Hexosamine content

Hashimoto, S., Maita, Y., Yanada, M., and Takahashi, K. (1997). Hexosamine contents in sinking particles as an indicator for biological processes in the Bering Sea and the central subarctic Pacific. In Biogeochemical processes in the North Pacific (Tsunogai, eds.). Japan Marine Science Foundation, Tokyo, pp. 290—299. 

This fractionation method was subsequently used successfully by other investigators (Bll, D2a, Gl, G64, H39, H40, II, 12, N6, N7, P14, S6-S9, W7). Schrager (SIO) 12 years later severely criticized it and considered that measurement of mucosubstances by determination of their peptide moiety was an improper technique for measuring the gastric juice mucosubstances. He simultaneously estimated the tyrosine and hexosamine contents of the mucoprotein and mucoproteose fractions and found no quantitative correlation between the two. He therefore concluded that tyrosine measurement was not adequate for quantitation of these fractions (see Section 2.2). These results are contradicted by recent data of DeGraef (D2a) obtained on Heidenhain pouches which show very satisfactory correlation between mucoprotein and mucoproteose assay by means of tyrosine and hexosamine quantitation (see Fig. I8a). 

Vita et al. (V2), using highly basic Dowex-1 X2 resin in Cl and OH form, separated acidic aminopolysaccharide (hexuronic acid content of 35-37%) and neutral mucopolysaccharide hexosamine content 25-30%) from an aqueous extract of hog gastric mucosa. 

In contrast, studies on the effect of ascorbic acid deficiency on the sequence of wound repair in guinea pig (D21) showed an initial decrease in amount of hexosamine and absence of metachromasia. Fibroblasts were poorly oriented and immature, and no collagen formation took place. By the twelfth day, the absence of coUagen and the presence of immature fibroblasts were established, and hexosamine content was found to be high instead of low as in normal repair. 

Past determinations of amino sugars have usually been carried out using standard amino-acid techniques with hydrolysis of polymeric material under the conditions applied for proteinaceous material and reporting of the total hexosamine content (e.g. Degens, 1970). Dawson and Mopper (1978b) have suggested that the conditions for hydrolysis should resemble those employed for polysaccharide material to avoid substantial destruction losses of amino sugars. 

Figure 2.8 Progress in wound healing (A), dynamic of hexosamine content (B) and collagen content (C) in skin after wounding [65], Reproduced with permission from ref [65], Copyright 2009, John Wiley Sons, Ltd...

Most publications on NVG contain incomplete lipid analyses or none. Craig et al. (1959) examined only some fractions of the liver lipids but not the brain. No chemical analyses were performed in the eight cases of Landing et al. (1964). In the case of Norman et al. (1959) with a cherry-red spot in the macula and hepatomegaly the spleen and liver hexosamine content was increased several-fold, while no neuraminic acid was present. Liver phospholipids but not total lipids were increased. 

Collagen derived from bovine deep flexor (Achilles) tendon was used for nerve conduit fabrication. Tendons were first cut into thin slices and then purified by a combination of enzymatic and chemical treatments to reduce the non-collagenous moieties while retaining the integrity of the fibrillar structure for mechanical strength. Chemical analysis of this material showed a minimal level of hexosamine content indicating most of the glycoproteins were removed by the purification steps. 

Houck, J.C. and Jacob, R.A. Effect of Age Upon Collagen and Hexosamine Content of Rat Skin. 

Values of optical rotations from [a]n +38° to + 78 , and various ratios of sulfate to hexosamine content have been reported these ratios, however, are all in the vicinity of i. Various contents of sulfamate and JV-acetyl groups have also been observed, and it has become evident that one is dealing more with a family of substances, possessing varying degrees of N- and 0-s ilfation, than with a chemical entity. Since our knowledge of the chemical structure of the polysaccharide chain is still scant, it has not been possible to ascertain definitely the chemical identity between the various low sulfated heparans. 

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