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PubMed1983

The effect of environmental temperature on immune response and metabolism of the young chicken. 4. Effect of environmental temperature on some aspects of energy and protein metabolism.

The effect of environmental temperature on some aspects of energy and protein metabolism of 3 to 6-weeks-old pullets was investigated in a combined immunological and physiological study. Four experiments were performed in two climate respiration chambers. In each experiment a constant standard temperature of 25 C was maintained in one chamber. The temperature regimens in the other chamber were: a constant temperature of 15 C (Experiment 1) and 35 C (Experiment 3) and temperatures that fluctuated between 10 to 20 C (Experiment 2) and between 30 to 40 C (Experiment 4). Four groups of 60 pullets were held at each temperature regimen. Treatments differed between groups in type of injection (phosphate buffered saline or sheep red blood cells); feeding level (ad libitum vs. +/- 80% of ad libitum); and length of acclimation period. At low temperatures, feed conversion (g feed/g growth) was higher (P less than .05) than at 25 C. Feed intake was increased by 12.9 (at 15 C) and 10.5% (at 10 to 20 C) compared to intake at 25 C. Growth rate and protein gain were not significantly affected by low temperatures. High temperatures reduced (P less than .05) feed intake (15.9% at 35 C and 14.9% at 30 to 40 C) and growth rate (12.3% at 35 C and 12.5% at 30 to 40 C) compared to 25 C. Protein gain and feed conversion were not significantly affected by high temperatures. Restricted feeding reduced (P less than .05) growth rate (Experiments 1 to 4) and increased (P less than .05) feed conversion (Experiments 3 and 4). Differences due to type of injection and degree of acclimation were not significant.

Animals↗

PubMedDate not supplied

Temperature and temperature measurement after induced hypothermia.

This study was designed to assess factors associated with afterdrop, the fall in core temperature following completion of cardiac surgery, and determine the validity of noninvasive measures of temperature to predict core temperature in the severely hypothermic patient. Twenty-five postcardiac surgery patients served as subjects. Core temperature was measured using the pulmonary artery, bladder, and esophageal sites. The less invasive measures included a tympanic membrane thermometer, oral and axillary electronic thermometers, and a forehead surface temperature indicator. Temperatures were recorded every 10 minutes for 2 hours. End-of-surgery temperatures ranged from 30.3-38.3 degrees C (86.5-100.9 degrees F) with a mean of 36.02 degrees C (96.84 degrees F). Temperature change over the next hour ranged from a rise of 2.5 degrees C (4.5 degrees F) to a fall of 4.1 degrees C (7.2 degrees F). Factors associated with afterdrop included age, end-of-surgery temperature (both positively) and body mass (negatively). No noninvasive measure appeared to be a valid indicator of core temperature in these hypothermic patients.

Aged↗

PubMed2006

[Responses of soil temperature in wetland ecosystem to air temperature and their effects on CO2 emission].

Through two years located field observation, this paper studied the responses of marsh soil temperature to air temperature and the effects of soil temperature on CO2 emission from marsh soil-vegetation system, and calculated the seasonal variation of CO2 emission. The results showed that from the beginning of thawing, an increasing trend of soil temperature was exerted by the change of air temperature, and there was a significant exponential correlation between soil temperature in root layer and air temperature (R2 = 0.94, P<0.01). Despite of the decreased responses of soil temperature to air temperature with increasing soil depth, the CO2 emission from marsh soil-vegetation system was strongly exponentially correlated with soil temperature in root layer (R2 = 0.84, P< 0.01). An improved model equation was used for calculating the mean CO2 efflux from marsh soil-vegetation system during the growth season in 2003, and the calculated CO2 efflux was 664.5 +/- 213.9 mg2 m(-2) h(-1), approaching the value of located field observation (634.0 +/- 227.7 mg x m(-2) h(-1)), indicating that this model equation was effective to evaluate the CO2 emission from marsh during growth season.

Air↗

PubMed2003

Defining torpor in free-ranging bats: experimental evaluation of external temperature-sensitive radiotransmitters and the concept of active temperature.

A variety of definitions involving body temperature (Tb), metabolic rate and behavior have been used to define torpor in mammals and birds. This problem is confounded in some studies of free-ranging animals that employ only skin temperature (Tsk), a measure that approximates but may not precisely reflect Tb. We assess the accuracy of Tsk in the context of a recent definition for torpor called active temperature. We compared the active temperatures of individual big brown bats (Eptesicus fuscus), which aggregate in cavities, with solitary, foliage-roosting hoary bats (Lasiurus cinereus). In captive big brown bats, we compared Tsk and core Tb at a range of ambient temperatures for clustered and solitary roosting animals, compared Tsk and Tb during arousal from torpor, and quantified the effect of flight on warming from torpor. Hoary bats had significantly lower active temperatures than big brown bats despite having the same normothermic Tsk. Tsk was significantly lower than Tb during normothermia but often greater than Tb during torpor. Flight increased the rate of warming from torpor. This effect was more pronounced for Tsk than Tb. This suggests that bats could rely on heat generated by flight muscles to complete the final stages of arousal. Using active temperature to define torpor may underestimate torpor due to ambient cooling of external transmitters or animals leaving roosts while still torpid. Conversely, active temperature may also overestimate shallow torpor use if it is recorded during active arousal when shivering and non-shivering thermogenesis warm external transmitters. Our findings illuminate the need for laboratory studies that quantify the relationship between metabolic rate and Tsk over a range of ambient temperatures.

Acclimatization↗

PubMed1997

Fluctuations of rectal and tympanic temperatures with changes of ambient temperature during night sleep.

Many studies have demonstrated a decline in core temperature during slow wave sleep (SWS) in animals and humans. However, there are few studies that have investigated core temperature fluctuation during rapid eye movement sleep (REM) at different ambient temperatures. This study examined the effects on core temperature of continuous hot or cold exposure during sleep. Ten male subjects were exposed to hot and cold stress from 00 h to 1:00 h, when SWS is most predominant, and from 5:00 h to 7:00 h, when REM is predominant. Rectal temperature (Tr) and tympanic temperature (Tt) were monitored for 3 days, and polysomnographies (PSG) were recorded from 23:00 h to 7:00 h. The experiments lasted 3 weeks for each subject, over 2 consecutive nights each week (including an adaptation night and an experimental night). On the experimental night, subjects were exposed to hot (29 degrees C) or cold (21 degrees C) ambience. The core temperature fluctuation under the hot or cold ambience were compared with under the thermoneutral ambience. Under hot ambience, Tr declined significantly in the first 2 hours of sleep, but Tt did not change. In the last 2 hours, both Tr and Tt were significantly elevated. Under cold ambience, both Tr and Tt declined significantly in the first 2 hours. However, in the last 2 hours, neither Tr not Tt showed any change. The result that Tr and Tt rose in hot ambience during the last 2 hours when REM is predominant suggests that body temperature during REM is influenced by ambient temperature.

Adult↗

PubMed1983

Effect of ambient temperature upon the surface temperature of the equine limb.

Ten clinically healthy adult horses were examined with the portable infrared thermometer at ambient temperatures of 5, 15, and 25 C to evaluate the thermal response of limbs of the horse to variations of ambient temperature. Limb surface temperature varied in direct proportion to changes in the ambient temperature, with considerable variation occurring among individual horses, especially at the lower temperatures. Areas of proximal parts of the limbs were more resistant to temperature variation than were distal parts. Ambient temperature had a statistically significant, but clinically unimportant, effect upon the bilateral symmetry (right side/left side) of limb surface temperature. At all ambient temperatures, the mean variation between left side and right side target areas was less than 1 degree C.

Animals↗

PubMed1973

The influence of body core temperature and peripheral temperatures on oxygen consumption in the pig.

1. The rate of oxygen consumption was measured in young pigs exposed to different ambient temperatures and the effect on metabolic rate of changing the temperature of thermodes implanted in the hypothalamus and over the spinal cord was determined. In some experiments the temperature of the skin over the trunk was changed by means of a water-perfused coat.2. Cooling the hypothalamus or the spinal cord in a warm ambient did not change the rate of oxygen consumption. At a thermoneutral ambient temperature, cooling either thermode increased oxygen consumption. In a cold environment, cooling either thermode increased the rate of oxygen consumption more than at a thermoneutral temperature. The increase in the rate of oxygen consumption was greatest during cooling of the spinal cord and it appeared that the pigs also shivered more violently. Heating either thermode tended to decrease oxygen consumption in a cold environment.3. In pigs with thermodes both in the hypothalamus and over the spinal cord, cooling both thermodes was accompanied by a greater increase in oxygen consumption than cooling either thermode alone. The increase in oxygen consumption on cooling one thermode could be reduced by heating the other.4. The skin temperature (fixed by the water perfused coat, or the ambient temperature) at which the rate of oxygen consumption increased, was lowered during heating of the thermodes, but the rate of increase in oxygen consumption appeared not to change as a function of falling skin or ambient temperature.

Animals↗

PubMed2000

On the temperature and pressure dependence of a range of properties of a type of water model commonly used in high-temperature protein unfolding simulations.

Molecular dynamics simulations of protein folding and unfolding are often carried out at temperatures (400-600 K) that are much higher than physiological or room temperature to speed up the (un)folding process. Use of such high temperatures changes both the protein and solvent properties considerably, compared to physiological or room temperature. Water models designed for use in conjunction with biomolecules, such as the simple point charge (SPC) model, have generally been calibrated at room temperature and pressure. To determine the distortive effect of high simulation temperatures on the behavior of such "room temperature" water models, the structural, dynamic, and thermodynamic properties of the much-used SPC water model are investigated in the temperature range from 300 to 500 K. Both constant pressure and constant volume conditions, as used in protein simulations, were analyzed. We found that all properties analyzed change markedly with increasing temperature, but no phase transition in this temperature range was observed.

Calibration↗

PubMed2001

Stability parameter estimation at ambient temperature from studies at elevated temperatures.

The determination of specific kinetic constants k(i) in pH-profile studies is often undertaken at ambient temperature. However, when dealing with a drug substance that is stable at ambient temperature, the pH-profile study is conducted at a chosen elevated temperature and the kinetic parameters are given at this particular elevated temperature. But in stability studies we generally need kinetic constants at ambient or storage temperature for practical reasons (information and storage conditions of formulation). To assess this ambient kinetic information from studies at elevated temperatures, cumulative sequential steps are usually employed with very few statistical concerns on the final estimates. The statistical problems on these final estimates in cumulative procedures are highlighted in many papers. Because these stability parameters are useful for drug formulation and storage conditions, good practical decisions have to be made on the basis of statistically unbiased identified parameters. We propose in this paper a nonlinear model that allows the direct determination of specific activation energies E(ai) that are linked to the specific kinetic constants k(i). Hence, a mathematical relationship between drug concentration C, pH, temperature T, and time t is obtained. Kinetic data from acetylsalicylic acid (ASA) hydrolysis (first-order kinetics) are used to validate the model. The results show that it is possible to obtain directly, by an extrapolation procedure, the kinetic parameters (specific kinetic constants k(i), specific activation energies E(ai), and dissociation constant pK(a)) at low temperature from data gathered at elevated temperatures using more meaningful statistics.

Data Interpretation, Statistical↗

PubMed1987

An evaluation of milk temperature measurement for detecting oestrus in dairy cattle. II. Variations in body and milk temperature associated with oestrus.

Vaginal and milk temperatures were measured at each milking in 15 post-partum Friesian cows showing recurrent oestrous cycles for a total of 33 oestruses. A significant increase (P less than 0.001) in both vaginal and milk temperature of 0.29 +/- 0.05 degrees C was shown between the milking prior to oestrus and the milking when oestrus occurred. Cows were divided into 3 groups: showing either a definite temperature rise (27% of cases), a limited temperature rise (60%) or no temperature change (13%) associated with oestrus. Various methods of analysis were investigated to determine the usefulness of the milk temperature data for oestrus prediction. The optimum compromise of high oestrus detection rate (73.3 +/- 16%) and lowest percentage of false positives (10.8 +/- 3.0%) was based on a temperature rise on the day of oestrus of greater than or equal to 0.2 degrees C over the corresponding mean temperature of the preceding three days. These rates suggest the measurement of milk temperature is less useful for oestrus prediction than some earlier reports have indicated.

Animals↗

PubMed1995

Influence of ambient temperature on the effects of NPY on body temperature and food intake.

Because thermoregulation and food consumption are interrelated, and because thermoregulation processes are influenced by ambient temperature, we examined the effects of neuropeptide Y (NPY) on both body temperature and food intake in various thermal environments after intracerebroventricular administration of 20 micrograms. Results reveal that the prominent effects of NPY on body temperature and food intake in relatively thermoneutral environments are drastically altered at more extreme ambient temperatures. NPY produced hypothermia in animals placed at 4, 12, and 21 degrees C, and actually increased body temperature in animals subjected to 30 and 38 degrees C temperature. On the other hand, in comparison with ambient temperatures of 12 and 21 degrees C, ambient temperatures of 4 and 30 degrees C significantly reduced the stimulatory effect of NPY on food consumption. Moreover, at 38 degrees C the effect of NPY on food intake was totally abolished. These data demonstrate that ambient temperature has a critical influence on central actions of NPY.

Animals↗

PubMed1982

The energy costs of temperature regulation in birds: the influence of quick sinusoidal temperature fluctuations on the gaseous metabolism of the Japanese quail (Coturnix coturnix japonica).

1. Quick sinusoidal temperature fluctuations (constant average 10 degrees C) cause an increase in metabolism in comparison to an invariable constant ambient temperature of the same dimension. 2. At the observed mean value of 10 degrees C metabolism is increased by 0.8% per 1 K/hr based on the values of resting metabolic rate (correlation: M = 53.5 + 0.445 Ta, M in J/K g hr, Ta = ambient temperature change in K/hr) and 0.6% based on the values of activity metabolism (M = 70.4 + 0.425 Ta). 3. The absolute augmentation of metabolism per 1K/hr is, by comparison, the same for day and night. Its amount is 0.42 and 0.43 J/K g hr respectively. 4. In the response of metabolism to temperature fluctuations no differences could be found with respect to the amplitude and frequency modifications of temperature. 5. The increase of energy consumption is probably caused to a greater extent by "overshoot" of the feedback control system in the course of adjusting metabolism to new levels according to the ambient temperature conditions. 6. Short term ambient temperature changes (i.e. measuring different temperature levels in one night to test basic metabolism vs ambient temperature) cannot produce reasonable values for basic metabolic rate, since these artificially high values reflect the testing procedure.

Animals↗

PubMed1996

Temperatures measured by a deep body thermometer (Coretemp) compared with tissue temperatures measured at various depths using needles placed into the sole of the foot.

Continuous monitoring of body temperature during anaesthesia is a widely accepted clinical practice for which a variety of techniques are used. In this study, the accuracy of the deep body thermometer (Coretemp) was compared with temperatures measured by needle thermocouples. With IRB approval and informed consent, seven ASA physical status I and II patients undergoing otolaryngeal surgery were studied. General anaesthesia and neuromuscular blockade were induced with thiamylal and vecuronium. Anaesthesia was maintained with isoflurane at an end-tidal concentration of 1.0-2.0% and 66% nitrous oxide in oxygen. After induction of general anaesthesia, subcutaneous temperature was measured at the sole of the left foot using a Coretemp. Additionally 8-, 18-, and 38-mm-long needle thermocouples were inserted into the the sole of the left foot close to Coretemp and skin-surface temperature was also recorded adjacent to the needles. The Coretemp measurement (Tc) correlated best with 18-mm-deep needle temperature (r2 = 0.87). There was also a good correlation between Tc and 38-mm-deep needle temperature (r2 = 0.83). Skin and 8-mm-deep needle temperatures correlated poorly or only moderately with Tc (r2 = 0.67, 0.75, respectively). These results indicate that temperatures measured by Coretemp well reflect the temperatures at a depth of 18 mm or more from the skin into the foot.

Anesthesia, General↗

PubMed1962

A temperature-gradient bar and its applications to the study of temperature effects on the growth of Reiter's treponeme.

Cannefax, George R. (Communicable Disease Center, Atlanta, Ga.). A temperature-gradient bar and its applications to the study of temperature effects on the growth of Reiter's treponeme. J. Bacteriol. 83:708-710. 1962.-A temperature-gradient device is described which employs a constant heat source and an aluminum bar with 294 holes to accommodate small test tubes. Examples of the range and degree of temperature gradients are presented, and the factors affecting heat conduction and heat losses are discussed. Three temperature gradients obtained under different conditions are shown graphically. The usefulness of the temperature-gradient bar in determining the optimal temperature for the cultivation of Reiter's treponeme is presented. The optimal temperature range was found to be 33 to 35 C. The potential usefulness of the temperature-gradient bar in other biological studies is suggested.

Temperature↗

PubMed1993

Comparison of core threshold temperatures for forehead sweating based on esophageal and rectal temperatures.

A protocol incorporating successive hot and cold water immersions, causing respective warming and cooling of the body, has been used to determine the core threshold for sweating. Disparate results have been reported for the core threshold of sweating, and these have been attributed to the possible existence of core temperature gradients during such a protocol. Spatial and temporal core temperature (Tc, degree C) gradients during dynamic changes in body temperature may give rise to different values of core temperature thresholds for sweating, depending on the Tc measurement site. In addition, during such an immersion protocol skin temperature transients may influence expression of thresholds using esophageal temperature (Tes). With these considerations, the effects of Tc gradients and skin temperature on Tc thresholds for sweating were examined. Subjects (n = 22) were immersed to the neck in 40 degrees C water until Tes reached 38.5 degrees C (phase 1), followed immediately by cooling in 30.6 degrees C water until extinction of sweating was observed (phase 2). Cooling was continued in the latter bath after the sweating extinction until total immersed time reached 50 min or until shivering was initiated (phase 3). During the trials continuous assessment was made of rectal temperature (Tre) and Tes, mean unweighted skin temperature (Tsk, degree C), forehead sweating rate (Esw, g.m-2.min-1), oxygen consumption (VO2, L.min-1), and surface heat flux (Q, W.m-2). With the current protocol it appeared inappropriate to determine the Tc thresholds for onset of sweating, as sweating was initiated prior to any significant displacement of Tc, but was most likely influenced by Tsk and its rate of change.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2005

Voluntary muscle activation is impaired by core temperature rather than local muscle temperature.

Fatigue during hyperthermia may be due in part to a failure of the central nervous system to fully activate the working muscles. We investigated the effects of passive hyperthermia on maximal plantar flexor isometric torque (maximal isometric voluntary contraction) and voluntary activation to determine the roles of local skin temperature, core temperature, and peripheral muscle temperature in fatigue. Nine healthy subjects were passively heated from 37.2 to 39.5 degrees C (core temperature) and then cooled back down to 37.9 degrees C using a liquid-conditioning garment, with the right leg kept at a thermoneutral temperature throughout the protocol, whereas the left leg was allowed to heat and cool. Passive heating resulted in significant decreases in torque from [mean (SD)] 172 N x m (SD 39) to 160 N x m (SD 44) and in voluntary activation from 96% (SD 2) to 91% (SD 5) in the heated leg, and maximal isometric voluntary contraction decreased similarly from 178 N xm (SD 37) to 165 N x m (SD 38) and voluntary activation from 97% (SD 2) to 94% (SD 5) in the thermoneutral leg. The initiation of cooling, which produced a rapid decrease in skin temperature and cardiovascular strain [heart rate reserve decreased from 58% (SD 12) to 31% (SD 12)], did not immediately restore either torque or voluntary activation. However, when core temperature was lowered back to normal, torque and voluntary activation were restored to baseline values. It was concluded that an increase in core temperature is a factor responsible for reducing voluntary activation during brief voluntary isometric contractions and that temperature-induced changes in the contractile properties of muscle and local thermal afferent input from the skin do not contribute significantly to the decrement in torque.

Adult↗

PubMed1996

Effects of lights of different color temperature on the nocturnal changes in core temperature and melatonin in humans.

A variety of types of artificial illumination has recently become available, differing in the quality of illumination and range of color temperature. In our previous studies we found that in subjects with normal color vision the nocturnal fall in core temperature and the increase of urinary melatonin excretion were suppressed by bright blue or green light, but not by bright red or dim lights. The aim of our present study was to examine from the view point of chronobiology whether the lights of different color temperature often used in everyday life may affect core temperature and urinary melatonin secretion differently. Experiments were carried out on five subjects with normal color vision. They were exposed for 5 hr (from 21:00 h to 2:00 h) to two kinds of bright (1000 lx) light of different color temperature (6500 K, 3000 K) with dim (50 lx) light as a control; after exposure they slept in darkness. Our main results were as follows: The light with a high color temperature of 6500 K more strongly suppressed the nocturnal fall of the core temperature and the nocturnal increase of melatonin secretion than the light with a low color temperature of 3000 K. This difference was particularly evident for core temperature during the sleep period following experimental illumination.

Adult↗

PubMed1999

Effects of ambient temperature and scrotal fleece cover on scrotal and testicular temperatures in rams.

The objective was to determine scrotal and testicular temperatures in rams and how they are affected by ambient temperature (10 degrees C vs 25 degrees C) and scrotal fleece (densely fleeced vs shaved). Scrotal surface temperatures (SST) of the caudal aspect of the shaved hemi-scrotum at 10 degrees C vs 25 degrees C were (mean, degrees C) 28.9 and 30.5 (P < 0.03), 28.2 and 29.6 (P < 0.04), and 26.1 and 27.6 (P < 0.06) at the top, middle and bottom of the testis, respectively. Scrotal subcutaneous temperatures (SQT) on the fleeced vs shaved side were 33.5 and 32.0 (P < 0.02), 32.2 and 31.1 (P < 0.06), and 31.7 and 30.8 (P < 0.09) at the top, middle, and bottom at 10 degrees C; they were 33.9 and 32.1 (P < 0.02), 33.1 and 31.9 (P < 0.05), and 32.5 and 32.0 (P < 0.15) at 25 degrees C. Intratesticular temperatures (ITT; measured only at 25 degrees C) on the fleeced vs shaved side were 35.3 and 35.0 (P < 0.5), 35.5 and 35.2 (P < 0.4), and 35.4 and 35.0 (P < 0.3) at the top, middle, and bottom. Temperature gradients (difference from top to bottom) were greatest for SST (2.8 degrees C), moderate for SQT (1.8 to 0.1 degrees C), and not significant for ITT (-0.1 and 0.1 degrees C). The SST was approximately 1.5 degrees C warmer at all 3 locations at 25 degrees C vs 10 degrees C. Increased ambient temperature affected SQT more at the bottom than at the top. Conversely, the difference in SQT between the fleeced and shaved sides was greatest at the top. The difference in ITT (0.3 degrees C warmer on the fleeced vs the shaved side at all locations) was not significant. Therefore, the magnitude of temperature increase associated with ambient temperature or scrotal fleece was affected by both depth and vertical location.

Animals↗