Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cold Climate”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources
PubMed1989

Cold-induced mitochondrial degradation and cryoprotectant synthesis in freeze-tolerant arctic caterpillars.

The larvae of Gynaephora groenlandica, a long-lived moth endemic to the high arctic, are perennially freeze-tolerant and able to increase their freeze-tolerance by synthesizing glycerol. Cold-induced mitochondrial changes were correlated (using electron microscopy, DNA staining, cytochrome c assay, and oxygen uptake) with glycerol production (using NMR spectroscopy) in larvae under different acclimations and in the field. Hypometabolism in summer- or warm-acclimated larvae led to glycerol accumulation. Extended exposure to near-zero or freezing temperatures caused mitochondrial degradation and glycerol accumulation. Rapid freezing of warm-acclimated larvae did not result in mitochondrial breakdown. Mitochondrial reconstitution upon warm-acclimation occurred much more rapidly (less than 1 week) than did degradation (greater than 2 months). Concomitant with mitochondrial breakdown was reduced oxidative metabolism, but the cytochrome c concentration remained independent of acclimation temperature. The adaptive response to cold by mitochondrial degradation and glycerol accumulation by G. groenlandica may be linked to diapause in other species of ectotherms.

Acclimatization↗
PubMed1995

Cold: a risk factor for stroke?

A retrospective study was performed to investigate seasonal variation in stroke incidence and to evaluate the hypothesis that cold might be a risk factor. Data were obtained from the central registry of the Hospital de S. João, Porto, Portugal, concerning 4048 patients consecutively admitted for cerebrovascular disease during a period of 33 months. Monthly admissions for stroke and its subtypes were related to mean values of ambient temperature using linear correlation. There was a strong inverse correlation between average temperature and total admissions for cerebrovascular disease (r = -0.72, P < 0.00005), intracerebral haemorrhage (r = -0.66, P < 0.00005), ischaemic stroke (r = -0.46, P = 0.007) and transient ischaemic attack (r = -0.41, P = 0.017). These correlations were independent of any seasonal variation in the number of hospital admissions due to all causes. No relation was found between temperature and subarachnoid haemorrhage. The rhythmometric analysis showed the presence of a statistically significant rhythm with an acrophase in the coldest months. These results support the hypothesis of stroke being a chronorisk disease to which cold might represent a triggering factor.

Cerebrovascular Disorders↗
PubMed1984

The Antarctic cryptoendolithic ecosystem: relevance to exobiology.

Cryptoendolithic microorganisms in the Antarctic desert live inside porous sandstone rocks, protected by a thin rock crust. While the rock surface is abiotic, the microclimate inside the rock is comparatively mild. These organisms may have descended from early, pre-glaciation Antarctic life forms and thus may represent the last outpost of life in a gradually deteriorating environment. Assuming that life once arose on Mars, it is conceivable that, following the loss of water, the last of surviving organisms withdrew to similar insulated microenvironments. Because such microscopic pockets have little connection with the outside environment, their detection may be difficult. The chances that the Viking lander could sample cryptoendolithic microorganisms in the Antarctic desert would be infinitesimal.

Arctic Regions↗
PubMed1991

Estimation of cold stress effect on dairy cows.

Twelve crossbred heifers (Slovak Spotted x Holstein-Friesian) were housed in an open, uninsulated barn with straw bedding and a concrete-floored yard. Minimum temperatures inside the barn were as low as -19 degrees C. The average milk yield decreased as the temperatures approached these minima. Compared with the temperature conditions, the feed intake and blood levels of glucose and free fatty acids increased. The level of sodium declined significantly during the second cold period. Correlations and regressions between milk yield and biochemical parameters were calculated, and the results indicate that the concentrations of free fatty acids, cholesterol, and triiodothyronine and the haematocrit values may serve to predict milk production during periods of cold stress, or in lactations of 305 days.

Animals↗
PubMed1991

Accidental hypothermia and death from cold in urban areas.

Hypothermia is considered a serious problem in big cities. In order to clarify factors contributing to urban hypothermia and death from cold, which will continue to be an issue in cities in the future, we analyzed autopsy reports recorded in the Tokyo Medical Examiner's Office from 1974 to 1983. In a total of 18,346 autopsy reports 157 deaths had been diagnosed as due to exposure to cold. Of these cases, the greatest number were males in their forties and fifties, and most of these were inebriated and/or homeless. Eighty-four percent of urban hypothermia cases occurred when the outdoor temperature was below 5 degrees C, and 50% of deaths from cold occurred when the outdoor temperature was between 0 degrees and 5 degrees C. There were no incidences of death from cold when the minimum outdoor temperature had remained above 16 degrees C. Seventy-four percent of deaths from cold occurred during the winter months of December, January and February, and most of the remaining deaths occurred in March and November. There were no deaths from cold from June to August. More than half of all deaths from cold occurred from 3.00 a.m. to 9.00 a.m., with the peak occurring at 5.00 a.m. A blood alcohol concentration of over 2.5 mg/ml had often been found in those in their forties and fifties who had died from hypothermia, and autopsy had often revealed disorders of the liver, digestive system, and circulatory system. Chronic lesions of the liver, probably due to alcoholism, were found in many cases; few cases showed no evidence of alcoholism and these were significantly different from the former group.

Accidents↗
PubMed1990

Hematological variations at rest and during maximal and submaximal exercise in a cold (0 degree C) environment.

The affect of negative thermal stress on hematological variables at rest, and during submaximal (sub ex) and maximal exercise (max ex) were observed for young males who volunteered in two experimental sessions, performed in cold (0 degree C) and in normal room temperature (20 degrees C). At rest, hematological variables such as RBC and derivates Hb and Hct were significantly increased (P less than 0.05) during cold stress exposure, while plasma volume decreased. The findings of this study suggest that the major factor inducing hypovolemia during low thermal stress can be imputed to local plasma water-shift mechanisms and especially to a transient shift of plasma water from intra- to extravascular compartments. Rest values for WBC and platelets (Pla) were also slightly increased during cold stress exposure. However this increase can partly be related to hemoconcentration but also to the cold induced hyperventilation activating the lung circulation. Maximal exhaustive exercise induced, in both experimental temperatures, significant (P less than 0.05) increments of RBC, Hb, Hct, and WBC while plasma volume decreased. However, Pla increase was less marked. On the other hand, cold stress raised slightly the observed variations of the different hematological variables. Submaximal exercise induced a similar, though non-significant, pattern for the different hematological variables in both experimental conditions. Observed plasma volume (delta PV%) reduction appears during exercise. However cold stress induced resting plasma volume variations that are transferred at every exercise level. Neither exercise nor cold inducement significantly modified the hematological indices (MCH, MCV, MCHC). In conclusion hematological variables are affected by cold stress exposure, even when subjects perform a physical activity.

Acclimatization↗
PubMed1989

Temperature and cardiovascular deaths in Montreal.

The incidence of mortality from myocardial infarction over a 2-year period in Montreal is examined in relation to temperatures and snowfall. Mortality is seen to increase with deviations from seasonally determined thermally neutral conditions, although compared to observations of a parallel study in subtropical Brisbane, death rates are lower with similar falls in temperature. In Montreal, mortality is also seen to increase with snow during the previous day. During anomalous cold spells death frequencies decrease, a phenomenon interpreted as the behavioural thermoregulatory process of cold avoidance.

Cold Climate↗
PubMed1991

Effects of cold stress on glutathione and related enzymes in rat erythrocytes.

Effects of acute and chronic cold stress on glutathione and related enzymes in rat erythrocytes were investigated. Blood from both cold-acclimated (CA) and cold-adapted (CG) rats had significantly lower concentrations of glutathione than blood from control animals. Superoxide dismutase activity was increased significantly in CA rats and tended to rise in CG rats. Activity of glutathione peroxidase in erythrocytes was inconsistent in that it tended to increase in CA rats but decreased significantly in CG rats. The results may imply that CG rats suffered deleterious effects of hydrogen peroxide. On the other hand, there were marked decreases in glutathione peroxidase and glutathione reductase activities in acutely cold-exposed rats in conjunction with unchanged levels of glutathione. In all treatments the state of riboflavin metabolism was estimated to be adequate, since no increases were observed in the erythrocyte glutathione reductase activity coefficient.

Animals↗
PubMedDate not supplied

The systemic approach to the stability and plasticity of neurophysiological processes during adaptive brain activity.

The problem of the stability and adaptability of regulatory processes is considered, taking as a point of departure N. P. Bekhtereva's theory regarding stable pathological states, and inflexible and adaptable links in control systems. The need to introduce a probabilistic approach is emphasized. Generalizations are made on materials relating to the connectability of the separate components of the biorhythms of functional systems, and to the stability of their amplitude-frequency characteristics. The corpus of facts permitted the successful development in clinical practice of functional biocontrol and feedback.

Adaptation, Physiological↗
PubMed1995

Seasonal variation in physiological responses to mild cold air in young and older men.

Eight men aged 60-65 years and six men aged 20-25 years, wearing only swimming trunks, were exposed to an air temperature of 17 degrees C and 45% R.H. in each of the four seasons. The increase in the rate of metabolic heat production (% delta M) for the older group in the cold test was significantly higher in summer and autumn than in winter and spring (P < 0.05), but did not differ in the young group between seasons. Compared to the young group the % delta M was significantly greater for the older group (due to a marked increase in four individuals) in summer and autumn (P < 0.04). At the end of the period of cold exposure, the decrements of rectal temperature (delta Tre), mean skin temperature (Tsk; due to a marked decrease in four individuals) and foot skin temperature (Tfoot) were significantly greater for the older group compared to the young group at all times of the year (P < 0.003). Seasonal variations in the two groups were similar, e.g., the delta Tre gradually became smaller from summer to winter (P < 0.05) and then increased slightly in the spring (P = 0.07). Tfoot for both groups decreased from summer to autumn (P < 0.01) and remained unchanged subsequently. No seasonal variations were observed for Tsk in either group. The increase in diastolic blood pressure (BPd) during the test was significantly smaller in winter in both groups (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1995

The relationship between chinook conditions and women's physical and mental well-being.

The objective of this study was (1) to determine the relationship between chinook conditions and physical and psychological symptoms in women aged 20-49 years, and (2) to examine the possibility of subgroups of chinook-sensitive women. The evidence for this relationship is at present merely anecdotal. The study carried out in 1985-1986 in Calgary comprises the secondary analysis of a large survey of various health and health-related factors, including different symptoms, of urban women aged 20-49 years. The interview date was used to link these data to days on which pre-chinook, chinook, post-chinook and non-chinook conditions occurred. Between November 1, 1985 and February 28, 1986, 182 women were interviewed on pre-chinook days, 74 on chinook days, 229 on post-chinook days and 886 on non-chinook days. Autonomic reactions and skin disorders were found to be significantly related to chinook conditions. None of the psychological symptoms was related to chinook conditions. However, a significant relationship was found between symptoms and chinook conditions in women with a history of emotional disorders. This type of information is important to educate chinook-sensitive women and health professionals as well as for hospital emergency departments in order to be able to prepare for potential increases in workload.

Acclimatization↗
PubMed1995

The relationship between chinook conditions and women's illness-related behaviours.

The objective of this study was to (1) to describe the relationship between chinook conditions and illness related behaviour in women, aged 20-49 years, and (2) to examine the possibility of the existence of subgroups of chinook-sensitive women. At present no empirical evidence is available regarding a relationship between chinook conditions and illness related behaviours. This study comprises the secondary analysis of a large survey of various health and health-related factors of urban women aged 20-49 years, carried out in 1985-1986 in Calgary. The interview date was used to link behaviours to chinook conditions. We found no evidence of a significant relationship between the behaviours investigated and chinook conditions in the general population. However, the data strongly supported the concept of chinook sensitivity. Women with a history of chronic health problems were more likely to visit a health care professional on chinook days than healthy women and women in the subgroup aged less than 35 years cut down their usual daily activities during chinook conditions. Women with a history of recurring migraine headaches were less likely to take prescription medication on chinook days, and women with a history of emotional disorders were more likely to have higher scores on the accident scale and to report bursts of energy or excitement during chinook days. More research is needed to identify subgroups of susceptible persons, as well as to determine whether chinook sensitive persons are equally susceptible to weather changer of other types.

Adult↗
PubMed1992

Myocardial infarct death and temperature in Auckland, New Zealand.

Daily myocardial infarct deaths for Auckland (36 degrees 51'S, 20 m above sea-level) show an increase in mortality rate with decreasing temperatures over the entire thermal range. Parallel studies in Brisbane and Montreal predicted a minimum death temperature between 21 and 24 degrees C, but no such point was apparent. Lack of temperatures above 21 degrees C, together with the small overall thermal range, is thought responsible.

Aged↗
PubMed1995

Predicting survival time for cold exposure.

The prediction of survival time (ST) for cold exposure is speculative as reliable controlled data of deep hypothermia are unavailable. At best, guidance can be obtained from case histories of accidental exposure. This study describes the development of a mathematical model for the prediction of ST under sedentary conditions in the cold. The model is based on steady-state heat conduction in a single cylinder comprised of a core and two concentric annular shells representing the fat plus skin and the clothing plus still boundary layer, respectively. The ambient condition can be either air or water; the distinction is made by assigning different values of insulation to the still boundary layer. Metabolic heat production (M) is comprised of resting and shivering components with the latter predicted by temperature signals from the core and skin. Where the cold expousure is too severe for M to balance heat loss, ST is largely determined by the rate of heat loss from the body. Where a balance occurs, ST is govedrned by the endurance time for shivering. End of survival is marked by the deep core temperature reacing a value of 30 degrees C. Th emodel was calibrated against survival data of cold water (0 to 20 degrees C) immersion and then applied to cold air exposure. A sampling of ST predictions for the nude exposure of an average healthy male in relatively calm air (1 km/h wind speed) are the following: 1.8, 2.5, 4.1, 9.0, and > 24 h for -30, -20, -10, 0 and 10 degrees C, respectively. With two layers of loose clothing (average thickness of 1 mm each) in a 5 km/h wind, STs are 4.0, 5.6, 8.6, 15.4, and > 24 h for -50, -40, -30, -20, and -10 degrees C. The predicted STS must be weighted against the extrapolative nature of the model. At present, it would be prudent to use the predictions in a relative sense, that is, to compare or rank-order predicted STs for various combinations of ambient conditions and clothing protection.

Adult↗
PubMed1993

Respiratory changes due to extreme cold in the Arctic environment.

Effects of acute exposure and acclimatisation to cold stress on respiratory functions were investigated in healthy tropical Indian men (n = 10). Initial baseline recordings were carried out at Delhi and thereafter serially thrice at the arctic region and once on return to Delhi. For comparison the respiratory functions were also evaluated on Russian migrants (RM; n = 7) and Russian natives (RN; n = 6). The respiratory functions were evaluated using standard methodology on a Vitalograph: In Indians, there was an initial decrease in lung vital capacity (VC), forced vital capacity (FVC), forced expiratory volume 1st s (FEV1), peak expiratory flow rate (PEFR) and maximum voluntary ventilation (MVV) on acute exposure to cold stress, followed by gradual recovery during acclimatisation for 4 weeks and a further significant improvement after 9 weeks of stay at the arctic region. On return to India all the parameters reached near baseline values except for MVV which remained slightly elevated. RM and RN showed similar respiratory functions at the beginning of acute cold exposure at the arctic zone. RN showed an improvement after 10 weeks of stay whereas RM did not show much change. The respiratory responses during acute cold exposure are similar to those of initial altitude responses.

Acclimatization↗
PubMed1996

Changes in cold tolerance due to a 14-day stay in the Canadian Arctic.

Response to cold exposure tests both locally and of the whole body were examined in subjects who stayed in the arctic (average maximum and minimum temperatures -11 and -21 degrees C respectively) for 14 days of skiing and sleeping in tents. These changes were compared to responses in subjects living working in Ottawa, Canada (average max. and min. temperatures -5 and -11 degrees C respectively). The tests were done before the stay in the Arctic (Pre), immediately after the return (Post 1) and approximately 32 days after the return (Post 2). For the whole-body cold exposure each subject, wearing only shorts and lying on a rope mesh cot, was exposed to an ambient temperature of 10 degrees C. There was no consistent response in the changes of metabolic or body temperature to this exposure in either of groups and, in addition, the changes over time were variable. Cold induced vasodilatation (CIVD) was determined by measuring temperature changes in the middle finger of the nondominant hand upon immersion in ice water for 30 min. CIVD was depressed after the Arctic exposure whilst during the Post 2 testing, although variable, did not return to the Pre values; the responses of the control group were similar. These results indicate that normal seasonal changes may be as important in adaptation as a stay in the Arctic. Caution is advised in the separation of seasonal effects when examining the changes in adaptation after exposure to a cold environment.

Acclimatization↗
PubMed1994

The effects of two different types of clothing on seasonal cold acclimation of thermophysiological responses.

The work described in this paper investigated the effects of two types of clothing, leaving the legs covered or uncovered, on seasonal cold acclimation in women. Experiments were carried out to observe the different thermal physiological responses between two groups of subjects, who dressed themselves in knee-length skirts or trousers during the daytime for 3 months from September to November. It was found that rectal temperatures and heart rates in the subjects wearing skirts were shifted to lower levels when the season gradually became colder. The results suggest that the clothing type worn in daily life may play a potential role in seasonal cold acclimation of thermal physiological responses in man.

Acclimatization↗