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At least 19 recordsLinked to original sources

PubMed1995

Transcription of heat shock gene loci versus non-heat shock loci in Chironomus polytene chromosomes: evidence for heat-induced formation of novel putative ribonucleoprotein particles (hsRNPs) in the major heat shock puffs.

The heat shock response of Chironomus polytene chromosomes was reexamined. The in vivo effects of heat shock on chromosomal [3H]uridine labeling, RNA polymerase II distribution and ribonucleoprotein (RNP) formation were investigated. One primary result is a clarification of the number and location of chromosomal sites strongly induced by treatment at 37 degrees C for 60 min. In total, seven major heat shock loci were identified by transcription autoradiography in Chironomus tentans: I-20A, II-16B, II-10C, II-4B, II-1C, III-12B, and IV-5C. Secondly, combining immunofluorescence with transcription autoradiography, I find RNA polymerase II occurring after heat shock at multiple chromosomal sites that were also active under normal conditions (20 degrees C). Furthermore, the results demonstrate conclusively that the presence of RNA polymerase II at heat shock and non-heat shock loci is generally correlated with [3H]uridine labeling during heat shock. These latter results extend and corroborate previous findings. Thirdly, the most striking result of this study was revealed in ultrathin sections of puffs by electron microscopy: I discerned a site-specific ultrastructural difference in putative RNP particles between heat shock versus non-heat shock loci. At least three of the seven induced major heat shock puffs (I-20A, III-12B, IV-5C) were observed to contain globular particles that were different, i.e. significantly larger, 250-1,000 A in diameter with a prominent 500-750 A class, than RNP particles of other loci under non-heat shock conditions. These large heat shock puff particles presumably represent nascent or newly synthesized heat shock RNA associated with protein(s) to form heat shock RNPs (hsRNPs). This finding suggests the possible involvement of novel RNPs (hsRNPs) in transcriptional regulation or heat shock RNA turnover and may stimulate further molecular investigations on this subject in both cell physiological and structural terms. I conclude that the locus-specific putative hsRNPs are an intrinsic property of greatly increased heat shock gene transcription.

Animals↗

PubMed2003

Heat shock factor 1-independent activation of dendritic cells by heat shock: implication for the uncoupling of heat-mediated immunoregulation from the heat shock response.

The induction of heat shock proteins by heat shock is classically defined as the heat shock response, which is involved in cytoprotection, inflammation and immune responses. Whereas the cytoprotective properties of heat shock have been well characterized, the immunomodulating roles of the heat shock response on the immune system are just emerging. In particular, it is not known whether immunomodulating functions of heat are mediated by the heat shock response. We addressed this question genetically, using a murine model that is unable to mount the heat shock response because of deletion of a major transcriptional factor, heat shock factor 1 (Hsf1). We focused on the roles of heat shock on modulating the functions of dendritic cells (DC) because of their important roles in both innate and adaptive immunity. We found that heat shock matures CD11c(+) DC both in vitro and in vivo, phenotypically and functionally, in the absence of any exogenous inflammatory stimuli. Furthermore, heat-shock-mediated DC maturation is independent of Hsf1, as Hsf1(-/-) DC can be matured by heat shock equally well as wild-type DC. Our novel findings demonstrate that heat shock, one of the most primitive biological responses, can modulate the immune response without the requirement for the transcriptional induction/repression of target genes mediated by Hsf1.

Animals↗

PubMedDate not supplied

Influence of heat transmission mode on heating rates and on the selection of patches for heating in a mediterranean lizard.

Heliothermy (heat gain by radiation) has been given a prominent role in basking lizards. However, thigmothermy (heat gain by conduction) could be relevant for heating in small lizards. To ascertain the importance of the different heat transmission modes to the thermoregulatory processes, we conducted an experimental study where we analyzed the role of heat transmission modes on heating rates and on the selection of sites for heating in the Mediterranean lizard Acanthodactylus erythrurus (Lacertidae). The study was conducted under laboratory conditions, where two situations of different operative temperatures (38 degrees and 50 degrees C) were simulated in a terrarium. In a first experiment, individuals were allowed to heat up during 2 min at both temperatures and under both heat transmission modes. In a second experiment, individuals were allowed to select between patches differing in the main transmission mode, at both temperatures, to heat up. Experiences were conducted with live, nontethered lizards with a starting body temperature of 27 degrees C. Temperature had a significant effect on the heating rate, with heat gain per unit of time being faster at the higher operative temperature (50 degrees C). The effect of the mode of heat transmission on the heating rate was also significant: at 50 degrees C, heating rate was greater when the main heat transmission mode was conduction from the substrate (thigmothermy) than when heating was mainly due to heat gain by radiation (heliothermy); at 38 degrees C, heating rates did not significantly differ between transmission modes. At 38 degrees C, selection of the site for heating was not significantly different from that expected by chance. However, at 50 degrees C, the heating site offering the slowest heating rate (heliothermic patch) was selected. These results show that heating rates vary not only with environmental temperature but also with different predominant heat transmission modes. Lizards are able to identify and exploit this heterogeneity, selecting the source of heat gain (radiation) that minimizes the risk of overheating when temperature is high.

Animals↗

PubMed1990

Use of polymerase chain reaction to detect the expression of the Mr 70,000 heat shock genes in control or heat shock leukemic cells as correlated to their heat response.

The expression of the Mr 70,000 heat shock protein (HSP-70) in heat-resistant variants or heat-shocked cells has been correlated with development of thermal resistance. In these studies polymerase chain reaction (PCR) was used to detect low levels of HSP-70 mRNA present in control, unheated cells to investigate the possibility of predicting the intrinsic heat response in various leukemic cells. The expression of two human heat shock genes in control or heat-shocked cells was investigated. Synthetic primers and probes from the untranslated region of the two HSP-70 genes sequenced by Hunt and Morimoto (HSP-70A)(C. Hunt and R. I. Morimoto, Proc. Natl. Acad. Sci. USA, 82: 6455-6459, 1985) and Voellmy et al. (HSP-70B)(R. Voellmy et al., Proc. Natl. Acad. Sci. USA, 82: 4949-4953, 1985) were used in PCR reactions to follow expression in control or heat-shocked leukemic K562, KG-1, and HL-60 cells. The PCR results were correlated with heat response and patterns of protein synthesis in these cells. Results indicate that, among leukemic cells, K562 was much more resistant to killing by heat shock than either KG-1 or HL-60 cells. All control cells, however, expressed the HSP-70B gene. Of the three leukemic cells tested, K562 was the most heat resistant and constitutively expressed the HSP-70A mRNA and the heat-inducible HSP-70 protein. KG-1 and HL-60 cells did not express this gene in unheated cells. All heat-shocked cells expressed the HSP-70A mRNA and the heat-inducible HSP-70 protein. However, there was no significant increase in the mRNA level of the HSP-70B in heat-shocked leukemic cells as measured by PCR or the S1-nuclease protection assay. Other cells including normal human bone marrow and normal and tumorous tissues of the colon and breast all expressed both genes in control cells. Normal breast tissue expressed less mRNA for HSP-70B gene than the tumor tissue obtained from the same patient. In all studies the amplified beta-actin mRNA expression was used as an internal standard. These studies indicate that HSP-70B gene is expressed in all control leukemic cells. The expression of this gene did not seem to correlate with intrinsic heat resistance. The HSP-70A expression correlated with intrinsic and transient heat resistance. These studies also indicate that both HSP-70 genes in humans may be expressed in a variety of unheated normal and tumorous tissues more so than previously reported.

Base Sequence↗

PubMed1991

Attenuation of the heat shock response in HeLa cells is mediated by the release of bound heat shock transcription factor and is modulated by changes in growth and in heat shock temperatures.

When HeLa S3 cells are subjected to a continuous 42 degrees C heat shock, activation of heat shock transcription factor (HSF) and transcriptional activation of the heat shock genes hsp70, hsp89 alpha, and hsp60 is transient, peaking at 40-60 min of heat shock, and then attenuating. We have used in vivo genomic footprinting to demonstrate that attenuation of hsp70 transcription is mediated by release of bound HSF from the heat shock element (HSE) of the hsp70 gene promoter. Release of bound HSF in vivo occurs at a higher rate than would be predicted from in vitro measurements of dissociation. Attenuation of HSF activation and heat shock gene transcription occurs only when mild heat shock temperatures are employed (42 degrees C); increasing the heat shock temperature by 1 degree C elicits a much higher level of activation, which does not attenuate during a 4-hr heat shock. Surprisingly, altering the temperature at which cells are grown prior to heat shock modulates the magnitude and temporal pattern of the response to a given heat shock temperature. This finding suggests that HSF does not sense temperature directly but, instead, may be responsive to the magnitude of the difference between growth and heat shock temperatures.

Base Sequence↗

PubMed2003

Heat sensitivity in a bentgrass variant. Failure to accumulate a chloroplast heat shock protein isoform implicated in heat tolerance.

Two variants of creeping bentgrass (Agrostis stolonifera cv palustris), developed using tissue culture, have been used to determine the roles of chloroplast-localized small heat shock proteins (CP-sHSPs) in heat tolerance. Results from previous research indicate that the heat-tolerant variant expressed two additional CP-sHSP isoforms not expressed in the heat-sensitive variant, that accumulation of the additional CP-sHSP isoforms was genetically linked to thermotolerance, and that the presence of the additional isoforms in the heat-tolerant variant provided greater protection to photosystem II during heat stress. To determine the basis of the differential expression, we isolated the genes encoding the CP-sHSPs from both variants and characterized their structure and expression. Two genes, ApHsp26.2 and ApHsp26.7a, were isolated from the heat-tolerant variant, and three genes, ApHsp26.2m, ApHsp26.8, and ApHsp26.7b, were isolated from the heat-sensitive variant. The sequence of ApHsp26.2m from the heat-sensitive variant was identical to ApHsp26.2, except for a point mutation that generated a premature stop codon. Therefore, the protein product of ApHsp26.2m did not accumulate in the heat-sensitive line. Mass spectrometry analysis confirmed that ApHsp26.2 encoded for the CP-sHSP isoforms unique to the heat-tolerant variant. An identical mutation was detected in one of the three parental lines used to develop the creeping bentgrass variants. This suggests that ApHsp26.2m was inherited from this parent and did not arise from a mutation that occurred during tissue culture. The presence of two isoforms encoded by the same gene might be due to differential processing of the N-terminal amino acids during or after import into the chloroplast.

Adaptation, Physiological↗

PubMed1967

Some properties of heat-resistant and heat-sensitive strains of Clostridium perfringens. I. Heat resistance and toxigenicity.

Heat resistance at 100 C (D-values), sporulating ratios, toxigenicity for mice, and lecithinase activity (as micrograms per milliliter of enzyme, ascertained by the lecithovitellin reaction) were determined for four strains of Clostridium perfringens. A definite inverse relationship between thermal resistance and toxigenicity was found. The D-values ranged from 17.6 for the most heat-resistant strain to 0.3 for the strain possessing the least heat resistance, with corresponding lecithinase activities from 25 to 133 mug/ml of enzyme. The sporulating ratios did not differ greatly between the strains. The heat stability of the toxin was greater at 100 C than at 75 C. There was a noticeable difference between the heat stabilities of the toxin in the culture fluids of the heat-sensitive and heat-resistant strains at pH 7.0 when the toxic filtrates were held at 100 C. At a holding temperature of 75 C, a similar but lesser difference was observed at pH 5.5. Heat resistance and lecithinase activity did not change when a substrain of the least heat-resistant parent strain was obtained through heat selection by a single transfer, or when the most heat-resistant strain was transferred serially 12 times.

Animals↗

PubMed1985

Heat-resistant mutants of B-16 melanoma cells. I. Stepwise heating in vitro induces progressive increase in resistance to heat.

Cloned lines from 4 different families of B-16 melanoma cells were heated repeatedly in tissue culture at 45 degrees C with step-up time intervals. These lines included the partially heat-resistant lines previously selected at 43 degrees C(HR 43 degrees) from wheat-germ-agglutinin-resistant mutant (WGAR, HR43 degrees), concanavalin-resistant mutant (conR-HR 43 degrees), ricin-resistant mutant (ricinR, HR 43 degrees), and parental B-16 (B-16, HR 43 degrees) cells. The heating cycles were repeated 7 to 11 times at 45 degrees C increasing from 45 min to 150 min with 3 weeks of culturing at 37 degrees C between cycles. Heat resistance in most cases increased progressively with each heating step. An extensive library of mutants was thus generated, varying in the degree of heat resistance and the apparent stability. HR variants from the WGAR family appeared to be the most resistant and the most stable. The heat-resistant phenotype was expressed not only by increased survival after a normally lethal heat dose, but also by protection against heat-mediated suppression of proteins and DNA syntheses. Protein synthesis in the heat-resistant cells was not only less suppressed by heat shock, but also recovered more rapidly after removal of shock. Clinical implications of these results and the potential usefulness of the mutant lines for genetic studies are discussed.

Adaptation, Physiological↗

PubMed1992

The 70-kilodalton heat-shock proteins of the SSA subfamily negatively modulate heat-shock-induced accumulation of trehalose and promote recovery from heat stress in the yeast, Saccharomyces cerevisiae.

In the yeast, Saccharomyces cerevisiae, the disaccharide trehalose is a stress-related metabolite that accumulates upon exposure of cells to heat shock or a variety of non-heat inducers of the stress response. Here, we describe the influence of mutations in individual heat-shock-protein genes on trehalose metabolism. A strain mutated in three proteins of the SSA subfamily of 70-kDa heat-shock proteins (hsp70) overproduced trehalose during heat shock at 37 degrees C or 40 degrees C and showed abnormally slow degradation of trehalose upon temperature decrease from 40 degrees C to 27 degrees C. The mutant cells were unimpaired in the induction of thermotolerance; however, the decay of thermotolerance during recovery at 27 degrees C was abnormally slow. Since both a high content of trehalose and induced thermotolerance are associated with the heat-stressed state of cells, the abnormally slow decline of trehalose levels and thermotolerance in the mutant cells indicated a defect in recovery from the heat-stressed state. A similar albeit minor defect, as judged from measurements of trehalose degradation during recovery, was detected in a delta hsp104 mutant, but not in a strain deleted in the polyubiquitin gene, UB14. In all our experiments, trehalose levels were closely correlated with thermotolerance, suggesting a thermoprotective function of trehalose. In contrast, heat-shock proteins, in particular hsp70, appear to be involved in recovery from the heat-stressed state rather than in the acquisition of thermotolerance. Cells partially depleted of hsp70 displayed an abnormally low activity of neutral trehalase when shifted to 27 degrees C after heat shock at 40 degrees C. Trehalase activity is known to be under positive control by cAMP-dependent protein kinases, suggesting that hsp70 directly or indirectly stimulate these protein-kinase activities. Alternatively, hsp70 may physically interact with neutral trehalase, thereby protecting the enzyme from thermal denaturation.

Glucose↗

PubMed1997

Induction of heat shock protein 72 synthesis by endogenous tumor necrosis factor via enhancement of the heat shock element-binding activity of heat shock factor 1.

Endogenous tumor necrosis factor (enTNF) acts as a resistance factor against cytotoxicity caused by heat by inducing manganous superoxide dismutase (MnSOD), thereby scavenging reactive oxygen free radicals. On the other hand, it is also well known that heat shock proteins (HSP) which are induced by heat stress behave as cytoprotective factor against this stress. However, the relationship of these two resistance factors is not elucidated yet. In the present study, we therefore proposed the possibility that enTNF enhances HSP72 expression. Heat-sensitive L-M (mouse tumorigenic fibroblast) cells, which normally do not express enTNF, were transfected with a nonsecretory-type human TNF-alpha expression vector to produce enTNF. Stable transfectants showed resistance to heat treatment and an increase of HSP72 expression. Conversely, when HeLa (human uterine cervical cancer) cells, which normally produce an appreciable amount of enTNF, were transfected with an antisense TNF-alpha mRNA expression vector to inhibit enTNF synthesis, their heat sensitivity was enhanced and HSP72 expression was reduced by half. Although enTNF caused no difference in the level of heat shock factor (HSF) 1 in these cells, enTNF expression correlated well with the binding activity of HSF-1 to a 32P-labeled synthetic oligonucleotide containing the human heat shock element (HSE). These results indicate that enTNF participates not only in intrinsic resistance against heat via induction of MnSOD but also via enhancement of the HSE-binding activity of HSF 1 followed by augmentation of HSP72 expression.

Animals↗

PubMed1986

Heat-induced vasoconstriction in the fingers: a mechanism for reducing heat gain through the hand heated locally.

This study examined the effect of local heating on the blood flow of the finger or forearm in male subjects in an environment of 35 degrees C--40% (r.h.). One hand or forearm was immersed in a water bath the temperature of which (Tw) was raised by 1 degrees C every 10th min from 35 degrees to 43 degrees C, while the other hand or forearm was kept at a constant Tw of 35 degrees C. Blood-flow (BF) was measured by venous occlusion plethysmography, using temperature-compensated mercury-in-Silastic strain gauges. Finger BF in the heated hand was significantly lower than that in the control hand at TwS of 37 degrees -41 degrees C, mostly for the first few minutes of each heating period. Thereafter, finger BF in the heated hand gradually returned toward the previous values. At TwS of 39 degrees -40 degrees C, however, finger BF in the heated hand remained lower than the control values for the entire period of heating. At TwS of 42 degrees -43 degrees C, finger BF in the heated hand greatly increased after an initial transitory fall. In the forearm skin, however, no such vasoconstriction in response to local heating was observed. All this suggests that a rise in skin temperature to above the core temperature produces paradoxical vasoconstriction in the finger, which may be a mechanism to reduce heat gain through the hand heated locally at higher temperatures.

Adult↗

PubMed1986

Heat production of cattle acclimated to cold, thermoneutrality and heat when exposed to thermoneutrality and heat stress.

Four Hereford X Red Angus yearling steers were acclimated to each of the following environments; cold (3 C), thermoneutrality (TNZ; 20 C) and heat (35 C). Intake was equalized for all treatments at 4.9 X kg X head-1 X d-1 (2.9 Mcal metabolizable energy/kg). Heat production, respiration rate and rectal temperature were determined after 3- and (21-h later) 24-h exposures to thermoneutral and heat stress test-temperatures: 25, 30, 32.5, 35, 37.5 and 40 C. Thermoneutral heat production (kcal X kg-.75 X d-1), after 3- and 24-h exposures, was greater (P less than .05) for the cold-acclimated cattle (139.6 +/- 5.0 and 153.0 +/- 5.8) as compared with the TNZ-acclimated cattle (117.7 +/- 5.0 and 121.6 +/- 5.8). Heat production of the heat-acclimated cattle after 3- and 24-h exposures to thermoneutrality was 121.0 +/- 5.1 and 123.5 +/- 3.2 and was not different from the TNZ-acclimated cattle. Heat production of steers acclimated to different temperatures was variable during the 3- and 24-h exposures to test-temperatures ranging from 25 to 40 C. Heat production increased linearly in the TNZ-acclimated cattle (24-h exposure) and in the heat-acclimated cattle (3-h exposure) at the rate of 1.3 and 2.3 kcal X kg-75 X d-1 X C-1 increase in test-temperature, respectively. In the other four comparisons, analysis by regression indicated no significant change in heat production. Rectal temperature and respiration rate increased significantly in either a linear or quadratic manner in all treatment groups exposed to test-temperatures from 25 to 40 C.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗

PubMed1993

Homoharringtonine induces heat protection and facilitates dissociation of heat shock transcription factor and heat shock element complex.

We investigated the effects of combined treatment with homoharringtonine (HHT) and hyperthermia on cytotoxicity and transcriptional regulation of heat shock genes in human colon carcinoma (HT-29) cells. The drug (100 ng/ml) which inhibited protein synthesis by 93% protected cells from killing at 43 degrees C. For example, treatment with HHT 2 hr before and during heating produced a 9-fold increase in survival from 3.7 x 10(-2) to 3.2 x 10(-1) after 10 hr at 43 degrees C. Little or no protection was observed if the drug was added only during heating. Interestingly, adding the drug (100 ng/ml) 2 hr before and during heat facilitated the dissociation of heat shock transcription factor-heat shock element (HSF-HSE) complex during continuous heating at 43 degrees C. These findings related to the literature suggest that the free pool of HSC70 is increased by inhibiting protein synthesis. An increase in the level of free HSC70 may more effectively protect or repair thermolabile targets and consequently affect regulation of heat shock response.

Antineoplastic Agents, Phytogenic↗

PubMed1995

Heat shock protein hsp70 accelerates the recovery of heat-shocked mammalian cells through its modulation of heat shock transcription factor HSF1.

The role of mammalian 70-kDa heat shock protein (hsp70) in regulating cellular response to heat shock was examined by using three closely related rat cells: control Rat-1 cells, thermotolerant Rat-1 (TT Rat-1) cells, and heat-resistant M21 cells, a derivative of Rat-1 cells that constitutively overexpress human hsp70. In all these cells, after a prescribed heat shock, the level of the phosphorylated form of heat shock transcription factor HSF1 and that of HSF1 capable of binding to its cognitive DNA sequence heat shock element (HSE) exhibit similar time dependence. The amount of a constitutive HSE-binding activity (CHBA), on the other hand, inversely correlates with those of the two aforementioned forms of HSF1. The recovery kinetics from heat shock are different for the three cell lines, with the thermal-resistant TT Rat-1 and M21 cells showing faster recovery in terms of the state of phosphorylation of HSF1 and its ability to bind HSE or in terms of the reappearance of CHBA. Treatment with okadaic acid, a serine/threonine phosphatase inhibitor, delays the recovery kinetics of Rat-1 cells but not that of thermal-resistant M21 cells. These results are interpreted in terms of a role for hsp70 in the recovery of heat-shocked mammalian cells.

Animals↗

PubMed1985

Chromatin structure of the 87A7 heat-shock locus during heat induction and recovery from heat shock.

We have examined the chromatin organization of the 87A7 heat-shock locus (which contains two hsp 70 genes transcribed in opposite orientation) as a function of the time of heat induction and during the course of recovery from heat shock. Our studies show that both induction and recovery from heat shock are accompanied by highly specific alterations in the nucleoprotein structure of this locus. Moreover, these changes parallel the transcriptional activity of the hsp 70 heat-shock genes. We have also examined the effect of inhibitors of transcription and translation. Cycloheximide, an inhibitor of translation, blocks both the attenuation of the heat-shock response (which occurs after a long-term incubation at elevated temperatures) and the re-establishment of the pre-induced chromatin organization of the locus during recovery from heat shock. Actinomycin D, an inhibitor of transcription, prevents some but not all of the alterations in chromatin structure which normally accompany heat induction.

Animals↗

PubMed1999

Constitutive and heat-inducible heat shock element binding activities of heat shock factor in a group of filamentous fungi.

This study represents the initial characterization of the heat shock factor (HSF) in filamentous fungi. We demonstrate that HSFs from Beauveria bassiana, Metarhizium anisopliae, Tolypocladium nivea, Paecilomyces farinosus, and Verticillium lecanii bind to the heat shock element (HSE) constitutively (non-shocked), and that heat shock resulted in increased quantities and decreased mobility of HSF-HSE complexes. The monomeric molecular mass of both heat-induced and constitutive HSFs was determined to be 85.8 kDa by UV-crosslinking and the apparent molecular masses of the native HSF-HSE complexes as determined by pore exclusion gradient gel electrophoresis was 260 and 300 kDa, respectively. Proteolytic band clipping assays using trypsin and chymotrypsin revealed an identical partial cleavage profile for constitutive and heat-induced HSF-HSE complexes. Thus, it appears that both constitutive and heat-inducible complexes are formed by trimers composed of the same HSF molecule which undergoes conformational changes during heat shock. The mobility difference between the complexes was not abolished by enzymatic dephosphorylation and deglycosylation, indicating that the reduced mobility of the heat-induced HSF is probably due to a post-translational modification other than phosphorylation or glycosylation.

Electrophoresis, Gel, Two-Dimensional↗

PubMedDate not supplied

Effects on the expression of heat shock proteins by step-down heating and hypothermia in rat hepatoma cells with a different degree of heat sensitivity.

Thermosensitization induced by pretreatment at supra- and subnormal temperatures, rate of protein synthesis and expression of the major heat shock proteins under such conditions was investigated in relation to intrinsic heat sensitivity of rat hepatoma cells, i.e. Reuber H35 and HTC. The high degree of heat susceptibility of H35 cells was reflected by a high degree of thermosensitization after pretreatment by heat (step-down heating) at temperatures of 42-44 degrees C for 30 min or cold for 16 h at temperatures ranging from 0 to 25 degrees C. Sensitization under step-down heating conditions was found to be paralleled by a delayed recovery of protein synthesis. Despite an increased relative rate, enhancement of the absolute rate of synthesis of the major heat shock proteins, HSP28, HSP60, HSP68, HSP70, HSP84 and HSP100, was less pronounced during step-down exposure. Comparable results were obtained during recovery of sensitized H35 cells at 37 degrees C after exposure to heat following pretreatment at 0 degrees C. Furthermore, clear differences in the regulation of the specific HSP synthesis, depending on the particular treatment protocol, were observed.

Animals↗

PubMed1995

The effete in the heat: heat-related hospital presentations during a ten day heat wave.

BACKGROUND: Severe heat-related illness can result in hospitalisation and possibly death. These illnesses are potentially preventable; in Australia high environmental temperatures are common. AIMS: To identify (i) possible risk factors for hospital attendance with heat-related illness during a heat wave, (ii) problems with diagnosis and therapy, (iii) issues in prevention, and (iv) areas for further study. METHODS: A retrospective descriptive survey from four major teaching hospitals in Adelaide, South Australia (SA), was conducted during a ten day period of exceptional heat in February 1993, in order to review all emergency department presentations (i.e. deaths, casualty treatment or hospital admissions) with a heat-related illness as determined by attending doctors' documentation. Demographic, clinical, management and outcome data were collected. RESULTS: Ninety-four patients were classified as having a heat-related illness of whom 78% had heat exhaustion. Eighty-five per cent were age 60 years or over; 20% came from institutional care; 48% lived alone; 30% had poor mobility. Peak presentation followed high daily temperatures for four consecutive days. Severity was related to pre-existing cognitive impairment, diuretic use and presenting temperature, heart rate, blood pressure, plasma sodium and plasma creatinine. Treatment tended to be non-standardised. Mortality was 12%. Seventeen per cent required a more dependent level of residential care upon discharge. CONCLUSION: Problems were identified in accuracy of diagnosis and appropriate intervention. Awareness of the risk factor profile is needed among health workers, to ensure early preventative strategies. Populations to target for future prevention include elderly people (including those in institutional care), patients with cognitive impairment and patients taking diuretics, multiple medication and/or with other severe co-existing illnesses. Treatment could be more standardised.

Adult↗