Genome-wide meta-analysis uncovers novel loci influencing circulating leptin levels.

Leptin is an adipocyte-secreted hormone, the circulating levels of which correlate closely with overall adiposity. Although rare mutations in the leptin (LEP) gene are well known to cause leptin deficiency and severe obesity, no common loci regulating circulating leptin levels have been uncovered. Therefore, we performed a genome-wide association study (GWAS) of circulating leptin levels from 32,161 individuals and followed up loci reaching P<10(-6) in 19,979 additional individuals. We identify five loci robustly associated (P<5 × 10(-8)) with leptin levels in/near LEP, SLC32A1, GCKR, CCNL1 and FTO. Although the association of the FTO obesity locus with leptin levels is abolished by adjustment for BMI, associations of the four other loci are independent of adiposity. The GCKR locus was found associated with multiple metabolic traits in previous GWAS and the CCNL1 locus with birth weight. Knockdown experiments in mouse adipose tissue explants show convincing evidence for adipogenin, a regulator of adipocyte differentiation, as the novel causal gene in the SLC32A1 locus influencing leptin levels. Our findings provide novel insights into the regulation of leptin production by adipose tissue and open new avenues for examining the influence of variation in leptin levels on adiposity and metabolic health

Simulated predator extinctions: Predator identity affects survival and recruitment of oysters

The rate of species loss is increasing at a global scale, and human-induced extinctions are biased toward predator species. We examined the effects of predator extinctions on a foundation species, the eastern oyster (Crassostrea virginica). We performed a factorial experiment manipulating the presence and abundance of three of the most common predatory crabs, the blue crab (Callinectes sapidus), stone crab (Menippe mercenaria), and mud crab (Panopeus herbstii) in estuaries in the eastern United States. We tested the effects of species richness and identity of predators on juvenile oyster survival, oyster recruitment, and organic matter content of sediment. We also manipulated the density of each of the predators and controlled for the loss of biomass of species by maintaining a constant mass of predators in one set of treatments and simultaneously using an additive design. This design allowed us to test the density dependence of our results and test for functional compensation by other species. The identity of predator species, but not richness, affected oyster populations. The loss of blue crabs, alone or in combination with either of the other species, affected the survival rate of juvenile oysters. Blue crabs and stone crabs both affected oyster recruitment and sediment organic matter negatively. Mud crabs at higher than ambient densities, however, could fulfill some of the functions of blue and stone crabs, suggesting a level of ecological redundancy. Importantly, the strong effects of blue crabs in all processes measured no longer occurred when individuals were present at higher-than-ambient densities. Their role as dominant predator is, therefore, dependent on their density within the system and the density of other species within their guild (e.g., mud crabs). Our findings support the hypothesis that the effects of species loss at higher trophic levels are determined by predator identity and are subject to complex intraguild interactions that are largely density dependent. Understanding the role of biodiversity in ecosystem functioning or addressing practical concerns, such as loss of predators owing to overharvesting, remains complicated because accurate predictions require detailed knowledge of the system and should be drawn from sound experimental evidence, not based on observations or generalized models

The inner barrier: How health psychology concepts contribute to the explanation of prehospital delays in acute myocardial infarction: A systematic analysis of the current state of knowledge.

During onset of an acute myocardial infarction (AMI), less than 20 % of patients reach the hospital within an optimal time window. About 75 % of pre-hospital delay time is caused by deficits in the patients' subjective decision making. To date, little is known about the course of threat appraisal during AMI. We aim to show here that health psychology related concepts offer an attractive conceptual frame to understand paradoxical reactions of AMI patients during this life threatening phase of their life. Only if patients overcome a complex network of barriers in perception and interpretation of symptoms, AMI symptoms will become effective as cues-to-action. Perception of symptoms may be compromised by a wide range of nociceptive stimuli originating from the heart. Symptom vagueness and a mismatch between expected and perceived symptoms may limit interpretation of the threat, yet active misattributing coping strategies may be even more present. Negative outcome expectancies and an impaired perceived self-efficacy, predominately in subjects with co-morbid negative affectivity are likely to contribute to delay

Perceived usage potential of fast-charging locations

Fast-charging infrastructure with charging durance of 20 to 30 minutes can help minimizing current perceived limitations of electric vehicles, especially considering the unbalanced and incomprehensive distribution of charging options combined with a long perceived charging durance. Positioned on optimal location from user's perspective, the technology is assumed to help increasing the usage of an EV. Current and potential EV users were interviewed in two different surveys about optimal fast-charging locations depending on travel purposes and relevant location criteria. The obtained results show that customers prefer to charge rather at origins and destinations than during the trip. For longer distances, charging locations on axes with attractive points of interest are also considered as optimal. From the business model point of view, fast-charging stations at destinations are controversial. The expensive infrastructure and the therefore needed large number of charging sessions are in conflict with the comparatively time consuming stay