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PubMedDate not supplied

Effect of combined heat, ozonation and ultraviolet irradiation (VasoCare) on heat shock protein expression by peripheral blood leukocyte populations.

The re-administration of whole blood subjected to heat, ozonation and ultraviolet irradiation (VasoCare therapy) has been shown to elicit clinical benefits in individuals with vascular disease. Given that these stressors induce heat shock protein (Hsp) expression and that heat shock protein reactivity is implicated in the pathogenesis of vascular disease, this study assessed the effect of VasoCare on intracellular expression of Hsp60 and Hsp70 by treated peripheral blood leukocytes. Contrary to expectations, VasoCare induced a significant reduction (approximately 40%) in the proportion of peripheral blood mononuclear cells expressing intracellular Hsp60 and Hsp70, whereas it had no effect on heat shock protein expression by peripheral blood neutrophils. Cell surface heat shock protein expression was not detectable. The reduced expression of Hsp60 by mononuclear cells was concomitant with an increase in the levels of Hsp60 in treated plasma. Although the mechanism underlying the clinical effectiveness of VasoCare therapy has yet to be established, it may be that re-administration of treated blood or soluble factors derived therefrom modifies in vivo immune responsiveness to heat shock proteins or associated molecules.

Flow Cytometry↗
PubMed1996

Characterization of a new high-temperature-induced 66-kDa heat-shock protein, antigenically related to heat-shock protein 72.

M-14 human melanoma cells, following severe hyperthermic exposures, synthesized a heat-shock protein of 66 kDa (hsp 66), in addition to the major "classic" heat-shock proteins. This hsp 66 was not expressed following mild hyperthermic exposures sufficient to trigger the synthesis of the other heat-shock proteins. The induction of hsp 66 was observed also in Li human glioma cells treated at 45 degrees C for 20 min. By contrast, hsp 66 was not induced in seven other human cell lines (both melanoma and nonmelanoma) when they were subjected to the same hyperthermic treatment. Immunological recognition experiments showed that hsp 66 cross-reacted with the inducible hsp 72, but not with the constitutive hsp 73. The possibility that hsp 66 is a breakdown product of hsp 72 was ruled out by the fact that Poly(A)+ RNA extracted from cells treated at 45 degrees C for 20 min was able to direct the synthesis of hsp 66 (together with hsp 72) in a message-dependent rabbit reticulocyte lysate, as well as in microinjected Xenopus oocytes. By contrast, only the hsp 72 was expressed using Poly(A)+ RNA extracted from cells heated at 42 degrees C for 1 h. Affinity chromatography experiments on ATP-agarose showed that hsp 66 did not bind ATP in vitro. hsp 66 was localized both in the cytoplasm (cytosol, mitochondria, and microsome fraction) and in the nuclei of cells recovered from a severe heat shock: this intracellular distribution closely corresponded to that of hsp 72. The nuclear-associated hsp 66 was found to be tightly bound to nuclear structures and could not be extracted by incubation in ATP-containing buffer.

Animals↗
PubMed1999

Spatial pattern of constitutive and heat shock-induced expression of the small heat shock protein gene family, Hsp30, in Xenopus laevis tailbud embryos.

We employed whole-mount in situ hybridization and immunohistochemistry to study the spatial pattern of hsp30 gene expression in normal and heatshocked embryos during Xenopus laevis development. Our findings revealed that hsp30 mRNA accumulation was present constitutively only in the cement gland of early and midtailbud embryos, while hsp30 protein was detected until at least the early tadpole stage. Heat shock-induced accumulation of hsp30 mRNA and protein was first observed in early and midtailbud embryos with preferential enrichment in the cement gland, somitic region, lens placode, and proctodeum. In contrast, cytoskeletal actin mRNA displayed a more generalized pattern of accumulation which did not change following heat shock. In heat shocked midtailbud embryos the enrichment of hsp30 mRNA in lens placode and somitic region was first detectable after 15 min of a 33 degrees C heatshock. The lowest temperature capable of inducing this pattern was 30 degrees C. Placement of embryos at 22 degrees C following a 1-h 33 degrees C heat shock resulted in decreased hsp30 mRNA in all regions with time, although enhanced hsp30 mRNA accumulation still persisted in the cement gland after 11 h compared to control. In late tailbud embryos the basic midtailbud pattern of hsp30 mRNA accumulation was enhanced with additional localization to the spinal cord as well as enrichment across the embryo surface. These studies demonstrate that hsp30 gene expression can be detected constitutively in the cement gland of tailbud embryos and that heat shock results in a preferential accumulation of hsp30 mRNA and protein in certain tissues.

Animals↗
PubMed1996

Heat stress improves functional recovery and induces synthesis of 27- and 70-kDa heat shock proteins without preserving sarcoplasmic reticulum function in the ischemic rat heart.

Heat stress (HS) and the subsequent expression of heat shock proteins has been shown to enhance post-ischemic functional recovery and reduce infarct size. The purpose of these experiments was to determine if HS pre-treatment preserves sarcoplasmic reticulum (SR) function, a cellular organelle that plays an important role in myocardial contractility. Anesthetized rats were heat stressed for 15 min by raising temperature to 42 degrees C. Twenty-four hours later the hearts were perfused by Langendorff's method and subjected to either 20 or 35 min of global ischemia, with a subset of hearts then being subjected to 10 or 20 min of reperfusion, respectively. SR function was assessed by oxalate-supported Ca2+ uptake rate in cell free preparations in the presence and absence of ruthenium red, a selective SR calcium release channel blocker Ca2+ uptake decreased significantly from 25.6 +/- 3.4 to 13.4 +/- 1.9 and 11.3 +/- 2.3 nmol/min/mg protein (mean +/- S.E.), following 20 and 35 min of ischemia, respectively. A similar trend was observed following reperfusion as well. No significant difference in Ca2+ uptake was observed between HS v control hearts. Similarly, in samples where the Ca2+ release channel was blocked with ruthenium red, decreased Ca2+ uptake rates were noted after both ischemia and reperfusion, with no significant differences seen between HS and non-HS hearts. There was significant improvement it developed pressure. +dP/dt and -dP/dt, with reduced creatine kinase release in HS v non-HS hearts. Western blot analysis demonstrated increased synthesis of 27- and 70-kDa heat shock proteins in HS but not in control animals. It is concluded that HS improves functional recovery and induces expression of 27- and 70-kDa heat shock proteins without preservation of SR function in the globally ischemic rat heart.

Animals↗
PubMed1999

The small heat shock proteins Hsp20 and alphaB-crystallin in cultured cardiac myocytes: differences in cellular localization and solubilization after heat stress.

Hsp20, a recently described new member of the small heat shock protein superfamily, is abundant in heart, skeletal muscle types and smooth muscle. We investigated the intracellular localization of Hsp20 in cultured rat neonatal cardiac myocytes, under normal conditions and after stress. These cellular characteristics of Hsp20 were compared with those of its closest relative, alphaB-crystallin, which is also highly expressed in heart. Like alphaB-crystallin, Hsp20 is normally located in the cytoplasm of the cardiac myocytes. After a heat stress, a subpopulation of Hsp20 migrates into the nucleus, while another part remains in the cytoplasm. In very few cells a faint sarcomeric association of Hsp20 is observed. In contrast, as previously reported, alphaB-crystallin displays a very distinct cross-striated sarcomeric staining after the heat shock, but no nuclear migration. Also at the level of Triton solubility, differences exist between the two related proteins; while alphaB-crystallin, like other small heat shock proteins, becomes insoluble upon heat stress, Hsp20 remains largely soluble. Our results indicate that Hsp20 and alphaB-crystallin, despite their structural similarities, display conspicuous functional differences.

Animals↗
PubMed1999

Role of protein kinase C and 72 kDa heat shock protein in ischemic tolerance following heat stress in the rat heart.

Heat stress (HS) and the subsequent expression of 72 kDa heat shock protein (HSP 72) has been shown to enhance post-ischemic functional recovery and reduce infarct size. Because the synthesis of heat shock proteins involves activation of heat shock transcription factors through phosphorylation, we hypothesized that inhibition of protein kinase C (PKC) would block HS mediated protection and expression of HSP 72 in the heart. Five groups of rats were studied (1) Sham anesthetized, (2) HS group--animals were heat shocked by raising the whole body core temperature to 42 degrees C for 15 min, (3) Vehicle group--HS rats treated with 50% DMSO in saline, (4) PKC inhibitor-treated group--specific PKC antagonist, chelerythrine chloride (5 mg/kg, i.p) given 30 min prior to HS and (5) Vehicle treated control--non-HS rats treated with vehicle prior to ischemia/reperfusion. Hearts were subjected to 30 min of regional ischemia and 90 min of reperfusion 24 h after HS. Risk area was delineated by injection of 10% Evan's blue and infarct size determined using computer morphometry of tetrazolium stained sections. Infarct size (% area at risk) reduced significantly from 49.4 +/- 2.3% (n = 7) in sham to 10.0 +/- 2.5% (p < 0.01) and 9.1 +/- 3.0% in HS and vehicle treated HS groups respectively (p < 0.05) Treatment with chelerythrine prior to HS increased infarct size to 49.4 +/- 2.3% (p < 0.05). Infarct size in chelerythrine-treated non-HS ischemic/reperfused heart was 40.7 +/- 5.4%, which did not differ significantly from vehicle-treated sham group. Western blot analysis demonstrated marked increase in HSP 72 in HS groups (with or without vehicle treatment) and pretreatment with chelerythrine chloride failed to inhibit the expression of HSP 72. The results suggest that HS-induced ischemic tolerance is mediated via PKC pathway and this protection does not appear to be directly related to the expression of HSP 72 in rat heart.

Animals↗
PubMed1998

Heat shock transcription factor-1 regulates heat shock protein-72 expression in human keratinocytes exposed to ultraviolet B light.

In response to ultraviolet radiation (UVR), skin keratinocytes increase expression of heat shock proteins that can protect cells from stress-induced damage. This heat shock response is known to be transcriptionally regulated in eukaryotic cells exposed to certain forms of environmental stress. In the skin, absorption of ultraviolet B light occurs primarily in the epidermis, and therefore, using primary cultures of normal human epidermal keratinocytes, we have examined whether transcriptional activation of the hsp72 gene occurs following UVB irradiation. Cultured keratinocytes were exposed to UVB (290-320 nm, 300 J per m2) and then incubated at 37 degrees C for various intervals before harvesting. Immediately following UV exposure, the heat shock transcription factor 1 (HSF1) dissociated from HSP72-HSF1 complexes, underwent trimerization and phosphorylation, and demonstrated DNA binding activity to the heat shock element in the promoter region of the hsp72 gene. UVB also increased hsp72 mRNA, with peak levels observed 1-3 h post-UVR. HSP72 protein was constitutively expressed in keratinocytes, and its expression was increased by UVB, with maximum levels at 6 h post-UVR. The stress response may be extremely important in the protection of human skin from UVB radiation, and modulation of heat shock protein expression and/or function offers a potential therapeutic target in the prevention of photoaging and skin cancer.

Cells, Cultured↗
PubMed1997

Xenopus heat shock factor 1 is a nuclear protein before heat stress.

Stress-induced expression of the heat shock (hs) genes in eukaryotes is mediated by a transcription factor known as heat shock factor 1 (HSF1). HSF1 is present in a latent, monomeric form in unstressed metazoan cells and upon exposure to heat or other forms of stress is converted to an "active" trimeric form, which binds the promoters of hs genes and induces their transcription. The conversion of HSF1 to its active form is hypothesized to be a multistep process involving (i) oligomerization of HSF1, plus (ii) additional changes in its physical conformation, (iii) changes in its phosphorylation state, and for some species (iv) translocation from the cytoplasm to the nucleus. Oligomerization of HSF appears to be essential for high affinity DNA binding, but it remains unclear whether the other steps occur in all organisms or what their mechanistic roles are. In this study we have examined if heat-induced cytoplasmic-nuclear translocation of HSF1 occurs in Xenopus oocytes. We observed that germinal vesicles (nuclei) that were physically dissected from unshocked Xenopus laevis oocytes contain no HSF1 binding activity. Interestingly, in vitro heat shock treatments of isolated nuclei from unshocked oocytes activated HSF1 binding, indicating that HSF1 must have been present in the unshocked nuclei prior to isolation. Induction of HSF1 binding was not observed in enucleated oocytes. Western blot analysis using an affinity-purified polyclonal antibody made against X. laevis HSF1 showed that HSF1 is present in equal amounts in unshocked and shocked oocytes and isolated nuclei. HSF1 was not detected in enucleated oocytes. These results clearly demonstrate that HSF1 is a nuclear protein in oocytes prior to exposure to stress. In Xenopus oocytes, therefore, HSF1 translocation from the cytoplasm to the nucleus is not part of the multistep process of HSF1 activation. These results also imply that the signals and/or factors involved in HSF1 activation must have their effect in the nuclear compartment.

Animals↗
PubMed2002

The Escherichia coli small heat-shock proteins IbpA and IbpB prevent the aggregation of endogenous proteins denatured in vivo during extreme heat shock.

The roles of the Escherichia coli IbpA and IbpB chaperones in protection of heat-denatured proteins against irreversible aggregation in vivo were investigated. Overproduction of IbpA and IbpB resulted in stabilization of the denatured and reversibly aggregated proteins (the S fraction), which could be isolated from E. coli cells by sucrose gradient centrifugation. This finding is in agreement with the present model of the small heat-shock proteins' function, based mainly on in vitro studies. Deletion of the ibpAB operon resulted in almost twofold increase in protein aggregation and in inactivation of an enzyme (fructose-1,6-biphosphate aldolase) in cells incubated at 50 degrees C for 4 h, decreased efficiency of the removal of protein aggregates formed during prolonged incubation at 50 degrees C and affected cell viability at this temperature. IbpA/B proteins were not needed for removal of protein aggregates or for the enzyme protection/renaturation in cells heat shocked at 50 degrees C for 15 min. These results show that the IbpA/B proteins are required upon an extreme, long-term heat shock. Overproduction of IbpA but not IbpB caused an increase of the level of beta-lactamase precursor, which was localized in the S fraction, together with the IbpA protein, which suggests that the unfolded precursor binds to IbpA but not to IbpB. Although in the wild-type cells both E. coli small heat-shock proteins are known to localize in the S fraction, only 2% of total IbpB co-localized with the aggregated proteins in the absence of IbpA, while in the absence of IbpB, the majority of IbpA was present in the aggregates fraction.

Escherichia coli↗
PubMed2001

The loop domain of heat shock transcription factor 1 dictates DNA-binding specificity and responses to heat stress.

Eukaryotic heat shock transcription factors (HSF) regulate an evolutionarily conserved stress-response pathway essential for survival against a variety of environmental and developmental stresses. Although the highly similar HSF family members have distinct roles in responding to stress and activating target gene expression, the mechanisms that govern these roles are unknown. Here we identify a loop within the HSF1 DNA-binding domain that dictates HSF isoform specific DNA binding in vitro and preferential target gene activation by HSF family members in both a yeast transcription assay and in mammalian cells. These characteristics of the HSF1 loop region are transposable to HSF2 and sufficient to confer DNA-binding specificity, heat shock inducible HSP gene expression and protection from heat-induced apoptosis in vivo. In addition, the loop suppresses formation of the HSF1 trimer under basal conditions and is required for heat-inducible trimerization in a purified system in vitro, suggesting that this domain is a critical part of the HSF1 heat-stress-sensing mechanism. We propose that this domain defines a signature for HSF1 that constitutes an important determinant for how cells utilize a family of transcription factors to respond to distinct stresses.

Amino Acid Sequence↗
PubMed2003

Heat shock and Cd2+ exposure regulate PML and Daxx release from ND10 by independent mechanisms that modify the induction of heat-shock proteins 70 and 25 differently.

Nuclear domains called ND10 or PML bodies might function as nuclear depots by recruiting or releasing certain proteins. Although recruitment of proteins through interferon-induced upregulation and SUMO-1 modification level of PML had been defined, it is not known whether release of proteins is regulated and has physiological consequences. Exposure to sublethal environmental stress revealed a sequential release of ND10-associated proteins. Upon heat shock Daxx and Sp100 were released but PML remained, whereas exposure to subtoxic concentrations of CdCl(2) induced the release of ND10-associated proteins, including PML, with Sp100 remaining in a few sites. In both cases, recovery times were similar and were followed by a burst of mitotic activity. Cadmium-induced release of proteins from ND10 could be blocked by inhibiting activation of p38 MAPK or ERK1/2. By contrast, heat-shock-induced desumolation of PML and release of proteins from ND10 are unaffected by these inhibitors but can be recapitulated by overexpression of the SUMO isopeptidase SENP-1. Therefore, activation of SENP-1-like SUMO isopeptidase(s) during heat shock is not affected by these kinases. Thus, the release of ND10-associated proteins is not due to a general dispersal of nuclear domains but seems to be regulated by rapid desumolation during thermal stress and through the phosphorylation cascade of stress and mitogenic signaling pathways in the case of CdCl(2). Whether the release of certain proteins had consequences was tested for heat-shock-protein transcription and synthesis. Release of Daxx correlated with Hsp25 suppression, suggesting that Daxx normally inhibits immediate Hsp25 production. Release of PML correlated with lower production of Hsp70. These results suggest that segregation or release of PML or Daxx have differential physiological relevance during the stress response. The fact that enzymatic activation of protein release or segregation after stress modifies the heat-shock response strengthens the concept of ND10 as a regulated depot of effector proteins.

Animals↗
PubMed2005

Simultaneous radiofrequency (RF) heating and magnetic resonance (MR) thermal mapping using an intravascular MR imaging/RF heating system.

Previous studies have confirmed the possibility of using an intravascular MR imaging guidewire (MRIG) as a heating source to enhance vascular gene transfection/expression. This motivated us to develop a new intravascular system that can perform MR imaging, radiofrequncy (RF) heating, and MR temperature monitoring simultaneously in an MR scanner. To validate this concept, a series of mathematical simulations of RF power loss along a 0.032-inch MRIG and RF energy spatial distribution were performed to determine the optimum RF heating frequency. Then, an RF generator/amplifier and a filter box were built. The possibility for simultaneous RF heating and MR thermal mapping of the system was confirmed in vitro using a phantom, and the obtained thermal mapping profile was compared with the simulated RF power distribution. Subsequently, the feasibility of simultaneous RF heating and temperature monitoring was successfully validated in vivo in the aorta of living rabbits. This MR imaging/RF heating system offers a potential tool for intravascular MR-mediated, RF-enhanced vascular gene therapy.

Animals↗
PubMed1986

Variation in alpha-L-fucosidase properties among 28 inbred mouse strains: six strains have high enzyme activity and heat-stabile enzyme with a variant pH-activity curve; twenty-two strains have low activity and heat-labile enzyme.

Alpha-L-fucosidase in tissues of 28 inbred mouse strains varied with respect to three properties: high or low heat stability, a pH-activity curve with high or low relative activity at pH 2.8, and high or low activity. Alpha-L-fucosidase from six strains (A/J, BDP/J, LP/J, P/J, SEA/GNJ, and 129/J) had high heat stability, high pH 2.8 relative activity, and high activity, whereas the other 22 strains all had low heat stability, low pH 2.8 relative activity, and low activity. The heat-stability difference was seen in all organs tested (brain, liver, kidney, spleen, heart, skeletal muscle, lung, and testis) for two heat-stabile strains (P/J and 129/J) and four heat-labile strains (C57BL/6J, C3H/HeJ, DBA/2J, and BALB/cJ) studied in detail. The findings suggested that two structural variants of alpha-L-fucosidase, probably genetically determined, exist in these 28 inbred mouse strains, although the presence of linkage disequilibrium between alleles of tightly linked structural and regulatory genes could not be excluded.

Animals↗
PubMed1991

Microbiological aspects of heat sterilization of drugs. III. Heat resistance of spore-forming bacteria, isolated from large-volume parenterals.

In order to calculate the minimum sterilization process conditions to obtain the generally accepted sterility level (less than 1.10(-6) probability of microbial survival), we determined the bioburden and its heat resistance of 500 ml large-volume parenteral bottles over a period of 5 years. For the bioburden determination 1,832 bottles were examined by the membrane filtration method. Mean bioburden was 9.36 colony-forming units/bottle. Of the colony-forming units isolated 118 were heat resistant (0.69%). These were spore-forming Bacillus species. Of the isolated Bacillus species heat resistance was determined in 5% glucose, 0.9% sodium chloride and 8% amino acids solution. D values greater than 1 min at 105 degrees C were found for 2, 5 and 4 different Bacillus species in glucose 5%, sodium chloride 0.9% and amino acids 8%, respectively. 2 Bacillus species showed a D value over 2 min at 105 degrees C in all three media. D values at 110 degrees C in sodium chloride 0.9% for these 2 Bacillus species were 1.8 and 2.6 min and in amino acids 8% 0.9 and 1.7 min, respectively. The minimum sterilization process time at 110 degrees C, calculated with the experimentally determined bioburden and D values is less than 25 min. When introducing reduced exposure times/temperatures, each individual manufacturer should assess the bioburden. The time-consuming determination of the heat resistance of bioburden isolates is not always necessary. By dividing the isolated colony-forming units in a 'heat-resistant' group and a 'not-heat-resistant' group, changing from standard overkill sterilization procedures to processes with lower F0 values is possible.

Bacillus↗