1,727 research outputs found

    Global late Quaternary megafauna extinctions linked to humans, not climate change

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    The late Quaternary megafauna extinction was a severe global-scale event. Two factors, climate change and modern humans, have received broad support as the primary drivers, but their absolute and relative importance remains controversial. To date, focus has been on the extinction chronology of individual or small groups of species, specific geographical regions or macroscale studies at very coarse geographical and taxonomic resolution, limiting the possibility of adequately testing the proposed hypotheses. We present, to our knowledge, the first global analysis of this extinction based on comprehensive country-level data on the geographical distribution of all large mammal species (more than or equal to 10 kg) that have gone globally or continentally extinct between the beginning of the Last Interglacial at 132 000 years BP and the late Holocene 1000 years BP, testing the relative roles played by glacial–interglacial climate change and humans. We show that the severity of extinction is strongly tied to hominin palaeobiogeography, with at most a weak, Eurasia-specific link to climate change. This first species-level macroscale analysis at relatively high geographical resolution provides strong support for modern humans as the primary driver of the worldwide megafauna losses during the late Quaternary

    Neutralizing antibodies explain the poor clinical response to Interferon beta in a small proportion of patients with Multiple Sclerosis: a retrospective study

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    <p>Abstract</p> <p>Background</p> <p>Neutralizing antibodies (NAbs) against Interferon beta (IFNβ) are reported to be associated with poor clinical response to therapy in multiple sclerosis (MS) patients. We aimed to quantify the contribution of NAbs to the sub-optimal response of IFNβ treatment.</p> <p>Methods</p> <p>We studied the prevalence of NAbs in MS patients grouped according to their clinical response to IFNβ during the treatment period. Patients were classified as: group A, developing ≥ 1 relapse after the first 6 months of therapy; group B, exhibiting confirmed disability progression after the first 6 months of therapy, with or without superimposed relapses; group C, presenting a stable disease course during therapy. A cytopathic effect assay tested the presence of NAbs in a cohort of ambulatory MS patients treated with one of the available IFNβ formulations for at least one year. NAbs positivity was defined as NAbs titre ≥ 20 TRU.</p> <p>Results</p> <p>Seventeen patients (12.1%) were NAbs positive. NAbs positivity correlated with poorer clinical response (<it>p </it>< 0.04). As expected, the prevalence of NAbs was significantly lower in Group C (2.1%) than in Group A (17.0%) and Group B (17.0%). However, in the groups of patients with a poor clinical response (A, B), NAbs positivity was found only in a small proportion of patients.</p> <p>Conclusion</p> <p>The majority of patients with poor clinical response are NAbs negative suggesting that NAbs explains only partially the sub-optimal response to IFNβ.</p

    Alternative statistical methods for estimating efficacy of interferon beta-1b for multiple sclerosis clinical trials

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    <p>Abstract</p> <p>Background</p> <p>In the randomized study of interferon beta-1b (IFN beta-1b) for multiple sclerosis (MS), it has usually been evaluated the simple annual relapse rate as the study endpoint. This study aimed to investigate the performance of various regression models using information regarding the time to each recurrent event and considering the MS specific data generation process, and to estimate the treatment effect of a MS clinical trial data.</p> <p>Methods</p> <p>We conducted a simulation study with consideration of the pathological characteristics of MS, and applied alternative efficacy estimation methods to real clinical trial data, including 5 extended Cox regression models for time-to-event analysis, a Poisson regression model and a Poisson regression model with Generalized Estimating Equations (GEE). We adjusted for other important covariates that may have affected the outcome.</p> <p>Results</p> <p>We compared the simulation results for each model. The hazard ratios of real data were estimated for each model including the effects of other covariates. The results (hazard ratios of high-dose to low-dose) of all models were approximately 0.7 (range, 0.613 - 0.769), whereas the annual relapse rate ratio was 0.714.</p> <p>Conclusions</p> <p>The precision of the treatment estimation was increased by application of the alternative models. This suggests that the use of alternative models that include recurrence event data may provide better analyses.</p

    TOZAL Study: An open case control study of an oral antioxidant and omega-3 supplement for dry AMD

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    BACKGROUND: The primary objective of this prospective study was to measure the change from baseline in visual function – Best-Corrected Visual Acuity (BCVA) via the Early Treatment Diabetic Retinopathy Study (ETDRS) chart, contrast sensitivity, central 10 degree visual fields and retinal imaging (angiograms and photographs) at 6 months in subjects with atrophic (dry) age-related macular degeneration treated with a targeted nutritional supplement. METHODS: 37 mixed gender patients with a mean age of 76.3 +/- 7.8 years were enrolled at 5 independent study sites and received standard of care with a novel formulation of a nutritional supplement. Results were compared to a placebo cohort constructed from the literature that was matched for inclusion and exclusion criteria. A paired t-test was used to test a null hypothesis and a two-sided alpha level of 0.05 was used to determine statistical significance. RESULTS: 76.7% of subjects receiving the nutritional supplement demonstrated stabilization or improvement of BCVA at 6 months. Subjects gained an average of 0.0541 logMAR or one-half of a line of visual acuity (VA) over the 6-month period. There was a statistically significant improvement in VA from baseline with P = .045. The results provide strong evidence that the treatment being studied produces an improvement in VA. CONCLUSION: Treatment with this unique nutritional supplement increased VA above the expected baseline decrease in the majority of patients in this population with dry macular degeneration. The results of the TOZAL study agree with the LAST and CARMIS studies and are predictive for positive visual acuity outcomes in the AREDS II trial. However, patients will likely require supplementation for longer than 6 months to effect changes in additional visual parameters

    Profiling allele-specific gene expression in brains from individuals with autism spectrum disorder reveals preferential minor allele usage.

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    One fundamental but understudied mechanism of gene regulation in disease is allele-specific expression (ASE), the preferential expression of one allele. We leveraged RNA-sequencing data from human brain to assess ASE in autism spectrum disorder (ASD). When ASE is observed in ASD, the allele with lower population frequency (minor allele) is preferentially more highly expressed than the major allele, opposite to the canonical pattern. Importantly, genes showing ASE in ASD are enriched in those downregulated in ASD postmortem brains and in genes harboring de novo mutations in ASD. Two regions, 14q32 and 15q11, containing all known orphan C/D box small nucleolar RNAs (snoRNAs), are particularly enriched in shifts to higher minor allele expression. We demonstrate that this allele shifting enhances snoRNA-targeted splicing changes in ASD-related target genes in idiopathic ASD and 15q11-q13 duplication syndrome. Together, these results implicate allelic imbalance and dysregulation of orphan C/D box snoRNAs in ASD pathogenesis

    Exploring the equity of GP practice prescribing rates for selected coronary heart disease drugs: a multiple regression analysis with proxies of healthcare need

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    Background There is a small, but growing body of literature highlighting inequities in GP practice prescribing rates for many drug therapies. The aim of this paper is to further explore the equity of prescribing for five major CHD drug groups and to explain the amount of variation in GP practice prescribing rates that can be explained by a range of healthcare needs indicators (HCNIs). Methods The study involved a cross-sectional secondary analysis in four primary care trusts (PCTs 1–4) in the North West of England, including 132 GP practices. Prescribing rates (average daily quantities per registered patient aged over 35 years) and HCNIs were developed for all GP practices. Analysis was undertaken using multiple linear regression. Results Between 22–25% of the variation in prescribing rates for statins, beta-blockers and bendrofluazide was explained in the multiple regression models. Slightly more variation was explained for ACE inhibitors (31.6%) and considerably more for aspirin (51.2%). Prescribing rates were positively associated with CHD hospital diagnoses and procedures for all drug groups other than ACE inhibitors. The proportion of patients aged 55–74 years was positively related to all prescribing rates other than aspirin, where they were positively related to the proportion of patients aged >75 years. However, prescribing rates for statins and ACE inhibitors were negatively associated with the proportion of patients aged >75 years in addition to the proportion of patients from minority ethnic groups. Prescribing rates for aspirin, bendrofluazide and all CHD drugs combined were negatively associated with deprivation. Conclusion Although around 25–50% of the variation in prescribing rates was explained by HCNIs, this varied markedly between PCTs and drug groups. Prescribing rates were generally characterised by both positive and negative associations with HCNIs, suggesting possible inequities in prescribing rates on the basis of ethnicity, deprivation and the proportion of patients aged over 75 years (for statins and ACE inhibitors, but not for aspirin)

    The combination of amlodipine and angiotensin receptor blocker or diuretics in high-risk hypertensive patients: rationale, design and baseline characteristics

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    The Chinese Hypertension Intervention Efficacy Study (CHIEF) is a multi-centre randomized controlled clinical trial comparing the effects of amlodipine+angiotensin II receptor blocker and amlodipine+diuretics on the incidence of cardiovascular events, represented as a composite of non-fatal stroke, non-fatal myocardial infarction and cardiovascular death events in high-risk Chinese hypertensive patients. The study also evaluates the long-term effects of lipid-lowering treatment and lifestyle modification. From October 2007 to October 2008, 13 542 patients were enrolled into the study in 180 centres in China. Patients will be followed up for 4 years. There was no difference in baseline characteristics between the two blood pressure arms

    The comparative performance of three screening questionnaires for psoriatic arthritis in a primary care surveillance study.

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    Objectives To compare the performance of three psoriatic arthritis (PsA) screening questionnaires in a primary care psoriasis surveillance study. Methods Participants with psoriasis, and not known to have psoriatic arthritis (PsA), were identified from general practice databases and invited to attend a secondary care centre for a clinical assessment. The three patient-completed screening questionnaires (PEST, CONTEST, and CONTESTjt) were administered along with other patient reported measures and a clinical examination of skin and joints was performed. Participants who demonstrated signs of inflammatory arthritis suggestive of PsA were referred, via their GP, for a further assessment in a secondary care rheumatology clinic. Results A total of 791 participants attended the screening visit and 165 participants were judged to have signs and symptoms of inflammatory arthritis, of which 150 were referred for assessment. Of these 126 were seen and 48 were diagnosed with PsA. The results for each questionnaire were as follows: PEST: Sensitivity 0.625 (95% CI 0.482–0.749), specificity 0.757 (0.724–0.787). CONTEST: Sensitivity 0.604 (0.461–0.731), specificity 0.768 (0.736–0.798). CONTESTjt: Sensitivity 0.542 (0.401–0.676), specificity 0.834 (0.805–0.859). CONTESTjt demonstrated marginally superior specificity to PEST though the area under the ROC curve was similar for all three instruments. Conclusions Minimal differences between the three screening questionnaires were found in this study and no preference can be made based on these results. The choice of which instrument to choose will depend on other factors, such as simplicity and low patient burden
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