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PubMedDate not supplied

Effect of alcohol on body core temperature during cold-water immersion.

This study investigates the influence of alcohol on body core temperature during cold-water immersion in human volunteers. In this randomised, double-blind, placebo-controlled crossover trial, 8 healthy male volunteers were randomised to drink 1 litre of beverage containing 50 g alcohol or placebo before 20 degrees C cold-water immersion for 1 hour. Body core temperature was measured before cooling and after 1 hour of immersion with an infrared ear thermometer. After a 1-week interval subjects crossed to the other study branch. In the placebo test, mean temperature decreased after immersion by 0.66 degrees C; after the alcohol mean temperature decreased by 1.0 degrees C (mean difference 0.34, 95% CI 0.14-0.53, P = 0.002).

Adult↗
PubMed1980

The influence of widely fluctuating temperatures on heat production and energetic efficiency of broilers.

Broiler chicks 4 and 4.5 weeks of age were subjected to the following temperature regimens for the experimental periods which ranged from 18 to 24 days in three experiments: cyclic cold temperature (1.7 to 12.8 C), cyclic hot temperature (23.9 to 35 C), cyclic normal temperature (12.8 to 23.9 C), and "changing" temperature. The birds of the "chaning" temperature regimen were rotated from the hot to the cold room and back allowing three days at each temperature on each cycle so that the overall mean temperature was similar for the birds of the changing and the normal regimens during experimental periods. In one experiment three diets with different energy and protein levels were used. The metabolizable energy per kilogram and percent protein were s follows: 3200 and 20 (control diet), 3200 and 17 (low protein diet), and 2800 and 20 (low energy diet). In two other experiments either the control diet or both the control and low energy diets wereused. The response to the different diets was similar at all temperatures so that no diet X temperature interaction occurred. Heat production as a percentage of metabolizable energy intake was least for birds kept at the normal temperature, intermediate for birds subjected to the changing temperatures, and greatest for birds of the cold and hot temperatures. Also, energy gain as percentage of metabolizable energy intake was greatest for birds housed at the normal temperature. The lower energetic efficiency of birds in the changing temperature as compared to birds in the normal temperature suggested an increase in energy cost for maintaining body temperature when chicks were subjected to a widely fluctuating temperature.

Animals↗
PubMed1990

The effects of monthly temperature fluctuations on mortality in the United States from 1921 to 1985.

The impact of short-term temperature fluctuations on mortality has been studied mainly on historical populations, thus providing a limited ability to generalize to contemporary conditions, which would be more useful in determining public health policies aimed at reducing mortality. Therefore, this study examined the effects of monthly temperature fluctuations on mortality in the United States from 1921 to 1985. Monthly data about mortality from the Vital Statistics and temperature from the National Oceanic and Atmospheric Administration and the US Department of Agriculture Weather Bureau were used. Six states were selected to be studied (Massachusetts, Michigan, Washington, Utah, North Carolina, and Mississippi). The analysis was carried out using distributed lag models. The analysis showed that warmer than usual temperatures in July and August, and unusually cold temperatures from January to June are linked to higher mortality. From September to December unusually low temperatures are associated with higher mortality in most states, while temperature has no significant effect on mortality in June and September. In January and February mortality is especially affected by unusually cold weather in the southern states of Mississippi and North Carolina. For example, a one degree drop in the mean temperature in 1921 is associated with a more than 3.5% increase in the February crude death rate in Mississippi and North Carolina and a less than 1% increase in the four other states examined. Finally, in the months from January to March the relationship between monthly fluctuations in the crude death rate and temperature declined over time and became relatively weak by 1985.

Humans↗
PubMed1993

Molecular interconversion of cold-sensitive cytosolic 3,3',5-tri-iodo-L-thyronine-binding proteins from human erythrocytes: effect of cold, heat and pH treatments.

Cytosolic 3,3',5-tri-iodo-L-thyronine-binding proteins (CTBP I, II and IV species) from human red blood cells undergo rapid loss of activity at low temperatures. Cold treatment of CTBPs was accompanied by dissociation of the polymeric protein to the 60 kDa inactive monomer. Re-activation of the cold-inactivated CTBP IV by warming resulted in association of the monomer to the active polymeric form. A similar association-dissociation phenomenon was also obtained isothermically, though pH changes. We conclude that CTBP I and CTBP II are polymeric forms of CTBP IV.

Carrier Proteins↗
PubMed1987

Pinealectomy blocks vernal courtship behavior in red-sided garter snakes.

Male red-sided garter snakes (Thamnophis sirtalis parietalis) court only on emergence from winter dormancy. The salient proximate factor responsible for the initiation of courtship behavior appears to be warm ambient temperatures subsequent to sustained exposure to cold temperatures. In the present study, autumn-captured garter snakes were pinealectomized or sham-pinealectomized 1-2 weeks prior to hibernation. After 17 weeks of maintenance in several ambient lighting and temperature conditions, all males were tested for the presence of courtship behavior. No pinealectomized animals exhibited any indications of reproductive behavior, whereas 53% of sham-pinealectomized males actively courted females. Photoperiod did not influence the prevalence of mating behavior. These results suggest that the pineal gland mediates non-photoperiodic seasonal information in the garter snake. This is the first demonstration, in any vertebrate species, that the pineal gland can directly influence reproductive behavior.

Animals↗
PubMedDate not supplied

Blood, bone marrow and eye fluid ethanol concentrations in putrefied rabbits.

The effect of putrefaction on postmortem blood, bone marrow and eye fluid ethanol levels was evaluated in rabbits. Control and dosed animals were sacrificed and stored at either room temperature (approx. 19 degrees C) or cold temperature (approx. 3.5 degrees C) for as long as 28 days. Control animals stored at room temperature showed ethanol levels in the bone marrow that peaked at 7 days after sacrifice, followed by decreases to a nondetectable level at 21 days. Overall decreases were demonstrated in bone marrow of dosed rabbits stored at room temperature for all postmortem intervals. The control animals stored at low temperature showed no ethanol in the bone marrow and blood until 21 days after sacrifice. Dosed rabbits stored at low temperature showed no significant changes in blood and marrow ethanol until 21 days after sacrifice.

Animals↗
PubMed1999

Anatomical and neurochemical peculiarities of the pika retina: basis for lack of circadian rhythm of core temperature.

We have previously reported a complete lack of circadian rhythm in the body temperature of pikas in contrast to other lagomorphs. In this present study, the anatomical and neurochemical findings by immunohistochemical, photo and electron microscopic methods reveal that the photoreceptor system of this animal is poorly developed. This probably explains their stable core body temperature which help them survive in cold temperatures.

Animals↗
PubMed2001

Ethylene induces antifreeze activity in winter rye leaves.

Antifreeze activity is induced by cold temperatures in winter rye (Secale cereale) leaves. The activity arises from six antifreeze proteins that accumulate in the apoplast of winter rye leaves during cold acclimation. The individual antifreeze proteins are similar to pathogenesis-related proteins, including glucanases, chitinases, and thaumatin-like proteins. The objective of this study was to study the regulation of antifreeze activity in response to ethylene and salicyclic acid, which are known regulators of pathogenesis-related proteins induced by pathogens. Nonacclimated plants treated with salicylic acid accumulated apoplastic proteins with no antifreeze activity. In contrast, when nonacclimated plants were exposed to ethylene, both antifreeze activity and the concentration of apoplastic protein increased in rye leaves. Immunoblotting revealed that six of the seven accumulated apoplastic proteins consisted of two glucanases, two chitinases, and two thaumatin-like proteins. The ethylene-releasing agent ethephon and the ethylene precursor 1-aminocyclopropane-1-carboxylate also induced high levels of antifreeze activity at 20 degrees C, and this effect could be blocked by the ethylene inhibitor AgNO(3). When intact rye plants were exposed to 5 degrees C, endogenous ethylene production and antifreeze activity were detected within 12 and 48 h of exposure to cold, respectively. Rye plants exposed to drought produced both ethylene and antifreeze activity within 24 h. We conclude that ethylene is involved in regulating antifreeze activity in winter rye in response to cold and drought.

Antifreeze Proteins↗
PubMed1993

Air pollution, lagged effects of temperature, and mortality: The Netherlands 1979-87.

OBJECTIVE: To explore whether the apparent low threshold for the mortality effects of air pollution could be the result of confounding. DESIGN: The associations between mortality and sulphur dioxide (SO2) were analysed taking into account potential confounding factors. SETTING: The Netherlands, 1979-87. MEASUREMENTS AND MAIN RESULTS: The number of deaths listed by the day on which the death occurred and by the cause of death were obtained from the Netherlands Central Bureau of Statistics. Mortality from all causes and mortality from four large groups of causes (neoplasms, cardiovascular diseases, respiratory diseases, and external causes) were related to the daily levels of SO2 air pollution and potential confounders (available from various sources) using log-linear regression analysis. Variables considered as potential confounders were: average temperature; difference between maximum and minimum temperatures; amount of precipitation; air humidity; wind speed; influenza incidence; and calendar year, month, and weekday. Both lagged and unlagged effects of the meteorological and influenza variables were considered. Average temperature was represented by two variables--'cold', temperatures below 16.5 degrees C, and 'warm', those above 16.5 degrees C--to allow for the V shaped relation between temperature and mortality. The positive regression coefficient for the univariate effect of SO2 density on mortality from all causes dwindles to close to zero when all potential confounding variables are taken into account. The most important of these represents the lagged (one to five days) effect of low temperatures. Low temperatures have strong lagged effects on mortality, and often precede relatively high SO2 densities in the Netherlands. Results were similar for separate causes of death. While univariate associations suggest an effect of air pollution on mortality in all four cause of death groups, multivariate analyses show these effects, including that on mortality from respiratory diseases, are a result of confounding. CONCLUSIONS: The SO2 density (or that of compounds closely associated with SO2) does not seem to have any short term effect on mortality in the Netherlands. SO2 levels higher than those currently reached in the Netherlands (above 200 micrograms/m3) may have a measurable effect on mortality and this should be investigated. Furthermore, analyses of the public health impact of outdoor air pollution should properly control for the lagged effects of temperature.

Air Pollution↗
PubMed1997

The effect of temperature and adrenaline on the relative importance of the sarcoplasmic reticulum in contributing Ca2+ to force development in isolated ventricular trabeculae from rainbow trout

The sarcoplasmic reticulum (SR) is central to intracellular Ca2+ regulation during excitation­contraction (E-C) coupling in mammalian cardiac tissue. The importance of the SR to E-C coupling in lower vertebrates is less certain. This uncertainty can be attributed, in part, to the temperature-dependency of the SR Ca2+-release channel and to interspecific differences in the ryanodine-sensitivity of ectotherm cardiac muscle. Furthermore, the relative importance of the SR in contributing intracellular Ca2+ to force development may be influenced by adrenergic stimulation, which increases trans-sarcolemmal (extracellular) Ca2+ influx. The objective of this study was to assess the relative importance of SR (intracellular) and sarcolemmal (SL; extracellular) Ca2+ fluxes during the isometric contraction of isolated ventricular trabeculae from rainbow trout Oncorhynchus mykiss. To approximate in vivo Ca2+ availability to the muscle better, a tonic level (10 nmol l-1) of adrenaline was used in all control experiments, and SL Ca2+ influx was stimulated with high levels (10 µmol l-1) of adrenaline. Ryanodine, a noted blocker of SR Ca2+ release in mammals, was used to assess SR involvement. To examine the role of temperature on the relative Ca2+ contribution from each source, experiments were performed at two temperatures (12 and 22 °C), using ventricular trabeculae from fish acclimated to both 12 and 22 °C. Under all test conditions studied, SL Ca2+ influx was the primary source of activator Ca2+, as assessed by the change in isometric force after ryanodine application. Even so, the SR contribution of activator Ca2+ was significantly greater at a test temperature of 22 °C than at 12 °C. We attribute this observation to the temperature-dependent nature of the SR Ca2+-release channel. At 22 °C and under control conditions, ryanodine reduced peak tension at all pacing frequencies (by approximately 50 % at 0.2 Hz, approximately 25 % at 1.2 Hz and approximately 20 % at 2.0 Hz), regardless of acclimation temperature. Therefore, the SR is a significant, but secondary, contributor of activator Ca2+ for tension development at warm temperatures. The magnitude of SR Ca2+ contribution was inversely related to pacing frequency, but remained significant at physiological pacing frequencies. This was a novel finding. The degree of ryanodine-sensitivity in the present study was greater than that reported previously for the rainbow trout. We attribute this difference to the use of tonic adrenergic stimulation in the present study. In contrast to the experiments at the warmer test temperature, at 12 °C and under control conditions, ryanodine significantly reduced peak tension only at low frequencies (by approximately 25 % at 0.2 Hz), regardless of acclimation temperature. These findings suggest that at cold temperatures, and at physiologically relevant pacing frequencies, the SR may not be important in supplying Ca2+ to the contractile elements of the trout heart. At both test temperatures and regardless of acclimation temperature, stimulation with 10 µmol l-1 adrenaline caused positive inotropy of sufficient magnitude to ameliorate the negative inotropic effect of ryanodine completely, with the exception of high pacing frequencies (>1.2 Hz) at 22 °C, where adrenergic stimulation did not fully compensate for the effects of ryanodine. This exception is discussed in relation to the reduced adrenergic sensitivity of the trout myocardium at warm temperatures. The adrenergically mediated compensation for the loss of the SR Ca2+ supply is a novel finding for fish hearts. Therefore, while our study clearly demonstrates that the relative importance of SR Ca2+ release is subject to temperature and frequency, adrenaline-mediated increases in SL Ca2+ influx decrease the importance of the SR in contributing Ca2+ to E-C coupling in trout ventricular myofilaments.

Journal Article↗
PubMed1988

Interaction of temperature with other environmental factors in controlling the development of plants.

Development is the ordered sequence of changes in plant form and phenology that occurs through time. As such it is distinguished from that of growth and includes the succession of ontogenetic stages as well as the initiation of leaves, shoots and roots. It is more useful to look at rates of development as functions of environmental influences rather than, for example, total number of days to a given stage. It is often found that linear, or close to linear, relationships are found between rates and temperature, photoperiod and the duration of cold temperatures. These ideas are treated theoretically and illustrated with data from an experiment where wheat was grown at ten sites in Britain. We conclude that temperature is the most important factor governing differences in developmental rates between sites and sowing dates, especially for later stages of development. Variation in the timing of earlier stages depends on either exposure to photoperiods of different lengths or on the degree of vernalization of the plants. Calculation is made of the maximum effectiveness of these environmental factors in shortening the vegetative phases in a range of wheat cultivars and the basis of their interaction is also explored. For wheat it seems that they act multiplicatively in their effect on developmental rate. The rate at which plants produce their leaves is important in canopy development. The sensitivity of the rate of leaf emergence, measured in thermal time, has been linked to the rate at which daylength changes (d phi/dt). A possible mechanism may involve plants responding to the ratio of light in the red (R, ca 660 nm) and far-red (FR, ca 730 nm) wavebands (R/FR). This ratio decreases when d phi/dt is becoming more negative and vice versa. Linkage can be found between the change in R/FR at twilight and commensurate changes in calculated phytochrome photoequilibria. Thus, the possibility exists that phytochrome may be involved in modulating the leaf production rate in response to different sowing dates. Alternatively, variation in rate of leaf production may be through changes in the base temperature, in response to the 'spectrum' of temperatures the plants experience during development. Thus, any involvement of photoperiod in this response may be spurious. Controlled environment studies of leaf emergence tend to support this latter interpretation as does analysis of experiments from three European sites.

Edible Grain↗
PubMed1993

Temperature affects human cardiac sarcoplasmic reticulum energy-mediated calcium transport.

Hypothermic cardioplegic solutions are currently used to preserve cardiac function during transportation. However, it has been shown that end-diastolic compliance decreases in donor hearts during reperfusion. Excessively cold temperatures may affect membrane-bound enzymes (Ca2+ ATPase and Ca2+ uptake) which are necessary for calcium homeostasis. To study the effect of temperature on Ca2+ ATPase and Ca2+ uptake activities over the temperature range to which a donor heart is usually exposed (4 degrees-37 degrees C), sarcoplasmic reticulum (SR) was isolated from human atrial appendages. SR was also isolated from atrial appendages which had been stored in saline at 4 degrees C for 4 or 24 h or 24 h in St Thomas' cardioplegic solution (ST). Ca2+ ATPase and Ca2+ uptake from these samples were compared with those found in the SR of unstored appendages. The activity of Ca2+ uptake and Ca2+ ATPase showed great sensitivity at assay temperatures below 22 degrees C, while no such sensitivity was identified in SR NADPH/cytochrome C reductase (NCR). After storage of atrial appendages for only 4 h in saline at 4 degrees C, Ca2+ uptake activity was reduced 50% in the SR when compared to unstored controls (80 +/- 9.9 nmol/mg/min and 155.24 +/- 2.4 nmol/mg/min, respectively; P < 0.02) whereas Ca2+ ATPase was not affected until 24 h of storage, when the activity was also decreased > 50% (P = 0.0002). However, NCR was not affected. In addition, storage at 4 degrees C significantly decreased the SR protein yield (mg/g homogenate protein) at 4 or 24 h in saline as well as 24 h in ST. However, there was no decrease in the enzyme activities (Ca2+ ATPase, 229 +/- 25.3; Ca2+ uptake, 221 +/- 27.1; NCR, 24.9 +/- 0.48 nmol/mg/min). Following exposure to low temperature, alteration of Ca2+ uptake and Ca2+ ATPase may result in disruption of calcium homeostasis, thereby interrupting excitation-contraction coupling and relaxation. The damaging effects of hypothermia should be taken into account when assessing the peri-operative complications and the long-term results of cardiac transplantation.

Analysis of Variance↗
PubMed1988

Adaptive changes in individual acyl-CoA esters from hamster BAT during cold acclimation.

Long-chain fatty acyl-CoA esters (LCFACoAE) were extracted from freeze-clamped powdered brown adipose tissue (BAT) obtained from thermoneutral control and cold-acclimated hamsters and the CoA esters individually separated by high-performance liquid chromatography. LCFACoAE of carbon chain length C12 to C20 were identified by increasing column retention time in the following order: C12:0, C14:1, C14:0, C16:1, C18:2, C16:0, C18:1, C18:0, and C20:4. The mean total LCFACoAE concentrations were 235 +/- 40 nmol/g protein for the control hamsters and 648 +/- 105 nmol/g protein for the 22-day cold-acclimated hamsters. A rapid fourfold increase in the levels of C16:0, C18:0, and C18:1 occurred within hours after initiation of the cold temperature, whereas the concentrations of the other six LCFACoAE either increased only slightly or remained unchanged. Almost 50% of the total LCFACoAE in the BAT of cold-acclimated hamsters was made up of C16:0, C18:0, and C18:1. These results, which demonstrate some dynamic changes in adipose tissue LCFACoAE, are consistent with their proposed role in the initiation and maintenance of BAT thermogenesis.

Acclimatization↗
PubMed2004

Seasonal changes in metabolic and temperature responses to cold air in humans.

The metabolic and temperature response to mild cold were investigated in summer and winter in a moderate oceanic climate. Subjects were 10 women and 10 men, aged 19-36 years and BMI 17-32 kg/m2. Metabolic rate (MR) and body temperatures were measured continuously in a climate chamber with an ambient temperature of 22 degrees C for 1 h and subsequently 3 h of 15 degrees C. The average metabolic response during cold exposure, measured as the increase in kJ/min over time, was significantly higher in winter (11.5%) compared to summer (7.0%, P < .05). The temperature response was comparable in both seasons. The metabolic response in winter was significantly related to the response in summer (r2 = .47, P < .001). Total heat production during cold exposure was inversely related to the temperature response in both seasons (summer, r2 = .39, P < .01; winter r2 = .32, P < .05). In conclusion, the observed higher metabolic response in winter compared to summer indicates cold adaptation. The magnitude of the cold response varies, but the relative contribution of metabolic and temperature response was subject specific and consistent throughout the seasons, which can have implications for energy balance and body composition.

Acclimatization↗
PubMed2006

Low cost of locomotion in lizards that are active at low temperatures.

The nocturnality hypothesis of K. Autumn and coworkers states that nocturnal geckos have evolved a low energetic cost of locomotion (C(min)). A low C(min) increases maximum aerobic speed and partially offsets the decrease in maximum oxygen consumption caused by activity at low nocturnal temperatures. We tested whether a low C(min) is unique to nocturnal geckos or represents a more general pattern of convergent evolution among lizards that enables nocturnality and/or cold-temperature activity. We measured C(min) in four carefully selected lizard species from New Zealand (two nocturnal and two diurnal; n=5-9 individuals per species), including a nocturnal and diurnal gecko (a low C(min) is a gecko trait and is not related to nocturnality), a nocturnal skink (a low C(min) is related to being nocturnal), and a diurnal skink active at low temperatures (a low C(min) is related to being active at low body temperatures). The C(min) values of the four species measured in this study (range=0.21-2.00 mL O(2) g(-1) km(-1)) are lower than those of diurnal lizards from elsewhere, and the values are within or below the 95% confidence limits previously published for nocturnal geckos. A low C(min) increases the range of locomotor speeds possible at low temperatures and provides an advantage for lizards active at these temperatures. We accepted the hypothesis that nocturnal lizards in general have a low C(min) and provide evidence for a low C(min) in lizards from cool-temperate environments. The low C(min) in lizards living at high latitudes may enable extension of their latitudinal range into otherwise thermally suboptimal habitats.

Animals↗
PubMed2004

Temperature and nutrient availability control growth rate and fatty acid composition of facultatively psychrophilic Cobetia marina strain L-2.

A facultative psychrophilic bacterium, strain L-2, that grows at 0 and 5 degrees C as minimum growth temperatures in complex and defined media, respectively, was isolated. On the basis of taxonomic studies, strain L-2 was identified as Cobetia marina. The adaptability of strain L-2 to cold temperature was higher than that of the type strain and of other reported strains of the same species. When the bacterium was grown at 5-15 degrees C in a defined medium, it produced a high amount of trans-unsaturated fatty acids. By contrast, in a complex medium in the same temperature range it produced a low amount of trans-unsaturated fatty acids. In the complex medium at 5 degrees C, the bacterium exhibited a three-fold higher growth rate than that obtained in the defined medium. Following a temperature shift from 11 to 5 degrees C, strain L-2 grew better in complex than in defined medium. Furthermore, when the growth temperature was shifted from 0 to 5 degrees C both the growth rate and the yield of strain L-2 growing in complex medium was markedly enhanced. These phenomena suggest that an upshift of the growth temperature had a positive effect on metabolism. The effects of adding complex medium components to the defined medium on bacterial growth rate and fatty acid composition at 5 degrees C were also studied. The addition of yeast extract followed by peptone was effective in promoting rapid growth, while glutamate addition was less effective, resulting in a cis-unsaturated fatty acid ratio similar to that of cells grown in the complex medium. These results suggest that the rapid growth of strain L-2 at low temperatures requires a high content of various amino acids rather than the presence of a high ratio of cis-unsaturated fatty acids in the cell membrane.

Cell Membrane↗
PubMed1989

Anemia at the onset of winter in the meadow vole (Microtus pennsylvanicus).

1. From 1981 to 1986, 6120 meadow voles (Microtus pennsylvanicus) were sampled for hematological indices in southeastern Manitoba, Canada. This survey revealed the sporadic occurrence of anemia in early winter at mean temperatures below about -5 degrees C. 2. Anemia was associated with leukocytosis and circulating normoblasts, suggesting a sudden, large blood loss. Individuals became anemic quickly, with no obvious predisposing factors. 3. Attempts were made to induce anemia by exposing voles in traps to various temperatures. Temperatures characteristic of most trapping sessions failed to induce anemia in both wild and laboratory-born voles. 4. Short-term exposure to more extreme temperatures (-20 to -30 degrees C) induced anemia. Voles lost blood through erosions of the epithelium of the glandular stomach, and developed other pathological lesions characteristic of hypothermia. 5. Although there was a strong association between cold weather and anemia, we could find no clear relationship between winter survival and winter weather. However, in 1984, extraordinarily cold temperatures were associated with anemia and a subsequent population decline. These events suggest a threshold mean daily temperature of about -15 degrees C, below which vole survival is grossly affected. 6. Deteriorating protein levels and energy reserves of small mammals in winter may make them particularly susceptible to cold stress. Hence, sporadic bouts of sustained cold may be responsible for some of the enigmatic winter declines seen in northern small mammals.

Acclimatization↗