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At least 19 recordsLinked to original sources
PubMed1979

Heat inactivation of superoxide dismutase in bovine milk.

Superoxide dismutase, and enzyme normal to bovine milk, may be inactivated partially by heat during processing of milk and milk products. A minimal pasteurization temperature (71.7 C for 15 s) does not cause heat inactivation of superoxide dismutase. Higher temperature of pasteurization or systems including a 'vac-heat process' will inactivate a substantial portion of the enzyme. Heat treatments greater than 75 C inactivated more than 20% of the superoxide dismutase. Purified superoxide dismutase fractionated from bovine milk was more sensitive to thermal processing than the superoxide dismutase in bovine milk serum.

Animals↗
PubMed1978

Heat inactivation of enteric viruses in dewatered wastewater sludge.

The effect of moisture content on the rates of heat inactivation of enteric viruses in wastewater sludge was determined. The protective effect of raw sludge on poliovirus previously observed (R. L. Ward, C. S. Ashley, and R. H. Moseley, Appl. Environ. Microbiol. 32:339--346, 1976) was found to be greatly enhanced in sludge dewatered by evaporation. Other enteroviruses responded in a similar fashion. This effect did not appear to be due merely to the state of dryness of the sludge samples because in humus-deficient soil, a relatively inert material, the rate of poliovirus inactivation by heat was not significantly altered through dewatering. Instead, this effect appeared to have been caused by protective substances in the sludge, such as detergents, which are concentrated through dewatering. As reported previously (R. L. Ward and C. S. Ashley, Appl. Environ. Microbiol. 34:681-688, 1977; R. L. Ward and C. S. Ashley, Appl. Environ. Microbiol 36:889--897, 1978) raw sludge is not protective of reovirus, but, instead, the ionic detergents in sludge cause the rate of heat inactivation of this virus to be accelerated. Dewatering of sludge, however, was found to partially reverse this virucidal effect. Evidence is presented indicating that this reversal is caused by an unidentified protective substance in sludge also concentrated through dewatering. Finally, it was shown that the effects of raw sludge on heat inactivation of poliovirus and reovirus are greatly reduced by composting, a result that correlated with the degradation of detergents.

Enterovirus↗
PubMed1976

[Antibody titers--curse in patients with recurring Herpes simplex virus infections under vaccination with heat-inactivated Herpes viruses].

Follow-up studies of antibody-titres in patients suffering from recidivations of herpes labialis and progenitalis treated with herpes virus vaccine inactivated by heat. It was stated by several authors that patients suffering from recidivations of herpes labialis and progenitalis can be successfully treated with a herpes virus vaccine inactivated by heat (Lupidon G/H). Nothing is known, however, about the mechanisms diminishing recurrences. We have studied 11 patients and 3 control persons whether there were changes in specific antibody titres after repeated vaccinations. Skin reactions following intradermal injections were also tested. Serum samples studied over a period of 8 weeks until 9 months showed that the antibody titres found by complement-fixation and neutralization tests remained practically constant. Skin tests were always negative. Therefore it merits further study to find out the mode of action of this clinically successful treatment.

Antibodies, Viral↗
PubMed1975

Dry-heat inactivation of Bacillus subtilis spores by means of infra-red heating.

An experumental equipment for dry-heat inactivation of bacterial spores in an open system using Infrared (IR) radiation for energy transfer was deveoped. The dry-heat-inactivation kinetics for Bacillus subtilis ATCC 6633 spores were studied in the temperature range of 120-180 C. The z value (z = 23C) was constant in the temperature range investigated. The advantages offered by using IR radiation in sterilization systems are pointed out.

Bacillus subtilis↗
PubMed1976

Role of keratinases in dermatophytosis. IV. Reactivities of sera from guinea pigs with heat-inactivated keratinase II.

Complement-fixing antibodies to the heat-inactivated keratinase II of Trichophyton mentagrophytes var. granulosum were detectable in sera from approximately 40% of the Hartley strain guinea pigs previously infected with this dermatophyte. However, no precipitating antibodies to the heat-inactivated keratinase II were detectable in these sera. Guinea pigs immunized with the heat-inactivated keratinase II had both complement-fixing and precipitating antibodies to the keratinase II. Circulating antibodies in sera from both the infected and the immunized guinea pigs also reacted with the active keratinase II but did not inhibit its proteolytic activity.

Animals↗
PubMed1978

[Kinetics and thermodynamics of heat inactivation of L-threonine-L-serine dehydratase from human liver].

It has been shown that heat inactivation of L-threonine- and L-serine dehydratase activities at 37; 45; 50 and 55 degrees C in human liver extracts (the liver was ectracted with buffer containing 1.10(-5) M of pyridoxal 5'-phosphate) in course of time is practically identical, and characterizes by the same of values of activation energy of heat inactivation process, activation enthalpy of this process, activation free energy of that and activation enthalpy of the heat inactivation process. A rise of pyridoxal 5'-phosphate concentration (to 2.10(-4) M) in the buffer used for the liver extraction and hence in the medium in which the heat inactivation process was carried out stabilises L-threonine- and L-serine dehydratase activities against the inactivation at 55 degrees C. It has been concluded thatL-threonine- and L-serine dehydratase activities in human liver belong to the single protein or to two proteins having very like physico-chemical properties, and that pyridoxal 5'-phosphate is essential for this enzyme not only as coenzyme but also it is necessary to support active and stable conformation of this oligomeric protein.

Adult↗
PubMed1976

Serological characteristics of the Leptospira serogroup Pomona. II. Changes in the agglutination and absorption properties of the reference strains after formalin- and heat-inactivation.

After formalin or heat-inactivation for 30 minutes at 56 degrees C, the absorption properties of some Pomona serogroup strains diminish, which indicates that they have thermolabile (Pomona, CZ 299U and LT 796) or formalin-labile (Pomona and 5621) minor antigenic factors. The agglutination properties of the various strains change differently after inactivation though not in parallel with the absorption properties.

Absorption↗
PubMed1978

Heat inactivation of vaccinia virus particle-associated functions: properties of heated particles in vivo and in vitro.

The heat inactivation characteristics of several vaccinia virus particle-associated functions known to be involved in the transcription of the genome were examined. All functions were more resistant to heat than infectivity. Noninfectious particles were generated which exhibited significant levels of activity of all enzymes examined, and their properties were investigaed both in vitro and in vivo. RNA was synthesized in vitro by such particles, although transport of the RNA into the surrounding medium was defective. This RNA was larger than that made in normal particles but it was polyadenylated and functioned in vitro as a message coding for normal early proteins. The sequences transcribed were similar to those transcribed in normal particles, and we suggest that the production of abnormally large RNA is due to a defect in transcriptional termination. We could not detect any virus-specific protein or RNA synthesis in cells exposed to these inactivated particles and conclude that the loss of infectivity caused by heating is due to a general decline in the activities of a number of particle functions.

Cell Line↗
PubMed1978

The effect of heat-inactivated murine cytomegalovirus on host DNA synthesis of different cells.

Heat-inactivated murine cytomegalovirus (MCMV) stimulates cellular DNA synthesis in WME, NMG, 3T3, WgIA, chick and NIK-8 cells, but active or u.v.-irradiated MCMV does not. The stimulation of DNA synthesis in NIL-8 and chick cells was studied in detail. We found that both the nuclear and the mitochondrial DNA synthesis were stimulated in these cells. There was no virus DNA synthesis during the period we studied (48 h). The stimulation of nuclear DNA synthesis was about threefold in NIL-8 and 2.5-fold in chick cells as measured by the rate of incorporation of 3H-thymidine (3H-dThd) in the CsCl fractions which banded at the density of cell DNA. The stimulation was about 9.5-fold in NIL-8 and 1.7-fold in chick cells as detected by autoradiography. There was a 3-fold and a 2.2-fold increase in the degree of incorporation of 3H-dThd into mitochondrial DNA of NIL-8 and chick cells, respectively. The amount of mitochondrial DNA obtained in infected cells of both kinds was about twice that in control cells. The synthesis of mitochondrial DNA was also stimulated by a factor of 2 in the thymidine kinaseless 3T3 cells which incorporate exogenous thymidine exclusively into mitochondrial DNA. There were no MCMV specific antigens detectable by immunofluorescence 5 h after infection, but diffuse nuclear fluorescence could be demonstrated 24 h after infection. Our results indicate that the heat-inactivated virus penetrates the cells, stimulates host DNA synthesis and induces synthesis of early MCMV antigens.

Animals↗
PubMed1976

Stabilization of human serum alkaline phosphatase to histidine-induced heat inactivation by tryptic digestion.

1. Serum alkaline phosphatase [EC 3.1.3.1] was strongly inactivated by histidine during incubation at pH 8.0 and 45degrees; however, tryptic digestion of the serum strongly protected the enzyme against inactivation by histidine. In the absence of histidine, however, neither heat inactivation of the phosphatase nor the effect of trypsin [EC 3.4.21.4] was observed. Factors affecting the alkaline phosphatase inactivation were studied further. 2. The effect of trypsin on the histidine-induced heat inactivation differed considerably according to the tissue source of the enzyme, which suggests a possible method for distinguishing alkaline phosphatase isoenzymes.

Alkaline Phosphatase↗
PubMed1979

The effect of heat inactivation of serum on aggregation of immunoglobulins.

Heating serum at 56 degrees is used to inactivate complement in several immunological assays. During heating, both heat-labile and heat-stable anticomplementary activity (ACA) develop. While heat-labile ACA can be completely inactivated, heat-stable ACA increases progressively with continued heating. Heat-stable ACA develops in deaggregated IgG and in normal, but not in hypogammaglobulinaemic, human and porcine serum heated at 56 degrees suggesting that this ACA is due to formation of immunoglobulin aggregates. These aggregates would produce false-positive tests for immune complexes and could inhibit a variety of cell-mediated reactions in assays which incorporate heat-inactivated serum. Other temperatures were tested to determine whether endogenous haemolytic activity could be destroyed without forming immunoglobulin aggregates. At 53 degrees both endogenous haemolytic activity and heat-labile ACA were inactivated and formation of heat-stable ACA in normal serum was minimal. ACA, however, could be induced in deaggregated IgG at 53 degrees. Moreover, the degree of heat-induced aggregation of IgG in vitro at either temperature was directly proportional to IgG concentrations and inversely related to albumin concentrations. Thus, pathological sera with these protein alterations might form more aggregates during heating than normal sera. These data suggest the following: (1) heat inactivation of complement at 53 degrees for 90 min is preferable to the traditional 56 degrees; (2) in any assay where immunoglobulin aggregates might interfere, normal serum may be an inadequate control and correlations will need to be made between serum IgG and albumin concentrations and the results obtained in these assays.

Adult↗
PubMed1978

Polyethylene glycol-induced fusion of heat-inactivated and living protoplasts of Bacillus megaterium.

Protoplasts of Bacillus megaterium, incubated at 50 degrees C for 120 min, lost the ability to revert to bacillary form. Such heat-inactivated protoplasts, however, produced recombinants when fused by polyethylene glycol treatment with normal protoplasts. Although this differential inactivation effect is not yet fully reproducible, reciprocal inactivations of the parental protoplasts in genetic crosses have clearly shown that for protoplast fusion (i) either of the parents may serve as the viable recipient for markers coming from the heated parental protoplasts, and (ii) either of the parents may be rendered nonviable and yet, when fused with a viable partner, contribute to formation of a recombinant. Heat inactivation seems to provide a way to counterselect when few markers are available and one of the parents is prototrophic.

Bacillus megaterium↗
PubMed1979

Platelet monoamine oxidase: studies on the rate of heat inactivation in normal and in paranoid and nonparanoid chronic schizophrenic groups.

The heat inactivation curves for platelet monoamine oxidase (MAO) in chronic schizophrenic and normal subjects were virtually identical. There were also no differences found when schizophrenic patients were subgrouped into paranoid and nonparanoid types. However, the MAO from one of the normal subjects showed a substantially greater thermolability than that of any other control or schizophrenic subject.

Blood Platelets↗
PubMed1976

Heat inactivation of poliovirus in wastewater sludge.

The effect of raw and anaerobically digested sludge on heat inactivation of poliovirus was investigated. Raw sludge was found to be very protective of poliovirus plaque-forming ability at all temperatures studied, but digested sludge had variable effects that were highly dependent upon the experimental conditions. In low concentrations and at relatively low inactivation temperatures, digested sludge is nearly as protective of poliovirus as raw sludge. However, at higher tempeatures and concentrations, digested sludge caused a significant acceleration of poliovirus inactivation. The difference between the protective capability of raw and digested sludge is not due to loss of protective material, because this component is present in the solids of digested sludge as well as in those of raw sludge. Instead, the difference is due to a virucidal agent acquired during digestion. Addition of this agent to the solids of either raw or digested sludge reverses the protective potential of these solids during heat treatment of poliovirus.

Anaerobiosis↗
PubMed1976

Dry-heat inactivation of Bacillus subtilis var. niger spores with special reference to spore density.

The dry-heat inactivation kinetics of Bacillus subtilis var. niger (ATCC9372) spores has been studied in the temperature range of 120-190 degrees C. The spores were applied to glass plates of a standardized area (3.24 cm2). Spore preparations of five different spore densities were used (8.3 X 10(4), 7.4 X 10(6), 6.3 X 10(7), and 6.6 X 10(8) spores per sample, respectively). The heat resistance of the spore was dependent on the number of spores per surface unit. Maximum resistance was observed when the concentration was 7.4 X 10(5) spores per sample. The D-values obtained at 160 degrees C from these samples were about twice as high as the D-values obtained from samples with a concentration of 6.3 X 10(7) or 6.6 X 10(8) spores per sample. The z-value was found to be independent of spore density. Thus, for the two concentrations 7.4 X 10(5) and 6.3 X 10(7) spores per sample, the z-value was found to be 22 degrees C and constant over the temperature range investigated.

Bacillus subtilis↗
PubMed1975

Influence of pH on the heat inactivation of staphylococcal enterotoxin A as determined by monkey feeding and serological assay.

The effect of pH on the thermal inactivation of staphylococcal enterotoxin A was investigated. Analysis of heated toxin by immunodiffusion in gel indicated that enterotoxin A in beef bouillon was inactivated faster at pH 5.3 than at pH 6.2. The z values (slopes) for the heat inactivation curves at pH 6.2 and 5.3 were 49.5 and 55 F (about 27 and 30 C), respectively. Enterotoxin produced and heated in dialyzed Casamino Acids medium and assayed by monkey feeding was more easily inactivated by heat at pH 5.3 than at pH 7.8. Thermal inactivation curves for enterotoxin A in beef bouillon (5 mug/ml, pH 5.3) were determined by two methods, monkey feeding and serological assay. The z values for the curves obtained by these two methods were both 55 F, although loss of biological or toxic activity of the enterotoxin occurred before loss of serological activity.

Animal Feed↗
PubMed1977

Biochemical and genetic factors in the heat inactivation of murine beta-glucuronidase.

The enzymes coded for by two alleles at the glucuronidase structural locus (Gus) were compared in their response to pH, buffering anion, buffer molarity, ionic strength, and temperature. The heat-labile Gush gene product responded in a qualitatively similar but quantitatively reduced manner compared to the relatively heat-stable Gusb gene product. In all buffers tested, the enzyme was most heat stable at pH 5.0. Ranking of the various buffer anions tested, according to increasing heat stabilization, was water less than acetate less than or equal to phosphate less than citrate. Varying the molarity of the buffers from 0.01 to 0.6 M at pH 5.0 revealed further differences among the buffers. Increasing ionic strength exerted a destabilizing force on the protein. The half-life of the enzyme decreased by as much as a hundredfold between 71 and 75 C. The Gush/Gush genotype also results in decreased activity levels in all tissues, reportedly because of decreased synthesis. The heat inactivation curves of Gusb/Gush heterozygotes were incompatible with any theoretical curve based on the assumption that the Gusb and Gush chromosomes in the heterozygote behave in a manner similar to that seen in the homozygotes.

Alleles↗