Weathering the storm: parental effort and experimental manipulation of stress hormones predict brood survival

BACKGROUND:Unpredictable and inclement weather is increasing in strength and frequency, challenging organisms to respond adaptively. One way in which animals respond to environmental challenges is through the secretion of glucocorticoid stress hormones. These hormones mobilize energy stores and suppress non-essential physiological and behavioral processes until the challenge passes. To investigate the effects of glucocorticoids on reproductive decisions, we experimentally increased corticosterone levels (the primary glucocorticoid in birds) in free-living female tree swallows, Tachycineta bicolor, during the chick-rearing stage. Due to an unprecedented cold and wet breeding season, 90% of the nests in our study population failed, which created a unique opportunity to test how challenging environmental conditions interact with the physiological mechanisms underlying life-history trade-offs.RESULTS:We found that exogenous corticosterone influenced the regulation of parental decisions in a context-dependent manner. Control and corticosterone-treated females had similar brood failure rates under unfavorable conditions (cold and rainy weather), but corticosterone treatment hastened brood mortality under more favorable conditions. Higher female nest provisioning rates prior to implantation were associated with increased probability of brood survival for treatment and control groups. However, higher pre-treatment male provisioning rates were associated with increased survival probability in the control group, but not the corticosterone-treated group.CONCLUSIONS:These findings reveal complex interactions between weather, female physiological state, and partner parental investment. Our results also demonstrate a causal relationship between corticosterone concentrations and individual reproductive behaviors, and point to a mechanism for why naturally disturbed populations, which experience multiple stressors, could be more susceptible and unable to respond adaptively to changing environmental conditions

Understanding the social context of fatal road traffic collisions among young people: A qualitative analysis of narrative text in coroners' records

Background: Deaths and injuries on the road remain a major cause of premature death among young people across the world. Routinely collected data usually focuses on the mechanism of road traffic collisions and basic demographic data of those involved. This study aimed to supplement these routine sources with a thematic analysis of narrative text contained in coroners' records, to explore the wider social context in which collisions occur. Methods. Thematic analysis of narrative text from Coroners' records, retrieved from thirty-four fatalities among young people (16-24 year olds) occurring as a result of thirty road traffic collisions in a rural county in the south of England over the period 2005-2010. Results: Six key themes emerged: social driving, driving experience, interest in motor vehicles, driving behaviour, perception of driving ability, and emotional distress. Social driving (defined as a group of related behaviours including: driving as a social event in itself (i.e. without a pre-specified destination); driving to or from a social event; driving with accompanying passengers; driving late at night; driving where alcohol or drugs were a feature of the journey) was identified as a common feature across cases. Conclusions: Analysis of the wider social context in which road traffic collisions occur in young people can provide important information for understanding why collisions happen and developing targeted interventions to prevent them. It can complement routinely collected data, which often focuses on events immediately preceding a collision. Qualitative analysis of narrative text in coroner's records may provide a way of providing this type of information. These findings provide additional support for the case for Graduated Driver Licensing programmes to reduce collisions involving young people, and also suggest that road safety interventions need to take a more community development approach, recognising the importance of social context and focusing on social networks of young people. © 2014 Pilkington et al.; licensee BioMed Central Ltd

Hyperglycaemia in pregnancy in Mediterranean women.

New diagnostic criteria have recently been proposed that will result in a higher proportion of individuals being diagnosed as suffering from gestational diabetes mellitus (GDM) than previously. The present circum-Mediterranean study sets out to identify the relevance of the new criteria in this population. The study was a prospective, non-interventional, multicentre study in the Mediterranean region. A convenient sample of 1,368 pregnant women was recruited. All participants underwent a 75 g oGTT subdivided into five different glycaemic categories. The women's anthropomorphic and biological data, together with obstetric and infant outcomes, were collected. There was a threefold increase in diagnosis using the new criteria. Most of the biological characteristics generally associated with GDM showed high specificity and low sensitivity values. The biological characteristics, including maternal age, BMI and FBG, showed a progressive increase as a function of maternal glycaemia with moderate sensitivity and specificity values. Using these latter characteristics in combination ensures that 72.3 % of the GDM population would be correctly identified, while an oGTT would only be required in 18.7 % of the population. The progressive relationship of increasing glycaemia to adverse characteristics suggests that the new IADPSG criteria are reasonable provided that dietary advice is given to all pregnant women. In situations of economic restraints, it appears possible to screen Mediterranean women for GDM risk using a composite model using FBG >5.0 mmol/l combined with the performance of an oGTT in women with a low FBG but who are overweight and aged >30 years

A composite risk assessment model to screen for gestational diabetes mellitus among Mediterranean women.

OBJECTIVE: To determine whether clinical risk assessment for gestational diabetes mellitus (GDM) may preclude the need for universal screening with an oral glucose tolerance test (OGTT) in situations of economic restraint. METHODS: Women with either GDM (n=119) or normal glucose tolerance (n=1249) were recruited from centers among 11 Mediterranean countries between August 1, 2010, and May 31, 2011. Outcome measures included anthropomorphic and biological data, obstetric outcomes, and infant outcomes. RESULTS: Significant risk factors for GDM included maternal age of 30 years or more; elevated body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters); elevated diastolic blood pressure; previous history of macrosomia; and family history of diabetes mellitus. These factors each had high specificity but low sensitivity for predicting GDM; however, when used in combination, sensitivity increased but specificity fell. Fasting blood glucose (FBG) level had high sensitivity (73.9%) and specificity (90.2%) for predicting GDM. Sensitivity was further increased by combining FBG measurement with maternal age and BMI (96.6%). CONCLUSION: Use of a composite model to prescreen women for GDM risk may reduce the need for universal screening with the OGTT among centers facing health-cost pressures