The Gut Microbiota Composition in Dichorionic Triplet Sets Suggests a Role for Host Genetic Factors

peer-reviewedMonozygotic and dizygotic twin studies investigating the relative roles of host genetics and environmental factors in shaping gut microbiota composition have produced conflicting results. In this study, we investigated the gut microbiota composition of a healthy dichorionic triplet set. The dichorionic triplet set contained a pair of monozygotic twins and a fraternal sibling, with similar pre- and post-natal environmental conditions including feeding regime. V4 16S rRNA and rpoB amplicon pyrosequencing was employed to investigate microbiota composition, and the species and strain diversity of the culturable bifidobacterial population was also examined. At month 1, the monozygotic pair shared a similar microbiota distinct to the fraternal sibling. By month 12 however, the profile was more uniform between the three infants. Principal coordinate analysis (PCoA) of the microbiota composition revealed strong clustering of the monozygotic pair at month 1 and a separation of the fraternal infant. At months 2 and 3 the phylogenetic distance between the monozygotic pair and the fraternal sibling has greatly reduced and by month 12 the monozygotic pair no longer clustered separately from the fraternal infant. Pulse field gel electrophoresis (PFGE) analysis of the bifidobacterial population revealed a lack of strain diversity, with identical strains identified in all three infants at month 1 and 12. The microbiota of two antibiotic-treated dichorionic triplet sets was also investigated. Not surprisingly, in both triplet sets early life antibiotic administration appeared to be a major determinant of microbiota composition at month 1, irrespective of zygosity. By month 12, early antibiotic administration appeared to no longer exert such a strong influence on gut microbiota composition. We hypothesize that initially host genetics play a significant role in the composition of an individual’s gut microbiota, unless an antibiotic intervention is given, but by month 12 environmental factors are the major determinant.This study was performed as part of the INFANTMET project (10/RD/Infantmet/MFRC/705) and was funded by the Government of Ireland's Department of Agriculture Fisheries and in part by Alimentary Pharmabiotic Centre. KM is a Teagasc Walsh Fellow. CS, RPR and PWOT are members of The Alimentary Pharmabiotic Centre, which is a Centre for Science and Technology (CSET) funded by the Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan (Grant no. 02/CE/B124 and 07/CE/B1368)

The Composition of Human Milk and Infant Faecal Microbiota Over the First Three Months of Life: A Pilot Study

peer-reviewedHuman milk contains a diverse array of bioactives and is also a source of bacteria for the developing infant gut. The aim of this study was to characterize the bacterial communities in human milk and infant faeces over the first 3 months of life, in 10 mother-infant pairs. The presence of viable Bifidobacterium and Lactobacillus in human milk was also evaluated. MiSeq sequencing revealed a large diversity of the human milk microbiota, identifying over 207 bacterial genera in milk samples. The phyla Proteobacteria and Firmicutes and the genera Pseudomonas, Staphylococcus and Streptococcus were the predominant bacterial groups. A core of 12 genera represented 81% of the microbiota relative abundance in milk samples at week 1, 3 and 6, decreasing to 73% at week 12. Genera shared between infant faeces and human milk samples accounted for 70–88% of the total relative abundance in infant faecal samples, supporting the hypothesis of vertical transfer of bacteria from milk to the infant gut. In addition, identical strains of Bifidobacterium breve and Lactobacillus plantarum were isolated from the milk and faeces of one mother-infant pair. Vertical transfer of bacteria via breastfeeding may contribute to the initial establishment of the microbiota in the developing infant intestine

The infectivity and behaviour of exsheathed and ensheathed Heterorhabditis megidis infective juveniles

The consequencesof sheath loss on infectivityand behaviourof infective juveniles (IJ) were investigatedin Heterorhabditis megidis. Ensheathed IJ were more infective, killing 32% of wax moth larvae, compared to 18% killed by exsheathed IJ. The percentage of time engaged in seven behavioural activitieswas recordedfor individuallystored IJ but no differenceswere found between exsheathed and ensheathed IJ. Immobility was the most common behavioural category exhibited by both exsheathed and ensheathed IJ, occupying one third of the observation time. Storage conditions affected the rate of exsheathment; 40% of IJ stored for 28 days in water in bulk (50 in 8 ml) exsheathed compared to only 23% of those stored individually (1 in 2 ml)

A dyad of lymphoblastic lysosomal cysteine proteases degrades the antileukemic drug L-asparaginase

l-Asparaginase is a key therapeutic agent for treatment of childhood acute lymphoblastic leukemia (ALL). There is wide individual variation in pharmacokinetics, and little is known about its metabolism. The mechanisms of therapeutic failure with l-asparaginase remain speculative. Here, we now report that 2 lysosomal cysteine proteases present in lymphoblasts are able to degrade l-asparaginase. Cathepsin B (CTSB), which is produced constitutively by normal and leukemic cells, degraded asparaginase produced by Escherichia coli (ASNase) and Erwinia chrysanthemi. Asparaginyl endopeptidase (AEP), which is overexpressed predominantly in high-risk subsets of ALL, specifically degraded ASNase. AEP thereby destroys ASNase activity and may also potentiate antigen processing, leading to allergic reactions. Using AEP-mediated cleavage sequences, we modeled the effects of the protease on ASNase and created a number of recombinant ASNase products. The N24 residue on the flexible active loop was identified as the primary AEP cleavage site. Sole modification at this site rendered ASNase resistant to AEP cleavage and suggested a key role for the flexible active loop in determining ASNase activity. We therefore propose what we believe to be a novel mechanism of drug resistance to ASNase. Our results may help to identify alternative therapeutic strategies with the potential of further improving outcome in childhood ALL

Associations among sedentary and active behaviours, body fat and appetite dysregulation: investigating the myth of physical inactivity and obesity

Background There is considerable disagreement about the association between free-living physical activity (PA) and sedentary behaviour and obesity. Moreover studies frequently do not include measures that could mediate between PA and adiposity. The present study used a validated instrument for continuous tracking of sedentary and active behaviours as part of habitual daily living, together with measures of energy expenditure, body composition and appetite dysregulation. This cross-sectional study tested the relationship between inactivity and obesity. Methods 71 participants (81.7% women) aged 37.4 years (±14) with a body mass index of 29.9 kg/m2 (±5.2) were continuously monitored for 6–7 days to track free-living PA (light 1.5–3 metabolic equivalents (METs), moderate 3–6 METs and vigorous >6 METs) and sedentary behaviour (<1.5 METs) with the SenseWear Armband. Additional measures included body composition, waist circumference, cardiovascular fitness, total and resting energy expenditure, and various health markers. Appetite control was assessed by validated eating behaviour questionnaires. Results Sedentary behaviour (11.06±1.72 h/day) was positively correlated with fat mass (r=0.50, p<0.001) and waist circumference (r=−0.65, p<0.001). Moderate-to-vigorous PA was negatively associated with fat mass (r=−0.72, p<0.001) and remained significantly correlated with adiposity after controlling for sedentary behaviour. Activity energy expenditure was positively associated with the level of PA and negatively associated with fat mass. Disinhibition and binge eating behaviours were positively associated with fat mass (r=0.58 and 0.47, respectively, p<0.001). Conclusions This study demonstrated clear associations among objective measures of PA (and sedentary behaviour), energy expenditure, adiposity and appetite control. The data indicate strong links between physical inactivity and obesity. This relationship is likely to be bidirectional

Clinical reappraisal of the Composite International Diagnostic Interview Screening Scales (CIDI‐SC) in the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS)

A clinical reappraisal study was carried out in conjunction with the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS) All‐Army Study (AAS) to evaluate concordance of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM‐IV) diagnoses based on the Composite International Diagnostic Interview Screening Scales (CIDI‐SC) and post‐traumatic stress disorder (PTSD) checklist (PCL) with diagnoses based on independent clinical reappraisal interviews (Structured Clinical Interview for DSM‐IV [SCID]). Diagnoses included: lifetime mania/hypomania, panic disorder, and intermittent explosive disorder; six‐month adult attention‐deficit/hyperactivity disorder; and 30‐day major depressive episode, generalized anxiety disorder, PTSD, and substance (alcohol or drug) use disorder (abuse or dependence). The sample ( n  = 460) was weighted for over‐sampling CIDI‐SC/PCL screened positives. Diagnostic thresholds were set to equalize false positives and false negatives. Good individual‐level concordance was found between CIDI‐SC/PCL and SCID diagnoses at these thresholds (area under curve [AUC] = 0.69–0.79). AUC was considerably higher for continuous than dichotomous screening scale scores (AUC = 0.80–0.90), arguing for substantive analyses using not only dichotomous case designations but also continuous measures of predicted probabilities of clinical diagnoses. Copyright © 2013 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102145/1/mpr1398.pd

SMART Binary: Sample Size Calculation for Comparing Adaptive Interventions in SMART studies with Longitudinal Binary Outcomes

Sequential Multiple-Assignment Randomized Trials (SMARTs) play an increasingly important role in psychological and behavioral health research. This experimental approach enables researchers to answer scientific questions about how to sequence and match interventions to the unique, changing needs of individuals. A variety of sample size planning resources for SMART studies have been developed in recent years; these enable researchers to plan SMARTs for addressing different types of scientific questions. However, relatively limited attention has been given to planning SMARTs with binary (dichotomous) outcomes, which often require higher sample sizes relative to continuous outcomes. Existing resources for estimating sample size requirements for SMARTs with binary outcomes do not consider the potential to improve power by including a baseline measurement and/or multiple repeated outcome measurements. The current paper addresses this issue by providing sample size simulation code and approximate formulas for two-wave repeated measures binary outcomes (i.e., two measurement times for the outcome variable, before and after receiving the intervention). The simulation results agree well with the formulas. We also discuss how to use simulations to calculate power for studies with more than two outcome measurement occasions. The results show that having at least one repeated measurement of the outcome can substantially improve power under certain conditions.Comment: 73 pages, 2 figures, submitted to Multivariate Behavioral Researc

Combined magnetic and chemical patterning for neural architectures

In vitro investigation of neural architectures requires cell positioning. For that purpose, micro-magnets have been developed on silicon substrates and combined with chemical patterning to attract cells to adhesive sites and keep them there during incubation. We have shown that the use of micro-magnets allows to achieve a high filling factor (~90%) of defined adhesive sites in neural networks and prevents migration of cells during growth. This approach has great potential for neural interfacing by providing accurate and time-stable coupling with integrated nanodevices