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Biomedical subjects

R S Kamat

Publications and source records attributed to R S Kamat.

32 records · Page 2Linked to original sources
PubMed1985

Polymorphism of a mycobacterial antigen participating in cell-mediated immunity.

The cross-reactivity of crude sonic extracts of six species of mycobacteria was studied by skin tests in mice and guinea pigs immunised with live Mycobacterium tuberculosis strain H37Rv, and in patients with pulmonary tuberculosis. All slowly growing mycobacteria elicited a strong delayed hypersensitivity response, M. vaccae a moderate response and M. phlei a poor or no response. A specific target antigen for cell-mediated immunity, known to be present in M. tuberculosis, was also present in all the mycobacteria studied. This shared antigen was shown, by immunoprecipitation tests, to be identical in all the slowly growing species but only a partial reaction of identity was obtained with M. phlei. It is concluded that the antigen shared by the slowly growing mycobacteria is immunodominant in cell-mediated immunity.

Animals↗
PubMed1984

Characterisation of target antigen of cell-mediated immunity in Mycobacterium tuberculosis H37RV.

Antigen participating in cell-mediated immunity was isolated from a sonic extract of Mycobacterium tuberculosis H37Rv. The purified antigen had a mol. wt 150 000-200 000, based upon its Rf in 7.5% polyacrylamide gel in the presence of sodium dodecyl sulphate. In simple agarose gel electrophoresis it had an Rf of 0.85. The protein in its native state was identified in the sonic extract with an antiserum to the purified antigen; it too had an Rf of 0.85 in agarose gel electrophoresis. The purified antigen elicited a delayed hypersensitivity response and stimulated the generation of activated macrophages in mice immunised with M. tuberculosis H37Rv.

Animals↗
PubMed1983

Role of heat labile antigens of Shigella flexneri in HeLa cell invasion.

In studies of the role of surface antigens of Shigella flexneri in HeLa cell invasion, three antisera were employed to block the invasion. Antisera against live (ALS) and boiled (ABS) S. flexneri blocked invasion very effectively. Reduction in the numbers of intracellular shigellae was always accompanied by reduction in the number adherent to the cells, indicating the importance of adhesion in the invasive process. Anti-live absorbed antiserum (ALAS) prepared by exhaustive absorption of ALS with boiled S. flexneri blocked adhesion and invasion at dilutions of 20 or 50; the efficiency of the absorption was indicated by absence of agglutinating and anti-lipopolysaccharide (LPS) antibodies. S. flexneri LPS did not block adhesion and invasion even at a concentration of 1.0 mg/ml. Hence it was concluded that heat-labile surface antigens are important in adhesion and invasion of HeLa cells by S. flexneri. Antiserum against heat stable antigen (ABS) probably blocks adhesion by steric hindrance.

Antigens, Bacterial↗
PubMed1982

Role of bacterial adhesion in the pathogenesis of cholera.

In studies with the adult-rabbit ileal-loop model, antibodies to the lipopolysaccharide somatic-antigen component of Vibrio cholerae gave passive protection against challenge with live V. cholerae. The antisomatic antibodies had no effect on bacterial proliferation and toxin production either in vivo or in vitro; after challenge, antibody-protected and non-protected rabbit ileal loops developed almost identical amounts of cholera toxin and numbers of V. Cholerae. The protection could be correlated only with a 10-15-fold reduction in the number of V. cholerae adherent to the mucous membrane of the antibody-protected loops. The amount of cholera toxin in the two sets of loops ranged from 1600 to 3200 units. In contrast, when biologically active cholera toxin was prepared in vitro, the amount required to induce ileal-loop secretion was very large (25,600 units). These findings indicate that toxin production by adherent vibrios on the surface of the mucous membrane is an important factor in the pathogenesis of cholera.

Animals↗
PubMed1982

Role of somatic antigen of Vibrio cholerae in adhesion to intestinal mucosa.

The in-vitro adhesion of Vibrio cholerae to intestinal mucous membrane was studied in isolated adult-rabbit ileal loops. Antisomatic antiserum Against V. cholerae Inaba could inhibit adhesion of three different strains of V. cholerae Inaba but had no effect on the adhesion of two different strains of enterotoxigenic NAG vibrios. The antiserum's bacterial agglutinin titre was 320, its anti-Inaba lipopolysaccharide (LPS) titre was 16 000 and its anti-flagellar antibody titre was 3200. Conversely, anti-live V. Cholerae Inaba antiserum absorbed with boiled cells of Inaba and devoid of antisomatic antibody, could not inhibit adhesion of the same three strains of V. cholerae Inaba. This antiserum had no anti-LPS or bacterial agglutinin activity, but its anti-flagellar antibody titre was 32 000. Thus, ability to inhibit adhesion of V. cholerae could be correlated only with antisomatic (anti-LPS) antibody activity. Antisomatic antiserum had no activity against 'adhesion', a V. cholerae surface antigen described by Freter. Conversely anti-live V. cholerae antiserum absorbed with boiled cells showed anti-adhesion activity even at a dilution of 1 in 200. LPS preparations from V. cholerae strain 569B Inaba could inhibit adhesion of two different Inaba strains to the intestinal mucous membrane. It is concluded that the somatic antigen plays a major role in the adhesion of V. cholerae to the intestinal mucous membrane.

Animals↗
PubMed1982

Effector cell-mediated immune response in mice immunised with Salmonella.

Effector responses of cell-mediated immunity were studied in mice immediately and 3 months after immunisation with different kinds of salmonella vaccine. Whereas immunisation with live Salmonella enteritidis generated delayed hypersensitivity and activated macrophages, immunisation with formalised vaccine generated neither. Although activated macrophages had declined considerably by 3 months after immunisation, the delayed-hypersensitivity response had persisted. It was possible to generate activated macrophages in these mice by stimulation with sonicate antigens of the immunising strain or Salmonella paratyphic C. Delayed-hypersensitivity responses were elicited in mice, immunised with live S. enteritidis, by sonicate antigens of the homologous strains, S. gallinarum or S. paratyphi C.

Animals↗
PubMedDate not supplied

Etiologic spectrum of acute sporadic viral hepatitis in children in India.

The relative magnitude by hepatitis A virus (HAV), hepatitis B virus (HBV) and hepatitis Non-A, Non-B virus (HNANBV) was determined in 496 children from three different parts of India suffering from acute viral hepatitis by tests for specific IgM class anti-HAV and anti-HBV antibodies in the serum. HAV, HBV and NANB infections accounted for 55.8 per cent, 20.2 per cent and 23.2 per cent of cases respectively. Hepatitis A largely (59.5%) affected younger children of 1-5 yr. Nearly a third of children affected by NANB hepatitis were additionally positive for HBsAg. The proportions of HAV and HBV infected cases respectively decreased and increased with increasing age whereas the incidence of HNANBV infection remained almost constant throughout childhood. Acute NANB hepatitis, a major health problem in the adults of India is also common throughout childhood. This study suggests that this infection does not impart long lasting protective immunity.

Adolescent↗