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PubMed1991

The bioclimate in temperate and northern cities.

Climate is a basic component of the human environment. Developments in building design and indoor climate control have contributed greatly to improving human health and comfort. By contrast, the possibilities for improving urban climatic conditions by deliberate planning have been poorly exploited. The structure and processes of the urban atmosphere in extratropical regions are briefly described. The impact of certain selected urban climates on human health is summarized. The need for relevant bioclimatological "design tools" for applications in urban planning is stressed, followed by a brief review of some recent work on human thermal comfort. It is argued that the modification of present day comfort criteria to reflect human adaptation to climate may be important for further improvements of indoor climate, as well as for deducing the emissions of air pollutants and greenhouse gases.

Acclimatization↗
PubMed1997

Psychrophilic enzymes: molecular basis of cold adaptation.

Psychrophilic organisms have successfully colonized polar and alpine regions and are able to grow efficiently at sub-zero temperatures. At the enzymatic level, such organisms have to cope with the reduction of chemical reaction rates induced by low temperatures in order to maintain adequate metabolic fluxes. Thermal compensation in cold-adapted enzymes is reached through improved turnover number and catalytic efficiency. This optimization of the catalytic parameters can originate from a highly flexible structure which provides enhanced abilities to undergo conformational changes during catalysis. Thermal instability of cold-adapted enzymes is therefore regarded as a consequence of their conformational flexibility. A survey of the psychrophilic enzymes studied so far reveals only minor alterations of the primary structure when compared to mesophilic or thermophilic homologues. However, all known structural factors and weak interactions involved in protein stability are either reduced in number or modified in order to increase their flexibility.

Adaptation, Biological↗
PubMed2001

Report of the consensus conference on diagnostic criteria of ALI/ARDS at high altitudes in Western China.

China is a mountainous country. The Qing-Zang plateau, Yun-Gui plateau, and Yellow Land plateau, which are known as the world's ridge, are located in the west of China. The highland area over 3,000 m in height occupies one-sixth of the land area of China and half the highland area of the world. About 60-80 million people live in the regions where the elevation ranges from 1,500 m to 4,000 m. In the latter half of the last century, the influence of complex environmental factors on the human body, such as low oxygen pressure, cold climate, strong radiation, high wind speed, and super-evaporation, were studied in an extensive and profound way and formed an important field of altitude medicine. For a long time, many researchers have carried out investigations related to the systemic inflammatory response syndrome (SIRS), acute respiratory distress syndrome (ARDS), and multiple organ dysfunction syndrome (MODS) and its pathophysiological mechanism initiated by cytokines and mediators, regarding which many problems are still unclear. However, systematic research into the mechanism from SIRS to ARDS to MODS in the highlands remains blank. The diagnostic criteria of ALI/ARDS in the highlands are quite different from that in the plain, and thus was a central topic for discussion at this meeting.

Adaptation, Physiological↗
PubMed2002

Seasonal variation of alterations in exercise-induced body composition in obese Japanese women.

Although many investigations have been conducted to determine the effects of exercise and/or diet prescription, seasonal variations in weight loss have not been thoroughly investigated in Japan. The present investigation was undertaken to determine seasonal variations in body composition and anthropometric characteristics during a weight-loss program. One hundred and twenty-seven women [mean (SD) age 44.3 (11.7) years] participated in this study. The subjects were categorized into four groups based on the season in which the weight-loss program was begun: subjects who joined our exercise program in winter (group WE), subjects who joined in summer (group SE), and two control groups, one for winter and one for summer (group WC and group SC, respectively). The subjects of groups WE and SE completed a 3-month exercise and food-restriction program. Analyses of covariance revealed that the subjects of group WE seemed to have attained more desirable changes. This group showed a decrease in body mass (-1.9 (1.5) kg) and percent body fat (-4.6 (4.8)%), while an increase in fat-free mass (1.6 (3.2) kg) during the experimental period. Our data suggest that the better season for desirable weight loss in Japan is winter, compared to summer. These alterations may be attributable, at least in part, to the fact that Japanese people are generally acclimatized to a cold climate in this season. The mechanisms involved in our speculation have not been well validated, but it seems clear that a significant difference in dietary intake might have affected the results of this study.

Adult↗
PubMed2003

Effect of air temperature on forecasting the start of the Betula pollen season at two contrasting sites in the south of Europe (1995-2001).

In order to survive periods of adverse cold climatic conditions, plant requirements are satisfied by means of physiological adaptations to prevent cells from freezing. Thus, the growth of woody plants in temperate regions slows down and they enter into a physiological state called dormancy. In order to identify the chilling and heat requirements to overcome the dormancy period of Betula in the south of Europe, a comparative study was carried out with aerobiological pollen data of a 7-year (1995-2001) period in Vigo (Spain) and Perugia (Italy). To satisfy chilling requirements, base temperatures of 7 degrees C and 5.75 degrees C showed a lower standard variation coefficient: 3.94% and 2.36% in Perugia and Vigo respectively. In the case of heat accumulation, the sum of mean temperatures in Perugia and the sum of maximum temperatures in Vigo were the parameters that showed a minor coefficient of variation (11.13% and 14.51% respectively).

Adaptation, Physiological↗
PubMed2006

Yeasts in high Arctic glaciers: the discovery of a new habitat for eukaryotic microorganisms.

Recently a new habitat for microbial life has been discovered at the base of polythermal glaciers. In ice from these subglacial environments so far only non-photosynthetic bacterial communities were discovered, but no eukaryotic microorganisms. We found high numbers of yeast cells, amounting to a maximum of 4,000 CFU ml(-1) of melt ice, in four different high Arctic glaciers. Twenty-two distinct species were isolated, including two new yeast species. Basidiomycetes predominated, among which Cryptococcus liquefaciens was the dominant species (ca. 90% of total). Other frequently occurring species were Cryptococcus albidus, Cryptococcus magnus, Cryptococcus saitoi and Rhodotorula mucilaginosa. The dominant yeast species were psychrotolerant, halotolerant, freeze-thaw resistant, unable to form mycelium, relatively small-sized and able to utilize a wide range of carbon and nitrogen sources. This is the first report on the presence of yeast populations in subglacial ice.

Arctic Regions↗
PubMed1979

Cold-induced diminution of paradoxical sleep in man.

Prolonged exposure to cold produced a chronic diminution in PS (PS-hyposomnia) primarily in the tonic component of PS. No significant change occurred in the REM (phasic or obligatory) component of PS. An inverse correlation was found in the activity of the pituitary-adrenal cortical system and the level of PS. The classical rebound phenomenon that occurs after PS deprivation was not observed in this study and it is suggested that the rebound effect characteristic of PS deprivation is related not to total PS but to its phasic (obligatory) component.

Adult↗
PubMed1983

Circannual changes in immune function.

Adrenocortical activity varies on a circannual basis with increased secretion in the winter and decreased secretion in the summer. One consequence of this variation is a circannual pattern in immune function. Adrenal corticosteroids, especially glucocorticoids, depress cellular immune function and seem to be more effective against T-suppressor cells. Thus, when adrenocortical activity is elevated, T-cell activity is depressed and B-cell activity is elevated. To the extent that T-cell "surveillance" is depressed in winter, there should be increased lymphoproliferative cancer risk during winter and in regions characterized by cold climates. This article presents data which suggest: (1) a winter, adrenal-corticoid induced, depression of T-cell function which is accompanied by elevated B-cell function; (2) elevated serum immunoglobulin levels in the winter; and (3) an inverse relationship between ambient temperature and serum immunoglobulin levels. The circannual pattern in immune function could help explain increased lymphoproliferative cancer risk, as a side effect of immunosuppression therapy during organ transplants, and as a function of latitude.

Adrenal Cortex Hormones↗
PubMed1991

Susceptibility of captive wildfowl to avian tuberculosis: the importance of genetic and environmental factors.

This study reports the findings of an epidemiological survey of death due to avian tuberculosis in the captive collection of wildfowl at The Wildfowl and Wetlands Trust Centre, Slimbridge, Gloucestershire. Both genetic and environmental factors have been shown to affect the incidence of, and the birds' susceptibility to, the disease. Seasonal body condition was related to the occurrence of death due to the disease in both males and females. Birds from either hot or cold climates appeared to have a higher incidence than those from temperate climates. What the birds ate did not affect incidence but the method they used for obtaining their food did. Higher susceptibility was found in those species evolved for marine or arboreal habitats. Anomalies in susceptibility which suggest a higher level of genetic immunity in some groups have also been found. Reasons are put forward to explain these findings.

Animals↗
PubMed1988

Lactate dehydrogenases in Antarctic and temperate fish species.

1. The kinetics of lactate dehydrogenase (both forward and back reaction) in cardiac and skeletal muscle of an Antarctic teleost have been compared with a temperate teleost of comparable morphology and ecology. 2. In both species the forward reaction (pyruvate to lactate) is maximally activated at 2.5-4 mM pyruvate and inhibited above this level. 3. The Michaelis constant (Km) for pyruvate is not significantly different between muscle types or between species when measured at their normal environmental temperature. 4. Km for pyruvate varies with temperature in a positive direction. 5. The back reaction (lactate to pyruvate) is maximally activated by 12-16 mM lactate but only in skeletal muscle of the antarctic species is there inhibition above this level. 6. The Km for lactate is significantly (P less than 0.05) lower in the Antarctic fish cardiac muscle. 7. While the two species are morphologically and ecologically similar, differences at the biochemical level are discussed with respect to environmental temperature range and conservation of enzymic characteristics.

Animals↗
PubMed1994

Uric acid and glutathione levels during short-term whole body cold exposure.

Ten healthy subjects who swim regularly in ice-cold water during the winter (winter swimming), were evaluated before and after this short-term whole body exposure. A drastic decrease in plasma uric acid concentration was observed during and following the exposure to the cold stimulus. We hypothesize that the uric acid decrease can be caused by its consumption after formation of oxygen radicals. In addition, the erythrocytic level of oxidized glutathione and the ratio of oxidized glutathione/total glutathione also increased following cold exposure, which supports this hypothesis. Furthermore, the baseline concentration of reduced glutathione was increased and the concentration of oxidized glutathione was decreased in the erythrocytes of winter swimmers as compared to those of nonwinter swimmers. This can be viewed as an adaptation to repeated oxidative stress, and is postulated as mechanism for body hardening. Hardening is the exposure to a natural, e.g., thermal stimulus, resulting in an increased tolerance to stress, e.g., diseases. Exposure to repeated intensive short-term cold stimuli is often applied in hydrotherapy, which is used in physical medicine for hardening.

Acclimatization↗
PubMed2006

The relationship of plasma indicators of lipid metabolism and muscle damage to overnight temperature in winter-acclimatized small birds.

Plasma glycerol and triglyceride levels and creatine kinase (CK) activity may increase during long-distance flights in migratory birds, but plasma profiles of these metabolites have not previously been reported for small birds during thermoregulation in cold climates. We measured early morning levels of plasma glycerol, triglycerides and CK activity in four species of small birds overwintering in South Dakota, Junco hyemalis, Spizella arborea, Passer domesticus, and Carduelis tristis. We hypothesized that metabolite levels and CK activity might vary with overnight temperature (measured as the temperature just prior to dawn), with higher levels during colder temperatures which require elevated thermogenesis. Triglyceride and glycerol levels were not significantly related to temperature for any of the four species. Triglyceride levels were significantly positively associated with time since sunrise in J. hyemalis and C. tristis, and the time-temperature interaction was significant for S. arborea, suggesting rapid replacement of fat stores. Plasma glycerol levels were also significantly positively related to time since sunrise in J. hyemalis and C. tristis, but not in other species. Plasma CK activity showed a significant negative relationship to overnight temperature only for S. arborea. These results suggest that triglycerides do not comprise a major contribution to lipid supply during intense shivering in small birds. Similarly, intense shivering does not generally appear to result in muscle damage in small birds.

Acclimatization↗
PubMed2004

The ice worm, Mesenchytraeus solifugus, elevates adenylate levels at low physiological temperature.

The ice worm, Mesenchytraeus solifugus, is among a few metazoan species that survive exclusively in glacier ice/snow. In this study, we demonstrate that ice worm adenylate levels [i.e. adenosine 5'-triphosphate (ATP), ADP and AMP] are maintained at levels well above their mesophilic counterparts, and that their response to temperature change is distinctly opposite, namely, ice worms increase energy levels as temperatures fall. Initially, this response is characterized by a sharp spike in [ATP] and the adenylate energy charge (even at sub-zero temperatures), which is followed by corresponding increases in [ADP] and [AMP] within a few days. These results suggest that ice worms have evolved a compensatory mechanism by which gains in adenylate nucleotides off-set, at least in part, the inherent lethargy and death usually associated with cold temperature.

Acclimatization↗
PubMed2004

Seasonal and daily changes in the capacity for nonshivering thermogenesis in the golden hamsters housed under semi-natural conditions.

Nonshivering thermogenesis (NST) is a main source of heat for many small mammals. It undergoes seasonal changes, being the highest in winter and the lowest in summer. Such acclimatization can ensure winter survival for species living in moderate or cold climates. Nevertheless, not only seasonal, but also daily changes in the capacity for NST seem to be of great importance. In this study, the effects of season and time of day on the temperature of brown adipose tissue (T(BAT)), preferred ambient temperature (PT(a)) and activity after noradrenaline (NA) injections in golden hamsters (Mesocricetus auratus) housed under semi-natural conditions were investigated. Animals were kept in outdoor enclosures and experienced natural changes in both, photoperiod and ambient temperature (T(a)). NA-induced hyperthermia was the largest during autumn (mean increase in T(BAT) by 0.74+/-0.04 degrees C), while during summer increase in T(BAT) was similar to that recorded in control (saline-injected) animals (0.16+/-0.05 degrees C and 0.24+/-0.04 degrees C, respectively). In spring hyperthermia was intermediary (0.57+/-0.05 degrees C). Daily variations in the response to NA depended on the season. In summer, the largest increase in T(BAT) (0.45+/-0.1 degrees C) was recorded during the first part of the day, while in autumn-in the middle of the day and night (1.1+/-0.1 degrees C and 0.9+/-0.1 degrees C, respectively). In spring, all NA injections induced large increase in T(BAT) except for the injection in the middle of the night. The largest decrease in PT(a) after NA administration was recorded in autumn (mean decrease by 1.5+/-0.3 degrees C). Both, seasonal and daily changes in the capacity for NST reflect different demands for heat dependently on the time of the year and time of the day. It can be concluded that although long history of breeding in captivity, golden hamsters preserved ability to survive in natural environment.

Acclimatization↗
PubMed2004

Cold hardiness abilities vary with the size of the land snail Cornu aspersum.

The land snail Cornu aspersum (syn. Helix aspersa) living in Brittany (France) can be considered partially freezing tolerant as it possesses a low ability to supercool and a limited capacity to bear freezing of its body tissues. The absence of a marked cold hardiness strategy permits the emphasis of the role of parameters such as individual size or water mass (W(M)) contained by the organism. Adult snails (shell diameter 30-32 mm) had a supercooling ability, about 1-1.5 degrees C lower than that of immatures (shell diameter 12-20 mm) and survived longer to an exposure to -5 degrees C, with an Lt(50) comprised between 6.0 and 9.8 h against 2.6 to 4.2 h for immature snails. This better ability to bear freezing was explained by the faster dynamic of body ice formation observed in small individuals, which attained ice lethal quantity more rapidly. At the species level, large snails will then tend to be more tolerant to freezing and small ones to be freezing avoidant, a statement also observable at the phylum level.

Acclimatization↗
PubMed2006

Hibernation proteins: preparing for life in the freezer.

Hibernation is an extreme response to a seasonal environment, yet we know almost nothing about how it is timed or how vital cellular functions are sustained in the face of plummeting body temperature. In this issue of Cell, kondo et al. (2006) identify a liver-derived protein complex as an essential coordinator of this adaptation to the depredations of winter.

Animals↗