Balancing the dilution and oddity effects: Decisions depend on body size

Background Grouping behaviour, common across the animal kingdom, is known to reduce an individual's risk of predation; particularly through dilution of individual risk and predator confusion (predator inability to single out an individual for attack). Theory predicts greater risk of predation to individuals more conspicuous to predators by difference in appearance from the group (the ‘oddity’ effect). Thus, animals should choose group mates close in appearance to themselves (eg. similar size), whilst also choosing a large group. Methodology and Principal Findings We used the Trinidadian guppy (Poecilia reticulata), a well known model species of group-living freshwater fish, in a series of binary choice trials investigating the outcome of conflict between preferences for large and phenotypically matched groups along a predation risk gradient. We found body-size dependent differences in the resultant social decisions. Large fish preferred shoaling with size-matched individuals, while small fish demonstrated no preference. There was a trend towards reduced preferences for the matched shoal under increased predation risk. Small fish were more active than large fish, moving between shoals more frequently. Activity levels increased as predation risk decreased. We found no effect of unmatched shoal size on preferences or activity. Conclusions and Significance Our results suggest that predation risk and individual body size act together to influence shoaling decisions. Oddity was more important for large than small fish, reducing in importance at higher predation risks. Dilution was potentially of limited importance at these shoal sizes. Activity levels may relate to how much sampling of each shoal was needed by the test fish during decision making. Predation pressure may select for better decision makers to survive to larger size, or that older, larger fish have learned to make shoaling decisions more efficiently, and this, combined with their size relative to shoal-mates, and attractiveness as prey items influences shoaling decisions

Common polymorphisms within the NR4A3 locus, encoding the orphan nuclear receptor Nor-1, are associated with enhanced β-cell function in non-diabetic subjects

<p>Abstract</p> <p>Background</p> <p>Neuron-derived orphan receptor (Nor) 1, nuclear receptor (Nur) 77, and nuclear receptor-related protein (Nurr) 1 constitute the NR4A family of orphan nuclear receptors which were recently found to modulate hepatic glucose production, insulin signalling in adipocytes, and oxidative metabolism in skeletal muscle. In this study, we assessed whether common genetic variation within the <it>NR4A3 </it>locus, encoding Nor-1, contributes to the development of prediabetic phenotypes, such as glucose intolerance, insulin resistance, or β-cell dysfunction.</p> <p>Methods</p> <p>We genotyped 1495 non-diabetic subjects from Southern Germany for the five tagging single nucleotide polymorphisms (SNPs) rs7047636, rs1526267, rs2416879, rs12686676, and rs10819699 (minor allele frequencies ≥ 0.05) covering 100% of genetic variation within the <it>NR4A3 </it>locus (with D' = 1.0, r²≥ 0.9) and assessed their association with metabolic data derived from the fasting state, an oral glucose tolerance test (OGTT), and a hyperinsulinemic-euglycemic clamp (subgroup, N = 506). SNPs that revealed consistent associations with prediabetic phenotypes were subsequently genotyped in a second cohort (METSIM Study; Finland; N = 5265) for replication.</p> <p>Results</p> <p>All five SNPs were in Hardy-Weinberg equilibrium (p ≥ 0.7, all). The minor alleles of three SNPs, i.e., rs1526267, rs12686676, and rs10819699, consistently tended to associate with higher insulin release as derived from plasma insulin at 30 min(OGTT), AUC_C-peptide-to-AUC_Glucratio and the AUC_Ins30-to-AUC_Gluc30ratio with rs12686676 reaching the level of significance (p ≤ 0.03, all; additive model). The association of the SNP rs12686676 with insulin secretion was replicated in the METSIM cohort (p ≤ 0.03, additive model). There was no consistent association with glucose tolerance or insulin resistance in both study cohorts.</p> <p>Conclusion</p> <p>We conclude that common genetic variation within the <it>NR4A3 </it>locus determines insulin secretion. Thus, <it>NR4A3 </it>represents a novel candidate gene for β-cell function which was not covered by the SNP arrays of recent genome-wide association studies for type 2 diabetes mellitus.</p

Comparison of risk-scoring systems in the prediction of outcome after liver resection

Background: Risk prediction techniques commonly used in liver surgery include the American Society of Anesthesiologists (ASA) grading, Charlson Comorbidity Index (CCI) and cardiopulmonary exercise tests (CPET). This study compares the utility of these techniques along with the number of segments resected as predictive tools in liver surgery. Methods: A review of a unit database of patients undergoing liver resection between February 2008 and January 2015 was undertaken. Patient demographics, ASA, CCI and CPET variables were recorded along with resection size. Clavien-Dindo grade III–V complications were used as a composite outcome in analyses. Association between predictive variables and outcome was assessed by univariate and multivariate techniques. Results: One hundred and seventy-two resections in 168 patients were identified. Grade III–V complications occurred after 42 (24.4%) liver resections. In univariate analysis of CPET variables, ventilatory equivalents for CO2 (VEqCO2) was associated with outcome. CCI score, but not ASA grade, was also associated with outcome. In multivariate analysis, the odds ratio of developing grade III–V complications for incremental increases in VEqCO2, CCI and number of liver segments resected were 1.09, 1.49 and 2.94, respectively. Conclusions: Of the techniques evaluated, resection size provides the simplest and most discriminating predictor of significant complications following liver surgery

Tranexamic acid for intracerebral haemorrhage within 2 hours of onset : protocol of a phase II randomised placebo-controlled double-blind multicentre trial

Rationale Haematoma growth is common early after intracerebral haemorrhage (ICH), and is a key determinant of outcome. Tranexamic acid, a widely available antifibrinolytic agent with an excellent safety profile, may reduce haematoma growth. Methods and design Stopping intracerebral haemorrhage with tranexamic acid for hyperacute onset presentation including mobile stroke units (STOP-MSU) is a phase II double-blind, randomised, placebo-controlled, multicentre, international investigator-led clinical trial, conducted within the estimand statistical framework. Hypothesis In patients with spontaneous ICH, treatment with tranexamic acid within 2 hours of onset will reduce haematoma expansion compared with placebo. Sample size estimates A sample size of 180 patients (90 in each arm) would be required to detect an absolute difference in the primary outcome of 20% (placebo 39% vs treatment 19%) under a two-tailed significance level of 0.05. An adaptive sample size re-estimation based on the outcomes of 144 patients will allow a possible increase to a prespecified maximum of 326 patients. Intervention Participants will receive 1 g intravenous tranexamic acid over 10 min, followed by 1 g intravenous tranexamic acid over 8 hours; or matching placebo. Primary efficacy measure The primary efficacy measure is the proportion of patients with haematoma growth by 24 +/- 6 hours, defined as either >= 33% relative increase or >= 6 mL absolute increase in haematoma volume between baseline and follow-up CT scan. Discussion We describe the rationale and protocol of STOP-MSU, a phase II trial of tranexamic acid in patients with ICH within 2 hours from onset, based in participating mobile stroke units and emergency departments.Peer reviewe

Evaluating comorbidities in total hip and knee arthroplasty: available instruments

Each year millions of patients are treated for joint pain with total joint arthroplasty, and the numbers are expected to rise. Comorbid disease is known to influence the outcome of total joint arthroplasty, and its documentation is therefore of utmost importance in clinical evaluation of the individual patient as well as in research. In this paper, we examine the various methods for obtaining and assessing comorbidity information for patients undergoing joint replacement. Multiple instruments are reliable and validated for this purpose, such as the Charlson Index, Index of Coexistent Disease, and the Functional Comorbidity Index. In orthopedic studies, the Charnley classification and the American Society of Anesthesiologists physical function score (ASA) are widely used. We recommend that a well-documented comorbidity index that incorporates some aspect of mental health is used along with other appropriate instruments to objectively assess the preoperative status of the patient

Women’s, partners’ and healthcare providers’ views and experiences of assisted vaginal birth: a systematic mixed methods review

Background When certain complications arise during the second stage of labour, assisted vaginal delivery (AVD), a vaginal birth with forceps or vacuum extractor, can effectively improve outcomes by ending prolonged labour or by ensuring rapid birth in response to maternal or fetal compromise. In recent decades, the use of AVD has decreased in many settings in favour of caesarean section (CS). This review aimed to improve understanding of experiences, barriers and facilitators for AVD use. Methods Systematic searches of eight databases using predefined search terms to identify studies reporting views and experiences of maternity service users, their partners, health care providers, policymakers, and funders in relation to AVD. Relevant studies were assessed for methodological quality. Qualitative findings were synthesised using a meta-ethnographic approach. Confidence in review findings was assessed using GRADE CERQual. Findings from quantitative studies were synthesised narratively and assessed using an adaptation of CERQual. Qualitative and quantitative review findings were triangulated using a convergence coding matrix. Results Forty-two studies (published 1985–2019) were included: six qualitative, one mixed-method and 35 quantitative. Thirty-five were from high-income countries, and seven from LMIC settings. Confidence in the findings was moderate or low. Spontaneous vaginal birth was most likely to be associated with positive short and long-term outcomes, and emergency CS least likely. Views and experiences of AVD tended to fall somewhere between these two extremes. Where indicated, AVD can be an effective, acceptable alternative to caesarean section. There was agreement or partial agreement across qualitative studies and surveys that the experience of AVD is impacted by the unexpected nature of events and, particularly in high-income settings, unmet expectations. Positive relationships, good communication, involvement in decision-making, and (believing in) the reason for intervention were important mediators of birth experience. Professional attitudes and skills (development) were simultaneously barriers and facilitators of AVD in quantitative studies. Conclusions Information, positive interaction and communication with providers and respectful care are facilitators for acceptance of AVD. Barriers include lack of training and skills for decision-making and use of instruments