Crowdsourcing hypothesis tests: Making transparent how design choices shape research results

To what extent are research results influenced by subjective decisions that scientists make as they design studies? Fifteen research teams independently designed studies to answer fiveoriginal research questions related to moral judgments, negotiations, and implicit cognition. Participants from two separate large samples (total N > 15,000) were then randomly assigned to complete one version of each study. Effect sizes varied dramatically across different sets of materials designed to test the same hypothesis: materials from different teams renderedstatistically significant effects in opposite directions for four out of five hypotheses, with the narrowest range in estimates being d = -0.37 to +0.26. Meta-analysis and a Bayesian perspective on the results revealed overall support for two hypotheses, and a lack of support for three hypotheses. Overall, practically none of the variability in effect sizes was attributable to the skill of the research team in designing materials, while considerable variability was attributable to the hypothesis being tested. In a forecasting survey, predictions of other scientists were significantly correlated with study results, both across and within hypotheses. Crowdsourced testing of research hypotheses helps reveal the true consistency of empirical support for a scientific claim.</div

Meta-analysis of 375,000 individuals identifies 38 susceptibility loci for migraine

Migraine is a debilitating neurological disorder affecting around one in seven people worldwide, but its molecular mechanisms remain poorly understood. There is some debate about whether migraine is a disease of vascular dysfunction or a result of neuronal dysfunction with secondary vascular changes. Genome-wide association (GWA) studies have thus far identified 13 independent loci associated with migraine. To identify new susceptibility loci, we carried out a genetic study of migraine on 59,674 affected subjects and 316,078 controls from 22 GWA studies. We identified 44 independent single-nucleotide polymorphisms (SNPs) significantly associated with migraine risk (P < 5 × 10−8) that mapped to 38 distinct genomic loci, including 28 loci not previously reported and a locus that to our knowledge is the first to be identified on chromosome X. In subsequent computational analyses, the identified loci showed enrichment for genes expressed in vascular and smooth muscle tissues, consistent with a predominant theory of migraine that highlights vascular etiologies

Ethical dilemmas in adult ECMO: emerging conceptual challenges

10.1053/j.jvca.2014.07.015Journal of cardiothoracic and vascular anesthesia291229-23

Anti-ulcerogenic activity of the root bark extract of the African laburnum <it>“Cassia sieberiana”</it> and its effect on the anti-oxidant defence system in rats

<p>Abstract</p> <p>Background</p> <p>Despite the widespread use of roots of <it>Cassia sieberiana</it> in managing several health conditions including gastric ulcer disease, there is little scientific data to support the rational phytotherapeutics as an anti-ulcer agent. This paper reports an evaluation of the <it>in vivo</it> anti-oxidant properties of an aqueous root bark extract of <it>C. sieberiana</it> in experimental gastric ulcer rats in a bid to elucidate its mechanism of action.</p> <p>Methods</p> <p>Fisher 344 (F₃₄₄) rats received pretreatment of <it>C. sieberiana</it> root bark extract (500, 750, and 1000 mg/kg body wt.) for 7 days after which there was induction of gastric injury with absolute ethanol. The mean ulcer index (MUI) was calculated and serum total anti-oxidant level determined. Gastric mucosal tissues were prepared and the activity level of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and myeloperoxidase (MPO) were measured together with the level of lipid hydroperoxides (LPO). Statistical difference between treatment groups was analysed using one-way analysis of variance (ANOVA) followed by Dunnett’s <it>post hoc t</it> test. Statistical significance was calculated at P< 0.05.</p> <p>Results</p> <p>The administration of ethanol triggered severe acute gastric ulcer and pretreatment with <it>C. sieberiana</it> root bark extract significantly and dose dependently protected against this effect. The root bark extract also dose dependently and significantly inhibited the ethanol induced decrease in activity levels of the enzymes SOD, CAT and GPx. The extract also inhibited the ethanol-induced decrease in level of serum total anti-oxidant capacity. The increase in ethanol-induced LPO level and MPO activity were also significantly and dose-dependently inhibited by the root bark extract.</p> <p>Conclusions</p> <p>The gastro-cytoprotective effect, inhibition of decrease in activity of gastric anti-oxidant enzymes and MPO as well as the inhibition of gastric LPO level suggests that one of the anti-ulcer mechanisms of <it>C. sieberiana</it> is the anti-oxidant property.</p