Effects of thermal underwear on thermal and subjective responses in winter

This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (p<0.05). (3) Among local skin temperature, trunk part (forehead and abdomen) did not show significant differences. After 90-min exposure, the skin temperature of hands and feet under the 18-condition was significantly lower than that under the 23-condition (p<0.001). (4) More than 80% of all the respondents felt comfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.     

mu-1 opioid receptor stimulation decreases body temperature in conscious,unrestrained neonatal rats

The influence of mu-selective opioid agonists on neonatal thermoregulatory mechanisms has received little attention. Opioid treatment in adult subjects can cause either hyper- or hypothermia, depending on the experimental conditions, the strain of rat used, and the dose and route of administration of the drug. The present study assessed the effect of two mu opioid agonists on body temperature in neonatal Wistar rats aged 2 to 13 days. Rat pups were administered either saline or one of the two mu-selective opioid agonists, dermorphin (0.4 mg/kg) or fentanyl (0.06 mg/kg), by subcutaneous injection. Continuous rectal temperatures were measured both prior to and following drug or saline injection in freely moving, conscious animals. Ambient temperature in a plethysmograph chamber was maintained within or close to the thermoneutral zone for pups (32 degrees C). To distinguish between mu-1 and mu-2 effects, all animals received either saline or 10 mg/kg of the irreversible mu-1 antagonist naloxonazine (NALZ) 1 day prior to agonist administration. NALZ on its own had no effect on body temperature. Dermorphin and fentanyl both caused a fall in body temperature in pups of all age groups. The temperature decreases ranged from 0.8 degrees -2.2 degrees C. These opioid-induced changes were inhibited by NALZ pretreatment. Although there was no evidence for endogenous mu-1 opioid activity, this study indicated that stimulation of mu-1 opioid receptors causes a decrease in body temperature in conscious, unrestrained neonatal rats under or close to thermoneutral conditions.     

Thermoregulatory stress during rest and exercise in heat in patients with a spinal cord injury

Twelve subjects with spinal cord injuries and four controls (all male) were exposed to heat while sitting at rest or working at each of three environmental temperatures, 30, 35 and 40 degrees C, with a relative humidity of 50%. Exercise was accomplished at a load of 50 W on a friction-braked cycle ergometer which was armcranked or pedalled. Functional electrical stimulation of the legs was provided to the subjects with quadriplegia and paraplegia to allow them to pedal a cycle ergometer. The data showed that individuals with quadriplegia had the poorest tolerance for heat. As an example, in this group, accomplishing armcrank ergometry while working at an environmental temperature of 40 degrees C resulted in an increase in aural temperature of 2 degrees C in 30 min. The aural temperature of individuals with paraplegia working for the same length of time under the same conditions rose approximately 1 degree C. There was virtually no change in the aural temperature in the control subjects.     

Moderate alterations in lower limbs muscle temperature do not affect postural stability during quiet standing in both young and older women.

Older adults demonstrate increased amounts of postural sway, which may ultimately lead to falls. Temperature is known to have a profound effect on the performance of the neuromuscular system which could have important implications on motor control. It is, therefore, of interest to investigate if the age-related decline in postural stability could be affected by changes in local limbs temperature. The present study investigated the effects of localized warming and cooling on postural sway in nine young (22+/-3 years) and nine older (73+/-3 years) women. Postural sway was assessed, using a single force platform, during quiet standing at three muscle temperature conditions: control (34.2+/-0.2 degrees C), cold (31.3+/-0.3 degrees C) and warm (37.0+/-0.1 degrees C). Two stances were evaluated, the Romberg (large support base) and modified Tandem (narrow support base), under both eyes-open and eyes-closed conditions. Root mean square (RMS), mean velocity (MV), sway area (SA) and mean power frequency (MPF) were calculated from the centre of pressure (COP) displacement. Neither warming nor cooling significantly affected any of the postural parameters which were, however, all higher (P<0.05) in the older group than the young group in all conditions. This study demonstrated that, in quiet standing conditions, a moderate variation (+/-3 degrees C) in lower limbs temperature does not affect postural steadiness in either young or older women.     

Effects of cold storage on field and laboratory performance of Trichogramma carverae (Hymenoptera: Trichogrammatidae) and the response of three Trichogramma spp. (T. carverae, T. nr. brassicae, and T. funiculatum) to cold

Delaying emergence of Trichogramma spp. is critical for commercial production. Here, diapause induction was considered for three species (Trichogramma nr. brassicae Bezdenko, Trichogramma carverae Oatman & Pinto, and Trichogramma funiculatum Carver), and the effect of storage temperature (4 degrees C, 8 degrees C, and 10 degrees C) and time (1-8 wk) was investigated for T. carverae. For all species, percentage of emergence was lowered after an initial diapause induction period (28 d at 14 degrees C and a photoperiod of 8:16 [L:D] h) and lowered further after 1-mo storage at 3 degrees C and a photoperiod of 0:24 (L:D) h. No wasps emerged after 2 mo of storage, suggesting that true diapause was not induced. The effect of 1-8-wk storage on wasp quality was investigated for T. carverae both in the laboratory and the field. Initial fieldwork suggested that this species could be successfully stored at 10 degrees C under continuous light (after 5-d development at 25 degrees C and a photoperiod of 16:8 [L:D] h) without reducing the ability of wasps to parasitize eggs in the field. In a second experiment, storage temperatures lower than 10 degrees C and storage times 3 wk or longer had a negative impact on emergence and longevity, and effects were not additive. Negative effects may partly reflect size changes, because size decreased in response to storage time, and there was an interaction between time and temperature effects on size. Storage time was the major factor influencing fecundity and field success; both fitness measures were reduced after storage of 3 wk or longer. T. carverae can therefore be successfully stored for up to 2 wk without detrimental effects, and 10 degrees C is the preferred storage temperature. T. carverae seems to survive unfavorable temperature conditions by entering a state of quiescence.     

Cooling different body surfaces during upper and lower body exercise

The effect of varying the body surface area being cooled by a liquid microclimate system was evaluated during exercise heat-stress conditions. Six male subjects performed a total of six exercise (O2 uptake = 1.2 l/min) tests in a hot environment (ambient temperature = 38 degrees C, relative humidity = 30%) while dressed in clothing having low moisture permeability and high insulation. Each subject completed two upper body exercise (U; arm crank) tests: 1) with only the torso surface (T) cooled; and 2) with the surfaces of both the torso and upper arms (TA) cooled [coolant temperature at the inlet (Ti) was 20 degrees C for all upper body tests]. Each subject also completed four lower body exercise (L; walking) tests: 1) with only the T cooled (Ti = 20 degrees C); 2) with only the T cooled (Ti = 26 degrees C); 3) with torso, upper arm, and thigh surface (TAT) cooled (Ti = 20 degrees C); and 4) with TAT cooled (Ti = 26 degrees C). During U exercise, TA cooling had no effects compared with cooling only T. During L exercise, sweat rates, heart rates, and rectal temperature (Tre) changes were less with TAT cooling compared with cooling only the T. Altering Ti had no effect on Tre changes, but higher heart rates were observed with 26 than with 20 degrees C. These data indicate that cooling arms during upper body exercise provides no thermoregulatory advantage, although cooling the thigh surfaces during lower body exercise does provide an advantage.     

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.     

Effects of room temperature on physiological and subjective responses during whole-body bathing,half-body bathing and showering

The effects of bathroom thermal conditions on physiological and subjective responses were evaluated before, during, and after whole-body bath (W-bath), half-body bath (H-bath) and showering. The air temperature of the dressing room and bathroom was controlled at 10 degrees C, 17.5 degrees C, and 25 degrees C. Eight healthy males bathed for 10 min under nine conditions on separate days. The water temperature of the bathtub and shower was controlled at 40 degrees C and 41 degrees C, respectively. Rectal temperature (Tre), mean skin temperature (Tsk), blood pressure (BP), heart rate (HR), body weight loss and blood characteristics (hematocrit: Hct, hemoglobin: Hb) were evaluated. Also, thermal sensation (TS), thermal comfort (TC) and thermal acceptability (TA) were recorded. BP decreased rapidly during W-bath and H-bath compared to showering. HR during W-bath was significantly higher than for H-bath and showering (p < 0.01). The double products due to W-bath during bathing were also greater than for H-bath and showering (p < 0.05). There were no distinct differences in Hct and Hb among the nine conditions. However, significant differences in body weight loss were observed among the bathing methods: W-bath > H-bath > showering (p < 0.001). W-bath showed the largest increase in Tre and Tsk, followed by H-bath, and showering. Significant differences in Tre after bathing among the room temperatures were found only at H-bath. The changes in Tre after bathing for H-bath at 25 degrees C were similar to those for W-bath at 17.5 degrees C and 10 degrees C. TS and TC after bathing significantly differed for the three bathing methods at 17.5 degrees C and 10 degrees C (TS: p < 0.01 TC: p < 0.001). Especially, for showering, the largest number of subjects felt "cold" and "uncomfortable". Even though all of the subjects could accept the 10 degrees C condition after W-bath, such conditions were intolerable to half of them after showering. These results suggested that the physiological strains during H-bath and showering were smaller than during W-bath. However, colder room temperatures made it more difficult to retain body warmth after H-bath and created thermal discomfort after showering. It is particularly important for H-bath and showering to maintain an acceptable temperature in the dressing room and bathroom, in order to bathe comfortably and ensure warmth.     

Extracellular determinants of cardiac contractility in the cold anoxic turtle

Painted turtles (Chrysemys picta) survive months of anoxic submergence, which is associated with large changes in the extracellular milieu where pH falls by 1, while extracellular K+, Ca++, and adrenaline levels all increase massively. While the effect of each of these changes in the extracellular environment on the heart has been previously characterized in isolation, little is known about their interactions and combined effects. Here we examine the isolated and combined effects of hyperkalemia, acidosis, hypercalcemia, high adrenergic stimulation, and anoxia on twitch force during isometric contractions in isolated ventricular strip preparations from turtles. Experiments were performed on turtles that had been previously acclimated to warm (25 degrees C), cold (5 degrees C), or cold anoxia (submerged in anoxic water at 5 degrees C). The differences between acclimation groups suggest that cold acclimation, but not anoxic acclimation per se, results in a downregulation of processes in the excitation-contraction coupling. Hyperkalemia (10 mmol L(-1) K+) exerted a strong negative inotropic effect and caused irregular contractions; the effect was most pronounced at low temperature (57%-97% reductions in twitch force). Anoxia reduced twitch force at both temperatures (14%-38%), while acidosis reduced force only at 5 degrees C (15%-50%). Adrenergic stimulation (10 micromol L(-1)) increased twitch force by 5%-19%, but increasing extracellular [Ca++] from 2 to 6 mmol L(-1) had only small effects. When all treatments were combined with anoxia, twitch force was higher at 5 degrees C than at 25 degrees C, whereas in normoxia twitch force was higher at 25 degrees C. We propose that hyperkalemia may account for a large part of the depressed cardiac contractility during long-term anoxic submergence.     

Hypercapnia increases core temperature cooling rate during snow burial.

Previous retrospective studies report a core body temperature cooling rate of 3 degrees C/h during avalanche burial. Hypercapnia occurs during avalanche burial secondary to rebreathing expired air, and the effect of hypercapnia on hypothermia during avalanche burial is unknown. The objective of this study was to determine the core temperature cooling rate during snow burial under normocapnic and hypercapnic conditions. We measured rectal core body temperature (T(re)) in 12 subjects buried in compacted snow dressed in a lightweight clothing insulation system during two different study burials. In one burial, subjects breathed with a device (AvaLung 2, Black Diamond Equipment) that resulted in hypercapnia over 30-60 min. In a control burial, subjects were buried under identical conditions with a modified breathing device that maintained normocapnia. Mean snow temperature was -2.5 +/- 2.0 degrees C. Burial time was 49 +/- 14 min in the hypercapnic study and 60 min in the normocapnic study (P = 0.02). Rate of decrease in T(re) was greater with hypercapnia (1.2 degrees C/h by multiple regression analysis, 95% confidence limits of 1.1-1.3 degrees C/h) than with normocapnia (0.7 degrees C/h, 95% confidence limit of 0.6-0.8 degrees C/h). In the hypercapnic study, the fraction of inspired carbon dioxide increased from 1.4 +/- 1.0 to 7.0 +/- 1.4%, minute ventilation increased from 15 +/- 7 to 40 +/- 12 l/min, and oxygen saturation decreased from 97 +/- 1 to 90 +/- 6% (P < 0.01). During the normocapnic study, these parameters remained unchanged. In this study, T(re) cooling rate during snow burial was less than previously reported and was increased by hypercapnia. This may have important implications for prehospital treatment of avalanche burial victims.     

Metabolic effects of microwave radiation and convection heating on human mononuclear leukocytes

The effects of microwave radiation (2450 MHz, continuous wave, mean specific absorption rate of 103.5 +/- 4.2 W/kg) and convection heating on the nonphosphorylating oxidative metabolism of human peripheral mononuclear leukocytes (96% lymphocytes, 4% monocytes) at 37 degrees C were investigated. Metabolic activity, determined by chemiluminescence (CL) of cells challenged with luminol (5-amino-2,3-dihydro-1,4-phthalazinedione) linked to bovine serum albumin, was detected with a brightness photometer. A significant stimulation after microwave exposure (p less than 0.005) over total CL of matched 37 degrees C incubator controls was observed. A similar degree of stimulation compared to incubator controls was also detected after sham treatment. There was no significant difference between changes in total CL or stimulation indices of the microwave and sham exposed groups. It appears that exposure to microwave radiation, under normothermic (37 +/- 0.03 degrees C) conditions, has no effect on the oxidative metabolic activity of human peripheral mononuclear leukocytes. However, the significant differences between microwave or sham exposed cells and their respective incubator controls occurred because the temperature of the incubator controls did not exceed 35.9 degrees C and this temperature required 39 minutes to reach from 22 degrees C. Slow heating of incubator controls must be accounted for in thermal and radiofrequency radiation studies in vitro.     

The circadian body temperature rhythm in the elderly: effect of single daily melatonin dosing

The present study is part of a more extensive investigation dedicated to the study and treatment of age-dependent changes/disturbances in the circadian system in humans. It was performed in the Tyumen Elderly Veteran House and included 97 subjects of both genders, ranging from 63 to 91 yrs of age. They lived a self-chosen sleep-wake regimen to suit their personal convenience. The experiment lasted 3 wks. After 1 control week, part of the group (n=63) received 1.5 mg melatonin (Melaxen) daily at 22:30 h for 2 wks. The other 34 subjects were given placebo. Axillary temperature was measured using calibrated mercury thermometers at 03:00, 08:00, 11:00, 14:00, 17:00, and 23:00 h each of the first and third week. Specially trained personnel took the measurements, avoiding disturbing the sleep of the subjects. To evaluate age-dependent changes, data obtained under similar conditions on 58 young adults (both genders, 17 to 39 yrs of age) were used. Rhythm characteristics were estimated by means of cosinor analyses, and intra- and inter-individual variability by analysis of variance (ANOVA). In both age groups, the body temperature underwent daily changes. The MESOR (36.38+/-0.19 degrees C vs. 36.17+/-0.21 degrees C) and circadian amplitude (0.33+/-0.01 degrees C vs. 0.26+/-0.01 degrees C) were slightly decreased in the elderly compared to the young adult subjects (p<0.001). The mean circadian acrophase was similar in both age groups (17.19+/-1.66 vs. 16.93+/-3.08 h). However, the inter-individual differences were higher in the older group, with individual values varying between 10:00 and 23:00 h. It was mainly this phase variability that caused a decrease in the inter-daily rhythm stability and lower group amplitude. With melatonin treatment, the MESOR was lower by 0.1 degrees C and the amplitude increased to 0.34+/-0.01 degrees C, a similar value to that found in young adults. This was probably due to the increase of the inter-daily rhythm stability. The mean acrophase did not change (16.93 vs. 16.75 h), although the inter-individual variability decreased considerably. The corresponding standard deviations (SD) of the group acrophases were 3.08 and 1.51 h (p<0.01). A highly significant correlation between the acrophase before treatment and the phase change under melatonin treatment indicates that this is due to a synchronizing effect of melatonin. Apart from the difference in MESOR, the body temperature rhythm in the elderly subjects undergoing melatonin treatment was not significantly different from that of young adults. The data clearly show that age-dependent changes mainly concern rhythm stability and synchronization with the 24 h day. A single daily melatonin dose stabilizes/synchronizes the body temperature rhythm, most probably via hypothermic and sleep-improving effects.     

Effect of muscle temperature on leg extension force and short-term power output in humans

The effect of changing muscle temperature on performance of short term dynamic exercise in man was studied. Four subjects performed 20 s maximal sprint efforts at a constant pedalling rate of 95 crank rev.min-1 on an isokinetic cycle ergometer under four temperature conditions: from rest at room temperature; and following 45 min of leg immersion in water baths at 44; 18; and 12 degrees C. Muscle temperature (Tm) at 3 cm depth was respectively 36.6, 39.3, 31.9 and 29.0 degrees C. After warming the legs in a 44 degrees C water bath there was an increase of approximately 11% in maximal peak force and power (PPmax) compared with normal rest while cooling the legs in 18 and 12 degrees C water baths resulted in reductions of approximately 12% and 21% respectively. Associated with an increased maximal peak power at higher Tm was an increased rate of fatigue. Two subjects performed isokinetic cycling at three different pedalling rates (54, 95 and 140 rev.min-1) demonstrating that the magnitude of the temperature effect was velocity dependent: At the slowest pedalling rate the effect of warming the muscle was to increase PPmax by approximately 2% per degree C but at the highest speed this increased to approximately 10% per degree C.     

No evidence for brain stem cooling during face fanning in humans.

The interpeak latencies (IPLs) of the acoustically evoked brain stem potentials depend on brain stem temperature. This was used to see whether face fanning during hyperthermia lowers brain stem temperature. In 15 subjects, three thermally stable conditions were maintained by a water bath. In each condition the IPLs were determined in 10 separate trials. In condition A esophageal temperature (Tes) was 36.9 +/- 0.3 degrees C and increased to 38.6 +/- 0.2 degrees C in condition B. In conditions A and B the head was enclosed in a ventilated hood (air temperature 38 degrees C, relative humidity 100%) to suppress any direct heat loss from the head. From conditions A to B the IPL at peaks I-V decreased by 0.146 ms/degrees C change in Tes, reflecting a change in brain stem temperature. In condition C the hood was removed and the face was fanned by a cold air-stream (8-15 degrees C, 4-10 m/s) to maximize direct heat loss from the head. Skin temperature at the sweating forehead decreased from 38 to 23 degrees C, whereas Tes in condition C was maintained at the same level as in condition B (38.5 +/- 0.2 degrees C). The IPL at peaks I-V showed no difference between conditions B and C. It is concluded that face fanning in hyperthermic subjects does not dissociate brain stem temperature from Tes.     

Perception of foot temperature in young women with cold constitution: analysis of skin temperature and warm and cold sensation thresholds

To examine the disease state of cold constitution, physiological measurements of the foot were conducted by investigating thermal sensations under an environmental condition of 25 degrees C-26 degrees C (neutral temperature) in 29 young women with and without cold constitution. The subjects were classified into 3 groups according to their experiences with cold constitution: cold constitution, intermediate, and normal groups. Foot skin temperature was measured by thermography. Thermal sensations were measured on the dorsum of the left foot using a thermal stimulator. Cold and warm spots on the dorsum of the right foot were ascertained. Thermal stimulation was delivered by a copper probe. No significant differences in foot skin temperature among these 3 groups were identified as measured in a laboratory under neutral temperature conditions. However, the mean warm sensation threshold was +6.3+/-1.09 degrees C (mean+/-SEM) for the cold constitution group (n=14), +3.4+/-2.10 degrees C (mean+/-SEM) for the intermediate group (n=7), and -0.25+/-1.96 degrees C (mean+/-SEM) for the normal group (n=6). The difference was significant between the cold constitution and normal groups. No significant differences among the 3 groups were found in the cold sensation threshold. This may be attributable to the distribution of thermal receptors and to chronically reduced blood flow in subcutaneous tissues, where the skin temperature receptors responsible for temperature sensation are located.     

Thermal effects of whole head submersion in cold water on nonshivering humans.

This study isolated the effect of whole head submersion in cold water, on surface heat loss and body core cooling, when the confounding effect of shivering heat production was pharmacologically eliminated. Eight healthy male subjects were studied in 17 degrees C water under four conditions: the body was either insulated or uninsulated, with the head either above the water or completely submersed in each body-insulation subcondition. Shivering was abolished with buspirone (30 mg) and meperidine (2.5 mg/kg), and subjects breathed compressed air throughout all trials. Over the first 30 min of immersion, exposure of the head increased core cooling both in the body-insulated conditions (head out: 0.47 +/- 0.2 degrees C, head in: 0.77 +/- 0.2 degrees C; P < 0.05) and the body-exposed conditions (head out: 0.84 +/- 0.2 degrees C and head in: 1.17 +/- 0.5 degrees C; P < 0.02). Submersion of the head (7% of the body surface area) in the body-exposed conditions increased total heat loss by only 10%. In both body-exposed and body-insulated conditions, head submersion increased core cooling rate much more (average of 42%) than it increased total heat loss. This may be explained by a redistribution of blood flow in response to stimulation of thermosensitive and/or trigeminal receptors in the scalp, neck and face, where a given amount of heat loss would have a greater cooling effect on a smaller perfused body mass. In 17 degrees C water, the head does not contribute relatively more than the rest of the body to surface heat loss; however, a cold-induced reduction of perfused body mass may allow this small increase in heat loss to cause a relatively larger cooling of the body core.     

Effects of transport container and ambient storage temperature on motion characteristics of equine spermatozoa

This study was conducted to compare the cooling rates and storage temperatures within equine semen transport containers exposed to different ambient temperatures, and to evaluate the ability of these containers to preserve spermatozoal motility following 24 h of storage under these conditions. In Experiment 1, nonfat dried milk solids, glucose, sucrose, equine semen extender was divided into seven 40-mL aliquots and loaded into seven different semen transport containers: Equitainer I, Equitainer II, Equitainer III, ExpectaFoal, Bio-Flite, Lane STS, and Equine Express. After containers were loaded, they were subjected to one of three ambient storage temperatures: 1) 22 degrees C for 72 h, 2) -20 degrees C for 6 h followed by 22 degrees C for 66 h, or 3) 37 degrees C for 72 h. Cooling rates and storage temperatures of semen extender in each container were monitored with thermocouples and a chart recorder. In Experiment 2, semen from each of three stallions (3 ejaculates per stallion) was diluted to 25 x 10(6) spermatozoa/mL with semen extender, divided into 40 mL aliquots and loaded into transport containers as in Experiment I. Containers were subjected to one of three ambient storage conditions: 1) 22 degrees C for 24 h, 2) -20 degrees C for 6 h, followed by 22 degrees C for 18 h, or 3) 37 degrees C for 24 h. After 24 h of storage, spermatozoal motion characteristics (percentage of motile spermatozoa; MOT, percentage of progressively motile spermatozoa; PMOT, and mean curvilinear velocity; VCL) were evaluated using a computerized spermatozoal motion analyzer. Significant interactions were detected among storage conditions and semen transport containers for the majority of the temperature endpoints measured. When exposed to temporary ambient freezing conditions, the lowest temperatures attained by samples in containers ranged from -2.8 to 0.8 degrees C. Lowest temperature samples attained was not correlated (P > 0.05) with spermatozoal motility under any ambient condition. However, time below 4 degrees C was highly correlated (P < 0.05) with a reduction in spermatozoal motility. Mean cooling rates from 20 degrees C to 8 degrees C did not correlate with spermatozoal motility, except when containers were exposed to temporary freezing conditions. No container cooled samples below 6 degrees C in 22 degrees C or 37 degrees C environments except for the ExpectaFoal, in which samples fell below 4 degrees C under all ambient conditions. Ambient temperature affected MOT, PMOT and VCL of semen stored in all containers (P < 0.05) except for the Equitainer II in which motion characteristics remained high and were similar among all ambient temperatures (P > 0.05). Results suggest that stallion semen may be able to tolerate a wider range of cooling rates and storage temperatures than previously considered safe.     

Continuous Monitoring of Post Mortem Temperature Changes in the Human Brain

Recent developments in neurochemistry research on the post mortem human brain require a detailed understanding of the post mortem changes in the human brain, including the correlation between time related temperature changes and alterations in biochemical parameters. As an initial step towards our deeper insight into the intricate relationships between post mortem time, temperature and neurochemical processes, in the present study we set out to monitor continuously temperature changes in the post mortem human brain in eight cadavers for a period of up to 24 h after death under 'standard' clinical conditions at a neurosurgery clinic. A main objective of the study was to find a simple and reliable mathematical formula, requiring only time and an easily obtainable body temperature measurement parameter, with the help of which the superficial and deep brain temperatures can be obtained without invasive interactions. With a portable thermoprobe data logger system superficial (4 cm from skull surface) and deep (8 cm) brain temperatures, the temperature of the liver and that of the forehead skin, as well as the ambient temperature of the room were measured at regular time intervals (every 1 or 5 min). Various mathematical models were fitted to the data in order to create a simple model capable to predict brain temperatures from easily accessible measurements, such as that of the forehead skin. On the basis of the tested models we propose that with simple polynomial equations the deep and superficial brain temperatures can be described reliably as T (br4) ( degrees C)=T (fh)-0.001t (3)+0.0541t (2)-1.0622t+7.5933 and T (br8) ( degrees C)=T (fh)-0.0003t (3)+0.0201t (2)-0.619t+7.9036, respectively, where T (br4) is the superficial (4 cm) brain temperature, T (br8) is the deep (8 cm) brain temperature, T (fh) is the forehead temperature and t is the time from death. These measurements can, in combination with further neurochemical studies, contribute to our better understanding of the human brain's time- and temperature-related post mortem biochemical changes.     

Immune changes in humans during cold exposure: effects of prior heating and exercise.

This study examined the immunological responses to cold exposure together with the effects of pretreatment with either passive heating or exercise (with and without a thermal clamp). On four separate occasions, seven healthy men [mean age 24.0 +/- 1.9 (SE) yr, peak oxygen consumption = 45.7 +/- 2.0 ml. kg(-1). min(-1)] sat for 2 h in a climatic chamber maintained at 5 degrees C. Before exposure, subjects participated in one of four pretreatment conditions. For the thermoneutral control condition, subjects remained seated for 1 h in a water bath at 35 degrees C. In another pretreatment, subjects were passively heated in a warm (38 degrees C) water bath for 1 h. In two other pretreatments, subjects exercised for 1 h at 55% peak oxygen consumption (once immersed in 18 degrees C water and once in 35 degrees C water). Core temperature rose by 1 degrees C during passive heating and during exercise in 35 degrees C water and remained stable during exercise in 18 degrees C water (thermal clamping). Subsequent cold exposure induced a leukocytosis and granulocytosis, an increase in natural killer cell count and activity, and a rise in circulating levels of interleukin-6. Pretreatment with exercise in 18 degrees C water augmented the leukocyte, granulocyte, and monocyte response. These results indicate that acute cold exposure has immunostimulating effects and that, with thermal clamping, pretreatment with physical exercise can enhance this response. Increases in levels of circulating norepinephrine may account for the changes observed during cold exposure and their modification by changes in initial status.