Pranav Vyas

Differential anti-inflammatory effects of immunosuppressive drugs: Cyclosporin, rapamycin and FK-506 on inducible nitric oxide synthase, nitric oxide, cyclooxygenase-2 and PGE2 production

Abstract.Objective and Design: Cyclosporin, FK-506 and rapamycin have similar but distinct modes of interaction with cyclophilins, calcineurins and transcription factors. These immunosuppressive drugs have also been shown to inhibit cytotoxic and inflammatory responses in macrophage. Therefore, we evaluated the mechanism of action of these drugs on iNOS and COX-2 expression by macrophages, the products of which (NO and PGE2) have cytotoxic and pro-inflammatory activities.¶Materials and Methods: The murine macrophage cell line RAW 264.7 was grown as monolayer cultures. The effects of pharmacologically relevant concentrations of cyclosporin, rapamycin and FK-506 were evaluated in the presence and absence of lipopolysaccharide (LPS) which is a known inducer of iNOS and COX-2. Subsequently the expression of iNOS and COX-2 were analyzed by Western and Northern analysis. The production of NO and PGE2 were assayed by Greiss and RIA respectively.¶Results: Cyclosporin (1-5 μg/ml) and rapamycin (1.0-10 nM) but not FK-506 (5-10 nM) inhibited both iNOS and COX-2 expression at mRNA level which led to significant inhibition of NO and PGE2 production.¶Conclusion: These studies characterize differential mechanistic capacity of the immunophilin-binding immunosuppressive drugs (comparable to hydrocortisone) to inhibit both iNOS and COX-2 expression. Inhibition of iNOS and COX-2 mRNA accumulation by cyclosporin and rapamycin seem to be distinct. These studies also highlight potential anti-inflammatory properties of these drugs in addition to their known immunosuppressive activity.¶

Production of chitinase and its optimization from a novel isolate Alcaligenes xylosoxydans: potential in antifungal biocontrol

A novel, highly chitinolytic strain of Alcaligenes xylosoxydans was isolated which showed potential for use as an antifungal biocontrol agent for the control of two fungal plant pathogens. It could degrade and utilize dead mycelia of Rhizoctonia bataticola and Fusarium sp. (fungal plant pathogens of Cajanus cajan). In vitro it could inhibit the growth of Fusarium sp. and R. bataticola. Chitin at 10–15 g/l was found to be good carbon and nitrogen source. Alcaligenes xylosoxydans showed optimum chitinase production at 72 h, pH optima at 8 and growth peak at 120 h. Yeast extract, arabinose, Tween 20 and several other surfactants enhanced chitinase production.

Multiple-Stress Tolerance of Ionizing Radiation-Resistant Bacterial Isolates Obtained from Various Habitats: Correlation Between Stresses

Isolation of five ionizing radiation (IR)-resistant bacteria by screening of isolates from various habitats classified as common and stressed is reported. IR-resistant isolates exhibited varying degrees of resistance to γ-radiation and were classified as highly and moderately radiation resistant. Resistance to ultraviolet (UV) radiation correlated well with γ-radiation resistance, whereas a comparable desiccation resistance for all the highly and moderately radiation-resistant isolates was observed. However, salt tolerance failed to correlate with IR resistance, indicating a divergent evolution of the salt tolerance and radiation resistance. Characterization of isolates by the amplified rDNA restriction analysis profiling attested to the clustering of these isolates with their stress phenotype. 16S rRNA gene-based analysis of the isolates showed that the bacteria with similar-resistance physiologies clustered together and belonged to related genera. Hydrogen peroxide resistance and mitomycin survival patterns of the isolates indicated the roles of oxidative-stress tolerance in desiccation survival and recombination repair in higher radiation resistance, respectively.

The novel method for isolating chitinolytic bacteria and its application in screening for hyperchitinase producing mutant of Alcaligenes xylosoxydans

Aims: To develop a novel, rapid and effective screening method for chitinase producing bacteria.