[Clinical significance of the activity of nitric oxide synthase in patients with leptospirosis].

Endotoxin-induced activation of inducible nitric oxide (NO) synthase (iNOS) becomes one of the triggers of the systemic response syndrome (SIRS). Determination of the activity of iNOS reflects the level of NO accumulation and may serve as a prognostically significant test of the severity of a pathological process. A procedure for determining the monocytic activity of iNOS has been developed on the basis of a histochemical reaction to NADPH-diaphorase. iNOS activity was determined in a group of healthy individuals and in 17 patients with leptospirosis. iNOS activity was decreased or absent (mean 0.56 +/- 0.085 c.u.) in patients with a very severe course of the disease and in those with protracted early convalescence. The increased activity of iNOS during early convalescence testifies to the incompleteness of an infectious process.