Biomarkers Part I

Oxidative and nitrosative stress is expressed in significantly increased generation of reactive oxygen and nitrogen species (RONS) against a sophisticated regulated enzymatic and non-enzymatic antioxidant system, depending on the stress intensity, exposure time and frequency. The determination of Carbonyl Proteins is a widely used oxidative stress marker generated from different sources such as free radicals, trace amounts of metals, lipid peroxidation from polyunsaturated fatty acids, carbohydrate degradation and direct oxidation of free radicals or RONS. The extent of occurrence of oxidative and nitrosative stress depends strongly on the model of exercise. Reactive intermediates produced under conditions of oxidative stress cause the oxidation of polyunsaturated fatty acids in membrane lipid bilayers, leading to the formation of aldehydes. In contrast to the short-living free radicals, the breakdown products of lipid peroxides may serve as ‘oxidative stress second messengers’, due to their prolonged half-life and their ability to diffuse from their site of formation.