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PubMed1999

Exercise in the Heat. II. Critical Concepts in Rehydration, Exertional Heat Illnesses, and Maximizing Athletic Performance.

OBJECTIVE: To acquaint athletic trainers with the numerous interrelated components that must be considered when assisting athletes who exercise in hot environments. Useful guidelines to maximize performance and minimize detrimental health consequences are presented. DATA SOURCES: The databases MEDLINE and SPORT Discus were searched from 1980 to 1999, with the terms. "body cooling," "dehydration," "exercise," "heat illnesses," "heat," "fluid replacement," "acclimatization," "hydration," "rehydration," "performance," and "intravenous," among others. DATA SYNTHESIS: This paper provides an in-depth look at issues regarding physiologic and performance considerations related to rehydration, strategies to maximize rehydration, modes of rehydration, health consequences of exercise in the heat, heat acclimatization, body cooling techniques, and practice and competition modifications. CONCLUSIONS/RECOMMENDATIONS: Athletic trainers have a responsibility to ensure that athletes who exercise in hot environments are prepared to do so in an optimal manner and to act properly to avoid the potentially harmful heat illnesses that can result from exercise in the heat.

Journal Article↗
PubMed2005

The crisis of the thesis of climatic pessimism: malaria and the climatic question.

The publication of Boudin's Traité de Geographie et de Statistique médicale (1857) and the creation in 1908 of the Institut de Pathologie Exotique by Laveran, correspond to two entirely different manners of considering tropical diseases and adaptability (or acclimatation) to the Tropics, directly associated with the idea of capability or incapability of Europeans to resist tropical diseases. We analyse the way perspectives have changed with respect to the influence that climate, particularly tropical, exert on the body of individuals and on populations used to live under temperate climatic conditions. The manner the concepts of medical geography, climatic pessimism and individual acclimatation get articulated with the discovery of tropical diseases, their aetiological agents and their localisation, particularly malaria, can only be understood by also analysing how the problems generated by the diversity of races and migration phenomena have been envisaged.

Adaptation, Physiological↗
PubMed2006

[Effects of risperidone on polysomnography in patients with first-episode schizophrenia].

OBJECTIVE: To investigate the effects of risperidone on the polysomnography (PSG) in the patients with first-episode schizophrenia. METHODS: Twenty-five patients with first-episode schizophrenia, 13 males and 12 females, aged 29 +/- 8, underwent polysomnographic recording for 4 consecutive nights, the first night being used for acclimatization, and on the 3 rd and 4 th nights risperidone in the dose of 1.2 mg was administered before going to bed. Forty-four healthy persons, 23 males and 21 females, aged 28 +/- 8, underwent polysomnographic recording for 2 consecutive nights, the first night being used for acclimatization. RESULTS: The baseline PSG recording showed that in comparison with the normal control group the total sleep time of the schizophrenia patients was shorter (378 min +/- 30 min vs 462 min +/- 21 min), sleep latency was longer (30 min +/- 14 min vs 18 min +/- 8 min), rapid eye movement (REM) sleep latency was shorter (59 min +/- 20 min vs 88 min +/- 10 min), REM sleep time was shorter (61 min +/- 17 min vs 84 min +/- 12 min), awakening time was longer (34 min +/- 17 min vs 15 min +/- 5 min), stage 1 (S1) time was longer (22% +/- 10% vs 9.0% +/- 1.7%), S3 time and S4 time were shorter, and the sleep efficacy was lower (86% +/- 10%) (P < 0.05 approximately P < 0.01); however, there was no significant difference in the S2 time between these 2 groups (54% +/- 16% vs 56% +/- 4%, P > 0.05). In the schizophrenia group, in comparison with the baseline levels in the third and fourth nights the total sleep times were significantly increased (406 min +/- 34 min and 428 min +/- 31 min respectively), the awakening times were significantly decreased (23 min +/- 15 min and 19 min +/- 8 min respectively), and S1 times were significantly decreased (14 min +/- 9 min and 10 min +/- 9 min respectively), with such changes time-dependently; and in the 4 th night the REM sleep time was significantly increased (87 min +/- 20 min) and the sleep efficacy was significantly improved (93% +/- 12%) (P < 0.05 approximately P < 0.01), however, there were no significant differences in the sleep latency and slow wave sleep (both P > 0.05). CONCLUSION: Risperidone significantly improves the quality of sleep.

Adult↗
PubMed1991

Working in the cold.

Physiologically speaking, working in the cold is primarily a matter of maintaining thermal balance, since both energy metabolism and neuromuscular function is temperature dependent. Body temperature is also subject to variations due to circadian rhythms. While local acclimatization to cold is well established, and may be of considerable practical benefit, general acclimatization to cold, if in fact a reality, is at best of limited practical value compared to know-how, experience, and environmental protection. Some of the major problems associated with the performance of physical work in the cold, are consequences of the hobbling effect of the protective clothing, as well as the obstructive effects of snow and ice, and the chilling effect of wind.

Body Temperature Regulation↗
PubMed1991

Biperiden administration in normal sleep and after rapid eye movement sleep deprivation in healthy volunteers.

Twenty-six healthy volunteers were randomly assigned to one of four groups. Groups Bip-4 and Bip-6, each with six subjects, received 4 and 6 mg of biperiden, respectively, and were studied on acclimatization, baseline, biperiden, and follow-up nights. Group REM-P (n = 7) and Group REM-Bip (n = 7) were studied on acclimatization, baseline, six nights of REM sleep deprivation, and one recovery (treatment) night with either placebo (group REM-P) or biperiden (group REM-Bip), and one follow-up night. Biperiden 4 and 6 mg increased REM sleep latency and biperiden 6 mg reduced REM sleep time. On the recovery night following REM sleep deprivation Group REM-P and REM-Bip showed an increase in sleep continuity. REM sleep time in the REM-P group was increased during the recovery (treatment) night (REM sleep recovery), while the REM-Bip group did not show a significant REM sleep increase during recovery (treatment) night. It was not until the follow-up night that REM sleep increased in the REM-Bip group.

Adult↗
PubMed1991

[Is altitude good for health?].

Health at altitude depends on the success of functional adjustments. Only the success of the short-term adjustments including increased tidal volume, acceleration of circulation, centralization of blood volume, hemoconcentration and adjustment of de diuresis to reduce cardiac volume overload render acclimatization possible. During these long-term adjustments, which always remain incomplete at altitudes above 2000 to 3000 m, mainly the cardiovascular economy and the respiratory efficiency are improved. Failure of the short-term adjustments excludes acclimatization and may be due to reduced physical capacity or to excessive physical activity (too fast too high). It is associated with sympathetic cardiac volume overload, central hypoxia, antidiuresis and distress which result in acute mountain sickness. Health at altitude may be preserved by moderating the ascent, the duration and the physical activity there.

Adaptation, Physiological↗
PubMed1989

Free radical membrane scavengers in myocardium of rats of different age exposed to chronic hypoxia.

Age-dependent changes in myocardial content of vitamin E and total hydrophobic free radical scavengers were estimated in rats of different age. Comparatively high values of vitamin E (0.10-0.12 mg/g fresh tissue) were found in 2-day-old rats. The content of vitamin E was lower in 15- and 60-day-old and 40% higher in 120-day-old rats as compared with new-born animals. Total scavengers were monotonously falling down with age. Vitamin E contribution to total scavengers activity gradually increased in postnatal developmental period of cardiac muscle (from 10% for 2-day-old rats to 50% for 120-day-old rats). Chronic hypoxia (intermittent high altitude hypoxia - 7000 m) had no effect on the levels of cardiac total scavengers and vitamin E when the animals were acclimatized from the 5th postnatal day. Acclimatization of adult animals induced a drop in concentration of vitamin E and did not affect the level of total scavengers.

Aging↗
PubMed1989

Effects of propranolol on acute mountain sickness (AMS) and well-being at 4,300 meters of altitude.

A number of physiological responses and adjustments occur at high altitude to compensate for hypoxia. We hypothesized that interference with one component of the normal compensatory process, the sympathetic nervous system, would hinder altitude acclimatization and thereby exacerbate acute mountain sickness (AMS) and compromise well-being. Twelve young males (21.2 +/- 0.4 years) received either 80 mg propranolol (PRO; n = 6) or placebo (PLA; n = 6), t.i.d. at sea level (SL) and during the first 15 d of a 19-d residence at 4,300 m (HA). Individuals were randomly assigned to each group. The Environmental Symptoms Questionnaire (ESQ) was administered at SL and twice daily (AM and PM) during the entire altitude exposure in order to assess AMS symptoms and subjective feelings of well-being. Supine heart rate (HR) was determined at rest twice at SL and four times at HA. HR in the PLA group increased 40% over SL values (57 +/- 3 to 80 +/- 4 beats/min) by day 7 at HA (p less than 0.01). HR in the PRO group did not increase above SL values during medication at HA. By 4 d after the medication administration was terminated, HR in the PRO group had increased and did not differ from the PLA group. Throughout the entire altitude exposure, ESQ scores for the PRO group were lower than or similar to the PLA group. Furthermore, cessation of PRO treatment did not result in a change in well-being. These findings suggested that interference with the normal acclimatization process by beta-adrenergic blockade did not exacerbate AMS or reduce feelings of well-being.

Acute Disease↗
PubMedDate not supplied

Reductive metabolism of nitrofurantoin in the rat.

The reductive metabolism of nitrofurantoin under anaerobic conditions was characterized in various tissues from control, germ-free, and germ-free acclimatized rats. Nitrofurantoin metabolism was highest in homogenates of cecum and colon contents of germ-free acclimatized and control rats, but was absent from those of germ-free animals. Appreciable levels of activity were also present in homogenates of liver and of small intestine walls with lesser rates of metabolism observed in kidney homogenates. The major metabolite of nitrofurantoin, which was isolated and purified by high-pressure liquid chromatography, was identified as 1-[[(3-cyano-1-oxopropyl)-methylene]amino]-2,4-imidazolidinedione. A second, minor metabolite with high-pressure liquid chromatography and ultraviolet absorption characteristics similar to those of 1-[[(5-amino-2-furanyl)methylene]amino]-2,4-imidazolidinedione (aminofurantoin) was detected in cecum and colon contents.

Anaerobiosis↗
PubMed1987

Pathophysiology of hypoxaemic pulmonary vascular diseases.

Chronic alveolar hypoxia whether due to living at high altitude or to lung disorders, such as chronic obstructive lung disease (COLD), leads to development of pulmonary arterial hypertension (PAH). Sustained PAH is the principal cause of right ventricular hypertrophy (RVH) and failure. The majority of high altitude residents, in spite of having moderate PAH and hypoxemia with some degree of RVH, manage to live actively and productively through acclimatization. Although the processes of acclimatization decrease the magnitude of oxygen (O2) pressure drop at each step of the O2 tension cascade, O2 pressures in the tissue capillaries and mixed venous blood are lower than those at sea level. Since the cardiac output and O2 consumption in residents at high altitude have been shown to be comparable to those of sea level residents, the importance of adaptive changes at the tissue level to facilitate diffusion and utilization of O2 must be emphasized. In patients with COLD and hypoxaemia, most of the adaptive changes that have been shown to operate in high altitude residents do not occur, or have not been observed consistently. At present, only long-term O2 therapy has been shown to improve survival and lower pulmonary artery pressure (Ppa), but the changes of the latter are generally too modest to explain the former. It may be that the improved survival is mainly achieved by correcting hypoxaemia, thereby improving tissue oxygenation, rather than lowering Ppa.

Altitude↗
PubMed1988

Inhibition by dietary ethanol of experimental colonic carcinogenesis induced by high-dose azoxymethane in F344 rats.

Epidemiological studies have shown an association between consumption of alcoholic beverages and increased occurrence of large bowel carcinoma, but studies in experimental models of colonic carcinogenesis have produced conflicting results. We assessed the effects of chronic dietary ethanol consumption during the preinduction and induction phase (period of acclimatization and carcinogen administration) in a high-dose azoxymethane-treated rat model (14 mg/kg/wk for 10 wk). Ten-wk-old male Fischer 344 rats were given 33% of calories as ethanol or no ethanol (controls). Pair-feeding with Lieber-DeCarli-type liquid diets provided comparable total carbohydrates, proteins, fats, and calories. After 3 wk of dietary acclimatization, injections of azoxymethane (AOM) were given s.c. to all rats in Wk 1 to 10. At necropsy in Wk 25, dramatic suppression of gastrointestinal tumorigenesis was evident in the ethanol-fed group: the prevalence of colonic tumors was 5% as compared with 91% in controls; and the prevalence of small bowel tumors was 0% versus 74% (P less than 0.0001). In an analogous study of [14C]AOM metabolism, exhaled 14CO2 was decreased in the ethanol-fed rats, indicating suppression of AOM metabolism. Similarly, in the ethanol-fed rats the levels of the DNA adducts O6-methylguanine and 7-methylguanine 24 h after AOM injection were reduced in the colonic mucosa to 14 +/- 7% and 61 +/- 11% of controls and in the liver to 80 +/- 9% and 86 +/- 6 of controls. By contrast, rats changed from the ethanol diet to no-ethanol diet for 12 h prior to the dose of [14C]AOM metabolized the carcinogen at a faster rate than controls, indicating loss of suppression with cessation of ethanol intake along with induction of metabolizing enzymes; DNA adduct levels were reduced in the colonic mucosa to 90 +/- 13% and 76 +/- 9% of controls and in the liver to 81 +/- 6% and 85 +/- 3% of controls. Our findings indicate that dietary ethanol during the preinduction and induction phase of the AOM model dramatically inhibits tumorigenesis, even with high dosage of carcinogen, and suggest that: (a) inhibition of tumorigenesis may result from suppression of metabolic activation of AOM and the consequent reduced formation of DNA adducts during the induction (initiation) phase of the model; (b) these anti-initiation effects of ethanol are unrelated to the epidemiological association between consumption of alcoholic beverages and large bowel cancer; and (c) mechanisms of action of agents found to modulate carcinogenesis in experimental models should be determined before the results can be generalized to human beings.

Alkylation↗
PubMed1986

Investigation of a fatal heatstroke.

On June 30, 1981, a young, apparently healthy, obese white male suffered a fatal heatstroke. This was the beginning of summer in southern Ohio, when mid-day temperatures can reach into the 30s degrees C (90s degrees F) and the humidity can climb above 70%. The predisposition of the individual in terms of acclimatization, physical size and dietary intake, along with strong motivation to perform well on a job requiring a heavy workload in a hot environment, pushed him beyond his physiologic capacity. Of those people who attended him, only professional rescue personnel recognized the illness and properly treated the man. The death may have prevented by acclimatization and training as to the hazards, recognition and treatment of heat illness.

Adult↗
PubMed1985

Assessment of immunological responsiveness in members of International Biomedical Expedition to the Antarctic 1980/81.

Analysis of immune responsiveness was performed in members of the IBEA during a controlled trial of acclimatization with cold baths and during the subsequent 71 day period of Antarctic isolation. Several parameters of humoral and cellular immunity were assessed. No differences were found for those individuals who underwent cold-acclimatization in the first phase of the expedition. On the ice-cap all members showed slight elevation of their immunoglobulins, the increase in IgA reaching significance (p less than 0.05). Values returned to normal on returning to Sydney. Enhanced reactivity to the mycobacterium antigen purified protein derivative (PPD) was found on the ice-cap with 4 individuals becoming positive and remaining so on returning to Sydney. There was no obvious exposure to mycobacterium during the expedition but it is recommended that in future expeditions all PPD negative individuals be vaccinated with BCG.

Adaptation, Physiological↗
PubMed1983

Perspectives on functional adaptation of the high altitude native.

The major physiological processes that enable humans to attain a complete acclimatization to high altitude are briefly reviewed. The available data indicate that: (a) complete acclimatization to high altitude is associated with changes of environmentally modifiable functional traits such as lung volume but not associated with the expression of genetically controlled features such as chest size; (b) as judged by measurements of maximal aerobic power, the high altitude native has attained at high altitude an adaptation that is comparable to that attained by the low altitude native at sea level; the available information suggests that such adaptation is acquired through growth and development in an hypoxic environment; at present, however, we do not know the developmental modifications that occur within each component of the oxygen transport system, such as ventilation, pulmonary diffusion, and oxygen transport, that enable a sea level native to attain a complete functional adaptation to high altitude; and (c) at comparable altitudes among high altitude natives, there are some inter-regional differences in hemopoietic response, so that the samples derived from mining regions of the Andes are characterized by higher hemoglobin concentration than those derived from non-mining areas or the Himalayas. The source of these differences remains to be investigated.

Adaptation, Physiological↗
PubMed1982

[Effect of temperature increase on some aspects of nitrogen catabolism in rainbow trout (Salmo gairdneri Rich.)].

Rainbow trout acclimatized to 9 degrees C were subjected to a temperature increase (up to 17 degrees C) for 16 hrs. During the period of acclimatization to 17 degrees C, we studied blood ammonia and urea and the hepatic activity of glutamate dehydrogenase, glutaminase, uricase and arginase. The daily mean rates of blood ammonia and urea did not differ significantly at 9 and 17 degrees C. However, the pattern of these two parameters during the circadian cycle was not the same at 9 degrees C as after 23 days at 17 degrees C. The enzymatic activities rose after one day at 17 degrees C and remained unchanged, except for arginase which showed perfect thermal compensation. During the circadian cycle, there was some similitude between glutaminase activity and blood ammonia at 9 degrees C and after 23 days at 17 degrees C, as well as between arginase activity and blood urea.

Ammonia↗
PubMedDate not supplied

[Hormonal variation during physical exertion at high altitude].

The influence of the physical exercise at high altitude on the endocrine function was studied in 8 normal native men of sea level and in 8 natives men of high altitude. The sea level dwellers were studied both, at sea level, during an acute exposure to low barometric pressure and after 3 months of acclimatization to altitudes over 3,500 meters above the sea level. The experiments at high altitude were conducted at an altitude of 4,500 meters above the sea level. Two types of exercise were carried out, sub-maximal and maximal, at fasting state, between 8 and 10 a.m. During an acute exposure to altitude the physical exercise produced a marked rise of glucose, cortisol and growth hormone and a fall in the insulin content of plasma. In the sea level dwellers, acclimatized to altitude during 3 months, an elevation of growth hormone was observed only during maximal physical effort. Marked variation in glucose and cortisol were observed during both types of exercise. This shows that in these subjects some adaptative changes have ocurred but of lesser extent as those observed in altitude natives. In the high altitude native higher basal concentrations of growth hormone and glucagón as well as a lower glucose concentration in blood, were found. During exercise the high altitude dweller showed no significant changes in somatotropin, meanwhile an important elevation of cortisol occurred. These findings indicate that the high altitude native has metabolic and endocrine responses to exercise similar to those found in well fitted atletes of sea level. The exposure to altitude provoked a rise in glucagon concentration directly proportional to the time of exposition ot altitude. The physical exercise did not elucidate any change in the glucagon content of blood.

Adult↗
PubMed1978

Microbial degradation of diethanolamine and related compounds.

Thirteen diethanolamine compounds were tested for their biodegradability employing (1) a bacterium selectively isolated from an industral cutting fluid, and (2) an acclimatized sewage population obtained from a domestic waste treatment plant. Pure culture growth and biochemical oxygen demand studies with the isolate showed that only diethanolamine, methyl-diethanolamine, triethanolamine, and laurylsulphate-diethanolamine were degradable. Biochemical oxygen demand techniques using the acclimatized sewage micro-organisms as seed yielded similar results with only diethanolamine, methyl-diethanolamine, triethanolamine, and laurylsulphate-diethanolamine being oxidized to any meaningful extent. Cyclohexyldiethanolamine, phenyl-diethanolamine, and m-tolyl-diethanolamine had oxygen demands of less than 1% of their theoretically calculated values, while ethyl-diethanolamine and benzyl-diethanolamine accounted for 3.6 and 2.3% of their theoretical values respectively. In both systems employed substitution of the tertiary hydrogen of the amine group with isopropyl, 3-aminopropyl, n-butyl, or t-butyl resulted in biologically recalcitrant compounds.

Bacteria↗
PubMed1975

[The rat ventricular myocardium in chronic hypercapnia. Electron microscopic study].

An electron microscope study of the left ventricular myocardium from rat acclimatized to chronic hypercapnia was done in order to complete the preceding work concerning general effects of respiratory acidosis. After 15 and 30 days of the acclimatation to 8% CO2 no lesions of the myocardium could be found. The results of the morphometric analysis indicated, however, discrete modifications of heart ultrastructure similar to those found before in hypoxic and failing hearts: namely a decrease of mitochondrial mean diameter and a non significant decrease of mitochondrial fractional volume. The latter was accompanied by a significant decrease of myofibrillar mass. The presence of cellular oedema seems to be suggested by an increase of fractional volume of the cytosol. The mechanism of these changes is not easy to explain. Further work will be necessary to make a choice between two possibilities: (1) depressed contractility related to some direct effect of high pCO2 and (2) tissue hypoxia secondary to local effects of the former.

Animals↗