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At least 829 records · Page 46Linked to original sources
PubMed1992

Strong heat stimulation sensitizes the heat response as well as the bradykinin response of visceral polymodal receptors.

1. Hyperalgesia after thermal injury is a common phenomenon, but its mechanism is poorly understood. As a step toward understanding the mechanism for heat sensitization, we searched conditions that would induce sensitization consistently and studied changes in polymodal receptors in their responses to heat (45 and 48 degrees C) and to bradykinin. Experiments were conducted in vitro, with the use of testis-superior spermatic nerve preparations excised from anesthetized dogs. 2. Stimulation at 55 degrees C for 30 s induced clear augmentation of the responses to stimulations at 45 and 48 degrees C when tested within 10 min in 22 out of 24 testicular polymodal units. In the remaining two units, weak or delayed augmenting tendencies were observed. The response to stimulation at 45 degrees C increased from 0.28 +/- 0.08 to 2.99 +/- 0.46 (SE) imp/s, whereas at 48 degrees C it increased from 1.08 +/- 0.16 to 4.60 +/- 0.63 imp/s (P < 0.001, n = 24). A low-level ongoing discharge appeared in about one-half of the units studied. 3. Despite frequent rinsing of the receptive field, augmentation of the heat response observed after stimulation at 55 degrees C continued for up to approximately 3 h. 4. The response to bradykinin (94 nM) was also potentiated: the net mean discharge rate (NMDR) during a 1-min application period of bradykinin as well as the total number of impulses induced by one bradykinin application significantly increased from 0.91 +/- 0.27 to 1.97 +/- 0.32 imp/s and from 213.9 +/- 42.3 to 433.5 +/- 58.7 impulses, respectively (P < 0.001, n = 15).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Expression of the 60 kDa and 71 kDa heat shock proteins and presence of antibodies against the 71 kDa heat shock protein in pediatric patients with immune thrombocytopenic purpura.

BACKGROUND: Immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by platelet destruction resulting from autoantibodies against platelet proteins, particularly platelet glycoprotein IIb/IIIa. Heat shock proteins (Hsp) have been shown to be major antigenic determinants in some autoimmune diseases. Antibodies to Hsps have also been reported to be associated with a number of pathological states. METHODS: Using western blot, we measured the levels of the 60 kDa heat shock protein (Hsp60) and of the inducible 71 kDa member of the Hsp70 family (Hsp71) in lymphocytes and the presence of antibodies against these hsps in plasma of 29 pediatric patients with ITP before the treatment and in 6 other patients before and after treatment. RESULTS: Interestingly only one out of 29 patients showed detectable Hsp60 in lymphocytes while this heat shock protein was detected in the 30 control children. Hsp71 levels were slightly lower in lymphocytes of patients with ITP than in controls (1567.8 ± 753.2 via 1763.2 ± 641.8 integrated optical density (IOD) units). There was a small increase of Hsp71 after recovery from ITP. The titers of plasma antibodies against Hsp60 and Hsp71 were also examined. Antibodies against Hsp71 were more common in ITP patients (15/29) than in control children (5/30). The titer of anti-Hsp71 was also higher in children patients with ITP. The prevalence of ITP children with antibodies against Hsp71 (51.7%) was as high as those with antibodies against platelet membrane glycoproteins (58.3%). CONCLUSIONS: In summary, pediatric patients with ITP showed no detectable expression of Hsp60 in lymphocytes and a high prevalence of antibody against Hsp71 in plasma. These changes add to our understanding of the pathogenesis of ITP and may be important for the diagnosis, prognosis and treatment of ITP.

Journal Article↗
PubMed2006

Augmentation of heat transfer on the downward surface of a heated plate by ion injection.

The heat transfer characteristics of an electrohydrodynamically induced submerged impinging liquid flow are studied in a point-plane configuration. The working fluid, HFE-7100, is a weakly polar dielectric. Thermofluid-dynamic conditions as close as possible to the microgravity ones are obtained by heating a confined, downward-facing plate. Heat transfer coefficients on the plate can be stably enhanced by over 10 times, with negligible additional work, by means of the ion injection technique.

Journal Article↗
PubMed1976

Flight energetics in sphinx moths: heat production and heat loss in Hyles lineata during free flight.

1. Mean thoracic temperature of free-flying H. lineata in the field and in the laboratory increased from about 40 degrees C at Ta=16 degrees C to 42-5 degrees C at Ta=32 degrees C. At a given Ta, thoracic temperature was independent of body weight and weakly correlated with wing loading. 2. The difference between abdominal temperature and air temperature increased from 2 degrees C at low Ta to 4-2 degrees C at high Ta. At a given Ta, the difference between Tab and Ta was positively correlated with thoracic temperature. 3. Oxygen consumption per unit weight did not appear to vary with Ta from 15 to 30 degrees C and was inversely proportional to body weight. 4. Thermal conductance of the abdomen (Cab) was greater than thermal conductance of the thorax (Cth) in still air and at wind velocities up to 2-5 m/s. In moving air at speeds approximating flight, Cth was twice as high as in still air. Under the same conditions Cab was 3-4 times as high as in still air. 5. Thoracic and abdominal conductance are inversely proportional to their respective weights. 6. These data are consistent with the hypothesis that thoracic temperature is controlled by regulation of heat loss. However, a heat budget derived from these data suggests that heat dissipation may not be sufficient to offset the decrease in passive cooling of the thorax at high ambient temperatures.

Abdomen↗
PubMed2003

Dynamic responses to acute heat stress between 34 degrees C and 38.5 degrees C, and characteristics of heat stress response in mice.

We focused on dynamic responses to acute heat stress between 34 degrees C and 38.5 degrees C. Physiological and neuroendocrinological changes between 34 degrees C and 38.5 degrees C were studied in mice. The influence of humid conditions, 85% relative humidity (RH), on these changes was also investigated. Rectal temperatures increased above 34 degrees C and hematocrit levels increased at 38.5 degrees C 85% RH for 60 min. Food consumption and body weight gains decreased after a daily 60 min exposure to 34, 37 and 38.5 degrees C for 2 weeks. The corticosterone and vasopressin levels in the blood, and catecholamine and serotonin metabolite levels in the hypothalamus were not changed at 34 degrees C, but increased when above 37 degrees C for 60 min. Above 37 degrees C, these physiological and neuroendocrinological changes were accelerated by humid conditions. These results indicated that food consumption and body weight gains decreased above 34 degrees C, and the neuroendocrinological changes, which were accelerated by humid conditions, were induced above 37 degrees C. In comparison with restraint and water immersion stress, heat stress at 37 degrees C 85% RH showed a slower increase in serum corticosterone levels, smaller changes in plasma dopamine and dihydroxyphenylacetic acid levels, and, after repeated exposure, larger decreases in food consumption and body weight gains. This study clarified the relationships between temperature and humidity conditions and physiological and neuroendocrinological changes, along with the characteristics of responses in acute heat stress.

Animals↗
PubMed2004

Effect of the rate of temperature increase on water quality during heating in electromagnetic- and gas-heated pans.

More rapid increases in the pH value and hardness during electromagnetic heating of a pan of water were observed than when the pan was heated by LNG or LPG. The water quality changed universally in several tap water samples across Japan. This quality change was closely correlated with the rate of temperature increase, irrespective of heating by electromagnetic induction, LNG or LPG.

Electromagnetic Phenomena↗
PubMed1999

Effect of heat acclimation and heat shock on oscillations of carbamyl-choline-evoked Ca2+ signal in HSY cell line.

We studied effects of heat acclimation (HA) and acute heat stress (HS) on Ca2+ signal oscillations following supramaximal carbamyl-choline (CCh) stimulation, using HSY cell line as a model. In the control cells, oscillations decreased their amplitude with time. HS alone did not change either oscillation amplitude or frequency, although calcium release to the cytosol upon CCh stimulation was faster. HA increased maximal oscillation amplitude only. There was no change in basal cytosolic calcium level and peak evoked signal in all experimental conditions. Collectively, the data suggest that HA affects the oscillation profile. Changes in the oscillation profile did not correlate with changes in the resting and evoked Ca2+ signal, which suggests that the oscillations are a separate target for heat acclimation.

Acclimatization↗
PubMed2001

Modeling the combined effect of pH and temperature on the heat resistance of Bacillus stearothermophilus spores heated in a multicomponent food extract.

The combined effect of pH and temperature on the heat resistance of Bacillus stearothermophilus spores heated in an extract of complex food was studied. The results showed that, in general, reducing the pH reduced the heat resistance of the spores. Similarly, the value for the D parameter in the nonacidified extract was between 30 and 70% lower than the one obtained with double-distilled water. This result once again shows the importance of the substrate in inactivation studies of microorganisms. The experimental data were used to carry out a comparison of two predictive mathematical models of inactivation, one based on a multiparametric regression obtained in this study and the other obtained from the bibliography and based on a linear-Bigelow equation. Both models predict reasonably well, although the multiparametric model presented a slightly better accuracy factor (1.11) than the one obtained with the linear-Bigelow equation (1.13).

Geobacillus stearothermophilus↗
PubMed1999

[The evaluation of skin temperature points and heat flow in the area of the foot for the measurement of the footwear heat insulation].

Analyzing results of the personal experiments, the authors present methodology to minimize number of sites for measurement of foot skin temperature and heat flow. Average foot temperature could be reliably measured through one or several sites. The studies revealed informativeness of each among 11 measurement sites and helped to specify corresponding equations for evaluation of foot heat conditions and heat insulation.

Adult↗
PubMed1976

[Relationship between the heat resistance of different muscles and frog viability during heat selection].

An attempt was made to elucidate the relation between the survival of mature frogs Rana temporaria during sudden (unforeseen) thermal selection and the heat resistance of several muscles: m. interfalangealis, m. ileofibularis, m. sartorius, m. gastrocnemius and m. rectus abdominis. It has been found that of greater selective value are the individuals with lower heat resistance not in all muscles, but in those having lesser heat resistance, such as m. ileofibularis and m. sartorius.

Adaptation, Physiological↗
PubMed2001

Effect of superficial heat, deep heat, and active exercise warm-up on the extensibility of the plantar flexors.

BACKGROUND AND PURPOSE: Warm-up prior to static stretching enhances muscle extensibility. The relative effectiveness of different modes of warm-up, however, is unknown. The purpose of this study was to evaluate the effectiveness of superficial heat, deep heat, and active exercise warm-up prior to stretching compared with stretching alone on the extensibility of the plantar-flexor muscles. SUBJECTS: Ninety-seven subjects (59 women, 38 men) with limited dorsiflexion range of motion (ROM) were randomly assigned to 1 of 5 groups. Female subjects had a mean age of 27.6 years (SD=7.68, range=17-50), and male subjects had a mean age of 26.8 years (SD=6.87, range=18-48). METHODS: The first group (group 1) was a control group and did not perform the stretching protocol. The 4 experimental groups (groups 2-5) performed a stretching protocol 3 days per week for 6 weeks. Group 2 performed the static stretching protocol only; group 3 performed active heel raises before stretching; group 4 received 15 minutes of superficial, moist heat to the plantar-flexor muscles before stretching; and group 5 received continuous ultrasound for 7 minutes before stretching. Dorsiflexion ROM measurements were taken initially and after 2, 4, and 6 weeks. RESULTS: All experimental groups increased active and passive range of motion (AROM and PROM). The mean AROM/PROM differences at 6 weeks were 1.11/1.39 degrees for group 1, 4.10/6.11 degrees for group 2, 4.16/4.21 degrees for group 3, 4.38/4.90 degrees for group 4, and 6.20/7.35 degrees for group 5. The group receiving ultrasound before performing the stretching protocol (group 5) displayed the greatest increase in both AROM (6.20() and PROM (7.35(). DISCUSSION AND CONCLUSION: Among the modalities tested, the use of ultrasound for 7 minutes prior to stretching may be the most effective for increasing ankle dorsiflexion ROM.

Adolescent↗
PubMed2002

Heat shock factor 1 and heat shock proteins: Critical partners in protection against acute cell injury.

OBJECTIVE: Life-threatening conditions cause severe changes in the organization and conformation of macromolecules, creating urgent requirements for protein repair to ensure survival. As molecular chaperones, heat shock proteins (HSP) that have specialized functions in protein folding are now well established to restore homeostasis in cells and organisms. Augmentation of HSP synthesis is tightly regulated by stress-inducible heat shock factors (HSF), which are part of a transcriptional signaling cascade with both positive (e.g., HSP) and negative (e.g., proinflammatory cytokines) properties. In this review, we discuss the biological roles and mechanisms of HSP-mediated protection in pathophysiologic conditions (ischemia, sepsis, and preeclampsia) and the regulation for stress-dependent HSP synthesis and speculate about future applications for harnessing HSF and HSP partners as cytoprotective agents. DATA SOURCES: Reactive oxygen species are major pathogenic factors in cell death pathways (e.g., necrosis, apoptosis), in part, because of proteotoxic effects. In intact organisms, forced overexpression of HSP per se affords effective counterbalance against ischemia challenges (e.g., heart and brain) and systemic conditions (e.g., sepsis). Besides stressful conditions, gene-targeting studies have uncovered new functions for heat shock transcription factors (e.g., maintenance of intrauterine pregnancy) in mammals. In parallel, pharmacologic studies using small molecules are paving the way for future prospects to exploit the beneficial properties of HSP, albeit an important but presently elusive goal. CONCLUSIONS: Together, HSF and HSP partners are attractive targets in therapeutic strategies designed to stimulate endogenous protective mechanisms against deleterious consequences of oxidative stress. With further technological advances, it is anticipated that the spotlight on HSP, alone or in combination with other stress response pathways, could, ultimately, reduce injury and accelerate functional recovery of susceptible organs in living organisms including humans.

Journal Article↗
PubMed1991

[Experimental study of the heat and cold constitutional types (II). A comparative observation on the heat and cold constitutional type rats on the DNA replication capacity after ultraviolet damage].

The cold-constitutional and the heat-constitutional type had selected in Wistar rats as the object of study. Using peripheral blood and spleen as materials by means of ultraviolet injury, isotope incorporation, cells incubation in vitro and liquid scintillation counting, the capacity of peripheral lymphocytes DNA replication after damage with ultraviolet radiation and the capacity of the spleen lymphocytes proliferation in vitro was observed. The results showed that the both capacities mentioned above were higher in the heat constitutional type rat than that in the cold type. It is suggested that the following conclusion in the Lingshu Jing is correct: "the capacity of tissue repair is higher in the heat constitutional type than in the cold."

Animals↗
PubMed1990

Heat stress in dairy cattle under southern African conditions. II. Identification of areas of potential heat stress during summer by means of observed true and predicted temperature-humidity index values.

November-March are the hottest months of the year with the highest monthly mean "temperature-humidity index" (THI) in South Africa and Namibia. These 5 months are associated with severe heat stress in dairy cattle, are of critical importance for their performance and may have great economic implications for the owner as well as for the dairy industry. Firstly, compared with the existing Livestock Weather Safety index (LWSI), more relevant meteorological data can be generated when mapping South Africa and Namibia according to the LWSI modified for lactating dairy cattle (LDC). Secondly, compared with the observed true THI values alone, more relevant data on heat stress and its deleterious effects on dairy cattle performance, become available when mapping South Africa and Namibia according to the combined observed true and predicted THI values. Minimum precautions against heat stress in dairy cattle are recommended depending on THI values as classified by the LWSI for LDC.

Animals↗
PubMed1988

[Reactive changes in the heat-resistant muscle tissue of lake frogs during heat acclimation].

A study was made of the effect of heat acclimation of animals on the individual changes in the muscle heat resistance in populations of Rana ridibunda belonging to European or Asiatic groups of the species. The relationship between the levels of heat resistance of muscle cells and the value of its changes are the same in the populations of these groups. It is believed that this relationship forms on the level higher than populational one.

Acclimatization↗
PubMed1988

HIV-antibody seroconversions in Dutch haemophiliacs using heat-treated and non heat-treated coagulation factor concentrates.

A national multicentre study was performed to investigate the effects of donorselection and the use of heat-treated plasma products on seroconversion to HIV in 157 Dutch haemophiliacs. All patients included in the study were seronegative for HIV antibodies in 1983. Thirteen percent (20/157) seroconverted between 1983 and 1986. Nineteen of 20 seroconversions could be related to the use of non heat-treated products in the year preceding HIV antibody seroconversion. One seroconversion occurred in a person using heat-treated non donor screened product. Seroconversion rate decreased as a result of the policy to discourage high risk blood donors and no seroconversions were observed following the introduction of donor screening in 1985.

Blood Coagulation Factors↗
PubMed1987

[Distribution of heat production in the tissues of the lower extremities during capacitative heating by a UHF field].

The authors described methods developed by them for measuring heat production in autopsy sections by taking pulse thermograms during local capacitative healing of tissues using special electrode devices filled in with liquid dielectric. Thermograms of heat production distribution on limb sections were shown. Qualitative peculiarities of heat production distribution determined by tissue topological structure, were analysed.

Diathermy↗
PubMed1985

Regional heat loss in newborn infants. Part I. Heat loss in healthy newborns at various environmental temperatures.

In 17 newborn infants (gestational age 33-40 weeks, birthweight 1 100-5 560 g) heat flux (HF) from the forehead, chest and calf was measured by HF transducers and heat loss (HL) from those body regions was calculated, taking into account variations in surface area. Both HF and HL were related to operative environmental temperature (Top). Average HF from the forehead, chest and calf was 63.3, 51.5 and 45.7 W/m2 respectively at a Top of 31.2 degrees C and increased by 100%, 66% and 50% as the Top fell to 27.5 degrees C. HL from the head, trunk and limbs contributed about one-third each to total dry HL. These data, in the form of regression equations, permit assessment of heat loss from the various body regions of individual neonates in any thermal environment.

Body Temperature Regulation↗