Promoter methylation and relative gene expression of O6-methyguanine-DNA-methyltransferase (MGMT) and p16 genes were examined in tissue and blood samples of patients with premalignant oral lesions (PMOLs) and oral squamous cell carcinoma (OSCC). Methylation-specific PCR and reverse transcriptase PCR were performed in 146 tissue and blood samples from controls and patients with PMOLs and OSCC. In PMOL group, significant promoter methylation of MGMT and p16 genes was observed in 59% (P = 0.0010) and 57% (P = 0.0016) of tissue samples, respectively, and 39% (P = 0.0135) and 33% (P = 0.0074) of blood samples, respectively. Promoter methylation of both genes was more frequent in patients with OSCC, that is, 76% (P = 0.0001) and 82% (P = 0.0001) in tissue and 57% (P = 0.0002) and 70% (P = 0.0001) in blood, respectively. Significant downregulation of MGMT and p16 mRNA expression was observed in both tissue and blood samples from patients with PMOLs and OSCC. Hypermethylation-induced transcriptional silencing of MGMT and p16 genes in both precancer and cancer suggests important role of these changes in progression of premalignant state to malignancy. Results support use of blood as potential surrogate to tissue samples for screening or diagnosing PMOLs and early OSCC.

: Present study demonstrates effect of metal ions and inhibitors on the activity of lipase, isolated from P.aeruginosa. Seven different concentrations (0.1mM -20mM) of twelve metal salts and two inhibitors, EDTA and SDS were studied for their effect on lipase. The results demonstrated that ten metal ions, namelyFe +2 andK + were not found to be significantly affecting the enzyme. The enzyme was also tested for two inhibitors, EDTA and SDS; both reduced the enzyme action and SDS showed complete inhibition at highest concentration, suggesting the dependence of enzyme on metal ions. Lipases, being one of the most extensively used industrial enzyme, a stable variant from a microbial source may be of immense potential.

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