The quantitative genetics of two life history trade-offs in the yellow dung fly in abundant and limited food environments

The trade-offs between body size and development time and between egg size and egg number (clutch size) are central to life history theory, but evidence for them, particularly in terms of genetic correlations, is equivocal. For the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae), we investigated variation in phenotypic and genetic variances and covariances, i.e. heritabilities and genetic correlations, of these life history traits (plus diapause) in benign and stressful larval field or adult laboratory food environments. We found both trade-offs to be weak, as evidenced by low phenotypic and genetic correlations, but stronger in the food limited environments. Broad sense heritabilities were generally significant for all traits considered, whereas the narrow sense heritabilities for egg and clutch size were nil. With regard to the question of how environmental stress affects heritabilities, we found a whole range of responses within one single species depending on the traits considered. All three possible patterns occurred, i.e. increased h2 due to increased VG or decreased $$V_{P^{\prime}}$$ decreased h2 due to increased $$V_{P^{\prime}}$$ and no change in h2 due to increased VG and VP. These can be explained by the particular ecological circumstances yellow dung flies face in their natural environment. Nevertheless, the majority of patterns was consistent with the idea that stressful conditions amplify phenotypic differences between genotypes. Such variable responses of traits even within one organism underscores the complexity of this issue and may well explain the multiple patterns found in various organism

Sperm survival in the female reproductive tract in the fly Scathophaga stercoraria (L.)

While sperm competition risk favours males transferring many sperm to secure fertilizations, females of a variety of species actively reduce sperm numbers reaching their reproductive tract, e.g. by extrusion or killing. Potential benefits of spermicide to females include nutritional gains, influence over sperm storage and paternity, and the elimination of sperm bearing somatic mutations that would lower zygote fitness.We investigated changes in sperm viability after in vivo and in vitro exposure to the female tract in the polyandrous fly, Scathophaga stercoraria. Sperm viability was significantly lower in the females' spermathecae immediately after mating than in the experimental males' testes. Males also varied significantly in the proportion of live sperm found in storage in vivo. However, the exact mechanism of sperm degradation remains to be clarified. In vitro exposure to extracts of the female reproductive tract, including female accessory glands, failed to significantly lower sperm viability compared to controls. These results are consistent either with postcopulatory sperm mortality in vivo depending entirely on the male (with individual differences in sperm viability, motility or longevity) or with postcopulatory sperm mortality being subtly affected by female effects which were not detected by the in vitro experimental conditions. Importantly, we found no evidence in support of the hypothesis that female accessory glands contribute to sexual conflict via spermicide. Therefore, female muscular control remains to date the only ascertained mechanism of female influence on sperm storage in this species

Nutrition support practices in critically ill head-injured patients: a global perspective

Background: Critical illness following head injury is associated with a hypermetabolic state but there are insufficient epidemiological data describing acute nutrition delivery to this group of patients. Furthermore, there is little information describing relationships between nutrition and clinical outcomes in this population. Methods: We undertook an analysis of observational data, collected prospectively as part of International Nutrition Surveys 2007-2013, and extracted data obtained from critically ill patients with head trauma. Our objective was to describe global nutrition support practices in the first 12 days of hospital admission after head trauma, and to explore relationships between energy and protein intake and clinical outcomes. Data are presented as mean (SD), median (IQR), or percentages. Results: Data for 1045 patients from 341 ICUs were analyzed. The age of patients was 44.5 (19.7) years, 78 % were male, and median ICU length of stay was 13.1 (IQR 7.9-21.6) days. Most patients (94 %) were enterally fed but received only 58 % of estimated energy and 53 % of estimated protein requirements. Patients from an ICU with a feeding protocol had greater energy and protein intakes (p <0.001, 0.002 respectively) and were more likely to survive (OR 0.65; 95 % CI 0.42-0.99; p = 0.043) than those without. Energy or protein intakes were not associated with mortality. However, a greater energy and protein deficit was associated with longer times until discharge alive from both ICU and hospital (all p <0.001). Conclusion: Nutritional deficits are commonplace in critically ill head-injured patients and these deficits are associated with a delay to discharge alive.Lee-anne S. Chapple, Marianne J. Chapman, Kylie Lange, Adam M. Deane and Daren K. Heylan

Gender differences in paediatric patients of the swiss inflammatory bowel disease cohort study.

PURPOSE: Gender differences in paediatric patients with inflammatory bowel disease (IBD) are frequently reported as a secondary outcome and the results are divergent. To assess gender differences by analysing data collected within the Swiss IBD cohort study database since 2008, related to children with IBD, using the Montreal classification for a systematic approach. METHODS: Data on gender, age, anthropometrics, disease location at diagnosis, disease behaviour, and therapy of 196 patients, 105 with Crohn's disease (CD) and 91 with ulcerative or indeterminate colitis (UC/IC) were retrieved and analysed. RESULTS: THE CRUDE GENDER RATIO (MALE : female) of patients with CD diagnosed at &lt;10 years of age was 2.57, the adjusted ratio was 2.42, and in patients with UC/IC it was 0.68 and 0.64 respectively. The non-adjusted gender ratio of patients diagnosed at ≥10 years was 1.58 for CD and 0.88 for UC/IC. Boys with UC/IC diagnosed &lt;10 years of age had a longer diagnostic delay, and in girls diagnosed with UC/IC &gt;10 years a more important use of azathioprine was observed. No other gender difference was found after analysis of age, disease location and behaviour at diagnosis, duration of disease, familial occurrence of IBD, prevalence of extra-intestinal manifestations, complications, and requirement for surgery. CONCLUSION: CD in children &lt;10 years affects predominantly boys with a sex ratio of 2.57; the impact of sex-hormones on the development of CD in pre-pubertal male patients should be investigated

Positron-molecule interactions: resonant attachment, annihilation, and bound states

This article presents an overview of current understanding of the interaction of low-energy positrons with molecules with emphasis on resonances, positron attachment and annihilation. Annihilation rates measured as a function of positron energy reveal the presence of vibrational Feshbach resonances (VFR) for many polyatomic molecules. These resonances lead to strong enhancement of the annihilation rates. They also provide evidence that positrons bind to many molecular species. A quantitative theory of VFR-mediated attachment to small molecules is presented. It is tested successfully for selected molecules (e.g., methyl halides and methanol) where all modes couple to the positron continuum. Combination and overtone resonances are observed and their role is elucidated. In larger molecules, annihilation rates from VFR far exceed those explicable on the basis of single-mode resonances. These enhancements increase rapidly with the number of vibrational degrees of freedom. While the details are as yet unclear, intramolecular vibrational energy redistribution to states that do not couple directly to the positron continuum appears to be responsible for these enhanced annihilation rates. Downshifts of the VFR from the vibrational mode energies have provided binding energies for thirty species. Their dependence upon molecular parameters and their relationship to positron-atom and positron-molecule binding energy calculations are discussed. Feshbach resonances and positron binding to molecules are compared with the analogous electron-molecule (negative ion) cases. The relationship of VFR-mediated annihilation to other phenomena such as Doppler-broadening of the gamma-ray annihilation spectra, annihilation of thermalized positrons in gases, and annihilation-induced fragmentation of molecules is discussed.Comment: 50 pages, 40 figure

Enhanced protein-energy provision via the enteral route in critically ill patients: a single center feasibility trial of the PEP uP protocol

INTRODUCTION: The purpose of this pilot study is to assess the feasibility, acceptability, and safety of a new feeding protocol designed to enhance the delivery of enteral nutrition (EN). METHODS: In a prospective before and after study, we evaluated a new protocol compared to our standard feeding protocol. Innovative elements of the new protocol included setting daily volume based goals instead of hourly rate targets, initiating motility agents and protein supplements on Day 1, liberalizing the gastric residual volume threshold, and the option to use trophic feeds. Bedside nurses filled out questionnaires to assess the acceptability of the new approach and we assessed patients' nutritional and clinical outcomes. RESULTS: We enrolled 20 mechanically ventilated patients who stayed in the Intensive Care Unit for more than three days in the before group and 30 such patients in the after group. On a scale where 1 = totally unacceptable and 10 = totally acceptable, 30 nurses rated the new protocol as 7.1 (range 1 to 10) and no incidents compromising patient safety were observed. In the before group, on average, patients received 58.8% of their energy and 61.2% of their protein requirements by EN compared to 67.9% and 73.6% in the after group (P = 0.33 and 0.13). When the subgroup of patients prescribed to receive full volume feeds in the after group were evaluated (n = 18), they received 83.2% and 89.4% of their energy and protein requirements by EN respectively (P = 0.02 for energy and 0.002 for protein compared to the before group). The rates of vomiting, regurgitation, aspiration, and pneumonia were similar between the two groups. CONCLUSIONS: This new feeding protocol seems to be safe and acceptable to critical care nurses. The adoption of this protocol may be associated with enhanced delivery of EN but further trials are warranted to evaluate its effect on nutritional and clinical endpoints. TRIAL REGISTRATION: ClinicalTrials.gov NCT0110234

A study of the perceived risks, benefits and barriers to the use of SDD in adult critical care units (the SuDDICU study)

Peer reviewedPublisher PD

Glutamine supplementation

Intravenous glutamine supplementation is standard care when parenteral nutrition is given for critical illness. There are data of a reduced mortality when glutamine supplementation is given. In addition, standard commercial products for parenteral nutrition do not contain any glutamine due to glutamine instability in aqueous solutions. For the majority of critical ill patients who are fed enterally, the available evidence is insufficient to recommend glutamine supplementation. Standard formulation of enteral nutrition contains some glutamine: 2-4 g/L. However, this dose is insufficient to normalize glutamine plasma concentration

The efficacy and safety of prokinetic agents in critically ill patients receiving enteral nutrition: a systematic review and meta-analysis of randomized trials.

BACKGROUND: Intolerance to enteral nutrition is common in critically ill adults, and may result in significant morbidity including ileus, abdominal distension, vomiting and potential aspiration events. Prokinetic agents are prescribed to improve gastric emptying. However, the efficacy and safety of these agents in critically ill patients is not well-defined. Therefore, we conducted a systematic review and meta-analysis to determine the efficacy and safety of prokinetic agents in critically ill patients. METHODS: We searched MEDLINE, EMBASE, and Cochrane Library from inception up to January 2016. Eligible studies included randomized controlled trials (RCTs) of critically ill adults assigned to receive a prokinetic agent or placebo, and that reported relevant clinical outcomes. Two independent reviewers screened potentially eligible articles, selected eligible studies, and abstracted pertinent data. We calculated pooled relative risk (RR) for dichotomous outcomes and mean difference for continuous outcomes, with the corresponding 95 % confidence interval (CI). We assessed risk of bias using Cochrane risk of bias tool, and the quality of evidence using grading of recommendations assessment, development, and evaluation (GRADE) methodology. RESULTS: Thirteen RCTs (enrolling 1341 patients) met our inclusion criteria. Prokinetic agents significantly reduced feeding intolerance (RR 0.73, 95 % CI 0.55, 0.97; P = 0.03; moderate certainty), which translated to 17.3 % (95 % CI 5, 26.8 %) absolute reduction in feeding intolerance. Prokinetics also reduced the risk of developing high gastric residual volumes (RR 0.69; 95 % CI 0.52, 0.91; P = 0.009; moderate quality) and increased the success of post-pyloric feeding tube placement (RR 1.60, 95 % CI 1.17, 2.21; P = 0.004; moderate quality). There was no significant improvement in the risk of vomiting, diarrhea, intensive care unit (ICU) length of stay or mortality. Prokinetic agents also did not significantly increase the rate of diarrhea. CONCLUSION: There is moderate-quality evidence that prokinetic agents reduce feeding intolerance in critically ill patients compared to placebo or no intervention. However, the impact on other clinical outcomes such as pneumonia, mortality, and ICU length of stay is unclear