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PubMed1996

Tolerance of the cirrhotic liver to cold ischemia: ex vivo analysis in rats.

We investigated the viability of rat cirrhotic livers preserved cold using an isolated rat liver perfusion model. Cirrhosis was induced by intravenous thioacetamide injection. Normal and cirrhotic livers were reperfused immediately or following 6 h of preservation through the portal vein with Krebs-Henseleit buffer and hyaluronic acid added. Cirrhotic livers with short cold ischemia showed higher portal venous resistance than their normal counterparts (p < 0.05), while cirrhotic livers preserved for 6 h exhibited marked elevation of the portal venous resistance as compared with their fresh counterparts or normal liver preserved cold for 6 h (p < 0.05). Similarly, the oxygen consumption of cirrhotic livers with short cold preservation was lower than that of normal livers (p < 0.05), which was further reduced by 6 h of cold preservation (p < 0.05). The bile output was not different between normal and cirrhotic livers. The sinusoidal endothelial cell function of cirrhotic livers as assessed by the clearance of hyaluronic acid was impaired even after a short period of cold ischemia. Histologically, cirrhotic livers showed severe sinusoidal endothelial cell damage, hepatocellular swelling, and marked septal edema which became more prominent by cold preservation. We conclude that the viability of the cirrhotic liver is impaired even by a short cold exposure, and that the prolongation of cold ischemia of the cirrhotic liver leads to further deterioration of the viability.

Animals↗
PubMed1978

Thermal measurements on divers in hyperbaric helium-oxygen environments.

During a series of three saturation dives to simulated depths of 1000, 1200, and 1400 fsw at the Ocean Simulation Facility, measurements were made to establish the rate of heat loss of unclad divers in helium-oxygen gaseous environments. These measurements were part of a program to determine the dangers of cold stress and the temperature/time relationship tolerated by divers in cold diving bells or in hyperbaric chambers in which environmental conditions are uncontrolled. Three specific gaseous temperatures of 15, 20, and 25 degrees C were considered. In each experiment, as many as four subjects were monitored for body core and mean skin temperature over a 2-h testing period. One or two of the subjects were also monitored for mean body convective heat loss to determine physiological (shell) thermal insulation. Results of these experiments are expressed in depth-time-temperature three-dimensional graphs in whic, the temperature variable is one of the following: mean skin temperature change, mean body temperature change, or mean rectal (core) temperature change, each suitable for defining diver thermal limitations. It was also possible to rank body areas of the subjects in relation to heat loss and temperature decrease during exposure to the cold environment.

Adult↗
PubMed2002

Important roles of drought- and cold-inducible genes for galactinol synthase in stress tolerance in Arabidopsis thaliana.

Raffinose family oligosaccharides (RFO) accumulating during seed development are thought to play a role in the desiccation tolerance of seeds. However, the functions of RFO in desiccation tolerance have not been elucidated. Here we examine the functions of RFO in Arabidopsis thaliana plants under drought- and cold-stress conditions, based on the analyses of function and expression of genes involved in RFO biosynthesis. Sugar analysis showed that drought-, high salinity- and cold-treated Arabidopsis plants accumulate a large amount of raffinose and galactinol, but not stachyose. Raffinose and galactinol were not detected in unstressed plants. This suggests that raffinose and galactinol are involved in tolerance to drought, high salinity and cold stresses. Galactinol synthase (GolS) catalyses the first step in the biosynthesis of RFO from UDP-galactose. We identified three stress-responsive GolS genes (AtGolS1, 2 and 3) among seven Arabidopsis GolS genes. AtGolS1 and 2 were induced by drought and high-salinity stresses, but not by cold stress. By contrast, AtGolS3 was induced by cold stress but not by drought or salt stress. All the GST fusion proteins of GST-AtGolS1, 2 and 3 expressed in Escherichia coli had galactinol synthase activities. Overexpression of AtGolS2 in transgenic Arabidopsis caused an increase in endogenous galactinol and raffinose, and showed reduced transpiration from leaves to improve drought tolerance. These results show that stress-inducible galactinol synthase plays a key role in the accumulation of galactinol and raffinose under abiotic stress conditions, and that galactinol and raffinose may function as osmoprotectants in drought-stress tolerance of plants.

Acclimatization↗
PubMed2003

The cold-regulated transcriptional activator Cbf3 is linked to the frost-tolerance locus Fr-A2 on wheat chromosome 5A.

Wheat chromosome 5A plays a key role in cold acclimation and frost tolerance. The major frost tolerance gene Fr-A1(formerly Fr1) and two loci that regulate the transcription of cold- regulated genes (Cor) have previously been mapped on the long arm of this chromosome. In this study we report the discovery of a new locus for frost tolerance designated Fr-A2. This new locus was mapped on the long arm of chromosome 5A of diploid wheat (T. monococcum), 40 cM from the centromere and 30 cM proximal to the major frost tolerance locus Fr-A1. We found also that frost-tolerant and frost-susceptible T. monococcum parental lines differed in the transcription level of the cold induced gene Cor14b when plants were grown at 15 degrees C. Transcription levels of this gene were measured in each of the recombinant inbred lines and mapped as a QTL that perfectly overlapped the QTL for frost survival at the Fr-A2 locus. This result suggested that frost tolerance in this cross was mediated by differential regulation of the expression of the Corgenes. In a previous study in hexaploid wheat (T. aestivum) we had shown that Cor14b was regulated by two loci located on chromosome 5A, one in the same chromosome region as the T. monococcum Fr-A2 locus and the other one closely linked to Fr-A1. Since CBF transcriptional activators in Arabidopsis regulate Corgenes and are involved in frost tolerance, we decided to localize the cold-regulated CBF-like barley gene Cbf3 on the T. monococcum map. This gene was mapped on the peak of the Fr-A2 QTL for frost tolerance. This result suggests that the observed differential regulation of Cor14b at the Fr-A2 locus is due to allelic variation at the XCbf3 locus, and that this transcriptional activator gene might be a candidate gene for the Fr-A2 frost tolerance locus on wheat chromosome 5A.

Chromosome Mapping↗
PubMedDate not supplied

Seasonal metabolic acclimatization in mountain chickadees and juniper titmice.

Mountain chickadees and juniper titmice from northern Utah were examined to determine metabolic and body-composition characteristics associated with seasonal acclimatization. These species use behavioral adaptations and nocturnal hypothermia, which reduce energetic costs. These adjustments could reduce the need for extensive metabolic adjustments typically found in small passerines that overwinter in cold regions. In addition, these species live at higher altitudes, which may also decrease metabolic acclimatization found in birds. Winter birds tolerated colder test temperatures than summer birds. This improved cold tolerance was associated with an increase in maximal thermogenic capacity or summit metabolism (M(sum)). Winter M(sum) exceeded summer M(sum) by 26.1% in chickadees and 16.2% in titmice. Basal metabolic rates (BMR) were also significantly higher in winter birds compared with summer birds. Pectoralis wet muscle mass increased 33.3% in chickadees and 24.1% in titmice in winter and paralleled the increased M(sum) and BMR. Dry mass of contour plumage increased in winter for both species and was associated with decreased thermal conductance in winter chickadees compared to summer chickadees. Chickadees and titmice show metabolic acclimatization similar to other temperate species.

Acclimatization↗
PubMedDate not supplied

The role of NMDA receptors in neonatal cocaine-induced neurotoxicity.

The present study assessed the ability of N-methyl-D-aspartate (NMDA) receptor antagonist, dizocilpine (MK-801), to modulate neonatal cocaine-induced neurobehavioral changes in the rat. Sprague-Dawley rats were randomly assigned on postnatal day 0 (PND 0) to one of four treatment groups. Treatments began on PND 4 and continued until PND 10. Treatments consisted of an oral bolus of either cocaine HCl (40 mg/kg), (+)MK-801 (0.4 mg/kg), (+)MK-801 (0.4 mg/kg) followed 30 min later with cocaine HCl (40 mg/kg) or 0.9% saline. On PND 21, 30, 40 and 60, males and females were examined for stress response using the cold-water swim test. Cocaine-treated male and female rats exhibited significantly diminished tolerance to cold-water stress compared to control and MK-801/cocaine-treated groups. In addition, neonatal exposure to cocaine was associated with increased severity of motor symptoms (tail twitches, wet dog shaking and convulsions) following the administration of NMDA (35 mg/kg). Treatment groups were also tested for pain sensitivity using the tail flick (TF) and hot plate (HP) methods. The results indicated that neonatal cocaine exposure altered pain sensitivity in both tests. NMDA receptor binding studies showed a significant increase in receptor densities in the hippocampus and hypothalamus of the cocaine-treated group compared to control. MK-801 administered to rat pups before cocaine treatment blocked the increase in receptor density. The results indicated that neonatal cocaine exposure was associated with altered responses to NMDA, stress tolerance and pain sensitivity. Moreover, the pretreatment with NMDA receptor antagonist, MK-801, abolished or attenuated these cocaine-induced neurobehavioral changes.

Adrenocorticotropic Hormone↗
PubMed2001

Cold acclimation increases basal heart rate but decreases its thermal tolerance in rainbow trout (Oncorhynchus mykiss).

Rainbow trout (Oncorhynchus mykiss, Walbaum) were acclimated to 4 degrees C and 17 degrees C for more than 4 weeks and heart rate was determined in the absence and presence of adrenaline to see how thermal adaptation influences basal heart rate and its beta-adrenergic control in a eurythermal fish species. The basal heart rate in vitro was higher in cold-acclimated than warm-acclimated rainbow trout at temperatures below 17 degrees C. On the other hand, adaptation to cold decreased thermal tolerance of heart rate so that the maximal heart rates were achieved at 17 degrees C (75 +/- 4 bpm) and 24 degrees C (88 +/- 2 bpm) in cold-acclimated and warm-acclimated trout, respectively. Beta-adrenergic response of the heart was enhanced by cold-adaptation, since adrenaline (100 nmol l(-1)) caused stronger stimulation of heart rate in cold-acclimated (29 +/- 14%) than in warm-acclimated fish (10 +/- 1%; P = 0.03). Furthermore, adrenaline strongly opposed the temperature-dependent deterioration of force production in cold-acclimated trout but not in warm-acclimated trout. The results indicate that adaptation to cold increases basal heart rate but decreases its thermal tolerance in rainbow trout. Cold acclimation up-regulates the beta-adrenergic system, and beta-adrenoceptor activation seems to provide cardioprotection against high temperatures in the cold-adapted rainbow trout.

Acclimatization↗
PubMedDate not supplied

Psychological and psychophysiological factors in prevention and treatment of cold injuries.

Cold injured patients in Alaska come from many sources. Although sport and work continues to provide large numbers of cold injured, most severe repeat injuries tend to reflect other biopsychosocial consequences. Certain behaviors can increase the probability of injury, however all persons living in cold climates are potential candidates. One can decrease risk by education, knowledge and intelligent behavior. Proper respect for adequate protection and hydration seem to be critical factors. Understanding the psychological, physiological and psychophysiological aspects of the cold environment performer helps refine the prevention and treatment strategies for cold injury. Skill training with bio-behavioral methods, such as thermal biofeedback, and the value of medical psychotherapy appear to offer continued promise by facilitating physiologic recovery from injury, as well as assisting in long term rehabilitation. Both approaches increase the likelihood of a favorable healing response by soliciting active patient participation. Medical Psychotherapy for traumatic injuries can also help identify and manage cognitive emotional issues for families and patients faced with the permanent consequences of severe thermal injuries. Thermal biofeedback therapy has the potential benefit of encouraging greater self-reliance and responsibility for self-regulating overall health by integrating self-management skills regarding physiology, diet and lifestyle. Inpatient and outpatient biofeedback training offers specific influence over vascular responses for healing, as well as providing an effective tool for pain management. Interest in cold region habitation has continued to expand our study of human tolerance to harsh, extreme environments. Biological, psychological, sociological, and anthropological views on adaptation, habituation, acclimatization, and injury in cold environments acknowledges the role of development, learning and educated responses to cold environments. The study of health, performance, and injury prevention in extreme isolated cold environments has important strategic and scientific implications. What is learned from behavioral studies of cold survival provides an opportunity to increase our scientific knowledge and understanding. These cold research findings can assist in our future exploration of cold, underwater farming at great depths, and to far distance space travel to cold planets. The relatively new research frontier "Polar Psychology" has evolved to study how interactions with cold environments can have both positive and/or negative consequences. This research simulates the psychological factors likely to be encountered while exploring isolated cold regions of distant galaxies. The psychological and psychophysiological correlates of cold experience appear to be a function of four interactive issues: the environment, genetic predisposition, learning or experience, and finally perception or cognition. Individual cold tolerance seems to relate heavily on sensation, perception and behavior.(ABSTRACT TRUNCATED AT 400 WORDS)

Acclimatization↗
PubMed2002

Cold-regulated cereal chloroplast late embryogenesis abundant-like proteins. Molecular characterization and functional analyses.

Cold acclimation and freezing tolerance are the result of complex interaction between low temperature, light, and photosystem II (PSII) excitation pressure. Previous results have shown that expression of the Wcs19 gene is correlated with PSII excitation pressure measured in vivo as the relative reduction state of PSII. Using cDNA library screening and data mining, we have identified three different groups of proteins, late embryogenesis abundant (LEA) 3-L1, LEA3-L2, and LEA3-L3, sharing identities with WCS19. These groups represent a new class of proteins in cereals related to group 3 LEA proteins. They share important characteristics such as a sorting signal that is predicted to target them to either the chloroplast or mitochondria and a C-terminal sequence that may be involved in oligomerization. The results of subcellular fractionation, immunolocalization by electron microscopy and the analyses of target sequences within the Wcs19 gene are consistent with the localization of WCS19 within the chloroplast stroma of wheat (Triticum aestivum) and rye (Secale cereale). Western analysis showed that the accumulation of chloroplastic LEA3-L2 proteins is correlated with the capacity of different wheat and rye cultivars to develop freezing tolerance. Arabidopsis was transformed with the Wcs19 gene and the transgenic plants showed a significant increase in their freezing tolerance. This increase was only evident in cold-acclimated plants. The putative function of this protein in the enhancement of freezing tolerance is discussed.

Acclimatization↗
PubMed1998

Pain tolerance in opioid addicts on and off naltrexone pharmacotherapy: a pilot study.

Under certain experimental and clinical conditions, opioid antagonists have been demonstrated to have analgesic properties. In this open-label, nonrandomized, within-subject comparison, the effect of chronic treatment with the antagonist, naltrexone, on tolerance for experimental pain was evaluated in a small sample of male opioid addicts (N = 10) receiving naltrexone maintenance. Cold-pressor pain tolerance was measured during (> or = 6 weeks) and after discontinuation (> or = 1 week) of naltrexone treatment. Intra-subject comparison revealed that eight of the ten subjects were more pain tolerant (median + 20 sec) while receiving naltrexone. It is suggested that either midbrain opioid system upregulation in the presence of naltrexone or underlying individual differences in pain tolerance in persons with addictive disease provide potential explanations for these findings.

Adolescent↗
PubMed1997

Cold pressor pain: comparing responses of juvenile arthritis patients and their parents.

UNLABELLED: The objective of this study was to compare the reactions to experimental cold pressor pain of Juvenile Arthritis (JA) patients, healthy children, and their parents. METHODS: We compared pain threshold, discomfort, intensity, and tolerance to experimental cold pressor pain in 15 JA patients (age 9-15) and one of their parents and a control group of 25 healthy children (age 9-12) and one of their parents. RESULTS: JA-patients exhibited significantly lower mean pain tolerance than healthy children. Pain tolerance correlated significantly with disease duration. Parents of JA-patients showed significantly greater mean pain intensity than parents of healthy children, and had higher estimates of their child's ability to endure pain than parents of healthy children. Correlations were found between pain scores of children and their parents for both pain intensity and tolerance. The pain coping category of Catastrophizing was associated with several of the experimental pain response measures. CONCLUSION: The results suggest that JA patients may differ from healthy children with regard to their responses to experimental pain, and that pain responses of both JA patients and healthy children could be related to the pain response of their parents.

Adolescent↗
PubMed1998

Evidence for the cell wall involvement in temporal changes in freezing tolerance of Jerusalem artichoke (Helianthus tuberosus L.) tubers during cold acclimation.

We studied the mechanism of cold acclimation of Jerusalem artichoke (Helianthus tuberosus L.) tubers with special reference to the role of the cell wall. During the cold-acclimation process from September to January, the freezing tolerance of tubers increased from -2.8 degrees C to -8.4 degrees C (LT50). By contrast, the isolated protoplasts constitutively showed a consistent high level of freezing tolerance (LT50; below -25 degrees C) throughout the period. In tuber tissues, freezing injury was effectively protected by the external addition of isotonic solutions. Cryomicroscopic observations revealed that tissue cells mounted in isotonic solutions plasmolyzed upon freezing; tissue cells mounted in water collapsed with a tight attachment of plasma membrane to the cell wall. Upon freezing of intact tissues in water to temperatures below the critical range, the cytoplasm was irreversibly acidified as revealed by a fluorescence pH-ratiometry, suggesting that occurrence of detrimental cellular events leading to permanent cell injury. The freeze-induced acidification of cytoplasm was also effectively prevented by the external addition of isotonic solutions. These results suggest that the tight attachment of the plasma membrane to the cell wall during freezing may have a harmful effect on cells, in particular on the plasma membrane, possibly due to mechanical or some sort of chemical/ physico-chemical interaction with the cell wall.

Acclimatization↗
PubMed1990

Relationship between Freezing Tolerance of Root-Tip Cells and Cold Stability of Microtubules in Rye (Secale cereale L. cv Puma).

The response of cortical microtubules to low temperature and freezing was assessed for root tips of cold-acclimated and non-acclimated winter rye (Secale cereale L. cv Puma) seedlings using indirect immunofluorescence microscopy with antitubulin antibodies. Roots cooled to 0 or -3 degrees C were fixed for immunofluorescence microscopy at these temperatures or after an additional hour at 4 degrees C. Typical arrays of cortical microtubules were present in root-tip cells of seedlings exposed to the cold-acclimation treatment of 4 degrees C for 2 days. Microtubules in these cold-acclimated cells were more easily depolymerized by a 0 degrees C treatment than microtubules in root-tip cells of nonacclimated, 22 degrees C-grown seedlings. Microtubules were still present in some cells of both nonacclimated and cold-acclimated roots at 0 and -3 degrees C; however, the number of microtubules in these cells was lower than in controls. Microtubules remaining during the -3 degrees C freeze were shorter than microtubules in unfrozen control cells. Repolymerization of microtubules after both the 0 and -3 degrees C treatments occurred within 1 h. Root tips of nonacclimated seedlings had an LT-50 of -9 degrees C. Cold acclimation lowered this value to -14 degrees C. Treatment of 22 degrees C-grown seedlings for 24 h with the microtubule-stabilizing drug taxol caused a decrease in the freezing tolerance of root tips, indicated by a LT-50 of -3 degrees C. Treatment with D-secotaxol, an analog of taxol that was less effective in stabilizing microtubules, did not alter the freezing tolerance. We interpret these data to indicate that a degree of depolymerization of microtubules is necessary for realization of maximum freezing tolerance in root-tip cells of rye.

Journal Article↗
PubMed1989

Normative model for cold pressor test.

The cold pressor test elicits an emotional/motivational pain experience from the immersion of a limb in cold water. It has been widely used to evaluate (experimental and chronic) pain. However, normative models for quantification and comparison for pain tolerance have not previously been established. This study developed a normative mathematical model for pain tolerance using the cold pressor test with over 600 subjects. Norms for age, sex, and ethnic group were calculated. In addition, chronic pain patients were compared with pain-free patients to determine normative differences in response. The results indicate that at any given age Anglo-Saxon males have the longest tolerance time followed by non-Anglo-Saxon males, Anglo-Saxon females, and finally non-Anglo-Saxon females. There is a consistent decrease in tolerance time as the male age increases and minimal change in tolerance time as the female age increases. Chronic pain patients exhibited the same type of pain response pattern as healthy volunteers when corrected for age, sex, and ethnocultural subgroup.

Adolescent↗