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One of the justifiable criticisms of human genetic studies is the underrepresentation of participants from diverse populations. Lack of inclusion must be addressed at-scale to identify causal disease factors and understand the genetic causes of health disparities. We present genome-wide associations for 2068 traits from 635,969 participants in the Department of Veterans Affairs Million Veteran Program, a longitudinal study of diverse United States Veterans. Systematic analysis revealed 13,672 genomic risk loci; 1608 were only significant after including non-European populations. Fine-mapping identified causal variants at 6318 signals across 613 traits. One-third (n = 2069) were identified in participants from non-European populations. This reveals a broadly similar genetic architecture across populations, highlights genetic insights gained from underrepresented groups, and presents an extensive atlas of genetic associations.
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Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Locos de Características Quantitativas , Veteranos , Humanos , Masculino , Variação Genética , Estudos Longitudinais , Polimorfismo de Nucleotídeo Único , Estados Unidos , United States Department of Veterans Affairs , FemininoRESUMO
BACKGROUND: Traditional electrocardiography (ECG)-derived heart rate variability (HRV) and photoplethysmography (PPG)-derived "HRV" (termed PRV) have been reported interchangeably. Any potential dissociation between HRV and PRV could be due to the variability in pulse arrival time (PAT; time between heartbeat and peripheral pulse). OBJECTIVE: This study examined if PRV is equivalent to ECG-derived HRV and if PRV's innate error makes it a high-quality measurement separate from HRV. METHODS: ECG data from 1084 subjects were obtained from the PhysioNet Autonomic Aging dataset, and individual PAT dispersions for both the wrist (n = 42) and finger (n = 49) were derived from Mol et al. (Exp Gerontol. 2020; 135: 110938). A Bayesian simulation was constructed whereby the individual arrival times of the PPG wave were calculated by placing a Gaussian prior on the individual QRS-wave timings of each ECG series. The standard deviation (σ) of the prior corresponds to the PAT dispersion from Mol et al. This was simulated 10,000 times for each PAT σ. The root mean square of successive differences (RMSSD) and standard deviation of N-N intervals (SDNN) were calculated for both HRV and PRV. The Region of Practical Equivalence bounds (ROPE) were set a priori at ± 0.2% of true HRV. The highest density interval (HDI) width, encompassing 95% of the posterior distribution, was calculated for each PAT σ. RESULTS: The lowest PAT σ (2.0 SD) corresponded to 88.4% within ROPE for SDNN and 21.4% for RMSSD. As the σ of PAT increases, the equivalence of PRV and HRV decreases for both SDNN and RMSSD. The HDI interval width increases with increasing PAT σ, with the HDI width increasing at a higher rate for RMSSD than SDNN. CONCLUSIONS: For individuals with greater PAT variability, PRV is not a surrogate for HRV. When considering PRV as a unique biometric measure, SDNN may have more favorable measurement properties than RMSSD, though both exhibit a non-uniform measurement error.
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Blood volume shifts during postural adjustment lead to irregular distension of the internal jugular vein (IJV). In microgravity, distension may contribute to flow stasis and thromboembolism, though the regional implications and associated risk remain unexplored. We characterized regional differences in IJV volume distension and flow complexity during progressive head-down tilt (HDT) (0°, -6°, -15°, -30°) using conventional ultrasound and vector flow imaging. We also evaluated low-pressure thigh cuffs (40 mmHg) as a fluid shifting countermeasure during -6° HDT. Total IJV volume expanded 139 ± 95% from supine position (4.6 ± 2.7 mL) to -30° HDT (10.3 ± 5.0 mL). Blood flow profiles had greater vector uniformity at the cranial IJV region (P < 0.01) and became more dispersed with increasing tilt (P < 0.01). Qualitatively, flow was more uniform throughout the IJV during its early flow cycle phase and more disorganized during late flow phase. This disorganized flow was accentuated closer to the vessel wall, near the caudal region, and during greater HDT. Low-pressure thigh cuffs during -6° HDT decreased IJV volume at the cranial region (-12 ± 15%; P < 0.01) but not the caudal region (P = 0.20), although flow uniformity was unchanged (both regions, P > 0.25). We describe a distensible IJV accommodating large volume shifts along its length. Prominent flow dispersion was primarily found at the caudal region, suggesting multidirectional blood flow. Thigh cuffs appear effective for decreasing IJV volume but effects on flow complexity are minor. Flow complexity along the vessel length is likely related to IJV distension during chronic volume shifting and may be a precipitating factor for flow stasis and future thromboembolism risk.NEW & NOTEWORTHY The internal jugular vein (IJV) facilitates cerebral outflow and is sensitive to volume shifts. Concerns about IJV expansion and fluid flow behavior in astronauts have surfaced following thromboembolism reports. Our study explored regional volume distension and blood flow complexity in the IJV during progressive volume shifting. We observed stepwise volume distension and increasing flow dispersion with head-down tilting across all regions. Flow dispersion may pose a risk of future thromboembolism during prolonged volume shifts.
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Decúbito Inclinado com Rebaixamento da Cabeça , Veias Jugulares , Humanos , Veias Jugulares/fisiologia , Veias Jugulares/diagnóstico por imagem , Masculino , Decúbito Inclinado com Rebaixamento da Cabeça/fisiologia , Adulto , Feminino , Volume Sanguíneo/fisiologia , Adulto Jovem , Fluxo Sanguíneo Regional/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Ultrassonografia/métodosRESUMO
There is a rich literature highlighting that pathogens are generally better adapted to infect local than novel hosts, and a separate seemingly contradictory literature indicating that novel pathogens pose the greatest threat to biodiversity and public health. Here, using Batrachochytrium dendrobatidis, the fungus associated with worldwide amphibian declines, we test the hypothesis that there is enough variance in "novel" (quantified by geographic and phylogenetic distance) host-pathogen outcomes to pose substantial risk of pathogen introductions despite local adaptation being common. Our continental-scale common garden experiment and global-scale meta-analysis demonstrate that local amphibian-fungal interactions result in higher pathogen prevalence, pathogen growth, and host mortality, but novel interactions led to variable consequences with especially virulent host-pathogen combinations still occurring. Thus, while most pathogen introductions are benign, enough variance exists in novel host-pathogen outcomes that moving organisms around the planet greatly increases the chance of pathogen introductions causing profound harm.
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Batrachochytrium , Interações Hospedeiro-Patógeno , Animais , Batrachochytrium/genética , Batrachochytrium/fisiologia , Anuros/microbiologia , Anfíbios/microbiologia , Micoses/veterinária , Micoses/microbiologia , Adaptação Fisiológica , FilogeniaRESUMO
Anthropogenic change is contributing to the rise in emerging infectious diseases, which are significantly correlated with socioeconomic, environmental and ecological factors1. Studies have shown that infectious disease risk is modified by changes to biodiversity2-6, climate change7-11, chemical pollution12-14, landscape transformations15-20 and species introductions21. However, it remains unclear which global change drivers most increase disease and under what contexts. Here we amassed a dataset from the literature that contains 2,938 observations of infectious disease responses to global change drivers across 1,497 host-parasite combinations, including plant, animal and human hosts. We found that biodiversity loss, chemical pollution, climate change and introduced species are associated with increases in disease-related end points or harm, whereas urbanization is associated with decreases in disease end points. Natural biodiversity gradients, deforestation and forest fragmentation are comparatively unimportant or idiosyncratic as drivers of disease. Overall, these results are consistent across human and non-human diseases. Nevertheless, context-dependent effects of the global change drivers on disease were found to be common. The findings uncovered by this meta-analysis should help target disease management and surveillance efforts towards global change drivers that increase disease. Specifically, reducing greenhouse gas emissions, managing ecosystem health, and preventing biological invasions and biodiversity loss could help to reduce the burden of plant, animal and human diseases, especially when coupled with improvements to social and economic determinants of health.
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Biodiversidade , Mudança Climática , Doenças Transmissíveis , Poluição Ambiental , Espécies Introduzidas , Animais , Humanos , Efeitos Antropogênicos , Mudança Climática/estatística & dados numéricos , Doenças Transmissíveis/epidemiologia , Doenças Transmissíveis/etiologia , Conservação dos Recursos Naturais/tendências , Conjuntos de Dados como Assunto , Poluição Ambiental/efeitos adversos , Agricultura Florestal , Florestas , Espécies Introduzidas/estatística & dados numéricos , Doenças das Plantas/etiologia , Medição de Risco , UrbanizaçãoRESUMO
Thalamocortical loops have a central role in cognition and motor control, but precisely how they contribute to these processes is unclear. Recent studies showing evidence of plasticity in thalamocortical synapses indicate a role for the thalamus in shaping cortical dynamics through learning. Since signals undergo a compression from the cortex to the thalamus, we hypothesized that the computational role of the thalamus depends critically on the structure of corticothalamic connectivity. To test this, we identified the optimal corticothalamic structure that promotes biologically plausible learning in thalamocortical synapses. We found that corticothalamic projections specialized to communicate an efference copy of the cortical output benefit motor control, while communicating the modes of highest variance is optimal for working memory tasks. We analyzed neural recordings from mice performing grasping and delayed discrimination tasks and found corticothalamic communication consistent with these predictions. These results suggest that the thalamus orchestrates cortical dynamics in a functionally precise manner through structured connectivity.
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Aprendizagem , Tálamo , Tálamo/fisiologia , Animais , Camundongos , Aprendizagem/fisiologia , Córtex Cerebral/fisiologia , Memória de Curto Prazo/fisiologia , Vias Neurais/fisiologia , Sinapses/fisiologia , Camundongos Endogâmicos C57BL , MasculinoAssuntos
Corticosteroides , Infecções Comunitárias Adquiridas , Pneumonia , Choque Séptico , Humanos , Infecções Comunitárias Adquiridas/tratamento farmacológico , Infecções Comunitárias Adquiridas/complicações , Choque Séptico/tratamento farmacológico , Choque Séptico/complicações , Pneumonia/tratamento farmacológico , Pneumonia/complicações , Corticosteroides/uso terapêutico , IncertezaRESUMO
Spectral unmixing designates techniques that allow to decompose measured spectra into linear or non-linear combination of spectra of all targets (endmembers). This technique was initially developed for satellite applications, but it is now also widely used in biomedical applications. However, several drawbacks limit the use of these techniques with standard optical devices like RGB cameras. The devices need to be calibrated and a a priori on the observed scene is often necessary. We propose a new method for estimating endmembers and their proportion automatically and without calibration of the acquisition device based on near separable non-negative matrix factorization. This method estimates the endmembers on spectra of absorbance changes presenting periodic events. This is very common in in vivo biomedical and medical optical imaging where hemodynamics dominate the absorbance fluctuations. We applied the method for identifying functional brain areas during neurosurgery using four different RGB cameras (an industrial camera, a smartphone and two surgical microscopes). Results obtained with the auto-calibration method were consistent with the intraoperative gold standards. Endmembers estimated with the auto-calibration method were similar to the calibrated endmembers used in the modified Beer-Lambert law. The similarity was particularly strong when both cardiac and respiratory periodic events were considered. This work can allow a widespread use of spectral imaging in the industrial or medical field.
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OBJECTIVES: We sought to assess whether genetic associations with metabolite concentrations in septic shock patients could be used to identify pathways of potential importance for understanding sepsis pathophysiology. DESIGN: Retrospective multicenter cohort studies of septic shock patients. SETTING: All participants who were admitted to 27 participating hospital sites in three countries (Australia, New Zealand, and the United Kingdom) were eligible for inclusion. PATIENTS: Adult, critically ill, mechanically ventilated patients with septic shock (n = 230) who were a subset of the Adjunctive Corticosteroid Treatment in Critically Ill Patients with Septic Shock trial (ClinicalTrials.gov number: NCT01448109). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A genome-wide association study was conducted for a range of serum metabolite levels for participants. Genome-wide significant associations (p ≤ 5 × 10-8) were found for the two major ketone bodies (3-hydroxybutyrate [rs2456680] and acetoacetate [rs2213037] and creatinine (rs6851961). One of these single-nucleotide polymorphisms (SNPs) (rs2213037) was located in the alcohol dehydrogenase cluster of genes, which code for enzymes related to the metabolism of acetoacetate and, therefore, presents a plausible association for this metabolite. None of the three SNPs showed strong associations with risk of sepsis, 28- or 90-day mortality, or Acute Physiology and Chronic Health Evaluation score (a measure of sepsis severity). CONCLUSIONS: We suggest that the genetic associations with metabolites may reflect a starvation response rather than processes involved in sepsis pathophysiology. However, our results require further investigation and replication in both healthy and diseased cohorts including those of different ancestry.
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ABSTRACT: Purpose: To examine the relationship of early persistent lymphopenia with hospital survival in critically ill patients with and without sepsis to assess whether it can be considered a treatable trait. Methods: Retrospective database analysis of patients with nonelective admission to intensive care units (ICUs) during January 2015 to December 2018. Patients were classified as having sepsis if the Acute Physiology and Chronic Health Evaluation III admission diagnostic code included sepsis or coded for an infection combined with a Sequential Organ Failure Assessment score of ≥2. We defined early persistent lymphopenia at two thresholds (absolute lymphocyte count [ALC] <1.0 and <0.75 × 10 9 /L) based on two qualifying values recorded during the first 4 days in ICU. The main outcome measure was time to in-hospital death. Results: Of 8,507 eligible patients, 7,605 (89.4%) had two ALCs recorded during their first 4 days in ICU; of these, 1,482 (19.5%) had sepsis. Persistent lymphopenia (ALC <1.0) was present in 728 of 1,482 (49.1%) and 2,302 of 6,123 (37.6%) patients with and without sepsis, respectively. For ALC <0.75, the results were 487 of 1,482 (32.9%) and 1,125 of 6,123 (18.4%), respectively. Of 3,030 patients with persistent lymphopenia (ALC <1.0), 562 (18.5%) died compared with 439 of 4,575 (9.6%) without persistent lymphopenia. Persistent lymphopenia was an independent risk factor for in-hospital death in all patients. The hazard ratios for death at ALC <1.0 were 1.89 (95% confidence interval, 1.32-2.71; P = 0.0005) and 1.17 (95% confidence interval, 1.02-1.35; P = 0.0246) in patients with and without sepsis respectively. Conclusions: Early persistent lymphopenia is common in critically ill patients and associated with increased risk of death in patients with and without sepsis. Although the association is stronger in patients with sepsis, lymphopenia is a candidate to be considered a treatable trait; drugs that reverse lymphopenia should be trialed in critically ill patients.
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Linfopenia , Sepse , Humanos , Estudos Retrospectivos , Estado Terminal , Mortalidade Hospitalar , Prognóstico , Linfopenia/complicações , Unidades de Terapia Intensiva , Curva ROCRESUMO
Responses of wildlife to climate change are typically quantified at the species level, but physiological evidence suggests significant intraspecific variation in thermal sensitivity given adaptation to local environments and plasticity required to adjust to seasonal environments. Spatial and temporal variation in thermal responses may carry important implications for climate change vulnerability; for instance, sensitivity to extreme weather may increase in specific regions or seasons. Here, we leverage high-resolution observational data from eBird to understand regional and seasonal variation in thermal sensitivity for 21 bird species. Across their ranges, most birds demonstrated regional and seasonal variation in both thermal peak and range, or the temperature and range of temperatures when observations peaked. Some birds demonstrated constant thermal peaks or ranges across their geographical distributions, while others varied according to local and current environmental conditions. Across species, birds typically demonstrated either geographical or seasonal adaptation to climate. Local adaptation and phenotypic plasticity are likely important but neglected aspects of organismal responses to climate change.
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Animais Selvagens , Aves , Animais , Estações do Ano , Aves/fisiologia , Temperatura , Mudança Climática , América do NorteRESUMO
Blood flow in large veins is dependent on arterial-atrial pressure gradients and pumping mechanisms in concert with valve recruitment. Classic descriptions of muscle and respiratory pumps describe venous transmural pressure changes that cause flow. Not often considered is the transmission of pulsatile energy from arteries to veins directly adjacent to each other. Recently, an ex vivo study demonstrated a novel arterial pump effect in venoarterial bundles when valves were active in managing venous flow. We sought to show in vivo evidence of this arterial pump mechanism in 16 healthy young adults. Venous blood flow was measured in the venoarterial bundled deep femoral vein (DFV) and the greater saphenous vein (GSV), which is not bundled with an artery. Veins were studied through randomized body positions of -6° head-down tilt (HDT), supine, 20° head-up tilt (HUT), and 40° HUT, with the assumption that greater HUT postures increased valve dependence to observe the arterial pump effect. Between 20° and 40° HUT conditions, bundled DFV blood flow did not change (68 ± 36 vs. 71 ± 56 mL·min-1; Padj > 0.99), whereas nonbundled GSV blood flow decreased (6.1 ± 4.8 vs. 3.5 ± 3.9 mL·min-1; P = 0.01). Diameters between 20° and 40° HUT conditions increased in DFV (0.90 ± 0.16 vs. 1.04 ± 0.19 cm; P < 0.01), but not in GSV (0.33 ± 0.10 vs. 0.32 ± 0.08 cm; P = 0.60). These data support previous ex vivo observations that when venous pressure gradients rely on valve recruitment, presence of an adjacent artery may protect against further decreases in blood flow. The arterial pump mechanism is an underappreciated contributor to venous return and warrants further investigation.NEW & NOTEWORTHY Venous return mechanisms have classically considered muscle and respiratory pumps; however, recent ex vivo evidence suggests that pulsatile energy imparted from arteries to adjacent bundled veins can increase venous flow under certain driving pressures. We tested this concept in humans by manipulating hydrostatic pressures and measuring flow in bundled and nonbundled veins. The bundled vein exhibited flow preservation at the highest hydrostatic pressure. We suggest a novel conservation of energy mechanism within the circulatory system.
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Pressão Arterial , Hemodinâmica , Adulto Jovem , Humanos , Velocidade do Fluxo Sanguíneo/fisiologia , Decúbito Inclinado com Rebaixamento da Cabeça , Postura/fisiologiaRESUMO
Genome-wide association studies (GWAS) have underrepresented individuals from non-European populations, impeding progress in characterizing the genetic architecture and consequences of health and disease traits. To address this, we present a population-stratified phenome-wide GWAS followed by a multi-population meta-analysis for 2,068 traits derived from electronic health records of 635,969 participants in the Million Veteran Program (MVP), a longitudinal cohort study of diverse U.S. Veterans genetically similar to the respective African (121,177), Admixed American (59,048), East Asian (6,702), and European (449,042) superpopulations defined by the 1000 Genomes Project. We identified 38,270 independent variants associating with one or more traits at experiment-wide P<4.6×10-11 significance; fine-mapping 6,318 signals identified from 613 traits to single-variant resolution. Among these, a third (2,069) of the associations were found only among participants genetically similar to non-European reference populations, demonstrating the importance of expanding diversity in genetic studies. Our work provides a comprehensive atlas of phenome-wide genetic associations for future studies dissecting the architecture of complex traits in diverse populations.
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INTRODUCTION: Blood pressure (BP) management is common in patients with aneurysmal subarachnoid hemorrhage (SAH) admitted to an intensive care unit. However, the practice patterns of BP management (timing, dose, and duration) have not been studied locally. METHODS: This post hoc analysis explored BP management goals (defined as the setting of a minimum systolic BP target or application of induced hypertension) in patients enrolled into the PROMOTE-SAH study in eleven neurosurgical centers in Australia and New Zealand. The primary outcome was 'dead or disabled' (modified Rankin Score ≥4) at 6 months, with the hypothesis being that setting BP management goals would be associated with improved outcomes. RESULTS: BP management goals were recorded in 266 of 357 (75%) patients, of which 149 were recorded as receiving induced hypertension for delayed cerebral ischemia (DCI) or vasospasm on 738 (19%) study days. In patients with a minimum systolic BP goal recorded (on 2067 d), the indication for the BP management goal was vasospasm or DCI on 651 (32%) days; no indication for BP management goals was documented on 1416 (69%) days. Crude analysis demonstrated an association between setting BP management goals and reduced death or disability (P=0.03), but this association was not significant after adjustment for the presence of DCI or vasospasm and clustered by the site. CONCLUSIONS: BP management goals are commonly 'prescribed' to aSAH patients admitted to an intensive care unit in Australia and New Zealand, but BP management goal setting was not associated with improved outcomes in the adjusted analysis.
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Competitive rock climbing recently made its Olympic debut, but minimal published research exists regarding training and competition strategies. Time management strategies define the structured approach climbers take in bouldering competitions to successfully obtain a "top" or a "zone" hold. During finals rounds of the International Federation of Sport Climbing bouldering competitions, climbers are allotted 240 s to complete a boulder. Variables influencing a climber's time management strategies include their work-to-rest intervals, and the frequency of their attempts or rests. Video analysis of International Federation of Sport Climbing competitions was used to collect time management strategy data of professional climbers. Fifty-six boulders (28 female and 28 male boulders) over the 2019 International Federation of Sport Climbing season were analyzed. Time management strategies variables were compared between slab/slab-like and non-slab bouldering styles using generalized estimating equations with significance set to p < 0.05. Additionally, we determined trends in success rates for various styles of boulders. There were no differences in the number of attempts taken per boulder between slab/slab-like and non-slab boulders (3.7 ± 2.3 and 3.8 ± 2.4, p = 0.97), but climbers spent more time actively climbing on slab/slab-like (92 ± 36 s) compared to non-slab boulders (65 ± 26 s, p < 0.001). Trends in the success rate suggest climbers who take more than 6 attempts on any boulder style are unsuccessful. The results of this study provide practical information that can be used by coaches and athletes to guide training and competition strategy.
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Arterial wave reflection augments cardiac afterload increasing myocardial demands. Mathematical models and comparative physiology suggest that the lower limbs are the primary source of reflected waves; however, in vivo human evidence corroborating these observations is lacking. This study was designed to determine whether the vasculature of the lower or upper limbs contributes more to wave reflection. We hypothesized that lower limb heating will result in larger reductions in central wave reflection compared with upper limb heating due to local vasodilation of a larger microvascular bed. Fifteen healthy adults (8 females, 24 ± 3.6 yr) completed a within-subjects experimental crossover protocol with a washout period. The right upper and lower limbs were heated in a randomized order using 38°C water-perfused tubing with a 30-min break between protocols. Central wave reflection was calculated using pressure-flow relationships derived from aortic blood flow and carotid arterial pressure at baseline and after 30 min of heating. We observed a main effect of time for reflected wave amplitude (12.8 ± 2.7 to 12.2 ± 2.6 mmHg; P = 0.03) and augmentation index (-7.5 ± 8.9% to -4.5 ± 9.1%; P = 0.03). No significant main effects or interactions were noted for forward wave amplitude, reflected wave arrival time, or central relative wave reflection magnitude (all P values >0.23). Unilateral limb heating reduced reflected wave amplitude; however, the lack of a difference between conditions does not support the hypothesis that the lower limbs are the primary source of reflection. Future investigations should consider alternative vascular beds, such as splanchnic circulation.NEW & NOTEWORTHY Lower limb contributions to central wave reflections have been theorized without direct evidence in humans. In this study, mild passive heating was used to locally vasodilate either the right arm or leg to control local wave reflection sites. Heating in general reduced the reflected wave amplitude, but there were no differences between the arm or leg heating intervention, failing to provide support for the lower limbs as a primary contributor to wave reflection in humans.
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Calefação , Vasodilatação , Adulto , Feminino , Humanos , Vasodilatação/fisiologia , Pressão Sanguínea/fisiologia , Hemodinâmica/fisiologia , Artérias Carótidas/fisiologia , Análise de Onda de PulsoRESUMO
The purpose of this investigation was to evaluate whether continuous glucose monitoring (CGM) sensors worn on the active muscle may provide enhanced insight into glucose control in non-diabetic participants during cycling exercise compared to traditional sensor placement on the arm. Data from 9 healthy participants (F:3) was recorded using CGM sensors on the arm (triceps brachii) and leg (vastus medialis) following 100â g glucose ingestion during 30â min experimental visits of: resting control, graded cycling, electrically stimulated quadriceps contractions, and passive whole-body heating. Finger capillary glucose was used to assess sensor accuracy. Under control conditions, the traditional arm sensor better reflected capillary glucose, with a mean absolute relative difference (MARD) of 12.4 ± 9.3% versus 18.3 ± 11.4% in the leg (P = 0.02). For the intended use during exercise, the sensor-site difference was attenuated, with similar MARDs during cycling (arm:15.5 ± 12% versus leg:16.7 ± 10.8%, P = 0.96) and quadriceps stimulation (arm:15.5 ± 14.8% versus leg:13.9 ± 9.5%, P = 0.9). At rest, glucose at the leg was consistently lower than the arm (P = 0.01); whereas, during graded cycling, the leg-glucose was lower only after maximal intensity exercise (P = 0.02). There was no difference between sensors during quadriceps stimulation (P = 0.8). Passive heating caused leg-skin temperature to increase by 3.1 ± 1.8°C versus 1.1 ± 0.72°C at the arm (P = 0.002), elevating MARD in the leg (23.5 ± 16.2%) and lowering glucose in the leg (P < 0.001). At rest, traditional placement of CGM sensors on the arm may best reflect blood glucose; however, during cycling, placement on the leg may offer greater insight to working muscle glucose concentrations, and this is likely due to greater blood-flow rather than muscle contractions.HighlightsWearing a continuous glucose monitoring (CGM) sensor on the arm may better reflect capillary glucose concentrations compared to wearing a sensor on the inner thigh at rest.With passive or active leg-muscle contractions, site-specific differences compared to capillary samples are attenuated; therefore, wearing a CGM sensor on the active-muscle during exercise may provide greater information to non-diabetic athletes regarding glucose flux at the active muscle.Discrepancies in CGM sensors worn at different sites likely primarily reflects differences in blood flow, as passive skin heating caused the largest magnitude difference between arm and leg sensor readings compared to the other experimental conditions (control, electric muscle stimulation, and cycling exercise).
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Automonitorização da Glicemia , Glicemia , Humanos , Glucose , Exercício Físico/fisiologia , Músculo EsqueléticoRESUMO
The cerebellum is considered a "learning machine" essential for time interval estimation underlying motor coordination and other behaviors. Theoretical work has proposed that the cerebellum's input recipient structure, the granule cell layer (GCL), performs pattern separation of inputs that facilitates learning in Purkinje cells (P-cells). However, the relationship between input reformatting and learning has remained debated, with roles emphasized for pattern separation features from sparsification to decorrelation. We took a novel approach by training a minimalist model of the cerebellar cortex to learn complex time-series data from time-varying inputs, typical during movements. The model robustly produced temporal basis sets from these inputs, and the resultant GCL output supported better learning of temporally complex target functions than mossy fibers alone. Learning was optimized at intermediate threshold levels, supporting relatively dense granule cell activity, yet the key statistical features in GCL population activity that drove learning differed from those seen previously for classification tasks. These findings advance testable hypotheses for mechanisms of temporal basis set formation and predict that moderately dense population activity optimizes learning.NEW & NOTEWORTHY During movement, mossy fiber inputs to the cerebellum relay time-varying information with strong intrinsic relationships to ongoing movement. Are such mossy fibers signals sufficient to support Purkinje signals and learning? In a model, we show how the GCL greatly improves Purkinje learning of complex, temporally dynamic signals relative to mossy fibers alone. Learning-optimized GCL population activity was moderately dense, which retained intrinsic input variance while also performing pattern separation.
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Córtex Cerebelar , Cerebelo , Neurônios , Aprendizagem , Células de PurkinjeRESUMO
Animals are facing novel 'timescapes' in which the stimuli entraining their daily activity patterns no longer match historical conditions due to anthropogenic disturbance. However, the ecological effects (e.g., altered physiology, species interactions) of novel activity timing are virtually unknown. We reviewed 1328 studies and found relatively few focusing on anthropogenic effects on activity timing. We suggest three hypotheses to stimulate future research: (i) activity-timing mismatches determine ecological effects, (ii) duration and timing of timescape modification influence effects, and (iii) consequences of altered activity timing vary biogeographically due to broad-scale variation in factors compressing timescapes. The continued growth of sampling technologies promises to facilitate the study of the consequences of altered activity timing, with emerging applications for biodiversity conservation.
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Biodiversidade , Ecossistema , AnimaisRESUMO
BACKGROUND: Trials and study-level meta-analyses have failed to resolve the role of corticosteroids in the management of patients with septic shock. Patient-level meta-analyses may provide more precise estimates of treatment effects, particularly subgroup effects. METHODS: We pooled individual patient data from septic shock trials investigating the adjunctive use of intravenous hydrocortisone. The primary outcome was 90-day all-cause mortality, and it was also analyzed across predefined subgroups. Secondary outcomes included mortality at intensive care unit and hospital discharge, at 28 and 180 days, and vasopressor-, ventilator-, and organ failurefree days. Adverse events included superinfection, muscle weakness, hyperglycemia, hypernatremia, and gastroduodenal bleeding. RESULTS: Of 24 eligible trials (n=8528), 17 (n=7882) provided individual patient data, and 7 (n=5929) provided 90-day mortality. The marginal relative risk (RR) for 90-day mortality of hydrocortisone versus placebo was 0.93 (95% confidence interval [CI], 0.82 to 1.04; P=0.22; moderate certainty). It was 0.86 (95% CI, 0.79 to 0.92) for hydrocortisone with fludrocortisone and 0.96 (95% CI, 0.82 to 1.12) without fludrocortisone. There was no significant differential treatment effect across subgroups. Hydrocortisone was associated with little to no difference in any of the secondary outcomes except vasopressor-free days (mean difference, 1.24 days; 95% CI, 0.74 to 1.73; high certainty). Hydrocortisone may not be associated with an increase in the risk of superinfection (RR, 1.04; 95% CI, 0.95 to 1.15; low certainty), hyperglycemia (RR, 1.05; 95% CI, 0.98 to 1.12; low certainty), or gastroduodenal bleeding (RR, 1.11; 95% CI, 0.83 to 1.48; low certainty). Hydrocortisone may be associated with an increase in the risk of hypernatremia (RR, 2.01; 95% CI, 1.56 to 2.60; low certainty) and muscle weakness (n=2647; RR, 1.73; 95% CI, 1.49 to 1.99; low certainty). CONCLUSIONS: In this patient-level meta-analysis, hydrocortisone compared with placebo was not associated with reduced mortality for patients with septic shock. (Funded by "Programme d'Investissements d'Avenir," a research Professorship from the National Institute of Health and Care Research, Leadership Fellowships from the National Health and Medical Research Council of Australia, and Emerging Leaders Fellowship from the National Health and Medical Research Council of Australia; PROSPERO registration number, CRD42017062198.)