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Biomedical subjects

G V Kadival

Publications and source records attributed to G V Kadival.

17 recordsLinked to original sources
PubMed1994

Detection of antibodies to defined M. tuberculosis antigen (38 kDa) in cerebrospinal fluids of patients with tuberculous meningitis.

Antibodies to the 38 kDa antigen of M. tuberculosis which is serospecific to the tuberculosis complex group of organisms was studied in CSF samples of patients with tuberculosis meningitis. Patients were classified into four groups, viz. post-mortem-proved, culture-proved, clinically suspected and tuberculoma. Anti-38 kDa antibody was detected by ELISA and was positive in 60%, 80% 62.5% and 0%, respectively in the four groups. Controls showed a false-positive detection of 5%. Follow-up of patients was done up to 6 weeks and antibody levels dropped in all the patient groups.

Antibodies, Bacterial↗
PubMed1994

Use of the recombinant 38-kDa antigen of Mycobacterium tuberculosis as an immunogen for specific antisera production.

The Mycobacterium tuberculosis 38-kDa protein antigen is one of the secreted immunodominant antigens showing high immunogenicity at B-cell and T-cell levels. Although monoclonal antibodies to this antigen have been produced, specific polyclonal antisera is required for standardization of specific immunodiagnostic assays. This protein has been overexpressed and purified from recombinant Escherichia coli using an inducible vector system. During each stage of expression and purification, the recombinant protein was used to immunize mice and rabbits by several methods: 1) as overexpressed protein present as inclusion bodies in recombinant E. coli; 2) embedded in a polyacrylamide gel; 3) fixed to a solid-phase nitrocellulose membrane and 4) emulsified with an adjuvant. All strategies yielded specific antisera as determined by enzyme-linked immunosorbent assay (ELISA) and immunoblot analyses. The results obtained, both quantitative (ELISA) and qualitative (immunoblot) demonstrate that the purified recombinant antigen retains its antigenicity and immunogenicity throughout the various steps in the process of expression and purification and serves as a potent antigen for production of specific antisera to be used in immunoassays.

Animals↗
PubMed1992

Radioimmunoscintigraphic approach for the in vivo detection of tuberculomas--a preliminary study in a rabbit model.

Radioimmunoscintigraphic approach could provide a viable non-invasive alternative for the diagnosis of deeply situated tuberculomas. We have evaluated this in a rabbit model constructed to give a characteristic localized tubercular lesion, with complimentary morphological, histological and antigenic profiles. 131I-anti Myobacterium bovis (BCG) antibody was shown to localize at the lesion, where as 131I-bovine serum albumin and 99mTc-red blood cell scans were negative. The clearance of intradermally-injected tuberculous antigen could be traced into ascending lymph nodes using 131I-anti M. bovis (BCG) antibody.

Animals↗
PubMed1992

A study of tubercular antigen and antibody in childhood tuberculosis.

A radioimmunoassay for the detection of tubercular (TB) antigen (Ag) and antitubercular antibody (Ab) was evaluated for the serodiagnosis of childhood tuberculosis. Children with primary complex, progressive primary complex, miliary tuberculosis, and calcified lung lesions without clinical evidence of active tuberculosis were studied. Significantly elevated levels of TB Ag and TB Ab isolated from the circulating immune complexes were obtained in primary, progressive primary, and miliary tuberculosis patients as compared to controls (P less than 0.01). The majority of patients with calcified lung lesions and without active tuberculosis demonstrated high levels of antibody. It was observed that elevated levels of TB Ag and/or antibodies were present in 54 per cent of patients with primary complex, 94 per cent of patients with progressive disease and 69 per cent of patients with miliary tuberculosis. It is possible that is suspected patients with the above mentioned diseases, a diagnosis can be established by using these techniques.

Antibodies, Bacterial↗
PubMed1987

Characterization of serologic and cell-mediated reactivity of a 38-kDa antigen isolated from Mycobacterium tuberculosis.

An antigen of Mycobacterium tuberculosis with an m.w. of 38,000 has been isolated by affinity chromatography using a monoclonal antibody. This antibody bound only to an antigen found in M. tuberculosis and Mycobacterium bovis BCG. The specificity of the antigen was tested in a vertical study by immunodetection on western blots reacted with hyperimmune sera against M. tuberculosis, M. bovis, and 10 other Mycobacterium species. The antigen was detected only by antisera to M. tuberculosis and M. bovis. Specificity in cell-mediated immunity was tested by skin tests in guinea pigs sensitized with M. tuberculosis, Mycobacterium intracellulare, and Mycobacterium kansasii and by lymphocyte proliferation tests. The 38-kDa antigen induced positive skin test reactions regardless of the Mycobacterium species used to sensitize the animal. The ability of the 38-kDa antigen to sensitize for cell-mediated immunity was tested by injecting mice with the 38-kDa antigen and challenging their lymphocytes in vitro with various mycobacterial antigens. Lymphocyte proliferation was observed in the presence of 38-kDa antigen, M. tuberculosis sonicate antigen, and tuberculin purified protein derivative and to M. kansasii and M. intracellulare. The 38-kDa antigen may contain a specific epitope detected by serology, but also contains epitopes that are cross-reactive for cellular immunity.

Animals↗
PubMed1987

Radioimmunoassay for detecting Mycobacterium tuberculosis antigen in cerebrospinal fluids of patients with tuberculous meningitis.

A biotin-avidin radioimmunoassay for detecting Mycobacterium tuberculosis antigen has been developed. The assay involves sandwiching mycobacterial antigens from sonicate preparations and cerebrospinal fluids between two antibodies produced in burros and rabbits. The reaction is amplified by using biotinylated antibody to rabbit IgG and 125I-labeled avidin. The assay has a sensitivity of 20 ng/ml and shows less than 5% cross-reactivity with six other mycobacteria. We studied patients with untreated tuberculous meningitis, patients with treated tuberculous meningitis, patients with nonbacterial meningitis, and patients with bacterial meningitis. Antigen was detectable in two of 56 control samples (40 ng/ml). Hence, samples with greater than or equal to 80 ng of antigen/ml were considered positive. In patients with untreated tuberculous meningitis, antigen levels ranged from 20 to 10,000 ng/ml, and 15 (79%) of 19 samples were positive. In the treated group, only two (10%) of 17 samples were positive. This test promises to be a rapid adjunct in the early diagnosis of tuberculous meningitis.

Antigens, Bacterial↗
PubMed1987

Production, characterization, and species specificity of five monoclonal antibodies to Mycobacterium tuberculosis.

The production and characterization of five monoclonal antibodies to Mycobacterium tuberculosis are described. Specificity of the monoclonal antibodies was tested against other mycobacterial species by an enzyme-linked immunosorbent assay and immunoblots. HGT 3a, an immunoglobulin M (IgM) antibody, recognizes a molecule of 38,000 molecular weight present only in the tuberculosis complex of M. tuberculosis and Mycobacterium bovis BCG. HGT 6, an IgG1 antibody, recognized two molecules with molecular weights of 43,000 and 45,000 and showed limited cross-reactivity. Three other antibodies, HGT 1, HGT 2, and HGT 4, all belonging to the IgG1 type, recognized multiple bands and showed broad reactivity among all mycobacterial antigens tested, Escherichia coli and Nocardia asteroides.

Animals↗
PubMed1986

Sensitivity and specificity of enzyme-linked immunosorbent assay in the detection of antigen in tuberculous meningitis cerebrospinal fluids.

A sandwich enzyme-linked immunosorbent assay was developed for its potential utility in the detection of antigen in the cerebrospinal fluid of patients with tuberculous meningitis. Cerebrospinal fluids examined included those from untreated (group Ia) and treated (group Ib) Mycobacterium tuberculosis meningitis, nonseptic central nervous conditions (group II) such as epilepsy, viral meningitis, and tetany, and nonmycobacterial septic meningitis (group III). The average levels of antigens determined and percent positive specimens, respectively, for each group were (group): Ia, 1.8 micrograms/ml and 75% positive; Ib, 0.37 microgram/ml and 36% positive; II, 0.036 microgram/ml and 100% negative; and III, 0.075 microgram/ml and 100% negative. The system developed employed hyperimmune polyclonal antibody raised against M. tuberculosis and Mycobacterium bovis BCG in burros and rabbits. Cross-reactivity by other mycobacterial species was very low; e.g., 5% for M. kansasii and less than 2% for M. intracellulare, M. avium, M. vaccae, and M. fortuitum. The test shows promise as a specific adjunct for the early diagnosis of tuberculous meningitis.

Antigens, Bacterial↗
PubMed1976

Adrenocorticosteroids and corticosteroid binding globulins in protein calorie malnutrition.

A study of adrenocorticosteroids and corticosteroid binding globulins was undertaken in 35 malnourished children with a weight deficit of 10 to 45%. The mean corticosteroid levels 5.9 +/- 3.0 mug% were not significantly different from control values of 6.43 +/- 3.2 mug%. Steroid levels were however low (4.38 +/- 1.8 mug%) in children with marasmic kwashiorkor. The corticosteroid binding globulin was reduced to 11.9 +/- 5.4 mug of cortisol bound in malnourished children with and without edema and was significantly lower than controls. "Free cortisol" levels were significantly raised in the malnourished state. In the presence of acute infection there was a remarkable rise of steroids suggesting that there was no hypofunction of the adrenal cortex. Where the infection was chronic (e.g., pulmonary tuberculosis) the levels were normal suggesting an adaptation to the stress. Early studies of the steroids and corticosteroid binding globulins within 2 to 3 weeks of starting a high protein diet showed that there was a remarkable rise of serum albumin 2.3 +/- 0.4 to 3.3 +/- 0.7 g%, steroids from 5.9 +/- 5.5 to 12.3 +/- 7.4 and corticosteroid binding globulins from 13.0 +/- 4.1 to 20.2 +/- 6.3 mug of cortisol bound per 100 ml. Weight gain was from 0.2 to 1.0 kg. A follow-up of four children for 6 weeks showed that the steroid levels fell to within normal limits. The integrity of the hypothalamohypophyseal adrenal axis was unimpaired in five out of six children studied. In conclusion it appears that marasmic children are well adapted to the stress of malnutrition and the ability of the adrenals to respond to stress is unimpaired.

Adrenal Cortex↗