Vitamin Mucous synthesis

Cobalt is one of twenty-seven known elements essential to humans (28) (see Mineral NUTRIENTS). It is an integral part of the cyanocobalamin [68-19-9] molecule, ie, vitamin B 2> only documented biochemically active cobalt component in humans (29,30) (see Vitamins, VITAMIN Vitamin B 2 is not synthesized by animals or higher plants, rather the primary source is bacterial flora in the digestive system of sheep and cattle (8). Except for humans, nonmminants do not appear to requite cobalt. Humans have between 2 and 5 mg of vitamin B22, and deficiency results in the development of pernicious anemia. The wasting disease in sheep and cattle is known as bush sickness in New Zealand, salt sickness in Florida, pine sickness in Scotland, and coast disease in AustraUa. These are essentially the same symptomatically, and are caused by cobalt deficiency. Symptoms include initial lack of appetite followed by scaliness of skin, lack of coordination, loss of flesh, pale mucous membranes, and retarded growth. The total laboratory synthesis of vitamin B 2 was completed in 65—70 steps over a period of eleven years (31). The complex stmcture was reported by Dorothy Crowfoot-Hodgkin in 1961 (32) for which she was awarded a Nobel prize in 1964. 

The story of vitamin B12 began with pernicious anemia, a disease that usually affects only persons of age 60 or more but which occasionally strikes children.3 Before 1926 the disease was incurable and usually fatal. Abnormally large, immature, and fragile red blood cells are produced but the total number of erythrocytes is much reduced from 4-6 x 106 mm-3 to 1- 3 x 106 mm-3. Within the bone marrow mitosis appears to be blocked and DNA synthesis is suppressed. The disease also affects other rapidly growing tissues such as the gastric mucous membranes (which stop secreting HC1) and nervous tissues. Demyelination of the central nervous system with loss of muscular coordination (ataxia) and psychotic symptoms is often observed. 

SAFETY PROFILE A powerful irritant to skin, eyes, and mucous membranes. Flammable when exposed to heat or flame. Ammonia is liberated and Uthium hydroxide is formed when this compound is exposed to moisture. Reacts violently with water or steam to produce toxic and flammable vapors. Vigorous reaction with oxidizing materials. Exothermic reaction with acid or acid fumes. When heated to decomposition it emits very toxic fumes of LiO, NH3, and NOx. Used in synthesis of drugs, vitamins, steroids, and other organics. See also LITHIUM COMPOUNDS, AMIDES, AMMONIA, and LITHIUM HYDROXIDE. 

The mechanism of action of 13-cis retinoic acid in normal and diseased human skin has not been studied. Many biological effects of vitamin A, especially its ability to labilize biological membranes and release lysosomal enzymes, have been described in detail. Vitamin A and its derivatives control cell growth and differentiation in epithelial tissues. Retinoic acid, in particular, is a potent stimulator of mitosis in the epidermis. Excess vitamin A and its derivatives also have been demonstrated to inhibit keratinization and induce a mucous metaplasia with enhanced glycoprotein synthesis in several laboratory models, such as embryonic chick skin in organ culture . The mode of action of topical retinoic acid in acne is thought to be the increased production of nonadherent surface scales, which prevents follicular occlusion and comedo formation . None of the known effects, however, can fully explain the apparent disease and individual specificity of the clinical response to 13-cis retinoic acid nor do they explain its ability to reduce the erythema in these diseases. 

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