[Oxidative stress: value of its demonstration in medical biology and problems posed by the choice of a marker].
Free radical stress results from a desequilibrium in the prooxidant/antioxidant balance. Such a desequilibrium originates in nutritional deficiencies, in inflammatory or stress processes or from environmental exposure. Our body can adapt itself to a moderate range of free radical production but genetic variations can alter such adaptation. Oxidative stress is often partly or totally a cause of various diseases as cancer, atheroma, cataract. But a great number of other diseases as diabetes, infectious processes such as AIDS creates a secondary free radical overproduction that worsens the evolution of the diseases. Monitoring free radical status becomes an interesting challenge for clinical chemists. It can be done by measuring the production of free radicals by patients, as well as their antioxidant capacity, or more often the damages resulting of the stress. Direct determination of free radicals can be obtained by physical methods such as electron spin resonance (ESR) or chemilumisnescence. Chemical trapping seems a good way of investigation by measuring the elimination of specific derivatives of salicylate hydroxylation or nitrosylation. Antioxidant capacity of the subject can be estimated by measuring the status of each antioxidant or by measuring the general antioxidant capacity of plasma or erythrocytes. Generally the evaluation of oxidative stress is performed by the determination of damaged biological products. A number of lipid derivatives can be measured: conjugated dienes, hydroperoxydes, aldehydes (malonaldehyde or hydroxynonenal), hydrocarbides (ethane or pentane in breath). The most controversial but the most used indicator is the determination of malonaldehyde. Other oxidized biological compounds can be measured: derivatives of DNA in urine, oxidized proteins as carbonyl or thiol groups. Oxidized antioxidants can be evaluated in biological fluids to prove the existence of an oxidative stress such as the ratio of oxidized glutathione to total glutathione. Whatever the parameter, its determination needs a lot of care in sampling and assay. Real standardization and quality control are actually lacking.
Favier
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Laboratoire de biochimie des pathologies oxydatives (GREPO), Faculté de pharmacie et Laboratoire de biochimie C, CHU de Grenoble, La Tronche.
D000975:Antioxidants / Q000378:metabolism; D015415:Biomarkers; D005609:Free Radicals / Q000032:analysis / Q000378:metabolism; D006801:Humans; D018384:Oxidative Stress
D000975:Antioxidants; D015415:Biomarkers; D005609:Free Radicals
Le stress oxydant: intérêt de sa mise en évidence en biologie médicale et problèmes posés par le choix d'un marqueur.