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At least 325 records · Page 18Linked to original sources
PubMed1981

Temperature dependence of ethanol depression in mice.

The relationship between environmental temperature, body temperature and ethanol depression was investigated in male C57BL/6J mice. Animals were injected with ethanol (3.6 g/kg) or saline and placed in an experimental or normal room temperature (control) environment. Environmental temperatures from 12-37 degrees C significantly influenced rectal temperature, sleep-time and wake-up brain ethanol concentrations. The rectal temperatures of ethanol-treated animals ranged from 1.5 degrees C greater to 11.3 degrees C lower than their matched saline controls, supporting indications that ethanol impairs normal thermoregulation. Sleep-time decreased up to 43% and wake-up brain ethanol concentrations increased as rectal temperature decreased from approximately 38-32 degrees C. More severe hypothermia after ethanol (rectal temperature less than 29 degrees C) increased sleep-time and decreased wake-up brain ethanol concentrations. These results indicate that sleep-time and brain sensitivity to ethanol vary with rectal temperature in accordance with predictions based on membrane expansion and partition theories of anesthesia and the anticipated anesthetic-like actions of severe hypothermia.

Animals↗
PubMed1981

Biomineralization on crinoid echinoderms. Characterization of crinoid skeletal elements using TEM and STEM microanalysis.

Columnals of Neocrinus blakei, a modern species of stalked crinoid, were studied using a variety of analytical techniques. Analyses of the magnesium calcite of the crinoid stereom using powder X-ray diffraction and electron microprobe analysis yield a composition of Ca 88Mg 12C03. Scanning transmission electron microscopy (STEM) microanalytical data indicate that Mg incorporation into the calcite structure of the crinoid stereom is random and homogeneous to at least the 20 nm level. There appear to be no variations in composition at this level either within or between structural entities of the crinoid columnal stereom. TEM reveals a heterogeneity of contrast which may be due to incorporation of organic material or some other substance which is non-crystalline in character. Single-crystal X-ray diffraction data indicate that the individual skeletal plates are single crystals which yield diffuse and imperfect X-ray reflections due to a mosaic structure. Subsequent selected area electron diffraction (SAD) photographs via TEM, using various sizes of SAD apertures, indicate that the crystallites making up the mosaic structure are (order of magnitude) about 1.0 micrometer in size. The presence of mosaic structure in the single crystal skeletal elements may at least in part explain the lack of cleavage in fracture surfaces of echinoderm skeletal material. Based on these data, as well as data from skeletal elements of other deep water, stalked crinoids, we feel that these results may be applicable to crinoids in general, at least those existing in relatively constant temperature environments. The single-crystal nature of crinoid high magnesium calcite, and its remarkable homogeneity of composition suggest that a large "vital effect" (i. e., biologic control of skeletal deposition) mediates the mineralization process.

Animals↗
PubMed1999

Fifteen cases of atropine poisoning after honey ingestion.

Fifteen persons developed atropine poisoning following consumption of wasp honey. Clinical signs, antidotal response and the presence of Datura plants near the wasp nests supported that the intoxications were caused by ingestion of atropine-contaminated honey. Two deaths occurred from heatstroke because of the poisoning and high environment temperatures and intensive physical activity.

Adolescent↗
PubMed2003

Engineering Deinococcus geothermalis for bioremediation of high-temperature radioactive waste environments.

Deinococcus geothermalis is an extremely radiation-resistant thermophilic bacterium closely related to the mesophile Deinococcus radiodurans, which is being engineered for in situ bioremediation of radioactive wastes. We report that D. geothermalis is transformable with plasmids designed for D. radiodurans and have generated a Hg(II)-resistant D. geothermalis strain capable of reducing Hg(II) at elevated temperatures and in the presence of 50 Gy/h. Additionally, D. geothermalis is capable of reducing Fe(III)-nitrilotriacetic acid, U(VI), and Cr(VI). These characteristics support the prospective development of this thermophilic radiophile for bioremediation of radioactive mixed waste environments with temperatures as high as 55 degrees C.

Biodegradation, Environmental↗
PubMed1990

Effect of hydrophobic coating on the behavior of a hygroscopic aerosol powder in an environment of controlled temperature and relative humidity.

Powders of uncoated disodium fluorescein (DF) and DF coated with various amounts of lauric or capric acids were generated as aerosols in an environment of controlled temperature and relative humidity. The particle size and distribution of these powders were characterized using a cascade impactor and a computerized data inversion method of analysis. Disodium fluorescein exhibited a hygroscopic growth ratio of 1.5 at a relative humidity of 97%. This growth was reduced to 1.3 by coating with 0.15 g of lauric acid or 0.8 g of capric acid per gram of DF, and was eliminated with 0.2 g of lauric acid or 0.18 g of capric acid per gram of DF. The reduction in hygroscopic growth probably reflects an inhibition of the growth rate. In the time following generation and prior to deposition in the collection device, approximately 40 s, the coated aerosol powders do not seem to reach their equilibrium droplet diameter. These studies indicate that these combinations of DF and fatty acid would result in larger equilibrium droplet diameters than that of the dye alone.

Aerosols↗
PubMed1998

California ground squirrel body temperature regulation patterns measured in the laboratory and in the natural environment.

Body temperature (Tb) was measured by telemetry in both laboratory maintained and natural environment California ground squirrels, Spermophilus beecheyi. Laboratory animals had a mean diurnal Tb of 37.5 degrees C under conditions of LD 14:10, 20 degrees C and 36.5 degrees C under conditions of LD 10:14, 20 degrees C (P < 0.01). Nocturnal mean Tbs were 37.1 and 35.2 degrees C, respectively (P < 0.05). Mean diurnal Tbs for each animal in the natural environment ranged from 39.3 to 40.1 degrees C (mean = 39.6 degrees C) during both study seasons which included the hot season months of March through August and the cool season months of December through February. Natural environment hot season mean Tb was not significantly different from cool season mean Tb but both mean Tbs were significantly different from the diurnal mean Tbs measured in the laboratory (P < 0.05). California ground squirrels exhibit an open-field stress induced hyperthermia in the laboratory which can be extended for periods up to 6 h. The hyperthermic response is blocked by L-propranolol at a dosage of 15 mg kg-1. Laboratory animals do not habituate to repeated open-field exposures over a five consecutive day period. It is suggested that stress hyperthermia might be a normal component of thermoregulation in some free-living ground squirrels because of the openness of the habitat in which they exist.

Animals↗
PubMed1987

Prediction of mean skin temperature in warm environments.

The data collected by the authors in four experimental series have been analysed together with data from the literature, to study the relationship between mean skin temperature and climatic parameters, subject metabolic rate and clothing insulation. The subjects involved in the various studies were young male subjects, unacclimatized to heat. The range of conditions examined involved mean skin temperatures between 33 degrees C and 38 degrees C, air temperatures (Ta) between 23 degrees C and 50 degrees C, ambient water vapour pressures (Pa) between 1 and 4.8 kPa, air velocities (Va) between 0.2 and 0.9 m.s-1, metabolic rates (M) between 50 and 270 W.m-2, and Clo values between 0.1 and 0.6. In 95% of the data, mean radiant temperature was within +/- 3 degrees C of air temperature. Based on 190 data averaged over individual values, the following equation was derived by a multiple linear regression technique: Tsk = 30.0 + 0.138 Ta + 0.254 Pa-0.57 Va + 1.28.10(-3) M-0.553 Clo. This equation was used to predict mean skin temperature from 629 individual data. The difference between observed and predicted values was within +/- 0.6 degrees C in 70% of the cases and within +/- 1 degrees C in 90% of the cases. It is concluded that the proposed formula may be used to predict mean skin temperature with satisfactory accuracy in nude to lightly clad subjects exposed to warm ambient conditions with no significant radiant heat load.

Adult↗
PubMed1994

Effects of restraint and cabin environment on skin temperature, sleep-wake, feeding and drinking circadian rhythms in Macaca mulatta during spacelab flight simulation.

Exposure to a weightless environment such as in spaceflight, leads to a number of physiological responses to assure the survival of an organism in this new environment. However, the real effect of microgravity itself has not been clearly established yet. Considering the environmental and operational characteristics of a spaceflight, and as it has been shown in previous flights, the use of animals, and more particularly the non-human primates, takes on importance in understanding the mechanisms and factors involved in the adaptation to changes in gravitational loading. The SLS-3 flight of the American shuttle, scheduled for launch in early 1996, will be the first flight of the Rhesus project, a joint program of C.N.E.S. and N.A.S.A. which will carry out experiments in various physiological disciplines using the Rhesus monkey as a human surrogate. This 16 day orbital flight will be the longest flight accomplished by the shuttle to date. A number of feasibility studies have already been conducted on Macaca mulatta in order to simulate flight conditions to obtain ground data and to test the technical characteristics of the Rhesus Research Facility which have been described elsewhere. Microgravity might be the main factor inducing the physiological changes observed during spaceflights. However, these responses could also be influenced by other factors related to the spaceflight environment such as the life support systems of the spacecraft. Thus, the main purpose of the present study was to determine the impact of specific restraint and cabin environment on the circadian rhythms of body temperature, feeding, drinking, and sleep-waking in order to separate them from the real impact of microgravity.

Activity Cycles↗
PubMed1984

[Influence of hot environment on body temperature, heart rate and blood pressure of pregnant rats].

Twenty-six out of fifty pregnant rats died on days 18-20 of gestation at 33 degrees C environment. The death generally occurred in the dark period around 1-5 a.m. Shortly prior to the death, very high body temperature of 42.0-43.7 degrees C were recorded and the blood pressure was undetectably low. In autopsy, the finding in the main was the congestion in lungs and liver. In temporal changes of body temperature and heart rate, influences of hot environment were observed, but there was no significant difference between dead pregnant group and delivered pregnant group at 33 degrees C environment. At 23 degrees C, the blood pressure of pregnant rats starting at about 140 mmHg level, reached 160-168 mmHg on day 12 of gestation and maintained the level to day 16. On day 18, the pressure returned to 140-145 mmHg and unchanged to term. At 33 degrees C, significant differences were obviously observed between dead group and delivered group in temporal changes of blood pressure. The blood pressure of rats delivered sharply increased to 170 mmHg or more in the middle stage of pregnancy and decreased to about 140 mmHg in the final stage. However, these of dead group increased to 160 mmHg or less in the middle stage of pregnancy, and maintained the level until the final stage.

Animals↗