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Biomedical subjects

W F Long

Publications and source records attributed to W F Long.

At least 91 records · Page 5Linked to original sources
PubMed1983

Porphyran primary structure. An investigation using beta-agarase I from Pseudomonas atlantica and 13C-NMR spectroscopy.

Porphyran, a highly substituted agarose from Porphyra umbilicalis was degraded by highly purified beta-agarase I from Pseudomonas atlantica. This enzyme cleaved at the reducing side of units of beta-neoagarobiose (3,6-anhydro-alpha-L-galactopyranosyl-(1 leads to 3)-beta-D-galactopyranose). The oligosaccharides were divided into fractions of low and high molecular weight by dialysis. The permeate (23% of total starting carbohydrate) was separated by ion-exchange into neutral and anionic fractions. Gel filtration of the neutral fraction (19%) resolved two major oligosaccharides. These were shown by 13C-NMR spectroscopy to be 6(3)-O-methyl-neoagarotetraose and 6(3),6(5)-di-O-methyl-neoagarohexaose. Gel filtration of the anionic oligosaccharides (3.3%) revealed two novel monosulphated tetrasaccharides, 6-O-sulphato-alpha-L-galacto-pyranosyl-(1 leads to 3)-beta-D-galactopyranosyl-(1 leads to 4)-3,6-anhydro-alpha-L-galactopyranosyl-(1 leads to 3)-D-galactopyranose and its 6(3)-O-methylated derivative. The 13C-NMR data from the sulphated tetrasaccharides provided a novel reference which was used to characterise higher, partially sulphated fragments in the dialysis permeate. The fraction retained on dialysis (77%) had an average degree of polymerisation of 40 and was homologous with the high-molecular-weight anionic permeate. From 13C-NMR spectroscopy porphyran was found to comprise 49% sulphated disaccharide units and these were calculated to occur in stretches averaging 2.0-2.5 contiguous units.

Chemical Phenomena↗
PubMed1983

Effect of antithrombin III, alpha 1-proteinase inhibitor and heparin on amidolytic activity of nerve growth factor (7S-NGF).

Amidolysis catalysed by nerve growth factor (7S-NGF) and by a glandular kallikrein, unlike that catalysed by thrombin, was not inhibited by antithrombin III, either in the presence or absence of heparin. Inhibition by alpha 1-proteinase inhibitor of thrombin-, but not of 7S-NGF- or kallikrein-catalysed amidolysis was alleviated by incubation of enzyme and heparin before addition of inhibitor. These data are discussed in terms of a possible control of growth factor activity by antiproteinases and glycosaminoglycans.

Animals↗
PubMed1983

Glycosaminoglycans and the control of cell surface proteinase activity.

It is postulated that the metabolically variable fine structure of pericellular heparan glycosaminoglycans affects the ability of these molecules to influence cell proliferation-associated proteinase-catalysed reactions occurring at cell surfaces. Evidence suggesting the possibility of a wide repertoire of glycosaminoglycan-mediated positive and negative effects on such reactions is reviewed. It is suggested that clinical administration of compounds related chemically to heparins might usefully modulate cell proliferation-associated proteinase activity.

Animals↗
PubMed1981

The accuracy of multimeridional refraction.

The accuracy of meridional refraction using equally spaced preselected meridians was investigated by using populations of computer-simulated patients. The number of meridians refracted, patient refractive error, and the coarseness of phoroptor steps were varied. Results indicate that the accuracy of meridional refraction is independent of the relative orientation of the axis of the patient's astigmatism and the preselected meridians, that little is to be gained by use of a phoropter with steps finer than the usual 0.25 D, and that with a sufficient number of meridians, meridional refraction can be as accurate as more conventional techniques.

Computers↗
PubMed1981

The anticoagulant activity of dermatan sulphates: evidence against the involvement of antithrombin III.

Anticoagulant activity of dermatan sulphates is unaffected by antiserum specific for antithrombin III (AT III) unless the glycosaminoglycan preparation contains demonstrable heparin. 2 Only dermatan sulphate preparations of considerable heparin content potentiate AT III inhibition of thrombin, factor Xa and plasmin. 3 These data suggest that dermatan sulphates exert anticoagulant activity which, unlike that of heparin, is largely or totally independent of AT III.

Animals↗
PubMed1981

Effect of sulphated polysaccharides on the alpha 1-antitrypsin inhibition of amidolysis catalysed by coagulation cascade proteinases.

1 The ability of several sulphated polysaccharide anticoagulants to prevent alpha 1-antitrypsin inhibition of thrombin paralleled their ability to potentiate antithrombin III inhibition of thrombin. None of the compounds examined altered the ability of alpha 1-antitrypsin to inhibit activated coagulation factor X (Xa). 2 These results are consistent with the possibility that a direct polysaccharide-proteinase interaction may be involved in the sulphated polysaccharide-modulated inhibition of thrombin by antithrombin III.

Amides↗
PubMed1980

Sulphated glycosaminoglycans in regenerating rat liver.

The total weight percentage glycosaminoglycan content of rat liber was found to increase by 50% in the first 30 h after partial hepatectomy. The content returned to near normal by the third day, but then increased again to a second maximum at 5-6 days, only to gradually decline to normal by the ninth day, when regeneration was nearly complete. This biphasic pattern was most marked in the chondroitin sulphate A/C component, with a 6-fold increase by the sixth day. Dermatan sulphate showed the same temporal trend, whereas heparan sulphate remained relatively unaltered. No such changes were detected in the livers of rats subjected to sham operation. The possible molecular mechanisms underlying the apparent link between cellular glycosaminoglycan content and proliferative tendency are discussed.

Animals↗