Oxidative stress: a theoretical model or a biological reality?

Although oxidative stress has been extensively studied the last fifteen years, many physicians and biologists are still sceptical concerning its interest in biology and medicine. This is probably due, in part, to the fact that this subject is a matter of biophysics, and the first studies reported were written using a physical language that inspired these people used to a more concrete problematic very little. Another problem is the difficulty to detect the species mediating oxidative stress, and to determine their role in biological processes. This review is aimed at presenting oxidative stress, as well as reactive oxygen species and free radicals--the molecules that mediate it--in a clear form able to convince all researchers involved in life sciences that these short-lived intermediates are indissociable from any aerobic organism. Moreover, if reactive oxygen species and free radicals are undoubtedly involved in many pathologies, they have physiological functions too.