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PubMed1998

Biological ice nucleation and ice distribution in cold-hardy ectothermic animals.

For many ectotherms, overwintering survival depends on the avoidance or regulation of ice nucleation and growth within their body fluids. Freeze avoidance via supercooling plays an important role in the cold hardiness of many small species, particularly terrestrial arthropods, that do not survive the freezing of their body fluids. In contrast, mechanisms that limit supercooling and initiate freezing at relatively high temperatures promote survival of the few invertebrates and vertebrates that tolerate freezing. These mechanisms include inoculative freezing, which results from contact with ice in the environment, and various ice nucleating proteins, microbes, and crystalloid compounds. In freeze-tolerant ectotherms, cold hardiness is influenced by complex, seasonally changing interactions among physiological factors, ice nucleators, and the physical microenvironment. Extraorgan sequestration of ice is a major adaptation of freeze tolerance. For most freeze-tolerant species, ice growth is primarily restricted to extracellular compartments; however, intracellular freezing also occurs in some species.

Adaptation, Physiological↗
PubMed2004

Heterosis in the freezing tolerance of crosses between two Arabidopsis thaliana accessions (Columbia-0 and C24) that show differences in non-acclimated and acclimated freezing tolerance.

Heterosis is broadly defined as the increased vigour of hybrids in comparison to their parents. In the model plant Arabidopsis thaliana, a significant heterosis effect on leaf-freezing tolerance was observed in the F(1) generation of a cross between the accessions Columbia-0 (Col) and C24. Parental Col plants were significantly more freezing-tolerant than C24 plants in both the acclimated and non-acclimated (NA) states. Mid-parent heterosis was observed in the F(1) plants, both in the basic tolerance of non-adapted plants and in freezing tolerance after cold acclimation. Best-parent heterosis, on the other hand, was only found after cold acclimation. The heterosis effect was reduced in the F(2) populations such that only mid-parent heterosis was evident. The leaf content of soluble sugars (fructose (Fru), glucose (Glc), sucrose (Suc) and raffinose (Raf)) increased dramatically in the F(1) plants after cold acclimation as compared to the parental lines. The content of proline (Pro), however, was only moderately increased in the F(1) plants under the same conditions. Correlation analyses showed that only Raf content was consistently related to leaf-freezing tolerance in both the acclimated and NA states. A quantification of mRNA levels in leaves of parental and F(1) lines using quantitative real-time RT-PCR showed no clear indication for an involvement of the investigated genes (CBF (C-repeat binding factor)1, CBF2, (cold-regulated protein (COR) 6.6, COR15a, COR15b, COR47 and COR78) in the heterosis effect.

Acclimatization↗
PubMed1983

Experimental pain measurement in patients with asymptomatic myocardial ischemia.

Men with substantial coronary heart disease determined angiographically and with reproducible myocardial ischemia were studied. During exercise electrocardiography, 22 patients exhibited significant ST segment depression with concomitant angina pectoris (that is, symptomatic myocardial ischemia) and 20 patients demonstrated significant ST segment depression without any symptoms (that is, asymptomatic myocardial ischemia). No significant differences were found between the patient groups in functional variables, coronary angiographic data or coronary risk factors. In contrast, various experimental pain measures (for example, electrical pain threshold, according to Notermans' method, cold pressor test and tourniquet pain test) yielded significant differences between groups. Results indicate that patients with asymptomatic myocardial ischemia demonstrated significantly higher electrical pain thresholds and ischemic pain thresholds, as well as more tolerance to cold and ischemia, so that individual differences in sensibility to pain may partly explain lack of pain in patients with asymptomatic myocardial ischemia.

Angiography↗
PubMed1991

When does a choice of coping strategies help? The interaction of choice and locus of control.

Undergraduate student volunteers either were given a choice of coping strategies or were assigned to a coping strategy which was used to help them tolerate the cold pressor. Subjects who were given a choice of coping strategies reported their strategy to be more credible and perceived a greater sense of control than subjects who were not given a choice. Improved pain tolerance, however, did not result directly from being given a choice. Increases in pain tolerance depended on locus of control. Subjects who had a high internal health locus of control reported a greater strength of self-efficacy and demonstrated increased pain tolerance following a choice of strategies. In comparison, subjects who reported a more external health locus of control did not benefit from receiving a choice. This study has implications for our understanding of the role of choice in therapy and for improving the effectiveness of our interventions with individuals.

Adaptation, Psychological↗
PubMed1995

Cold water immersion simulations using the Wissler Texas Thermal Model: validation and sensitivity analysis.

BACKGROUND: Wissler's Texas Thermal Model (TM) has been used to simulate the effects of thermal stresses on individuals under a variety of conditions. As part of a U.S. Navy effort to develop integrated protection garments, TM was modified to predict tolerance to cold water immersion (CWI) with garments with clo values less than 0.1 (15). METHODS: With these modifications, TM predictions were validated using experimental data obtained from 39 males and females during anti-exposure suit CWI assessments. Data analyses were based on changes in rectal (Tre) and various skin temperatures (Tsk). A sensitivity analysis was also performed to determine which TM parameters were most affected during simulated CWI. The condition tested was head-out immersion in 4.4 degrees C water by a 72.6 kg man (10 mm mean skinfold thickness). RESULTS: For most of the subject pool, the estimated change in Tre, chest, thigh, calf, and arm temperatures were not statistically different from experimental values. However, TM predictions were less accurate with respect to female responses. Based on thermal end points, TM predictions indicated that the following body segments were most sensitive to changes in insulation level (ordered from most to least important): chest and abdomen, leg, head, and arm. The physical parameters mean skinfold thickness, basal metabolic rate, body weight, and exercise metabolic rate had the most impact on TM predictions. CONCLUSIONS: The relative benefit of increased insulation on individual body segments was identified to aid garment design. Further, the relative importance of model physical parameters was identified so that judicious initial conditions could be selected to ensure that only garment design changes would be reflected in model predictions.

Abdomen↗
PubMed1989

Energy balance and diabetes. The effects of cold exposure, exercise training, and diet composition on glucose tolerance and glucose metabolism in rat peripheral tissues.

The effects of cold exposure, exercise training, and diet (high fat versus high carbohydrate) on glucose tolerance and glucose metabolism in rat peripheral tissues will be briefly reviewed. Stimulation of energy expenditure by cold exposure (4 degrees C) or exercise training generally leads to decreased plasma insulin levels and to an improvement in glucose tolerance, suggesting that insulin action on peripheral tissues is increased when energy expenditure is stimulated. On the contrary, feeding high-fat diets to sedentary rats living in the warm (25 degrees C) induces hyperinsulinemia and insulin resistance resulting in a marked deterioration of glucose tolerance. Nevertheless, cold exposure reverses the diabetogenic effects of high-fat feeding, demonstrating that nutrition-induced insulin resistance is amplified in sedentary animals living at temperatures close to thermoneutrality. Radioactive tracer studies of 2-deoxyglucose uptake in peripheral tissues revealed that cold exposure synergistically potentiates the effects of insulin on glucose uptake in skeletal muscles as well as in white and brown adipose tissues. However, more recent data showed that cold exposure improves glucose tolerance and stimulates glucose uptake in starved animals (ie., in the virtual absence of circulating insulin) nearly by the same order of magnitude as in fed animals. It is therefore concluded that cold exposure, and possibly also exercise, improve glucose tolerance and stimulate glucose uptake in peripheral tissues primarily by enhancing glucose oxidation via insulin-independent pathways, and secondarily by increasing the responsiveness of peripheral tissues to insulin.

Acclimatization↗
PubMed2001

Pain experience and pain coping strategies in children with juvenile idiopathic arthritis.

OBJECTIVE: To compare reactions to cold pressor pain and pain coping strategies of patients with juvenile idiopathic arthritis (JIA), healthy children, and their parents. METHODS: We studied 16 children with JIA and one of their parents and 14 healthy children and one of their parents. Patients with JIA were selected from the patient population by fulfilling criteria for inclusion in a "high pain" group (n = 7) of patients with modest clinical arthritis activity, but who presented daily reports of pain in connection with everyday activities, and a "low pain" group (n = 9) who presented significant clinical arthritis activity, but who had only a few complaints of pain related to everyday activities. Dependent variables included pain threshold, discomfort, intensity and tolerance to cold pressor pain, and pain coping strategies. RESULTS: Patients with JIA exhibited significantly lower mean pain tolerance than healthy children. Disease duration correlated with both experimental and clinical pain measures, and JIA patients used significantly more Behavioral Distraction than healthy children. Correlations were found between children's and parents' use of Approach and Distraction related coping strategies. Correlations were also found for the coping strategy of Catastrophizing in the JIA patient group. For experimental pain coping strategies, a significant correlation was found between the JIA patients' and their parents' use of Distraction. For the JIA patients Positive Self-statements and Behavioral Distraction were inversely correlated with the clinical pain measures. In both children and parents the experimental pain coping strategies of Catastrophizing and Distraction were associated with the experimental pain response measures, and low pain JIA patients tended to use more Distraction pain coping strategies than high pain patients. CONCLUSION: The results indicate that JIA patients may differ from healthy children with regard to their responses to experimental pain as well as to their use of pain coping strategies. Pain coping strategies of JIA patients were associated with pain coping strategies of their parents, and use of pain coping strategies was associated with both experimental and clinical pain experience.

Adaptation, Psychological↗
PubMed1995

Visceral perception in irritable bowel syndrome. Rectal and gastric responses to distension and serotonin type 3 antagonism.

We wished to determine if visceral perception in the rectum and stomach is altered in patients with irritable bowel syndrome and to evaluate the effects on visceral sensation of 5-HT3 receptor blockade. Twelve community patients with diarrhea-predominant irritable bowel syndrome and 10 healthy controls were studied in a double-blind, randomized, placebo-controlled study. Using two barostats, the stomach and rectum were distended, with pressure increments of 4 mm Hg, from 10 to 26 mm Hg; visceral perception was measured on an ordinal scale of 0-10. Personality traits were measured using standard psychological methods, and somatic pain was evaluated by immersion of the nondominant hand in cold water. The effect of 5-HT3 antagonism was tested with a single intravenous dose of ondansetron at 0.15 mg/kg. Gastric perception was higher in irritable bowel syndrome, but rectal distension was perceived similarly in irritable bowel syndrome and controls. Pain tolerance to cold water was also similar in irritable bowel syndrome and controls. Ondansetron induced rectal relaxation and increased rectal compliance but did not significantly alter gastric compliance or visceral perception. Psychological test scores were similar in patients and controls. We conclude that in this group of psychologically normal patients with irritable bowel syndrome, who were not chronic health-care seekers, visceral perception was normal. Ondansetron did not alter gut perception in health or in irritable bowel syndrome.

Adult↗
PubMed1999

Desiccation elicits heat shock protein transcription in the flesh fly, Sarcophaga crassipalpis, but does not enhance tolerance to high or low temperatures.

Although heat shock protein (hsp) production has been noted in response to multiple environmental stresses, no link has been previously established between desiccation and hsps. Following a nonlethal desiccation at 0% relative humidity (R.H.) for up to 48 h, two heat shock protein transcripts, hsp23 and hsp70, were upregulated in pupae of the flesh fly, Sarcophaga crassipalpis. The transcripts were nearly undetectable in control pupae, but within 24 h after being placed at 0% R.H. high transcript expression was observed. This suggests that protection against desiccation may be linked to the general stress response employed by flesh flies against other environmental stressors such as low or high temperature. Adaptive cross-tolerance to cold shock and heat shock following an hsp-inducing desiccation pretreatment was also tested. Although the two hsp transcripts were upregulated in response to desiccation, the upregulation was less dramatic than the upregulation elicited by heat shock, and desiccation failed to generate tolerance to high or low temperatures.

Journal Article↗
PubMedDate not supplied

Protective effects of ambroxol in hypothermic liver preservation: a transplant study.

The bronchosecretolytic agent ambroxol added to histidine-tryptophan-ketoglutarate (HTK) solution has recently been shown to protect cold stored rat hepatocytes. The aim of the present study was to confirm these observations in a rat liver transplantation model. Before orthotopic liver transplantation, donor livers from 30 syngeneic Wistar rats were assigned to three groups (n = 10): (A) in situ flush (ISF) and 1/2-h cold storage (CS) with HTK solution, (B) ISF and 3-h CS with HTK, and (C) ISF and 3-h CS with HTK + 10(-3) mol/L ambroxol. The efficacy of the drug was evaluated by postoperative survival (> 14 days) and liver enzyme release (ALT), bile flow, histomorphological injury, and malondialdehyde (MDA) level in the grafts 15 min after reperfusion. After 1/2-h CS with HTK solution (A), 90% of the transplanted rats survived. In comparison with donor conditions, bile flow in the reperfused grafts decreased to 87 +/- 5.3%, whereas postoperative ALT levels slightly increased. After 3-h HTK preservation (B), the survival rate decreased to 60%, while ALT values markedly increased and bile flow after reperfusion declined to 82 +/- 6.6%. Ambroxol added to HTK solution (C) enhanced bile flow to 106 +/- 3.4%(p < .05), and reduced ALT and MDA levels and histomorphological injury of the transplanted livers, so that its beneficial effect in organ preservation has been confirmed in the transplant model. However, survival rate was not improved by the agent, probably because of the low cold ischemia tolerance of the Wistar rat livers used.

Alanine Transaminase↗
PubMed1995

Evaluation of pain perception after anterior capsulotomy: a case report.

The medial prefrontal cortex has been implicated in pain perception by recent anatomical, physiological, and functional imaging data demonstrating that frontal and anterior cingulate cortices receive inputs related to nociception; neurosurgical case reports suggest that lesions involving these areas may specifically reduce the affective or emotional component of chronic intractable pain. We examined this hypothesis more closely by assessing psychophysical ratings of (1) warmth, pain intensity, and unpleasantness evoked by phasic thermal stimuli, (2) tolerance to tonic cold stimuli, and (3) perceived intensity of visual stimuli, both before and after neurosurgical lesions of the fiber tracts connecting the frontal lobes to subcortical structures. A 22-year-old male, with no history of chronic pain, underwent psychophysical testing 3 days before, 5 days after, and 6 months after receiving bilateral lesions of the anterior internal capsule (aIC), performed as treatment for obsessive-compulsive disorder. In each session, the patient rated the intensity and unpleasantness of 5-sec cutaneous heat stimuli (39-47 degrees C); pain tolerance was measured by means of a cold-pressor test (hand immersion in 1 degrees C water). The patient was able to differentially rate the intensities of heat stimuli during both pre- and postsurgical testing sessions (p < 0.001). However, he rated heat stimuli as less intense 5 days after surgery than during presurgical testing (p < 0.001), with significant decreases in both pain intensity (p < 0.005) and unpleasantness (p < 0.05). Likewise, the patient described the cold-water immersion as less painful following surgery, although his tolerance times were substantially shorter than those of the presurgical evaluation. Ratings of visual stimulus intensity did not differ across the pre- and postsurgical testing periods, suggesting that changes in pain perception were not related to attentional or cognitive deficits. Magnetic resonance imaging 5 days following surgery revealed bilateral lesions and edema centered in the aIC, with some edema in the left frontal lobe. Those 6 months later showed substantially smaller lesions involving less than half of the aIC and no edema; pain ratings and cold-water tolerance measured at that time indicated a substantial return toward the patient's presurgical values. These data suggest that blocking subcortical input to the anterior cingulate and frontal cortices reduces both the perceived intensity and the unpleasantness of noxious stimuli; reduced cold tolerance times--in the face of decreased pain perception--may reflect a disinhibition of cortical control on spinal reflexes.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

Tolerance to ethanol hypothermia in HOT and COLD mice.

COLD and HOT mice have been selected to be sensitive or resistant, respectively, to the acute hypothermic effect of ethanol. Previous studies have found HOT mice to be relatively resistant to the development of tolerance to this effect, whereas COLD mice readily develop tolerance. By administering several doses of ethanol and recording multiple postdrug temperatures, in the current study we equated the selected lines for area under the curve describing initial hypothermic response over time, a measure reflecting both maximal hypothermia achieved and the duration of total hypothermic response. The dose-response function for COLD mice was much steeper than that for HOT mice, and HOT mice recovered to baseline body temperatures more slowly. Doses were administered daily for 5 days. Both lines developed tolerance to ethanol hypothermia. The magnitude of tolerance developed was greater in COLD than in HOT mice. At higher doses, HOT mice showed a progressively enhanced hypothermic response over days (i.e., sensitization).

Animals↗
PubMed2001

Can estrogen influence the response to noxious stimuli?

STUDY OBJECTIVES: To evaluate estrogen-induced alternations in noxious stimuli response. DESIGN: Randomized, prospective, double-blind study. SETTINGS: Tertiary-care academic medical center. PATIENTS: 40 ASA physical status I and II women at the beginning and conclusion of an in vitro fertilization stimulation cycle. INTERVENTIONS: Stimuli were applied to the fingers of the dominant hand via a Basile Analgesy-Meter, which applied increasing pressure (g/cm(2)) in a continuous fashion, and ice water immersion. MEASUREMENTS: Serum hormonal concentrations and responses to noxious (pressure and cold thermal) stimuli were studied. MAIN RESULTS: Estrogen and progesterone concentrations changed from 377 +/- 323.42 pg/mL to 2078.05 +/- 1175.92 pg/mL (p < 0.001) and 1.20 +/- 0.56 to 1.03 +/- 0.35 ng/mL (p = NS), respectively. Although no significant difference was noted in the response to pressure (16.92 +/- 4.41 to 17.85 +/- 4.95 g/cm(2)), a significant reduction in the tolerance to ice water immersion (34.18 +/- 28.29 to 24.05 +/- 23.02 s) was observed. CONCLUSIONS: High estrogen concentrations are associated with significantly lower tolerance to cold, but not pressure stimuli.

Adult↗
PubMed2003

Mutations in the Ca2+/H+ transporter CAX1 increase CBF/DREB1 expression and the cold-acclimation response in Arabidopsis.

Transient increases in cytosolic free calcium concentration ([Ca2+]cyt) are essential for plant responses to a variety of environmental stimuli, including low temperature. Subsequent reestablishment of [Ca2+]cyt to resting levels by Ca2+ pumps and antiporters is required for the correct transduction of the signal [corrected]. C-repeat binding factor/dehydration responsive element binding factor 1 (Ca2+/H+) antiporters is required for the correct transduction of the signal. We have isolated a cDNA from Arabidopsis that corresponds to a new cold-inducible gene, rare cold inducible4 (RCI4), which was identical to calcium exchanger 1 (CAX1), a gene that encodes a vacuolar Ca2+/H+ antiporter involved in the regulation of intracellular Ca2+ levels. The expression of CAX1 was induced in response to low temperature through an abscisic acid-independent pathway. To determine the function of CAX1 in Arabidopsis stress tolerance, we identified two T-DNA insertion mutants, cax1-3 and cax1-4, that display reduced tonoplast Ca2+/H+ antiport activity. The mutants showed no significant differences with respect to the wild type when analyzed for dehydration, high-salt, chilling, or constitutive freezing tolerance. However, they exhibited increased freezing tolerance after cold acclimation, demonstrating that CAX1 plays an important role in this adaptive response. This phenotype correlates with the enhanced expression of CBF/DREB1 genes and their corresponding targets in response to low temperature. Our results indicate that CAX1 ensures the accurate development of the cold-acclimation response in Arabidopsis by controlling the induction of CBF/DREB1 and downstream genes.

Abscisic Acid↗
PubMed1995

Influence of the sympathetic nervous system in the development of abnormal pain-related behaviours in a rat model of neuropathic pain.

This study evaluated the effect of surgical sympathectomy on pain-related behaviours in a well established model of peripheral mononeuropathy produced by loose ligatures around the common sciatic nerve in the rat. Behavioural abnormalities include spontaneous abnormal position of the hindpaw after the nerve constriction, indicative of "spontaneous pain", and changes in responses to mechanical or thermal stimuli applied to this paw. These changes are usually maximal at week 2 after the surgery, stable until weeks 3-4, and disappear between weeks 8 and 12. To assess the role of the sympathetic nervous system in the development and persistence of these abnormalities, four groups of rats were behaviourally tested: (i) rats receiving a complete sham surgery, (ii) rats with a sciatic nerve constriction produced by loose ligatures around the common nerve trunk plus a sham sympathectomy, (iii) rats receiving a lumbar sympathectomy with a sham nerve ligature, and (iv) rats receiving a simultaneous surgical lumbar sympathectomy and a sciatic nerve constriction. The efficacy of the sympathectomy was assessed by the measure of the noradrenaline level in the sciatic nerve. Sympathectomy reduced selectively or even prevented the abnormal reaction to cold temperature and to heat (45 degrees C) in rats with a peripheral mononeuropathy. In contrast, the abnormal reaction to mechanical pressure was not influenced, and the behavioural abnormalities indicating spontaneous pain were still present. Sympathectomy alone resulted in a reduction of the vocalization threshold to pressure on both hindpaws, but also a short-lasting increased tolerance to cold immersion. This study confirms the selective role of the sympathetic nervous system in affecting the development and maintenance of some abnormal pain-related behaviours to thermal stimuli in rats with a moderate, but persistent, constriction of one sciatic nerve.

Animals↗
PubMed2006

Heat shock induces apoptosis related gene expression and apoptosis in porcine parthenotes developing in vitro.

Successful in vitro development of embryos is dependent upon maintenance of cellular function in the embryonic microenvironment. However, the molecular aspects involved in the thermoprotection of embryos, against heat and cold stress it is not clear. The aim of this study was to determine the effects of heat and cold shock on the viability and development of porcine diploid parthenotes developing in vitro. Exposure of two-cell stage embryos to 41 degrees C did not affect further cleavage. However, prolonged heat shock, greater than 12h, reduced the percentage of blastocysts that developed from two-cell stage parthenotes, as well as the total number of nuclei in the blastocysts that formed. Furthermore, the degree of apoptosis was increased (P<0.05) in these blastocyst stage parthenotes. In contrast, exposure of two-cell parthenotes to cold (30 degrees C) for 24h did not affect the cleavage rates, development to blastocyst, nor the total cell numbers per blastocyst. Real time PCR revealed that quantitative expression of the Bcl-xL gene was not different, but amounts of HSP 70.2, Bak, and Caspase 3mRNA were significantly increased in the heat shocked embryos, as compared with untreated controls. These results suggest that porcine embryos are more tolerant to cold shock than to heat shock. Heat stress seems to induce apoptosis related gene expression in porcine parthenotes developing in vitro, which results in diminished parthenote viability.

Animals↗
PubMed2000

Two loci on wheat chromosome 5A regulate the differential cold-dependent expression of the cor14b gene in frost-tolerant and frost-sensitive genotypes.

Although cold acclimation in cereals involves the expression of many cold-regulated genes, genetic studies have shown that only very few chromosomal regions carry loci that play an important role in frost tolerance. To investigate the genetic relationship between frost tolerance and the expression of cold-regulated genes, the expression and regulation of the wheat homolog of the barley cold-regulated gene cor14b was studied at various temperatures in frost-sensitive and frost-tolerant wheat genotypes. At 18/15 degrees C (day/night temperatures) frost-tolerant plants accumulated cor14b mRNAs and expressed COR14b proteins, whereas the sensitive plants did not. This result indicates that the threshold temperature for induction of the wheat cor14b homolog is higher in frost-resistant plants, and allowed us to use this polymorphism in a mapping approach. Studies made with chromosome substitution lines showed that the polymorphism for the threshold induction temperature of the wheat cor14b homolog is controlled by a locus(i) located on chromosome 5A of wheat, while the cor14b gene was mapped in Triticum monococcum on the long arm of chromosome 2Am. The analysis of single chromosome recombinant lines derived from a cross between Chinese Spring/Triticum spelta 5A and Chinese Spring/Cheyenne 5A identified two loci with additive effects that are involved in the genetic control of cor14b mRNA accumulation. The first locus was tightly linked to the marker psr911, while the second one was located between the marker Xpsr2021 and Frost resistance 1 (Fr1).

Blotting, Northern↗