PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Cold Temperature”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 775 records · Page 43Linked to original sources
PubMed1991

Structure and properties of luciferase from Photobacterium phosphoreum.

The nucleotide sequences of the luxA and luxB genes coding for the alpha and beta subunits, respectively, of luciferase from Photobacterium phosphoreum have been determined. The predicted amino acid sequences of the alpha and beta subunits were shown to be significantly different from other bacterial luciferases with 62 to 88% identity with the alpha subunits and 47 to 71% identity with the beta subunits of other species. Expression of the different luciferases appear to correlate with the number of modulator codons. Kinetic properties of P. phosphoreum luciferase were shown to reflect the bacterium's natural cold temperature habitat.

Amino Acid Sequence↗
PubMed1983

Behavioural responses to hypothalamic cooling and heating in the rat.

Rats with hypothalamic thermodes had their hypothalamus cooled or warmed for short sessions. In a first series of experiments, rats could bar-press to obtain fanning with cool air. Cooling the hypothalamus did not suppress or inhibit this behaviour although rectal temperature was markedly increased. In a second series of experiments, bar-pressing would warm the water flowing in the thermode. The rats thus self suppressed the cooling of their hypothalamus. This behaviour was absent at 10 degrees C ambient temperature, and increased with increasing ambient temperature up to 35 degrees C. The result of this behaviour was a small hyperthermia in warm and hot environment compared to control when the rats could not self-suppress the cooling of hypothalamus. The results of both experiments suggest that no conscious direct sensation is aroused by hypothalamic cooling. Hypothalamic heating increased the rat's bar-pressing for cool air and decreased the rat's rectal temperature. When pressure on the lever would suppress a warm hypothalamic stimulus rats self-cooled their hypothalamus, especially in warm environments. Such behaviour resulted in an increased somatic hyperthermia due to the warm environment and hypothalamic cooling. These results are compatible with the hypothesis of a direct conscious sensation from a warm hypothalamus.

Animals↗
PubMed1984

Lack of correlation between [3H]ouabain binding and Na-K ATPase inhibition in rat aorta.

The binding of [3H]ouabain to intact strips of rat aorta was compared with the ability of ouabain to inhibit the uptake of 86Rb by the same preparation. When a cold temperature wash was used to process tissues after binding of [3H]ouabain, a class of relatively high affinity binding sites was found (KD = 1.2 X 10(-7) M). Binding was saturable and sensitive to both ATP depletion and elevated potassium. Elevation of cytoplasmic Ca2+ levels by phenylephrine or c-AMP levels by theophylline and terbutaline had no influence on [3H]ouabain binding. Ouabain inhibition of 86Rb uptake progressed to 60% of the total 86Rb uptake at 2 X 10(-3) from a threshold of about 10(-5) M. Half-maximal inhibition by ouabain occurred at a concentration of 10(-4) M. The disparity between [3H]ouabain binding and inhibition of 86Rb uptake indicates that the high affinity binding site in the rat does not contribute to inhibition of Na-K ATPase function.

Animals↗
PubMed1985

Pathophysiology and pathogenesis of acute gastric mucosal lesions after hypothermic restraint stress in rats.

The interrelationships of core body temperature, blood viscosity, gastric mucosal blood flow, surface pH of the corpus mucosa, and acute gastric mucosal lesions in rats after up to 3 h of hypothermic stress were investigated. Three groups of rats were studied: (a) control rats restrained at room temperature, (b) conscious rats under restraint and varying degrees of hypothermia, and (c) anesthetized rats under hypothermia. Under hypothermic stress both restrained and anesthetized rats manifested a sharp decline in core temperature, a marked increase in blood viscosity with a mirror-image decrease in gastric mucosal blood flow, a significant decline in gastric mucosal surface pH, and similar frequencies and severities of acute gastric mucosal lesions. In the control group, neither mucosal lesions nor changes in physiologic measurements were observed, except for a decline in mucosal surface pH. An increase in blood viscosity identical to that in rats subjected to hypothermia was observed in vitro when blood temperature was lowered in the viscometer. These findings indicate that hypothermia but not restraint led to an increase in blood viscosity, which in turn resulted in a decrease in mucosal blood flow and the development of gastric mucosal lesions. Also, hyperacidity was found to be a permissive factor in the pathogenesis of mucosal lesions.

Animals↗
PubMed1990

Earth analogs for Martian life. Microbes in evaporites, a new model system for life on Mars.

The prospect of life on Mars today is daunting. Especially problematic for a potential life form is a lack of water, particularly in a liquid state; extremely cold temperatures; ultraviolet and ionizing radiation; and soil oxidants. Yet, "oases" where life might persist have been suggested to occur in rocks (in analogy with endolithic microorganisms described from deserts around the world), in polar ice caps (in analogy with snow and ice algae) and in possible volcanic regions (in analogy with chemoautotrophs living in deep sea hydrothermal vents); all are critically examined. Microorganisms are known to be able to survive in salt crystals, and recently it has been shown that organisms can metabolize while encrusted in evaporites. Because evaporites are thought to occur on Mars and can attenuate light in the UV range while being far more transparent to radiation useful for photosynthesis (400-700 nm), and because of the properties of these "endoevaporitic" organisms, I propose that such communities provide a new model system for studying potential life on Mars. On the basis of this model, I suggest possibilities for site selection for future exobiological experiments on Mars.

Atmosphere↗
PubMed1990

Effect of environmental factors on film badge dosimetry readings of dental office personnel.

Inadvertent exposure of film badges to environmental factors may produce fogging of the film and yield higher radiation exposure readings. Common environmental factors in everyday living were studied to assess their effect on film badge readings. Only heat appeared to have any significant effect, because moisture, chemicals, pressure, cold temperature, and non-work-related electromagnetic radiation did not substantially alter film badge readings. Therefore not all unexplained high readings on personnel film badge reports may be due to heat or other common environmental factors evaluated in this study.

Automobiles↗