Vitamin cellular activity

The changes in calvarial phosphatase activities observed in animals treated with 25-(OH)D3 are totally different from those obtained with either 1.25-(OH)2D3 or 24.25—(OH)2D3. This fact indicates that physiological doses of 25-(OH)D3 may have an effect on cellular activity, independent of the conversion of this metabolite into these dihydroxyderivatives. The various effects of these vitamin D3 metabolites cannot be correlated with changes in serum calcium and/or phosphate concentrations. Among those factors other than serum calcium and phosphate concentrations that may be involved in the mechanism of action of vitamin D3 metabolites on bone phosphatase activities, the parathyroid hormone is of importance. This hormone is known to be a potent activator of bone phosphatases223,224,228. Parathormone increases the content of alkaline, neutral and acid phosphatases in mouse calvaria in vitro. Calcitonin does not prevent the increase of those enzymes while dichloromethylene diphosphonate causes a decrease in acid phosphatase and pyrophosphatase226. ... 

Blood serum, usually bovine-derived (calf or fetal bovine), contains amino acids, growth factors, vitamins, proteins, hormones, lipids, and minerals, among other components, as indicated in Table 5.3. Besides fetal bovine serum, serum from horse (equine), and even from humans (less common) can also be used. The main functions of serum are to stimulate growth and other cellular activities through hormones and growth factors, to increase cellular adhesion through specific proteins, and to supply proteins for the transport of hormones, minerals, and lipids (Freshney, 2005). Supplementation with bovine fetal serum is performed at concentrations from 2 to 20% in volume. 

ZINGG, J. M. 2007b. Molecular and cellular activities of vitamin E analogues. Mini Rev Med... 

The specific role of vitamin A in tissue differentiation has been an active area of research. The current thinking, developed in 1979, involves initial dehvery of retinol by holo-B >V (retinol-binding protein) to the cell cytosol (66). Retinol is then ultimately oxidized to retinoic acid and binds to a specific cellular retinoid-binding protein and is transported to the nucleus. Retinoic acid is then transferred to a nuclear retinoic acid receptor (RAR), which enhances the expression of a specific region of the genome. Transcription occurs and new proteins appear during the retinoic acid-induced differentiation of cells (56). 

Myo-inositol is one of the most biologically active forms of inositol. It exists in several isomeric forms, the most common being the constituent of phospholipids in biological cell membranes. It also occurs as free inositol and as inositol hexaphosphate (IP6) also known as phytate which is a major source from food. Rice bran is one of the richest sources of IP6 as well as free inositol. Inositol is considered to belong to the B-complex vitamins. It is released in the gastrointestinal tract of humans and animals by the dephosphorylation of IP6 (phytate) by the intestinal enzyme phytase. Phytase also releases intermediate products as inositol triphosphate and inositol pentaphosphate. Inositol triphosphate in cellular membrane functions as an important intra- and intercellular messenger, that merits its value as a nutritional therapy for cancer. 

Natural products have been noted for their potential health benefits from time immemorial and are the basis of Ayurveda, an ancient Indian medical practice (Bushkin and Bushkin, 2002). However, the potential benefits of several natural products reside in one or two active ingredients. For example green tea stands for polyphenols, soy for soy estrogens, broccoli for isothiocyanates and grape seed for polyphenols. The beauty of rice bran is that there are more than 100 antioxidants, several categories of bioactive phytonutrients, such as IP6, polyphenols, phytosterols, tocotrienols, y-oryzanol, B vitamins, minerals and trace minerals in addition to fat, protein, fiber, polysaccharides and other nutrients. These phytonutrients and antioxidants of rice bran are believed to act at the cellular level, and their synergestic function is responsible for the positive health benefits. 

Selenium is readily available in a variety of foods including shrimp, meat, dairy products, and grains, with a recommended daily intake of 55 to 70 jug. It occurs in several forms with Se+6 being biologically most important. Selenium is readily absorbed by the intestine and is widely distributed throughout the tissues of the body, with the highest levels in the liver and kidney. It is active in a variety of cellular functions and interacts with vitamin E. Selenium appears to reduce the toxic effects of metals such as cadmium and mercury and to have anticarcinogenic activity. Selenium produces notable adverse effects both in deficiency and excess thus recommended daily intake for adults is approximately 70 Jg/day but should not exceed 200 pg/day. 

Vitamin D is converted in the liver and kidneys to 1,25-dihydroxyvitamin D, which is the hormone-active compounds. The principal physiological function is to maintain the serum calcium and phosphorus concentrations in a range that support cellular processes, neuromuscular function, and bone ossihcation [417], Only a few foods contain vitamin D in quantities that have an impact on the dietary intake hsh liver, hsh liver oils, fatty fish, and egg yolks. Thus, some countries practice fortihcation of certain foods with vitamin D, most often milk, margarine, and/or butter. 

Vitamin A is essential for proper functioning of the retina, for the integrity of epithelial tissue, for growth and bone development and for reproduction. For vision the active vitamin appears to be retinal as the chromophore of both rods and cones is 11-cis-retinal which, in combination with the protein opsin, forms the photoreceptor rhodopsin. Retinoic acid is the active form associated with growth, differentiation, and transformation. Both all-trans and 9-cis retinoic acid act as a steroid hormone to affect cellular differentiation, especially for morphogenesis, reproduction and for immune responses. At... 

Retinoids are a family of naturally occurring and synthetic analogues of vitamin A. The skin of subjects deficient in vitamin A becomes hyperplastic and keratotic (phrynoderma, or toad skin). While natural vitamin A is occasionally employed therapeutically, synthetic retinoids are more effective and represent a major advance in dermatological pharmacotherapy. Retinoids have myriad effects on cellular differentiation and proliferation it is likely that nuclear retinoic acid receptors mediate these effects by activating gene expression in a manner analogous to receptors for steroid hormones and thyroid hormones. Despite a common mechanism of action, however, retinoids vary widely in their physiological effects. 

Retinol (vitamin A) is found in foods of mammalian origin in the form of retinyl ester, or in fruits and vegetables as carotenoids with provitamin A activity, especially P-carotene (provitamin A). In enterocytes, retinol binds to cellular retinol-binding protein type II (CRBPII), which directs the esterification by the enzyme lecithin retinol acyltransferase (LRAT). 

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