Thyroid hormones paradox, oxidative stress, and selenium

Reactive oxygen species (ROS) play an important role in physiological processes, but - when being in excess - ROS cause oxidative damage to molecules. Under physiological conditions, the production and detoxification of ROS are more-or-less balanced. Also in the thyroid, ROS and free radicals participate in physiological and pathological processes in the gland. For example, hydrogen peroxide (H2O2) is crucial for thyroid hormone biosynthesis, acting at different steps of the process. Additionally, H2O2 is believed to participate in the Wolff-Chaikoff`s effect, undergoing in conditions of iodide excess in the thyroid. It is the purpose of this review to attempt a synthesis of what we currently know of thyroid hormones production and their relation to oxidative stress and selenium, a trace element.Biomedical Reviews 2009; 20: 17-29

Influence of the Administration of a TNF-α Inhibitor on the Oxidant/Antioxidant Balance in Chronic Venous Insufficiency

Purpose: many studies in experimental models have evidenced the presence of inflammation in venous vascular dysfunction and the implication of TNF-α in vascular pathology, through its prooxidant and proinflammatory effect. Starting from these studies, we experimentally investigated the effect of treatment with a TNF-α inhibitor, etanercept, on the oxidant/antioxidant balance in rats, with the partial obstruction of the common femoral vein. Methods: the researches were carried out in 7 groups of animals (n=10 rats/group), 6 groups undergoing surgery and a control group. In 3 groups, the ligation of the common femoral vein was performed (groups 1, 2, 3), 3 groups underwent the ligation of the common femoral vein and received etanercept (groups 4, 5, 6), in a dose of 1 mg/kg, one dose per week, according to data found in literature. The serum indicators of the O/AO balance were determined: indicators for oxidative stress (malondialdehyde (MDA), protein carbonyls (PC)), indicators for non-enzymatic AO defense (thiol groups (SH), hydrogen donors (HD ), glutathione (GSH)) at weeks 1, 2 and three. Results and Conclusions: chronic venous insufficiency with and without anti-TNF-α treatment induced changes in the oxidant/antioxidant balance compared to the control group; after the administration of the anti-TNF-α preparation, oxidative stress was maintained on account of MDA that increased significantly, and decreased significantly on account of PC compared to the untreated groups; after the administration of the anti-TNF-α preparation, at two and three weeks there was an insignificant increase in antioxidant defense on account of HD and GSH compared to the untreated groups; the administered anti-TNF-α preparation had late and insignificant effects in chronic venous insufficiency