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V M Katoch

Publications and source records attributed to V M Katoch.

At least 73 records · Page 4Linked to original sources
PubMed1990

Lymphocyte arginase activity in leprosy--a preliminary report.

Arginase activity was estimated in serum and lymphocytes of 22 healthy controls and 50 untreated leprosy patients across the spectrum. The patients included 21 lepromatous/borderline lepromatous (LL/BL); 20 borderline borderline/borderline tuberculoid (BB/BT) and 9 tuberculoid (TT) cases. Mean serum arginase levels were 1.51 +/- 0.43, 1.41 +/- 0.43, 1.24 +/- 0.43 and 1.10 +/- 0.026 mu moles/min/ml in LL/BL, BB/BT and TT patients and healthy controls respectively. The lymphocyte arginase activity showed a similar increasing trend from TT to LL/BL. The mean lymphocyte arginase levels were 0.87 +/- 0.31 mu moles/min/10(6) cells in healthy controls and 1.81 +/- 0.40, 2.54 +/- 0.60 and 5.48 +/- 0.56 mu moles/min/10(6) cells in TT, BB/BT and LL/BL patients respectively. The increasing trend specially in lymphocyte arginase levels across the spectrum of leprosy correlated with the degree of impairment in the protective cell mediated immune response and also the extent of disease. The role of these pathophysiological alterations in relation to defect in immune response calls for investigation.

Arginase↗
PubMed1989

Studies on ribosomal RNA genes of mycobacteria including M. leprae.

Information about specific genes specially of pathogenic mycobacteria could be used to unequivocally identify isolates of mycobacteria which are of clinical interest. Both eukaryotic and prokaryotic ribosomal RNA (rRNA) genes have been shown to comprise sequences which are conserved and others which are divergent. In the present study, rRNA genes from several cultivable mycobacteria including M. tuberculosis and armadillo derived M. leprae have been investigated. rRNA was isolated, made radioactive in vitro and then used to identify restriction fragments of DNA containing rRNA gene sequences. It was observed that restriction endonuclease patterns of rRNA genes are characteristic. By probing with homologous and heterologous rRNA probes, fragments hybridizing maximum with homologous probes could be identified and it appears that sequences flanking the rRNA genes are not identical. These fragments need to be further sequenced to identify the nucleotide sequences specific to rRNA gene cluster. It would also be necessary to analyse several isolates of each species including armadillo derived M. leprae before reaching any conclusions.

Genes, Bacterial↗
PubMed1989

Effect of chemotherapy on viability of Mycobacterium leprae as determined by ATP content, morphological index and FDA-EB fluorescent staining.

Viable bacterial populations were estimated in bacilli purified from 105 biopsies from 40 untreated and 65 multibacillary leprosy patients treated with multidrug therapy (MDT) for varying periods. The bacilli were purified and viability was determined by ATP content, morphological index (MI), and fluorescein diacetate-ethidium bromide (FDA-EB) staining. Viable populations were calculated, taking 3.58 x 10(-15) g/solid bacillus as the mean ATP content of a viable unit of Mycobacterium leprae. The proportion of viable bacilli was also estimated in the same specimens using solid-staining (MI) and green-staining bacilli by the FDA-EB method. In the untreated cases, the positive viability by ATP assay was 100%, 92% by MI, and 100% by FDA-EB. ATP content per solid bacillus was relatively constant, which was not the case with ATP content per green-staining bacillus. While the MI was zero in all cases, viable bacilli could still be detected by ATP estimations in 5 of the 32 (16%) patients after 2 years of MDT and in 1 of the 20 (5%) patients after 3 years of MDT. No viable bacilli could be detected even by this method beyond 3 years of MDT. On the other hand, green-staining bacilli were demonstrable in 7/32 (22%) of cases after 2 years of MDT, 2/20 (10%) after 3 years of MDT, and 1/13 (8%) after more than 3 years of treatment, indicating that the FDA-EB staining and ATP assay did not detect the same populations. A determination of the ATP content of M. leprae could be used as a reliable and sensitive tool for determining viability of the bacilli.

Adenosine Triphosphate↗
PubMed1989

Immunotherapy of treated BL/LL cases with BCG: histopathological, immunohistological and bacteriological assessments.

The persistence of dead as well as viable bacteria is an important therapeutic problem in multibacillary leprosy. In highly bacillated patients, viable bacteria are detectable in 10-15% of cases after 2 years of treatment and none of these cases became smear negative by 2 years of recommended multidrug therapy (MTD). Immunotherapy trials using BCG (0.1 mg) by intradermal route have been undertaken in cases who had MDT for 2 years and who had viable bacilli by ATP photometry and/or FDA-EB staining. Biopsies and smears were taken from local as well as distant sites at 0.4 weeks and 6 months after BCG vaccination. Biopsies were processed for ATP counts, FDA-EB staining, histopathology and immunohistology for cell types at 0.4 weeks. There was transient effect on BI, ATP counts, FDA-EB staining at local as well as distant sites in some cases. Histopathology and immunohistological findings suggest that there is tendency to form epithelioid cell granuloma at local site in all cases and at distal sites in some. There was infiltration of subepidermal zone in one case, 4 weeks after vaccination. BCG may be of use as potential immunotherapeutic agent but its usefulness needs to be investigated in depth preferably in the beginning or early phases of chemotherapy and with also repeated inoculations.

BCG Vaccine↗
PubMed1989

Studies on energy synthesis in M. leprae.

ATP measurements have been earlier used to study the effect of various nutrients on the growth and multiplication of M. leprae. In a preliminary study, we had observed that glycerol and asparagine stimulated the ATP synthesis by M. leprae but this was marginal and not sustained. We have extended the study to investigate the role of various environmental factors which could affect this ATP synthesis. It has been observed that ATP synthesis was better and sustained for a longer period i.e. upto 2 weeks if the M. leprae were incubated at pH 6-6.5 and at 30-33 degrees C in the modified Dubos and Sauton's media. The pH and temperature above these values were suboptimal. It is concluded that temperature and pH are important factors for maintenance and synthesis of ATP by M. leprae.

Adenosine Triphosphate↗
PubMed1989

Results of a modified WHO regimen in highly bacilliferous BL/LL patients.

A regimen consisting of 600 mg of rifampin once a month, 100 mg of clofazimine on alternate days, and 100 mg of dapsone daily was used in 56 untreated, highly bacillated borderline lepromatous/lepromatous (BL/LL) patients with an average bacterial index (BI) of 4.45. Treatment was continued until skin-smear negativity. After 2 years of therapy, none of the patients had become smear negative and the average BI was 2.56. There was no growth on inoculation of skin-tissue biopsies in the normal mouse foot pad after 6 months of therapy. Bacillemia was still detectable in 11/50 patients, and significant ATP levels were detected in Mycobacterium leprae from skin-tissue biopsies in 16% of the cases. After 3 years of therapy, three patients had become smear negative. The average BI was 1.30. None of the patients had detectable bacillemia, and 5% of the cases showed detectable ATP levels in M. leprae from tissue biopsies. After 4 years of therapy, 41.7% of the patients had become smear negative. The average BI was 0.66, and no ATP was detected in any of the purified bacillary suspensions. The fall in BI was accelerated, and more patients on continued treatment became negative earlier compared to those having treatment for a limited duration, as reported by others.

Adenosine Triphosphate↗
PubMed1989

Application of ATP assay for in vitro drug screening testing against human derived M. leprae.

In this study, the ATP content of M. leprae exposed to various antimicrobial agents has been measured to evaluate its usefulness in drug sensitivity screening. Purified M. leprae suspensions from human biopsies have been incubated at 30 degrees C in a modified Dubos medium in the presence of different concentrations of various drugs viz., Rifampicin, Ethionamide, Ethambutol, Cycloserine, Dapsone, Clofazimine, Erythromycin and Tetracycline. ATP levels were estimated at 0, 7 days, 14 days of incubation by the procedures modified and standardised at this laboratory. ATP decay was accelerated by ethionamide, rifampicin, clofazimine, dapsone, erythromycin and to a lesser extent by cycloserine, whereas ethambutol and tetracycline did not have any significant effect. The rate of decay depended on the concentrations of these drugs. ATP assay promises to be a useful system for in vitro drug sensitivity screening against M. leprae isolated from patients.

Adenosine Triphosphate↗
PubMed1987

Appearance of a methoxy mycolate-like component by the acid methanolysis of Mycobacterium leprae.

It has been reported that Mycobacterium leprae contains two types of mycolic acid, namely, alpha- and keto-mycolic acids, thus it is taxonomically similar to M. bovis BCG. However, there was some controversy about the presence of methoxy mycolic acid which was observed in small amounts only in the case of experimentally infected (W45) armadillo-derived M. leprae. To investigate this fact, mycolic acids were extracted from the cell-wall structure of M. leprae and characterized using chromatographic techniques. The results showed the appearance of a methoxy mycolate-like component for both purified bacilli and infected human skin tissue materials. However, this appearance occurred only when the acid methanolysis procedure was followed for the release of mycolic acids from these bacilli. No such component appeared on the chromatogram when the alkaline methanolysis procedure was followed. Nevertheless, the consistent presence of this methoxy mycolate-like component by acid methanolysis is an important finding which has to be kept in mind while identifying this pathogen when using chromatographic techniques.

Chromatography, Thin Layer↗
PubMed1986

Evidence for genetic divergence in ribosomal RNA genes in mycobacteria.

DNA was isolated from Mycobacterium phlei and from M. smegmatis. Each DNA sample was restricted with endonucleases, the fragments were separated by agarose gel electrophoresis and transferred to nitrocellulose film. Fragments of DNA containing rRNA sequences were identified by means of 125I-labelled rRNA of M. phlei or of M. smegmatis. The distributions of restriction endonuclease sites within the rRNA gene(s) and flanking sequences were found to be characteristic for each of the two species. Hybridizations with heterologous probes indicate that although M. phlei rRNA and M. smegmatis rRNA share regions of sequence homology, they are probably not identical in primary structure. The results suggest that the rRNA genes might prove to be useful taxonomic markers for mycobacteria.

Biological Evolution↗
PubMed1986

Step-wise isolation of RNA and DNA from mycobacteria.

Mycobacterium phlei and M. smegmatis were lysed at -15 degrees C in the presence of guanidinium salts and poly(A)+-RNA. Nonpolyadenylated RNA (mainly rRNA) and DNA were isolated in successive steps from the same lysate. DNA isolated by this procedure was sufficient to yield distinct bands on treatment with restriction endonucleases as shown by hybridization to 125I-labeled rRNA. The successive isolation of poly(A)+-RNA, nonpolyadenylated RNA, and high molecular weight DNA from the same lysate by this procedure, which is being reported for the first time, provides a very economical approach for isolation and purification of nucleic acids from mycobacteria and other organisms. This could be of special value for various genetic recombination studies, particularly in the case of mycobacteria which are available in very limited quantities, e.g., noncultivable or difficult-to-grow mycobacteria, especially M. leprae.

DNA, Bacterial↗
PubMed1985

Comparative study on the thin-layer chromatographic pattern of methyl mycolates of M. leprae and related species.

The thin-layer chromatographic (TLC) pattern of methyl mycolates of Mycobacterium leprae has been compared with the lipids extracted from M. leprae-infected tissue material and also with those of other cultivable mycobacterial species. It has been found that M. leprae-derived methyl mycolates give two spots, namely, alpha- and keto-derivatives, after charring the TLC plates with K2Cr2O7/H2SO4 spray. Lipids extracted from infected tissue material also show spots with the same Rf values when compared with those of armadillo-derived M. leprae. Normal skin tissue extracts, however, do not show any presence of mycolates. This TLC pattern of M. leprae-derived methyl mycolates is characteristic and is not shown by any other mycobacterial species isolated from leprosy lesions. The strain and species which have been earlier found to resemble M. leprae antigenically or biochemically could readily be distinguished with the help of the TLC pattern of their methyl mycolates.

Cell Wall↗
PubMed1984

Lactate dehydrogenase in Mycobacterium leprae grown in armadillo liver.

Lactate dehydrogenase (LDH) was detected in extracts of untreated and NaOH-treated Mycobacterium leprae. Since armadillo liver LDH isoenzymes with a similar electrophoretic mobility were shown to be considerably more sensitive to inhibition by oxamate than LDH in M. leprae extracts, it was confirmed that M. leprae grown in armadillo liver has its own LDH. Neither the activity of LDH in M. leprae nor its electrophoretic mobility supported the tentative suggestion that an "anomolous" LDH isoenzyme in infected skin biopsies was in fact an M. leprae-derived enzyme.

Animals↗
PubMed1983

Effect of pyridine extraction on the acid fastness of mycobacteria.

The effect of pyridine extraction on mycobacterial acid-fastness has been studied using M. leprae and some cultivable mycobacteria. The results revealed that not only M. leprae but some other mycobacteria, notably, M. vaccae and M. phlei also lose their acid-fastness when extracted with fresh pyridine for 2 hours at room temperature. The implication of these findings is discussed.

Humans↗
PubMed1983

Observations on the cultivation of M. leprae in medium 'V' (Veeraraghavan).

The medium 'V' has been evaluated for the in vitro growth of M. leprae. M. leprae were obtained from five untreated cases of multibacillary type of leprosy. Medium was prepared and inoculated by the method described by Veeraraghavan. Killed (Autoclaved) M. leprae from the same biopsies were kept as controls. Growth was monitored in a double blind manner at 60 hours, 120 hours of incubation at 8-10 degrees C of both primary and subcultures. Counting was done by both standard Shepard and McRae method as well as by Veeraraghavan's method. There was no evidence of any multiplication in any of the cases at 60 and 120 hours of incubation.

Cell Division↗