Mucopolysaccharides biological function

H luronic add an unbranched mucopolysaccharide, M, 200,000-400,000. The repeating subunit is a disaccharide, N-acetyl-D-glucosamine glycosidi-cally linked P-1,4 to n-glucuronic add, the latter being linked P-13 to the next disaccharide unit. H.a. occurs in various animal tissues and joint fluids. Its aqueous solution is highly viscous, which explains its biological function as a lubricant. It is synthesized from n-glu-cose in the fibroblasts. 

It is convenient to discuss the polysaccharides under several broad headings from the standpoint of their biological function. The amino sugar-containing polysaccharides of the animal kingdom (excluding the skeletal polysaccharide chitin) form a special class, the mucopolysaccharides, and Bibliography p. 231... 

The existence of biologically active metabolites of retinoic acid has been reported. Krishnamurthy et al. (1963) detected a fat-soluble metabolite of retinoic acid, which displayed biological activity in a rat curative assay, in the liver of chicks administered a 10-mg oral dose of the parent retinoid. Similarly, Wolf et al. (1963) reported that an intestinal metabolite, isolated from retinoid-deficient rats injected with labeled retinoic acid, was active in restoring to normal levels the mucopolysaccharide biosynthesis in retinoid-deficient rat intestinal cell-free particle suspensions. The same laboratory also described a decarboxy-lated metabolite of both retinol and retinoic acid that was isolated from the intestine of retinoid-deficient rats administered retinol or retinoic acid. This compound, which appeared to have both carboxyl and hydroxyl functional groups, was biologically active in a growth assay (Yagishita et al., 1964). In... 

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