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Biomedical subjects

R A Gibbons

Publications and source records attributed to R A Gibbons.

29 records · Page 2Linked to original sources

The passage of calcium and strontium across the gut of the anaesthetized goat.

1. The translocation of calcium and strontium across the intestine of the anaesthetized goat has been studied. It has been found to be unaffected by ouabain, by the absence of sodium, by a severely hypertonic environment and by heparin and chondroitin sulphate. Thus it is unlikely that, in the intact goat, the trans-mucosal sodium and calcium transport systems are interrelated.2. The effect of sodium alginate both on the rate of absorption and the calcium/strontium discrimination ratio has been confirmed.3. The movement of calcium ion in both directions across the intestinal mucosa has been studied and evidence for the active transport of calcium adduced.

Alginates↗

The action of neutral hypochlorite on epithelial mucopolysaccharides.

1. The uptake of dilute neutral hypochlorite by epithelial mucopolysaccharides has been compared with that of proteins, polysaccharides, amino acids and sugars. The uptake has been shown to be related to the protein content of the mucopolysaccharides rather than their polysaccharide content. 2. The destruction of the components of epithelial mucopolysaccharides, certain sugars and polysaccharides after oxidation with dilute neutral hypochlorite at 0-4 degrees has been studied. Very little destruction of the sugar components occurred and in epithelial mucopolysaccharides the only amino acid destroyed specifically was arginine. 3. Oxidation of bovine submaxillary-gland mucoprotein and ovalbumin caused very little destruction of hexosamine and no detectable liberation of this residue as a free reducing group, indicating that the O-seryl galactosaminide and the N-acyl-glycosylamine linkages reported to be present in these compounds were relatively stable to hypochlorite. 4. Depolymerization of epithelial mucopolysaccharides by neutral hypochlorite has been studied by using gel-filtration columns and compared with the depolymerization of polysaccharides and proteins under similar conditions. The polysaccharides examined were relatively resistant to oxidation whereas the proteins were extensively broken down. It is inferred that the extensive depolymerization of epithelial mucopolysaccharides by hypochlorite is related to their protein content rather than their polysaccharide content. 5. Fractionation of the products of oxidation of epithelial mucopolysaccharides by column procedures has revealed that the relative proportions of components in all fractions were similar to those in the original material. 6. Though this study does not provide unequivocal evidence from which the overall structure of this type of epithelial mucopolysaccharide may be deduced, the balance of probabilities now appears to favour a long polypeptide chain to which a large number of oligosaccharide side chains are attached via O-seryl and O-threonyl glycosidic linkages. The results, however, are also consistent with an alternating sequence of short polysaccharide and polypeptide chains and further evidence is necessary before this structure can be ruled out.

Animals↗