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At least 127 records · Page 7Linked to original sources
PubMed1998

Diurnally changing effects of locomotor activity on body temperature in laboratory mice.

In mice circadian body temperature curves are masked due to the effect of motor activity. However, body temperature will not immediately reflect activity, but rather the integrated activity over IT minutes (integration time) and after a certain delay (lag), and the sensitivity to such masking may change throughout the circadian cycle. The aims of the present investigation were to estimate IT and lag, to quantify the effect of motor activity on body temperature at different times of the day, and, using these results, to draw temperature curves that are closer to the endogenous one. Activity and body temperature of adult male laboratory mice were recorded telemetrically at 10-min intervals. Animals were housed in air-conditioned rooms (T = 22+/-2 degrees C; relative humidity: 55-65%) with a light-dark cycle of 12 h:12 h (light from 0700 to 1900 hours) and food and water available ad lib. The diurnal activity and body temperature rhythms were similar with a main maximum during the dark time and a secondary maximum immediately following lights-on. Nearly all changes of activity were reflected in body temperature. IT and lag were established on the basis of the best correlation between body temperature and activity (overlapping 4-h sections of 12 days) for all combinations of IT from 10 to 90 min and lag from 0 to 50 min (10-min steps each). The overall means of IT and lag were 40 and 0 min, respectively. During the dark time the values were somewhat larger, but not significantly so. The correlation between activity and body temperature was significantly better in the light time compared to the dark time. The sensitivity of the body temperature to changes in activity was investigated by linear regression analysis for every hour over 12 days (IT = 40 min, lag = 0 min). The gradients assessed by regression analysis showed a diurnal pattern with maximal values during the light time (p < 0.01). Thus, body temperature was raised by activity more during the light time (minimum of body temperature and activity) than during the dark time. The intercepts showed a nearly sinusoidal diurnal pattern with maximal values in the middle of the dark time. Accepting that the intercepts correspond to zero activity at a certain time of day, one might use them to get a curve that is closer to the endogenous body temperature rhythm. Mechanisms (circadian and thermoregulatory) that might cause the diurnally changing sensitivity of body temperature to activity are discussed.

Animals↗
PubMed1998

Radiotelemetric measurement of body temperature in feedlot steers during winter.

Little is known concerning body temperature regulation in cattle under conditions of low ambient temperature. To investigate the influence of cold on body temperature regulation, core body temperatures of feedlot steers (crossbred Bos taurus) were monitored for two winters in Nebraska, from late December to mid-March in yr 1 and from late December through June in yr 2. In yr 1, radiotransmitters to monitor temperature were implanted in the peritoneum of five steers (360 kg); in yr 2, four steers (320 kg) were used. Body temperatures and ambient temperatures were recorded at 3-min intervals and were mathematically filtered to produce 120 readings/d. For yr 1 and 2, daily maximum (40.09 and 39.66 degrees C), minimum (38.78 and 38.64 degrees C), and average (39.29 and 39.06 degrees C) body temperatures were not affected by ambient temperatures. Body temperatures exhibited circadian rhythms with the minima at approximately 0800 and the maxima at approximately 1900. For both years, sharp peaks in body temperature were often seen in the evening and, for yr 2, to a lesser extent in the morning. The occurrence of peaks was normally congruent, within a 1.5-h window, across steers. Congruent peaks in the evening with peak heights of 1.05 and .77 degrees C occurred on 65 and 56% of the days in yr 1 and 2, respectively. Occurrence of congruent peaks was correlated with dusk; peaks followed dusk by 30 to 60 min. Ambient temperature also influenced the occurrence of peaks; few peaks were observed when average daily ambient temperatures were below -7.5 degrees C. The dynamic changes in body temperature throughout the day, including the peaks in body temperature after dusk, strongly suggest that thermoregulatory systems in steers respond not only to current ambient conditions, but also to more integrative measures such as day length and daily heat load.

Animals↗
PubMed2004

Body temperature regulation during hemodialysis in long-term patients: is it time to change dialysate temperature prescription?

During hemodialysis procedures, changes in the dialysate temperature can raise or lower body temperature because the blood is returned to the patient in thermal equilibrium with the dialysate. Even a dialysate temperature equal to the patient's body temperature as measured from the tympanic membrane, oral cavity, or axilla can result in an increase in the patient's body temperature, leading to cutaneous vasodilation and the potential for cardiovascular instability and hypotension. This deleterious cycle of events can be prevented by suitably adjusting the dialysate temperature. Lowering the dialysate temperature from 37 degrees C to 34-35.5 degrees C has improved the cardiovascular stability of many hemodialysis patients. Continuous monitoring of blood temperature allows the practitioner to make preemptive changes in dialysate temperature because a small change in body temperature can have enormous cardiovascular implications. For example, only 0.3 degrees C to 0.8 degrees C separates the thresholds for skin vasodilation from that for shivering. A suggested improvement in the hemodialysis procedure is to use devices that allow continuous monitoring of arterial and venous blood temperatures and adjust the dialysate temperature automatically, keeping the patient, not the dialysate, isothermic. Less optimal solutions appear to be (1) to monitor arterial and venous temperatures while manually adjusting the dialysate temperature to maintain arterial (and hence body) temperature stability; (2) to monitor peripheral temperatures (oral, tympanic) at regular intervals and adjust dialysate temperature to maintain the body temperature constant; (3) routinely use a dialysate temperature <37.0 degrees C in all patients unless contraindicated.

Adult↗
PubMed1982

Photoperiod-induced changes in temperature-metabolism curve, shivering threshold and body temperature in the pigeon.

A short photophase combined with cold-acclimation changed the shivering threshold of the pigeon from 21 to 14 degrees C. The change of critical temperature was also found in the temperature-metabolism curve. A long photophase both alone and combined with warm-acclimation induced a reduction of body temperature to a lower level (about 2 degrees C) at all ambient temperature, ranging from 5 to 40 degrees C.

Acclimatization↗
PubMed1999

The effects of naked neck genotypes, ambient temperature, and feeding status and their interactions on body temperature and performance of broilers.

The effect of ambient temperature (AT) and feeding status on body temperature (BT) were investigated in broilers of the three naked neck genotypes (Na/Na, Na, na, and na/na). From 29 to 49 d of age, chicks were reared in a temperature-controlled chamber, where AT alternated daily between 24 and 32 C. At Day 47, all birds were deprived of feed for 12 h at 32 C, followed by 12 h of ad libitum intake at 24 C, then 12 h of ad libitum intake at 32 C, and finally feed deprivation for 12 h at 24 C. Body temperature was measured at the end of each of these 12-h periods. Body weight, feed consumption, feather coverage, and breast yield were determined. The Na/na and Na/Na birds had 20 and 40% less feather mass than the na/na birds. The three genotypes had similar BW at Day 49, but the naked neck birds had a higher breast yield. At high AT, BT was positively associated with feather mass of the three naked neck genotypes. The highest BT was exhibited by the fully feathered birds, and the lowest by the homozygous naked neck birds. The feeding status also affected BT of all birds, but to a larger extent in the normally feathered than in the naked neck birds. It appears that the lower negative effects of high AT on growth rate and meat yield in naked neck broilers can be attributed to their lower BT. Thus, it is suggested that measuring BT of broilers can be used as an indicator of the level of stress imposed on them by high AT.

Animal Feed↗
PubMed1977

Periodicity in body temperature in man.

Body temperatures and self-assessed mood scales were recorded for 7 weeks or more by male volunteers. Auto-correlations of temperatures from the 21 subjects show evidence of a significant peak at the 20-day-interval. The self-assessed measure of 'Alertness' (from 18 of them) also shows some evidence of rhythmicity, at the 22-day-period.

Behavior↗
PubMed2005

Decrease of body temperature after aglepristone treatment in bitches.

Body temperature responses and the timing of abortions were evaluated in pregnant bitches with the anti-progestin aglepristone. Fifteen purebred and crossbred, 25-45 days pregnant, were included in this study and seven untreated bitches at the same stage of pregnancy served as controls. Treated bitches were administered two applications of aglepristone (10 mg/kg SC) 24 h apart for pregnancy termination. Pregnancy termination was confirmed by ultrasonographic assessment. Body temperature was rectally measured three times a day for 6 days beginning 24 h before treatment or pregnancy diagnosis in the treated and control bitches, respectively. Additionally, serum progesterone concentrations were assessed at time points during the study in the treated bitches. Pregnancy was terminated in 14 treated bitches in a mean+/-S.E.M. of 4.3+/-0.7 days after treatment. Control bitches remained pregnant. In the treated bitches, but not in the controls, body temperature significantly decreased 24 h after the beginning of the treatments (P < 0.01) and then gradually returned to pre-treatment values. Correlation between the day of mean minimum body temperature and the day of pregnancy termination was low (0.07; > 0.05). Progesterone did not show significant change throughout the study. Body temperature does not seem to be a suitable variable to clinically monitor the aborting effect of aglepristone. Decrease of body temperature after aglepristone treatment could represent further evidence of its hypothalamic effects.

Abortifacient Agents, Steroidal↗
PubMedDate not supplied

Reliability of urine temperature as a measurement of basal body temperature.

Natural family planning is based on the recognition of physiologic signs and symptoms that identify fertile and infertile phases of the menstrual cycle. Identification of the onset of the infertile period can be determined when the upward shift in basal body temperature (BBT) has occurred. A study was conducted to determine if the temperature of the first-morning voided urine adequately represents BBT. In 22 subjects, vaginal temperature, taken immediately upon awakening, was compared with first-morning voided urine temperature as measured continuously by thermocouples mounted in either of two flow-through devices attached to a toilet bowl. A significant correlation was found between the two temperatures. The convenience and hygiene of the method together with the reliability of urine temperature as an estimator of BBT could reduce the generally high rate of noncompliance of women choosing this natural method of family planning.

Adult↗
PubMed1993

The influence of gender and race on mean body temperature in a population of healthy older adults.

Body temperature is known to vary with environmental conditions, physical activity, and illness. There is also some suggestion that body temperature is higher in women than men, and higher in blacks than whites. This study was undertaken to determine if previously described differences in body temperature found in relatively uncontrolled settings associated with gender and race can be reproduced under carefully controlled conditions. Temperature was measured orally with calibrated mercury-in-glass thermometers in 92 healthy community-dwelling volunteers aged 64 years and older. Environmental conditions were carefully controlled and patients with physical conditions or medication regimes known to alter body temperature were excluded. The mean body temperature for all subjects was 36.86 degrees C +/- 0.23 degrees C. The means for white men and women did not differ significantly. There was a statistically significant difference between black and white women, with blacks having 0.13 degrees C higher temperature. We conclude that body temperature varies with race in older women. No significant gender-related difference in normal body temperature was found in these healthy elderly white men and women. Differences in body temperature between men and women found in younger patient populations may reflect the temperature elevations in women associated with menstruation.

Age Factors↗
PubMedDate not supplied

Behavioural postures and the rate of body temperature change in wild freshwater crocodiles, Crocodylus johnstoni.

I recorded body temperature and behaviour of eight Crocodylus johnstoni in the wild over a 2-yr period in order to quantify the effect of posturing on body temperature and to provide a mechanistic explanation of how behaviour affects body temperature. Behaviour was categorised according to the proportion of a crocodile's surface area exposed from the water (0% exposed [=diving] to 100% exposed [=basking]). Crocodiles did not simply shuttle between the extremes of 100% exposed and diving but showed an array of intermediate postures. Rates of body temperature change were negative for exposures less than 40% and positive for 60%-100% exposed. This was due to the difference between operative temperature and body temperature, which was negative during diving but increased with the percentage of exposure, up to 25 degrees-30 degrees C during basking. For any particular posture, the rate of body temperature change decreased with increasing mass. Thermal time constants were shortest during diving and longest during basking. A heat-transfer equation predicted the rate of body temperature change well, except that it underestimated the rate of body temperature change during 80% and 100% exposed. Exposing only a small part of their body when in water (20%) slowed heat loss considerably, allowing crocodiles to spend more time in the water while maintaining body temperature within their preferred body temperature range.

Alligators and Crocodiles↗
PubMed1993

Cocaine alters body temperature and behavioral thermoregulatory responses.

This study examined the effects of cocaine HCl and ambient temperature on the core body temperature of the rat. To further examine the mechanisms of cocaine-induced changes in temperature regulation, the effects of cocaine on behavioral thermoregulatory responses were also observed. At normal room temperature (20 degrees C) cocaine produced a reduction in core body temperature. At a higher ambient temperature (27 degrees C), however, cocaine produced hyperthermia. When given a choice between normal and warm environments, cocaine-injected animals spent significantly less time in the warm environment than did control animals, but had significantly lower core body temperature. These results suggest that cocaine treatment may lower the thermoregulatory set point.

Animals↗
PubMed1994

Contribution of locomotor activity to the generation of the daily rhythm of body temperature in golden hamsters.

The locomotor activity and body temperature of 40 golden hamsters maintained under a 14L:10D light:dark cycle were studied by telemetry. Body temperature was found to be highly correlated with activity. On average, an increase from 0 to 200 units of activity was associated with a 0.7 degrees C increase in body temperature. However, body temperature during the dark phase of the light:dark cycle was 0.3 degrees C higher than during the light phase, irrespective of the activity level. These results indicate that, although activity can affect body temperature, the increase in activity during the dark phase is not the cause of the temperature rhythm. At least 30% of the total daily variation in body temperature is independent of variations in the activity level.

Animals↗
PubMed1986

Cold-rearing normalizes capacity for norepinephrine-stimulated thermogenesis but not body temperature in 16-day-old fatty Zucker rats.

The effects of a lowered rearing temperature on body weight, core temperature (Tc) and norepinephrine(NE)-stimulated thermogenesis were investigated in 16- to 17-day-old Zucker rat pups. 16-day-old fatty pups were significantly heavier (9%) than lean littermates in litters reared at 18 degrees C ("cold-reared") but not in litters reared at 25 degrees C ("normally-reared"). After 2 h isolation at 25 degrees C, Tc of lean pups was slightly higher (37.1 degrees C) in cold-reared litters than in normally-reared litters (36.4 degrees C), while fatty pups reared at either temperature were severely hypothermic (Tc = 33 - 34 degrees C). At an ambient temperature of 25 degrees C Tc in fatty and lean cold-reared pups increased to 39.5 degrees C after subcutaneous injection of 800 micrograms/kg NE. Normally-reared lean pups reached the same peak Tc after NE injection, while their fatty littermates reached a significantly lower peak Tc of 38.4 degrees C. The hypothermia associated with the onset of excess fat deposition in suckling fatty Zucker rats is not caused by a reduced capacity for NE-stimulated thermogenesis.

Adipose Tissue, Brown↗
PubMed1989

[Effects of general anesthesia on deep body temperature: with special reference to operation hours].

Deep body temperature in central part (thorax) and peripheries (dorsum of foot and hand) were determined, in order to observe the changes in body temperature occurring due to long or short duration of surgical operation in dental or oral surgery. The results obtained are as follows. Subjects selected were 49 cases including 32 males and 17 females, aged 17-43 years, of less surgical risk and without any disorders in respiratory and circulatory systems. They were classified into five groups on the basis of operation time: 10 cases for two hours or less group, 10 for two to three hours or less, 11 for three to four hours or less, 9 for four to five hours or less and 9 for five hours or more. The measured value in each measured site obtained when anesthesia started and at 30, 60, 120, 180, 240, 300 and 360 min. after when anesthesia started. The difference between central (thorax) deep body temperature and peripheral (dorsums pedis and manus) one was determined as delta T. 1. Changes of deep body temperature in each measured site Central (thorax) deep body temperature decreased temporarily at 30 and 60 min. and increased after 180 min. Peripheral (dorsums of foot and hand) deep body temperature increased till 60 min. and decreased after 120 min. 2. Changes in difference between central (thorax) and peripheral (dorsums of pedis and manus) deep body temperature (delta T). Both differences in deep body temperature, i.e., thorax VS dorsum pedis (delta T1) and thorax VS dorsum of manus (delta T2) became smaller with time from when anesthesia started to 120 minute.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Relationships between heat production, heat loss, and body temperature for rats with burn injuries between 26% and 63% of the body surface area.

Burn injury in man is characterized by increased body temperature proportional to burn wound size and may represent fever and/or hyperthermia. A nonseptic animal model used to study this phenomena has not been described. To test the hypothesis that large burn injuries in rats would produce increased body temperature, the rectal, skin, and body temperatures were sequentially measured and were calculated for rats in the control group and rats with burn injuries covering 26% to 63% of the body surface area [< or = 35%, 36% to 45%, and > or = 46% body surface area]. The group with burns covering > or = 46% of the body surface area had significantly higher rectal temperatures than did at least one other group on postburn days 7, 9, 11, 13, 18, and 20. On postburn days 7 and 11 this increase was significantly higher than that of all burn and control groups. Animals did not demonstrate any overt evidence of wound infection. These data do not establish a cause for increased body temperature after burn injury but suggest that a reproducible animal model may be possible for the study of the cause of increased body temperature after burn injury.

Animals↗
PubMed1995

Circadian rhythm of body temperature in an ectotherm (Iguana iguana).

Ectothermic animals regulate their body temperatures primarily by behavioral adjustment in relation to the thermal characteristics of the environment. Several studies have shown that some vertebrate ectotherms may show a daily pattern of body temperature selection when given a choice of environmental temperature. The pattern of body temperature selection free-runs when the animals are kept in constant darkness, demonstrating the existence of circadian regulation. To test whether there might also be a low amplitude circadian rhythm of body temperature itself, we examined the pattern of body temperature and locomotor activity of the lizard Iguana iguana held in a constant environmental temperature. Both variables were recorded for 3 days in a light:dark cycle and then for 10 days in constant dim light (0.1 lux). Under these conditions the body temperature of the lizard oscillates with a circadian period as does the locomotor behavior. These results demonstrate for the first time that ectothermic animals may display physiologically generated circadian rhythms of body temperature similar to those recorded in endotherms. In some animals the circadian rhythms of body temperature and locomotor activity showed different free-running periods, demonstrating that the body temperature rhythm was not caused by locomotor activity and suggesting internal desyncronization of the two rhythms.

Animals↗
PubMed2003

Complexity analysis of the temperature curve: new information from body temperature.

An attempt was made to develop a truly quantitative approach to temperature, based on models derived from nonlinear dynamics and chaos theory. Three different procedures for measuring the degree of complexity of the temperature curve were compared, and the possible correlations between these measurements and certain physiopathologically relevant parameters in healthy subjects were examined. Twenty-three healthy subjects (10 males, 13 females) between 18 and 85 years of age had their temperature measured every 10 min for at least 30 h. These time series were used to determine the approximate entropy (ApEn), a detrended fluctuation analysis (DFA), and the fractal dimension by the compass method (FD(c)). There was good correlation between the different methods of measuring the complexity of the curve [ r=-0.603 for ApEn vs. DFA ( p=0.002), r=0.438 for ApEn vs. FDc ( p=0.04) and r=-0.647 for DFA vs. FDc ( p=0.0008)]. Both the fractal dimension and the approximate entropy were inversely correlated with age [ r=-0.637 ( p=0.001) and r=-0.417 ( p=0.03), respectively], while the DFA increased with age ( r=0.413, p=0.04). The results thus suggest that complexity of the temperature curve decreases with age. The complexity of the temperature curve can be quantified in a consistent fashion. Age is associated with lower complexity of the temperature curve.

Adolescent↗