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PubMed1981

Lung function after marathon running at warm and cold ambient temperatures.

using maximal expiratory flow-volume curves we studied the effects of endurance exercise on lung function in 46 and 41 runners before and after completion of a marathon race (42.2 km) at different ambient temperatures. There was a significant decrease (-3.9%; -5.9%) in the post-race forced vital capacity in runners at each marathon. The mean values for forced expiratory volume in one second did not change. Post-race peak flow at 50% of forced vital capacity were significantly decreased in runners participating in subfreezing conditions (-2 degrees C to -4 degrees C), but were unchanged when the ambient temperature was above freezing. These data demonstrated that healthy persons may develop bronchoconstriction during endurance exercise in subfreezing temperatures. The decrement in forced vital capacity noted in marathon runners competing at above freezing temperatures may be related to fuel metabolism and running performance.

Adolescent↗
PubMed1993

Reflex sympathetic dystrophy and repetitive strain injury: temperature and microcirculatory changes following mild cold stress.

Temperature and blood flow studies were performed in the upper limbs of six patients with reflex sympathetic dystrophy (RSD), nine patients with repetitive strain injury (RSI) and 12 control subjects using thermography, laser Doppler flowmetry, infrared photoplethysmography and venous occlusion strain gauge plethysmography. The contralateral responses of the symptomatic and asymptomatic limbs were examined after being subjected, separately, to mild cold stress (20 degrees C for 1 min). Altered thermoregulation and haemodynamics were evident in RSD. Though the pattern of response to contralateral cold challenge is similar to normal in RSI, vasodilatation and reduced vasomotion appears to be characteristic in this condition. Such changes may assist in distinguishing between RSD and RSI from other causes of chronic upper limb pain.

Adult↗
PubMed1982

Response properties of high-threshold cutaneous cold receptors in the primate.

Cutaneous high-threshold cold receptors (HCRs) in the monkey were identified as sensitive only to cold temperatures below 27 degrees C and not responsive to mechanical or heat noxious stimulation. Some HCRs had axons conducting in the low A-delta range while others had C fibers. The response properties of HCRs were contrasted with those of mechanothermal nociceptors, the latter believed to contribute to the sense of cold pain. HCRs with A delta fibers may contribute to the sense of innocuous cold below temperatures to which low-threshold cold receptors are maximally responsive.

Afferent Pathways↗
PubMed1995

Growth of broiler chickens in response to feed restriction regimens to reduce ascites.

A trial was conducted to investigate the impact of early feed restriction on ascites induced by cold temperatures and the subsequent effect on the whole body and breast muscle growth of broilers. Two feed restriction regimens were tested, consisting of limiting daily feed intake of the birds to 75% of the ME required for normal growth from either 4 to 11 d or from 7 to 14 d. At 21 d, half of the birds were moved to a cold house (17.8 C) to induce ascites. Five birds from each pen were killed for the breast muscle growth, Pectoralis major and Pectoralis minor, and heart and abdominal fat pad weights at 4, 7, 11, 14, 21, 35, and 49 d of the experiment. Birds in the cold house were heavier and had better feed conversion than birds in the control house at 49 d of age. This could be attributed to the high ambient temperatures (27 to 33 C) in the control house. The ad libitum birds had a significantly greater percentage of P. major than the feed-restricted birds. Exposure to cold temperatures caused significantly higher percentage of ascites from 21 to 49 d. Cold temperatures also increased the percentage of total heart and the right ventricle weight relative to total heart weight ratio at 35 and 49 d of age, suggesting that the surviving birds were more likely to develop ascites. Although catch-up growth was observed, the final body weight of feed-restricted birds was not the same as ad libitum birds. Early feed restriction reduced the incidence of ascites, but at the cost of breast muscle growth.

Age Factors↗
PubMed1982

Recycling of cold-stable microtubules: evidence that cold stability is due to substoichiometric polymer blocks.

A substantial subpopulation of mammalian brain crude extract microtubules is resistant to cold-temperature disassembly. We propose here that microtubules are rendered cold stable by rare substoichiometric blocks. Mild shearing of rat brain cold-stable microtubules makes them largely cold labile. In addition, cold-stable microtubules can be destabilized by exposure to low concentrations of calmodulin (5 microM) in the presence of calcium at 0 degree C. Cold-disassembled microtubule protein, obtained from sheared or calmodulin-treated cold-stable preparations, re-forms a cold-stable subpopulation upon reassembly. These observations allow strategies for the recycling purification of cold-stable microtubules. Comparison of purified cold-labile and cold-stable material by gel electrophoresis shows enrichment for a few unique polypeptides, of 135, 70-82, and 56 kilodaltons, in the cold-stable preparation. The 64-kilodalton "switch protein", previously identified as uniquely dephosphorylated in cold-stable microtubules, is equally represented in recycled cold-stable and cold-labile microtubule preparations. Furthermore, when disassembled, cold-stable microtubule proteins are passed through a calmodulin affinity column on which the polypeptides characteristic of cold-stable microtubules are specifically retained, the breakthrough (unbound) material repolymerizes into cold-labile microtubules only. Based on the above data, a model is presented in which microtubules are rendered cold stable by the presence of substoichiometric, calmodulin-sensitive blocks that randomly reshuffle upon reassembly of cold-stable microtubules.

Animals↗
PubMed1951

EXPOSURE to cold.

Explore the source record for details and available documents.

Body Temperature↗
PubMed2005

The contribution of TRPM8 channels to cold sensing in mammalian neurones.

Different classes of ion channels have been implicated in sensing cold temperatures at mammalian thermoreceptor nerve endings. A major candidate is TRPM8, a non-selective cation channel of the transient receptor potential family, activated by menthol and low temperatures. We investigated the role of TRPM8 in cold sensing during transient expression in mouse cultured hippocampal neurones, a tissue that lacks endogenous expression of thermosensitive TRPs. In the absence of synaptic input, control hippocampal neurones were not excited by cooling. In contrast, all TRPM8-transfected hippocampal neurones were excited by cooling and menthol. However, in comparison to cold-sensitive trigeminal sensory neurones, hippocampal neurones exhibited much lower threshold temperatures, requiring temperatures below 27 degrees C to fire action potentials. These results directly demonstrate that expression of TRPM8 in mammalian neurones induces cold sensing, albeit at lower temperatures than native TRPM8-expressing neurones, suggesting the presence of additional modulatory mechanisms in the cold response of sensory neurones.

Animals↗
PubMed1988

Body temperature and grooming in the Mongolian gerbil.

The Mongolian gerbil, Meriones unguiculatus, like many other rodents, releases a complex mixture of pigments and lipids from the Harderian gland during a self-groom. The material exits from the external nares of the nose, is mixed with saliva, and spread widely over the pelage. Cold temperatures, especially, are effective in initiating grooming. A self-groom is associated with an increase in body temperature (compensatory thermogenesis in the cold). In addition to acting as a chemosignal, the Harderian material serves two major homeostatic functions: (1) the lipids on the pelage act to insulate the animal against cold and wetness, and (2) the lipids and pigments darken the pelage and increase radiant absorption. Body temperature is thus maintained at a higher level than would otherwise be the case. The amount of Harderian material found on the pelage varies with Harderianectomy, sandbathing, and ambient temperatures. Animals prevented from sandbathing accumulate excess lipids on the pelage, and cold temperatures facilitate the acquisition of lipids on the pelage. Under hot temperatures the grooming of Harderian substances is repressed and the frequency of sandbathing is increased. Thus pelage lipids are reduced in two ways. The amount of Harderian material released during an autogroom is inversely related to the ambient temperature, whereas the amount of saliva used for evaporative cooling is positively related to ambient temperature. The net effect is that pelage lipids are increased and maintained during cold conditions, and are reduced during hot conditions. In hot environments the gerbil switches from the spread of Harderian material for insulation to the spread of saliva for evaporative cooling. The gerbil optimizes its body temperature by varying the frequency of grooming and sandbathing, and by altering the amount of Harderian material and saliva released. Other species living in arid environments may use similar mechanisms to stabilize body temperature. Self-grooming is a critical behavior for meeting thermal needs, and is complexly integrated with related processes.

Adaptation, Physiological↗
PubMed1975

Responses of spinal cord neurons to systematic changes in hindlimb skin temperatures in cats and primates.

Single-neuron recordings were made from the lumbar spinal cords of cats and squirrel monkeys. Recording sites were distributed throughout the dorsal horn and included Rexed's laminae I and III-VI in both species and laminae VII-VIII in cats. Activity was studied during systematic changes in skin temperature over the range of 15-49 degress C; this encompasses the perceptions of innocuous cooling and warming plus the initial stages of noxious heating. The experiment included studies in which the thermal stimulus was changed from various preadapting temperatures. In all cases, the sensitivity of an individual neuron to changes in skin temperature was associated with responses to various intensities of tactile stimulation which, for some neurons, could range from low to painful pressures. More than two-thirds of the neurons excited by innocuous temperature changes discharged to both cooling and warming, although the thresholds were much lower for cold temperature differecnes (less than or equal to 2 degrees C for cold steps as compared with more than 6 degrees C for warm steps). However, many neurons only responded to extreme cooling or, more frequently, noxious heating. The temperature response relationships of many neurons during cooling was best described in reference to specific cold-receptor activity because the discharge rates declined at extremely cold temperatures and because the slopes of the temperature-response functions were nearly identical when studied with different adapting temperatures. The responses of certain slowly adapting mechanoreceptors was considered in describing some of the spinal cord activity during extreme cooling. The responses to hot temperatures were attributed to activity in various receptors, including especially polymodal receptors. Activity during innocuous warming was ascribed to one population of peripheral warm receptors that do not show maximal static activity during innocuous warm stimuli. The significance of the extensive convergence in the spinal cord from mechanoreceptors and thermoreceptors was discussed in relation to thermal perception and the complexity of the information transmitted by the spinothalamic tract.

Adaptation, Physiological↗
PubMed1991

Spermatogenesis in Hydra oligactis. II. How temperature controls the reciprocity of sexual and asexual reproduction.

Hydra oligactis undergo two mutually exclusive modes of reproduction: at warm temperatures (18-22 degrees C) animals reproduce asexually by budding, while at cold temperatures (10-12 degrees C) gamete differentiation occurs. Using a monoclonal antibody which is specific for cells of the sperm lineage, it was discovered that under conditions where sperm differentiation does not occur (18-22 degrees C), cells continually enter the sperm pathway but progression down the pathway is prematurely halted, effectively blocking the production of sperm. To elucidate the mechanism by which completion of sperm differentiation is controlled, the cell cycle times of interstitial cells entering the sperm pathway at both the restrictive (18 degrees C) and permissive (10 degrees C) temperatures were examined. It was envisaged that at the restrictive temperature the cell cycle times of committed cells would lengthen as they proceeded down the pathway, leading to dilution and eventual loss of cells at later stages of sperm differentiation. This did not occur. Although cells of the sperm lineage were found overall to divide more slowly at 18 degrees C than at 10 degrees C, at both temperatures the cell cycle times shortened as cells proceeded further down the pathway, making a dilution mechanism untenable. The effect of high temperature on the survival of cells was then tested by subjecting animals to a heat shock. Within 12 hr of the increase in temperature, the total number of sperm lineage interstitial cells dropped 10-fold while the total numbers of epithelial and somatic interstitial cells remained virtually unchanged. A distinct consequence of this cell loss was the disappearance of cells furthest down the sperm pathway. It is proposed that as cells move down the sperm pathway, they become increasingly sensitive to high temperature which adversely affects their survival; the higher the temperature, the earlier in the pathway cells die. The lethal effect is abolished by lowering the temperature, allowing sperm differentiation to continue to completion. The possible adaptive advantages of temperature controlling gametogenesis are discussed.

Adaptation, Physiological↗
PubMed1997

Postcranial evidence of cold adaptation in European Neandertals.

The low brachial and crural indices of the European Neandertals have long been considered indicative of cold adaptation. Recent work has documented lower limb/trunk ratios and deeper chests (anterior-posterior diameter) in European Neandertals than among their successors. The present study uses variables reflective of limb length, body mass and trunk height, and compares European Neandertals to 15 globally diverse recent human samples (1 "Eskimo," 3 North African, 4 sub-Saharan African and 7 European). Bivariate plots, as well as principal components analysis plots of log shape-transformed data, indicate that European Neandertals had an overall body shape that falls at the extreme end of modern higher latitude groups' range of variation. Cluster analysis (minimum spanning tree on a principal coordinates plot) indicates that the Neandertals are closest in body shape to modern "Eskimos," but even in this dendrogram, they are joined to the "Eskimo" via a long branch. In fact, it appears that European Neandertals were "hyperpolar" in body shape, likely due to two factors: 1) the extremely cold temperatures of glacial Europe and 2) less effective cultural buffering against cold stress.

Adaptation, Biological↗
PubMed1987

Influence of chemical and environmental stressors on acute cadmium toxicity.

Previous investigations have demonstrated that the cytosolic protein metallothionein (MT) is induced not only by exposure to certain heavy metals but also by a variety of other factors, including environmental stress. While MT synthesis has been observed with exposure to cold temperatures, there is a paucity of data concerning the influence of cold on heavy-metal toxicity. The present investigation focused on the influence of metal and cold pretreatments on the acute toxicity of cadmium. Mortalities of 80% and 100% were observed for mice orally administered challenge doses of 100 mg Cd/kg and 150 mg Cd/kg, respectively. To determine a protective cadmium pretreatment dose, animals were administered 2.5, 5, 10, 20, 25, and 50 mg Cd/kg 24 h prior to cadmium challenge. In animals pretreated with 10 mg Cd/kg, mortalities of 20% and 70% were observed with the respective challenge doses. Immediately following cold stress (4 degrees C, 12 h), mortalities of 30% and 90% were observed with cadmium challenge doses of 100 and 150 mg Cd/kg, respectively. Significant correlations were demonstrated between induced hepatic MT concentrations and cadmium pretreatment (r = 0.99), as well as cold pretreatment (r = 0.87). Results of this investigation indicate that stressors, such as cold, influence the acute toxicity of cadmium to the same magnitude as metal pretreatment. This induced tolerance to cadmium was attributed, in part, to the induction of MT synthesis. Furthermore, the induced levels of MT resulting from cold stress may confound the simplistic approach of using MT as a biological monitor of occupational exposure to cadmium.

Animals↗
PubMed2005

The BME3 (Blue Micropylar End 3) GATA zinc finger transcription factor is a positive regulator of Arabidopsis seed germination.

In many plant species, seed dormancy is broken by cold stratification, a pre-chilling treatment of fully imbibed seeds. Although the ecological importance of seed response to cold temperature is well appreciated, the mechanisms underlying the physiological changes during cold stratification is unknown. Here we show that the GATA zinc finger protein expressed in Arabidopsis seeds during cold stratification plays a critical role in germination. Characterization of an enhancer-trap population identified multiple lines that exhibited beta-glucuronidase (GUS) expression in the micropylar end of the seed (named Blue Micropylar End, BME lines). One of these lines, BME3, had a T-DNA insertion site in the 5' upstream region of a GATA-type zinc finger transcription factor gene (termed BME3-ZF). The BME3-ZF mRNA accumulated in seeds during cold stratification. Characterization of the BME3-ZF promoter indicated that this gene was activated specifically in the embryonic axis, which was still enclosed by the endosperm. The zinc finger gene knockout plants produced seeds exhibiting deeper dormancy, which showed reduced response to cold stratification. The ungerminated knockout seeds exhibited testa rupture, but failed to penetrate the endosperm layer. Application of gibberellic acid (GA3) rescued impaired germination of knockout seeds without cold stratification, indicating that the normal GA signal transduction pathway is present in the knockout mutants. Expression of GA20-oxidase and GA3-oxidase genes was greatly reduced in the knockout seeds, suggesting the potential involvement of the zinc finger protein in GA biosynthesis. These results suggest that the GATA zinc finger protein is a positive regulator of seed germination.

Amino Acid Sequence↗
PubMed1986

Cold exposure and mammary exchanges of circulating thyroxine and oestrone sulphate in the goat.

The effects of cold exposure on arterial and mammary venous concentrations of thyroxine and oestrone sulphate, and on mammary blood flow, were measured in goats during different stages of pregnancy and lactation. There were no significant differences in net mammary uptake of thyroxine in four non-pregnant lactating goats exposed for 30 h to cold (-3 +/- 2 degrees C) or control (20 +/- 2 degrees C) temperatures. Cold exposure for 30 h of six lactating goats (approximately 85 d pregnant) stimulated a net mammary release into the circulation of oestrone sulphate (mean 294 ng/min); plasma cortisol concentrations also increased. Cold exposure at approximately 30 d of pregnancy increased cortisol concentrations but had no effect on release of oestrone sulphate.

Animals↗
PubMed2001

[Cold shock in bacteria].

Various species and genera of bacterial show the same responses to low temperature. Cold induces cold shock genes, by causing significant changes in the regulation of protein synthesis. The synthesis of major proteins in the microbial cell is suppressed. However, there is synthesis of a great deal of new proteins, the so-called cold shock ones. The chief protein in this family is E. coli CspA that activates the translation of other cold shock genes and negatively regulates the expression of its own gene. E. coli CspA homologies were identified in many bacteria. They can be also identified in other microorganisms, including the pathogens of infectious diseases. This can be attributable to the presence of common antigens in different bacteria. The data presented should be borne in mind in identifying bacteria and in designing immunodiagnostic agents if there is a culture cooling stage in their technology.

Bacillus subtilis↗
PubMedDate not supplied

Gene expression in response to low temperatures in mammalian cells: a review of current ideas.

This review was undertaken to identify responses of mammalian cells to cold temperatures, such as might be encountered in therapeutic procedures where body temperatures are lowered, in preservation of cells and organs, and in cryopreservation. In general, cold elicits a range of stress responses through identified signaling pathways, which may determine the survival or otherwise of the cells. Under conditions of mild hypothermia, there is evidence for responses which reflect an ordered acclimation to the new environment, whilst deep cooling invokes a more generalised stress response.

Animals↗
PubMed1983

Low temperature inhibits bleomycin lung toxicity in the rat.

In order to see if exposure to cold temperature affects the development of bleomycin lung toxicity in mammals, 14 rats received endotracheal injections of bleomycin, while another 14 rats received saline. Half of the saline-treated animals were then exposed to room temperature for 7 days (SRT), and half were exposed to 4 degrees C for 7 days (SC). The bleomycin-treated animals similarly yielded groups kept at room temperature (BRT) and in the cold (BC). After 1 wk the rats were killed and the lungs were sectioned for assessment of histologic changes. All the bleomycin-treated animals had evidence of lung toxicity but this was much less marked in group BC than in group BRT. The lungs in group SC remained normal. These results were confirmed by morphometric methods, which showed significantly increased volume proportions of alveolar walls in groups BRT and BC compared with that in groups SRT and SC (p less than 0.001), with BRT being greater than BC (p less than 0.001). It is concluded that exposure of bleomycin-treated rats to low ambient temperature significantly reduces lung toxicity.

Animals↗