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 487 records · Page 27Linked to original sources
PubMed1986

[Effect of ganglionectomy (superior cervical ganglia) at normal temperature and exposure to cold on the circadian rhythm of liver glycogen and blood glucose levels of the Wistar rat with regard to the pineal gland].

Liver glycogen content and blood glucose level of 80 male Wistar rats were measured 4 times a day, 30 d after following surgeries: sham-operation without exposure to cold, sham-operation with exposure to cold (283 K, 72 h before killing), extirpation of the ganglia cervicalia superiora (GX) without exposure to cold, extirpation of the ganglia cervicalia superiora with exposure to cold (283 K, 72 h before killing). Exposure to cold alone as well as GX with and without exposure to cold modify the unimodal daily patterns (curves were calculated by means of empirical regression) of liver glycogen content and blood glucose level: there are changes from contrary localization of the maxima (and minima) of both, liver glycogen content and blood glucose level (exposure to cold alone) to nearly equal localization (GX alone). Compared to control group, all surgeries reduce the liver glycogen content statistical-significantly and also enhance the blood glucose level. Combination of GX with exposure to cold shows the strongest effect. In this case, the influence of GX is visible, but the effect is not significantly different from this of exposure to cold alone, which causes a high activation of the metabolism. To the contrary, a statistically significant influence is to be seen after GX alone, but the effect is lower than this one of exposure to cold. Extirpation of the ganglia cervicalia superiora and the resulting sympathetic denervation of the pineal gland is answered by comparable reactions of the investigated parameters as the extirpation of the pineal gland itself (90 d post operationem). Diminuation of liver glycogen content and enhancement of blood glucose level characterize the influence of gangliectomy (30 d post operationem) in this way, that the ratio of effect of factors causing hypo- and hyperglycemia is changed in favour of the latter.

Animals↗
PubMed1984

[Influence of the environmental temperature on the metabolic use of dietary energy and nitrogen in the growing rat].

Sixty-seven male rats of the Wistar CF strain were used in two trials to study the effect of ambient temperature on nitrogen and energy balances (experiment 1) and on the variations of certain biochemical parameters of metabolism (experiment 2). In both cases, the rats, housed individually in metal cages and fed ad libitum, were kept under three different temperatures : 21 degrees C (control), 3 degrees C (cold), 31 degrees C (hot). Compared to the controls, the rats at 3 degrees C showed a significant increase (P less than 0.01) in food intake and a significant decrease (P less than 0.01) in daily growth rate and feed efficiency ratio; body fat content was unchanged. Compared to the controls, the rats at 31 degrees C showed a decrease (P less than 0.01) in food intake and growth rate, a better feed efficiency ratio (P less than 0.01) and a significant increase in carcass lipid content. When compared to rats at 21 degrees C, those at 3 degrees C had a much lower nitrogen retention; at 31 degrees C this retention was only slightly lower. The urinary nitrogen excretion, increased by the cold temperature, reflected higher nitrogen catabolism, while its increase at a high temperature was probably due to a decrease in protein synthesis, and a subsequent degradation of excess ingested nitrogen. Energy retention increased (P less than 0.01) as the ambient temperature increased from 3 to 31 degrees C, and wide variations in the amounts of fixed energy in the form of proteins or lipids were observed. The balance results obtained have been discussed in relation to the variations of some biochemical parameters of metabolism such as free fatty acids, free glycerol, lipoprotein-lipase activity and in vitro utilization of labelled glucose.

Animal Feed↗
PubMed1986

Adaptation to cold antagonizes neurotensin-induced hypothermia in mice.

Intracerebrally-administered neurotensin produces a marked hypothermia in a variety of mammals. In this study, prior adaptation to a cold environment was found to significantly antagonize the hypothermia produced by intracisternally-administered neurotensin in mice. This antagonism required both previous exposure to cold ambient temperatures and cold exposure immediately prior to, or simultaneously with, neurotensin administration. The antagonism of neurotensin-induced hypothermia by prior cold-adaptation was blocked by indomethacin, but not by acetylsalicylic acid, suggesting that brain prostaglandin synthesis may be essential for this newly-discovered phenomenon.

Adaptation, Physiological↗
PubMed1978

Microtubules in protozoan cells. III. Ultrastructural changes during disintegration and reformation of heliozoan microtubules.

In the heliozoan, Echinosphaerium nucleofilum strain MA, cold temperature (2 degrees C) induced axopodial retraction to about 36% of the initial length after 3 h. By electron microscopy, it was found that such axopodial shortening is accompanied by degradation of axonemal microtubules (25 nm in diameter), followed by the appearance of macrotubles (37 nm in diameter) and filamentous structures (14 nm in diameter) of a tubular and twisted appearance. All of these structures (microtubules, macrotubules and filamentous structures) were found to be depolymerized completely by applying 10 mM colchicine for 1-2 h, and to be replaced by regions with low electron density. Axopodial re-extension was induced rapidly by returning the cold-treated organisms to room temperature (20 degrees C). At a very early stage of axopodial re-extension, the filamentous structures were often observed to be continuous with the macrotubules. At a late stage of axopodial re-extension, the reforming axoneme was composed only of normal microtubules, while the macrotubules and filamentous structures had disappeared. On the basis of these results, the processes of disintegration and reformation of microtubules are discussed.

Animals↗
PubMed2004

Clues to understanding cold sensation: thermodynamics and electrophysiological analysis of the cold receptor TRPM8.

The cold and menthol receptor, TRPM8, also designated CMR1, is a member of the transient receptor potential (TRP) family of excitatory ion channels. TRPM8 is a channel activated by cold temperatures, voltage, and menthol. In this study, we characterize the cold- and voltage-induced activation of TRPM8 channel in an attempt to identify the temperature- and voltage-dependent components involved in channel activation. Under equilibrium conditions, decreasing temperature has two effects. (i) It shifts the normalized conductance vs. voltage curves toward the left, along the voltage axis. This effect indicates that the degree of order is higher when the channel is in the open configuration. (ii) It increases the maximum channel open probability, suggesting that temperature affects both voltage-dependent and -independent pathways. In the temperature range between 18 degrees C and 25 degrees C, large changes in enthalpy (DeltaH=-112 kcal/mol) and entropy (DeltaS=-384 cal/mol K) accompany the activation process. The Q10 calculated in the same temperature range is 24. This thermodynamic analysis strongly suggests that the process of opening involves large conformational changes of the channel-forming protein. Therefore, the highly temperature-dependent transition between open and closed configurations is possible because enthalpy and entropy are both large and compensate each other. Our data also demonstrate that temperature and voltage interact allosterically to enhance channel opening.

Cell Line↗
PubMed1999

A minireview of studies conducted in japan using finger-skin temperature during cold-stress tests for the diagnosis of hand-arm vibration syndrome.

For the diagnosis of the hand-arm vibration syndrome, cold-stress tests using different water temperatures and periods of hand immersion have been investigated in Europe, North America, and Japan. In recent years, peripheral circulation and sensory tests, including finger-skin temperature measurement involving immersion of one hand in cold water at 10 degrees C for 10 min, have been widely accepted in Japan. On the other hand, standardization of the vascular assessment method is under discussion at the International Organization of Standardization. We reviewed research findings from Japan concerning finger-skin temperature measurement during the cold-stress test, especially factors influencing the test results and the diagnostic significance. For establishment of the cold-stress test for epidemiology studies of the hand-arm vibration syndrome, standardization of the environmental factors influencing the test results and reporting of its sensitivity and specificity are needed.

Arm↗
PubMed1992

Effects of cold on vascular permeability and edema formation in the isolated cat limb.

We investigated the effects of cold temperatures on microvascular protein permeability in the isolated constant-flow perfused cat hindlimb. The perfusates were 20% cat plasma-80% albumin-electrolyte solution (low-viscosity perfusate, approximately 1 cP) or whole blood (high-viscosity perfusate, approximately 4 cP). The time at low temperature (less than 10 degrees C) was less than 3 h (short term) or greater than 5 h (long term). Decreases in the solvent drag reflection coefficient (sigma f) indicated increases in permeability. The sigma f's were determined with the integral-mass balance method from measurement of changes in protein concentration and hematocrit induced by fluid filtration into the tissues. Short-term cold exposure did not increase permeability with either a low- or a high-viscosity perfusate, whereas long-term exposure with limb temperatures of approximately 5 degrees C significantly increased permeability when the perfusate was whole blood. In addition, we verified our previous prediction that flow had to be reduced to 6-8 ml.min-1.100 g-1 to avoid the hydrostatic edema caused by short-term perfusion with whole blood at approximately 5 degrees C. Also, we found that at approximately 3 degrees C histamine's permeability-increasing effect was totally abolished, whereas at approximately 20 degrees C this effect was partially inhibited. Hence, constant-flow perfusion at low temperature with whole blood can cause edema by a pressure-dependent mechanism, whereas long-term perfusion with this perfusate at low temperatures can cause a permeability increase that further compounds edema formation. Histamine is not responsible for this permeability increase.

Animals↗
PubMed1998

Wild and cultivated barleys show differences in the expression pattern of a cold-regulated gene family under different light and temperature conditions.

Cold acclimation in plants involves the expression of many genes and gene families. The present study reports the expression analysis of three members of the blt14 gene family in barley. Gene-specific antisense oligonucleotides were used as probes in northern experiments so as to follow independently the expression of individual members of the gene family. Each clone revealed different accumulation kinetics when a spring and a winter cultivar were compared, suggesting that the different regulatory mechanisms leading to mRNA accumulation of an individual member of the blt14 gene family are genotype-dependent. In a collection of Hordeum spontaneum genotypes both qualitative and quantitative polymorphisms were found for the accumulation of blt14-related mRNAs, although no clear relationships were found between blt14 expression and frost resistance. The accumulation of the blt14-related mRNAs was also modulated by light and by the albino mutation a(n). The effects of light on the accumulation of the transcripts corresponding to the blt14 gene family were evaluated by comparing etiolated and green plants. Etiolated plants accumulate the blt14-related mRNAs at a detectable level already at 22 degrees C. When the same plants are exposed to cold in absence of light an increased mRNA accumulation above the level present in green cold-treated plants can be detected. On the contrary, etiolated plants showed a reduced blt14 accumulation when exposed to cold in the presence of light. Cold-induced expression of the blt14 gene family was strongly reduced in plants carrying the albino mutation a(n). This mutant showed a defective molecular response to cold even when probed with a cDNA coding for LEA type protein (paf93). The albino mutant a(n) was not able to harden when exposed to low temperature providing a direct evidence of the relationship between expression of cold-regulated (COR) genes and the development of cold hardening. Failure of cold acclimation in the mutant cannot be merely ascribed to the absence of photosynthetic activity, since etiolated wild-type plants accumulated COR mRNAs and improved frost resistance when exposed to cold.

Acclimatization↗
PubMed1986

Slow outward tail currents in molluscan bursting pacemaker neurons: two components differing in temperature sensitivity.

Bursting pacemaker neurons of Tritonia and Aplysia were studied in voltage-clamp experiments to determine the ionic requirements of the slow outward tail current. This current is important for terminating bursts and hyperpolarizing the neuron during the interval between bursts and therefore contributes to the timing of pacemaker activity. A method for rapid extracellular perfusion of the neuron soma with solutions of different ionic composition was used to study the ionic dependence of the tail current. Measurements of the current-voltage relationship were made at different times during the decay of the tail current to determine the reversal potential in different ionic solutions. These experiments showed that 2 or more slow outward currents contribute to the tail current. Temperature had a large effect on these currents. At cold temperatures (10-15 degrees C), the tail current was predominantly a K current. At warm temperatures (20-23 degrees C), both a K current and a K-insensitive outward current were seen. Bursting pacemaker activity occurred throughout this temperature range. Both the K current and the K-insensitive current required Ca influx for activation. These findings help to reconcile conflicting reports in the literature concerning the ionic dependence of the slow outward tail current and suggest a mechanism for temperature compensation of bursting activity in these pacemaker cells.

Action Potentials↗
PubMedDate not supplied

Daily PM10/mortality associations: an investigations of at-risk subpopulations.

Recent time-series epidemiological studies have reported significant associations between daily air pollution and mortality. These studies typically report a short-term excess increase in deaths as the fractional increase of total (nonaccidental) deaths per unit of air pollutant. The relative risk (RR) calculated for the total population in these studies, however, may underestimate the risk for the most sensitive subpopulation(s) at risk. In this study, race, gender, and cause-specific counts of daily mortality in Cook County, Illinois (which encompasses the city of Chicago) during 1985-1990 were analyzed to determine if there was any heterogeneity in air pollution/weather/mortality associations across these various population subcategories. Seasonal cross-correlations between mortality and environmental variables first were examined to identify appropriate lag structures. Of the pollution variables considered-particulate matter less than 10 microns (PM10), ozone, carbon monoxide, sulfur dioxide, and visual range-derived extinction coefficient-both PM10 and ozone showed significant associations with same-day and next-day mortality. The Poisson regression models employed included seasonal cycles (sine/cosine series), square and linear terms of lagged temperature, trend line, day-of-week dummy variables, and the average of the same day's and previous day's PM10 or ozone. The RR for total nonaccidental mortality per 100 micrograms/m3 increase in PM10 was 1.05 (95% CI: 1.03-1.08). The respiratory (RR = 1.14; 95% CI: 1.04-1.25) and cancer (RR = 1.12; 95% CI: 1.06-1.18) categories showed higher estimates than the circulatory category (RR = 1.03; 95% CI: 0.98-1.07), while the residual of the total from these three categories showed no association with PM10 (RR = 1.01; 95% CI: 0.95-1.08). Among the race- and gender-specific categories, black (African-American) females showed the higher RRs for the total (RR = 1.11; 95% CI: 1.03-1.21), respiratory (RR = 1.31; 95% CI: 0.98-1.75), and cancer (RR = 1.25; 95% CI: 1.07-1.46) mortality categories. Neither ozone nor hot temperature showed such cause-specificity in mortality associations. Cold temperature lagged by two days was a significant predictor of circulatory and respiratory mortality. This study suggests the importance of race- and gender-specific analysis. The greater mortality risk to Chicago's black women from exposure to urban air pollution indicated by this finding should be tested in other metropolitan areas.

Air Pollutants↗