1,552 research outputs found

    Sauna Exposure Immediately Prior to Short-term Heat Acclimation Accelerates Phenotypic Adaptation in Females

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    Objectives: Investigate whether a sauna exposure prior to short-term heat acclimation (HA) accelerates phenotypic adaptation in females. Design: Randomised, repeated measures, cross-over trial. Methods: Nine females performed two 5-d HA interventions (controlled hyperthermia Tre ≥ 38.5°C), separated by 7-wk, during the follicular phase of the menstrual cycle confirmed by plasma concentrations of 17-β estradiol and progesterone. Prior to each 90-min HA session participants sat for 20-min in either a temperate environment (20°C, 40% RH; HAtemp) wearing shorts and sports bra or a hot environment (50°C, 30% RH) wearing a sauna suit to replicate sauna conditions (HAsauna). Participants performed a running heat tolerance test (RHTT) 24-hr pre and 24-hr post HA. Results: Mean heart rate (HR) (85±4 vs. 68±5 bpm, p≤0.001), sweat rate (0.4±0.2 vs. 0.0±0.0 L.hr-1, p≤0.001), and thermal sensation (6±0 vs. 5±1, p=0.050) were higher during the sauna compared to temperate exposure. Resting rectal temperature (Tre) (-0.28±0.16°C), peak Tre (-0.42±0.22°C), resting HR (-10±4 bpm), peak HR (-12±7 bpm), Tre at sweating onset (-0.29±0.17°C) (p≤0.001), thermal sensation (-0.5±0.5; p=0.002), and perceived exertion (-3±2; p≤0.001) reduced during the RHTT, following HAsauna; but not HAtemp. Plasma volume expansion was greater following HAsauna (HAsauna, 9±7%; HAtemp, 1±5%; p=0.013). Sweat rate (p≤0.001) increased and sweat NaCl (p=0.006) reduced during the RHTT following HAsauna and HAtemp. Conclusions: This novel strategy initiated HA with an attenuation of thermoregulatory, cardiovascular, and perceptual strain in females due to a measurably greater strain in the sauna compared to temperate exposure when adopted prior to STHA

    A comparison of males and females' temporal patterning to short-and long-term heat acclimation

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    The current study assessed sex differences in thermoregulatory and physiological adaptation to short-term (STHA) and long-term heat acclimation (LTHA). Sixteen (eight males; eight females) participants performed three running heat tolerance test

    Performance evaluation of cetacean species distribution models developed using generalized additive models and boosted regression trees

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    Species distribution models (SDMs) are important management tools for highly mobile marine species because they provide spatially and temporally explicit information on animal distribution. Two prevalent modeling frameworks used to develop SDMs for marine species are generalized additive models (GAMs) and boosted regression trees (BRTs), but comparative studies have rarely been conducted; most rely on presence-only data; and few have explored how features such as species distribution characteristics affect model performance. Since the majority of marine species BRTs have been used to predict habitat suitability, we first compared BRTs to GAMs that used presence/absence as the response variable. We then compared results from these habitat suitability models to GAMs that predict species density (animals per km2) because density models built with a subset of the data used here have previously received extensive validation. We compared both the explanatory power (i.e., model goodness of fit) and predictive power (i.e., performance on a novel dataset) of the GAMs and BRTs for a taxonomically diverse suite of cetacean species using a robust set of systematic survey data (1991–2014) within the California Current Ecosystem. Both BRTs and GAMs were successful at describing overall distribution patterns throughout the study area for the majority of species considered, but when predicting on novel data, the density GAMs exhibited substantially greater predictive power than both the presence/absence GAMs and BRTs, likely due to both the different response variables and fitting algorithms. Our results provide an improved understanding of some of the strengths and limitations of models developed using these two methods. These results can be used by modelers developing SDMs and resource managers tasked with the spatial management of marine species to determine the best modeling technique for their question of interest

    A Crucial Role for Kupffer Cell-Derived Galectin-9 in Regulation of T Cell Immunity in Hepatitis C Infection

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    Approximately 200 million people throughout the world are infected with hepatitis C virus (HCV). One of the most striking features of HCV infection is its high propensity to establish persistence (∼70–80%) and progressive liver injury. Galectins are evolutionarily conserved glycan-binding proteins with diverse roles in innate and adaptive immune responses. Here, we demonstrate that galectin-9, the natural ligand for the T cell immunoglobulin domain and mucin domain protein 3 (Tim-3), circulates at very high levels in the serum and its hepatic expression (particularly on Kupffer cells) is significantly increased in patients with chronic HCV as compared to normal controls. Galectin-9 production from monocytes and macrophages is induced by IFN-γ, which has been shown to be elevated in chronic HCV infection. In turn, galectin-9 induces pro-inflammatory cytokines in liver-derived and peripheral mononuclear cells; galectin-9 also induces anti-inflammatory cytokines from peripheral but not hepatic mononuclear cells. Galectin-9 results in expansion of CD4+CD25+FoxP3+CD127low regulatory T cells, contraction of CD4+ effector T cells, and apoptosis of HCV-specific CTLs. In conclusion, galectin-9 production by Kupffer cells links the innate and adaptive immune response, providing a potential novel immunotherapeutic target in this common viral infection

    New ophthalmosaurid ichthyosaurs from the European lower cretaceous demonstrate extensive ichthyosaur survival across the Jurassic–Cretaceous boundary

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    Background Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic–Cretaceous boundary (JCB), and one (resulting in total extinction) at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian–Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood. Methodology/Principal Findings Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian–Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian–Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian–Barremian interval and the JCB records one of the highest survival rates of the interval. Conclusions/Significance There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle Jurassic to their total extinction at the beginning of the Late Cretaceous

    Engaging End-users to Inform the Development of the Global Standard for the Identification of Key Biodiversity Areas

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    We report results from an end-user engagement process, convened by the International Union for Conservation of Nature (IUCN), which informed the development of the Global Standard for the Identification of Key Biodiversity Areas. Key Biodiversity Areas are sites contributing significantly to the global persistence of biodiversity. We used a mixed methods approach involving interviews and an online questionnaire with end-users to determine their needs and concerns in relation to the Key Biodiversity Area approach. We found a remarkable level of convergence in end-user opinion on 12 important topics. Four topics resulted in a divergence in end-user opinion requiring further dialogue and consideration, including: (i) the value of a global standard compared to various national approaches; (ii) the prioritisation of Key Biodiversity Areas over other areas; (iii) whether Key Biodiversity Area data should be made freely available; and (iv) whether or not development activities should be permitted in Key Biodiversity Areas. Our results informed the development of the Global Standard for the Identification of Key Biodiversity Areas and a new governance structure, the Key Biodiversity Area Consultative Forum, which provides a mechanism for ongoing dialogue with end-users. We conclude by sharing five good practice recommendations for future end-user engagement processes
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