Molecular analysis of isoniazid-resistant clinical isolates of Mycobacterium tuberculosis from India

The presence of mutations in specific regions of katG, inhA, oxyR–ahpC and kasA associated with isoniazid (INH)-resistant clinical isolates of Mycobacterium tuberculosis from India were analysed by DNA sequencing. Point mutations in the katG gene at codon 315 and a mutation at codon 138 were detected in 64.3% (45/70) and 4% (1/25) of isolates, respectively. Polymorphisms at codon 463 of the katG gene were found both in resistant and sensitive isolates. Mutation at the inhA and oxyR–ahpC promoter regions occurred in 11.4% (8/70) and 35.0% (14/40) of the isolates, respectively. No mutation was found to occur in kasA and inhA structural gene regions. Of the 70 resistant isolates studied, 55 (78.6%) showed mutation in the regions sequenced. This is the first comprehensive molecular analysis of INH resistance in India, which suggests that point mutation rather than deletion and insertion is the major cause of INH resistance

Effect of oral exposure of mycobacterium avium intracellulare on the protective imunity induced by BCG

The relative protective efficacy of oral administration of mycobacteria as compared to the conventional intradermal route of vaccination has been assessed in guinea pigs. Skin test reactivity to partially purified protein derivative and protective immunity to challenge with virulent Mycobacterium tuberculosis were used as parameters of protective immunity. Oral immunisation of guinea pigs either with BCG or with Mycobacterium avium intracellulare induces skin test reactivity and protective immunity comparable to that induced by intradermal route of vaccination. Oral exposure of Mycobacterium avium intracellulare prior to oral or intradermal dose of BCG did not interfere with the protective immunity induced by BCG in guinea pigs challenged with Mycobacterium tuberculosis H37Rv

CMI response of tuberculosis patients and volunteers to mitogens and mycobacterial antigens by LTT

Various mechanisms have been proposed in the past to explain the inability of the body’s cell mediated immunity (CMI) to cope with the infecting organism in myco bacterial disease such as leprosy. They include short lived suppressor cells, n-2 (IL2) defect and Prostaglandin mediated suppression1,2,3. In leprosy hanisms have been studied using the lymphocyte transformation test (LTT) to elucidate CMI in vitro. The present study was designed to study the regulation of CMI in tuberculosis patients and normal individuals with regard to induction, expression, inhibition and modulation due to prior exposure to environmental mycobacteria

COMPARATIVE EVALUATION OF ANTIOXIDANT ACTIVITY OF SUBSTITUTED FLAVONES

  Objective: The flavonoids are a heterogeneous group of plant polyphenols that are endowed with several biological activities including antioxidant, anti-inflammatory, immunomodulatory, antiviral, antimutagenic, and anticarcinogenic properties. They are believed to interfere with the various free radical-producing systems and they also enhance the functions of endogenous antioxidants. The aim of this study was to compare the antioxidant activity of synthesized substituted flavones by various free radical scavenging assays.Methods: The flavones used in the study, 6,3',4' - trihydroxy flavones (THF) and 3-hydroxy-6,3'-dimethoxy flavones were synthesized using standard procedures and their antioxidant activity was compared by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, hydrogen peroxide scavenging assay, hydroxyl radical scavenging assay, reducing power capacity, superoxide free radical scavenging assay, and 2,2′-azino-bis-3-ethylbenzthiazoline-6- sulphonic acid assay.Results: In the DPPH assay, THF has an inhibitory concentration 50% value of 18.89 μg/ml which was much better than that of standard ascorbic acid which was 26.1 μg/ml. The THF had a much better antioxidant activity in most of the free radical scavenging assays.Conclusion: From the study, it can be seen that the flavones showed significant antioxidant activity that can be used for treatment of various disease

Sensitisation pattern of healthy volunteers and tuberculosis patients to various mycobacterial antigens by ELISA

The sensitisation pattern of 39 tuberculosis patients and 21 healthy volunteers to 9 different mycobacterial antigen sonicates was estimated using ELISA. The antibody levels of patients and volunteers were high against M. tuberculosis-7219, M. kanasii and M. scrofulaceurn and low against M. chelonei and M.fortuitum. The tuberculosis patients showed a mean antibody level which was significantly different from that of volunteers to M. tuber culosis-7219, M. kansasii, M. scrofulaceum, M. tuberculosis S.I., M. bovis and PPD-S. With respect to three antigens, namely, M. chelonei, M. fortuitum and M, avium intracellulare, there was no significant difference between patients and volunteers

Identification & differentiation of Mycobacterium avium & M. intracellulare by PCR- RFLP assay using the groES gene

Background & objectives: We report a new polymerase chain reaction (PCR) – restriction fragment length polymorphism (RFLP) assay using mycobacterial groES as a target to identify Mycobacterium avium and M. intracellulare in clinical samples. Methods: The assay was standardized using M. avium and M. intracellulare standard strains obtained from ATCC and was tested with 45 M. avium-M. intracellulare complex (MAC) clinical isolates (Of which 31 were from HIV+ individuals). The standard and clinical strains were typed with HPLC based mycolic acid fingerprinting. Results: Three polymorphisms (BamHI, BstNI and HgaI) were identified for inter-species differentiation among standard strains; of which, only HgaI was found to be useful in clinical isolates. Of the 45 isolates, 25 were M. avium and 20 were M. intracelluare. MAC isolates, which could not be differentiated by HPLC analysis, were also typed by this method. Interpretation & conclusions: The use of mycobacterial groES as a PCR-RFLP target for M. avium and M. intracellulare is a simple and rapid method that can complement HPLC in their differentiation