A comparison of survey and focal follow methods for estimating individual activity budgets of cetaceans

Activity budget data are essential for determining behavioral responses to physiological and ecological variables. Yet, few studies are available to investigate the robustness, accuracy, and biases of the methods used to estimate activity budgets for cetaceans. In this study, we compare activity budgets of 55 adult female bottlenose dolphins in Shark Bay, Australia derived from two methods: surveys (n = 6,903) and focal follows (n = 1,185, totaling 2,721 h of observation). Activity budgets estimated from survey data differed in all behavioral states compared to focal follow data. However, when controlling for temporal autocorrelation, only time spent socializing and time spent traveling remained disparate between the methods. To control for biases associated with assigning group‐level behavior to individuals, we also compared survey and focal follow activity budgets for lone females. Here we found differences between methods in time spent foraging and traveling regardless of whether we controlled for temporal autocorrelation, which suggests detection biases likely play a role in explaining differences in activity budget estimates between the two methodologies. Our results suggest that surveys are less representative of individual‐level activity budgets, and thus, when individual‐level knowledge about behavior is needed, focal follows are preferred.     

Genome-wide assessment for genetic variants associated with ventricular dysfunction after primary coronary artery bypass graft surgery

Background

Postoperative ventricular dysfunction (VnD) occurs in 9–20% of coronary artery bypass graft (CABG) surgical patients and is associated with increased postoperative morbidity and mortality. Understanding genetic causes of postoperative VnD should enhance patient risk stratification and improve treatment and prevention strategies. We aimed to determine if genetic variants associate with occurrence of in-hospital VnD after CABG surgery.

Methods

A genome-wide association study identified single nucleotide polymorphisms (SNPs) associated with postoperative VnD in male subjects of European ancestry undergoing isolated primary CABG surgery with cardiopulmonary bypass. VnD was defined as the need for ≥2 inotropes or mechanical ventricular support after CABG surgery. Validated SNPs were assessed further in two replication CABG cohorts and meta-analysis was performed.

Results

Over 100 SNPs were associated with VnD (P<10⁻⁴), with one SNP (rs17691914) encoded at 3p22.3 reaching genome-wide significance (P_{additive model} = 2.14×10⁻⁸). Meta-analysis of validation and replication study data for 17 SNPs identified three SNPs associated with increased risk for developing postoperative VnD after adjusting for clinical risk factors. These SNPs are located at 3p22.3 (rs17691914, OR_{additive model} = 2.01, P = 0.0002), 3p14.2 (rs17061085, OR_{additive model} = 1.70, P = 0.0001) and 11q23.2 (rs12279572, OR_{recessive model} = 2.19, P = 0.001).

Conclusions

No SNPs were consistently associated with strong risk (OR_{additive model}>2.1) of developing in-hospital VnD after CABG surgery. However, three genetic loci identified by meta-analysis were more modestly associated with development of postoperative VnD. Studies of larger cohorts to assess these loci as well as to define other genetic mechanisms and related biology that link genetic variants to postoperative ventricular dysfunction are warranted.     

Epigenetic changes with dietary soy in cynomolgus monkeys

Nutritional interventions are important alternatives for reducing the prevalence of many chronic diseases. Soy is a good source of protein that contains isoflavones, including genistein and daidzein, and may alter the risk of obesity, Type 2 diabetes, osteoporosis, cardiovascular disease, and reproductive cancers. We have shown previously in nonhuman primates that soy protein containing isoflavones leads to improved body weight, insulin sensitivity, lipid profiles, and atherosclerosis compared to protein without soy isoflavones (casein), and does not increase the risk of cancer. Since genistein has been shown to alter DNA methylation, we compared the methylation profiles of cynomolgus monkeys, from multiple tissues, eating two high-fat, typical American diets (TAD) with similar macronutrient contents, with or without soy protein. DNA methylation status was successfully determined for 80.6% of the probes in at least one tissue using Illumina's HumanMethylation27 BeadChip. Overall methylation increased in liver and muscle tissue when monkeys switched from the TAD-soy to the TAD-casein diets. Genes involved in epigenetic processes, specifically homeobox genes (HOXA5, HOXA11, and HOXB1), and ABCG5 were among those that changed between diets. These data support the use of the HumanMethylation27 BeadChip in cynomolgus monkeys and identify epigenetic changes associated with dietary interventions with soy protein that may potentially affect the etiology of complex diseases.     

European society of intensive care medicine study of therapeutic hypothermia (32-35°C) for intracranial pressure reduction after traumatic brain injury (the Eurotherm3235Trial)

Background

Severe malaria remains a major cause of global morbidity and mortality. Despite the use of potent anti-parasitic agents, the mortality rate in severe malaria remains high. Adjunctive therapies that target the underlying pathophysiology of severe malaria may further reduce morbidity and mortality. Endothelial activation plays a central role in the pathogenesis of severe malaria, of which angiopoietin-2 (Ang-2) has recently been shown to function as a key regulator. Nitric oxide (NO) is a major inhibitor of Ang-2 release from endothelium and has been shown to decrease endothelial inflammation and reduce the adhesion of parasitized erythrocytes. Low-flow inhaled nitric oxide (iNO) gas is a US FDA-approved treatment for hypoxic respiratory failure in neonates.

Methods/Design

This prospective, parallel arm, randomized, placebo-controlled, blinded clinical trial compares adjunctive continuous inhaled nitric oxide at 80 ppm to placebo (both arms receiving standard anti-malarial therapy), among Ugandan children aged 1-10 years of age with severe malaria. The primary endpoint is the longitudinal change in Ang-2, an objective and quantitative biomarker of malaria severity, which will be analysed using a mixed-effects linear model. Secondary endpoints include mortality, recovery time, parasite clearance and neurocognitive sequelae.

Discussion

Noteworthy aspects of this trial design include its efficient sample size supported by a computer simulation study to evaluate statistical power, meticulous attention to complex ethical issues in a cross-cultural setting, and innovative strategies for safety monitoring and blinding to treatment allocation in a resource-constrained setting in sub-Saharan Africa.

Trial Registration

ClinicalTrials.gov Identifier: NCT01255215     

Effect of smoke-free legislation on adult smoking behaviour in England in the 18 months following implementation

Background

Comprehensive smoke-free legislation covering all enclosed public places and workplaces was implemented in England on 1 July 2007. This study examines the impact of this legislation on smoking prevalence, number of cigarettes smoked and location of smoking, controlling for secular trends through the end of 2008.

Method and Findings

Repeat cross sectional survey using nationally representative data from the Health Survey for England (HSE). In total there are 54,333 respondents from 2003–2008. Logit and linear regression models were used to examine the effect of the legislation on smoking prevalence and the number of cigarettes smoked daily among continuing smokers which took the underlying trend into account. Our finding suggest that smoking prevalence (current smoker) decreased from 25% in 2003 to 21% in 2008 (AOR = 0.96 per year, 95% CI = 0.95–0.98, P<0.01) and the mean number of cigarettes consumed daily by smokers decreased from 14.1 in 2003 to 13.1 in 2008 (coefficient for time trend = −0.28±0.06 SE cig/day per year, P<0.01). After adjusting for these trends the introduction of smoke-free legislation was not associated with additional reductions in smoking prevalence (AOR = 1.02, 95% CI = 0.94–1.11, P = 0.596) or daily cigarette use in smokers (0.42±0.28 SE; P = 0.142). The percentage of respondents reporting smoking ‘at work’ and ‘inside pubs or bars’ decreased significantly from 14% to 2% (p<0.001) and from 34% to 2% (p<0.001), respectively, after the legislation. The percentage reporting smoking ‘inside restaurants, cafes, or canteens’ decreased significantly from 9% to 1% (p<0.001) and ‘inside their home’ decreased significantly from 65% to 55% (p<0.01).

Conclusion

There is widespread compliance with the smoke-free legislation in England, which has led to large drops in indoor smoking in all venues, including at home. Declines in smoking prevalence and consumption continued along existing trends; they did not accelerate during the 18 months immediately following implementation.     

Short-term learning and the searching accuracy of egg-laying butterflies

Searching constraints influence foraging patterns in three species of Colias butterflies. The activity of egg-laying females is partitioned into periods of searching for oviposition plants and periods of visiting flowers for nectar. Eggs are laid most frequently upon legume host-plants, although females frequently land upon non-legume species, particularly those bearing a superficial resemblance to suitable hosts. The average frequency of these landing ‘errors’ decreases over the course of an egglaying flight, implying thet females learn to identify host-plants more accurately on the basis of recent experience. Landing accuracy is low after periods of nectar-feeding, which suggests a trade-off between the two searching modalities. Within oviposition sequences, females that visit a narrow range of host specis make fewer landing errors than females visiting a broader host-plant set. Two interpretations of these data are presented: (1) that partitioning searching time into discrete modes may enhance overaccuracy in invertebrates, as has been demonstrated previously for vertebrates. Searching dynamics of this type may explain some discrepancies between the predictions made by simple optimal diet models and the occurrence of ‘switching’ behaviours in foragers.     

Statistical convenience vs biological insight: consequences of data transformation for the analysis of fitness variation in heterogeneous environments

In plants, more favourable environmental conditions can lead to dramatic increases in both mean fitness and variance in fitness. This results in data that violate the equality-of-variance assumption of anova, a problem that most empiricists would address by log-transforming fitness values. Using heuristic data sets and simple simulations, we show that anova on log-transformed fitness consistently fails to match the outcome of selection in a heterogeneous environment or its sensitivity to environmental frequency. Only anova based on relative fitness within environments accurately predicts the sensitivity of genotype selection to the frequency of alternative environments. Parallel analyses of variance based on absolute fitness and relative fitness can bracket the expected success of alternative genotypes under hard and soft selection, respectively. For example, for Sinapis arvensis growing in full sun and partial shade treatments, families achieving high fitness in the best environment are favoured under hard selection, whereas soft selection favours different families that achieve consistently good performance across environments. Based on these findings, we recommend that log-transformation of fitness should no longer be standard practice in ecological genetics studies. Weighted anova is a preferable method for dealing with unequal variances, and investigators should also make greater use of techniques such as quantile regression or resampling to describe and evaluate fitness variation across heterogeneous environments.     

Ecological factors influencing tetraploid speciation in snow buttercups (Ranunculus Adoneus): niche differentiation and tetraploid establishment

Chromosome doubling plays an important role in generating new species of flowering plants. However, reproductive incompatibilities between newly formed tetraploid plants and their diploid progenitors are expected to create a significant barrier to the persistence and establishment of neopolyploid populations. Ecological differentiation can reduce this barrier via prezygotic isolation arising from spatial separation. Alternatively, superior viability or fecundity of neotetraploid plants might compensate for the reproductive cost of incompatible pollen from diploid neighbors. The performance of plants of both cytotypes can be assessed in their respective habitats through reciprocal transplants, although such experiments have not been used previously in the study of tetraploid speciation. We used a series of seed and seedling transplant experiments to assess ecological differentiation and competitive ability during early establishment phases for tetraploid and diploid forms of the snow buttercup (Ranunculus adoneus). At two sites, seeds from diploids and tetraploids had similar germination probabilities. Tetraploid snow buttercup seedlings had a significant growth advantage in a controlled environment chamber experiment. However, in the field diploid and tetraploid buttercup seedlings did not differ consistently in survival or growth, nor did the two cytotypes show reciprocal advantages in performance, as expected if ecological differentiation has occurred. At the seed and seedling stages, neither niche differentiation nor tetraploid competitive superiority appears sufficient to explain neotetraploid success in the presence of their diploid progenitors.     

The short apical membrane half-life of rescued {Delta}F508-cystic fibrosis transmembrane conductance regulator (CFTR) results from accelerated endocytosis of {Delta}F508-CFTR in polarized human airway epithelial cells

The most common mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene in individuals with cystic fibrosis, DeltaF508, causes retention of DeltaF508-CFTR in the endoplasmic reticulum and leads to the absence of CFTR Cl(-) channels in the apical plasma membrane. Rescue of DeltaF508-CFTR by reduced temperature or chemical means reveals that the DeltaF508 mutation reduces the half-life of DeltaF508-CFTR in the apical plasma membrane. Because DeltaF508-CFTR retains some Cl(-) channel activity, increased expression of DeltaF508-CFTR in the apical membrane could serve as a potential therapeutic approach for cystic fibrosis. However, little is known about the mechanisms responsible for the short apical membrane half-life of DeltaF508-CFTR in polarized human airway epithelial cells. Accordingly, the goal of this study was to determine the cellular defects in the trafficking of rescued DeltaF508-CFTR that lead to the decreased apical membrane half-life of DeltaF508-CFTR in polarized human airway epithelial cells. We report that in polarized human airway epithelial cells (CFBE41o-) the DeltaF508 mutation increased endocytosis of CFTR from the apical membrane without causing a global endocytic defect or affecting the endocytic recycling of CFTR in the Rab11a-specific apical recycling compartment.