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PubMed1991

[The relationship between the deep body temperature and hemodynamics after open-heart surgery].

The relation of the forehead-sole deep body temperature difference with the cardiac index (CI), and the relation of that with the systemic vascular resistance index (SVRI) were studied in 61 adult patients after open-heart surgery for 24 hours. A correlation between the deep body temperature difference (X) and CI (Y) was expressed as, Y = -0.21X + 3.42 (r = 0.48), and that between the deep body temperature difference (X) and SVRI (Y), Y = 184X + 808 (r = 0.52). But immediately after the end of operation (n = 61), the correlation coefficients (r) were lower, 0.46 and 0.45, respectively. The deep body temperature difference was 1.8 degrees C on the average in patients whose CI was 2.21.min-1.m-2, and was 4.3 degrees C in patients whose CI was below 2.21.min-1.m-2. Conversely CI was below 2.21.min-1.m-2 in patients whose deep body temperature difference was more than 4 degrees C. We conclude that the measurement of deep body temperature difference is useful as a circulatory monitor, and that a critical level of deep body temperature difference is 4 degrees C.

Adult↗
PubMed2004

Effect of body temperature on mortality of acute stroke.

OBJECTIVES: The exact relation between body temperature and mortality of acute stroke victims is poorly understood. However, body temperature can affect the outcome of stroke cases in relation to mortality. In the initial (4-12 hrs) hours of stroke, the temperature rise is often neurogenic in origin and mortality is also higher with raised body temperature. Though the anatomical lesion or nature of lesion along with other established risk factors influence the mortality of stroke cases, change in temperature does affect the outcome of stroke cases. We sought to find out the significance of stroke victim's body temperature (within 4-12 hrs) with respect to short-term mortality rate in our study. METHODS: We selected 100 ischemic and 100 hemorrhagic stroke patients proved by CT scan of brain and 2-hrly oral temperature was strictly recorded for the initial 4-12 hrs of admission. RESULTS: It was evident from the study that hyperthermia (>37.5 degrees C) was associated with highest mortality rate in both hemorrhagic (51.78%) and ischemic (56.66%) cases. In normothermic group, mortality was 13.5% and 8.8% in hemorrhagic and ischemic group respectively, whereas hypothermia (<36.5 degrees C) was associated with 0 % mortality. CONCLUSION: Hyperthermia in acute stroke victim carries a bad prognostic parameter in short term basis.

Acute Disease↗
PubMed1979

[Body temperature during fasting in chickens of various ages and body weight].

Chickens of different ages will be submitted to periods of non-eating of 2 to 10 days. The non-eating causes a constant lowering of the body temperature which, in the 10 days old chickens, is 4-5 times higher than in the 3 months old ages. To an higher diminishing of the temperature it corresponds an higher loss percentage of weight. In normal conditions the temperature tends to increase from morning to evening, while during the non-eating period it diminishes. With repeated non-eating periods the colling increases. The difference between young and old animals would depend on differences in quantity of their basal metabolism (lower in the old aged) and on the different availability of energetic material in reserve (higher percentage in the old aged).

Animals↗
PubMed2003

Body temperature, oxygen uptake and heart rate during walking in water and on land at an exercise intensity based on RPE in elderly men.

The purpose of this study was to clarify the characteristics of the physiological response that occurs while walking in water and on land at an exercise intensity based on the rating of perceived exertion (RPE) in elderly men. Nine elderly men ranging from 66-70 years of age participated in this study as subjects. The actual trials consisted of walking for 20 minutes in 31 degrees C and 35 degrees C water on an underwater treadmill. The water depth of the treadmill corresponded to the level of the xiphoid process in the subject. The same subjects performed on-land walking using a moving belt treadmill for 20 minutes at a room temperature of 27 degrees C. The exercise intensity during walking in the two water trials and the on-land trial was the same "somewhat hard" measured on the basis of the subject's RPE rating of 13. There was no significant difference between the subjects' rectal temperatures among the three trials. The mean skin temperature and mean body temperature while walking for 20 minutes in 35 degrees C water were significantly higher (P<0.01) than in 31 degrees C water and on land. There were no significant differences in oxygen uptake and heart rate among the two trials in water and the on-land trial. The above results suggest that the exercise intensity based on a subject's RPE may be an effective index for the prescription of thermoneutral water walking in the same way that it is for land walking in the elderly.

Aged↗
PubMed2002

Body temperature patterns before, during, and after semi-natural hibernation in the European ground squirrel.

Ground squirrels undergo extreme body temperature fluctuations during hibernation. The effect of low body temperatures on the mammalian circadian system is still under debate. Using implanted temperature loggers, we recorded body temperature patterns in European ground squirrels kept in an enclosure under natural conditions. Although hibernation onset was delayed, hibernation end corresponded closely to that measured in a field population. Circadian body temperature fluctuations were not detected during deep torpor, but indications of circadian timing of arousal episodes at higher temperatures were found at the beginning and end of hibernation. One male exhibited synchronised arousals to a relatively constant phase of the day throughout hibernation. All animals first entered torpor in the afternoon. Daily body temperature fluctuations were decreased or distorted during the first days after hibernation. We hypothesise that hibernation may affect the circadian system by either decreasing the expression of the circadian oscillator, or by decreasing the amplitude of the circadian oscillator itself. possibly due to gradual, temperature dependent, internal desynchronisation. The latter mechanism may be beneficial because it might facilitate post-hibernation re-entrainment rates.

Animals↗
PubMed2003

Metabolic heat production, heat loss and the circadian rhythm of body temperature in the rat.

Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase-advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase-delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1 % of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature.

Animals↗
PubMed2001

Effect of melatonin on circadian rhythm, locomotor activity and body temperature in the intact house sparrow, Japanese quail and owl.

We compared the effect of melatonin on circadian rhythm, body temperature, and locomotion in the intact house sparrow, Japanese quail and owl. Daily treatment with melatonin at a fixed time did not entrain the free-running rhythm of locomotor activity in the house sparrow and the disrupted rhythm in Japanese quail under constant dim light. However, melatonin clearly inhibited movement for several hours after treatment. The duration of resting after injection of melatonin was dose-dependent. Body temperature was significantly decreased after melatonin treatment, the effect being more potent during the active phase than in the resting phase. Although this effect of melatonin on body temperature was also dose-dependent, the magnitude of the decrease in body temperature after injection of melatonin was greater in the house sparrow than in the Japanese quail. On the other hand, melatonin induced a further large decrease of body temperature in a nocturnal bird, the owl, whose pineal gland is degenerate. The decrease of body temperature was larger in the active phase than in the resting phase, and melatonin did not prevent movement in spite of the decrease in body temperature. These results suggest that the effects of melatonin on circadian rhythm, locomotor activity and body temperature differ among avian species, and that these mechanisms may not be linked to each other.

Animals↗
PubMed2005

Environmental light and suprachiasmatic nucleus interact in the regulation of body temperature.

The mammalian biological clock, located in the suprachiasmatic nucleus (SCN), is crucial for circadian rhythms in physiology and behavior. However, equivocal findings have been reported on its role in the circadian regulation of body temperature. The goal of the present studies was to investigate the interaction between the SCN and environmental light in the regulation of body temperature. All recordings were performed by telemetry in free moving male Wistar rats. Firstly, we demonstrated an endogenous circadian rhythm in body temperature independent of locomotor activity. This rhythm was abolished by stereotactic lesioning of the SCN. Secondly, we demonstrated a circadian phase-dependent suppressive effect of light ('negative masking') on body temperature. Light suppressed body temperature more at the end of the subjective night (circadian time [CT] 22) than in the middle (CT 6) and at the end (CT 10) of the subjective day. This circadian-phase dependent suppression was not demonstrated in SCN-lesioned animals. Surprisingly, after half a year of recovery from lesioning of the SCN, light regained its suppressing action on body temperature, resulting in a daily body temperature rhythm only under light-dark conditions. In contrast to body temperature, light could not substantially mimic a daytime inhibitory SCN-output in the regulation of heart rate and locomotor activity. The present results suggest that, after lesioning of the SCN as main relay station for the immediate body temperature-inhibition by light, secondary relay nuclei can fully take over this function of the SCN. These findings provide a possible explanation for the controversy in literature over the question whether the SCN is required for the diurnal rhythm in body temperature. Furthermore, they show that light may have an acute effect on behavior and physiology of the organism via the SCN, which extends beyond the generally acknowledged effect on melatonin secretion.

Analysis of Variance↗
PubMed2006

Temporal patterns of body temperatures in the acute stage of stroke.

OBJECTIVE: The present study aimed to describe the day-by-day temporal patterns of body temperatures in acute stroke and to delineate the differences in serial daily changes in body temperatures between intracerebral hemorrhage (ICH) and cerebral infarct (CI). METHODS: We retrospectively enrolled 90 patients (32 with ICH and 58 with CI), admitted within 12 hours after the onset of stroke. Body temperatures were measured as the tympanic temperatures during the initial 6 days of hospitalization. Patients with clinical infections were excluded. The severity of stroke was assessed by Scandinavian Stroke Scale (SSS). SSS score < or = 30 was defined as severe stroke, and SSS score >30 as mild-to-moderate stroke. RESULTS: Mean body temperature was significantly higher in patients with ICH than those with CI in 0 approximately 12 hours; 12 approximately 24 hours, 24 approximately 48 hours, and 48 approximately 72 hours (all p<0.05) after the onset of stroke. Among patients with ICH, the body temperature was significantly higher in the severe group than the mild-to-moderate group during 24 approximately 48 hours and 48 approximately 72 hours (both p<0.05) after the onset of stroke. No significant difference in body temperatures was observed between patients with severe stroke and patient with mild-to-moderate CI. CONCLUSIONS: The serial time course of body temperature in the acute stage of stroke differs between ICH and CI. This study showed that, in ICH but not in CI, the elevation of body temperature has significant association with the stroke severity. Our results may help in the management of hyperthermia during acute stroke.

Acute Disease↗
PubMed1985

The influence of raised body temperature on auditory evoked brainstem responses.

The influence of raised body temperature on the auditory evoked brainstem responses (BSER) has been investigated in 9 healthy volunteers. Ipsi- and contralateral BSER recordings were obtained before and after raising body temperature by at least 1 degree C by means of a specially constructed heat cradle. In two of the subjects further BSER recordings were obtained after their body temperature had been allowed to fall again to its preheated level. The results for wave V have been analysed in detail: the latency in the 5 men shortened from a mean of 5.84 ms (s.d. 0.193) to a mean of 5.62 ms (s.d. 0.185). For the 4 women the figures were 5.87 ms (s.d. 0.105) and 5.68 ms (s.d. 0.105). Using paired t-tests this change is highly significant (P less than 0.001). Similar changes were observed in the other waves although they were less consistent. In the 2 subjects who were allowed to cool again after heating, the BSER wave latencies returned to their preheated values. It is concluded that nerve conduction rates in the auditory pathway are influenced by body temperature and that this may have to be taken into account when interpreting BSER recordings.

Adult↗
PubMed2002

Individual variation in body temperature and energy expenditure in response to mild cold.

We studied interindividual variation in body temperature and energy expenditure, the relation between these two, and the effect of mild decrease in environmental temperature (16 vs. 22 degrees C) on both body temperature and energy expenditure. Nine males stayed three times for 60 h (2000-0800) in a respiration chamber, once at 22 degrees C and twice at 16 degrees C, in random order. Twenty-four-hour energy expenditure, thermic effect of food, sleeping metabolic rate, activity-induced energy expenditure, and rectal and skin temperatures were measured. A rank correlation test with data of 6 test days showed significant interindividual variation in both rectal and skin temperatures and energy expenditures adjusted for body composition. Short-term exposure of the subjects to 16 degrees C caused a significant decrease in body temperature (both skin and core), an increase in temperature gradients, and an increase in energy expenditure. The change in body temperature gradients was negatively related to changes in energy expenditure. This shows that interindividual differences exist with respect to the relative contribution of metabolic and insulative adaptations to cold.

Adaptation, Physiological↗
PubMed1991

Body temperature modulates the effect of platelet-activating factor (PAF) on airways responsiveness in the rabbit.

Platelet-activating factor (PAF) is a potent mediator known to cause bronchoconstriction and increase airways responsiveness. In vitro studies have shown that the effects of PAF on cell function can be very temperature-dependent. The aim of the current study was to investigate the effect of elevated body temperature on numbers of circulating cells and pulmonary function in anesthetized rabbits in response to PAF. PAF was given intravenously, at a dose of 1.2 micrograms/kg hour, whereas the control experiments were performed after the animals received a saline infusion. Alteration of airways function was assessed by measuring specific pulmonary conductance (SGL) and dose-response relationships to inhaled histamine, where airways responsiveness was expressed as the effective concentration causing 50% of maximal change in specific airways conductance (EC50SGL). The rabbits were studied at two body temperatures: a normal temperature (rectal temperature of 39.8 C), and a higher temperature (rectal temperature 41.2 degrees C). Changes in circulating inflammatory cells, plasma corticosterone concentrations and in hematocrit were also monitored, to examine some potential mechanisms which might explain why body temperature altered airways responsiveness. At the normal body temperature infusion of PAF caused a significant increase in airways responsiveness (p less than 0.025), while at the high body temperature, there was a significant decrease in responsiveness (p less than 0.025). However, at both body temperatures, a profound but similar thrombocytopenia and neutropenia was observed. While plasma corticosterone levels and hematocrit showed increases coincident with the infusion of PAF, this response was unchanged by altering body temperature. We conclude that increased body temperature reduces the effect of PAF on airways responsiveness apparently through a mechanism independent of PAF effects on hemoconcentration, plasma corticosterone or circulating inflammatory cells.

Aerosols↗
PubMed1997

Lesion of the serotonergic terminals in the suprachiasmatic nuclei limits the phase advance of body temperature rhythm in food-restricted rats fed during daytime.

The daily rhythm of body temperature was recorded in control rats fed ad libitum and subsequently fed during daytime 50% of ad libitum food intake. Aside from the expression of a feeding-associated component, body temperature rhythm was phase advanced (7 h) by a timed caloric restriction; the new plateau of the acrophase of the nocturnal peak was close to the light-dark transition. A lesion of serotonergic (5-HTergic) terminals in the suprachiasmatic nuclei (SCN)-the endogenous circadian clock(s)-was performed by microinjection of the 5-HT neurotoxin 5,7-dihydroxytryptamine (5,7-DHT). During the ad libitum-fed state, the acrophase of body temperature rhythm was not modified by the 5,7-DHT treatment. In response to a timed caloric restriction, however, the phase advance of the nocturnal peak of body temperature rhythm was reduced by 2 h in rats with 5,7-DHT lesions as compared to that of sham-operated rats. Magnitude and day-night pattern of wheel-running activity between the two groups of rats also were analyzed. No intergroup difference was found in the amount of wheel-running activity prior to the time of feeding. Moreover, the phase advance of nocturnal component of locomotor activity rhythm observed toward the time of feeding in sham-operated rats was limited by 5,7-DHT treatment. It is concluded that the photic synchronization of body temperature rhythm does not depend on the 5-HTergic projection to SCN under ad libitum conditions. By contrast, the phase-advancing property of a timed caloric restriction on the daily rhythm of body temperature is mediated by a neuronal circuit involving the 5-HTergic projection to SCN. That the phase advance was not fully eliminated by 5,7-DHT treatment suggests that other pathways participate in this mediation.

Animals↗
PubMed1997

The electrical conductivity of human cerebrospinal fluid at body temperature.

The electrical conductivity of human cerebrospinal fluid (CSF) from seven patients was measured at both room temperature (25 degrees C) and body temperature (37 degrees C). Across the frequency range of 10 Hz-10 kHz, room temperature conductivity was 1.45 S/m, but body temperature conductivity was 1.79 S/m, approximately 23% higher. Modelers of electrical sources in the human brain have underestimated human CSF conductivity by as much as 44% for nearly two decades, and this should be corrected to increase the accuracy of source localization models.

Body Temperature↗
PubMed2002

[Body temperature changes during 7 d -6 degrees head-down bed rest].

Objective. To investigate body temperature changes in man during 7-day -6 degrees head-down bed rest (BR). Method. Body temperatures were measured in the morning (6:00), afternoon (16:00) and evening (20:00) during 7 d BR in 18 healthy males (18-22 years old). Result. Rectal temperature (Tre) in the morning gradually decreased as time (d) of BR increased: after the 4th day of BR (BR4d), Tre significantly reduced compared with the supine control (SC, 36.50 +/- 0.03 degrees C) before BR, and it consistently declined to 36.38 +/- 0.04 degrees C on BR7d; But Tre significantly increased in the afternoon after BR5d and in the evening after BR1d, with the final increments of 0.12 +/- 0.05 degrees C and 0.25 +/- 0.03 degrees C respectively on BR7d. Mean body temperature (Tsk) in the morning was significantly higher from BR2d than its SC, with a final net increase (delta Tsk) of 0.38 +/- 0.14 degrees C on BR7d. And Tsk significantly increased in the afternoon and evening from BR4d, BR2d respectively. Skin temperature on the forehead (Tforehead) elevated in the morning during BR. While in the afternoon and evening, Tforehead were significantly higher from BR7d and BR6d than their SC. Conclusion. Both the difference in time of recording at a BR day and the time (d) of BR have significant influence on Tre, Tsk , and Tforehead (P<0.01). These data suggest that body temperature rhythm, body fluid loss and headward distribution, hypokinesis etc. induced by BR have an impact on human thermal regulation during BR.

Adolescent↗