| This contest is fueled by the following news: |
| | Four Oakland Raiders football players - defensive tackle Dana Stubblefield, center Barret Robbins, linebacker Bill Romanowski and defensive tackle Chris Cooper - have tested positive for the newly discovered steroid THG (tetrahydrogestrinone) and face four-game suspensions.
Steroids are substances of animal or more often of plants, possessing high biological activity. Steroids are formed in nature from isoprenoid predecessors. The specialty of steroid structure is the presence of a condensed tetracyclic system of gonane (former name - sterane). The nucleus of gonane in steroids can be saturated or partially unsaturated and contain alkyl and some functional groups – hydroxyl, carbonyl or carboxyl.
Steroid hormones participate in the metabolic control of substances and several physiological functions of the organism. A series of synthetic hormones, for example, prednisolone, due to the action of which an organism, natural analogues excel. Sterols of cholesterol and also bile acids – compounds, having carboxyl group in side chain, for example, cholic acid, which are present in the human organism, belong to the steroids group.
Cardiac glycosides – vegetable substances (from digitalis, strophanthus, lily of the valley), regulating cardiac activity, belong to steroids. In glycosides, the steroid fragment is connected by the glycoside connection with oligosaccharide.
Steroids is a group of natural and synthetic chemical compounds – derivatives of partially or completely hydrogenated 1,2-cyclo pentene phenantrene types.
Four articulated rings A, B, C, D are formed from 17 carbon atoms in a molecular structure. Steroids occur widely in nature and they participate in the realization of diversified biological functions. Sexual hormones, vitamin D, hormones of adrenal glands, bilious acids, molting hormone and metamorphosis of arthropods, repellents of insects, frightening off predators and the poison in the skin of toads have a steroid nature. Both natural and synthetic steroids, at similar structure, reveal highly distinguishing physiological action, therefore, they are widely used in medicine as anti-inflammatory, cardiac, contraceptives and other means.
Steroids are divided into sterols, bile acid, steroid hormones, steroidal saponins, cardiac glycosides and steroidal alkaloids.
More often, steroids occur in the form of sterols, found practically in all plants, mushrooms and animals. Particularly, cholesterol, which is known to all, serves as an initial substance for synthesis of all steroid hormones in the organism. Cholesterol can be used for the industrial manufacture of many steroids, however, it is more economically viable to use some readily available vegetative sterols (for example, stigmasterol from soybeans), having a structural similarity with the target steroids instead of cholesterol.
Steroidal sexual hormones are steroids, produced by the sexual glands (testicles and ovaries) or influencing them. Androgens or male hormones, the main of which is testosterone and female sexual hormones – estrogens and progestines (gestogens) belong to the steroidal sexual hormones. Progestin, including progesterone, participates in preparation of the uterus for pregnancy and helps in the maintenance of pregnancy. Synthetic progestines and estrogen are part of contraceptive tablets.
Thanks to its anabolic activity (occurring particularly in the growth of muscular and bone tissues), all the androgens acquired bad popularity amongst sportsmen, for which, the word "steroid" began to mean male sexual hormones. However, the ability of androgens, taken in large doses to improve the sportsmen's shape by increasing the force, endurance and muscular weight, remains the subject of dispute. Moreover, the excessive use of these steroids can lead to liver diseases and also other harmful side effects.
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