Vitamins, continued functions

Table 1 Vitamin 1 [continued) Functions Deficiency Disease...

More than 20 other, naturally occurring metaboUtes of vitamin D have been isolated and characterized, and many derivatives have been synthesized. Their function is the subject of continuing research (16,51,141,162). 

Vitamin D is not strictly a vitamin since it can be synthesized in the skin, and under most conditions that is its major source. Only when sunlight is inadequate is a dietary source required. The main function of vitamin D is in the regulation of calcium absorption and homeostasis most of its actions are mediated by way of nuclear receptors that regulate gene expression. Deficiency—leading to rickets in children and osteomalacia in adults—continues to be a problem in northern latitudes, where sunlight exposure is poor. 

Coenzyme Q10 is an antioxidant essential for mitochondrial function. A dose of 1200 mg daily was associated with a slower decline in UPDRS scores than patients not receiving coenzyme Q10. Lower doses were no better than placebo, but the drug continues to be studied in doses up to 2400 mg daily. Many formulations contain vitamin E, and patients should not exceed recommended daily allowances of this vitamin, as bleeding times may be prolonged.42,43... 

Early vitamin A- deficiency loss of ciliae and continuous basal cells loss of barrier function... 

There have been continuous search for new substances that can improve biological functions and possibility of applying these compounds to promote well-being of human. This has resulted in development of products such as vitamins, dietary supplements, functional foods, nutraceuticals, phytochemicals, bio-chemopreventatives, and designer foods (Zeisel,... 

The most clearly documented role lor selenium is as a necessary component of glutathione peroxidase. Selenium is also involved in the functions of additional enzymes, e.g.. type I iodoihvronine deiodinase. leukocyte acid phosphatase, and glucuronidases. A role for selenium in electron transfer has been suggested as has involvement in nonheme iron proteins. Selenium and vitamin b appear to be necessary lor proper functioning of lysosomal membranes. A role for selenium in metabolism of thyroid hormone has been continued. 

Three types of inline HPLC detector have been used to measure fat-soluble vitamin concentrations in food sample extracts absorbance, fluorescence, and electrochemical detectors. Each of these detectors provides a continuous electrical output that is a function of the concentration of solute in the column effluent passing through the flow cell. 

Hepatic Fibrosis/Cirrhosis Fibrosis usually results from chronic inflammation which can be the result of continuous exposure to a variety of hepatotoxic chemicals such as organic arscnicals, vinyl chloride, or high doses of vitamin A (Zimmerman, 1999), chronic ethanol ingestion and nonalcoholic fatty liver disease. Fibrosis usually occurs around the portal area, in the space of Disse, and around the central veins. This results in loss of liver architecture and function. The hepatocytes are replaced with fibrous material and thus there is hepatocyte loss. Periportal fibrosis may lead to portal hypertension. 

Hlastin is a hydroxyproline containing protein of connective tissue. Unlike collagen, elastin does not form a triple helix. With a vitamin deficiency elaslin continues to be produced and secreted from the cell, but in an underhydroxylated state. The function of the hydroxyl group in eJastin is not dear. 

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