• Mahtab S Bamji

      Articles written in Journal of Biosciences

    • In vitro effects of gossypol on testicular lactic dehydrogenase-X and other dehydrogenases

      N Giridharan Mahtab S Bamji M N Madhyastha

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      Thein vitro inhibition of several rat testis dehydrogenases by gossyPol was examined. Inclusion of the coenzyme (substrate for NADP+-isocitrate dehydrogenase) in the Preincubation mixture containing the enzyme and gossyPol, Protected the enzymes against inhibition by gossyPol. Lactic dehydrogenase-X was amongst the least Protected enzymes. This, couPled with its lowKi for gossyPol makes it one of the most vulnerable target enzymesin vivo for gossyPol action.

      The inhibition kinetics for lactic dehydrogenase-X were comPetitive when NADH was Present during Preincubation, but non-comPetitive when the coenzyme was excluded during Preincubation. In the latter condition, the enzyme seems to undergo Progressive inactivation with time causing a nonreversible tyPe of inhibition.

    • Effects of ovulen-50, diethylnitrosamine and phenobarbital on liver regeneration in female rats

      V V Annapurna M A Mukundan B Sesikeran Mahtab S Bamji

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      Short term effects of ovulen-50, a combination type oral contraceptive agent and phenobarbital—an established hepatic tumour promoter, were examined in the livers of diethylnitrosamine-initiated and uninitiated female rats. Liver mitotic activity as judged by liver weight, [3H] thymidine incorporation into DNA and levels of DNA, RNA and protein were measured in non-regenerating and regenerating liver. Hepatic γ-glutamyl transpeptidase activity and hepatocyte agglutination with concanavalin A were examined in diethylnitrosamine- and/or phenobarbital-treated rats.

      The results indicate that diethylnitrosamine or ovulen-50 individually are mitoinhibitory in regenerating liver. Phenobarbital alone has a slight mitostimulatory effects in non-regenerating liver, but no effect on liver regeneration. Administration of ovulen-50 and phenobarbital to diethylnitrosamine initiated rats mitigated the mitoinhibition during regeneration. Contrary to the earlier observation with ovulen-50, neither phenobarbital nor diethylnitrosamine induced hepatocyte agglutination in the presence of concanavalin A. Like ovulen-50, diethylnitrosamine also increased the level of hepatic γ-glutamyl transpeptidase. Phenobarbital produced only insignificant rise and did not substantially exacerbate the effect diethylnitrosamine.

      The data show that though some of the effects of ovulen-50 resemble those of diethylnitrosamine or phenobarbital, the changes observed may not be related to the neoplastic phenomenon since they were not seen in an initiator-promoter combination regimen.

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