SEARCH · PubMed Health

Results for “Cold Temperature”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources

PubMed1999

Blood flow to the brown adipose tissue of conscious young rabbits during hypoxia in cold and warm conditions.

Brown adipose tissue (BAT) non-shivering thermogenesis is stimulated by cold temperature and depressed by hypoxia. We investigated the extent to which changes in metabolic rate during cold and hypoxia, singly or combined, were accompanied by changes in BAT perfusion. One-month-old rabbits were instrumented for measurements of regional blood flow by the coloured microsphere technique. One group of rabbits was tested in warm (24 degrees C, n=17), and the other in cold (13 degrees C, n=9) conditions, first in normoxia (inspired oxygen concentration FIO2 about 21%, arterial oxygen saturation SaO2 approximately 88%) followed by hypoxia (FIO2 approximately 10%, SaO2 approximately 54%). In warm conditions, oxygen consumption (VO2, measured by an open-flow method) averaged 22 ml.kg-1.min-1 (STPD), and BAT blood flow 98 ml.100g-1.min-1. In hypoxia, VO2 dropped on average to 87%, whereas BAT flow dropped to 43% of the normoxic values. In the cold during normoxia, VO2 averaged 31 ml.kg-1.min-1 (STPD), and BAT blood flow was 155 ml.100g-1.min-1. In cold and hypoxia VO2 dropped to 19 ml.kg-1.min-1 (STPD) (i.e. 60% of the normoxic value), whereas BAT blood flow was not altered significantly (148 ml.100g-1.min-1). Hence, BAT blood flow decreased in hypoxia in absence of cold stimuli, whereas it remained high when hypoxia occurred during cold, despite the major drop in VO2. We conclude that cold is more important than hypoxia in determining BAT perfusion, and that changes in BAT blood flow are not a mechanism for the hypoxic control of V.O2.

Adipose Tissue, Brown↗

PubMed2005

Selection strategies for body weight and reduced ascites susceptibility in broilers.

Ascites syndrome is a metabolic disorder in broilers. Mortality due to ascites results in significant economic losses and has a negative impact on animal welfare. It has been shown that genetic factors play a considerable role in susceptibility of birds to ascites, which offers perspectives for selection against this syndrome. The aim of the present study was to evaluate the consequences of alternative selection strategies for BW and resistance to ascites syndrome using deterministic simulation. In addition to the consequences of current selection (i.e., selection for increased BW only) alternative selection strategies including information on different ascites-related traits measured under normal or cold conditions and the consequences of having information on the underlying genes (i.e., MAS) were quantified. Five different breeding schemes were compared based on the selection response for BW, ascites susceptibility, and the rate of inbreeding. Traits investigated in the index as indicators for ascites were hematocrit value (HCT) and ratio of right ventricle to the total ventricular weight of the heart (RV:TV). The results indicated that by ignoring ascites susceptibility in the breeding goal, the gain for BW is 130 g and the birds will become more susceptible to ascites. Testing 50% of the birds under cold temperature conditions and including information of ascites related traits (HCT and RV:TV) measured under normal and cold conditions makes it possible to achieve a relatively high gain for BW (111.4 g) while controlling the genetic level for ascites susceptibility (selection response was 0). The results of scenarios including QTL information of ascites susceptibility showed that QTL information could be used very effectively in controlling ascites susceptibility.

Animals↗

PubMed1998

Differential sensory block: spinal vs epidural with lidocaine.

PURPOSE: In this study we sought to determine if and when a difference exists with regards to differential sensory blockade between spinal and epidural anaesthesia using lidocaine. METHODS: Ten healthy volunteers were randomly assigned to receive both spinal and epidural anaesthesia. Non-epinephrine containing solutions of lidocaine, 100 mg lidocaine 5% with 7.5% dextrose (spinal) and 600 mg lidocaine 2% (epidural), were used to establish sensory blockade. At five minute intervals, for a total of 65 min, the following sensory modalities were tested: anaesthesia (complete loss of sensation to pinprick), analgesia (loss of an equally sharp sensation to pinprick compared with that at an unblocked dermatome), cold sensation (complete loss of cold temperature discrimination). RESULTS: At all times, except at time = 0 during spinal anaesthesia, the levels of analgesia and cold sensation were more cephalad than the level of anaesthesia for both spinal and epidural anaesthesia. Multiple comparison testing among the three dermatomal response levels showed that, during epidural anaesthesia, the level of analgesia was more cephalad than the level of cold sensation at the following times: 25 min, 30 min, and from 40 to 60 min. In contrast, the level of analgesia was not different from the level of cold sensation during spinal anaesthesia. CONCLUSIONS: Spinal and epidural anaesthesia with lidocaine produce a similar degree of differential sensory blockade. Epidural anaesthesia produces a detectable difference between the level of analgesia and cold sensation at various times, whereas spinal anaesthesia did not reliably do so in this study.

Adult↗

PubMed2003

A single recessive mutation in the proteolytic machinery of Arabidopsis chloroplasts impairs photoprotection and photosynthesis upon cold stress.

Intracellular proteases, together with molecular chaperones, are components of the cellular protein quality control system. Although the identity of chloroplast proteases has been revealed in recent years, little is known about their regulation. As a first step towards identifying unknown functional or regulatory components of the chloroplast proteolytic machinery, a genetic screen was devised with the aim of generating Arabidopsis thaliana (L.) Heynh. mutants impaired in chloroplast protein degradation. A streptomycin-resistance gene was fused to a cDNA construct that encodes an unstable mutant of the OE33 protein. This chimeric gene was used for transforming Arabidopsis plants. Analysis of transgenic plants revealed a correlation between streptomycin resistance and accumulation of the recombinant fusion protein. Seeds from transgenic plants that were sensitive to streptomycin were chemically mutagenized and screened for resistance to streptomycin. Such resistance could be due to stabilization of the protein caused by a mutation in the chloroplast proteolytic machinery. Genetic analysis of one of the mutants showed the mutation to be recessive, in a single nuclear gene. Further characterization of the mutant revealed that it was not a result of increased transcription of the transgene. Moreover, chloroplast lysates from the mutant plant showed decreased ATP-dependent degradation of a chloroplast protein substrate, consistent with the conclusion that the mutation impaired the proteolytic machinery. Physiological analysis revealed that upon cold stress, photoprotection and photosynthesis in the mutant was inhibited, suggesting that the chloroplast proteolytic machinery is involved in repairing damage incurred to the photosynthetic machinery upon exposure to cold temperatures.

Acclimatization↗

PubMed1997

Pyrophosphorylases in potato. V. Allelic polymorphism of UDP-glucose pyrophosphorylase in potato cultivars and its association with tuber resistance to sweetening in the cold.

UDP-glucose pyrophosphorylase (UGPase) was cloned from six American and nine European potato (Solanum tuberosum L.) cultivars. Restriction mapping of the different UGPase-cDNAs with BamHI, HindIII, and EcoRI revealed that at least two mRNA populations were present in most cultivars. Staining for UGPase activity in nondenaturing gels of proteins extracted from developing potato tubers yielded two major isozymes that were highly active and appeared to be dimeric in nature. Following sodium dodecyl sulfate-polyacrylamide gel electrophoresis, all isozymes were disassociated into a single subunit with a molecular mass of 53 kD. Since UGPase has been demonstrated to be a single-copy gene in the haploid genome of potato (A.Y. Borovkov, P.E. McClean, J.R. Sowokinos, S.H. Ruud, G.A. Secor [1995] J Plant Physiol 147: 644-652), there must be allelic differences at the UGPase locus (chromosome 11). The two alleles, designated ugpA and ugpB, were identified by the absence and presence of a BamHI site, respectively. The relative band intensities of the two cDNA populations following polymerase chain reaction amplification and agarose gel electrophoresis were related to a potato cultivar's ability to resist sweetening when exposed to cold temperatures.

Alleles↗

PubMedDate not supplied

Effects of diet temperature on tolerance of enteral feedings.

Nasogastric tube feedings administered at three temperatures were studied for effect on gastric motility, total gastrointestinal transit time, diarrhea, and subjective sensations in normal volunteers. Following a period of base-line observation, six volunteers received tube feedings at one of three temperatures: cold (8-11 degrees C), room (23-26 degrees C), or warm (36-39 degrees C). There was no significant difference between the temperature of the feeding and gastric motility patterns in selected postfeeding periods. Administration of diets at all three temperatures resulted in a similar decrease in the frequency of gastric contraction and similar patterns of return of gastric activity. After cold feedings two subjects experienced cramping accompanied by diarrhea. No gastrointestinal disturbances were reported following warmer infusions.

Cold Temperature↗

PubMed2004

Cell-based assay for the determination of temperature sensitive and cold adapted phenotypes of influenza viruses.

The determination of temperature sensitive (ts) and cold adapted (ca) phenotype for influenza A and B strains has been conducted traditionally using embryonated chicken eggs. As attempts are made to move away from the use of eggs in the manufacturing process of influenza vaccines, it will become useful to develop cell-based assays to support cell culture-based vaccine production. In this study, MDCK cells have been evaluated as a tool for determining the ts and ca phenotypes associated with live attenuated influenza viruses. Direct comparisons were made of these phenotypes carried out in eggs. Reassortants made from the Russian live attenuated influenza donor strains A/Leningrad/134/17/57 (H2N2) and B/USSR/60/69 were prepared entirely in MDCK cells and their phenotypes evaluated using the MDCK cell-based assay. It is concluded that MDCK cells are more sensitive than eggs for the measurement of ts and ca phenotype of influenza viruses (particularly for influenza A) and they provide an alternative means for screening candidate reassortants prior to determining their genome composition.

Animals↗

PubMed1994

Intrinsic microtubule stability in interphase cells.

Interphase microtubule arrays are dynamic in intact cells under normal conditions and for this reason they are currently assumed to be composed of polymers that are intrinsically labile, with dynamics that correspond to the behavior of microtubules assembled in vitro from purified tubulin preparations. Here, we propose that this apparent lability is due to the activity of regulatory effectors that modify otherwise stable polymers in the living cell. We demonstrate that there is an intrinsic stability in the microtubule network in a variety of fibroblast and epithelial cells. In the absence of regulatory factors, fibroblast cell interphase microtubules are for the most part resistant to cold temperature exposure, to dilution-induced disassembly and to nocodazole-induced disassembly. In epithelial cells, microtubules are cold-labile, but otherwise similar in behavior to polymers observed in fibroblast cells. Factors that regulate stability of microtubules appear to include Ca2+ and the p34cdc2 protein kinase. Indeed, this kinase induced complete destabilization of microtubules when applied to lysed cells, while a variety of other protein kinases were ineffective. This suggests that p34cdc2, or a kinase of similar specificity, may phosphorylate and inactivate microtubule-associated proteins, thereby conferring lability to otherwise length-wise stabilized microtubules.

3T3 Cells↗

PubMed1985

Cold sensitivity induced by overproduction of UmuDC in Escherichia coli.

The UmuD and UmuC proteins of Escherichia coli are essential for mutagenesis by UV and most chemicals. Their mode of action is presently unknown. Strains which lack the LexA repressor [lexA(Def)] and contain a pBR322-derived plasmid carrying the umuDC operon overexpress UmuD and UmuC and become cold sensitive (growth at 42 degrees C but not at 30 degrees C). Deletion mapping showed that the umuDC locus on the plasmid is responsible for conferring cold sensitivity. The conditional lethality appeared due to a rapid and reversible inhibition of DNA synthesis at the nonpermissive temperature. Cold sensitivity was enhanced by the increase of NaCl in the medium to 1% and eliminated by 4% ethanol in the medium. Cold sensitivity was partially suppressed by the lon-100 mutation and completely suppressed by the htpR165 mutation.

Bacterial Proteins↗

PubMed2005

Impact of control for air pollution and respiratory epidemics on the estimated associations of temperature and daily mortality.

We assessed the influence of control for air pollution and respiratory epidemics on associations between apparent temperature (AT) and daily mortality in Mexico City and Monterrey. Poisson regressions were fit to mortality among all ages, children (ages 0-14 years) and the elderly (ages >or=65 years). Predictors included mean daily AT, season, day of week and public holidays for the base model. Respiratory epidemics and air pollution (particulate matter <10 microm in aerodynamic diameter and O3) were added singly and then jointly for a fully adjusted model. Percent changes in mortality were calculated for days of relatively extreme temperatures [cold (10-11 degrees C) for both cities and heat (35-36 degrees C) for Monterrey], compared to days at the overall mean temperature in each city (15 degrees C in Mexico City, 25 degrees C in Monterrey). In Mexico City, total mortality increased 12.4% [95% confidence interval (CI) 10.5%, 14.5%] on cold days (fully adjusted). Among children, the adjusted association was similar [10.9% (95% CI: 5.4%, 16.7%)], but without control for pollution and epidemics, was nearly twice as large [19.7% (95% CI: 13.9%, 25.9)]. In Monterrey, the fully adjusted heat effect for all deaths was 18.7% (95% CI: 11.7%, 26.1%), a third lower than the unadjusted estimate; the heat effect was lower among children [5.5% (95% CI: -10.1%, 23.8%)]. Cold had a similar effect on all-age mortality as in Mexico City [11.7% (95% CI: 3.7%, 20.3%)]. Responses of the elderly differed little from all-ages responses in both cities. Associations between weather and health persisted even with control for air pollution and respiratory epidemics in two Mexican cities, but risk assessments and climate change adaptation programs are best informed by analyses that account for these potential confounders.

Adolescent↗

PubMed2000

Thermal stimulation of taste.

The first electrophysiological recordings from animal and human taste nerves gave clear evidence of thermal sensitivity, and studies have shown that as many as half of the neurons in mammalian taste pathways respond to temperature. Because temperature has never been shown to induce sensations of taste, it has been assumed that thermal stimulation in the gustatory system is somehow nulled. Here we show that heating or cooling small areas of the tongue can in fact cause sensations of taste: warming the anterior edge of the tongue (chorda tympani nerve) from a cold temperature can evoke sweetness, whereas cooling can evoke sourness and/or saltiness. Thermal taste also occurs on the rear of the tongue (glossopharyngeal nerve), but the relationship between temperature and taste is different there than on the front of the tongue. These observations indicate the human gustatory system contains several different types of thermally sensitive neurons that normally contribute to the sensory code for taste.

Body Temperature↗

PubMed1994

Effects of hypothermia upon endothelial cells: mechanisms and clinical importance.

The endothelial cell is vital in the regulation of blood vessel wall structure, vasomotor tone, and thrombogenicity. Hypothermic temperatures alter both the physiological and biochemical dynamics of endothelial cells. However, there has been no systematic investigation of the influence of cold temperatures upon endothelial cell biology. This review summarizes the current clinical areas of interests, identifies the problems, and addresses the fundamental requirement for further research in endothelial cell cryobiology.

Animals↗

PubMed1994

Temperature acceleration in cold oral stimulation.

This study measured the temperature acceleration of a cold probe as it contacts human tissue. Both the effects of touching a cold probe to the oral cavity were investigated. The results indicated a rapid warming pattern. This warming is effected first by temperature changes resulting from the probe being moved from ice into room temperature and second by the contact to oral mucosa. In fact, in some cases, the probe had reached minimal cold sensation levels by the time it reached the oral cavity. Results also indicated that 6 sec after the probe is lifted from the ice, the temperature closely approximates temperatures perceived as warm or at least neutral, but not cold.

Body Temperature↗

PubMed2004

Cold-sensitive, menthol-insensitive neurons in the murine sympathetic nervous system.

Several mechanisms have been implicated in underlying the perception of cold, most notably the activation of TRPM8 and TRPA1. We have used ratiometric calcium imaging to reveal a population of neurons in the superior cervical ganglion (SCG) of the mouse that respond to cooling but are insensitive to menthol. Furthermore we show that the expression of the mRNA transcripts encoding the recently identified noxious cold-sensitive channel TRPA1 but not TRPM8 are expressed in the SCG. These data provide evidence for a population of cold-responsive neurons in the SCG whose cold-responsiveness could be mediated by the activation of TRPA1 and suggest that the sympathetic nervous system may play a direct role in mediating sympathetic responses to cold temperatures.

Animals↗

PubMed2005

The alternative oxidase of plant mitochondria is involved in the acclimation of shoot growth at low temperature. A study of Arabidopsis AOX1a transgenic plants.

The alternative oxidase (AOX) pathway of plant mitochondria uncouples respiration from mitochondrial ATP production and may ameliorate plant performance under stressful environmental conditions, such as cold temperatures, by preventing excess accumulation of reactive oxygen species. We tested this model in whole tissues by growing AtAOX1a-transformed Arabidopsis (Arabidopsis thaliana) plants at 12 degrees C. For the first time, to our knowledge, in plants genetically engineered for AOX, we identified a vegetative shoot growth phenotype. Compared with wild type at day 21 after sowing, anti-sense and overexpressing lines showed, on average, 27% reduced leaf area and 25% smaller rosettes versus 30% increased leaf area and 33% larger rosette size, respectively. Lines overexpressing a mutated, constitutively active AOX1a showed smaller phenotypic effects. These phenotypic differences were not the result of a major alteration of the tissue redox state because the changes in levels of lipid peroxidation products, reflecting oxidative damage, and the expression of genes encoding antioxidant and electron transfer chain redox enzymes did not correspond with the shoot phenotypes. However, the observed phenotypes were correlated with the amount of total shoot anthocyanin at low temperature and with the transcription of the flavonoid pathway genes PAL1 and CHS. These results demonstrate that (1) AOX activity plays a role in shoot acclimation to low temperature in Arabidopsis, and that (2) AOX not only functions to prevent excess reactive oxygen species formation in whole tissues under stressful environmental conditions but also affects metabolism through more pervasive effects, including some that are extramitochondrial.

Acclimatization↗

PubMed2005

Relationship between heat shock protein levels and infectivity in Trichinella spiralis larvae exposed to different stressors.

The aim of the present study was to investigate the relationship between infectivity and the levels of two major heat shock proteins (Hsp70 and Hsp60) in Trichinella spiralis larvae. Parasites were exposed to either sublethal thermal stress (43 and 45 degrees C) or to warm or cold temperature oxidative stress. The stressed larvae were then inoculated into female CD1 mice to determine their infectivity. Hsps were detected and quantified by Western blotting using monoclonal antibodies. Infectivity was expressed as larvae per gram of muscle. Warm temperature oxidative stress (20 mM H2O2 at 37 degrees C) caused a significant increase in Hsp levels and total loss of infectivity. Cold oxidative stress (20 mM H2O2 at 4 degrees C) caused no alterations in either Hsp levels or infectivity. However, high oxidative stress and cold (200 mM H2O2 at 4 degrees C) caused a slight increase in Hsp60 levels and a drastic reduction in infectivity. Exposure of the larvae to 43 or 45 degrees C did not significantly alter Hsp levels or infectivity. These results show that (i) cold reduces the deleterious effects of oxidative stress; (ii) heat induces neither increased Hsp60/Hsp70 levels nor reduces infectivity; (iii) increased Hsp levels induced by oxidative stress may cause lower infectivity.

Animals↗

PubMed1997

The pathogenesis of non-freezing cold nerve injury. Observations in the rat.

Non-freezing cold nerve injury is uncommon in civilian practice, but may reach epidemic proportions in war zones. Studied since the time of Hippocrates, its aetiology has remained elusive. We sought to replicate experimentally, a peripheral nerve cold temperature gradient, since this has been emphasized in clinical descriptions. Our observations, in the rat, of the vasa nervorum show that cold-induced intravascular aggregation is followed by a 'no-reflow' phenomenon which culminates in endothelial damage and delayed thrombotic occlusion.

Animals↗

PubMed1992

Extracellular protease from the antarctic yeast Candida humicola.

The psychrotrophic, dimorphic yeast Candida humicola, isolated from Antarctic soil, secretes an acidic protease into the medium. The secretion of this protease by C. humicola was found to be dependent on the composition of the medium. In YPD or yeast nitrogen base medium containing either amino acids or ammonium sulfate as the nitrogen source, the activity of the protease in the medium was low (basal level). However, when yeast nitrogen base medium was depleted of amino acids or ammonium sulfate and supplemented with proteins, the activity of the enzyme increased. The secretion of the enzyme was greater during exponential growth at low temperatures than during growth at higher temperatures. The purified protease had a molecular mass of 36,000 Da and was inhibited by pepstatin, iodoacetamide, and sodium dodecyl sulfate. Despite the prevalent cold temperatures in Antarctica, this extracellular protease of the psychrotrophic yeast C. humicola was active at temperatures ranging from 0 to 45 degrees C, with an optimum activity at 37 degrees C.

Adaptation, Physiological↗