Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Temperature environment”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources
PubMed1976

Acclimatization in a hot, humid environment: energy exchange, body temperature, and sweating.

Four trained young men, worked for 4 h/day at 43-50% of their maximum aerobic capacity for 3 days at 25 degrees C db, 18 degrees C wb and then for 10 consecutive days at 45 degrees C db, 32 degrees C wb. Their thermal status was assessed using direct calorimetry. As a group, the men showed classical acclimization responses, but there were marked individual differences. The calorimetric analysis revealed that reductions in strain were associated with minor changes in heat balance confined to the first and last hours of exposure. Events occurring within the first 4 days appeared to have little effect on body temperatures. Significant decreases in body temperature took place only when sweat and evaporation rate increased. A 10% increase in evaporation rate was accompanied by a 30% increase in sweat rate and a 200% increase in unevaporated sweat; thus, there is a wasteful overproduction of sweat. By the 10th day skin temperature was confined to the level necessary to evaporate sufficient sweat to achieve thermal balance with a fully wet body surface. The efficiency of heat transport within the body did not change with acclimatization.

Acclimatization↗
PubMed2006

Use of hot water bottles can improve lymphocytopenia.

We observed that patients with lymphocytopenia have a cold external body temperature-especially the abdomen, hips and extremities-as recognized by palpation. Such patients were recommended to use a hot water bottle especially for cold extremities for the purpose of improving "chill". Six cases of lymphocytopenia diagnosed by previous medical doctors within two weeks before consulting our clinic are described in this study. The patients warmed their trunks and extremities by hot water bottles for as long as possible not only while sleeping but also during the daytime. There was no remarkable change in leukocyte count, but granulocytes significantly decreased in number (from 6,716 +/- 4,032 to 5,467 +/- 2,660) (p=0.013), and lymphocytes significantly increased from 718 +/- 211 to 1,845 +/- 406 (p=0.0017). It is important for clinicians to recognize that such an easy method can improve lymphocytopenia.

Adult↗
PubMed2005

Environmental temperature and mortality.

In Finland, mortality increases steeply in autumn, reaches a peak during the Christhmas holidays and declines slowly towards a trough in August. The relative excess in daily mortality (peak vs. trough) is 30% for coronary heart disease, 40% for cerebral vascular accidents and 90% for diseases of the respiratory organs. There is a secondary peak in Midsummer, especially in coronary deaths of working aged men. Mortality is lowest at mean daily temperature of +14 degrees C, and it increases slowly with falling temperature and steeply with increasing temperature. An estimated 2000-3000 extra deaths occur in Finland during the cold season, most of which are people aged 65 years and over but 20% at working age. The number of people dying from high temperatures (over +14 degrees C) in this country in a normal year is 100-200. Heat deaths are mostly certified as being due to cardiovascular or respiratory conditions. Exposure to cold air causes a rise in blood pressure and haemoconcentration which lead to increased tendency to vascular thromboses. In hot weather, haemoconcentration due to sweating and perspiration increases blood viscosity and the risk of thrombosis. Both cold and heat are significant public health hazards which should be taken into account in health care and education of health professionals.

Acclimatization↗
PubMed2006

The contribution of carotid rete variability to brain temperature variability in sheep in a thermoneutral environment.

The degree of variability in the temperature difference between the brain and carotid arterial blood is greater than expected from the presumed tight coupling between brain heat production and brain blood flow. In animals with a carotid rete, some of that variability arises in the rete. Using thermometric data loggers in five sheep, we have measured the temperature of arterial blood before it enters the carotid rete and after it has perfused the carotid rete, as well as hypothalamic temperature, every 2 min for between 6 and 12 days. The sheep were conscious, unrestrained, and maintained at an ambient temperature of 20-22 degrees C. On average, carotid arterial blood and brain temperatures were the same, with a decrease in blood temperature of 0.35 degrees C across the rete and then an increase in temperature of the same magnitude between blood leaving the rete and the brain. Rete cooling of arterial blood took place at temperatures below the threshold for selective brain cooling. All of the variability in the temperature difference between carotid artery and brain was attributable statistically to variability in the temperature difference across the rete. The temperature difference between arterial blood leaving the rete and the brain varied from -0.1 to 0.9 degrees C. Some of this variability was related to a thermal inertia of the brain, but the majority we attribute to instability in the relationship between brain blood flow and brain heat production.

Animals↗
PubMedDate not supplied

An application of randomization for detecting evidence of thermoregulation in timber rattlesnakes (Crotalus horridus) from northwest Arkansas.

Most reptiles maintain their body temperatures within normal functional ranges through behavioral thermoregulation. Under some circumstances, thermoregulation may be a time-consuming activity, and thermoregulatory needs may impose significant constraints on the activities of ectotherms. A necessary (but not sufficient) condition for demonstrating thermoregulation is a difference between observed body temperature distributions and available operative temperature distributions. We examined operative and body temperature distributions of the timber rattlesnake (Crotalus horridus) for evidence of thermoregulation. Specifically, we compared the distribution of available operative temperatures in the environment to snake body temperatures during August and September. Operative temperatures were measured using 48 physical models that were randomly deployed in the environment and connected to a Campbell CR-21X data logger. Body temperatures (n=1,803) were recorded from 12 radiotagged snakes using temperature-sensitive telemetry. Separate randomization tests were conducted for each hour of day within each month. Actual body temperature distributions differed significantly from operative temperature distributions at most time points considered. Thus, C. horridus exhibits a necessary (but not sufficient) condition for demonstrating thermoregulation. However, unlike some desert ectotherms, we found no compelling evidence for thermal constraints on surface activity. Randomization may prove to be a powerful technique for drawing inferences about thermoregulation without reliance on studies of laboratory thermal preference.

Adaptation, Physiological↗
PubMed1992

Interactive effects of thermal environment and dietary amino acid and fat levels on rate and efficiency of growth of pigs housed in a conventional nursery.

In four trials, 480 weanling pigs were housed in a conventional nursery maintained at 20 or 30 degrees C, which represented a cool and hot thermal environment, respectively. They were allowed ad libitum access to corn-soybean meal-dried whey diets containing .7, 1.0, or 1.3% lysine and 0 or 5% added fat (choice white grease). The pigs were weaned between 27 and 33 d of age (7.27 +/- .90 kg) and penned in groups of five for the duration of the 42-d trials. Pigs housed in the cool environment consumed more feed (P < .01), gained more weight (P < .01), and utilized feed more efficiently (P < .01) than those in the hot environment. As dietary lysine levels were increased in the 20 and 30 degrees C environments, daily weight gains and gain:feed ratios increased linearly (P < .01) from d 0 to 21 and quadratically (P < .01) from d 21 to 42. However, the magnitudes of the increases were less in the cool environment, resulting in temperature x lysine interactions (P < .05). As the pig's feed intake, body weight, and heat production increased over time, the 20 and 30 degrees C environments became progressively warmer relative to the animal's zone of thermoneutrality. The associated reductions over time in energy and lysine intakes relative to the pigs' maintenance needs resulted in an increase in the concentration of dietary lysine needed to maximize rate and efficiency of gain in the 30 degrees C environment but not in the 20 degrees C environment (temperature x lysine x period interaction, P < .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed2005

Effect of adverse storage conditions on performance of glucometer test strips.

OBJECTIVE: A study was conducted to assess the impact of adverse storage environments, i.e., not manufacturer recommended, on the performance of reagent test strips used with a point of care testing (POCT) glucometer to measure whole blood glucose levels. DESIGN/SETTING: Glucose reagent test strips were placed in open, i.e., uncapped, and closed, i.e., capped vials. These vials were those used by the manufacturer to package and store the reagent test strips. One of each type of vial was placed in the manufacturer-recommended storage environment at room temperature and the adverse environments (incubator, direct light to mimic sunlight exposure, humidity, and refrigerated). The Accu-Chek Easy glucometer and reagent test strips as well as Accu-Chek Easy high and low glucose control solutions, manufactured by Roche, were used for this study. MAIN OUTCOME MEASURES: On day-3, day-7, and then once every 7 days, one strip from each vial in each environment was tested with the same glucometer using both a high and a low glucose control. The strip was considered failed for a type of vial and storage environment when either control was out of the reference range on a regular testing day and still out of range when tested the subsequent day. Testing continued up to 50 days. RESULTS: For the tested environments it was found that, overall, test strip stability lasted longer for closed vials than open vials. For open vials in adverse storage conditions, the refrigerator environment offered the longest stability at 35 to 50 days and direct light and humidity offered the shortest periods of stability at 3 to 14 days. CONCLUSIONS: The results of this study support the manufacturer's recommendations to store POCT glucose test strips in their original vial, capped, and at room temperature, though refrigeration may offer an alternative storage environment with acceptable stability. As compliance with testing, quality control, and storage instructions is often an issue with POCT, the manufacturers of these systems for blood glucose measurement should design storage systems that allow the patient to store the glucose meter and the reagent strips in the same location. Manufacturers may also need to consider designing storage systems that are more portable, knowing that patients must take the glucose meters and test strips with them when they travel. Roche's Accu-Chek Compact system is an example of such a design. The glucose test strips are incorporated into a drum that is stored in the Accu-Chek meter itself. When a patient performs a fingerstick blood glucose measurement, the drum advances to move a test strip outside the meter. When the test is complete, the test strip is ejected for disposal. Future studies to clarify the effect of adverse storage conditions, particularly refrigeration, on the integrity of POCT test systems and reagent strips is warranted with currently marketed brands.

Blood Glucose↗
PubMed2003

Environment affects stress in exercised turbot.

We investigated the interaction of water temperature (10, 18 and 22 degrees C) and salinity (33.5 and 15 per thousand ) on the stress response of juvenile turbot. At each temperature/salinity combination, fish were subjected to 10 min enforced exercise. This induced a moderate stress response, which differed at the various temperature and salinity combinations. High temperatures caused more rapid increases in plasma cortisol and glucose, larger and more rapid increases in plasma lactate levels, which were also influenced by body weight, and a faster recovery in plasma Na(+) and Cl(-). Low salinity ameliorated cortisol responses at low but not at high temperatures. The magnitude of ionic disturbance was reduced at 15 per thousand. Plasma K(+) did not change at any temperature or salinity. The stress response involved activation of the brain-pituitary-interrenal axis, as indicated by the cortisol elevations. The low magnitude of glucose responses, the mild Na(+) and Cl(-) disturbances, and the lacking K(+)-responses indicated mild activation of the brain-sympathetic-chromaffin cell axis, and hence a low release of catecholamines, which seemed though to occur to a higher extent at higher temperatures. The relatively low catecholaminergic response of turbot may be linked to their inactive sedentary lifestyle. The higher responsiveness at higher water temperatures may reflect a higher overall adaptive capacity.

Animals↗
PubMedDate not supplied

Benzodiazepine-resistant "brown fat" pattern in positron emission tomography: two case reports of resolution with temperature control.

PURPOSE: Supraclavicular uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) on positron emission tomography (PET) scan is attributed to lymph node, muscle, or brown fat activity. Differentiation between physiological or pathological etiologies is necessary. Benzodiazepine premedication to reduce physiological uptake has been attempted with variable success. A relationship between brown-fat FDG uptake and cold temperature has also been established. To our knowledge, no case reports or studies have been published to demonstrate whether controlling the temperature can alter the physiological uptake in these regions. PROCEDURES: Two teenage female patients with these patterns on PET scans performed with oral benzodiazepine administration underwent repeat imaging with temperature-controlled environment settings. RESULTS: Resolution of supraclavicular FDG uptake with temperature control in two patients in whom benzodiazepine had no prior effect. CONCLUSION: Although the exact mechanism remains unknown, we propose that the control of temperature reduces the metabolism of glucose by brown fat. Further studies are warranted to confirm the above observations, and, if confirmed, to determine the most efficient and effective use of temperature control to minimize supraclavicular and axillary FDG uptake.

Adipose Tissue, Brown↗