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1.
Change in Exercise Performance and Markers of Acute Kidney Injury Following Heat Acclimation with Permissive Dehydration.
Haroutounian, A, Amorim, FT, Astorino, TA, Khodiguian, N, Curtiss, KM, Matthews, ARD, Estrada, MJ, Fennel, Z, McKenna, Z, Nava, R, et al
Nutrients. 2021;(3)
Abstract
Implementing permissive dehydration (DEH) during short-term heat acclimation (HA) may accelerate adaptations to the heat. However, HA with DEH may augment risk for acute kidney injury (AKI). This study investigated the effect of HA with permissive DEH on time-trial performance and markers of AKI. Fourteen moderately trained men (age and VO2max = 25 ± 0.5 yr and 51.6 ± 1.8 mL.kg-1.min-1) were randomly assigned to DEH or euhydration (EUH). Time-trial performance and VO2max were assessed in a temperate environment before and after 7 d of HA. Heat acclimation consisted of 90 min of cycling in an environmental chamber (40 °C, 35% RH). Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) were assessed pre- and post-exercise on day 1 and day 7 of HA. Following HA, VO2max did not change in either group (p = 0.099); however, time-trial performance significantly improved (3%, p < 0.01) with no difference between groups (p = 0.485). Compared to pre-exercise, NGAL was not significantly different following day 1 and 7 of HA (p = 0.113) with no difference between groups (p = 0.667). There was a significant increase in KIM-1 following day 1 and 7 of HA (p = 0.002) with no difference between groups (p = 0.307). Heat acclimation paired with permissive DEH does not amplify improvements in VO2max or time-trial performance in a temperate environment versus EUH and does not increase markers of AKI.
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2.
Hot weather and heat extremes: health risks.
Ebi, KL, Capon, A, Berry, P, Broderick, C, de Dear, R, Havenith, G, Honda, Y, Kovats, RS, Ma, W, Malik, A, et al
Lancet (London, England). 2021;(10301):698-708
Abstract
Hot ambient conditions and associated heat stress can increase mortality and morbidity, as well as increase adverse pregnancy outcomes and negatively affect mental health. High heat stress can also reduce physical work capacity and motor-cognitive performances, with consequences for productivity, and increase the risk of occupational health problems. Almost half of the global population and more than 1 billion workers are exposed to high heat episodes and about a third of all exposed workers have negative health effects. However, excess deaths and many heat-related health risks are preventable, with appropriate heat action plans involving behavioural strategies and biophysical solutions. Extreme heat events are becoming permanent features of summer seasons worldwide, causing many excess deaths. Heat-related morbidity and mortality are projected to increase further as climate change progresses, with greater risk associated with higher degrees of global warming. Particularly in tropical regions, increased warming might mean that physiological limits related to heat tolerance (survival) will be reached regularly and more often in coming decades. Climate change is interacting with other trends, such as population growth and ageing, urbanisation, and socioeconomic development, that can either exacerbate or ameliorate heat-related hazards. Urban temperatures are further enhanced by anthropogenic heat from vehicular transport and heat waste from buildings. Although there is some evidence of adaptation to increasing temperatures in high-income countries, projections of a hotter future suggest that without investment in research and risk management actions, heat-related morbidity and mortality are likely to increase.
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3.
Occupational heat exposure and the risk of chronic kidney disease of nontraditional origin in the United States.
Chapman, CL, Hess, HW, Lucas, RAI, Glaser, J, Saran, R, Bragg-Gresham, J, Wegman, DH, Hansson, E, Minson, CT, Schlader, ZJ
American journal of physiology. Regulatory, integrative and comparative physiology. 2021;(2):R141-R151
Abstract
Occupational heat exposure is linked to the development of kidney injury and disease in individuals who frequently perform physically demanding work in the heat. For instance, in Central America, an epidemic of chronic kidney disease of nontraditional origin (CKDnt) is occurring among manual laborers, whereas potentially related epidemics have emerged in India and Sri Lanka. There is growing concern that workers in the United States suffer with CKDnt, but reports are limited. One of the leading hypotheses is that repetitive kidney injury caused by physical work in the heat can progress to CKDnt. Whether heat stress is the primary causal agent or accelerates existing underlying pathology remains contested. However, the current evidence supports that heat stress induces tubular kidney injury, which is worsened by higher core temperatures, dehydration, longer work durations, muscle damaging exercise, and consumption of beverages containing high levels of fructose. The purpose of this narrative review is to identify occupations that may place US workers at greater risk of kidney injury and CKDnt. Specifically, we reviewed the scientific literature to characterize the demographics, environmental conditions, physiological strain (i.e., core temperature increase, dehydration, heart rate), and work durations in sectors typically experiencing occupational heat exposure, including farming, wildland firefighting, landscaping, and utilities. Overall, the surprisingly limited available evidence characterizing occupational heat exposure in US workers supports the need for future investigations to understand this risk of CKDnt.
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4.
Sex difference in initial thermoregulatory response to dehydrated exercise in the heat.
Giersch, GEW, Morrissey, MC, Butler, CR, Colburn, AT, Demarais, ZS, Kavouras, SA, Jay, O, Charkoudian, N, Casa, DJ
Physiological reports. 2021;(14):e14947
Abstract
Although it is well established that dehydration has a negative impact on thermoregulation during exercise in the heat, it is unclear whether this effect of dehydration is different between men and women, or across the phases of the menstrual cycle (MC). Twelve men and seven women (men: 20 ± 2 years, 70.13 ± 10.5 kg, 173.4 ± 6.0 cm, 54.2 ± 8.6 ml kg-1 min-1 ; women: 20 ± 2 years, 57.21 ± 7.58 kg, 161 ± 5 cm, 40.39 ± 3.26 ml kg-1 min-1 ) completed trials either euhydrated (urine specific gravity, USG ≤ 1.020, Euhy) or dehydrated (USG > 1.020, Dehy). Trial order was randomized and counterbalanced; men completed two trials (MEuhy and MDehy) and women completed four over two MC phases (late follicular: days 10-13, FDehy, FEuhy; midluteal: days 18-22, LDehy, LEuhy). Each trial consisted of 1.5 h, split into two 30 min blocks of exercise (B1 and B2, 15 min at 11 W/kg & 15 min at 7 W/kg) separated by 15 min rest in between and after. Rectal temperature (Tre ) was measured continuously and estimated sweat loss was calculated from the body mass measured before and after each block of exercise. When dehydrated, the rate of rise in Tre was greater in women in the first block of exercise compared to men, independently of the MC phase (MDehy: 0.03 ± 0.03°C/min, FDehy: 0.06 ± 0.02, LDehy: 0.06 ± 0.02, p = 0.03). Estimated sweat loss was lower in all groups in B1 compared to B2 when dehydrated (p < 0.05), with no difference between sexes for either hydration condition. These data suggest that women may be more sensitive to the negative thermoregulatory effects of dehydration during the early stages of exercise in the heat.
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5.
Comparison of two different cooling systems in alleviating thermal and physiological strain during prolonged exercise in the heat.
Keller, S, Kohne, S, Bloch, W, Schumann, M
Ergonomics. 2021;(1):129-138
Abstract
This study compared the efficacy of an ice vest comprising of water (WATER) or a water-carbon (CARBON) emulsion on thermophysiological responses to strenuous exercise in the heat. Twelve male cyclists completed three 50-minute constant workload trials (55% of peak power output, ambient temperature 30.4 ± 0.6°C) with WATER, CARBON, and without ice vest (CONTROL), respectively. The increase in core body temperature (Tcore) was lower in WATER at 40 (-0.49 ± 0.34 °C) and 50 minutes (-0.48 ± 0.48 °C) and in CARBON at 30 (-0.41 ± 0.48 °C), 40 (-0.54 ± 0.51 °C), and 50 minutes (-0.67 ± 0.62 °C) as compared to CONTROL (p < 0.05, ES > 0.8). While heart rate and blood lactate kinetics did not differ between the conditions, statistical main effects in favour of both WATER and CARBON were found for thermal sensation (condition p < 0.001 and interaction p < 0.01) and rating of perceived exertion (condition p < 0.05). Per-cooling with CARBON and WATER similarly reduced Tcore but not physiological strain during prolonged exercise in the heat. Practitioner Summary: Exercise in the heat is characterised by increases in thermophysiological strain. Both per-cooling with a novel carbon-based and a conventional water-based ice vest were shown to reduce core temperature significantly. However, due to its lower mass, the carbon-based system may be recommended especially for weight-bearing sports.
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6.
Real world study of short term efficacy, safety, and tolerability of canagliflozin 100 mg initiation in type 2 diabetes mellitus patients during hot humid Indian summer.
Sanyal, D, Majumder, A, Ghosh, S, Pandit, K
Diabetes & metabolic syndrome. 2021;(1):385-389
Abstract
BACKGROUND AND AIM To assess short term (3 months) efficacy, safety, and tolerability of canagliflozin 100 mg among type 2 diabetes mellitus (T2DM) initiated during hot humid Indian summer. METHODS A prospective, observational, multi-center study of 300 T2DM patients with inadequate glycemic control (i.e., HbA1c of ≥6.5%) with or without other antihyperglycemic agents (AHA) were enrolled in the study in the month of March. The objective of the study was to assess the efficacy that is changes in glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), blood pressure (BP), lipid profile, body mass index (BMI) and safety of canagliflozin with regards to genitourinary infection, fall, diabetic keto acidosis (DKA) episodes, blood ketone and beta-hydroxybutyrate levels. All patients were initiated on canagliflozin 100 mg once daily for 12 weeks, irrespective of background medications. RESULTS At 12 weeks, a significant reduction was observed in all the glycemic parameters,BMI, BP, total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). However, a nonsignificant reduction in estimated glomerular filtration rate (eGFR) was observed at 12 weeks. A total of 9 adverse events were reported including 2 episodes of urinary tract infection (UTI) and 4 episodes of genital infection. The blood ketone, beta-hydroxybutyrate levels were found to be within normal limits and no episode of DKA was reported at 12 weeks. None of our patients had reported any volume depletion related adverse events viz. postural hypotension, giddiness etc. CONCLUSION Canagliflozin 100 mg can be safely initiated in type 2 diabetes patients during hot humid Indian summer, irrespective of background medications and is effective and well tolerated.
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7.
High temperature susceptibility of sexual reproduction in crop plants.
Lohani, N, Singh, MB, Bhalla, PL
Journal of experimental botany. 2020;(2):555-568
Abstract
Climate change-induced increases in the frequency of extreme weather events, particularly heatwaves, are a serious threat to crop productivity. The productivity of grain crops is dependent on the success of sexual reproduction, which is very sensitive to heat stress. Male gametophyte development has been identified as the most heat-vulnerable stage. This review outlines the susceptibility of the various stages of sexual reproduction in flowering plants from the time of floral transition to double fertilization. We summarize current knowledge concerning the molecular mechanisms underpinning the heat stress-induced aberrations and abnormalities at flowering, male reproductive development, female reproductive development, and fertilization. We highlight the stage-specific bottlenecks in sexual reproduction, which regulate seed set and final yields under high-temperature conditions, together with the outstanding research questions concerning genotypic and species-specific differences in thermotolerance observed in crops. This knowledge is essential for trait selection and genetic modification strategies for the development of heat-tolerant genotypes and high-temperature-resilient crops.
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8.
The weather condition and epidemics as triggers for febrile seizure: A single-center retrospective observational study.
Kawakami, I, Inoue, M, Adachi, S, Koga, H
Epilepsy & behavior : E&B. 2020;:107306
Abstract
OBJECTIVE The objective of this study was to investigate the association between the weather and epidemic condition and risk of febrile seizures (FSs) in Japan. STUDY DESIGN This single-center, retrospective study included 560 children (age, 6-60 months) with FSs who were transported to our center by ambulance from January 2011 through December 2018. The weather (temperature, atmospheric pressure, relative air humidity, amount of rainfall, sunshine duration, and air concentration of nitrogen dioxide [NO2] and sulfur dioxide [SO2]) and epidemic (influenza virus infection, infectious gastroenteritis, and exanthem subitum) conditions in this region were compared between the periods (days or weeks) with the transportation of children with FS to our hospital and those without such transportation. RESULTS In the univariate analyses, neither daily or weekly weather condition nor weekly epidemic condition was correlated to FS transportation. Furthermore, the multiple logistic regression analysis suggested that epidemic influenza virus infection (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.08-1.73) and infectious gastroenteritis (OR, 1.64; 95% CI, 1.09-2.54) were the independent risk factors for FS occurrence and weather condition was not associated with FS risk. CONCLUSIONS Febrile seizure incidence may be increased by epidemic febrile infections but not by weather condition.
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9.
Cooling intervention studies among outdoor occupational groups: A review of the literature.
Chicas, R, Xiuhtecutli, N, Dickman, NE, Scammell, ML, Steenland, K, Hertzberg, VS, McCauley, L
American journal of industrial medicine. 2020;(11):988-1007
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Abstract
BACKGROUND The purpose of this systematic review is to examine cooling intervention research in outdoor occupations, evaluate the effectiveness of such interventions, and offer recommendations for future studies. This review focuses on outdoor occupational studies conducted at worksites or simulated occupational tasks in climatic chambers. METHODS This systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed, Embase, and Web of Science were searched to identify original research on intervention studies published in peer-reviewed journals that aimed at reducing heat stress or heat-related illness from January 2000 to August 2020. RESULTS A systematic search yielded a total of 1042 articles, of which 21 met the inclusion criteria. Occupations with cooling intervention studies included agriculture (n = 5), construction (n = 5), industrial workers (n = 4), and firefighters (n = 7). The studies focused on multiple types of cooling interventions cooling gear (vest, bandanas, cooling shirts, or head-cooling gel pack), enhanced heat dissipation clothing, forearm or lower body immersion in cold water, water dousing, ingestion of a crushed ice slush drink, electrolyte liquid hydration, and modified Occupational Safety and Health Administration recommendations of drinking water and resting in the shade. CONCLUSION Current evidence indicates that using multiple cooling gears along with rest cycles may be the most effective method to reduce heat-related illness. Occupational heat-related illnesses and death may be mitigated by targeted cooling intervention and workplace controls among workers of vulnerable occupational groups and industries.
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10.
Evaluation of the efficacy of warm salt water foot-bath on patients with painful diabetic peripheral neuropathy: A randomized clinical trial.
Vakilinia, SR, Vaghasloo, MA, Aliasl, F, Mohammadbeigi, A, Bitarafan, B, Etripoor, G, Asghari, M
Complementary therapies in medicine. 2020;:102325
Abstract
OBJECTIVES Pain relief is one of the main goals of treatment in Diabetic peripheral neuropathy (DPN). Abzan(foot- bath) is one of the effective ways to relief various types of pain in Persian Medicine (PM). DESIGN This study is a randomized clinical trial (RCT) conducted on 60 patients of age range within 30 to 70 years, which were randomly divided into three groups. Group A (warm water bath):For one month each night before bedtime, they were asked to sit on a chair with trousers pulled up to about 5 cm above the ankles and both feet immersed in an electrical foot-bath that contained 5 liters of warm tolerable water (between 40 and 45 ° C) for 15 minutes without any massage. In Group B (salt water bath) was added and dissolved 250 grams of powdered mineral salt to their warm water. Other stages were similar to the group A. Group C (control) did not receive any interventions. Patients were evaluated prior to and following the intervention by the Douleur Neuropathique 4 questionnaire (DN4), The McGill Pain questionnaire and The World Health Organization Bref Quality of Life (WHOQOL-BREF) questionnaire. RESULTS Decrease in DN4 score level in the salt warm water group was significant while The McGill questionnaire showed a significant decrease of pain level the same group. CONCLUSIONS Application of a specific Abzan (salt water bath) may significantly decrease the pain of DPN patients.