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Biomedical subjects

R Prabhakar

Publications and source records attributed to R Prabhakar.

At least 91 records · Page 5Linked to original sources
PubMed1987

Virulence for guinea pigs of tubercle bacilli isolated from the sputum of participants in the BCG trial, Chingleput District, South India.

This study, conducted in Madras, India and in Madison, Wisconsin, USA, was concerned with the virulence of isolates of Mycobacterium tuberculosis obtained from the sputum of individuals living in the Chingleput district of south India. The following results were obtained. 1. The findings of Mitchison with respect to the predominance of low virulence for guinea pigs among isolates from persons living Madras, were confirmed on isolates from the sputum of residents of the Chingleput district. 2. A high correlation was found between the log10 number of tubercle bacilli recovered from the spleen of guinea pigs infected intramuscularly with 1.0 mg of tubercle bacilli and the root index of virulence. 3. A high correlation was found between the log10 number of tubercle bacilli recovered from the spleen of guinea pigs infected intramuscularly with 1.0 mg of tubercle bacilli and the number recovered from the spleen of guinea pigs infected by the respiratory route with 5-10 tubercle bacilli. 4. Relatively low correlations were found between RIV and the susceptibility of isolates to thiophene-2 carboxylic acid hydrazide or to hydrogen peroxide.

Animals↗
PubMed1986

Reduced lymphocyte response to mitogens in patients with Bancroftian filariasis.

Peripheral blood lymphocytes from patients with acute and chronic Wuchereria bancrofti infections responded poorly to concanavalin A, phytohaemagglutinin and pokeweed mitogen when cultured in heat-inactivated pooled normal serum. The lymphocyte response to mitogens in carriers of microfilariae (mff) were normal. The suppression of transformation to mitogens was not reversible by the removal of plastic adherent cells. Incubation with mitogens and the adult filarial worm antigen (BmA) did not alter the mitogen response either in control subjects or in filarial patients. The possible mechanism of immunosuppression is discussed.

Concanavalin A↗
PubMed1986

Three chemotherapy studies of tuberculous meningitis in children.

Chemotherapy studies were undertaken in 180 patients with tuberculous meningitis. They were treated for 12 months with 1 of 3 regimens: the first consisted of streptomycin, isoniazid and rifampicin daily for the first 2 months, followed by ethambutol plus isoniazid for 10 months; in the second, pyrazinamide was added for the first 2 months, and in the third, rifampicin was reduced to twice weekly in the first 2 months. Steroids were prescribed for all the patients in the initial weeks of treatment. Approximately 50% of the patients were aged less than 3 years. On admission, 13% of the patients were classified as stage I, 77% as stage II and 9% as stage III. Cerebrospinal fluid (CSF) culture results were available for all the 180 patients and M. tuberculosis was isolated in 59 (33%). CSF smear results for acid fast bacilli were available only for the 103 patients admitted to the second and the third studies, and of these in 60 (58%) the CSF was positive either by smear or culture. The response to therapy was similar in the 3 studies. Despite administration of rifampicin for 2 months, the mortality was high. In all, 27% of the patients died of tuberculous meningitis, 39% had neurological sequelae and 34% recovered completely. There was a strong association between the stage on admission and the mortality rate, the deaths being highest in stage III. In the first study, when isoniazid was prescribed daily in a dosage of 20 mg/kg, 39% of the patients developed jaundice; however, when the dosage was reduced to 12 mg/kg, the incidence fell to 16%. In the third study, where rifampicin was administered twice a week, the incidence of jaundice was much lower (5%).

Antitubercular Agents↗
PubMed1985

Species level identification of non-tuberculous mycobacteria from South Indian BCG trial area during 1981.

In 1981, non-tuberculous mycobacteria (NTM) were obtained from 8.6% of 16 907 sputum specimens in a trial in the Chingleput district of Madras state to test the efficacy of BCG vaccination in the prevention of tuberculosis, but from only 0.6% of 672 autoclaved specimens cultured as part of a quality control procedure. This finding suggested that the NTM were truly derived from the sputum of the BCG trial subjects. The mycobacterial species could be identified in 966 (96.6%) of the first 1000 isolates of NTM: 54.6% were potential pathogens and 73.0% were slow growing. The species isolated most frequently were M. avium/intracellulare (22.6% of all NTM), M. terrae (12.5%) and M. scrofulaceum (10.5%). Those species accounting for 8-5% of all NTM were M. fortuitum, M. chelonei, M. flavescens, M. gordonae and M. vaccae.

BCG Vaccine↗
PubMed1983

Effect of storage of sputum specimens at room temperature on smear and culture results.

A study of 41 specimens of sputum stored for up to 28 days at room temperature in a tropical country showed that smear results were not affected by storage, the positivity being 83% before storage and 80-83% after. The culture positivity was 88% before storage, and 83%, 68%, 22%, 13% and 0% after 3, 7, 14, 21 and 28 days of storage respectively. The reduction in positivity on storage attains significance at 7 days (P = 0.05). Another study involved 163 specimens of sputum and storage for 3, 5 or 7 days. Each specimen was examined before storage and after 2 periods of storage, at random. The smear results were again not affected. There was, however, significant loss of viability, the proportion culture positive being reduced from 92% before storage to 83% at 3 days (P = 0.05), 71% at 5 days (P less than 0.01) and 63% at 7 days (P less than 0.001). The contamination rate was 5%, 7%, 12% and 18% respectively. It is concluded that sputum should not be stored at room temperature for longer than 3 days for culture but it can be stored for 4 weeks without any loss of smear-positivity.

Bacteriological Techniques↗
PubMed1983

Observations on the culture of M. leprae in Medium V. A preliminary report.

This paper reports the preliminary findings of an investigation using Medium V for culture of M. leprae. The medium was prepared adhering to the procedures adopted by Veeraraghavan. Tissues from 7 cases of lepromatous leprosy (Bacteriological Index of 3 or more) were inoculated into Medium V and incubated at 8-10 degrees C for 72 hours. Quantitative estimation of leprosy bacilli were made employing the enumeration technique of Veeraraghavan. There was no evidence of multiplication in any of the cultures. The findings are in conformity with those of Kato (1983) and of Katoch and Desikan (1983).

Culture Media↗
PubMed1976

Study of adverse reactions to a once-weekly regimen of streptomycin plus a slow-release preparation of isoniazid in high dosage for six months.

A once-weekly regimen of streptomycin (1 g) plus a slow-release preparation of isoniazid (matrix isoniazid) in high dosage, namely 50 mg/kg body-weight for rapid inactivators of isoniazid and 35 mg/kg for slow inactivators, was prescribed for 6 months to 64 tuberculous patients (27 rapid, 37 slow). The regimen was tolerated by most the of the patients. However, 4 rapid and 3 slow inactivators had a modification of the regimen, mainly for giddiness. There were no cases of peripheral neuropathy. No adverse effects on haemopoiesis or hepatic or renal functions were observed in any of the patients. It is concluded that it is feasible to administer matrix isoniazid in dosages considerably higher than ordinary isoniazid, in once-weekly chemotherapy.

Adolescent↗
PubMedDate not supplied

Short course chemotherapy for tuberculous lymphadenitis in children.

OBJECTIVE: To assess the efficacy of a short course chemotherapy regimen for treating tuberculosis of the lymph nodes in children. DESIGN: Open, collaborative, outpatient clinical trial. SETTING: Outpatient department of the Tuberculosis Research Centre, paediatric surgery departments of the Institute of Child Health and Hospital for Children and the Government Stanley Hospital, Madras, South India. PATIENTS: Children aged 1-12 years with extensive, multiple site, superficial tuberculous lymphadenitis confirmed by biopsy (histopathology or culture). INTERVENTIONS: Patients were treated with a fully supervised intermittent chemotherapy regimen consisting of streptomycin, rifampicin, isoniazid, and pyrazinamide three times a week for two months followed by streptomycin and isoniazid twice a week for four months on an outpatient basis. Surgery was limited to biopsy of nodes for diagnosis and assessment. MAIN OUTCOME MEASURES: Response to chemotherapy was assessed by regression of lymph nodes and healing of sinuses and abscesses during treatment and follow up. Compliance with treatment and frequency of adverse reactions were also estimated. RESULTS: 197 Patients were admitted to the study and 168 into the analysis. The regimen was well tolerated and compliance was good with 101 (60%) patients receiving the prescribed chemotherapy within 15 days of the stipulated period of six months. Those whose chemotherapy extended beyond that period received the same total number of doses. Clinical response was favourable in most patients at the end of treatment. Sinuses and abscesses healed rapidly. Residual lymphadenopathy (exceeding 10 mm diameter) was present in 50 (30%) patients at the end of treatment; these nodes were biopsied. Fresh nodes, increase in size of nodes, and sinuses and abscesses occurred both during treatment and follow up. After 36 months of follow up after treatment only 5 (3%) patients required retreatment for tuberculosis. CONCLUSION: Tuberculous lymphadenitis in children can be successfully treated with a short course chemotherapy regimen of six months.

Antitubercular Agents↗
PubMedDate not supplied

Observations on the cultivation of M. leprae and M. tuberculosis in medium 'V' and 'V 1'.

Skin scrapings from five different active sites were collected from 14 leprosy patients and inoculated into medium V. Skin scrapings from three leprosy patients were inoculated into medium V 1. All the cultures were incubated at 8-10 degrees C. M. tuberculosis H37Rv, pretreatment isolates and streptomycin resistant strains were inoculated into medium V, with and without antibiotics, and incubated at 8-10 degrees C as well as 37 degrees C. Smears were made from the M. leprae and M. tuberculosis cultures at 0 hours and at different time points. The number of bacilli in the smears were counted. There was no increase in the number of M. leprae or M. tuberculosis in any of the cultures.

Culture Media↗