Oxidative stress. Biochemistry and human disease.

The early involvement of free radicals in the evolution of life may explain their ubiquitous presence and vital physiological role. Imbalance between protection against free radicals and their generation, explains the likely association of various diseases with toxic oxygen species. An elaborate defence system against oxygen-free radicals exists. The effects of oxidative stress are manifold. Direct demonstration of oxygen radicals in intact biological systems is difficult. Frequently, effect-related measurements are used in this respect. The clinical conditions adult respiratory distress syndrome and multiple organ failure, reflex sympathetic dystrophy and sugar cataract are discussed and the role of oxygen radicals in the aetiology of these diseases are described.