.01). ANCOVA, with somatic maturity and gender as covariates, revealed that those in the ‘normal’ risk group were more fit than those in the ‘higher’ risk group [f (1,24)=4.518, p=0.044]). There were no statistically significant differences between risk groups and PA however mean data suggest that those in the ‘normal’ risk group accrued 4 minutes more daily VPA than the ‘higher’ risk group which may be clinically important. \ud \ud Conclusions: This provides further evidence of the importance of promoting CRF and VPA in children, to reduce cardiometabolic risk especially for those that are ‘higher’ risk

    The occupation of a box as a toy model for the seismic cycle of a fault

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    We illustrate how a simple statistical model can describe the quasiperiodic occurrence of large earthquakes. The model idealizes the loading of elastic energy in a seismic fault by the stochastic filling of a box. The emptying of the box after it is full is analogous to the generation of a large earthquake in which the fault relaxes after having been loaded to its failure threshold. The duration of the filling process is analogous to the seismic cycle, the time interval between two successive large earthquakes in a particular fault. The simplicity of the model enables us to derive the statistical distribution of its seismic cycle. We use this distribution to fit the series of earthquakes with magnitude around 6 that occurred at the Parkfield segment of the San Andreas fault in California. Using this fit, we estimate the probability of the next large earthquake at Parkfield and devise a simple forecasting strategy.Comment: Final version of the published paper, with an erratum and an unpublished appendix with some proof

    Whole-Retina Reduced Electrophysiological Activity in Mice Bearing Retina-Specific Deletion of Vesicular Acetylcholine Transporter

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    Background: Despite rigorous characterization of the role of acetylcholine in retinal development, long-term effects of its absence as a neurotransmitter are unknown. One of the unanswered questions is how acetylcholine contributes to the functional capacity of mature retinal circuits. The current study investigates the effects of disrupting cholinergic signalling in mice, through deletion of vesicular acetylcholine transporter (VAChT) in the developing retina, pigmented epithelium, optic nerve and optic stalk, on electrophysiology and structure of the mature retina. Methods & Results A combination of electroretinography, optical coherence tomography imaging and histological evaluation assessed retinal integrity in mice bearing retina-targeted (embryonic day 12.5) deletion of VAChT (VAChT(Six3-Cre-flox/flox)) and littermate controls at 5 and 12 months of age. VAChT(Six3-Cre-flox/flox) mice did not show any gross changes in nuclear layer cellularity or synaptic layer thickness. However, VAChT(Six3-Cre-flox/flox) mice showed reduced electrophysiological response of the retina to light stimulus under scotopic conditions at 5 and 12 months of age, including reduced a-wave, b-wave, and oscillatory potential (OP) amplitudes and decreased OP peak power and total energy. Reduced a-wave amplitude was proportional to the reduction in b-wave amplitude and not associated with altered a-wave 10%-90% rise time or inner and outer segment thicknesses. Significance This study used a novel genetic model in the first examination of function and structure of the mature mouse retina with disruption of cholinergic signalling. Reduced amplitude across the electroretinogram wave form does not suggest dysfunction in specific retinal cell types and could reflect underlying changes in the retinal and/or extraretinal microenvironment. Our findings suggest that release of acetylcholine by VAChT is essential for the normal electrophysiological response of the mature mouse retina
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