Presse Med
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INDIRECT MECHANISM OF ACTION: Tibolone (OD 14) is the precursor of its active principles that are its metabolites: 3 alpha and 3 beta hydroxylated derivatives. In vivo, the latter behave like estrogens. Certain tissues (liver, endometrium) may metabolize the 3 beta ol derivative into the delta 4 isomer with progestagenic and androgenic activity. The metabolism of the product in other tissues such as the breast and brain is unknown.
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FREE RADICALS AND THE THEORY OF AGING: Severe oxidative stress progressively leads to cell dysfunction and ultimately cell death. Oxidative stress is defined as an imbalance between pro-oxidants and/or free radicals on the one hand, and anti-oxidizing systems on the other. The oxygen required for living may indirectly be responsible for negative effects; these deleterious effects are due to the production of free radicals, which are toxic for the cells (superoxide anions, hydroxyl radicals, peroxyl radicals, hydrogen peroxide, hydroperoxides and peroxinitrite anions). Free radical attacks are responsible for cell damage and the targeted cells are represented by the cell membranes, which are particularly rich in unsaturated fatty acids, sensitive to oxidation reactions; DNA is also the target of severe attacks by these reactive oxygen species (ROS).
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A FREQUENTLY MISUNDERSTOOD AFFECTION: Because of its high prevalence and the considerable alteration it often provokes in quality of life, tinnitus aurium is an important public health problem. Current treatment of tinnitus aurium is limited by the lack of knowledge of the physiopathological processes that generate it.