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At least 1,387 records · Page 77Linked to original sources
PubMed1983

Clostridium oedematiens antitoxin: the correlation between anti-lethal and anti-edematizing activities.

To re-evaluate the current potency tests of C. oedematiens anti-toxin that titrates only the anti-lethal activity in mice, investigations were made on neutralization of the lethal, edematizing, and hemolytic activities with different preparations of the antitoxin and on their therapeutic effects. The anti-lethal and anti-edematizing potencies of antitoxins prepared by hyperimmunization with each of crude and purified antigens were the same when titrated with either crude or purified lethal toxin as test toxin. The two antitoxins protected mice equally against the lethal and edematizing activities of crude toxin. The antitoxin prepared against highly purified hemolytic toxin contained neither anti-lethal nor anti-edematizing activity. We conclude that the lethal and edematizing activities of C. oedematiens. are borne by the same molecule and that the therapeutic effect of the antitoxin may depend entirely on the anti-lethal (or anti-edematizing) activity. The method currently used for titrating C. oedematiens antitoxin, therefore, appears to be valid.

Animals↗
PubMed1994

Comparative analysis of tetanus antitoxin titers of sera from immunized mice and guinea pigs determined by toxin neutralization test and enzyme-linked immunosorbent assay.

Enzyme-linked immunosorbent assay (ELISA) and toxin neutralization (TN) test were comparatively evaluated for determination of antibodies to tetanus toxin in sera of immunized guinea pigs and mice at different intervals. Tetanus specific IgG antibodies by ELISA were found in sera of guinea pigs at ninth day after inoculation and in mice sera at seventh day after inoculation when there were no TN antibodies. Two weeks after injection of mice with aluminium phosphate adsorbed tetanus toxoid, anti-tetanus toxin IgG levels determined by ELISA were 35 to 40 times higher than the TN titers. At 4 weeks, ELISA IgG antibody levels of mice and guinea pig sera were still statistically significantly higher than TN titers but with a good correlation between ELISA and TN titers (correlation coefficient of mice sera 0.89). Mice sera at 2 weeks after two doses of tetanus toxoid (interval between doses 30 days) and 8 weeks after a single injection showed similar ELISA and TN titers (P > 0.1). Guinea pig sera at 6 weeks after a single injection showed similar TN and ELISA titers (P > 0.4). During the course of immunization in mice and guinea pigs, low avidity and low affinity IgG antibodies start appearing early which are detected by ELISA but not by TN test. Therefore ELISA results on sera before 6 weeks of immunization determined against a hyper-immune reference serum do not give a true picture of TN levels.

Animals↗
PubMed1962

The biological, immunological, and physicochemical characterization of a transmissible agent capable of inducing DNA and thymine degradation in cultured human cells.

EXPERIMENTS DESIGNED TO CHARACTERIZE AN UNIDENTIFIED TRANSMISSIBLE AGENT BROUGHT FORTH THE FOLLOWING FINDINGS: The cytopathology consisted of the formation of intranuclear globules, collapse of the involved nuclei, and the extrusion of nuclear materials. The relatively dormant primary human amnion cells were less susceptible than the rapidly growing cell lines. Similarly, the slowly multiplying ribose variants were less susceptible than their corresponding parent cell lines. Interferon-like activity was released from infected cells. Infectivity was readily demonstrated following storage at 0-4 degrees C for at least 8 months or at 37 degrees C for at least 2 weeks. Freeze-thawing, however, markedly reduced or completely destroyed its infectivity. Infectivity was destroyed completely by ether and chloroform; partially by desoxycholate, and not affected by trypsin, papain, RNAse, DNAse, hyaluronidase, lysozyme, lecithinase, or pancreatic lipase. The rate of inactivation by 0.025 per cent formalin was much slower than that of vaccinia and herpes viruses. Its synthesis was suppressed by 5-fluorodeoxyuridine. This suppression was not reversed by thymidine and/or uracil. Heat-stable neutralizing antibody could not be demonstrated in 379 human and animal serums, in human gamma globulins, or in serums from animals "immunized" with this agent. Heat-labile inhibitors (lipoprotein-like) capable of inhibiting the infectivity of this agent were demonstrated in 154 of the 157 serums tested. Experimental evidence indicated the non-identity of this ubiquitous inhibitor and the properdin system. The non-infectious complex between this agent and the ubiquitous serum inhibitor may be dissociated (hence, become infectious) by simple dilution. Repeated attempts to reisolate a similar agent have not been successful. We have hypothesized that this agent is a virus consisting of DNA wrapped in a surface coat rich in lipid, and suggest that this virus be referred to tentatively as a lipovirus.

Animals↗
PubMed1978

Experimental studies of the pathogenesis of Pseudomonas aeruginosa infection: evidence for the in-vivo production of a lethal toxin.

Evidence is presented that a lethal toxin is produced by P. aeruginosa growing in the burned skin of experimental mice. After injection of approximately 100 P. aeruginosa cells into the burned skin there was a rapid proliferation of organisms at the site of inoculation. When the organisms in the burned skin tissue reached a critical concentration, there was generalised toxaemia with subsequent mortality; the process was not reversible at this stage, even by reducing substantially the numbers of infecting organisms. However, when the reduction was accompanied by administration of rabbit serum prepared against filter-sterilised extracts of infected burned tissues, approximately 40% of the animals survived for at least 96 h. The data suggests that the antiserum afforded protection by inactivating a toxin produced by the organisms growing in the infected burned tissues rather than by further reducing the numbers of infecting organisms.

Animals↗
PubMed1979

Reinterpretation of the Dick test: role of group A streptococcal pyrogenic exotoxin.

Because of the association of the group A streptococcal pyrogenic exotoxins (SPEs) with erythrogenic toxin used in the classical Dick test, the involvement of the SPEs in production of erythematous skin reactions was assessed. Unless they had been presensitized, young adult rabbits failed to show skin reactions after intracutaneous challenged with SPEs. Rabbits presensitized to purified protein derivative exhibited enhanced skin reactivity when given purified protein derivative plus SPE C; the enhancement was neutralized by antiserum to SPE C. Rabbits sensitized to bovine serum albumin showed extensive red rash development resembling scarlet fever rashes when given bovine serum albumin containing SPE C. Desquamation occurred 5 to 10 days after injection. Animals sensitized to one SPE type showed enhanced skin reactivity to challenge with homologous or heterologous SPE types, indicating the presence of a cross-reactive determinant within the SPE molecules. Repeated challenge of SPE-sensitized animals with homologous toxin resulted in concomitant antitoxin production with reduction of the enhanced skin reactivities, until typical delayed-hypersensitivity skin reactions remained. The data indicate that, in addition to the toxic reaction previously described, SPEs enhance Arthus and delayed-hypersensitivity skin reactions. It follows that erythrogenic toxin represents the enhancement of acquired skin reactivity to streptococcal antigens by one or more SPE types. Therefore, the Dick test measures SPE-enhanced hypersensitivity to streptococcal products.

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