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 307 records · Page 17Linked to original sources

PubMed2003

Tympanic temperature reflects intracranial temperature changes in humans.

The purpose of the study was to identify extracranial locations in which temperature changes in humans reflect those of intracranial temperature in a reliable and repeatable way. This was achieved by subjecting 14 non-anaesthetized patients after neurosurgery to face fanning while intracranial and extracranial temperatures were continuously measured. In all patients the cranium was closed and the group included both febrile and non-febrile as well as hyperthermic and normothermic patients. The patients' faces were fanned for 20-30 min, with a small fan at an air speed of 3.25 m s(-1). This gave intracranial temperature changes measured in the subdural space ( T(sd)) that were highly and significantly correlated ( r=0.91, P<0.05, n=14) with changes in tympanic temperatures ( T(ty)). A low, statistically insignificant correlation ( r=0.40, P>0.05, n=12) was found between T(sd) and oesophageal temperatures. In conclusion, intracranial temperature changes, induced by face fanning, were reliably reflected by the changes in T(ty).

Adult↗

PubMed2026

Maternal and developmental temperature modulate adult response to temperature in Drosophila melanogaster.

Beyond inherited genes and environmentally induced changes in gene expression, phenotypes can also be shaped by parental effects-an effect from a parental phenotype that causes modifications in offspring traits, which cannot be solely explained by the parental or offspring genomes. Such effects may prepare offspring for future environmental conditions and contribute to phenotypic plasticity, including responses to temperature. While temperature-induced plasticity has been extensively studied, the relative contributions of parental versus direct environmental cues remain poorly understood. The fruit fly Drosophila melanogaster is a powerful model for studying physiological and behavioral adaptation to temperature. Flies inhabit environments spanning broad thermal ranges and show evidence of parental effects, such as increased heat tolerance in offspring from warm-reared parents. Here, we exposed mothers to two experimental temperatures and split their broods between the same two temperatures to estimate the relative importance of maternal and developmental effects on adult physiological and developmental responses to temperature. We find that the reaction norms of locomotor activity under gradually increasing temperatures, responses to heat-shock and cold-shock, and fecundity are mostly governed by direct plastic responses to developmental environment. We detected comparatively weak maternal effects in the response to heat-shock, fecundity, and grand-offspring survival where matched environments counteracted the effects of direct offspring experience. We conclude that thermal experience during development is the primary determinant of phenotypic plasticity in D. melanogaster, while maternal experience contributes a small but non-negligible component.

Animals↗

PubMed1986

Scrotal temperature reflects intratesticular temperature and is lowered by shaving.

Intratesticular and scrotal skin temperatures were measured in 34 men undergoing scrotal or inguinal surgical procedures under general anesthesia. Scrotal temperatures were measured before and after a dry scrotal shave. Intratesticular temperature was measured under direct vision with a needle thermistor. Linear regression analysis revealed a strong correlation between intratesticular and scrotal skin temperatures. In addition, simple scrotal shaving significantly decreased scrotal skin temperature. These observations suggest that scrotal skin temperature measurements may be useful to detect elevations of intratesticular temperature and scrotal shaving may be a useful adjunct for testicular cooling.

Adult↗

PubMed2005

Studies on the effect of MDMA ('ecstasy') on the body temperature of rats housed at different ambient room temperatures.

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') administration to rats produces hyperthermia if they are housed in normal or warm ambient room temperature (Ta) conditions (>or=20 degrees C), but hypothermia when in cool conditions (Ta<or=17 degrees C). We have now investigated some of the mechanisms involved. MDMA (5 mg kg(-1) i.p.) produced a rapid decrease in rectal temperature in rats at Ta 15 degrees C. This response was blocked by pretreatment with the dopamine D2 receptor antagonist remoxipride (10 mg kg(-1) i.p.), but unaltered by pretreatment with the D1 antagonist SCH23390 (1.1 mg kg(-1) i.p). MDMA (5 mg kg(-1)) did not alter the tail temperature of rats at Ta 15 degrees C, but decreased the tail temperature of rats at Ta 30 degrees C. A neurotoxic dose of MDMA (three doses of 5 mg kg(-1) given 3 h apart) decreased cortical and hippocampal 5-HT content by approximately 30% 7 days later. This lesion did not influence the rise in tail temperature when rats were moved from Ta 20 degrees C to 30 degrees C compared to nonlesioned controls, but did result in a lower tail temperature than that of controls when they were returned to Ta 24 degrees C. Acute administration of MDMA (5 mg kg(-1)) to MDMA-lesioned rats produced a sustained decrease in tail temperature in rats housed at Ta 30 degrees C compared to nonlesioned controls. These data suggest that the thermoregulatory problems previously observed in MDMA-lesioned rats housed at Ta 30 degrees C result, partially, from their inability to lose heat by vasodilation of the tail, a major heat-loss organ in this species.

Animals↗

PubMed2005

pKa of fentanyl varies with temperature: implications for acid-base management during extremes of body temperature.

OBJECTIVE: The pKa of fentanyl has not been measured previously at varying extremes of body temperature. The goal of this laboratory investigation was to test the hypothesis that the pKa of fentanyl changes with temperature. DESIGN: The investigation involved measuring the pKa values of aqueous fentanyl at varying temperatures. SETTING: The investigation was conducted in a controlled laboratory environment. PARTICIPANTS: No human or animal subjects were involved. INTERVENTIONS: Because no live subjects were involved in the investigation, no interventions were necessary. MEASUREMENTS AND MAIN RESULTS: This paper reports the effect of temperature on the pKa of fentanyl. The pKa of aqueous fentanyl was measured at 15 degrees C, 25 degrees C, 37 degrees C, 42 degrees C, and 47.5 degrees C by potentiometric titration in 0.01 mmol/L of potassium chloride after extensive degassing. Data were analyzed using the least squares method with an appropriately fitting equation. The pKa of fentanyl was found to change in a similar manner to the neutral point of water at varying temperatures. CONCLUSIONS: This finding has implications for the bioavailability of fentanyl at extremes of body temperature in association with the clinical acid-base management of the patient. Clinical implications for differing methods of intraoperative acid-base management at varying temperatures are discussed.

Acid-Base Equilibrium↗

PubMed1988

Bladder temperature as an estimate of body temperature during cardiopulmonary bypass.

Bladder temperature measured by a thermistor-tipped urinary catheter, was compared to oesophageal, nasopharyngeal, rectal and cutaneous temperatures in 33 patients during cardiopulmonary bypass. The bladder site was warmer than all other monitored sites in the pre-bypass period and showed least variation in temperature. The rate of change of bladder temperature during cooling and rewarming on bypass was significantly (p less than 0.01) lower than for oesophageal and nasopharyngeal temperatures, but was greater than or similar to the rate of change of rectal and cutaneous temperatures. This method of temperature measurement was found to be satisfactory during major surgery and also during the postoperative period in the intensive care unit.

Body Temperature↗

PubMed1999

Effect of ambient temperature and humidity on pulmonary artery temperature of exercising horses.

Six healthy Thoroughbred mares were trained to run on a high-speed treadmill and were conditioned for approximately 5 weeks. Each horse performed 6 identical standardised exercise tests (SET) 5 to 7 days apart. Each SET was performed under different ambient laboratory conditions: low temperature/low humidity (LL) 20.2 degrees +/- 0.6 degree C, 53.6 +/- 4.1%; low temperature/high humidity (LH) 19.7 +/- 0.6 degrees C, 86.7 +/- 4.2%; medium temperature/low humidity (ML) 24.6 +/- 0.2 degrees C, 58.7 +/- 3.7%; medium temperature/high humidity (MH) 24.7 +/- 0.3 degrees C, 87.5 +/- 1.4%; high temperature/low humidity (HL) 31.1 +/- 0.6 degrees C, 41.6 +/- 3.5%; and high temperature/high humidity (HH) 30.6 +/- 0.2 degrees C, 84.4 +/- 3.6%. Horses completed the 46 min SET, became fatigued or exercise was terminated when a pulmonary artery temperature (PAT) of 41.5 degrees C was reached. During a 30 min recovery period, horses stood quietly on the treadmill. Only one trial was terminated due to fatigue; in all other trials horses completed the 46 min SET or the trial was terminated when PAT = 41.5 degrees C. The relationships among run time (min) or PAT (degree C), ambient temperature and % relative humidity were defined by multiple linear regression analysis. Run time (min) = 90.9 - (1.39 x ambient temperature degree C) - (0.236 x relative humidity %). Approximately 54% of the variation in run times was explained by variation in environmental conditions, indicating that ambient temperature and humidity contribute substantially to the rate of rise in PAT. Run times to a PAT of 41.5 degrees C were significantly shorter (P < 0.000001) in HH than in other groups during the SET. Approximately 63% of the variation in PAT at the end of exercise was due to ambient temperature and humidity. In general, the longer the exercise time, the better the correlation among PAT, ambient temperature and relative humidity. Rectal temperature increased significantly (P < 0.0001) during the recovery period only in horses in the HH group, indicating that heat dissipation during recovery may have been impaired by environmental conditions. This study demonstrates that hot humid conditions result in more rapid rate of rise in PAT for horses undertaking identical exercise tests.

Animals↗

PubMed2006

How the body controls brain temperature: the temperature shielding effect of cerebral blood flow.

Normal brain functioning largely depends on maintaining brain temperature. However, the mechanisms protecting brain against a cooler environment are poorly understood. Reported herein is the first detailed measurement of the brain-temperature profile. It is found to be exponential, defined by a characteristic temperature shielding length, with cooler peripheral areas and a warmer brain core approaching body temperature. Direct cerebral blood flow (CBF) measurements with microspheres show that the characteristic temperature shielding length is inversely proportional to the square root of CBF in excellent agreement with a theoretical model. This "temperature shielding effect" quantifies the means by which CBF prevents "extracranial cold" from penetrating deep brain structures. The effect is crucial for research and clinical applications; the relationship between brain, body, and extracranial temperatures can now be quantitatively predicted.

Adaptation, Physiological↗

PubMed2003

Influence of temperature on water and aqueous glucose absorption spectra in the near- and mid-infrared regions at physiologically relevant temperatures.

Near- and mid-infrared absorption spectra of pure water and aqueous 1.0 g/dL glucose solutions in the wavenumber range 8000-950 cm-1 were measured in the temperature range 30-42 degrees C in steps of 2 degrees C. Measurements were carried out with an FT-IR spectrometer and a variable pathlength transmission cell controlled within 0.02 degree C. Pathlengths of 50 microns and 0.4 mm were used in the mid- and near-infrared spectral region, respectively. Difference spectra were used to determine the effect of temperature on the water spectra quantitatively. These spectra were obtained by subtracting the 37 degrees C water spectrum from the spectra measured at other temperatures. The difference spectra reveal that the effect of temperature is highest in the vicinity of the strong absorption bands, with a number of isosbestic points with no temperature dependence and relatively flat plateaus in between. On the basis of these spectra, prospects for and limitations on data analysis for infrared diagnostic methods are discussed. As an example, the absorptive properties of glucose were studied in the same temperature range in order to determine the effect of temperature on the spectral shape of glucose. The change in water absorption associated with the addition of glucose has also been studied. An estimate of these effects is given and is related to the expected level of infrared signals from glucose in humans.

Artifacts↗

PubMed2006

A new system for the analysis of thermal judgments: multipoint measurements of skin temperatures and temperature-related sensations and their joint visualization.

We report a new system for monitoring sensations of many body parts as well as comprehensively showing the distribution of overall skin temperature (T(sk)) and temperature-related sensations. The system consists of a console with 52 levers to report temperature-related sensations and software that facilitates the visualization of the distribution of T(sk) and temperature-related sensations by displaying them on a model of the human body. The system's utility was demonstrated with a physiological experiment involving three males and three females. They were exposed to step changes of ambient temperature from 23 degrees C to 33 degrees C. We measured T(sk) at 50 points, and the subjects concurrently provided estimates of local temperature sensation and thermal comfort/discomfort at 25 loci. This system greatly facilitates the perception and analysis of spatial relationships and differences in temperature and sensation in various areas of the body.

Adult↗

PubMed1982

Effect of water temperature on rumen temperature, digestion and rumen fermentation in sheep.

Three studies were conducted to examine effect of water temperature on rumen temperature, digestion and fermentation in sheep. Four, 2-yr-old wethers were used in a Latin square design among four water temperature treatments: 0, 10, 20 and 30 C. Rumen temperature was depressed most by 0 C water followed by 10 C, 20 C and 30 C water. For 0, 10, 20 and 30 C water, respectively, 108, 96, 96 and 72 min were needed to reach initial rumen temperature. Water temperature had no significant effect on N balance or percentage dry matter digestibility, crude protein digestibility and crude fiber digestibility although lowest digestion coefficients were observed for the 0 C treatment. Numerical differences were observed in rumen pH or volatile fatty acid (VFA) and ammonia-N concentrations at the various water temperatures; however, the effects were not significant. Rumen pH was maximally depressed at 2 h postfeeding for 0 C water, 3 h for 10 C water, 4 h for 20 C water, and 3 and 4 h for 30 C water. By 4 h postfeeding, the 0 C water treatment produced the highest concentration of all VFA and ammonia-N; however, by 4 h not all of the VFA or ammonia-N concentrations had reached maxima for 10, 20 or 30 C water treatments. The 0 C water treatment produced the lowest concentrations of ammonia-N and VFA (except acetate) by 5 h postfeeding.

Animals↗

PubMed1994

Can insulated skin temperature act as a substitute for rectal temperature when studying circadian rhythms?

We measured rectal, lateral chest wall, and axillary temperature every half hour for at least 24 h while subjects were living normal life-styles and keeping a sleep/activity diary. We then used a purification method to estimate the decrease of temperature due to sleep and the increases due to sitting, standing, walking, or exercising, as well as the parameters of the cosine curve that described the "purified data." Cosinor analysis of raw and purified data showed that the acrophases from both skin sites were much more variable and up to 8 h later than were those from the rectum (particularly if exercise had been taken), even though the acrophases from the two skin sites were similar to each other. For rectal temperature, there was an increase in the size of the masking effect as activity progressed through the sequence: sitting, standing or walking, exercising. In contrast, for both chest wall and axillary temperatures, although sitting produced masking effects similar to those for rectal temperature, masking effects due to standing or walking and exercising were much smaller, and sometimes they were even less than the masking effects due to sitting. These results indicate that our measurements of cutaneous temperature did not act as a substitute for rectal temperature, particularly when the subject was physically active rather than sedentary.

Adult↗

PubMed1978

Telemetry measured body temperature of domestic fowl at various ambient temperatures.

Adult, male Single Comb White Leghorn chickens (SCWL) were housed unrestrained in individual cages in a controlled environment room with a photoperiod of 12L:12D. By means of surgically implanted radio transmitter, body temperatures were recorded hourly for five consecutive days at each of six experimental temperatures: 23, 26, 29, 32, 35, and 38 C. The data were evaluated statistically by correlogram, periodogram, and harmonic analysis. Period length of each cycle was about 24 hr at all ambient temperatures. No significant differences in deep body temperature were observed until the ambient temperature reached 32 C; but highly significant increases were detected between 32, 35, and 38 C. Diurnal differences in body temperature ranged from .6 to 1.1 C. It has been suggested that the body temperature of male chicken may be under the control of a biological clock that synchronizes with the solar day.

Animals↗

PubMed1987

Body temperature of acclimated broilers during exposure to high temperature.

Short-term acclimation to high temperatures increased resistance of broilers to heat exposure. Two trials were conducted to determined the effect of acclimation on body temperature (Tb) during heat exposure. Broilers, 46-days old, were maintained at control or acclimating temperatures for 4 days. The control temperature was a constant 21 C with a 10 C dewpoint, and the acclimating temperature was a diurnal cycle of 24-35-24 C with a constant 21 C dewpoint. During the 4th day, broilers of both groups were exposed to temperatures of 41 C and 23 C dewpoint for 210 min. Body temperature was determined at the beginning of the heat exposure and at 30-min intervals until the end of the exposure. The Tb of both groups increased throughout heat exposure, but acclimated broilers had significantly lower Tb than control broilers from 90 through 210 min. Acclimated broilers had significantly lower heat stress mortality. The data show that acclimated broiler's Tb rises upon exposure to heat but that acclimation gives the capacity to stabilize Tb above normal Tb. The data also suggest Tb is preferable to mortality as a measure of acclimation in broilers.

Acclimatization↗

PubMed1995

[Transitory decreases in skin temperature during temperature increase training: possible explanation].

During biofeedback training, skin temperature changes were analyzed. Ten male undergraduates were asked to increase the temperature of the right index finger under three conditions: rest instructions with simulation feedback (Rest-SF), response-specific instructions without feedback (RI-NF), and response-specific instructions with feedback (RI-F). Skin temperature decreases during the early trials under the RI-F condition continued longer than under the RI-NF condition. Recovery from temperature decreases occurred faster after the repetition of feedback sessions. Skin temperature decreases were not observed under the Rest-SF condition. These results suggest that skin temperature decreases during early training associated with response-specific instructions, feedback, and the novelty of training. The results were also discussed in terms of the techniques which could increase skin temperature.

Adolescent↗

PubMedDate not supplied

The effects of heated and room-temperature abdominal lavage solutions on core body temperature in dogs undergoing celiotomy.

To document the magnitude of temperature elevation obtained with heated lavage solutions during abdominal lavage, 18 dogs were lavaged with sterile isotonic saline intraoperatively (i.e., during a celiotomy). In nine dogs, room-temperature saline was used. In the remaining nine dogs, saline heated to 43+/-2 degrees C (110+/-4 degrees F) was used. Esophageal, rectal, and tympanic temperatures were recorded every 60 seconds for 15 minutes after initiation of the lavage. Temperature levels decreased in dogs lavaged with room-temperature saline. Temperature levels increased significantly in dogs lavaged with heated saline after 2 to 6 minutes of lavage, and temperatures continued to increase throughout the 15-minute lavage period.

Animals↗

PubMed2006

Body temperature variability (Part 1): a review of the history of body temperature and its variability due to site selection, biological rhythms, fitness, and aging.

Body temperature is a complex, non-linear data point, subject to many sources of internal and external variation. While these sources of variation significantly complicate interpretation of temperature data, disregarding knowledge in favor of oversimplifying complex issues would represent a significant departure from practicing evidence-based medicine. Part 1 of this review outlines the historical work of Wunderlich on temperature and the origins of the concept that a healthy normal temperature is 98.6 degrees F (37.0 degrees C). Wunderlich's findings and methodology are reviewed and his results are contrasted with findings from modern clinical thermometry. Endogenous sources of temperature variability, including variations caused by site of measurement, circadian, menstrual, and annual biological rhythms, fitness, and aging are discussed. Part 2 will review the effects of exogenous masking agents - external factors in the environment, diet, or lifestyle that can influence body temperature, as well as temperature findings in disease states.

Adult↗

PubMed1968

The influence of hypothalamic temperature and ambient temperature on thermoregulatory mechanisms in the pig.

1. Two types of temperature fluctuation have been recorded from the preoptic region of the conscious pig. One, which is associated with arousal or movement, and another, which is related to rhythms in respiration and blood pressure.2. When the pigs were subjected to infra-red irradiation at various ambient temperatures it was found that there was no precise temperature of the preoptic region at which the respiratory frequency increased.3. Local heating of the preoptic region was effective in increasing the respiratory frequency only when the ambient temperature was above 30 degrees C.4. Even when both the peripheral temperature and central temperatures were increased there was a delay of several minutes before the onset of panting.5. Cooling the preoptic region of the hypothalamus prevented the onset of panting in a hot environment, and reduced respiratory frequency in an animal which was already panting.6. Oxygen consumption was reduced in a cold environment when the preoptic region was warmed, and increased when it was cooled. No increase in oxygen consumption occurred when the hypothalamus was cooled in a hot environment.

Animals↗