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Biomedical subjects

R Prabhakar

Publications and source records attributed to R Prabhakar.

At least 55 records · Page 3Linked to original sources
PubMed1995

Isolation of tubercle bacilli from sputum samples of patients in the field studies by the cetylpyridinium chloride-sodium chloride & sodium hydroxide methods.

A total of 125 sputum specimens, collected in the field, were homogenised, aliquoted in sterile universal containers and randomly allocated to the cetylpyridinium chloride - sodium chloride (CPC-NaCl) method and sodium hydroxide (NaOH) method for culture of tubercle bacilli. After storage for 8 days at ambient temperature in the field laboratory at Thiruvallur, the aliquots were transported to the main laboratory at Madras where they were processed for culture by the respective methods. The yield of positive cultures in the CPC-NaCl (31/125) method was only marginally better than that in the NaOH method (27/125) (95% CI being-3.4 to 9.8%), while the contamination of cultures was significantly less in the CPC-NaCl method (3/125) than in the NaOH method (12/125) (95% CI being 2.2 to 12.2%). As the CPC-NaCl method has advantages over the NaOH method in reducing contamination, in augmenting the yield of positive cultures and also in its simplicity, it can be applied in field studies.

Bacteriological Techniques↗
PubMed1995

Vancomycin for controlling contamination of selective Kirchner's liquid medium in the culture of gastric lavage for tubercle bacilli.

Gastric lavage (GL) was collected for culture of tubercle bacilli from children too young to expectorate sputum. The selective Kirchner's liquid medium (SKLM), routinely used as one of the media for culture of all extrapulmonary specimens, was found to often get contaminated when cultured with GL. We have shown that vancomycin at a concentration of 10 mg/l successfully reduced the contamination from about 60 to 20 per cent, and enhanced the isolation rate of tubercle bacilli from 3 to 6 per cent. Decontamination of the liquid culture before subculture on solid medium also helped to reduce the contamination rate. Vancomycin was found to be an effective selective drug for use in the Kirchner's liquid medium for culture of tubercle bacilli.

Bacteriological Techniques↗
PubMed1995

A direct rifampicin sensitivity test for tubercle bacilli.

A direct sensitivity test for rifampicin has been standardised for early detection of resistance for the mycobacterium tuberculosis smear positive sputum samples. Indirect sensitivity tests set up from primary cultures of the same samples served as controls. The direct test showed 95 per cent agreement with the standard indirect test and as such 74 per cent and 90 per cent of the resistant strains were detected by the fourth week and fifth week, respectively, with an overall gain of 4-5 wks time. Resistance could be detected earlier for multibacillary specimens. This direct sensitivity test on Lowenstein Jensen (LJ) medium offers a feasible alternative for laboratories which lack facilities to perform drug susceptibility tests by the rapid but sophisticated and costly BACTEC method. The method is simple to perform, economic, reliable and amenable to confirmation by the indirect test, if needed.

Drug Resistance, Microbial↗
PubMed1995

Distribution of HLA (class I and class II) antigens in the native Dravidian Hindus of Tamil Nadu, south India.

HLA - A, B, C, DR, DQ antigen profile of South Indian Tamil-speaking Hindus of Dravidian descent was studied. Phenotype, gene and haplotype frequencies were calculated and compared with the literature. There was a complete lack of A23, A25 and A32 antigens in the sample presently monitored. Except for minor differences (higher incidence of Cw6 and DR10 antigens), the Dravidian Hindus show similarity to North Indio-Aryan and other Hindu samples. The haplotypes A1, B17; A2, B5; A2, B51; A1, DR7; B12, DR7; B13, DR2; B17, DR7; DR2, DQ1; DR3, DQ2; DR4, DQ3; DR5, DQ3; DR7, DQ2; DR11, DQ3; show significant positive linkage disequilibrium whereas A1, DR2; DR2, DQ2; DR7, DQ1 were significant for negative linkage disequilibrium in the Dravidian Hindus.

Ethnicity↗
PubMed1994

Evaluation of procedures for isolation of nontuberculous mycobacteria from soil and water.

Six methods of decontamination each for the isolation of mycobacteria from soil and water were compared. On the basis of the results obtained, three of the six methods for soil and two of the six methods for water were further evaluated. For both soil and water samples, the method using 3% sodium lauryl sulfate in combination with 1% NaOH yielded more positives than the other methods.

Journal Article↗
PubMed1994

Isolation and Identification of Environmental Mycobacteria in the Mycobacterium bovis BCG Trial Area of South India.

The isolation profiles of environmental mycobacteria present in soil, water, and dust samples, and sputum samples of persons with symptoms of chest infection in the South Indian Mycobacterium bovis BCG (bacillus Calmette-Guérin) trial area were compared. Isolates belonging to the Mycobacterium avium-intracellulare-scrofulaceum complex were predominant in water, dust, and sputum samples and Mycobacterium fortuitum-complex organisms were predominant in soil samples irrespective of the season of the year.

Journal Article↗
PubMed1994

Procoagulant activity of bronchoalveolar lavage fluids taken from the site of tuberculous lesions.

We wanted to determine the procoagulant activity (PCA) of bronchoalveolar lavage fluids, in order to understand the macrophage-mediated lung injury at the site of tuberculous lesion. Alveolar lavage fluids taken from the site of a lesion (radiologically abnormal site (RAS)) and an unaffected site (radiologically normal site (RNS)) of active pulmonary tuberculosis (TB) patients (n = 7) and inactive (cured) patients (n = 9) were studied for their PCA producing potential. The observed results were not significant using Mann-Whitney test, and thus all increases/decreases reported below are trends/tendencies only. An increased PCA was seen in 4 out of 7 cell-free lavage supernatants of active-TB taken from the site of lesion (RAS), compared to only 1 out of 9 in inactive-TB. The PCA producing potential of the alveolar macrophages of RAS and RNS of active-TB patients was enhanced when the alveolar macrophages were co-cultured with autologous peripheral blood lymphocytes under in vitro condition. Stimulation with purified protein derivative (PPD) of M. tuberculosis showed a variable (increased or decreased) PCA production. Peripheral blood monocytes and total mononuclear cells (monocytes+lymphocytes) of active-TB patients stimulated with or without PPD showed increased PCA production, compared with normal individuals and inactive-TB patients. The present study suggests that increased production of PCA by the alveolar macrophages, in collaboration with lymphocytes and other cells at the site of tuberculous lesions will result in fibrin formation. The deposition of fibrin in the alveoli may lead to further lung injury.

Blood Coagulation↗
PubMed1994

Expression of proto-oncogenes, genes for muscle specific isoforms and heat shock protein (HSP) -70 gene in hypertrophied cardiac muscles from patients with atrial septal defect or tetralogy of Fallot.

Studies on the expression of proto-oncogenes and muscle specific genes in hypertrophied human hearts have shown that proto-oncogenes such as c-myc, c-fos and c-ras are activated in both atrial and ventricular tissues of patients with atrial septal defect (ASD) and tetralogy of Fallot (TOF). Although the expression of muscle specific genes such as MLC2 and skeletal alpha-actin are induced the expression of tissue specific cardiac actin remained the same in both the control and diseased tissues. Further, an increased synthesis of messengers of heat shock protein gene-HSP70 was observed in the ventricular tissues of TOF patients, with out much of a change in atrial tissues of patients with ASD.

Actins↗
PubMed1994

Early bactericidal action of pulsed exposure to rifampicin, ethambutol, isoniazid & pyrazinamide in pulmonary tuberculosis patients.

The bactericidal action of two therapeutic regimens on Mycobacterium tuberculosis was assessed by viable counts in serial sputum samples in 49 pulmonary tuberculosis patients being treated with rifampicin (R), ethambutol (Emb), isoniazid (I) and pyrazinamide (Z) together in a single dose thrice weekly (REmbIZ3) or with REmb and IZ on alternate days (REmb3IZ3alt). In both groups of patients, there was a significant reduction (P < or = 0.02) in the colony forming units (cfu) of M. tuberculosis per ml of sputum during the first two days of treatment itself. This early bactericidal action (EBA) as well as the reduction in counts during the subsequent days of treatment were similar (P > 0.2) for both REmbIZ3 and REmb3IZ3alt regimens indicating that splitting up REmbIZ into REmb on one day and IZ on the next day in short course chemotherapy (SCC) regimens may not affect the bactericidal action of the regimens.

Antitubercular Agents↗
PubMed1994

Protective response in guinea pigs exposed to Mycobacterium aviumintracellulare/M. scrofulaceum, BCG & south Indian isolates of M. tuberculosis.

The protective immunity resulting from exposure to nontuberculous mycobacteria (NTM), BCG and virulent mycobacteria in different sequences was studied in the guinea pig model employing strains prevalent in the south Indian BCG trial area and time kinetics to observe the immuno-modulation. The findings suggest that during the early course of challenge infection in guinea pigs there was no interference with the immunity due to BCG, by prior exposure to NTM. In the animals sensitised with M. avium intracellulare before immunisation, the challenge infection was localised and confined to the site of inoculation, and only a few organisms reached the spleen. However, at the later stages of the infection, as seen by the spleen viable counts at 12 wk, it appeared that the barrier at the localised site of infection may not be intact in the animals with prior exposure to NTM, and a few organisms disseminate to the spleen.

Animals↗
PubMed1993

Serum protein of 135-kDa molecular weight--a molecular signal for cardiac hypertrophy.

A serum protein, similar to the 135-kDa protein which appears during experimentally induced cardiac hypertrophy in rats, was identified in human serum by Western blot analysis using anti-rat 135-kDa protein antibody. The rat protein antibody gave a very strong positive signal when reacted with sera obtained from cardiac patients, suggesting an induced level of this protein in patients' sera when compared to normal sera from healthy individuals. Multiple injections of polyclonal anti-rat 135-kDa protein antibody to aorta-constricted animals completely inhibited the development of cardiac hypertrophy, suggesting that this protein could be hypertrophy specific. This was further substantiated by the decrease in the expression of a molecular marker such as the beta myosin heavy chain gene in aorta-constricted but antibody-injected animals. Further, the presence of high levels of this protein in first- and third-day neonatal animals is also suggestive of the hypertrophy-specific nature of this protein as the heart is subjected to high pressure overload immediately after birth.

Animals↗
PubMed1993

Critical assessment of smear-positive pulmonary tuberculosis patients after chemotherapy under the district tuberculosis programme.

This is a status report of a retrospectively assembled cohort of 3357 smear-positive patients initiated on anti-tuberculosis chemotherapy in the North Arcot district between April 1986 and March 1988. The patients were contacted once at their homes between November 1988 and June 1989 (6 and 36 months after start of treatment), and information on their status, including death, could be obtained from 76% of them. Regimens were selected by the patients. 2306 (69%) had accepted short course regimens (SCC) and 1051 (31%) had been started on standard chemotherapy (non-SCC), 43% and 35% in SCC and non-SCC respectively had completed 80% or more of their treatment. Overall mortality was 28%. Of those remaining, 31% had active disease and were excreting bacilli, among which 65% of the cultures were resistant to isoniazid and 12% to rifampicin. Combined resistance to isoniazid and rifampicin was seen in 4% and to isoniazid and streptomycin was seen in 19%. A significant finding was that even among those who had taken less than 50% of their treatment, 56% were bacteriologically negative. However, inadequate or irregular chemotherapy resulted in over four times the mortality and about twice the rate of smear positivity as compared with those taking adequate chemotherapy. No comparisons are made between patients on short-course and standard regimens as the patients selected their treatment and the groups are not comparable.

Adolescent↗
PubMed1993

Bacteriological investigations for short-course chemotherapy under the tuberculosis programme in two districts of India.

To examine the bacteriological profile and the prevalence of drug resistance among patients attending the health facilities where the District Tuberculosis Programme (DTP) was in operation with short-course chemotherapy (SCC) regimens, sputum specimens were collected on admission and the end of treatment in North Arcot district and Pondicherry region. In North Arcot district, rifampicin, isoniazid and pyrazinamide were given twice weekly for the first 2 months followed by rifampicin and isoniazid twice a week for the next 4 months under fully supervised administration. In Pondicherry, rifampicin, isoniazid and pyrazinamide were given daily for the first 2 months followed by rifampicin and isoniazid twice weekly for the next 4 months. Of the patients who had received 80% or more of the drugs, 80% from North Arcot and 92% from Pondicherry were rendered culture-negative for Mycobacterium tuberculosis at the end of treatment. Even among patients with initially resistant bacilli, a high proportion had a favourable response. Before start of treatment, of the 2779 patients from North Arcot, 25% had resistance to one or more drugs including 2% with resistance to rifampicin. In Pondicherry, 13% of the patients had initial resistance to one or more drugs. Initial resistance to rifampicin was observed in 0.9%. None of the initially drug-sensitive patients had acquired resistance to rifampicin at the end of treatment.

Adolescent↗
PubMed1993

Monocyte antimycobacterial activity before and after Mycobacterium bovis BCG vaccination in Chingleput, India, and London, United Kingdom.

Monocytes from purified protein derivative S Mantoux-negative children and young adults inhibited intracellular growth of Mycobacterium microti more in Chingleput than in London. Mycobacterium bovis BCG vaccination did not enhance bacteriostasis with the Indians but did so with the Londoners. No evidence was found for involvement of cytokines such as macrophage-activating factor and granulocyte macrophage colony-stimulating factor in the differences.

BCG Vaccine↗
PubMed1993

Bactericidal action of pulsed exposure to rifampicin, ethambutol, isoniazid & pyrazinamide on Mycobacterium tuberculosis in vitro.

The bactericidal action of pulsed exposure to rifampicin (R), ethambutol (Emb), isoniazid (I) and pyrazinamide (Z) together on alternate days (REmbIZ) and as REmb and IZ separately on alternate days (REmb/IZ) on M.tuberculosis H37Rv, two isolates of M.tuberculosis sensitive to these drugs, as well as four isolates resistant to one or more drugs, was studied using an in vitro method. The experimental duration was 6 days. REmbIZ and REmb/IZ appeared to have equally good bactericidal action on M.tuberculosis strains in the in vitro system. The results suggest that splitting REmbIZ into REmb and IZ on alternate days in short course chemotherapy regimens for tuberculosis may not affect the bactericidal action of the regimens.

Antitubercular Agents↗
PubMed1992

Defaults, defaulter action and retrieval of patients during studies on tuberculous meningitis in children.

Chemotherapy studies were undertaken on 180 children, aged between 1 and 12 years, with tuberculous meningitis. They received therapy for 12 months. As approximately one-half of the patients came from outside Madras city, retrieval action was not possible in all cases of default. Despite this, a high rate of compliance and punctuality was achieved as a result of initial and periodic motivation. This report highlights the role and importance of motivation in the prevention of default and the retrieval of defaulters during the treatment of children with tuberculous meningitis.

Antitubercular Agents↗
PubMed1992

Pulmonary eosinophilia in pulmonary tuberculosis.

Three radiologically and bacteriologically confirmed pulmonary tuberculosis patients had eosinophilic pneumonia, as demonstrated by BAL. In two patients, pulmonary eosinophilia was present only at the site of the lesion and the third had eosinophilia in both peripheral blood and lung. There was complete elimination of the eosinophilic inflammatory process in two patients who had successfully completed antituberculosis treatment.

Adult↗