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PubMed2003

[Sleep and breathing at altitude of 3800 m--the acclimatization effect].

UNLABELLED: Periodic breathing (PB) is a very common phenomenon occurring during sleep at high altitude. It consists of repetitive apneas or hypopneas of central origin and clusters of hyperpneic breaths. The aim of this study was to analyze sleep structure and periodic breathing in shift workers of a gold mine situated in Tien-Schan Mountains at 3800 m. In 12 subjects aged 36.1 +/- 9.3 yrs, polysomnography (PSG) was performed twice, on the night after the first working shift or during the day following first night shift, and the second PSG at the end of the first week of work. After one week, significant increase in REM sleep was noticed (5.2 +/- 4.0% vs. 12.0 +/- 6.7%, p < 0.05). There were no differences in sleep pattern between night sleep and sleep during daytime. During first PSG periodic breathing was seen in all subjects and occupied 14.7 +/- 16.6% of total sleep time. After one week PB decreased in 8 subjects however, in 4 subjects an increase in PB was observed (15.4 +/- 11.2 vs. 29.0 +/- 11.8% of sleep time). CONCLUSIONS: Sleep at altitude is characterized by reduction of REM sleep, which improves after a week of acclimatization. There are great individual variations in duration of periodic breathing; in some subjects an increase in PB can be seen.

Acclimatization↗
PubMed1991

Factors affecting laboratory acclimatization of field collected Lymnaea (Bullastra) cumingiana Pfeiffer (Pulmonata: Lymnaeidae).

Lymnaea (Bullastra) cumingiana, the newly discovered natural second intermediate host of Echinostoma malayanum in the Philippines, is a sensitive and delicate lymnaeid species which requires certain conditions for successful transport from the field and cultivation in the laboratory. Field collected specimens were found to be best transported in styrofoam containers lined with wet filter paper or containing natural substrate and vegetation instead of Sphagnum moss. The method is convenient and produces a survival rate of 73-86%. However, transport time is crucial and mortality increases the longer the snails are in transit. For optimal results in laboratory acclimatization, snails are best raised in wide-mouthed containers providing a large exposed water surface area. Adequate aeration is advised but vigorous bubbling of the water should be avoided. Water should be replaced with filtered dechlorinated water every 2 to 3 days, depending on water quality. A combination of fresh lettuce leaves and a few flakes of fish food was found to be ideal. Lastly, population density was the most significant factor affecting survival and so overcrowding should be avoided.

Acclimatization↗
PubMed1989

Effect of post-hypoxic acclimatization on extremity temperature during exposure to acute cold stress in man.

Twelve male volunteers aged 20-28 yr, who were physically fit for high altitude duties were studied. Recordings of oral temperature, mean skin temperature, extremity temperature, O2 consumption and heart rate were taken in a thermoneutral room (26 degrees +/- 2 degrees C) and cold room (6 degrees-8 degrees C) initially; after 4 wk stay at 3353 m (502 mm Hg); again after 4 wk at 4115 m (455 mm Hg); and finally after return to Delhi (740 mm Hg). The oral temperature, mean skin temperature, oxygen consumption and heart rate did not show any significant difference from their initial sea level values recorded in the thermoneutral room or the cold room. It may be concluded that our subjects did not exhibit any degree cold acclimatization when retested at sea level. A significant elevation (P less than 0.001) of extremity temperature observed during retest in cold might be due to some degree of vasodilatation through relaxation of constrictor tone that might have taken place during exposure to hypoxia at high altitude.

Acclimatization↗
PubMed1986

[Immunological status of monkeys during acclimatization and its correction with levamisole].

The work presents the results of investigations, carried out in different monkey species, on the physiological norms as regards the bactericidal factors of neutrophilic polymorphonuclear leukocytes in the blood, nonenzymatic lysosomal cationic proteins and myeloperoxidase, as well as on changes in these characteristics in monkeys at different periods of their acclimatization at the Institute of Experimental Pathology and Therapy, Sukhumi. The possibility of correcting the characteristics under study by means of the immunostimulating agent levamisole is shown.

Acclimatization↗
PubMed1988

Intestinal parasites in novice black miners. Prevalence and possible effect on heat acclimatization.

A study of 189 black novice miners at two goldmines showed: (i) an overall prevalence of parasites of 62%; (ii) that parasitization has no significant effect on physical fitness or the ability to acclimatize to heat; (iii) that parasitization does not appear to predispose to more frequent consultations at the mine dressing-stations; and (iv) that haemoglobin, although showing regional variation, was unaffected by parasite status, but eosinophil counts did show significant differences.

Acclimatization↗
PubMedDate not supplied

An inquiry into the role of cardiac filling pressure in acclimatization to heat.

During the first exposure of exercising subjects to hot environments (30-50 degrees C), cardiac output, heart rate, and body temperature increase over that seen in cool environments, while stroke volume decreases. If daily heat exposures occur, during the second heat exposure, heart rates and rectal temperatures are decreased from day 1 while cardiac output is maintained. This decrease in physiological strain occurs with little or no increase in evaporative heat loss. The alleviating agent appears to be an expansion of plasma volume. Several brief studies have indicated decreases in cardiac filling pressure during exercise in heat, and though inferential, it appears that the progressive increase in plasma volume during the first five to six days of heat exposure assists in maintaining cardiac filling pressure. Later, with increased evaporative heat loss due to increased sweat secretion, the mechanism of supplying increased volume to maintain cardiac filling is changed; fluid is transferred from extravascular to intravascular compartment, thus protecting venous return and cardiac filling pressure. These statements are based on limited data, and there is need of experiments designed to confirm or deny certain conclusions as to the role of cardiac filling pressure in acclimatization to heat.

Acclimatization↗
PubMed1984

Effects of high hydrostatic pressure on catecholamine contents in tissues of the eel acclimatized at two temperatures.

Catecholamines (CA) are involved in many adaptative mechanisms of an organism to its environment. In fish, pressure is an environmental factor able to modify these mechanisms of adaptation, and some of the physiological perturbations observed under pressure can be compared to CA unloading. Moreover, the metabolic rate, and probably the CA metabolism of fish, are modified by the ambient temperature. This study has been conducted to measure tissue (brain and heart) CA contents (dopamine, norepinephrine, epinephrine) of eels acclimatized for 15 d at two temperatures, Tw, (15 degrees C or 25 degrees C). The measurements have been made either at atmospheric pressure (1 ATA) or after 60 min at 101 ATA of hydrostatic pressure "per se." The results show that 1) at a given Tw, pressure has no significant effect on tissue CA contents; and 2) there seems to exist a pressure-temperature antagonism concerning dopamine and epinephrine in the brain. It is suggested that this antagonism acts on enzymatic systems involved in the metabolism of these two amines.

Acclimatization↗
PubMedDate not supplied

[Activity of arginase and proteolytic processes in the brain and liver of rats in cold acclimatization].

The activity of arginase, neutral peptidohydrolase (protaminase) and total intensity of autolysis were determined in the brain and liver of rats on the 1st, 3d, 30th and 45th days animal stay at a temperature of 2-4 degrees C. in the process of rats acclimatization to cold there occurs a correlation in the brain - between the activity of arginase and neutral peptidohydrolase, in the liver - between the arginase activity and total proteolytical activity (autolysis).

Acclimatization↗
PubMed1981

[Thermal acclimatation in rats. I. Influence on reproductivity and fetal development].

Virgin female rats were kept in rooms where temperature was about 5 degrees C higher or lower than standard rearing temperature for two weeks before mating and during pregnancy. Acclimatation to changed environmental conditions caused reproductive alterations: ovulation increase; decrease of implanting blastocists and/or viable foetuses; developmental defects.

Acclimatization↗
PubMed1980

Responses of physically active and acclimatized men and women to exercise in a desert environment.

In most studies of physiological responses of men and women to exercise in the heat, the subjects are unacclimatized and the females are unaccustomed to strenuous physical activity. In this investigation, 5 men and 6 women known to be physically active in an outdoor hot-dry environment were studied in a temperate environment (Tdb=23C, WBGT=18C) and in an outdoor desert environment (Tdb=39C, WBGT=29C) during rest and exercise at 50% Vo2max. No differences between the groups occurred in Vo2, HR or Tre in either environment. Of greatest interest was that no differences occurred in evaporative weight losses, sweating rates, or % body weight losses in the heat. It was concluded that (1) women accustomed to exercise in a desert climate are able to substantially increase their sudorific response, and (2) that acclimatized male and female subjects of similar aerobic capacity have comparable responses to rest and exercise in a desert environment.

Acclimatization↗
PubMed1995

[Periodic breathing at high altitude relation to acclimatization and acute mountain sickness].

Periodic breathing (PB) during sleep at an altitude of 5100 m was studied with a pulse oximeter. The subjects were six Japanese who stayed at about 5100 m (group A), nine Japanese who climbed above 7000 m (group B) and eight Sherpase (high landers). Among Japanese subjects, PB was observed most often in group A. The sherpas almost never breathed periodically. PB and symptoms of acute mountain sickness correlated positively among Japanese subjects. The cycle time of PB did not differ among the three groups. PB may be related to acclimatization.

Acclimatization↗
PubMed1996

Respiratory changes during initial days of acclimatization to increasing altitudes.

METHOD: The daily changes in respiratory function were monitored in 16 healthy male road inductees at sea level (SL) and at high altitudes (HA) of 3110 m, 3445 m, and 4177 m. Identical studies were also carried out on acclimatized low landers (ALL) staying at 3110 m and at 4177 m for 2 years. RESULTS: Ventilation, tidal volume, and respiratory rate showed significant increases on arrival at HA and remained high during the entire period of observation (p < 0.001). These parameters did not show any appreciable difference between 3110 m and 3445 m. Forced vital capacity (FVC) and forced expiratory volume (L) in 1.0-s (FEC1.0) also did not change on the first day of arrival at HA but decreased significantly (p < 0.001) on the second day at 3110 m. However, both FVC and FEV1.0(L) returned to SL values by day 3 but declined further at 3445 m and at 4177 m. Forced expiratory flow and maximum voluntary ventilation declined on arrival at HA. Peak expiratory flow rate, however, tended to decline during initial days but increased by day 3 and remained elevated during the subsequent residence. Respiratory adaptation to hypoxia in ALL appeared to be different at 3110 m as compared to that at 4177 m. At higher altitude the lung volumes and capacities were markedly decreased, whereas at lower altitudes these parameters were comparable to SL values. CONCLUSION: We conclude that initial respiratory adjustments in sojourners occur by day 3 at 3110 m and show further decrement at 4177 m with a cyclic variation on day 6, while ALL manifest variability in respiratory adaptation at different altitudes.

Acclimatization↗
PubMed1997

[Effect of norepinephrine on the thermosensitive neurons in preoptic area of hypothalamus tissue slices in cold acclimatized rats].

In this work, single unit firing activities were recorded in the preoptic anterior hypothalamus (POAH) brain slices of cold acclimatized and room-temperature housed rats (CR and RR) and the effects of NE on the neuronal discharges were observed. The neurons of POAH in CR became much more sensitive to NE than that in RR (the threshold concentration of NE of CR became significantly lowered). In comparison with RR, the percentage of warm sensitive neurons that could be excited by NE was decreased and some of them even showed inhibitory responses. On the other hand, the percentage of cold sensitive neurons that could be inhibited by NE was decreased and some of them even showed excitatory responses. The percentage of thermo-insensitive neurons that could be either excited or inhibited by NE were increased.

Acclimatization↗
PubMed1996

Cellular changes during cold acclimatation in adipose tissues.

Cold exposure is a well-known physiological stimulus that activates the sympathetic nervous system and induces brown adipose tissue (BAT) hyperplasia. The effects of cold exposure or cold acclimatation have been extensively studied in interscapular BAT (IBAT). However, it has been recently shown that studied adipocytes are present in adipose deposits considered as white fat such as periovarian (PO) fat pad. We have investigated the kinetic of brown precursor recruitment in adipose tissues using DNA measurement and specific marker expression. In IBAT, cold exposure induces proliferation of precursor cells and differentiation into preadipocytes characterized by the expression of A2COL6, a marker specific to early steps of the differentiation process. A chronic stimulation of the tissue is necessary to observe the full effect. In PO fat pad, no proliferation can be detected, whereas differentiation of brown preadipocytes and maybe phenotypic conversion of white adipocytes seems to be promoted. In conclusion, these data demonstrated that 1) the same stimulus (cold exposure) does not induce the same response in terms of preadipocyte proliferation and differentiation in periovarian and brown adipose tissues, although both contain brown adipocytes, and 2) preadipocyte recruitment in adipose tissues after cold exposure depends on the predominant type of fat cells.

Adaptation, Physiological↗
PubMed2003

Mesophilic and thermophilic BTEX substrate interactions for a toluene-acclimatized biofilter.

Benzene, toluene, ethylbenzene and xylene (BTEX) substrate interactions for a mesophilic (25 degrees C) and thermophilic (50 degrees C) toluene-acclimatized composted pine bark biofilter were investigated. Toluene, benzene, ethylbenzene, o-xylene, m-xylene and p-xylene removal efficiencies, both individually and in paired mixtures with toluene (1:1 ratio), were determined at a total loading rate of 18.1 g m(-3) h(-1) and retention time ranges of 0.5-3.0 min and 0.6-3.8 min for mesophilic and thermophilic biofilters, respectively. Overall, toluene degradation rates under mesophilic conditions were superior to degradation rates of individual BEX compounds. With the exception of p-xylene, higher removal efficiencies were achieved for individual BEX compounds compared to toluene under thermophilic conditions. Overall BEX compound degradation under mesophilic conditions was ranked as ethylbenzene >benzene > o-xylene > m-xylene > p-xylene. Under thermophilic conditions overall BEX compound degradation was ranked as benzene > o-xylene >ethylbenzene > m-xylene > p-xylene. With the exception of o-xylene, the presence of toluene in paired mixtures with BEX compounds resulted in enhanced removal efficiencies of BEX compounds, under both mesophilic and thermophilic conditions. A substrate interaction index was calculated to compare removal efficiencies at a retention time of 0.8 min (50 s). A reduction in toluene removal efficiencies (negative interaction) in the presence of individual BEX compounds was observed under mesophilic conditions, while enhanced toluene removal efficiency was achieved in the presence of other BEX compounds, with the exception of p-xylene under thermophilic conditions.

Bacteria↗
PubMed1986

Acute and chronic pulmonary pressor responses to hypoxia: the role of blunting in acclimatization.

We studied two strains of Sprague-Dawley rats: the Madison (M) that acclimatizes successfully to high altitude; and the Hilltop (H), that manifests signs of chronic mountain sickness at high altitude and has a high mortality rate. Awake, chronically instrumented animals were tested at sea level, at intervals during 30 days at a simulated altitude of 5500 m, and during 10 to 15 days of recovery at sea level. Mean pulmonary artery pressure (PAP) rose at high altitude to reach 60 mm Hg in H and 40 mm Hg in M, but the acute pressor response to hypoxia at sea level was much more pronounced in M than H. Depression of PAP by normoxic exposures in H rats at high altitude was slightly early in the period of stay but was enhanced with further prolongation of high altitude residence. The M rats, in contrast, had a blunted response (normoxia had very little depressant effect on PAP) after the first 24 h at high altitude, and it remained so for the duration of the stay. On return to sea level the response of H rats remained unchanged for 7 days, but the blunted response of the M rats at high altitude reversed at sea level to become exaggerated. We conclude: that responses of PAP to acute hypoxia do not forecast what the chronic response will be; that the appearance of an unidentified mechanism during chronic hypoxia in the M strain attenuates the vasoreactivity of the pulmonary vessels to hypoxia; and that the absence of such a blunting mechanism in H leads to the higher PAP in this strain and its morbid consequences. The hypothesis is put forward that the existence of such a blunting mechanism is an important factor in the adaptability of species to high altitude.

Adaptation, Physiological↗
PubMed1995

Effects of carotid body sympathetic denervation on ventilatory acclimatization to hypoxia in the goat.

Our objective was to test the hypothesis that diminishing sympathetic input to the carotid body (CB) during prolonged exposure to hypoxia results in increased CB afferent activity and increased ventilatory drive. Six awake goats were studied prior to and following sectioning of the efferent sympathetic input to the CB from the superior cervical ganglion. Ventilatory responses to acute and prolonged isocapnic hypoxia (PaO2 40 Torr) and drugs (norepinephrine and dopamine, 0.5, 1.0 and 5.0 micrograms.kg-1 min-1) were collected prior to the denervation. One week and 3-4 weeks following the sympathetic denervation, the animals were restudied following the above protocol. Ventilation was significantly lower following sympathetic denervation in normoxia and during the hypoxic exposure. However, the response to acute hypoxia and the time-course of ventilatory acclimatization to hypoxia was not altered by sympathetic denervation. All doses of norepinephrine and dopamine significantly inhibited VE in a dose-dependent manner. Sympathetic denervation did not significantly alter the response to the drug infusions. The sympathetic innervation to the CB does not appear to play a role in either the acute or prolonged ventilatory responses to hypoxia in the awake goat, but may affect overall ventilation.

Animals↗
PubMed2006

Medicinal potential from in vivo and acclimatized plants of Cleome rosea.

Methanolic extracts obtained from different organs of Cleome rosea, collected from its natural habitat and from in vitro-propagated plants, were submitted to in vitro biological assays. Inhibition of nitric oxide (NO) production by J774 macrophages and antioxidant effects by protecting the plasmid DNA from the SnCl(2)-induced damage were evaluated. Extracts from the stem of both origins and leaf of natural plants inhibited NO production. The plasmid DNA strand breaks induced by SnCl(2) were reduced by extracts from either leaf or stem of both sources. On the other hand, root extracts did not show any kind of effects on plasmid DNA, and presented significant toxic effects to J774 cells. The results showed that C. rosea presents medicinal potential and that the acclimatization process reduces the plant toxicity both to plasmid DNA and to J774 cells, suggesting the use of biotechnology tools to obtain elite plants as source of botanical material for pharmacological and phytochemical studies.

Animals↗