Nature and biological significance of free radicals generated during bicarbonate hemodialysis.

This study investigates evidence of oxidative stress during bicarbonate hemodialysis by measuring total glutathione and lipid peroxidation products in plasma, and characterizes the free radicals produced by neutrophils from healthy volunteers when incubated in vitro with increasing concentrations of bicarbonate. Blood samples were taken from nine hemodialysis patients before and after two hemodialysis sessions. Plasma hydroperoxides and total glutathione were measured.

Production of nitric oxide and superoxide by activated macrophages and killing of Leishmania major.

Murine macrophages can be activated to produce nitric oxide (NO) and superoxide and these two radicals can react to form peroxynitrite, a powerful oxidant which may be involved in parasite killing. We now show that murine macrophages activated with zymosan and interferon-gamma (ZYM/IFN-gamma) produced both superoxide (peaking 1-2 h after stimulation, then rapidly declining) and NO (barely detectable at 6 h, peaking by 24 h). Macrophages activated with ZYM alone produced only superoxide, while stimulation with lipopolysaccharide (LPS) and IFN-gamma induced NO but not superoxide.

Effect of cigarette smoking on cultured human endothelial cells.

Objective: The aim was to investigate whether the morphological changes previously described in endothelium exposed to cigarette smoke are linked with the oxidative burden imposed on the cells.

Methods: Cultured human umbilical vein endothelial cells (HUVEC) were exposed to samples of plasma taken from volunteer smokers and to samples of plasma to which small doses of fresh cigarette smoke derived from a smoking machine had been added. Measurements of the pentose phosphate pathway and the extruded total glutathione (GSSG) were performed to assess the presence and degree of oxidative stress on cells.

Reaction of nitric oxide with hydrogen peroxide to produce potentially cytotoxic singlet oxygen as a model for nitric oxide-mediated killing.

Nitric oxide, as well as being a major regulator of vascular reactivity, has been shown to be one of the mediators of cytotoxicity in macrophages. This cytotoxic effect seems to be due to the interaction between nitric oxide and oxygen-related free radicals. This study shows that, in vitro, nitric oxide reacts with hydrogen peroxide to release large amounts of chemiluminescence with the characteristics of the highly cytotoxic species, singlet oxygen.