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At least 163 records · Page 9Linked to original sources
PubMed1988

Aprotic polar solvents that affect porcine brain tubulin aggregation in vitro induce aneuploidy in yeast cells growing at low temperatures.

Seven aprotic polar solvents which had previously been shown to interfere with the aggregation in vitro of porcine brain tubulin have been examined for their ability to induce mitotic aneuploidy in Saccharomyces cerevisiae in relation to temperature during exposure. Induction of aneuploidy was in general considerably enhanced when incubation at 28 degrees C was interrupted by overnight storage at low temperature (cold shock). The optimum cold-shock temperatures for individual chemicals varied over a range of 0-16 degrees C. While storage at reduced temperature enhanced the effect of treatment at 28 degrees C, it was also shown that continuous incubation at reduced temperature could greatly enhance the induction of aneuploidy. Only 2 chemicals, 1-methyl-2-pyrrolidinone and gamma-valerolactone, required cold shock to yield a positive response. The other chemicals did not require cold shock for enhanced induction. The observation that the agents examined also interfere with in vitro tubulin aggregation suggests that there is a temperature component to the interaction of these agents with tubulin in vivo. This temperature component is unusual in that the most effective temperature range for aneuploidy induction can be well below the optimal growth temperature for the test organism.

Aneuploidy↗
PubMed2005

Cold temperature-induced modifications to the composition and structure of the lipopolysaccharide of Yersinia pestis.

Following a report of variations in the lipopolysaccharide (LPS) structure of Yersinia pestis at mammalian (37 degrees C) and flea (25 degrees C) temperatures, a number of changes to the LPS structure were observed when the bacterium was cultivated at a temperature of winter-hibernating rodents (6 degrees C). In addition to one of the known Y. pestis LPS types, LPS of a new type was isolated from Y. pestis KM218 grown at 6 degrees C. The core of the latter differs in: (i) replacement of terminal galactose with terminal d-glycero-d-manno-heptose; (ii) phosphorylation of terminal oct-2-ulosonic acid with phosphoethanolamine; (iii) a lower content of GlcNAc, and; (iv) the absence of glycine; lipid A differs in the lack of any 4-amino-4-deoxyarabinose and presumably partial (di)oxygenation of a fatty acid(s). The data obtained suggest that cold temperature switches on an alternative mechanism of control of the synthesis of Y. pestis LPS.

Carbohydrate Sequence↗
PubMed2006

[Study of organosulfur compounds in fresh garlic by gas chromatography/mass spectrometry incorporated with temperature-programmable cold on-column injection].

For the analysis of organosulfur compounds in fresh garlic, a gas chromatographic/mass spectrometric (GC/MS) method is proposed using temperature-programmable cold on-column injection and cold solvent extraction of the fresh garlic. This was carried out under the conditions of cryogenic process from extraction to column separation. Hence, a valid identification can be achieved about the primary components in garlic extract before thermo-degradation. The obtained results showed that 3-vinyl-4H-1, 2-dithiin and 2-vinyl-4H-1, 3-dithiin were the major compounds in the garlic extract with minor amounts of S-methyl methanethiosulfinate, diallyl disulfide, trisulfide-di-2-propenyl. A comparative study of chemical compounds was performed between garlic extract by cold solvent and garlic oil by stream distillation. The degradation and formation of major organosulfur compounds in the garlic extract were also explored.

Allyl Compounds↗
PubMed1986

Effects of skin temperature on cold defense after cutaneous denervation of the trunk.

In intact goats the core temperature threshold below which heat production increases with falling core temperature, is inversely related to the temperature of the water bath in which they stand and is therefore assumed to be indicative of the central integration of signals from skin and core temperature receptors. The present study shows that a difference in core temperature thresholds for bath temperatures of 35 degrees C and 40 degrees C persisted after denervation of about two-thirds of the skin of the trunk and limbs. Also, for a given combination of skin and core temperatures, heat production was as great or greater after cutaneous denervation as before. It is concluded that, following denervation of the trunk and upper limbs, intact temperature receptors in the non-denervated skin of the legs and tail, and/or also in tissues between the skin and core, provide important and significant inputs to the temperature regulating system. But these inputs cannot explain fully the thermoregulatory responses observed unless it is assumed that the thermosensitivity of these tissues increased.

Acclimatization↗
PubMed2002

Effect of cold ambient temperature on palmar sweating response to vibration stress.

We investigated the effect of cold ambient temperature on the palmar sweating response to vibration stress. Ten healthy, male subjects were exposed to eight ambient temperatures (5, 7, 10, 14, 18, 22, 24 and 28 degrees C). At each ambient temperature, each subject gripped the handle of a vibration generator with his left hand with a grasp strength of 49 N. This hand was then exposed to a 125-Hz sinusoidal vibration with an acceleration of 50 m/s(2) (rms) for 3 min at each ambient temperature. Palmar sweating and skin temperature were measured simultaneously on the palm and the fourth finger, respectively, of the subjects' right palm. The palmar sweating response showed a significant change among eight ambient temperatures. The palmar sweating measured at an ambient temperature of 5 degrees C was found to be significantly larger than those measured at 10, 14, 18, 22, 24 and 28 degrees C. Vibration exposure caused a significant increase in the palmar sweating response. Our results suggest that a cold environment plays a significant role in the palmar sweating response to vibration stress.

Adult↗
PubMed2004

Metabolic responses to low temperature in fish muscle.

For most fish, body temperature is very close to that of the habitat. The diversity of thermal habitats exploited by fish as well as their capacity to adapt to thermal change makes them excellent organisms in which to examine the evolutionary and phenotypic responses to temperature. An extensive literature links cold temperatures with enhanced oxidative capacities in fish tissues, particularly skeletal muscle. Closer examination of inter-species comparisons (i.e. the evolutionary perspective) indicates that the proportion of muscle fibres occupied by mitochondria increases at low temperatures, most clearly in moderately active demersal species. Isolated muscle mitochondria show no compensation of protein-specific rates of substrate oxidation during evolutionary adaptation to cold temperatures. During phenotypic cold acclimation, mitochondrial volume density increases in oxidative muscle of some species (striped bass Morone saxatilis, crucian carp Carassius carassius), but remains stable in others (rainbow trout Oncorhynchus mykiss). A role for the mitochondrial reticulum in distributing oxygen through the complex architecture of skeletal muscle fibres may explain mitochondrial proliferation. In rainbow trout, compensatory increases in the protein-specific rates of mitochondrial substrate oxidation maintain constant capacities except at winter extremes. Changes in mitochondrial properties (membrane phospholipids, enzymatic complement and cristae densities) can enhance the oxidative capacity of muscle in the absence of changes in mitochondrial volume density. Changes in the unsaturation of membrane phospholipids are a direct response to temperature and occur in isolated cells. This fundamental response maintains the dynamic phase behaviour of the membrane and adjusts the rates of membrane processes. However, these adjustments may have deleterious consequences. For fish living at low temperatures, the increased polyunsaturation of mitochondrial membranes should raise rates of mitochondrial respiration which would in turn enhance the formation of reactive oxygen species (ROS), increase proton leak and favour peroxidation of these membranes. Minimisation of mitochondrial oxidative capacities in organisms living at low temperatures would reduce such damage.

Acclimatization↗
PubMed1984

Isoproterenol-induced blood flow in rats acclimated to room temperature and cold.

Blood flow was measured with labeled microspheres in cold (6 degrees C)- and room-temperature-acclimated rats at rest and during infusion of the beta-agonist, isoproterenol. Isoproterenol elicited decreased mass-specific blood flows (ml . g-1 . min-1) to liver (55% of control), kidney (48%), and white fat (64%) in room-temperature-acclimated (RT) rats. Blood flow was similarly decreased in liver (51%), kidney (37%), and white fat (70%) in cold-acclimated (CA) rats. In contrast, isoproterenol increased blood flows to brown fat and cardiac and skeletal muscles. The blood flows to cardiac muscle during isoproterenol infusion were comparable in both RT (12.7 ml . g-1 . min-1) and CA (11.7 ml . g-1 . min-1) animals, representing increases of 2.9- and 2.6-fold above control values, respectively. Blood flow to skeletal muscle was also similarly elevated in RT and CA animals, representing increases 5.9 and 5.6 times those of their respective control values. In contrast, although isoproterenol greatly stimulated (ca. 8-fold) blood flow to brown fat (interscapular plus cervical depots) in RT animals, it had a greater effect on these two depots in the CA rats (18-fold increase). These data emphasize the importance of brown fat as a major effector of nonshivering thermogenesis as well as the importance of beta-adrenergic receptors in mediating the metabolic response of nonshivering thermogenesis.

Acclimatization↗
PubMed2005

Evaluation of different temperatures in cold air cooling with pulsed-dye laser treatment of facial telangiectasia.

BACKGROUND AND OBJECTIVES: Cold air cooling is widely used in dermatological laser therapy. We investigated the influence of cold air cooling at different skin temperatures on therapeutic outcome and side effects of pulsed dye laser treatment of facial telangiectasia. STUDY DESIGN/MATERIALS AND METHODS: From September 2002 to February 2003, 17 patients with previously untreated facial telangiectasia underwent a single treatment session with flash-lamp pulsed dye laser (3.5 J/cm(2), 585 nm, 0.45 milliseconds pulse length, 10 mm beam diameter, Cynosure V). The treatment area was divided into three sub-areas: no cooling, cold air cooling to 20 degrees C and to 17 degrees C skin temperature. The skin temperature was monitored by a prototype infrared sensor system which controlled the temperature of the cold air stream (Cryo5). In a prospective study, we collected data on purpura, pain, clearance, and patient satisfaction on numerical analog scales (NAS) from 0 (meaning "no") to 3 (meaning "high"). RESULTS: Without cooling, purpura (2.53), pain (2.41), and clearance (2.35) were rated medium to high. Cooling to 20 degrees C reduced purpura (1.12) and pain (1.06), whereas the clearance (2.12) was only slightly affected. Cooling to 17 degrees C reduced purpura (0.88) and pain (0.76) even more, the clearance (2.06) was lowered marginally. Most patients preferred cooling to 20 degrees C skin temperature. CONCLUSION: In dermatological laser therapy of facial telangiectasia, the use of cold air cooling can significantly reduce side effects and increase patient satisfaction while only slightly affecting clearance. Cooling to 20 degrees C skin temperature proved to be a well-balanced middle course. For the practical use of cold air cooling, we thus recommend cooling to a level which the patient can tolerate without problems and to try to increase the energy densities.

Adult↗
PubMed1986

Age comparisons of body temperature and cold tolerance among different strains of Mus musculus.

The age-related declines in colonic temperature (Tco) and cold tolerance (ability to maintain Tco when exposed to 10 degrees C for 3 h) described for C57BL/6J mice are compared to other mouse strains. Assessment of young and aged male mice of the C57BL/6J and A/J inbred strains and their F1 hybrid, B6AF1/J, as well as a pen-bred strain of Mus musculus captured from the wild revealed an aged-related decline in thermoregulation among all these strains. The degree of decline in thermoregulation was roughly correlated to differences in strain-specific lifespan. Aged mice of the relatively short-lived genotype, A/J (mean lifespan of 22 months), had the lowest Tco and poorest cold tolerance. The long-lived hybrids, B6AF1/J (mean lifespan of 29 months), demonstrated the highest Tco and the best cold tolerance among aged mice. C57BL/6J (mean lifespan of 26 months) showed an intermediate level of thermoregulation. Aged pen-bred mice demonstrated a significant decline in cold tolerance, but not a significant decline in Tco. The thermoregulatory responses of the pen-bred mice were superior to those observed among the domesticated strains. These data suggest that the age-related impairment in thermoregulation is a general phenomenon of aging in Mus musculus that is correlated with strain-specific lifespan but is possibly affected by the level of hybridization and domestication.

Aging↗
PubMed2006

Influence of long-term stability conditions on microbicidal nucleoside prodrug (WHI-07)-loaded gel-microemulsion.

The objective of this study was to evaluate the long-term stability of the antiretroviral spermicide WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate) in a polymer-based microemulsion. The recovery and stability of WHI-07 in gel-microemulsion was examined by a validated high-performance liquid chromatography (HPLC) method. The stability was examined over a period of 24 weeks at 3 controlled temperatures (4 degrees C, 25 degrees C, and 40 degrees C). The recovery of the prodrug from 0.5% to 2.0% WHI-07-loaded gel-microemulsion was 99.8%. HPLC analysis revealed that a 2% WHI-07-loaded gel-microemulsion stored at room temperature and cold temperatures for 24 weeks retained >90% of the prodrug, whereas those stored at 40 degrees C maintained 90% of initial WHI-07 for at least 10 weeks. The observed stability of WHI-07 in gel-microemulsion is of great importance for its widespread utility in various climatological conditions.

Dideoxynucleotides↗
PubMed2003

Heat balance precedes stabilization of body temperatures during cold water immersion.

Certain previous studies suggest, as hypothesized herein, that heat balance (i.e., when heat loss is matched by heat production) is attained before stabilization of body temperatures during cold exposure. This phenomenon is explained through a theoretical analysis of heat distribution in the body applied to an experiment involving cold water immersion. Six healthy and fit men (mean +/- SD of age = 37.5 +/- 6.5 yr, height = 1.79 +/- 0.07 m, mass = 81.8 +/- 9.5 kg, body fat = 17.3 +/- 4.2%, maximal O2 uptake = 46.9 +/- 5.5 l/min) were immersed in water ranging from 16.4 to 24.1 degrees C for up to 10 h. Core temperature (Tco) underwent an insignificant transient rise during the first hour of immersion, then declined steadily for several hours, although no subject's Tco reached 35 degrees C. Despite the continued decrease in Tco, shivering had reached a steady state of approximately 2 x resting metabolism. Heat debt peaked at 932 +/- 334 kJ after 2 h of immersion, indicating the attainment of heat balance, but unexpectedly proceeded to decline at approximately 48 kJ/h, indicating a recovery of mean body temperature. These observations were rationalized by introducing a third compartment of the body, comprising fat, connective tissue, muscle, and bone, between the core (viscera and vessels) and skin. Temperature change in this "mid region" can account for the incongruity between the body's heat debt and the changes in only the core and skin temperatures. The mid region temperature decreased by 3.7 +/- 1.1 degrees C at maximal heat debt and increased slowly thereafter. The reversal in heat debt might help explain why shivering drive failed to respond to a continued decrease in Tco, as shivering drive might be modulated by changes in body heat content.

Adipose Tissue↗