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PubMed1987

Temperature-induced protein conformational changes in barley root plasma membrane-enriched microsomes: I. Effect of temperature on membrane protein and lipid mobility.

A protein spin label and lipid spin probes were used to study the temperature-dependent motion of protein and lipid, respectively, in barley (Hordeum vulgare L. cv Conquest) root plasma membrane-enriched microsomes. Using membranes from seedlings grown at 20 degrees C, the temperature-dependence of the relative motion of membrane surface spin probes and a spin label covalently attached to membrane proteins suggested abrupt changes in the lipid and protein mobilities at about 12 degrees C. Spin probe spin-spin exchange broadening and fluorescent probe eximer formation indicated apparent temperature-induced alterations in probe lateral diffusion within the membrane at about 12 to 14 degrees C. The results suggest the presence of temperature-induced quasicrystalline lipid clusters which may influence the activity of membrane-bound enzymes.

Journal Article↗

PubMed1989

Temperature-Induced Protein Conformational Changes in Barley Root Plasma Membrane-Enriched Microsomes: III. Effect of Temperature and Cations on Protein Sulfhydryl Reactivity.

Temperature and cations modified the reaction of barley (Hordeum vulgare L. cv Conguest) root plasma membrane protein sulfhydryl groups with N-4-(7-diethylamino-4-methylcoumarin-3-yl)-phenyl maleimide (CPM). The pseudo-first-order rate constants for the formation of fluorescent CPM-protein adducts increased as the temperature was raised above 30 degrees C, suggesting changes in protein conformation. Monovalent [K(I), Na(I), L(I)] and certain divalent cations [Ba(II), Mg(II)] increased the reaction rates. Other divalent cations [Ca(II), Mn(II), Ni(II), Co(II), Sr(II), Cd(II), Hg(II)] decreased the rate of fluorescent adduct formation. Na(I) promoted and Ca(II) delayed the onset of the temperature-dependent increases in reaction rates. The results are discussed in terms of lipid-mediated, temperature-dependent changes in membrane protein conformation and ion-protein interactions.

Journal Article↗

PubMed2005

Powder neutron diffraction of Tl2BeF4 at six temperatures from room temperature to 1.5 K.

The structure of thallium fluoroberyllate, Tl2BeF4, has been analysed by the Rietveld method on neutron diffraction patterns collected at 1.5, 50, 100, 150, 200 and 300 K, with the aim of detecting low-temperature instabilities. Atomic parameters based on the isomorphic beta-K2SO4 crystal in the paraelectric phase were used as the starting model at room temperature; no evidence for any phase transition has been detected at lower temperature. The structure was determined in the orthorhombic space group Pnma. All the atoms (except one F atom) occupy sites with m symmetry. We have compared the structure with those of other compounds of the beta-K2SO4 family, at room temperature, in order to gain insight into their observed instabilities. The irregular coordination of the cations may indicate stereochemical activity of the TlI lone pair but does not indicate a possible structural instability.

Journal Article↗

PubMed1980

Influence of seasonal temperature on the temperature optima of bacteria in sediments of lake george, new york.

Temperature optima for the heterotrophic utilization of glucose and an amino acid mixture were determined throughout the year in sediments from Lake George, N.Y. The temperature optimum decreased with decreasing in situ temperature in the fall and winter, suggesting that selection for or adaptation by a psychrotrophic bacterial population occurred. Replicate plating of bacterial isolates from 3 and 20 degrees C indicated that a psychrotrophic bacterial population was present in the sediments throughout the year. These results indicate that decomposition and nutrient cycling processes in the sediments within the littoral zone of Lake George were probably not completely inhibited by winter temperatures, although process rates were decreased.

Journal Article↗

PubMed1994

Temperature gradient osmometer and anomalies in freezing temperatures.

We have developed a new device that measures freezing and melting temperatures in nanoliter volume samples and can be used as a "freezing point osmometer" with a resolution many orders of magnitude greater than that of existing freezing point osmometers. Using this device we found anomalies in the depression of the freezing temperature and thermal hysteresis in aqueous solutions of hydrophilic amino acids, polyamino acids, and lectins. These anomalies would not have been possible to detect with currently used technology. The compounds that produce anomalies in freezing temperature were reported in the literature as having the ability to bind to cell membranes. This suggests a relation between a molecule's ability to bind to cell membranes and its anomalous freezing temperature depression. The new freezing point osmometer and our results could be important for studying and understanding organic molecules and their interaction with membranes and water.

Amino Acids↗

PubMed1984

Suction blister device with regulation of temperature: demonstration of histamine release and temperature change in cold urticaria.

A suction blister device with a sensitive thermometer and with a temperature regulator was constructed. Utilizing this device, it was demonstrated that the cold challenge induces an increase in the skin temperature in cold urticaria patients during the cold challenge and a simultaneous release of histamine into the suction blisters. The skin temperature increases faster after the cold challenge period in cold urticaria patients than in normal control persons. This could be explained by vasodilatation and increased circulation in the skin, following the release of histamine in the cold urticaria reaction.

Cold Temperature↗

PubMed1990

The effects of elevated temperature and humidity on rectal temperature and respiration rate in the New Zealand white rabbit.

In 2 replicated factorial experiments, 7-h climate chamber exposures were used to study the responses of adult NZW rabbits to a range of elevated temperatures and humidities. At 18 mm Hg water vapour pressure, 23.8 degrees C was well tolerated, rectal temperature (RT) and respiration rate (RR) averaging 38.6 +/- 0.3 degrees C and 82.9 +/- 15.5 breaths/min, respectively. Both parameters were elevated (P less than 0.001) at 32.2 degrees, 37.8 degrees and 43.3 degrees C. RT and RR reached plateau levels of 39.5-40.1 degrees C and 410-460/min at 32.2 degrees C, which was tolerated for the full 7-h test period. Test temperatures of 37.8 degrees and 43.3 degrees C, on the other hand, could be tolerated for only 80 and 40 min respectively, before RT reached the safe upper limit of 41.7 degrees C. Final RR values at 37.8 degrees and 43.3 degrees C were 701.6 +/- 42.7 and 812 +/- 55.1/min, respectively. In a 34.5 degrees C atmosphere a humidity of 21 mm Hg water vapour pressure was classified as "dry", and was tolerated for 323 +/- 123 min. RT and RR increased by 0.6 degrees C and 316/min during the first 20 min of exposure (P less than 0.05). Thereafter both parameters increased progressively, but with no significant differences between successive recording periods, until RR reached 550.3 +/- 88.8/min at 41.7 degrees C RT. Humidities of 25, 29 and 33 mm Hg water vapour pressure were, on the other hand, classified as "wet" and were tolerated for only 92 +/- 22, 81 +/- 16 and 119 +/- 50 min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2006

Exhaled air temperature as a function of ambient temperature in flying and resting ducks.

Exhaled air temperature (T (exh)) has a paramount effect on respiratory water loss during flight. For migratory birds, low T (exh) potentially reduces water loss and increases flight range. However, only three studies provide empirical data on T (exh) during flight. The aim of this study was to record T (exh) of birds during rest and flight at a range of controlled ambient temperatures (T (amb)). One wigeon and two teal flew a total of 20 times in a wind tunnel at T (amb) ranging from 1 degrees to 24 degrees C. T (exh) during flight did not differ between the two species and was strongly correlated with T (amb) (T (exh)=1.036 T (amb) + 13.426; R2=0.58). In addition, body temperature had a weak positive effect on T (exh). At a given T (amb), T (exh )was about 5 degrees C. higher during flight than at rest.

Animal Migration↗

PubMed1989

Automatic temperature controller for maintaining body temperature in experimental animals.

A system for autoregulation of body temperature of large and small animals is described. The device uses the IC AD590 as a temperature transducer. It operates on the basis of continuous regulation of the heating current, and does not emit transients which interfere with electrical recordings. A panel meter shows either the rectal temperature of the animal or the current flow to the blanket.

Body Temperature Regulation↗

PubMed1991

Effect of temperature history on the growth of Listeria monocytogenes Scott A at refrigeration temperatures.

The effect of pre-inoculation temperature on the subsequent growth of Listeria monocytogenes Scott A at 5 degrees C was examined in microbiological medium, UHT milk, canned dog food, and raw ground beef (untreated and irradiation-sterilized). In microbiological medium, the duration of the lag phase was decreased when aerobic and anaerobic cultures were initially grown at less than or equal to 28 and less than or equal to 13 degrees C, respectively. Subsequent exponential growth rates and maximum population densities of the 5 degrees C cultures were not affected by temperature history. Differences in lag phase durations were also observed when L. monocytogenes initially cultured at 19 and 37 degrees C were grown at 5 degrees C in UHT milk and some of the canned dog food varieties. Growth of L. monocytogenes was not observed in either untreated or irradiation-sterilized raw ground beef. While temperature history can affect the growth kinetics of L. monocytogenes at 5 degrees C, it did not account for the lack of growth in raw meat, suggesting that there is an inhibitory condition or component in ground beef that is lost upon cooking.

Aerobiosis↗

PubMed2006

Hot water epilepsy occurring at temperature below the core temperature.

A 6-year-old girl had water reflex epilepsy occurring at lower temperature than the core temperature. Seizures episodes consisted of a loss of consciousness absence followed by left predominant hypotonia with right fronto-temporal high voltage slow waves on the ictal-EEG. Seizures were only observed when the water was poured on scalp or face. Neuropsychological evaluation showed frontal dysfunction (Rey's figure). MRI study was normal. Oxcarbazepine permitted the disappearance of seizures and an improvement of executive disorders. In this case, the pathophysiological mechanism cannot be a hyperthermic related event. The temperature control as treatment of hot-water epilepsy could be used after the exploration of its implication in seizure induction.

Anticonvulsants↗

PubMed2005

Impact of water temperature and stressor controllability on swim stress-induced changes in body temperature, serum corticosterone, and immobility in rats.

The present study compared the effects of three different water temperatures (20, 25, and 30 degrees C) and stressor controllability on several physiological and behavioral endpoints in an intermittent swim stress paradigm. The escape latency of rats in the 20 and 25 degrees C water was less than that observed for the 30 degrees C group. Both escape and yoked groups at 20 and 25 degrees C exhibited moderate to severe hypothermia following the swim stress session that returned to prestress levels 30-40 min post-stress. At 30 degrees C core body temperature (Tb) only decreased by 1 degree C for either swim group. Following swim, serum corticosterone (CORT) levels were significantly elevated in both escape and yoked groups in comparison to confined and home cage controls. The confined control group showed a significant elevation that was approximately halfway between the home cage control and the swim stress groups. At 30 degrees C, there was still a significant elevation of serum CORT in both swim groups in comparison to confined and home cage controls. Therefore, 30 degrees C appears to be the optimal water temperature to evaluate stress controllability effects in the current paradigm. In a final experiment, swim stressor controllability effects were examined in a 5 min forced swim test (FST) 24 h following the initial stress exposure. Rats exposed to yoked-inescapable swim stress at 30 degrees C exhibited more immobility than their escapable swim stress and confined counterparts, while the escape and confined controls did not differ. These results demonstrate that the behavioral deficits observed in the FST are attributable to the stress of inescapable swim and not swim stress per se.

Animals↗

PubMed1977

Regulatory effect of temperature and antigen upon immunity in ectothermic vertebrates. II. Primary enhancement of anti-hapten antibody response at high and low temperatures.

Enhancement of primary anti-hapten antibody response was more efficient when carp were preimmunized with modified carrier, rather than with its native form, especially when they were challenged with a slightly substituted penicilloyl-BSA conjugate (Pen5 BSA). No significant enhancement was obtained when the fish were challenged with a heavy conjugate (Pen30 BSA). When fish kept at optimal temperature were preinjected with the modified carriers, rising titers of anti-hapten antibodies were obtained even when the fish were transferred to low temperature just before being challenged with Pen5 BSA. It was concluded that modified carriers are more efficient in enhancing the anti-hapten antibody response and light conjugates are needed to make the cell cooperation possible. It was also suggested that when helper memory cell maturation was allowed to develop at optimal conditions, both cell cooperation and antibody synthesis could occur at low temperatures.

Animals↗

PubMed1997

Cyclo (His-Pro) modulation of body temperature at hot ambient temperature in the desert rat (Mastomys natalensis).

Cyclo(His-Pro) (CHP) has been shown to facilitate cold-induced hypothermia in the desert rat Mastomys natalensis. In the present study, we examined the role of endogenous CHP in hyperthermia induced by hot ambient temperature (40 degrees C) in the above rodent species. The results of these studies show that housing rodents at 40 degrees C resulted in a altered distribution of CHP in the brain, with a rise in hypothalamic content accompanied by an increase in rectal temperature. While administration of exogenous CHP decreased hyperthermia, immunoneutralization of endogenous CHP increased hyperthermia. The results of these studies show that changes in endogenous CHP levels may affect body temperature regulation.

Animals↗

PubMed2005

Muscle metabolism, temperature, and function during prolonged, intermittent, high-intensity running in air temperatures of 33 degrees and 17 degrees C.

Nine unacclimatized university sportsmen performed a prolonged, intermittent, high-intensity shuttle running test in hot (HT) (33 degrees C, dry bulb temperature, approximately 28 %, relative humidity) and moderate (MT) (17 degrees C, 63 %) environmental conditions. Subjects performed 60 m of walking, a 15-m sprint, 60 m of cruising ( approximately 85 % V.O (2max)), and 60 m of jogging ( approximately 45 %V.O (2max)) for 14.8 +/- 0.1 min followed by a 3-min rest, repeated until volitional exhaustion. The hot trial was performed first followed, 14 days later, by the moderate trial. During exercise subjects drank water ad libitum. Subjects ran almost twice as far in the moderate as in the hot trial (HT 11216 +/- 1411, MT 21644 +/- 1629, m, p < 0.01), and the decline in average 15-m sprint performance was greater in the heat (HT, 0.17 +/- 0.05, MT, 0.09 +/- 0.03, s, p < 0.05). Average heart rates, blood lactate and glucose, and plasma adrenaline and noradrenaline concentrations were greater in the HT (main effect trial, p < 0.01), as were serum cortisol concentration (main effect trial p < 0.05, n = 5) and muscle temperature (HT exhaustion vs. same time point in MT, 40.2 +/- 0.3 vs. 39.3 +/- 0.2, degrees C, p < 0.01). Peak torque during knee flexion and extension was not different pre-and post-exercise in the HT. Muscle glycogen utilization tended to be greater in the heat (HT 193.2 +/- 19.5, MT 143.8 +/- 23.9, mmol . kg dry wt (-1), p = 0.055, n = 8). In 7 out of the 8 subjects the increase in utilization was between 19 and just over 200 % greater in the HT. Glycogen remaining in the muscle at exhaustion was greater in the hot than moderate trial (HT 207.4 +/- 34.3, MT 126.5 +/- 46.8, mmol . kg dry wt (-1), p < 0.01, n = 8). Rectal temperature (T (rec)) was higher in the HT at exhaustion than at the same point in time in the moderate trial (HT, 39.60 +/- 0.15 vs. MT 38.75 +/- 0.10, degrees C, interaction trial-time, p < 0.01). There was a very strong negative relationship between rate of rise in T (rec) and distance completed in the HT (HT r = - 0.90, p < 0.01, MT r = - 0.76, p < 0.05). Thus, the earlier onset of exhaustion during prolonged intermittent shuttle running in the heat is associated with hyperthermia. However, while muscle glycogen utilization may be elevated by heat stress, low whole muscle glycogen concentrations would not seem to be the cause of this earlier exhaustion.

Adult↗

PubMedDate not supplied

Metabolic response to air temperature and wind in day-old mallards and a standard operative temperature scale.

Most duckling mortality occurs during the week following hatching and is often associated with cold, windy, wet weather and scattering of the brood. We estimated the thermoregulatory demands imposed by cold, windy weather on isolated 1-d-old mallard (Anas platyrhynchos) ducklings resting in cover. We measured O2 consumption and evaporative water loss at air temperatures from 5 degrees to 25 degrees C and wind speeds of 0.1, 0.2, 0.5, and 1.0 m/s. Metabolic heat production increased as wind increased or temperature decreased but was less sensitive to wind than that of either adult passerines or small mammals. Evaporative heat loss ranged from 5% to 17% of heat production. Evaporative heat loss and the ratio of evaporative heat loss to metabolic heat production was significantly lower in rest phase. These data were used to define a standard operative temperature (Tes) scale for night or heavy overcast conditions. An increase of wind speed from 0.1 to 1 m/s decreased Tes by 3 degrees -5 degrees C.

Animals↗

PubMed1997

Influence of carotid denervation on the body-core temperature and metabolic responses to changes in ambient temperature during normoxemia and acute hypoxemia in guinea pigs during postnatal maturation.

Acute hypoxemia produces a decrease in body-core temperature (Tbc) in guinea pigs during postnatal maturation, although the factors mediating the response remain unknown. Experiments were therefore carried out to test the hypothesis that the carotid chemoreceptors and (or) baroreceptors mediate the decrease in Tbc during acute hypoxemia. Twelve guinea pigs, six carotid intact and six carotid denervated, were studied in a metabolic chamber to determine the influence of carotid denervation on the Tbc and metabolic (i.e., oxygen consumption) responses to changes in ambient temperature during normoxemia and during acute hypoxemia at 2, 3, and 4 weeks of age. Carotid denervation accentuated the decrease in Tbc in response to a decrease in ambient temperature during normoxemia at 2 and 3 weeks of age but not at 4 weeks of age without altering the metabolic response. This suggests that carotid denervation disrupted heat conservation mechanisms rather than heat production mechanisms in an age-specific manner. Furthermore, carotid denervation accentuated the decrease in Tbc and oxygen consumption in response to acute hypoxemia at all ages studied. This provides evidence that the carotid chemoreceptors and (or) baroreceptors do not mediate the decrease in Tbc that occurs in response to acute hypoxemia in guinea pigs during postnatal maturation.

Animals↗

PubMed1990

Cocaine and body temperature in the rat: effects of ambient temperature.

The laboratory rat is being developed as a model to determine whether abuse of cocaine constitutes a risk factor in the pathogenesis of stress or exertion-induced heatstroke. Under thermoneutral conditions (Ta 20 degrees C) cocaine (10-40 mg/kg i.p.) caused a dose-dependent fall in core temperature ranging from 0.45 +/- 0.18 to 1.77 +/- 0.26 degrees C. When the ambient temperature (Ta) was increased to 35 degrees C, cocaine (10-40 mg/kg i.p.) led to a dose-dependent hyperthermia (0.3 +/- 0.08 to 1.43 +/- 0.43 degrees C). Repeated injection of cocaine (40 mg/kg at Ta 20 degrees C or 20 mg/kg at Ta 40 degrees C) on days 1, 3, 8, 15, and 23 did not alter the magnitude of the temperature change compared to that following the first injection, i.e., neither tolerance nor potentiation occurred.

Animals↗