Heat stress occurs when the body cannot adequately cool itself due to the combined contributions of metabolic heat, environmental factors and clothing. Heat stress found in the workplace puts employees at risk of developing heat-related illnesses, disorders and could be fatal. The wet bulb globe temperature (WBGT) index is the current method used to assess environmental contributions to heat stress in an occupational setting. The purpose of this thesis was to explore whether the National Weather Service's Heat Index (HI) could substitute for the WBGT Index during occupational heat stress exposure assessment. The possibility of using the HI for heat stress exposure assessments was explored by first developing an occupational exposure limit based on the HI and then by comparing the HI to WBGT Index over a range of environments. Data from 10 selected studies were reviewed and categorized into two groups (Classic Data and Progressive Data) based on the method used to determine the upper limit of the prescriptive zone. WBGT and HI values were estimated from the environmental data provided in the 10 studies and the metabolic demands were also noted. These data were used to illustrate the relationship between environment (WBGT and HI) and metabolic rate. Next the relationship between HI and WBGT was compared over a range of environments consisting of combinations of air temperature and percent relative humidity as defined by the NWS's Heat Index Chart. Finally the effects of adding a high radiant heat load (Tg = Tdb+10 °C) to the relationship between WBGT and HI was explored. The HI occupational exposure limits were protective of the upper limit threshold points in a manner similar to WBGT. A greater spread in the Classic and Progressive upper limit data was observed above the occupational exposure limit when expressed as HI. High correlation was observed (R2 = 0.95) between the WBGT Index and HI over a range of environments, assuming no radiant heat. The incremental increase in HI due to high radiant heat indicated a strong dependency on the absolute value of HI, which makes using HI to predict WBGT in radiant heat environments problematic. Findings suggest the Heat Index could be used to assess heat stress exposures and to set occupational exposure limits for hot environments in the absence of high radiant heat.

<p>The purification and biochemical characterization of the substance P (SP) hydrolyzing enzyme, substance P endopeptidase (SPE), have been carried out; with subsequent orientation in neurobiological fundamental processes involved in opioid dependence, withdrawal, and heat-stress.</p><p>SPE was purified from rat spinal cord, human spinal cord and cerebrospinal fluid (CSF), rat ventral tegemental area (VTA), and rat hippocampus. The enzyme activity was found to release the biologically active fragments SP(1-7) and SP(1-8) as major products. The purified enzymes were characterized with regard to their biochemical and kinetic properties. The typical SPE is neither inhibited by phosphoramidon nor captopril nor phenylmethanesulfonylflourid (PMSF). In comparison to other known proteases SPE differed in characteristics regarding substrate specificity, inhibition-profile, cleavage pattern, and other kinetic parameters. The technically very delicate approach of micro purification of SPE from the rat ventral tegemental area (VTA) (this is a very small tissue), turned out to be possible with the ÄKTA™-purifier system. Studies revealed a crucial role of SPE in a series of clinically important neuropathological conditions, such as opioid tolerance, and withdrawal (SPE, increased); and heat-stress (SPE, increased). These findings emerged from assessment of enzyme activity in hypothalamus, nucleus accumbens (NAc) periaqueductal gray (PAG), pituitary, striatum, substantia nigra (SN), VTA, spinal cord. Viewing the role of SPE in morphine tolerance, it was possible to note regional differences with a decrease in PAG, and striatum, whereas an increase was seen in SN, and VTA. After heat-stress treatment, SPE was raised in several regions (cerebral cortex, hippocampus, diencephalon, cerebellum, spinal cord), and the most precise observation of this was located to the hippocampus structure.</p>

Experiments were conducted to determine the effects of nutrition, temperature during feed withdrawal, shackling duration, sex and age at processing on broiler quality. Low energy (94% of recommended) diets resulted in a lower percentage of carcass fat while increasing the percentage of carcass protein. Low protein (85% of recommended) resulted in a decreased percentage of carcass protein while carcass fat increased. Low protein diets also limited frame size as measured by length and width of P. major. Exposure to 9 C temperatures during feed withdrawal resulted in improved meat quality as measured by higher ultimate pH, lower drip loss and darker color. Long shackling time (120 s) did not affect ultimate pH, drip or cooking losses compared to short shackling (<10 s); however, short shackled broilers exhibited poorer tenderness values. Males had higher carcass protein and lower fat than females. Females exhibited higher ultimate pH, higher drip loss and lighter breast meat. Drip loss and ultimate pH decreased with age. Processing age and sex of broilers may have greater influences on meat quality than previously reported. / Animal Science

The purification and biochemical characterization of the substance P (SP) hydrolyzing enzyme, substance P endopeptidase (SPE), have been carried out; with subsequent orientation in neurobiological fundamental processes involved in opioid dependence, withdrawal, and heat-stress. SPE was purified from rat spinal cord, human spinal cord and cerebrospinal fluid (CSF), rat ventral tegemental area (VTA), and rat hippocampus. The enzyme activity was found to release the biologically active fragments SP(1-7) and SP(1-8) as major products. The purified enzymes were characterized with regard to their biochemical and kinetic properties. The typical SPE is neither inhibited by phosphoramidon nor captopril nor phenylmethanesulfonylflourid (PMSF). In comparison to other known proteases SPE differed in characteristics regarding substrate specificity, inhibition-profile, cleavage pattern, and other kinetic parameters. The technically very delicate approach of micro purification of SPE from the rat ventral tegemental area (VTA) (this is a very small tissue), turned out to be possible with the ÄKTA™-purifier system. Studies revealed a crucial role of SPE in a series of clinically important neuropathological conditions, such as opioid tolerance, and withdrawal (SPE, increased); and heat-stress (SPE, increased). These findings emerged from assessment of enzyme activity in hypothalamus, nucleus accumbens (NAc) periaqueductal gray (PAG), pituitary, striatum, substantia nigra (SN), VTA, spinal cord. Viewing the role of SPE in morphine tolerance, it was possible to note regional differences with a decrease in PAG, and striatum, whereas an increase was seen in SN, and VTA. After heat-stress treatment, SPE was raised in several regions (cerebral cortex, hippocampus, diencephalon, cerebellum, spinal cord), and the most precise observation of this was located to the hippocampus structure.

Outdoor workers are often subjected to thermal conditions beyond the comfort zone, but to what degree do such conditions affect the health and safety of those workers is still a matter requiring further investigation. The purpose of this study is to examine the relationship between thermal conditions and (1) heat-related disorders and (2) acute injuries using injury and illness data collected during the BP Deepwater Horizon clean-up operations. Over an eleven month period, 5,485 cases were identified as either heat-related or an acute injury (incident type) and further divided by severity. Daily weather data were used to estimate the wet bulb globe temperature (WBGT) based on the time of day. Heat Stress Levels intervals were defined using the estimated WBGT. Labor-hours by month were estimated by the prevailing shift length in the month and the number of workers. The incidents were assigned a Heat Stress Level and the number of labor-hours by heat stress level were determined. The next step was to calculate the incident rate ratio by Heat Stress Level against the baseline of thermal comfort. The results indicated that the rate ratios for heat-related disorders and acute injury increased for thermal conditions from 24⁰C-WBGT to 30⁰C-WBGT. There was a further significant increase in rate ratio for heat-related injury above 33 °C-WBGT. It was notable that the incident rates for both heat-related disorders and acute injuries increased at thermal conditions generally considered to be below the occupational exposure limit (OEL) at 30 ⁰C-WBGT. The rate of heat-related disorders increased substantially above the occupational exposure limit.

Heat stress is influenced by environmental conditions, workload and clothing. A critical environment is the upper limit of compensable heat stress for a given metabolic rate and clothing ensemble. The physiological strains associated with heat stress are core and skin temperatures, heart rate and physiological strain index (PSI). Because heat dissipation mechanisms may differ between men and women, there may be gender differences in the critical environment and the associated physiological variables. Gender differences were explored between acclimated men (n = 20) and women (n = 9) at the upper limit of compensable heat stress. Participants walked on a motorized treadmill at a target metabolic rate of 160W/m2 while wearing five different clothing ensembles (cotton work clothes, cotton coveralls, and three coveralls of particle barrier, liquid barrier, and vapor barrier properties). The starting air temperature (Tdb) was 34°C and humidity was held constant at 50%. Once thermal equilibrium was achieved, Tdb was increased 1°C every five minutes until loss of thermal equilibrium or termination criteria were met. Upon initial analysis, several gender differences were found. A significant difference (p = 0.035) was found for WBGTcrit, where values were 32.5°C for men and 33.1°C for women. Women had higher average heart rates (hr = 125 and 112 bpm), average skin temperatures (Tsk =36.4 and 36.2°C), and psi values (4.5 and 3.8) than men. No significant difference was found between genders for core temperature (tre) (p = 0.147). The target metabolic rate of 160W/m2 was not achieved and there were significant differences (p <0.0001) between men (172 W/m2) and women (152 W/m2). The effects of metabolic rate on WBGTcrit was examined and it was discovered that the difference in WGBTcrit could be explained by the difference in metabolic rate. The same logic was applied to the physiological responses and confirmed a difference between genders for Tre, HR, and PSI. The differences for Tsk disappeared. These findings indicate that women experienced a greater cardiovascular strain at the critical conditon and also greater heat strain than men at the same heat load.

No description available.

Background The remarkably efficient mechanisms of the human body to maintain its core temperature of 37°C can be inadequate when harsh climatic conditions and excessive muscle movement lead to heat stress, dehydration and potential heat illness, ranging from minor symptoms such as fatigue to a potentially fatal heat stroke. Agricultural workers in the tropics are at high risk, which is expected to increase with climate change. Sugarcane harvesting in Costa Rica is largely done by cutting the cane with a machete, by temporary, sub-contracted workers who are often migrants and living in poverty. Sugarcane harvesters are known to be affected by an epidemic of chronic kidney disease of non-traditional origin, currently hypothesized to be related to working conditions. Objectives This work aimed to better understand and document sugarcane harvester exposure to heat and the health consequences of working under such conditions. Specific objectives were to 1) Document working conditions and heat in the Costa Rican sugarcane industry (Paper I); 2) Quantify heat stress exposures faced by sugarcane harvesters in Costa Rica (Paper II); and 3) Quantify the occurrence of heat stress symptoms and abnormal urinary parameters in sugarcane workers in Costa Rica (Papers III and IV). Methods This study took place over three harvests following a pilot assessment prior to the first harvest. Methods included direct observation, semi-structured interviews with 24 individuals and a participatory workshop with 8 harvesters about heat-related perceptions, exposures and coping strategies during the harvest and non-harvest season (Pilot). Researchers accompanied workers in the field during all three harvests, measured wet bulb globe temperature (WBGT) and conducted direct observation. Heat exposure assessment was conducted by calculating metabolic load, WBGT and corresponding limit values based on international guidelines (NTP and OSHA) (Harvest 1). Self-reported symptom data were collected using orally-administered questionnaires from 106 sugarcane harvesters and 63 non-harvesters from the same company (Harvest 2). Chi-square test and gamma statistic were used to evaluate differences in self-reported symptoms and trends over heat exposure categories. Finally, liquid consumption during the work shift was documented and urinalysis was conducted pre-and post-shift in 48 sugarcane harvesters on three days; differences were assessed with McNemar´s test on paired proportions (Harvest 3). Results Sugarcane workers in both the harvest and non-harvest seasons are exposed to heat, but particularly during the harvest season. Field workers have to carry their own water to the field and often have no access to shade. Some plantworkers are also exposed to intense heat. The metabolic load of sugarcane harvesting was determined to be 261 W/m2. The corresponding threshold value is 26 ◦C WBGT, above which workers should decrease work load or take breaks to avoid the risk of heat stress. Harvesters in this study were at risk of heat stress as early as 7:15 am on some mornings and by 9:00 am on all mornings. After 9:15 am, OSHA recommendations would require that harvesters only work at full effort 25% of each hour to avoid heat stress. Heat and dehydration symptoms at least once per week were experienced significantly more frequently among harvesters than non-harvesters (p&lt;0.05): headache, tachycardia, fever, nausea, difficulty breathing, dizziness, and dysuria. Percentages of workers reporting heat and dehydration-related symptoms increased over increasing heat exposure categories. Total liquid consumed ranged from 1 to 9 L and differed over days (median 5.0, 4.0 and 3.25 on days 1, 2 and 3 respectively). On these same days, the two principle indicators of dehydration: high USG (≥1.025) and low pH (≤5), changed significantly from pre to post-shift (p=0.000 and p=0.012).Proportions of workers with proteinuria &gt;30 mg/dL, and blood, leucocytes and casts in urine were also significantly different between pre and post-shift samples at the group level, but unlike USG and pH, these alterations were more frequent in the pre-shift sample. 85% of workers presented with proteinuria at least once and 52% had at least one post-shift USG indicative of dehydration. Conclusion Heat exposure is an important occupational health risk for sugarcane workers according to international standards. A large percentage of harvesters experience symptoms consistent with heat exhaustion throughout the harvest season. Pre and post-shift urine samples demonstrate dehydration and other abnormal findings. The results of this study demonstrate an urgent need to improve working conditions for sugarcane harvesters both under current conditions and in adaptation plans for future climate change.

Dissertation (Ph.D.)--University of South Florida, 2006. / Title from PDF of title page. Document formatted into pages; contains 107 pages. Includes vita. Includes bibliographical references.

Resumo: O estresse por calor é considerado um dos fatores de maior impacto na criação de frangos de corte, já que exerce grande influência no desempenho e na qualidade da carcaça, bem como no perfil de expressão de genes relacionados ao crescimento e desenvolvimento animal. Assim, o presente trabalho objetivou verificar o efeito da temperatura e da restrição alimentar no desempenho, composição de carcaça e nos padrões de expressão de genes envolvidos na regulação do crescimento e desenvolvimento (GHR, IGF-I e IGF-IR), aos 21 e 42 dias de idade dos frangos de corte pela técnica de PCR quantitativo em tempo real. Os resultados evidenciaram que a restrição alimentar imposta pela exposição ao calor reduziu o desempenho e rendimento de peito e aumentou o rendimento de coxas+sobrecoxas. O estresse por calor e o consumo de ração alteraram o rendimento de asas, mas não influenciaram o rendimento de carcaça e de gordura abdominal. O calor aumentou o teor de extrato etéreo no peito e nas asas e diminuiu o de matéria mineral nas coxas+sobrecoxas. Independente da temperatura de criação, a restrição alimentar exerce um efeito negativo na expressão do gene do GHR no fígado das aves jovens, sem maiores reflexos na expressão do gene do IGF-I. O estresse térmico afeta a expressão dos genes hepáticos GHR e IGF-I somente nas aves adultas, as quais apresentam perfil inverso ao das aves restritas pelo "pair-feeding". A reação de amplificação do gene IGF-IR apresentou formação de produtos de amplificação inespecíficos, assim como formação de estruturas secundárias das moléculas dos iniciadores (dímeros e "hairpins"), o que impossibilitou a análise dos resultados / Abstract: Heat stress is considered one of greatest impact factors on broiler chicken production, once that it has great influence on the performance and carcass quality, as well as on the expression profile of genes related to growth and animal development. Thus, the present work had the objective of verifying the effect of temperature and food restriction on the performance, carcass composition and expression pattern of genes involved in the growth regulation and development (GHR, IGF-I and IGF-IR), at 21 and 42 days of age of the broilers using the PCR quantitative real-time technique. The results showed that the food restriction imposed by heat exposure, affected negatively the performance and breast yield and, positively, the tight and drumstick yield. The heat stress and feed intake altered the yield of wings, but did not affect carcass yield and abdominal fat. The heat increased both ether extract content in the breast and wings and reduced the mineral matter content in the tights and drumsticks. Independent of temperature, in the young bird's livers, food restriction endorses a negative effect on the GHR gene expression, without greatest reflects on IGF-I expression. Only on adult bird's, thermal stress affects the expression of GHR and IGF-I hepatic genes, that exhibit an inverse profile of restricted pair-feeding birds. The amplification reaction of IGF-IR gene showed both formation of nonspecific amplification products, as well as secondary structures of the primers of the molecules (dimerous and hairpins), precluding the analysis of results / Orientador: Renato Luís Furlan / Coorientador: Luiz Roberto Furlan / Banca: João Martins Pizauro Júnior / Banca: Poliana Fernanda Giachetto / Mestre