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PubMedDate not supplied

Heat shock protection against induction of chromatid aberrations is dependent on the time span between heat shock and clastogen treatment of Vicia faba root tip meristem cells.

Variation of the time span between heat shock (hs) and clastogen treatment of V. faba root tip meristems showed that hs protection is a very quick response (effective after less than 10 min) and lasting for up to 240 min in the case of induction of chromatid aberrations by maleic hydrazide (MH). Analogous protective responses are significantly slower and shorter when TEM is used for aberration induction. This, together with absence of 'clastogenic cross-adaptation' to these agents and differential effects of benzamide (BA, an inhibitor of poly-ADP-ribosylation) pretreatment before hs on hs protection, suggests that hs before clastogen treatment triggers at least 2 clastogen-specific, protective functions which eventually result in protection against these 2 clastogens.

Chromosome Aberrations↗
PubMed1989

Effect of NaCl on the heating activation of the heat-stable alkaline proteinases from various animal muscles.

1. Heat-stable alkaline proteinase (HAP) showed a wide distribution in fish, avian and mammalian muscles, while the total activity varied among animal species. 2. Total activity of HAP was changeable according to the degree of maturation in the case of chum salmon. 3. Effect of NaCl on HAPs varied among animal species. 4. It seems likely that the different sensitivity of HAPs to NaCl reflects the difference in the living circumstances of each animal species. 5. It is also postulated that the different sensitivity of HAPs to NaCl reflects the conformational diversity of the regulatory structure of HAP among animal species.

Aging↗
PubMed1998

A longitudinal study of immunological status in Chinese haemophiliacs: importance of the heat viral inactivation of factor concentrates. II. Improvements of CD4/CD8 ratio after treatments with heat-inactivated factor concentrates.

Screened and heated clotting factor concentrates of intermediate purity have been used in Taiwanese haemophiliacs since the end of 1986. A significant improvement of CD4/CD8 ratio during the years 1987-1989 as compared with those during the years 1984-1986 was observed in haemophilia A patients [mean +/- SD (median), 1.191 +/- 0.495 (1.163) vs. 0.880 +/- 0.325 (0.838), P = 0.0020] who were seronegative for human immunodeficiency virus. Almost all patients received an increased amount of factor VIII concentrates and total plasma products since 1987. Multiple linear regression analysis for the association of CD4/CD8 ratio with changes in dosage of plasma products revealed that there was a significant positive association of CD4/CD8 ratio measured during 1987-1989 with dosage of factor VIII concentrate administered during 1984-1986 (P = 0.0230), which is an indicator for changes in viral load, but not with changes in dosage of plasma products, which are indicators for changes in plasma protein intake. Our data indicate that immunological abnormalities after replacement therapy observed in haemophiliacs are mainly attributed to virus infection through infusion of factor concentrates, not to allogeneic proteins existing in plasma products.

Adolescent↗
PubMed1985

Brown adipose tissue heat production in heat acclimated and perchlorate treated rats.

The noradrenaline-induced energy dissipation rate was measured with a direct microcalorimeter in brown adipose tissue taken from rats acclimated to 34 degrees C (HA), perchlorate treated (PC) and heat acclimated-perchlorate treated (HAPC). The response to 10(-7) M NA was reduced by 45%, 47% and 86% in HA, PC and HAPC groups, respectively, as compared to a control group kept at 24 degrees C. In the same groups, the response to 10(-6) M NA was reduced by 34%, 7% and 64%, respectively. The specific activity of the soluble alpha-glycerophosphate dehydrogenase in brown fat from HA rats was reduced by 50%, whereas it was not altered in the PC animals. It is concluded that the sensitivity to noradrenaline of the brown adipose tissue thermogenic mechanisms is decreased in hypothyroidism, and that the acclimation temperature and the thyroid status per se each have a different influence on brown adipose tissue function.

Acclimatization↗
PubMed1995

Blood lactate concentration following exercise: effects of heat exposure and of active recovery in heat-acclimatized subjects.

The purpose of this study was to examine the effect of ambient heat on the decrease in blood lactate concentration ([LA]bl) during passive and during active recovery. Ten trained men performed six 1-min bouts of exercise at 100% VO2peak on a cycle ergometer, with 1-min rest between the bouts. Each subject exercised twice in thermoneutral (22 degrees C, 40% RH, TN), and twice in hot (35 degrees C, 30% RH, H) conditions. Exercise was followed by either 40 min of passive recovery (sitting) or by 20 min active recovery (cycling at 35% VO2peak) and 20 min passive recovery, named thereafter, 'active recovery'. Capillary blood lactate was measured before, 1 min after, and every 5 min during recovery. Heart rate (HR), rectal and skin temperatures (Tre, Tsk) were monitored continuously. VO2 was measured prior to exercise, during the last exercise bout, the first 10 min of recovery, and periodically thereafter. Post-exercise [LA]bl was similar in all treatments (13.5 +/- 1.8, 13.0 +/- 1.3, 14.8 +/- 4.1, 13.3 +/- 2.6 mmol.l-1 for TN-active, TN-passive, H-active and H-passive, respectively). [LA]bl was significantly lower during active, compared to passive recovery in both, TN and H conditions. Environmental heart did not independently affect [LA]bl during passive or active recovery. Exercise resulted in an elevation in Tre in all treatments, with a significantly higher Tre during active recovery in H compared to the other sessions. Likewise, no differences in HR and in VO2 were observed between H and TN conditions during active nor during passive recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1992

A study of heat production and heat loss in crated broiler chickens: a mathematical model for a single bird.

1. A steady state model of heat production and loss in crated broiler chickens is presented. 2. The model is based on physiological factors and uses experimental data from various sources. 3. Although many of the required parameters are not well defined at present, the model allows a better understanding of the processes which lead to hyperthermic stress in crated broiler chickens, and is relevant to the design of ventilation systems for poultry transporters.

Animals↗
PubMed1981

Comparison of sensitivity of rad mutants of diploid yeast to heat and gamma radiation: cellular target for heat inactivation.

Wild type and radiation-sensitive mutants rad 53, 54 and 55 of the diploid yeast Saccharomyces cerevisiae, in stationary and log phase were exposed to gamma radiation and hyperthermia (51 degrees C) in order to compare their sensitivity to these agents. The wild type diploid strain exposed to gamma rays showed a sigmoidal survival curve both in stationary and log phase cultures. Log phase cells were significantly more resistant than stationary phase cells. When compared to wild type, the gamma radiation response of the mutants indicated that the mutations in these RAD loci render the cells sensitive in stationary phase and very sensitive in log phase. The response of mutants to hyperthermia was similar to that of wild type cells in both the phases. The log phase cells of both wild type and mutants wee gamma radiation response of the mutants indicated that the mutations in these RAD loci render the cells sensitive in stationary phase and very sensitive in log phase. The response of mutants to hyperthermia was similar to that of wild type cells in both the phases. The log phase cells of both wild type and mutants wee gamma radiation response of the mutants indicated that the mutations in these RAD loci render the cells sensitive in stationary phase and very sensitive in log phase. The response of mutants to hyperthermia was similar to that of wild type cells in both the phases. The log phase cells of both wild type and mutants were more sensitive to heat than stationary phase cells. These results suggest that the RAD loci are not involved in the repair of hyperthermic damage. Since it is known that the products of the RAD genes are involved in the repair of DNA damage, the wild type response of these rad mutants to hyperthermia indicates that the DNA may not be the principal target for hyperthermic killing. Furthermore, the enhanced thermal sensitivity of log phase cells, containing higher amounts of active enzymes and sensitive membrane, strongly suggests that proteins and/or membranes could be the primary targets for thermal inactivation.

Cell Survival↗
PubMed2000

Energy confinement time and heat transport in initial neutral beam heated plasmas on the large helical device

The confinement characteristics of large net-current-free plasmas heated by neutral-beam injection have been investigated in the Large Helical Device (LHD). A systematic enhancement in energy-confinement times from the scaling derived from the medium-sized heliotron/torsatron experiments have been observed, which is attributed to the edge pedestal. The core confinement is scaled with the Bohm term divided by the square root of the gyro radii. The comparative analysis using a dimensionally similar discharge in the Compact Helical System indicates gyro-Bohm dependence in the core and transport improvement in the edge region of LHD plasmas.

Journal Article↗
PubMed1979

Passive transfer in man and the monkey of Type I allergy due to heat labile and heat stable antibody to complex salts of platinum.

Passive transfer (P-K) tests have been performed in man and monkeys with sera from a group of six refinery workers sensitive to ammonium hexachloroplatinate and tetrachloroplatinite. Positive (P-K) prick test reactions were elicited in three human recipients and in the monkey to three of the test sera. The other three sera gave inconsistent results in man and negative results in monkeys and these differences appeared to correspond with the duration of exposure of the workers. The passive transfer tests did not correlate with the intensity of the prick test reactions in the donors or with the RAST; there was partial correlation with total levels of IgE. Antigen mediated histamine release from whole blood and washed leucocytes from two of the six subjects correlated with the RAST and P-K levels. These findings confirm the presence of specific IgE antibody to the platinum salts, and also of heat stable, short-term sensitising antibodies, presumably STS-IgG.

Adult↗
PubMed1978

Dry-heat destruction of lipopolysaccharide: dry-heat destruction kinetics.

Dry-heat destruction kinetics of lipopolysaccharides from Escherichia coli, Serratia marcescens, and Salmonella typhosa at 170 to 250 degrees C are described. The destruction rate seems to follow the second order and can be linearized by the equation, log y = a + b . -10cx. Because c is the slope, 1/c = D3. Both a and b are constant at a given temperature and are linear functions of temperature. The D(3)170, D(3)190, D(3)210, D(3)230, and D(3)250 values for E. coli lipopolysaccharide are 251, 99.4, 33.3, 12.3, and 4.99 min, respectively, with a z value of 46.4 min. The D values for lipopolysaccharides from S. marcescens and S. typhosa are not significantly different from those from E. coli lipopolysaccharide.

Escherichia coli↗
PubMed1981

Molecular organization of heat-labile enterotoxin genes originating in Escherichia coli of human origin and construction of heat-labile toxoid-producing strains.

Recombinant deoxyribonucleic acid technology was employed to construct heat-labile enterotoxin (LT) toxoids. A recombinant plasmid carrying both an LT promoter region and LT subunit A (LTA) gene, lacking as much as 0.25 kilobases of the region up to the C terminus, produced a peptide possessing immunological properties of LTA but lacking the ability to construct LT activity (designated as LTA*). A cloned LT subunit B (LTB) gene produced LTB when a promoter on a vector was available for the gene. Escherichia coli producing LTA* and LTB (LT toxoids) could be useful as a vaccine.

Bacterial Toxins↗
PubMed1989

Serotype-related differences in production and type of heat-labile hemolysin and heat-labile cytotoxin of Actinobacillus (Haemophilus) pleuropneumoniae.

Reference strains of serotypes 1 to 12 of Actinobacillus (Haemophilus) pleuropneumoniae were cultured in Eagle minimal essential medium with 10% Serum Plus. Culture supernatants were examined for cytotoxicity to alveolar macrophages and for the ability to hemolyze sheep erythrocytes. All strains except the reference strain of serotype 6 produced cytotoxin, whereas only serotypes 1, 5, 9, 10, and 11 produced hemolysin. Both cytotoxin and hemolysin appeared to be heat labile. Antisera were raised against cytotoxin- and hemolysin-containing culture supernatants of serotypes 1 to 11. Cross-neutralization studies revealed that the hemolysins were serologically homogeneous. In contrast, four serologically different cytotoxins were distinguished. One cytotoxin was produced by serotypes 1, 5, 9, and 11, and a second was produced by serotypes 2, 3, 4, and 8. A third cytotoxin was produced by serotypes 7 and 12; this cytotoxin was related to the cytotoxins of serotypes 1, 2, 4, 5, 9, and 11. A fourth cytotoxin, produced by serotype 10, was related to the cytotoxin of serotypes 1, 5, 9, and 11. Seventy field strains belonging to serotypes 2, 3, 7, 8, 9, and 11 were also tested for production of cytotoxin and hemolysin. All strains belonging to serotypes 9 and 11 produced hemolysin and cytotoxin, whereas all strains of serotypes 2, 3, 7, and 8 produced only cytotoxin. Hemolysins and cytotoxins of both the field strains and the corresponding serotype reference strains were comparably neutralized. These findings strongly suggest that the observed differences in production and type of hemolysin and cytotoxin were related to serotype and not to strain.

Actinobacillus↗
PubMed1973

Protein kinase activity from vaccinia virions: solubilization and separation into heat-labile and heat-stable components.

A protein kinase was solubilized from whole vaccinia virions by using a solution containing deoxycholate, dithiothreitol, and sodium or potassium chloride. The released enzyme was completely dependent on Mg(2+) and was greatly stimulated by added basic proteins such as protamine or histones. Dithiothreitol was also stimulatory, whereas GTP, CTP, UTP, and P(i) at concentrations equimolar with ATP had little or no effect. Attempts to purify the protein kinase were initially unsuccessful, leading us to consider that either the enzyme was extremely labile or that two readily separable components were required for activity. The observation that the material extracted with NP-40 detergent during the preparation of viral cores stimulated the protein kinase activity of the intact cores supported the second possibility. As the protein kinase, now solubilized from viral cores, was passed through successive DEAE-cellulose columns, it became increasingly dependent for activity on addition of the NP-40 extract. A 30- to 40-fold stimulation of protein kinase activity, which afforded recovery of essentially all starting activity, could be effected by addition of the NP-40 extract to the partially purified enzyme. The NP-40 extract was shown to contain a heat stable, trypsin-sensitive protein, whose action could not be duplicated by cyclic nucleotides.

Chromatography, DEAE-Cellulose↗
PubMed1971

Heat losses from a breathing system with a heated-water humidifier.

Air was "breathed" in the laboratory through a heated-water humidifier and a breathing tube. Several different humidifiers and tubes were used. The temperature rise of the air on passing through the humidifier and the temperature drop on passing through the tube were measured. Both were dependent on ventilation. Insulating the tube and humidifier together with the insertion of baffles in the latter reduced the rise and fall and their dependence on ventilation. With suitable design the dependence on ventilation and the need to use high water temperatures could be greatly reduced. In addition, a thermostat with a reduced dead zone is needed.

Air↗
PubMed2004

Epitope mapping of Porphyromonas gingivalis heat-shock protein and human heat-shock protein in human atherosclerosis.

To identify T- and/or cross-reactive B-cell epitopes of P. gingivalis and human heat-shock protein (HSP)60 in atherosclerosis patients, we synthesized 104 overlapping synthetic peptides spanning whole molecules of P. gingivalis HSP60 and human HSP60, respectively. T-cell epitopes of P. gingivalis HSP were identified with the use of previously established P. gingivalis HSP-reactive T-cell lines. B-cell epitopes of P. gingivalis HSP60 and human HSP60 were identified by the use of patients' sera. Anti-P. gingivalis, anti-P. gingivalis HSP60, or anti-human HSP60 IgG antibody titers were higher in the atherosclerosis patients compared with the healthy subjects. Five immunodominant peptides of P. gingivalis HSP60, identified as T-cell epitopes, were also found to be B-cell epitopes. Moreover, 6 cross-reactive B-cell epitopes of human HSP60 were identified. It was concluded that P. gingivalis HSP60 might be involved in the immunoregulatory process of atherosclerosis, with common T- and/or B-cell epitope specificities and with cross-reactivity with human HSP60.

Aged↗
PubMed1985

Decreased core-to-skin heat transfer in mild essential hypertensives exercising in the heat.

In previous reports (1,2) we examined the physiological responses of normotensive and essentially hypertensive men to steady state leg exercise (at 40% V02max) in a warm (38 degrees C dry-bulb, 28 degrees C wet-bulb) environment. Those results are reviewed. Additionally, in this paper we report relative core-to-skin heat transfer (HT) characteristics of these two groups, matched for age, aerobic fitness, and body composition, but differing in resting blood pressure. Forearm skin blood flow (as measured from changes in total forearm blood flow) was relatively reduced in the hypertensives. This resulted in a similar (but slightly compensated) reduction in HT, e.g., at minute 30, the hypertensives had 81% less skin blood flow and 56% less HT than their normotensive counterparts. This finding has important implications for unmedicated mild hypertensives exercising or working in hot environments.

Adult↗
PubMed1975

Mechanisms of heat damage in proteins. 5. The nutritional values of heat-damaged and propionylated proteins as sources of lysine, methionine and tryptophan.

The preparation of a propionylated protein is described, and the effects of this treatment on amino acid composition and availability are compared with the effects of severe heat treatment (autoclaving) of a protein. 2. Using chemical analyses, changes exceeding 5% for total tyrosine, histidine, methionine and cystine contents were found after propionylation of the protein. Autoclaving of the protein resulted in changes in total serine, lysine, methionine, cystine and tryptophan contents. 3. Microbiological estimates of total amino acid contents were not in close agreement with the chemical estimates for the autoclaved protein. 4. Fluorodinitrobenzene-reactive lysine content was reduced to almost zero by propionylation, and by almost 40% by autoclaving. 5. Both propionylating and autoclaving protein reduced the amount of lysine available to the chick by about half. In contrast, the availabilities of methionine and tryptophan to the chick were unchanged by propionylation, but were reduced to 0.66 and 0.44 respectively, relative to the untreated protein, by autoclaving. 6. Because of the difficulties of obtaining reliable absolute estimates of amino acid availability using chick growth assays, our interpretation of results is mainly based on relative values. The merits of microbiological estimates of amino acid availability are assessed.

Amino Acids↗