The visualization of oxidant stress in tissues and isolated cells

Many studies have implicated the role of oxidant stress in a wide range of human diseases and have led to the rapid expansion of research in this area . With many experimental approaches a direct detection of the production of reactive oxygen species (ROS) and free radicals is not possible. Free radi cals are very reactive, short-lived and react in a non-specific way, so tha t ongoing oxidative damage is generally analyzed by measurement of secondar y products e.g. H2O2, "oxidized" proteins, peroxidized lipids and their bre akdown products, "oxidized" DNA or by fluorographic analysis in combination with fluorescent dyes e.g. dichlorofluorescin (DCFH). The histochemical vi sualization of selected molecular markers for oxidative phenomena can often provide valuable information concerning the distribution of oxidative proc esses in vivo. A number of biochemical methods are available for the monito ring of almost all oxidant stress-related processes, although their applica bility in vivo is limited. This review summarizes the biochemical methods currently available for hist ochemical detection and indirect visualization of an excess of free radical s and ROS. The cited methods are discussed and the results obtained from th eir application are critically evaluated.