Biology subjects

Hays, A.

Publications and source records attributed to Hays, A..

3 recordsLinked to original sources

bioRxiv2026

Noninvasive thigh temperature mapping after cold water immersion and subsequent exercise using magnetic resonance spectrometry.

Heat-related illnesses pose a significant public health challenge in Europe, resulting in increased mortality. Although cold water immersion (CWI) is the most effective treatment for heat stroke, its clinical use is limited. A better understanding of temperature changes in the peripheral body regions can lead to more effective CWI application. Nevertheless, most muscle temperature measurement techniques are invasive. This study evaluated magnetic resonance spectroscopy (MRS) for non-invasive assessment of intramuscular temperature during cold stress and rewarming. Nine healthy volunteers (7 men, 2 women) participated in three 3T MRI sessions: baseline (PRE), immediately after 15 minutes of CWI at 10 degrees to the iliac crest (POST-CWI), and following 100-Watt cycling (POST-cycling). Each scan session included T1w and localized spectroscopy acquisitions in the right thigh. Absolute temperature was estimated from the proton resonance frequency shift between water and creatine peaks. The measurements were split into three groups of voxels, defined as follows: close to the top (TL), bottom (BL), or central (DL) thigh positions. Measurement depth showed a location main effect (p<0.001, p^2=0.40), with DL (35.4[5.9] mm) significantly deeper than TL (22.5[4.2] mm) and BL (25.3[5.1] mm), remaining constant across phases. Temperature decreased significantly from PRE to POST-CWI across all locations (TL: p<0.001, d=2.74; BL: p<0.001, d=1.84; DL: p<0.005, d=1.14). Post-cycling temperature increased at all sites compared to POST-CWI (DL: p=0.040, d=1.06; TL: p<0.001, d=1.7; BL: p<0.001, d=1.80), though TL remained lower than PRE (p<0.017, d=1.48). During POST-CWI, DL showed a significantly higher temperature than TL (p<0.001, d=2.13) and BL (p<0.001, d=2.06). These findings demonstrate that MRS-based temperature mapping provides unique anatomical and thermal characterization of muscle during thermoregulatory stress. While results are promising for understanding CWI mechanisms, validation in larger cohorts is necessary to establish clinical reliability and reproducibility for heat illness management.

physiology↗

bioRxiv2025

Metabolic and Redox Pathway Dysregulation in HIV-Associated Coronary Endothelial Dysfunction

BackgroundPeople with HIV (PWH), even with sustained viral suppression on antiretroviral therapy (ART), remain at increased risk for cardiovascular disease. Coronary endothelial dysfunction, a sensitive marker of early vascular injury and a potential target for intervention is common in this population, but its biological basis remains unknown. MethodsWe performed a cross-sectional study combining in vivo coronary MRI and high-throughput serum proteomics to investigate mechanisms of coronary endothelial dysfunction in treated HIV. Forty-five virally suppressed PWH and twenty-nine age- and sex-matched healthy controls underwent coronary MRI during isometric handgrip exercise to quantify coronary endothelial function, defined as the percentage change in coronary cross-sectional area (%CSA) from rest to stress. An increase in coronary CSA <2% indicated endothelial dysfunction. Parallel serum proteomic profiling was performed using the SomaScan 7K platform, and differential protein expression between groups was analyzed using linear modeling (LIMMA). ResultsCoronary endothelial dysfunction was more prevalent in PWH with suppressed viral load compared to controls (67% vs 10%, p<0.001). Pathway analysis of differentially expressed proteins between participants with and without endothelial dysfunction highlighted significant dysregulation of glutathione dependent detoxification, oxidative metabolism and fatty acid {beta}-oxidation pathways in individuals with endothelial dysfunction (adjusted p value <0.05). ConclusionsEndothelial dysfunction in PWH on ART is associated with metabolic and redox imbalance. These findings highlight glutathione and fatty acid oxidation related pathways as potential therapeutic targets for reducing cardiovascular risk in this patient population.

immunology↗

bioRxiv2023

High-intensity physical activity enhances cognitive decision processes

This study investigates the acute impact of high-intensity activity on perceptual decision-making, using computational modeling to assess changes during and after physical activity. Participants performed a two-alternative forced choice perceptual decision-making task at rest (pre- and post-exercise) and during six of eight 5-minute cycling bouts (totaling 47 minutes) under dual-task condition, while maintaining an average intensity of 86 {+/-} 7% of their maximum heart rate. Drift diffusion modeling was applied to accuracy and reaction time data to estimate changes in evidence accumulation (drift rate), decision threshold (boundary separation), and non-decision processes (ter). Results revealed improved post-exercise performance, characterized by shorter non-decision time, potentially reflecting a transient improvement in motor or perceptual efficiency. During ongoing physical activity, results indicate that exercise is associated with a decrease in non-decision time and an increase in the efficiency of evidence accumulation, while response caution remains stable. These findings provide novel insights into how sustained high-intensity exercise modulates perceptual decision-making dynamics under physiological stress.

neuroscience↗