The association between overall health, psychological distress, and occupational heat stress among a large national cohort of 40,913 Thai workers

BACKGROUND Occupational heat stress is a well-known problem, particularly in tropical countries, affecting workers, health and well-being. There are very few recent studies that have reported on the effect of heat stress on mental health, or overall health in workers, although socioeconomic development and rapid urbanization in tropical developing countries like Thailand create working conditions in which heat stress is likely. OBJECTIVE This study is aimed at identifying the relationship between self-reported heat stress and psychological distress, and overall health status in Thai workers. RESULTS 18% of our large national cohort (>40,000 subjects) often works under heat stress conditions and males are exposed to heat stress more often than females. Furthermore, working under heat stress conditions is associated with both worse overall health and psychological distress (adjusted odds ratios ranging from 1.49 to 1.84). CONCLUSIONS This association between occupational heat stress and worse health needs more public health attention and further development on occupational health interventions as climate change increases Thailand's temperatures.This study was supported by the International Collaborative Research Grants Scheme with joint grants from the Wellcome Trust UK (GR0587MA) and the Australian NHMRC (268055)

Phenotypic evidence for local adaptation to heat stress in the marine snail Chlorostoma (formerly Tegula) funebralis

Southern California (USA) populations of the intertidal marine snail Chlorostoma (formerly Tegula) funebralis generally occupy warmer climates and are exposed to high air temperatures during low tides more often than northern California populations. Available genetic data suggest there is extensive gene flow across a broad range of C. funebralis populations, so it is unclear if populations can adapt to differences in local environments. To test for population-specific responses to heat stress, three phenotypic assays were performed on three northern and on three southern populations of C. funebralis, after acclimation to common-garden conditions in the laboratory. Thermal drop-down, heat stress mortality, and heat stress reattachment assays were designed to evaluate ecologically relevant phenotypic responses to heat stress; these assays assessed tolerance during, mortality following, and speed of recovery following heat stress. The latter two tests indicate that southern populations consistently suffer significantly lower mortality and recover significantly more quickly following heat stress compared to northern populations. Hierarchical cluster analysis of stress response data clearly identified northern California and southern California regional groupings of populations. Thus, these results indicate that southern populations have higher tolerance to heat stress than northern populations and suggest that adaptation to local environmental differences can evolve despite moderate potential for larval dispersal in this species. Accounting for intraspecific population variation in thermal tolerance may provide important insights for predicting how species distributions will respond to global warming. © 2013 Elsevier B.V

Whole-body heat stress and exercise stimulate the appearance of platelet microvesicles in plasma with limited influence of vascular shear stress

Intense, large muscle mass exercise increases circulating microvesicles, but our understanding of microvesicle dynamics and mechanisms inducing their release remains limited. However, increased vascular shear stress is generally thought to be involved. Here, we manipulated exercise-independent and exercise-dependent shear stress using systemic heat stress with localized single-leg cooling (low shear) followed by single-leg knee extensor exercise with the cooled or heated leg (Study 1, n = 8) and whole-body passive heat stress followed by cycling (Study 2, n = 8). We quantified femoral artery shear rates (SRs) and arterial and venous platelet microvesicles (PMV-CD41+) and endothelial microvesicles (EMV-CD62E+). In Study 1, mild passive heat stress while one leg remained cooled did not affect [microvesicle] (P ≥ 0.05). Single-leg knee extensor exercise increased active leg SRs by ~12-fold and increased arterial and venous [PMVs] by two- to threefold, even in the nonexercising contralateral leg (P < 0.05). In Study 2, moderate whole-body passive heat stress increased arterial [PMV] compared with baseline (mean±SE, from 19.9 ± 1.5 to 35.5 ± 5.4 PMV.μL-1.103, P < 0.05), and cycling with heat stress increased [PMV] further in the venous circulation (from 27.5 ± 2.2 at baseline to 57.5 ± 7.2 PMV.μL-1.103 during cycling with heat stress, P < 0.05), with a tendency for increased appearance of PMV across exercising limbs. Taken together, these findings demonstrate that whole-body heat stress may increase arterial [PMV], and intense exercise engaging either large or small muscle mass promote PMV formation locally and systemically, with no influence upon [EMV]. Local shear stress, however, does not appear to be the major stimulus modulating PMV formation in healthy humans

Contribution of time of day and the circadian clock to the heat stress responsive transcriptome in Arabidopsis.

In Arabidopsis, a large subset of heat responsive genes exhibits diurnal or circadian oscillations. However, to what extent the dimension of time and/or the circadian clock contribute to heat stress responses remains largely unknown. To determine the direct contribution of time of day and/or the clock to differential heat stress responses, we probed wild-type and mutants of the circadian clock genes CCA1, LHY, PRR7, and PRR9 following exposure to heat (37 °C) and moderate cold (10 °C) in the early morning (ZT1) and afternoon (ZT6). Thousands of genes were differentially expressed in response to temperature, time of day, and/or the clock mutation. Approximately 30% more genes were differentially expressed in the afternoon compared to the morning, and heat stress significantly perturbed the transcriptome. Of the DEGs (~3000) specifically responsive to heat stress, ~70% showed time of day (ZT1 or ZT6) occurrence of the transcriptional response. For the DEGs (~1400) that are shared between ZT1 and ZT6, we observed changes to the magnitude of the transcriptional response. In addition, ~2% of all DEGs showed differential responses to temperature stress in the clock mutants. The findings in this study highlight a significant role for time of day in the heat stress responsive transcriptome, and the clock through CCA1 and LHY, appears to have a more profound role than PRR7 and PRR9 in modulating heat stress responses during the day. Our results emphasize the importance of considering the dimension of time in studies on abiotic stress responses in Arabidopsis

Impact of phenylpropanoid compounds on heat stress tolerance in carrot cell cultures

The phenylpropanoid and flavonoid families include thousands of specialized metabolites that influence a wide range of processes in plants, including seed dispersal, auxin transport, photoprotection, mechanical support and protection against insect herbivory. Such metabolites play a key role in the protection of plants against abiotic stress, in many cases through their well-known ability to inhibit the formation of reactive oxygen species (ROS). However, the precise role of specific phenylpropanoid and flavonoid molecules is unclear. We therefore investigated the role of specific anthocyanins (ACs) and other phenylpropanoids that accumulate in carrot cells cultivated in vitro, focusing on their supposed ability to protect cells from heat stress. First we characterized the effects of heat stress to identify quantifiable morphological traits as markers of heat stress susceptibility. We then fed the cultures with precursors to induce the targeted accumulation of specific compounds, and compared the impact of heat stress in these cultures and unfed controls. Data modeling based on Projection to Latent Structures (PLS) regression revealed that metabolites containing coumaric or caffeic acid, including ACs, correlate with less heat damage. Further experiments suggested that one of the cellular targets damaged by heat stress and protected by these metabolites is the actin microfilament cytoskeleton

The Influence of Heat Stress and Powder of Jaloh Leaves Supplementation Into Commercial Fish Feed on Body Weight Gain, Hematokrit Level and Malondialdehid Content in the Nila's Liver

The aims of this experiment are to find out the effect of temperature stress and jaloh leaves supplementation on body weight gain, hematocrit level, and malondialdehid (MDA) content in the liver tissues of nila fish (Oreochromis niloticus). A total of 80 fishes with the weight of 40-50 gr were randomly allocated into 8 treatments. The treatments consisted of P1 (no heat stress and no jaloh leaves supplementation); P2 (no heat stress and 5% of jaloh leaves supplementation) ; P3 (no heat stress and 10% of leaves supplementation); P4 (no heat stress and 15 % of leaves supplementation); P5 (heat stress and no jaloh leaves supplementation); P6 (heat stress and 5% of jaloh leaves supplementation); P7 (heat stress and 10% of jaloh leaves supplementation); P8 (heat stress about 35 ± 1oC for 4 h per day in 30 days and 15% of jaloh leaves supplementation). The body weight was measured from 1d to 31d. Blood samples, lever tissues and statistical analysis were conducted on 31d. The results of the experiments indicated that supplementation of fish feed with jaloh leaves 5-15% had negative effects on body weight gain. On the other hand, supplementation of jaloh leaves 5-10% on commercial fish feed had positive effects on performances and immune system of experiment fishe

Local temperature-sensitive mechanisms are important mediators of limb tissue hyperemia in the heat-stressed human at rest and during small muscle mass exercise.

Limb tissue and systemic blood flow increases with heat stress, but the underlying mechanisms remain poorly understood. Here, we tested the hypothesis that heat stress-induced increases in limb tissue perfusion are primarily mediated by local temperature-sensitive mechanisms. Leg and systemic temperatures and hemodynamics were measured at rest and during incremental single-legged knee extensor exercise in 15 males exposed to 1 h of either systemic passive heat-stress with simultaneous cooling of a single leg (n=8) or isolated leg heating or cooling (n=7). Systemic heat-stress increased core, skin and heated leg blood (Tb) temperatures, cardiac output and heated leg blood flow (LBF, 0.6 ± 0.1 l.min(-1); P0.05). Increased heated leg deep tissue BF was closely related to Tb (R(2) = 0.50; P0.05), despite unchanged systemic temperatures and hemodynamics. During incremental exercise, heated LBF was consistently maintained ~ 0.6 l.min(-1) higher than that in the cooled leg (P<0.01), with LBF and vascular conductance in both legs showing a strong correlation with their respective local Tb (R(2) = 0.85 and 0.95, P<0.05). We conclude that local temperature-sensitive mechanisms are important mediators in limb tissue perfusion regulation both at rest and during small-muscle mass exercise in hyperthermic humans.The invasive study was partially funded by Gatorade Sports Science Institute, PepsiCo

Some Like It Hot, Some Like It Warm: Phenotyping To Explore Thermotolerance Diversity

Plants have evolved overlapping but distinct cellular responses to different aspects of high temperature stress. These responses include basal thermotolerance, short- and long-term acquired thermotolerance, and thermotolerance to moderately high temperatures. This ‘thermotolerance diversity’ means that multiple phenotypic assays are essential for fully describing the functions of genes involved in heat stress responses. A large number of genes with potential roles in heat stress responses have been identified using genetic screens and genome wide expression studies. We examine the range of phenotypic assays that have been used to characterize thermotolerance phenotypes in both Arabidopsis and crop plants. Three major variables differentiate thermotolerance assays: (1) the heat stress regime used, (2) the developmental stage of the plants being studied, and (3) the actual phenotype which is scored. Consideration of these variables will be essential for deepening our understanding of the molecular genetics of plant thermotolerance

Polymorphisms of Bovine HSP90 and Their Implications in Beef Cattle Productivity

Production of beef cattle represents a $60 billion industry in the United States (USDA, 2015). The American beef cattle industry loses an estimated$370 million annually due to heat stress (St-Pierre, 2003). As of 2003, this was equal to nearly 99 million pounds of beef lost (USDA, 2015). The average American consumed roughly 65 pounds of beef in 2003; this means that the 99 million pounds of beef lost to heat stress would have been enough to feed approximately 1.5 million Americans for an entire year (Barclay, 2012)

Effect of Heat Stress on Crossbred Dairy Cattle in Tropical Nepal: Impact on Blood Parameters

Chitwan district of Nepal has been known as the dairy kingdom of the country considering its strategic location andpotential to easily provision inputs and produce as well as market quality milk across the country. However, theclimate especially during summer has been a challenge to farmers that potentially compromise the daily milk yieldof cows. Therefore, sixteen crossbred dairy cattle were placed in a RCBD fashion to assess the impacts of cold waterbathing in ameliorating effect of heat stress on their performance and body physiology. Routine assessment of themicroclimate within the experimental shed and blood parameters was made. The results from the experimentinferred that frequency of bathing (none, once, twice or thrice a day) did not have any significant impact onHaemoglobin, Haematocrit, Sodium, Potassium, Chloride and Bicarbonate levels in the blood plasma(p&gt;0.05). Inaddition, the animals did not exhibit any signs of physiological distress clinically either. A detailed study scopingtemperature humidity index and over a number of other milk and blood parameters are to be tested across a numberof other available breeds too in order for the researchers to come to a meaningful strategy to beat the heat stress