Biomedical subjects

J J HAHN

Publications and source records attributed to J J HAHN.

4 recordsLinked to original sources

PubMed1963

STREPTOCOCCAL M ANTIGEN LOCATION AND SYNTHESIS, STUDIED BY IMMUNOFLUORESCENCE.

Streptococcal M protein has been studied directly in the intact streptococcal cell by specific immunofluorescence. By this method, it can be seen to be concentrated in or on the cell wall, but cannot be detected in the capsule. The lack of type-specific (but not group-specific) immunofluorescence after trypsinization; and the inhibition of group-specific immunofluorescence by unlabeled type-specific antibody, are observations most compatible with a location of the M antigen determinants on the cell surface superficial to the group antigen. M antigen is not "resynthesized" after trypsinization of living cells, but appears anew only at sites of new cell wall growth. A limited amount of such growth, leading sometimes to detectable amounts of M in the gross, can take place in deficient media without detectable increases in optical density of the cell population.

Animals↗

PubMed1963

Studiey on the mechanism of the long chain phenomenon of group A streptococci.

The formation and destruction of long chains by growth of Group A streptococci in the presence of type-specific antibody have been studied with the fluorescent antibody technique. Long chain formation has been shown to depend on the presence of free antibody during the growth of the bacteria. Destruction of long chains has been shown to depend on the continued growth and division of the bacteria in the absence of free antibody. Univalent antibody fragments formed by proteolytic digestion of antibody globulin have been shown to have the combining properties of untreated antibody but do not result in the production of long chains. A model involving end-to-end agglutination during growth of Group A streptococci has been presented to explain the mechanism of production of long chains by growth of Group A streptococci in the presence of type-specific antibody.

Antibodies↗

PubMed1962

Cell wall replication in Streptococcus pyogenes.

Group A streptococci (Streptococcus pyogenes) of several different serological types were grown in fluorescein-labeled homologous type or group-specific globulins, thereby labeling the antigen-containing cell walls. Specific precipitation or inhibition of the labeled antibody, followed by continued incubation and examination at intervals by ultraviolet, phase, and dark-field microscopy, showed that new cell wall was then nonfluorescent. These nonfluorescent portions were differentiated by a reverse technique of culture in unlabeled globulin, followed by antibody precipitation, further growth, and fluorescent-antibody staining. This technique of differential labeling of cell wall has permitted following, for the first time in a living system, the fate of cell wall formed at different times. The results suggest that cell wall synthesis in actively growing cultures usually occurs simultaneously at at least two sites per coccus, each site representing stages in successive divisions, and that cell wall growth in Streptococcus pyogenes is not by diffuse intercalation with old wall, but is initiated at and extends both peripherally and centripetally from the coccal equator.

Cell Division↗

PubMed1962

Time and concentration relationships in the long-chain reaction of group A streptococci in homologous antiserum and an improved method for evaluation of test results.

Hahn, Jerome J. (National Institutes of Health, Bethesda, Md.) and Roger M. Cole. Time and concentration relationships in the long-chain reaction of group A streptococci in homologous antiserum and an improved method for evaluation of test results. J. Bacteriol. 83:85-96. 1962-We have described a statistically controlled method for evaluating the long chain reaction of group A streptococci grown in homologous antisera. The method is based on the chi-square analysis of the frequency distribution of chain lengths found in test and control sera, and is called the Size-Class Frequency method. Useful tables for rapid application of the method are presented. It is reproducible, and is simpler, more rapid, and more sensitive than the previously described method. Using this method, we have shown that the long-chain reaction reaches a maximum and then declines with time of incubation. The time at which the maximal response and height are attained depends directly on the initial antibody concentration and inversely on the initial antigen concentration. The inter-relationships of time, antibody concentration, total number of cocci, total number of chains, and long-chain frequency (or chain length) are presented in the discussion.In view of the findings reported here, we suggest a re-evaluation of possible methods of "dechaining" or "chaining" among group A streptococci. Present evidence appears inadequate to explain the long-chain reaction on the basis of inhibition of a single enzyme.

Humans↗