SEARCH · PubMed Health

Results for “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 379 records · Page 21Linked to original sources

PubMed1975

Genetic variation of body temperature of Coturnix coturnix in two ambient temperatures.

Coturnix quail were placed in an environmental chamber maintained at 21 degree C. and rectal temperatures taken. The birds were subjected to an abrupt change to 36 degree C. and the temperatures taken hourly for eight hours and at 25, 38 and 72 hours. Females had higher temperatures than males. When birds were moved to 36 degrees C. their temperatures rose rapidly and then dropped to a level higher than when birds were in the 21 degrees C. chamber. The genetic and total variation estimated from the analysis of variance method decreased under this sudden thermal stress condition. Birds kept in 36 degrees C. for three weeks were shifted to 21 degrees C. Their body temperature dropped sharply and then increased to a level lower than that obtained in the 36 degrees C. environment. The genetic variation was essentially zero when shifted to a lower temperature while the total variation increased.

Animals↗

PubMed2004

[Effects of SP-6 acupressure on dysmenorrhea, skin temperature of CV2 acupoint and temperature, in the college students].

PURPOSE: The purpose of this study was to identify effects of the SP-6 acupressure on dysmenorrhea, the skin temperature of the CV2 acupoint and oral temperatures in the college students. METHOD: Data was collected from May 1 to August 31, 2002. A total of 58 students from two universities participated in the study. Both groups were pretested before the intervention for three variables', the intensity of dysmenorrhea, skin temperature of the CV2 acupoint and oral temperature. Then, SP-6 acupressure was provided for 20 minutes for students in the experimental group. The instruments used in this study included the Visual Analogue Scale developed by Johnson & Rice(1974), Menstrual Attitudes Questionnaire Scale developed by Brooks-Gunn & Ruble(1980), and a Stress scale developed by Cheun and Kim(1991). RESULT: There were statistically significant differences in the intensity of dysmenorrhea 30 minutes after the intervention. The experimental group had a lower intensity than the control group. There were not statistically significant differences in skin temperature of the CV2 acupoint and oral temperature 30 minutes after the intervention with the experimental group. CONCLUSION: SP-6 acupressure reduced the subjective perception of dysmenorrhea.

Acupressure↗

PubMedDate not supplied

Studies on rectal temperature of rats in relation to seasonal air temperature and morphine administration.

The present findings demonstrate that seasonal air temperature does not only influence the basal core temperature of rats, but also modifies the physiological/pharmacological actions of drugs. Thus, at low ambient temperature, intracerebroventricular on intraperitoneal administration of morphine produces mainly hypothermia followed by a secondary rise in rectal temperature. On the other hand, at high ambient temperature, the drug produces hyperthermia only. The hypothermic response at low ambient temperature is abolished by pretreatment of rats with 6-hydroxydopamine but not with phenoxybenzamine administration. This suggests that catecholamine pathway in the central nervous system is involved in morphine induced hypothermic response. Further, the role of cholinergic neurons in such response is also indicated.

Animals↗

PubMed1994

Kidney temperature measurement. Thermistors for temperature measurement.

During a study of the protective effects of cold on kidney cells under conditions of interrupted blood circulation, it was found that attention must be paid to the temperature of kidney tissue in order to prevent cell damage caused by an excessively reduced temperature. The authors correspondingly developed an instrument for the measurement of kidney tissue temperature where thermal sensors located in a needle are able to measure deep temperature in live tissue under conditions of external hypothermia. Thermal sensors were also placed in a hypothermal coil for contact measurement of surface temperature of a cooled kidney and in a duct for supply of cooling medium into a coil. Construction of these devices is described and basic the characteristics of the thermistor and thermocouple sensors for temperature measurement are presented. After evaluation of advantages of the tested sensors, indications regarding their application are given.

Body Temperature↗

PubMed1987

Body temperature set-point and the conscious perception of skin temperature in obese women.

Obese and control women were immersed in a bath of water kept at 37 degrees C. Oral temperature was measured. The subjects left hand was placed outside the bath for the local application of thermal stimuli between 20 degrees and 45 degrees C, subjects reporting the most pleasant temperature. The lower oral temperatures and lower levels of skin temperature rated as pleasant by obese women as compared with women of normal body weight or less suggests that in obesity the set-point of body temperature is lowered.

Adolescent↗

PubMed1983

Oral temperature as an index of core temperature during heat transients.

Rectal (Tre), oral (Tor) and oesophageal (Tes) temperatures were measured in five exercising subjects exposed for two hours to five conditions (1) a steady condition (WR) involving a constant work load (50 W) at a constant air temperature (Ta = 36.5 degrees C); (2) air temperature variations (delta Ta) between 28 degrees C and 45 degrees C and (3) between 23 degrees C and 50 degrees C at constant work load (50 W); (4) and (5) to work load variations (delta W) between 25 W and 75 W at a constant Ta (= 36.5 degrees C). Oral temperature recordings were taken sublingually and were either continuous or discontinuous. When discontinuous, the time needed for Tor to stabilize after the mouth opening was taken into account. The respective reliability of Tor and Tre as estimates of Tes were compared in each condition. Results showed that the resting (Tor - Tes) difference (+ 0.12 degrees C) was barely modified after two hours of exposure, whereas Tre overestimated Tes by 0.2 degrees C to 0.4 degrees C depending on the condition. The Tor variations were highly correlated with Tes variations under steady condition and under air temperature variations. In these conditions, Tor represented the best estimate of Tes. Under work-load variations, Tor was less closely related to Tes than was Tre. It is suggested that the relative inertia of Tor to step changes in exercise intensity could be ascribed to work induced variations in mouth blood flow.

Adult↗

PubMed1986

The influence of ambient temperature on metabolism and body temperature of newborn and growing reindeer calves (Rangifer tarandus tarandus L.).

Thermoregulatory capacities of 51 reindeer calves (Rangifer tarandus tarandus L.) aged 1-35 days were studied at -26.5 to +35.0 degrees C ambient temperatures at Kaamanen reindeer research station, Finland (69 degrees 10' N) during calving periods in May 1981 and May-July 1982. The newborn calves aged 1-4 days maintained a high body temperature (Tre) (mean +40.2 degrees C) even at the lowest experimental temperature of -22.5 degrees C by increasing their metabolic rate five-fold above the level at +11.0 degrees C. Heat production of the new-born calves was largely based on the metabolism of brown adipose tissue, stimulated by cold-induced discharge of the sympathetic nervous transmitter, noradrenaline (NA). Sensitivity of the calves to exogenous NA disappeared during the first 3-4 weeks of life. Thermal conductance of the calves was low at low ambient temperatures, but rose strongly as Ta increased above +10 degrees C. The extensive peripheral cooling, especially in the feet, was demonstrated in the calves aged 1-10 days. The lowest foot temperature (+10.5 degrees C) was measured in a 4-day-old calf at -14.5 degrees C. Slight shivering thermogenesis was recorded in the calves aged 1-4 days and occasionally in the older calves at low values of Ta. Shivering appears to be a reserve mechanism against severe cold. At about +20 degrees C and above the calves increased their Tre (approximately 1 degree C), oxygen consumption and heart rate. In the newborn calves oxygen consumption rose four- to five-fold and in 1-month-old calves about two-fold. Fast growing calves (maximum 400 g/day) appear to be more stressed by heat than by cold exposure.

Aging↗

PubMed1988

Core temperature is regulated, although at a lower temperature, in rats exposed to hypergravic fields.

1. In rats acclimated to 23 degrees C (RT rats) or 5 degrees C (CA rats), core temperature (Tc), tail temperature (Tt) and oxygen consumption (VO2) were measured during exposure to a hypergravic field. 2. Rats were exposed for 5.5 h to a 3 g field while ambient temperature (Ta) was varied. For the first 2 h, Ta was 25 degrees C; then Ta was raised to 34 degrees C for 1.5 h. During this period of warm exposure, Tc increased 4 degrees C in both RT and CA rats. Finally, Ta was returned to 25 degrees C for 2 h, and Tc decreased toward the levels measured prior to warm exposure. 3. In a second experiment at 3 g, RT and CA rats were exposed to cold (12 degrees C) after two hours at 25 degrees C. During the one hour cold exposure, Tc fell 1.5 degrees C in RT and 0.5 degree C in CA rats. After cold exposure, when ambient temperature was again 25 degrees C, Tc of RT and CA rats returned toward the levels measured prior to the thermal disturbance. 4. Rats appear to regulate their temperature, albeit at a lower level, in a 3 g field.

Acclimatization↗

PubMed1995

Incubation temperature and gonadal sex affect growth and physiology in the leopard gecko (Eublepharis macularius), a lizard with temperature-dependent sex determination.

Temperature-dependent sex determination (TSD), in which the temperature at which an egg incubates determines the sex of the individual, occurs in egg-laying reptiles of three separate orders. Previous studies have shown that the embryonic environment can have effects lasting beyond the period of sex determination. We investigated the relative roles of incubation temperature, exogenous estradiol, and gonadal sex (testis vs. ovary) in the differentiation of adult morphological and physiological traits of the leopard gecko, Eublepharis macularius. The results indicate that incubation temperature, steroid hormones, and gonads interact in the development of morphological and physiological characters with incubation temperature resulting in the greatest differences in adult phenotype. Incubation temperature did not affect reproductive success directly, but may influence offspring survival in natural situations through effects on adult female body size. Postnatal hormones seem to be more influential in the formation of adult phenotypes than prenatal hormones. These results demonstrate that TSD species can be used to investigate the effects of the physical environment on development in individuals without a predetermined genetic sex and thus provide further insight into the roles of gonadal sex and the embryonic environment in sexual differentiation.

Animals↗

PubMed1995

Temperature regulation and metabolism in rats exposed perinatally to dioxin: permanent change in regulated body temperature?

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been shown to lower thyroxine levels and cause hypothermia in the adult rat; however, there is little known regarding the perinatal effects of TCDD on metabolism and temperature regulation of the offspring. To address this issue, thermoregulatory responses were assessed in adult male rat offspring exposed perinatally to 1.0 micrograms TCDD/kg body wt by gavage on Gestational Day 15. Individual castrated offspring were placed in a gradient-layer calorimeter for 5 hr during their nocturnal period while ambient temperature (Ta) was maintained at 10, 16, 24, or 28 degrees C. Metabolic rate (M), as measured from the total heat loss in the calorimeter, was determined along with evaporative heat loss (EHL), dry thermal conductance, and body core temperature (Tc). Animals exposed to TCDD had a significantly lower body temperature at TaS of 10, 16, and 24 degrees C and a higher thermal conductance. M was unaffected by TCDD, indicating that TCDD did not impair the effector to regulate Tc during cold exposure. EHL was also unaffected by TCDD. Skin blood flow of the interscapular area was measured in anesthetized rats with laser Doppler velocimetry and found to be the same in control and TCDD groups. The reduction in body temperature over a wide range of TaS concomitant with normal thermoregulatory effector function suggests that perinatal exposure to TCDD results in a reduction in the regulated body temperature (i.e., decrease in set-point).

Adipose Tissue, Brown↗

PubMed1992

Temperature coupling in cricket acoustic communication. II. Localization of temperature effects on song production and recognition networks in Gryllus firmus.

Acoustic communication in Gryllus firmus is temperature-coupled: temperature induces parallel changes in male calling song temporal pattern, and in female preference for song. Temperature effects on song production and recognition networks were localized by selectively warming head or thorax or both head and thorax of intact crickets, then eliciting aggression song production (males) or phonotaxis to synthetic calling song (females). Because male song is produced by a thoracic central pattern generator (CPG), and because head ganglia are necessary for female song recognition, measurements of female phonotaxis under such conditions may be used to test the following competing hypotheses about organization of the song recognition network: 1. A set of neurons homologous to the male song CPG exist in the female, and are used as a template that determines preferred values of song temporal parameters for song pattern recognition (the common neural elements hypothesis), and 2. temporal pattern preference is determined entirely within the head ganglia. Neither selective warming of the head nor of the thorax was effective in changing female song preference, but simultaneous warming of head and thorax shifted preference toward a faster song in most preparations, as did warming the whole animal by raising ambient temperature. These results suggest that phonotactic preference for song temporal pattern is plurisegmentally determined in field crickets. Selective warming experiments during aggression song production in males revealed that syllable period is influenced but not completely determined by thoracic temperature; head temperature is irrelevant. The song CPG appears to receive some rate-setting information from outside the thoracic central nervous system.

Acoustic Stimulation↗

PubMed1978

The temperature sensitive mutant 72c. II. Accumulation at high temperature of ppGpp and pppGpp in the presence of protein synthesis.

A heat sensitive mutant of E. coli has been analyzed. A shift to restrictive temperature leads to an accumulation of ppGpp and pppGpp in both the parental and the mutant strains (both are relA+). The pool of these compounds is shown to decrease with time after the temperature shift in the case of the parental strain, but remains at the same elevated level in the case of the mutant. The temperature shift of the mutant leads to an apparent reduction of stable RNA synthesis; this inhibition can be released by chloroamphenicol or tetracycline. Gross protein synthesis is more or less unaffected at restrictive temperature. In the parental strain little effect is seen on RNA and protein synthesis after the temperature shift. A relA derivative of the mutant does not show the same inhibition of RNA synthesis at high temperature. Sedimentation analysis suggests that mutant 70S ribosome are more stable, when exposed to a lowered Mg2+ concentration, than are 70S ribosomes from the parental strain. In addition, the relative amounts of the two forms of ribosomal protein S6, which can be obtained on DEAE chromatography (Held et al., 1973), are significantly changed in the mutant.

Bacterial Proteins↗

PubMed2004

Degradation of 4-chlorophenol at low temperature and during extreme temperature fluctuations by Arthrobacter chlorophenolicus A6.

Low average temperatures and temperature fluctuations in temperate soils challenge the efficacy of microbial strains used for clean up of pollutants. In this study, we investigated the cold tolerance of Arthrobacter chlorophenolicus A6, a microorganism previously shown to degrade high concentrations of 4-chlorophenol at 28 degrees C. Luciferase activity from a luc-tagged derivative of the strain (A6L) was used to monitor the metabolic status of the population during 4-chlorophenol degradation. The A6L strain could degrade 200-300 mug mL(-1) 4-chlorophenol in pure cultures incubated at 5 degrees C, although rates of degradation, growth and the metabolic status of the cells were lower at 5 degrees C compared to 28 degrees C. When subjected to temperature fluctuations between 5 and 28 degrees C, A6L continued to degrade 4-chlorophenol and remained active. In soil microcosm experiments, the degradation rates were significantly faster the first week at 28 degrees C, compared to 5 degrees C. However, this difference was no longer seen after 7 days, and equally low 4-chlorophenol concentrations were reached after 17 days at both temperatures. During 4-chlorophenol degradation in soil, CFU and luciferase activity values remained constant at both 5 and 28 degrees C. However, once most of the 4-chlorophenol was degraded, both values decreased by 1-1.5 logarithmic values at 28 degrees C, whereas they remained constant at 5 degrees C, indicating a high survival of the cells at low temperatures. Because of the ability of A. chlorophenolicus A6 to degrade high concentrations of 4-chlorophenol at 5 degrees C, together with its tolerance to temperature fluctuations and stress conditions found in soil, this strain is a promising candidate for bioaugmentation of chlorophenol-contaminated soil in temperate climates.

Arthrobacter↗

PubMed1980

Characterization of a temperature-sensitive membrane alteration in chick embryo fibroblasts infected with a temperature-sensitive mutant of Rous sarcoma virus.

The intramembrane particles of freeze-fractured chick embryo fibroblasts transformed with a temperature-sensitive mutant of Rous sarcoma virus (TS68) are distributed differently at the permissive and non-permissive temperatures if, and only if, the cells are treated with glycerol before fixation. Few aggregates of intramembrane particles are present in glycerol-treated cells grown at the permissive temperature for transformation (36 degrees C), while numerous large aggregates of particles are present at the non-permissive temperature (41 degrees C). Changes in the distribution of particles after cells are shifted from 36 to 41 degrees C are observed after 20 min, while a temperature shift from 41 to 26 degrees C causes changes in glycerol-induced redistributions after 1 h. The changes observed in temperature shifts from 36 to 41 degrees C and from 41 to 36 degrees D do not require protein synthesis or RNA synthesis.

Animals↗

PubMed1981

Temperature adaptation of biological membranes. The effects of acclimation temperature on the unsaturation of the main neutral and charged phospholipids in mitochondrial membranes of the carp (Cyprinus carpio L.).

The phospholipid composition, fatty acid pattern and cholesterol content are studied in mitochondria of red lateral muscle of carp acclimated to high and low environmental temperatures. The results of the experiments are: mitochondria from cold-acclimated carp contain higher proportions of ethanolamine phosphatides than mitochondria from warm-acclimated fish, the opposite is true for the choline phosphatides. Thus, at constant pH, the membrane phospholipids are slightly more negatively charged at low acclimation temperature. The total plasmalogen content is reduced in the cold; this reduction is caused by a decrease in the proportion of the choline plasmalogens. The ethanolamine phosphoglycerides contain approx. 20% of the alk-1-enyl acyl type, irrespective of the acclimation temperature. There is no temperature-dependent difference in the low proportion of cholesterol. The fatty acids of total mitochondrial phospholipids are characterized by large amounts of the n-3 and n-6 families. The ratio of unsaturated to saturated fatty acids and the unsaturation index are remarkably higher than those reported for comparable mammalian phospholipids. Cold acclimation of carp does not significantly increase the unsaturation of total phospholipids. A fatty acid analysis of the main isolated phospholipids, however, shows that cold acclimation considerably increases unsaturation of the neutral phosphatidylcholine, whereas it dramatically decreases unsaturation of the negatively charged cardiolipin. It is suggested that the observed fatty acid substitution in phosphatidylcholine indicates a temperature-induced fluidity adaptation within the mitochondrial lipid bilayer, whereas the inverse acclimation pattern of cardiolipin provides a suitable lipid to accommodate the temperature-dependent modifications in the dynamic surface shape of integral membrane proteins.

Acclimatization↗

PubMed1977

Analogs of endoperoxide precursors of prostaglandins: failure to affect body temperature when injected into primary and secondary central temperature controls.

It is known that central administration of prostaglandins of the E series has marked effects on body temperature. The purpose in the present experiments was to learn whether stable analogs of the cyclic endoperoxide precursors of PGE2, PGF2alpha and PGD2, injected into the primary temperature control in the preoptic/anterior (PO/AH) hypothalamic region and into a presumed secondary control in the medulla oblongata, can produce rises in body temperature similar to those caused by PGE2. Injection of the analogs U-44069 and U-46619 (1.0 and 2.0 microng) into the PO/AH region of the rat, where both PGE2 and PGE1 caused hyperthermia, had no effect on Tre. Likewise, injections into the medulla oblongata, in the region where PGE2 and PGE1 caused hypothermia, were ineffective in altering body temperature. That neurons important to the control of body temperature are selectively sensitive to PGE2 and not to analogs of prostaglandin precursors suggests that local cyclic endoperoxides can influence body temperature only through bioconversion to prostaglandin.

Animals↗

PubMed1984

The effect of non-permissive temperature on met-tRNA synthetase in Saccharomyces cerevisiae temperature-sensitive mutant ts 7-45.

The effects of incubation of yeast spheroplasts at elevated temperature (40 degrees C) on a number of activities involved in protein biosynthesis have been examined in preparations obtained from wild-type cells (wt A364A ) and a temperature-sensitive mutant (ts 7-45) derived from it. With wild-type cells, preincubation of spheroplasts at the elevated temperature had little or no effect on the following: the ribosomal subunit-polysome pattern; the translation of exogenous natural mRNA in postpolysomal extracts devoid of endogenous mRNA; the translation of poly(U) in postpolysomal extracts; the incorporation of methionine into 40 S preinitiation and 80 S initiation complexes; the synthesis of Met-tRNA in postribosomal (cytosol) extracts; and the formation of eIF-2 X GTP X Met-tRNAf ternary complex in the cytosol. With temperature-sensitive spheroplasts that had not been preincubated at the elevated temperature, the concentration of free, native 40 S subunits appeared to be lower and that of 60 S subunits higher than in wild-type cells; translation of exogenous natural mRNA in postpolysomal extracts was somewhat lower than in wild-type preparations, but all of the other reactions and components measured were comparable to those in wild-type preparations. Preincubation of temperature-sensitive spheroplasts at 40 degrees C resulted in: a further decrease in the level of 40 S subunits; disaggregation of polysomes; loss of ability to translate natural mRNA but not poly(U); decreased ability to form 40 S preinitiation intermediates; and production of an activity, found in the cytosol, that inhibited Met-tRNA synthetase reversibly. The inhibitor had the characteristics of a protein and did not appear to be a proteinase, nuclease, or nucleotidase.

Amino Acyl-tRNA Synthetases↗

PubMed1987

Temperature-mediated processes in teleost immunity: the effects of temperature on membrane immunoglobulin capping on channel catfish B lymphocytes.

1. In order to better understand ligand-induced redistribution of membrane receptors and lymphocyte activation in ectothermic vertebrates, flow cytometry was used to monitor the effects of both in vivo acclimation temperature and in vitro assay temperatures on the kinetics of monoclonal antibody-induced membrane immunoglobulin (mIg) capping on channel catfish lymphocytes. 2. It was observed that the kinetics of mIg capping were dependent on in vitro assay temperatures, in vivo acclimation temperatures, and the length of time of in vivo acclimation. In the latter situation in vivo acclimation of fish to 27, 22 and 17 degrees C was considered complete after 3 weeks, while acclimation to 12 degrees C required a minimum of 5 weeks. 3. The energies of activation required for mIg capping ranged from 33 to 24 kcal/mol; lower energies of activation were observed with lower temperature acclimation. 4. It was also noted that the lower energies of activation were associated with concomitant decreases in cellular phospholipid saturated/unsaturated fatty acid ratios. 5. It appears that channel catfish B cell mIg capping, presumably a requisite for immune function, can be significantly affected by environmental temperatures; most likely such effects are attributable to changes in plasma membrane viscosities.

Acclimatization↗