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At least 1,063 records · Page 59Linked to original sources
PubMed1999

High-temperature effects on antibody response to viral antigen in mice.

To determine the effects of high-temperature exposure on antibody response to viral antigen in mice, male BALB/c mice were placed for 13 days in animal chambers at 23 degrees C, 32 degrees C, and 35.5 degrees C. Rectal temperature rose from 37 degrees C to 39 degrees C on day 1 in a 35.5 degrees C environment. The rectal temperature was kept constant throughout the exposure period. The IgG-antibody to Sendai virus (SV) antigen was inhibited to about 50% of the control value (23 degrees C). The serum corticosterone concentration indicating thermal stress increased steadily, peaking on day 1 and then gradually decreased and recovered to the normal level on day 13. Body weight decreased to about 72% of the controls on day 13. Thymus and spleen weight decreased to 31.7% and 61.5% respectively. At 32 degrees C, these effects were less than at 35.5 degrees C. Effects of high-temperature exposure at 35.5 degrees C appeared to noticeably decrease thymus and spleen weight. It is clear that IgG-antibody response to SV antigen is suppressed by high-temperature exposure.

Animals↗
PubMed1988

Environmental temperature control in very low birth weight infants (less than 1000 grams) cared for in double-walled incubators.

To evaluate the effect of fluctuations in environment and body temperatures on preterm infants, we recorded these variables in very immature newborn infants (birth weight less than 1000 gm) cared for in double-walled incubators (Air-Shields model C-100 and Ohio model IC). Both incubators maintained environmental temperatures corresponding overall to the set point, despite incubator openings. Under skin temperature servocontrol, however, environmental temperature fluctuations were greater than 2 degrees C even in strictly controlled conditions. The pattern of incubator temperature fluctuations depended on the set point rather than on the type of incubator (conventionally heated or heated by warm air blown between the double walls). The long-term clinical significance of the incubator temperature variability remains to be determined; the choice between air and skin servocontrolling should depend in part on the need for environmental stability.

Body Temperature↗
PubMed1994

Adaptation to extreme environments: structure-function relationships in Emperor penguin haemoglobin.

The functional properties of the single haemoglobin (Hb) of Emperor penguin (Aptenodytes forsteri) have been investigated at different temperatures as a function of proton and organic phosphate concentration. The complete amino acid sequence has been established. Comparison with that of human HbA shows 12 substitutions in the contact regions of alpha beta dimers. In addition to overall similarities shared with most of the avian Hbs previously described, this Hb shows significant differences, which could be related to the peculiar behaviour of this penguin. In particular we may consider that: (1) the shape of the Bohr effect curve seems well adapted for gas exchange during very prolonged dives, preserving penguin Hb from a sudden and not controlled stripping of oxygen; (2) the very minor enthalpy change observed at lower pH could be an example of molecular adaptation, through which oxygen delivery becomes essentially insensitive to exposure to the extremely low temperatures of the environment. Moreover, the small alkaline Bohr effect has been found to be only chloride-linked, since the pH dependence of the oxygen affinity is totally abolished in the absence of this ion. These functional characteristics are discussed on the basis of the primary structure of alpha and beta-chains.

Amino Acid Sequence↗
PubMed1988

Local skin hyperthermia due to transcutaneous electrode heat.

The hypothesis that a transcutaneous monitor electrode can heat skin beyond the electrode edge was tested. This heating would cause a skin thermistor probe, if placed too close to the transcutaneous electrode, to transduce an artifactually high skin temperature. In a skin servo control system, this might result in a cooler environment than desired. Eight premature newborns in humidified incubators were tested once each between one and five days of age. Mean skin temperatures at 0.5 cm, 1.5 cm, and 2.5 cm from the electrode edge were significantly higher after electrode placement, although there were virtually no temperature changes in two of the subjects. Transcutaneous monitor electrodes can heat the surrounding skin. This may affect environment temperature in a skin servo control system if the skin probe is placed too close to the transcutaneous electrode.

Blood Gas Monitoring, Transcutaneous↗
PubMed1982

Pigmentation and Soluble Peroxidase Isozyme Patterns of Leaves of Pedilanthus tithymaloides L. variegatus as a Result of Daily Temperature Differences.

In a constant environment with a narrow (less than 8 degrees C) daily temperature difference (deltat), leaves of Pedilanthus tithymaloides L. variegatus usually appeared green. After at least two days of deltat > 10 degrees C, new leaves had become green-white, and a red pigmentation appeared and increased if high deltat conditions were maintained. If plants were returned to a narrow deltat, new green leaves reappeared. Electrophoretic patterns of soluble peroxidase isozymes changed during the color changes. Three groups of electrophoretic bands occurred, and each was related to a characteristic tissue. The development of red color was correlated with the appearance of the group with the fastest electrophoretic mobility and the highest peroxidase activity.

Journal Article↗
PubMed2000

Physicochemical surface properties of five Listeria monocytogenes strains from a pork-processing environment in relation to serotypes, genotypes and growth temperature.

Physicochemical surface properties, related to electrostatic, van der Waals and Lewis acid-base interactions, of five Listeria monocytogenes strains isolated from pork-processing environments were determined after two subcultures at 37 degrees C and a final culture at three temperatures: 37, 10 and 4 degrees C. Three strains (Lm1, Lm114 and Lm191) were genetically related while two were unrelated (Lm25 and Lm74) according to ApaI-macrorestriction and pulsed-field gel electrophoresis (PFGE) typing. Listeria monocytogenes cell surfaces were generally negatively charged regardless of pH and tended to be hydrophilic due to a basic character. However, variable physicochemical surface properties of the five Listeria monocytogenes isolates were observed after growth at 37 degrees C. After growth at 10 degrees C, the three genetically related isolates exhibited similar surface properties and were slightly more hydrophilic and basic than the others. After growth at 4 degrees C, the five isolates displayed the same weak affinity for all kinds of solvents and low electrophoretic mobility values. A sharp decrease of temperature and subsequent growth of various Listeria monocytogenes strains resulted in loss of the physicochemical surface property variability, which may suggest the role of common chill adaptation mechanisms affecting surface properties.

Abattoirs↗
PubMed1990

Stress-induced rise of body temperature in rats is the same in warm and cool environments.

Several forms of psychological stress result in a rise in body temperature in rats. In this study, we report that rats housed at a low ambient temperature (11.1 degrees C) develop stress-induced rises in body temperature that do not differ from the responses seen when the animals are kept at a temperature within their thermoneutral zone (24.7 degrees C). These data support the hypothesis that stress-induced "hyperthermia" is a regulated rise in temperature (i.e., a rise in thermoregulatory "set-point," or fever), and is not simply the result of metabolic changes associated with the stress response itself.

Animals↗
PubMed2005

Ambient temperature related sleep changes in rats neonatally treated with capsaicin.

Ambient temperature related sleep changes in rats neonatally treated with capsaicin. PHYSIOL BEHAV 00(0) 000-000, 2004. The study was conducted on adult male Wistar rats, neonatally treated with capsaicin to destroy the peripheral warm receptors. The sleep-wakefulness was recorded for 5 h at an ambient temperature (T(amb)) of 18, 24, 30 and 33 degrees C on different days. The rectal temperatures (T(r)) of the rats were studied on exposure to 6 and 37 degrees C for 2 h to assess their thermoregulatory ability. The changes in the behavioral thermoregulation were assessed by noting the thermal preference of rats when they were placed in an environmental chamber with 3 interconnected compartments maintained at 24, 27 and 30 degrees C. Slow wave (SWS) and rapid eye movement (REM) sleep were decreased at 18 degrees C and increased at 30 degrees C, in control rats. There was a decrease in REM sleep and no change in SWS when T(amb) was raised from 30 to 33 degrees C. However, in neonatally capsaicin treated rats, sleep was increased even at 33 degrees C, though there was no significant change in sleep when T(amb) was increased from 18 to 24 degrees C. Capsaicin treated rats showed thermoregulatory deficiency at 37 degrees C but the thermal preference was unaltered in these rats. The results suggest that the central warm receptors can produce alteration in sleep at different T(amb), even in absence of peripheral warm receptors. The behavioral thermoregulation was unaffected in these rats, though their ability to defend the body temperature in warm environment was affected.

Animals↗
PubMed2004

Survival of mouse blastocysts after low-temperature preservation under high pressure.

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21 degrees C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0 degrees C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

Animals↗
PubMed2001

Exciton formation in semiconductors and the influence of a photonic environment.

A fully microscopic theory is presented for interacting electrons, holes, photons, and phonons in semiconductor heterostructures. The formation dynamics and statistics of incoherent excitons are analyzed for different densities, lattice temperatures, and photonic environments. Luminescence experiments are shown to depend strongly on the photonic environment in contrast to suggested terahertz absorption measurements. Whereas luminescence in free space is dominated by plasma contributions, terahertz absorption should be able to directly measure excitonic populations.

Journal Article↗
PubMed2002

Quantum and classical correlations in quantum Brownian motion.

We investigate the entanglement properties of the joint state of a distinguished quantum system and its environment in the quantum Brownian motion model. This model is a frequent starting point for investigations of environment-induced superselection. Using recent methods from quantum information theory, we show that there exists a large class of initial states for which no entanglement will be created at all times between the system of salient interest and the environment. If the distinguished system has been initially prepared in a pure Gaussian state, then entanglement is created immediately, regardless of the temperature of the environment and the nonvanishing coupling.

Journal Article↗
PubMed2005

Survival or growth of Escherichia coli O157:H7 in a model system of fresh meat decontamination runoff waste fluids and its resistance to subsequent lactic acid stress.

A potential may exist for survival of and resistance development by Escherichia coli O157:H7 in environmental niches of meat plants applying carcass decontamination interventions. This study evaluated (i) survival or growth of acid-adapted and nonadapted E. coli O157:H7 strain ATCC 43895 in acetic acid (pH 3.6 +/- 0.1) or in water (pH 7.2 +/- 0.2) fresh beef decontamination runoff fluids (washings) stored at 4, 10, 15, or 25 degrees C and (ii) resistance of cells recovered from the washings after 2 or 7 days of storage to a subsequent lactic acid (pH 3.5) stress. Corresponding cultures in sterile saline or in heat-sterilized water washings were used as controls. In acetic acid washings, acid-adapted cultures survived better than nonadapted cultures, with survival being greatest at 4 degrees C and lowest at 25 degrees C. The pathogen survived without growth in water washings at 4 and 10 degrees C, while it grew by 0.8 to 2.7 log cycles at 15 and 25 degrees C, and more in the absence of natural flora. E. coli O157:H7 cells habituated without growth in water washings at 4 or 10 degrees C were the most sensitive to pH 3.5, while cells grown in water washings at 15 or 25 degrees C were relatively the most resistant, irrespective of previous acid adaptation. Resistance to pH 3.5 of E. coli O157:H7 cells habituated in acetic acid washings for 7 days increased in the order 15 degrees C > 10 degrees C > 4 degrees C, while at 25 degrees C cells died off. These results indicate that growth inhibition by storage at low temperatures may be more important than competition by natural flora in inducing acid sensitization of E. coli O157:H7 in fresh meat environments. At ambient temperatures in meat plants, E. coli O157:H7 may grow to restore acid resistance, unless acid interventions are applied to inhibit growth and minimize survival of the pathogen. Acid-habituated E. coli O157:H7 at 10 to 15 degrees C may maintain a higher acid resistance than when acid habituated at 4 degrees C. These responses should be evaluated with fresh meat and may be useful for the optimization of decontamination programs and postdecontamination conditions of meat handling.

Acetic Acid↗