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Biomedical subjects

S P Halbert

Publications and source records attributed to S P Halbert.

At least 55 records · Page 3Linked to original sources
PubMed1971

In vitro organization of dissociated rat cardiac cells into beating three-dimensional structures.

When isolated beating ventricular heart cells from newborn rats were grown in tissue culture on untreated polystyrene surfaces, they showed a striking tendency to grow focally in three dimensions from the single layer cell sheets which were formed early in growth. During this process, they frequently formed miniature spherical heart-like masses, which continued to beat and grow in size. These often were somewhat lobulated in appearance, and grew up to 2 mm in diameter. Histological sections of such structures sometimes revealed evidence of appreciable orientation of the cells to each other, in fiber-like units. Electron microscope sections of such mini-hearts showed structures resembling intercalated discs between myocardial cells. The precise factors which induced the cardiac cells to apparently organize into these heart-like structures are not presently known.

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PubMed1970

The toxicity of streptolysin O for beating mammalian heart cells in tissue culture.

Pulsating mammalian myocardial cells were found to be highly susceptible in tissue culture to rapid destruction by streptolysin O. Cessation of beating occurred almost immediately, followed within minutes by multiple cell membrane bleb formation. Parallel with these changes, the cytoplasm became intensely granular and the nuclear membrane apparently thickened when viewed by phase microscopy. At the ultrastructural level, the cell membrane blebs were found to contain relatively small numbers of granular fragments. The endoplasmic reticulum of damaged heart cells was quite swollen, and its contents were considerably condensed. The myofibers were not strikingly altered, but cytoplasmic and mitochondria vacuoles were rather abundant. Cardiac endothelial, kidney epithelial, and fibroblast cells were also susceptible to lysis by this toxin, but the reactions occurred more slowly or bleb formation was less evident. An antiserotonin drug known to be protective against streptolysin-O in vivo (UML-491), did not protect against killing of cardiac cells at the tissue culture level. Serotonin could not be detected in the culture fluid after lysis of cardiac cells by streptolysin O.

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PubMed1968

Cardiac autoantibodies. I. Immunodiffusion analysis of multiple responses evoked homologously and heterologously.

1. A high proportion of rabbits immunized with pooled rabbit heart homogenates in complete Freund's adjuvant responded with the production of multiple precipitating antibodies to soluble rabbit heart antigens. The most potent antisera revealed at least five distinct antigens. 2. Rabbit anti-rabbit heart antibodies reacted with similar antigens in other mammalian hearts, (human, rat, guinea pig, and bovine) with apparent "reactions of identity" by immunodiffusion. 3. Rabbits immunized with human, rat, or guinea pig heart homogenates also responded with multiple precipitating antibodies directed against rabbit cardiac antigens, although somewhat less intensively than animals immunized homologously. The specificities of these antibodies appeared to be the same as those evoked homologously. 4. The autoantibody nature of the homologously and heterologously induced responses was unequivocally demonstrated in several instances by reactions between the sera from immunized rabbits and their own hearts. 5. Many of the autoantibodies appeared to be directed against antigens restricted to the heart, judging by comparative immunodiffusion tests with other rabbit tissue extracts. This was convincingly confirmed by multiple absorption of potent antisera with several rabbit tissues. The cardiac-restricted antigens were also present in heart extracts of other mammalian species. In those instances where some of the cardiac-evoked autoantibodies reacted with other rabbit tissues, the tissue cross-reactions were quite variable. 6. Rabbits immunized with guinea pig heart homogenate suffered a high early mortality of undetermined cause, compared to animals immunized with rabbit, human, or rat hearts. 7. A small proportion of the anti-heart sera revealed immunodiffusion reactions with Group A streptococcal products, derived from organisms grown in antigen-free media. In these few instances, the reactions appeared unrelated to cardiac autoantibody responses.

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