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At least 433 records · Page 24Linked to original sources
PubMed1999

Environmentally responsive temperature instability in pediatric spinal cord injury.

OBJECTIVE: To study the frequency and clinical implications of environmentally responsive temperature instability in hospitalized pediatric patients with spinal cord injury (SCI). SETTING: A tertiary level SCI rehabilitation unit located in a free standing children's hospital in Wilmington, DE, USA. STUDY DESIGN: Temperature data and corresponding clinical responses were collected prospectively between January 1991 and June 1993. Fifty-four consecutive patients with SCI levels at or above T6 were admitted to the pediatric spinal cord injury rehabilitation unit over that time (4059 SCI days). METHODS: Hypothermic events were defined as oral temperatures less than 35.0 degrees C or rectal temperatures less than 35.6 degrees C. Hyperthermic events were defined as oral temperatures greater than 38.0 degrees C or rectal temperatures greater than 38.4 degrees C. The events and the clinical responses were reviewed retrospectively and were used for subsequent analysis if there was evidence of clinical response to environmental manipulation within 4 hours of case identification, and other potential etiologies of temperature fluctuation could be excluded. RESULTS: Sixty-five events of hypothermia (1.60%) and 14 events of hyperthermia (0.34%) were analyzed. Twelve patients (22%) accounted for all 79 events. Subjects with environmentally responsive temperature instability were more recently injured (P<0.001), had longer lengths of stay (P<0.001) and were more likely to be ventilator dependent (P<0.002) than those who did not have environmentally responsive temperature instability. There was no significant difference between the two groups in age, gender, level or etiology of the SCI. There were no adverse clinical outcomes as a result of the environmentally responsive temperature instability. CONCLUSIONS: Environmentally responsive temperature instability affects a select subset of pediatric aged spinal cord injured persons. Early recognition of the potential contribution of the environment to temperature fluctuation in this group has led to the successful utilization of a temperature instability protocol on our SCI unit.

Adolescent↗
PubMed1977

Fall in skin temperature during exercise.

During light work using the arm in a warm environment, skin temperatures of the arms and chest fell and remained at lower levels during work. The fall in skin temperature during work was not observed in a cool environment. The fall in skin temperature was nearly proportional to work intensity and was observed in both static and dynamic work. Leg work of moderate intensity produced an initial decline and a subsequent rise in skin temperatures of the hands, thighs and legs. A significant fall in skin temperature was observed not only in the foot but also in inactive regions such as the epigastrium. The mean skin temperature remained practically unchanged during work. The fall in skin temperature during work was not due to increased evaporative cooling, but was the result of segmental vasoconstriction probably caused as a reflex in the spinal cord by non-thermal afferents from exercising muscles or moving tissues. The effect of thermoregulatory vasodilation was reduced by the reflex vasoconstriction caused by non-thermal factors. The rise in internal temperature during work could be explained by decreased heat loss due to persistently lower skin temperature.

Adult↗
PubMed2000

Effects of color temperature of fluorescent lamps on body temperature regulation in a moderately cold environment.

A study on the effects of different color temperatures of fluorescent lamps on skin and rectal temperatures in a moderately cold environment involving (i) changes in skin temperature of 7 male subjects exposed to an ambient temperature ranging from 28 degrees C to 18 degrees C (experiment I) and (ii) changes in skin and rectal temperatures and metabolic heat production of 11 male subjects exposed to ambient temperature of 15 degrees C for 90 min (Experiment II) was conducted. In Experiment I, the reduction of mean skin temperature from the control value was significantly greater under 3000 K than under 5000 K or 7500 K lighting. In Experiment II, the reductions in mean skin temperature and rectal temperature were respectively greater and smaller under 3000 K than those under 5000 K or 7500 K lighting. However, metabolic heat production was not affected by color temperature conditions. The relationships between morphological and physiological parameters revealed that no significant relation of rectal temperature to body surface area per unit body weight was found only under 3000 K. Furthermore, while the mean skin temperature was independent on the mean skinfold thickness under 3000 K, a significant negative correlation between the rectal and mean skin temperatures was observed. Therefore, body heat loss might be suppressed effectively by increasing the vasoconstrictor tone under a color temperature of 3000 K, and the body shell was dependent only on morphological factors under 5000 K and 7500 K lighting.

Adult↗
PubMed2003

Thermoregulatory behavior of the crayfish Procambarus clarki in a burrow environment.

The behavioral thermoregulation of the red swamp crayfish, Procambarus clarki, was investigated in its burrow environment. In the field, air and water temperatures within crayfish burrows fluctuated less compared with surface temperatures in the Mojave Desert. However, crayfish could still experience sub-optimal temperature regimes inside burrows. In the laboratory, P. clarki heated and cooled more rapidly in water than in air. In a thermal gradient, the crayfish selected a water temperature of 22 degrees C and avoided water temperatures above 31 degrees C and below 12 degrees C. Observations of behavior in an artificial burrow showed that P. clarki displayed three main shuttling behaviors between water and air in response to temperature. The number of bilateral emersions and emigrations, as well as the amount of time spent in air (in a 24 h period), were significantly greater at 34 degrees C than at 12, 16, 22 or 28 degrees C. This reflected an increased use of the behavioral thermoregulation at temperatures approaching the critical thermal maximum of this species. Upon migrating from 34 degrees C water into 38 degrees C air, crayfish body temperature decreased significantly. These periods of emersion were interspersed with frequent dipping in the water, allowing the crayfish to gain the benefits of evaporative cooling, without the physiological costs incurred by long-term exposure to air.

Air↗
PubMed1998

The relationships of body temperature to weight gain, feed consumption, and feed utilization in broilers under heat stress.

Commercial broiler males were used to evaluate body temperature response to heat stress and its relationship to gain, feed consumption, and feed conversion ratio. Individual gain, feed consumption, and feed conversion ratio were obtained from 28 to 49 d in a heat stress environment (32 C) and compared to a 21 C environment. Body temperatures were measured at 28, 35, and 42 d, then daily from 43 to 48 d, and correlated with 28 to 49 d gain, feed consumption, and feed conversion ratio. Feather cover was measured at 51 d of age as a percentage of BW. Initial 28-d body temperature was not significantly different between 21 and 32 C. Body temperature was significantly higher in the 32 C environment after 7 d of heat stress and was significantly higher than at 21 C at all points through 21 d of heat stress, with mean differences ranging from 0.5 to 1.0 C. Feather weight as a percentage of BW was significantly greater in the 21 C environment (6.22%) than the 32 C environment (5.03%). Mortality was not affected by the heat stress environment. Correlations between body temperature and gain, feed consumption, and feed conversion ratio were low and nonsignificant for most periods in the 21 C environment. In the 32 C environment, body temperature was significantly correlated with gain, feed consumption, and feed conversion ratio after 7 d of heat stress, with mean correlations of -0.40 for gain, -0.31 for feed consumption, and 0.24 for feed conversion ratio in Replicate 1 and -0.44 for gain, -0.40 for feed consumption, and 0.43 for feed conversion ratio in Replicate 2.

Aging↗
PubMed1984

Effects of confinement on attainment of puberty in gilts.

The present work is a review of experiments realized in order to determine the effects of confinement conditions on attainment of puberty in gilts. Few authors have compared age at first estrus or first ovulation of gilts bred in total confinement, in open front buildings and in outdoor dirt lots. Results are not always significant but lead to conclude to a detrimental effect of confinement on attainment of puberty (5 to 17 day delay). Interactions with other factors such as genotype, season of birth, age at treatment explain the differences between results. Large variations are also observed in the response of confined gilts housed in different conditions of intensity and duration of light, temperature and social environment. However, high temperature and individual penning induce a delay in age at puberty (4 to 10 days). Although the sexual development is known to depend on hormonal control, studies regarding the influence of environmental conditions on hormonal secretions are recent, rather scarce and incomplete. Significant variations in the pineal gland activity, the plasma levels of prolactin, LH and estrogens have not yet been associated with confinement, intensity and duration of light. A disruption of the corticosteroid rythm has been observed in individual compared to group penned animals. Estrus response to gonadotropin hormones is not modified but ovarian response to estrogen is reduced by confinement. Further experiments taking into account the existence of interactions between genotype, light and temperature conditions, season of birth and social relations are required in order to investigate more precisely the influence of the different types of environment on the hormonal secretions and consequently the sexual development of gilts.

Age Factors↗
PubMedDate not supplied

[Salmonella typhimurium population in water environment under the influence of temperature].

The strategy of the adaptation of S. typhimurium population to water environment under the influence of temperature factor was studied by scanning electron microscopy. Salmonellae were found to adhere to the surface of the Daphnia chitin covering. The study revealed that S. typhimurium population existed in water in the form of covered microcolonies as well as in the form of spheroplast-type cells and small cells in the L-form, joined with bands. The viability of salmonellae in water environment was studied without interaction and following interaction with Daphnia.

Adaptation, Physiological↗
PubMed1978

Voluntary increase in finger temperature in man in a cooling environment.

To test whether man can increase voluntarily skin temperature in a cool environment, 14 subjects (age 15--51) were studied. They came once or twice a week for five to eight sessions of 1 h. The room temperature of various sessions varied from 21.2 to 15.6 degrees C. Temperatures of six fingers were recorded using thermocouples. During trials to increase temperature, subjects were shown a dial indicating temperature of an index finger and were instructed to try to warm their hands. The trials were begun when skin temperatures were stable or were falling, indicating that vasoconstriction was occurring. They were preceded and followed by a rest period. The differences between changes in temperature during the trials and the rest periods were significant for the group of 14 subjects (p less than 0.01). In 10 subjects with individually significant results, differences between the trial and rest periods averaged 5.0 degrees C for 'the best' and 3.9 degrees C for 'the worst' finger. The maximum temperatures during the trials averaged 30.9 +/- 1.0 degrees C (mean +/- SE) in 'the best' finger. During later sessions, subjects were able to increase temperatures without seeing the dial. The results indicate that humans are able to increase voluntarily cutaneous finger blood flow in a cool environment.

Adolescent↗
PubMed1991

[The water-salt metabolic state of guinea pigs after a prolonged stay at different temperatures of a hyperbaric environment].

Guinea-pigs were exposed for 6-10 days to a helio-oxygen mixture with the pressure 6 x 10(5) and 36 x 10(5) Pa and temperature 30.5 degrees C to 34.5 degrees C. The concentration of cations was studied in the blood serum and cortex, outer medulla and papilla of the kidney. At the optimal temperature of the helio-oxygen mixture, the concentrations of sodium, potassium, calcium, magnesium and osmotically active substances did not differ from the control in the blood serum. In these conditions, the renal ability to create osmotic gradient does not change, i.e. the systems responsible for the permanence of the cation composition of internal milieu work in a sufficiently effective way and maintain a stable concentration of ions in the blood serum.

Animals↗
PubMedDate not supplied

The measurement of radiant temperature in neonatal thermal environments.

Heat exchange through radiation is recognized as the dominant mode of heat transfer for an infant nursed in an incubator or warmer. A radiometer was constructed to measure the planar radiant temperature experienced by the infant. Two heat-flow sensors of different emissivities were mounted onto a heat sink such that one measured principally convective heat exchange while the other measured convective and radiant heat exchange. The radiant heat exchange was obtained from the difference between these values, from which the planar radiant temperature could be calculated. The spatial variation in planar radiant temperatures within an incubator and warmer was determined by orienting the instrument towards the five orthogonal hemispheres sensed by the infant abdomen, sides, head, and feet. In the incubator, the spatial variation in radiant temperatures exceeded 2 degrees C, or four times the spatial variation in air temperatures (0.5 degrees C). The radiant warmer had a spatial variation of 18 degrees C in radiant temperature at three-fourths of maximum power, corresponding to a variation in heat flux over the infant's surface of 100 W/m2. This thermal asymmetry would be expected to influence the variation in surface skin temperature, and thus the thermal stimuli to the infant thermoregulatory system. Further research is needed to understand the clinical significance of this asymmetry. Furthermore, the precise control over air temperature in modern incubators provides a false sense of thermal control and stability. Radiant temperature needs to be measured in addition to air temperature if the thermal performances of incubators and warmers are to be fully understood.

Calibration↗