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Sample records for heat stress assessment

  1. Climate change and occupational heat stress: methods for assessment

    PubMed Central

    Holmér, Ingvar

    2010-01-01

    Background Presumed effects of global warming on occupational heat stress aggravate conditions in many parts of the world, in particular in developing countries. In order to assess and evaluate conditions, heat stress must be described and measured correctly. Objective Assessment of heat stress using internationally recognized methods. Design Two such methods are wet bulb globe temperature (WBGT; ISO 7243) and predicted heat strain (PHS; ISO 7933). Both methods measure relevant climatic factors and provide recommendations for limit values in terms of time when heat stress becomes imminent. The WBGT as a heat stress index is empirical and widely recognized. It requires, however, special sensors for the climatic factors that can introduce significant measurement errors if prescriptions in ISO 7243 are not followed. The PHS (ISO 7933) is based on climatic factors that can easily be measured with traditional instruments. It evaluates the conditions for heat balance in a more rational way and it applies equally to all combinations of climates. Results Analyzing similar climatic conditions with WBGT and PHS indicates that WBGT provides a more conservative assessment philosophy that allows much shorter working time than predicted with PHS. Conclusions PHS prediction of physiological strain appears to fit better with published data from warm countries. Both methods should be used and validated more extensively worldwide in order to give reliable and accurate information about the actual heat stress. PMID:21139697

  2. Heat stress assessment among workers in a Nicaraguan sugarcane farm

    PubMed Central

    Delgado Cortez, Orlando

    2009-01-01

    Background Heat illness is a major cause of preventable morbidity worldwide. Workers exposed to intense heat can become unable to activate compensation mechanisms, putting their health at risk. Heat stress also has a direct impact on production by causing poor task performance and it increases the possibility of work-related morbidity and injuries. During the sugarcane harvest period, workers are exposed to excessive sunlight and heat from approximately 6 am to 3 pm. A first assessment of heat stress during the 2006/2007 harvesting season served to redesign the existing rehydration measures. In this project, sugarcane workers were provided with more rehydration solutions and water during their work schedule. Objective To assess heat stress preventive measures in order to improve existing rehydration strategies as a means of increasing productivity. Methods A small group of 22 workers were followed up for 15 days during working hours, from 6 am to 3 pm. Selection criteria were defined: to have worked more than 50% of the day's working schedule and to have worked for at least 10 days of the follow-up period. A simple data recollection sheet was used. Information regarding the amount of liquid intake was registered. Production output data was also registered. Temperature measurements were recorded by using a portable temperature monitoring device (‘EasyLog’, model EL-USB-2). Results The average temperature measurements were above the Nicaraguan Ministry of Labour thresholds. Seven workers drank 7–8 L of liquid, improving their production. Output production increased significantly (p=0.005) among those best hydrated, from 5.5 to 8 tons of cut sugarcane per worker per day. Conclusions Productivity improved with the new rehydration measures. Awareness among workers concerning heat stress prevention was increased. PMID:20052378

  3. Study of heat-stress levels in naturally ventilated sheep barns during heat waves: development and assessment of regression models

    NASA Astrophysics Data System (ADS)

    Papanastasiou, D. K.; Bartzanas, T.; Panagakis, P.; Zhang, G.; Kittas, C.

    2016-11-01

    It is well documented that heat-stress burdens sheep welfare and productivity. Peak heat-stress levels are observed when high temperatures prevail, i.e. during heat waves; however, continuous measurements inside livestock buildings are not usually available for long periods so as to study the variation of summer heat-stress levels for several years, especially during extreme hot weather. Α methodology to develop a long time series of summer temperature and relative humidity inside naturally ventilated sheep barns is proposed. The accuracy and the transferability of the developed linear regression models were verified. Temperature Humidity Index (THI) was used to assess sheep's potential heat-stress. Τhe variation of THI inside a barn during heat wave and non-heat wave days was examined, and the results were comparatively assessed. The analysis showed that sheep were exposed to moderate, severe, and extreme severe heat-stress in 10, 21 and 66 % of hours, respectively, during heat wave days, while the corresponding values during non-heat wave days were 14, 33 and 43 %, respectively. The heat load on sheep was much higher during heat wave events than during non-heat wave periods. Additionally, based on the averaged diurnal variation of THI, it was concluded that extreme severe heat-stress conditions were prevailing between 1000 and 2400 hours local time during heat wave days. Cool off night periods were never and extremely rarely detected during heat wave and non-heat wave days, respectively.

  4. Study of heat-stress levels in naturally ventilated sheep barns during heat waves: development and assessment of regression models.

    PubMed

    Papanastasiou, D K; Bartzanas, T; Panagakis, P; Zhang, G; Kittas, C

    2016-11-01

    It is well documented that heat-stress burdens sheep welfare and productivity. Peak heat-stress levels are observed when high temperatures prevail, i.e. during heat waves; however, continuous measurements inside livestock buildings are not usually available for long periods so as to study the variation of summer heat-stress levels for several years, especially during extreme hot weather. Α methodology to develop a long time series of summer temperature and relative humidity inside naturally ventilated sheep barns is proposed. The accuracy and the transferability of the developed linear regression models were verified. Temperature Humidity Index (THI) was used to assess sheep's potential heat-stress. Τhe variation of THI inside a barn during heat wave and non-heat wave days was examined, and the results were comparatively assessed. The analysis showed that sheep were exposed to moderate, severe, and extreme severe heat-stress in 10, 21 and 66 % of hours, respectively, during heat wave days, while the corresponding values during non-heat wave days were 14, 33 and 43 %, respectively. The heat load on sheep was much higher during heat wave events than during non-heat wave periods. Additionally, based on the averaged diurnal variation of THI, it was concluded that extreme severe heat-stress conditions were prevailing between 1000 and 2400 hours local time during heat wave days. Cool off night periods were never and extremely rarely detected during heat wave and non-heat wave days, respectively.

  5. An assessment of heat stress in the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Rasilla Álvarez, D.; Fernandez García, F.

    2010-09-01

    of heat extremes (PET > 35 °C) was compared with the occurrence of several circulation patterns, in other to validate the circulation pattern catalogue and obtain a regional signal. In order to gain a comprehensive understanding of the sources and thermodynamic characteristics of the air masses involved in those events, the atmospheric circulation prior selected episodes of heat stress was analyzed using a sequential classification procedure (up to three days) and compared with the backward trajectories supplied by the HYSPLIT model (Hybrid Single-Particle Lagrangian Integrated Trajectory model; http://ready.arl.noaa.gov/HYSPLIT.php). The dependence of the PET on some geographical controls (e.g. topography, latitude, distance to sea) results on marked variation between the values calculated for different stations. Low/middle-altitude continental stations (eg. Madrid, Seville) show much higher thermal stress than coastal stations (Barcelona, Málaga) or stations in elevated areas (e.g. Burgos, Navacerrada). Besides, coastal stations display an asymmetric monthly distribution, with larger probability in August, while July is the most typical month in the interior of Iberia. 5 regions resulted from the analysis of daily PET fields: Northern, Atlantic North, Atlantic South, Mediterranean North and Mediterranean South. The extreme heat events occurrence on each region showed strong links with the atmospheric circulation, but two basic mechanisms are involved in most of them. Coastal stations experience such events when the regional atmospheric circulation overrules local circulations, replacing the cooler and moist air masses by continental downslope flows. In continental Iberia the advection of hot air masses from a diverse precedence and embedded into a weak atmospheric circulation (radiative processes) trigger most of the situations of heat stress.

  6. Occupational heat stress assessment and protective strategies in the context of climate change

    NASA Astrophysics Data System (ADS)

    Gao, Chuansi; Kuklane, Kalev; Östergren, Per-Olof; Kjellstrom, Tord

    2017-04-01

    Global warming will unquestionably increase the impact of heat on individuals who work in already hot workplaces in hot climate areas. The increasing prevalence of this environmental health risk requires the improvement of assessment methods linked to meteorological data. Such new methods will help to reveal the size of the problem and design appropriate interventions at individual, workplace and societal level. The evaluation of occupational heat stress requires measurement of four thermal climate factors (air temperature, humidity, air velocity and heat radiation); available weather station data may serve this purpose. However, the use of meteorological data for occupational heat stress assessment is limited because weather stations do not traditionally and directly measure some important climate factors, e.g. solar radiation. In addition, local workplace environmental conditions such as local heat sources, metabolic heat production within the human body, and clothing properties, all affect the exchange of heat between the body and the environment. A robust occupational heat stress index should properly address all these factors. This article reviews and highlights a number of selected heat stress indices, indicating their advantages and disadvantages in relation to meteorological data, local workplace environments, body heat production and the use of protective clothing. These heat stress and heat strain indices include Wet Bulb Globe Temperature, Discomfort Index, Predicted Heat Strain index, and Universal Thermal Climate Index. In some cases, individuals may be monitored for heat strain through physiological measurements and medical supervision prior to and during exposure. Relevant protective and preventive strategies for alleviating heat strain are also reviewed and proposed.

  7. Comparison of Temperature Indexes for the Impact Assessment of Heat Stress on Heat-Related Mortality

    PubMed Central

    Kim, Young-Min; Cheong, Hae-Kwan; Kim, Eun-Hye

    2011-01-01

    Objectives In order to evaluate which temperature index is the best predictor for the health impact assessment of heat stress in Korea, several indexes were compared. Methods We adopted temperature, perceived temperature (PT), and apparent temperature (AT), as a heat stress index, and changes in the risk of death for Seoul and Daegu were estimated with 1℃ increases in those temperature indexes using generalized additive model (GAM) adjusted for the non-temperature related factors: time trends, seasonality, and air pollution. The estimated excess mortality and Akaike's Information Criterion (AIC) due to the increased temperature indexes for the 75th percentile in the summers from 2001 to 2008 were compared and analyzed to define the best predictor. Results For Seoul, all-cause mortality presented the highest percent increase (2.99% [95% CI, 2.43 to 3.54%]) in maximum temperature while AIC showed the lowest value when the all-cause daily death counts were fitted with the maximum PT for the 75th percentile of summer. For Daegu, all-cause mortality presented the greatest percent increase (3.52% [95% CI, 2.23 to 4.80%]) in minimum temperature and AIC showed the lowest value in maximum temperature. No lag effect was found in the association between temperature and mortality for Seoul, whereas for Daegu one-day lag effect was noted. Conclusions There was no one temperature measure that was superior to the others in summer. To adopt an appropriate temperature index, regional meteorological characteristics and the disease status of population should be considered. PMID:22125770

  8. Heat Stress

    MedlinePlus

    ... Work in the Heat: Why Acclimatization Matters The natural adaptation to the heat takes time, and from a management perspective, it may require careful planning. NIOSH Science Blog: Extreme Heat – Are you prepared for summer ...

  9. Scenario-neutral Food Security Risk Assessment: A livestock Heat Stress Case Study

    NASA Astrophysics Data System (ADS)

    Broman, D.; Rajagopalan, B.; Hopson, T. M.

    2015-12-01

    Food security risk assessments can provide decision-makers with actionable information to identify critical system limitations, and alternatives to mitigate the impacts of future conditions. The majority of current risk assessments have been scenario-led and results are limited by the scenarios - selected future states of the world's climate system and socioeconomic factors. A generic scenario-neutral framework for food security risk assessments is presented here that uses plausible states of the world without initially assigning likelihoods. Measures of system vulnerabilities are identified and system risk is assessed for these states. This framework has benefited greatly by research in the water and natural resource fields to adapt their planning to provide better risk assessments. To illustrate the utility of this framework we develop a case study using livestock heat stress risk within the pastoral system of West Africa. Heat stress can have a major impact not only on livestock owners, but on the greater food production system, decreasing livestock growth, milk production, and reproduction, and in severe cases, death. A heat stress index calculated from daily weather is used as a vulnerability measure and is computed from historic daily weather data at several locations in the study region. To generate plausible states, a stochastic weather generator is developed to generate synthetic weather sequences at each location, consistent with the seasonal climate. A spatial model of monthly and seasonal heat stress provide projections of current and future livestock heat stress measures across the study region, and can incorporate in seasonal climate and other external covariates. These models, when linked with empirical thresholds of heat stress risk for specific breeds offer decision-makers with actionable information for use in near-term warning systems as well as for future planning. Future assessment can indicate under which states livestock are at greatest risk

  10. Assessment of male anthropometric trends and the effects on simulated heat stress responses.

    PubMed

    Yokota, Miyo; Bathalon, Gaston P; Berglund, Larry G

    2008-09-01

    Assessing temporal changes in anthropometrics and body composition of US Army soldiers is important because these changes may affect fitness, performance, and safety. This study investigated differences in body dimensions (height, weight, percent body fat (%BF)) of US Army male soldiers by comparing 2004 and 1988 databases. Anthropometric somatotypes were identified and physiological responses of the different somatotypes to simulated heat stress (35 degrees C/50%rh, approximately 550 W work rate, carrying 12 kg load including battle dress uniform and body armor, rest for 30 min and walk for 70 min) using a thermal regulatory model were evaluated. A significant increase in body weight (2.4 kg) was observed between the 2004 and 1988 data (P < 0.05, after Bonferroni correction). However, changes in height and circumference measurements for %BF were insignificant, with the magnitude of the changes not exceeding inter-observer errors. Multivariate analyses demonstrated that anthropometric distributions did not differ between the two databases and identified five primary somatotypes: "tall-fat", "tall-lean", "average", "short-lean", and "short-fat." Within each database, anthropometric values differed among the somatotypes. However, simulated physiological responses to heat stress in each somatotype were similar in the 2004 and 1988 populations. In conclusion, an increase in body weight was the primary change observed in this sample of US Army male soldiers. Temporal changes in somatotypes of soldiers over a 16-year period had minimal impact on simulated physiological response to heat stress using a thermal regulatory model.

  11. Estimated work ability in warm outdoor environments depends on the chosen heat stress assessment metric

    NASA Astrophysics Data System (ADS)

    Bröde, Peter; Fiala, Dusan; Lemke, Bruno; Kjellstrom, Tord

    2017-04-01

    With a view to occupational effects of climate change, we performed a simulation study on the influence of different heat stress assessment metrics on estimated workability (WA) of labour in warm outdoor environments. Whole-day shifts with varying workloads were simulated using as input meteorological records for the hottest month from four cities with prevailing hot (Dallas, New Delhi) or warm-humid conditions (Managua, Osaka), respectively. In addition, we considered the effects of adaptive strategies like shielding against solar radiation and different work-rest schedules assuming an acclimated person wearing light work clothes (0.6 clo). We assessed WA according to Wet Bulb Globe Temperature (WBGT) by means of an empirical relation of worker performance from field studies (Hothaps), and as allowed work hours using safety threshold limits proposed by the corresponding standards. Using the physiological models Predicted Heat Strain (PHS) and Universal Thermal Climate Index (UTCI)-Fiala, we calculated WA as the percentage of working hours with body core temperature and cumulated sweat loss below standard limits (38 °C and 7.5% of body weight, respectively) recommended by ISO 7933 and below conservative (38 °C; 3%) and liberal (38.2 °C; 7.5%) limits in comparison. ANOVA results showed that the different metrics, workload, time of day and climate type determined the largest part of WA variance. WBGT-based metrics were highly correlated and indicated slightly more constrained WA for moderate workload, but were less restrictive with high workload and for afternoon work hours compared to PHS and UTCI-Fiala. Though PHS showed unrealistic dynamic responses to rest from work compared to UTCI-Fiala, differences in WA assessed by the physiological models largely depended on the applied limit criteria. In conclusion, our study showed that the choice of the heat stress assessment metric impacts notably on the estimated WA. Whereas PHS and UTCI-Fiala can account for

  12. Estimated work ability in warm outdoor environments depends on the chosen heat stress assessment metric.

    PubMed

    Bröde, Peter; Fiala, Dusan; Lemke, Bruno; Kjellstrom, Tord

    2017-04-19

    With a view to occupational effects of climate change, we performed a simulation study on the influence of different heat stress assessment metrics on estimated workability (WA) of labour in warm outdoor environments. Whole-day shifts with varying workloads were simulated using as input meteorological records for the hottest month from four cities with prevailing hot (Dallas, New Delhi) or warm-humid conditions (Managua, Osaka), respectively. In addition, we considered the effects of adaptive strategies like shielding against solar radiation and different work-rest schedules assuming an acclimated person wearing light work clothes (0.6 clo). We assessed WA according to Wet Bulb Globe Temperature (WBGT) by means of an empirical relation of worker performance from field studies (Hothaps), and as allowed work hours using safety threshold limits proposed by the corresponding standards. Using the physiological models Predicted Heat Strain (PHS) and Universal Thermal Climate Index (UTCI)-Fiala, we calculated WA as the percentage of working hours with body core temperature and cumulated sweat loss below standard limits (38 °C and 7.5% of body weight, respectively) recommended by ISO 7933 and below conservative (38 °C; 3%) and liberal (38.2 °C; 7.5%) limits in comparison. ANOVA results showed that the different metrics, workload, time of day and climate type determined the largest part of WA variance. WBGT-based metrics were highly correlated and indicated slightly more constrained WA for moderate workload, but were less restrictive with high workload and for afternoon work hours compared to PHS and UTCI-Fiala. Though PHS showed unrealistic dynamic responses to rest from work compared to UTCI-Fiala, differences in WA assessed by the physiological models largely depended on the applied limit criteria. In conclusion, our study showed that the choice of the heat stress assessment metric impacts notably on the estimated WA. Whereas PHS and UTCI-Fiala can account for

  13. Comparison of heat and cold stress to assess thermoregulatory dysfunction in hypothyroid rats.

    PubMed

    Gordon, C J; Becker, P; Padnos, B

    2000-12-01

    How borderline impairment of thyroid function can affect thermoregulation is an important issue because of the antithyroidal properties of a many environmental toxicants. This study compared the efficacy of heat and cold stress to identify thermoregulatory deficits in rats subjected to borderline and overt hypothyroidism via subchronic exposure to propylthiouracil (PTU). After 3 wk of exposure to PTU in the drinking water (0, 2.5, 5, 10, and 25 mg/l), rats were subjected to a heat stress challenge (34 degrees C for 2.5 h). After one more week of PTU treatment, the same rats were subjected to a cold stress challenge (7 degrees C for 2.5 h). Core temperature (T(c)) was monitored by radiotelemetry. Baseline T(c) during the light phase was reduced by treatment with 25 mg/l PTU. The rate of rise and overall increase in T(c) during heat stress was attenuated by PTU doses of 10 and 25 mg/l. Cold stress resulted in a 1.0 degrees C increase in T(c) regardless of PTU treatment. The rate of rise in T(c) during the cold stress challenge was similar in all PTU treatment groups. There was a dose-related decrease in serum thyroxine (T(4)) at PTU doses >/=5 mg/l. Serum triiodothyronine (T(3)) was reduced at PTU doses of 5 and 25 mg/l. Serum thyroid-stimulating hormone (TSH) was marginally elevated by PTU treatment. Overall, heat stress was more effective than cold stress for detecting a thermoregulatory deficit in borderline (i.e., 10 mg/l PTU) and overtly hypothyroid rats (i.e., 25 mg/l PTU). A significant thermoregulatory deficit is manifested with a 78% decrease in serum T(4). A thermoregulatory deficit is more correlated with a reduction in serum T(4) compared with T(3). Serum levels of TSH are unrelated to thermoregulatory response to heat and cold stress.

  14. Stress and heat flow

    SciTech Connect

    Lachenbrunch, A.H.; McGarr, A.

    1990-01-01

    As the Pacific plate slides northward past the North American plate along the San Andreas fault, the frictional stress that resists plate motion there is overcome to cause earthquakes. However, the frictional heating predicted for the process has never been detected. Thus, in spite of its importance to an understanding of both plate motion and earthquakes, the size of this frictional stress is still uncertain, even in order of magnitude.

  15. Assessing the Heat Stress and Establishing the Limits for Work in a Hot Mine

    PubMed Central

    Wyndham, C. H.; Allan, A. McD.; Bredell, G. A. G.; Andrew, R.

    1967-01-01

    The management of the mine at Mount Isa, Queensland, Australia decided to enquire into the following questions with regard to men working underground in hot conditions: (a) Which of the various heat stress indices predicts most accurately the effects on workmen of the various heat stress factors which occur in the mine at Mount Isa? (b) How best should the limits of heat stress be judged at which the normal 8-hour shift should be reduced to a 6-hour shift, or at which work should be stopped? With these objects in mind, oral temperatures were measured on 86 workmen after three hours of ordinary work in the mine and also on 36 occasions on 29 volunteers after three hours of stepping on and off a stool at a work rate of 1,560 ft. lb./min. These men were studied in different environmental heat stresses over the range that occurs in the mine. Dry bulb air temperatures (D.B.), wet bulb temperatures (W.B.), velocity of air movements, and globe temperatures (G.T.) were measured in the micro-climate in which each man worked. An estimate was made of the work rate of the 86 workmen. From these estimates and measurements, the predicted 4-hourly sweat rate (P4SR) and corrected effective temperature (C.E.T.) values were determined for each heat stress condition. P4SR values varied between 0·9 and 6·5 and C.E.T. between 70° and 95°F. Correlation coefficients were calculated between oral temperatures and W.B.s, C.E.T.s, and P4SRs and are 0·51, 0·64, and 0·75 respectively. Further analysis was confined to C.E.T. and P4SR. Plots of oral temperature on P4SR for conditions where G.T. was more than 10°F. above D.B. were found to fall well below the rest of the plots, indicating that P4SR exaggerates the effect of mean radiant temperature. These data were therefore excluded from the rest of the analysis. Regression equations were calculated for oral temperature on P4SR and for oral temperature on C.E.T. for (a) men `on the job', for (i) conditions where D.B. was more than 10

  16. Applicability of Universal Thermal Climate Index (UTCI) in occupational heat stress assessment: a case study in brick industries

    PubMed Central

    VATANI, Javad; GOLBABAEI, Farideh; DEHGHAN, Somayeh Farhang; YOUSEFI, Azam

    2015-01-01

    The present study aimed to investigate the applicability of Universal Thermal Climate Index (UTCI) as an innovative and science-based index in public health researches, in occupational heat stress assessment. All indoor and outdoor workers (200 people) of Brick industries of Shahroud, Iran participated in the research. First, the environmental variables such as air temperature, wet-bulb temperature, globe temperature, air velocity and relative humidity were measured; then UTCI and WBGT (wet-bulb globe temperature) indices were calculated. Simultaneously, physiological parameters including systolic and diastolic blood pressure, oral temperature, skin temperature, tympanic temperature and heart rate of workers were measured. UTCI and WBGT indices were 34.2 ± 2°C, 21.8 ± 1.8°C in the outdoor environments and 38.1 ± 4.4°C, 24.7 ± 3.3°C at the indoor environments, respectively. There were the weak inverse relationships between UTCI and WBGT indices at the outdoor environments and physiological responses such as systolic blood pressure, and diastolic blood pressure. However, there were no similar results for indoor environments. The significant relationships were found between UTCI and WBGT at both indoor and outdoor environments. Both UTCI and WBGT indices are suitable for assessing the occupational heat stress. Although, UTCI index seems more appropriate for heat stress assessment in the environments with low humidity and air velocity. PMID:26320731

  17. Applicability of Universal Thermal Climate Index (UTCI) in occupational heat stress assessment: a case study in brick industries.

    PubMed

    Vatani, Javad; Golbabaei, Farideh; Dehghan, Somayeh Farhang; Yousefi, Azam

    2016-01-01

    The present study aimed to investigate the applicability of Universal Thermal Climate Index (UTCI) as an innovative and science-based index in public health researches, in occupational heat stress assessment. All indoor and outdoor workers (200 people) of Brick industries of Shahroud, Iran participated in the research. First, the environmental variables such as air temperature, wet-bulb temperature, globe temperature, air velocity and relative humidity were measured; then UTCI and WBGT (wet-bulb globe temperature) indices were calculated. Simultaneously, physiological parameters including systolic and diastolic blood pressure, oral temperature, skin temperature, tympanic temperature and heart rate of workers were measured. UTCI and WBGT indices were 34.2 ± 2°C, 21.8 ± 1.8°C in the outdoor environments and 38.1 ± 4.4°C, 24.7 ± 3.3°C at the indoor environments, respectively. There were the weak inverse relationships between UTCI and WBGT indices at the outdoor environments and physiological responses such as systolic blood pressure, and diastolic blood pressure. However, there were no similar results for indoor environments. The significant relationships were found between UTCI and WBGT at both indoor and outdoor environments. Both UTCI and WBGT indices are suitable for assessing the occupational heat stress. Although, UTCI index seems more appropriate for heat stress assessment in the environments with low humidity and air velocity.

  18. Occupational health impacts of climate change: current and future ISO standards for the assessment of heat stress.

    PubMed

    Parsons, Ken

    2013-01-01

    The current system of International Standards (ISO) is assessed to consider whether standards are fit for purpose for the future in the context of climate change. ISO 7243, ISO 7933 and ISO 9886 provide the current ISO system for the assessment of heat stress. These involve a simple monitoring index, an analytical approach and physiological monitoring, respectively. The system relies on accurate measurement of the thermal conditions experienced by the worker (ISO 7726); and estimations of metabolic heat production due to work (ISO 8996) and the thermal properties of clothing (ISO 9920). As well as standards for heat stress assessment, the full range of ISO standards and the physical environment is listed as well as current work and proposed standards. A particular 'gap' in anticipating requirements for ISO standards in the future is the link between meteorological data and ISO standards. This is important for predicting the global consequences of a changing climate and anticipating potential impacts on occupational health across countries and cultures.

  19. Heat Stress Monitor

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The heavy, cumbersome body protection suits worn by members of hazardous materials response teams cause marked elevation of body temperatures, which can reduce effectiveness and lead to heat stress and injury. The CorTemp System, marketed by Human Technologies, Inc., provides the basis for a body temperature monitoring alarm system. Encased in a three-quarter-inch ingestible capsule, the system includes a mini-thermometer, miniature telemetry system, a microbattery and temperature sensor. It makes its way through the digestive system, continuously monitoring temperature. Findings are sent to the recorder by telemetry, and then displayed and stored for transfer to a computer.

  20. Application of Universal Thermal Climate Index (UTCI) for assessment of occupational heat stress in open-pit mines.

    PubMed

    Nassiri, Parvin; Monazzam, Mohammad Reza; Golbabaei, Farideh; Dehghan, Somayeh Farhang; Rafieepour, Athena; Mortezapour, Ali Reza; Asghari, Mehdi

    2017-10-07

    The purpose of this article is to examine the applicability of Universal Thermal Climate Index (UTCI) index as an innovative index for evaluating of occupational heat stress in outdoor environments. 175 workers of 12 open-pit mines in Tehran, Iran were selected for this research study. First, the environmental variables such as air temperature, wet-bulb temperature, globe temperature, relative humidity and air flow rate were measured; then UTCI, wet-bulb globe temperature (WBGT) and heat stress index (HSI) indices were calculated. Simultaneously, physiological parameters including heart rate, oral temperature, tympanic temperature and skin temperature of workers were measured. UTCI and WBGT are positively significantly correlated with all environmental parameters (p<0.03), except for air velocity (r<-0.39; p>0.05). Moreover, a strong significant relationship was found between UTCI and WBGT (r=0.95; p<0.001). The significant positive correlations exist between physiological parameters including oral temperature, tympanic and skin temperatures and heart rate and both the UTCI and WBGT indices (p<0.029). The highest correlation coefficient has been found between the UTCI and physiological parameters. Due to the low humidity and air velocity (~<1 m/s) in understudied mines, UTCI index appears to be appropriate to assess the occupational heat stress in these outdoor workplaces.

  1. Protecting Workers from Heat Stress

    MedlinePlus

    ... temperatures are high and the job involves physical work. Risk Factors for Heat Illness • High temperature and humidity, ... heat or those that have been away from work to adapt to working in the heat (acclimatization). • Routinely check workers who are at risk of heat stress due to protective clothing and ...

  2. In vitro Assessment of Hg Toxicity in Hepatocytes from Heat-Stressed Atlantic Salmon.

    PubMed

    Olsvik, Pål A; Waagbø, Rune; Hevrøy, Ernst M; Remø, Sofie C; Søfteland, Liv

    2016-11-01

    Global warming may alter the bioavailability of contaminants in aquatic environments. In this work, mercury (Hg(2+)) toxicity was studied in cells obtained from Atlantic salmon smolt kept at 15 °C (optimal growth temperature) for 3 months or at a stepwise increase to 20 °C (temperature-stress) during 3 months prior to cell harvest to evaluate whether acclimation temperature affects Hg toxicity. To examine possible altered dietary requirements in warmer seas, one group of fish following the stepwise temperature regimes was fed a diet spiked with antioxidants. Atlantic salmon hepatocytes were exposed in vitro to 0, 1.0, or 100 μM Hg(2+) for 48 h. Cytotoxicity, determined as electrical impedance changes with the xCELLigence system, and transcriptional responses, determined with RT-qPCR, were assessed as measures of toxicity. The results showed that inorganic Hg at a concentration up to 100 μM is not cytotoxic to Atlantic salmon hepatocytes. Significance and directional responses of the 18 evaluated target genes suggest that both Hg and temperature stress affected the transcription of genes encoding proteins involved in the protection against ROS-generated oxidative stress. Both stressors also affected the transcription of genes linked to lipid metabolism. Spiking the diet with antioxidants resulted in higher concentrations of Se and vitamin C and reduced concentration of Hg in the liver in vivo, but no interactions were seen between the dietary supplementation of antioxidants and Hg toxicity in vitro. In conclusion, no evidence was found suggesting that inorganic Hg is more toxic in cells harvested from temperature-stressed fish.

  3. Assessing risks from drought and heat stress in productive grasslands under present and future climatic conditions

    NASA Astrophysics Data System (ADS)

    Calanca, Pierluigi; Mosimann, Eric; Meisser, Marco; Deléglise, Claire

    2014-05-01

    Grasslands cover the majority of the world's agricultural area, provide the feedstock for animal production, contribute to the economy of farms, and deliver a variety of ecological and societal services. Assessing responses of grassland ecosystems to climate change, in particular climate-related risks, is therefore an important step toward identifying adaptation options necessary to secure grassland functioning and productivity. Of particular concern are risks in relation to drought and extreme temperatures, on the one hand because grasslands are very sensitive to water stress, on the other hand also because global warming is expected to increase the occurrence and intensity of these events in many agricultural areas of the world. In this contribution we review findings of ongoing experimental and modelling activities that aim at examining the implications of climate extremes and climate change for grassland vegetation dynamics and herbage productivity. Data collected at the Jura foot in western Switzerland indicate that water scarcity and associated anomalous temperatures slowed plant development in relation to both the summer drought of 2003 as well as the spring drought of 2011, with decline in annual yields of up to 40%. Further effects of drought found from the analysis of recent field trials explicitly designed to study the effects of different water management regimes are changes in the functional composition and nutritive value of grasslands. Similar responses are disclosed by simulations with a process based grassland ecosystem model that was originally developed for the simulation of mixed grass/clover swards. Simulations driven with historical weather records from the Swiss Plateau suggest that drought and extreme temperature could represent one of the main reasons for the observed yield variability in productive systems. Simulations with climate change scenarios further reveal important changes in ecosystem dynamics for the current century. The results

  4. Assessment of indoor heat stress variability in summer and during heat warnings: a case study using the UTCI in Berlin, Germany.

    PubMed

    Walikewitz, Nadine; Jänicke, Britta; Langner, Marcel; Endlicher, Wilfried

    2015-09-30

    Humans spend most of their time in confined spaces and are hence primarily exposed to the direct influence of indoor climate. The Universal Thermal Climate Index (UTCI) was obtained in 31 rooms (eight buildings) in Berlin, Germany, during summer 2013 and 2014. The indoor UTCI was determined from measurements of both air temperature and relative humidity and from data of mean radiant temperature and air velocity, which were either measured or modeled. The associated outdoor UTCI was obtained through facade measurements of air temperature and relative humidity, simulation of mean radiant temperature, and wind data from a central weather station. The results show that all rooms experienced heat stress according to UTCI levels, especially during heat waves. Indoor UTCI varied up to 6.6 K within the city and up to 7 K within building. Heat stress either during day or at night occurred on 35 % of all days. By comparing the day and night thermal loads, we identified maximum values above the 32 °C threshold for strong heat stress during the nighttime. Outdoor UTCI based on facade measurements provided no better explanation of indoor UTCI variability than the central weather station. In contrast, we found a stronger relationship of outdoor air temperature and indoor air temperature. Building characteristics, such as the floor level or window area, influenced indoor heat stress ambiguously. We conclude that indoor heat stress is a major hazard, and more effort toward understanding the causes and creating effective countermeasures is needed.

  5. Improved Heat-Stress Algorithm

    NASA Technical Reports Server (NTRS)

    Teets, Edward H., Jr.; Fehn, Steven

    2007-01-01

    NASA Dryden presents an improved and automated site-specific algorithm for heat-stress approximation using standard atmospheric measurements routinely obtained from the Edwards Air Force Base weather detachment. Heat stress, which is the net heat load a worker may be exposed to, is officially measured using a thermal-environment monitoring system to calculate the wet-bulb globe temperature (WBGT). This instrument uses three independent thermometers to measure wet-bulb, dry-bulb, and the black-globe temperatures. By using these improvements, a more realistic WBGT estimation value can now be produced. This is extremely useful for researchers and other employees who are working on outdoor projects that are distant from the areas that the Web system monitors. Most importantly, the improved WBGT estimations will make outdoor work sites safer by reducing the likelihood of heat stress.

  6. Heat-stressed Metarhizium anisopliae: viability (in vitro) and virulence (in vivo) assessments against the tick Rhipicephalus sanguineus.

    PubMed

    Alves, Fabrício M; Bernardo, Cíntia C; Paixão, Flávia R S; Barreto, Lucas P; Luz, Christian; Humber, Richard A; Fernandes, Éverton K K

    2017-01-01

    The current study investigated the thermotolerance of Metarhizium anisopliae s.l. conidia from the commercial products Metarril® SP Organic and Metarril® WP. The efficacy of these M. anisopliae formulations against the tick Rhipicephalus sanguineus s.l. was studied in laboratory under optimum or heat-stress conditions. The products were prepared in water [Tween® 80, 0.01 % (v/v)] or pure mineral oil. Conidia from Metarril® SP Organic suspended in water presented markedly delayed germination after heating to constant 40 °C (for 2, 4, or 6 h) compared to conidia suspended in mineral oil. Metarril® SP Organic suspended in oil and exposed to daily cycles of heat-stress (40 °C for 4 h and 25 °C for 19 h for 5 consecutive days) presented relative germination of conidia ranging from 92.8 to 87.2 % from day 1 to day 5, respectively. Conversely, germination of conidia prepared in water ranged from 79.3 to 39.1 % from day 1 to day 5, respectively. Culturability of Metarril® WP decreased from 96 % when conidia were cultured for 30 min prior to heat exposure (40 °C for 4 h) to 9 % when conidia were cultured for 8 h. Tick percent control was distinctly higher when engorged females were treated with oil suspensions rather than water suspensions, even when treated ticks were exposed to heat-stress regimen. Oil-based applications protected fungal conidia against heat-stress. Although Metarril® is not registered for tick control, it may be useful for controlling R. sanguineus, especially if it is prepared in mineral oil.

  7. Investigation of Urban Heat Stress from Satellite Atmospheric Profiles

    NASA Astrophysics Data System (ADS)

    Hu, L.; Brunsell, N. A.

    2014-12-01

    Heat stress is the leading cause of weather-related human mortality in the United States and in many countries world-wide. Heat stress is usually enhanced by the urban heat island effect. Here, we investigate the ability to use remotely sensed atmospheric profiles to detect and monitor heat stress in the urban environment. MODIS atmospheric profiles at 5 km are used to quantify the spatial distribution of heat stress across Chicago during summer periods from 2003-2013. Four heat stress indices are investigated (Discomfort Index (DI), NWS Heat Index (HI), Humidex, and Simplified Wet Bulb Globe Temperature (SWBGT)) from the near-surface temperature and humidity observed at ground sites and retrieved from satellite atmospheric profiles. The heat stress climatology indicates that the urban effects are similar to the heat stress in top 5% hot days and 11 summers during the daytime. There is a lack of relationship between urban fraction and the heat stress on the warmest nights. The nighttime heat stress in the hottest 5% suggests a larger stress compared to the normal conditions during 11 summers. A case study of the heat wave in 2012 is assessed to identify the key pre-heat wave spatial patterns, which may potentially apply to predict future high heat-stress events. In addition, the role of the temporal persistence on the spatial dynamics of the heat wave is also examined. This research illustrates the spatial heat pattern under normal and heat wave conditions, which may help to make public heat health protection strategies. Also, the remotely sensed temperature and humidity information are invaluable to assess urban heat island impact spatially and temporally.

  8. Occupational heat stress in Australian workplaces

    PubMed Central

    Jay, Ollie; Brotherhood, John R.

    2016-01-01

    ABSTRACT The aim of this review was to summarize the current state of knowledge on heat stress risk within typical Australian occupational settings. We assessed identified occupations (mining, agriculture, construction, emergency services) for heat production and heat loss potential, and resultant levels of physiological heat strain. A total of 29 reports were identified that assessed in-situ work settings in Northern Territory, South Australia, Western Australia, Queensland, New South Wales and Victoria, that measured physiological responses and characterized the thermal environment. Despite workers across all industries being regularly exposed to high ambient temperatures (32–42°C) often coupled with high absolute humidity (max: 33 hPa), physiological strain is generally low in terms of core temperature (<38°C) and dehydration (<1 % reduction in mass) by virtue of the low energy demands of many tasks, and self-regulated pacing of work possible in most jobs. Heat stress risk is higher in specific jobs in agriculture (e.g. sheep shearing), deep underground mining, and emergency services (e.g., search/rescue and bushfire fighting). Heat strain was greatest in military-related activities, particularly externally-paced marching with carried loads which resulted in core temperatures often exceeding 39.5°C despite being carried out in cooler environments. The principal driver of core temperature elevations in most jobs is the rate of metabolic heat production. A standardized approach to evaluating the risk of occupational heat strain in Australian workplaces is recommended defining the individual parameters that alter human heat balance. Future research should also more closely examine female workers and occupational activities within the forestry and agriculture/horticulture sector. PMID:28349081

  9. Occupational heat stress in Australian workplaces.

    PubMed

    Jay, Ollie; Brotherhood, John R

    2016-01-01

    The aim of this review was to summarize the current state of knowledge on heat stress risk within typical Australian occupational settings. We assessed identified occupations (mining, agriculture, construction, emergency services) for heat production and heat loss potential, and resultant levels of physiological heat strain. A total of 29 reports were identified that assessed in-situ work settings in Northern Territory, South Australia, Western Australia, Queensland, New South Wales and Victoria, that measured physiological responses and characterized the thermal environment. Despite workers across all industries being regularly exposed to high ambient temperatures (32-42°C) often coupled with high absolute humidity (max: 33 hPa), physiological strain is generally low in terms of core temperature (<38°C) and dehydration (<1 % reduction in mass) by virtue of the low energy demands of many tasks, and self-regulated pacing of work possible in most jobs. Heat stress risk is higher in specific jobs in agriculture (e.g. sheep shearing), deep underground mining, and emergency services (e.g., search/rescue and bushfire fighting). Heat strain was greatest in military-related activities, particularly externally-paced marching with carried loads which resulted in core temperatures often exceeding 39.5°C despite being carried out in cooler environments. The principal driver of core temperature elevations in most jobs is the rate of metabolic heat production. A standardized approach to evaluating the risk of occupational heat strain in Australian workplaces is recommended defining the individual parameters that alter human heat balance. Future research should also more closely examine female workers and occupational activities within the forestry and agriculture/horticulture sector.

  10. Effects of heat stress on baroreflex function in humans

    NASA Technical Reports Server (NTRS)

    Crandall, Craig G.; Cui, Jian; Wilson, Thad E.

    2003-01-01

    INTRODUCTION: Heat stress significantly reduces orthostatic tolerance in humans. The mechanism(s) causing this response remain unknown. The purpose of this review article is to present data pertaining to the hypothesis that reduced orthostatic tolerance in heat stressed individuals is a result of heat stress induced alterations in baroflex function. METHODS: In both normothermic and heat stressed conditions baroreflex responsiveness was assessed via pharmacological and non-pharmacological methods. In addition, the effects of heat stress on post-synaptic vasoconstrictor responsiveness were assessed. RESULTS: Generally, whole body heating did not alter baroreflex sensitivity defined as the gain of the linear portion of the baroreflex curve around the operating point. However, whole body heating shifted the baroreflex curve to the prevailing (i.e. elevated) heart rate and muscle sympathetic nerve activity. Finally, the heat stress impaired vasoconstrictor responses to exogenous administration of adrenergic agonists. CONCLUSION: Current data do not support the hypothesis that reduced orthostatic tolerance associated with heat stress in humans is due to impaired baroreflex responsiveness. This phenomenon may be partially due to the effects of heat stress on reducing vasoconstrictor responsiveness.

  11. Effects of heat stress on baroreflex function in humans

    NASA Technical Reports Server (NTRS)

    Crandall, Craig G.; Cui, Jian; Wilson, Thad E.

    2003-01-01

    INTRODUCTION: Heat stress significantly reduces orthostatic tolerance in humans. The mechanism(s) causing this response remain unknown. The purpose of this review article is to present data pertaining to the hypothesis that reduced orthostatic tolerance in heat stressed individuals is a result of heat stress induced alterations in baroflex function. METHODS: In both normothermic and heat stressed conditions baroreflex responsiveness was assessed via pharmacological and non-pharmacological methods. In addition, the effects of heat stress on post-synaptic vasoconstrictor responsiveness were assessed. RESULTS: Generally, whole body heating did not alter baroreflex sensitivity defined as the gain of the linear portion of the baroreflex curve around the operating point. However, whole body heating shifted the baroreflex curve to the prevailing (i.e. elevated) heart rate and muscle sympathetic nerve activity. Finally, the heat stress impaired vasoconstrictor responses to exogenous administration of adrenergic agonists. CONCLUSION: Current data do not support the hypothesis that reduced orthostatic tolerance associated with heat stress in humans is due to impaired baroreflex responsiveness. This phenomenon may be partially due to the effects of heat stress on reducing vasoconstrictor responsiveness.

  12. Effects of heat stress on mammalian reproduction

    PubMed Central

    Hansen, Peter J.

    2009-01-01

    Heat stress can have large effects on most aspects of reproductive function in mammals. These include disruptions in spermatogenesis and oocyte development, oocyte maturation, early embryonic development, foetal and placental growth and lactation. These deleterious effects of heat stress are the result of either the hyperthermia associated with heat stress or the physiological adjustments made by the heat-stressed animal to regulate body temperature. Many effects of elevated temperature on gametes and the early embryo involve increased production of reactive oxygen species. Genetic adaptation to heat stress is possible both with respect to regulation of body temperature and cellular resistance to elevated temperature. PMID:19833646

  13. Re-evaluating Occupational Heat Stress in a Changing Climate

    PubMed Central

    Spector, June T.; Sheffield, Perry E.

    2014-01-01

    The potential consequences of occupational heat stress in a changing climate on workers, workplaces, and global economies are substantial. Occupational heat stress risk is projected to become particularly high in middle- and low-income tropical and subtropical regions, where optimal controls may not be readily available. This commentary presents occupational heat stress in the context of climate change, reviews its impacts, and reflects on implications for heat stress assessment and control. Future efforts should address limitations of existing heat stress assessment methods and generate economical, practical, and universal approaches that can incorporate data of varying levels of detail, depending on resources. Validation of these methods should be performed in a wider variety of environments, and data should be collected and analyzed centrally for both local and large-scale hazard assessments and to guide heat stress adaptation planning. Heat stress standards should take into account variability in worker acclimatization, other vulnerabilities, and workplace resources. The effectiveness of controls that are feasible and acceptable should be evaluated. Exposure scientists are needed, in collaboration with experts in other areas, to effectively prevent and control occupational heat stress in a changing climate. PMID:25261455

  14. Re-evaluating occupational heat stress in a changing climate.

    PubMed

    Spector, June T; Sheffield, Perry E

    2014-10-01

    The potential consequences of occupational heat stress in a changing climate on workers, workplaces, and global economies are substantial. Occupational heat stress risk is projected to become particularly high in middle- and low-income tropical and subtropical regions, where optimal controls may not be readily available. This commentary presents occupational heat stress in the context of climate change, reviews its impacts, and reflects on implications for heat stress assessment and control. Future efforts should address limitations of existing heat stress assessment methods and generate economical, practical, and universal approaches that can incorporate data of varying levels of detail, depending on resources. Validation of these methods should be performed in a wider variety of environments, and data should be collected and analyzed centrally for both local and large-scale hazard assessments and to guide heat stress adaptation planning. Heat stress standards should take into account variability in worker acclimatization, other vulnerabilities, and workplace resources. The effectiveness of controls that are feasible and acceptable should be evaluated. Exposure scientists are needed, in collaboration with experts in other areas, to effectively prevent and control occupational heat stress in a changing climate. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  15. Water Replacement Schedules in Heat Stress

    ERIC Educational Resources Information Center

    Londeree, Ben R.; and others

    1969-01-01

    Although early ingestion of cold water appears to lead to greater relief from heat stress during physical exertion than late ingestion, this difference is reduced toward the end of an hour's work in high heat and humidity. (CK)

  16. Water Replacement Schedules in Heat Stress

    ERIC Educational Resources Information Center

    Londeree, Ben R.; and others

    1969-01-01

    Although early ingestion of cold water appears to lead to greater relief from heat stress during physical exertion than late ingestion, this difference is reduced toward the end of an hour's work in high heat and humidity. (CK)

  17. Heat stress interaction with shade and cooling.

    PubMed

    Armstrong, D V

    1994-07-01

    Hot weather causes heat stress in dairy cattle. Although effects are more severe in hot climates, dairy cattle in areas with relatively moderate climates also are exposed to periods of heat stress. The resultant decrease in milk production and reproductive efficiency can be offset by implementation of a program consisting of cooling through shades, ventilation and spray, and fans. The economic benefit should be determined before installation of equipment to reduce heat stress.

  18. Human cardiovascular responses to passive heat stress.

    PubMed

    Crandall, Craig G; Wilson, Thad E

    2015-01-01

    Heat stress increases human morbidity and mortality compared to normothermic conditions. Many occupations, disease states, as well as stages of life are especially vulnerable to the stress imposed on the cardiovascular system during exposure to hot ambient conditions. This review focuses on the cardiovascular responses to heat stress that are necessary for heat dissipation. To accomplish this regulatory feat requires complex autonomic nervous system control of the heart and various vascular beds. For example, during heat stress cardiac output increases up to twofold, by increases in heart rate and an active maintenance of stroke volume via increases in inotropy in the presence of decreases in cardiac preload. Baroreflexes retain the ability to regulate blood pressure in many, but not all, heat stress conditions. Central hypovolemia is another cardiovascular challenge brought about by heat stress, which if added to a subsequent central volumetric stress, such as hemorrhage, can be problematic and potentially dangerous, as syncope and cardiovascular collapse may ensue. These combined stresses can compromise blood flow and oxygenation to important tissues such as the brain. It is notable that this compromised condition can occur at cardiac outputs that are adequate during normothermic conditions but are inadequate in heat because of the increased systemic vascular conductance associated with cutaneous vasodilation. Understanding the mechanisms within this complex regulatory system will allow for the development of treatment recommendations and countermeasures to reduce risks during the ever-increasing frequency of severe heat events that are predicted to occur. © 2015 American Physiological Society.

  19. Human Cardiovascular Responses to Passive Heat Stress

    PubMed Central

    Crandall, Craig G.; Wilson, Thad E.

    2016-01-01

    Heat stress increases human morbidity and mortality compared to normothermic conditions. Many occupations, disease states, as well as stages of life are especially vulnerable to the stress imposed on the cardiovascular system during exposure to hot ambient conditions. This review focuses on the cardiovascular responses to heat stress that are necessary for heat dissipation. To accomplish this regulatory feat requires complex autonomic nervous system control of the heart and various vascular beds. For example, during heat stress cardiac output increases up to twofold, by increases in heart rate and an active maintenance of stroke volume via increases in inotropy in the presence of decreases in cardiac preload. Baroreflexes retain the ability to regulate blood pressure in many, but not all, heat stress conditions. Central hypovolemia is another cardiovascular challenge brought about by heat stress, which if added to a subsequent central volumetric stress, such as hemorrhage, can be problematic and potentially dangerous, as syncope and cardiovascular collapse may ensue. These combined stresses can compromise blood flow and oxygenation to important tissues such as the brain. It is notable that this compromised condition can occur at cardiac outputs that are adequate during normothermic conditions but are inadequate in heat because of the increased systemic vascular conductance associated with cutaneous vasodilation. Understanding the mechanisms within this complex regulatory system will allow for the development of treatment recommendations and countermeasures to reduce risks during the ever-increasing frequency of severe heat events that are predicted to occur. PMID:25589263

  20. Occupational Heat Stress Profiles in Selected Workplaces in India

    PubMed Central

    Venugopal, Vidhya; Chinnadurai, Jeremiah S.; Lucas, Rebekah A. I.; Kjellstrom, Tord

    2015-01-01

    Health and productivity impacts from occupational heat stress have significant ramifications for the large workforce of India. This study profiled occupational heat stress impacts on the health and productivity of workers in select organized and unorganized Indian work sectors. During hotter and cooler seasons, Wet Bulb Globe Temperatures (WBGT) were used to quantify the risk of heat stress, according to International workplace guidelines. Questionnaires assessed workers’ perceived health and productivity impacts from heat stress. A total of 442 workers from 18 Indian workplaces participated (22% and 78% from the organized and unorganized sector, respectively). Overall 82% and 42% of workers were exposed to higher than recommended WBGT during hotter and cooler periods, respectively. Workers with heavy workloads reported more heat-related health issues (chi square = 23.67, p ≤ 0.001) and reduced productivity (chi square = 15.82, p ≤ 0.001), especially the outdoor workers. Heat-rashes, dehydration, heat-syncope and urinogenital symptoms were self-reported health issues. Cited reasons for productivity losses were: extended-work hours due to fatigue/exhaustion, sickness/hospitalization and wages lost. Reducing workplace heat stress will benefit industries and workers via improving worker health and productivity. Adaptation and mitigation measures to tackle heat stress are imperative to protect the present and future workforce as climate change progresses. PMID:26729144

  1. Occupational Heat Stress Profiles in Selected Workplaces in India.

    PubMed

    Venugopal, Vidhya; Chinnadurai, Jeremiah S; Lucas, Rebekah A I; Kjellstrom, Tord

    2015-12-29

    Health and productivity impacts from occupational heat stress have significant ramifications for the large workforce of India. This study profiled occupational heat stress impacts on the health and productivity of workers in select organized and unorganized Indian work sectors. During hotter and cooler seasons, Wet Bulb Globe Temperatures (WBGT) were used to quantify the risk of heat stress, according to International workplace guidelines. Questionnaires assessed workers' perceived health and productivity impacts from heat stress. A total of 442 workers from 18 Indian workplaces participated (22% and 78% from the organized and unorganized sector, respectively). Overall 82% and 42% of workers were exposed to higher than recommended WBGT during hotter and cooler periods, respectively. Workers with heavy workloads reported more heat-related health issues (chi square = 23.67, p ≤ 0.001) and reduced productivity (chi square = 15.82, p ≤ 0.001), especially the outdoor workers. Heat-rashes, dehydration, heat-syncope and urinogenital symptoms were self-reported health issues. Cited reasons for productivity losses were: extended-work hours due to fatigue/exhaustion, sickness/hospitalization and wages lost. Reducing workplace heat stress will benefit industries and workers via improving worker health and productivity. Adaptation and mitigation measures to tackle heat stress are imperative to protect the present and future workforce as climate change progresses.

  2. Quantifying Livestock Heat Stress Impacts in the Sahel

    NASA Astrophysics Data System (ADS)

    Broman, D.; Rajagopalan, B.; Hopson, T. M.

    2014-12-01

    climate variables for West Africa will be presented, An assessment of current and future risk was obtained by linking climatic heat stress to cattle health and production. Seasonal forecasts of heat stress are also provided by modeling the heat stress climate variables using persistent large-scale climate features.

  3. Perceived heat stress and health effects on construction workers

    PubMed Central

    Dutta, Priya; Rajiva, Ajit; Andhare, Dileep; Azhar, Gulrez Shah; Tiwari, Abhiyant; Sheffield, Perry

    2015-01-01

    Introduction: Increasing heat waves-particularly in urban areas where construction is most prevalent, highlight a need for heat exposure assessment of construction workers. This study aims to characterize the effects of heat on construction workers from a site in Gandhinagar. Materials and Methods: This study involved a mixed methods approach consisting of a cross sectional survey with anthropometric measurements (n = 219) and four focus groups with construction workers, as well as environmental measurements of heat stress exposure at a construction site. Survey data was collected in two seasons i.e., summer and winter months, and heat illness and symptoms were compared between the two time periods. Thematic coding of focus group data was used to identify vulnerability factors and coping mechanisms of the workers. Heat stress, recorded using a wet bulb globe temperature monitor, was compared to international safety standards. Results: The survey findings suggest that heat-related symptoms increased in summer; 59% of all reports in summer were positive for symptoms (from Mild to Severe) as compared to 41% in winter. Focus groups revealed four dominant themes: (1) Non-occupational stressors compound work stressors; (2) workers were particularly attuned to the impact of heat on their health; (3) workers were aware of heat-related preventive measures; and (4) few resources were currently available to protect workers from heat stress. Working conditions often exceed international heat stress safety thresholds. Female workers and new employees might be at increased risk of illness or injury. Conclusion: This study suggests significant health impacts on construction workers from heat stress exposure in the workplace, showed that heat stress levels were higher than those prescribed by international standards and highlights the need for revision of work practices, increased protective measures, and possible development of indigenous work safety standards for heat exposure

  4. Perceived heat stress and health effects on construction workers.

    PubMed

    Dutta, Priya; Rajiva, Ajit; Andhare, Dileep; Azhar, Gulrez Shah; Tiwari, Abhiyant; Sheffield, Perry

    2015-01-01

    Increasing heat waves-particularly in urban areas where construction is most prevalent, highlight a need for heat exposure assessment of construction workers. This study aims to characterize the effects of heat on construction workers from a site in Gandhinagar. This study involved a mixed methods approach consisting of a cross sectional survey with anthropometric measurements (n = 219) and four focus groups with construction workers, as well as environmental measurements of heat stress exposure at a construction site. Survey data was collected in two seasons i.e., summer and winter months, and heat illness and symptoms were compared between the two time periods. Thematic coding of focus group data was used to identify vulnerability factors and coping mechanisms of the workers. Heat stress, recorded using a wet bulb globe temperature monitor, was compared to international safety standards. The survey findings suggest that heat-related symptoms increased in summer; 59% of all reports in summer were positive for symptoms (from Mild to Severe) as compared to 41% in winter. Focus groups revealed four dominant themes: (1) Non-occupational stressors compound work stressors; (2) workers were particularly attuned to the impact of heat on their health; (3) workers were aware of heat-related preventive measures; and (4) few resources were currently available to protect workers from heat stress. Working conditions often exceed international heat stress safety thresholds. Female workers and new employees might be at increased risk of illness or injury. This study suggests significant health impacts on construction workers from heat stress exposure in the workplace, showed that heat stress levels were higher than those prescribed by international standards and highlights the need for revision of work practices, increased protective measures, and possible development of indigenous work safety standards for heat exposure.

  5. Impact of Heat Stress on Poultry Production.

    PubMed

    Lara, Lucas J; Rostagno, Marcos H

    2013-04-24

    Understanding and controlling environmental conditions is crucial to successful poultry production and welfare. Heat stress is one of the most important environmental stressors challenging poultry production worldwide. The detrimental effects of heat stress on broilers and laying hens range from reduced growth and egg production to decreased poultry and egg quality and safety. Moreover, the negative impact of heat stress on poultry welfare has recently attracted increasing public awareness and concern. Much information has been published on the effects of heat stress on productivity and immune response in poultry. However, our knowledge of basic mechanisms associated to the reported effects, as well as related to poultry behavior and welfare under heat stress conditions is in fact scarce. Intervention strategies to deal with heat stress conditions have been the focus of many published studies. Nevertheless, effectiveness of most of the interventions has been variable or inconsistent. This review focuses on the scientific evidence available on the importance and impact of heat stress in poultry production, with emphasis on broilers and laying hens.

  6. Heat stress and protection from permanent acoustic injury in mice.

    PubMed

    Yoshida, N; Kristiansen, A; Liberman, M C

    1999-11-15

    The inner ear can be permanently damaged by overexposure to high-level noise; however, damage can be decreased by previous exposure to moderate level, nontraumatic noise (). The mechanism of this "protective" effect is unclear, but a role for heat shock proteins has been suggested. The aim of the present study was to directly test protective effects of heat stress in the ear. For physiological experiments, CBA/CaJ mice were exposed to an intense octave band of noise (8-16 kHz) at 100 dB SPL for 2 hr, either with or without previous whole-body heat stress (rectal temperature to 41. 5 degrees C for 15 min). The interval between heat stress and sound exposure varied in different groups from 6 to 96 hr. One week later, inner ear function was assessed in each animal via comparison of compound action potential thresholds to mean values from unexposed controls. Permanent threshold shifts (PTSs) were approximately 40 dB in the group sound-exposed without previous heat stress. Heat-stressed animals were protected from acoustic injury: mean PTS in the group with 6 hr heat-stress-trauma interval was reduced to approximately 10 dB. This heat stress protection disappeared when the treatment-trauma interval surpassed 24 hr. A parallel set of quantitative PCR experiments measured heat-shock protein mRNA in the cochlea and showed 100- to 200-fold increase over control 30 min after heat treatment, with levels returning to baseline at 6 hr after treatment. Results are consistent with the idea that upregulation of heat shock proteins protects the ear from acoustic injury.

  7. Mechanisms of orthostatic intolerance during heat stress.

    PubMed

    Schlader, Zachary J; Wilson, Thad E; Crandall, Craig G

    2016-04-01

    Heat stress profoundly and unanimously reduces orthostatic tolerance. This review aims to provide an overview of the numerous and multifactorial mechanisms by which this occurs in humans. Potential causal factors include changes in arterial and venous vascular resistance and blood distribution, and the modulation of cardiac output, all of which contribute to the inability to maintain cerebral perfusion during heat and orthostatic stress. A number of countermeasures have been established to improve orthostatic tolerance during heat stress, which alleviate heat stress induced central hypovolemia (e.g., volume expansion) and/or increase peripheral vascular resistance (e.g., skin cooling). Unfortunately, these countermeasures can often be cumbersome to use with populations prone to syncopal episodes. Identifying the mechanisms of inter-individual differences in orthostatic intolerance during heat stress has proven elusive, but could provide greater insights into the development of novel and personalized countermeasures for maintaining or improving orthostatic tolerance during heat stress. This development will be especially impactful in occuational settings and clinical situations that present with orthostatic intolerance and/or central hypovolemia. Such investigations should be considered of vital importance given the impending increased incidence of heat events, and associated cardiovascular challenges that are predicted to occur with the ensuing changes in climate. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Mechanisms of orthostatic intolerance during heat stress

    PubMed Central

    Schlader, Zachary J.; Wilson, Thad E.; Crandall, Craig G.

    2017-01-01

    Heat stress profoundly and unanimously reduces orthostatic tolerance. This review aims to provide an overview of the numerous and multifactorial mechanisms by which this occurs in humans. Potential causal factors include changes in arterial and venous vascular resistance and blood distribution, and the modulation of cardiac output, all of which contribute to the inability to maintain cerebral perfusion during heat and orthostatic stress. A number of countermeasures have been established to improve orthostatic tolerance during heat stress, which alleviate heat stress induced central hypovolemia (e.g., volume expansion) and/or increase peripheral vascular resistance (e.g., skin cooling). Unfortunately, these countermeasures can often be cumbersome to use with populations prone to syncopal episodes. Identifying the mechanisms of inter-individual differences in orthostatic intolerance during heat stress has proven elusive, but could provide greater insights into the development of novel and personalized countermeasures for maintaining or improving orthostatic tolerance during heat stress. This development will be especially impactful in occuational settings and clinical situations that present with orthostatic intolerance and/or central hypovolemia. Such investigations should be considered of vital importance given the impending increased incidence of heat events, and associated cardiovascular challenges that are predicted to occur with the ensuing changes in climate. PMID:26723547

  9. Drivers and barriers to heat stress resilience.

    PubMed

    Hatvani-Kovacs, Gertrud; Belusko, Martin; Skinner, Natalie; Pockett, John; Boland, John

    2016-11-15

    Heatwaves are the most dangerous natural hazard to health in Australia. The frequency and intensity of heatwaves will increase due to climate change and urban heat island effects in cities, aggravating the negative impacts of heatwaves. Two approaches exist to develop population heat stress resilience. Firstly, the most vulnerable social groups can be identified and public health services can prepare for the increased morbidity. Secondly, the population level of adaptation and the heat stress resistance of the built environment can be increased. The evaluation of these measures and their efficiencies has been fragmented across research disciplines. This study explored the relationships between the elements of heat stress resilience and their potential demographic and housing drivers and barriers. The responses of a representative online survey (N=393) about heat stress resilience at home and work from Adelaide, South Australia were analysed. The empirical findings demonstrate that heat stress resistant buildings increased adaptation capacity and decreased the number of health problems. Air-conditioning increased dependence upon it, limited passive adaptation and only people living in homes with whole-house air-conditioning had less health problems during heatwaves. Tenants and respondents with pre-existing health conditions were the most vulnerable, particularly as those with health conditions were not aware of their vulnerability. The introduction of an Energy Performance Certificate is proposed and discussed as an effective incentive to increase the heat stress resistance of and the general knowledge about the built environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Industrial heat pump assessment study

    NASA Astrophysics Data System (ADS)

    Chappell, R. N.; Priebe, S. J.; Wilfert, G. L.

    1989-03-01

    This report summarizes preliminary studies that assess the potential of industrial heat pumps for reduction of process heating requirements in industries receiving power from the Bonneville Power Administration (BPA). This project was initiated at the request of BPA to determine the potential of industrial heat pumps in BPA's service area. Working from known heat pump principles and from a list of BPA's industrial customers, the authors estimated the fuel savings potential for six industries. Findings indicate that the pulp and paper industry would yield the greatest fuel savings and increased electrical consumption. Assessments presented in this report represent a cooperative effort between The Idaho National Engineering Laboratory (INEL), and Battelle-Northwest Laboratories.

  11. Assessment of stress tolerance acquisition in the heat-tolerant derivative strains of Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus rhamnosus GG.

    PubMed

    Aakko, J; Sánchez, B; Gueimonde, M; Salminen, S

    2014-07-01

    The purpose of this study was to investigate the heat-shock response at molecular level in Lactobacillus rhamnosus GG, Bifidobacterium animalis subsp. lactis BB-12 and their heat-tolerant derivatives and to characterize the changes that make the derivatives more robust in terms of heat stress. The study strains were exposed for 2 h to a heat-shock treatment, Bif. animalis subsp. lactis BB-12 and its derivative at 50°C and the Lact. rhamnosus GG and its derivative at 60°C. Protein synthesis before and after heat shock was examined using proteomics and RT-qPCR. The analysis revealed that the regulation of seven proteins in both strain pairs was modified as a response to heat or between the original and the derivative strain. The comparison of wild-type strains and the heat-tolerant derivatives suggests that the acquisition of heat tolerance in the Bif. animalis subsp. lactis BB-12 derivative is due to a slightly increased constitutive level of chaperones, while in Lact. rhamnosus GG derivative, the main reason seems to be a higher ability to induce the production of chaperones. This study revealed possible markers of heat tolerance in B. lactis and Lact. rhamnosus strains. This study increases our knowledge on how Lactobacillus and Bifidobacterium strains may acquire heat tolerance. These findings may be useful for improving the heat tolerance of existing probiotic strains as well as screening new heat-tolerant strains. © 2014 The Society for Applied Microbiology.

  12. Heat Stress in Older Adults

    MedlinePlus

    ... Centers Extreme Heat PSAs Related Links MMWR Bibliography Floods Flood Readiness Personal Hygiene After a Disaster Reentering Your Flooded Home Cleanup of Flood Water After a Flood Worker Safety Educational Materials ...

  13. Thermometry, calorimetry, and mean body temperature during heat stress.

    PubMed

    Kenny, Glen P; Jay, Ollie

    2013-10-01

    Heat balance in humans is maintained at near constant levels through the adjustment of physiological mechanisms that attain a balance between the heat produced within the body and the heat lost to the environment. Heat balance is easily disturbed during changes in metabolic heat production due to physical activity and/or exposure to a warmer environment. Under such conditions, elevations of skin blood flow and sweating occur via a hypothalamic negative feedback loop to maintain an enhanced rate of dry and evaporative heat loss. Body heat storage and changes in core temperature are a direct result of a thermal imbalance between the rate of heat production and the rate of total heat dissipation to the surrounding environment. The derivation of the change in body heat content is of fundamental importance to the physiologist assessing the exposure of the human body to environmental conditions that result in thermal imbalance. It is generally accepted that the concurrent measurement of the total heat generated by the body and the total heat dissipated to the ambient environment is the most accurate means whereby the change in body heat content can be attained. However, in the absence of calorimetric methods, thermometry is often used to estimate the change in body heat content. This review examines heat exchange during challenges to heat balance associated with progressive elevations in environmental heat load and metabolic rate during exercise. Further, we evaluate the physiological responses associated with heat stress and discuss the thermal and nonthermal influences on the body's ability to dissipate heat from a heat balance perspective.

  14. Drivers of self-reported heat stress in the Australian labour force.

    PubMed

    Zander, Kerstin K; Moss, Simon A; Garnett, Stephen T

    2017-01-01

    Heat stress causes reductions in well-being and health. As average annual temperatures increase, heat stress is expected to affect more people. While most research on heat stress has explored how exposure to heat affects functioning of the human organism, stress from heat can be manifest long before clinical symptoms are evident, with profound effects on behavior. Here we add to the little research conducted on these subclinical effects of environmental heat using results from an Australian-wide cross-sectional study of nearly 2000 respondents on their self-reported level of heat stress. Slightly less than half (47%) of the respondents perceived themselves as at least sometimes, often or very often stressed by heat during the previous 12 months. Health status and smoking behavior had the expected impact on self-reported perceived heat stress. There were also regional differences with people living in South Australia, Victoria and New South Wales most likely to have reported to have felt heat stressed. People generally worried about climate change, who had been influenced by recent heat waves and who thought there was a relationship between climate change and health were also more likely to have been heat stressed. Surprisingly average maximum temperatures did not significantly explain heat stress but stress was greater among people who perceived the day of the survey as hotter than usual. Currently heat stress indices are largely based on monitoring the environment and physical limitations to people coping with heat. Our results suggest that psychological perceptions of heat need to be considered when predicting how people will be affected by heat under climate change and when developing heat relief and climate change adaptation plans, at work, at home or in public spaces. We further conclude that the perception of temperature and heat stress complements measures that assess heat exposure and heat strain.

  15. Estimates of heat stress relief needs for Holstein dairy cows.

    PubMed

    Berman, A

    2005-06-01

    Estimates of environmental heat stress are required for heat stress relief measures in cattle. Heat stress is commonly assessed by the temperature-humidity index (THI), the sum of dry and wet bulb temperatures. The THI does not include an interaction between temperature and humidity, although evaporative heat loss increases with rising air temperature. Coat, air velocity, and radiation effects also are not accounted for in the THI. The Holstein dairy cow is the primary target of heat stress relief, followed by feedlot cattle. Heat stress may be estimated for a variety of conditions by thermal balance models. The models consist of animal-specific data (BW, metabolic heat production, tissue and coat insulation, skin water loss, coat depth, and minimal and maximal tidal volumes) and of general heat exchange equations. A thermal balance simulation model was modified to adapt it for Holstein cows by using Holstein data for the animal characteristics in the model, and was validated by comparing its outputs to experimental data. Model outputs include radiant, convective, skin evaporative, respiratory heat loss and rate of change of body temperature. Effects of milk production (35 and 45 kg/d), hair coat depth (3 and 6 mm), air temperature (20 to 45 degrees C), air velocity (0.2 to 2.0 m/s), air humidity (0.8 to 3.9 kPa), and exposed body surface (100, 75, and 50%) on thermal balance outputs were examined. Environmental conditions at which respiratory heat loss attained approximately 50% of its maximal value were defined as thresholds for intermediate heat stress. Air velocity increased and humidity significantly decreased threshold temperatures, particularly at higher coat depth. The effect of air velocity was amplified at high humidity. Increasing milk production from 35 to 45 kg/d decreased threshold temperature by 5 degrees C. In the lying cow, the lower air velocity in the proximity of body surface and the smaller exposed surface markedly decrease threshold

  16. Urban Heat Wave Hazard Assessment

    NASA Astrophysics Data System (ADS)

    Quattrochi, D. A.; Jedlovec, G.; Crane, D. L.; Meyer, P. J.; LaFontaine, F.

    2016-12-01

    Heat waves are one of the largest causes of environmentally-related deaths globally and are likely to become more numerous as a result of climate change. The intensification of heat waves by the urban heat island effect and elevated humidity, combined with urban demographics, are key elements leading to these disasters. Better warning of the potential hazards may help lower risks associated with heat waves. Moderate resolution thermal data from NASA satellites is used to derive high spatial resolution estimates of apparent temperature (heat index) over urban regions. These data, combined with demographic data, are used to produce a daily heat hazard/risk map for selected cities. MODIS data are used to derive daily composite maximum and minimum land surface temperature (LST) fields to represent the amplitude of the diurnal temperature cycle and identify extreme heat days. Compositing routines are used to generate representative daily maximum and minimum LSTs for the urban environment. The limited effect of relative humidity on the apparent temperature (typically 10-15%) allows for the use of modeled moisture fields to convert LST to apparent temperature without loss of spatial variability. The daily max/min apparent temperature fields are used to identify abnormally extreme heat days relative to climatological values in order to produce a heat wave hazard map. Reference to climatological values normalizes the hazard for a particular region (e.g., the impact of an extreme heat day). A heat wave hazard map has been produced for several case study periods and then computed on a quasi-operational basis during the summer of 2016 for Atlanta, GA, Chicago, IL, St. Louis, MO, and Huntsville, AL. A hazard does not become a risk until someone or something is exposed to that hazard at a level that might do harm. Demographic information is used to assess the urban risk associated with the heat wave hazard. Collectively, the heat wave hazard product can warn people in urban

  17. Thermal Indices and Thermophysiological Modeling for Heat Stress.

    PubMed

    Havenith, George; Fiala, Dusan

    2015-12-15

    The assessment of the risk of human exposure to heat is a topic as relevant today as a century ago. The introduction and use of heat stress indices and models to predict and quantify heat stress and heat strain has helped to reduce morbidity and mortality in industrial, military, sports, and leisure activities dramatically. Models used range from simple instruments that attempt to mimic the human-environment heat exchange to complex thermophysiological models that simulate both internal and external heat and mass transfer, including related processes through (protective) clothing. This article discusses the most commonly used indices and models and looks at how these are deployed in the different contexts of industrial, military, and biometeorological applications, with focus on use to predict related thermal sensations, acute risk of heat illness, and epidemiological analysis of morbidity and mortality. A critical assessment is made of tendencies to use simple indices such as WBGT in more complex conditions (e.g., while wearing protective clothing), or when employed in conjunction with inappropriate sensors. Regarding the more complex thermophysiological models, the article discusses more recent developments including model individualization approaches and advanced systems that combine simulation models with (body worn) sensors to provide real-time risk assessment. The models discussed in the article range from historical indices to recent developments in using thermophysiological models in (bio) meteorological applications as an indicator of the combined effect of outdoor weather settings on humans.

  18. Heat Stress Effects on Growing-Finishing Swine

    USDA-ARS?s Scientific Manuscript database

    Understanding the factors that create heat stress, the response of the animals while under heat stress, and the signs of heat-stressed swine are essential to making rational decisions for the selection, design, and management of their environments. Heat stressors include combinations of environment...

  19. Effect of heat stress on oxidative stress, lipid peroxidation and some stress parameters in broilers.

    PubMed

    Altan, O; Pabuçcuoğlu, A; Altan, A; Konyalioğlu, S; Bayraktar, H

    2003-09-01

    1. This study was conducted to determine the effects of heat stress on fearfulness, leucocyte components, oxidative stress and lipid peroxidation in two commercial broiler strains, Cobb (C) and Ross (R). 2. At 36 and 37 d of age birds were exposed to 38 +/- 1 degree C for 3 h. Rectal temperatures, duration of tonic immobility (TI), haematocrit values, proportions of leucocyte components (heterophil, lymphocyte, basophil, eosinophil, monocyte), malondialdehyde (MDA) concentrations and antioxidant enzyme activities (CAT, SOD, GPx) of all the birds were determined, before and after heat treatment. 3. Rectal temperatures increased and haematocrit values decreased in birds exposed to heat stress. Heat stress caused a significant increase in heterophil/lymphocyte and in basophil ratios. 4. Exposing birds to heat stress increased duration of TI, suggesting heat-stressed birds tended to be more fearful. 5. Heat stress resulted in a significant Genotype x Treatment interaction for MDA concentration. CAT, SOD and GPx activities; MDA concentrations in heat-stressed R strain birds were greater than in heat-stressed C strain birds.

  20. Sensing the Heat Stress by Mammalian Cells

    PubMed Central

    2011-01-01

    Background The heat-shock response network controls the adaptation and survival of the cell against environmental stress. This network is highly conserved and is connected with many other signaling pathways. A key element of the heat-shock network is the heat-shock transcription factor-1 (HSF), which is transiently activated by elevated temperatures. HSF translocates to the nucleus upon elevated temperatures, forming homotrimeric complexes. The HSF homotrimers bind to the heat shock element on the DNA and control the expression of the hsp70 gene. The Hsp70 proteins protect cells from thermal stress. Thermal stress causes the unfolding of proteins, perturbing thus the pathways under their control. By binding to these proteins, Hsp70 allows them to refold and prevents their aggregation. The modulation of the activity of the hsp70-promoter by the intensity of the input stress is thus critical for cell's survival. The promoter activity starts from a basal level and rapidly increases once the stress is applied, reaches a maximum level and attenuates slowely back to the basal level. This phenomenon is the hallmark of many experimental studies and of all computational network analysis. Results The molecular construct used as a measure of the response to thermal stress is a Hsp70-GFP fusion gene transfected in Chinese hamster ovary (CHO) cells. The time profile of the GFP protein depends on the transient activity, Transient(t), of the heat shock system. The function Transient(t) depends on hsp70 promoter activity, transcriptional regulation and the translation initiation effects elicited by the heat stress. The GFP time profile is recorded using flow cytometry measurements, a technique that allows a quantitative measurement of the fluorescence of a large number of cells (104). The GFP responses to one and two heat shocks were measured for 261 conditions of different temperatures and durations. We found that: (i) the response of the cell to two consecutive shocks (i.e., no

  1. Determination of Air Enthalpy Based on Meteorological Data as an Indicator for Heat Stress Assessment in Occupational Outdoor Environments, a Field Study in IRAN.

    PubMed

    Heidari, Hamidreza; Golbabaei, Farideh; Shamsipour, Aliakbar; Rahimi Forushani, Abbas; Gaeini, Abbasali

    2016-01-01

    Heat stress evaluation and timely notification, especially using meteorological data is an important issue attracted attention in recent years. Therefore, this study aimed at answering the following research questions: 1) can enthalpy as a common environmental parameter reported by meteorological agencies be applied accurately for evaluation of thermal condition of outdoor settings, and 2) if so, what is it's the best criterion to detect areas in stress or stress-free situations, separately. Nine climatic regions were selected throughout Iran covering a wide variety of climatic conditions like those, which exist around the world. Three types of parameters including measured (ta, RH, Pa and WBGT), estimated (metabolic rate and cloth thermal insulation), and calculated parameters (enthalpy and effective WBGT) were recorded for 1452 different situations. Enthalpy as a new indicator in this research was compared to WBGT in selected regions. Altogether, a good consistency was obtained between enthalpy and WBGT in selected regions (Kappa value: 0.815). Based on the good ROC curve obtained using MedCal software, the criterion of the values more than 74.24 for the new index was determined to explain heat stress situation for outdoor environments. Because of simplicity in measurement, applicability of the indicator for weather agencies, the consistency observed between enthalpy and a valid as well as accurate index (WBGT), sensor requirements which take only a few seconds to reach equilibrium and so on, enthalpy indicator can be introduced and applied as a good substitute for WBGT for outdoor settings.

  2. Influence of heat stress to matrix on bone formation.

    PubMed

    Yoshida, Keiko; Uoshima, Katsumi; Oda, Kimimitsu; Maeda, Takeyasu

    2009-08-01

    It is important to know the etiology of implant failure. It has been reported that heat stress during drilling was one of the causes for failure and the threshold was 47 degrees C. However, clinically, we encounter cases in which overheating does not seem to affect osseointegration eventually. The purpose of this study was to assess histologically the spatio-temporal effect of heat stress on bone formation after overheating the bone matrix. Rat calvarial bone was heated to 37 degrees C, 43 degrees C, 45 degrees C and 48 degrees C for 15 min by a temperature stimulator. Paraffin sections were prepared 1, 3 and 5 weeks after heating and investigated histologically under light microscopy. Hematoxylin and eosin staining, alkaline phosphatase (ALP), osteopontin (OPN), heat shock protein 27 (Hsp27) and heat shock protein 70 (Hsp70) immunohistochemistry and tartrate-resistant acid phosphatase (TRAP) enzyme histochemistry were carried out. The area of dead osteocytes was calculated and statistically analyzed. Apoptotic osteocytes were detected by the terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling (TUNEL) method. Along with the temperature increase, the area of dead osteocytes increased and regeneration of the periosteal membrane was delayed. Hsps- and TUNEL-positive cells were only seen in the 48 degrees C group. Spatio-temporal changes of TRAP- and ALP-positive cell numbers were observed, while OPN expression was mostly absent. Even after 48 degrees C stimulation, bone formation on the calvarial surface was observed after 5 weeks. Although there was a temperature-dependent delay in bone formation after heat stress, the 48 degrees C heat stress did not obstruct bone formation eventually. This delay was probably caused by slow periosteal membrane regeneration.

  3. Expression of translationally controlled tumor protein in heat-stressed human dental pulp cells.

    PubMed

    Jirachotikoon, Canussanun; Tannukit, Sissada; Kedjarune-Leggat, Ureporn

    2015-10-01

    The aim of this study was to investigate the effects of heat stress on cell viability, translationally controlled tumor protein (TCTP) expression, and the effects of recombinant TCTP on heat-stressed human dental pulp cells (HDPCs). HDPCs were isolated from human teeth and cultured at 37°C. For heat stress, HPDCs were incubated at 43°C for 45min. After heat stress, recombinant TCTP were added to HDPCs and cultured for various periods of time at 37°C. Heat-treated cells were then analyzed by DNA staining with Hoechst 33258, MTT, and caspase 3 activity assays. TCTP expression level was assessed by real-time PCR and western blot analysis. Heat-treated cells displayed lower cell density and nuclear morphology resembling apoptotic body. Heat stress significantly decreased cell viability and induced activity of caspase 3. The effect of recombinant TCTP on pulp cell death from heat stress varied depending on each subject and TCTP concentration. Heat stress up-regulated TCTP mRNA expression level. In contrast, TCTP protein level remained unchanged. Recombinant TCTP did not affect TCTP mRNA expression but down-regulated TCTP protein in heat-treated cells. Heat stress induces caspase 3 activation and up-regulates TCTP mRNA expression in HDPCs. TCTP did not play a key role on pulp cell recovery from heat stress. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Carotid baroreflex responsiveness in heat-stressed humans

    NASA Technical Reports Server (NTRS)

    Crandall, C. G.

    2000-01-01

    The effects of whole body heating on human baroreflex function are relatively unknown. The purpose of this project was to identify whether whole body heating reduces the maximal slope of the carotid baroreflex. In 12 subjects, carotid-vasomotor and carotid-cardiac baroreflex responsiveness were assessed in normothermia and during whole body heating. Whole body heating increased sublingual temperature (from 36.4 +/- 0.1 to 37.4 +/- 0.1 degrees C, P < 0.01) and increased heart rate (from 59 +/- 3 to 83 +/- 3 beats/min, P < 0. 01), whereas mean arterial blood pressure (MAP) was slightly decreased (from 88 +/- 2 to 83 +/- 2 mmHg, P < 0.01). Carotid-vasomotor and carotid-cardiac responsiveness were assessed by identifying the maximal gain of MAP and heart rate to R wave-triggered changes in carotid sinus transmural pressure. Whole body heating significantly decreased the responsiveness of the carotid-vasomotor baroreflex (from -0.20 +/- 0.02 to -0.13 +/- 0.02 mmHg/mmHg, P < 0.01) without altering the responsiveness of the carotid-cardiac baroreflex (from -0.40 +/- 0.05 to -0.36 +/- 0.02 beats x min(-1) x mmHg(-1), P = 0.21). Carotid-vasomotor and carotid-cardiac baroreflex curves were shifted downward and upward, respectively, to accommodate the decrease in blood pressure and increase in heart rate that accompanied the heat stress. Moreover, the operating point of the carotid-cardiac baroreflex was shifted closer to threshold (P = 0.02) by the heat stress. Reduced carotid-vasomotor baroreflex responsiveness, coupled with a reduction in the functional reserve for the carotid baroreflex to increase heart rate during a hypotensive challenge, may contribute to increased susceptibility to orthostatic intolerance during a heat stress.

  5. Carotid baroreflex responsiveness in heat-stressed humans

    NASA Technical Reports Server (NTRS)

    Crandall, C. G.

    2000-01-01

    The effects of whole body heating on human baroreflex function are relatively unknown. The purpose of this project was to identify whether whole body heating reduces the maximal slope of the carotid baroreflex. In 12 subjects, carotid-vasomotor and carotid-cardiac baroreflex responsiveness were assessed in normothermia and during whole body heating. Whole body heating increased sublingual temperature (from 36.4 +/- 0.1 to 37.4 +/- 0.1 degrees C, P < 0.01) and increased heart rate (from 59 +/- 3 to 83 +/- 3 beats/min, P < 0. 01), whereas mean arterial blood pressure (MAP) was slightly decreased (from 88 +/- 2 to 83 +/- 2 mmHg, P < 0.01). Carotid-vasomotor and carotid-cardiac responsiveness were assessed by identifying the maximal gain of MAP and heart rate to R wave-triggered changes in carotid sinus transmural pressure. Whole body heating significantly decreased the responsiveness of the carotid-vasomotor baroreflex (from -0.20 +/- 0.02 to -0.13 +/- 0.02 mmHg/mmHg, P < 0.01) without altering the responsiveness of the carotid-cardiac baroreflex (from -0.40 +/- 0.05 to -0.36 +/- 0.02 beats x min(-1) x mmHg(-1), P = 0.21). Carotid-vasomotor and carotid-cardiac baroreflex curves were shifted downward and upward, respectively, to accommodate the decrease in blood pressure and increase in heart rate that accompanied the heat stress. Moreover, the operating point of the carotid-cardiac baroreflex was shifted closer to threshold (P = 0.02) by the heat stress. Reduced carotid-vasomotor baroreflex responsiveness, coupled with a reduction in the functional reserve for the carotid baroreflex to increase heart rate during a hypotensive challenge, may contribute to increased susceptibility to orthostatic intolerance during a heat stress.

  6. Plastic and evolutionary responses to heat stress in a temperate dung fly: negative correlation between basal and induced heat tolerance?

    PubMed

    Esperk, T; Kjaersgaard, A; Walters, R J; Berger, D; Blanckenhorn, W U

    2016-05-01

    Extreme weather events such as heat waves are becoming more frequent and intense. Populations can cope with elevated heat stress by evolving higher basal heat tolerance (evolutionary response) and/or stronger induced heat tolerance (plastic response). However, there is ongoing debate about whether basal and induced heat tolerance are negatively correlated and whether adaptive potential in heat tolerance is sufficient under ongoing climate warming. To evaluate the evolutionary potential of basal and induced heat tolerance, we performed experimental evolution on a temperate source population of the dung fly Sepsis punctum. Offspring of flies adapted to three thermal selection regimes (Hot, Cold and Reference) were subjected to acute heat stress after having been exposed to either a hot-acclimation or non-acclimation pretreatment. As different traits may respond differently to temperature stress, several physiological and life history traits were assessed. Condition dependence of the response was evaluated by exposing juveniles to different levels of developmental (food restriction/rearing density) stress. Heat knockdown times were highest, whereas acclimation effects were lowest in the Hot selection regime, indicating a negative association between basal and induced heat tolerance. However, survival, adult longevity, fecundity and fertility did not show such a pattern. Acclimation had positive effects in heat-shocked flies, but in the absence of heat stress hot-acclimated flies had reduced life spans relative to non-acclimated ones, thereby revealing a potential cost of acclimation. Moreover, body size positively affected heat tolerance and unstressed individuals were less prone to heat stress than stressed flies, offering support for energetic costs associated with heat tolerance. Overall, our results indicate that heat tolerance of temperate insects can evolve under rising temperatures, but this response could be limited by a negative relationship between basal and

  7. Comparison of the heat stress induced variations in DNA methylation between heat-tolerant and heat-sensitive rapeseed seedlings

    PubMed Central

    Gao, Guizhen; Li, Jun; Li, Hao; Li, Feng; Xu, Kun; Yan, Guixin; Chen, Biyun; Qiao, Jiangwei; Wu, Xiaoming

    2014-01-01

    DNA methylation is responsive to various biotic and abiotic stresses. Heat stress is a serious threat to crop growth and development worldwide. Heat stress results in an array of morphological, physiological and biochemical changes in plants. The relationship between DNA methylation and heat stress in crops is relatively unknown. We investigated the differences in methylation levels and changes in the cytosine methylation patterns in seedlings of two rapeseed genotypes (heat-sensitive and heat-tolerant) under heat stress. Our results revealed that the methylation levels were different between a heat-tolerant genotype and a heat-sensitive one under control conditions. Under heat treatment, methylation increased more in the heat-sensitive genotype than in the heat-tolerant genotype. More DNA demethylation events occurred in the heat-tolerant genotype, while more DNA methylation occurred in the heat-sensitive genotype. A large and diverse set of genes were affected by heat stress via cytosine methylation changes, suggesting that these genes likely play important roles in the response and adaption to heat stress in Brassica napus L. This study indicated that the changes in DNA methylation differed between heat-tolerant and heat-sensitive genotypes of B. napus in response to heat stress, which further illuminates the molecular mechanisms of the adaption to heat stress in B. napus. PMID:24987298

  8. Prompt protein glycosylation during acute heat stress.

    PubMed

    Henle, K J; Kaushal, G P; Nagle, W A; Nolen, G T

    1993-08-01

    Constitutive patterns of protein synthesis and protein glycosylation are severely disrupted by acute heat stress. Stressed cells respond by preferential synthesis of specific proteins, e.g., the well-known family of heat shock proteins. We observed another response that rapidly occurs during heating periods as short as 10 min at 45 degrees C. During that period, CHO cells began to glycosylate specific proteins, designated as "prompt" stress glycoproteins (P-SG), while constitutive protein glycosylation ceased. Labeling of P-SGs showed a dose response with time and with temperature and appeared regardless of the label used (D-[3H]mannose or D-[3H]glucose). On SDS-PAGE, the major P-SG was characterized by M(r) approximately 67 kDa (P-SG67) and pI = 5.1. Other less prominent P-SGs appeared at M(r) 160, 100, 64, 60, and 47 kDa; incorporated label showed little turnover during 24 h at 37 degrees C. Prompt glycosylation was inhibited by tunicamycin, and label incorporated into P-SGs was sensitive to N-glycosidase F, but not to O-glycosidase. Analysis of enzymatically digested P-SG67 indicated that label had been incorporated into both high-mannose (Man9GlcNAc) and complex-type oligosaccharides. Brefeldin A did not eliminate P-SG67 labeling, but caused the further appearance of novel, Brefeldin-associated P-SGs. Labeling of P-SG67 oligosaccharides occurred without significant concomitant protein synthesis, suggesting that addition of labeled oligosaccharides largely occurred on mature, rather than nascent proteins. The functional significance of prompt glycosylation remains to be defined, but we propose that this novel phenomenon is an integral part of the cellular heat stress response.

  9. Tank waste remediation system heat stress control program report, 1995

    SciTech Connect

    Carls, D.R.

    1995-09-28

    Protecting employees from heat stress within tank farms during the summer months is challenging. Work constraints typically experienced in tank farms complicate the measures taken to protect employees from heat stress. TWRS-Industrial Hygiene (IH) has endeavored to control heat stress injuries by anticipating, recognizing, evaluating and controlling the factors which lead or contribute to heat stress in Tank Farms. The TWRS Heat Stress Control Program covers such areas as: employee and PIC training, communication of daily heat stress alerts to tank farm personnel, setting work/rest regimens, and the use of engineering and personal protective controls when applicable. The program has increased worker awareness of heat stress and prevention, established provisions for worker rest periods, increased drinking water availability to help ensure worker hydration, and allowed for the increased use of other protective controls to combat heat stress. The TWRS Heat Stress Control Program is the cornerstone for controlling heat stress among tank farm employees. The program has made great strides since it`s inception during the summer of 1994. Some improvements can still be made to enhance the program for the summer of 1996, such as: (1) procurement and use of personal heat stress monitoring equipment to ensure appropriate application of administrative controls, (2) decrease the need for use of containment tents and anti-contamination clothing, and (3) providing a wider variety of engineering and personal protective controls for heat stress prevention

  10. Osmotic and Heat Stress Effects on Segmentation

    PubMed Central

    Weiss, Julian

    2016-01-01

    During vertebrate embryonic development, early skin, muscle, and bone progenitor populations organize into segments known as somites. Defects in this conserved process of segmentation lead to skeletal and muscular deformities, such as congenital scoliosis, a curvature of the spine caused by vertebral defects. Environmental stresses such as hypoxia or heat shock produce segmentation defects, and significantly increase the penetrance and severity of vertebral defects in genetically susceptible individuals. Here we show that a brief exposure to a high osmolarity solution causes reproducible segmentation defects in developing zebrafish (Danio rerio) embryos. Both osmotic shock and heat shock produce border defects in a dose-dependent manner, with an increase in both frequency and severity of defects. We also show that osmotic treatment has a delayed effect on somite development, similar to that observed in heat shocked embryos. Our results establish osmotic shock as an alternate experimental model for stress, affecting segmentation in a manner comparable to other known environmental stressors. The similar effects of these two distinct environmental stressors support a model in which a variety of cellular stresses act through a related response pathway that leads to disturbances in the segmentation process. PMID:28006008

  11. Aloin Protects Skin Fibroblasts from Heat Stress-Induced Oxidative Stress Damage by Regulating the Oxidative Defense System.

    PubMed

    Liu, Fu-Wei; Liu, Fu-Chao; Wang, Yu-Ren; Tsai, Hsin-I; Yu, Huang-Ping

    2015-01-01

    Oxidative stress is commonly involved in the pathogenesis of skin damage induced by environmental factors, such as heat stress. Skin fibroblasts are responsible for the connective tissue regeneration and the skin recovery from injury. Aloin, a bioactive compound in Aloe vera, has been reported to have various pharmacological activities, such as anti-inflammatory effects. The aim of this study was to investigate the protective effect of aloin against heat stress-mediated oxidative stress in human skin fibroblast Hs68 cells. Hs68 cells were first incubated at 43°C for 30 min to mimic heat stress. The study was further examined if aloin has any effect on heat stress-induced oxidative stress. We found that aloin protected Hs68 cells against heat stress-induced damage, as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay. Aloin protected Hs68 cells by regulating reactive oxygen species production and increasing the levels of glutathione, cytosolic and mitochondrial superoxide dismutase. Aloin also prevented the elevation of thiobarbituric acid reactive substances and the reduction of 8-OH-dG induced by heat stress. These results indicated that aloin protected human skin fibroblasts from heat stress-induced oxidative stress damage by regulating the oxidative defense system.

  12. Aloin Protects Skin Fibroblasts from Heat Stress-Induced Oxidative Stress Damage by Regulating the Oxidative Defense System

    PubMed Central

    Wang, Yu-Ren; Tsai, Hsin-I; Yu, Huang-Ping

    2015-01-01

    Oxidative stress is commonly involved in the pathogenesis of skin damage induced by environmental factors, such as heat stress. Skin fibroblasts are responsible for the connective tissue regeneration and the skin recovery from injury. Aloin, a bioactive compound in Aloe vera, has been reported to have various pharmacological activities, such as anti-inflammatory effects. The aim of this study was to investigate the protective effect of aloin against heat stress-mediated oxidative stress in human skin fibroblast Hs68 cells. Hs68 cells were first incubated at 43°C for 30 min to mimic heat stress. The study was further examined if aloin has any effect on heat stress-induced oxidative stress. We found that aloin protected Hs68 cells against heat stress-induced damage, as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay. Aloin protected Hs68 cells by regulating reactive oxygen species production and increasing the levels of glutathione, cytosolic and mitochondrial superoxide dismutase. Aloin also prevented the elevation of thiobarbituric acid reactive substances and the reduction of 8-OH-dG induced by heat stress. These results indicated that aloin protected human skin fibroblasts from heat stress-induced oxidative stress damage by regulating the oxidative defense system. PMID:26637174

  13. Finite element residual stress analysis of induction heating bended ferritic steel piping

    SciTech Connect

    Kima, Jong Sung; Kim, Kyoung-Soo; Oh, Young-Jin; Chang, Hyung-Young; Park, Heung-Bae

    2014-10-06

    Recently, there is a trend to apply the piping bended by induction heating process to nuclear power plants. Residual stress can be generated due to thermo-mechanical mechanism during the induction heating bending process. It is well-known that the residual stress has important effect on crack initiation and growth. The previous studies have focused on the thickness variation. In part, some studies were performed for residual stress evaluation of the austenitic stainless steel piping bended by induction heating. It is difficult to find the residual stresses of the ferritic steel piping bended by the induction heating. The study assessed the residual stresses of induction heating bended ferriticsteel piping via finite element analysis. As a result, it was identified that high residual stresses are generated on local outersurface region of the induction heating bended ferritic piping.

  14. Finite element residual stress analysis of induction heating bended ferritic steel piping

    NASA Astrophysics Data System (ADS)

    Kima, Jong Sung; Kim, Kyoung-Soo; Oh, Young-Jin; Chang, Hyung-Young; Park, Heung-Bae

    2014-10-01

    Recently, there is a trend to apply the piping bended by induction heating process to nuclear power plants. Residual stress can be generated due to thermo-mechanical mechanism during the induction heating bending process. It is well-known that the residual stress has important effect on crack initiation and growth. The previous studies have focused on the thickness variation. In part, some studies were performed for residual stress evaluation of the austenitic stainless steel piping bended by induction heating. It is difficult to find the residual stresses of the ferritic steel piping bended by the induction heating. The study assessed the residual stresses of induction heating bended ferriticsteel piping via finite element analysis. As a result, it was identified that high residual stresses are generated on local outersurface region of the induction heating bended ferritic piping.

  15. Quantifying livestock responses for heat stress management: a review

    NASA Astrophysics Data System (ADS)

    Nienaber, J. A.; Hahn, G. L.; Eigenberg, R. A.

    Hot weather challenges livestock production but technology exists to offset the challenge if producers have made appropriate strategic decisions. Key issues include understanding the hazards of heat stress, being prepared to offer relief from the heat, recognizing when an animal is in danger, and taking appropriate action. This paper describes our efforts to develop biological response functions; assesses climatic probabilities and performs associated risk analyses; provides inputs for computer models used to make environmental management decisions; and evaluates threshold temperatures as estimates of critical temperature limits for swine, cattle and sheep.

  16. Heat Stress Alters Ruminal Fermentation and Digesta Characteristics, and Behavior in Lactating Dairy Cattle

    USDA-ARS?s Scientific Manuscript database

    In a study designed to assess the impact and interaction of nonfiber carbohydrates (NFC) and ruminally degradable protein (RDP) on ruminal characteristics and animal behavior, animals experienced heat stress in the first period (HS), and no/greatly reduced heat stress (NHS) in the second period, all...

  17. Outdoor occupational environments and heat stress in IRAN.

    PubMed

    Heidari, Hamidreza; Golbabaei, Farideh; Shamsipour, Aliakbar; Rahimi Forushani, Abbas; Gaeini, Abbasali

    2015-01-01

    The present study aimed at demonstrating the heat stress situation (distribution and intensity) based on a standard and common heat stress index, Wet Bulb Globe Temperature (WBGT), during hot seasons and interpret the obtained results considering global warming and rising temperature in different parts of the country based on climate changes studied in Iran. Heat stress assessment was done using WBGT index. Environmental parameters were measured simultaneously in the early, middle and end of shift work. The personal parameters including cloth thermal insulation and metabolic rate of 242 participants from 9 climatic categories were recorded for estimating effective WBGT (measured WBGT plus cloth adjustment factor as well as metabolic rate effect). The values of the indicator were categorized in the statistical software media and then linked to the climatic zoning of the data in the GIS information layers, in which, WBGT values relating to selected stations were given generalization to similar climatic regionalization. The obtained results showed that in the summer about 60 % and more than 75 % of the measurements relating to 12 pm and 3 pm, respectively, were in heat stress situations (i.e. the average amount of heat stress index was higher than 28 °C). These values were found to be about 20-25 % in the spring. Moreover, only in the early hours of shift work in spring could safe conditions be seen throughout the country. This situation gradually decreased in the middle of the day hours and was replaced by the warning status and stress. And finally, in the final hours of shift work thermal stresses reached their peaks. These conditions for the summer were worse. Regarding several studies related to climate change in Iran and the results of present study, heat stress, especially in the central and southern parts of Iran, can be exacerbated in the decades to come if climate change and rising temperature occurs. Therefore, paying attention to this critical issue

  18. Future Changes in Heat Stress over East Asia Resulting from Different Target Temperature Increases

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Min; Min, Seung-Ki

    2017-04-01

    In assessing the impact of global warming, it is very important to understand the change in comprehensive heat stress as a function of several variables, rather than only temperature. Furthermore, in order to assess and implement the target temperature goals of the 2015 Paris Agreement, it is essential to have effective and scientifically valid information to predict and measure regional impact. In this study, the future changes in summer heat stress over East Asia were examined based on the Wet-Bulb Globe Temperature (WBGT) using CMIP5 multimodel simulations (historical and RCP scenario simulations), and differences in heat stress changes were assessed between 1.5-degree and 2-degree warmer worlds. Future boreal summer heat stress of land regions over East Asia, in excess of the 50-year return value, shows a rapid and nonlinear increase from the 2000s, and it is expected that severe heat stress will occur in the overall East Asia region by the 2040s. In particular, extreme heat stress events were found to occur much more frequently than summer mean intensity of heat stress. Comparisons of the increase in heat stress between 1.5-degree and 2-degree warmer worlds indicated a 20% decrease in the area experiencing severe heat stress over East Asia, and relatively large benefits (i.e. less frequent and less severe heat stress) were found in the southeastern China, the Korean Peninsula and Japan compared to other regions. Further, the equilibrium scenarios showed a larger increase in heat stress over East Asia than the transient scenarios, particularly in case of the 1.5-degree warmer world, which was found due to warmer water in the northwestern North Pacific in the equilibrium scenarios.

  19. Contrasting urban and rural heat stress responses to climate change

    NASA Astrophysics Data System (ADS)

    Fischer, E. M.; Oleson, K. W.; Lawrence, D. M.

    2012-02-01

    Hot temperatures in combination with high humidity cause human discomfort and may increase morbidity and mortality. A global climate model with an embedded urban model is used to explore the urban-rural contrast in the wet-bulb globe temperature, a heat stress index accounting for temperature and humidity. Wet-bulb globe temperatures are calculated at each model time step to resolve the heat stress diurnal cycle. The model simulates substantially higher heat stress in urban areas compared to neighbouring rural areas. Urban humidity deficit only weakly offsets the enhanced heat stress due to the large night-time urban heat island. The urban-rural contrast in heat stress is most pronounced at night and over mid-latitudes and subtropics. During heatwaves, the urban heat stress amplification is particularly pronounced. Heat stress strongly increases with doubled CO2 concentrations over both urban and rural surfaces. The tropics experience the greatest increase in number of high-heat-stress nights, despite a relatively weak ˜2°C warming. Given the lack of a distinct annual cycle and high relative humidity, the modest tropical warming leads to exceedance of the present-day record levels during more than half of the year in tropical regions, where adaptive capacity is often low. While the absolute urban and rural heat stress response to 2 × CO2 is similar, the occurrence of nights with extremely high heat stress increases more in cities than surrounding rural areas.

  20. Controlled Heat Stress Promotes Myofibrillogenesis during Myogenesis.

    PubMed

    Guo, Qiongyu; Miller, Devin; An, Hongying; Wang, Howard; Lopez, Joseph; Lough, Denver; He, Ling; Kumar, Anand

    2016-01-01

    Hyperthermia therapy has recently emerged as a clinical modality used to finely tune heat stress inside the human body for various biomedical applications. Nevertheless, little is known regarding the optimal timing or temperature of heat stress that is needed to achieve favorable results following hyperthermia therapy for muscle regeneration purposes. The regeneration of skeletal muscle after injury is a highly complex and coordinated process that involves a multitude of cellular mechanisms. The main objective of this study was to characterize the effects of hyperthermal therapy on the overall behavior of myoblasts during myogenic differentiation. Various cellular processes, including myogenesis, myofibrillogenesis, hypertrophy/atrophy, and mitochondrial biogenesis, were studied using systematic cellular, morphological, and pathway-focused high-throughput gene expression profiling analyses. We found that C2C12 myoblasts exhibited distinctive time and temperature-dependence in biosynthesis and regulatory events during myogenic differentiation. Specifically, we for the first time observed that moderate hyperthermia at 39°C favored the growth of sarcomere in myofibrils at the late stage of myogenesis, showing universal up-regulation of characteristic myofibril proteins. Characteristic myofibrillogenesis genes, including heavy polypeptide 1 myosin, heavy polypeptide 2 myosin, alpha 1 actin, nebulin and titin, were all significantly upregulated (p<0.01) after C2C12 cells differentiated at 39°C over 5 days compared with the control cells cultured at 37°C. Furthermore, moderate hyperthermia enhanced myogenic differentiation, with nucleus densities per myotube showing 2.2-fold, 1.9-fold and 1.6-fold increases when C2C12 cells underwent myogenic differentiation at 39°C over 24 hours, 48 hours and 72 hours, respectively, as compared to the myotubes that were not exposed to heat stress. Yet, atrophy genes were sensitive even to moderate hyperthermia, indicating that

  1. Controlled Heat Stress Promotes Myofibrillogenesis during Myogenesis

    PubMed Central

    Guo, Qiongyu; Miller, Devin; An, Hongying; Wang, Howard; Lopez, Joseph; Lough, Denver; He, Ling; Kumar, Anand

    2016-01-01

    Hyperthermia therapy has recently emerged as a clinical modality used to finely tune heat stress inside the human body for various biomedical applications. Nevertheless, little is known regarding the optimal timing or temperature of heat stress that is needed to achieve favorable results following hyperthermia therapy for muscle regeneration purposes. The regeneration of skeletal muscle after injury is a highly complex and coordinated process that involves a multitude of cellular mechanisms. The main objective of this study was to characterize the effects of hyperthermal therapy on the overall behavior of myoblasts during myogenic differentiation. Various cellular processes, including myogenesis, myofibrillogenesis, hypertrophy/atrophy, and mitochondrial biogenesis, were studied using systematic cellular, morphological, and pathway-focused high-throughput gene expression profiling analyses. We found that C2C12 myoblasts exhibited distinctive time and temperature-dependence in biosynthesis and regulatory events during myogenic differentiation. Specifically, we for the first time observed that moderate hyperthermia at 39°C favored the growth of sarcomere in myofibrils at the late stage of myogenesis, showing universal up-regulation of characteristic myofibril proteins. Characteristic myofibrillogenesis genes, including heavy polypeptide 1 myosin, heavy polypeptide 2 myosin, alpha 1 actin, nebulin and titin, were all significantly upregulated (p<0.01) after C2C12 cells differentiated at 39°C over 5 days compared with the control cells cultured at 37°C. Furthermore, moderate hyperthermia enhanced myogenic differentiation, with nucleus densities per myotube showing 2.2-fold, 1.9-fold and 1.6-fold increases when C2C12 cells underwent myogenic differentiation at 39°C over 24 hours, 48 hours and 72 hours, respectively, as compared to the myotubes that were not exposed to heat stress. Yet, atrophy genes were sensitive even to moderate hyperthermia, indicating that

  2. Human Adaptations to Heat and Cold Stress

    DTIC Science & Technology

    2002-04-01

    Heat and Cold Stress Michael N. Sawka, Ph.D. US Army Research Institute of Environmental Medicine 42 Kansas Street Natick, MA 01760-5007, USA John W...Castellani, Ph.D. US Army Research Institute of Environmental Medicine 42 Kansas Street Natick, MA 01760-5007, USA Kent B. Pandolf, Ph.D. US Army...Research Institute of Environmental Medicine 42 Kansas Street Natick, MA 01760-5007, USA Andrew J. Young, Ph.D. US Army Research Institute of Environmental

  3. Aspirin upregulates αB-Crystallin to protect the myocardium against heat stress in broiler chickens

    PubMed Central

    Tang, Shu; Yin, Bin; Song, Erbao; Chen, Hongbo; Cheng, Yanfen; Zhang, Xiaohui; Bao, Endong; Hartung, Joerg

    2016-01-01

    We established in vivo and in vitro models to investigate the role of αB-Crystallin (CryAB) and assess the ability of aspirin (ASA) to protect the myocardium during prolonged heat stress. Thirty-day-old chickens were divided into three groups (n = 90): heat stress (HS, 40±1 °C); ASA(−)HS(+), 1 mg/kg ASA orally 2 h before heat stress; and ASA(+)HS(−), pretreated with aspirin, no heat stress (25 °C). Hearts were excised after 0, 1, 2, 3, 5, 7, 10, 15 and 24 h. Heat stress increased body temperature, though the ASA(−)HS(+) group had significantly higher temperatures than the ASA(+)HS(+) group at all time points. Compared to ASA(+)HS(+), the ASA(−)HS(+) group displayed increased sensitivity to heat stress. Pathological analysis revealed the ASA (+)HS(+) myocardium showed less severe changes (narrowed, chaotic fibers; fewer necrotic cells) than the ASA(−)HS(+) group (bleeding and extensive cell death). In vitro, ASA-pretreatment significantly increased primary chicken myocardial cell survival during heat stress. ELISAs indicated ASA induced CryAB in vivo to protect against heat stress-induced myocardial damage, but ASA did not induce CryAB in primary chicken myocardial cells. The mechanisms by which ASA induces the expression of CryAB in vivo and protects the myocardium during heat stress merit further research. PMID:27857180

  4. Feasibility assessment of a tunnel-ventilated, water-padded barn on alleviation of heat stress for lactating Holstein cows in a humid area.

    PubMed

    Shiao, T F; Chen, J C; Yang, D W; Lee, S N; Lee, C F; Cheng, W T K

    2011-11-01

    The use of evaporative cooling for mitigating heat stress in lactating cows in humid areas is controversial. In Taiwan, Holstein cow performance is significantly restricted by hot and humid weather. This study investigated the efficacy of using a tunnel-ventilated, water-padded freestall (TP) barn for reducing heat stress in lactating cows. From August to October 2006, 36 cows allocated in a 3×3 Latin square were raised in 3 barn cooling treatments: a conventional freestall barn with fans and sprinklers in the feed line (Fan+SP, control), a TP barn, and a TP barn with sprinkler cooling (TP+SP). Daytime air speeds in the 3 barns were 1.23, 2.38, and 2.06 m/s, respectively. Both TP barns were more efficient than the control in reducing the daytime temperature and temperature-humidity index. The barn temperature was <26°C for an extra 4.2h per day, but the relative humidity was >96% in both TP barns. Cows in both TP barns had higher respiration rates and skin temperatures at 0300 h than cows in the Fan+SP barn. The TP environment increased the cows' serum cholesterol level and the activities of alkaline phosphatase and alanine aminotransferase, but blood partial pressure of CO(2) was not affected. Vaginal temperature was persistently high in cows in the TP barn; in the 2 SP barns, it decreased 0.4 to 0.6°C following sprinkling and milking. The intake activity and rumen digestion of cows raised in the 3 environments were similar. Cows in both TP barns ingested more dry matter. Cows in the TP+SP barn tended to produce more milk than those in the Fan+SP barn (25.4 vs. 24.7 kg). Although heat stress was not completely alleviated in these 3 barns, the TP+SP treatment resolved the negative effect of a previous TP barn built in 2004 on intake and milk yield by increasing air speed and using sprinkler cooling. Thus, it is expected that TP+SP barns will be beneficial in regions with high humidity. Adequate air speed and sprinkler cooling are likely to be key factors for

  5. Sprint performance under heat stress: A review.

    PubMed

    Girard, O; Brocherie, F; Bishop, D J

    2015-06-01

    Training and competition in major track-and-field events, and for many team or racquet sports, often require the completion of maximal sprints in hot (>30 °C) ambient conditions. Enhanced short-term (<30 s) power output or single-sprint performance, resulting from transient heat exposure (muscle temperature rise), can be attributed to improved muscle contractility. Under heat stress, elevations in skin/core temperatures are associated with increased cardiovascular and metabolic loads in addition to decreasing voluntary muscle activation; there is also compelling evidence to suggest that large performance decrements occur when repeated-sprint exercise (consisting of brief recovery periods between sprints, usually <60 s) is performed in hot compared with cool conditions. Conversely, poorer intermittent-sprint performance (recovery periods long enough to allow near complete recovery, usually 60-300 s) in hotter conditions is solely observed when exercise induces marked hyperthermia (core temperature >39 °C). Here we also discuss strategies (heat acclimatization, precooling, hydration strategies) employed by "sprint" athletes to mitigate the negative influence of higher environmental temperatures.

  6. Heat stress-induced response of the proteomes of leaves from Salvia splendens Vista and King

    PubMed Central

    2013-01-01

    Background Salvia splendens Ker-Gawl, most commonly used in China to add a splash of brilliant color to the surroundings during the warm season, is subject to heat stress, which can greatly affect its growth and yield. Results To gain a comprehensive understanding of heat-tolerance mechanisms of S. splendens, we assessed the heat-stress responses and characterized the proteomes of leaves from two varieties, Vista (heat resistant) and King (heat sensitive). Denaturing two-dimensional gel electrophoresis (2–DE) and tandem mass spectrometry were used to identify heat-responsive proteins. Heat stress induced the reversible inactivation of photosystem II reaction centers and increased the amounts of antioxidative enzymes, thereby decreasing oxidative damage. Vista leaves had a much greater ability than King leaves to develop light-protective and oxygen-scavenging systems in response to heat stress. More than 1213 leaf proteome spots were reproducibly detected in the gels, with a total of 33 proteins in each leaf type differentially regulated when Salvia splendens were heat stress treated. Of these proteins, 23 and 28 from Vista and King, respectively, were identified. Conclusions Most of the identified proteins are involved in photosynthesis, metabolism, protein processing, or stress response, indicating that many different processes work together to establish a new cellular homeostasis in response to heat stress. PMID:23773552

  7. Heat stress causes substantial labour productivity loss in Australia

    NASA Astrophysics Data System (ADS)

    Zander, Kerstin K.; Botzen, Wouter J. W.; Oppermann, Elspeth; Kjellstrom, Tord; Garnett, Stephen T.

    2015-07-01

    Heat stress at the workplace is an occupational health hazard that reduces labour productivity. Assessment of productivity loss resulting from climate change has so far been based on physiological models of heat exposure. These models suggest productivity may decrease by 11-27% by 2080 in hot regions such as Asia and the Caribbean, and globally by up to 20% in hot months by 2050. Using an approach derived from health economics, we describe self-reported estimates of work absenteeism and reductions in work performance caused by heat in Australia during 2013/2014. We found that the annual costs were US$655 per person across a representative sample of 1,726 employed Australians. This represents an annual economic burden of around US$6.2 billion (95% CI: 5.2-7.3 billion) for the Australian workforce. This amounts to 0.33 to 0.47% of Australia’s GDP. Although this was a period when many Australians experienced what is at present considered exceptional heat, our results suggest that adaptation measures to reduce heat effects should be adopted widely if severe economic impacts from labour productivity loss are to be avoided if heat waves become as frequent as predicted.

  8. Work-related heat stress concerns in automotive industries: a case study from Chennai, India.

    PubMed

    Ayyappan, Ramalingam; Sankar, Sambandam; Rajkumar, Paramasivan; Balakrishnan, Kalpana

    2009-11-11

    Work-related heat stress assessments, the quantification of thermal loads and their physiological consequences have mostly been performed in non-tropical developed country settings. In many developing countries (many of which are also tropical), limited attempts have been made to create detailed job-exposure profiles for various sectors. We present here a case study from Chennai in southern India that illustrates the prevalence of work-related heat stress in multiple processes of automotive industries and the efficacy of relatively simple controls in reducing prevalence of the risk through longitudinal assessments. We conducted workplace heat stress assessments in automotive and automotive parts manufacturing units according to the protocols recommended by NIOSH, USA. Sites for measurements included indoor locations with process-generated heat exposure, indoor locations without direct process-generated heat exposure and outdoor locations. Nearly 400 measurements of heat stress were made over a four-year period at more than 100 locations within eight units involved with automotive or automotive parts manufacturing in greater Chennai metropolitan area. In addition, cross-sectional measurements were made in select processes of glass manufacturing and textiles to estimate relative prevalence of heat stress. Results indicate that many processes even in organised large-scale industries have yet to control heat stress-related hazards adequately. Upwards of 28% of workers employed in multiple processes were at risk of heat stress-related health impairment in the sectors assessed. Implications of longitudinal baseline data for assessing efficacy of interventions as well as modelling potential future impacts from climate change (through contributions from worker health and productivity impairments consequent to increases in ambient temperature) are described. The study re-emphasises the need for recognising heat stress as an important occupational health risk in both formal

  9. Work-related heat stress concerns in automotive industries: a case study from Chennai, India

    PubMed Central

    Ayyappan, Ramalingam; Sankar, Sambandam; Rajkumar, Paramasivan; Balakrishnan, Kalpana

    2009-01-01

    Background Work-related heat stress assessments, the quantification of thermal loads and their physiological consequences have mostly been performed in non-tropical developed country settings. In many developing countries (many of which are also tropical), limited attempts have been made to create detailed job-exposure profiles for various sectors. We present here a case study from Chennai in southern India that illustrates the prevalence of work-related heat stress in multiple processes of automotive industries and the efficacy of relatively simple controls in reducing prevalence of the risk through longitudinal assessments. Methods We conducted workplace heat stress assessments in automotive and automotive parts manufacturing units according to the protocols recommended by NIOSH, USA. Sites for measurements included indoor locations with process-generated heat exposure, indoor locations without direct process-generated heat exposure and outdoor locations. Nearly 400 measurements of heat stress were made over a four-year period at more than 100 locations within eight units involved with automotive or automotive parts manufacturing in greater Chennai metropolitan area. In addition, cross-sectional measurements were made in select processes of glass manufacturing and textiles to estimate relative prevalence of heat stress. Results Results indicate that many processes even in organised large-scale industries have yet to control heat stress-related hazards adequately. Upwards of 28% of workers employed in multiple processes were at risk of heat stress-related health impairment in the sectors assessed. Implications of longitudinal baseline data for assessing efficacy of interventions as well as modelling potential future impacts from climate change (through contributions from worker health and productivity impairments consequent to increases in ambient temperature) are described. Conclusions The study re-emphasises the need for recognising heat stress as an important

  10. Phenotypic, physiological and malt quality analyses of US barley varieties subjected to short periods of heat and drought stress

    USDA-ARS?s Scientific Manuscript database

    Drought and heat are major abiotic stresses that significantly reduce crop yield and seed quality. In this study, we examined the impact of heat, drought and combined effect of heat and drought stress imposed during the grain filling stage in 18 US spring barley varieties. These impacts were assesse...

  11. Heat stress-induced life span extension in yeast.

    PubMed

    Shama, S; Lai, C Y; Antoniazzi, J M; Jiang, J C; Jazwinski, S M

    1998-12-15

    The yeast Saccharomyces cerevisiae has a limited life span that can be measured by the number of times individual cells divide. Several genetic manipulations have been shown to prolong the yeast life span. However, environmental effects that extend longevity have been largely ignored. We have found that mild, nonlethal heat stress extended yeast life span when it was administered transiently early in life. The increased longevity was due to a reduction in the mortality rate that persisted over many cell divisions (generations) but was not permanent. The genes RAS1 and RAS2 were necessary to observe this effect of heat stress. The RAS2 gene is consistently required for maintenance of life span when heat stress is chronic or in its extension when heat stress is transient or absent altogether. RAS1, on the other hand, appears to have a role in signaling life extension induced by transient, mild heat stress, which is distinct from its life-span-curtailing effect in the absence of stress and its lack of involvement in the response to chronic heat stress. This distinction between the RAS genes may be partially related to their different effects on growth-promoting genes and stress-responsive genes. The ras2 mutation clearly hindered resumption of growth and recovery from stress, while the ras1 mutation did not. The HSP104 gene, which is largely responsible for induced thermotolerance in yeast, was necessary for life extension induced by transient heat stress. An interaction between mitochondrial petite mutations and heat stress was found, suggesting that mitochondria may be necessary for life extension by transient heat stress. The results raise the possibility that the RAS genes and mitochondria may play a role in the epigenetic inheritance of reduced mortality rate afforded by transient, mild heat stress.

  12. Effects of exogenous desmopressin on a model of heat stress nephropathy in mice.

    PubMed

    Roncal-Jimenez, Carlos A; Milagres, Tamara; Andres-Hernando, Ana; Kuwabara, Masanari; Jensen, Thomas; Song, Zhilin; Bjornstad, Petter; Garcia, Gabriela E; Sato, Yuka; Sanchez-Lozada, Laura G; Lanaspa, Miguel A; Johnson, Richard J

    2017-03-01

    Recurrent heat stress and dehydration have recently been shown experimentally to cause chronic kidney disease (CKD). One potential mediator may be vasopressin, acting via the type 2 vasopressin receptor (V2 receptor). We tested the hypothesis that desmopressin accelerates CKD in mice subjected to heat stress and recurrent dehydration. Recurrent exposure to heat with limited water availability was performed in male mice over a 5-wk period, with one group receiving desmopressin two times daily and the other group receiving vehicle. Two additional control groups were not exposed to heat or dehydration and received vehicle or desmopressin. The effects of the treatment on renal injury were assessed. Heat stress and recurrent dehydration induced functional changes (albuminuria, elevated urinary neutrophil gelatinase-associated protein), glomerular changes (mesangiolysis, matrix expansion), and tubulointerstitial changes (fibrosis, inflammation). Desmopressin also induced albuminuria, glomerular changes, and tubulointerstitial fibrosis in normal animals and also exacerbated injury in mice with heat stress nephropathy. Both heat stress and/or desmopressin were also associated with activation of the polyol pathway in the renal cortex, likely due to increased interstitial osmolarity. Our studies document both glomerular and tubulointerstitial injury and inflammation in heat stress nephropathy and may be clinically relevant to the pathogenesis of Mesoamerican nephropathy. Our data also suggest that vasopressin may play a role in the pathogenesis of the renal injury of heat stress nephropathy, likely via a V2 receptor-dependent pathway.

  13. Spectral characteristics of skin sympathetic nerve activity in heat-stressed humans.

    PubMed

    Cui, Jian; Sathishkumar, Mithra; Wilson, Thad E; Shibasaki, Manabu; Davis, Scott L; Crandall, Craig G

    2006-04-01

    Skin sympathetic nerve activity (SSNA) exhibits low- and high-frequency spectral components in normothermic subjects. However, spectral characteristics of SSNA in heat-stressed subjects are unknown. Because the main components of the integrated SSNA during heat stress (sudomotor/vasodilator activities) are different from those during normothermia and cooling (vasoconstrictor activity), we hypothesize that spectral characteristics of SSNA in heat-stressed subjects will be different from those in subjects subjected to normothermia or cooling. In 17 healthy subjects, SSNA, electrocardiogram, arterial blood pressure (via Finapres), respiratory activity, and skin blood flow were recorded during normothermia and heat stress. In 7 of the 17 subjects, these variables were also recorded during cooling. Spectral characteristics of integrated SSNA, R-R interval, beat-by-beat mean blood pressure, skin blood flow variability, and respiratory excursions were assessed. Heat stress and cooling significantly increased total SSNA. SSNA spectral power in the low-frequency (0.03-0.15 Hz), high-frequency (0.15-0.45 Hz), and very-high-frequency (0.45-2.5 Hz) regions was significantly elevated by heat stress and cooling. Interestingly, heat stress caused a greater relative increase of SSNA spectral power within the 0.45- to 2.5-Hz region than in the other spectral ranges; cooling did not show this effect. Differences in the SSNA spectral distribution between normothermia/cooling and heat stress may reflect different characteristics of central modulation of vasoconstrictor and sudomotor/vasodilator activities.

  14. Nutritional interventions to alleviate the negative consequences of heat stress.

    PubMed

    Rhoads, Robert P; Baumgard, Lance H; Suagee, Jessica K; Sanders, Sara R

    2013-05-01

    Energy metabolism is a highly coordinated process, and preferred fuel(s) differ among tissues. The hierarchy of substrate use can be affected by physiological status and environmental factors including high ambient temperature. Unabated heat eventually overwhelms homeothermic mechanisms resulting in heat stress, which compromises animal health, farm animal production, and human performance. Various aspects of heat stress physiology have been extensively studied, yet a clear understanding of the metabolic changes occurring at the cellular, tissue, and whole-body levels in response to an environmental heat load remains ill-defined. For reasons not yet clarified, circulating nonesterified fatty acid levels are reduced during heat stress, even in the presence of elevated stress hormones (epinephrine, glucagon, and cortisol), and heat-stressed animals often have a blunted lipolytic response to catabolic signals. Either directly because of or in coordination with this, animals experiencing environmental hyperthermia exhibit a shift toward carbohydrate use. These metabolic alterations occur coincident with increased circulating basal and stimulated plasma insulin concentrations. Limited data indicate that proper insulin action is necessary to effectively mount a response to heat stress and minimize heat-induced damage. Consistent with this idea, nutritional interventions targeting increased insulin action may improve tolerance and productivity during heat stress. Further research is warranted to uncover the effects of heat on parameters associated with energy metabolism so that more appropriate and effective treatment methodologies can be designed.

  15. Urban Heat Wave Hazard Assessment

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Jedlovec, Gary; Meyer, Paul J.; LaFontaine, Frank J.; Crane, Dakota L.

    2016-01-01

    Heat waves are the largest cause of environment-related deaths globally. On average, over 6,000 people in the United States alone are hospitalized each summer due to excessive heat. Key elements leading to these disasters are elevated humidity and the urban heat island effect, which act together to increase apparent temperature and amplify the effects of a heat wave. Urban demographics and socioeconomic factors also play a role in determining individual risk. Currently, advisories of impending heat waves are often too generalized, with limited or no spatial variability over urban regions. This frequently contributes to a lack of specific response on behalf of the population. A goal of this project is to develop a product that has the potential to provide more specific heat wave guidance invoking greater awareness and action.

  16. Acute volume expansion preserves orthostatic tolerance during whole-body heat stress in humans

    PubMed Central

    Keller, David M; Low, David A; Wingo, Jonathan E; Brothers, R Matthew; Hastings, Jeff; Davis, Scott L; Crandall, Craig G

    2009-01-01

    Whole-body heat stress reduces orthostatic tolerance via a yet to be identified mechanism(s). The reduction in central blood volume that accompanies heat stress may contribute to this phenomenon. The purpose of this study was to test the hypothesis that acute volume expansion prior to the application of an orthostatic challenge attenuates heat stress-induced reductions in orthostatic tolerance. In seven normotensive subjects (age, 40 ± 10 years: mean ±s.d.), orthostatic tolerance was assessed using graded lower-body negative pressure (LBNP) until the onset of symptoms associated with ensuing syncope. Orthostatic tolerance (expressed in cumulative stress index units, CSI) was determined on each of 3 days, with each day having a unique experimental condition: normothermia, whole-body heating, and whole-body heating + acute volume expansion. For the whole-body heating + acute volume expansion experimental day, dextran 40 was rapidly infused prior to LBNP sufficient to return central venous pressure to pre-heat stress values. Whole-body heat stress alone reduced orthostatic tolerance by ∼80% compared to normothermia (938 ± 152 versus 182 ± 57 CSI; mean ±s.e.m., P < 0.001). Acute volume expansion during whole-body heating completely ameliorated the heat stress-induced reduction in orthostatic tolerance (1110 ± 69 CSI, P < 0.001). Although heat stress results in many cardiovascular and neural responses that directionally challenge blood pressure regulation, reduced central blood volume appears to be an underlying mechanism responsible for impaired orthostatic tolerance in the heat-stressed human. PMID:19139044

  17. Management of heat stress in the livestock industry

    USDA-ARS?s Scientific Manuscript database

    Heat stress costs the animal industry over $1.7 billion annually. Annual losses average $369 million in the beef cattle industry and $299 million in the swine industry. The impacts of a single heat stress event on individual animals are quite varied. Brief events often cause little or no effect. ...

  18. Rubisco activase and wheat productivity under heat stress conditions

    USDA-ARS?s Scientific Manuscript database

    Rubisco activase (RCA) constrains the photosynthetic potential of plants at high temperature (heat stress). We hypothesized that endogenous levels of RCA could serve as an important determinant of plant productivity under heat stress conditions. In this study, we investigated the possible relation...

  19. Assessing Stress in Cancer Patients

    PubMed Central

    Golden-Kreutz, Deanna M.; Browne, Michael W.; Frierson, Georita M.; Andersen, Barbara L.

    2009-01-01

    Using the Perceived Stress Scale (PSS), perceptions of global stress were assessed in 111 women following breast cancer surgery and at 12 and 24 months later. This is the first study to factor analyze the PSS. The PSS data were factor analyzed each time using exploratory factor analysis with oblique direct quartimin rotation. Goodness-of-fit indices (root mean square error of approximation [RMSEA]), magnitude and pattern of factor loadings, and confidence interval data revealed a two-factor solution of positive versus negative stress items. The findings, replicated across time, also indicate factor stability. Hierarchical factor analyses supported a second-order factor of “perceived stress.” This alternative factor model of the PSS is presented along with observations regarding the measure's use in cancer research. PMID:15358877

  20. A systems biology approach to heat stress, heat injury, and heat stroke

    NASA Astrophysics Data System (ADS)

    Stallings, Jonathan D.; Ippolito, Danielle L.

    2015-05-01

    Heat illness is a major source of injury for military populations in both deployed and training settings. Developing tools to help leaders enhance unit performance while reducing the risk of injury is of paramount importance to the military. Here, we review our recent systems biology approaches to heat stress in order to develop a 3-dimensional (3D) realistic thermoregulation model, identify the molecular basis and mediators of injury, and characterize associated biomarkers. We discuss the implications of our work, future directions, and the type of tools necessary to enhance force health protection in the future.

  1. Effects of heat stress on day-old broiler chicks.

    PubMed

    Ernst, R A; Weathers, W W; Smith, J

    1984-09-01

    Short-term heat stress can occur when chicks are transported from the hatchery to growing facilities. Two experiments were conducted to determine the possible effects of short-term heat stress on growth and feed conversion of broiler (Hubbard X Hubbard) chicks. The heat stress was accomplished by placing chicks in Jamesway 252 incubators at dry bulb temperatures ranging from 40 to 45 C for variable times. Growth, feed consumption, and mortality were measured for 16 days following the heat stress. Short sublethal heat stress significantly reduced growth rate to 16 days in these experiments without any effect on feed conversion ratio. The results indicate that the hatchery industry should avoid overheating chicks even for periods as short as 1 hr.

  2. Increased heat shock protein expression after stress in Japanese quail.

    PubMed

    Hoekstra, K A; Iwama, G K; Nichols, C R; Godin, D V; Cheng, K M

    1998-12-01

    Heat shock proteins (HSPs) have been shown to provide information on the biological impact of environmental stress to organisms, yet none have investigated the HSP response to stress in birds. Japanese quail were exposed to seven different stressors (mild restraint, loud noise, inescapable irritation, cold temperature, isolation in darkness, and two stressful social situations) and expression of HSP30, 60, 70, and 90 in heart, liver, lung, kidney and gonads was examined. Tonic Immobility (TI) tests were also conducted to assess whether the stressors increased fear response. Increased expression of HSP70 was found in the myocardial tissue of birds exposed to loud noise, inescapable irritation, cold temperature, and isolation in darkness. Increased expression of other HSPs was not apparent in the heart or any of the other all tissues examined. Longer TI was observed only in birds exposed to the noise stress. Evidence is presented that a fairly wide range of stressors caused increased expression of HSP70 in the Japanese quail myocardial tissue and that HSPs may provide useful biomarkers for the study of environmental stress in birds.

  3. Effects of cold stress and heat stress on coral fluorescence in reef-building corals

    PubMed Central

    Roth, Melissa S.; Deheyn, Dimitri D.

    2013-01-01

    Widespread temperature stress has caused catastrophic coral bleaching events that have been devastating for coral reefs. Here, we evaluate whether coral fluorescence could be utilized as a noninvasive assessment for coral health. We conducted cold and heat stress treatments on the branching coral Acropora yongei, and found that green fluorescent protein (GFP) concentration and fluorescence decreased with declining coral health, prior to initiation of bleaching. Ultimately, cold-treated corals acclimated and GFP concentration and fluorescence recovered. In contrast, heat-treated corals eventually bleached but showed strong fluorescence despite reduced GFP concentration, likely resulting from the large reduction in shading from decreased dinoflagellate density. Consequently, GFP concentration and fluorescence showed distinct correlations in non-bleached and bleached corals. Green fluorescence was positively correlated with dinoflagellate photobiology, but its closest correlation was with coral growth suggesting that green fluorescence could be used as a physiological proxy for health in some corals. PMID:23478289

  4. Effects of cold stress and heat stress on coral fluorescence in reef-building corals.

    PubMed

    Roth, Melissa S; Deheyn, Dimitri D

    2013-01-01

    Widespread temperature stress has caused catastrophic coral bleaching events that have been devastating for coral reefs. Here, we evaluate whether coral fluorescence could be utilized as a noninvasive assessment for coral health. We conducted cold and heat stress treatments on the branching coral Acropora yongei, and found that green fluorescent protein (GFP) concentration and fluorescence decreased with declining coral health, prior to initiation of bleaching. Ultimately, cold-treated corals acclimated and GFP concentration and fluorescence recovered. In contrast, heat-treated corals eventually bleached but showed strong fluorescence despite reduced GFP concentration, likely resulting from the large reduction in shading from decreased dinoflagellate density. Consequently, GFP concentration and fluorescence showed distinct correlations in non-bleached and bleached corals. Green fluorescence was positively correlated with dinoflagellate photobiology, but its closest correlation was with coral growth suggesting that green fluorescence could be used as a physiological proxy for health in some corals.

  5. Effect of acute heat stress on plant nutrient metabolism proteins

    USDA-ARS?s Scientific Manuscript database

    Abrupt heating decreased the levels (per unit total root protein) of all but one of the nutrient metabolism proteins examined, and for most of the proteins, effects were greater for severe vs. moderate heat stress. For many of the nutrient metabolism proteins, initial effects of heat (1 d) were r...

  6. Repeated muscle damage blunts the increase in heat strain during subsequent exercise heat stress.

    PubMed

    Dolci, A; Fortes, M B; Walker, F S; Haq, A; Riddle, T; Walsh, N P

    2015-07-01

    Exercise-induced muscle damage (EIMD) has recently been shown to increase heat strain during exercise heat stress (HS), and represents a risk factor for exertional heat illness (EHI). We hypothesised that a repeated bout of EIMD blunts the increase in rectal temperature (T re) during subsequent endurance exercise in the heat. Sixteen non-heat-acclimated males were randomly allocated to EIMD (n = 9) or control (CON, n = 7). EIMD performed a downhill running treatment at -10 % gradient for 60 min at 65 % [Formula: see text]O2max in 20 °C, 40 % RH. CON participants performed the same treatment but at +1 % gradient. Following treatment, participants rested for 30 min, then performed HS (+1 % gradient running for 40 min at 65 % [Formula: see text]O2max in 33 °C, 50 % RH) during which thermoregulatory measures were assessed. Both groups repeated the treatment and subsequent HS 14 days later. Isometric quadriceps strength was assessed at baseline, and 48 h post-treatment. The decrease in leg strength 48 h post-EIMD trial 1 (-7.5 %) was absent 48 h post-EIMD trial 2 (+2.9 %) demonstrating a repeated bout effect. Final T re during HS was lower following EIMD trial 2 (39.25 ± 0.47 °C) compared with EIMD trial 1 (39.59 ± 0.49 °C, P < 0.01), with CON showing no difference. Thermal sensation and the T re threshold for sweating onset were also lower during HS on EIMD trial 2. The repeated bout effect blunted the increase in heat strain during HS conducted after EIMD. Incorporating a muscle-damaging bout into training could be a strategy to reduce the risk of EHI and improve endurance performance in individuals undertaking heavy exercise with an eccentric component in the heat.

  7. Waste Heat to Power Market Assessment

    SciTech Connect

    Elson, Amelia; Tidball, Rick; Hampson, Anne

    2015-03-01

    Waste heat to power (WHP) is the process of capturing heat discarded by an existing process and using that heat to generate electricity. In the industrial sector, waste heat streams are generated by kilns, furnaces, ovens, turbines, engines, and other equipment. In addition to processes at industrial plants, waste heat streams suitable for WHP are generated at field locations, including landfills, compressor stations, and mining sites. Waste heat streams are also produced in the residential and commercial sectors, but compared to industrial sites these waste heat streams typically have lower temperatures and much lower volumetric flow rates. The economic feasibility for WHP declines as the temperature and flow rate decline, and most WHP technologies are therefore applied in industrial markets where waste heat stream characteristics are more favorable. This report provides an assessment of the potential market for WHP in the industrial sector in the United States.

  8. Assessment of Vegetation Indices Derived by UAV Imagery for Durum Wheat Phenotyping under a Water Limited and Heat Stressed Mediterranean Environment.

    PubMed

    Kyratzis, Angelos C; Skarlatos, Dimitrios P; Menexes, George C; Vamvakousis, Vasileios F; Katsiotis, Andreas

    2017-01-01

    There is growing interest for using Spectral Vegetation Indices (SVI) derived by Unmanned Aerial Vehicle (UAV) imagery as a fast and cost-efficient tool for plant phenotyping. The development of such tools is of paramount importance to continue progress through plant breeding, especially in the Mediterranean basin, where climate change is expected to further increase yield uncertainty. In the present study, Normalized Difference Vegetation Index (NDVI), Simple Ratio (SR) and Green Normalized Difference Vegetation Index (GNDVI) derived from UAV imagery were calculated for two consecutive years in a set of twenty durum wheat varieties grown under a water limited and heat stressed environment. Statistically significant differences between genotypes were observed for SVIs. GNDVI explained more variability than NDVI and SR, when recorded at booting. GNDVI was significantly correlated with grain yield when recorded at booting and anthesis during the 1st and 2nd year, respectively, while NDVI was correlated to grain yield when recorded at booting, but only for the 1st year. These results suggest that GNDVI has a better discriminating efficiency and can be a better predictor of yield when recorded at early reproductive stages. The predictive ability of SVIs was affected by plant phenology. Correlations of grain yield with SVIs were stronger as the correlations of SVIs with heading were weaker or not significant. NDVIs recorded at the experimental site were significantly correlated with grain yield of the same set of genotypes grown in other environments. Both positive and negative correlations were observed indicating that the environmental conditions during grain filling can affect the sign of the correlations. These findings highlight the potential use of SVIs derived by UAV imagery for durum wheat phenotyping under low yielding Mediterranean conditions.

  9. Molecular mechanisms of the plant heat stress response

    SciTech Connect

    Qu, Ai-Li; Ding, Yan-Fei; Jiang, Qiong; Zhu, Cheng

    2013-03-08

    Highlights: ► This review elaborates the response networks of heat stress in plants. ► It elaborates proteins responding to heat stress in special physiological period. ► The proteins and pathways have formed a basic network of the heat stress response. ► Achievements of the various technologies are also combined. -- Abstract: High temperature has become a global concern, which seriously affects the growth and production of plants, particularly crops. Thus, the molecular mechanism of the heat stress response and breeding of heat-tolerant plants is necessary to protect food production and ensure crop safety. This review elaborates on the response networks of heat stress in plants, including the Hsf and Hsp response pathways, the response of ROS and the network of the hormones. In addition, the production of heat stress response elements during particular physiological periods of the plant is described. We also discuss the existing problems and future prospects concerning the molecular mechanisms of the heat stress response in plants.

  10. Interactive effects of water, light and heat stress on photosynthesis in Fremont cottonwood.

    PubMed

    Tozzi, Emily S; Easlon, Hsien Ming; Richards, James H

    2013-08-01

    Fremont cottonwood seedlings are vulnerable to water stress from rapid water-table decline during river recession in spring. Water stress is usually cited as the reason for reduced establishment, but interactions of water stress with microclimate extremes are more likely the causes of mortality. We assessed photosynthetic responses of Fremont cottonwood seedlings to water, light and heat stresses, which commonly co-occur in habitats where seedlings establish. Under moderate temperature and light conditions, water stress did not affect photosynthetic function. However, stomatal closure during water stress predisposed Fremont cottonwood leaves to light and heat stress, resulting in greatly reduced photosynthesis beginning at 31 °C versus at 41 °C for well-watered plants. Ontogenetic shifts in leaf orientation from horizontal to vertical, which occur as seedlings mature, reduce heat and light stress, especially during water stress. When compared with naturally occurring microclimate extremes, seedling stress responses suggest that reduced assimilation and photoprotection are common for Fremont cottonwood seedlings on exposed point bars where they establish. These reductions in photosynthesis likely have negative impacts on growth and may predispose young (<90-day-old) seedlings to early mortality during rapid water-table declines. Interactions with heat and light stress are more important in these effects than water stress alone. © 2013 John Wiley & Sons Ltd.

  11. Salicylic acid and heat acclimation pretreatment protects Laminaria japonica sporophyte (Phaeophyceae) from heat stress

    NASA Astrophysics Data System (ADS)

    Zhou, Bin; Tang, Xuexi; Wang, You

    2010-07-01

    Possible mediatory roles of heat acclimation and salicylic acid in protecting the sporophyte of marine macroalga Laminaria japonica (Phaeophyceae) from heat stress were studied. Heat stress resulted in oxidative injury in the kelp blades. Under heat stress significant accumulation of hydrogen peroxide (H2O2) and malonaldehyde (MDA), a membrane lipid peroxidation product, and a drastic decrease in chlorophyll a content were recorded. Activity of the enzymatic antioxidant system was drastically affected by heat stress. The activity of superoxide dismutase (SOD) was significantly increased while peroxidase (POD), catalase (CAT) and glutathione peroxidase (GPX) were greatly inhibited and, simultaneously, phenylalanine ammonia-lyase was activated while polyphenol oxidase (PPO) was inhibited. Both heat acclimation pretreatment and exogenous application of salicylic acid alleviated oxidative damage in kelp blades. Blades receiving heat acclimation pretreatment and exogenous salicylic acid prior to heat stress exhibited a reduced increase in H2O2 and MDA content, and a lower reduction in chlorophyll a content. Pretreatment with heat acclimation and salicylic acid elevated activities of SOD, POD, CAT, GPX and PPO. Considering these results collectively, we speculate that the inhibition of antioxidant enzymes is a possible cause of the heat-stress-induced oxidative stress in L. japonica, and enhanced thermotolerance may be associated, at least in part, with the elevated activity of the enzymatic antioxidant system.

  12. Root proteomic responses to heat stress in two Agrostis grass species contrasting in heat tolerance.

    PubMed

    Xu, Chenping; Huang, Bingru

    2008-01-01

    Protein metabolism plays an important role in plant adaptation to heat stress. This study was designed to identify heat-responsive proteins in roots associated with thermotolerance for two C3 grass species contrasting in heat tolerance, thermal Agrostis scabra and heat-sensitive Agrostis stolonifera L. Plants were exposed to 20 degrees C (control), 30 C (moderate heat stress), or 40 degrees C (severe heat stress) in growth chambers. Roots were harvested at 2 d and 10 d after temperature treatment. Proteins were extracted and separated by two-dimensional polyacrylamide gel electrophoresis. Seventy protein spots were regulated by heat stress in at least one species. Under both moderate and severe heat stress, more proteins were down-regulated than were up-regulated, and thermal A. scabra roots had more up-regulated proteins than A. stolonifera roots. The sequences of 66 differentially expressed protein spots were identified using mass spectrometry. The results suggested that the up-regulation of sucrose synthase, glutathione S-transferase, superoxide dismutase, and heat shock protein Sti (stress-inducible protein) may contribute to the superior root thermotolerance of A. scabra. In addition, phosphoproteomic analysis indicated that two isoforms of fructose-biphosphate aldolase were highly phosphorylated under heat stress, and thermal A. scabra had greater phosphorylation than A. stolonifera, suggesting that the aldolase phosphorylation might be involved in root thermotolerance.

  13. Heat stress mortality and desired adaptation responses of healthcare system in Poland

    NASA Astrophysics Data System (ADS)

    Błażejczyk, Anna; Błażejczyk, Krzysztof; Baranowski, Jarosław; Kuchcik, Magdalena

    2017-09-01

    Heat stress is one of the environmental factors influencing the health of individuals and the wider population. There is a large body of research to document significant increases in mortality and morbidity during heat waves all over the world. This paper presents key results of research dealing with heat-related mortality (HRM) in various cities in Poland which cover about 25% of the country's population. Daily mortality and weather data reports for the years 1991-2000 were used. The intensity of heat stress was assessed by the universal thermal climate index (UTCI). The research considers also the projections of future bioclimate to the end of twenty-first century. Brain storming discussions were applied to find necessary adaptation strategies of healthcare system (HCS) in Poland, to minimise negative effects of heat stress. In general, in days with strong and very strong heat stress, ones must expect increase in mortality (in relation to no thermal stress days) of 12 and 47%, respectively. Because of projected rise in global temperature and heat stress frequency, we must expect significant increase in HRM to the end of twenty-first century of even 165% in comparison to present days. The results of research show necessity of urgent implementation of adaptation strategies to heat in HCS.

  14. Heat stress mortality and desired adaptation responses of healthcare system in Poland.

    PubMed

    Błażejczyk, Anna; Błażejczyk, Krzysztof; Baranowski, Jarosław; Kuchcik, Magdalena

    2017-09-01

    Heat stress is one of the environmental factors influencing the health of individuals and the wider population. There is a large body of research to document significant increases in mortality and morbidity during heat waves all over the world. This paper presents key results of research dealing with heat-related mortality (HRM) in various cities in Poland which cover about 25% of the country's population. Daily mortality and weather data reports for the years 1991-2000 were used. The intensity of heat stress was assessed by the universal thermal climate index (UTCI). The research considers also the projections of future bioclimate to the end of twenty-first century. Brain storming discussions were applied to find necessary adaptation strategies of healthcare system (HCS) in Poland, to minimise negative effects of heat stress. In general, in days with strong and very strong heat stress, ones must expect increase in mortality (in relation to no thermal stress days) of 12 and 47%, respectively. Because of projected rise in global temperature and heat stress frequency, we must expect significant increase in HRM to the end of twenty-first century of even 165% in comparison to present days. The results of research show necessity of urgent implementation of adaptation strategies to heat in HCS.

  15. Heat stress and societal impacts in the 21st century

    NASA Astrophysics Data System (ADS)

    Coffel, E.; Horton, R. M.; de Sherbinin, A. M.

    2015-12-01

    Heat is the number-one weather related killer in the US and around the world. As a result of rising temperatures and steady or slightly rising levels of specific humidity, heat stress is projected to become increasingly severe. Here we show that heat stress as measured by two common indices -- the heat index and the wet-bulb temperature -- is projected to rapidly and dramatically increase, and that by mid-century crippling summertime conditions are possible across some of the most densely populated regions of the planet. Many of these regions are places where cooling infrastructure is scarce, adaptive capacity is low, and populations are rapidly rising. We find that by the end of the 21st century, the habitability of some regions of the planet may be questionable due to heat stress alone, and in many other regions severe impacts to human health, infrastructure, agriculture, and economic performance will create significant societal stress and necessitate rapid adaptation.

  16. Heat stress intervention research in construction: gaps and recommendations.

    PubMed

    Yang, Yang; Chan, Albert Ping-Chuen

    2017-06-08

    Developing heat stress interventions for construction workers has received mounting concerns in recent years. However, limited efforts have been exerted to elaborate the rationale, methodology, and practicality of heat stress intervention in the construction industry. This study aims to review previous heat stress intervention research in construction, to identify the major research gaps in methodological issues, and to offer detailed recommendations for future studies. A total of 35 peer-reviewed journal papers have been identified to develop administrative, environmental or personal engineering interventions to safeguard construction workers. It was found that methodological limitations, such as arbitrary sampling methods and unreliable instruments, could be the major obstacle in undertaking heat stress intervention research. To bridge the identified research gaps, this study then refined a research framework for conducting heat stress intervention studies in the construction industry. The proposed research strategy provides researchers and practitioners with fresh insights into expanding multidisciplinary research areas and solving practical problems in the management of heat stress. The proposed research framework may foster the development of heat stress intervention research in construction, which further aids researchers, practitioners, and policymakers in formulating proper intervention strategies.

  17. Heat stress intervention research in construction: gaps and recommendations

    PubMed Central

    YANG, Yang; CHAN, Albert Ping-chuen

    2017-01-01

    Developing heat stress interventions for construction workers has received mounting concerns in recent years. However, limited efforts have been exerted to elaborate the rationale, methodology, and practicality of heat stress intervention in the construction industry. This study aims to review previous heat stress intervention research in construction, to identify the major research gaps in methodological issues, and to offer detailed recommendations for future studies. A total of 35 peer-reviewed journal papers have been identified to develop administrative, environmental or personal engineering interventions to safeguard construction workers. It was found that methodological limitations, such as arbitrary sampling methods and unreliable instruments, could be the major obstacle in undertaking heat stress intervention research. To bridge the identified research gaps, this study then refined a research framework for conducting heat stress intervention studies in the construction industry. The proposed research strategy provides researchers and practitioners with fresh insights into expanding multidisciplinary research areas and solving practical problems in the management of heat stress. The proposed research framework may foster the development of heat stress intervention research in construction, which further aids researchers, practitioners, and policymakers in formulating proper intervention strategies. PMID:28111405

  18. Rubisco activase and wheat productivity under heat-stress conditions.

    PubMed

    Ristic, Zoran; Momcilovic, Ivana; Bukovnik, Urska; Prasad, P V Vara; Fu, Jianming; Deridder, Benjamin P; Elthon, Thomas E; Mladenov, Novica

    2009-01-01

    Rubisco activase (RCA) constrains the photosynthetic potential of plants at high temperatures (heat stress). Endogenous levels of RCA could serve as an important determinant of plant productivity under heat-stress conditions. Thus, in this study, the possible relationship between expression levels of RCA and plant yield in 11 European cultivars of winter wheat following prolonged exposure to heat stress was investigated. In addition, the effect of a short-term heat stress on RCA expression in four genotypes of wheat, five genotypes of maize, and one genotype of Arabidopsis thaliana was examined. Immunoblots prepared from leaf protein extracts from control plants showed three RCA cross-reacting bands in wheat and two RCA cross-reacting bands in maize and Arabidopsis. The molecular mass of the observed bands was in the range between 40 kDa and 46 kDa. Heat stress affected RCA expression in a few genotypes of wheat and maize but not in Arabidopsis. In wheat, heat stress slightly modulated the relative amounts of RCA in some cultivars. In maize, heat stress did not seem to affect the existing RCA isoforms (40 kDa and 43 kDa) but induced the accumulation of a new putative RCA of 45-46 kDa. The new putative 45-46 kDa RCA was not seen in a genotype of maize (ZPL 389) that has been shown to display an exceptional sensitivity to heat stress. A significant, positive, linear correlation was found between the expression of wheat 45-46 kDa RCA and plant productivity under heat-stress conditions. Results support the hypothesis that endogenous levels of RCA could play an important role in plant productivity under supraoptimal temperature conditions.

  19. Ethylene is involved in maintaining tomato (Solanum lycopersicum) pollen quality under heat-stress conditions

    PubMed Central

    Firon, Nurit; Pressman, Etan; Meir, Shimon; Khoury, Reham; Altahan, Leviah

    2012-01-01

    Background and aims Exposure to higher-than-optimal temperatures reduces crop yield and quality, mainly due to sensitivity of developing pollen grains. The mechanisms maintaining high pollen quality under heat-stress conditions are poorly understood. Our recently published data indicate high heat-stress-induced expression of ethylene-responsive genes in tomato pollen, indicating ethylene involvement in the pollen heat-stress response. Here we elucidated ethylene's involvement in pollen heat-stress response and thermotolerance by assessing the effects of interfering with the ethylene signalling pathway and altering ethylene levels on tomato pollen functioning under heat stress. Methodology Plants of the ethylene-insensitive mutant Never ripe (Nr)—defective in an ethylene response sensor (ERS)-like ethylene receptor—and the corresponding wild type were exposed to control or heat-stress growing conditions, and pollen quality was determined. Starch and carbohydrates were measured in isolated pollen grains from these plants. The effect of pretreating cv. Micro-Tom tomato plants, prior to heat-stress exposure, with an ethylene releaser or inhibitor of ethylene biosynthesis on pollen quality was assessed. Principal results Never ripe pollen grains exhibited higher heat-stress sensitivity, manifested by a significant reduction in the total number of pollen grains, reduction in the number of viable pollen and elevation of the number of non-viable pollen, compared with wild-type plants. Mature Nr pollen grains accumulated only 40 % of the sucrose level accumulated by the wild type. Pretreatment of tomato plants with an ethylene releaser increased pollen quality under heat stress, with an over 5-fold increase in the number of germinating pollen grains per flower. Pretreatment with an ethylene biosynthesis inhibitor reduced the number of germinating pollen grains following heat-stress exposure over 5-fold compared with non-treated controls. Conclusions Ethylene plays a

  20. Heat shock protein response in phosphorus-deficient heat-stressed broiler chickens.

    PubMed

    Edens, F W; Hill, C H; Wang, S

    1992-12-01

    1. During acute in vivo heat stress, a normal heat shock protein (HSP) response was not inducible in chickens deficient in inorganic phosphorus (P(i)-deficient). 2. Small quantities of HSP 70 and HSP 90 were induced, but little or no HSP 23 was induced in P(i)-deficient chickens compared to P(i)-adequate chickens. 3. Increased susceptibility of P(i)-deficient chickens to acute heat stress was attributed to their inability to produce an adequate HSP response.

  1. Biophysical aspects of human thermoregulation during heat stress.

    PubMed

    Cramer, Matthew N; Jay, Ollie

    2016-04-01

    Humans maintain a relatively constant core temperature through the dynamic balance between endogenous heat production and heat dissipation to the surrounding environment. In response to metabolic or environmental disturbances to heat balance, the autonomic nervous system initiates cutaneous vasodilation and eccrine sweating to facilitate higher rates of dry (primarily convection and radiation) and evaporative transfer from the body surface; however, absolute heat losses are ultimately governed by the properties of the skin and the environment. Over the duration of a heat exposure, the cumulative imbalance between heat production and heat dissipation leads to body heat storage, but the consequent change in core temperature, which has implications for health and safety in occupational and athletic settings particularly among certain clinical populations, involves a complex interaction between changes in body heat content and the body's morphological characteristics (mass, surface area, and tissue composition) that collectively determine the body's thermal inertia. The aim of this review is to highlight the biophysical aspects of human core temperature regulation by outlining the principles of human energy exchange and examining the influence of body morphology during exercise and environmental heat stress. An understanding of the biophysical factors influencing core temperature will enable researchers and practitioners to better identify and treat individuals/populations most vulnerable to heat illness and injury during exercise and extreme heat events. Further, appropriate guidelines may be developed to optimize health, safety, and work performance during heat stress.

  2. Heat stress protects against mechanical ventilation-induced diaphragmatic atrophy.

    PubMed

    Ichinoseki-Sekine, Noriko; Yoshihara, Toshinori; Kakigi, Ryo; Sugiura, Takao; Powers, Scott K; Naito, Hisashi

    2014-09-01

    Mechanical ventilation (MV) is a life-saving intervention in patients who are incapable of maintaining adequate pulmonary gas exchange due to respiratory failure or other disorders. However, prolonged MV is associated with the development of respiratory muscle weakness. We hypothesized that a single exposure to whole body heat stress would increase diaphragm expression of heat shock protein 72 (HSP72) and that this treatment would protect against MV-induced diaphragmatic atrophy. Adult male Wistar rats (n = 38) were randomly assigned to one of four groups: an acutely anesthetized control group (CON) with no MV; 12-h controlled MV group (CMV); 1-h whole body heat stress (HS); or 1-h whole body heat stress 24 h prior to 12-h controlled MV (HSMV). Compared with CON animals, diaphragmatic HSP72 expression increased significantly in the HS and HSMV groups (P < 0.05). Prolonged MV resulted in significant atrophy of type I, type IIa, and type IIx fibers in the costal diaphragm (P < 0.05). Whole body heat stress attenuated this effect. In contrast, heat stress did not protect against MV-induced diaphragm contractile dysfunction. The mechanisms responsible for this heat stress-induced protection remain unclear but may be linked to increased expression of HSP72 in the diaphragm. Copyright © 2014 the American Physiological Society.

  3. New guidelines are needed to manage heat stress in elite sports--The Fédération Internationale de Volleyball (FIVB) Heat Stress Monitoring Programme.

    PubMed

    Bahr, Roald; Reeser, Jonathan C

    2012-09-01

    There seems to be a discrepancy between the available heat stress guidelines and the actual risk of heat-related illness among professional beach volleyball players competing under hot and humid conditions. To monitor heat stress and record cases of heat-related medical forfeits on the Swatch FIVB Beach Volleyball World Tour. The FIVB Heat Stress Monitoring Protocol covered events on the FIVB Beach Volleyball World Tour and FIVB Beach Volleyball World Championships during the 2009, 2010 and 2011 seasons (51 events, most of these double gender). The protocol consisted of (1) measuring the Wet Bulb Globe Temperature (WBGT) on centre court prior to the start of every match, and (2) recording any heat-related medical forfeits during the tournament. Data were collected during 48 of 51 events. There were nine events where the peak WBGT exceeded the US Navy Black flag conditions of >32.3°C and an additional two events where the peak WBGT exceeded 31°C, (meeting Red flag conditions.) In two events, the average WBGT equalled at least 31°C. One case of a medical forfeit related to heat stress was recorded over the 3-year surveillance period: an athlete whose fluid balance was compromised from a 3-day bout of acute gastroenteritis. The incidence of significant heat illness among athletes competing on the FIVB Beach Volleyball World Tour appears to be quite low, even though weather conditions frequently result in a WBGT index >32°C. Currently available guidelines appear to be inadequate to fully assess the risk of heat stress and too conservative to inform safety decisions in professional beach volleyball.

  4. Recovery of normal testicular temperature after scrotal heat stress in rams assessed by infrared thermography and its effects on seminal characteristics and testosterone blood serum concentration.

    PubMed

    Alves, Maíra Bianchi Rodrigues; Andrade, André Furugen Cesar de; Arruda, Rubens Paes de; Batissaco, Leonardo; Florez-Rodriguez, Shirley Andrea; Oliveira, Bruna Marcele Martins de; Torres, Mariana Andrade; Lançoni, Renata; Ravagnani, Gisele Mouro; Prado Filho, Roberto Romano do; Vellone, Vinícius Silva; Losano, João Diego de Agostini; Franci, Celso Rodrigues; Nichi, Marcílio; Celeghini, Eneiva Carla Carvalho

    2016-08-01

    Reestablishment of testicular normal temperature after testicular heat stress is unknown and its effect varies widely. The aim of this study was to investigate the impact of scrotal insulation (IN) on testicular temperature and its relation to semen quality and testosterone blood serum concentration. For this, 33 rams were used; 17 submitted to IN for 72 hours (using bags involving the testes) and 16 not submitted to IN (control group). The experiment was performed between August and December 2013 in Pirassununga, Brazil (21°56″13″ South/47°28'24″ West). Seminal characteristics, testosterone blood serum concentration, rectal temperature (RT), respiratory frequency, scrotal superficies mean temperature (SSMT), and eye area mean temperature (EAMT) were analyzed 7 days before IN and 21, 35, 49, 63, and 90 days afterward. Scrotal superficies mean temperature and EAMT were measured by thermography camera FLIR T620. Testosterone was evaluated by radioimmunoassay. Analysis of variance was used to determine the main effects of treatment, time, and treatment-by-time interaction using PROC MIXED of SAS software adding command REPEAT. Pearson correlation test was used to verify correlation between SSMT, EAMT, RT, and respiratory frequency. Significant difference was considered when P ≤ 0.05. At the end of IN, SSMT was higher (P < 0.05) in insulated group (32.26 ± 0.19(o)C) than in control group (30.58 ± 0.18(o)C), and the difference between rectal and testicular (deduced from SSMT) temperatures was 1.12 °C; in the other times of the evaluation this difference was between 2.91 and 4.25 °C in IN group. Scrotal superficies mean temperature was reestablished 24 hours after IN. Rectal temperature and EAMT presented correlation (r = 0.59; P < 0.0001). There was time-by-treatment interaction for total sperm (P = 0.0038) and progressive motility (P = 0.01), abnormal spermatozoa (P < 0.0001), membranes integrity (P < 0.0001), induced

  5. Telemetric heat stress monitor (THSM) spin-offs

    SciTech Connect

    Berkbigler, L.; Bradley, O.; Lopez, R.; Martinez, D.; Stampfer, J.

    1996-07-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project sought to investigate spin-offs of the telemetric heat stress monitoring system (THSM) developed at LANL. Hazardous-materials workers and firefighters wear clothing that protects them from external hazards, but the sealed environment of a protective suit makes its wearer susceptible to heat stress. Heat stress occurs when the body`s natural cooling mechanisms fail: it can cause collapse and death. The THSM warns both workers and remote monitoring personnel of incipient heat stress by monitoring and responding to elevations of workers` skin temperatures and heart rates. The technology won a 1994 R & D 100 award.

  6. Proteomics Analysis of Alfalfa Response to Heat Stress

    PubMed Central

    Li, Weimin; Wei, Zhenwu; Qiao, Zhihong; Wu, Zinian; Cheng, Lixiang; Wang, Yuyang

    2013-01-01

    The proteome responses to heat stress have not been well understood. In this study, alfalfa (Medicago sativa L. cv. Huaiyin) seedlings were exposed to 25°C (control) and 40°C (heat stress) in growth chambers, and leaves were collected at 24, 48 and 72 h after treatment, respectively. The morphological, physiological and proteomic processes were negatively affected under heat stress. Proteins were extracted and separated by two-dimensional polyacrylamide gel electrophoresis (2-DE), and differentially expressed protein spots were identified by mass spectrometry (MS). Totally, 81 differentially expressed proteins were identified successfully by MALDI-TOF/TOF. These proteins were categorized into nine classes: including metabolism, energy, protein synthesis, protein destination/storage, transporters, intracellular traffic, cell structure, signal transduction and disease/defence. Five proteins were further analyzed for mRNA levels. The results of the proteomics analyses provide a better understanding of the molecular basis of heat-stress responses in alfalfa. PMID:24324825

  7. Invited review: Effects of heat stress on dairy cattle welfare.

    PubMed

    Polsky, Liam; von Keyserlingk, Marina A G

    2017-09-13

    The effects of high ambient temperatures on production animals, once thought to be limited to tropical areas, has extended into northern latitudes in response to the increasing global temperature. The number of days where the temperature-humidity index (THI) exceeds the comfort threshold (>72) is increasing in the northern United States, Canada, and Europe. Compounded by the increasing number of dairy animals and the intensification of production, heat stress has become one of the most important challenges facing the dairy industry today. The objectives of this review were to present an overview of the effects of heat stress on dairy cattle welfare and highlight important research gaps in the literature. We will also briefly discuss current heat abatement strategies, as well as the sustainability of future heat stress management. Heat stress has negative effects on the health and biological functioning of dairy cows through depressed milk production and reduced reproductive performance. Heat stress can also compromise the affective state of dairy cows by inducing feelings of hunger and thirst, and we have highlighted the need for research efforts to examine the potential relationship between heat stress, frustration, aggression, and pain. Little work has examined how heat stress affects an animal's natural coping behaviors, as well as how the animal's evolutionary adaptations for thermoregulation are managed in modern dairy systems. More research is needed to identify improved comprehensive cow-side measurements that can indicate real-time responses to elevated ambient temperatures and that could be incorporated into heat abatement management decisions. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  8. Heat stress and sudden infant death syndrome--stress gene expression after exposure to moderate heat stress.

    PubMed

    Rohde, Marianne Cathrine; Corydon, Thomas Juhl; Hansen, Jakob; Pedersen, Christina Bak; Schmidt, Stinne P; Gregersen, Niels; Banner, Jytte

    2013-10-10

    The aim of the present study was to investigate stress gene expression in cultured primary fibroblasts established from Achilles tendons collected during autopsies from sudden infant death syndrome (SIDS) cases, and age-matched controls (infants dying in a traumatic event). Expression of 4 stress responsive genes, HSPA1B, HSPD1, HMOX1, and SOD2, was studied by quantitative reverse transcriptase PCR analysis of RNA purified from cells cultured under standard or various thermal stress conditions. The expression of all 4 genes was highly influenced by thermal stress in both SIDS and control cells. High interpersonal variance found in the SIDS group indicated that they represented a more heterogeneous group than controls. The SIDS group responded to thermal stress with a higher expression of the HSPA1B and HSPD1 genes compared to the control group, whereas no significant difference was observed in the expression of SOD2 and HMOX1 between the two groups. The differences were related to the heat shock treatment as none of the genes were expressed significantly different in SIDS at base levels at 37 °C. SOD2 and HMOX1 were up regulated in both groups, for SOD2 though the expression was lower in SIDS at all time points measured, and may be less related to heat stress. Being found dead in the prone position (a known risk factor for SIDS) was related to a lower HSPA1B up-regulation in SIDS compared to SIDS found on their side or back. The study demonstrates the potential usefulness of gene expression studies using cultured fibroblasts established from deceased individuals as a tool for molecular and pathological investigations in forensic and biomedical sciences. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  9. Camelid heat stress: 15 cases (2003–2011)

    PubMed Central

    Norton, Piper L.; Gold, Jenifer R.; Russell, Karen E.; Schulz, Kara L.; Porter, Brian F.

    2014-01-01

    This case series describes novel findings associated with heat stress in 15 cases in South American camelids that had no pre-existing illnesses and which had clinical signs of illness after exposure to a warm environment. Novel findings include decreased packed cell volume and albumin concentration and mild spinal axonal degeneration. Heat stress should be considered in weak camelids with a history of hyperthermia. PMID:25320390

  10. Effect of exercise, heat stress and dehydration on myocardial performance.

    PubMed

    Fehling, P C; Haller, J M; Lefferts, W K; Hultquist, E M; Wharton, M; Rowland, T W; Smith, D L

    2015-06-01

    Myocardial dysfunction is a well-documented outcome of extended periods of high cardiac output. Whether similar effects occur during firefighting, an occupation characterized by repeated periods of work compounded by dehydration and heat stress, is uncertain. To investigate the independent and combined effects of moderate heat stress and dehydration on indicators of myocardial performance following intermittent, submaximal treadmill exercise while wearing personal protective equipment (PPE). Twelve aerobically fit young men (age 21.5±2.6 years; maximal oxygen uptake [VO2max] 60.3±4.4ml kg(-1) min(-1)) performed intermittent treadmill walking exercise consisting of three 20min bouts at an intensity of ~40% VO2max separated by two periods of rest in four different conditions in random order: (i) no heat stress-euhydrated, (ii) heat stress-euhydrated (heat stress created by wearing PPE, (iii) no heat stress-dehydrated and (iv) heat stress-dehydrated. We measured core temperature by a telemetric gastrointestinal pill. We determined cardiac variables by standard echocardiographic techniques immediately before and ~30min after exercise. We recorded no significant changes in markers of systolic (ejection fraction, shortening fraction, tissue Doppler-S) or diastolic (mitral peak E velocity, tissue Doppler-E' and E/E') function following exercise in any of the four conditions. In this model of exercise designed to mimic the work, heat stress and dehydration associated with firefighting activities, we observed no negative effects on myocardial inotropic or lusitropic function. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Regulation of Heat Stress by HSF1 and GR

    DTIC Science & Technology

    2016-09-01

    thermogenesis and mitochondria -derived reactive oxygen species, which likely play a role in heat stress response. Both HSF1 and GR may directly or indirectly...control, n = 3 per group. Furthermore, we examined GR and HSF1 contents in the cytosol, mitochondria , and nucleus of the skeletal muscles. We...are indeed sensitive to heat stress as well as HA. Mitochondria in skeletal muscles are likely the target organelle of acute severe and repeated

  12. Industrial process heat market assessment

    SciTech Connect

    Bresnick, S.

    1981-12-01

    This report is designed to be a reference resource, giving a broad perspective of the potential HTGR market for industrial process heat. It is intended to serve as a briefing document for those wishing to obtain background information and also to serve as a starting point from which more detailed and refined studies may be undertaken. In doing so, the report presents a qualitative and quantitative description of the industrial process heat market in the US, provides a summary discussion of cogeneration experience to date, and outlines the existing institutional and financial framework for cogeneration. The intent is to give the reader an understanding of the current situation and experience in this area. The cogeneration area in particular is an evolving one because of regulations and tax laws, which are still in the process of being developed and interpreted. The report presents the latest developments in regulatory and legislative activities which are associated with that technology. Finally, the report presents a brief description of the three HTGR systems under study during the current fiscal year and describes the specific market characteristics which each application is designed to serve.

  13. Differential proteomic response to heat stress in thermal Agrostis scabra and heat-sensitive Agrostis stolonifera.

    PubMed

    Xu, Chenping; Huang, Bingru

    2010-06-01

    Knowledge of heat-responsive proteins is critical for further understanding of the molecular mechanisms of heat tolerance. The objective of this study was to compare proteins differentially expressed in two C(3) grass species contrasting in heat tolerance, heat-tolerant thermal Agrostis scabra and heat-sensitive Agrostis stolonifera L., and to identify heat-responsive proteins for short- and long-term responses. Plants were exposed to 20/15 degrees C (day/night, control) or 40/35 degrees C (day/night, heat stress) in growth chambers. Leaves were harvested at 2 and 10 days after temperature treatment. Proteins were extracted and separated by fluorescence difference gel electrophoresis (DIGE). Thermal A. scabra had superior heat tolerance than A. stolonifera, as indicated by the maintenance of higher chlorophyll content and photochemical efficiency under heat stress. The two-dimensional difference electrophoresis detected 68 heat-responsive proteins in the two species. Thermal A. scabra had more protein spots either down- or up-regulated at 2 days of heat stress, but fewer protein spots were altered at 10 days of heat stress compared with A. stolonifera. Many protein spots exhibited transient down-regulation in thermal A. scabra (only at 2 days of heat treatment), whereas down-regulation of many proteins was also found at 10 days of heat treatment in A. stolonifera, which suggested that protein metabolism in thermal A. scabra might acclimate to heat stress more rapidly than those in A. stolonifera. The sequences of 56 differentially expressed protein spots were identified using mass spectrometry. The results suggest that the maintenance or less severe down-regulation of proteins during long-term (10 days) heat stress may contribute to the superior heat tolerance in thermal A. scabra, including those involved in photosynthesis [RuBisCo, RuBisCo activase, chloroplastic glyceraldehydes-3-phosphate dehydrogenase (GAPDH), chloroplastic aldolase, oxygen-evolving complex

  14. Cardiovascular drift during heat stress: implications for exercise prescription.

    PubMed

    Wingo, Jonathan E; Ganio, Matthew S; Cureton, Kirk J

    2012-04-01

    Cardiovascular drift, the progressive increase in heart rate and decrease in stroke volume that begins after approximately 10 min of prolonged moderate-intensity exercise, is associated with decreased maximal oxygen uptake, particularly during heat stress. Consequently, the increased heart rate reflects an increased relative metabolic intensity during prolonged exercise in the heat when cardiovascular drift occurs, which has implications for exercise prescription.

  15. Climate change projections of heat stress in Europe: From meteorological variables to impacts on productivity

    NASA Astrophysics Data System (ADS)

    Casanueva, Ana; Kotlarski, Sven; Liniger, Mark A.

    2017-04-01

    is the most widely used heat stress index for working people and can be easily interpreted by means of ISO standards. Within the HEAT-SHIELD project, climate change projections of the WBGT will be used to assess the impact of climate change on workers' health and productivity.

  16. Identification of heat risk patterns in the U.S. National Capital Region by integrating heat stress and related vulnerability.

    PubMed

    Aubrecht, Christoph; Özceylan, Dilek

    2013-06-01

    The increase in the number and severity of weather extremes (including excessive heat) potentially associated with climate change has highlighted the needs for research into risk assessment and risk reduction measures. Extreme heat events, the focus of this paper, have been consistently reported as the leading cause of weather-related mortality in the United States in recent years. In order to fully understand impact potentials and analyze risk in its individual components both the spatially and temporally varying patterns of heat and the multidimensional characteristics of vulnerability have to be considered. In this paper we present a composite index aggregating these factors to assess heat related risk for the U.S. National Capital Region in 2010. The study reveals how risk patterns are in part driven by the geographic variations of vulnerability, generally showing a clear difference between high-risk urban areas and wide areas of low risk in the suburban and rural environments. This pattern is particularly evident for the core center of the study area around the District of Columbia, which is largely characterized by high index values despite not having experienced the peak of the heat stress as compared to other regions in the metropolitan area. The article aims to set a framework for local-level heat stress risk assessment that can provide valuable input and decision support for climate adaptation planning as well as emergency managers aiming at risk reduction and optimization of resource distribution. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. A virtual rat for simulating environmental and exertional heat stress.

    PubMed

    Rakesh, Vineet; Stallings, Jonathan D; Reifman, Jaques

    2014-12-01

    Severe cases of environmental or exertional heat stress can lead to varying degrees of organ dysfunction. To understand heat-injury progression and develop efficient management and mitigation strategies, it is critical to determine the thermal response in susceptible organs under different heat-stress conditions. To this end, we used our previously published virtual rat, which is capable of computing the spatiotemporal temperature distribution in the animal, and extended it to simulate various heat-stress scenarios, including 1) different environmental conditions, 2) exertional heat stress, 3) circadian rhythm effect on the thermal response, and 4) whole body cooling. Our predictions were consistent with published in vivo temperature measurements for all cases, validating our simulations. We observed a differential thermal response in the organs, with the liver experiencing the highest temperatures for all environmental and exertional heat-stress cases. For every 3°C rise in the external temperature from 40 to 46°C, core and organ temperatures increased by ∼0.8°C. Core temperatures increased by 2.6 and 4.1°C for increases in exercise intensity from rest to 75 and 100% of maximal O2 consumption, respectively. We also found differences as large as 0.8°C in organ temperatures for the same heat stress induced at different times during the day. Even after whole body cooling at a relatively low external temperature (1°C for 20 min), average organ temperatures were still elevated by 2.3 to 2.5°C compared with normothermia. These results can be used to optimize experimental protocol designs, reduce the amount of animal experimentation, and design and test improved heat-stress prevention and management strategies.

  18. Phenotypic Effects of Salt and Heat Stress over Three Generations in Arabidopsis thaliana

    PubMed Central

    Suter, Léonie; Widmer, Alex

    2013-01-01

    Current and predicted environmental change will force many organisms to adapt to novel conditions, especially sessile organisms such as plants. It is therefore important to better understand how plants react to environmental stress and to what extent genotypes differ in such responses. It has been proposed that adaptation to novel conditions could be facilitated by heritable epigenetic changes induced by environmental stress, independent of genetic variation. Here we assessed phenotypic effects of heat and salt stress within and across three generations using four highly inbred Arabidopsis thaliana genotypes (Col, Cvi, Ler and Sha). Salt stress generally decreased fitness, but genotypes were differently affected, suggesting that susceptibility of A. thaliana to salt stress varies among genotypes. Heat stress at an early rosette stage had less detrimental effects but accelerated flowering in three out of four accessions. Additionally, we found three different modes of transgenerational effects on phenotypes, all harboring the potential of being adaptive: heat stress in previous generations induced faster rosette growth in Sha, both under heat and control conditions, resembling a tracking response, while in Cvi, the phenotypic variance of several traits increased, resembling diversified bet-hedging. Salt stress experienced in earlier generations altered plant architecture of Sha under salt but not control conditions, similar to transgenerational phenotypic plasticity. However, transgenerational phenotypic effects depended on the type of stress as well as on genotype, suggesting that such effects may not be a general response leading to adaptation to novel environmental conditions in A. thaliana. PMID:24244719

  19. The interactive association between heat shock factor 1 and heat shock proteins in primary myocardial cells subjected to heat stress.

    PubMed

    Tang, Shu; Chen, Hongbo; Cheng, Yanfen; Nasir, Mohammad Abdel; Kemper, Nicole; Bao, Endong

    2016-01-01

    Heat shock factor 1 (HSF1) is a heat shock transcription factor that rapidly induces heat shock gene transcription following thermal stress. In this study, we subjected primary neonatal rat myocardial cells to heat stress in vitro to create a model system for investigating the trends in expression and association between various heat shock proteins (HSPs) and HSF1 under adverse environmental conditions. After the cells were subjected to heat stress at 42˚C for different periods of time, HSP and HSF1 mRNA and protein levels were detected by qPCR and western blot analysis in the heat-stressed cells. The HSF1 expression levels significantly increased in the cells following 120 min of exposure to heat stess compared to the levels observed at the beginning of heat stress exposure. HSP90 followed a similar trend in expression to HSF1, whereas HSP70 followed an opposite trend. However, no significant changes were observed in the crystallin, alpha B (CRYAB, also known as HSP beta-5) expression levels during the 480‑min period of exposure to heat stress. The interaction between the HSPs and HSF1 was analyzed by STRING 9.1, and it was found that HSF1 interacted with HSP90 and HSP70, and that it did not play a role in regulating CRYAB expression. Based on our findings, HSP70 may suppress HSF1 in rat myocardial cells under conditions of heat stress. Furthermore, our data demonstrate that HSF1 is not the key factor for all HSPs, and this was particularly the case for CRYAB.

  20. The interactive association between heat shock factor 1 and heat shock proteins in primary myocardial cells subjected to heat stress

    PubMed Central

    TANG, SHU; CHEN, HONGBO; CHENG, YANFEN; NASIR, MOHAMMAD ABDEL; KEMPER, NICOLE; BAO, ENDONG

    2016-01-01

    Heat shock factor 1 (HSF1) is a heat shock transcription factor that rapidly induces heat shock gene transcription following thermal stress. In this study, we subjected primary neonatal rat myocardial cells to heat stress in vitro to create a model system for investigating the trends in expression and association between various heat shock proteins (HSPs) and HSF1 under adverse environmental conditions. After the cells were subjected to heat stress at 42°C for different periods of time, HSP and HSF1 mRNA and protein levels were detected by qPCR and western blot analysis in the heat-stressed cells. The HSF1 expression levels significantly increased in the cells following 120 min of exposure to heat stess compared to the levels observed at the beginning of heat stress exposure. HSP90 followed a similar trend in expression to HSF1, whereas HSP70 followed an opposite trend. However, no significant changes were observed in the crystallin, alpha B (CRYAB, also known as HSP beta-5) expression levels during the 480-min period of exposure to heat stress. The interaction between the HSPs and HSF1 was analyzed by STRING 9.1, and it was found that HSF1 interacted with HSP90 and HSP70, and that it did not play a role in regulating CRYAB expression. Based on our findings, HSP70 may suppress HSF1 in rat myocardial cells under conditions of heat stress. Furthermore, our data demonstrate that HSF1 is not the key factor for all HSPs, and this was particularly the case for CRYAB. PMID:26719858

  1. Enhanced economic connectivity to foster heat stress-related losses.

    PubMed

    Wenz, Leonie; Levermann, Anders

    2016-06-01

    Assessing global impacts of unexpected meteorological events in an increasingly connected world economy is important for estimating the costs of climate change. We show that since the beginning of the 21st century, the structural evolution of the global supply network has been such as to foster an increase of climate-related production losses. We compute first- and higher-order losses from heat stress-induced reductions in productivity under changing economic and climatic conditions between 1991 and 2011. Since 2001, the economic connectivity has augmented in such a way as to facilitate the cascading of production loss. The influence of this structural change has dominated over the effect of the comparably weak climate warming during this decade. Thus, particularly under future warming, the intensification of international trade has the potential to amplify climate losses if no adaptation measures are taken.

  2. Feedlot cattle susceptibility to heat stress: an animal specific model

    USDA-ARS?s Scientific Manuscript database

    The extreme effects of heat stress in a feedlot situation can cause losses exceeding 5% of all the cattle on feed in a single feedlot. These losses can be very devastating to a localized area of feedlot producers. Animal stress is a result of the combination of three different components: environm...

  3. Association between heat stress and oxidative stress in poultry; mitochondrial dysfunction and dietary interventions with phytochemicals.

    PubMed

    Akbarian, Abdollah; Michiels, Joris; Degroote, Jeroen; Majdeddin, Maryam; Golian, Abolghasem; De Smet, Stefaan

    2016-01-01

    Heat as a stressor of poultry has been studied extensively for many decades; it affects poultry production on a worldwide basis and has significant impact on well-being and production. More recently, the involvement of heat stress in inducing oxidative stress has received much interest. Oxidative stress is defined as the presence of reactive species in excess of the available antioxidant capacity of animal cells. Reactive species can modify several biologically cellular macromolecules and can interfere with cell signaling pathways. Furthermore, during the last decade, there has been an ever-increasing interest in the use of a wide array of natural feed-delivered phytochemicals that have potential antioxidant properties for poultry. In light of this, the current review aims to (1) summarize the mechanisms through which heat stress triggers excessive superoxide radical production in the mitochondrion and progresses into oxidative stress, (2) illustrate that this pathophysiology is dependent on the intensity and duration of heat stress, (3) present different nutritional strategies for mitigation of mitochondrial dysfunction, with particular focus on antioxidant phytochemicals. Oxidative stress that occurs with heat exposure can be manifest in all parts of the body; however, mitochondrial dysfunction underlies oxidative stress. In the initial phase of acute heat stress, mitochondrial substrate oxidation and electron transport chain activity are increased resulting in excessive superoxide production. During the later stage of acute heat stress, down-regulation of avian uncoupling protein worsens the oxidative stress situation causing mitochondrial dysfunction and tissue damage. Typically, antioxidant enzyme activities are upregulated. Chronic heat stress, however, leads to downsizing of mitochondrial metabolic oxidative capacity, up-regulation of avian uncoupling protein, a clear alteration in the pattern of antioxidant enzyme activities, and depletion of antioxidant

  4. Heat-stress increase under climate change twice as large in cities as in rural areas

    NASA Astrophysics Data System (ADS)

    Wouters, Hendrik; De Ridder, Koen; Poelmans, Lien; Willems, Patrick; Brouwers, Johan; Hosseinzadehtalaei, Parisa; Tabari, Hossein; Vanden Broucke, Sam; van Lipzig, Nicole P. M.; Demuzere, Matthias

    2017-04-01

    Urban areas, being warmer than their surroundings, are particularly vulnerable to global warming and associated increases in extreme temperatures. Yet ensemble climate-model projections are generally performed on a scale that is too coarse to represent the evolution of temperatures in cities. Here, for the first time, we combine a 35-year convection-permitting climate model integrations with information from an ensemble of general circulation models to assess heat stress in a typical densely populated mid-latitude maritime region. We show that the heat-stress increase for the mid-21st century is twice as large in cities compared to their surrounding rural areas. The exacerbation is driven by the urban heat island itself, its concurrence with heatwaves, and urban expansion. Cities experience a heat-stress multiplication by a factor 1.4 and 15 depending on the scenario. Remarkably, the future heat-stress surpasses everywhere the urban hot spots of today. Our novel insights exemplify the need to combine information from climate models, acting on different scales, for climate-change risk assessment in heterogeneous regions. Moreover, these results highlight the necessity for adaptation to increasing heat stress, especially in urban areas.

  5. Heat stress is overestimated in climate impact studies for irrigated agriculture

    NASA Astrophysics Data System (ADS)

    Siebert, Stefan; Webber, Heidi; Zhao, Gang; Ewert, Frank

    2017-05-01

    Climate change will increase the number and severity of heat waves, and is expected to negatively affect crop yields. Here we show for wheat and maize across Europe that heat stress is considerably reduced by irrigation due to surface cooling for both current and projected future climate. We demonstrate that crop heat stress impact assessments should be based on canopy temperature because simulations with air temperatures measured at standard weather stations cannot reproduce differences in crop heat stress between irrigated and rainfed conditions. Crop heat stress was overestimated on irrigated land when air temperature was used with errors becoming larger with projected climate change. Corresponding errors in mean crop yield calculated across Europe for baseline climate 1984-2013 of 0.2 Mg yr-1 (2%) and 0.6 Mg yr-1 (5%) for irrigated winter wheat and irrigated grain maize, respectively, would increase to up to 1.5 Mg yr-1 (16%) for irrigated winter wheat and 4.1 Mg yr-1 (39%) for irrigated grain maize, depending on the climate change projection/GCM combination considered. We conclude that climate change impact assessments for crop heat stress need to account explicitly for the impact of irrigation.

  6. Drought stress had a predominant effect over heat stress on three tomato cultivars subjected to combined stress.

    PubMed

    Zhou, Rong; Yu, Xiaqing; Ottosen, Carl-Otto; Rosenqvist, Eva; Zhao, Liping; Wang, Yinlei; Yu, Wengui; Zhao, Tongmin; Wu, Zhen

    2017-01-25

    Abiotic stresses due to environmental factors could adversely affect the growth and development of crops. Among the abiotic stresses, drought and heat stress are two critical threats to crop growth and sustainable agriculture worldwide. Considering global climate change, incidence of combined drought and heat stress is likely to increase. The aim of this study was to shed light on plant growth performance and leaf physiology of three tomatoes cultivars ('Arvento', 'LA1994' and 'LA2093') under control, drought, heat and combined stress. Shoot fresh and dry weight, leaf area and relative water content of all cultivars significantly decreased under drought and combined stress as compared to control. The net photosynthesis and starch content were significantly lower under drought and combined stress than control in the three cultivars. Stomata and pore length of the three cultivars significantly decreased under drought and combined stress as compared to control. The tomato 'Arvento' was more affected by heat stress than 'LA1994' and 'LA2093' due to significant decreases in shoot dry weight, chlorophyll a and carotenoid content, starch content and NPQ (non-photochemical quenching) only in 'Arvento' under heat treatment. By comparison, the two heat-tolerant tomatoes were more affected by drought stress compared to 'Arvento' as shown by small stomatal and pore area, decreased sucrose content, ΦPSII (quantum yield of photosystem II), ETR (electron transport rate) and qL (fraction of open PSII centers) in 'LA1994' and 'LA2093'. The three cultivars showed similar response when subjected to the combination of drought and heat stress as shown by most physiological parameters, even though only 'LA1994' and 'LA2093' showed decreased Fv/Fm (maximum potential quantum efficiency of photosystem II), ΦPSII, ETR and qL under combined stress. The cultivars differing in heat sensitivity did not show difference in the combined stress sensitivity, indicating that selection for tomatoes

  7. On Time Domain Analysis of Photoplethysmogram Signals for Monitoring Heat Stress

    PubMed Central

    Elgendi, Mohamed; Fletcher, Rich; Norton, Ian; Brearley, Matt; Abbott, Derek; Lovell, Nigel H.; Schuurmans, Dale

    2015-01-01

    There are a limited number of studies on heat stress dynamics during exercise using the photoplethysmogram (PPG) and its second derivative (APG). However, we investigate the most suitable index from short PPG signal recordings for heat stress assessment. The APG waveform consists of a, b, c and d waves in systole and an e wave in diastole. Our preliminary results indicate that the use of the energy of aa area, derived from PPG signals measured from emergency responders in tropical conditions, is promising in determining the heat stress level using 20-s recordings. After examining 14 time domain features using leave-one-out cross-validation, we found that the aa energy extracted from PPG signals is the most informative feature for classifying heat-stressed subjects, with an overall accuracy of 79%. Moreover, the combination of the aa energy with the traditional heart rate variability index of heat stress (i.e., the square root of the mean of the squares of the successive aa intervals) improved the heat stress detection to an overall accuracy of 83%. PMID:26404271

  8. Low, medium, and high heat tolerant strains of Listeria monocytogenes and increased heat stress resistance after exposure to sublethal heat.

    PubMed

    Shen, Qian; Jangam, Priyanka M; Soni, Kamlesh A; Nannapaneni, Ramakrishna; Schilling, Wes; Silva, Juan L

    2014-08-01

    A group of 37 strains representing all 13 serotypes of Listeria monocytogenes with an initial cell density of 10(7) CFU/ml were analyzed for their heat tolerance at 60°C for 10 min. These L. monocytogenes strains were categorized into three heat tolerance groups: low (<2 log CFU/ml survival), medium (2 to 4 log CFU/ml survival), and high (4 to 6 log CFU/ml survival). Serotype 1/2a strains had relatively low heat tolerance; seven of the eight tested strains were classified as low heat tolerant. Of the two serotype 1/2b strains tested, one was very heat sensitive (not detectable) and the other was very heat resistant (5.4 log CFU/ml survival). Among the 16 serotype 4b strains, survival ranged from not detectable to 4 log CFU/ml. When one L. monocytogenes strain from each heat tolerance group was subjected to sublethal heat stress at 48°C for 30 or 60 min, the survival of heat-stressed cells at 60°C for 10 min increased by 5 log CFU/ml (D60°C-values nearly doubled) compared with the nonstressed control cells. Sublethal heat stress at 48°C for 60 or 90 min increased the lag phase of L. monocytogenes in tryptic soy broth supplemented with 0.6% yeast extract at room temperature by 3 to 5 h compared with nonstressed control cells. The heat stress adaptation in L. monocytogenes was reversed after 2 h at room temperature but was maintained for up to 24 h at 4°C. Our results indicate a high diversity in heat tolerance among strains of L. monocytogenes, and once acquired this heat stress adaptation persists after cooling, which should be taken into account while conducting risk analyses for this pathogen.

  9. Ability to Discriminate Between Sustainable and Unsustainable Heat Stress Exposures-Part 2: Physiological Indicators.

    PubMed

    Garzón-Villalba, Ximena P; Wu, Yougui; Ashley, Candi D; Bernard, Thomas E

    2017-06-08

    There are times when it is not practical to assess heat stress using environmental metrics and metabolic rate, and heat strain may provide an alternative approach. Heat strain indicators have been used for decades as tools for monitoring physiological responses to work in hot environments. Common indicators of heat strain are body core temperature (assessed here as rectal temperature Tre), heart rate (HR), and average skin temperature (Tsk). Data collected from progressive heat stress trials were used to (1) demonstrate if physiological heat strain indicators (PHSIs) at the upper limit of Sustainable heat stress were below generally accepted limits; (2) suggest values for PHSIs that demonstrate a Sustainable level of heat stress; (3) suggest alternative PHSIs; and (4) determine if metabolic rate was an effect modifier. Two previous progressive heat stress studies included 176 trials with 352 pairs of Sustainable and Unsustainable exposures over a range of relative humidities and metabolic rates using 29 participants. To assess the discrimination ability of PHSIs, conditional logistic regression and stepwise logistic regression were used to find the best combinations of predictors of Unsustainable exposures. The accuracy of the models was assessed using receiver operating characteristic curves. Current recommendations for physiological heat strain limits were associated with probabilities of Unsustainable greater than 0.5. Screening limits for Sustainable heat stress were Tre of 37.5°C, HR of 105 bpm, and Tsk of 35.8°C. Tsk alone resulted in an area under the curve of 0.85 and the combination of Tsk and HR (area under the curve = 0.88) performed the best. The adjustment for metabolic rate was statistically significant for physiological strain index or ∆Tre-sk as main predictors, but its effect modification was negligible and could be ignored. Based on the receiver operating characteristic curve, PHSIs (Tre, HR, and Tsk) can accurately predict Unsustainable heat

  10. Effect of moderate exercise-induced heat stress on carotid wave intensity.

    PubMed

    Smith, Denise L; DeBlois, Jacob P; Wharton, Margaret; Fehling, Patricia C; Ranadive, Sushant M

    2015-10-01

    Exercise disrupts the interaction between the left ventricle and the vasculature, as measured by wave intensity (WI) analysis. However, the effect of exercise-induced heat stress on WI amplitude is unknown. WI measures are calibrated using brachial or carotid artery blood pressure, but the influence of calibration method on WI outcomes is unknown. (1) To compare WI analysis during low and moderate exercise-induced heat stress; (2) to examine differences in carotid WI analysis based on calibration method. Eleven healthy, young men (22 ± 3 years) performed intermittent exercise in moderate- and low-heat stress conditions. WI was assessed pre- and post-exercise on the right carotid artery, and calibrated with brachial and carotid blood pressures. A main effect of time was found for W1 when calibrated by brachial, but not carotid pressure. A time-by-condition interaction was observed for late systolic/early diastolic function (W2) in both brachial (p = 0.047) and carotid calibration methods (p = 0.042), where W2 increased following exercise-induced moderate-heat stress but decreased following low-heat stress. The elastic modulus exhibited a significant time-by-condition interaction (brachial p = 0.039; carotid p = 0.044), increasing following moderate-heat stress but decreasing following low-heat stress. Calibrations using carotid blood pressure significantly reduced WI amplitudes compared with brachial calibrations (p < 0.001). Arterial-ventricular coupling is affected in different ways following moderate and low exercise-induced heat stress. Wave amplitudes were lower (~13 %) following carotid calibration compared with brachial.

  11. Heat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in Humans

    PubMed Central

    Iguchi, Masaki; Littmann, Andrew E.; Chang, Shuo-Hsiu; Wester, Lydia A.; Knipper, Jane S.; Shields, Richard K.

    2012-01-01

    Context: Conditions such as osteoarthritis, obesity, and spinal cord injury limit the ability of patients to exercise, preventing them from experiencing many well-documented physiologic stressors. Recent evidence indicates that some of these stressors might derive from exercise-induced body temperature increases. Objective: To determine whether whole-body heat stress without exercise triggers cardiovascular, hormonal, and extra-cellular protein responses of exercise. Design: Randomized controlled trial. Setting: University research laboratory. Patients or Other Participants: Twenty-five young, healthy adults (13 men, 12 women; age = 22.1 ± 2.4 years, height = 175.2 ± 11.6 cm, mass = 69.4 ± 14.8 kg, body mass index = 22.6 ± 4.0) volunteered. Intervention(s): Participants sat in a heat stress chamber with heat (73°C) and without heat (26°C) stress for 30 minutes on separate days. We obtained blood samples from a subset of 13 participants (7 men, 6 women) before and after exposure to heat stress. Main Outcome Measure(s): Extracellular heat shock protein (HSP72) and catecholamine plasma concentration, heart rate, blood pressure, and heat perception. Results: After 30 minutes of heat stress, body temperature measured via rectal sensor increased by 0.8°C. Heart rate increased linearly to 131.4 ± 22.4 beats per minute (F6,24 = 186, P < .001) and systolic and diastolic blood pressure decreased by 16 mm Hg (F6,24 = 10.1, P < .001) and 5 mm Hg (F6,24 = 5.4, P < .001), respectively. Norepinephrine (F1,12 = 12.1, P = .004) and prolactin (F1,12 = 30.2, P < .001) increased in the plasma (58% and 285%, respectively) (P < .05). The HSP72 (F1,12 = 44.7, P < .001) level increased with heat stress by 48.7% ± 53.9%. No cardiovascular or blood variables showed changes during the control trials (quiet sitting in the heat chamber with no heat stress), resulting in differences between heat and control trials. Conclusions: We found that whole-body heat stress triggers some of the

  12. Heat stress and cardiovascular, hormonal, and heat shock proteins in humans.

    PubMed

    Iguchi, Masaki; Littmann, Andrew E; Chang, Shuo-Hsiu; Wester, Lydia A; Knipper, Jane S; Shields, Richard K

    2012-01-01

    Conditions such as osteoarthritis, obesity, and spinal cord injury limit the ability of patients to exercise, preventing them from experiencing many well-documented physiologic stressors. Recent evidence indicates that some of these stressors might derive from exercise-induced body temperature increases. To determine whether whole-body heat stress without exercise triggers cardiovascular, hormonal, and extracellular protein responses of exercise. Randomized controlled trial. University research laboratory. Twenty-five young, healthy adults (13 men, 12 women; age = 22.1 ± 2.4 years, height = 175.2 ± 11.6 cm, mass = 69.4 ± 14.8 kg, body mass index = 22.6 ± 4.0) volunteered. Participants sat in a heat stress chamber with heat (73°C) and without heat (26°C) stress for 30 minutes on separate days. We obtained blood samples from a subset of 13 participants (7 men, 6 women) before and after exposure to heat stress. Extracellular heat shock protein (HSP72) and catecholamine plasma concentration, heart rate, blood pressure, and heat perception. After 30 minutes of heat stress, body temperature measured via rectal sensor increased by 0.8°C. Heart rate increased linearly to 131.4 ± 22.4 beats per minute (F₆,₂₄ = 186, P < .001) and systolic and diastolic blood pressure decreased by 16 mm Hg (F₆,₂₄ = 10.1, P < .001) and 5 mm Hg (F₆,₂₄ = 5.4, P < .001), respectively. Norepinephrine (F₁,₁₂ = 12.1, P = .004) and prolactin (F₁,₁₂ = 30.2, P < .001) increased in the plasma (58% and 285%, respectively) (P < .05). The HSP72 (F₁,₁₂ = 44.7, P < .001) level increased with heat stress by 48.7% ± 53.9%. No cardiovascular or blood variables showed changes during the control trials (quiet sitting in the heat chamber with no heat stress), resulting in differences between heat and control trials. We found that whole-body heat stress triggers some of the physiologic responses observed with exercise. Future studies are necessary to investigate whether

  13. Heat stress in grapevine: the pros and cons of acclimation.

    PubMed

    Carvalho, Luísa C; Coito, João L; Colaço, Silvana; Sangiogo, Maurício; Amâncio, Sara

    2015-04-01

    Heat stress is a major limiting factor of grapevine production and quality. Acclimation and recovery are essential to ensure plant survival, and the recovery mechanisms can be independent of the heat response mechanisms. An experimental set up with and without acclimation to heat followed by recovery [stepwise acclimation and recovery (SAR) and stepwise recovery (SR), respectively] was applied to two grapevine varieties, Touriga Nacional (TN), and Trincadeira (TR), with different tolerance to abiotic stress. Major differences were found between leaves of SAR and SR, especially after recovery; in SAR, almost all parameters returned to basal levels while in SR they remained altered. Acclimation led to a swifter and short-term antioxidative response, affecting the plant to a lesser extent than SR. Significant differences were found among varieties: upon stress, TN significantly increased ascorbate and glutathione reduction levels, boosting the cell's redox-buffering capacity, while TR needed to synthesize both metabolites, its response being insufficient to keep the redox state at working levels. TR was affected by stress for a longer period and the up-regulation pattern of antioxidative stress genes was more obvious. In TN, heat shock proteins were significantly induced, but the canonical heat-stress gene signature was not evident probably because no shutdown of the housekeeping metabolism was needed.

  14. Heat Stress and Baroreflex Regulation of Blood Pressure

    PubMed Central

    CRANDALL, CRAIG G.

    2010-01-01

    In healthy, noninjured, individuals, passive (i.e., nonexercising) whole-body heating has the potential to cause significant cardiovascular stress that may be second only to the cardiovascular stress associated with exercise. For example, such a heat stress can increase heart rate to well over 100 beats·min−1 with cardiac output increasing upward to 13 L·min−1. This increase in cardiac output is necessary to maintain blood pressure due to profound reductions in total vascular conductance associated with cutaneous vasodilation. These responses are accompanied with elevations in sympathetic activity and reductions in vascular conductance (i.e., increased vascular resistance) from noncutaneous beds. While heat-stressed, blood pressure control is compromised resulting in orthostatic intolerance. A plausible explanation for such an event is that heat stress impairs baroreflex responsiveness perhaps due to the reduced range by which baroreflexes can increase heart rate, cardiac output, sympathetic activity, and vascular resistance during a hypotensive challenge. Given that dynamic exercise has the potential to cause large increases in internal temperature, possibly a component of the response to exercise, with respect to baroreflex control of blood pressure, may be affected by the thermal load during the exercise bout. Within this context, the purpose of this review was to summarize findings investigating the effects of heat stress on baroreflex regulation of blood pressure. PMID:18981943

  15. Heat stress and baroreflex regulation of blood pressure.

    PubMed

    Crandall, Craig G

    2008-12-01

    In healthy, noninjured, individuals, passive (i.e., nonexercising) whole-body heating has the potential to cause significant cardiovascular stress that may be second only to the cardiovascular stress associated with exercise. For example, such a heat stress can increase heart rate to well over 100 beats min(-1) with cardiac output increasing upward to 13 L min(-1). This increase in cardiac output is necessary to maintain blood pressure due to profound reductions in total vascular conductance associated with cutaneous vasodilation. These responses are accompanied with elevations in sympathetic activity and reductions in vascular conductance (i.e., increased vascular resistance) from noncutaneous beds. While heat-stressed, blood pressure control is compromised resulting in orthostatic intolerance. A plausible explanation for such an event is that heat stress impairs baroreflex responsiveness perhaps due to the reduced range by which baroreflexes can increase heart rate, cardiac output, sympathetic activity, and vascular resistance during a hypotensive challenge. Given that dynamic exercise has the potential to cause large increases in internal temperature, possibly a component of the response to exercise, with respect to baroreflex control of blood pressure, may be affected by the thermal load during the exercise bout. Within this context, the purpose of this review was to summarize findings investigating the effects of heat stress on baroreflex regulation of blood pressure.

  16. Scrotal heat stress effects on sperm viability, sperm DNA integrity, and the offspring sex ratio in mice.

    PubMed

    Pérez-Crespo, M; Pintado, B; Gutiérrez-Adán, A

    2008-01-01

    Evidence exists to suggest detrimental effects of heat stress on male fertility. This study was designed to assess the effects of scrotal heat stress on mature and developing sperm in a mouse model. After receiving shock heat treatment (42 degrees C for 30 min), mature spermatozoa were recovered from the epididymis hours (6) or Days (7, 14, 21, 28, 60) later, to determine the variables: number of spermatozoa, sperm viability, motility and progressive motility, sperm DNA integrity as established by the TUNEL method, embryo implantation rate, and sex ratio of the fetuses conceived using the heat-exposed spermatozoa. Our results indicate that transient mild heat treatment does not affect in the same way the different types of male germ cells. Spermatocytes present within the testis at the time of heat stress resulted into a lower concentration of spermatozoa with reduced viability and low motility. Even though, DNA integrity of spermatozoa resulting from spermatocytes was also compromised by heat stress, the higher degree of DNA damage was found among spermatozoa resulting from spermatids present within the testis at the time of heat stress. At last, heat shock effect on spermatozoa present in the epididymis at the time of thermal stress resulted into a sex ratio distortion. These findings point to a higher sensitivity of spermatocytes to heat exposure and also suggest a different response of X and Y chromosome-bearing spermatozoa to heat stress that warrants further investigation.

  17. Ideas and perspectives: Heat stress: more than hot air

    NASA Astrophysics Data System (ADS)

    De Boeck, Hans J.; Van De Velde, Helena; De Groote, Toon; Nijs, Ivan

    2016-10-01

    Climate models project an important increase in the frequency and intensity of heat waves. In gauging the impact on plant responses, much of the focus has been on air temperatures, while a critical analysis of leaf temperatures during heat extremes has not been conducted. Nevertheless, direct physiological consequences from heat depend primarily on leaf rather than on air temperatures. We discuss how the interplay between various environmental variables and the plants' stomatal response affects leaf temperatures and the potential for heat stress by making use of both an energy balance model and field data. The results demonstrate that this interplay between plants and environment can cause leaf temperature to vary substantially at the same air temperature. In general, leaves tended to heat up when radiation was high and when stomates were closed, as expected. But perhaps counterintuitively, high air humidity also raised leaf temperatures, while humid conditions are typically regarded as benign with respect to plant survival since they limit water loss. High wind speeds brought the leaf temperature closer to the air temperature, which can imply either cooling or warming (i.e. abating or reinforcing heat stress) depending on other prevailing conditions. The results thus indicate that heat waves characterized by similar extreme air temperatures may pose little danger under some atmospheric conditions but could be lethal in other cases. The trends illustrated here should give ecologists and agronomists a more informed indication about which circumstances are most conducive to the occurrence of heat stress.

  18. Dynamics of urban heat stress events in climate models

    NASA Astrophysics Data System (ADS)

    Yang, David

    2016-04-01

    Extreme heat stress events as measured by the wet-bulb temperature require extraordinarily high air temperatures coupled with high humidity. These conditions are rare, as relative humidity rapidly falls with rising air temperature, and this effect often results in decreasing heat stress as temperature rises. However, in certain coastal locations in the Middle East recent heat waves have resulted in wet-bulb temperatures of 33-35 degrees C, which approach the theoretical limits of human tolerance. These conditions result from the combination of extreme desert heat and humid winds off of the warm ocean waters. It is unclear if climate models properly simulate these dynamics. This study will analyse the ability of the CMIP5 model suite to replicate observed dynamics during extreme heat events in major urban areas.

  19. Cardiovascular responses to heat stress in chronic heart failure

    PubMed Central

    Cui, Jian; Sinoway, Lawrence I.

    2014-01-01

    Clinical reports have suggested that patients with heart diseases may be particularly vulnerable to heat injury. This review examines the effects of heat stress on cardiovascular and autonomic functions in patients with chronic heart failure (CHF). Laboratory investigations have shown that cutaneous vasodilator responses to heating are impaired in patients, whereas activation of skin sympathetic nerve activation is not attenuated in CHF as compared to controls. Attenuated cutaneous vasodilation may increase the risk of a heat related illness when CHF subjects are exposed to hyperthermic conditions. PMID:24599558

  20. A comparison of THI indices leads to a sensible heat-based heat stress index for shaded cattle that aligns temperature and humidity stress

    NASA Astrophysics Data System (ADS)

    Berman, A.; Horovitz, Talia; Kaim, M.; Gacitua, H.

    2016-10-01

    The combined temperature-humidity heat stress is estimated in farm animals by indices derived of an index based on human thermal comfort sensation. The latter index consists of temperature and humidity measures that sum to form the temperature-humidity index (THI). The hitherto unknown relative contribution of temperature and humidity to the THI was examined. A temperature-humidity data set (temperature 20-42 °C and relative humidity 10-70 %) was used to assess by regression procedures the relative weights of temperature and humidity in the variance of THI values produced by six commonly used heat stress indices. The temperature (Ta) effect was predominant (0.82-0.95 of variance) and humidity accounted for only 0.05 to 0.12 of THI variance, half of the variance encountered in animal responses to variable humidity heat stress. Significant difference in THI values was found between indices in the relative weights of temperature and humidity. As in THI indices, temperature and humidity are expressed in different physical units, their sum has no physical attributes, and empirical evaluations assess THI relation to animal responses. A sensible heat THI was created, in which at higher temperatures humidity reaches 0.25 of sensible heat, similarly to evaporative heat loss span in heat stressed animals. It relates to ambient temperature-humidity similarly to present THI; its values are similar to other THI but greater at higher humidity. In warm conditions, mean animal responses are similar in both indices. The higher sensitivity to humidity makes this index preferable for warm-humid conditions.

  1. A comparison of THI indices leads to a sensible heat-based heat stress index for shaded cattle that aligns temperature and humidity stress.

    PubMed

    Berman, A; Horovitz, Talia; Kaim, M; Gacitua, H

    2016-10-01

    The combined temperature-humidity heat stress is estimated in farm animals by indices derived of an index based on human thermal comfort sensation. The latter index consists of temperature and humidity measures that sum to form the temperature-humidity index (THI). The hitherto unknown relative contribution of temperature and humidity to the THI was examined. A temperature-humidity data set (temperature 20-42 °C and relative humidity 10-70 %) was used to assess by regression procedures the relative weights of temperature and humidity in the variance of THI values produced by six commonly used heat stress indices. The temperature (Ta) effect was predominant (0.82-0.95 of variance) and humidity accounted for only 0.05 to 0.12 of THI variance, half of the variance encountered in animal responses to variable humidity heat stress. Significant difference in THI values was found between indices in the relative weights of temperature and humidity. As in THI indices, temperature and humidity are expressed in different physical units, their sum has no physical attributes, and empirical evaluations assess THI relation to animal responses. A sensible heat THI was created, in which at higher temperatures humidity reaches 0.25 of sensible heat, similarly to evaporative heat loss span in heat stressed animals. It relates to ambient temperature-humidity similarly to present THI; its values are similar to other THI but greater at higher humidity. In warm conditions, mean animal responses are similar in both indices. The higher sensitivity to humidity makes this index preferable for warm-humid conditions.

  2. Calibration of Heat Stress Monitor and its Measurement Uncertainty

    NASA Astrophysics Data System (ADS)

    Ekici, Can

    2017-07-01

    Wet-bulb globe temperature (WBGT) equation is a heat stress index that gives information for the workers in the industrial areas. WBGT equation is described in ISO Standard 7243 (ISO 7243 in Hot environments—estimation of the heat stress on working man, based on the WBGT index, ISO, Geneva, 1982). WBGT is the result of the combined quantitative effects of the natural wet-bulb temperature, dry-bulb temperature, and air temperature. WBGT is a calculated parameter. WBGT uses input estimates, and heat stress monitor measures these quantities. In this study, the calibration method of a heat stress monitor is described, and the model function for measurement uncertainty is given. Sensitivity coefficients were derived according to GUM. Two-pressure humidity generators were used to generate a controlled environment. Heat stress monitor was calibrated inside of the generator. Two-pressure humidity generator, which is located in Turkish Standard Institution, was used as the reference device. This device is traceable to national standards. Two-pressure humidity generator includes reference temperature Pt-100 sensors. The reference sensor was sheltered with a wet wick for the calibration of natural wet-bulb thermometer. The reference sensor was centred into a black globe that has got 150 mm diameter for the calibration of the black globe thermometer.

  3. Identification of workers exposed concomitantly to heat stress and chemicals.

    PubMed

    Bourbonnais, Robert; Zayed, Joseph; Lévesque, Martine; Busque, Marc-Antoine; Duguay, Patrice; Truchon, Ginette

    2013-01-01

    In the context of climate change, concomitant exposure to heat stress and chemicals takes on great importance. However, little information is available in this regard. The purpose of this research, therefore, was to develop an approach aimed at identifying worker groups that would be potentially most at risk. The approach comprises 5 consecutive steps: - Establishment of a list of occupations for all industry sectors - Determination of heat stress parameters - Identification of occupations at risk of heat stress - Determination of exposure to chemicals - Identification of occupations potentially most at risk. Overall, 1,010 occupations were selected due to their representativeness of employment sectors in Québec. Using a rating matrix, the risk stemming from exposure to heat stress was judged "critical" or "significant" for 257 occupations. Among these, 136 occupations were identified as showing a high potential of simultaneous exposure to heat stress and chemicals. Lastly, a consultation with thirteen experts made it possible to establish a list of 22 priority occupations, that is, 20 occupations in the metal manufacturing sector, as well as roofers and firefighters. These occupations would merit special attention for an investigation and evaluation of the potential effects on workers' health.

  4. Reductions in labour capacity from heat stress under climate warming

    NASA Astrophysics Data System (ADS)

    Dunne, John P.; Stouffer, Ronald J.; John, Jasmin G.

    2013-06-01

    A fundamental aspect of greenhouse-gas-induced warming is a global-scale increase in absolute humidity. Under continued warming, this response has been shown to pose increasingly severe limitations on human activity in tropical and mid-latitudes during peak months of heat stress. One heat-stress metric with broad occupational health applications is wet-bulb globe temperature. We combine wet-bulb globe temperatures from global climate historical reanalysis and Earth System Model (ESM2M) projections with industrial and military guidelines for an acclimated individual's occupational capacity to safely perform sustained labour under environmental heat stress (labour capacity)--here defined as a global population-weighted metric temporally fixed at the 2010 distribution. We estimate that environmental heat stress has reduced labour capacity to 90% in peak months over the past few decades. ESM2M projects labour capacity reduction to 80% in peak months by 2050. Under the highest scenario considered (Representative Concentration Pathway 8.5), ESM2M projects labour capacity reduction to less than 40% by 2200 in peak months, with most tropical and mid-latitudes experiencing extreme climatological heat stress. Uncertainties and caveats associated with these projections include climate sensitivity, climate warming patterns, CO2 emissions, future population distributions, and technological and societal change.

  5. A spatio-temporal index for heat vulnerability assessment.

    PubMed

    Kershaw, Suzanne E; Millward, Andrew A

    2012-12-01

    The public health consequences of extreme heat events are felt most intensely in metropolitan areas where population density is high and the presence of the urban heat island phenomenon exacerbates the potential for prolonged exposure. This research develops an approach to map potential heat stress on humans by combining temperature and relative humidity into an index of apparent temperature. We use ordinary kriging to generate hourly prediction maps describing apparent temperature across the Greater Toronto Area, Canada. Meteorological data were obtained from 65 locations for 6 days in 2008 when extreme heat alerts were issued for the City of Toronto. Apparent temperature and exposure duration were integrated in a single metric, humidex degree hours (HDH), and mapped. The results show a significant difference in apparent temperature between built and natural locations from 3 PM to 7 AM; this discrepancy was greatest at 12 AM where built locations had a mean of 2.8 index values larger, t(71) = 5.379, p < 0.001. Spatial trends in exposure to heat stress (apparent temperature, ≥ 30°C) show the downtown core of the City of Toronto and much of Mississauga (west of Toronto) as likely to experience hazardous levels of prolonged heat and humidity (HDH ≥ 72) during a heat alert. We recommend that public health officials use apparent temperature and exposure duration to develop spatially explicit heat vulnerability assessment tools; HDH is one approach that unites these risk factors into a single metric.

  6. The Plant Heat Stress Transcription Factors (HSFs): Structure, Regulation, and Function in Response to Abiotic Stresses

    PubMed Central

    Guo, Meng; Liu, Jin-Hong; Ma, Xiao; Luo, De-Xu; Gong, Zhen-Hui; Lu, Ming-Hui

    2016-01-01

    Abiotic stresses such as high temperature, salinity, and drought adversely affect the survival, growth, and reproduction of plants. Plants respond to such unfavorable changes through developmental, physiological, and biochemical ways, and these responses require expression of stress-responsive genes, which are regulated by a network of transcription factors (TFs), including heat stress transcription factors (HSFs). HSFs play a crucial role in plants response to several abiotic stresses by regulating the expression of stress-responsive genes, such as heat shock proteins (Hsps). In this review, we describe the conserved structure of plant HSFs, the identification of HSF gene families from various plant species, their expression profiling under abiotic stress conditions, regulation at different levels and function in abiotic stresses. Despite plant HSFs share highly conserved structure, their remarkable diversification across plants reflects their numerous functions as well as their integration into the complex stress signaling and response networks, which can be employed in crop improvement strategies via biotechnological intervention. PMID:26904076

  7. The Plant Heat Stress Transcription Factors (HSFs): Structure, Regulation, and Function in Response to Abiotic Stresses.

    PubMed

    Guo, Meng; Liu, Jin-Hong; Ma, Xiao; Luo, De-Xu; Gong, Zhen-Hui; Lu, Ming-Hui

    2016-01-01

    Abiotic stresses such as high temperature, salinity, and drought adversely affect the survival, growth, and reproduction of plants. Plants respond to such unfavorable changes through developmental, physiological, and biochemical ways, and these responses require expression of stress-responsive genes, which are regulated by a network of transcription factors (TFs), including heat stress transcription factors (HSFs). HSFs play a crucial role in plants response to several abiotic stresses by regulating the expression of stress-responsive genes, such as heat shock proteins (Hsps). In this review, we describe the conserved structure of plant HSFs, the identification of HSF gene families from various plant species, their expression profiling under abiotic stress conditions, regulation at different levels and function in abiotic stresses. Despite plant HSFs share highly conserved structure, their remarkable diversification across plants reflects their numerous functions as well as their integration into the complex stress signaling and response networks, which can be employed in crop improvement strategies via biotechnological intervention.

  8. Chloroplast Retrograde Regulation of Heat Stress Responses in Plants

    PubMed Central

    Sun, Ai-Zhen; Guo, Fang-Qing

    2016-01-01

    It is well known that intracellular signaling from chloroplast to nucleus plays a vital role in stress responses to survive environmental perturbations. The chloroplasts were proposed as sensors to heat stress since components of the photosynthetic apparatus housed in the chloroplast are the major targets of thermal damage in plants. Thus, communicating subcellular perturbations to the nucleus is critical during exposure to extreme environmental conditions such as heat stress. By coordinating expression of stress specific nuclear genes essential for adaptive responses to hostile environment, plants optimize different cell functions and activate acclimation responses through retrograde signaling pathways. The efficient communication between plastids and the nucleus is highly required for such diverse metabolic and biosynthetic functions during adaptation processes to environmental stresses. In recent years, several putative retrograde signals released from plastids that regulate nuclear genes have been identified and signaling pathways have been proposed. In this review, we provide an update on retrograde signals derived from tetrapyrroles, carotenoids, reactive oxygen species (ROS) and organellar gene expression (OGE) in the context of heat stress responses and address their roles in retrograde regulation of heat-responsive gene expression, systemic acquired acclimation, and cellular coordination in plants. PMID:27066042

  9. Effects of City Expansion on Heat Stress under Climate Change Conditions

    PubMed Central

    Argüeso, Daniel; Evans, Jason P.; Pitman, Andrew J.; Di Luca, Alejandro

    2015-01-01

    We examine the joint contribution of urban expansion and climate change on heat stress over the Sydney region. A Regional Climate Model was used to downscale present (1990–2009) and future (2040–2059) simulations from a Global Climate Model. The effects of urban surfaces on local temperature and vapor pressure were included. The role of urban expansion in modulating the climate change signal at local scales was investigated using a human heat-stress index combining temperature and vapor pressure. Urban expansion and climate change leads to increased risk of heat-stress conditions in the Sydney region, with substantially more frequent adverse conditions in urban areas. Impacts are particularly obvious in extreme values; daytime heat-stress impacts are more noticeable in the higher percentiles than in the mean values and the impact at night is more obvious in the lower percentiles than in the mean. Urban expansion enhances heat-stress increases due to climate change at night, but partly compensates its effects during the day. These differences are due to a stronger contribution from vapor pressure deficit during the day and from temperature increases during the night induced by urban surfaces. Our results highlight the inappropriateness of assessing human comfort determined using temperature changes alone and point to the likelihood that impacts of climate change assessed using models that lack urban surfaces probably underestimate future changes in terms of human comfort. PMID:25668390

  10. Effects of city expansion on heat stress under climate change conditions.

    PubMed

    Argüeso, Daniel; Evans, Jason P; Pitman, Andrew J; Di Luca, Alejandro

    2015-01-01

    We examine the joint contribution of urban expansion and climate change on heat stress over the Sydney region. A Regional Climate Model was used to downscale present (1990-2009) and future (2040-2059) simulations from a Global Climate Model. The effects of urban surfaces on local temperature and vapor pressure were included. The role of urban expansion in modulating the climate change signal at local scales was investigated using a human heat-stress index combining temperature and vapor pressure. Urban expansion and climate change leads to increased risk of heat-stress conditions in the Sydney region, with substantially more frequent adverse conditions in urban areas. Impacts are particularly obvious in extreme values; daytime heat-stress impacts are more noticeable in the higher percentiles than in the mean values and the impact at night is more obvious in the lower percentiles than in the mean. Urban expansion enhances heat-stress increases due to climate change at night, but partly compensates its effects during the day. These differences are due to a stronger contribution from vapor pressure deficit during the day and from temperature increases during the night induced by urban surfaces. Our results highlight the inappropriateness of assessing human comfort determined using temperature changes alone and point to the likelihood that impacts of climate change assessed using models that lack urban surfaces probably underestimate future changes in terms of human comfort.

  11. The effects of acclimatization on blood clotting parameters in exertional heat stress.

    PubMed

    Vesić, Zoran; Vukasinović-Vesić, Milica; Dincić, Dragan; Surbatović, Maja; Radaković, Sonja S

    2013-07-01

    Exertional heat stress is a common problem in military services. Considering the coagulation abnormalities are of major importance in development of severe heat stroke, we wanted to examine changes in hemostatic parameters in soldiers during exertional heat stress test as well as the effects of a 10-day passive or active acclimatization in a climatic chamber. A total of 40 male soldiers with high aerobic capacity performed exertional heat stress test (EHST) either in cool [20 degrees C, 16 degrees C wet bulb globe temperature (WBGT)], or hot (40 degrees C, 29 degrees C, (WBGT) environment, unacclimatized (U) or after 10 days of passive (P) or active (A) acclimatization. Physiological strain was measured by tympanic temperatures (Tty) and heart rates (HR). Platelet count (PC), antithrombin III (AT), and prothrombin time (PT) were assessed in blood samples collected before and immediately after the EHST. EHST in hot conditions induced physiological heat stress (increase in Tty and HR), with a significant increase in prothrombin time in the groups U and A. Platelet counts were significantly higher after the EHST compared to the basic levels in all the investigated groups, regardless environmental conditions and acclimatization state. Antithrombin levels were not affected by EHST whatsoever. In the trained soldiers, physiological heat stress caused mild changes in some serum parameters of blood clotting such as prothrombin time, while others such as antithrombin levels were not affected. Platelet counts were increased after EHST in all groups. A 10-day passive or active acclimatization in climatic chamber showed no effect on parameters investigated.

  12. Impact of heat stress on crop yield—on the importance of considering canopy temperature

    NASA Astrophysics Data System (ADS)

    Siebert, Stefan; Ewert, Frank; Eyshi Rezaei, Ehsan; Kage, Henning; Graß, Rikard

    2014-04-01

    Increasing crop productivity while simultaneously reducing the environmental footprint of crop production is considered a major challenge for the coming decades. Even short episodes of heat stress can reduce crop yield considerably causing low resource use efficiency. Studies on the impact of heat stress on crop yields over larger regions generally rely on temperatures measured by standard weather stations at 2 m height. Canopy temperatures measured in this study in field plots of rye were up to 7 °C higher than air temperature measured at typical weather station height with the differences in temperatures controlled by soil moisture contents. Relationships between heat stress and grain number derived from controlled environment studies were only confirmed under field conditions when canopy temperature was used to calculate stress thermal time. By using hourly mean temperatures measured by 78 weather stations located across Germany for the period 1994-2009 it is estimated, that mean yield declines in wheat due to heat stress during flowering were 0.7% when temperatures are measured at 2 m height, but yield declines increase to 22% for temperatures measured at the ground. These results suggest that canopy temperature should be simulated or estimated to reduce uncertainty in assessing heat stress impacts on crop yield.

  13. Practices for Alleviating Heat Stress of Dairy Cows in Humid Continental Climates: A Literature Review

    PubMed Central

    Fournel, Sébastien; Ouellet, Véronique; Charbonneau, Édith

    2017-01-01

    Simple Summary The severity of heat stress issues on dairy cows will increase as global warming progresses. Fortunately, major advances in environmental management, including fans, misters, sprinklers, and cooled waterbeds, can attenuate the effects of thermal stress on cow health, production, and reproduction. These cooling systems were, however, tested in subtropical areas and their efficiency in northern regions is uncertain. This article assesses the potential of existing technologies to cool cows in humid continental climates through calculation of heat stress indices. Abstract Heat stress negatively affects the health and performance of dairy cows, resulting in considerable economic losses for the industry. In future years, climate change will exacerbate these losses by making the climate warmer. Physical modification of the environment is considered to be the primary means of reducing adverse effects of hot weather conditions. At present, to reduce stressful heat exposure and to cool cows, dairy farms rely on shade screens and various forms of forced convection and evaporative cooling that may include fans and misters, feed-line sprinklers, and tunnel- or cross-ventilated buildings. However, these systems have been mainly tested in subtropical areas and thus their efficiency in humid continental climates, such as in the province of Québec, Canada, is unclear. Therefore, this study reviewed the available cooling applications and assessed their potential for northern regions. Thermal stress indices such as the temperature-humidity index (THI) were used to evaluate the different cooling strategies. PMID:28468329

  14. Development of a telemetric heat stress monitor. Final report

    SciTech Connect

    1996-10-21

    Hazardous-materials workers and firefighters wear clothing that protects them from external hazards, but the sealed environment of a protective suit makes its wearer susceptible to heat stress. A prototype of the Telemetric Heat Stress Monitor (THSM) was developed at LANL to warn workers, and personnel monitoring the workers, of incipient heat stress by detecting the workers` elevated temperatures and heart rates. The purpose of this CRADA was to transfer the information and technology from LANL to the industrial partner, and to assist in the further development of a commercial THSM product. The THSM is the first extensive telemetric physiological monitor to be developed; previous monitors used wires between the sensors and the recording and display equipment. Developing a reliable, small, battery-powered, inexpensive telemetry system to share the RF spectrum with today`s proliferating wireless devices was a significant technical accomplishment.

  15. Low, medium and high heat tolerant strains of Listeria monocytogenes and increased heat stress resistance after exposure to sublethal heat

    USDA-ARS?s Scientific Manuscript database

    Listeria monocytogenes exhibits sophisticated adaptive mechanisms to counteract higher levels of lethal acid, heat, salt or oxidative stresses after pre-exposure to sublethal concentrations of homogenous stress. A group of 37 strains representing all 13 serotypes of Listeria monocytogenes with initi...

  16. Solar Heating and Cooling: An Economic Assessment.

    ERIC Educational Resources Information Center

    McGarity, Arthur E.

    This study serves as an introduction to the important economic considerations that are necessary for an assessment of the potential for solar heating and cooling in the United States. The first chapter introduces the technology that is used to tap solar energy for residential and commercial applications and illustrates the potential significance…

  17. Survival of heat stress with and without heat hardening in Drosophila melanogaster: interactions with larval density.

    PubMed

    Arias, Leticia N; Sambucetti, Pablo; Scannapieco, Alejandra C; Loeschcke, Volker; Norry, Fabian M

    2012-07-01

    Survival of a potentially lethal high temperature stress is a genetically variable thermal adaptation trait in many organisms. Organisms cope with heat stress by basal or induced thermoresistance. Here, we tested quantitative trait loci (QTL) for heat stress survival (HSS) in Drosophila melanogaster, with and without a cyclic heat-hardening pre-treatment, for flies that were reared at low (LD) or high (HD) density. Mapping populations were two panels of recombinant inbred lines (RIL), which were previously constructed from heat stress-selected stocks: RIL-D48 and RIL-SH2, derived from backcrosses to stocks of low and high heat resistance, respectively. HSS increased with heat hardening in both LD and HD flies. In addition, HSS increased consistently with density in non-hardened flies. There was a significant interaction between heat hardening and density effects in RIL-D48. Several QTL were significant for both density and hardening treatments. Many QTL overlapped with thermotolerance QTL identified for other traits in previous studies based on LD cultures only. However, three new QTL were found in HD only (cytological ranges: 12E-16F6; 30A3-34C2; 49C-50C). Previously found thermotolerance QTL were also significant for flies from HD cultures.

  18. Sequence determinants of prokaryotic gene expression level under heat stress.

    PubMed

    Xiong, Heng; Yang, Yi; Hu, Xiao-Pan; He, Yi-Ming; Ma, Bin-Guang

    2014-11-01

    Prokaryotic gene expression is environment-dependent and temperature plays an important role in shaping the gene expression profile. Revealing the regulation mechanisms of gene expression pertaining to temperature has attracted tremendous efforts in recent years particularly owning to the yielding of transcriptome and proteome data by high-throughput techniques. However, most of the previous works concentrated on the characterization of the gene expression profile of individual organism and little effort has been made to disclose the commonality among organisms, especially for the gene sequence features. In this report, we collected the transcriptome and proteome data measured under heat stress condition from recently published literature and studied the sequence determinants for the expression level of heat-responsive genes on multiple layers. Our results showed that there indeed exist commonness and consistent patterns of the sequence features among organisms for the differentially expressed genes under heat stress condition. Some features are attributed to the requirement of thermostability while some are dominated by gene function. The revealed sequence determinants of bacterial gene expression level under heat stress complement the knowledge about the regulation factors of prokaryotic gene expression responding to the change of environmental conditions. Furthermore, comparisons to thermophilic adaption have been performed to reveal the similarity and dissimilarity of the sequence determinants for the response to heat stress and for the adaption to high habitat temperature, which elucidates the complex landscape of gene expression related to the same physical factor of temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Enemies with benefits: parasitic endoliths protect mussels against heat stress

    NASA Astrophysics Data System (ADS)

    Zardi, G. I.; Nicastro, K. R.; McQuaid, C. D.; Ng, T. P. T.; Lathlean, J.; Seuront, L.

    2016-08-01

    Positive and negative aspects of species interactions can be context dependant and strongly affected by environmental conditions. We tested the hypothesis that, during periods of intense heat stress, parasitic phototrophic endoliths that fatally degrade mollusc shells can benefit their mussel hosts. Endolithic infestation significantly reduced body temperatures of sun-exposed mussels and, during unusually extreme heat stress, parasitised individuals suffered lower mortality rates than non-parasitised hosts. This beneficial effect was related to the white discolouration caused by the excavation activity of endoliths. Under climate warming, species relationships may be drastically realigned and conditional benefits of phototrophic endolithic parasites may become more important than the costs of infestation.

  20. Enemies with benefits: parasitic endoliths protect mussels against heat stress

    PubMed Central

    Zardi, G. I.; Nicastro, K. R.; McQuaid, C. D.; Ng, T. P. T.; Lathlean, J.; Seuront, L.

    2016-01-01

    Positive and negative aspects of species interactions can be context dependant and strongly affected by environmental conditions. We tested the hypothesis that, during periods of intense heat stress, parasitic phototrophic endoliths that fatally degrade mollusc shells can benefit their mussel hosts. Endolithic infestation significantly reduced body temperatures of sun-exposed mussels and, during unusually extreme heat stress, parasitised individuals suffered lower mortality rates than non-parasitised hosts. This beneficial effect was related to the white discolouration caused by the excavation activity of endoliths. Under climate warming, species relationships may be drastically realigned and conditional benefits of phototrophic endolithic parasites may become more important than the costs of infestation. PMID:27506855

  1. Crop heat stress in the context of Earth System modeling

    NASA Astrophysics Data System (ADS)

    Levis, Samuel

    2014-05-01

    Siebert et al (2014 Environ. Res. Lett. 9 044012) suggest that crop models do not represent the effect of heat stress on crop yield adequately unless they apply such effect to sensitive phases in a crop’s growth cycle. Siebert et al focus particularly on the phase considered most sensitive for wheat yield in Germany, the time of anthesis. Siebert et al find that observed canopy rather than 2 m or ground temperature better quantifies the effect of heat stress during anthesis on wheat yield in Germany when evaluated against data from pot experiments under controlled conditions.

  2. Contribution of the Paraventricular Nucleus (PVN) in Autonomic Adjustments to Heat Stress

    PubMed Central

    Leite, Laura H. R.; Zheng, Hong; Coimbra, Cândido C.; Patel, Kaushik P.

    2013-01-01

    We assessed the contribution of the paraventricular nucleus (PVN) in the heat stress-mediated changes in sympathetic nerve activity and blood flow redistribution from the core to the skin surface. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), body and tail temperatures were recorded in anesthetized rats after bilateral microinjection of CSF, lidocaine or L-NMMA into the PVN during heat stress. Heat stress was induced by a graded increase in the temperature of a heating pad for 30 min. Heat stimulus after blockade of the PVN with lidocaine resulted in a blunted RSNA response (ΔRSNA: 117.6 ± 17.0 % vs. 11.3 ± 7.3 %), as well as blunted MAP and HR (ΔMAP: 22 ± 2 mmHg vs. −0.04 ± 7.2 mmHg; ΔHR: 93.4 ± 9.3 bpm vs. 43.4 ± 18.8 bpm). Body temperature threshold for tail vasodilation was unaffected by lidocaine treatment. The increase in RSNA, MAP and HR due to heat stress in L-NMMA-treated rats reached similar levels as CSF treated control rats. However, a higher body temperature threshold for tail vasodilation was observed after L-NMMA injection (37.3 ± 0.1 °C vs. 37.8 ± 0.2°). In conclusion, an intact PVN contributes to an increase in renal sympathetic activity provoked by heat stress, resulting in cardiovascular adjustments that influence core blood redistribution to the periphery. Furthermore, during heat stress, the effect of the PVN on cutaneous vasodilation is dependent on a nitric oxide mechanism. PMID:22619372

  3. Yield-stress fluid drop impact on heated surfaces

    NASA Astrophysics Data System (ADS)

    Blackwell, Brendan; Wu, Alex; Ewoldt, Randy

    2015-11-01

    Yield-stress fluids, including gels and pastes, are effectively fluid at high stress and solid at low stress. In liquid-solid impacts, these fluids can stick and accumulate where they impact, motivating several applications of these rheologically-complex materials. Here we use high-speed imaging to experimentally study liquid-solid impact of yield-stress fluids on heated surfaces. At low temperatures yield-stress fluids tend to stick to surfaces and leave a coating layer. At sufficiently high temperatures the Leidenfrost effect can be observed, wherein a layer of vapor is created between the material and the surface due to rapid boiling, which can prevent a droplet of yield-stress fluid from sticking to the surface. In this study rheological material properties, drop size, drop velocity, and surface temperature are varied to characterize behavioral regimes. Material sticking to and releasing from the surface is observed as a function of the input parameters.

  4. Research in occupational heat stress in India: Challenges and opportunities

    PubMed Central

    Srinivasan, Krishnan; Maruthy, K. N.; Venugopal, Vidhya; Ramaswamy, Padmavathi

    2016-01-01

    Occupational heat stress is a major health burden with several potential negative health and well-being outcomes. It is only in the recent years medical research has addressed this risk factor. The aim of this paper is to present an overview of studies in the area of occupational heat stress and its health impacts. Research in occupational heat stress in developing countries like India is limited because of several challenges and constraints. Few challenges are permission from industries to publish the data, resistance for change from employers and workers, improper record of heat/any occupational disease by the employer or worker, study design, and paucity in number of studies. Proper education and guidelines can help to overcome some of the constraints. Proper and correct guidelines will help in mitigating the effects of excessive heat exposure on the health of workers. The studies in this area are limited, and the association between occupational heat exposure and health impacts is not clearly established. Hence, carefully designed studies are required to examine this association and thereby provide valuable information to protect worker's health. PMID:28194079

  5. Hypersonic Composites Resist Extreme Heat and Stress

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Through research contracts with NASA, Materials and Electrochemical Research Corporation (MER), of Tucson, Arizona, contributed a number of technologies to record-breaking hypersonic flights. Through this research, MER developed a coating that successfully passed testing to simulate Mach 10 conditions, as well as provide several additional carbon-carbon (C-C) composite components for the flights. MER created all of the leading edges for the X-43A test vehicles at Dryden-considered the most critical parts of this experimental craft. In addition to being very heat resistant, the coating had to be very lightweight and thin, as the aircraft was designed to very precise specifications and could not afford to have a bulky coating. MER patented its carbon-carbon (C-C) composite process and then formed a spinoff company, Frontier Materials Corporation (FMC), also based in Tucson. FMC is using the patent in conjunction with low-cost PAN (polyacrylonitrile)-based fibers to introduce these materials to the commercial markets. The C-C composites are very lightweight and exceptionally strong and stiff, even at very high temperatures. The composites have been used in industrial heating applications, the automotive and aerospace industries, as well as in glass manufacturing and on semiconductors. Applications also include transfer components for glass manufacturing and structural members for carrier support in semiconductor processing.

  6. Case studies on heat stress related perceptions in different industrial sectors in southern India

    PubMed Central

    Balakrishnan, Kalpana; Ramalingam, Ayyappan; Dasu, Venkatesan; Stephen, Jeremiah Chinnadurai; Sivaperumal, Mohan Raj; Kumarasamy, Deepan; Mukhopadhyay, Krishnendu; Ghosh, Santu; Sambandam, Sankar

    2010-01-01

    Linkages between thermal loads and its physiological consequences have been widely studied in non-tropical developed country settings. In many developing countries like India, despite the widespread recognition of the problem, limited attempts have been made to estimate health impacts related to occupational heat stress and fewer yet to link heat stress with potential productivity losses. This is reflected in the ubiquity of workplaces with limited or no controls to reduce exposures. As a prelude to understanding the feasibility of alternative interventions in different industrial sectors, we present case studies from 10 different industrial units in Tamil Nadu, Chennai, which describe perceptions of occupational heat stress among the workers and supervisors/management. Units were selected from among those who had previously requested an assessment of workplace heat stress exposure at select locations as part of routine industrial hygiene services provided by the investigators. Since the earlier measurements were performed in response to a management request, all units were revisited to generate a simple job and process profile using checklists in order to understand the overall heat exposure situation in the concerned unit. This was followed by a simple questionnaire administration to a small subsample of employees to evaluate the perceptions of workers and supervisors/management. Finally, we retrieved available quantitative data from previous measurements of heat stress at these units to correlate prevalence of exposures with respective perceptions. Results indicate that the existing level of controls may not be sufficient for managing work-related heat stress in any of the sectors studied, with wide variations in perceived risks. There was a noticeable disconnect between worker's perceptions and their ability to secure workplace improvements related to heat stress from the management. Wider availability of engineering and administrative controls in the

  7. Heat stress and antioxidant enzyme activity in bubaline ( Bubalus bubalis) oocytes during in vitro maturation

    NASA Astrophysics Data System (ADS)

    Waiz, Syma Ashraf; Raies-ul-Haq, Mohammad; Dhanda, Suman; Kumar, Anil; Goud, T. Sridhar; Chauhan, M. S.; Upadhyay, R. C.

    2016-09-01

    In vitro environments like heat stress usually increase the production of reactive oxygen species in bubaline oocytes which have been implicated as one of the major causes for reduced developmental competence. Oocytes during meiotic maturation are sensitive to oxidative stress, and heat stress accelerates cellular metabolism, resulting in the higher production of free radicals. Therefore, the aim of present work was to assess the impact of heat stress during meiotic maturation on bubaline cumulus-oocyte complexes (COC), denuded oocytes (DO), and cumulus cell mass in terms of their oxidative status. Accordingly, for control group, COC were matured at 38.5 °C for complete 24 h of meiotic maturation and heat stress of 40.5 and 41.5 °C was applied to COC during the first 12 h of maturation and then moved to 38.5 °C for rest of the 12 h. In another group, COC after maturation were denuded from the surrounding cumulus cells by manual pipetting. Results indicated that the production of reactive oxygen species (ROS), lipid peroxides, and nitric oxide (NO) was significantly ( P < 0.05) higher in the oocytes subjected to heat stress (40.5 and 41.5 °C) during meiotic maturation compared to the oocytes matured under standard in vitro culture conditions (38.5 °C). Also, the antioxidant enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were significantly ( P < 0.05) increased in all the treatment groups compared to the control group. Therefore, the present study clearly establishes that heat stress ensues oxidative stress in bubaline oocytes which triggers the induction of antioxidant enzymatic defense system for scavenging the ROS.

  8. Heat stress and antioxidant enzyme activity in bubaline (Bubalus bubalis) oocytes during in vitro maturation.

    PubMed

    Waiz, Syma Ashraf; Raies-Ul-Haq, Mohammad; Dhanda, Suman; Kumar, Anil; Goud, T Sridhar; Chauhan, M S; Upadhyay, R C

    2016-09-01

    In vitro environments like heat stress usually increase the production of reactive oxygen species in bubaline oocytes which have been implicated as one of the major causes for reduced developmental competence. Oocytes during meiotic maturation are sensitive to oxidative stress, and heat stress accelerates cellular metabolism, resulting in the higher production of free radicals. Therefore, the aim of present work was to assess the impact of heat stress during meiotic maturation on bubaline cumulus-oocyte complexes (COC), denuded oocytes (DO), and cumulus cell mass in terms of their oxidative status. Accordingly, for control group, COC were matured at 38.5 °C for complete 24 h of meiotic maturation and heat stress of 40.5 and 41.5 °C was applied to COC during the first 12 h of maturation and then moved to 38.5 °C for rest of the 12 h. In another group, COC after maturation were denuded from the surrounding cumulus cells by manual pipetting. Results indicated that the production of reactive oxygen species (ROS), lipid peroxides, and nitric oxide (NO) was significantly (P < 0.05) higher in the oocytes subjected to heat stress (40.5 and 41.5 °C) during meiotic maturation compared to the oocytes matured under standard in vitro culture conditions (38.5 °C). Also, the antioxidant enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were significantly (P < 0.05) increased in all the treatment groups compared to the control group. Therefore, the present study clearly establishes that heat stress ensues oxidative stress in bubaline oocytes which triggers the induction of antioxidant enzymatic defense system for scavenging the ROS.

  9. Assessing the heat tolerance of 17 beef cattle genotypes

    NASA Astrophysics Data System (ADS)

    Gaughan, J. B.; Mader, T. L.; Holt, S. M.; Sullivan, M. L.; Hahn, G. L.

    2010-11-01

    Cattle production plays a significant role in terms of world food production. Nearly 82% of the world's 1.2 billion cattle can be found in developing countries. An increasing demand for meat in developing countries has seen an increase in intensification of animal industries, and a move to cross-bred animals. Heat tolerance is considered to be one of the most important adaptive aspects for cattle, and the lack of thermally-tolerant breeds is a major constraint on cattle production in many countries. There is a need to not only identify heat tolerant breeds, but also heat tolerant animals within a non-tolerant breed. Identification of heat tolerant animals is not easy under field conditions. In this study, panting score (0 to 4.5 scale where 0 = no stress and 4.5 = extreme stress) and the heat load index (HLI) [HLIBG<25°C = 10.66 + 0.28 × rh + 1.30 × BG - WS; and, HLI BG> 25°C = 8.62 + 0.38 × rh + 1.55 × BG - 0.5 × WS + e(2.4 - WS), where BG = black globe temperature (oC), rh = relative humidity (decimal form), WS = wind speed (m/s) and e is the base of the natural logarithm] were used to assess the heat tolerance of 17 genotypes (12,757 steers) within 13 Australian feedlots over three summers. The cattle were assessed under natural climatic conditions in which HLI ranged from thermonuetral (HLI < 70) to extreme (HLI > 96; black globe temperature = 40.2°C, relative humidity = 64%, wind speed = 1.58 m/s). When HLI > 96 a greater number ( P < 0.001) of pure bred Bos taurus and crosses of Bos taurus cattle had a panting score ≥ 2 compared to Brahman cattle, and Brahman-cross cattle. The heat tolerance of the assessed breeds was verified using panting scores and the HLI. Heat tolerance of cattle can be assessed under field conditions by using panting score and HLI.

  10. Assessing the heat tolerance of 17 beef cattle genotypes.

    PubMed

    Gaughan, J B; Mader, T L; Holt, S M; Sullivan, M L; Hahn, G L

    2010-11-01

    Cattle production plays a significant role in terms of world food production. Nearly 82% of the world's 1.2 billion cattle can be found in developing countries. An increasing demand for meat in developing countries has seen an increase in intensification of animal industries, and a move to cross-bred animals. Heat tolerance is considered to be one of the most important adaptive aspects for cattle, and the lack of thermally-tolerant breeds is a major constraint on cattle production in many countries. There is a need to not only identify heat tolerant breeds, but also heat tolerant animals within a non-tolerant breed. Identification of heat tolerant animals is not easy under field conditions. In this study, panting score (0 to 4.5 scale where 0 = no stress and 4.5 = extreme stress) and the heat load index (HLI) [HLI(BG<25°C) = 10.66 + 0.28 × rh + 1.30 × BG - WS; and, HLI (BG> 25°C) = 8.62 + 0.38 × rh + 1.55 × BG - 0.5 × WS + e((2.4 - WS)), where BG = black globe temperature ((o)C), rh = relative humidity (decimal form), WS = wind speed (m/s) and e is the base of the natural logarithm] were used to assess the heat tolerance of 17 genotypes (12,757 steers) within 13 Australian feedlots over three summers. The cattle were assessed under natural climatic conditions in which HLI ranged from thermonuetral (HLI < 70) to extreme (HLI > 96; black globe temperature = 40.2°C, relative humidity = 64%, wind speed = 1.58 m/s). When HLI > 96 a greater number (P < 0.001) of pure bred Bos taurus and crosses of Bos taurus cattle had a panting score ≥ 2 compared to Brahman cattle, and Brahman-cross cattle. The heat tolerance of the assessed breeds was verified using panting scores and the HLI. Heat tolerance of cattle can be assessed under field conditions by using panting score and HLI.

  11. Climate Change and the Emergent Epidemic of CKD from Heat Stress in Rural Communities: The Case for Heat Stress Nephropathy

    PubMed Central

    Glaser, Jason; Lemery, Jay; Rajagopalan, Balaji; Diaz, Henry F.; García-Trabanino, Ramón; Taduri, Gangadhar; Madero, Magdalena; Amarasinghe, Mala; Abraham, Georgi; Anutrakulchai, Sirirat; Jha, Vivekanand; Stenvinkel, Peter; Roncal-Jimenez, Carlos; Lanaspa, Miguel A.; Correa-Rotter, Ricardo; Sheikh-Hamad, David; Burdmann, Emmanuel A.; Andres-Hernando, Ana; Milagres, Tamara; Weiss, Ilana; Kanbay, Mehmet; Wesseling, Catharina; Sánchez-Lozada, Laura Gabriela

    2016-01-01

    Climate change has led to significant rise of 0.8°C–0.9°C in global mean temperature over the last century and has been linked with significant increases in the frequency and severity of heat waves (extreme heat events). Climate change has also been increasingly connected to detrimental human health. One of the consequences of climate-related extreme heat exposure is dehydration and volume loss, leading to acute mortality from exacerbations of pre-existing chronic disease, as well as from outright heat exhaustion and heat stroke. Recent studies have also shown that recurrent heat exposure with physical exertion and inadequate hydration can lead to CKD that is distinct from that caused by diabetes, hypertension, or GN. Epidemics of CKD consistent with heat stress nephropathy are now occurring across the world. Here, we describe this disease, discuss the locations where it appears to be manifesting, link it with increasing temperatures, and discuss ongoing attempts to prevent the disease. Heat stress nephropathy may represent one of the first epidemics due to global warming. Government, industry, and health policy makers in the impacted regions should place greater emphasis on occupational and community interventions. PMID:27151892

  12. Climate Change and the Emergent Epidemic of CKD from Heat Stress in Rural Communities: The Case for Heat Stress Nephropathy.

    PubMed

    Glaser, Jason; Lemery, Jay; Rajagopalan, Balaji; Diaz, Henry F; García-Trabanino, Ramón; Taduri, Gangadhar; Madero, Magdalena; Amarasinghe, Mala; Abraham, Georgi; Anutrakulchai, Sirirat; Jha, Vivekanand; Stenvinkel, Peter; Roncal-Jimenez, Carlos; Lanaspa, Miguel A; Correa-Rotter, Ricardo; Sheikh-Hamad, David; Burdmann, Emmanuel A; Andres-Hernando, Ana; Milagres, Tamara; Weiss, Ilana; Kanbay, Mehmet; Wesseling, Catharina; Sánchez-Lozada, Laura Gabriela; Johnson, Richard J

    2016-08-08

    Climate change has led to significant rise of 0.8°C-0.9°C in global mean temperature over the last century and has been linked with significant increases in the frequency and severity of heat waves (extreme heat events). Climate change has also been increasingly connected to detrimental human health. One of the consequences of climate-related extreme heat exposure is dehydration and volume loss, leading to acute mortality from exacerbations of pre-existing chronic disease, as well as from outright heat exhaustion and heat stroke. Recent studies have also shown that recurrent heat exposure with physical exertion and inadequate hydration can lead to CKD that is distinct from that caused by diabetes, hypertension, or GN. Epidemics of CKD consistent with heat stress nephropathy are now occurring across the world. Here, we describe this disease, discuss the locations where it appears to be manifesting, link it with increasing temperatures, and discuss ongoing attempts to prevent the disease. Heat stress nephropathy may represent one of the first epidemics due to global warming. Government, industry, and health policy makers in the impacted regions should place greater emphasis on occupational and community interventions. Copyright © 2016 by the American Society of Nephrology.

  13. Sympathetic activity during passive heat stress in healthy aged humans

    PubMed Central

    Gagnon, Daniel; Schlader, Zachary J; Crandall, Craig G

    2015-01-01

    Abstract Cardiovascular adjustments during heat stress are generally attenuated in healthy aged humans, which could be due to lower increases in sympathetic activity compared to the young. We compared muscle sympathetic nerve activity (MSNA) between 11 young (Y: 28 ± 4 years) and 10 aged (A: 70 ± 5 years) subjects prior to and during passive heating. Furthermore, MSNA responses were compared when a cold pressor test (CPT) and lower body negative pressure (LBNP) were superimposed upon heating. Baseline MSNA burst frequency (Y: 15 ± 4 vs. A: 31 ± 3 bursts min−1, P ≤ 0.01) and burst incidence (Y: 26 ± 8 vs. A: 50 ± 7 bursts (100 cardiac cycles (CC))−1, P ≤ 0.01) were greater in the aged. Heat stress increased core temperature to a similar extent in both groups (Y: +1.2 ± 0.1 vs. A: +1.2 ± 0.0°C, P = 0.99). Absolute levels of MSNA remained greater in the aged during heat stress (burst frequency: Y: 47 ± 6 vs. A: 63 ± 11 bursts min−1, P ≤ 0.01; burst incidence: Y: 48 ± 8 vs. A: 67 ± 9 bursts (100 CC)−1, P ≤ 0.01); however, the increase in both variables was similar between groups (both P ≥ 0.1). The CPT and LBNP further increased MSNA burst frequency and burst incidence, although the magnitude of increase was similar between groups (both P ≥ 0.07). These results suggest that increases in sympathetic activity during heat stress are not attenuated in healthy aged humans. Key points Cardiovascular adjustments to heat stress are attenuated in healthy aged individuals, which could contribute to their greater prevalence of heat-related illnesses and deaths during heat waves. The attenuated cardiovascular adjustments in the aged could be due to lower increases in sympathetic nerve activity during heat stress. We examined muscle sympathetic nerve activity (MSNA) and plasma catecholamine concentrations in healthy young and aged individuals during whole-body passive heat stress. The main finding

  14. Assessment of Workplace Stress: Occupational Stress, Its Consequences, and Common Causes of Teacher Stress.

    ERIC Educational Resources Information Center

    Hansen, Jo-Ida; Sullivan, Brandon A.

    This chapter introduces teachers and other education professionals to the assessment of occupational stress. It begins with a brief discussion of what occupational stress is, and overview of the consequences of prolonged stress, and a review of the common causes of teacher stress. Next, it presents methods for reducing occupational stress through…

  15. The effects of heat stress on physical functioning in persons with multiple sclerosis.

    PubMed

    Romberg, Anders; Ikonen, Anna; Ruutiainen, Juhani; Virtanen, Arja; Hämäläinen, Päivi

    2012-08-15

    Heat sensitivity is a well-recognised feature in multiple sclerosis (MS). However, little is known about how heat affects physical performance in persons with MS. The objective of the study was to evaluate the effects of short-term heat stress on physical functioning in persons with MS. Twenty-three heat-sensitive MS subjects and 19 healthy controls participated. Moderate heat exposure took place in a dry Finnish sauna. Measures of upper and lower extremity function, static and dynamic balance, and walking capacity were applied. Core body temperature was measured by a telemetric physiological monitoring system. Assessments were conducted before, immediately, 1 hour, and 1 day after the heat exposure. Subjects with MS showed a significantly (P=0.002) higher core body temperature than the controls following the heat stress. Performances in walking (P<0.001), chair rise (P=0.005) and functional reach (P=0.04) were poorer in MS subjects than in controls immediately after the heat. No prolonged heat effects were observed. An increase in ambient temperature causes a higher core body temperature rise in MS subjects than in healthy controls. This rise in temperature is associated with acute, but not prolonged detrimental effects on physical functioning.

  16. Heat index and adjusted temperature as surrogates for wet bulb globe temperature to screen for occupational heat stress.

    PubMed

    Bernard, Thomas E; Iheanacho, Ivory

    2015-01-01

    Ambient temperature and relative humidity are readily ava-ilable and thus tempting metrics for heat stress assessment. Two methods of using air temperature and relative humidity to create an index are Heat Index and Adjusted Temperature. The purposes of this article are: (1) to examine how well Heat Index and Adjusted Temperature estimated the wet bulb globe temperature (WBGT) index, and (2) to suggest how Heat Index and Adjusted Temperature can be used to screen for heat stress level. Psychrometric relationships were used to estimate values of actual WBGT for conditions of air temperature, relative humidity, and radiant heat at an air speed of 0.5 m/s. A relationship between Heat Index [°F] and WBGT [°C] was described by WBGT = -0.0034 HI(2) + 0.96 HI - 34. At lower Heat Index values, the equation estimated WBGTs that were ± 2 °C-WBGT around the actual value, and to about ± 0.5 °C-WBGT for Heat Index values > 100 °F. A relationship between Adjusted Temperature [°F] and WBGT [°C] was described by WBGT = 0.45 Tadj - 16. The actual WBGT was between 1 °C-WBGT below the estimated value and 1.4 °C-WBGT above. That is, there was a slight bias toward overestimating WBGT from Adjusted Temperature. Heat stress screening tables were constructed for metabolic rates of 180, 300, and 450 W. The screening decisions were divided into four categories: (1) < alert limit, (2) < exposure limit, (3) hourly time-weighted averages (TWAs) of work and recovery, and (4) a caution zone for an exposure > exposure limit at rest. The authors do not recommend using Heat Index or Adjusted Temperature instead of WBGT, but they may be used to screen for circumstances when a more detailed analysis using WBGT is appropriate. A particular weakness is accounting for radiant heat; and neither air speed nor clothing was considered.

  17. Antioxidant Properties of the Mung Bean Flavonoids on Alleviating Heat Stress

    PubMed Central

    Che, Huilian; Cao, Jiankang; Yang, Liu; Zhu, Chunqiu; Jiang, Weibo

    2011-01-01

    Background It is a widespread belief in Asian countries that mung bean soup (MBS) may afford a protective effect against heat stress. Lack of evidence supports MBS conferring a benefit in addition to water. Results Here we show that vitexin and isovitexin are the major antioxidant components in mungbean (more than 96% of them existing in the bean seed coat), and both of them could be absorbed via gavage into rat plasma. In the plasma of rats fed with mungbean coat extract before or after exposure to heat stress, the levels of malonaldehyde and activities of lactate dehydrogenase and nitric oxide synthase were remarkably reduced; the levels of total antioxidant capacity and glutathione (a quantitative assessment of oxidative stress) were significantly enhanced. Conclusions Our results demonstrate that MBS can play additional roles to prevent heat stress injury. Characterization of the mechanisms underlying mungbean beneficial effects should help in the design of diet therapy strategies to alleviate heat stress, as well as provide reference for searching natural medicines against oxidative stress induced diseases. PMID:21695166

  18. Body Temperature Versus Microclimate Selection in Heat Stressed Dairy Cows

    USDA-ARS?s Scientific Manuscript database

    The purpose of this study is to characterize the thermoregulatory responses of unrestrained heat-stressed dairy cows within a freestall environment using fan and spray configurations for cooling cows while lying or standing. An experimental treatment sprayed individual cows lying in freestalls from ...

  19. Mechanisms of Aerobic Performance Impairment With Heat Stress and Dehydration

    DTIC Science & Technology

    2010-08-01

    Jones (65) demonstrated that a menthol mouth rinse reduced RPE (com- pared with placebo) by 15% and improved TTE by 9% during exercise-heat stress...potentials. Appl Physiol Nutr Metab 35: 456–463, 2010. 65. Mundel T, Jones DA. The effects of swilling an l()- menthol solution during exercise in the

  20. Genetic solutions to infertility caused by heat stress

    USDA-ARS?s Scientific Manuscript database

    Reproductive function in mammals is very susceptible to disruption by heat stress. In lactating dairy cows, for example, pregnancy rates per insemination can be as low as 10-15% in the summer vs. 25-40% in cool weather. Reduced fertility in females is caused by a combination of 1) the negative cons...

  1. Peripheral vascular responses to heat stress after hindlimb suspension

    NASA Technical Reports Server (NTRS)

    Looft-Wilson, Robin C.; Gisolfi, Carl V.

    2002-01-01

    PURPOSE: The purpose of this study was to determine whether hindlimb suspension (which simulates the effects of microgravity) results in impaired hemodynamic responses to heat stress or alterations in mesenteric small artery sympathetic nerve innervation. METHODS: Over 28 d, 16 male Sprague-Dawley rats were hindlimb-suspended, and 13 control rats were housed in the same type of cage. After the treatment, mean arterial pressure (MAP), colonic temperature (Tcol), and superior mesenteric and iliac artery resistances (using Doppler flowmetry) were measured during heat stress [exposure to 42 degrees C until the endpoint of 80 mm Hg blood pressure was reached (75 +/- 9 min); endpoint Tcore = 43.6 +/- 0.2] while rats were anesthetized (sodium pentobarbital, 50 mg x kg(-1) BW). RESULTS: Hindlimb-suspended and control rats exhibited similar increases in Tcol, MAP, and superior mesenteric artery resistance, and similar decreases in iliac resistance during heat stress (endpoint was a fall in MAP below 80 mm Hg). Tyrosine hydroxylase immunostaining indicated similar sympathetic nerve innervation in small mesenteric arteries from both groups. CONCLUSION: Hindlimb suspension does not alter the hemodynamic or thermoregulatory responses to heat stress in the anesthetized rat or mesenteric sympathetic nerve innervation, suggesting that this sympathetic pathway is intact.

  2. Peripheral vascular responses to heat stress after hindlimb suspension

    NASA Technical Reports Server (NTRS)

    Looft-Wilson, Robin C.; Gisolfi, Carl V.

    2002-01-01

    PURPOSE: The purpose of this study was to determine whether hindlimb suspension (which simulates the effects of microgravity) results in impaired hemodynamic responses to heat stress or alterations in mesenteric small artery sympathetic nerve innervation. METHODS: Over 28 d, 16 male Sprague-Dawley rats were hindlimb-suspended, and 13 control rats were housed in the same type of cage. After the treatment, mean arterial pressure (MAP), colonic temperature (Tcol), and superior mesenteric and iliac artery resistances (using Doppler flowmetry) were measured during heat stress [exposure to 42 degrees C until the endpoint of 80 mm Hg blood pressure was reached (75 +/- 9 min); endpoint Tcore = 43.6 +/- 0.2] while rats were anesthetized (sodium pentobarbital, 50 mg x kg(-1) BW). RESULTS: Hindlimb-suspended and control rats exhibited similar increases in Tcol, MAP, and superior mesenteric artery resistance, and similar decreases in iliac resistance during heat stress (endpoint was a fall in MAP below 80 mm Hg). Tyrosine hydroxylase immunostaining indicated similar sympathetic nerve innervation in small mesenteric arteries from both groups. CONCLUSION: Hindlimb suspension does not alter the hemodynamic or thermoregulatory responses to heat stress in the anesthetized rat or mesenteric sympathetic nerve innervation, suggesting that this sympathetic pathway is intact.

  3. Body Temperature Versus Microclimate Selection in Heat Stressed Dairy Cows

    USDA-ARS?s Scientific Manuscript database

    The purpose of this study is to characterize the thermoregulatory responses of unrestrained heat-stressed dairy cows within a freestall environment using fan and spray configurations for cooling cows while lying or standing. An experimental treatment sprayed individual cows lying in freestalls from ...

  4. Simulating canopy temperature for modelling heat stress in cereals

    USDA-ARS?s Scientific Manuscript database

    Crop models must be improved to account for the large effects of heat stress effects on crop yields. To date, most approaches in crop models use air temperature despite evidence that crop canopy temperature better explains yield reductions associated with high temperature events. This study presents...

  5. Causes, effects and molecular mechanisms of testicular heat stress.

    PubMed

    Durairajanayagam, Damayanthi; Agarwal, Ashok; Ong, Chloe

    2015-01-01

    The process of spermatogenesis is temperature-dependent and occurs optimally at temperatures slightly lower than that of the body. Adequate thermoregulation is imperative to maintain testicular temperatures at levels lower than that of the body core. Raised testicular temperature has a detrimental effect on mammalian spermatogenesis and the resultant spermatozoa. Therefore, thermoregulatory failure leading to heat stress can compromise sperm quality and increase the risk of infertility. In this paper, several different types of external and internal factors that may contribute towards testicular heat stress are reviewed. The effects of heat stress on the process of spermatogenesis, the resultant epididymal spermatozoa and on germ cells, and the consequent changes in the testis are elaborated upon. We also discuss the molecular response of germ cells to heat exposure and the possible mechanisms involved in heat-induced germ cell damage, including apoptosis, DNA damage and autophagy. Further, the intrinsic and extrinsic pathways that are involved in the intricate mechanism of germ cell apoptosis are explained. Ultimately, these complex mechanisms of apoptosis lead to germ cell death. Copyright © 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  6. A Chrysanthemum Heat Shock Protein Confers Tolerance to Abiotic Stress

    PubMed Central

    Song, Aiping; Zhu, Xirong; Chen, Fadi; Gao, Haishun; Jiang, Jiafu; Chen, Sumei

    2014-01-01

    Heat shock proteins are associated with protection against various abiotic stresses. Here, the isolation of a chrysanthemum cDNA belonging to the HSP70 family is reported. The cDNA, designated CgHSP70, encodes a 647-residue polypeptide, of estimated molecular mass 70.90 kDa and pI 5.12. A sub-cellular localization assay indicated that the cDNA product is deposited in the cytoplasm and nucleus. The performance of Arabidopsis thaliana plants constitutively expressing CgHSP70 demonstrated that the gene enhances tolerance to heat, drought and salinity. When CgHSP70 was stably over-expressed in chrysanthemum, the plants showed an increased peroxidase (POD) activity, higher proline content and inhibited malondialdehyde (MDA) content. After heat stress, drought or salinity the transgenic plants were better able to recover, demonstrating CgHSP70 positive effect. PMID:24663057

  7. COMPARISON OF PHYSIOLOGICAL REACTIONS AND PHYSIOLOGICAL STRAIN IN HEALTHY MEN UNDER HEAT STRESS IN DRY AND STEAM HEAT SAUNAS

    PubMed Central

    Pilch, W.; Palka, T.; Pilch, P.; Cison, T.; Wiecha, S.; Tota, Ł.

    2014-01-01

    The aim of the paper was to follow up major physiological reactions, provoked by heat stress during dry and wet sauna baths. A physical strain index and subjective estimation of heat comfort of subjects who had not taken sauna baths before was also evaluated. Ten healthy males aged 25-28 underwent a dry sauna bath and then after a one-month break they underwent a steam sauna bath. Each time, they entered the sauna chamber 3 times for 15 minutes with five-minute breaks. During breaks they cooled their bodies with a cold shower and then rested in a sitting position. Before and after the baths, body mass and blood pressure were measured. Rectal temperature and heart rate were monitored during the baths. The physiological strain index (PSI) and cumulative heat strain index (CHSI) were calculated. Subjects assessed heat comfort by Bedford's scale. Greater body mass losses were observed after the dry sauna bath compared to the wet sauna (-0.72 vs. -0.36 kg respectively). However, larger increases in rectal temperature and heart rate were observed during the wet sauna bath (38.8% and 21.2% respectively). Both types of sauna baths caused elevation of systolic blood pressure, but changes were greater after the dry one. Diastolic pressure was reduced similarly. Subjective feelings of heat comfort as well as PSI (4.83 ± 0.29 vs. 5.7 ± 0.28) and CHSI (76.3 ± 18.4 vs. 144.6 ± 21.7) were greater during the wet sauna bath. It can be concluded that due to high humidity and reduction of thermoregulation mechanisms, the wet sauna is more stressful for the organism than the dry sauna, where the temperature is higher with low humidity. Both observed indexes (PSI and CHSI) could be appropriate for objective assessment of heat strain during passive heating of the organism. PMID:24899780

  8. Comparison of physiological reactions and physiological strain in healthy men under heat stress in dry and steam heat saunas.

    PubMed

    Pilch, W; Szygula, Z; Palka, T; Pilch, P; Cison, T; Wiecha, S; Tota, L

    2014-06-01

    The aim of the paper was to follow up major physiological reactions, provoked by heat stress during dry and wet sauna baths. A physical strain index and subjective estimation of heat comfort of subjects who had not taken sauna baths before was also evaluated. Ten healthy males aged 25-28 underwent a dry sauna bath and then after a one-month break they underwent a steam sauna bath. Each time, they entered the sauna chamber 3 times for 15 minutes with five-minute breaks. During breaks they cooled their bodies with a cold shower and then rested in a sitting position. Before and after the baths, body mass and blood pressure were measured. Rectal temperature and heart rate were monitored during the baths. The physiological strain index (PSI) and cumulative heat strain index (CHSI) were calculated. Subjects assessed heat comfort by Bedford's scale. Greater body mass losses were observed after the dry sauna bath compared to the wet sauna (-0.72 vs. -0.36 kg respectively). However, larger increases in rectal temperature and heart rate were observed during the wet sauna bath (38.8% and 21.2% respectively). Both types of sauna baths caused elevation of systolic blood pressure, but changes were greater after the dry one. Diastolic pressure was reduced similarly. Subjective feelings of heat comfort as well as PSI (4.83 ± 0.29 vs. 5.7 ± 0.28) and CHSI (76.3 ± 18.4 vs. 144.6 ± 21.7) were greater during the wet sauna bath. It can be concluded that due to high humidity and reduction of thermoregulation mechanisms, the wet sauna is more stressful for the organism than the dry sauna, where the temperature is higher with low humidity. Both observed indexes (PSI and CHSI) could be appropriate for objective assessment of heat strain during passive heating of the organism.

  9. Pathway to a Phenocopy: Heat Stress Effects in Early Embryogenesis

    PubMed Central

    Crews, Sarah M.; McCleery, W. Tyler; Hutson, M. Shane

    2015-01-01

    Background Heat shocks applied at the onset of gastrulation in early Drosophila embryos frequently lead to phenocopies of U-shaped mutants – having characteristic failures in the late morphogenetic processes of germband retraction and dorsal closure. The pathway from non-specific heat stress to phenocopied abnormalities is unknown. Results Drosophila embryos subjected to 30-min, 38-°C heat shocks at gastrulation appear to recover and restart morphogenesis. Post-heat-shock development appears normal, albeit slower, until a large fraction of embryos develop amnioserosa holes (diameters > 100 μm). These holes are positively correlated with terminal U-shaped phenocopies. They initiate between amnioserosa cells and open over tens of minutes by evading normal wound healing responses. They are not caused by tissue-wide increases in mechanical stress or decreases in cell-cell adhesion, but instead appear to initiate from isolated apoptosis of amnioserosa cells. Conclusions The pathway from heat shock to U-shaped phenocopies involves the opening of one or more large holes in the amnioserosa that compromise its structural integrity and lead to failures in morphogenetic processes that rely on amnioserosa-generated tensile forces. The proposed mechanism by which heat shock leads to hole initiation and expansion is heterochonicity – i.e., disruption of morphogenetic coordination between embryonic and extra-embryonic cell types. PMID:26498920

  10. Heat stress and thermal strain challenges in running.

    PubMed

    Bergeron, Michael F

    2014-10-01

    Running well and safely in the heat is challenging for all runners, from recreational to elite. As environmental heat stress (heat stress modulated or augmented by air temperature, humidity, wind speed, and solar radiation) and the intensity and duration of a training run or race increase, so are metabolic heat production, the parallel need for heat transfer from the body to maintain thermal equilibrium, the consequent increase in blood flow to the skin, and the concomitant sweating response progressively and proportionally amplified. An accumulating total body-water deficit from extensive sweating and escalating level of cardiovascular and thermal strain will, in due course, considerably challenge a runner's physiology, perception of effort, and on-course well-being and performance. However, with the appropriate preparation and modifications to planned running intensity and distance, runners can safely tolerate and effectively train and compete in a wide range of challenging environmental conditions. Clinicians play a key role in this regard as an effective resource for providing the most effective guidelines and making the best overall individual recommendations regarding training and competing in the heat.

  11. Pathway to a phenocopy: Heat stress effects in early embryogenesis.

    PubMed

    Crews, Sarah M; McCleery, W Tyler; Hutson, M Shane

    2016-03-01

    Heat shocks applied at the onset of gastrulation in early Drosophila embryos frequently lead to phenocopies of U-shaped mutants-having characteristic failures in the late morphogenetic processes of germband retraction and dorsal closure. The pathway from nonspecific heat stress to phenocopied abnormalities is unknown. Drosophila embryos subjected to 30-min, 38 °C heat shocks at gastrulation appear to recover and restart morphogenesis. Post-heat-shock development appears normal, albeit slower, until a large fraction of embryos develop amnioserosa holes (diameters > 100 µm). These holes are positively correlated with terminal U-shaped phenocopies. They initiate between amnioserosa cells and open over tens of minutes by evading normal wound healing responses. They are not caused by tissue-wide increases in mechanical stress or decreases in cell-cell adhesion, but instead appear to initiate from isolated apoptosis of amnioserosa cells. The pathway from heat shock to U-shaped phenocopies involves the opening of one or more large holes in the amnioserosa that compromise its structural integrity and lead to failures in morphogenetic processes that rely on amnioserosa-generated tensile forces. The proposed mechanism by which heat shock leads to hole initiation and expansion is heterochonicity, i.e., disruption of morphogenetic coordination between embryonic and extra-embryonic cell types. © 2015 Wiley Periodicals, Inc.

  12. The effect of heat stress on skeletal muscle contractile properties.

    PubMed

    Locke, Marius; Celotti, Carlo

    2014-07-01

    An elevated heat-shock protein (HSP) content protects cells and tissues, including skeletal muscles, from certain stressors. We determined if heat stress and the elevated HSP content that results is correlated with protection of contractile characteristics of isolated fast and slow skeletal muscles when contracting at elevated temperatures. To elevate muscle HSP content, one hindlimb of Sprague-Dawley rats (21-28 days old, 70-90 g) was subjected to a 15 min 42 °C heat-stress. Twenty-four hours later, both extensor digitorum longus (EDL) and soleus muscles were removed, mounted in either 20 °C or 42 °C Krebs-Ringer solution, and electrically stimulated. Controls consisted of the same muscles from the contra-lateral (non-stressed) hindlimbs as well as muscles from other (unstressed) animals. Isolated muscles were twitched and brought to tetanus every 5 min for 30 min. As expected, HSP content was elevated in muscles from the heat-stressed limbs when compared with controls. Regardless of prior treatment, both EDL and soleus twitch tensions were lower at 42 °C when compared with 20 °C. In addition, when incubated at 42 °C, both muscles showed a drop in twitch tension between 5 and 30 min. For tetanic tension, both muscles also showed an increase in tension between 5 and 30 min when stimulated at 20 °C regardless of treatment but when stimulated at 42 °C no change was observed. No protective effect of an elevated HSP content was observed for either muscle. In conclusion, although heat stress caused an elevation in HSP content, no protective effects were conferred to isolated contracting muscles.

  13. Heat shock proteins in relation to heat stress tolerance of creeping bentgrass at different N levels.

    PubMed

    Wang, Kehua; Zhang, Xunzhong; Goatley, Mike; Ervin, Erik

    2014-01-01

    Heat stress is a primary factor causing summer bentgrass decline. Changes in gene expression at the transcriptional and/or translational level are thought to be a fundamental mechanism in plant response to environmental stresses. Heat stress redirects protein synthesis in higher plants and results in stress protein synthesis, particularly heat shock proteins (HSPs). The goal of this work was to analyze the expression pattern of major HSPs in creeping bentgrass (Agrostis stolonifera L.) during different heat stress periods and to study the influence of nitrogen (N) on the HSP expression patterns. A growth chamber study on 'Penn-A4' creeping bentgrass subjected to 38/28°C day/night for 50 days, was conducted with four nitrate rates (no N-0, low N-2.5, medium N-7.5, and high N-12.5 kg N ha-1) applied biweekly. Visual turfgrass quality (TQ), normalized difference vegetation index (NDVI), photochemical efficiency of photosystem II (Fv/Fm), shoot electrolyte leakage (ShEL), and root viability (RV) were monitored, along with the expression pattern of HSPs. There was no difference in measured parameters between treatments until week seven, except TQ at week five. At week seven, grass at medium N had better TQ, NDVI, and Fv/Fm accompanied by lower ShEL and higher RV, suggesting a major role in improved heat tolerance. All the investigated HSPs (HSP101, HSP90, HSP70, and sHSPs) were up-regulated by heat stress. Their expression patterns indicated cooperation between different HSPs and their roles in bentgrass thermotolerance. In addition, their production seems to be resource dependent. This study could further improve our understanding about how different N levels affect bentgrass thermotolerance.

  14. Heat Shock Proteins in Relation to Heat Stress Tolerance of Creeping Bentgrass at Different N Levels

    PubMed Central

    Wang, Kehua; Zhang, Xunzhong; Goatley, Mike; Ervin, Erik

    2014-01-01

    Heat stress is a primary factor causing summer bentgrass decline. Changes in gene expression at the transcriptional and/or translational level are thought to be a fundamental mechanism in plant response to environmental stresses. Heat stress redirects protein synthesis in higher plants and results in stress protein synthesis, particularly heat shock proteins (HSPs). The goal of this work was to analyze the expression pattern of major HSPs in creeping bentgrass (Agrostis stolonifera L.) during different heat stress periods and to study the influence of nitrogen (N) on the HSP expression patterns. A growth chamber study on ‘Penn-A4’ creeping bentgrass subjected to 38/28°C day/night for 50 days, was conducted with four nitrate rates (no N-0, low N-2.5, medium N-7.5, and high N-12.5 kg N ha−1) applied biweekly. Visual turfgrass quality (TQ), normalized difference vegetation index (NDVI), photochemical efficiency of photosystem II (Fv/Fm), shoot electrolyte leakage (ShEL), and root viability (RV) were monitored, along with the expression pattern of HSPs. There was no difference in measured parameters between treatments until week seven, except TQ at week five. At week seven, grass at medium N had better TQ, NDVI, and Fv/Fm accompanied by lower ShEL and higher RV, suggesting a major role in improved heat tolerance. All the investigated HSPs (HSP101, HSP90, HSP70, and sHSPs) were up-regulated by heat stress. Their expression patterns indicated cooperation between different HSPs and their roles in bentgrass thermotolerance. In addition, their production seems to be resource dependent. This study could further improve our understanding about how different N levels affect bentgrass thermotolerance. PMID:25050702

  15. Urban heat stress: novel survey suggests health and fitness as future avenue for research and adaptation strategies

    NASA Astrophysics Data System (ADS)

    Schuster, Christian; Honold, Jasmin; Lauf, Steffen; Lakes, Tobia

    2017-04-01

    Extreme heat has tremendous adverse effects on human health. Heat stress is expected to further increase due to urbanization, an aging population, and global warming. Previous research has identified correlations between extreme heat and mortality. However, the underlying physical, behavioral, environmental, and social risk factors remain largely unknown and comprehensive quantitative investigation on an individual level is lacking. We conducted a new cross-sectional household questionnaire survey to analyze individual heat impairment (self-assessed and reported symptoms) and a large set of potential risk factors in the city of Berlin, Germany. This unique dataset (n = 474) allows for the investigation of new relationships, especially between health/fitness and urban heat stress. Our analysis found previously undocumented associations, leading us to generate new hypotheses for future research: various health/fitness variables returned the strongest associations with individual heat stress. Our primary hypothesis is that age, the most commonly used risk factor, is outperformed by health/fitness as a dominant risk factor. Related variables seem to more accurately represent humans’ cardiovascular capacity to handle elevated temperature. Among them, active travel was associated with reduced heat stress. We observed statistical associations for heat exposure regarding the individual living space but not for the neighborhood environment. Heat stress research should further investigate individual risk factors of heat stress using quantitative methodologies. It should focus more on health and fitness and systematically explore their role in adaptation strategies. The potential of health and fitness to reduce urban heat stress risk means that encouraging active travel could be an effective adaptation strategy. Through reduced CO2 emissions from urban transport, societies could reap double rewards by addressing two root causes of urban heat stress: population health and

  16. Effects of heat-stress on production in dairy cattle.

    PubMed

    West, J W

    2003-06-01

    The southeastern United States is characterized as humid subtropical and is subject to extended periods of high ambient temperature and relative humidity. Because the primary nonevaporative means of cooling for the cow (radiation, conduction, convection) become less effective with rising ambient temperature, the cow becomes increasingly reliant upon evaporative cooling in the form of sweating and panting. High relative humidity compromises evaporative cooling, so that under hot, humid conditions common to the Southeast in summer the dairy cow cannot dissipate sufficient body heat to prevent a rise in body temperature. Increasing air temperature, temperature-humidity index and rising rectal temperature above critical thresholds are related to decreased dry matter intake (DMI) and milk yield and to reduced efficiency of milk yield. Modifications including shade, barns which enhance passive ventilation, and the addition of fans and sprinklers increase body heat loss, lowering body temperature and improving DMI. New technologies including tunnel ventilation are being investigated to determine if they offer cooling advantages. Genetic selection for heat tolerance may be possible, but continued selection for greater performance in the absence of consideration for heat tolerance will result in greater susceptibility to heat stress. The nutritional needs of the cow change during heat stress, and ration reformulation to account for decreased DMI, the need to increase nutrient density, changing nutrient requirements, avoiding nutrient excesses and maintenance of normal rumen function is necessary. Maintaining cow performance in hot, humid climatic conditions in the future will likely require improved cooling capability, continued advances in nutritional formulation, and the need for genetic advancement which includes selection for heat tolerance or the identification of genetic traits which enhance heat tolerance.

  17. When defense pathways collide. The response of Arabidopsis to a combination of drought and heat stress.

    PubMed

    Rizhsky, Ludmila; Liang, Hongjian; Shuman, Joel; Shulaev, Vladimir; Davletova, Sholpan; Mittler, Ron

    2004-04-01

    Within their natural habitat, plants are subjected to a combination of abiotic conditions that include stresses such as drought and heat. Drought and heat stress have been extensively studied; however, little is known about how their combination impacts plants. The response of Arabidopsis plants to a combination of drought and heat stress was found to be distinct from that of plants subjected to drought or heat stress. Transcriptome analysis of Arabidopsis plants subjected to a combination of drought and heat stress revealed a new pattern of defense response in plants that includes a partial combination of two multigene defense pathways (i.e. drought and heat stress), as well as 454 transcripts that are specifically expressed in plants during a combination of drought and heat stress. Metabolic profiling of plants subjected to drought, heat stress, or a combination of drought and heat stress revealed that plants subject to a combination of drought and heat stress accumulated sucrose and other sugars such as maltose and glucose. In contrast, Pro that accumulated in plants subjected to drought did not accumulate in plants during a combination of drought and heat stress. Heat stress was found to ameliorate the toxicity of Pro to cells, suggesting that during a combination of drought and heat stress sucrose replaces Pro in plants as the major osmoprotectant. Our results highlight the plasticity of the plant genome and demonstrate its ability to respond to complex environmental conditions that occur in the field.

  18. Muscle-damaging exercise increases heat strain during subsequent exercise heat stress.

    PubMed

    Fortes, Matthew Benjamin; Di Felice, Umberto; Dolci, Alberto; Junglee, Naushad A; Crockford, Michael J; West, Liam; Hillier-Smith, Ryan; Macdonald, Jamie Hugo; Walsh, Neil Peter

    2013-10-01

    It remains unclear whether exercise-induced muscle damage (EIMD) increases heat strain during subsequent exercise heat stress, which in turn may increase the risk of exertional heat illness. We examined heat strain during exercise heat stress 30 min after EIMD to coincide with increases in circulating pyrogens (e.g., interleukin-6 [IL-6]) and 24 h after EIMD to coincide with the delayed muscle inflammatory response when a higher rate of metabolic energy expenditure (M˙) and thus decreased economy might also increase heat strain. Thirteen non-heat-acclimated males (mean ± SD, age = 20 ± 2 yr) performed exercise heat stress tests (running for 40 min at 65% V˙O2max in 33°C, 50% humidity) 30 min (HS1) and 24 h (HS2) after treatment, involving running for 60 min at 65% V˙O2max on either -10% gradient (EIMD) or +1% gradient (CON) in a crossover design. Rectal (Tre) and skin (Tsk) temperature, local sweating rate, and M˙ were measured throughout HS tests. Compared with CON, EIMD evoked higher circulating IL-6 pre-HS1 (P < 0.01) and greater plasma creatine kinase and muscle soreness pre-HS2 (P < 0.01). The ΔTre was greater after EIMD than CON during HS1 (0.35°C, 95% confidence interval = 0.11°C-0.58°C, P < 0.01) and HS2 (0.17°C, 95% confidence interval = 0.07°C-0.28°C, P < 0.01). M˙ was higher on EIMD throughout HS1 and HS2 (P < 0.001). Thermoeffector responses (Tsk, sweating rate) were not altered by EIMD. Thermal sensation and RPE were higher on EIMD after 25 min during HS1 (P < 0.05). The final Tre during HS1 correlated with the pre-HS1 circulating IL-6 concentration (r = 0.67). Heat strain was increased during endurance exercise in the heat conducted 30 min after and, to a much lesser extent, 24 h after muscle-damaging exercise. These data indicate that EIMD is a likely risk factor for exertional heat illness particularly during exercise heat stress when behavioral thermoregulation cues are ignored.

  19. An adaptability limit to climate change due to heat stress

    PubMed Central

    Sherwood, Steven C.; Huber, Matthew

    2010-01-01

    Despite the uncertainty in future climate-change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation. Peak heat stress, quantified by the wet-bulb temperature TW, is surprisingly similar across diverse climates today. TW never exceeds 31 °C. Any exceedence of 35 °C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible. While this never happens now, it would begin to occur with global-mean warming of about 7 °C, calling the habitability of some regions into question. With 11–12 °C warming, such regions would spread to encompass the majority of the human population as currently distributed. Eventual warmings of 12 °C are possible from fossil fuel burning. One implication is that recent estimates of the costs of unmitigated climate change are too low unless the range of possible warming can somehow be narrowed. Heat stress also may help explain trends in the mammalian fossil record. PMID:20439769

  20. Modelling the heat stress and the recovery of bacterial spores.

    PubMed

    Mafart, P; Leguérinel, I

    1997-07-22

    After heat treatment, the temperature incubation and the medium composition, (pH and sodium chloride content) influence the capacity of injured spores to repair heat damage. The concept of heat resistance D- (decimal reduction time) and z-values (temperature increase which results in a ten fold reduction of the D value) is not sufficient and the ratio of spore recovery after incubation should be considered in calculations used in thermal processing of food. This paper aims to derive a model describing the recovery of injured spores as a function of both the heat treatment intensity and the environmental conditions. According to data from numerous investigators, when spores are incubated in unfavorable conditions, the ratio of cell recovery and the apparent D-value are reduced. Moreover the ratio of the apparent D-value and the estimated in optimal incubation D-value is constant and independent of the heat treatment conditions. Beyond these observations it is shown that the ratio of cell recovery with respect to the heat treatment F-value (exposure time, in minutes, at 121.1 degrees C which results in the same destruction ratio that the considered heat treatment does) is linear and can be quantified by using two factors independent of the heat treatment: the gamma-factor reflects the degree of precariousness due to the heat stress while the epsilon-factor reflects more intrinsically the incubation conditions without previous heat treatment. The gamma-factor varies as a function of the incubation temperature according to an Arrhenius law.

  1. Assessment of next generation nuclear plant intermediate heat exchanger design.

    SciTech Connect

    Majumdar, S.; Moisseytsev, A.; Natesan, K.; Nuclear Engineering Division

    2008-10-17

    The Next Generation Nuclear Plant (NGNP), which is an advanced high temperature gas reactor (HTGR) concept with emphasis on production of both electricity and hydrogen, involves helium as the coolant and a closed-cycle gas turbine for power generation with a core outlet/gas turbine inlet temperature of 900-1000 C. In the indirect cycle system, an intermediate heat exchanger is used to transfer the heat from primary helium from the core to the secondary fluid, which can be helium, nitrogen/helium mixture, or a molten salt. The system concept for the vary high temperature reactor (VHTR) can be a reactor based on the prismatic block of the GT-MHR developed by a consortium led by General Atomics in the U.S. or based on the PBMR design developed by ESKOM of South Africa and British Nuclear Fuels of U.K. This report has made an assessment on the issues pertaining to the intermediate heat exchanger (IHX) for the NGNP. A detailed thermal hydraulic analysis, using models developed at ANL, was performed to calculate heat transfer, temperature distribution, and pressure drop. Two IHX designs namely, shell and straight tube and compact heat exchangers were considered in an earlier assessment. Helical coil heat exchangers were analyzed in the current report and the results were compared with the performance features of designs from industry. In addition, a comparative analysis is presented between the shell and straight tube, helical, and printed circuit heat exchangers from the standpoint of heat exchanger volume, primary and secondary sides pressure drop, and number of tubes. The IHX being a high temperature component, probably needs to be designed using ASME Code Section III, Subsection NH, assuming that the IHX will be classified as a class 1 component. With input from thermal hydraulic calculations performed at ANL, thermal conduction and stress analyses were performed for the helical heat exchanger design and the results were compared with earlier-developed results on

  2. Single nucleotide polymorphisms associated with thermoregulation in lactating dairy cows exposed to heat stress.

    PubMed

    Dikmen, S; Wang, X-z; Ortega, M S; Cole, J B; Null, D J; Hansen, P J

    2015-12-01

    Dairy cows with increased rectal temperature experience lower milk yield and fertility. Rectal temperature during heat stress is heritable, so genetic selection for body temperature regulation could reduce effects of heat stress on production. One aim of the study was to validate the relationship between genotype and heat tolerance for single nucleotide polymorphisms (SNPs) previously associated with resistance to heat stress. A second aim was to identify new SNPs associated with heat stress resistance. Thermotolerance was assessed in lactating Holsteins during the summer by measuring rectal temperature (a direct measurement of body temperature regulation; n = 435), respiration rate (an indirect measurement of body temperature regulation, n = 450) and sweating rate (the major evaporative cooling mechanism in cattle, n = 455). The association between genotype and thermotolerance was evaluated for 19 SNPs previously associated with rectal temperature from a genomewide analysis study (GWAS), four SNPs previously associated with change in milk yield during heat stress from GWAS, 2 candidate gene SNPs previously associated with rectal temperature and respiration rate during heat stress (ATPA1A and HSP70A) and 66 SNPs in genes previously shown to be associated with reproduction, production or health traits in Holsteins. For SNPs previously associated with heat tolerance, regions of BTA4, BTA6 and BTA24 were associated with rectal temperature; regions of BTA6 and BTA24 were associated with respiration rate; and regions of BTA5, BTA26 and BTA29 were associated with sweating rate. New SNPs were identified for rectal temperature (n = 12), respiration rate (n = 8) and sweating rate (n = 3) from among those previously associated with production, reproduction or health traits. The SNP that explained the most variation were PGR and ASL for rectal temperature, ACAT2 and HSD17B7 for respiration rate, and ARL6IP1 and SERPINE2 for sweating rate. ARL6IP1 was associated with all three

  3. Heat stress monitoring system. Innovative technology summary report

    SciTech Connect

    1998-11-01

    The US Department of Energy`s (DOE) nuclear facility decontamination and decommissioning (D and D) program involves the need to decontaminate and decommission buildings expeditiously and cost-effectively. Simultaneously, the health and safety of personnel involved in the D and D activities is of primary concern. Often, D and D workers must perform duties in inclement weather, and because they also frequently work in contaminated areas, they must wear personal protective clothing and/or respirators. Monitoring the health status of workers under these conditions is an important component of ensuring their safety. The MiniMitter VitalSense Telemetry System`s heat stress monitoring system (HSMS) is designed to monitor the vital signs of individual workers as they perform work in conditions that might be conducive to heat exhaustion or heat stress. The HSMS provides real-time data on the physiological condition of workers which can be monitored to prevent heat stress or other adverse health situations. This system is particularly useful when workers are wearing personal protective clothing or respirators that make visual observation of their condition more difficult. The MiniMitter VitalSense Telemetry System can monitor up to four channels (e.g., heart rate, body activity, ear canal, and skin temperature) and ten workers from a single supervisory station. The monitors are interfaced with a portable computer that updates and records information on individual workers. This innovative technology, even though it costs more, is an attractive alternative to the traditional (baseline) technology, which measures environmental statistics and predicts the average worker`s reaction to those environmental conditions without taking the physical condition of the individual worker into consideration. Although use of the improved technology might be justified purely on the basis of improved safety, it has the potential to pay for itself by reducing worker time lost caused by heat

  4. Heat stress regimes for the investigation of pollen thermotolerance in crop plants.

    PubMed

    Mesihovic, Anida; Iannacone, Rina; Firon, Nurit; Fragkostefanakis, Sotirios

    2016-06-01

    Pollen thermotolerance. Global warming is predicted to increase the frequency and severity of extreme weather phenomena such as heat waves thereby posing a major threat for crop productivity and food security. The yield in case of most crop species is dependent on the success of reproductive development. Pollen development has been shown to be highly sensitive to elevated temperatures while the development of the female gametophyte as well as sporophytic tissues might also be disturbed under mild or severe heat stress conditions. Therefore, assessing pollen thermotolerance is currently of high interest for geneticists, plant biologists and breeders. A key aspect in pollen thermotolerance studies is the selection of the appropriate heat stress regime, the developmental stage that the stress is applied to, as well as the method of application. Literature search reveals a rather high variability in heat stress treatments mainly due to the lack of standardized protocols for different plant species. In this review, we summarize and discuss experimental approaches that have been used in various crops, with special focus on tomato, rice and wheat, as the best studied crops regarding pollen thermotolerance. The overview of stress treatments and the major outcomes of each study aim to provide guidelines for similar research in other crops.

  5. Can intradermal administration of angiotensin II influence human heat loss responses during whole body heat stress?

    PubMed

    Fujii, Naoto; Meade, Robert D; Paull, Gabrielle; McGinn, Ryan; Foudil-bey, Imane; Akbari, Pegah; Kenny, Glen P

    2015-05-01

    It is unclear if angiotensin II, which can increase the production of reactive oxygen species (oxidative stress), modulates heat loss responses of cutaneous blood flow and sweating. We tested the hypothesis that angiotensin II-induced increases in oxidative stress impair cutaneous perfusion and sweating during rest and exercise in the heat. Eleven young (24 ± 4 yr) healthy adults performed two 30-min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C). The first and second exercises were followed by a 20- and 40-min recovery. Four microdialysis fibers were placed in the forearm skin for continuous administration of either: 1) lactated Ringer (control), 2) 10 μM angiotensin II, 3) 10 mM ascorbate (an antioxidant), or 4) a combination of 10 μM angiotensin II + 10 mM ascorbate. Cutaneous vascular conductance (CVC; laser-Doppler perfusion units/mean arterial pressure) and sweating (ventilated capsule) were evaluated at each skin site. Compared with control, angiotensin II reduced both CVC and sweating at baseline resting and during each recovery in the heat (all P < 0.05). However, during both exercise bouts, there were no differences in CVC or sweating between the treatment sites (all P > 0.05). When ascorbate was coinfused with angiotensin II, the effect of angiotensin II on sweating was abolished (all P > 0.05); however, its effect on CVC at baseline resting and during each recovery remained intact (all P < 0.05). We show angiotensin II impairs cutaneous perfusion independent of oxidative stress, while it impairs sweating through increasing oxidative stress during exposure to an ambient heat stress before and following exercise. Copyright © 2015 the American Physiological Society.

  6. Can intradermal administration of angiotensin II influence human heat loss responses during whole body heat stress?

    PubMed Central

    Fujii, Naoto; Meade, Robert D.; Paull, Gabrielle; McGinn, Ryan; Foudil-bey, Imane; Akbari, Pegah

    2015-01-01

    It is unclear if angiotensin II, which can increase the production of reactive oxygen species (oxidative stress), modulates heat loss responses of cutaneous blood flow and sweating. We tested the hypothesis that angiotensin II-induced increases in oxidative stress impair cutaneous perfusion and sweating during rest and exercise in the heat. Eleven young (24 ± 4 yr) healthy adults performed two 30-min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C). The first and second exercises were followed by a 20- and 40-min recovery. Four microdialysis fibers were placed in the forearm skin for continuous administration of either: 1) lactated Ringer (control), 2) 10 μM angiotensin II, 3) 10 mM ascorbate (an antioxidant), or 4) a combination of 10 μM angiotensin II + 10 mM ascorbate. Cutaneous vascular conductance (CVC; laser-Doppler perfusion units/mean arterial pressure) and sweating (ventilated capsule) were evaluated at each skin site. Compared with control, angiotensin II reduced both CVC and sweating at baseline resting and during each recovery in the heat (all P < 0.05). However, during both exercise bouts, there were no differences in CVC or sweating between the treatment sites (all P > 0.05). When ascorbate was coinfused with angiotensin II, the effect of angiotensin II on sweating was abolished (all P > 0.05); however, its effect on CVC at baseline resting and during each recovery remained intact (all P < 0.05). We show angiotensin II impairs cutaneous perfusion independent of oxidative stress, while it impairs sweating through increasing oxidative stress during exposure to an ambient heat stress before and following exercise. PMID:25767030

  7. Multi-model ensemble projections of future extreme heat stress on rice across southern China

    NASA Astrophysics Data System (ADS)

    He, Liang; Cleverly, James; Wang, Bin; Jin, Ning; Mi, Chunrong; Liu, De Li; Yu, Qiang

    2017-08-01

    Extreme heat events have become more frequent and intense with climate warming, and these heatwaves are a threat to rice production in southern China. Projected changes in heat stress in rice provide an assessment of the potential impact on crop production and can direct measures for adaptation to climate change. In this study, we calculated heat stress indices using statistical scaling techniques, which can efficiently downscale output from general circulation models (GCMs). Data across the rice belt in southern China were obtained from 28 GCMs in the Coupled Model Intercomparison Project phase 5 (CMIP5) with two emissions scenarios (RCP4.5 for current emissions and RCP8.5 for increasing emissions). Multi-model ensemble projections over the historical period (1960-2010) reproduced the trend of observations in heat stress indices (root-mean-square error RMSE = 6.5 days) better than multi-model arithmetic mean (RMSE 8.9 days) and any individual GCM (RMSE 11.4 days). The frequency of heat stress events was projected to increase by 2061-2100 in both scenarios (up to 185 and 319% for RCP4.5 and RCP8.5, respectively), especially in the middle and lower reaches of the Yangtze River. This increasing risk of exposure to heat stress above 30 °C during flowering and grain filling is predicted to impact rice production. The results of our study suggest the importance of specific adaption or mitigation strategies, such as selection of heat-tolerant cultivars and adjustment of planting date in a warmer future world.

  8. Validating the Heat Stress Indices for Using In Heavy Work Activities in Hot and Dry Climates.

    PubMed

    Hajizadeh, Roohalah; Golbabaei, Farideh; Farhang Dehghan, Somayeh; Beheshti, Mohammad Hossein; Jafari, Sayed Mohammad; Taheri, Fereshteh

    2016-01-01

    Necessity of evaluating heat stress in the workplace, require validation of indices and selection optimal index. The present study aimed to assess the precision and validity of some heat stress indices and select the optimum index for using in heavy work activities in hot and dry climates. It carried out on 184 workers from 40 brick kilns workshops in the city of Qom, central Iran (as representative hot and dry climates). After reviewing the working process and evaluation the activity of workers and the type of work, environmental and physiological parameters according to standards recommended by International Organization for Standardization (ISO) including ISO 7243 and ISO 9886 were measured and indices were calculated. Workers engaged in indoor kiln experienced the highest values of natural wet temperature, dry temperature, globe temperature and relative humidity among studied sections (P<0.05). Indoor workplaces had the higher levels of all environmental parameters than outdoors (P=0.0001), except for air velocity. The wet-bulb globe temperature (WBGT) and heat stress index (HSI) indices had the highest correlation with other physiological parameters among the other heat stress indices. Relationship between WBGT index and carotid artery temperature (r=0.49), skin temperature (r=0.319), and oral temperature (r=0.203) was statistically significant (P=0.006). Since WBGT index, as the most applicable index for evaluating heat stress in workplaces is approved by ISO, and due to the positive features of WBGT such as ease of measurement and calculation, and with respect to some limitation in application of HSI; WBGT can be introduced as the most valid empirical index of heat stress in the brick workshops.

  9. Change in spontaneous baroreflex control of pulse interval during heat stress in humans.

    PubMed

    Lee, Kichang; Jackson, Dwayne N; Cordero, Douglas L; Nishiyasu, Takeshi; Peters, Jochen K; Mack, Gary W

    2003-11-01

    Spontaneous baroreflex control of pulse interval (PI) was assessed in healthy volunteers under thermoneutral and heat stress conditions. Subjects rested in the supine position with their lower legs in a water bath at 34 degrees C. Heat stress was imposed by increasing the bath temperature to 44 degrees C. Arterial blood pressure (Finapres), PI (ECG), esophageal and skin temperature, and stroke volume were continuously collected during each 5-min experimental stage. Spontaneous baroreflex function was evaluated by multiple techniques, including 1) the mean slope of the linear relationship between PI and systolic blood pressure (SBP) with three or more simultaneous increasing or decreasing sequences, 2) the linear relationship between changes in PI and SBP (deltaPI/DeltaSBP) derived by using the first differential equation, 3) the linear relationship between changes in PI and SBP with simultaneously increasing or decreasing sequences (+deltaPI/+deltaSBP or -deltaPI/-deltaSBP), and 4) transfer function analysis. Heat stress increased esophageal temperature by 0.6 +/- 0.1 degrees C, decreased PI from 1,007 +/- 43 to 776 +/- 37 ms and stroke volume by 16 +/- 5 ml/beat. Heat stress reduced baroreflex sensitivity but increased the incidence of baroreflex slopes from 5.2 +/- 0.8 to 8.6 +/- 0.9 sequences per 100 heartbeats. Baroreflex sensitivity was significantly correlated with PI or vagal power (r2 = 0.45, r2 = 0.71, respectively; P < 0.05). However, the attenuation in baroreflex sensitivity during heat stress appeared related to a shift in autonomic balance (shift in resting PI) rather than heat stress per se.

  10. Gastric emptying during exercise: effects of heat stress and hypohydration.

    PubMed

    Neufer, P D; Young, A J; Sawka, M N

    1989-01-01

    To determine the effects of acute heat stress, heat acclimation and hypohydration on the gastric emptying rate of water (W) during treadmill exercise, ten physically fit men ingested 400 ml of W before each of three 15 min bouts of exercise (treadmill, approximately 50% VO2max) on five separate occasions. Stomach contents were aspirated after each exercise bout. Before heat acclimation (ACC), experiments were performed in a neutral (18 degrees C), hot (49 degrees C) and warm (35 degrees C) environment. Subjects were euhydrated for all experiments before ACC. After ACC, the subjects completed two more experiments in the warm (35 degrees C) environment; one while euhydrated and a final one while hypohydrated (-5% of body weight). The volume of ingested water emptied into the intestines at the completion of each exercise bout was inversely correlated (P less than 0.01) with the rectal temperature (r = -0.76). The following new observations were made: 1) exercise in a hot (49 degrees C) environment impairs gastric emptying rate as compared with a neutral (18 degrees C) environment, 2) exercise in a warm (35 degrees C) environment does not significantly reduce gastric emptying before or after heat acclimation, but 3) exercise in a warm environment (35 degrees C) when hypohydrated reduces gastric emptying rate and stomach secretions. Reductions in gastric emptying appear to be related to the severity of the thermal strain induced by an exercise/heat stress.

  11. Stress Assessment by Prefrontal Relative Gamma

    PubMed Central

    Minguillon, Jesus; Lopez-Gordo, Miguel A.; Pelayo, Francisco

    2016-01-01

    Stress assessment has been under study in the last years. Both biochemical and physiological markers have been used to measure stress level. In neuroscience, several studies have related modification of stress level to brain activity changes in limbic system and frontal regions, by using non-invasive techniques such as functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). In particular, previous studies suggested that the exhibition or inhibition of certain brain rhythms in frontal cortical areas indicates stress. However, there is no established marker to measure stress level by EEG. In this work, we aimed to prove the usefulness of the prefrontal relative gamma power (RG) for stress assessment. We conducted a study based on stress and relaxation periods. Six healthy subjects performed the Montreal Imaging Stress Task (MIST) followed by a stay within a relaxation room while EEG and electrocardiographic signals were recorded. Our results showed that the prefrontal RG correlated with the expected stress level and with the heart rate (HR; 0.8). In addition, the difference in prefrontal RG between time periods of different stress level was statistically significant (p < 0.01). Moreover, the RG was more discriminative between stress levels than alpha asymmetry, theta, alpha, beta, and gamma power in prefrontal cortex. We propose the prefrontal RG as a marker for stress assessment. Compared with other established markers such as the HR or the cortisol, it has higher temporal resolution. Additionally, it needs few electrodes located at non-hairy head positions, thus facilitating the use of non-invasive dry wearable real-time devices for ubiquitous assessment of stress. PMID:27713698

  12. Deficiency of heat shock transcription factor 1 suppresses heat stress-associated increase in slow soleus muscle mass of mice.

    PubMed

    Ohno, Y; Egawa, T; Yokoyama, S; Nakai, A; Sugiura, T; Ohira, Y; Yoshioka, T; Goto, K

    2015-12-01

    Effects of heat shock transcription factor 1 (HSF1) deficiency on heat stress-associated increase in slow soleus muscle mass of mice were investigated. Both HSF1-null and wild-type mice were randomly assigned to control and heat-stressed groups. Mice in heat-stressed group were exposed to heat stress (41 °C for 60 min) in an incubator without anaesthesia. Significant increase in wet and dry weights, and protein content of soleus muscle in wild-type mice was observed seven days after the application of the heat stress. However, heat stress had no impact on soleus muscle mass in HSF1-null mice. Neither type of mice exhibited much effect of heat stress on HSF mRNA expression (HSF1, HSF2 and HSF4). On the other hand, heat stress upregulated heat shock proteins (HSPs) at the mRNA (HSP72) and protein (HSP72 and HSP110) levels in wild-type mice, but not in HSF1-null mice. The population of Pax7-positive nuclei relative to total myonuclei of soleus muscle in wild-type mice was significantly increased by heat stress, but not in HSF1-null mice. Furthermore, the absence of HSF1 gene suppressed heat stress-associated phosphorylation of Akt and p70 S6 kinase (p-p70S6K) in soleus muscle. Heat stress-associated increase in skeletal muscle mass may be induced by HSF1 and/or HSF1-mediated stress response that activates muscle satellite cells and Akt/p70S6K signalling pathway. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  13. Association of heat shock protein 70 expression with rat myocardial cell damage during heat stress in vitro and in vivo.

    PubMed

    Chen, H B; Zhang, X C; Cheng, Y F; Abdelnasir, A; Tang, S; Kemper, N; Hartung, J; Bao, E D

    2015-03-20

    To investigate the mechanism of sudden death as a result of stress-induced damage to heart tissue and myocardial cells and to investigate the cardioprotective role of Hsp70 during heat stress, the distribution and expression of Hsp70 was evaluated in the heart cells of heat-stressed rats in vivo and heat-stressed H9c2 cells in vitro. After exposure to heat stress at 42°C for different durations, we observed a significant induction of CK, CK-MB, and LDH as well as pathologic lesions characterized by acute degeneration, suggesting that cell damage occurs from the onset of heat stress. Immunocytochemistry showed that Hsp70 was distributed mainly in the cytoplasm of myocardial cells in vivo and in vitro. Hsp70-positive signals in the cytoplasm were more prominent in intact areas than in degenerated areas after 60 min of heat stress. Hsp70 protein levels in myocardial cells in vitro decreased from the beginning to the end of heat stress. Hsp70 protein levels in rat heart tissues in vivo decreased gradually with prolonged heat stress, with a slight increase at the beginning of heat stress. These results indicate that Hsp70 plays a role in the response of cardiac cells to heat stress and that decreased Hsp70 levels are associated with damage to rat myocardial cells in vitro and in vivo. Significant differences were found in hsp70 mRNA, which began to increase after 20 min of heat stress in vitro and after 40 min in vivo. This indicates that hysteresis is involved in mRNA expression after heat stress in vivo.

  14. Stress response in the ascidian Ciona intestinalis: transcriptional profiling of genes for the heat shock protein 70 chaperone system under heat stress and endoplasmic reticulum stress.

    PubMed

    Fujikawa, Tetsuya; Munakata, Takeo; Kondo, Shin-ichi; Satoh, Nori; Wada, Shuichi

    2010-03-01

    The genome of Ciona intestinalis contains eight genes for HSP70 superfamily proteins, 36 genes for J-proteins, a gene for a J-like protein, and three genes for BAG family proteins. To understand the stress responses of genes in the HSP70 chaperone system comprehensively, the transcriptional profiles of these 48 genes under heat stress and endoplasmic reticulum (ER) stress were studied using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Heat stress treatment increased the messenger RNA (mRNA) levels of six HSP70 superfamily genes, eight J-protein family genes, and two BAG family genes. In the cytoplasmic group of the DnaK subfamily of the HSP70 family, Ci-HSPA1/6/7-like was the only heat-inducible gene and Ci-HSPA2/8 was the only constitutively active gene which showed striking simplicity in comparison with other animals that have been examined genome-wide so far. Analyses of the time course and temperature dependency of the heat stress responses showed that the induction of Ci-HSPA1/6/7-like expression rises to a peak after heat stress treatment at 28 degrees C (10 degrees C upshift from control temperature) for 1 h. ER stress treatment with Brefeldin A, a drug that is known to act as ER stress inducer, increased the mRNA levels of four HSP70 superfamily genes and four J-protein family genes. Most stress-inducible genes are conserved between Ciona and vertebrates, as expected from a close evolutionary relationship between them. The present study characterized the stress responses of HSP70 chaperone system genes in Ciona for the first time and provides essential data for comprehensive understanding of the functions of the HSP70 chaperone system.

  15. Population-specificity of heat stress gene induction in northern and southern eelgrass Zostera marina populations under simulated global warming.

    PubMed

    Bergmann, Nina; Winters, Gidon; Rauch, Gisep; Eizaguirre, Christophe; Gu, Jenny; Nelle, Peter; Fricke, Birgit; Reusch, Thorsten B H

    2010-07-01

    Summer heat waves have already resulted in mortality of coastal communities, including ecologically important seagrass meadows. Gene expression studies from controlled experiments can provide important insight as to how species/genotypes react to extreme events that will increase under global warming. In a common stress garden, we exposed three populations of eelgrass, Zostera marina, to extreme sea surface temperatures, simulating the 2003-European heat wave. Populations came from locations widely differing in their thermal regime, two northern European locations [Ebeltoft (Kattegat), Doverodde (Limfjord, Baltic Sea)], and one southern population from Gabicce Mare (Adriatic Sea), allowing to test for population specificity in the response to a realistic heat stress event. Eelgrass survival and growth as well as the expression of 12 stress associated candidate genes were assessed during and after the heat wave. Contrary to expectations, all populations suffered equally from 3 weeks of heat stress in terms of shoot loss. In contrast, populations markedly differed in multivariate measures of gene expression. While the gene expression profiles converged to pre-stress values directly after the heat wave, stress correlated genes were upregulated again 4 weeks later, in line with the observed delay in shoot loss. Target genes had to be selected based on functional knowledge in terrestrial plants, nevertheless, 10/12 genes were induced relative to the control treatment at least once during the heat wave in the fully marine plant Z. marina. This study underlines the importance of realistic stress and recovery scenarios in studying the impact of predicted climate change.

  16. Wind stress and heat fluxes over a Brazilian Coastal Upwelling

    NASA Astrophysics Data System (ADS)

    Dourado, Marcelo; Candella, Rogério

    2017-04-01

    Coastal upwelling zones have been intensively studied in the last decades especially due to their importance to the biological cycle. The coastal upwelling system of the Cabo Frio region (east coast of the Rio de Janeiro state, Brazil) keeps the surface water cold during most part of the year, what induces a stable atmospheric boundary layer associated to northeast winds. The main goal of this study is to investigate the wind stress and heat fluxes exchanges between the ocean and the atmosphere in that area. For this purpose, a set of hourly data meteorological and oceanographic data collected by a Wavescan metocean buoy anchored at 23o59S; 42oW, were used, as well as solar radiation and relative humidity from a terrestrial meteorological station from the Instituto Nacional de Meteorologia (InMet). COARE 3.0 algorithm was used to calculate the latent and sensible heat fluxes. In this discussion, positive values represent fluxes towards the ocean. The average net heat flux over our study period is 88 W m-2. The reduction of the net heat flux is due to the increase of the ocean latent heat loss, although a reduction in incoming shortwave radiation and an increase in ocean long wave cooling also contributes. The latent heat is 20 times larger than the sensible heat flux, but the mean value of the latent heat flux, 62 W m-2, is half the typical value found in open ocean. The temporal variability of both sensible and latent heat fluxes reflects their dependence on wind speed and air-sea temperature differences. When upwelling events, here periods when diurnal SST is lower than 18oC, are compared with undisturbed (without upwelling) events, it can be noted the sensible heat fluxes are positives and 10 times greater in magnitude. This is related to an increment, during these upwelling events, of the air-sea temperature difference and an increasing of the wind speed. The cold waters of the upwelling increase the air-sea temperature gradient and, also, the horizontal land

  17. Pulmonary Artery and Intestinal Temperatures during Heat Stress and Cooling

    PubMed Central

    Pearson, James; Ganio, Matthew S; Seifert, Thomas; Overgaard, Morten; Secher, Niels H; Crandall, Craig G

    2011-01-01

    Introduction/Purpose In humans, whole body heating and cooling are used to address physiological questions where core temperature is central to the investigated hypotheses. Core temperature can be measured in various locations throughout the human body. The measurement of intestinal temperature is increasingly used in laboratory settings as well as in athletics. However, it is unknown whether intestinal temperature accurately tracks pulmonary artery blood temperature, the gold standard, during thermal stimuli in resting humans, which is the investigated hypothesis. Methods This study compared pulmonary artery blood temperature (via thermistor in a pulmonary artery catheter) with intestinal temperature (telemetry pill) during whole-body heat stress (n=8), followed by whole-body cooling in healthy humans (mean ± SD age 24 ± 3 yrs; height 183 ± 8 cm; mass 78.1 ± 8.2 kg). Heat stress and subsequent cooling were performed by perfusing warm followed by cold water through a tube-lined suit worn by each subject. Results Prior to heat stress blood temperature (36.69 ± 0.25°C) was less than intestinal temperature (36.96 ± 0.21°C, P = 0.004). The increase in blood temperature after 20 min of heat stress was greater than intestinal temperature (0.70 ± 0.24 vs. 0.47 ± 0.18; P = 0.001). However, the increase in temperatures at the end of heat stress were similar between sites (blood Δ = 1.32 ± 0.20°C vs. intestinal Δ = 1.21 ± 0.36°C; P = 0.30). Subsequent cooling decreased blood temperature (Δ = −1.03 ± 0.34°C) to a greater extent than intestinal temperature (Δ = −0.41 ± 0.30°C, P = 0.04). Conclusion In response to the applied thermal provocations, early temperature changes in the intestine are less than the temperature changes in pulmonary artery blood. PMID:22015711

  18. Heat stress during the Black Saturday event in Melbourne, Australia

    NASA Astrophysics Data System (ADS)

    Jacobs, Stephanie J.; Vihma, Timo; Pezza, Alexandre B.

    2015-06-01

    The Black Saturday bushfire event of February 7, 2009, devastated the state of Victoria, Australia, resulting in 173 deaths. On this day, the maximum temperature in Melbourne (state capital of Victoria, population 4 million people) exceeded 46 °C, there were wind gusts of over 80 km h-1 and the relative humidity dropped below 5 %. We investigated the severe meteorological conditions of Black Saturday and the risk of heat stress and dehydration for the residents of Melbourne. This was through the analysis of weather station data, air pollution data, the apparent temperature (AT) and the COMfort FormulA human energy budget model. A very strong pressure gradient caused hot and dry air to be advected to Melbourne from the desert interior of Australia creating the extreme weather conditions. The AT showed that on Black Saturday, heat stress conditions were present, though underrepresented due to assumptions in the AT formula. Further investigation into the human energy budget revealed that the conditions required a sweating rate of 1.4 kg h-1 to prevent heat accumulation into the body. If sweating stopped, hyperthermia could occur in 15 min. Sensitivity tests indicated that the dry air and strong winds on Black Saturday helped to release latent heat, but the required sweating rate was virtually unattainable for an average person and would result in intense dehydration. Air particulates were at dangerous concentrations in Melbourne on Black Saturday, further intensifying the stresses to the human body. In the future, we recommend that the AT is not used as a thermal comfort measure as it underestimates the physical stress people experience.

  19. Heat stress of helicopter aircrew wearing immersion suit.

    PubMed

    Ducharme, Michel B

    2006-07-01

    The objectives of the present study were to define the lowest ambient air and cabin temperatures at which aircrews wearing immersion protection are starting to experience thermal discomfort and heat stress during flight operations, and to characterize during a flight simulation in laboratory, the severity of the heat stress during exposure to a typical northern summer ambient condition (25 degrees C, 40% RH). Twenty male helicopter aircrews wearing immersion suits (insulation of 2.2 Clo in air) performed 26 flights within an 8-month period at ambient temperatures ranging between -15 and 25 degrees C, and cabin temperatures ranging between 3 and 28 degrees C. It was observed based on thermal comfort ratings that the aircrews were starting to experience thermal discomfort and heat stress at ambient and cabin air conditions above 18 degrees C and at a WBGT index of 16 degrees C. In a subsequent study, seven aircrews dressed with the same clothing were exposed for 140 min to 25 degrees C and 40% RH in a climatic chamber. During the exposure, the aircrews simulated pilot flight maneuvers for 80 min followed with backender/flight engineer activities for 60 min. By the end of the 140 min exposure, the skin temperature, rectal temperature and heart rate had increased significantly to 35.7 +/- 0.2 degrees C, 38.4 +/- 0.2 degrees C and between 110 and 160 beats/min depending on the level of physical activity. The body sweat rate averaged 0.58 kg/h and the relative humidity inside the clothing was at saturation by the end of the exposure. It was concluded that aircrews wearing immersion suits during the summer months in northern climates might experience thermal discomfort and heat stress at ambient or cabin air temperature as low as 18 degrees C.

  20. Heat stress during the Black Saturday event in Melbourne, Australia.

    PubMed

    Jacobs, Stephanie J; Vihma, Timo; Pezza, Alexandre B

    2015-06-01

    The Black Saturday bushfire event of February 7, 2009, devastated the state of Victoria, Australia, resulting in 173 deaths. On this day, the maximum temperature in Melbourne (state capital of Victoria, population 4 million people) exceeded 46 °C, there were wind gusts of over 80 km h(-1) and the relative humidity dropped below 5 %. We investigated the severe meteorological conditions of Black Saturday and the risk of heat stress and dehydration for the residents of Melbourne. This was through the analysis of weather station data, air pollution data, the apparent temperature (AT) and the COMfort FormulA human energy budget model. A very strong pressure gradient caused hot and dry air to be advected to Melbourne from the desert interior of Australia creating the extreme weather conditions. The AT showed that on Black Saturday, heat stress conditions were present, though underrepresented due to assumptions in the AT formula. Further investigation into the human energy budget revealed that the conditions required a sweating rate of 1.4 kg h(-1) to prevent heat accumulation into the body. If sweating stopped, hyperthermia could occur in 15 min. Sensitivity tests indicated that the dry air and strong winds on Black Saturday helped to release latent heat, but the required sweating rate was virtually unattainable for an average person and would result in intense dehydration. Air particulates were at dangerous concentrations in Melbourne on Black Saturday, further intensifying the stresses to the human body. In the future, we recommend that the AT is not used as a thermal comfort measure as it underestimates the physical stress people experience.

  1. Protective effects of ectoine on heat-stressed Daphnia magna.

    PubMed

    Adam, Bownik; Zofia, Stępniewska; Tadeusz, Skowroński

    2014-12-01

    Ectoine (ECT) is an amino acid produced and accumulated by halophilic bacteria in stressful conditions in order to prevent the loss of water from the cell. There is a lack of knowledge on the effects of ECT in heat-stressed aquatic animals. The purpose of our study was to determine the influence of ECT on Daphnia magna subjected to heat stress with two temperature gradients: 1 and 0.1 °C/min in the range of 23-42 °C. Time to immobilisation, survival during recovery, swimming performance, heart rate, thoracic limb movement and the levels of heat shock protein 70 kDa 1A (HSP70 1A), catalase (CAT) and nitric oxide species (NOx) were determined in ECT-exposed and unexposed daphnids; we showed protective effects of ECT on Daphnia magna subjected to heat stress. Time to immobilisation of daphnids exposed to ECT was longer when compared to the unexposed animals. Also, survival rate during the recovery of daphnids previously treated with ECT was higher. ECT significantly attenuated a rapid increase of mean swimming velocity which was elevated in the unexposed daphnids. Moreover, we observed elevation of thoracic limb movement and modulation of heart rate in ECT-exposed animals. HSP70 1A and CAT levels were reduced in the presence of ECT. On the other hand, NOx level was slightly elevated in both ECT-treated and unexposed daphnids, however slightly higher NOx level was found in ECT-treated animals. We conclude that the exposure to ectoine has thermoprotective effects on Daphnia magna, however their mechanisms are not associated with the induction of HSP70 1A.

  2. Single nucleotide polymorphisms associated with thermoregulation in lactating dairy cows exposed to heat stress

    USDA-ARS?s Scientific Manuscript database

    Dairy cows with increased rectal temperature during heat stress experience lower milk yield and fertility. Given that rectal temperature during heat stress is heritable in dairy cattle, genetic selection for regulation of body temperature should reduce effects of heat stress on production. One goal...

  3. Mitochondrial Respiratory Electron Carriers Are Involved in Oxidative Stress during Heat Stress in Saccharomyces cerevisiae

    PubMed Central

    Davidson, John F.; Schiestl, Robert H.

    2001-01-01

    In the present study we sought to determine the source of heat-induced oxidative stress. We investigated the involvement of mitochondrial respiratory electron transport in post-diauxic-phase cells under conditions of lethal heat shock. Petite cells were thermosensitive, had increased nuclear mutation frequencies, and experienced elevated levels of oxidation of an intracellular probe following exposure to a temperature of 50°C. Cells with a deletion in COQ7 leading to a deficiency in coenzyme Q had a much more severe thermosensitivity phenotype for these oxidative endpoints following heat stress compared to that of petite cells. In contrast, deletion of the external NADH dehydrogenases NDE1 and NDE2, which feed electrons from NADH into the electron transport chain, abrogated the levels of heat-induced intracellular fluorescence and nuclear mutation frequency. Mitochondria isolated from COQ7-deficient cells secreted more than 30 times as much H2O2 at 42 as at 30°C, while mitochondria isolated from cells simultaneously deficient in NDE1 and NDE2 secreted no H2O2. We conclude that heat stress causes nuclear mutations via oxidative stress originating from the respiratory electron transport chains of mitochondria. PMID:11713283

  4. Practices for Alleviating Heat Stress of Dairy Cows in Humid Continental Climates: A Literature Review.

    PubMed

    Fournel, Sébastien; Ouellet, Véronique; Charbonneau, Édith

    2017-05-02

    Heat stress negatively affects the health and performance of dairy cows, resulting in considerable economic losses for the industry. In future years, climate change will exacerbate these losses by making the climate warmer. Physical modification of the environment is considered to be the primary means of reducing adverse effects of hot weather conditions. At present, to reduce stressful heat exposure and to cool cows, dairy farms rely on shade screens and various forms of forced convection and evaporative cooling that may include fans and misters, feed-line sprinklers, and tunnel- or cross-ventilated buildings. However, these systems have been mainly tested in subtropical areas and thus their efficiency in humid continental climates, such as in the province of Québec, Canada, is unclear. Therefore, this study reviewed the available cooling applications and assessed their potential for northern regions. Thermal stress indices such as the temperature-humidity index (THI) were used to evaluate the different cooling strategies.

  5. Metabolic crosstalk between membrane and storage lipids facilitates heat stress management in Schizosaccharomyces pombe

    PubMed Central

    Péter, Mária; Glatz, Attila; Gudmann, Péter; Gombos, Imre; Török, Zsolt; Horváth, Ibolya; Vígh, László

    2017-01-01

    Cell membranes actively participate in stress sensing and signalling. Here we present the first in-depth lipidomic analysis to characterize alterations in the fission yeast Schizosaccharomyces pombe in response to mild heat stress (HS). The lipidome was assessed by a simple one-step methanolic extraction. Genetic manipulations that altered triglyceride (TG) content in the absence or presence of HS gave rise to distinct lipidomic fingerprints for S. pombe. Cells unable to produce TG demonstrated long-lasting growth arrest and enhanced signalling lipid generation. Our results reveal that metabolic crosstalk between membrane and storage lipids facilitates homeostatic maintenance of the membrane physical/chemical state that resists negative effects on cell growth and viability in response to HS. We propose a novel stress adaptation mechanism in which heat-induced TG synthesis contributes to membrane rigidization by accommodating unsaturated fatty acids of structural lipids, enabling their replacement by newly synthesized saturated fatty acids. PMID:28282432

  6. l-Arginine Enhances Resistance against Oxidative Stress and Heat Stress in Caenorhabditis elegans

    PubMed Central

    Ma, Heran; Ma, Yudan; Zhang, Zhixian; Zhao, Ziyuan; Lin, Ran; Zhu, Jinming; Guo, Yi; Xu, Li

    2016-01-01

    The antioxidant properties of l-arginine (l-Arg) in vivo, and its effect on enhancing resistance to oxidative stress and heat stress in Caenorhabditis elegans were investigated. C. elegans, a worm model popularly used in molecular and developmental biology, was used in the present study. Here, we report that l-Arg, at a concentration of 1 mM, prolonged C. elegans life by 26.98% and 37.02% under oxidative and heat stress, respectively. Further experiments indicated that the longevity-extending effects of l-Arg may be exerted by its free radical scavenging capacity and the upregulation of aging-associated gene expression in worms. This work is important in the context of numerous recent studies that concluded that environment stresses are associated with an increased population death rate. PMID:27690079

  7. Effect of heat stress on reproductive performances of dairy cattle and buffaloes: A review

    PubMed Central

    Dash, Soumya; Chakravarty, A. K.; Singh, Avtar; Upadhyay, Arpan; Singh, Manvendra; Yousuf, Saleem

    2016-01-01

    Heat stress has adverse effects on the reproductive performances of dairy cattle and buffaloes. The dairy sector is a more vulnerable to global warming and climate change. The temperature humidity index (THI) is the widely used index to measure the magnitude of heat stress in animals. The objective of this paper was to assess the decline in performances of reproductive traits such as service period, conception rate and pregnancy rate of dairy cattle and buffaloes with respect to increase in THI. The review stated that service period in cattle is affected by season of calving for which cows calved in summer had the longest service period. The conception rate and pregnancy rate in dairy cattle were found decreased above THI 72 while a significant decline in reproductive performances of buffaloes was observed above threshold THI 75. The non-heat stress zone (HSZ) (October to March) is favorable for optimum reproductive performance, while fertility is depressed in HSZ (April to September) and critical HSZ (CHSZ) (May and June). Heat stress in animals has been associated with reduced fertility through its deleterious impact on oocyte maturation and early embryo development. The management strategies viz., nutrition modification, environment modification and timed artificial insemination protocol are to be strictly operated to ameliorate the adverse effects of heat stress in cattle and buffaloes during CHSZ to improve their fertility. The identification of genes associated with heat tolerance, its incorporation into breeding program and the inclusion of THI covariate effects in selection index should be targeted for genetic evaluation of dairy animals in the hot climate. PMID:27057105

  8. Effect of heat stress on reproductive performances of dairy cattle and buffaloes: A review.

    PubMed

    Dash, Soumya; Chakravarty, A K; Singh, Avtar; Upadhyay, Arpan; Singh, Manvendra; Yousuf, Saleem

    2016-03-01

    Heat stress has adverse effects on the reproductive performances of dairy cattle and buffaloes. The dairy sector is a more vulnerable to global warming and climate change. The temperature humidity index (THI) is the widely used index to measure the magnitude of heat stress in animals. The objective of this paper was to assess the decline in performances of reproductive traits such as service period, conception rate and pregnancy rate of dairy cattle and buffaloes with respect to increase in THI. The review stated that service period in cattle is affected by season of calving for which cows calved in summer had the longest service period. The conception rate and pregnancy rate in dairy cattle were found decreased above THI 72 while a significant decline in reproductive performances of buffaloes was observed above threshold THI 75. The non-heat stress zone (HSZ) (October to March) is favorable for optimum reproductive performance, while fertility is depressed in HSZ (April to September) and critical HSZ (CHSZ) (May and June). Heat stress in animals has been associated with reduced fertility through its deleterious impact on oocyte maturation and early embryo development. The management strategies viz., nutrition modification, environment modification and timed artificial insemination protocol are to be strictly operated to ameliorate the adverse effects of heat stress in cattle and buffaloes during CHSZ to improve their fertility. The identification of genes associated with heat tolerance, its incorporation into breeding program and the inclusion of THI covariate effects in selection index should be targeted for genetic evaluation of dairy animals in the hot climate.

  9. The American football uniform: uncompensable heat stress and hyperthermic exhaustion.

    PubMed

    Armstrong, Lawrence E; Johnson, Evan C; Casa, Douglas J; Ganio, Matthew S; McDermott, Brendon P; Yamamoto, Linda M; Lopez, Rebecca M; Emmanuel, Holly

    2010-01-01

    In hot environments, the American football uniform predisposes athletes to exertional heat exhaustion or exercise-induced hyperthermia at the threshold for heat stroke (rectal temperature [T(re)] > 39 degrees C). To evaluate the differential effects of 2 American football uniform configurations on exercise, thermal, cardiovascular, hematologic, and perceptual responses in a hot, humid environment. Randomized controlled trial. Human Performance Laboratory. Ten men with more than 3 years of competitive experience as football linemen (age = 23.8 +/- 4.3 years, height = 183.9 +/- 6.3 cm, mass = 117.41 +/- 12.59 kg, body fat = 30.1% +/- 5.5%). Participants completed 3 controlled exercise protocols consisting of repetitive box lifting (lifting, carrying, and depositing a 20.4-kg box at a rate of 10 lifts per minute for 10 minutes), seated recovery (10 minutes), and up to 60 minutes of treadmill walking. They wore one of the following: a partial uniform (PART) that included the National Football League (NFL) uniform without a helmet and shoulder pads; a full uniform (FULL) that included the full NFL uniform; or control clothing (CON) that included socks, sneakers, and shorts. Exercise, meals, and hydration status were controlled. We assessed sweat rate, T(re), heart rate, blood pressure, treadmill exercise time, perceptual measurements, plasma volume, plasma lactate, plasma glucose, plasma osmolality, body mass, and fat mass. During 19 of 30 experiments, participants halted exercise as a result of volitional exhaustion. Mean sweat rate, T(re), heart rate, and treadmill exercise time during the CON condition were different from those measures during the PART (P range, .04-.001; d range, 0.42-0.92) and FULL (P range, .04-.003; d range, 1.04-1.17) conditions; no differences were detected for perceptual measurements, plasma volume, plasma lactate, plasma glucose, or plasma osmolality. Exhaustion occurred during the FULL and PART conditions at the same T(re) (39.2 degrees C

  10. The American Football Uniform: Uncompensable Heat Stress and Hyperthermic Exhaustion

    PubMed Central

    Armstrong, Lawrence E.; Johnson, Evan C.; Casa, Douglas J.; Ganio, Matthew S.; McDermott, Brendon P.; Yamamoto, Linda M.; Lopez, Rebecca M.; Emmanuel, Holly

    2010-01-01

    Abstract Context: In hot environments, the American football uniform predisposes athletes to exertional heat exhaustion or exercise-induced hyperthermia at the threshold for heat stroke (rectal temperature [Tre] > 39°C). Objective: To evaluate the differential effects of 2 American football uniform configurations on exercise, thermal, cardiovascular, hematologic, and perceptual responses in a hot, humid environment. Design: Randomized controlled trial. Setting: Human Performance Laboratory. Patients or Other Participants: Ten men with more than 3 years of competitive experience as football linemen (age  =  23.8 ± 4.3 years, height  =  183.9 ± 6.3 cm, mass  =  117.41 ± 12.59 kg, body fat  =  30.1% ± 5.5%). Intervention(s): Participants completed 3 controlled exercise protocols consisting of repetitive box lifting (lifting, carrying, and depositing a 20.4-kg box at a rate of 10 lifts per minute for 10 minutes), seated recovery (10 minutes), and up to 60 minutes of treadmill walking. They wore one of the following: a partial uniform (PART) that included the National Football League (NFL) uniform without a helmet and shoulder pads; a full uniform (FULL) that included the full NFL uniform; or control clothing (CON) that included socks, sneakers, and shorts. Exercise, meals, and hydration status were controlled. Main Outcome Measure(s): We assessed sweat rate, Tre, heart rate, blood pressure, treadmill exercise time, perceptual measurements, plasma volume, plasma lactate, plasma glucose, plasma osmolality, body mass, and fat mass. Results: During 19 of 30 experiments, participants halted exercise as a result of volitional exhaustion. Mean sweat rate, Tre, heart rate, and treadmill exercise time during the CON condition were different from those measures during the PART (P range, .04–.001; d range, 0.42–0.92) and FULL (P range, .04–.003; d range, 1.04–1.17) conditions; no differences were detected for perceptual measurements, plasma

  11. Environmental Heat and Salt Stress Induce Transgenerational Phenotypic Changes in Arabidopsis thaliana

    PubMed Central

    Suter, Léonie; Widmer, Alex

    2013-01-01

    Plants that can adapt their phenotype may be more likely to survive changing environmental conditions. Heritable epigenetic variation could provide a way to rapidly adapt to such changes. Here we tested whether environmental stress induces heritable, potentially adaptive phenotypic changes independent of genetic variation over few generations in Arabidopsis thaliana. We grew two accessions (Col-0, Sha-0) of A. thaliana for three generations under salt, heat and control conditions and tested for induced heritable phenotypic changes in the fourth generation (G4) and in reciprocal F1 hybrids generated in generation three. Using these crosses we further tested whether phenotypic changes were maternally or paternally transmitted. In generation five (G5), we assessed whether phenotypic effects persisted over two generations in the absence of stress. We found that exposure to heat stress in previous generations accelerated flowering under G4 control conditions in Sha-0, but heritable effects disappeared in G5 after two generations without stress exposure. Previous exposure to salt stress increased salt tolerance in one of two reciprocal F1 hybrids. Transgenerational effects were maternally and paternally inherited. Lacking genetic variability, maternal and paternal inheritance and reversibility of transgenerational effects together indicate that stress can induce heritable, potentially adaptive phenotypic changes, probably through epigenetic mechanisms. These effects were strongly dependent on plant genotype and may not be a general response to stress in A. thaliana. PMID:23585834

  12. It's the Heat AND the Humidity -- Assessment of Extreme Heat Scenarios to Enable the Assessment of Climate Impacts on Public Health

    NASA Technical Reports Server (NTRS)

    Crosson, William L; Al-Hamdan, Mohammad Z.; Economou, Sigrid, A.; Estes, Maurice G.; Estes, Sue M.; Puckett, Mark; Quattrochi, Dale A

    2013-01-01

    In the United States, extreme heat is the most deadly weather-related hazard. In the face of a warming climate and urbanization, which contributes to local-scale urban heat islands, it is very likely that extreme heat events (EHEs) will become more common and more severe in the U.S. In a NASA-funded project supporting the National Climate Assessment, we are providing historical and future measures of extreme heat to enable assessments of the impacts of heat on public health over the coterminous U.S. We use atmospheric temperature and humidity information from meteorological reanalysis and from Global Climate Models (GCMs) to provide data on past and future heat events. The project s emphasis is on providing assessments of the magnitude, frequency and geographic distribution of extreme heat in the U.S. to facilitate public health studies. In our approach, long-term climate change is captured with GCM output, and the temporal and spatial characteristics of short-term extremes are represented by the reanalysis data. Two future time horizons, 2040 and 2090, are the focus of future assessments; these are compared to the recent past period of 1981-2000. We are characterizing regional-scale temperature and humidity conditions using GCM output for two climate change scenarios (A2 and A1B) defined in the Special Report on Emissions Scenarios (SRES). For each future period, 20 years of multi-model GCM output have been analyzed to develop a heat stress climatology based on statistics of extreme heat indicators. Differences between the two future and past periods have been used to define temperature and humidity changes on a monthly time scale and regional spatial scale. These changes, combined with hourly historical meteorological data at a spatial scale (12 km) much finer than that of GCMs, enable us to create future climate realizations, from which we compute the daily heat stress measures and related spatially-specific climatological fields. These include the mean annual

  13. Thermoregulatory disorders and illness related to heat and cold stress.

    PubMed

    Cheshire, William P

    2016-04-01

    Thermoregulation is a vital function of the autonomic nervous system in response to cold and heat stress. Thermoregulatory physiology sustains health by keeping body core temperature within a degree or two of 37°C, which enables normal cellular function. Heat production and dissipation are dependent on a coordinated set of autonomic responses. The clinical detection of thermoregulatory impairment provides important diagnostic and localizing information in the evaluation of disorders that impair thermoregulatory pathways, including autonomic neuropathies and ganglionopathies. Failure of neural thermoregulatory mechanisms or exposure to extreme or sustained temperatures that overwhelm the body's thermoregulatory capacity can also result in potentially life-threatening departures from normothermia. Hypothermia, defined as a core temperature of <35.0°C, may present with shivering, respiratory depression, cardiac dysrhythmias, impaired mental function, mydriasis, hypotension, and muscle dysfunction, which can progress to cardiac arrest or coma. Management includes warming measures, hydration, and cardiovascular support. Deaths from hypothermia are twice as frequent as deaths from hyperthermia. Hyperthermia, defined as a core temperature of >40.5°C, may present with sweating, flushing, tachycardia, fatigue, lightheadedness, headache, and paresthesia, progressing to weakness, muscle cramps, oliguria, nausea, agitation, hypotension, syncope, confusion, delirium, seizures, and coma. Mental status changes and core temperature distinguish potentially fatal heat stroke from heat exhaustion. Management requires the immediate reduction of core temperature. Ice water immersion has been shown to be superior to alternative cooling measures. Avoidance of thermal risk and early recognition of cold or heat stress are the cornerstones of preventive therapy. Copyright © 2016 The Author. Published by Elsevier B.V. All rights reserved.

  14. Carcass and meat quality traits of rabbits under heat stress.

    PubMed

    Zeferino, C P; Komiyama, C M; Fernandes, S; Sartori, J R; Teixeira, P S S; Moura, A S A M T

    2013-03-01

    Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 × 3 factorial arrangement (two genetic groups and three ambient temperatures: 18°C, 25°C and 30°C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.4°C and 63.9%, 24.4°C and 80.2% and 29.6°C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 30°C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group × ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and

  15. Heat stress standard for hot work environments in Japan.

    PubMed

    Tanaka, Masatoshi

    2007-01-01

    Threshold limit values (TLVs) are intended to protect workers from the severest effects of thermal stress and to establish the exposures to heat in working conditions. Earlier, acute heat strokes often occurred as a result of working in hot environments in Japan. However, acute heat strokes recently sometimes occurred in outdoor work environments such as industrial constructions and agriculture. Seasonal variations in weather are significant and the climatic conditions vary. The criteria are mainly set for working in mines, factories, and so on. WBGT is a useful evaluation index for hot environments; however, it is not commonly used for work practices. WBGT could be calculated and should be commonly used as a standard during summer. Japan mainly has a very hot and humid climate during summer. With regard to the thermal standard for offices, humidity also creates a problem in the indoor thermal conditions. Therefore, it is better to decide the TLVs of the thermal conditions according to seasons and activity levels. Inadequate thermal stress may cause discomfort and adversely affect the performance, safety, and harm to health. Further, thermal factors in the work environment must be measured and evaluated under light workload conditions like desk work for safety and work efficiency.

  16. Plasma hyperosmolality improves tolerance to combined heat stress and central hypovolemia in humans.

    PubMed

    Gagnon, Daniel; Romero, Steven A; Ngo, Hai; Poh, Paula Y S; Crandall, Craig G

    2017-03-01

    Heat stress profoundly impairs tolerance to central hypovolemia in humans via a number of mechanisms including heat-induced hypovolemia. However, heat stress also elevates plasma osmolality; the effects of which on tolerance to central hypovolemia remain unknown. This study examined the effect of plasma hyperosmolality on tolerance to central hypovolemia in heat-stressed humans. With the use of a counterbalanced and crossover design, 12 subjects (1 female) received intravenous infusion of either 0.9% iso-osmotic (ISO) or 3.0% hyperosmotic (HYPER) saline. Subjects were subsequently heated until core temperature increased ~1.4°C, after which all subjects underwent progressive lower-body negative pressure (LBNP) to presyncope. Plasma hyperosmolality improved LBNP tolerance (ISO: 288 ± 193 vs. 382 ± 145 mmHg × min, P = 0.04). However, no differences in mean arterial pressure (P = 0.10), heart rate (P = 0.09), or muscle sympathetic nerve activity (P = 0.60, n = 6) were observed between conditions. When individual data were assessed, LBNP tolerance improved ≥25% in eight subjects but remained unchanged in the remaining four subjects. In subjects who exhibited improved LBNP tolerance, plasma hyperosmolality resulted in elevated mean arterial pressure (ISO: 62 ± 10 vs. 72 ± 9 mmHg, P < 0.01) and a greater increase in heart rate (ISO: +12 ± 24 vs. HYPER: +23 ± 17 beats/min, P = 0.05) before presyncope. No differences in these variables were observed between conditions in subjects that did not improve LBNP tolerance (all P ≥ 0.55). These results suggest that plasma hyperosmolality improves tolerance to central hypovolemia during heat stress in most, but not all, individuals. Copyright © 2017 the American Physiological Society.

  17. Short term post-partum heat stress in dairy cows

    NASA Astrophysics Data System (ADS)

    Fuquay, J. W.; Chapin, L. T.; Brown, W. H.

    1980-06-01

    Since many dairy cows calve during late summer, the objective was to determine if heat stress immediately post-partum would (1) alter metabolism, thus, increasing susceptibility to metabolic disorders, (2) affect lactation and/or (3) affect reproduction. Forty four cows, calving during late summer, were paired with one member of each pair stressed (HS) for the first 10 post-partum days in a hot barn. Controls (CC) were kept in a cooled section of the barn. Plasma drawn weekly for 7 weeks was analyzed in an autoanalyzer for calcium, inor. phosphorus, protein, glucose and cholesterol and by radioimmunoassay for cortisol and progesterone. Ovaries and uteri were palpated weekly. Rectal temperatures were significant higher for HS during the first 10 post-partum days. No significant effects on plasma constituents were observed during the 10-day treatment period. For the 7-week period, glucose and cholesterol were lower in HS, as were cyclic peaks of progesterone and cortisol. Both calcium and inorganic phosphorus remained clinically low for the 7 weeks, but no treatment effects were seen. Uteri of HS involuted more rapidly than the CC. Treatment did not affect reproductive efficiency. Lactation milk yields did not differ, but milk fat percent was lower in HS. Heat stress immediately post-partum altered lipid metabolism, but the animal's compensatory mechanisms prevented reduction in milk production or reproductive efficiency.

  18. Expression of heat stress proteins by human periodontal ligament cells.

    PubMed

    Sauk, J J; Norris, K; Foster, R; Moehring, J; Somerman, M J

    1988-11-01

    The purpose of the present report was to document the stress response produced by physical and chemical abuses to human periodontal ligament cells, and to review some of the known functions of stress response proteins produced as a result of such treatments. For these studies human PDL cells were exposed to sublethal challenges of 43 degrees C heat, sodium arsenite and the amino acid analog L-azetidine-2-carboxylic acid (AZC). The cells were labelled with [35S]-methionine and the proteins produced were examined by autofluorography of SDS-PAGE gels. Heat challenges were shown to induce hsps with an apparent mol. wts. of 90K, 68-72K, 41-47K, and 36 K. Arsenite-treated cells produced similar hsps including a 30k protein not produced by other forms of stress. AZC treatment resulted in the production of apparent functionless hsps with apparent molecular weights of 90,000, 72,000, 68,000 and 36,000. The function of these proteins and their possible role in periodontal disease is discussed.

  19. Heat stress-induced hepatotoxicity and its prevention by resveratrol in rats.

    PubMed

    Das, Asima

    2011-06-01

    The high ambient temperature beyond the range of comfort zone or thermoneutral zone causes environmental heat stress (HST). It causes serious physiological dysfunction that may result in heat-related diseases and even death. The underlying mechanism in the pathogenesis of hepatic dysfunction following hyperthermic challenge and the possible involvement of oxidative stress to induce oxidative deterioration of liver functions in adult rats are investigated in this study. Cellular damage was assessed in terms of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and histology of liver. The effect of hyperthermia in altering the oxidative stress was evaluated on the basis of its influence on hepatic lipid peroxidation and antioxidant status-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activity. The current study demonstrated that HST is associated with a complex set of integrated alterations in liver, time-dependent rise in oxidative stress followed by distinct pattern of liver injury in animals. Heat-induced hepatotoxicity was assessed by increased lipid peroxidation, depletion of antioxidant enzyme activities such as SOD, CAT, GPx and tissue damages revealed by hepatic vacuolization, and widespread necrosis. The study also revealed that pretreatment with resveratrol resulted in normalizing these parameters appreciably, emphasizing the therapeutic potentials of this polyphenol. Taken together, the results suggest that an increase in free radical formation relative to loss of the antioxidant defense system during heat stress may render liver more susceptible to oxidative damage, leading to their functional inactivation. However, resveratrol supplementation can be an effective antidote in the treatment of HST-induced malfunction.

  20. Patterns of Gene Expression Associated with Recovery and Injury in Heat-stressed Rats

    DTIC Science & Technology

    2014-12-03

    RESEARCH ARTICLE Open Access Patterns of gene expression associated with recovery and injury in heat-stressed rats Jonathan D Stallings1*, Danielle L...characterization of the gene response to heat stress using an in vivo conscious rat model. Results: We heated rats until implanted thermal probes indicated a maximal...all four organs at Tc,Max. Self-organizing maps identified gene-specific signatures corresponding to protein-folding disorders in heat-stressed rats

  1. Thermomechanical Stress in Cryopreservation Via Vitrification With Nanoparticle Heating as a Stress-Moderating Effect.

    PubMed

    Eisenberg, David P; Bischof, John C; Rabin, Yoed

    2016-01-01

    This study focuses on thermomechanical effects in cryopreservation associated with a novel approach of volumetric heating by means on nanoparticles in an alternating electromagnetic field. This approach is studied for the application of cryopreservation by vitrification, where the crystalline phase is completely avoided-the cornerstone of cryoinjury. Vitrification can be achieved by quickly cooling the material to cryogenic storage, where ice cannot form. Vitrification can be maintained at the end of the cryogenic protocol by quickly rewarming the material back to room temperature. The magnitude of the rewarming rates necessary to maintain vitrification is much higher than the magnitude of the cooling rates that are required to achieve it in the first place. The most common approach to achieve the required cooling and rewarming rates is by exposing the specimen's surface to a temperature-controlled environment. Due to the underlying principles of heat transfer, there is a size limit in the case of surface heating beyond which crystallization cannot be prevented at the center of the specimen. Furthermore, due to the underlying principles of solid mechanics, there is a size limit beyond which thermal expansion in the specimen can lead to structural damage and fractures. Volumetric heating during the rewarming phase of the cryogenic protocol can alleviate these size limitations. This study suggests that volumetric heating can reduce thermomechanical stress, when combined with an appropriate design of the thermal protocol. Without such design, this study suggests that the level of stress may still lead to structural damage even when volumetric heating is applied. This study proposes strategies to harness nanoparticles heating in order to reduce thermomechanical stress in cryopreservation by vitrification.

  2. Heat shock factor 1 promotes TERRA transcription and telomere protection upon heat stress.

    PubMed

    Koskas, Sivan; Decottignies, Anabelle; Dufour, Solenne; Pezet, Mylène; Verdel, André; Vourc'h, Claire; Faure, Virginie

    2017-03-27

    In response to metabolic or environmental stress, cells activate powerful defense mechanisms to prevent the formation and accumulation of toxic protein aggregates. The main orchestrator of this cellular response is HSF1 (heat shock factor 1), a transcription factor involved in the up-regulation of protein-coding genes with protective roles. It has become very clear that HSF1 has a broader function than initially expected. Indeed, our previous work demonstrated that, upon stress, HSF1 activates the transcription of a non-coding RNA, named Satellite III, at pericentromeric heterochromatin. Here, we observe that the function of HSF1 extends to telomeres and identify subtelomeric DNA as a new genomic target of HSF1. We show that the binding of HSF1 to subtelomeric regions plays an essential role in the upregulation of non-coding TElomeric Repeat containing RNA (TERRA) transcription upon heat shock. Importantly, our data show that telomere integrity is impacted by heat shock and that telomeric DNA damages are markedly enhanced in HSF1 deficient cells. Altogether, our findings reveal a new direct and essential function of HSF1 in the transcriptional activation of TERRA and in telomere protection upon stress.

  3. Does heat stress alter the pig's response to dietary fat?

    PubMed

    Kellner, T A; Baumgard, L H; Prusa, K J; Gabler, N K; Patience, J F

    2016-11-01

    Heat stress (HS) results in major losses to the pork industry via reduced growth performance and, possibly, carcass fat quality. The experimental objective was to measure the effects of HS on the pig's response to dietary fat in terms of lipid digestion, metabolism, and deposition over a 35-d finishing period. A total of 96 PIC 337 × C22/C29 (PIC, Inc., Hendersonville, TN) barrows (initial BW of 100.4 ± 1.2 kg) were randomly allotted to 1 of 9 treatments arranged as a 3 × 3 factorial: thermoneutral (TN; constant 24°C; ad libitum access to feed), pair-fed thermoneutral (PFTN; constant 24°C; limit fed based on previous HS daily feed intake), or HS (cyclical 28°C nighttime, 33°C from d 0 to 7, 33.5°C from d 7 to 14, 34°C from d 14 to 21, 34.5°C from d 21 to 28, and 35°C from d 28 to 35 daytime; ab libitum access to feed) and diet (a corn-soybean meal-based diet with 0% added fat [CNTR], CNTR with 3% added tallow [TAL; iodine value {IV} = 41.8], or CNTR with 3% added corn oil [CO; IV = 123.0]). No interactions between environment and diet were evident for any major response criteria ( ≥ 0.063). Rectal temperature increased due to HS (39.0°C for HS, 38.1°C for TN, and 38.2°C for PFTN; < 0.001). Heat stress decreased ADFI (27.8%; < 0.001), ADG (0.72 kg/d for HS, 1.03 kg/d for TN, and 0.78 kg/d for PFTN; < 0.001), and G:F (0.290 for HS, 0.301 for TN, and 0.319 for PFTN; = 0.006). Heat stress barrows required 1.2 Mcal of ME intake more per kilogram of BW gain than PFTN ( < 0.001). Heat stress tended to result in the lowest apparent total tract digestibility of acid hydrolyzed ether extract (AEE; 59.0% for HS, 60.2% for TN, and 61.4% for PFTN; = 0.055). True total tract digestibility (TTTD) of AEE of CO-based diets (99.3%) was greater than that of CNTR (97.3%) and TAL-based diets (96.3%; = 0.012). Environment had no impact on TTTD of AEE ( = 0.118). Environment had no impact on jowl IV at market (69.2 g/100 g for HS, 69.3 g/100 g for TN, and 69.8 g/100 g for

  4. Does the hair influence heat extraction from the head during head cooling under heat stress?

    PubMed Central

    SHIN, Sora; PARK, Joonhee; LEE, Joo-Young

    2015-01-01

    The purpose of this study was to investigate the effects of head hair on thermoregulatory responses when cooling the head under heat stress. Eight young males participated in six experimental conditions: normal hair (100–130 mm length) and cropped hair (5 mm length) with three water inlet temperatures of 10, 15, and 20°C. The head and neck of subjects were cooled by a liquid perfused hood while immersing legs at 42°C water for 60 min in a sitting position at the air temperature of 28°C with 30% RH. The results showed that heat removal from the normal hair condition was not significantly different from the cropped hair condition. Rectal and mean skin temperatures, and sweat rate showed no significant differences between the normal and cropped hair conditions. Heat extraction from the head was significantly greater in 10°C than in 15 or 20°C cooling (p<0.05) for both normal and cropped hair, whereas subjects preferred the 15°C more than the 10 or 20°C cooling regimen. These results indicate that the selection of effective cooling temperature is more crucial than the length of workers’ hair during head cooling under heat stress, and such selection should be under the consideration of subjective perceptions with physiological responses. PMID:26165361

  5. Does the hair influence heat extraction from the head during head cooling under heat stress?

    PubMed

    Shin, Sora; Park, Joonhee; Lee, Joo-Young

    2015-01-01

    The purpose of this study was to investigate the effects of head hair on thermoregulatory responses when cooling the head under heat stress. Eight young males participated in six experimental conditions: normal hair (100-130 mm length) and cropped hair (5 mm length) with three water inlet temperatures of 10, 15, and 20°C. The head and neck of subjects were cooled by a liquid perfused hood while immersing legs at 42°C water for 60 min in a sitting position at the air temperature of 28°C with 30% RH. The results showed that heat removal from the normal hair condition was not significantly different from the cropped hair condition. Rectal and mean skin temperatures, and sweat rate showed no significant differences between the normal and cropped hair conditions. Heat extraction from the head was significantly greater in 10°C than in 15 or 20°C cooling (p<0.05) for both normal and cropped hair, whereas subjects preferred the 15°C more than the 10 or 20°C cooling regimen. These results indicate that the selection of effective cooling temperature is more crucial than the length of workers' hair during head cooling under heat stress, and such selection should be under the consideration of subjective perceptions with physiological responses.

  6. Heat stress abatement during the dry period influences prolactin signaling in lymphocytes Heat stress abatement during the dry period influences prolactin signaling in lymphocytes

    USDA-ARS?s Scientific Manuscript database

    Heat stress perturbs PRL release and affects dairy cow lactational performance and immune cell function. We hypothesized that greater PRL concentration in plasma of heat-stressed cows would decrease expression of PRL-R mRNA and increase mRNA expression of suppressors of cytokine signaling (SOCS) in ...

  7. Acute Heat Stress and Reduced Nutrient Intake Alter Intestinal Proteomic Profile and Gene Expression in Pigs

    PubMed Central

    Pearce, Sarah C.; Lonergan, Steven M.; Huff-Lonergan, Elisabeth; Baumgard, Lance H.; Gabler, Nicholas K.

    2015-01-01

    Heat stress and reduced feed intake negatively affect intestinal integrity and barrier function. Our objective was to compare ileum protein profiles of pigs subjected to 12 hours of HS, thermal neutral ad libitum feed intake, or pair-fed to heat stress feed intake under thermal neutral conditions (pair-fed thermal neutral). 2D-Differential In Gel Electrophoresis and gene expression were performed. Relative abundance of 281 and 138 spots differed due to heat stress, compared to thermal neutral and pair-fed thermal neutral pigs, respectively. However, only 20 proteins were different due to feed intake (thermal neutral versus pair-fed thermal neutral). Heat stress increased mRNA expression of heat shock proteins and protein abundance of heat shock proteins 27, 70, 90-α and β were also increased. Heat stress reduced ileum abundance of several metabolic enzymes, many of which are involved in the glycolytic or TCA pathways, indicating a change in metabolic priorities. Stress response enzymes peroxiredoxin-1 and peptidyl-prolyl cis-trans isomerase A were decreased in pair-fed thermal neutral and thermal neutral pigs compared to heat stress. Heat stress increased mRNA abundance markers of ileum hypoxia. Altogether, these data show that heat stress directly alters intestinal protein and mRNA profiles largely independent of reduced feed intake. These changes may be related to the reduced intestinal integrity associated with heat stress. PMID:26575181

  8. Heat stress responses modulate calcium regulations and electrophysiological characteristics in atrial myocytes.

    PubMed

    Chen, Yao-Chang; Kao, Yu-Hsun; Huang, Chun-Feng; Cheng, Chen-Chuan; Chen, Yi-Jen; Chen, Shih-Ann

    2010-04-01

    Heat stress-induced responses change the ionic currents and calcium homeostasis. However, the molecular insights into the heat stress responses on calcium homeostasis remain unclear. The purposes of this study were to examine the mechanisms of heat stress responses on calcium handling and electrophysiological characteristics in atrial myocytes. We used indo-1 fluorimetric ratio technique and whole-cell patch clamp to investigate the intracellular calcium, action potentials, and ionic currents in isolated rabbit single atrial cardiomyocytes with or without (control) exposure to heat stress (43 degrees C, 15 min) 5+/-1 h before experiments. The expressions of sarcoplasmic reticulum ATPase (SERCA2a), and Na(+)-Ca(2+) exchanger (NCX) in the control and heat stress-treated atrial myocytes were evaluated by Western blot and real-time PCR. As compared with control myocytes, the heat stress-treated myocytes had larger sarcoplasmic reticulum calcium content and larger intracellular calcium transient with a shorter decay portion. Heat stress-treated myocytes also had larger L-type calcium currents, transient outward potassium currents, but smaller NCX currents. Heat stress responses increased the protein expressions, SERCA2a, NCX, and heat shock protein. However, heat stress responses did not change the RNA expression of SERCA2a and NCX. In conclusion, heat stress responses change calcium handling through protein but not RNA regulation.

  9. Active cutaneous vasodilation in resting humans during mild heat stress.

    PubMed

    Kamijo, Yoshi-Ichiro; Lee, Kichang; Mack, Gary W

    2005-03-01

    The role of skin temperature in reflex control of the active cutaneous vasodilator system was examined in six subjects during mild graded heat stress imposed by perfusing water at 34, 36, 38, and 40 degrees C through a tube-lined garment. Skin sympathetic nerve activity (SSNA) was recorded from the peroneal nerve with microneurography. While monitoring esophageal, mean skin, and local skin temperatures, we recorded skin blood flow at bretylium-treated and untreated skin sites by using laser-Doppler velocimetry and local sweat rate by using capacitance hygrometry on the dorsal foot. Cutaneous vascular conductance (CVC) was calculated by dividing skin blood flow by mean arterial pressure. Mild heat stress increased mean skin temperature by 0.2 or 0.3 degrees C every stage, but esophageal and local skin temperature did not change during the first three stages. CVC at the bretylium tosylate-treated site (CVC(BT)) and sweat expulsion number increased at 38 and 40 degrees C compared with 34 degrees C (P < 0.05); however, CVC at the untreated site did not change. SSNA increased at 40 degrees C (P < 0.05, different from 34 degrees C). However, SSNA burst amplitude increased (P < 0.05), whereas SSNA burst duration decreased (P < 0.05), at the same time as we observed the increase in CVC(BT) and sweat expulsion number. These data support the hypothesis that the active vasodilator system is activated by changes in mean skin temperature, even at normal core temperature, and illustrate the intricate competition between active vasodilator and the vasoconstrictor system for control of skin blood flow during mild heat stress.

  10. Heat stress results in loss of chloroplast Cu/Zn superoxide dismutase and increased damage to Photosystem II in combined drought-heat stressed Lotus japonicus.

    PubMed

    Sainz, Martha; Díaz, Pedro; Monza, Jorge; Borsani, Omar

    2010-09-01

    Drought and heat stress have been studied extensively in plants, but most reports involve analysis of response to only one of these stresses. Studies in which both stresses were studied in combination have less commonly been reported. We report the combined effect of drought and heat stress on Photosystem II (PSII) of Lotus japonicus cv. Gifu plants. Photochemistry of PSII was not affected by drought or heat stress alone, but the two stresses together decreased PSII activity as determined by fluorescence emission. Heat stress alone resulted in degradation of D1 and CP47 proteins, and D2 protein was also degraded by combined drought-heat stress. None of these proteins were degraded by drought stress alone. Drought alone induced accumulation of hydrogen peroxide but the drought-heat combination led to an increase in superoxide levels and a decrease in hydrogen peroxide levels. Furthermore, combined drought-heat stress was correlated with an increase in oxidative damage as determined by increased levels of thiobarbituric acid reactive substances. Heat also induced degradation of chloroplast Cu/Zn superoxide dismutase (SOD: EC 1.15.1.1) as shown by reduced protein levels and isozyme-specific SOD activity. Loss of Cu/Zn SOD and induction of catalase (CAT: EC 1.11.1.6) activity would explain the altered balance between hydrogen peroxide and superoxide in response to drought vs combined drought-heat stress. Degradation of PSII could thus be caused by the loss of components of chloroplast antioxidant defence systems and subsequent decreased function of PSII. A possible explanation for energy dissipation by L. japonicus under stress conditions is discussed.

  11. Factors of subjective heat stress of urban citizens in contexts of everyday life

    NASA Astrophysics Data System (ADS)

    Kunz-Plapp, Tina; Hackenbruch, Julia; Schipper, Janus Willem

    2016-04-01

    Heat waves and the consequent heat stress of urban populations have a growing relevance in urban risk management and strategies of urban adaptation to climate change. In this context, social science studies on subjective experiencing of heat as stress by urban citizens are a new emerging field. To contribute to the understanding of self-reported subjective heat stress and its major determinants in a daily life perspective, we conducted a questionnaire survey with 323 respondents in Karlsruhe, Germany, after heat waves in July and August 2013. Statistical data analysis showed that subjective heat stress is an issue permeating everyday activities. Subjective heat stress at home was lower than at work and in general. Subjective heat stress in general, at home, and at work was determined by the health impairments experienced during the heat and the feeling of being helplessly exposed to the heat. For subjective heat stress at home, characteristics of the residential building and the built environment additionally played a role. Although the rate of implemented coping measures was rather high, coping measures showed no uniform effect for the subjective heat stress. We conclude that in terms of urban adaptation strategies, further research is needed to understand how various processes of daily social (work) life enable or limit individual coping and that communication strategies are important for building capacities to better cope with future heat waves.

  12. Role of the Red Ginseng in Defense against the Environmental Heat Stress in Sprague Dawley Rats.

    PubMed

    Kim, Kui-Jin; Yoon, Kye-Yoon; Hong, Hee-Do; Lee, Boo-Yong

    2015-11-10

    Global temperature change causes heat stress related disorders in humans. A constituent of red ginseng has been known the beneficial effect on the resistance to many diseases. However, the mechanism of red ginseng (RG) against heat stress still remains unclear. To determine the effect of RG on heat stress, we examined the effect of the RG on the gene expression profiles in rats subjected to environmental heat stress. We evaluated the transcripts associated with hepatic lipid accumulation and oxidative stress in rats subjected to heat stress. We also analyzed the reactive oxygen species (ROS) contents. Our results suggested RG inhibited heat stress mediated altering mRNA expressions include HSPA1, DEAF1, HMGCR, and FMO1. We also determined RG attenuated fat accumulation in the liver by altering C/EBPβ expression. RG promoted to repress the heat stress mediated hepatic cell death by inhibiting of Bcl-2 expression in rats subjected to heat stress. Moreover, RG administered group during heat stress dramatically decreased the malondialdehyde (MDA) contents and ROS associated genes compared with the control group. Thus, we suggest that RG might influence inhibitory effect on environmental heat stress induced abnormal conditions in humans.

  13. Silver nanoparticles induced heat shock protein 70, oxidative stress and apoptosis in Drosophila melanogaster

    SciTech Connect

    Ahamed, Maqusood; Posgai, Ryan; Gorey, Timothy J.; Nielsen, Mark; Hussain, Saber M.; Rowe, John J.

    2010-02-01

    Due to the intensive commercial application of silver nanoparticles (Ag NPs), risk assessment of this nanoparticle is of great importance. Our previous in vitro study demonstrated that Ag NPs caused DNA damage and apoptosis in mouse embryonic stem cells and fibroblasts. However, toxicity of Ag NPs in vivo is largely lacking. This study was undertaken to examine the toxic effects of well-characterized polysaccharide coated 10 nm Ag NPs on heat shock stress, oxidative stress, DNA damage and apoptosis in Drosophila melanogaster. Third instar larvae of D. melanogaster were fed a diet of standard cornmeal media mixed with Ag NPs at the concentrations of 50 and 100 mug/ml for 24 and 48 h. Ag NPs up-regulated the expression of heat shock protein 70 and induced oxidative stress in D. melanogaster. Malondialdehyde level, an end product of lipid peroxidation was significantly higher while antioxidant glutathione content was significantly lower in Ag NPs exposed organisms. Activities of antioxidant enzyme superoxide dismutase and catalase were also significantly higher in the organisms exposed to Ag NPs. Furthermore, Ag NPs up-regulated the cell cycle checkpoint p53 and cell signaling protein p38 that are involved in the DNA damage repair pathway. Moreover, activities of caspase-3 and caspase-9, markers of apoptosis were significantly higher in Ag NPs exposed organisms. The results indicate that Ag NPs in D. melanogaster induce heat shock stress, oxidative stress, DNA damage and apoptosis. This study suggests that the organism is stressed and thus warrants more careful assessment of Ag NPs using in vivo models to determine if chronic exposure presents developmental and reproductive toxicity.

  14. A protocol to assess insect resistance to heat waves, applied to bumblebees (Bombus Latreille, 1802).

    PubMed

    Martinet, Baptiste; Lecocq, Thomas; Smet, Jérémy; Rasmont, Pierre

    2015-01-01

    Insect decline results from numerous interacting factors including climate change. One of the major phenomena related to climate change is the increase of the frequency of extreme events such as heat waves. Since heat waves are suspected to dramatically increase insect mortality, there is an urgent need to assess their potential impact. Here, we determined and compared the resistance to heat waves of insects under hyperthermic stress through their time before heat stupor (THS) when they are exposed to an extreme temperature (40°C). For this, we used a new experimental standardised device available in the field or in locations close to the field collecting sites. We applied this approach on different Arctic, Boreo-Alpine and Widespread bumblebee species in order to predict consequences of heat waves. Our results show a heat resistance gradient: the heat stress resistance of species with a centred arctic distribution is weaker than the heat resistance of the Boreo-Alpine species with a larger distribution which is itself lower than the heat stress resistance of the ubiquitous species.

  15. A Protocol to Assess Insect Resistance to Heat Waves, Applied to Bumblebees (Bombus Latreille, 1802)

    PubMed Central

    Martinet, Baptiste; Lecocq, Thomas; Smet, Jérémy; Rasmont, Pierre

    2015-01-01

    Insect decline results from numerous interacting factors including climate change. One of the major phenomena related to climate change is the increase of the frequency of extreme events such as heat waves. Since heat waves are suspected to dramatically increase insect mortality, there is an urgent need to assess their potential impact. Here, we determined and compared the resistance to heat waves of insects under hyperthermic stress through their time before heat stupor (THS) when they are exposed to an extreme temperature (40°C). For this, we used a new experimental standardised device available in the field or in locations close to the field collecting sites. We applied this approach on different Arctic, Boreo-Alpine and Widespread bumblebee species in order to predict consequences of heat waves. Our results show a heat resistance gradient: the heat stress resistance of species with a centred arctic distribution is weaker than the heat resistance of the Boreo-Alpine species with a larger distribution which is itself lower than the heat stress resistance of the ubiquitous species. PMID:25738862

  16. Plasma Volume during Heat Stress and Exercise in Women,

    DTIC Science & Technology

    1986-11-01

    AD-A174 W16 PLASMA VOLUME DURING HEAT STRESS AND EXERCISE IN o t ( U ) ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA L A STEPHENSON ET AL NOV...86 USARIER-M-i-87 U NLLASSIFE F/G 614 II 11110 2 2 IlUll Im .. : llILIII.a ILO 1ffl.2.5 au* iICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF...NAME OF MONITORING ORGANIZATION U.S. Army Res Inst of Env Med (if aplicable) U.S. Army Research Institute of GRD- U - Environmental Medicine 6c

  17. Self organizing maps in urban heat stress projections

    NASA Astrophysics Data System (ADS)

    Lee, Kyoung

    2016-04-01

    A self organizing map (SOM) is an unsupervised machine learning algorithm well suited for identifying patterns in large datasets. It has been used successfully to classify atmospheric states in climate data and as part of statistical downscaling procedures. This study aims to use SOMs to produce downscaled CMIP5-based projections of wet-bulb temperature in urban areas, taking into account the regional atmospheric state and learned local dynamics. These downscaled projections will be compared to the CMIP5 models as well as to observations and then used to project local extreme heat stress events in the future.

  18. Hormonal modulation of the heat shock response: insights from fish with divergent cortisol stress responses.

    PubMed

    LeBlanc, Sacha; Höglund, Erik; Gilmour, Kathleen M; Currie, Suzanne

    2012-01-01

    Acute temperature stress in animals results in increases in heat shock proteins (HSPs) and stress hormones. There is evidence that stress hormones influence the magnitude of the heat shock response; however, their role is equivocal. To determine whether and how stress hormones may affect the heat shock response, we capitalized on two lines of rainbow trout specifically bred for their high (HR) and low (LR) cortisol response to stress. We predicted that LR fish, with a low cortisol but high catecholamine response to stress, would induce higher levels of HSPs after acute heat stress than HR trout. We found that HR fish have significantly higher increases in both catecholamines and cortisol compared with LR fish, and LR fish had no appreciable stress hormone response to heat shock. This unexpected finding prevented further interpretation of the hormonal modulation of the heat shock response but provided insight into stress-coping styles and environmental stress. HR fish also had a significantly greater and faster heat shock response and less oxidative protein damage than LR fish. Despite these clear differences in the physiological and cellular responses to heat shock, there were no differences in the thermal tolerance of HR and LR fish. Our results support the hypothesis that responsiveness to environmental change underpins the physiological differences in stress-coping styles. Here, we demonstrate that the heat shock response is a distinguishing feature of the HR and LR lines and suggest that it may have been coselected with the hormonal responses to stress.

  19. Radiant heat loss, an unexploited path for heat stress reduction in shaded cattle.

    PubMed

    Berman, A; Horovitz, T

    2012-06-01

    Reducing thermal radiation on shaded animals reduces heat stress independently of other means of stress relief. Radiant heat exchange was estimated as a function of climate, shade structure, and animal density. Body surface portion exposed to radiant sources in shaded environments was determined by geometrical relations to determine angles of view of radiation sources (roof underside, sky, sun-exposed ground, shaded ground) on the animal's surface. The relative representation of environment radiation sources on the body surface was determined. Animal thermal radiation balance was derived from radiant heat gained from radiation sources (including surrounding animals) and that lost from the animal surface. The animal environment was assumed to have different shade dimensions and temperatures. These were summed to the radiant heat balance of the cow. The data formed served to estimate the effect of changes in intensity of radiation sources, roof and shaded surface dimensions, and animal density on radiant heat balance (Rbal) of cattle. Roof height effect was expressed by effect of roof temperature on Rbal. Roof underside temperature (35 to 75°C) effect on Rbal was reduced by roof height. If roof height were 4m, an increase in its underside temperature from 35 to 75°C would increase mean Rbal from -63 to -2 W·m⁻², whereas if roof height were 10 m, Rbal would only increase from -99 to -88 W·m⁻². A hot ground temperature increase from 35 to 65°C reduced mean Rbal heat loss from -45 to 3 W·m⁻². Increasing the surface of the shaded area had only a minor effect on Rbal and on the effect of hot ground on Rbal. Increasing shade roof height reduced the effect of roof temperature on Rbal to minor levels when height was > 8m. Increasing the roof height from 4 to 10 m decreased Rbal from -32 to -94 W·m⁻². Increasing indirect radiation from 100 to 500 W·m⁻² was associated with an increase in Rbal from -135 to +23 W·m⁻². Their combined effects were lower

  20. Spatio-temporal modelling of heat stress and climate change implications for the Murray dairy region, Australia.

    PubMed

    Nidumolu, Uday; Crimp, Steven; Gobbett, David; Laing, Alison; Howden, Mark; Little, Stephen

    2014-08-01

    The Murray dairy region produces approximately 1.85 billion litres of milk each year, representing about 20 % of Australia's total annual milk production. An ongoing production challenge in this region is the management of the impacts of heat stress during spring and summer. An increase in the frequency and severity of extreme temperature events due to climate change may result in additional heat stress and production losses. This paper assesses the changing nature of heat stress now, and into the future, using historical data and climate change projections for the region using the temperature humidity index (THI). Projected temperature and relative humidity changes from two global climate models (GCMs), CSIRO MK3.5 and CCR-MIROC-H, have been used to calculate THI values for 2025 and 2050, and summarized as mean occurrence of, and mean length of consecutive high heat stress periods. The future climate scenarios explored show that by 2025 an additional 12-15 days (compared to 1971 to 2000 baseline data) of moderate to severe heat stress are likely across much of the study region. By 2050, larger increases in severity and occurrence of heat stress are likely (i.e. an additional 31-42 moderate to severe heat stress days compared with baseline data). This increasing trend will have a negative impact on milk production among dairy cattle in the region. The results from this study provide useful insights on the trends in THI in the region. Dairy farmers and the dairy industry could use these results to devise and prioritise adaptation options to deal with projected increases in heat stress frequency and severity.

  1. Spatio-temporal modelling of heat stress and climate change implications for the Murray dairy region, Australia

    NASA Astrophysics Data System (ADS)

    Nidumolu, Uday; Crimp, Steven; Gobbett, David; Laing, Alison; Howden, Mark; Little, Stephen

    2014-08-01

    The Murray dairy region produces approximately 1.85 billion litres of milk each year, representing about 20 % of Australia's total annual milk production. An ongoing production challenge in this region is the management of the impacts of heat stress during spring and summer. An increase in the frequency and severity of extreme temperature events due to climate change may result in additional heat stress and production losses. This paper assesses the changing nature of heat stress now, and into the future, using historical data and climate change projections for the region using the temperature humidity index (THI). Projected temperature and relative humidity changes from two global climate models (GCMs), CSIRO MK3.5 and CCR-MIROC-H, have been used to calculate THI values for 2025 and 2050, and summarized as mean occurrence of, and mean length of consecutive high heat stress periods. The future climate scenarios explored show that by 2025 an additional 12-15 days (compared to 1971 to 2000 baseline data) of moderate to severe heat stress are likely across much of the study region. By 2050, larger increases in severity and occurrence of heat stress are likely (i.e. an additional 31-42 moderate to severe heat stress days compared with baseline data). This increasing trend will have a negative impact on milk production among dairy cattle in the region. The results from this study provide useful insights on the trends in THI in the region. Dairy farmers and the dairy industry could use these results to devise and prioritise adaptation options to deal with projected increases in heat stress frequency and severity.

  2. Bioequivalence and food effect of heat-stressed and non-heat-stressed dapagliflozin 2.5- and 10-mg tablets.

    PubMed

    LaCreta, Frank; Griffen, Steven C; Liu, Xiaoni; Smith, Charles; Hines, Carey; Volk, Kevin; Tejwani, Ravindra; Boulton, David W

    2016-09-10

    Physical storage of formulations may result in physical composition changes that affect pharmacokinetics. Dapagliflozin, an oral sodium-glucose cotransporter 2 inhibitor used for type 2 diabetes mellitus, stored under prolonged exposure to heat converts crystalline dapagliflozin to an amorphous form. Bioequivalence of the amorphous to crystalline form and food effects of each form in the 2.5-mg formulation are unknown. Two open-label, crossover, single-dose studies in healthy participants assessed pharmacokinetics for heat-stressed (HS) and non-heat-stressed (NH) dapagliflozin 10-mg (study 1, N=29, fasted+HS food effect) and 2.5-mg (study 2, N=28, fasted+HS and NH food effect) tablets. The 90% confidence intervals for geometric mean ratios of area under the concentration-time curve (AUC) and peak concentration (Cmax) for HS 2.5- and 10-mg tablets were within 80-125%, indicating bioequivalence. In the fed vs. fasted state for 2.5-mg and 10-mg HS tablets, AUCs were similar, time to Cmax was prolonged by 1.25h, and Cmax decreased by approximately 50%. No serious adverse events were reported. Given that dapagliflozin's efficacy is dependent upon AUC, it was concluded that HS and NH dapagliflozin tablets are bioequivalent in 2.5- and 10-mg doses with no clinically meaningful food effect for either form.

  3. Use of heat stress responsive gene expression levels for early selection of heat tolerant cabbage (Brassica oleracea L.).

    PubMed

    Park, Hyun Ji; Jung, Won Yong; Lee, Sang Sook; Song, Jun Ho; Kwon, Suk-Yoon; Kim, Hyeran; Kim, Chulwook; Ahn, Jun Cheul; Cho, Hye Sun

    2013-06-04

    Cabbage is a relatively robust vegetable at low temperatures. However, at high temperatures, cabbage has disadvantages, such as reduced disease tolerance and lower yields. Thus, selection of heat-tolerant cabbage is an important goal in cabbage breeding. Easier or faster selection of superior varieties of cabbage, which are tolerant to heat and disease and have improved taste and quality, can be achieved with molecular and biological methods. We compared heat-responsive gene expression between a heat-tolerant cabbage line (HTCL), "HO", and a heat-sensitive cabbage line (HSCL), "JK", by Genechip assay. Expression levels of specific heat stress-related genes were increased in response to high-temperature stress, according to Genechip assays. We performed quantitative RT-PCR (qRT-PCR) to compare expression levels of these heat stress-related genes in four HTCLs and four HSCLs. Transcript levels for heat shock protein BoHsp70 and transcription factor BoGRAS (SCL13) were more strongly expressed only in all HTCLs compared to all HSCLs, showing much lower level expressions at the young plant stage under heat stress (HS). Thus, we suggest that expression levels of these genes may be early selection markers for HTCLs in cabbage breeding. In addition, several genes that are involved in the secondary metabolite pathway were differentially regulated in HTCL and HSCL exposed to heat stress.

  4. Use of Heat Stress Responsive Gene Expression Levels for Early Selection of Heat Tolerant Cabbage (Brassica oleracea L.)

    PubMed Central

    Park, Hyun Ji; Jung, Won Yong; Lee, Sang Sook; Song, Jun Ho; Kwon, Suk-Yoon; Kim, HyeRan; Kim, ChulWook; Ahn, Jun Cheul; Cho, Hye Sun

    2013-01-01

    Cabbage is a relatively robust vegetable at low temperatures. However, at high temperatures, cabbage has disadvantages, such as reduced disease tolerance and lower yields. Thus, selection of heat-tolerant cabbage is an important goal in cabbage breeding. Easier or faster selection of superior varieties of cabbage, which are tolerant to heat and disease and have improved taste and quality, can be achieved with molecular and biological methods. We compared heat-responsive gene expression between a heat-tolerant cabbage line (HTCL), “HO”, and a heat-sensitive cabbage line (HSCL), “JK”, by Genechip assay. Expression levels of specific heat stress-related genes were increased in response to high-temperature stress, according to Genechip assays. We performed quantitative RT-PCR (qRT-PCR) to compare expression levels of these heat stress-related genes in four HTCLs and four HSCLs. Transcript levels for heat shock protein BoHsp70 and transcription factor BoGRAS (SCL13) were more strongly expressed only in all HTCLs compared to all HSCLs, showing much lower level expressions at the young plant stage under heat stress (HS). Thus, we suggest that expression levels of these genes may be early selection markers for HTCLs in cabbage breeding. In addition, several genes that are involved in the secondary metabolite pathway were differentially regulated in HTCL and HSCL exposed to heat stress. PMID:23736694

  5. Stress response in the ascidian Ciona intestinalis: transcriptional profiling of genes for the heat shock protein 70 chaperone system under heat stress and endoplasmic reticulum stress

    PubMed Central

    Fujikawa, Tetsuya; Munakata, Takeo; Kondo, Shin-ichi; Satoh, Nori

    2009-01-01

    The genome of Ciona intestinalis contains eight genes for HSP70 superfamily proteins, 36 genes for J-proteins, a gene for a J-like protein, and three genes for BAG family proteins. To understand the stress responses of genes in the HSP70 chaperone system comprehensively, the transcriptional profiles of these 48 genes under heat stress and endoplasmic reticulum (ER) stress were studied using real-time reverse transcriptase–polymerase chain reaction (RT-PCR) analysis. Heat stress treatment increased the messenger RNA (mRNA) levels of six HSP70 superfamily genes, eight J-protein family genes, and two BAG family genes. In the cytoplasmic group of the DnaK subfamily of the HSP70 family, Ci-HSPA1/6/7-like was the only heat-inducible gene and Ci-HSPA2/8 was the only constitutively active gene which showed striking simplicity in comparison with other animals that have been examined genome-wide so far. Analyses of the time course and temperature dependency of the heat stress responses showed that the induction of Ci-HSPA1/6/7-like expression rises to a peak after heat stress treatment at 28°C (10°C upshift from control temperature) for 1 h. ER stress treatment with Brefeldin A, a drug that is known to act as ER stress inducer, increased the mRNA levels of four HSP70 superfamily genes and four J-protein family genes. Most stress-inducible genes are conserved between Ciona and vertebrates, as expected from a close evolutionary relationship between them. The present study characterized the stress responses of HSP70 chaperone system genes in Ciona for the first time and provides essential data for comprehensive understanding of the functions of the HSP70 chaperone system. Electronic supplementary material The online version of this article (doi:10.1007/s12192-009-0133-x) contains supplementary material, which is available to authorized users. PMID:19629754

  6. Effects of genistein and hesperidin on biomarkers of heat stress in broilers under persistent summer stress.

    PubMed

    Kamboh, A A; Hang, S Q; Bakhetgul, M; Zhu, W-Y

    2013-09-01

    This study investigated the supplemental effects of the flavonoids genistein and hesperidin for biomarkers of heat stress in broilers reared under persistent summer stress. A total of 360 one-day-old, mixed-sex broiler chickens were divided into 6 treatment groups: control or supplemented with 5 mg of genistein•kg of feed(-1), 20 mg of hesperidin•kg of feed(-1), or a mixture of genistein and hesperidin (1:4) at a dosage of 5 mg•kg(-1), 10 mg•kg(-1), and 20 mg•kg(-1) of feed. Broilers were slaughtered at 42 d and samples were analyzed for hematological profile, creatine kinase, lactate dehydrogenase, and heat shock protein 70 mRNA levels. Results showed that dietary genistein and hesperidin improved (P < 0.05) the weekly performance of broilers particularly during the finisher period. The circulating heterophils and heterophil-to-lymphocyte ratios were found to decrease (P < 0.01) in the treated groups. Moreover, biomarkers of heat stress including the level of creatine kinase, lactate dehydrogenase, and heat shock protein 70 mRNA of breast muscle was also changed (P < 0.01) positively by the dietary compounds with pronounced effects of combined treatments. These findings suggested that genistein and hesperidin could be a prime strategy to ameliorate summer stress effects in broilers; and a combination of both compounds may lead to mutual synergistic effects. It could be suggested that dietary use of both genistein and hesperidin as a feed supplement may offer a potential nutritional strategy in tropical and subtropical regions to overcome the deleterious effects of persistent summer stress in broiler production.

  7. Effects of heat stress on the regeneration of injured skeletal muscle in rats

    NASA Astrophysics Data System (ADS)

    Yoshioka, Toshitada; Goto, Katsumasa; Kojima, Atsushi; Akema, Tatsuo; Sugiura, Takao; Ohira, Yoshinobu

    2005-08-01

    The purpose of this study was to investigate the effects of heat stress on the regeneration of injured mammalian skeletal muscles. To activate a necrosis-regeneration cycle, cardiotoxin (CTX) was injected into the left tibialis anterior (TA) muscle, except for the normal control group. Rats in the heat-stressed group were exposed to heat in a heat chamber 24 hours before or immediately after CTX injection. The muscle protein contents in the heat-stressed group were significantly higher than the non-heated group 28 days after CTX injection (p<0.05). The CTX-injection-related increment of Pax7-positive nuclei in the heated group was greater than that in the non-heated group. Evidences suggest that heat-stress could activate satellite cells, promote the proliferation and the differentiation of satellite cells, and facilitate the regeneration of muscle.

  8. On thermal stress failure of the SNAP-19A RTG heat shield

    NASA Technical Reports Server (NTRS)

    Pitts, W. C.; Anderson, L. A.

    1974-01-01

    Results of a study on thermal stress problems in an amorphous graphite heat shield that is part of the launch-abort protect system for the SNAP-19A radio-isotope thermoelectric generators (RTG) that will be used on the Viking Mars Lander are presended. The first result is from a thermal stress analysis of a full-scale RTG heat source that failed to survive a suborbital entry flight test, possibly due to thermal stress failure. It was calculated that the maximum stress in the heat shield was only 50 percent of the ultimate strength of the material. To provide information on the stress failure criterion used for this calculation, some heat shield specimens were fractured under abort entry conditions in a plasma arc facility. It was found that in regions free of stress concentrations the POCO graphite heat shield material did fracture when the local stress reached the ultimate uniaxial stress of the material.

  9. Singlet oxygen production in Chlamydomonas reinhardtii under heat stress

    PubMed Central

    Prasad, Ankush; Ferretti, Ursula; Sedlářová, Michaela; Pospíšil, Pavel

    2016-01-01

    In the current study, singlet oxygen formation by lipid peroxidation induced by heat stress (40 °C) was studied in vivo in unicellular green alga Chlamydomonas reinhardtii. Primary and secondary oxidation products of lipid peroxidation, hydroperoxide and malondialdehyde, were generated under heat stress as detected using swallow-tailed perylene derivative fluorescence monitored by confocal laser scanning microscopy and high performance liquid chromatography, respectively. Lipid peroxidation was initiated by enzymatic reaction as inhibition of lipoxygenase by catechol and caffeic acid prevented hydroperoxide formation. Ultra-weak photon emission showed formation of electronically excited species such as triplet excited carbonyl, which, upon transfer of excitation energy, leads to the formation of either singlet excited chlorophyll or singlet oxygen. Alternatively, singlet oxygen is formed by direct decomposition of hydroperoxide via Russell mechanisms. Formation of singlet oxygen was evidenced by the nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl detected by electron paramagnetic resonance spin-trapping spectroscopy and the imaging of green fluorescence of singlet oxygen sensor green detected by confocal laser scanning microscopy. Suppression of singlet oxygen formation by lipoxygenase inhibitors indicates that singlet oxygen may be formed via enzymatic lipid peroxidation initiated by lipoxygenase. PMID:26831215

  10. Heat stress induces ferroptosis-like cell death in plants.

    PubMed

    Distéfano, Ayelén Mariana; Martin, María Victoria; Córdoba, Juan Pablo; Bellido, Andrés Martín; D'Ippólito, Sebastián; Colman, Silvana Lorena; Soto, Débora; Roldán, Juan Alfredo; Bartoli, Carlos Guillermo; Zabaleta, Eduardo Julián; Fiol, Diego Fernando; Stockwell, Brent R; Dixon, Scott J; Pagnussat, Gabriela Carolina

    2017-02-01

    In plants, regulated cell death (RCD) plays critical roles during development and is essential for plant-specific responses to abiotic and biotic stresses. Ferroptosis is an iron-dependent, oxidative, nonapoptotic form of cell death recently described in animal cells. In animal cells, this process can be triggered by depletion of glutathione (GSH) and accumulation of lipid reactive oxygen species (ROS). We investigated whether a similar process could be relevant to cell death in plants. Remarkably, heat shock (HS)-induced RCD, but not reproductive or vascular development, was found to involve a ferroptosis-like cell death process. In root cells, HS triggered an iron-dependent cell death pathway that was characterized by depletion of GSH and ascorbic acid and accumulation of cytosolic and lipid ROS. These results suggest a physiological role for this lethal pathway in response to heat stress in Arabidopsis thaliana The similarity of ferroptosis in animal cells and ferroptosis-like death in plants suggests that oxidative, iron-dependent cell death programs may be evolutionarily ancient. © 2017 Distéfano et al.

  11. Heat stress induces ferroptosis-like cell death in plants

    PubMed Central

    D’Ippólito, Sebastián; Colman, Silvana Lorena; Soto, Débora; Bartoli, Carlos Guillermo; Fiol, Diego Fernando

    2017-01-01

    In plants, regulated cell death (RCD) plays critical roles during development and is essential for plant-specific responses to abiotic and biotic stresses. Ferroptosis is an iron-dependent, oxidative, nonapoptotic form of cell death recently described in animal cells. In animal cells, this process can be triggered by depletion of glutathione (GSH) and accumulation of lipid reactive oxygen species (ROS). We investigated whether a similar process could be relevant to cell death in plants. Remarkably, heat shock (HS)–induced RCD, but not reproductive or vascular development, was found to involve a ferroptosis-like cell death process. In root cells, HS triggered an iron-dependent cell death pathway that was characterized by depletion of GSH and ascorbic acid and accumulation of cytosolic and lipid ROS. These results suggest a physiological role for this lethal pathway in response to heat stress in Arabidopsis thaliana. The similarity of ferroptosis in animal cells and ferroptosis-like death in plants suggests that oxidative, iron-dependent cell death programs may be evolutionarily ancient. PMID:28100685

  12. Heat stress and a countermeasure in the Shuttle rescueman's suit

    NASA Technical Reports Server (NTRS)

    Doerr, D. F.; Reed, H.; Convertino, V. A.

    1992-01-01

    Rescue of the astronaut flight crew from a contingency landing may risk exposure of the rescue crew to toxic propellants spilling from potentially ruptured tanks in the crew module area. An Aquala dry diver's suit has been in service by the rescue team to preclude exposure, especially in the water rescue scenario. Heat stress has become a factor of concern in recent years when older and less physically-fit team members work in this suit. Methods: Field testing was initiated using fully instrumented rescue men in a simulated scenario to determine the extent of heat stress. Two tests were accomplished, one in the normal (N) configuration and one with a proposed cooling countermeasure, the Steele vest (S). Results: Heat stress was high as indicated by average rectal temperatures (Tre) of 38.28 degrees C(100.9 degrees F) after the 45 minute protocol. Slopes of the regression equations describing the increase in Tre with time were greater (P less than 0.05) with N (0.073 plus or minus .008) compared to S (0.060 plus or minus .007). Projection of time to the 38.89 degree C (102 degree F) limit was increased by 15.3 percent with the vest. Mean skin temperature (Tsk) was higher (P less than 0.05) in N (38.33 plus or minus .11 degrees C) compared to S (34.33 plus or minus .39 degrees C). Average heart rate was higher (P less than 0.05 in N than S. Sweat loss, as measured by weight loss, was more (P less than 0.05) for N (1.09 plus or minus .09 kg versus 0.77 plus or minus .06 kg). Air usage, while slightly less for S, was not statistically different. Conclusion: The use of the cool vest provided significant relief from thermal stress in spite of the addition of 3.4 kg (7.5 pounds) weight and some loss in mobility.

  13. Heat loss through the glabrous skin surfaces of heavily insulated, heat-stressed individuals.

    PubMed

    Grahn, D A; Dillon, J L; Heller, H C

    2009-07-01

    Insulation reduces heat exchange between a body and the environment. Glabrous (nonhairy) skin surfaces (palms of the hands, soles of the feet, face, and ears) constitute a small percentage of total body surface area but contain specialized vascular structures that facilitate heat loss. We have previously reported that cooling the glabrous skin surfaces is effective in alleviating heat stress and that the application of local subatmospheric pressure enhances the effect. In this paper, we compare the effects of cooling multiple glabrous skin surfaces with and without vacuum on thermal recovery in heavily insulated heat-stressed individuals. Esophageal temperatures (T(es)) and heart rates were monitored throughout the trials. Water loss was determined from pre- and post-trial nude weights. Treadmill exercise (5.6 km/h, 9-16% slope, and 25-45 min duration) in a hot environment (41.5 degrees C, 20-30% relative humidity) while wearing insulating pants and jackets was used to induce heat stress (T(es)>or=39 degrees C). For postexercise recovery, the subjects donned additional insulation (a balaclava, winter gloves, and impermeable boot covers) and rested in the hot environment for 60 min. Postexercise cooling treatments included control (no cooling) or the application of a 10 degrees C closed water circulating system to (a) the hand(s) with or without application of a local subatmospheric pressure, (b) the face, (c) the feet, or (d) multiple glabrous skin regions. Following exercise induction of heat stress in heavily insulated subjects, the rate of recovery of T(es) was 0.4+/-0.2 degrees C/h(n=12), but with application of cooling to one hand, the rate was 0.8+/-0.3 degrees C/h(n=12), and with one hand cooling with subatmospheric pressure, the rate was 1.0+/-0.2 degrees C/h(n=12). Cooling alone yielded two responses, one resembling that of cooling with subatmospheric pressure (n=8) and one resembling that of no cooling (n=4). The effect of treating multiple surfaces was

  14. Temperature stress differentially modulates transcription in meiotic anthers of heat-tolerant and heat-sensitive tomato plants

    PubMed Central

    2011-01-01

    Background Fluctuations in temperature occur naturally during plant growth and reproduction. However, in the hot summers this variation may become stressful and damaging for the molecular mechanisms involved in proper cell growth, impairing thus plant development and particularly fruit-set in many crop plants. Tolerance to such a stress can be achieved by constitutive gene expression or by rapid changes in gene expression, which ultimately leads to protection against thermal damage. We have used cDNA-AFLP and microarray analyses to compare the early response of the tomato meiotic anther transcriptome to moderate heat stress conditions (32°C) in a heat-tolerant and a heat-sensitive tomato genotype. In the light of the expected global temperature increases, elucidating such protective mechanisms and identifying candidate tolerance genes can be used to improve breeding strategies for crop tolerance to heat stress. Results The cDNA-AFLP analysis shows that 30 h of moderate heat stress (MHS) alter the expression of approximately 1% of the studied transcript-derived fragments in a heat-sensitive genotype. The major effect is gene down-regulation after the first 2 h of stress. The microarray analysis subsequently applied to elucidate early responses of a heat-tolerant and a heat-sensitive tomato genotype, also shows about 1% of the genes having significant changes in expression after the 2 h of stress. The tolerant genotype not only reacts with moderate transcriptomic changes but also exhibits constitutively higher expression levels of genes involved in protection and thermotolerance. Conclusion In contrast to the heat-sensitive genotype, the heat-tolerant genotype exhibits moderate transcriptional changes under moderate heat stress. Moreover, the heat-tolerant genotype also shows a different constitutive gene expression profile compared to the heat-sensitive genotype, indicating genetic differences in adaptation to increased temperatures. In the heat-tolerant genotype

  15. Endoplasmic Reticulum Stress in Heat- and Shake-Induced Injury in the Rat Small Intestine

    PubMed Central

    Yin, Peng; Xu, Jianqin; He, Shasha; Liu, Fenghua; Yin, Jie; Wan, Changrong; mei, Chen; Yin, Yulong; Xu, Xiaolong; Xia, Zhaofei

    2015-01-01

    We investigated the mechanisms underlying damage to rat small intestine in heat- and shake-induced stress. Eighteen Sprague-Dawley rats were randomly divided into a control group and a 3-day stressed group treated 2 h daily for 3 days on a rotary platform at 35°C and 60 r/min. Hematoxylin and eosin-stained paraffin sections of the jejunum following stress revealed shedding of the villus tip epithelial cells and lamina propria exposure. Apoptosis increased at the villus tip and extended to the basement membrane. Photomicrographs revealed that the microvilli were shorter and sparser; the nuclear envelope invaginated and gaps in the karyolemma increased; and the endoplasmic reticulum (ER) swelled significantly. Gene microarray analysis assessed 93 differentially expressed genes associated with apoptosis, ER stress, and autophagy. Relevant genes were compiled from the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Forty-one genes were involved in the regulation of apoptosis, fifteen were related to autophagy, and eleven responded to ER stress. According to KEGG, the apoptosis pathways, mitogen-activated protein kinase(MAPK) signaling pathway, the mammalian target of rapamycin (mTOR) signaling pathway, and regulation of autophagy were involved. Caspase3 (Casp3), caspase12 (Casp12), and microtubule-associate proteins 1 light chain 3(LC3) increased significantly at the villus tip while mTOR decreased; phosphorylated-AKT (P-AKT) decreased. ER stress was involved and induced autophagy and apoptosis in rat intestinal damage following heat and shake stress. Bioinformatic analysis will help determine the underlying mechanisms in stress-induced damage in the small intestine. PMID:26636675

  16. Metabolic Response to Heat Stress in Late-Pregnant and Early Lactation Dairy Cows: Implications to Liver-Muscle Crosstalk

    PubMed Central

    Eslamizad, Mehdi; Weitzel, Joachim; Kuhla, Björn

    2016-01-01

    Climate changes lead to rising temperatures during summer periods and dramatic economic losses in dairy production. Modern high-yielding dairy cows experience severe metabolic stress during the transition period between late gestation and early lactation to meet the high energy and nutrient requirements of the fetus or the mammary gland, and additional thermal stress during this time has adverse implications on metabolism and welfare. The mechanisms enabling metabolic adaptation to heat apart from the decline in feed intake and milk yield are not fully elucidated yet. To distinguish between feed intake and heat stress related effects, German Holstein dairy cows were first kept at thermoneutral conditions at 15°C followed by exposure to heat-stressed (HS) at 28°C or pair-feeding (PF) at 15°C for 6 days; in late-pregnancy and again in early lactation. Liver and muscle biopsies and plasma samples were taken to assess major metabolic pathway regulation using real-time PCR and Western Blot. The results indicate that during heat stress, late pregnant cows activate Cahill but reduce Cori cycling, prevent increase in skeletal muscle fatty acid oxidation, and utilize increased amounts of pyruvate for gluconeogenesis, without altering ureagenesis despite reduced plane of nutrition. These homeorhetic adaptations are employed to reduce endogenous heat production while diverting amino acids to the growing fetus. Metabolic adaptation to heat stress in early lactation involves increased long-chain fatty acid degradation in muscle peroxisomes, allowance for muscle glucose utilization but diminished hepatic use of amino acid-derived pyruvate for gluconeogenesis and reduced peroxisomal fatty acid oxidation and ATP production in liver of HS compared to PF cows in early lactation. Consequently, metabolic adaptation to heat stress and reduced feed intake differ between late pregnancy and early lactation of dairy cows to maintain energy supply for fetus development or milk production

  17. Testing the responses of four wheat crop models to heat stress at anthesis and grain filling.

    PubMed

    Liu, Bing; Asseng, Senthold; Liu, Leilei; Tang, Liang; Cao, Weixing; Zhu, Yan

    2016-05-01

    Higher temperatures caused by future climate change will bring more frequent heat stress events and pose an increasing risk to global wheat production. Crop models have been widely used to simulate future crop productivity but are rarely tested with observed heat stress experimental datasets. Four wheat models (DSSAT-CERES-Wheat, DSSAT-Nwheat, APSIM-Wheat, and WheatGrow) were evaluated with 4 years of environment-controlled phytotron experimental datasets with two wheat cultivars under heat stress at anthesis and grain filling stages. Heat stress at anthesis reduced observed grain numbers per unit area and individual grain size, while heat stress during grain filling mainly decreased the size of the individual grains. The observed impact of heat stress on grain filling duration, total aboveground biomass, grain yield, and grain protein concentration (GPC) varied depending on cultivar and accumulated heat stress. For every unit increase of heat degree days (HDD, degree days over 30 °C), grain filling duration was reduced by 0.30-0.60%, total aboveground biomass was reduced by 0.37-0.43%, and grain yield was reduced by 1.0-1.6%, but GPC was increased by 0.50% for cv Yangmai16 and 0.80% for cv Xumai30. The tested crop simulation models could reproduce some of the observed reductions in grain filling duration, final total aboveground biomass, and grain yield, as well as the observed increase in GPC due to heat stress. Most of the crop models tended to reproduce heat stress impacts better during grain filling than at anthesis. Some of the tested models require improvements in the response to heat stress during grain filling, but all models need improvements in simulating heat stress effects on grain set during anthesis. The observed significant genetic variability in the response of wheat to heat stress needs to be considered through cultivar parameters in future simulation studies. © 2016 John Wiley & Sons Ltd.

  18. Humid heat exposure induced oxidative stress and apoptosis in cardiomyocytes through the angiotensin II signaling pathway.

    PubMed

    Wang, Xiaowu; Yuan, Binbin; Dong, Wenpeng; Yang, Bo; Yang, Yongchao; Lin, Xi; Gong, Gu

    2015-05-01

    Exposure to humid heat stress leads to the initiation of serious physiological dysfunction that may result in heat-related diseases, including heat stroke, heat cramp, heat exhaustion, and even death. Increasing evidences have shown that the humid heat stress-induced dysfunction of the cardiovascular system was accompanied with severe cardiomyocyte injury; however, the precise mechanism of heat stress-induced injury of cardiomyocyte remains unknown. In the present study, we hypothesized that humid heat stress promoted oxidative stress through the activation of angiotensin II (Ang II) in cardiomyocytes. To test our hypothesis, we established mouse models of humid heat stress. Using the animal models, we found that Ang II levels in serum were significantly up-regulated and that the Ang II receptor AT1 was increased in cardiomyocytes. The antioxidant ability in plasma and heart tissues which was detected by the ferric reducing/antioxidant power assay was also decreased with the increased ROS production under humid heat stress, as was the expression of antioxidant genes (SOD2, HO-1, GPx). Furthermore, we demonstrated that the Ang II receptor antagonist, valsartan, effectively relieved oxidative stress, blocked Ang II signaling pathway and suppressed cardiomyocyte apoptosis induced by humid heat stress. In addition, overexpression of antioxidant genes reversed cardiomyocyte apoptosis induced by Ang II. Overall, these results implied that humid heat stress increased oxidative stress and caused apoptosis of cardiomyocytes through the Ang II signaling pathway. Thus, targeting the Ang II signaling pathway may provide a promising approach for the prevention and treatment of cardiovascular diseases caused by humid heat stress.

  19. Biochemical analysis of 'kerosene tree' Hymenaea courbaril L. under heat stress.

    PubMed

    Gupta, Dinesh; Eldakak, Moustafa; Rohila, Jai S; Basu, Chhandak

    2014-01-01

    Hymenaea courbaril or jatoba is a tropical tree known for its medically important secondary metabolites production. Considering climate change, the goal of this study was to investigate differential expression of proteins and lipids produced by this tree under heat stress conditions. Total lipid was extracted from heat stressed plant leaves and various sesquiterpenes produced by the tree under heat stress were identified. Gas chromatographic and mass spectrometric analysis were used to study lipid and volatile compounds produced by the plant. Several volatiles, isoprene, 2-methyl butanenitrile, β ocimene and a numbers of sesquiterpenes differentially produced by the plant under heat stress were identified. We propose these compounds were produced by the tree to cope up with heat stress. A protein gel electrophoresis (2-D DIGE) was performed to study differential expression of proteins in heat stressed plants. Several proteins were found to be expressed many folds different in heat stressed plants compared to the control. These proteins included heat shock proteins, histone proteins, oxygen evolving complex, and photosynthetic proteins, which, we believe, played key roles in imparting thermotolerance in Hymenaea tree. To the best of our knowledge, this is the first report of extensive molecular physiological study of Hymenaea trees under heat stress. This work will open avenues of further research on effects of heat stress in Hymenaea and the findings can be applied to understand how global warming can affect physiology of other plants.

  20. Biochemical analysis of ‘kerosene tree’ Hymenaea courbaril L. under heat stress

    PubMed Central

    Gupta, Dinesh; Eldakak, Moustafa; Rohila, Jai S; Basu, Chhandak

    2014-01-01

    Hymenaea courbaril or jatoba is a tropical tree known for its medically important secondary metabolites production. Considering climate change, the goal of this study was to investigate differential expression of proteins and lipids produced by this tree under heat stress conditions. Total lipid was extracted from heat stressed plant leaves and various sesquiterpenes produced by the tree under heat stress were identified. Gas chromatographic and mass spectrometric analysis were used to study lipid and volatile compounds produced by the plant. Several volatiles, isoprene, 2-methyl butanenitrile, β ocimene and a numbers of sesquiterpenes differentially produced by the plant under heat stress were identified. We propose these compounds were produced by the tree to cope up with heat stress. A protein gel electrophoresis (2-D DIGE) was performed to study differential expression of proteins in heat stressed plants. Several proteins were found to be expressed many folds different in heat stressed plants compared to the control. These proteins included heat shock proteins, histone proteins, oxygen evolving complex, and photosynthetic proteins, which, we believe, played key roles in imparting thermotolerance in Hymenaea tree. To the best of our knowledge, this is the first report of extensive molecular physiological study of Hymenaea trees under heat stress. This work will open avenues of further research on effects of heat stress in Hymenaea and the findings can be applied to understand how global warming can affect physiology of other plants. PMID:25482765

  1. Whole body heat stress increases motor cortical excitability and skill acquisition in humans.

    PubMed

    Littmann, Andrew E; Shields, Richard K

    2016-02-01

    Vigorous systemic exercise stimulates a cascade of molecular and cellular processes that enhance central nervous system (CNS) plasticity and performance. The influence of heat stress on CNS performance and learning is novel. We designed two experiments to determine whether passive heat stress (1) facilitated motor cortex excitability and (2) improved motor task acquisition compared to no heat stress. Motor evoked potentials (MEPs) from the first dorsal interosseus (FDI) were collected before and after 30 min of heat stress at 73 °C. A second cohort of subjects performed a motor learning task using the FDI either following heat or the no heat condition. Heat stress increased heart rate to 65% of age-predicted maximum. After heat, mean resting MEP amplitude increased 48% (p<0.05). MEP stimulus-response amplitudes did not differ according to stimulus intensity. In the second experiment, heat stress caused a significant decrease in absolute and variable error (p<0.05) during a novel movement task using the FDI. Passive environmental heat stress (1) increases motor cortical excitability, and (2) enhances performance in a motor skill acquisition task. Controlled heat stress may prime the CNS to enhance motor skill acquisition during rehabilitation. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  2. Whole body heat stress increases motor cortical excitability and skill acquisition in humans

    PubMed Central

    Littmann, Andrew E.; Shields, Richard K.

    2015-01-01

    Objective Vigorous systemic exercise stimulates a cascade of molecular and cellular processes that enhance central nervous system (CNS) plasticity and performance. The influence of heat stress on CNS performance and learning is novel. We designed two experiments to determine whether passive heat stress 1) facilitated motor cortex excitability and 2) improved motor task acquisition compared to no heat stress. Methods Motor evoked potentials (MEPs) from the first dorsal interosseus (FDI) were collected before and after 30 minutes of heat stress at 73° C. A second cohort of subjects performed a motor learning task using the FDI either following heat or the no heat condition. Results Heat stress increased heart rate to 65% of age-predicted maximum. After heat, mean resting MEP amplitude increased 48% (P < 0.05). MEP stimulus-response amplitudes did not differ according to stimulus intensity. In the second experiment, heat stress caused a significant decrease in absolute and variable error (p < 0.05) during a novel movement task using the FDI. Conclusions Passive environmental heat stress 1) increases motor cortical excitability, and 2) enhances performance in a motor skill acquisition task. Significance Controlled heat stress may prime the CNS to enhance motor skill acquisition during rehabilitation. PMID:26616546

  3. The combined effect of salt stress and heat shock on proteome profiling in Suaeda salsa.

    PubMed

    Li, Wei; Zhang, Chunyan; Lu, Qingtao; Wen, Xiaogang; Lu, Congming

    2011-10-15

    Under natural conditions or in the field, plants are often subjected to a combination of different stresses such as salt stress and heat shock. Although salt stress and heat shock have been extensively studied, little is known about how their combination affects plants. We used proteomics, coupled with physiological measurements, to investigate the effect of salt stress, heat shock, and their combination on Suaeda salsa plants. A combination of salt stress and heat shock resulted in suppression of CO(2) assimilation and the photosystem II efficiency. Approximately 440 protein spots changed their expression levels upon salt stress, heat shock and their combination, and 57 proteins were identified by MS. These proteins were classified into several categories including disease/defense, photosynthesis, energy production, material transport, and signal transduction. Some proteins induced during salt stress, e.g. choline monooxygenase, chloroplastic ATP synthase subunit beta, and V-type proton ATPase catalytic subunit A, and some proteins induced during heat shock, e.g. heat shock 70kDa protein, probable ion channel DMI1, and two component sensor histidine kinase, were either unchanged or suppressed during a combination of salt stress and heat shock. In contrast, the expression of some proteins, including nucleoside diphosphate kinase 1, chlorophyll a/b binding protein, and ABC transporter I family member 1, was specifically induced during a combination of salt stress and heat shock. The potential roles of the stress-responsive proteins are discussed.

  4. The influence of alloy composition on residual stresses in heat treated aluminium alloys

    SciTech Connect

    Robinson, J.S.; Redington, W.

    2015-07-15

    The as quenched properties of eight different heat treatable aluminium alloys are related to residual stress magnitudes with the objective being to establish if there is a relationship between the residual stress and the as quenched alloy hardness and strength. Near surface residual stresses were assessed with X-ray diffraction using both the established sin{sup 2}ψ method and the more recent cos α technique. Through thickness residual stresses were also characterised using neutron diffraction. The alloys were chosen to encompass a wide range of strengths. The low to medium strength alloys were 6060 and 6082, medium to high strength 2618A, 2014A, 7075, 7010 and two variants of 7449, while the very high strength alloy was the powder metallurgy alloy N707. To assess the as quenched strength, dynamic hardness and tensile properties were determined from samples tested immediately after quenching to minimise the influence of precipitation hardening by natural aging. In addition, hot hardness measurements were made in situ on samples cooled to simulate quench paths. Within the experimental constraints of the investigation, the distribution of residual stress through the thickness was found to follow the same pattern for all the alloys investigated, varying from tensile in the interior to surface compression. The influence of alloy strength was manifested as a change in the observed residual stress magnitudes, and surface residual stresses were found to vary linearly with as quenched hardness and strength. - Highlights: • As quenched aluminium alloys contain high magnitude residual stresses. • Surface is compressive balance by a tensile core. • As quenched surface residual stress is linear function of alloy strength. • In situ hot hardness demonstrates rapid change in intrinsic hardness during rapid cooling.

  5. Prediction of residual stress and distortion from residual stress in heat treated and machined aluminum parts

    NASA Astrophysics Data System (ADS)

    Jones, Robert

    Parts machined from relatively large thickness cross sections can experience significant deformations from high residual stresses that develop in the part during the heat treatment used to form the aluminum alloy. Uphill quenching is a process that can create a part with low residual stress and stable dimensions when the process is controlled properly. The uphill quenching process involves a solution heat treat, quench, cool to liquid nitrogen, steam blast, and then age to final temper. In this thesis two parts were modeled using ANSYS. The first part underwent the uphill quench process in the rough machined state. The second part was modeled in the stock material shape and only underwent a solution heat treat, quench, and age to final temper. After the residual stress in the second part was predicted the excess material was removed by killing the associated elements and the deformation of the final machined part was predicted. For both parts analyzed measurements were made and compared against predictions with fairly good results.

  6. 21st Century Heat Stress Projections and their Effects on US Livestock

    NASA Astrophysics Data System (ADS)

    McCabe, E.; Buzan, J. R.; Krishnan, S.; Huber, M.

    2016-12-01

    In this study we aim to determine future yield changes in the United States for livestock caused by heat stress, under the high greenhouse gas emissions scenario, representative concentration pathway 8.5 (RCP8.5). We use CMIP5 output and the Community Earth System Model Large Ensemble (CESM LENS), produced by the National Center for Atmospheric Research (NCAR). We apply the HumanIndexMod, a diagnostic heat stress package, to calculate Temperature Humidity Index for Comfort (THIC) and wet bulb temperature (Buzan et al., 2015). THIC is used to assess an animal's behavioral changes as it is subjected to discomfort. Using output from our simulations with the HumanIndexMod, we utilized the agricultural livestock model of St. Pierre et al. (2003). THIC and wet bulb temperatures are all projected by climate models to increase by the end of the century. We found that increases in THIC and heat stress are caused by both temperature and humidity increases. We show the differences for dry matter intake loss and milk loss for the Dairy Cow Model as well as other yield related variables. These variables are estimated to decrease overall production for dairy cattle, finishing hogs, poultry and various livestock. By the end of the 21st century (2071-2100), dairy cow milk production decreases by 14%, and food intake decreases by 11% compared to the beginning of the century (2005-2034). 35% less weight is gained and 19% less food is consumed by hogs the end of the century compared to the beginning of the century. We estimate and discuss resulting yield losses for the livestock industries and the implications of these losses in the United States. These results indicate that the effect of heat stress on livestock production will be highest for dairy cows, finishing hogs, and poultry.References:Buzan, J.R., K. Oleson, and M. Huber. 2015. Implementation and comparison of a suite of heat stress metrics within the Community Land Model version 4.5. Geoscien. Model Devel. 8(2): 151-170. St

  7. Assessment of cold stress in outdoor work.

    PubMed

    Anttonen, H; Virokannas, H

    1994-01-01

    The evaluation of cold stress in working life was done in 13, mainly outdoor, occupations and 143 workers using local temperatures, body cooling and thermal sensations. The subjects in the study were young, healthy men and they wore the type of winter clothing generally used in those ambient temperatures (+6...-29 degrees C), for in a work load of from 112 to 480 W. Local temperatures on finger skin indicated that manual dexterity was often reduced in outdoor work. A risk of frostbite was frequently found on the cheek and the wind chill index predicted the risk quite well. Body cooling was often temporarily too high when measured by heat debt and mean skin temperature. Thermal sensations were cool or cold occasionally in 28% of the workers interviewed. The insulation of clothing worn was often lower than the IREQmin-value recommends. The results showed that in outdoor work in winter time cold stress frequently reduced (70%) working ability at least for a short period. Mean skin temperature seems to be, in practice, a useful indicator for body cooling and the IREQmin-value was suitable, especially in light work, to indicate body cooling. A very sensitive factor for the expression of cold stress was finger temperature, at least as an indicator of finger dexterity. Due to the adverse health effects found the cold stress should also be evaluated more systematically in occupational health and safety with health examinations, with protective clothing and technical preventive means.

  8. Impact of heat stress, nutritional restriction and combined stresses (heat and nutritional) on growth and reproductive performance of Malpura rams under semi-arid tropical environment.

    PubMed

    Maurya, V P; Sejian, V; Kumar, D; Naqvi, S M K

    2016-10-01

    A study was conducted to assess the combined effect of heat stress and nutritional restriction on growth and reproductive performances in Malpura rams. Twenty-eight adult Malpura rams (average body weight (BW) 66.0 kg) were used in this study. The rams were divided into four groups: CON (n = 7; control), HES (n = 7; heat stress), NUS (n = 7; nutritional stress) and COS (n = 7; combined stress). The study was conducted for a period of 2 months. CON and HES rams had ad libitum access to their feed while NUS and COS rams were under restricted feed (30% intake of CON rams) to induce nutritional stress. The HES and COS rams were kept in climatic chamber at 42 °C and 55% relative humidity for 6 h a day between 10 : 00 h and 16 : 00 h to induce heat stress. Body weight increased significantly (p < 0.05) in CON as compared to NUS and COS. When compared within groups, scrotal width morning, scrotal width afternoon, scrotal circumference morning and scrotal circumference afternoon were significantly (p < 0.05) larger in CON while smaller in COS rams. The higher testicular length was recorded both during morning (p < 0.05) and afternoon (p < 0.01) in COS rams while the lowest in NUS rams. The highest plasma testosterone concentration was recorded in CON and lowest in COS rams. Semen volume and mass motility also differed significantly (p < 0.05) between the groups. The highest semen volume and mass motility was recorded in CON and NUS while lowest in both HES and COS rams. It can be concluded from this study that when two stressors occur simultaneously, they may have severe impact on reproductive performance of rams. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

  9. Comparison of heat dissipation response between Malaysian and Japanese males during exercise in humid heat stress.

    PubMed

    Wakabayashi, Hitoshi; Wijayanto, Titis; Lee, Joo-Young; Hashiguchi, Nobuko; Saat, Mohamed; Tochihara, Yutaka

    2011-07-01

    This study investigated the differences in heat dissipation response to intense heat stress during exercise in hot and humid environments between tropical and temperate indigenes with matched physical characteristics. Ten Japanese (JP) and ten Malaysian (MY) males participated in this study. Subjects performed exercise for 60 min at 55% peak oxygen uptake in 32°C air with 70% relative humidity, followed by 30 min recovery. The increase in rectal temperature (T(re)) was smaller in MY during exercise compared to JP. The local sweat rate and total body mass loss were similar in both groups. Both skin blood flow and mean skin temperature was lower in MY compared to JP. A significantly greater increase in hand skin temperature was observed in MY during exercise, which is attributable to heat loss due to the greater surface area to mass ratio and large number of arteriovenous anastomoses. Also, the smaller increase in T(re) in MY may be explained by the presence of a significantly greater core-skin temperature gradient in MY than JP. The thermal gradient is also a major factor in increasing the convective heat transfer from core to skin as well as skin blood flow. It is concluded that the greater core-skin temperature gradient observed in MY is responsible for the smaller increase in T(re).

  10. Comparison of heat dissipation response between Malaysian and Japanese males during exercise in humid heat stress

    NASA Astrophysics Data System (ADS)

    Wakabayashi, Hitoshi; Wijayanto, Titis; Lee, Joo-Young; Hashiguchi, Nobuko; Saat, Mohamed; Tochihara, Yutaka

    2011-07-01

    This study investigated the differences in heat dissipation response to intense heat stress during exercise in hot and humid environments between tropical and temperate indigenes with matched physical characteristics. Ten Japanese (JP) and ten Malaysian (MY) males participated in this study. Subjects performed exercise for 60 min at 55% peak oxygen uptake in 32°C air with 70% relative humidity, followed by 30 min recovery. The increase in rectal temperature ( T re) was smaller in MY during exercise compared to JP. The local sweat rate and total body mass loss were similar in both groups. Both skin blood flow and mean skin temperature was lower in MY compared to JP. A significantly greater increase in hand skin temperature was observed in MY during exercise, which is attributable to heat loss due to the greater surface area to mass ratio and large number of arteriovenous anastomoses. Also, the smaller increase in T re in MY may be explained by the presence of a significantly greater core-skin temperature gradient in MY than JP. The thermal gradient is also a major factor in increasing the convective heat transfer from core to skin as well as skin blood flow. It is concluded that the greater core-skin temperature gradient observed in MY is responsible for the smaller increase in T re.

  11. Transcriptomic analysis of grape (Vitis vinifera L.) leaves during and after recovery from heat stress

    PubMed Central

    2012-01-01

    Background Grapes are a major fruit crop around the world. Heat stress can significantly reduce grape yield and quality. Changes at the molecular level in response to heat stress and subsequent recovery are poorly understood. To elucidate the effect of heat stress and subsequent recovery on expression of genes by grape leaves representing the classic heat stress response and thermotolerance mechanisms, transcript abundance of grape (Vitis vinifera L.) leaves was quantified using the Affymetrix Grape Genome oligonucleotide microarray (15,700 transcripts), followed by quantitative Real-Time PCR validation for some transcript profiles. Results We found that about 8% of the total probe sets were responsive to heat stress and/or to subsequent recovery in grape leaves. The heat stress and recovery responses were characterized by different transcriptional changes. The number of heat stress-regulated genes was almost twice the number of recovery-regulated genes. The responsive genes identified in this study belong to a large number of important traits and biological pathways, including cell rescue (i.e., antioxidant enzymes), protein fate (i.e., HSPs), primary and secondary metabolism, transcription factors, signal transduction, and development. We have identified some common genes and heat shock factors (HSFs) that were modulated differentially by heat stress and recovery. Most HSP genes were upregulated by heat stress but were downregulated by the recovery. On the other hand, some specific HSP genes or HSFs were uniquely responsive to heat stress or recovery. Conclusion The effect of heat stress and recovery on grape appears to be associated with multiple processes and mechanisms including stress-related genes, transcription factors, and metabolism. Heat stress and recovery elicited common up- or downregulated genes as well as unique sets of responsive genes. Moreover, some genes were regulated in opposite directions by heat stress and recovery. The results indicated

  12. Transcriptomic analysis of grape (Vitis vinifera L.) leaves during and after recovery from heat stress.

    PubMed

    Liu, Guo-Tian; Wang, Jun-Fang; Cramer, Grant; Dai, Zhan-Wu; Duan, Wei; Xu, Hong-Guo; Wu, Ben-Hong; Fan, Pei-Ge; Wang, Li-Jun; Li, Shao-Hua

    2012-09-28

    Grapes are a major fruit crop around the world. Heat stress can significantly reduce grape yield and quality. Changes at the molecular level in response to heat stress and subsequent recovery are poorly understood. To elucidate the effect of heat stress and subsequent recovery on expression of genes by grape leaves representing the classic heat stress response and thermotolerance mechanisms, transcript abundance of grape (Vitis vinifera L.) leaves was quantified using the Affymetrix Grape Genome oligonucleotide microarray (15,700 transcripts), followed by quantitative Real-Time PCR validation for some transcript profiles. We found that about 8% of the total probe sets were responsive to heat stress and/or to subsequent recovery in grape leaves. The heat stress and recovery responses were characterized by different transcriptional changes. The number of heat stress-regulated genes was almost twice the number of recovery-regulated genes. The responsive genes identified in this study belong to a large number of important traits and biological pathways, including cell rescue (i.e., antioxidant enzymes), protein fate (i.e., HSPs), primary and secondary metabolism, transcription factors, signal transduction, and development. We have identified some common genes and heat shock factors (HSFs) that were modulated differentially by heat stress and recovery. Most HSP genes were upregulated by heat stress but were downregulated by the recovery. On the other hand, some specific HSP genes or HSFs were uniquely responsive to heat stress or recovery. The effect of heat stress and recovery on grape appears to be associated with multiple processes and mechanisms including stress-related genes, transcription factors, and metabolism. Heat stress and recovery elicited common up- or downregulated genes as well as unique sets of responsive genes. Moreover, some genes were regulated in opposite directions by heat stress and recovery. The results indicated HSPs, especially small HSPs

  13. The influence of occupational heat exposure on cognitive performance and blood level of stress hormones: a field study report.

    PubMed

    Mazlomi, Adel; Golbabaei, Farideh; Farhang Dehghan, Somayeh; Abbasinia, Marzieh; Mahmoud Khani, Somayeh; Ansari, Mohammad; Hosseini, Mostafa

    2017-09-01

    This article aimed to investigate the effect of heat stress on cognitive performance and the blood concentration of stress hormones among workers of a foundry plant. Seventy workers within the exposed (35 people) and unexposed (35 people) groups were studied. The wet bulb globe temperature (WBGT) index was measured for heat stress assessment. The cognitive performance tests were conducted using the Stroop color word test (SCWT) before and during working hours. For the assessment of the serum level of cortisol and the plasma level of adrenaline and noradrenaline, blood samples were taken during working hours from both groups. Only for SCWT III was there a significant relationship between heat stress and test duration, error rate and reaction time. The laboratory test results revealed significantly higher concentrations of cortisol, adrenaline and noradrenaline in the exposed subjects than in the unexposed group. There existed a positive correlation between cortisol, adrenaline, noradrenaline and WBGT index and also test duration and reaction time of SCWT III, and number of errors of SCWT I, SCWT II and SCWT III during work. Heat stress can lead to an increase in the blood level of stress hormones, resulting in cognitive performance impairment.

  14. Transcriptional profiling of Arabidopsis heat shock proteins and transcription factors reveals extensive overlap between heat and non-heat stress response pathways

    PubMed Central

    Swindell, William R; Huebner, Marianne; Weber, Andreas P

    2007-01-01

    Background The heat shock response of Arabidopsis thaliana is dependent upon a complex regulatory network involving twenty-one known transcription factors and four heat shock protein families. It is known that heat shock proteins (Hsps) and transcription factors (Hsfs) are involved in cellular response to various forms of stress besides heat. However, the role of Hsps and Hsfs under cold and non-thermal stress conditions is not well understood, and it is unclear which types of stress interact least and most strongly with Hsp and Hsf response pathways. To address this issue, we have analyzed transcriptional response profiles of Arabidopsis Hsfs and Hsps to a range of abiotic and biotic stress treatments (heat, cold, osmotic stress, salt, drought, genotoxic stress, ultraviolet light, oxidative stress, wounding, and pathogen infection) in both above and below-ground plant tissues. Results All stress treatments interact with Hsf and Hsp response pathways to varying extents, suggesting considerable cross-talk between heat and non-heat stress regulatory networks. In general, Hsf and Hsp expression was strongly induced by heat, cold, salt, and osmotic stress, while other types of stress exhibited family or tissue-specific response patterns. With respect to the Hsp20 protein family, for instance, large expression responses occurred under all types of stress, with striking similarity among expression response profiles. Several genes belonging to the Hsp20, Hsp70 and Hsp100 families were specifically upregulated twelve hours after wounding in root tissue, and exhibited a parallel expression response pattern during recovery from heat stress. Among all Hsf and Hsp families, large expression responses occurred under ultraviolet-B light stress in aerial tissue (shoots) but not subterranean tissue (roots). Conclusion Our findings show that Hsf and Hsp family member genes represent an interaction point between multiple stress response pathways, and therefore warrant functional

  15. Stress and Heat Transfer Analyses for Different Channel Arrangements of PCHE

    SciTech Connect

    Jong B. Lim; Robert G. Shrake; Eung S. Kim; Chang H. Oh

    2008-11-01

    Stress and heat transfer analyses are being performed on the different channel arrangements of Printed Circuit Heat Exchanger (PCHE) proposed for application of VHTRs using ABAQUS [ABAQUS, 2007] and COMSOL [COMSOL, 2007], respectively. The work is being done to determine the configuration that would result in minimum stress for the same heat performance. This paper discusses the effects of shifting the coolant channels in every other row to reduce stress.

  16. Metabolic adaptations to heat stress in growing cattle.

    PubMed

    O'Brien, M D; Rhoads, R P; Sanders, S R; Duff, G C; Baumgard, L H

    2010-02-01

    To differentiate between the effects of heat stress (HS) and decreased dry matter intake (DMI) on physiological and metabolic variables in growing beef cattle, we conducted an experiment in which a thermoneutral (TN) control group (n=6) was pair fed (PF) to match nutrient intake with heat-stressed Holstein bull calves (n=6). Bulls (4 to 5 mo old, 135 kg body weight [BW]) housed in climate-controlled chambers were subjected to 2 experimental periods (P): (1) TN (18 degrees C to 20 degrees C) and ad libitum intake for 9 d, and (2) HS (cyclical daily temperatures ranging from 29.4 degrees C to 40.0 degrees C) and ad libitum intake or PF (in TN conditions) for 9 d. During each period, blood was collected daily and all calves were subjected to an intravenous insulin tolerance test (ITT) on day 7 and a glucose tolerance test (GTT) on day 8. Heat stress reduced (12%) DMI and by design, PF calves had similar nutrient intake reductions. During P1, BW gain was similar between environments and averaged 1.25 kg/d, and both HS and PF reduced (P<0.01) average daily gain (-0.09 kg/d) during P2. Compared to PF, HS decreased (P<0.05) basal circulating glucose concentrations (7%) and tended (P<0.07) to increase (30%) plasma insulin concentrations, but neither HS nor PF altered plasma nonesterified fatty acid concentrations. Although there were no treatment differences in P2, both HS and PF increased (P<0.05) plasma urea nitrogen concentrations (75%) compared with P1. In contrast to P1, both HS and PF had increased (16%) glucose disposal, but compared with PF, HS calves had a greater (67%; P<0.05) insulin response to the GTT. Neither period nor environment acutely affected insulin action, but during P2, calves in both environments tended (P=0.11) to have a blunted overall glucose response to the ITT. Independent of reduced nutrient intake, HS alters post-absorptive carbohydrate (basal and stimulated) metabolism, characterized primarily by increased basal insulin concentrations and

  17. Genital heat stress in men of barren couples: a prospective evaluation by means of a questionnaire.

    PubMed

    Jung, A; Schill, W-B; Schuppe, H-C

    2002-12-01

    Exposure to genital heat stress among men of barren couples was evaluated in a prospective study. Five hundred and forty-two consecutive patients referred for andrological examination were asked to complete a specific questionnaire at their first visit. For 449 patients who answered all questions, the individual score values could be calculated by scoring each answer with points. Patients with 'idiopathic' oligoasthenoteratozoospermia had significantly higher score values when compared with men showing normozoospermia (P < 0.01), 'symptomatic' oligoasthenoteratozoospermia as a result of defined andrological disorders (P < 0.01), cryptozoospermia (P < 0.01) or other pathological semen profiles (P < 0.05). These data support the hypothesis that patients with 'idiopathic' oligoasthenoteratozoospermia are more exposed to genital heat stress than normozoospermic men. Moreover, in patients with a varicocele impairment semen quality was associated with significantly higher score values compared with the subgroup of men with normal semen profiles (P < 0.05). In contrast, the score values did not significantly differ between equivalent subgroups of men with a history of a retractile testis. Our observations indicate that the questionnaire used in the present study allows an integrative assessment of genital heat stress, which is superior to single factor analysis. Notably, the group of men with 'idiopathic' oligoasthenoteratozoospermia showed the highest mean score values for 10 of the 18 questions compared with the other groups. Prolonged sitting in a vehicle represented the only single factor with significantly different score values in patients with 'idiopathic' oligoasthenoteratozoospermia and those with normozoospermia (P < 0.05).

  18. Regulation of Non-coding RNAs in Heat Stress Responses of Plants

    PubMed Central

    Zhao, Jianguo; He, Qingsong; Chen, Gang; Wang, Li; Jin, Biao

    2016-01-01

    Heat stress is an important factor limiting plant growth, development, and productivity; thus, plants have evolved special adaptive mechanisms to cope with high-temperature stress. Non-coding RNAs (ncRNAs) are a class of regulatory RNAs that play an important role in many biological processes. Recently developed advanced technologies, such as genome-wide transcriptomic analysis, have revealed that abundant ncRNAs are expressed under heat stress. Although this area of research is still in its infancy, an increasing number of several classes of regulatory ncRNA (i.e., miRNA, siRNA, and lncRNA) related to heat stress responses have been reported. In this mini-review, we discuss our current understanding of the role of ncRNAs in heat stress responses in plants, especially miRNAs, siRNAs, and their targets. For example, the miR398-CSD/CCS-HSF, miR396-WRKY6, miR159-GAMYB, and TAS1-HTT-HSF pathways regulate plant heat tolerance. We highlight the hormone/development-related miRNAs involved in heat stress, and discuss the regulatory networks of miRNA-targets. We also note that DNA methylation and alternative splicing could affect miRNA expression under heat stress, and some lncRNAs could respond to heat stress. Finally, we briefly discuss future prospects concerning the ncRNA-related mechanisms of heat stress responses in plants. PMID:27588021

  19. Dietary supplementation of Zingiber officinale and Zingiber zerumbet to heat-stressed broiler chickens and its effect on heat shock protein 70 expression, blood parameters and body temperature.

    PubMed

    Hasheimi, S R; Zulkifli, I; Somchit, M N; Zunita, Z; Loh, T C; Soleimani, A F; Tang, S C

    2013-08-01

    The present study was conducted to assess the effects of dietary supplementation of Zingiber officinale and Zingiber zerumbet and to heat-stressed broiler chickens on heat shock protein (HSP) 70 density, plasma corticosterone concentration (CORT), heterophil to lymphocyte ratio (HLR) and body temperature. Beginning from day 28, chicks were divided into five dietary groups: (i) basal diet (control), (ii) basal diet +1%Z. zerumbet powder (ZZ1%), (iii) basal diet +2%Z. zerumbet powder (ZZ2%), (iv) basal diet +1%Z. officinale powder (ZO1%) and (v) basal diet +2%Z. officinale powder (ZO2%). From day 35-42, heat stress was induced by exposing birds to 38±1°C and 80% RH for 2 h/day. Irrespective of diet, heat challenge elevated HSP70 expression, CORT and HLR on day 42. On day 42, following heat challenge, the ZZ1% birds showed lower body temperatures than those of control, ZO1% and ZO2%. Neither CORT nor HLR was significantly affected by diet. The ZO2% and ZZ2% diets enhanced HSP70 expression when compared to the control groups. We concluded that dietary supplementation of Z. officinale and Z. zerumbet powder may induce HSP70 reaction in broiler chickens exposed to heat stress.

  20. ROLE OF ENVIRONMENTAL HEAT AND COLD STRESS ON THE PHYSIOLOGICAL RESPONSE TO ORGANOPHOSPHATES AND OTHER TOXICANTS.

    EPA Science Inventory

    Most toxicological and pharmacological studies are performed in laboratory rodents maintained under comfortable environmental conditions. However, exposure to toxicants as well as some drugs can occur under stressful conditions during rest or while exercising. Heat stress can exa...

  1. ROLE OF ENVIRONMENTAL HEAT AND COLD STRESS ON THE PHYSIOLOGICAL RESPONSE TO ORGANOPHOSPHATES AND OTHER TOXICANTS.

    EPA Science Inventory

    Most toxicological and pharmacological studies are performed in laboratory rodents maintained under comfortable environmental conditions. However, exposure to toxicants as well as some drugs can occur under stressful conditions during rest or while exercising. Heat stress can exa...

  2. Estimating heat stress from climate-based indicators: present-day biases and future spreads in the CMIP5 global climate model ensemble

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Ducharne, A.; Sultan, B.; Braconnot, P.; Vautard, R.

    2015-08-01

    The increased exposure of human populations to heat stress is one of the likely consequences of global warming, and it has detrimental effects on health and labor capacity. Here, we consider the evolution of heat stress under climate change using 21 general circulation models (GCMs). Three heat stress indicators, based on both temperature and humidity conditions, are used to investigate present-day model biases and spreads in future climate projections. Present day estimates of heat stress indicators from observational data shows that humid tropical areas tend to experience more frequent heat stress than other regions do, with a total frequency of heat stress 250-300 d yr-1. The most severe heat stress is found in the Sahel and south India. Present-day GCM simulations tend to underestimate heat stress over the tropics due to dry and cold model biases. The model based estimates are in better agreement with observation in mid to high latitudes, but this is due to compensating errors in humidity and temperature. The severity of heat stress is projected to increase by the end of the century under climate change scenario RCP8.5, reaching unprecedented levels in some regions compared with observations. An analysis of the different factors contributing to the total spread of projected heat stress shows that spread is primarily driven by the choice of GCMs rather than the choice of indicators, even when the simulated indicators are bias-corrected. This supports the utility of the multi-model ensemble approach to assess the impacts of climate change on heat stress.

  3. Intervention to reduce heat stress and improve efficiency among sugarcane workers in El Salvador: Phase 1

    PubMed Central

    Bodin, T; García-Trabanino, R; Weiss, I; Jarquín, E; Glaser, J; Jakobsson, K; Lucas, R A I; Wesseling, C; Hogstedt, C; Wegman, D H

    2016-01-01

    Background Chronic heat stress and dehydration from strenuous work in hot environments is considered an essential component of the epidemic of chronic kidney disease in Central America. Objective (1) To assess feasibility of providing an intervention modelled on OSHA's Water.Rest.Shade programme (WRS) during sugarcane cutting and (2) to prevent heat stress and dehydration without decreasing productivity. Methods Midway through the 6-month harvest, the intervention introduced WRS practices. A 60-person cutting group was provided water supplied in individual backpacks, mobile shaded rest areas and scheduled rest periods. Ergonomically improved machetes and efficiency strategies were also implemented. Health data (anthropometric, blood, urine, questionnaires) were collected preharvest, preintervention, mid-intervention and at the end of harvest. A subsample participated in focus group discussions. Daily wet bulb globe temperatures (WBGT) were recorded. The employer provided individual production records. Results Over the harvest WBGT was >26°C from 9:00 onwards reaching average maximum of 29.3±1.7°C, around 13:00. Postintervention self-reported water consumption increased 25%. Symptoms associated with heat stress and with dehydration decreased. Individual daily production increased from 5.1 to a high of 7.3 tons/person/day postintervention. This increase was greater than in other cutting groups at the company. Focus groups reported a positive perception of components of the WRS, and the new machete and cutting programmes. Conclusions A WRS intervention is feasible in sugarcane fields, and appears to markedly reduce the impact of the heat stress conditions for the workforce. With proper attention to work practices, production can be maintained with less impact on worker health. PMID:27073211

  4. Intervention to reduce heat stress and improve efficiency among sugarcane workers in El Salvador: Phase 1.

    PubMed

    Bodin, T; García-Trabanino, R; Weiss, I; Jarquín, E; Glaser, J; Jakobsson, K; Lucas, R A I; Wesseling, C; Hogstedt, C; Wegman, D H

    2016-06-01

    Chronic heat stress and dehydration from strenuous work in hot environments is considered an essential component of the epidemic of chronic kidney disease in Central America. (1) To assess feasibility of providing an intervention modelled on OSHA's Water.Rest.Shade programme (WRS) during sugarcane cutting and (2) to prevent heat stress and dehydration without decreasing productivity. Midway through the 6-month harvest, the intervention introduced WRS practices. A 60-person cutting group was provided water supplied in individual backpacks, mobile shaded rest areas and scheduled rest periods. Ergonomically improved machetes and efficiency strategies were also implemented. Health data (anthropometric, blood, urine, questionnaires) were collected preharvest, preintervention, mid-intervention and at the end of harvest. A subsample participated in focus group discussions. Daily wet bulb globe temperatures (WBGT) were recorded. The employer provided individual production records. Over the harvest WBGT was >26°C from 9:00 onwards reaching average maximum of 29.3±1.7°C, around 13:00. Postintervention self-reported water consumption increased 25%. Symptoms associated with heat stress and with dehydration decreased. Individual daily production increased from 5.1 to a high of 7.3 tons/person/day postintervention. This increase was greater than in other cutting groups at the company. Focus groups reported a positive perception of components of the WRS, and the new machete and cutting programmes. A WRS intervention is feasible in sugarcane fields, and appears to markedly reduce the impact of the heat stress conditions for the workforce. With proper attention to work practices, production can be maintained with less impact on worker health. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  5. The relationship between yield and the antioxidant defense system in tomatoes grown under heat stress.

    PubMed

    Rainwater, D T; Gossett, D R; Millhollon, E P; Hanna, H Y; Banks, S W; Lucas, M C

    1996-11-01

    Four putative heat-tolerant tomato (Lycopersicum esculentum) cultivars (Tamasabro, Heat Wave, LHT-24, and Solar Set) and one putative heat-sensitive tomato cultivar (Floradade) were grown in the field under non-stress (average daily temperature of 26 degrees C) and heat-stress (average daily temperature of 34 degrees C) conditions. At anthesis, approximately five weeks after being transplanted to the field, leaf samples were collected for antioxidant analyses. Yield was determined by harvesting ripe fruit seven weeks after the collection of leaf samples. Heat stress resulted in a 79.1% decrease in yield for the heat-sensitive Floradade, while the fruit yield in the heat-tolerant cultivars Heat Wave, LHT-24, Solar Set, and Tamasabro was reduced 51.5%, 22.1%, 43.8%, and 34.8% respectively. When grown under heat stress, antioxidant activities were also greater in the heat-tolerant cultivars. Superoxide dismutase (SOD) activity increased up to 9-fold in the heat-tolerant cultivars but decreased 83.1% in the heat-sensitive Floradade. Catalase, peroxidase, and ascorbate peroxidase activity increased significantly in all cultivars. Only Heat Wave showed a significant increase in glutathione reductase in response to heat stress but all heat-tolerant cultivars exhibited significantly lower oxidized ascorbate/reduced ascorbate ratios, greater reduced glutathione/oxidized glutathione rations, and greater alpha-tocopherol concentrations compared to the heat-sensitive cultivar Floridade. These data indicate that the more heat-tolerant cultivars had an enhanced capacity for scavenging active oxygen species and a more active ascorbate-glutathione cycle and suggest a strong correlation between the ability to up-regulate the antioxidant defense system and the ability of tomatoes to produce greater yields when grown under heat stress.

  6. Impact of Heat Stress on Cellular and Transcriptional Adaptation of Mammary Epithelial Cells in Riverine Buffalo (Bubalus Bubalis)

    PubMed Central

    Kapila, Neha; Sharma, Ankita; Kishore, Amit; Sodhi, Monika; Tripathi, Pawan K.; Mohanty, Ashok K.

    2016-01-01

    The present study aims to identify the heat responsive genes and biological pathways in heat stressed buffalo mammary epithelial cells (MECs). The primary mammary epithelial cells of riverine buffalo were exposed to thermal stress at 42°C for one hour. The cells were subsequently allowed to recover at 37°C and harvested at different time intervals (30 min to 48 h) along with control samples (un-stressed). In order to assess the impact of heat stress in buffalo MECs, several in-vitro cellular parameters (lactate dehydrogenase activity, cell proliferation assay, cellular viability, cell death and apoptosis) and transcriptional studies were conducted. The heat stress resulted in overall decrease in cell viability and cell proliferation of MECs while induction of cellular apoptosis and necrosis. The transcriptomic profile of heat stressed MECs was generated using Agilent 44 K bovine oligonucleotide array and at cutoff criteria of ≥3-or ≤3 fold change, a total of 153 genes were observed to be upregulated while 8 genes were down regulated across all time points post heat stress. The genes that were specifically up-regulated or down-regulated were identified as heat responsive genes. The upregulated genes in heat stressed MECs belonged to heat shock family viz., HSPA6, HSPB8, DNAJB2, HSPA1A. Along with HSPs, genes like BOLA, MRPL55, PFKFB3, PSMC2, ENDODD1, ARID5A, and SENP3 were also upregulated. Microarray data revealed that the heat responsive genes belonged to different functional classes viz., chaperons; immune responsive; cell proliferation and metabolism related. Gene ontology analysis revealed enrichment of several biological processes like; cellular process, metabolic process, response to stimulus, biological regulation, immune system processes and signaling. The transcriptome analysis data was further validated by RT-qPCR studies. Several HSP (HSP40, HSP60, HSP70, HSP90, and HSPB1), apoptotic (Bax and Bcl2), immune (IL6, TNFα and NF-kβ) and oxidative

  7. Heat stress dictates microbial lipid composition in hydrothermal marine sediments

    NASA Astrophysics Data System (ADS)

    Sollich, M.; Yoshinaga, M. Y.; Häusler, S.; Hinrichs, K. U.; Bühring, S. I.

    2016-02-01

    Abundant and diverse microbial communities inhabit hydrothermal marine sediments. Since ion permeability of membranes increases with temperature archaea and bacteria that use proton/sodium as coupling ions for bioenergetics must constantly adjust their cytoplasmic membrane permeability, which in turn is mostly controlled by the lipid composition. Here, we investigated a thermal gradient across a marine sediment field (ranging from 18 to over 100°C) and tested the concept that membrane lipids provide a major biochemical basis for cellular bioenergetics of archaea and bacteria under stressful conditions. Reflecting the lower ion permeability of the ether-linked isoprenoidal lipids, we found that archaea dominate over bacteria in sediments of >50 °C. Moreover, a detailed examination of the molecular lipid species revealed a quandary: low membrane permeability concomitantly with increased fluidity is required for energy conservation of both archaea and bacteria under heat stress. For instance, bacterial fatty acids were found to increase chain length in concert with a higher degree of unsaturation at elevated sediment temperatures while archaeal tetraethers were observed to show a higher degree of bulking (e.g. methylation and H-shaped) and fluidity (i.e. cyclization) under elevated temperatures. In addition, our data indicate that strong intermolecular hydrogen bonding at the headgroup level of archaeal glycolipids and bacterial sphingolipids may provide ideal membrane stability to attain the required balance between low permeability and a more fluidized configuration. For example, sphingolipids may stabilize bacterial phospholipids into lipid domains, enabling bacteria to thrive in heated sediments under unfavorable thermodynamic conditions. The scientific marriage of lipidomics and bioenergetics described here provides a new dimension for understanding microbial life in natural environments.

  8. Climate Change Impact on Evapotranspiration, Heat Stress and Chill Requirements

    NASA Astrophysics Data System (ADS)

    Snyder, R. L.; Marras, S.; Spano, D.

    2013-12-01

    Carbon dioxide concentration scenarios project an increase in CO2 from 372 ppm to between 500 and 950 ppm by the year 2100, and the potential effect on temperature, humidity, and plant responses to environmental factors are complex and concerning. For 2100, mean daily temperature increase projections range from 1.2oC to 6.8oC depending on greenhouse gas emissions. On the bad side, higher temperatures are often associated with increases in evapotranspiration (ET), heat stress, and pest infestations. On the good side, increased temperature is commonly related to less frost damage, faster growth, and higher production in some cases. One misconception is that global warming will increase evapotranspiration and, hence, agricultural water demand. As the oceans and other water bodies warm, evaporation and humidity are likely to increase globally, but higher humidity tends to reduce plant transpiration and hence ET. Higher CO2 concentrations also tend to reduce ET, and, in the end, the increase in ET due to higher temperature is likely to be offset by a decrease in ET due to higher humidity and CO2. With a decrease in daytime evapotranspiration, the canopy temperature is likely to rise relative to the air temperature, and this implies that heat stress could be worse than predicted by increased air temperature. Daily minimum temperatures are generally increasing about twice as fast as maximum temperatures presumably because of the increasing dew point temperatures as more water vapor is added to the atmosphere. This could present a serious problem to meet the chill requirement for fruit and nut crops. Growing seasons, i.e., from the last spring to the first fall frost, are likely to increase, but the crop growth period is likely to shorten due to higher temperature. Thus, spring frost damage is unlikely to change but there should be fewer damaging fall frost events. In this paper, we will present some ideas on the possible impact of climate change on evapotranspiration and

  9. Uncoupling Stress-Inducible Phosphorylation of Heat Shock Factor 1 from Its Activation

    PubMed Central

    Budzyński, Marek A.; Puustinen, Mikael C.; Joutsen, Jenny

    2015-01-01

    In mammals the stress-inducible expression of genes encoding heat shock proteins is under the control of the heat shock transcription factor 1 (HSF1). Activation of HSF1 is a multistep process, involving trimerization, acquisition of DNA-binding and transcriptional activities, which coincide with several posttranslational modifications. Stress-inducible phosphorylation of HSF1, or hyperphosphorylation, which occurs mainly within the regulatory domain (RD), has been proposed as a requirement for HSF-driven transcription and is widely used for assessing HSF1 activation. Nonetheless, the contribution of hyperphosphorylation to the activity of HSF1 remains unknown. In this study, we generated a phosphorylation-deficient HSF1 mutant (HSF1Δ∼PRD), where the 15 known phosphorylation sites within the RD were disrupted. Our results show that the phosphorylation status of the RD does not affect the subcellular localization and DNA-binding activity of HSF1. Surprisingly, under stress conditions, HSF1Δ∼PRD is a potent transactivator of both endogenous targets and a reporter gene, and HSF1Δ∼PRD has a reduced activation threshold. Our results provide the first direct evidence for uncoupling stress-inducible phosphorylation of HSF1 from its activation, and we propose that the phosphorylation signature alone is not an appropriate marker for HSF1 activity. PMID:25963659

  10. Ability to Discriminate Between Sustainable and Unsustainable Heat Stress Exposures-Part 1: WBGT Exposure Limits.

    PubMed

    Garzón-Villalba, Ximena P; Wu, Yougui; Ashley, Candi D; Bernard, Thomas E

    2017-06-08

    Heat stress exposure limits based on wet-bulb globe temperature (WBGT) were designed to limit exposures to those that could be sustained for an 8-h day using limited data from Lind in the 1960s. In general, Sustainable exposures are heat stress levels at which thermal equilibrium can be achieved, and Unsustainable exposures occur when there is a steady increase in core temperature. This paper addresses the ability of the ACGIH® Threshold Limit Value (TLV®) to differentiate between Sustainable and Unsustainable heat exposures, to propose alternative occupational exposure limits, and ask whether an adjustment for body surface area improves the exposure decision. Two progressive heat stress studies provided data on 176 trials with 352 pairs of Sustainable and Unsustainable exposures over a range of relative humidities and metabolic rates using 29 participants wearing woven cotton clothing. To assess the discrimination ability of the TLV, the exposure metric was the difference between the observed WBGT and the TLV adjusted for metabolic rate. Conditional logistic regression models and receiver operating characteristic curves (ROC) along with ROC's area under the curve (AUC) were used. Four alternative models for an occupational exposure limit were also developed and compared to the TLV. For the TLV, the odds ratio (OR) for Unsustainable was 2.5 per 1°C-WBGT [confidence interval (CI) 2.12-2.88]. The AUC for the TLV was 0.85 (CI 0.81-0.89). For the alternative models, the ORs were also about 2.5/°C-WBGT, with AUCs between 0.84 and 0.88, which were significantly different from the TLV's AUC but have little practical difference. This study (1) confirmed that the TLV is appropriate for heat stress screening; (2) demonstrated the TLV's discrimination accuracy with an ROC AUC of 0.85; and (3) established the OR of 2.5/°C-WBGT for unsustainable exposures. The TLV has high sensitivity, but its specificity is very low, which is protective. There were no important

  11. Inflammatory stress of pancreatic beta cells drives release of extracellular heat shock protein 90α.

    PubMed

    Ocaña, Gail J; Pérez, Liliana; Guindon, Lynette; Deffit, Sarah N; Evans-Molina, Carmella; Thurmond, Debbie C; Blum, Janice S

    2017-02-11

    A major obstacle in predicting and preventing the development of autoimmune type 1 diabetes (T1D) in at-risk individuals is the lack of well-established early biomarkers indicative of ongoing beta cell stress during the pre-clinical phase of disease. Recently, serum levels of the alpha cytoplasmic isoform of heat shock protein (HSP) 90 were shown to be elevated in individuals with new-onset T1D. We therefore hypothesized HSP90α could be released from beta cells in response to cellular stress and inflammation associated with the earliest stages of T1D. Here, human beta cell lines and cadaveric islets released HSP90α in response to stress induced by treatment with a combination of pro-inflammatory cytokines including IL-1β, TNF-α, and IFN-γ. Mechanistically, HSP90α release was found to be driven by cytokine-induced endoplasmic reticulum (ER) stress mediated by c-Jun N-terminal kinase (JNK), a pathway that can eventually lead to beta cell apoptosis. Cytokine-induced beta cell HSP90α release and JNK activation were significantly reduced by pre-treating cells with the ER stress-mitigating chemical chaperone tauroursodeoxycholic acid (TUDCA). HSP90α release by cells may thus be a sensitive indicator of stress during inflammation and a useful tool in assessing therapeutic mitigation of cytokine-induced cell damage linked to autoimmunity. This article is protected by copyright. All rights reserved.

  12. Age, splanchnic vasoconstriction, and heat stress during tilting

    NASA Technical Reports Server (NTRS)

    Minson, C. T.; Wladkowski, S. L.; Pawelczyk, J. A.; Kenney, W. L.

    1999-01-01

    During upright tilting, blood is translocated to the dependent veins of the legs and compensatory circulatory adjustments are necessary to maintain arterial pressure. For examination of the effect of age on these responses, seven young (23 +/- 1 yr) and seven older (70 +/- 3 yr) men were head-up tilted to 60 degrees in a thermoneutral condition and during passive heating with water-perfused suits. Measurements included heart rate (HR), cardiac output (Qc; acetylene rebreathing technique), central venous pressure (CVP), blood pressures, forearm blood flow (venous occlusion plethysmography), splanchnic and renal blood flows (indocyanine green and p-aminohippurate clearance), and esophageal and mean skin temperatures. In response to tilting in the thermoneutral condition, CVP and stroke volume decreased to a greater extent in the young men, but HR increased more, such that the fall in Qc was similar between the two groups in the upright posture. The rise in splanchnic vascular resistance (SVR) was greater in the older men, but the young men increased forearm vascular resistance (FVR) to a greater extent than the older men. The fall in Qc during combined heat stress and tilting was greater in the young compared with older men. Only four of the young men versus six of the older men were able to finish the second tilt without becoming presyncopal. In summary, the older men relied on a greater increase in SVR to compensate for a reduced ability to constrict the skin and muscle circulations (as determined by changes in FVR) during head-up tilting.

  13. Age, splanchnic vasoconstriction, and heat stress during tilting

    NASA Technical Reports Server (NTRS)

    Minson, C. T.; Wladkowski, S. L.; Pawelczyk, J. A.; Kenney, W. L.

    1999-01-01

    During upright tilting, blood is translocated to the dependent veins of the legs and compensatory circulatory adjustments are necessary to maintain arterial pressure. For examination of the effect of age on these responses, seven young (23 +/- 1 yr) and seven older (70 +/- 3 yr) men were head-up tilted to 60 degrees in a thermoneutral condition and during passive heating with water-perfused suits. Measurements included heart rate (HR), cardiac output (Qc; acetylene rebreathing technique), central venous pressure (CVP), blood pressures, forearm blood flow (venous occlusion plethysmography), splanchnic and renal blood flows (indocyanine green and p-aminohippurate clearance), and esophageal and mean skin temperatures. In response to tilting in the thermoneutral condition, CVP and stroke volume decreased to a greater extent in the young men, but HR increased more, such that the fall in Qc was similar between the two groups in the upright posture. The rise in splanchnic vascular resistance (SVR) was greater in the older men, but the young men increased forearm vascular resistance (FVR) to a greater extent than the older men. The fall in Qc during combined heat stress and tilting was greater in the young compared with older men. Only four of the young men versus six of the older men were able to finish the second tilt without becoming presyncopal. In summary, the older men relied on a greater increase in SVR to compensate for a reduced ability to constrict the skin and muscle circulations (as determined by changes in FVR) during head-up tilting.

  14. Mitochondrial efficiency and exercise economy following heat stress: a potential role of uncoupling protein 3.

    PubMed

    Salgado, Roy M; Sheard, Ailish C; Vaughan, Roger A; Parker, Daryl L; Schneider, Suzanne M; Kenefick, Robert W; McCormick, James J; Gannon, Nicholas P; Van Dusseldorp, Trisha A; Kravitz, Len R; Mermier, Christine M

    2017-02-01

    Heat stress has been reported to reduce uncoupling proteins (UCP) expression, which in turn should improve mitochondrial efficiency. Such an improvement in efficiency may translate to the systemic level as greater exercise economy. However, neither the heat-induced improvement in mitochondrial efficiency (due to decrease in UCP), nor its potential to improve economy has been studied. Determine: (i) if heat stress in vitro lowers UCP3 thereby improving mitochondrial efficiency in C2C12 myocytes; (ii) whether heat acclimation (HA) in vivo improves exercise economy in trained individuals; and (iii) the potential improved economy during exercise at altitude. In vitro, myocytes were heat stressed for 24 h (40°C), followed by measurements of UCP3, mitochondrial uncoupling, and efficiency. In vivo, eight trained males completed: (i) pre-HA testing; (ii) 10 days of HA (40°C, 20% RH); and (iii) post-HA testing. Pre- and posttesting consisted of maximal exercise test and submaximal exercise at two intensities to assess exercise economy at 1600 m (Albuquerque, NM) and 4350 m. Heat-stressed myocytes displayed significantly reduced UCP3 mRNA expression and, mitochondrial uncoupling (77.1 ± 1.2%, P < 0.0001) and improved mitochondrial efficiency (62.9 ± 4.1%, P < 0.0001) compared to control. In humans, at both 1600 m and 4350 m, following HA, submaximal exercise economy did not change at low and moderate exercise intensities. Our findings indicate that while heat-induced reduction in UCP3 improves mitochondrial efficiency in vitro, this is not translated to in vivo improvement of exercise economy at 1600 m or 4350 m. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  15. Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502.

    PubMed

    Selby, Katja; Mascher, Gerald; Somervuo, Panu; Lindström, Miia; Korkeala, Hannu

    2017-01-01

    Foodborne pathogenic bacteria are exposed to a number of environmental stresses during food processing, storage, and preparation, and in the human body. In order to improve the safety of food, the understanding of molecular stress response mechanisms foodborne pathogens employ is essential. Many response mechanisms that are activated during heat shock may cross-protect bacteria against other environmental stresses. To better understand the molecular mechanisms Clostridium botulinum, the causative agent of botulism, utilizes during acute heat stress and during adaptation to stressfully high temperature, the C. botulinum Group I strain ATCC 3502 was grown in continuous culture at 39°C and exposed to heat shock at 45°C, followed by prolonged heat stress at 45°C to allow adaptation of the culture to the high temperature. Growth in continuous culture was performed to exclude secondary growth phase effects or other environmental impacts on bacterial gene transcription. Changes in global gene expression profiles were studied using DNA microarray hybridization. During acute heat stress, Class I and III heat shock genes as well as members of the SOS regulon were activated. The neurotoxin gene botA and genes encoding the neurotoxin-associated proteins were suppressed throughout the study. Prolonged heat stress led to suppression of the sporulation machinery whereas genes related to chemotaxis and motility were activated. Induced expression of a large proportion of prophage genes was detected, suggesting an important role of acquired genes in the stress resistance of C. botulinum. Finally, changes in the expression of a large number of genes related to carbohydrate and amino acid metabolism indicated remodeling of the cellular metabolism.

  16. Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502

    PubMed Central

    Selby, Katja; Mascher, Gerald; Somervuo, Panu; Korkeala, Hannu

    2017-01-01

    Foodborne pathogenic bacteria are exposed to a number of environmental stresses during food processing, storage, and preparation, and in the human body. In order to improve the safety of food, the understanding of molecular stress response mechanisms foodborne pathogens employ is essential. Many response mechanisms that are activated during heat shock may cross-protect bacteria against other environmental stresses. To better understand the molecular mechanisms Clostridium botulinum, the causative agent of botulism, utilizes during acute heat stress and during adaptation to stressfully high temperature, the C. botulinum Group I strain ATCC 3502 was grown in continuous culture at 39°C and exposed to heat shock at 45°C, followed by prolonged heat stress at 45°C to allow adaptation of the culture to the high temperature. Growth in continuous culture was performed to exclude secondary growth phase effects or other environmental impacts on bacterial gene transcription. Changes in global gene expression profiles were studied using DNA microarray hybridization. During acute heat stress, Class I and III heat shock genes as well as members of the SOS regulon were activated. The neurotoxin gene botA and genes encoding the neurotoxin-associated proteins were suppressed throughout the study. Prolonged heat stress led to suppression of the sporulation machinery whereas genes related to chemotaxis and motility were activated. Induced expression of a large proportion of prophage genes was detected, suggesting an important role of acquired genes in the stress resistance of C. botulinum. Finally, changes in the expression of a large number of genes related to carbohydrate and amino acid metabolism indicated remodeling of the cellular metabolism. PMID:28464023

  17. Temporal characteristics of thermal satellite images for urban heat stress and heat island mapping

    NASA Astrophysics Data System (ADS)

    Nichol, Janet E.; To, Pui Hang

    2012-11-01

    The reconstruction of urban climate is still challenging to climatologists in spite of over five decades of research including direct data measurement and model building. Methods for measuring and monitoring urban climate have strengths and weaknesses depending on the application. The mapping of patterns of urban heat stress over a city is not useful if the patterns depicted apply only to the time of data acquisition. Since thermal satellite sensors can now provide detailed temperature data covering whole cities and beyond, their adoption in urban planning depends on demonstrating their relevance to commonly prevailing conditions. This research investigates and presents a methodology based on four summertime ASTER thermal satellite images of Hong Kong for urban heat stress mapping at detailed level. It demonstrates that satellite images obtained under certain climatic conditions, and accompanied by adequate 'in situ' ground data, can provide a basis for an operational heat stress mapping system. The temporal limitation of thermal satellite images is examined for both day and nighttime images by comparison of image-derived air temperatures with ground data representing extended periods and other hot days and nights outside the image acquisition times. The nighttime images were found to be more representative of air temperature at other times than the daytime images, due to a more stable boundary layer, with lower wind speeds and temperature inversion at night. The nighttime images showed high and significant correlations with ground level air temperatures for an average 13-h period surrounding the image time 10.42pm, from 6 pm to 4-8 am the next day. Additionally they were highly and significantly correlated with ground air temperature distributions on 93% of all hot summer nights in the same years. Therefore the nighttime images can be considered representative of a commonly occurring summer nighttime situation in Hong Kong, and can be used to determine the

  18. Assessment of Residual Stresses in 3013 Inner and Outer Containers and Teardrop Samples

    SciTech Connect

    Stroud, Mary Ann; Prime, Michael Bruce; Veirs, Douglas Kirk; Berg, John M.; Clausen, Bjorn; Worl, Laura Ann; DeWald, Adrian T.

    2015-12-08

    This report is an assessment performed by LANL that examines packaging for plutonium-bearing materials and the resilience of its design. This report discusses residual stresses in the 3013 outer, the SRS/Hanford and RFETS/LLNL inner containers, and teardrop samples used in studies to assess the potential for SCC in 3013 containers. Residual tensile stresses in the heat affected zones of the closure welds are of particular concern.

  19. Insect pollination reduces yield loss following heat stress in faba bean (Vicia faba L.).

    PubMed

    Bishop, Jacob; Jones, Hannah Elizabeth; Lukac, Martin; Potts, Simon Geoffrey

    2016-03-15

    Global food security, particularly crop fertilization and yield production, is threatened by heat waves that are projected to increase in frequency and magnitude with climate change. Effects of heat stress on the fertilization of insect-pollinated plants are not well understood, but experiments conducted primarily in self-pollinated crops, such as wheat, show that transfer of fertile pollen may recover yield following stress. We hypothesized that in the partially pollinator-dependent crop, faba bean (Vicia faba L.), insect pollination would elicit similar yield recovery following heat stress. We exposed potted faba bean plants to heat stress for 5 days during floral development and anthesis. Temperature treatments were representative of heat waves projected in the UK for the period 2021-2050 and onwards. Following temperature treatments, plants were distributed in flight cages and either pollinated by domesticated Bombus terrestris colonies or received no insect pollination. Yield loss due to heat stress at 30 °C was greater in plants excluded from pollinators (15%) compared to those with bumblebee pollination (2.5%). Thus, the pollinator dependency of faba bean yield was 16% at control temperatures (18-26 °C) and extreme stress (34 °C), but was 53% following intermediate heat stress at 30 °C. These findings provide the first evidence that the pollinator dependency of crops can be modified by heat stress, and suggest that insect pollination may become more important in crop production as the probability of heat waves increases.

  20. Heat stress proteins and myocardial protection: experimental model or potential clinical tool?

    PubMed

    Gray, C C; Amrani, M; Yacoub, M H

    1999-05-01

    Heat stress proteins (hsp) are induced by a variety of stimuli including elevated temperature, ischaemia, hypoxia, pressure overload and some chemicals. They help to maintain the metabolic and structural integrity of the cell, as a protective response to external stresses. They are known to protect the myocardium from the damaging effects of ischaemia and reperfusion. The heat stress response results in accumulation of heat stress proteins. The beneficial effects associated with their expression include improved endothelial and mechanical recovery of the ischaemic heart. In addition, preservation of high energy phosphates and reduction in infarct size. It has also been shown that critical amounts of hsp70 are necessary to ensure protection of the myocardium. However, questions remain regarding the biochemical mechanisms underlying this protective effect. Alterations in the cell metabolism and chaperone function of cells expressing heat shock proteins, are thought to be responsible. Despite the obvious clinical benefits related to the heat stress response in a clinical setting, the application of this phenomena remains limited. Heat, both quantitatively and qualitatively is one of the best inducers of heat stress proteins. However, the effects of heat stress are nonspecific and intracellular damage is a common occurrence. The search for alternative stimuli, particularly within the fields of pharmacotherapy or genetic manipulation may offer more viable options, if the heat stress response is take its place as an established strategy for myocardial protection.

  1. Nutritional Interventions to Alleviate the Negative Consequences of Heat Stress12

    PubMed Central

    Rhoads, Robert P.; Baumgard, Lance H.; Suagee, Jessica K.; Sanders, Sara R.

    2013-01-01

    Energy metabolism is a highly coordinated process, and preferred fuel(s) differ among tissues. The hierarchy of substrate use can be affected by physiological status and environmental factors including high ambient temperature. Unabated heat eventually overwhelms homeothermic mechanisms resulting in heat stress, which compromises animal health, farm animal production, and human performance. Various aspects of heat stress physiology have been extensively studied, yet a clear understanding of the metabolic changes occurring at the cellular, tissue, and whole-body levels in response to an environmental heat load remains ill-defined. For reasons not yet clarified, circulating nonesterified fatty acid levels are reduced during heat stress, even in the presence of elevated stress hormones (epinephrine, glucagon, and cortisol), and heat-stressed animals often have a blunted lipolytic response to catabolic signals. Either directly because of or in coordination with this, animals experiencing environmental hyperthermia exhibit a shift toward carbohydrate use. These metabolic alterations occur coincident with increased circulating basal and stimulated plasma insulin concentrations. Limited data indicate that proper insulin action is necessary to effectively mount a response to heat stress and minimize heat-induced damage. Consistent with this idea, nutritional interventions targeting increased insulin action may improve tolerance and productivity during heat stress. Further research is warranted to uncover the effects of heat on parameters associated with energy metabolism so that more appropriate and effective treatment methodologies can be designed. PMID:23674792

  2. Sm-Like Protein-Mediated RNA Metabolism Is Required for Heat Stress Tolerance in Arabidopsis

    PubMed Central

    Okamoto, Masanori; Matsui, Akihiro; Tanaka, Maho; Morosawa, Taeko; Ishida, Junko; Iida, Kei; Mochizuki, Yoshiki; Toyoda, Tetsuro; Seki, Motoaki

    2016-01-01

    Sm-like proteins play multiple functions in RNA metabolism, which is essential for biological processes such as stress responses in eukaryotes. The Arabidopsis thaliana sad1 mutant has a mutation of sm-like protein 5 (LSM5) and shows impaired drought and salt stress tolerances. The lsm5/sad1 mutant also showed hypersensitivity to heat stress. GFP-fused LSM5/SAD1 was localized in the nucleus under optimal growth conditions. After heat stress treatment, GFP-fused LSM5/SAD1 fluorescence was also observed as small cytoplasmic dots, in addition to nuclear localization. Whole genome transcriptome analysis revealed that many genes in Arabidopsis were drastically changed in response to heat stress. More heat-responsive genes were highly expressed in lsm5/sad1 mutant at both 2 and 6 h after heat stress treatment. Additionally, intron-retained and capped transcripts accumulated in the lsm5/sad1 mutant after heat stress treatment. In this study, we also identified non-Arabidopsis Genome Initiative transcripts that were expressed from unannotated regions. Most of these transcripts were antisense transcripts, and many capped non-AGI transcripts accumulated in the lsm5/sad1 mutant during heat stress treatment. These results indicated that LSM5/SAD1 functions to degrade aberrant transcripts through appropriate mRNA splicing and decapping, and precise RNA metabolic machinery is required for heat stress tolerance. PMID:27493656

  3. Expression and interaction of small heat shock proteins (sHsps) in rice in response to heat stress.

    PubMed

    Chen, Xinhai; Lin, Shoukai; Liu, Qiulin; Huang, Jian; Zhang, Wenfeng; Lin, Jun; Wang, Yongfei; Ke, Yuqin; He, Huaqin

    2014-04-01

    The inherent immobility of rice (Oryza sativa L.) limited their abilities to avoid heat stress and required them to contend with heat stress through innate defense abilities in which heat shock proteins played important roles. In this study, Hsp26.7, Hsp23.2, Hsp17.9A, Hsp17.4 and Hsp16.9A were up-regulated in Nipponbare during seedling and anthesis stages in response to heat stress. Subsequently, the expressing levels of these five sHsps in the heat-tolerant rice cultivar, Co39, were all significantly higher than that in the heat-susceptible rice cultivar, Azucena. This indicated that the expressive level of these five sHsps was positively related to the ability of rice plants to avoid heat stress. Thus, the expression level of these five sHsps can be regarded as bio-markers for screening rice cultivars with different abilities to avoid heat stress. Hsp18.1, Hsp17.9A, Hsp17.7 and Hsp16.9A, in the three rice cultivars under heat stress were found to be involved in one protein complex by Native-PAGE, and the interactions of Hsp18.1 and Hsp 17.7, Hsp18.1 and Hsp 17.9A, and Hsp17.7 and Hsp16.9A were further validated by yeast 2-hybridization. Pull down assay also confirmed the interaction between Hsp17.7 and Hsp16.9A in rice under heat stress. In conclusion, the up-regulation of the 5 sHsps is a key step for rice to tolerate heat stress, after that some sHsps assembled into a large hetero-oligomeric complex. In addition, through protein-protein interaction, Hsp101 regulated thiamine biosynthesis, and Hsp82 homology affected nitrogen metabolism, while Hsp81-1 were involved in the maintenance of sugar or starch synthesis in rice plants under heat stress. These results provide new insight into the regulatory mechanism of sHsps in rice. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Investigation of countermeasure for unloading-related muscle plasticity: role of heat stress

    NASA Astrophysics Data System (ADS)

    Goto, K.; Kobayashi, T.; Kojima, A.; Akema, T.; Sugiura, T.; Yamada, S.; Ohira, Y.; Yoshioka, T.

    We have been studying the mechanisms responsible for unloading- or loading-related muscle plasticity. The purpose of the current study was to investigate the effects of heat stress on the growth of mammalian skeletal muscles in vivo. Male Wistar rats (7 weeks old) were divided into two groups: control (n = 24) and heat stress (n = 24). Rats of heat stressed group were exposed to environmental heat stress (41°C for 60 min) in a heat chamber without anesthesia. The soleus muscles were dissected 1, 3, 7, and 14 days after the heat exposure. The wet weights of muscle relative to body weights in heat stressed group were significantly higher than control group 7 days after the exposure (p<0.05). The relative proportion of 5-bromo-2'-deoxyuridine- and proliferating cell nuclear antigen-positive nuclei, that are indicators for the cell proliferation, were increased 1 day after heating (p<0.05). Pax7-positive nuclei, that are indicators for the muscle satellite cells, were also increased 3 day after heat exposure. The expression of phosphorylated p70 S6 kinase was increased 1 day following heat exposure. These results suggest that heat stress could promote cell proliferation, activate satellite cells, and induce muscular hypertrophy.

  5. Genome scale transcriptional response diversity among ten ecotypes of Arabidopsis thaliana during heat stress

    PubMed Central

    Barah, Pankaj; Jayavelu, Naresh D.; Mundy, John; Bones, Atle M.

    2013-01-01

    In the scenario of global warming and climate change, heat stress is a serious threat to crop production worldwide. Being sessile, plants cannot escape from heat. Plants have developed various adaptive mechanisms to survive heat stress. Several studies have focused on diversity of heat tolerance levels in divergent Arabidopsis thaliana (A. thaliana) ecotypes, but comprehensive genome scale understanding of heat stress response in plants is still lacking. Here we report the genome scale transcript responses to heat stress of 10 A. thaliana ecotypes (Col, Ler, C24, Cvi, Kas1, An1, Sha, Kyo2, Eri, and Kond) originated from different geographical locations. During the experiment, A. thaliana plants were subjected to heat stress (38°C) and transcript responses were monitored using Arabidopsis NimbleGen ATH6 microarrays. The responses of A. thaliana ecotypes exhibited considerable variation in the transcript abundance levels. In total, 3644 transcripts were significantly heat regulated (p < 0.01) in the 10 ecotypes, including 244 transcription factors and 203 transposable elements. By employing a systems genetics approach- Network Component Analysis (NCA), we have constructed an in silico transcript regulatory network model for 35 heat responsive transcription factors during cellular responses to heat stress in A. thaliana. The computed activities of the 35 transcription factors showed ecotype specific responses to the heat treatment. PMID:24409190

  6. Genome scale transcriptional response diversity among ten ecotypes of Arabidopsis thaliana during heat stress.

    PubMed

    Barah, Pankaj; Jayavelu, Naresh D; Mundy, John; Bones, Atle M

    2013-01-01

    In the scenario of global warming and climate change, heat stress is a serious threat to crop production worldwide. Being sessile, plants cannot escape from heat. Plants have developed various adaptive mechanisms to survive heat stress. Several studies have focused on diversity of heat tolerance levels in divergent Arabidopsis thaliana (A. thaliana) ecotypes, but comprehensive genome scale understanding of heat stress response in plants is still lacking. Here we report the genome scale transcript responses to heat stress of 10 A. thaliana ecotypes (Col, Ler, C24, Cvi, Kas1, An1, Sha, Kyo2, Eri, and Kond) originated from different geographical locations. During the experiment, A. thaliana plants were subjected to heat stress (38°C) and transcript responses were monitored using Arabidopsis NimbleGen ATH6 microarrays. The responses of A. thaliana ecotypes exhibited considerable variation in the transcript abundance levels. In total, 3644 transcripts were significantly heat regulated (p < 0.01) in the 10 ecotypes, including 244 transcription factors and 203 transposable elements. By employing a systems genetics approach- Network Component Analysis (NCA), we have constructed an in silico transcript regulatory network model for 35 heat responsive transcription factors during cellular responses to heat stress in A. thaliana. The computed activities of the 35 transcription factors showed ecotype specific responses to the heat treatment.

  7. Characterization of genes and pathways that respond to heat stress in Holstein calves through transcriptome analysis.

    PubMed

    Srikanth, Krishnamoorthy; Kwon, Anam; Lee, Eunjin; Chung, Hoyoung

    2017-01-01

    This study aimed to investigate the genes and pathways that respond to heat stress in Holstein bull calves exposed to severe ranges of temperature and humidity. A total of ten animals from 4 to 6 months of age were subjected to heat stress at 37 °C and 90 % humidity for 12 h. Skin and rectal temperatures were measured before and after heat stress; while no correlation was found between them before heat stress, a moderate correlation was detected after heat stress, confirming rectal temperature to be a better barometer for monitoring heat stress. RNAseq analysis identified 8567 genes to be differentially regulated, out of which 465 genes were significantly upregulated (≥2-fold, P < 0.05) and 49 genes were significantly downregulated (≤2-fold, P < 0.05) in response to heat stress. Significant terms and pathways enriched in response to heat stress included chaperones, cochaperones, cellular response to heat stress, phosphorylation, kinase activation, immune response, apoptosis, Toll-like receptor signaling pathway, Pi3K/AKT activation, protein processing in endoplasmic reticulum, interferon signaling, pathways in cancer, estrogen signaling pathway, and MAPK signaling pathway. The differentially expressed genes were validated by quantitative real-time PCR analysis, which confirmed the tendency of the expression. The genes and pathways identified in this analysis extend our understanding of transcriptional response to heat stress and their likely functioning in adapting the animal to hyperthermic stress. The identified genes could be used as candidate genes for association studies to select and breed animals with improved heat tolerance.

  8. Moderate summer heat stress does not modify immunological parameters of Holstein dairy cows

    NASA Astrophysics Data System (ADS)

    Lacetera, Nicola; Bernabucci, Umberto; Ronchi, Bruno; Scalia, Daniela; Nardone, Alessandro

    2002-02-01

    The study was undertaken during spring and summer months in a territory representative of the Mediterranean climate to assess the effects of season on some immunological parameters of dairy cows. Twenty Holstein cows were used. Eleven of those cows gave birth during spring; the remaining nine cows gave birth in summer. The two groups of cows were homogeneous for parity. Values of air temperatures and relative humidity were recorded both during spring and summer, and were utilized to calculate the temperature humidity index (THI). One week before the expected calving, rectal temperatures and respiratory rates of the cows were recorded (1500 hours), and cell-mediated immunity was assessed by measuring the proliferation of mitogen-stimulated peripheral blood mononuclear cells (PBMC). Within 3 h of calving, one colostrum sample was taken from each cow and analysed to determine content of immunoglobulin (Ig) G1, IgG2, IgM and IgA. At 48 h after birth, passive immunization of the calves was assessed by measuring total serum IgG. During summer, daytime (0900-2000 hours) THI values were above the upper critical value of 72 [75.2, (SD 2.6)] indicating conditions that could represent moderate heat stress. That THI values were able to predict heat stress was confirmed by the values of rectal temperatures and respiratory rates, which were higher ( P < 0.05 and P < 0.001 respectively) during summer. Proliferation of PBMC, the colostral concentration of Ig fractions and serum levels of IgG in their respective offspring did not differ between spring and summer cows. Results indicated that moderate heat stress due to the hot Mediterranean summer does not modify cell-mediated immunity, the protective value of colostrum and passive immunization of the offspring in dairy cows.

  9. Moderate summer heat stress does not modify immunological parameters of Holstein dairy cows.

    PubMed

    Lacetera, Nicola; Bernabucci, Umberto; Ronchi, Bruno; Scalia, Daniela; Nardone, Alessandro

    2002-02-01

    The study was undertaken during spring and summer months in a territory representative of the Mediterranean climate to assess the effects of season on some immunological parameters of dairy cows. Twenty Holstein cows were used. Eleven of those cows gave birth during spring; the remaining nine cows gave birth in summer. The two groups of cows were homogeneous for parity. Values of air temperatures and relative humidity were recorded both during spring and summer, and were utilized to calculate the temperature humidity index (THI). One week before the expected calving, rectal temperatures and respiratory rates of the cows were recorded (1500 hours), and cell-mediated immunity was assessed by measuring the proliferation of mitogen-stimulated peripheral blood mononuclear cells (PBMC). Within 3 h of calving, one colostrum sample was taken from each cow and analysed to determine content of immunoglobulin (Ig) G1, IgG2, IgM and IgA. At 48 h after birth, passive immunization of the calves was assessed by measuring total serum IgG. During summer, daytime (0900-2000 hours) THI values were above the upper critical value of 72 [75.2, (SD 2.6)] indicating conditions that could represent moderate heat stress. That THI values were able to predict heat stress was confirmed by the values of rectal temperatures and respiratory rates, which were higher (P < 0.05 and P < 0.001 respectively) during summer. Proliferation of PBMC, the colostral concentration of Ig fractions and serum levels of IgG in their respective off-spring did not differ between spring and summer cows. Results indicated that moderate heat stress due to the hot Mediterranean summer does not modify cell-mediated immunity, the protective value of colostrum and passive immunization of the offspring in dairy cows.

  10. Reynolds stress and heat flux in spherical shell convection

    NASA Astrophysics Data System (ADS)

    Käpylä, P. J.; Mantere, M. J.; Guerrero, G.; Brandenburg, A.; Chatterjee, P.

    2011-07-01

    Context. Turbulent fluxes of angular momentum and enthalpy or heat due to rotationally affected convection play a key role in determining differential rotation of stars. Their dependence on latitude and depth has been determined in the past from convection simulations in Cartesian or spherical simulations. Here we perform a systematic comparison between the two geometries as a function of the rotation rate. Aims: Here we want to extend the earlier studies by using spherical wedges to obtain turbulent angular momentum and heat transport as functions of the rotation rate from stratified convection. We compare results from spherical and Cartesian models in the same parameter regime in order to study whether restricted geometry introduces artefacts into the results. In particular, we want to clarify whether the sharp equatorial profile of the horizontal Reynolds stress found in earlier Cartesian models is also reproduced in spherical geometry. Methods: We employ direct numerical simulations of turbulent convection in spherical and Cartesian geometries. In order to alleviate the computational cost in the spherical runs, and to reach as high spatial resolution as possible, we model only parts of the latitude and longitude. The rotational influence, measured by the Coriolis number or inverse Rossby number, is varied from zero to roughly seven, which is the regime that is likely to be realised in the solar convection zone. Cartesian simulations are performed in overlapping parameter regimes. Results: For slow rotation we find that the radial and latitudinal turbulent angular momentum fluxes are directed inward and equatorward, respectively. In the rapid rotation regime the radial flux changes sign in accordance with earlier numerical results, but in contradiction with theory. The latitudinal flux remains mostly equatorward and develops a maximum close to the equator. In Cartesian simulations this peak can be explained by the strong "banana cells". Their effect in the

  11. Thermotolerance and heat stress responses of Douglas-fir and ponderosa pine seedling populations from contrasting climates.

    PubMed

    Marias, Danielle E; Meinzer, Frederick C; Woodruff, David R; McCulloh, Katherine A

    2016-12-21

    Temperature and the frequency and intensity of heat waves are predicted to increase throughout the 21st century. Germinant seedlings are expected to be particularly vulnerable to heat stress because they are in the boundary layer close to the soil surface where intense heating occurs in open habitats. We quantified leaf thermotolerance and whole-plant physiological responses to heat stress in first-year germinant seedlings in two populations each of Pinus ponderosa P. and C. Lawson (PIPO) and Pseudotsuga menziesii (Mirb.) Franco (PSME) from climates with contrasting precipitation and temperature regimes. Thermotolerance of detached needles was evaluated using chlorophyll fluorescence (FV/FM, FO) and electrolyte leakage. PSME was more heat tolerant than PIPO according to both independent assessments of thermotolerance. Following exposure of whole seedlings to a simulated heat wave at 45 °C for 1 h in a growth chamber, we monitored FV/FM, photosynthesis, stomatal conductance, non-structural carbohydrates (NSCs) and carbon isotope ratios (δ(13)C) for 14 days. Heat treatment induced significant reductions in FV/FM in both species and a transient reduction in photosynthetic gas exchange only in PIPO 1 day after treatment. Heat treatment induced an increase in glucose + fructose concurrent with a decrease in starch in both species, whereas total NSC and sucrose were not affected by heat treatment. The negative relationship between glucose + fructose and starch observed in treated plants may be due to the conversion of starch to glucose + fructose to aid recovery from heat-induced damage. Populations from drier sites displayed greater δ(13)C values than those from wetter sites, consistent with higher intrinsic water-use efficiency and drought resistance of populations from drier climates. Thermotolerance and heat stress responses appeared to be phenotypically plastic and representative of the environment in which plants were grown, whereas intrinsic water

  12. Full genome gene expression analysis of the heat stress response in Drosophila melanogaster

    PubMed Central

    Sørensen, Jesper G.; Nielsen, Morten M.; Kruhøffer, Mogens; Justesen, Just; Loeschcke, Volker

    2005-01-01

    The availability of full genome sequences has allowed the construction of microarrays, with which screening of the full genome for changes in gene expression is possible. This method can provide a wealth of information about biology at the level of gene expression and is a powerful method to identify genes and pathways involved in various processes. In this study, we report a detailed analysis of the full heat stress response in Drosophila melanogaster females, using whole genome gene expression arrays (Affymetrix Inc, Santa Clara, CA, USA). The study focuses on up- as well as downregulation of genes from just before and at 8 time points after an application of short heat hardening (36°C for 1 hour). The expression changes were followed up to 64 hours after the heat stress, using 4 biological replicates. This study describes in detail the dramatic change in gene expression over time induced by a short-term heat treatment. We found both known stress responding genes and new candidate genes, and processes to be involved in the stress response. We identified 3 main groups of stress responsive genes that were early–upregulated, early– downregulated, and late–upregulated, respectively, among 1222 differentially expressed genes in the data set. Comparisons with stress sensitive genes identified by studies of responses to other types of stress allow the discussion of heat-specific and general stress responses in Drosophila. Several unexpected features were revealed by this analysis, which suggests that novel pathways and mechanisms are involved in the responses to heat stress and to stress in general. The majority of stress responsive genes identified in this and other studies were downregulated, and the degree of overlap among downregulated genes was relatively high, whereas genes responding by upregulation to heat and other stress factors were more specific to the stress applied or to the conditions of the particular study. As an expected exception, heat shock

  13. Intensity of heat stress in winter wheat—phenology compensates for the adverse effect of global warming

    NASA Astrophysics Data System (ADS)

    Eyshi Rezaei, Ehsan; Siebert, Stefan; Ewert, Frank

    2015-02-01

    Higher temperatures during the growing season are likely to reduce crop yields with implications for crop production and food security. The negative impact of heat stress has also been predicted to increase even further for cereals such as wheat under climate change. Previous empirical modeling studies have focused on the magnitude and frequency of extreme events during the growth period but did not consider the effect of higher temperature on crop phenology. Based on an extensive set of climate and phenology observations for Germany and period 1951-2009, interpolated to 1 × 1 km resolution and provided as supplementary data to this article (available at stacks.iop.org/ERL/10/024012/mmedia), we demonstrate a strong relationship between the mean temperature in spring and the day of heading (DOH) of winter wheat. We show that the cooling effect due to the 14 days earlier DOH almost fully compensates for the adverse effect of global warming on frequency and magnitude of crop heat stress. Earlier heading caused by the warmer spring period can prevent exposure to extreme heat events around anthesis, which is the most sensitive growth stage to heat stress. Consequently, the intensity of heat stress around anthesis in winter crops cultivated in Germany may not increase under climate change even if the number and duration of extreme heat waves increase. However, this does not mean that global warning would not harm crop production because of other impacts, e.g. shortening of the grain filling period. Based on the trends for the last 34 years in Germany, heat stress (stress thermal time) around anthesis would be 59% higher in year 2009 if the effect of high temperatures on accelerating wheat phenology were ignored. We conclude that climate impact assessments need to consider both the effect of high temperature on grain set at anthesis but also on crop phenology.

  14. Study of heat exchange in cooling systems of heat-stressed structures

    NASA Astrophysics Data System (ADS)

    Vikulin, A. V.; Yaroslavtsev, N. L.; Zemlyanaya, V. A.

    2017-01-01

    Increasing working parameters of the cycle of gas-turbine engines, complicating design of gas-turbine plants, as well as growing aerodynamic, thermal, static, and dynamic loads, necessitate the development of promising cooling systems for heat-stressed structures. This work is devoted to an experimental study of heat exchange in ducts equipped with systems of inclined and cross walls (fins). It has been found that an increase in the Reynolds number Re from 3000 to 20000 leads to a decrease in the heat exchange, which is characterized by the relative Nusselt number overline{Nu}, by 19-30% at the angle of inclination of the walls φ = 0, 40°, 50°, and 90° if the length of the walls x w is comparable to the spacing b s and by 12-15% at φ = 30° and 90° if x w ≫ b s. If cross walls are used in cooling ducts, the length of the walls x w plays the governing role; an increase in this characteristic from 1.22 × 10-3 to 3.14 × 10-3 m leads to an increase in the intensity of heat exchange by 30-40% and to a decrease in the capacity of the entire system of the walls. It has been shown that, on surfaces with wavy fins, the intensity of heat exchange is closest to that determined in the models under study. For example, values of the Colborne criterion StPr2/3 for ducts equipped with wavy fins and for the models under study differ only slightly (by 2-20% depending on the value of the angle φ). However, the difference for surfaces with short plate fins and ducts equipped with inclined walls is high (30-40%). This is due to the design features of these surfaces and to the severe effect of the inlet portion on heat exchange, since the surfaces are characterized by a higher ratio of the duct length to the hydraulic diameter L/d h at small fin thicknesses ((0.1-0.15) × 10-3 m). The experimental results can be used in developing designs of nozzle and rotor blades of high-temperature gas turbines in gas-turbine engines and plants.

  15. Post-heading heat stress and yield impact in winter wheat of China.

    PubMed

    Liu, Bing; Liu, Leilei; Tian, Liying; Cao, Weixing; Zhu, Yan; Asseng, Senthold

    2014-02-01

    Wheat is sensitive to high temperatures, but the spatial and temporal variability of high temperature and its impact on yield are often not known. An analysis of historical climate and yield data was undertaken to characterize the spatial and temporal variability of heat stress between heading and maturity and its impact on wheat grain yield in China. Several heat stress indices were developed to quantify heat intensity, frequency, and duration between heading and maturity based on measured maximum temperature records of the last 50 years from 166 stations in the main wheat-growing region of China. Surprisingly, heat stress between heading and maturity was more severe in the generally cooler northern wheat-growing regions than the generally warmer southern regions of China, because of the delayed time of heading with low temperatures during the earlier growing season and the exposure of the post-heading phase into the warmer part of the year. Heat stress between heading and maturity has increased in the last decades in most of the main winter wheat production areas of China, but the rate was higher in the south than in the north. The correlation between measured grain yields and post-heading heat stress and average temperature were statistically significant in the entire wheat-producing region, and explained about 29% of the observed spatial and temporal yield variability. A heat stress index considering the duration and intensity of heat between heading and maturity was required to describe the correlation of heat stress and yield variability. Because heat stress is a major cause of yield loss and the number of heat events is projected to increase in the future, quantifying the future impact of heat stress on wheat production and developing appropriate adaptation and mitigation strategies are critical for developing food security policies in China and elsewhere. © 2013 John Wiley & Sons Ltd.

  16. Heat-stress and light-stress induce different cellular pathologies in the symbiotic dinoflagellate during coral bleaching.

    PubMed

    Downs, C A; McDougall, Kathleen E; Woodley, Cheryl M; Fauth, John E; Richmond, Robert H; Kushmaro, Ariel; Gibb, Stuart W; Loya, Yossi; Ostrander, Gary K; Kramarsky-Winter, Esti

    2013-01-01

    Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m(-2) s(-1) PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching.

  17. Heat-Stress and Light-Stress Induce Different Cellular Pathologies in the Symbiotic Dinoflagellate during Coral Bleaching

    PubMed Central

    Downs, C. A.; McDougall, Kathleen E.; Woodley, Cheryl M.; Fauth, John E.; Richmond, Robert H.; Kushmaro, Ariel; Gibb, Stuart W.; Loya, Yossi; Ostrander, Gary K.; Kramarsky-Winter, Esti

    2013-01-01

    Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m−2 s−1 PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching. PMID:24324575

  18. Genetic variation for tolerance to terminal heat stress in Dasypyrum villosum

    USDA-ARS?s Scientific Manuscript database

    Heat stress substantially reduces the grain yield and quality of wheat and poses a major challenge to sustain productivity due to global warming. Across wheat growing regions in the US and globally, wheat often experiences terminal heat stress during the post-flowering period. Dasypyrum villosum, a ...

  19. Genome wide association of changes in feeding behavior due to heat stress in pigs

    USDA-ARS?s Scientific Manuscript database

    Heat stress negatively impacts pork production, losses include decreased growth, reduced feed intake, and mortality. Therefore, the objective of this study was to identify genetic markers associated with changes in feeding behavior due to heat stress in grow-finish pigs. Data were collected on grow-...

  20. Transcriptome response to heat stress in a chicken hepatocellular carcinoma cell line.

    PubMed

    Sun, Liang; Lamont, Susan J; Cooksey, Amanda M; McCarthy, Fiona; Tudor, Catalina O; Vijay-Shanker, K; DeRita, Rachael M; Rothschild, Max; Ashwell, Chris; Persia, Michael E; Schmidt, Carl J

    2015-11-01

    Heat stress triggers an evolutionarily conserved set of responses in cells. The transcriptome responds to hyperthermia by altering expression of genes to adapt the cell or organism to survive the heat challenge. RNA-seq technology allows rapid identification of environmentally responsive genes on a large scale. In this study, we have used RNA-seq to identify heat stress responsive genes in the chicken male white leghorn hepatocellular (LMH) cell line. The transcripts of 812 genes were responsive to heat stress (p < 0.01) with 235 genes upregulated and 577 downregulated following 2.5 h of heat stress. Among the upregulated were genes whose products function as chaperones, along with genes affecting collagen synthesis and deposition, transcription factors, chromatin remodelers, and genes modulating the WNT and TGF-beta pathways. Predominant among the downregulated genes were ones that affect DNA replication and repair along with chromosomal segregation. Many of the genes identified in this study have not been previously implicated in the heat stress response. These data extend our understanding of the transcriptome response to heat stress with many of the identified biological processes and pathways likely to function in adapting cells and organisms to hyperthermic stress. Furthermore, this study should provide important insight to future efforts attempting to improve species abilities to withstand heat stress through genome-wide association studies and breeding.

  1. Invited review: heat stress effects during late gestation on dry cows and their calves.

    PubMed

    Tao, S; Dahl, G E

    2013-07-01

    In dairy cattle, late gestation is a critical period for fetal growth and physiological transition into the next lactation. Environmental factors, such as temperature and light, exert dramatic effects on the production, health, and well-being of animals during this period and after parturition. The aim of this review was to introduce effects of heat stress during late gestation on dairy cattle, and discuss the biological mechanisms that underlie the observed production and health responses in the dam and her fetus. Relative to cooled cows, cows that are heat stressed during late gestation have impaired mammary growth before parturition and decreased milk production in the subsequent lactation. In response to higher milk yield, cows cooled prepartum undergo a series of homeorhetic adaptations in early lactation to meet higher demand for milk synthesis compared with heat-stressed cows, but no direct effect of environmental heat stress on metabolism exists during the dry period. Prepartum cooling improves immune status of transition cows and evidence suggests that altered prolactin signaling in immune cells mediates the effects of heat stress on immune function. Late-gestation heat stress compromises placental development, which results in fetal hypoxia, malnutrition, and eventually fetal growth retardation. Maternal heat stress may also have carryover effects on the postnatal growth of offspring, but direct evidence is still lacking. Emerging evidence suggests that offspring from prepartum heat-stressed cows have compromised passive immunity and impaired cell-mediated immune function compared with those from cooled cows.

  2. Heat stress in pregnant sows: Thermal responses and subsequent performance of sows and their offspring.

    PubMed

    Lucy, Matthew C; Safranski, Timothy J

    2017-09-01

    Seasonal infertility is a significant problem in the swine industry, and may be influenced by photoperiod and heat stress. Heat stress during gestation in particular affects pregnancy, resulting in long-term developmental damage to the offspring. This review summarizes what is known about how heat stress on the pregnant sow affects lactation and her offspring. Sows responded to heat stress during gestation with increased rectal temperature, respiration rate, and skin temperature, and tended to reduce their activity-which may have changed their body composition, increasing the adipose-to-muscle ratio. Heat stress during gestation caused temporary insulin resistance during lactation, but this metabolic state did not seem to affect health, lactation, or rebreeding performance of the sow. Heat-stressed sows also presented with a shorter gestation period and reduced litter birth weight, although weaning weights are not affected when these sows are moved to thermoneutral conditions for lactation. The offspring of gestational heat-stressed sows, however, possessed unique phenotypes, including elevated body temperature, greater fat deposition, and impaired gonad development. Thus, gestational heat stress may significantly impact a herd through its effects on sows and their offspring. Further work is necessary to determine the magnitude of the effects across fa cilities and breeds. © 2017 Wiley Periodicals, Inc.

  3. Fertility of lactating dairy cows administered recombinant bovine somatotropin during heat stress.

    PubMed

    Jousan, F D; de Castro e Paula, L A; Block, J; Hansen, P J

    2007-01-01

    Administration of recombinant bovine somatotropin (bST) to lactating dairy cows during heat stress increases milk yield, but it also can increase body temperature and may therefore compromise fertility. However, it is possible that bST treatment could increase fertility during heat stress because it has been reported to increase fertility in lactating cows. In addition, bST increases secretion of insulin-like growth factor-I (IGF-I) that promotes embryo survival. The purpose of this study was to determine effects of bST on reproductive function in lactating dairy cows during heat stress. The experiment was conducted in southern Georgia from July to November 2005 using lactating Holstein cows (n = 276 for reproductive traits). For first service timed artificial insemination (TAI), cows were presynchronized with 2 injections of PGF(2alpha) given 14 d apart followed by a modified Ovsynch protocol (GnRH and insemination at 72 h following PGF(2alpha) ). Pregnancy was diagnosed by using ultrasonography on d 29 and reconfirmed by palpation between d 45 and 80 post-TAI. Nonpregnant cows were resynchronized with the modified Ovsynch protocol and received a second TAI. Treatment with bST started 1 wk before the start of Ovsynch and continued at 2-wk intervals. Blood samples were collected from a subset of cows to determine IGF-I profiles immediately before the first bST injection, 1 wk later, and at d 35 of bST treatment. Rectal temperatures were assessed on d 29 of bST treatment. Pregnancy rates (d 45 to 80 post-TAI) did not differ between bST and control cows for first- (16.7 vs. 15.2%) or second-service TAI (14.8 vs. 17.2%). Plasma concentrations of IGF-I and milk yield were greater for bST-treated cows following the initiation of bST treatment and bST increased rectal and vaginal temperatures. Body condition score was less for bST-treated cows. In conclusion, treatment with bST during heat stress increased IGF-I concentrations, milk yield over time, and rectal and

  4. Heat-resistant protein expression during germination of maize seeds under water stress.

    PubMed

    Abreu, V M; Silva Neta, I C; Von Pinho, E V R; Naves, G M F; Guimarães, R M; Santos, H O; Von Pinho, R G

    2016-08-12

    Low water availability is one of the factors that limit agricultural crop development, and hence the development of genotypes with increased water stress tolerance is a challenge in plant breeding programs. Heat-resistant proteins have been widely studied, and are reported to participate in various developmental processes and to accumulate in response to stress. This study aimed to evaluate heat-resistant protein expression under water stress conditions during the germination of maize seed inbreed lines differing in their water stress tolerance. Maize seed lines 91 and 64 were soaked in 0, -0.3, -0.6, and -0.9 MPa water potential for 0, 6, 12, 18, and 24 h. Line 91 is considered more water stress-tolerant than line 64. The analysis of heat-resistant protein expression was made by gel electrophoresis and spectrophotometry. In general, higher expression of heat-resistant proteins was observed in seeds from line 64 subjected to shorter soaking periods and lower water potentials. However, in the water stress-tolerant line 91, a higher expression was observed in seeds that were subjected to -0.3 and -0.6 MPa water potentials. In the absence of water stress, heat-resistant protein expression was reduced with increasing soaking period. Thus, there was a difference in heat-resistant protein expression among the seed lines differing in water stress tolerance. Increased heat-resistant protein expression was observed in seeds from line 91 when subjected to water stress conditions for longer soaking periods.

  5. Mitigation of heat stress-related complications by a yeast fermentate product.

    PubMed

    Giblot Ducray, Henri Alexandre; Globa, Ludmila; Pustovyy, Oleg; Reeves, Stuart; Robinson, Larry; Vodyanoy, Vitaly; Sorokulova, Iryna

    2016-08-01

    Heat stress results in a multitude of biological and physiological responses which can become lethal if not properly managed. It has been shown that heat stress causes significant adverse effects in both human and animals. Different approaches have been proposed to mitigate the adverse effects caused by heat stress, among which are special diet and probiotics. We characterized the effect of the yeast fermentate EpiCor (EH) on the prevention of heat stress-related complications in rats. We found that increasing the body temperature of animals from 37.1±0.2 to 40.6±0.2°C by exposure to heat (45°C for 25min) resulted in significant morphological changes in the intestine. Villi height and total mucosal thickness decreased in heat-stressed rats pre-treated with PBS in comparison with control animals not exposed to the heat. Oral treatment of rats with EH before heat stress prevented the traumatic effects of heat on the intestine. Changes in intestinal morphology of heat-stressed rats, pre-treated with PBS resulted in significant elevation of lipopolysaccharides (LPS) level in the serum of these animals. Pre-treatment with EH was effective in the prevention of LPS release into the bloodstream of heat-stressed rats. Our study revealed that elevation of body temperature also resulted in a significant increase of the concentration of vesicles released by erythrocytes in rats, pre-treated with PBS. This is an indication of a pathological impact of heat on the erythrocyte structure. Treatment of rats with EH completely protected their erythrocytes from this heat-induced pathology. Finally, exposure to heat stress conditions resulted in a significant increase of white blood cells in rats. In the group of animals pre-treated with EH before heat stress, the white blood cell count remained the same as in non-heated controls. These results showed the protective effect of the EH product in the prevention of complications, caused by heat stress.

  6. Assessment of heating rate and non-uniform heating in domestic microwave ovens.

    PubMed

    Pitchai, Krishnamoorthy; Birla, Sohan L; Jones, David; Subbiah, Jeyamkondan

    2012-01-01

    Due to the inherent nature of standing wave patterns of microwaves inside a domestic microwave oven cavity and varying dielectric properties of different food components, microwave heating produces non-uniform distribution of energy inside the food. Non-uniform heating is a major food safety concern in not-ready-to-eat (NRTE) microwaveable foods. In this study, we present a method for assessing heating rate and non-uniform heating in domestic microwave ovens. In this study a custom designed container was used to assess heating rate and non-uniform heating of a range of microwave ovens using a hedgehog of 30 T-type thermocouples. The mean and standard deviation of heating rate along the radial distance and sector of the container were measured and analyzed. The effect of the location of rings and sectors was analyzed using ANOVA to identify the best location for placing food on the turntable. The study suggested that the best location to place food in a microwave oven is not at the center but near the edge of the turntable assuming uniform heating is desired. The effect of rated power and cavity size on heating rate and non-uniform heating was also studied for a range of microwave ovens. As the rated power and cavity size increases, heating rate increases while non-uniform heating decreases. Sectors in the container also influenced heating rate (p < 0.0001), even though it did not have clear trend on heating rate. In general, sectors close to the magnetron tend to heat slightly faster than sectors away from the magnetron. However, the variation in heating rate among sectors was only 2 degrees C/min and considered not practically important. Overall heating performance such as mean heating rate and non-uniform heating did not significantly vary between the two replications that were performed 4 h apart. However, microwave ovens were inconsistent in producing the same heating patterns between the two replications that were performed 4 h apart.

  7. Heat Index in Migrant Farmworker Housing: Implications for Rest and Recovery From Work-Related Heat Stress

    PubMed Central

    Wiggins, Melinda F.; Chen, Haiying; Bischoff, Werner E.; Arcury, Thomas A.

    2013-01-01

    Although the health risk to farmworkers of working in hot conditions is recognized, potential for excessive heat exposure in housing affecting rest and recovery has been ignored. We assessed heat index in common and sleeping rooms in 170 North Carolina farmworker camps across a summer and examined associations with time of summer and air conditioning use. We recorded dangerous heat indexes in most rooms, regardless of time or air conditioning. Policies to reduce heat indexes in farmworker housing should be developed. PMID:23763392

  8. Heat index in migrant farmworker housing: implications for rest and recovery from work-related heat stress.

    PubMed

    Quandt, Sara A; Wiggins, Melinda F; Chen, Haiying; Bischoff, Werner E; Arcury, Thomas A

    2013-08-01

    Although the health risk to farmworkers of working in hot conditions is recognized, potential for excessive heat exposure in housing affecting rest and recovery has been ignored. We assessed heat index in common and sleeping rooms in 170 North Carolina farmworker camps across a summer and examined associations with time of summer and air conditioning use. We recorded dangerous heat indexes in most rooms, regardless of time or air conditioning. Policies to reduce heat indexes in farmworker housing should be developed.

  9. Prostaglandin E synthase interacts with inducible heat shock protein 70 after heat stress in bovine primary dermal fibroblast cells.

    PubMed

    Richter, Constanze; Viergutz, Torsten; Schwerin, Manfred; Weitzel, Joachim M

    2015-01-01

    Exposure to heat stress in dairy cows leads to undesired side effects that are reflected by complex alterations in endocrine parameters, such as reduced progesterone, estradiol, and thyroid hormone concentrations. These endocrine maladaptation leads to failure to resume cyclicity, a poor uterine environment and inappropriate immune responses in postpartum dairy cows. Prostaglandins (PG's) are lipid mediators, which serve as signal molecules in response to various external stimuli as well as to cell-specific internal signal molecules. A central role in PG synthesis plays prostaglandin E synthase (PGES) that catalyzes the isomerization of PGH2 to PGE2 .The present study was conducted to investigate heat stress associated PGES expression. Expression of PGES and inducible heat shock protein 70 (HSP70), as a putative chaperonic protein, was studied in bovine primary fibroblasts under different heat shock conditions. Bovine primary fibroblasts produce PGE2 at homoiothermical norm temperature (38.5°C in bovine), but reduce PGE2 production rates under extreme heat stress (at 45°C for 6 h). By contrast, PGE2 production rates are maintained after a milder heat stress (at 41.5°C for 6 h). PGE2 synthesis is abolished by application of cyclooxygenase inhibitor indomethacin, indicating de novo synthesis. Heat stress increases HSP70 but not PGES protein concentrations. HSP70 physically interacts with PGES and the PGES-HSP70 complex did not dissociate upon heat stress at 45°C even after returning the cells to 37°C. The PGE2 production negatively correlates with the portion of PGES-HSP70 complex. These results suggest a protein interaction between HSP70 and PGES in dermal fibroblast cells. Blockage of PGES protein by HSP70 seems to interfere with the regulatory processes essential for cellular adaptive protection. © 2014 International Society for Advancement of Cytometry. © 2014 International Society for Advancement of Cytometry.

  10. Biological stress responses to radio frequency electromagnetic radiation: are mobile phones really so (heat) shocking?

    PubMed

    Cotgreave, Ian A

    2005-03-01

    Cells phenotypically adapt to alterations in their intra- and extracellular environment via organised alterations to gene and protein expression. Many chemical and physical stimuli are known to drive such responses, including the induction of oxidative stress and heat shock. Increasing use of mobile telephones in our society, has brought focus on the potential for radio frequency (microwave) electromagnetic radiation to elicit biological stress responses, in association with potentially detrimental effects of this to human health. Here we review evidence suggesting altered gene and protein expression in response to such emissions, with particular focus on heat shock proteins. Non-thermal induction of heat shock proteins has been claimed by a number of investigations in in vitro cellular systems, and appears pleiotropic for many other regulatory events. However, many of these studies are flawed by inconsistencies in exposure models, cell types used and the independent reproducibility of the findings. Further, the paucity of evidence from in vivo experimentation is largely contradictory. Therefore, the validity of these effects in human health risk assessment remain unsubstantiated. Where possible, suggestions for further experimental clarification have been provided.

  11. Tensile and compressive stress-strain behavior of heat treated boron-aluminum

    NASA Technical Reports Server (NTRS)

    Kennedy, J. M.; Tenney, D. R.; Herakovich, C. T.

    1978-01-01

    An experimental study was conducted to assess the effects of heat treatment and cyclic mechanical loading on the tensile and compressive stress-strain behavior of six boron-aluminum composites having different laminate orientations and being subjected to different heat treatments. The heat treatments were as-fabricated, T6, and T6N consisting of T6 treatment followed by cryogenic quench in liquid nitrogen prior to testing. All laminates were tested in monotonic and cyclic compression, while the tensile-test data are taken from the literature for comparison purposes. It is shown that the linear elastic range of the T6- and T6N-condition specimens is larger than that of the as-fabricated specimens, and that cyclic loading in tension or compression strain hardens the specimens and extends the linear elastic range. For laminates containing 0-deg plies, the stress-strain behavior upon unloading is found to be nonlinear, whereas the other laminates exhibit a linear behavior upon unloading. Specimens in the T6 and T6N conditions show higher strain hardening than the as-fabricated specimens.

  12. The efficacy of radiant heat controls on workers' heat stress around the blast furnace of a steel industry.

    PubMed

    Giahi, Omid; Darvishi, Ebrahim; Aliabadi, Mohsen; Khoubi, Jamshid

    2015-01-01

    Workers' exposure to excessive heat in molten industries is mainly due to radiant heat from hot sources. The aim of this study was to evaluate the efficacy of radiant heat controls on workers heat stress around a typical blast furnace. Two main interventions were applied for reducing radiant heat around the blast furnace of a steel industry located in western Iran. These included using a heat absorbing system in the furnace body and installing reflective aluminum barrier in the main workstation. Heat stress indexes were measured before and after each intervention using the digital WBGT-meter. The results showed MRT and WBGT indexes decreased by 20 °C and 3.9 °C, respectively after using heat absorbing system and also decreased by 18.6 °C and 2.5 °C, respectively after installing a reflective barrier. These indexes decrease by 26.5 °C and 5.2 °C, respectively due to the simultaneous application of the two interventions which were statistically significant (p < 0.001). The core body temperature of workers decreased by 2.6 °C after the application of interventions which was also significant (p < 0.05). The results confirmed heat control at source can be considered as a first solution for reducing radiant heat of blast furnaces. However, the simultaneous application of interventions could noticeably reduce worker heat stress. The results provide reliable information in order to implement the effective heat controls in typical hot steel industries.

  13. Modeling analysis of women litter bearers during heat stress.

    PubMed

    Santee, W R; Kraning, K K; Matthew, W T

    1999-04-01

    The majority of military physiological studies have been conducted on men. Consequently most physiological modeling is based on male performance. This study obtained data on women performing military tasks under hot-dry field conditions. Results for rectal temperature (Tre) and heart rate (HR) were compared with values generated by the SCENARIO physiological model. Three skin surface temperatures, Tre, and HR were collected while four female subjects participated in walking or two-person litter carriage (68 kg load) in regular battledress and with full chemical protection at Yuma Proving Ground, AZ. Metabolic rates were measured prior to the test days. Meteorological data were also recorded. Overall, the potential for thermal stress decreased over the four test days, with air temperature dropping from 39.4 degrees to 35.5 degrees C. Whole body metabolic values were 364 W (walking), 91 W (standing), and 492 W (litter carriage). Endurance times (160 min maximum) for walking were 140 min in Mission Oriented Protective Posture (MOPP)-0 and 29 min in MOPP-4. For litter carriage, the average times were 59 min in MOPP-0 and 43 min in MOPP-4. A comparison of root mean squared deviation (RMSD) to the mean standard deviation for Tre demonstrated a good fit between the model and mean observed values for the MOPP-0 condition. Observed HRs were greater than predicted by the model. The modeling results support a conclusion that factors other than heat stress limited litter carriage in MOPP-0. Analysis of calculated values for Tre using RMSD supports an assumption that the male-based SCENARIO may be applicable to females.

  14. Management of climatic heat stress risk in construction: a review of practices, methodologies, and future research.

    PubMed

    Rowlinson, Steve; Yunyanjia, Andrea; Li, Baizhan; Chuanjingju, Carrie

    2014-05-01

    Climatic heat stress leads to accidents on construction sites brought about by a range of human factors emanating from heat induced illness, and fatigue leading to impaired capability, physical and mental. It is an occupational characteristic of construction work in many climates and the authors take the approach of re-engineering the whole safety management system rather than focusing on incremental improvement, which is current management practice in the construction industry. From a scientific viewpoint, climatic heat stress is determined by six key factors: (1) air temperature, (2) humidity, (3) radiant heat, and (4) wind speed indicating the environment, (5) metabolic heat generated by physical activities, and (6) "clothing effect" that moderates the heat exchange between the body and the environment. By making use of existing heat stress indices and heat stress management processes, heat stress risk on construction sites can be managed in three ways: (1) control of environmental heat stress exposure through use of an action-triggering threshold system, (2) control of continuous work time (CWT, referred by maximum allowable exposure duration) with mandatory work-rest regimens, and (3) enabling self-paced working through empowerment of employees. Existing heat stress practices and methodologies are critically reviewed and the authors propose a three-level methodology for an action-triggering, localized, simplified threshold system to facilitate effective decisions by frontline supervisors. The authors point out the need for "regional based" heat stress management practices that reflect unique climatic conditions, working practices and acclimatization propensity by local workers indifferent geographic regions. The authors set out the case for regional, rather than international, standards that account for this uniqueness and which are derived from site-based rather than laboratory-based research. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Temperature and blood flow distribution in the human leg during passive heat stress

    PubMed Central

    Chiesa, Scott T.; Trangmar, Steven J.

    2016-01-01

    The influence of temperature on the hemodynamic adjustments to direct passive heat stress within the leg's major arterial and venous vessels and compartments remains unclear. Fifteen healthy young males were tested during exposure to either passive whole body heat stress to levels approaching thermal tolerance [core temperature (Tc) + 2°C; study 1; n = 8] or single leg heat stress (Tc + 0°C; study 2; n = 7). Whole body heat stress increased perfusion and decreased oscillatory shear index in relation to the rise in leg temperature (Tleg) in all three major arteries supplying the leg, plateauing in the common and superficial femoral arteries before reaching severe heat stress levels. Isolated leg heat stress increased arterial blood flows and shear patterns to a level similar to that obtained during moderate core hyperthermia (Tc + 1°C). Despite modest increases in great saphenous venous (GSV) blood flow (0.2 l/min), the deep venous system accounted for the majority of returning flow (common femoral vein 0.7 l/min) during intense to severe levels of heat stress. Rapid cooling of a single leg during severe whole body heat stress resulted in an equivalent blood flow reduction in the major artery supplying the thigh deep tissues only, suggesting central temperature-sensitive mechanisms contribute to skin blood flow alone. These findings further our knowledge of leg hemodynamic responses during direct heat stress and provide evidence of potentially beneficial vascular alterations during isolated limb heat stress that are equivalent to those experienced during exposure to moderate levels of whole body hyperthermia. PMID:26823344

  16. [Oxygen deficiency increases invasive activity and resistance of Yersinia pseudotuberculosis to heat stress].

    PubMed

    Bakholdina, S I; Shubin, F N; Solov'eva, T F

    2009-01-01

    To study effects of oxygen availability and presence of glucose in growth medium on adhesive and invasive properties of Yersinia pseudotuberculosis as well as its resistance to heat stress during sharp rise of temperature from 8 degrees C to 37 degrees C. Yersinia pseudotuberculosis was grown on nutrient broth with or without glucose at 8 degrees C and two regimen of aeration--during intensive stirring (180 rpm) and without it. Adhesive and invasive activities were studied on the model of HeLa human cell line. Effects of temperature stress on the bacterial growth were assessed from growth curves plotted on the basis of quantity of colony-forming cells. Morphology of bacterial cells was studied by electron microscopy. It was shown that cultivation of Y. pseudotuberculosis at 8 degrees C and low aeration increases its adhesive and invasive activity as well resistance to heat stress. Adding of glucose to growth medium decreases invasiveness of Y. pseudotuberculosis irrespective to aeration regimen. Oxygen deficiency during low temperature of growth promotes increasing of pathogenic potential of Y. pseudotuberculosis. Obtained data are useful for solving practical problems associated with development of prevention measures for pseudotuberculosis as well with food processing and storage.

  17. BAG3 affects the nucleocytoplasmic shuttling of HSF1 upon heat stress

    SciTech Connect

    Jin, Young-Hee; Ahn, Sang-Gun; Kim, Soo-A.

    2015-08-21

    Bcl2-associated athoanogene (BAG) 3 is a member of the co-chaperone BAG family. It is induced by stressful stimuli such as heat shock and heavy metals, and it regulates cellular adaptive responses against stressful conditions. In this study, we identified a novel role for BAG3 in regulating the nuclear shuttling of HSF1 during heat stress. The expression level of BAG3 was induced by heat stress in HeLa cells. Interestingly, BAG3 rapidly translocalized to the nucleus upon heat stress. Immunoprecipitation assay showed that BAG3 interacts with HSF1 under normal and stressed conditions and co-translocalizes to the nucleus upon heat stress. We also demonstrated that BAG3 interacts with HSF1 via its BAG domain. Over-expression of BAG3 down-regulates the level of nuclear HSF1 by exporting it to the cytoplasm during the recovery period. Depletion of BAG3 using siRNA results in reduced nuclear HSF1 and decreased Hsp70 promoter activity. BAG3 in MEF(hsf1{sup −/−}) cells actively translocalizes to the nucleus upon heat stress suggesting that BAG3 plays a key role in the processing of the nucleocytoplasmic shuttling of HSF1 upon heat stress. - Highlights: • The expression level of BAG3 is induced by heat stress. • BAG3 translocates to the nucleus upon heat stress. • BAG3 interacts with HSF1 and co-localizes to the nucleus. • BAG3 is a key regulator for HSF1 nuclear shuttling.

  18. Heat stress hardening of oriental armyworms is induced by a transient elevation of reactive oxygen species during sublethal stress.

    PubMed

    Matsumura, Takashi; Matsumoto, Hitoshi; Hayakawa, Yoichi

    2017-09-05

    Pre-exposure to mild heat stress enhances the thermotolerance of insects. Stress hardening is a beneficial physiological plasticity, but the mechanism underlying it remains elusive. Here we report that reactive oxygen species (ROS) concentrations were quickly and transiently elevated in the armyworms, Mythimna separata, by exposing them to 40°C, but not other tested temperatures. Larvae exposed to 40°C had subsequently elevated antioxidant activity and the highest survival of all tested heating conditions. The elevation of ROS after lethal heating at 44°C for 1 h was approximately twofold compared to heating at 40°C. Injection of an optimal amount of hydrogen peroxide (H2 O2 ) similarly caused sequential elevation of ROS and antioxidant activity in the test larval hemolymph, which led to significantly enhanced survival after lethal heat stress. The H2 O2 -induced thermotolerance was abolished by coinjection of potent antioxidants such as ascorbic acid or N-acetylcysteine. Both preheating at 40°C and H2 O2 injection enhanced expression of genes encoding superoxide dismutase 1, catalase, and heat shock protein 70 in the fat body of test larvae, indicating the adequate heat stress induced a transient elevation of ROS, followed by upregulation of antioxidant activity. We infer that thermal stress hardening is induced by a small timely ROS elevation that triggers a reduction-oxidation signaling mechanism. © 2017 Wiley Periodicals, Inc.

  19. Dietary chromium methionine supplementation could alleviate immunosuppressive effects of heat stress in broiler chicks.

    PubMed

    Jahanian, R; Rasouli, E

    2015-07-01

    The present study was conducted to investigate the effects of dietary supplementation of chromium methionine (CrMet) on performance, immune responses, and stress status of broiler chicks subjected to heat-stress conditions. A total of 450 day-old Ross 308 broiler chicks were randomly distributed between 5 replicate pens (15 birds each) of 6 experimental treatments according to a 2 × 3 factorial arrangement of treatments including 2 temperature conditions (thermoneutral and heat stress) and 3 supplemental Cr levels (0, 500, and 1,000 μg/kg as CrMet). For induction of heat stress, the house temperature was set at 35 ± 2°C from 15 to 42 d of age. Results showed that the chicks subjected to heat-stress condition had lower (P < 0.01) feed intake, BW gain, and deteriorated (P < 0.05) feed conversion values compared with those kept in the thermoneutral house. Dietary supplementation with CrMet increased (P < 0.01) feed intake and improved (P < 0.01) weight gain and feed efficiency. There were significant Cr level × temperature interactions, so that inclusion of CrMet into the diets was more effective in heat-stressed chicks. Exposure to heat stress suppressed (P < 0.01) cutaneous hypersensivity response to phytohemagglutinin-P injection at 30 d of age, and dietary supplementation of 500 μg Cr/kg induced (P < 0.05) this response, with the greater impacts in heat-stressed chicks, resulting in a significant (P < 0.01) Cr × temperature interaction. Antibody responses against Newcastle and infectious bronchitis disease viruses were diminished (P < 0.01) in heat-stressed chicks. Dietary inclusion of CrMet improved (P < 0.05) antibody responses to different immunostimulants, and this effect was more pronounced in heat-stressed chicks. Exposure to heat stress caused a significant (P < 0.05) decrease in the proportion of helper (CD4+) T lymphocytes and increased cytotoxic (CD8+) T lymphocytes, resulting in a decreased (P < 0.01) CD4+ to CD8+ ratio in peripheral blood

  20. ABA Is Required for Plant Acclimation to a Combination of Salt and Heat Stress

    PubMed Central

    Suzuki, Nobuhiro; Bassil, Elias; Hamilton, Jason S.; Inupakutika, Madhuri A.; Zandalinas, Sara Izquierdo; Tripathy, Deesha; Luo, Yuting; Dion, Erin; Fukui, Ginga; Kumazaki, Ayana; Nakano, Ruka; Rivero, Rosa M.; Verbeck, Guido F.; Azad, Rajeev K.; Blumwald, Eduardo; Mittler, Ron

    2016-01-01

    Abiotic stresses such as drought, heat or salinity are a major cause of yield loss worldwide. Recent studies revealed that the acclimation of plants to a combination of different environmental stresses is unique and cannot be directly deduced from studying the response of plants to each of the different stresses applied individually. Here we report on the response of Arabidopsis thaliana to a combination of salt and heat stress using transcriptome analysis, physiological measurements and mutants deficient in abscisic acid, salicylic acid, jasmonic acid or ethylene signaling. Arabidopsis plants were found to be more susceptible to a combination of salt and heat stress compared to each of the different stresses applied individually. The stress combination resulted in a higher ratio of Na+/K+ in leaves and caused the enhanced expression of 699 transcripts unique to the stress combination. Interestingly, many of the transcripts that specifically accumulated in plants in response to the salt and heat stress combination were associated with the plant hormone abscisic acid. In accordance with this finding, mutants deficient in abscisic acid metabolism and signaling were found to be more susceptible to a combination of salt and heat stress than wild type plants. Our study highlights the important role abscisic acid plays in the acclimation of plants to a combination of two different abiotic stresses. PMID:26824246

  1. ABA Is Required for Plant Acclimation to a Combination of Salt and Heat Stress.

    PubMed

    Suzuki, Nobuhiro; Bassil, Elias; Hamilton, Jason S; Inupakutika, Madhuri A; Zandalinas, Sara Izquierdo; Tripathy, Deesha; Luo, Yuting; Dion, Erin; Fukui, Ginga; Kumazaki, Ayana; Nakano, Ruka; Rivero, Rosa M; Verbeck, Guido F; Azad, Rajeev K; Blumwald, Eduardo; Mittler, Ron

    2016-01-01

    Abiotic stresses such as drought, heat or salinity are a major cause of yield loss worldwide. Recent studies revealed that the acclimation of plants to a combination of different environmental stresses is unique and cannot be directly deduced from studying the response of plants to each of the different stresses applied individually. Here we report on the response of Arabidopsis thaliana to a combination of salt and heat stress using transcriptome analysis, physiological measurements and mutants deficient in abscisic acid, salicylic acid, jasmonic acid or ethylene signaling. Arabidopsis plants were found to be more susceptible to a combination of salt and heat stress compared to each of the different stresses applied individually. The stress combination resulted in a higher ratio of Na+/K+ in leaves and caused the enhanced expression of 699 transcripts unique to the stress combination. Interestingly, many of the transcripts that specifically accumulated in plants in response to the salt and heat stress combination were associated with the plant hormone abscisic acid. In accordance with this finding, mutants deficient in abscisic acid metabolism and signaling were found to be more susceptible to a combination of salt and heat stress than wild type plants. Our study highlights the important role abscisic acid plays in the acclimation of plants to a combination of two different abiotic stresses.

  2. Assessment of heat generation during implant insertion.

    PubMed

    Sumer, Mahmut; Keskiner, Ilker; Mercan, Ugur; Misir, Ferhat; Cankaya, Soner

    2014-09-01

    Many studies have investigated the heat generated during implant preparation, but data are needed to better predict heat generation during implant insertion. The purpose of this study was to measure the heat generated during insertion of an implant at speeds of 30, 50, and 100 rpm, and with manual insertion. Sixty-four uniform fresh bovine femoral cortical bone specimens were used. After the cortical bone was drilled, 3 different implant insertion speeds and the manual insertion of the implant were evaluated for 2 different implant diameters. The temperature was measured with 2 Teflon-insulated, type K thermocouples. Data were analyzed by 2-way ANOVA, and the Tukey honestly significant difference test (α=.05). The highest thermal change for 4.1-mm-diameter implants was found at a speed of 100 rpm (9.81°C ±2.29°C), and the lowest thermal change was 3.69°C ±0.85°C at a speed of 30 rpm. A statistically significant difference was found between 100 rpm and the other 3 insertion procedures. The highest thermal change for a 4.8-mm-diameter implant was found at a speed of 100 rpm (8.79°C ±1.53°C), and the lowest thermal change was 4.48°C ±0.85°C at a speed of 30 rpm. No statistical difference was observed with manual, 30 rpm, and 50 rpm; however, a statistically significant difference was found between 100 rpm and the other 3 insertion procedures. Manual implant insertion and at speeds of 30 rpm and 50 rpm generated lower heat compared with insertion at 100 rpm. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  3. Effect of heat stress on production parameters and immune responses of commercial laying hens.

    PubMed

    Mashaly, M M; Hendricks, G L; Kalama, M A; Gehad, A E; Abbas, A O; Patterson, P H

    2004-06-01

    The present study was conducted to determine the adverse effects of high temperature and humidity not only on live performance and egg quality but also on immune function in commercial laying hens. One hundred eighty 31-wk-old laying hens at peak production were used in this study. Hens were housed in cages (15 cages of 4 birds/cage) in each of 3 environmental chambers and received 1 of 3 treatments. The 3 treatments were control (average temperature and relative humidity), cyclic (daily cyclic temperature and humidity), and heat stress (constant heat and humidity) for 5 wk. Different production and immune parameters were measured. Body weight and feed consumption were significantly reduced in hens in the heat stress group. Egg production, egg weight, shell weight, shell thickness, and specific gravity were significantly inhibited among hens in the heat stress group. Likewise, total white blood cell (WBC) counts and antibody production were significantly inhibited in hens in the heat stress group. In addition, mortality was higher in the heat stress group compared to the cyclic and control groups. Even though T- and B-lymphocyte activities were not significantly affected by any of the treatments, lymphocytes from hens in the heat stress group had the least activity at 1 wk following treatment. These results indicate that heat stress not only adversely affects production performance but also inhibits immune function.

  4. Heat stress management program improving worker health and operational effectiveness: a case study.

    PubMed

    Huss, Rosalyn G; Skelton, Scott B; Alvis, Kimberly L; Shane, Leigh A

    2013-03-01

    Heat stress monitoring is a vital component of an effective health and safety program when employees work in exceptionally warm environments. Workers at hazardous waste sites often wear personal protective equipment (PPE), which increases the body heat stress load. No specific Occupational Safety and Health Administration (OSHA) regulations address heat stress; however, OSHA does provide several guidance documents to assist employers in addressing this serious workplace health hazard. This article describes a heat stress and surveillance plan implemented at a hazardous waste site as part of the overall health and safety program. The PPE requirement for work at this site, coupled with extreme environmental temperatures, made heat stress a significant concern. Occupational health nurses and industrial hygienists developed a monitoring program for heat stress designed to prevent the occurrence of significant heat-related illness in site workers. The program included worker education on the signs of heat-related illness and continuous physiologic monitoring to detect early signs of heat-related health problems. Biological monitoring data were collected before workers entered the exclusion zone and on exiting the zone following decontamination. Sixty-six site workers were monitored throughout site remediation. More than 1,700 biological monitoring data points were recorded. Outcomes included improved worker health and safety, and increased operational effectiveness. Copyright 2013, SLACK Incorporated.

  5. Exercise intensity prescription during heat stress: A brief review.

    PubMed

    Wingo, J E

    2015-06-01

    Exercise intensity can be prescribed using a variety of indices, such as rating of perceived exertion, heart rate, levels of absolute intensity (e.g., metabolic equivalents), and levels of relative intensity [e.g., percentage of maximal aerobic capacity (% V ˙ O 2 m a x ) or percentage of oxygen uptake reserve (% V ˙ O 2 R )]. Heart rate has a linear relationship with oxygen uptake, is easy to measure, and requires relatively inexpensive monitoring equipment, so it is commonly used to monitor exercise intensity. During heat stress, however, cardiovascular adjustments - including a rise in heart rate that is disproportionate to absolute intensity - result in diminished aerobic capacity and performance. These adjustments include cardiovascular drift, the progressive rise in heart rate and fall in stroke volume over time during prolonged, constant-rate exercise. A variety of factors have been shown to modulate the magnitude of cardiovascular drift, e.g., hyperthermia, dehydration, exercise intensity, and ambient temperature. Regardless of the mode of manipulation, decreases in stroke volume with cardiovascular drift are associated with proportionally similar decreases in V ˙ O 2 m a x , which affects the relationship between heart rate and relative metabolic intensity (% V ˙ O 2 m a x or % V ˙ O 2 R ). This review summarizes the current state of knowledge regarding the influence of cardiovascular drift and reduced V ˙ O 2 m a x on exercise intensity prescription in hot conditions. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Shiftwork and heat stress in an intensive care unit.

    PubMed

    Liu, L W; Costa, G; Schallenberg, G; Trinco, R

    1994-01-01

    This paper reported the results of investigation on shiftwork and heat stress in an intensive care unit. The aim of this study was to analyse the physiological strain of nurses during the three shifts (Morning, Afternoon, Night) in relation to the specific microclimatic conditions and job activities. 8 professional nurses (6 female and 2 male), aged between 21 and 38 years (mean 29.8 +/- 5.6 years), having from 3 to 18 years service, were monitored throughout a complete working cycle of 4 days. They worked on a three shift system at fast rotation. Their working environment was an independent unit for intensive care and expert surgical treatment which was entirely air conditioned. The observation indexes included: twenty-five blood parameters, ten urine parameters, net cardiac cost and relation cardiac cost, etc. The results of the investigation have not evidenced serious alterations of the psycho-physical conditions of the nurses, but do pointed out some problems pertaining both to the environmental and physiological conditions.

  7. Gene expression changes in response to aging compared to heat stress, oxidative stress and ionizing radiation in Drosophila melanogaster

    PubMed Central

    Landis, Gary; Shen, Jie; Tower, John

    2012-01-01

    Gene expression changes in response to aging, heat stress, hyperoxia, hydrogen peroxide, and ionizing radiation were compared using microarrays. A set of 18 genes were up-regulated across all conditions, indicating a general stress response shared with aging, including the heat shock protein (Hsp) genes Hsp70, Hsp83 and l(2)efl, the glutathione-S-transferase gene GstD2, and the mitochondrial unfolded protein response (mUPR) gene ref(2)P. Selected gene expression changes were confirmed using quantitative PCR, Northern analysis and GstD-GFP reporter constructs. Certain genes were altered in only a subset of the conditions, for example, up-regulation of numerous developmental pathway and signaling genes in response to hydrogen peroxide. While aging shared features with each stress, aging was more similar to the stresses most associated with oxidative stress (hyperoxia, hydrogen peroxide, ionizing radiation) than to heat stress. Aging is associated with down-regulation of numerous mitochondrial genes, including electron-transport-chain (ETC) genes and mitochondrial metabolism genes, and a sub-set of these changes was also observed upon hydrogen peroxide stress and ionizing radiation stress. Aging shared the largest number of gene expression changes with hyperoxia. The extensive down-regulation of mitochondrial and ETC genes during aging is consistent with an aging-associated failure in mitochondrial maintenance, which may underlie the oxidative stress-like and proteotoxic stress-like responses observed during aging. PMID:23211361

  8. Gene expression changes in response to aging compared to heat stress, oxidative stress and ionizing radiation in Drosophila melanogaster.

    PubMed

    Landis, Gary; Shen, Jie; Tower, John

    2012-11-01

    Gene expression changes in response to aging, heat stress, hyperoxia, hydrogen peroxide, and ionizing radiation were compared using microarrays. A set of 18 genes were up-regulated across all conditions, indicating a general stress response shared with aging, including the heat shock protein (Hsp) genes Hsp70, Hsp83 and l(2)efl, the glutathione-S-transferase gene GstD2, and the mitochondrial unfolded protein response (mUPR) gene ref(2)P. Selected gene expression changes were confirmed using quantitative PCR, Northern analysis and GstD-GFP reporter constructs. Certain genes were altered in only a subset of the conditions, for example, up-regulation of numerous developmental pathway and signaling genes in response to hydrogen peroxide. While aging shared features with each stress, aging was more similar to the stresses most associated with oxidative stress (hyperoxia, hydrogen peroxide, ionizing radiation) than to heat stress. Aging is associated with down-regulation of numerous mitochondrial genes, including electron-transport-chain (ETC) genes and mitochondrial metabolism genes, and a sub-set of these changes was also observed upon hydrogen peroxide stress and ionizing radiation stress. Aging shared the largest number of gene expression changes with hyperoxia. The extensive down-regulation of mitochondrial and ETC genes during aging is consistent with an aging-associated failure in mitochondrial maintenance, which may underlie the oxidative stress-like and proteotoxic stress-like responses observed during aging.

  9. Heart rate variability during high heat stress: a comparison between young and older adults with and without Type 2 diabetes.

    PubMed

    Carrillo, Andres E; Flouris, Andreas D; Herry, Christophe L; Poirier, Martin P; Boulay, Pierre; Dervis, Sheila; Friesen, Brian J; Malcolm, Janine; Sigal, Ronald J; Seely, Andrew J E; Kenny, Glen P

    2016-10-01

    We examined whether older individuals with and without Type 2 diabetes (T2D) experience differences in heart rate variability (HRV) during a 3-h exposure to high heat stress compared with young adults. Young (Young; n = 22; 23 ± 3 yr) and older individuals with (T2D; n = 11; 59 ± 9 yr) and without (Older; n = 25; 63 ± 5 yr) T2D were exposed to heat stress (44°C, 30% relative humidity) for 3 h. Fifty-five HRV measures were assessed for 15 min at baseline and at minutes 82.5-97.5 (Mid) and minutes 165-180 (End) during heat stress. When compared with Young, a similar number of HRV indices were significantly different (P < 0.05) in Older (Baseline: 35; Mid: 29; End: 32) and T2D (Baseline: 31; Mid: 30; End: 27). In contrast, the number of HRV indices significantly different (P < 0.05) between Older and T2D were far fewer (Baseline: 13, Mid: 1, End: 3). Within-group analyses demonstrated a greater change in the Young group's HRV during heat stress compared with Older and T2D; the number of significantly different (P < 0.05) HRV indices between baseline and End were 42, 29, and 20, for Young, Older, and T2D, respectively. Analysis of specific HRV domains suggest that the Young group experienced greater sympathetic activity during heat stress compared with Older and T2D. In conclusion, when compared with young, older individuals with and without T2D demonstrate low HRV at baseline and less change in HRV (including an attenuated sympathetic response) during 3 h high heat stress, potentially contributing to impaired thermoregulatory function. Copyright © 2016 the American Physiological Society.

  10. BREEDING AND GENETICS SYMPOSIUM: Resilience and lessons from studies in genetics of heat stress.

    PubMed

    Misztal, I

    2017-04-01

    Production environments are expected to change, mostly to a hotter climate but also possibly more extreme and drier. Can the current generation of farm animals cope with the changes or should it be specifically selected for changing conditions? In general, genetic selection produces animals with a smaller environmental footprint but also with smaller environmental flexibility. Some answers are coming from heat-stress research across species, with heat tolerance partly understood as a greater environmental flexibility. Specific studies in various species show the complexities of defining and selecting for heat tolerance. In Holsteins, the genetic component for effect of heat stress on production approximately doubles in second and quadruples in third parity. Cows with elevated body temperature have the greatest production under heat stress but probably are at risk for increased mortality. In hot but less intensive environments, the effect of heat stress on production is minimal, although the negative effect on fertility remains. Mortality peaks under heat stress and increases with parity. In Angus, the effect of heat stress is stronger only in selected regions, probably because of adaptation of calving seasons to local conditions and crossbreeding. Genetically, the direct effect shows variability because of heat stress, but the maternal effect does not, probably because dams shield calves from environmental challenges. In pigs, the effect of heat stress is strong for commercial farms but almost nothing for nucleus farms, which have lower pig density and better heat abatement. Under intensive management, heat stress is less evident in drier environments because of more efficient cooling. A genetic component of heat stress exists, but it is partly masked by improving management and selection based on data from elite farms. Genetic selection may provide superior identification of heat-tolerant animals, but a few cycles may be needed for clear results. Also, simple

  11. Expression of HSPs: an adaptive mechanism during long-term heat stress in goats ( Capra hircus)

    NASA Astrophysics Data System (ADS)

    Dangi, Satyaveer Singh; Gupta, Mahesh; Dangi, Saroj K.; Chouhan, Vikrant Singh; Maurya, V. P.; Kumar, Puneet; Singh, Gyanendra; Sarkar, Mihir

    2015-08-01

    Menacing global rise in surface temperature compelled more focus of research over understanding heat stress response mechanism of animals and mitigation of heat stress. Twenty-four goats divided into four groups ( n = 6) such as NHS (non-heat-stressed), HS (heat-stressed), HS + VC (heat-stressed administered with vitamin C), and HS + VE + Se (heat-stressed administered with vitamin E and selenium). Except NHS group, other groups were exposed to repeated heat stress (42 °C) for 6 h on 16 consecutive days. Blood samples were collected at the end of heat exposure on days 1, 6, 11, and 16. When groups compared between days, expression of all heat shock proteins (HSPs) showed a similar pattern as first peak on day 1, reached to basal level on the sixth day, and followed by second peak on day 16. The relative messenger RNA (mRNA) and protein expression of HSP 60, HSP70, and HSP90 was observed highest ( P < 0.05) in HS group, followed by antioxidant-administered group on days 1 and 16, which signifies that antioxidants have dampening effect on HSP expression. HSP105/110 expression was highest ( P < 0.05) on day 16. We conclude that HSP expression pattern is at least two-peak phenomenon, i.e., primary window of HSP protection on the first day followed by second window of protection on day 16. HSP60, HSP70, and HSP90 play an important role during the initial phase of heat stress acclimation whereas HSP105/110 joins this cascade at later phase. Antioxidants may possibly attenuate the HSP expression by reducing the oxidative stress.

  12. Expression of HSPs: an adaptive mechanism during long-term heat stress in goats (Capra hircus).

    PubMed

    Dangi, Satyaveer Singh; Gupta, Mahesh; Dangi, Saroj K; Chouhan, Vikrant Singh; Maurya, V P; Kumar, Puneet; Singh, Gyanendra; Sarkar, Mihir

    2015-08-01

    Menacing global rise in surface temperature compelled more focus of research over understanding heat stress response mechanism of animals and mitigation of heat stress. Twenty-four goats divided into four groups (n = 6) such as NHS (non-heat-stressed), HS (heat-stressed), HS + VC (heat-stressed administered with vitamin C), and HS + VE + Se (heat-stressed administered with vitamin E and selenium). Except NHS group, other groups were exposed to repeated heat stress (42 °C) for 6 h on 16 consecutive days. Blood samples were collected at the end of heat exposure on days 1, 6, 11, and 16. When groups compared between days, expression of all heat shock proteins (HSPs) showed a similar pattern as first peak on day 1, reached to basal level on the sixth day, and followed by second peak on day 16. The relative messenger RNA (mRNA) and protein expression of HSP 60, HSP70, and HSP90 was observed highest (P < 0.05) in HS group, followed by antioxidant-administered group on days 1 and 16, which signifies that antioxidants have dampening effect on HSP expression. HSP105/110 expression was highest (P < 0.05) on day 16. We conclude that HSP expression pattern is at least two-peak phenomenon, i.e., primary window of HSP protection on the first day followed by second window of protection on day 16. HSP60, HSP70, and HSP90 play an important role during the initial phase of heat stress acclimation whereas HSP105/110 joins this cascade at later phase. Antioxidants may possibly attenuate the HSP expression by reducing the oxidative stress.

  13. Heat stress-induced memory impairment is associated with neuroinflammation in mice.

    PubMed

    Lee, Wonil; Moon, Minho; Kim, Hyo Geun; Lee, Tae Hee; Oh, Myung Sook

    2015-05-23

    Heat stress induces many pathophysiological responses and has a profound impact on brain structure. It has been demonstrated that exposure to high temperature induces cognitive impairment in experimental animals and humans. Although the effects of heat stress have long been studied, the mechanisms by which heat stress affects brain structure and cognition not well understood. In our longitudinal study of mice exposed to heat over 7, 14, or 42 days, we found that heat stress time dependently impaired cognitive function as determined by Y-maze, passive avoidance, and novel object recognition tests. To elucidate the histological mechanism by which thermal stress inhibited cognitive abilities, we examined heat stress-induced inflammation in the hippocampus. In mice subjected to heat exposure, we found: 1) an increased number of glial fibrillary acid protein (GFAP)- and macrophage-1 antigen (Mac-1)-positive cells, 2) up-regulated nuclear factor (NF)-κB, a master regulator of inflammation, and 3) marked increases in cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and cytokine interleukin (IL)-1β and tumor necrosis factor (TNF)-α in the mouse hippocampus. We also observed that neuronal and synaptic densities were degenerated significantly in hippocampal regions after heat exposure, as determined by histological analysis of neuronal nuclei (NeuN), postsynaptic density protein 95 (PSD-95), and synaptophysin expression. Moreover, in heat-exposed mice, we found that the number of cells positive for doublecortin (DCX), a marker of neurogenesis, was significantly decreased compared with control mice. Finally, anti-inflammatory agent minocycline inhibited the heat stress-induced cognitive deficits and astogliosis in mice. Together, these findings suggest that heat stress can lead to activation of glial cells and induction of inflammatory molecules in the hippocampus, which may act as causative factors for memory loss, neuronal death, and impaired adult

  14. Steady-state chlorophyll fluorescence (Fs) as a tool to monitor plant heat and drought stress

    NASA Astrophysics Data System (ADS)

    Cendrero Mateo, M.; Carmo-Silva, A.; Salvucci, M.; Moran, S. M.; Hernandez, M.

    2012-12-01

    Crop yield decreases when photosynthesis is limited by heat or drought conditions. Yet farmers do not monitor crop photosynthesis because it is difficult to measure at the field scale in real time. Steady-state chlorophyll fluorescence (Fs) can be used at the field level as an indirect measure of photosynthetic activity in both healthy and physiologically-perturbed vegetation. In addition, Fs can be measured by satellite-based sensors on a regular basis over large agricultural regions. In this study, plants of Camelina sativa grown under controlled conditions were subjected to heat and drought stress. Gas exchange and Fs were measured simultaneously with a portable photosynthesis system under light limiting and saturating conditions. Results showed that Fs was directly correlated with net CO2 assimilation (A) and inversely correlated with non-photochemical quenching (NPQ). Analysis of the relationship between Fs and Photosynthetically Active Radiation (PAR) revealed significant differences between control and stressed plants that could be used to track the status, resilience, and recovery of photochemical processes. In summary, the results provide evidence that Fs measurements, even without normalization, are an easy means to monitor changes in plant photosynthesis, and therefore, provide a rapid assessment of plant stress to guide farmers in resource applications. Figure1. Net CO2 assimilation rate (A) of Camelina sativa plants under control conditions and after heat stress exposure for 1 or 3 days (1d-HS and 3d-HS, respectively) (right) and control, drought and re-watering conditions (left). Conditions for infra-red gas analysis were: reference CO2 = 380 μmol mol-1, PPFD = 500 μmol m-2 s-1 and Tleaf set to 25°C (control, drought and re-water) or 35°C (HS). Different letters denote significant differences at the α=0.05 level. Values are means±SEM (n=10). Figure 2. Stable chlorophyll fluorescence (Fs) of Camelina sativa plants under control conditions and

  15. The development of the Hong Kong Heat Index for enhancing the heat stress information service of the Hong Kong Observatory.

    PubMed

    Lee, K L; Chan, Y H; Lee, T C; Goggins, William B; Chan, Emily Y Y

    2016-07-01

    This paper presents a study to develop a heat index, for use in hot and humid sub-tropical climate in Hong Kong. The study made use of hospitalization data and heat stress measurement data in Hong Kong from 2007 to 2011. The heat index, which is called Hong Kong Heat Index (HKHI), is calculated from the natural wet bulb temperature, the globe temperature, and the dry bulb temperature together with a set of coefficients applicable to the high humidity condition in the summer of Hong Kong. Analysis of the response of hospitalization rate to variation in HKHI and two other heat indices, namely Wet Bulb Globe Temperature (WBGT) and Net Effective Temperature (NET), revealed that HKHI performed generally better than WBGT and NET in reflecting the heat stress impact on excess hospitalization ratio in Hong Kong. Based on the study results, two reference criteria of HKHI were identified to establish a two-tier approach for the enhancement of the heat stress information service in Hong Kong.

  16. The development of the Hong Kong Heat Index for enhancing the heat stress information service of the Hong Kong Observatory

    NASA Astrophysics Data System (ADS)

    Lee, K. L.; Chan, Y. H.; Lee, T. C.; Goggins, William B.; Chan, Emily Y. Y.

    2016-07-01

    This paper presents a study to develop a heat index, for use in hot and humid sub-tropical climate in Hong Kong. The study made use of hospitalization data and heat stress measurement data in Hong Kong from 2007 to 2011. The heat index, which is called Hong Kong Heat Index (HKHI), is calculated from the natural wet bulb temperature, the globe temperature, and the dry bulb temperature together with a set of coefficients applicable to the high humidity condition in the summer of Hong Kong. Analysis of the response of hospitalization rate to variation in HKHI and two other heat indices, namely Wet Bulb Globe Temperature (WBGT) and Net Effective Temperature (NET), revealed that HKHI performed generally better than WBGT and NET in reflecting the heat stress impact on excess hospitalization ratio in Hong Kong. Based on the study results, two reference criteria of HKHI were identified to establish a two-tier approach for the enhancement of the heat stress information service in Hong Kong.

  17. Proteomic response of mouse pituitary gland under heat stress revealed active regulation of stress responsive proteins.

    PubMed

    Memon, Shahar Bano; Lian, Li; Gadahi, Javaid Ali; Genlin, Wang

    2016-10-01

    The mapping of tissue proteomes can identify the molecular regulators and effectors of their physiological activity. However, proteomic response of a mammalian tissue against heat stress (HS) particularly of the pituitary gland has not yet been resolved. The proteomic response of the mouse pituitary gland against HS at 40(o)C was evaluated by iTRAQ. We found that, HS actively regulates stress-related proteins. Among 375 differentially expressed proteins, 26 up and 46 downregulated proteins were found as stress responsive proteins. Two proteins belonging to the HSP70 and one to HSP90 family were found upregulated. Meanwhile, the expression of HSP90α (Cytosolic), HSP60, and HSP84b were observed to be downregulated. A neuroprotective enzyme Nmnat3 was observed to be significantly upregulated. Three proteins related to the intermediate filament (IF) proteins (lamins, vimentin and keratins) were also found to be upregulated. We reported, an association between the IF proteins and HSPs as a biological marker of HS. The expression of Apo A-IV was upregulated and might be one explanation for low food intake during HS. Our findings indicated that, differentially expressed proteins might be played important roles in combating HS. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Heat stress increase under climate change twice as large in cities as in rural areas: A study for a densely populated midlatitude maritime region

    NASA Astrophysics Data System (ADS)

    Wouters, Hendrik; De Ridder, Koen; Poelmans, Lien; Willems, Patrick; Brouwers, Johan; Hosseinzadehtalaei, Parisa; Tabari, Hossein; Vanden Broucke, Sam; van Lipzig, Nicole P. M.; Demuzere, Matthias

    2017-09-01

    Urban areas are usually warmer than their surrounding natural areas, an effect known as the urban heat island effect. As such, they are particularly vulnerable to global warming and associated increases in extreme temperatures. Yet ensemble climate-model projections are generally performed on a scale that is too coarse to represent the evolution of temperatures in cities. Here, for the first time, we combine unprecedented long-term (35 years) urban climate model integrations at the convection-permitting scale (2.8 km resolution) with information from an ensemble of general circulation models to assess temperature-based heat stress for Belgium, a densely populated midlatitude maritime region. We discover that the heat stress increase toward the mid-21st century is twice as large in cities compared to their surrounding rural areas. The exacerbation is driven by the urban heat island itself, its concurrence with heat waves, and urban expansion. Cities experience a heat stress multiplication by a factor 1.4 and 15 depending on the scenario. Remarkably, the future heat stress surpasses everywhere the urban hot spots of today. Our results demonstrate the need to combine information from climate models, acting on different scales, for climate change risk assessment in heterogeneous regions. Moreover, these results highlight the necessity for adaptation to increasing heat stress, especially in urban areas.

  19. Mitochondrial dysfunction induced by heat stress in cultured rat CNS neurons

    PubMed Central

    White, Michael G.; Saleh, Osama; Nonner, Doris; Barrett, Ellen F.; Moraes, Carlos T.

    2012-01-01

    Previous work demonstrated that hyperthermia (43°C for 2 h) results in delayed, apoptotic-like death in striatal neuronal cultures. We investigated early changes in mitochondrial function induced by this heat stress. Partial depolarization of the mitochondrial membrane potential (ΔΨm) began about 1 h after the onset of hyperthermia and increased as the stress continued. When the heat stress ended, there was a partial recovery of ΔΨm, followed hours later by a progressive, irreversible depolarization of ΔΨm. During the heat stress, O2 consumption initially increased but after 20–30 min began a progressive, irreversible decline to about one-half the initial rate by the end of the stress. The percentage of oligomycin-insensitive respiration increased during the heat stress, suggesting an increased mitochondrial leak conductance. Analysis using inhibitors and substrates for specific respiratory chain complexes indicated hyperthermia-induced dysfunction at or upstream of complex I. ATP levels remained near normal for ∼4 h after the heat stress. Mitochondrial movement along neurites was markedly slowed during and just after the heat stress. The early, persisting mitochondrial dysfunction described here likely contributes to the later (>10 h) caspase activation and neuronal death produced by this heat stress. Consistent with this idea, proton carrier-induced ΔΨm depolarizations comparable in duration to those produced by the heat stress also reduced neuronal viability. Post-stress ΔΨm depolarization and/or delayed neuronal death were modestly reduced/postponed by nicotinamide adenine dinucleotide, a calpain inhibitor, and increased expression of Bcl-xL. PMID:22832569

  20. Mitochondrial dysfunction induced by heat stress in cultured rat CNS neurons.

    PubMed

    White, Michael G; Saleh, Osama; Nonner, Doris; Barrett, Ellen F; Moraes, Carlos T; Barrett, John N

    2012-10-01

    Previous work demonstrated that hyperthermia (43°C for 2 h) results in delayed, apoptotic-like death in striatal neuronal cultures. We investigated early changes in mitochondrial function induced by this heat stress. Partial depolarization of the mitochondrial membrane potential (ΔΨ(m)) began about 1 h after the onset of hyperthermia and increased as the stress continued. When the heat stress ended, there was a partial recovery of ΔΨ(m), followed hours later by a progressive, irreversible depolarization of ΔΨ(m). During the heat stress, O(2) consumption initially increased but after 20-30 min began a progressive, irreversible decline to about one-half the initial rate by the end of the stress. The percentage of oligomycin-insensitive respiration increased during the heat stress, suggesting an increased mitochondrial leak conductance. Analysis using inhibitors and substrates for specific respiratory chain complexes indicated hyperthermia-induced dysfunction at or upstream of complex I. ATP levels remained near normal for ∼4 h after the heat stress. Mitochondrial movement along neurites was markedly slowed during and just after the heat stress. The early, persisting mitochondrial dysfunction described here likely contributes to the later (>10 h) caspase activation and neuronal death produced by this heat stress. Consistent with this idea, proton carrier-induced ΔΨ(m) depolarizations comparable in duration to those produced by the heat stress also reduced neuronal viability. Post-stress ΔΨ(m) depolarization and/or delayed neuronal death were modestly reduced/postponed by nicotinamide adenine dinucleotide, a calpain inhibitor, and increased expression of Bcl-xL.

  1. Differential effects of heat stress on fibre capillarisation in tenotomised soleus and plantaris muscles.

    PubMed

    Hirunsai, Muthita; Srikuea, Ratchakrit

    2017-07-18

    Capillary regression is commonly observed in response to disuse muscle atrophy. Heat stress is known to alleviate muscle atrophy, while effect of heat exposure on capillary adaptation following disuse atrophy is not defined. Here, we examined the effect of heat treatment on capillarisation and the associated signalling in slow-oxidative soleus and fast-glycolytic plantaris muscles following Achilles tendon ablation (tenotomy). Male Wistar rats were assigned into control (CON), control with heat stress (CON + HEAT), tenotomy (TEN) and tenotomy with heat stress (TEN + HEAT) groups. Tenotomy was induced for 8 days in TEN and TEN + HEAT groups. Heat stress was maintained at 40.5-41.5 °C, 30 min for 7 days. Tenotomy resulted in reduction of capillary-to-fibre ratio, decreased VEGFR-2 and increased TSP-1 in soleus muscle, whereas VEGF protein expression remained unaffected. Tenotomy had no effect on capillary distribution and angiogenic signalling in plantaris muscle. These results were concomitant with larger reduction of cross-sectional area (CSA) in MHC type I and II myofibres of soleus compared to plantaris muscles. Interestingly, heat stress increased VEGFR-2 and attenuated TSP-1 protein expression in tenotomised soleus, but not plantaris muscles. Additionally, CSA of both type I and type II myofibres was greater in tenotomised soleus than plantaris muscles after heat treatment. Heat stress mitigated effect of tenotomy-induced capillary regression in a fibre-type-specific response, in part, by shifting the balance between angiogenic and angiostatic regulators. These results suggest beneficial effect of heat treatment for maintaining microcirculation in disuse muscle atrophy.

  2. Integrated Physiological Mechanisms of Exercise Performance, Adaptation, and Maladaptation to Heat Stress

    DTIC Science & Technology

    2011-10-01

    number of heat exposures (359, 424). Heat acclimatization is specific to the environment (hot/dry vs. hot/ wet ) and physical activity level, however...Comprehensive Physiology Table 1 Risk of Hyperthermia (and Possible Exertional Heat Illness) for a Typical Marathon Racer Based on Wet Bulb Globe...clothing during activities in hot weather, and performing firefighting near the active fire. Environmental heat stress and exchange Wet Bulb Globe

  3. Phosphoproteomic analysis of the response of maize leaves to drought, heat and their combination stress.

    PubMed

    Hu, Xiuli; Wu, Liuji; Zhao, Feiyun; Zhang, Dayong; Li, Nana; Zhu, Guohui; Li, Chaohao; Wang, Wei

    2015-01-01

    Drought and heat stress, especially their combination, greatly affect crop production. Many studies have described transcriptome, proteome and phosphoproteome changes in response of plants to drought or heat stress. However, the study about the phosphoproteomic changes in response of crops to the combination stress is scare. To understand the mechanism of maize responses to the drought and heat combination stress, phosphoproteomic analysis was performed on maize leaves by using multiplex iTRAQ-based quantitative proteomic and LC-MS/MS methods. Five-leaf-stage maize was subjected to drought, heat or their combination, and the leaves were collected. Globally, heat, drought and the combined stress significantly changed the phosphorylation levels of 172, 149, and 144 phosphopeptides, respectively. These phosphopeptides corresponded to 282 proteins. Among them, 23 only responded to the combined stress and could not be predicted from their responses to single stressors; 30 and 75 only responded to drought and heat, respectively. Notably, 19 proteins were phosphorylated on different sites in response to the single and combination stresses. Of the seven significantly enriched phosphorylation motifs identified, two were common for all stresses, two were common for heat and the combined stress, and one was specific to the combined stress. The signaling pathways in which the phosphoproteins were involved clearly differed among the three stresses. Functional characterization of the phosphoproteins and the pathways identified here could lead to new targets for the enhancement of crop stress tolerance, which will be particularly important in the face of climate change and the increasing prevalence of abiotic stressors.

  4. Leaf Proteome Analysis Reveals Prospective Drought and Heat Stress Response Mechanisms in Soybean.

    PubMed

    Das, Aayudh; Eldakak, Moustafa; Paudel, Bimal; Kim, Dea-Wook; Hemmati, Homa; Basu, Chhandak; Rohila, Jai S

    2016-01-01

    Drought and heat are among the major abiotic stresses that affect soybean crops worldwide. During the current investigation, the effect of drought, heat, and drought plus heat stresses was compared in the leaves of two soybean varieties, Surge and Davison, combining 2D-DIGE proteomic data with physiology and biochemical analyses. We demonstrated how 25 differentially expressed photosynthesis-related proteins affect RuBisCO regulation, electron transport, Calvin cycle, and carbon fixation during drought and heat stress. We also observed higher abundance of heat stress-induced EF-Tu protein in Surge. It is possible that EF-Tu might have activated heat tolerance mechanisms in the soybean. Higher level expressions of heat shock-related protein seem to be regulating the heat tolerance mechanisms. This study identifies the differential expression of various abiotic stress-responsive proteins that regulate various molecular processes and signaling cascades. One inevitable outcome from the biochemical and proteomics assays of this study is that increase of ROS levels during drought stress does not show significant changes at the phenotypic level in Davison and this seems to be due to a higher amount of carbonic anhydrase accumulation in the cell which aids the cell to become more resistant to cytotoxic concentrations of H2O2.

  5. Leaf Proteome Analysis Reveals Prospective Drought and Heat Stress Response Mechanisms in Soybean

    PubMed Central

    Das, Aayudh; Eldakak, Moustafa; Paudel, Bimal; Kim, Dea-Wook; Hemmati, Homa; Basu, Chhandak

    2016-01-01

    Drought and heat are among the major abiotic stresses that affect soybean crops worldwide. During the current investigation, the effect of drought, heat, and drought plus heat stresses was compared in the leaves of two soybean varieties, Surge and Davison, combining 2D-DIGE proteomic data with physiology and biochemical analyses. We demonstrated how 25 differentially expressed photosynthesis-related proteins affect RuBisCO regulation, electron transport, Calvin cycle, and carbon fixation during drought and heat stress. We also observed higher abundance of heat stress-induced EF-Tu protein in Surge. It is possible that EF-Tu might have activated heat tolerance mechanisms in the soybean. Higher level expressions of heat shock-related protein seem to be regulating the heat tolerance mechanisms. This study identifies the differential expression of various abiotic stress-responsive proteins that regulate various molecular processes and signaling cascades. One inevitable outcome from the biochemical and proteomics assays of this study is that increase of ROS levels during drought stress does not show significant changes at the phenotypic level in Davison and this seems to be due to a higher amount of carbonic anhydrase accumulation in the cell which aids the cell to become more resistant to cytotoxic concentrations of H2O2. PMID:27034942

  6. Characterization of physiological response and identification of associated genes under heat stress in rice seedlings.

    PubMed

    Xue, Da-Wei; Jiang, Hua; Hu, Jiang; Zhang, Xiao-Qin; Guo, Long-Biao; Zeng, Da-Li; Dong, Guo-Jun; Sun, Guo-Chang; Qian, Qian

    2012-12-01

    Global warming, which is caused by greenhouse gas emissions, makes food crops more vulnerable to heat stress. Understanding the heat stress-related mechanisms in crops and classifying heat stress-related genes can increase our knowledge in heat-resistant molecular biology and propel developments in molecular design breeding, which can help rice cope with unfavorable temperatures. In this study, we carried out a physiological analysis of rice plants after heat stress. The results show a dramatic increase in malondialdehyde contents and SOD activities. We successfully isolated 11 heat-related rice genes with known function annotation through DNSH, which is an improved SSH method for screening long cDNA fragments. The reanalysis of microarray data from public database revealed that all these genes displayed various expression patterns after heat stress, drought, cold and salt. Quantitative real-time reverse transcription PCR was also performed to validate the expression of these genes after heat stress. The expressions in 10 genes were all significantly changed except for contig 77, which is a CBL-interacting protein kinase. Several reports have been published about the members of the same gene family. Copyright © 2012. Published by Elsevier Masson SAS.

  7. Assessment of ASME code examinations on regenerative, letdown and residual heat removal heat exchangers

    SciTech Connect

    Gosselin, Stephen R.; Cumblidge, Stephen E.; Anderson, Michael T.; Simonen, Fredric A.; Tinsley, G. A.; Lydell, B.; Doctor, Steven R.

    2005-07-01

    Inservice inspection requirements for pressure retaining welds in the regenerative, letdown, and residual heat removal heat exchangers are prescribed in Section XI Articles IWB and IWC of the ASME Boiler and Pressure Vessel Code. Accordingly, volumetric and/or surface examinations are performed on heat exchanger shell, head, nozzle-to-head, and nozzle-to-shell welds. Inspection difficulties associated with the implementation of these Code-required examinations have forced operating nuclear power plants to seek relief from the U.S. Nuclear Regulatory Commission. The nature of these relief requests are generally concerned with metallurgical, geometry, accessibility, and radiation burden. Over 60% of licensee requests to the NRC identify significant radiation exposure burden as the principle reason for relief from the ASME Code examinations on regenerative heat exchangers. For the residual heat removal heat exchangers, 90% of the relief requests are associated with geometry and accessibility concerns. Pacific Northwest National Laboratory was funded by the NRC Office of Nuclear Regulatory Research to review current practice with regard to volumetric and/or surface examinations of shell welds of letdown heat exchangers regenerative heat exchangers and residual (decay) heat removal heat exchangers Design, operating, common preventative maintenance practices, and poten