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PubMed1987

Alteration of Gene Expression during the Induction of Freezing Tolerance in Brassica napus Suspension Cultures.

Brassica napus suspension-cultured cells can be hardened to a lethal temperature for 50% of the sample of -20 degrees C in eight days at room temperature with abscisic acid. During the induction of freezing tolerance, changes were observed in the electrophoretic pattern of [(35)S]methionine labeled polypeptides. In hardening cells, a 20 kilodalton polypeptide was induced on day 2 and its level increased during hardening. The induction of freezing tolerance with nonmaximal hardening regimens also resulted in increases in the 20 kilodalton polypeptide. The 20 kilodalton polypeptide was associated with a membrane fraction enriched in endoplasmic reticulum and was resolved as a single spot by two-dimensional electrophoresis. In vitro translation of mRNA indicate alteration of gene expression during abscisic acid induction of freezing tolerance. The new mRNA encodes a 20 kilodalton polypeptide associated with increased freezing tolerance induced by either abscisic acid or high sucrose. A 20 kilodalton polypeptide was also translated by mRNA isolated from cold-hardened B. napus plants.

Journal Article↗
PubMed1978

Aspects of temperature regulation in harp seal pups evaluated by in vivo experiments and computer simulations.

Temperature regulation in harp seal pups (Pagophilus groenlandicus) has been studied by in vivo measurements of oxygen consumption, body temperatures and in vitro determinations of the thermal values of a fur sample. The experimental animals were restrained and exposed to natural wheather conditions. Solar irradiance above 600 W/m (global radiation) caused hyperthermia. Computer simulations based on the thermal values of the fur indicated that heat dissipation from primarily the limbs is a prerequisite for avoiding hyperthermia under natural weather conditions. Further simulations showed that the lower critical temperature of a lean newborn harp seal pup with standard metabolism is only--1 degree C while it is depressed to--59 degree C as the pup grows, aquire a 10 cm thick layer of blubber and the metabolism increases to 1.5 times standard. High metabolism and tolerance to low deep body temperatures (35 degree C) seems a prerequisite for thermal balance in the harp seal pup under cold conditions.

Animals↗
PubMed1994

Exercise training in sweat clothing in cool conditions to improve heat tolerance.

Training in sweat clothing in cool conditions has appeal as the most practical and exercise-specific method of improving heat tolerance when athletes cannot achieve natural acclimation to hot conditions prior to competition. However, both early and more recent studies have not provided sufficient evidence to allow a conclusive endorsement of this method. Despite this, it is apparent that training in sweat clothing in cool conditions can induce levels of thermal strain in trained individuals which are very similar to those experienced when the same exercise is performed in hot-humid conditions. Certainly, training in sweat clothing in cool conditions is preferable to attempting no artificial acclimation measures, although statistically significant improvements in heat tolerance beyond those induced by the training itself are rare.

Acclimatization↗
PubMed1995

2,3-Butanedione monoxime (BDM) increases initial yields and improves long-term survival of isolated cardiac myocytes.

When BDM is added to the perfusion solutions used during the preparation of single, enzymatically dispersed mammalian cardiomyocytes, higher yields of calcium-tolerant cells are obtained. As the principal component of a storage solution, BDM also improves the survival of myocytes maintained in cold storage. These data support the hypothesis that BDM can act as a cardioprotective agent under certain conditions.

Animals↗
PubMed1977

[Local tissue reactions to subplatysmal implants of cold polymerizing silastic as bladder prostheses in the animal experiment].

In animal experiments silicone rubber bodies of various volumes and weights were implanted under the platysma. The grafts were completely tolerated by 6 rabbits and partially by a minipig, but not at all by 4 dogs. The primary reason for the failures were chronic inflammation by motion of the graft, heaviness of the plastic material, and stromal weakness.

Animals↗
PubMed1999

Improved antioxidative protection in winter swimmers.

Adaptation to oxidative stress is an improved ability to resist the damaging effects of reactive oxygen species, resulting from pre-exposure to a lower dose. Changes in uric acid and glutathione levels during ice-bathing suggest that the intensive voluntary short-term cold exposure of winter swimming produces oxidative stress. We investigated whether the repeated oxidative stress in winter swimmers results in improved antioxidative adaptation. We obtained venous blood samples from winter swimmers and determined important components of the antioxidative defense system in the erythrocytes or blood plasma: reduced and oxidized glutathione (GSH and GSSG), and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (Cat). The control group consisted of healthy people who had never participated in winter swimming. The baseline concentration of GSH and the activities of erythrocytic SOD and Cat, were higher in winter swimmers. We interpret this as an adaptative response to repeated oxidative stress, and postulate it as a new basic molecular mechanism of increased tolerance to environmental stress.

Adaptation, Physiological↗
PubMed1984

Effect of temperature stress on circulating biogenic amines in bovine.

A sensitive, simple and selective chromatographic method using high performance liquid chromatography was developed to measure circulating levels of histamine (HI), norepinephrine (NE), dopamine (DA) and serotonin (5-HT) as indicators of response to thermal stress in two breeds of cattle. Duplicate exposures for 8 hr to 13 degrees C resulted in significantly elevated plasma NE and DA in longhorns but not in Herefords and suggest a relatively greater sensitivity to the cold (13 degrees C) in the longhorn. Environmental temperatures of 32 and 42 degrees C significantly increased rectal temperatures of both breeds with much higher rectal temperatures in Herefords. The 32 and 42 degrees C effects on circulating NE and DA of Herefords were highly significant but not in the longhorn. However, heat stress significantly elevated HI and 5-HT in the longhorn which may account for their relatively greater heat tolerance based on their lower rectal temperatures.

Animals↗
PubMed2003

Influence of phytostanol phosphoryl ascorbate (FM-VP4) on insulin resistance, hyperglycemia, plasma lipid levels, and gastrointestinal absorption of exogenous cholesterol in Zucker (fa/fa) fatty and lean rats.

The purpose of this investigation was to determine the effects of Phytostanol Phosphoryl Ascorbate (FM-VP4) on insulin resistance, hyperglycemia, plasma lipid levels, body weight, and gastrointestinal absorption of exogenous cholesterol in Zucker (fa/fa) fatty and lean rats. A group of 12 age-matched male obese (n = 6) and lean (n = 6) Zucker rats were administered 250 mg/kg twice a day (as 2% FM-VP4 in drinking water) for 30 consecutive days. Fasted blood samples prior to and following treatment were taken from all rats for glucose, lipid, insulin, and leptin determination. An oral glucose tolerance test was also carried out at the end of the treatment protocol. In addition, male obese (n = 7) and lean (n = 8) Zucker rats were coadministered a single oral gavage of [(3)H]cholesterol plus cold cholesterol with or without FM-VP4 (20 mg/kg) dissolved in Intralipid and the plasma concentration of the radiolabel was determined 10 h following the dose. FM-VP4 30-day treatment did not alter body weight, morning glucose, insulin, lipids, and leptin concentrations. There was no alteration in glucose tolerance in the nondiabetic, normoglycemic lean group; however, there was a highly significant improvement in glucose tolerance in the fatty group following FM-VP4 treatment. In addition, the insulin response to oral glucose showed no significant change in nondiabetic lean rats, whereas there was a change in the insulin secretory profile in the fatty group following FM-VP4 treatment. Furthermore, following a single oral gavage of FM-VP4 resulted in a significant decrease in the percentage of radiolabeled cholesterol absorbed. These findings suggest that FM-VP4 treatment to fatty Zucker rats could result in increased glucose responsiveness of the insulin secreting pancreatic beta cells. Furthermore, our findings suggest that FM-VP4 may only be effective presystemically. Systemic administration of FM-VP4 is warranted to determine the therapeutic potential of this effect.

Animals↗
PubMed1983

Neonatal tolerance of major histocompatibility complex antigens alters Ir gene control of the cytotoxic T cell response to vaccinia virus.

The K region of H-2 controls the Tc cell response to vaccinia-Db. The Kb, Kd, and Kq alleles allow good Tc cell responses against vaccinia-Db. In contrast, the presence of Kk in H-2 recombinants 2R (Kk,Db) and 4R (Kk,Db) or in F1 hybrids greatly reduces the anti-vaccinia-Db response. The defect does not lie in antigen presentation, as infected 4R cells can stimulate anti-vaccinia-Db Tc cells in vitro. Furthermore, nonresponder animals possess Tc cell precursors for vaccinia-Db, as transfer of F1 nonresponder spleen cells into infected, lethally irradiated responder recipients allowed generation of anti-vaccinia-Db effector Tc cells. Secondary responses to vaccinia-Db can also be obtained in vitro from T cells of 4R animals. Feedback inhibition was excluded in experiments with mixed chimeras in which Kk and Db were expressed on separate cell populations. Neonatal tolerance of B10 animals to Kk suppressed the anti-vaccinia-Db response but did not affect anti-vaccinia-Kb, anti-lymphocytic choriomeningitis virus, or anti-H-2d responses. In cold target competition experiments, H-2k competitors inhibited vaccinia-Db-specific target cell lysis by Tc cells, which suggests that anti-vaccinia-Db and anti-H-2Kk Tc cells may cross-react. Therefore, we propose that the suppressive influence of Kk on anti-vaccinia-Db Tc cell responses is a consequence of self-tolerance and that suppression of anti-Kk Tc cells results in cross-reactive suppression of anti-vaccinia-Db Tc cells.

Animals↗
PubMed1988

Tolerance of Scottish National Blood Transfusion Service intravenous immunoglobulin in patients with primary hypogammaglobulinaemia: report of 1235 infusions.

A total of 1235 immunoglobulin infusions were carried out as replacement therapy in 37 patients suffering from primary hypogammaglobulinaemia from 1983 to 1987, using Scottish National Blood Transfusion Service (SNBTS) IV IgG, manufactured by cold ethanol fractionation of plasma, ultrafiltration and mild pepsin proteolysis at pH4. Ten patients experienced adverse reactions during 34 infusions (2.8% of all infusions) and all but five were mild; 21 (62%) of the adverse reactions were encountered in the patients' first five infusions. A maximum immunoglobulin infusion rate of 5 mg/kg/min was tolerated without adverse reaction.

Adolescent↗
PubMed1988

Glycerol metabolism in a freeze-tolerant arctic insect: an in vivo 13C NMR study.

Freeze-tolerance in larvae of Gynaephora groenlandica is enhanced by the accumulation of glycerol in the winter. Since summer larvae remain freeze-tolerant despite the lack of glycerol, we investigated glycerol metabolism as a function of acclimation and body temperature using noninvasive 13C NMR spectroscopy. Major constituents of hemolymph isolated from cold- and warm-acclimated larvae were identified with the aid of standard NMR spectra and confirmed by TLC and GLC. Spectra obtained on live, warm-acclimated larvae showed the presence of lipids, glycogen, glucose, trehalose and amino acids. Similar spectra of cold-acclimated or previously frozen larvae showed the additional presence of glycerol. In vitro time-lapse 13C spectra of D-[1-13C]glucose added separately to hemolymph or extracted fat body tissue showed that glycerol is synthesized from glucose in the fat body tissue and distributed to the peripheral tissue via hemolymph. In vivo time-lapse 13C spectra of cold- and warm-acclimated larvae were obtained after injection with D-[1-13C]glucose to monitor the production of labeled metabolic intermediates and end-products. [13C]Glycerol was produced between -30 degrees C and 30 degrees C but accumulated only below 5 degrees C. Above 5 degrees C glycerol was degraded and the 13C label incorporated mainly into glycogen. The mechanism underlying temperature control of glycerol biosynthesis and degradation may provide a clue to the role of glycerol in enhancing freeze-tolerance in these insects.

Acclimatization↗
PubMed2005

Subjective outcomes following sural nerve harvest.

PURPOSE: The goal of this study was to assess subjective patient recovery of donor site sensory deficit following sural nerve harvest for trigeminal nerve repair surgery. PATIENTS AND METHODS: A review of 42 consecutive sural nerve graft patient records yielded 26 patients, at least 20 months following sural nerve grafting for trigeminal nerve repair, who participated in a telephone questionnaire survey to assess subjective outcomes. The association between donor site outcome and other factors, including nerve graft recovery, age, gender, pain, cold sensitivity, scar cosmesis and tactile sensitivity, and legal involvement were analyzed, and presurgical and present levels of donor and nerve graft site sensibility were compared. RESULTS: The perceived area of donor site sensory deficit decreased significantly over time. Postoperative donor site pain and cold sensitivity at low levels were reported by few patients, and the majority have completely resolved. Most patients reported no problems with scar cosmesis or pain. There was a moderate agreement between donor site recovery and nerve graft recovery (kappa = 0.32). Few patients reported satisfaction with one site and not the other or complete dissatisfaction with both sites. Other factors such as age, gender, or legal involvement were not found to correlate with satisfaction level. CONCLUSIONS: The use of a questionnaire for subjective assessment of neurosensory recovery following nerve graft repair yields outcomes information that is generally not considered in the traditional clinical patient assessment. The majority of patients tolerate sural nerve harvest without significant donor site morbidity.

Adult↗
PubMed1995

Usefulness of R-R interval and its variability in evaluation of thermal comfort.

The use of R-R interval and the coefficient of variation in R-R intervals (CVR-R) for the evaluation of thermal comfort was investigated. The experiments were carried out with ten male subjects but data from one were excluded from the analysis. Thermal sensation, comfort, and tolerance of environmental conditions were reported and mean skin temperature, R-R interval and CVR-R were monitored during a 3 h period in a climatic chamber with the operative temperature set at 26, 20, or 30 degrees C. Relative humidity was maintained at ca. 50% in each case. At the operative temperature of 20 degrees C, the mean skin temperature was significantly lower, the cold sensation was significantly more intense, and discomfort was significantly greater than at 26 degrees C and R-R interval was increased significantly. Seven of the nine subjects were unable to tolerate this thermal environment. The R-R interval and CVR-R were increased in five and four of those seven subjects, respectively. At the operative temperature of 30 degrees C, the mean skin temperature was significantly higher, and the sensation of warmth was significantly more intense than at 26 degrees C. Seven of the nine subjects felt discomfort, and four of the seven reported an inability to tolerate this thermal environment. The R-R interval and CVR-R were decreased in four and three of these four subjects, respectively. At the operative temperature of 20 degrees C CVR-R was significantly greater than that at 30 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1994

[Differences in the mechanisms of damage to Kupffer cells and liver endothelial cells during preservation in UW solution].

AIM OF THE STUDY: The predominant injury during cold preservation of the liver appears to affect the non-parenchymal cells. Therefore we studied the contribution of hypoxia and the effect of the University of Wisconsin (UW) solution on the injury to cultured liver endothelial and Kupffer cells. METHODS: Cultured endothelial cells and Kupffer cells of the rat liver were incubated in Krebs-Henseleit buffer at 37 degrees C and in both, Krebs-Henseleit buffer and UW solution, at 4 degrees C. Hypoxic conditions were simulated by the addition of cyanide (1 mM), to some of the cultures glucose (10 mM) was added. Cell injury was assessed by the uptake of the vital dye trypan blue and by the release of cytosolic lactate dehydrogenase. RESULTS: Kupffer cells as well as endothelial cells exhibited a high hypoxia tolerance in Krebs-Henseleit buffer at both 37 degrees C and 4 degrees C. A large difference between both cell types, however, was seen during cold incubation in UW solution: whereas only 35 +/- 10% of Kupffer cells lost viability during 24 hrs under aerobic control conditions, the loss of viability of liver endothelial cells was already 83 +/- 12% under the same conditions. The addition of KCN increased the Kupffer cell injury to 75 +/- 8% but strongly decreased the endothelial cell injury to 3 +/- 2%. The addition of glucose to the cyanide-containing UW solution decreased the injury to Kupffer cells but increased the injury to endothelial cells. CONCLUSION: During cold incubation in UW solution cultured liver endothelial cells are affected by an energy-dependent injury. This type of injury is not detectable in Kupffer cells.

Adenosine↗
PubMed1997

Critical thermal limits, temperature tolerance and water balance of a sub-Antarctic caterpillar, Pringleophaga marioni (Lepidoptera: Tineidae).

Thermal tolerance, supercooling point, water balance and osmoregulatory ability of Pringleophaga marioni Viette (Lepidoptera: Tineidae) are investigated in this study. Field-fresh larvae had a mean CT(Min) (cold stupor) of -0.6 degrees C and a mean CT(Max) (heat coma) of 38.7 degrees C. The mean supercooling point of field-fresh individuals was -5.0 degrees C. Caterpillars showed 100% survival of freezing to -6.5 degrees C, but at -12 degrees C mortality rose to 100%. Survival of a 30h exposure to -6.0 degrees C was 80%, but declined to 30% in the 6-12h interval at -7.5 degrees C. No caterpillars survived for longer than 12h at -9.0 degrees C. Survival of high temperatures (35 degrees C and above) was poor. Tolerance of water loss (46% of fresh mass) and rates of water loss (1% fresh massh(-1)) were similar to those found in other mesic insects. P. marioni larvae were incapable of metabolizing lipids to replenish lost water and showed no haemolymph osmoregulatory ability. It is suggested that the preponderance of freeze tolerance in high-latitude southern hemisphere species may be associated with their occurrence in moist habitats, and that the "freeze tolerance" category be re-examined in the light of the range of strategies adopted by such arthropods.

Journal Article↗