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 1,405 records · Page 78Linked to original sources
PubMed2006

Mercury (micro)biogeochemistry in polar environments.

The contamination of polar regions with mercury that is transported as inorganic mercury from lower latitudes has resulted in the accumulation of methylmercury in the food chain of polar environments, risking the health of humans and wildlife. This problem is likely to be particularly severe in coastal marine environments where active cycling occurs. Little is currently known about how mercury is methylated in polar environments. Relating observations on mercury deposition and transport through polar regions to knowledge of the microbiology of cold environments and considering the principles of mercury transformations as have been elucidated in temperate aquatic environments, we propose that in polar regions (1) variable pathways for mercury methylation may exist, (2) mercury bioavailability to microbial transformations may be enhanced, and (3) microbial niches within sea ice are sites where active microorganisms are localized in proximity to high concentrations of mercury. Thus, microbial transformations, and consequently mercury biogeochemistry, in the Arctic and Antarctic are both unique and common to these processes in lower latitudes, and understanding their dynamics is needed for the management of mercury-contaminated polar environments.

Antarctic Regions↗
PubMed1991

Mental distress during winter. An epidemiologic study of 7759 adults north of Arctic Circle.

The prevalence of mental distress in a general population north of the Arctic Circle at 69 degrees N was studied over 4 midwinter months. Within the framework of a health survey for coronary heart disease, 3 questions about depression, coping problems and insomnia were posed. They were answered by 7759 people randomly assigned to a survey date from November to February. The extreme lack of daylight in December and January taken into consideration, the prevalence of mental distress found, 14% in men and 19% in women, is remarkably low compared with previous epidemiologic research. Except for insomnia in women, which was most prevalent in December, no significant relationship between month of survey and any of the 3 symptoms were found. Thus, the findings cast some doubt upon the importance of daylight for mental distress in the general population.

Adaptation, Psychological↗
PubMed1994

Season and mental illness in an Arctic area of northern Finland.

The seasonal variation in mental disturbances was examined in 1251 reindeer herding males in an arctic area of northern Finland using the psychiatric section of the Cornell Medical Index questionnaire (CMI-MR). The mean age of subjects was 43 years. One third of them were full-time reindeer herders and 1/10 were Lapps. The prevalence of mental disorders (CMI-MR at least 5) was estimated at 14%, and it showed peaks in spring and autumn. The pattern was repeated for different varieties of illness, except for depression which showed a single cycle with the highest prevalence in the light season. The authors conclude that mental disorders in the arctic are most common in spring and autumn, and they question the common belief in mid-winter as the most common season for mental disorders.

Adolescent↗
PubMed1994

Temperature-metabolism relations in the cotton-top tamarin (Saguinus oedipus) model for ulcerative colitis.

Examination of temperature-metabolism relations found no significant differences between thermoregulation of temperature housed laboratory cotton-top tamarins (Saguinus oedipus) and wild tamarins in Colombia, S.A. The results indicate that tamarins do not acclimate to a temperature environment and are metabolically stressed at Ta less than 32 degrees C. This is consistent with an hypothesis of chronic metabolic stress as a factor in the etiology of cotton-top tamarin colitis, which is restricted to captive populations and not found in wild tamarins.

Acclimatization↗
PubMed1984

Modes of thermal protection in newborn muskoxen (Ovibos moschatus).

The muskoxen (Ovibos moschatus), a native of Greenland and the Canadian North West Territories, give birth in late April, and the newborn calves are known to tolerate an ambient temperature (Ta) of -35 degrees C. At birth the calves weigh about 8 kg, increasing in weight with 0.6 kg . day-1 for the first 30 days. With a deep body temperature (DBT) of 39.5 degrees C (range 37.7-41.3 degrees C) the newborn calves are consequently able to maintain a thermogradient of at least 70 degrees C between body core and the environment. The calves use primarily two modes of thermal protection: High metabolic heat production and prime fur insulation. Metabolic rate was about 3.5 W . kg-1 at thermoneutrality in calves aged from 8 h to 7 days. Lower critical temperature at this age was about -7 degrees C and a drop in Ta to -30 degrees C increased metabolism to about 5.3 W . kg-1. Upper critical temperature at age 4-7 days is as low as 20 degrees C, while it in calves aged only 18-24 h appears to be even lower. The calves possess great amounts of brown adipose tissue (BAT) at birth. Mitochondria from the BAT deposits were isolated and found to be in an extremely loose-coupled state with a great capacity for thermogenesis. Skeletal muscle contained very few mitochondria and is hardly employed in aerobic non-shivering thermogenesis. Calves shiver visibly while drying just after birth, but are normally not seen shivering thereafter. The conductance value for the dry pelt of newborn calves averaged 3.2 W . m-2 . 0 degrees C-1 (n = 4). Wetting of the pelt with ice-water at a Ta of 3 degrees C increased conductance to 8.8 W . m-2 . 0 degrees C-1. The conductance of the pelt was also influenced by wind, being 10 W . m-2 . C-1 at a wind-speed of 10 m . sec-1. The legs of the newborn calves are heavily furred and countercurrent circulation is not present, subcutaneous temperature just above the hooves being +29.8 degrees C at Ta of -24 degrees C as compared to 37.5 degrees C on the back. The newborn calves could cope with a Ta of -30 degrees C without apparent problems under experimental conditions, but they suffered hypothermia when exposed to a Ta of -33 degrees C in combination with wind of 10 m . sec-1.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1988

The development of homeothermy in common eider ducklings (Somateria mollissima).

Oxygen consumption (VO2), body temperature (TB) and electric muscle activity (EMG) were measured at varying ambient temperatures (TA) in common eider ducklings from the eggs pipped to 1 day after hatching. Eggs at pipping and ducklings still wet from hatching doubled their VO2 at TA = 2-4 degrees C compared with TA = 27 degrees C, but were unable to maintain constant TB. Increased EMG activity was recorded from ducklings 30 min after hatching. Artificially dried 1-h-old ducklings maintained normal TB (39.0-40.5) for at least 90 min at TA = 2 degrees C. Ducklings older than 24 h maintained homeothermy even when the pelt was artificially wetted. Oxygen consumption at thermoneutrality increased about 50% from hatching to 12 h of age. The specific thermal conductance of ducklings at different ages indicates that the youngest ducklings maintain homeothermy by having a cold periphery in addition to pelt insulation and increased VO2, while ducklings older than 12 h rely on pelt insulation and increased VO2 only.

Age Factors↗
PubMed1989

The formation of weathering products on the LEW 85320 ordinary chondrite: evidence from carbon and oxygen stable isotope compositions and implications for carbonates in SNC meteorites.

Isotopic analysis of nesquehonite recovered from the surface of the LEW 85320 H5 ordinary chondrite shows that the delta 13C and delta 18O values of the two generations of bicarbonate (Antarctic and Texas) are different: delta 13C = +7.9% and +4.2%; delta 18O = +17.9% and 12.1% respectively. Carbon isotopic compositions are consistent with equilibrium formation from atmospheric carbon dioxide at -2 +/- 4 degrees C (Antarctic) and +16 +/- 4 degrees C (Texas). Oxygen isotopic data imply that the water required for nesquehonite precipitation was derived from atmospheric water vapour or glacial meltwater which had locally exchanged with silicates, either in the meteorite or in underlying bedrock. Although carbonates with similar delta 13C values have been identified in the SNC meteorites EETA 79001 and Nakhla, petrographic and temperature constraints argue against their simply being terrestrial weathering products.

Antarctic Regions↗
PubMed2000

Investigations into an unknown organism on the martian meteorite Allan Hills 84001.

Examination of fracture surfaces near the fusion crust of the martian meteorite Allan Hills (ALH) 84001 have been conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and has revealed structures strongly resembling mycelium. These structures were compared with similar structures found in Antarctic cryptoendolithic communities. On morphology alone, we conclude that these features are not only terrestrial in origin but probably belong to a member of the Actinomycetales, which we consider was introduced during the Antarctic residency of this meteorite. If true, this is the first documented account of terrestrial microbial activity within a meteorite from the Antarctic blue ice fields. These structures, however, do not bear any resemblance to those postulated to be martian biota, although they are a probable source of the organic contaminants previously reported in this meteorite.

Actinomycetales↗
PubMed1966

Skin temperature, thermal comfort, sweating, clothing and activity of men sledging in Antarctica.

1. Three men were studied while dog-sledging 320 km in 12 days in Antarctica. Conventional Antarctic clothing (;sweaters and windproofs') was worn. Four hundred observations were made of medial thigh skin temperature, thermal comfort, sweating, clothing, activity and environmental conditions.2. Work occupied an average of 11.0 hr/day and sleep 7.5 hr. Estimated daily energy expenditure averaged 5100 kcal (range 2740-6660 kcal).3. Skin temperature fell on exposure to cold despite the clothing worn, but was not changed by the level of activity. Sweating, and thermal comfort, were directly related to both skin temperature and activity.4. Inside the tent, the modal value of skin temperature was 33 degrees C (range 27-36 degrees C) and the men were comfortable in 94% of observations.5. During the 9.2 hr/day spent outdoors the modal value of skin temperature was 27 degrees C (range 18-33 degrees C) and the men felt too cold (but did not shiver) in 11% (range 7-20%) of observations, suggesting that cold stress was not negligible. However, they also felt too hot in 20% of observations and were sweating in 23%.

Acclimatization↗
PubMed1966

Body temperature, shivering, blood pressure and heart rate during a standard cold stress in Australia and Antarctica.

1. Four men of European descent were exposed naked to an air temperature of 10 degrees C for 2 hr in Australia, and again after 24 weeks' residence at Mawson, Antarctica.2. Their ability to maintain rectal temperature during the test cold exposure significantly improved at Mawson. Shivering and cold diuresis did not change. The response of skin temperature did not change significantly except for a small increase in toe temperature. Bradycardia caused by the cold exposure was significantly greater at Mawson, but the rise in blood pressure did not change. Spontaneous fluctuations in rectal temperature that occurred during the cold exposure were intensified at Mawson.3. The results confirm those of a previous study at Mawson, and are attributed to general acclimatization to cold. It is suggested that tissue insulation increased as a result of enhanced vasoconstriction.

Acclimatization↗
PubMed1966

Cardiovascular and metabolic responses to noradrenaline in man, before and after acclimatization to cold in Antarctica.

1. Four men of European descent were infused with noradrenaline at rates of 0.038, 0.075, 0.150 and 0.300 mug/kg.min in Australia, and again after 29 weeks' residence at Mawson, Antarctica. A concurrent study of their responses to whole-body cooling showed that they acclimatized to cold in Antarctica.2. Blood pressure rose and heart rate fell in proportion to the dose of noradrenaline infused. The response was much less after than before acclimatization in three of the four subjects. Subjective effects of the drug decreased in proportion to the decrease in the pressor effect.3. Finger temperature fell in proportion to the dose infused, in three subjects. The response was unchanged or increased after acclimatization.4. Oxygen consumption was initially unaffected by noradrenaline, but after acclimatization it apparently increased in proportion to the dose infused. The increase in pulmonary ventilation during infusion was slightly greater after acclimatization.

Acclimatization↗
PubMed1968

Finger blood flow in Antarctica.

1. Finger blood flow was estimated, by strain-gauge plethysmography, before and during a 1 hr immersion in ice water, on twenty-five men throughout a year at Wilkes, Antarctica. A total of 121 satisfactory immersions were made.2. Blood flow before and during immersion decreased significantly in the colder months of the year, and the increase caused by cold-induced vasodilatation (CIVD) became less as the year progressed. The time of onset, blood flow at onset, and frequency of the cycles of CIVD showed no significant relation to the coldness of the weather (as measured by mean monthly wind chill) or the time in months. Comparisons of blood flow before and after five field trips (average duration 42 days), on which cold exposure was more severe than at Wilkes station, gave similar results.3. The results suggest that vasoconstrictor tone increased. This interpretation agrees with previous work on general acclimatization in Antarctica, but contrasts with work elsewhere on local acclimatization of the hands.

Acclimatization↗
PubMed1970

Urinary excretion of adrenal steroids, catecholamines and electrolytes in man, before and after acclimatization to cold in Antarctica.

1. Urine samples were collected from four men before and during test cold exposures in Melbourne, Australia, and Mawson, Antarctica. Changes in the response of body temperature to the test exposures showed that the men had acclimatized to cold at Mawson.2. Excretion rates of 17-hydroxycorticosteroids and 17-ketosteroids were significantly greater at Mawson than in Melbourne, in both the pre-exposure and exposure periods.3. Excretion rates of noradrenaline, adrenaline, sodium, potassium and creatinine did not differ significantly between Mawson and Melbourne, nor did urine flow rates.4. During the cold exposure significant increases occurred, to the same extent at Mawson as in Melbourne, in urine flow rate and in all measured urinary constituents except creatinine.

17-Hydroxycorticosteroids↗