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At least 163 records · Page 9Linked to original sources
PubMed1992

ATP dependence of Na(+)-K+ pump of cold-sensitive and cold-tolerant mammalian red blood cells.

1. The ATP concentration of intact, cold-tolerant (ground squirrel) red cells and cold-sensitive (guinea-pig and human) red cells was monitored by use of the firefly tail, luciferin-luciferase assay. ATP kinetics of the pump in intact red blood cells was investigated by altering cell [ATP] by progressive depletion of ATP in the presence of 2-deoxy-D-glucose and then by measurement of ouabain-sensitive K+ influx at each level of [ATP] at various temperatures between 37 and 5 degrees C. Na(+)-K(+)-ATPase activity of broken membranes was also determined in parallel experiments using ouabain-sensitive release of 32P from [gamma-32P]ATP as a measure of activity. 2. Without depletion, there is no immediate decrease in [ATP] of intact cold-sensitive cells at low temperature (5 degrees C) at times when there are marked differences in the activities of the Na(+)-K+ pump of cold-tolerant and cold-sensitive cells. 3. At 37 degrees C Na(+)-K(+)-ATPase of all three species exhibited two components of ATP dependence at 37 degrees C, one with high velocity, low affinity, the other with low velocity, high affinity. Affinities of both components rose with cooling. 4. A similar, two component pattern was observed in intact guinea-pig and human red cells at 37 degrees C, except that the segment corresponding to the high affinity component had an apparent Km (Michaelis-Menten constant) 3- to 4-fold higher than that of the broken membrane preparation. 5. Cooling intact guinea-pig and human red cells decreased the apparent affinity of the high velocity, low affinity component for ATP, so that at 20 degrees C the value of Km approached or exceeded the levels of physiological ATP concentration. Below 20 degrees C only one component with values corresponding to that of the low velocity, high affinity component could be observed. 6. In intact ground squirrel cells only the low affinity, high velocity component was apparent between 37 and 5 degrees C. Its affinity for ATP rose with cooling between 37 and 5 degrees C.

Adenosine Triphosphate↗
PubMed1996

Cold shock and cold acclimation proteins in the psychrotrophic bacterium Arthrobacter globiformis SI55.

The psychrotrophic bacterium Arthrobacter globiformis SI55 was grown at 4 and 25 degrees C, and the cell protein contents were analyzed by two-dimensional electrophoresis. Cells subjected to cold shocks of increasing magnitude were also analyzed. Correspondence analysis of protein appearance distinguished four groups of physiological significance. Group I contained cold shock proteins (Csps) overexpressed only after a large temperature downshift. Group II contained Csps with optimal expression after mild shocks. Group III contained proteins overexpressed after all cold shocks. These last proteins were also overexpressed in cells growing at 4 degrees C and were considered to be early cold acclimation proteins (Caps). Group IV contained proteins which were present at high concentrations only in 4 degrees C steady-state cells and appeared to be late Caps. A portion of a gene very similar to the Escherichia coli cspA gene (encoding protein CS7.4) was identified. A synthetic peptide was used to produce an antibody which detected a CS7.4-like protein (A9) by immunoblotting two-dimensional electrophoresis gels of A. globiformis SI55 total proteins. Unlike mesophilic microorganisms, this CS7.4-like protein was still produced during prolonged growth at low temperature, and it might have a particular adaptive function needed for balanced growth under harsh conditions. However, A9 was induced at high temperature by chloramphenicol, suggesting that CS7.4-like proteins have a more general role than their sole implication in cold acclimation processes.

Acclimatization↗
PubMed1980

Parallel regression of cold-induced changes in ultrastructure, composition, and properties of brown adipose tissue mitochondria during recovery of rats from acclimation to cold.

When cold-acclimated rats are returned to a thermoneutral environment (28 degrees C) after 5 weeks at 4 degrees C, the size of the enlarged interscapular brown adipose tissue decreases during the 1st week. The altered composition of the mitochondria, however, reverts to normal during deacclimation more rapidly than the size of the tissue: a marked decrease in binding of purine nucleotides occurs by 3 days and a decrease in the proportion of polypeptides of molecular weight 25 000-35 000 occurs by 1 day. The very rapid decrease in the polypeptides, compared with the slower decrease in binding of purine nucleotides, known to be to a 32 000 polypeptide, suggests an initial conversion of masked binding sites to another form. Mitochondria isolated from cold-acclimated rats are larger than those of warm-acclimated rats, a difference which appears slowly during acclimation to cold, requiring 7-14 days for full development; during deacclimation the increase in size disappears by 7 days. The ultrastructure of mitochondria isolated from cold-acclimated rats shows inmerices arranged in numerous, narrow, interconnecting parallel sheets in contrast to the sparser broad tubes and bands in mitochondria isolated from warm-acclimated rats. This difference in ultrastructure develops in a biphasic manner during acclimation to cold: an initial appearance (1-12 h) of the parallel arrangement, associated with a transient increase in size, is no longer apparent at 1-3 days and reappears only after 7-14 days. During deacclimation the reversal to the tubular form requires approximately 7 days. During deacclimation the changes in brown adipose tissue mitochondrial composition, structure, size, and properties and in tissue size appear to occur independently.

Acclimatization↗
PubMed1983

Effects of desmethylimipramine and normetanephrine on calorigenic response and plasma noradrenaline concentration in warm- and in cold-acclimated rats exposed to cold.

Oxygen consumption and plasma noradrenaline concentration were increased significantly above resting levels in warm-acclimated and in cold-acclimated rats exposed to an ambient temperature of 4 degrees C. Administration of normetanephrine (1 microgram X min-1 X g body weight-0.74), but not of desmethylimipramine (1 mg X kg-1), resulted in higher resting plasma noradrenaline levels at 24 degrees C and increased the length of time required for the oxygen consumption to return to resting levels after cold exposure in both acclimation groups. These observations support a significant role of extraneuronal uptake in noradrenaline inactivation under normal physiological conditions. Calorigenic responses to cold exposure were not affected at all by treatment of animals with desmethylimipramine and (or) normetanephrine in either warm-acclimated or cold-acclimated rats, although an enhancing effect of these uptake inhibitors on plasma noradrenaline was evident in cold-acclimated rats. It is suggested that a peripheral-central thermoregulatory mechanism adjusts activation of thermogenic effectors so as to maintain a steady calorigenic response, appropriate to the thermal demand of the environment, to compensate for changes in perineuronal concentration of noradrenaline in sympathetic thermoeffectors owing to blockade of extraneuronal uptake.

Acclimatization↗
PubMed1975

Nonshivering thermogenesis and cold resistance in rats under severe cold conditions.

Following either chronic exposure to 6 degrees C, or outdoor winter exposure, or chronic treatment with tyramine rats were exposed to -40 degrees C and their oxygen consumption and colonic temperature monitored. Fall in body temperature with time of exposure followed a sigmoid curve which had an inflection point around 32.9 degrees C. Both the time required for body temperature to reach this point and hypothermic resistance defined as the total O2 consumed up to the inflection time were useful indices of resistance to severe cold; Three days before the cold tests, capacity for norepinephrine-induced nonshivering thermogenesis was measured in all animals by examination of their metabolic response to tyraminemthe magnitude of response to tyramine correlated well with hypothermic resistance only for those rats chroncally treated with tyramine. It is concluded that it is impossible to predict with any reasonable degree of confidence the cold resistance of a rat from its tyramine response. In cold-acclimated rats, factors in addition to norepinephrine sensitivity are significantly involved in cold resistance and deserve further studies.

Acclimatization↗
PubMed1981

Cold-specific feeding response of rats to cold exposure and energy density of body weight change.

The increased food intake of rats exposed to cold is the result of increased intake due to cold (cold-specific compartment; A) and decreased intake due to simultaneously decreased body weight (weight-specific compartment; B). The two compartments are evaluated at 5, 13, and 17 degrees C. B is evaluated as the food intake of theoretical, isogravimetric control (identical to cold-exposed rats with respect to body weight and rate of change of body weight and identical to nonexposed rats in all other respects) that takes into account both the change in energy expenditure due to decreased body weight and the energy yield from tissue catabolism represented by change of body weight. A is the observed food intake minus B. A theoretical heat-flow model, in which expected changes in heat flow during cold exposure drive food intake to maintain or restore preexposure body weight status, corroborated the partition derived from experimental data. However, both the experimental results and the heat-flow model imply that the energy density of body weight change is negatively correlated with rate of body weight change. The energy density of weight change is high with high rates of weight loss and low with high rats of weight gain.

Animals↗
PubMed2006

Change in Ucp1 mRNA expression following long-term cold exposure under normal or high-fat diet regimes in the cold-intolerant mammal, Suncus murinus.

The house musk shrew (Suncus murinus), or suncus, is a unique experimental mammal that is cold intolerant. However, even basic knowledge of brown adipose tissue (BAT), which is important for non-shivering thermogenesis (NST), is minimal. Therefore, we exposed suncus for 18 days to mild cold temperatures (8-14 degrees C) and/or a high-fat diet, which are factors that increase NST, and measured two mRNAs that are critical for NST in BAT, uncoupling protein 1 (Ucp1) and type II 5'-deiodinase (D2). Neither mild cold exposure nor a high-fat diet alone induced up-regulation of the mRNAs. However, combinations of cold exposure and high-fat diet significantly increased both mRNAs. Therefore, cold intolerance in suncus may be partly caused by dietary components.

Adaptation, Physiological↗
PubMed2006

Enhanced cold and desiccation tolerance in diapausing adults of Culex pipiens, and a role for Hsp70 in response to cold shock but not as a component of the diapause program.

Culex pipiens L. reared under diapause-inducing conditions (short daylength; 18 degrees C) were more cold tolerant and desiccation resistant than their nondiapausing counterparts (long daylength; 18 degrees C). Upon cold exposure (-5 degrees C), diapausing mosquitoes reared at 18 degrees C survived nearly twice as long as nondiapausing mosquitoes reared at 18 degrees C and 10 times longer than nondiapausing mosquitoes reared at 25 degrees C. Thus, rearing temperature provided partial protection against low temperature injury in nondiapausing mosquitoes, but maximum resistance to cold was attained by the diapause state. In this species, the supercooling point is not a good indicator of cold tolerance. Both diapausing and nondiapausing females had supercooling points of approximately -16 degrees C, but diapausing as well as nondiapausing females died at temperatures well above the supercooling point, suggesting that low temperature mortality was due to indirect chilling injury. Diapause also conferred greater resistance to desiccation (1.6-2-fold increase in survival) compared with the nondiapause state. The gene encoding a 70-kDa heat shock protein, hsp70, was not up-regulated (i.e., more highly expressed) as a part of the diapause program, nor was it up-regulated by desiccation stress, but it was up-regulated during recovery from cold shock. Cx. pipiens thus differs from a number of other diapausing insect species that are known to developmentally up-regulate hsp70 during diapause.

Amino Acid Sequence↗
PubMed2001

Metabolic habituation following repeated resting cold-water immersion is not apparent during low-intensity cold-water exercise.

This project examined the effects of repeated, resting cold-water immersion on metabolic heat production and core temperature defence during subsequent rest and exercising immersions. Seven males undertook 15 days of cold-water adaptation, immersed to the fourth intercostal space, with cold-water stress tests (CWST) on days 1, 8 and 15 (18.1 SD 0.1 degree C: 60 min seated, followed by 30 min cycling (1 W.kg-1)), and 90-min resting immersions (18.4 SD 0.4 degree C) on each of the intervening days. Adaptation elicited an habituated thermogenic response during the rest phase of CWST3 beyond 20 min, compared to CWST1 (P < 0.05), with oxygen consumption averaging 11.15 (+/- 0.25) ml.kg-1.min-1 and 8.61 (+/- 0.90) ml.kg-1.min-1 by 50 min, for CWST1 and CWST3, respectively. During exercise, this metabolic blunting was only apparent over the first 10-min period (60-70 min). No significant differences were observed during either the rest or exercise phases of the CWSTs for oesophageal temperature (Tes). While repeated cold-water exposures produced an habituated-thermogenic response, for an equivalent drop in Tes during rest, neither this response, nor an elevated thermogenesis, were apparent during subsequent cold-water exercise.

Adaptation, Physiological↗
PubMed2003

[A cold agglutinin disease, difficult to distinguish from paroxysmal cold hemoglobinuria].

A 58-year-old male started passing dark brown colored urine in January 2002. An annual medical examination in the same month revealed a mild anemia and an increased serum LDH level. Because of the instability of the data of his peripheral red cell count and hemoglobin concentration as measuring with a blood cell auto-analyzer, and also the hemolytic findings in a test tube at room temperature (25 degrees C), he was referred to our hospital. Laboratory data revealed Hb 11.2 g/dl, reticulocytes 73.1% (233,000/microliter), indirect-bilirubin 2.8 mg/dl, LDH 757 U/l, and hemosiderinuria, suggesting some intravascular hemolysis. The cold agglutinin titer was > 1,024, direct and indirect Coombs tests were both positive, and the Donath-Landsteiner antibody (D-L antibody) was initially assessed as false positive because of a high titer of cold agglutinin. He was finally diagnosed as having a cold agglutinin disease (CAD) with anti-I autoantibody. Serologic tests for syphilis and mycoplasma, and various virus tests were all negatives. After avoiding cold exposure, his symptoms, including hemoglobinuria, disappeared. However, during 9 months follow-up, he still showed a high titer of cold agglutinin. This case suggests that CAD should be considered when peripheral blood cell count data are unstable as assessed by a blood cell auto-analyzer.

Agglutinins↗
PubMed2006

[Survival in cold water. Physiological consequences of accidental immersion in cold water].

This survey addresses the immediate physiological reactions to immersion in cold water: cold shock response, diving reflex, cardiac arrhythmias and hypothermia. Cold shock response is the initial sympathetic reaction to immersion in cold water. The diving reflex is elicited by submersion of the face. Afferent and efferent nerves are the trigeminal and vagal nerves. Cardiac arrhythmias occur immediately after immersion. If the immersion persists, hypothermia becomes an issue. Hypothermia is delayed by habituation to immersion in cold water as well as insulating garments, subcutaneous fat and a large lean body mass.

Accidents↗
PubMed1989

Detection of cold hemagglutination in a blood cardioplegia unit before systemic cooling of a patient with unsuspected cold agglutinin disease.

A case is described in which hemagglutination occurred intraoperatively in cold blood flushed through the blood cardioplegia delivery system from a patient with unsuspected cold agglutinin disease. On initiating cardiopulmonary bypass and then selectively cooling the perfusate in the blood cardioplegia delivery system before inducing systemic cooling, it is possible to check for cold agglutination. Routine use of this technique may be worthwhile to detect cold agglutination in vitro before systemic cooling is begun in the rare patient with unsuspected cold agglutinins.

Aged↗
PubMed1992

Long-term preservation of canine pancreas by a new simple cold storage method using perfluorochemical--the two-layer cold storage method (Euro-Collins' solution/perfluorochemical).

Long term preservation of canine pancreas by a new simple cold storage method using perfluorochemical (PFC), two-layer (Euro-Collins' solution (EC)/PFC) cold storage method, was tested in the canine model of segmental pancreas autotransplantation. The functional recovery of the graft preserved by this method (group 1) was determined by daily fasting blood glucose concentration and intravenous glucose tolerance test at two weeks after autotransplantation and compared with simple cold storage with EC (group 2), cold storage in EC with simple bubbling of oxygen (group 3), and control (no preservation) (group 4). Maintenance of normoglycemia at least 5 days after transplantation was considered a success of preservation. The functional success rates after 24 hour preservation were 4/4 (100%), 4/4 (100%) and 4/5 (80%) for groups 1, 2 and 3 respectively, and the functional success rates of groups 1, 2 and 3 after 48 hour preservation were 5/6 (86%), 1/5 (20%) and 1/5 (20%) respectively. In addition the functional success rates after 72 hour preservation were 6/6 (100%), 0/6 (0%) and 0/5 (0%) for groups 1, 2, and 3 respectively. It was clear that the two-layer cold storage method had made it possible to preserve the canine pancreas for up to 72 hours although the upper limit of reliable preservation time of groups 2 and 3 was 24 hours. The mean K value of group 1 after 72 hour preservation was 1.78 +/- 0.42 compared with 2.05 +/- 0.32 of group 4 at two weeks after transplantation. Biopsies of grafts of group 2 and 3 after 72 hours preservation showed remarkable autolytic changes in exocrine and endocrine tissues. In contrast, biopsies of grafts of group 1 after 72 hour preservation showed almost normal architecture in both tissues. In addition, biopsies of 72 hour preserved grafts of group 1 at 4 weeks after autotransplantation showed almost normal pancreatic architecture with minimal fibrotic changes in the exocrine tissue. This study demonstrated the possibility of long-term preservation of the pancreas for transplantation.

Animals↗
PubMed1993

Work in the cold. Review of methods for assessment of cold exposure.

The obvious hazard of a cold exposure under natural as well as artificial conditions is tissue cooling and the associated sequel of more or less harmful effects from cold injury to discomfort. The nature, risk and magnitude of effects depend largely on the cooling effect, which results from the interaction of climatic factors (air temperature, mean radiant temperature, humidity and wind), protection (clothing) and metabolic heat production (activity). Assessment of cold stress should be based on methods which measure or predict this cooling effect in a relevant and reliable way. The nature of cooling encompasses (1) whole-body cooling, (2) extremity cooling, (3) convective cooling (wind chill), (4) conductive cooling (contact) and (5) airway cooling. The review contains a description of methods for evaluation of the various types of cold stress, as well as a discussion of their capacity and limitations. On the basis of selected methods, recommendations related to lowest permissible temperatures and other measures are discussed and compared with published data. Apparently, local cooling in most cases produces discomfort and harmful effects, before more significant whole-body cooling develops. With strong wind or movement at very low temperature, frostnip of unprotected skin may quickly develop. For most other conditions extremity (digit) cooling determines duration of exposure. However, as digit cooling largely depends on whole-body heat balance, it is important to control body cooling by selection and use of appropriate protective clothing.

Acclimatization↗
PubMed2026

Metabolomic differences in the Ophiura sarsii complex from the Yellow Sea Cold Water Mass and Bering Sea Cold Pool.

Metabolomics provides a functional readout of cellular physiology and can reveal metabolite-level differences associated with environmental and evolutionary contexts. Here, we used GC-MS- and LC-MS-based metabolomics to characterize metabolic profiles of the Ophiura sarsii complex from the Yellow Sea Cold Water Mass (YSCWM) and the Bering Sea Cold Pool (BSCP). This metabolomics analysis identified 398 LC-MS/MS and 87 GC-MS/MS differential metabolites (DEMs). Marked metabolic differences were observed between the two taxa, involving antioxidant-related metabolites, central carbon-related intermediates, osmolyte-associated compounds, and membrane lipid components. O. sarsii vadicola from the YSCWM showed higher levels of glutathione, glucose, citric acid, D-ribulose 5-phosphate, and unsaturated lipid-related metabolites, indicating differences in antioxidant-related and energy-associated metabolic profiles. By contrast, O. sarsii from the BSCP was characterized by higher levels of sugar alcohols, particularly myo-inositol, together with differences in membrane lipid-associated metabolites. These results provide metabolomics-based evidence for metabolite-level physiological differences between two members of the O. sarsii complex sampled from the Yellow Sea Cold Water Mass and the Bering Sea Cold Pool, while the relative contributions of lineage divergence and site-specific environmental variation remain to be tested experimentally.

Metabolomics↗
PubMed1996

Immune system of cold-exposed and cold-adapted humans.

The aim of this study was to investigate whether or not the human immune system can be activated by a noninfectious stimulus, thereby improving the physiological status of the individual. The effect of a single cold water immersion (14 degrees C for 1 h) on the immune system of athletic young men, monitored immediately after immersion, was minimal. With the continuation of the cold water immersions (three times a week for a duration of 6 weeks) a small, but significant, increase in the proportions of monocytes, lymphocytes with expressed IL2 receptors (CD25) and in plasma tumour necrosis factor alpha content was induced. An increase in the plasma concentrations of some acute phase proteins, such as haptoglobin and haemopexin, was also observed. After 6 weeks of repeated immersions a trend towards an increase in the plasma concentrations of IL6 and the amount of total T lymphocytes (CD3), T helper cells (CD4), T suppressor cells (CD8), activated T and B lymphocytes (HLA-DR) and a decrease in the plasma concentration of alpha 1-antitrypsin was observed. Concentrations of IL1 beta, neopterin, C-reactive protein, orosomucoid, ceruloplasmin, macroglobulin, immunoglobulins (IgG, IgM, IgA) and C3, C4 components of the complement, as well as the total number of erythrocytes, leucocytes, granulocytes and neutrophils showed no significant changes after the repeated cold water immersions. It was concluded that the stress-inducing noninfectious stimuli, such as repeated cold water immersions, which increased metabolic rate due to shivering the elevated blood concentrations of catecholamines, activated the immune system to a slight extent. The biological significance of the changes observed remains to be elucidated.

Adult↗
PubMed1977

Cold adapted variants of influenza A. II. Comparison of the genetic and biological properties of ts mutants and recombinants of the cold adapted A/AA/6/60 strain.

The genetic and biological properties of 13 recombinant influenza A clones derived at 25 degrees C from the A/AA/6/60-cold variant (by crosses with 4 different wild type strains) were compared with a set of 5-FU induced ts-mutants. The 5-FU mutants had previously been placed into 7 complementation-recombination groups; the A/AA/6/60-cold parent (PI-7) and the 12 cold recombinant clones which were ts were shown to share a lesion with only one of these groups. The parental strain and 5 recombinant clones were evaluated for replication in the lungs and nasal turbinates of hamsters. Each virus appeared to be attenuated; genetic stability correlated with the level of viral replication in the hamster lung, i.e., viruses which grew best showed a tendency to revert to the ts+ phenotype. Characterization of the ts+ revertants for the presence of the cold adaptation property revealed that these viruses exhibited a spectrum of cold adaptation properties. Two viruses, PI-7 (the parental cold variant) and the CR6 recombinant (A/Queensland/6/72) did not revert in either the lungs or nasal turbinates of hamsters.

Animals↗
PubMed1996

Some like it cold: response of microorganisms to cold shock.

Bacteria respond to an abrupt decrease in temperature with a specific response, in which cold-induced proteins (CIPs) are transiently expressed at a higher level. Employing two-dimensional gel electrophoresis, several CIPs have been identified. In spite of this, the overall function of the cold shock response is unclear. Recently, the main attention has focused on a group of conserved cold shock proteins (CSPs) that have been shown to have the highest induction after cold shock and to play a major regulatory role in the physiology of adaptation to low temperatures. CSPs, of which Escherichia coli, Bacillus subtilis, and B. cereus possess a family comprising at least 3-7 proteins, are small acidic proteins that share over 45% of sequence identity. Recent evidence suggests that members of this wide-spread protein family can function both at the transcriptional and translational level in vitro. However, the exact mode of action has yet to be established. In addition, post-transcriptional regulation seems to play a major role in the induction of CSPs, a process in which the ribosome may be involved. This is in accordance with a model in which the ribosome has been proposed to be the sensor of temperature in bacteria.

Bacillus subtilis↗