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Results for “TOXINS AND ANTITOXINS”

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At least 1,135 records · Page 63Linked to original sources
PubMed1983

Conjunctival immunity: compared effects of ocular or intestinal immunization in rats.

The ability to induce a conjunctival antitoxin response by conjunctival or enteric administration of cholera toxin antigen was studied in rats. Repeated enteric immunization caused a vigorous jejunal antitoxin response, but none in the conjunctiva. Enteric immunization did, however, prime for a conjunctival antitoxin response to locally applied antigen, as did direct ocular administration of cholera toxin. Vigorous conjunctival antitoxin responses occurred only after ocular challenge, and were localized to the challenged eye. These results agree with the notions that (1) specific memory cells migrate to the conjunctiva after enteric immunization, or arise locally after ocular immunization; and (2) specific antibody-producing plasma cells arise almost entirely within the immunized conjunctiva, and few if any migrate to the conjunctiva from distant mucosae or from the conjunctiva of the immunized eye to that of the nonimmunized eye.

Animals↗
PubMed1963

SIALIDASE (NEURAMINIDASE) OF CORYNEBACTERIUM DIPHTHERIAE.

Warren, Leonard (National Institute of Arthritis and Metabolic Diseases, Bethesda, Md.) and C. W. Spearing. Sialidase (neuraminidase) of Corynebacterium diphtheriae. J. Bacteriol. 86:950-955. 1963.-The characteristics of a sialidase produced by Corynebacterium diphtheriae were studied. The enzyme was partially purified from preparations of diphtheria toxin on a column of Sephadex G-75. By this means the lethal factor of diphtheria toxin was separated, in part, from the sialidase activity. There appeared to be a close immunological relationship between the sialidases of C. diphtheriae and clostridia, since a preparation of diphtheria antitoxin was as effective an inhibitor of diphtheria sialidase as of the sialidase of three species of clostridia. Conversely, antitoxin to clostridia inhibited diphtheria sialidase. Diphtheria antitoxin was essentially inactive toward influenza virus sialidase, and was completely inactive against purified sialidase of Vibrio cholerae. Removal of sialic acid from the proteins in a preparation of diphtheria antitoxin did not alter the inhibitory activity of the antitoxin against diphtheria sialidase. The enzyme operated optimally at pH 5.5 and did not require calcium ions for activity. The substrate specificity of diphtheria sialidase appears to be the same as that of other previously described sialidases.

Corynebacterium diphtheriae↗
PubMed1983

Induction of a novel morphological response in Chinese hamster ovary cells by pertussis toxin.

Exposing Chinese hamster ovary cells in culture to pertussis toxin resulted in a novel clustered growth pattern. The specificity of the response for pertussis toxin was shown by neutralization of the activity with specific anti-toxin antibody, heat lability (80 degrees C for 15 min), and absence of such activity by culture media from nontoxigenic Bordetella species. Although a lag of at least 16 h was required before clustered growth was seen, exposure to the toxin for as little as 10 min resulted in a full response 24 h later. The morphological effect appeared to be independent of the cyclic AMP-mediated cell elongation elicited by the heat-labile enterotoxin from Vibrio cholerae in that the pertussis toxin effect was seen in both the presence and absence of elongation. Although the mechanism by which this effect is mediated remains to be determined, it is already providing a useful in vitro assay for pertussis toxin.

Animals↗
PubMedDate not supplied

Cardiac effects of botulinal toxin.

Crystalline type A botulinal toxin rapidly caused temporary bradycardia and electrocardiographic (ECG) changes in mice, rats, rabbits and dogs. In addition, in the dog the force of contraction was measured and found to be depressed. The ECG changes were indicative of conduction defects. The hemagglutinin present in the toxin played no role in the effects on the heart, since a derivative toxin without hemagglutinin also caused these phenomena. The cardiac effects were spontaneously reversible in the intact animal without removal of the toxin. On the other hand, in the in vitro isolated heart of the rat, recovery from the cardiac effects occurred only after the toxin was washed out of the preparation. The findings are consistent with, but do not prove, a physical rather than a chemical mechanism for the effects of toxin on the heart.

Animals↗