303 research outputs found

    Blueprint for an intestinal villus: Species‐specific assembly required

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144650/1/wdev317_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144650/2/wdev317.pd

    Effects of treatment on IgE responses against parasite allergen-like proteins and immunit to reinfection in childhood schistosome and hookworm coinfections

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    Naturally occurring human immunity to both schistosomiasis and hookworm infection has been associated with IgE responses against parasite allergen-like proteins. Since the two helminths frequently coinfect the same individuals, there is growing advocacy for their concurrent treatment. However, both helminths are known to exert strong immunomodulatory effects; therefore, coinfected individuals could have immune responses different from those characteristically seen in monoinfected individuals. In this study, we measured changes in IgE, IgG1, and IgG4 responses to schistosome and hookworm antigens, including the allergen-like proteins Schistosoma mansoni tegumental-allergen-like 1 protein (SmTAL1), SmTAL2, and Necator americanus Ancylostoma-secreted protein-2 (Na-ASP-2), following concurrent treatment of schoolchildren coinfected withSchistosoma mansoni and hookworm. Antibody responses to schistosome egg (soluble egg antigen and SmTAL2) or somatic adult hookworm (AHW) antigens either decreased after treatment or were unchanged, whereas those to schistosome worm antigens (soluble worm antigen and SmTAL1) increased. The observed different effects of treatment likely reflect the different modes of drug action and sites of infection for these two helminths. Importantly, there was no evidence that the simultaneous treatment of coinfected children with praziquantel and albendazole affected schistosome- and hookworm-specific humoral responses differently from those characteristic of populations in which only one organism is endemic; schistosome- and hookworm-specific responses were not associated, and there was no evidence for cross-regulation. Posttreatment increases in the levels of IgE to schistosome worm antigens were associated with lower Schistosoma mansoni reinfection intensity, while no associations between humoral responses to AHW antigen and protection from hookworm reinfection were observed in this sample of school-aged children

    Laboratory predictors of uphill cycling performance in trained cyclists

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    This study aimed to assess the relationship between an uphill time-trial (TT) performance and both aerobic and anaerobic parameters obtained from laboratory tests. Fifteen cyclists performed a Wingate anaerobic test, a graded exercise test (GXT) and a field-based 20-min TT with 2.7% mean gradient. After a 5-week non-supervised training period, 10 of them performed a second TT for analysis of pacing reproducibility. Stepwise multiple regressions demonstrated that 91% of TT mean power output variation (W kg-1) could be explained by peak oxygen uptake (ml kg-1.min-1) and the respiratory compensation point (W kg-1), with standardised beta coefficients of 0.64 and 0.39, respectively. The agreement between mean power output and power at respiratory compensation point showed a bias ± random error of 16.2 ± 51.8 W or 5.7 ± 19.7%. One-way repeated-measures analysis of variance revealed a significant effect of the time interval (123.1 ± 8.7; 97.8 ± 1.2 and 94.0 ± 7.2% of mean power output, for epochs 0-2, 2-18 and 18-20 min, respectively; P < 0.001), characterising a positive pacing profile. This study indicates that an uphill, 20-min TT-type performance is correlated to aerobic physiological GXT variables and that cyclists adopt reproducible pacing strategies when they are tested 5 weeks apart (coefficients of variation of 6.3; 1 and 4%, for 0-2, 2-18 and 18-20 min, respectively)

    Using the past to constrain the future: how the palaeorecord can improve estimates of global warming

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    Climate sensitivity is defined as the change in global mean equilibrium temperature after a doubling of atmospheric CO2 concentration and provides a simple measure of global warming. An early estimate of climate sensitivity, 1.5-4.5{\deg}C, has changed little subsequently, including the latest assessment by the Intergovernmental Panel on Climate Change. The persistence of such large uncertainties in this simple measure casts doubt on our understanding of the mechanisms of climate change and our ability to predict the response of the climate system to future perturbations. This has motivated continued attempts to constrain the range with climate data, alone or in conjunction with models. The majority of studies use data from the instrumental period (post-1850) but recent work has made use of information about the large climate changes experienced in the geological past. In this review, we first outline approaches that estimate climate sensitivity using instrumental climate observations and then summarise attempts to use the record of climate change on geological timescales. We examine the limitations of these studies and suggest ways in which the power of the palaeoclimate record could be better used to reduce uncertainties in our predictions of climate sensitivity.Comment: The final, definitive version of this paper has been published in Progress in Physical Geography, 31(5), 2007 by SAGE Publications Ltd, All rights reserved. \c{opyright} 2007 Edwards, Crucifix and Harriso

    Gene evolution of epoxide hydrolases and recommended nomenclature

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    We have analyzed amino acid sequence relationships among soluble and microsomal epoxide hydrolases, haloacid dehalogenases, and a haloalkane dehalogenase. The amino-terminal residues (1-229) of mammalian soluble epoxide hydrolase are homologous to a haloacid dehalogenase. The carboxy-terminal residues (230-554) of mammalian soluble epoxide hydrolase are homologous to haloalkane dehalogenase, to plant soluble epoxide hydrolase, and to microsomal epoxide hydrolase. The shared identity between the haloacid and haloalkane dehalogenases does not indicate relatedness between these two types of dehalogenases. The amino-terminal and carboxy-terminal homologies of mammalian soluble epoxide hydrolase to the respective dehalogenases suggests that this epoxide hydrolase, but not the soluble epoxide hydrolase of plant or the microsomal epoxide hydrolase, derives from a gene fusion. The homology of microsomal to soluble epoxide hydrolase suggests they derive from a gene duplication, probably of an ancestral bacterial (epoxide) hydrolase gene. Based on homology to haloalkane dehalogenase, the catalytic residues for the soluble and microsomal epoxide hydrolases are predicted. A nomenclature system based on divergent molecular evolution is proposed for these epoxide hydrolases
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