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PubMed2001

Effect of sequential cold shocks on survival and molting incidence in Panstrongylus megistus (Burmeister) (Hemiptera, Reduviidae).

The survival and molting incidence were studied in the insect, Panstrongylus megistus, following sequential cold shocks in which a milder shock at 0 or 5 degrees C for 1 h preceded a more severe shock (0 degrees C, 12 h). The shocks were separated by intervals of 8, 18, 24, and 72 h at 28 degrees C. The survival rate after sequential shocks was identical to that of unshocked controls. Cold-shock tolerance differed from heat-shock tolerance since the latter varied with the time between shocks and was much more transient. Sequential cold shocks produced a higher molting incidence when the first shock was given at 0 compared to 5 degrees C. This response was more rapid than that to sequential heat shocks. Cold-shock tolerance in P. megistus may involve heat-shock proteins, although other protective mechanisms may also occur concurrently. This is the first report of cold-shock tolerance in a blood-sucking hemipteran.

Animals↗
PubMed1987

Adaptation to extreme ambient temperatures in cold-acclimated gerbils and mice.

To explain tolerance of heat and cold in gerbils (Gerbillus campestris) in their natural environment, a comparative study was made of thermoregulatory reactions in these animals and white mice (Mus musculus) of the same body mass exposed for 2-3 h to ambient temperatures (Ta) ranging from -23 to 40 degrees C. Metabolic rate (MR), evaporative heat loss (EHL), colonic temperature (Tb), and electromyographic activity (EMG) were measured. Nonshivering thermogenesis (NST) was also evaluated from the increase in MR after norepinephrine injection. In gerbils, tolerance of cold was higher than in mice; there was no fall in Tb in cold-acclimated (CA) and control (TN) gerbils after 3 h of exposure at -20 and -10 degrees C Ta, respectively; peak MR (PMR) reached five to six times resting MR (RMR) in gerbils and four to five times in mice. In gerbils, RMR was 35% below that of mice. In TN gerbils, EHL did not increase before 38 degrees C Ta; EHL increased at 26 degrees C in mice. In both animals, cold acclimation increased cold tolerance, PMR, RMR, and NST. Low RMR, high Tb, and mainly burrowing habits preserve gerbils from overheating and save water in hot and arid environments, and a conspicuous tolerance of cold allows them to live and forage in the wild during the cold night.

Acclimatization↗
PubMed1997

Transformation of Arabidopsis thaliana with the codA gene for choline oxidase; accumulation of glycinebetaine and enhanced tolerance to salt and cold stress.

Glycinebetaine is one of the compatible solutes that accumulate in the chloroplasts of contain halotolerant plants when these plants are exposed to salt or cold stress. The codA gene for choline oxidase, the enzyme that converts choline into glycinebetaine, has previously been cloned from a soil bacterium, Arthrobacter globiformis. Transformation of Arabidopsis thaliana with the cloned codA gene under the control of the 35S promoter of cauliflower mosaic virus enabled the plant to accumulate glycinebetaine and enhanced its tolerance to salt and cold stress. At 300 mM NaCl, considerable proportions of seeds of transformed plants germinated well, whereas seeds of wild-type plants failed to germinate. At 100 mM NaCl, transformed plants grew well whereas wild-type plants did not do so. The transformed plants tolerated 200 mM NaCl, which was lethal to wild-type plants. After plants had been incubated with 400 mM NaCl for two days, the photosystem II activity of wild-type plants had almost completely disappeared, whereas that of transformed plants remained at more than 50% of the original level. When exposed to a low temperature in the light, leaves of wild-type plants exhibited symptoms of chlorosis, whereas those of transformed plants did not. These observations demonstrate that the genetic modification of Arabidopsis thaliana that allowed it to accumulate glycinebetaine enhanced its ability to tolerate salt and cold stress.

Acclimatization↗
PubMed1976

[Relationship between temperatures behavior following short-term exposure of fingers to heat and cold and various anthropometric index values. Contribution on the problem of temperature regulation in man].

On a sample of n=201 male students between 18 and 30 years cold resp. heat tolerance tests were carried out in order to examine, how far correlations to anthropometric traits are present. No correlation between body height and heat resp. cold tolerance were found. Against that body weight, ROHRER-Index, subcutaneous fat tissue, weight/surface-ratio and surface/weight-ratio showed marked correlations with variations in body temperature. Particularly in the cold tolerance test more heavy and fatty individuals were characterist by a greater ability to store body heat as the decrease of temperature in them was obviously lower. The anthropological significance of these observations is discussed.

Adolescent↗
PubMed1984

An improved cold stress test for aging mice.

Tolerance to cold stress is a simple and reliable test which can be used longitudinally to study age-related differences or changes in thermoregulation of C57BL/6J mice. Neither prior food deprivation nor permanently inserted thermoprobes are necessary conditions for eliciting reliable age differences. However, restraint during the test is important and does elicit reliable age differences.

Aging↗
PubMed1998

The role of prior pain experience and expectancy in psychologically and physically induced pain.

Cognitive theories regarding symptom formation suggest that environmental factors such as warnings of impending pain and earlier experiences with pain can lead to a cognitive schema in which pain is selectively monitored. This study evaluated the role of prior experience with pain in the development of expectancy induced somatoform pain. Subjects from two experimental groups were connected to a sham stimulator and told to expect a headache. One of these groups, the physical stimulation first group, was exposed to pain induction by ice water and by pressure prior to the sham stimulation. A second group, the sham stimulation first group, received the sham stimulation followed by the cold water and pressure pain induction techniques. Subjects in the physical stimulation first group showed significant increases in their pain reports as settings on the sham stimulator were increased. Significant increases were not noted in the sham stimulation first group. The two groups did not differ in the number of subjects reporting pain or the mean maximal pain reported during the sham stimulation. Duration of cold water tolerance and the time until the analgesic threshold level for cold water were significantly shorter in subjects who had the sham stimulation first. This study suggests that prior pain can influence the reactivity to external suggestion for pain but does not increase the frequency of pain reports. It does suggest that the selective monitoring induced during the sham stimulation may influence later pain behaviours as was seen during the cold water tolerance testing.

Adult↗
PubMed2006

Validation of a green fluorescent protein-labeled strain of Vibrio vulnificus for use in the evaluation of postharvest strategies for handling of raw oysters.

In this paper we describe a biological indicator which can be used to study the behavior of Vibrio vulnificus, an important molluscan shellfish-associated human pathogen. A V. vulnificus ATCC 27562 derivative that expresses green fluorescent protein (GFP) and kanamycin resistance was constructed using conjugation. Strain validation was performed by comparing the GFP-expressing strain (Vv-GFP) and the wild-type strain (Vv-WT) with respect to growth characteristics, heat tolerance (45 degrees C), freeze-thaw tolerance (-20(o) and -80 degrees C), acid tolerance (pH 5.0, 4.0, and 3.5), cold storage tolerance (5 degrees C), cold adaptation (15 degrees C), and response to starvation. Levels of recovery were evaluated using nonselective medium (tryptic soy agar containing 2% NaCl) with and without sodium pyruvate. The indicator strain was subsequently used to evaluate the survival of V. vulnificus in oysters exposed to organic acids (citric and acetic acids) and various cooling regimens. In most cases, Vv-GFP was comparable to Vv-WT with respect to growth and survival upon exposure to various biological stressors; when differences between the GFP-expressing and parent strains occurred, they usually disappeared when sodium pyruvate was added to media. When V. vulnificus was inoculated into shellstock oysters, the counts dropped 2 log(10) after 11 to 12 days of refrigerated storage, regardless of the way in which the oysters were initially cooled. Steeper population declines after 12 days of refrigerated storage were observed for both iced and refrigerated products than for slowly cooled product and product held under conservative harvest conditions. By the end of the refrigeration storage study (22 days), the counts of Vv-GFP in iced and refrigerated oysters had reached the limit of detection (10(2) CFU/oyster), but slowly cooled oysters and oysters stored under conservative harvest conditions still contained approximately 10(3) and >10(4) CFU V. vulnificus/oyster by day 22, respectively. The Vv-GFP levels in the oyster meat remained stable for up to 24 h when the meat was exposed to acidic conditions at various pH values. Ease of detection and comparability to the wild-type parent make Vv-GFP a good candidate for use in studying the behavior of V. vulnificus upon exposure to sublethal stressors that might be encountered during postharvest handling of molluscan shellfish.

Animals↗
PubMed1997

Cold Acclimation and Freezing Tolerance (A Complex Interaction of Light and Temperature).

By comparing growth under five different temperature and irradiance regimes (20[deg]C and 800, 250, and 50[mu]mol m-2 s-1 and 5[deg]C and 250 and 50 [mu]mul m-2 s-1), we have examined the effects of light, temperature, and the relative reduction state of photosystem II on plant morphology, freezing tolerance (lethal temperature at which freezing injury occurs [LT50]), transcript levels of Lhcb and two cold-stimulated genes (Wcs19 and Wcs120), and photosynthetic adjustment in winter rye (Secale cereale L. cv Musketeer). We show, for the first time to our knowledge, that in addition to adjustments in photosynthetic capacity, nonphotochemical quenching capacity and tolerance to photoinhibition, the accumulation of the cold-induced transcript Wcs19, and the compact plant morphology usually associated with cold-hardening are correlated with the relative reduction state of photosystem II rather than with growth temperature or growth irradiance per se. In contrast, the acquisition of maximal LT50, as well as Lhcb and Wcs120 mRNA accumulation, appears to be dependent on both growth temperature and growth irradiance but in an independent, additive manner. The results are discussed with respect to the possible role of the modulation of chloroplastic redox poise in photosynthetic acclimation to cold-hardening temperatures and the attainment of maximal LT50.

Journal Article↗
PubMed2005

[Effects of cold-hardening on freezing tolerance and antioxidant enzyme activities in plantlets of Saussurea laniceps Hand.-Mazz].

Living conditions for plants in the mountains become increasingly less favorable with increasing altitude. In the alpine region, the plants are commonly exposed to daily rather than seasonal temperature fluctuations and by frequent freezing temperature. To elucidate the freezing tolerance mechanism of alpine plants, Saussurea laniceps Hand.-Mazz. was used as a model plant. It is a perennial herbal plant distributed in alpine regions of Yunnan and Tibet of China. It can survive on mountains with elevations over 4000 m. Wild S. laniceps plants are propagated only by seeds in the alpine areas. Micropropagation of S. laniceps through seed was a desirable method to get enough seedlings for freezing research. Micropropagation through plantlets derived from germinated S. laniceps seeds collected from Tibet was achieved successfully. Activities of antioxidant enzyme and solute contents were investigated in plantlets of S. laniceps. Freezing tolerance in plantlets increased after 7 or 15 d of cold-hardening (Table 1). Cold-hardening (2 degrees C) increased the activities of SOD, peroxidase, and catalase (Fig.1) in plantlets. A similar increase was also observed in the protein and proline content (Fig.1), whereas soluble carbohydrates changed little (Fig.1). These results obtained suggest that the higher activities of SOD, peroxidase, and catalase, as well as the higher protein and proline content may be biochemical adaptation for freezing toleranc in cold-hardened S. laniceps plantlets. Interestingly, deacclimation was slow; even after the plants were placed again under a temperature of 21-23 degrees C for 5 d, the higher freezing hardiness, enzyme activities, protein and proline content acquired after cold acclimation remained. In conclusion, our plantlet cultures have proved to be good materials for experimentation on freezing resistance in study of freezing-resistance mechanism in the alpine plant S. laniceps.

Adaptation, Physiological↗
PubMed1988

Heat shock protection against cold stress of Drosophila melanogaster.

Heat shock protein synthesis can be induced during recovery from cold treatment of Drosophila melanogaster larvae. Survival of larvae after a cold treatment is dramatically improved by a mild heat shock just before the cold shock. The conditions which induce tolerance to cold are similar to those which confer tolerance to heat.

Acclimatization↗
PubMed1983

Interactions of cold exposure and starvation on glucose tolerance and insulin response.

The metabolic interactions of cold exposure, cold acclimation, and starvation on glucose tolerance and plasma insulin levels were studied in precannulated, unrestrained, and unanesthetized rats. Cold exposure (48 h at 5 degrees C) significantly reduced the insulin response to intravenous glucose injection (P less than 0.01) while improving glucose tolerance (P less than 0.01). Starvation (48 h at 25 degrees C) also reduced the insulin response (P less than 0.01) but did not significantly alter glucose tolerance. "Accelerated starvation" induced by starving rats for 48 h at 5 degrees C dramatically reduced both basal and glucose-stimulated insulin levels while even improving glucose tolerance, resulting in a 15-fold reduction in the insulinogenic index. Cold acclimation (3 wk at 5 degrees C) induced essentially the same alterations as cold exposure. Approximately reversed changes were observed when cold-acclimated rats were returned to a warm environment for 15-18 h. Results from these studies indicate that 1) cold exposure and starvation, but not cold acclimation, act synergistically in decreasing the sensitivity and/or the capacity of pancreatic islets for secreting insulin in response to glucose stimulation; 2) glucose tolerance and possibly insulin sensitivity of peripheral tissues are enhanced by cold exposure and starvation, although glucose tolerance is improved by cold exposure only, not by starvation; 3) an improved glucose tolerance with barely detectable plasma insulin levels was obtained in cold-starved rats under normal physiological conditions.

Acclimatization↗
PubMed1981

Morphine, experimental pain, and psychological reactions.

This study examines the effects of morphine (10 mg/70 kg body weight) versus placebo (isotonic saline) on experimentally induced cold pressor pain threshold and tolerance, on self-reports of psychological states and drug effects, observer ratings of psychological states, and performance on timed cognitive-motor tasks in 20 non-drug using, normal male volunteers (21-28 years of age). Morphine increased both threshold and tolerance for cold pressor pain, and also increased "euphoric" and decreased "clear thinking" responses on the respective scales. Morphine, in contrast to placebo, increased scores on depression, fatigue, and cognitive loss-dysfunction scales and decreased scores on carefree and "friendliness" scales. Three sets of psychological variables were observed to covary significantly: Measures of anxiety and hostility; reports of fatigue and cognitive dysfunction; and reports of carefree feelings and perceptions of clear thinking. While measures of hostility, fatigue, and cognitive dysfunction covaried positively, reports of carefree feelings and perception of clear thinking covaried negatively with increased pain threshold and tolerance. Anxiety, contrary to reports in the literature, also covaried positively with the pain measures. The results were interpreted as supporting a relationship between increased arousal of the nervous system and decreased pain sensitivity in conjunction with the known analgesic effects of morphine.

Adult↗
PubMed2005

Ischemic preconditioning and liver tolerance to warm or cold ischemia: experimental studies in large animals.

BACKGROUND: In the rodent, ischemic preconditioning (IPC) has been shown to improve the tolerance of the liver to ischemia-reperfusion under normothermic or hypothermic conditions. The aim of the present study was to test this hypothesis in a dog model, which may be more relevant to the human. METHODS: Beagle dogs were used in two distinct animal models of hepatic warm ischemia and orthotopic liver transplantation (hypothermic ischemia). IPC consisted of 10 minutes of ischemia followed by 10 minutes of reperfusion. In the first model, livers were exposed to 55 minutes prolonged warm ischemia and reperfused for 3 days (n = 6). In the second model, livers were retrieved and preserved for 48 hours at 4 degrees C in University of Wisconsin solution, transplanted, and reperfused without immunosuppression for 7 days (n = 5). In each model, nonpreconditioned animals served as controls (n = 5 in each group). Also, isolated dog hepatocytes were subjected to warm and cold storage ischemia-reperfusion to model the animal transplant studies using IPC. RESULTS: In the first model (warm ischemia), IPC significantly decreased serum aminotransferase activity at 6 and 24 hours post-reperfusion. After 1 hour of reperfusion, preconditioned livers contained more adenosine triphosphate and produced more bile and less myeloperoxidase activity (neutrophils) relative to controls. In the second model (hypothermic preservation), IPC was not protective. Finally, IPC significantly attenuated hepatocyte cell death after cold storage and warm reperfusion in vitro. CONCLUSIONS: IPC is effective in large animals for protecting the liver against warm ischemia-reperfusion injury but not injury associated with cold ischemia and reperfusion (preservation injury). However, the IPC effect observed in isolated hepatocytes suggests that preconditioning for preservation is theoretically possible.

Adaptation, Physiological↗
PubMed1993

Cold-Induced Changes in Freezing Tolerance, Protein Phosphorylation, and Gene Expression (Evidence for a Role of Calcium).

The role of Ca2+ in cold-induced changes in protein phosphorylation, gene expression, and development of freezing tolerance has been studied in cell-suspension cultures of a freezing-tolerant cultivar of alfalfa (Medicago sativa spp. falcata cv Anik). Chemical treatments to block Ca2+ channels, antagonize calmodulin action, or inhibit protein kinases markedly inhibited the cellular capacity to develop cold-induced freezing tolerance but had little effect on cell viability. An analysis of phosphoprotein profile by two-dimensional polyacrylamide gel electrophoresis revealed that at low temperature the relative level of phosphorylation of several proteins increased, whereas that of several others decreased. When cold acclimation was carried out in the presence of N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide hydrochloride, an antagonist of calmodulin and Ca2+-dependent protein kinases, or the Ca2+ channel blocker La3+, the cold-induced changes in protein phosphorylation were strongly inhibited, cells lost their capacity to develop freezing tolerance, and accumulation of transcripts of cold acclimation-specific genes was substantially reduced. An inhibitor of protein kinases, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride, had less pronounced effects on the cold-induced protein phosphorylation and caused only a partial inhibition of the cold-induced development of freezing tolerance and accumulation of the transcripts. The level of phosphorylation of one protein, of about 15 kD, increased more than 10-fold at low temperature and showed a strong positive correlation with cold-induced freezing tolerance and gene expression even when the latter were altered with various chemical treatments. These results suggest that Ca2+ and protein phosphorylation, or perhaps a coupling of the two, play an important role during the acquisition of freezing tolerance during cold acclimation.

Journal Article↗
PubMed1984

Intermittent cold water stress-analgesia in rats: cross-tolerance to morphine.

Continuous cold water swim ( CCWS , 3.5 min, 2 degrees C) induces a non-opiate type of analgesia since 14 mg/kg of naltrexone or 20 mg/kg of naloxone only partially antagonize this stress-induced analgesia (SIA) and since there is no cross-tolerance between CCWS and morphine-analgesia. Intermittent cold water swim ( ICWS ) analgesia is significantly antagonized by naltrexone (14 mg/kg). These studies suggested that CCWS -analgesia is mediated by non-opioid systems, while ICWS -analgesia acts through a system that also mediates morphine analgesia. The hypothesis that ICWS -analgesia shares a common opioid pathway with morphine-analgesia, but not with CCWS -analgesia, was further tested by cross-tolerance studies in rats. The results showed a complete cross-tolerance to morphine analgesia in ICWS -tolerant animals,, but no cross-tolerance in animals. This suggests that morphine- and ICWS -analgesia partially share a common pathway, ICWS acting probably at levels "downstream" from the opiate-sensitive site, while CCWS induces analgesia by acting on a different system which is not mediated by opioids.

Analgesia↗