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PubMed2001

The cold-shock stress response in Mycobacterium smegmatis induces the expression of a histone-like protein.

The response of Mycobacterium smegmatis to a cold shock was investigated by monitoring changes in both growth and cellular protein composition of the organism. The nature of the cellular response was influenced by the magnitude of the temperature reduction, with the shock from 37 degrees C to 10 degrees C having the most widespread effect on growth, metabolism and protein composition. This 27 degrees C temperature reduction was associated with a lag period of 21-24 h before increases were seen in all the measured cellular activities. The response to cold shock was adaptive, with growth resuming after this period, albeit at a 50-fold slower rate. The synthesis of at least 15 proteins was induced during the lag period. Two distinct patterns of cold-induced synthesis were apparent, namely transient and continuous, indicating the production of both cold-induced and cold-acclimation proteins. One of these cold-shock proteins, CipMa, was identified as the histone-like protein, Hlp, of M. smegmatis, which is also induced during anaerobic-induced dormancy. The corresponding gene demonstrated transient, cold-inducible expression with a five- to sevenfold increase in mRNA occurring 9-12 h after temperature shift. Although bacterial survival was unaffected, CipMa/Hlp knock-out mutants were unable to adapt metabolically to the cold shock and resume growth, thus indicating a key role for CipMa in the cold-shock response.

Amino Acid Sequence↗

PubMed2002

Light signalling mediated by phytochrome plays an important role in cold-induced gene expression through the C-repeat/dehydration responsive element (C/DRE) in Arabidopsis thaliana.

Low temperature induces a number of genes that encode the proteins promoting tolerance to freezing, mediated by ABA-dependent and ABA-independent pathways in plants. The cis-acting element called C/DRE is known to respond to low temperature independently of ABA action. To investigate the signalling and network of ABA-independent pathways, the transgenic Arabidopsis plants were generated containing several copies of the C/DRE derived from cor15a gene with a minimal promoter fused to a GUS reporter gene. The transgenic plants containing four copies of the C/DRE (4C/DRE-GUS) showed responsiveness to cold and drought treatments and were used for characterization of cold signalling and cross-talk. Cold-induced GUS expression was inhibited by okadaic acid at 1 nM, indicating that protein phosphatase 2A might act as a positive regulator. Light was shown to activate cold- and drought-induced GUS expression. Photo-reversibility of the GUS mRNA by red and far-red light with concomitant cold treatment suggests a role of phytochrome as a photoreceptor in mediating light signalling to activate the cold-induced gene expression through the C/DRE. Furthermore, GUS expression analysis in phyA or phyB or phyAphyB mutant backgrounds showed that phytochrome B is a primary photoreceptor responsible for the activation of cold-stress signalling in response to light. Light enhanced the induction kinetics of CBF1, 2, and 3 encoding the cognate transcription factors, and cor15a, in a consecutive manner compared to the dark condition in the cold, suggesting that the connection point between cold and light signalling mediated by phytochrome is at a higher step than the expression of CBF genes.

Abscisic Acid↗

PubMed1999

Patient and injury characteristics in the development of cold sensitivity of the hand: a prospective cohort study.

In this prospective cohort study, we questioned whether cold sensitivity occurring after all types of injuries decreases, increases, or remains constant. We also questioned which patient and injury characteristics are most associated with the development of cold sensitivity. The degree of cold sensitivity of 123 patients with acute hand and forearm injuries was repeatedly scored from a prevalidated questionnaire over 11 months after injury. Twenty-five patients with more severe symptoms at 11 months were reassessed at 3 years. The patients' age, gender, smoking habit, workers' compensation status, mechanism of injury, level and orientation of injury, and injured structures were analyzed with respect to cold sensitivity. The results of our study indicate that the severity of cold sensitivity increased from the time of injury until 3 months following injury and then remained constant until 11 months following injury. At 3 years from injury, symptoms in patients with severe cold sensitivity had significantly reduced to 67% of the 11-month level. Cold sensitivity was common in all types of hand injuries, not just in amputations and in arterial or nerve injuries. A multiple linear regression analysis suggested that the severity of cold sensitivity was most related to the presence of bone injury. Cold severity was not specifically related to smoking or amputations.

Adolescent↗

PubMed1985

Influence of lesions in the limbic-hypothalamic system on metabolic response of pyruvate to daily repeated cold exposure in rabbits.

The effects of lesions of the limbic-hypothalamic structures on the pyruvate metabolic responses to daily repeated cold exposures in the liver of rabbits have been investigated. The experimental results were as follows: The metabolic pattern of pyruvate and the pyruvate metabolic responses to the 1st cold exposure (cold exposure on the 1st day) were altered by lesions of periventricular arcuate nucleus (ARC), ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). The pyruvate metabolic responses to cold exposure were completely abolished by seven times repetition of daily cold exposures in rabbits with lesions of ARC, VMH and FX, as well as in each sham-operated group. In rabbits with ST lesions, the pyruvate metabolic responses to cold exposure remained even after the seven times repetition of daily cold exposures. From these results, it might be suggested that the ARC, VMH, amygdala (AMYG)-ST system and dorsal hippocampus (HPC)-FX system played a certain role in the metabolic regulation of pyruvate and in the mechanisms of pyruvate metabolic responses to the 1st cold exposure, but that only the AMYG-ST system participated in the process of pyruvate metabolic adaptation to daily repeated cold exposures.

Animals↗

PubMed1992

The role of limbic-hypothalamic systems in metabolic responses of phenylalanine to repeated cold exposures in rabbits.

In this study we examine the effects of lesions to limbic or hypothalamic structures on the metabolic responses of phenylalanine in liver slices prepared from rabbits exposed to cold stress (-20 degrees C) for 12 hours at a fixed time once a day. The results were as follows: 1. The 1st cold exposure (cold exposure on the 1st day) had marked and various effects on phenylalanine metabolism, and the metabolic responses of phenylalanine to cold exposure gradually decreased and then completely disappeared with repetitions of exposure in intact rabbits. 2. The metabolic patterns and responses of phenylalanine to the 1st cold exposure were altered by lesioning the periventricular arcuate nucleus (ARC), ventromedial hypothalamus (VMH), stria terminalis (ST) or dorsal fornix (FX). 3. The complete abolishment of the metabolic responses to cold exposure by its repetition was observed in rabbits with lesions in the ARC or VMH as well. 4. In contrast, metabolic responses of phenylalanine to cold exposure in rabbits with lesions in the ST or FX remained even after six exposures. These results suggest that the ARC, VMH, amygdala (AMYG)-ST system and dorsal hippocampus (HPC)-FX system played a role in the metabolic regulation of phenylalanine and in the metabolic responses of phenylalanine to the 1st cold exposure and that the AMYG-ST and HPC-FX systems, but not the ARC or VMH, participated in the process of the metabolic adaptation of phenylalanine to cold exposure.

Amygdala↗

PubMed2002

Effect of cold exposure on older humans.

Epidemiological studies have shown excess winter mortality particularly in older age groups. A question is how much these statistics are affected by age-related physiological changes in cold thermoregulation and how much due to other factors related to aging. In experimental studies concerning age and cold stress both whole-body and local exposures have been used mostly in resting subjects with minimal clothing. Older persons, particularly men over ca. 60 years, are less able to maintain core temperature during a given cold challenge compared to younger individuals. Older persons have a reduced cutaneous thermal sensitivity, and a reduced subjective thermal perception during cooling. Thus, older people may require a more intense stimulus to perform protective actions against cold stress. Older persons' skin vasoconstrictive response to cold is diminished compared to younger persons, which seems partly related to a reduced skin vasomotor sensitivity to sympathoneuronal stimuli. The cold-induced rise in metabolic rate is attenuated in older persons, but the mechanism is unknown. Both central and peripheral components seem to be involved in the age-related changes in regulatory effector functions. Enhanced aerobic fitness may not give added protection against core cooling during cold stress in the elderly, but seems to attenuate older subjects' heightened blood pressure response to cold. Bronchial responsiveness to face cooling may increase with age. Further studies are needed to examine the age-related changes in non-thermoregulatory responses to cold (e. g. hemodynamics, cardiac function, respiration, autonomic nervous function), and the modifying effects of acute exercise and physical training.

Aged↗

PubMed2002

Continuous antegrade blood cardioplegia: cold vs. tepid.

BACKGROUND: Continuous antegrade blood cardioplegia (CABCP) is used at different temperatures. We investigated the consequences of CABCP at 6 degrees C (COLD) vs. 28 degrees C (TEPID). METHODS: Anesthetized open-chest pigs (25 +/- 2 kg) were placed on cardiopulmonary bypass (CPB). The hearts were arrested for 30 min by 6 degrees C cold or 28 degrees C tepid CABCP (n = 8 each). After an initial 3 min antegrade application of high potassium (20 mEq) cold (6 degrees C) blood cardioplegia, the hearts were arrested for a subsequent 27 min by normokalemic blood delivered antegrade at either 6 degrees C or 28 degrees C. After this, the hearts underwent perfusion with warm systemic blood for an additional 30 min on CPB. Biochemical cardiac data (MVO2 [ml/min/100 g], release of creatine kinase [CK U/min/100 g] and lactate [mg/min/100 g]) were measured during CPB. Total tissue water content (%) and left ventricular stroke work index (SWI g x m/kg) were determined 30 min after discontinuation of CPB and compared to pre-CPB controls. RESULTS: Cold CABCP kept all hearts continuously arrested. The COLD hearts showed no biochemical or functional disturbance. The TEPID hearts intermittently fibrillated and required additional high potassium BCP shots. The TEPID hearts showed a marked CK leakage (2.6 +/- 0.4 vs. 0.7 +/- 0.4), lactate production (4.0 +/- 1.6 vs. extraction from the COLD group) despite the non-ischemic protocol, an impaired initial oxygen consumption (4.2 +/- 1.3 vs. 7.1 +/- 1.6) at the end of cardiac arrest, the formation of myocardial edema (79.5 +/- 1.0 vs. 77.0 +/- 0.8), and a depressed recovery of SWI (0.69 +/- 0.15 degrees vs. 1.41 +/- 0.13). *p < 0.05 for comparison of TEPID vs. COLD hearts using Student's t-test for unpaired data; degrees p < 0.05 for intergroup-comparison of TEPID vs. COLD vs. controls using ANOVA adjusted for repeated measures. CONCLUSIONS: Uninterrupted cardioplegia can be safely performed with cold normokalemic CABCP. In contrast, tepid normokalemic CABCP leads to fibrillation, jeopardizes the heart, and should be avoided.UND

Animals↗

PubMed1996

Molecular cloning and cold-inducible gene expression of ferritin H subunit isoforms in rainbow trout cells.

Cold acclimation of rainbow trout cells is considered to be mediated by alterations in the mRNAs and proteins present in cold-treated cells. A subtracted cDNA library from cold-treated rainbow trout RTG-2 cells was constructed and screened to isolate cDNA induced in the cold-treated cells in order to elucidate which genes are induced by cold acclimation. A set of cDNA clones encoding three members of ferritin H isoforms was isolated as cold-inducible genes. Northern blot analysis and nuclear run-on transcription assay showed that the transcription and accumulation of the ferritin H isoforms mRNA were enhanced by cold acclimation. Furthermore, the ferritin level in the trout cells increased on cold acclimation in response to a temperature shift from 22 degrees C to 4 degrees C. When the trout cells were subjected to 4 degrees C under the condition of a decreased ferritin H level obtained by the addition of an antisense oligonucleotide, cell growth was apparently inhibited. These findings indicate an association between the induction of ferritin H and cellular mechanisms during cold acclimation of trout cells.

Amino Acid Sequence↗

PubMed2002

Gene-engineered rigidification of membrane lipids enhances the cold inducibility of gene expression in synechocystis.

A sudden decrease in ambient temperature induces the expression of a number of genes in poikilothermic organisms. We report here that the cold inducibility of gene expression in Synechocystis sp. PCC 6803 was enhanced by the rigidification of membrane lipids that was engineered by disruption of genes for fatty acid desaturases. DNA microarray analysis revealed that cold-inducible genes could be divided into three groups according to the effects of the rigidification of membrane lipids. The first group included genes whose expression was not induced by cold in wild-type cells but became strongly cold-inducible upon rigidification of membrane lipids. This group included certain heat-shock genes, genes for subunits of the sulfate transport system, and the hik34 gene for a histidine kinase. The second group consisted of genes whose cold inducibility was moderately enhanced by the rigidification of membrane lipids. Most genes in this group encoded proteins of as yet unknown function. The third group consisted of genes whose cold inducibility was unaffected by the rigidification of membrane lipids. This group included genes for an RNA helicase and an RNA-binding protein. DNA microarray analysis also indicated that the rigidification of membrane lipids had no effect on the heat inducibility of gene expression. Hik33, a cold-sensing histidine kinase, regulated the expression of most genes in the second and third groups but of only a small number of genes in the first group, an observation that suggests that the cold-inducible expression of genes in the first group might be regulated by a cold sensor that remains to be identified.

Cold Temperature↗

PubMed1982

Effects of cold exposure on feed protein degradation, microbial protein synthesis and transfer of plasma urea to the rumen of sheep.

1. Three diets of barley-canola-seed (Brassica campestris), lucerne (Medicago sativa) or chopped brome-grass (Bromus inermis) were given at intervals of 3 h to closely-shorn Suffolk wethers held at a temperature of 1-5 degree (cold) or 22-24 degree (warm). Apparent digestibility of organic matter (OM) and nitrogen was reduced by 0.08-0.05 and 0.04 units respectively for lucerne and brome-grass diets given to cold-exposed sheep, but no treatment effects on digestibility were observed for the barley-CSM diet. Measurements achieved using infusion of the digesta markers 58Co-EDTA and 103Ru-phenanthroline (103Ru-P) showed that cold exposure depressed apparent OM digestion in the stomach and intestines by 33 and 42 g/d for the lucerne diet, and 13 and 35 g/d for the brome-grass diet respectively. 2. The turnover time (h) of the 103Ru-P marker in the rumen of warm sheep was 38.9 for barley-CSM, 18.4 for lucerne, and 15.6 for brome-grass. In cold-exposed sheep, 103Ru-P turnover time (h) tended to be reduced to 32.3, 12.3 and 15.3 for the three diets, respectively. OM fermentation in the stomach was highly related to 103RU-P turnover time for lucerne and brome-grass diets. 3. Cold exposure increased the escape of dietary N from the abomasum by 0.04 and 0.09 of dietary N intake for sheep given lucerne and brome-grass diets respectively. Dietary N degradation was closely related to 103Ru-P turnover time for lucerne, and to the proportion of large particles in rumen digesta for the brome-grass diet. Estimates of feed N degradation made by use of information on the rate of fermentation of the diet in nylon bags and 103Ru-P turnover time were consistently lower than those observed in vivo for barley-CSM and lucerne diets. Intestinal digestibility of non-ammonia N was not significantly changed by cold exposure. 4. Transfer of urea from plasma to the rumen was 1.4-2.5 g N/d for the barley-CSM and lucerne diets, but the value for brome-grass was 4.5-4.9 g N/d. Cold exposure did not affect urea transfer. The production of ammonia from feed and endogenous protein was approximately 0.66 and 0.47 g N/g N intake of barley-CSM and lucerne diets, with no effect of cold exposure. Cold exposure reduced the value from 0.57 to 0.38 for brome-grass. 5. The results are compared with those obtained previously with pelleted hay, and the importance of large particle breakdown in the prediction of OM and N fermentation using nylon bags is discussed.

Animal Feed↗

PubMed1985

Influences of cold exposure on digestion of organic matter, rates of passage of digesta in the gastrointestinal tract, and feeding and rumination behaviour in sheep given four forage diets in the chopped, or ground and pelleted form.

Sixteen sheep, each fitted with cannulas in the rumen and proximal duodenum, were given four diets in the chopped or ground and pelleted form, at fixed intakes at intervals of 2 h. The sheep were closely shorn and exposed to temperatures of 22-25 degrees or 1-4 degrees for four periods of 45 d. Flow of duodenal digesta by reference to the markers CoEDTA and 103Ru-phenanthroline, chewing behaviour and particle size of rumen and duodenal digesta were measured. Apparent digestibility of organic matter (OM) in the gastrointestinal tract was depressed (P less than 0.05) by grinding and pelleting the diet, and by exposure of sheep to cold ambient temperatures. This was attributable to depression (P less than 0.01) by 0.1 of OM digestion in the reticulo-rumen. No effects on intestinal digestion of OM were observed. Cold ambient temperatures did not affect the content, but increased the rate of digestion for pelleted diets but not for chopped diets, of potentially-degradable cell-wall constituents of ground dietary material incubated in nylon-bags in the rumen. Retention times of markers of the particulate and liquid phases of rumen digesta were not significantly (P less than 0.05) affected by ambient temperature, despite significant (P less than 0.001) increases in the rate of contraction of the reticulum. Retention time of 103Ru-phenanthroline in the intestines was not affected by cold exposure. Cold exposure was associated with depression (P less than 0.05) of volatile fatty acids concentration in the rumen and elevated (P less than 0.05)pH. Molar proportions of acetic and isovaleric acid were reduced (P less than 0.01), accompanied by increased (P less than 0.001) proportions of propionic acid during cold exposure. Cold exposure and pelleting of the diets were both associated with reduction in digesta particle size in the rumen. Duodenal particle size was not affected by cold exposure. Pelleting of the diet markedly reduced (P less than 0.001) duration of chewing and number of chews/d during eating and rumination. Cold exposure of sheep resulted in a faster (P less than 0.01) rate of eating of the diets. When allowed to express their voluntary feed consumption during a 10 d period, intakes of chopped diets were increased by 0.13 (P less than 0.01) by cold exposure, in contrast to lack of significant change in sheep given pellets.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2001

Effect of cold exposure on energy balance and liver respiratory capacity in post-weaning rats fed a high-fat diet.

Variations in energy balance, body composition, and nutrient partitioning induced by high-fat feeding, cold exposure or by concomitant high-fat feeding and cold exposure were studied in young Wistar rats. Changes in hepatic metabolism as well as in serum free triiodothyronine and leptin levels were also evaluated. Rats were exposed to either 24 or 4 degrees C and fed either a low- or high-fat diet (10 % or 50 % energy respectively) for 2 weeks. Relative to low-fat feeding at 24 degrees C, both energy intake and expenditure were increased by high-fat feeding or by cold exposure, and these changes were accompanied by increased serum triiodothyronine levels. In response to concomitant high-fat feeding and cold exposure, serum triiodothyronine tended to be further elevated, but no further increases in energy intake or energy expenditure were observed. Independently of diet, the increased energy expenditure in cold-exposed rats was not completely balanced by adaptive hyperphagia, with consequential reductions in protein and fat gain, accompanied by marked decreases in serum leptin. Furthermore, unlike high-fat feeding at 24 degrees C, cold exposure enhanced hepatic mitochondrial oxidative capacity both in the low-fat- and high-fat-fed groups. It is concluded that in this strain of young Wistar rats, despite similarly marked stimulation of energy expenditure by high-fat feeding at 24 degrees C, by cold exposure and by concomitant high-fat feeding and cold exposure, an increased hepatic oxidative capacity occurred only in the presence of the cold stimulus.

Animals↗

PubMed2006

The prophylactic and therapeutic effectiveness of zinc sulphate on common cold in children.

AIM: To determine the efficacy of prophylactic administration of zinc sulphate in reducing the occurrence of the common cold in children, and to evaluate the efficacy of zinc sulphate in reducing the duration and severity of cold symptoms. METHODS: A total of 200 healthy children were randomly assigned to receive oral zinc sulphate (zinc group, n=100) or placebo (placebo group, n=100). Zinc sulphate (15 mg of zinc) or placebo syrup were administered for prophylaxis once daily during a 7-mo study period. The dose was increased to two times per day (30 mg of zinc) at the onset of cold, until symptoms resolved. RESULTS: The mean number of colds in the zinc group was significantly less than in the placebo group (1.2 vs 1.7 colds per child; p=0.003). The mean cold-related school absence was 0.9 d per child in the zinc group versus 1.3 d in the placebo group (p=0.04). Compared to the placebo group, the zinc group had shorter mean duration of cold symptoms and decreased total severity scores for cold symptoms (p<0.0001). Adverse effects were mild and similar in both groups. CONCLUSION: Zinc sulphate appears to be an easily administered, safe and well-tolerated alternative for the prevention and treatment of the common cold in children.

Antiviral Agents↗

PubMed2004

Effect of sodium on vasoconstriction and angiotensin II type 1 receptor mRNA expression in cold-induced hypertensive rats.

Angiotensin II and sodium play an important pathogenetic role in several models of hypertension. Now, we investigated the effects of sodium on vasoconstriction and angiotensin II type 1 (AT1) and type 2 (AT2) receptor mRNA expression in aortic vessels from cold-induced hypertensive rats. Wistar rats on low sodium and high sodium diet were exposed to cold-stress for 8 weeks. The effects of angiotensin II infusion on mean arterial blood pressure were investigated in these rats. In addition, angiotensin II induced contraction was measured using aortic rings. Expression of AT1 receptor mRNA and AT2 receptor mRNA was assessed in aortic vessels by reverse transcription polymerase chain reaction. After infusion of angiotensin II mean arterial blood pressure in cold-induced hypertensive rats on high sodium diet was significantly higher compared to cold-induced hypertensive rats on low sodium diet (p < 0.05). Angiotensin II-induced contraction of aortic rings was significantly higher in cold-induced hypertensive rats on high sodium diet compared to cold-induced hypertensive rats on low sodium diet (2.39 +/- 0.03 g vs. 2.21 +/- 0.04 g, n = 12, p < 0.01). Angiotensin AT1 receptor mRNA was significantly higher in cold-induced hypertensive rats on high sodium diet compared to cold-induced hypertensive rats on low sodium diet (p < 0.05). It is concluded that in this nongenetic, nonsurgical animal model of cold-induced hypertension increased vasoconstriction and increased AT1 receptor mRNA expression in aortic vessels are dependent on sodium intake.

Animals↗

PubMed2006

Efficacy of COLD-fX in the prevention of respiratory symptoms in community-dwelling adults: a randomized, double-blinded, placebo controlled trial.

BACKGROUND: COLD-fX (CVT-E002), a proprietary extract of the roots of North American ginseng (Panax quinquefolium), rich in poly-furanosyl-pyranosyl-saccharides, has been found efficacious in the prevention of respiratory infections in institutionalized seniors and healthy adults. OBJECTIVE: We examined the efficacy of COLD-fX in the prevention of acute respiratory illness (ARI) in community dwelling seniors. DESIGN: This was a randomized, double-blind, placebo controlled trial. INTERVENTION: The participants were asked to take 2 capsules/day of either COLD-fX or placebo (200 mg/ capsule) for a period of 4 months. SUBJECTS: A total of 43 community-dwelling adults aged 65 years or older were recruited. Following one month of intervention, subjects were immunized with influenza vaccine. OUTCOME MEASURES: Subjects recorded the incidence and duration of respiratory symptoms during the study. They also recorded the incidence of adverse events during the study. RESULTS: The frequency and duration of ARI during the first two months of the study was found to be similar in the two groups. However, during the last 2 months (November and December) significantly fewer subjects in the COLD-fX group 32% reported ARI compared to the placebo group 62%. The duration of symptoms during the last 2 months was significantly shorter in the COLD-fX group than the placebo group (5.6 days in the COLD-fX group vs 12.6 days in the placebo group). There was no influenza illness circulating in the community during the period of the study. CONCLUSIONS: Ingestion of COLD-fX by immunocompetent seniors during an early "cold and flu" season reduced the relative risk and duration of respiratory symptoms by 48% and 55%, respectively. Daily COLD-fX administration can thus be a safe, natural therapeutic means for the prevention of ARI in healthy seniors.

Aged↗

PubMed1996

Survival of Ixodes scapularis (Acari: Ixodidae) exposed to cold.

The cold hardiness of Ixodes scapularis Say unengorged larvae, engorged larvae, unengorged nymphs, engorged nymphs, and unengorged adults was evaluated. Ticks were exposed to cold for 2 or 8 h at a range of temperatures. Likelihood ratio tests and LT50 estimates were used to evaluate cold hardiness. Likelihood ratio tests indicated that stage and engorgement effects were significant with the exception of the stage effect between engorged larvae and engorged nymphs. LT50 estimates indicated that unengorged nymphs were the most cold-hardy, followed by engorged nymphs, unengorged adults, and both unengorged and engorged larvae. Sex of adult ticks had no statistically significant effect on cold hardiness. Unengorged larvae and unengorged nymphs were tested for evidence of a cold-hardening response. No larvae or nymphs exposed to a cold pretreatment and subsequent cold treatment displayed rapid cold-hardening.

Animals↗

PubMed1982

Plasma magnesium levels as influenced by cold exposure in fed or fasted sheep.

Eight ewes weighing about 52 kg were used in a 2 X 2 factorial arrangement of treatments replicated with temperature reversal to determine the effect of cold exposure on plasma Mg, Ca, free fatty acids (FFA), glucose and insulin concentrations and on renal clearance of Mg and Ca. Closely sheared ewes were fed a complete mixed diet at either 1.5% of body weight with no pretreatment fast or fed ad libitum followed by fasting 3 days before initiation of temperature treatments. Fasting superimposed on cold exposure reduced (P less than 0.01) plasma Mg at 1 hour after exposure to cold, and this effect continued during the cold treatment period, whereas Mg concentration was not significantly affected in fed sheep. Plasma FFA measured across temperature treatments was increased (P less than 0.01) by fasting. FFA measured across dietary treatments was only slightly increased by cold exposure. Plasma glucose levels of fasting sheep were lower (P less than 0.05) than those of fed sheep; however, levels rose (P less than 0.05) after exposure to cold. A tendency for plasma insulin to increase after cold stress was observed. Renal clearances of Mg and Ca were markedly reduced (P less than 0.01) by fasting, but clearance was not changed by cold stress. These results suggest that exposure to cold (2-5 degrees) and a deficient dietary intake synergistically reduce plasma Mg in sheep.

Animals↗

PubMed1997

Hepatitis C virus-related liver damage is related to cold activation of complement.

A high positivity of cold activation of complement has been reported in Japanese patients having hepatitis B virus-negative chronic hepatitis. Although the cause of cold activation of complement is unknown, the involvement of hepatitis C virus (HCV) has been suspected. We studied the positivity of cold activation of complement in 253 patients, including 93 patients with chronic hepatitis C infection who received 6MU natural interferon-alpha per day for 24 continuous weeks. Cold activation was positive in 38% of patients with chronic hepatitis C and in 46% of patients with liver cirrhosis C. We did not detect cold activation in asymptomatic HCV carriers; patients with chronic hepatitis B, liver cirrhosis B, or alcohol-related liver damage; or in the controls. Cold activation was also negative in HCV-RNA-negative patients who responded completely to interferon-alpha, and in HCV-RNA-positive patients who responded partially whose serum alanine transaminase levels were normalized after interferon treatment. In the patients who had a relapse of hepatitis C after interferon treatment, positivity of cold activation increased sharply. We conclude that HCV-associated liver damage is related to the development of cold activation of complement. Cold activation is useful for monitoring the response to interferon in patients with chronic hepatitis C infection.

Adult↗