Lipid peroxidation product, malonaldehyde (MDA) and antioxidants were estimated in plasma and erythrocytes of 34 cases of oral submucous fibrosis (OSMF) of different grades with equal number of healthy controls to evaluate the association of reactive oxygen species (ROS) and OSMF. While plasma MDA was found to be significantly higher in patients (3.3±0.4 nmole/ml, P<0.001) as compared to controls (2.4±0.5 nmole/ml), plasma beta carotene and vitamin E levels were found to be decreased significantly in patients (81.7±14.3 μg/100 ml, P<0.001; 9.3±0.9 mg/L, P<0.01 respectively) with respect to healthy controls (110±20.8 μg/100 ml and 10.1±1.2 mg/L). The decrease in beta-carotene and vitamin E was found to be more significant in OSMF grade II and III than in grade I. After 6 weeks of oral administration of beta-carotene and vitamin E, patients showed increase in plasma level of these two antioxidants along with decrease in MDA level associated with clinical improvement.

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Tuberculosis (TB) is an ancient disease caused by Mycobacterium tuberculosis (MTB), which remains a major cause for morbidity and mortality in several developing countries. Most drug-resistant MTB clinical strains are resistant to isoniazid (INH), a first-line anti-TB drug. Mutation in KatG, a catalase-peroxidase, of MTB is reported to be a major cause of INH resistance. Normally upon activation by KatG, INH is converted to an active intermediate which has antimycobacterial action in MTB. This INH intermediate in the presence of NADH forms INH-NAD adduct which inhibits inhA (2-trans-enoyl-acyl carrier protein reductase) of MTB, thus blocking the synthesis of mycolic acid, a major lipid of the mycobacterial cell wall. In this docking study, the high binding affinity of INH-NAD adduct towards InhA was observed in comparison with INH alone. In this study, two resistant mutants of KatG (S315T and S315N) were modeled using Modeller9v10 and docking analysis with INH was performed using AutoDock4.2 and the docking results of these mutants were compared with the wild type KatG. Docking results revealed the formation of a single hydrogen (H) bond between the secondary amine nitrogen (-NH) of INH with Thr or Asn residues in place of Serine at 315 position of KatG mutant strains respectively, whereas in the case of the wild type, there was no H-bond formation observed between INH and Ser315. The H-bond formation may prevent free radical formation by KatG in mutant strains thus the development of resistance to the drug. This in silico evidence may implicate the basis of INH resistance in KatG mutant strains.

Tuberculosis is still a major health problem in most developing countdes and its incidence is rising in many developed countries. This resurgence has been attributed to the HIV epidemic and TB has been declared as a global health emergency by WHO in 1993. The diagnosis of tuberculosis mainly depends upon initial clinical suspicion and radiographic findings with subsequent bacteriological confirmation by sputum smear examination and culture. Lack of sensitivity in smear examination, non specificity of radiological findings, extended turn around time of Mycobactedum tuberculosis culture and difficulties in diagnosing paucibacillary, childhood and extrapulmonary tuberculosis has necessitated to explore the utility of immunodiagnosis of tuberculosis as a convenient and cost effective test to supplement clinical information for definite diagnosis. Many commercial tests are available in the market for diagnosis of TB. Most of these tests are based on the detection of IgG, IgA and IgM antibodies to specific mycobacterial antigen or mixture of antigens. Indigenous immunoassay systems have explored excretory-secretory ES-31 mycobactedal antigen for immunodiagnosis of'lB. Many a time there is lack of consistent elevation in all the three Ig classes in active infection thus making it more important to determine the ideal antibody isotype assay for reliable diagnosis of tuberculosis and to save the costs of the patient for unnecessary investigations.

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