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Biomedical subjects

R E Hurst

Publications and source records attributed to R E Hurst.

At least 73 records · Page 4Linked to original sources
PubMed1979

Structural basis for the anticoagulant activity of heparin. 1. Relationship to the number of charged groups.

This study was undertaken to provide further information concerning the chemical heterogeneity of heparins and the relationships between the anticoagulant activity (USP assay) and the anionic density of the heparin. A sample of commercial heparin was fractionated into 13 fractions by sequential extraction in a two-phase system of 1-butanol-aqueous NaCl containing excess hexadecylpyridinium chloride. The anionic density distribution was characterized by the fractional distribution of uronate among the fractions. The fractions were characterized by several molar ratios of constituents, molecular weight, charge density, and anticoagulant activity in recalcified sheep plasma. The heparin was broadly distributed among the last 10 fractions; the first three contained impurities which were completely separated from the heparin fractions. The heparin fractions differ systematically in anionic density but are of substantially the same molecular weight. Anticoagulant activity increased markedly with anionic density, ranging from 81 units/mg for the heparin fraction with the lowest anionic density up to a high of 243 units/mg. The relationship between anticoagulant activity and either anionic density or its square is nonlinear. However, in the latter case an initial linear relationship was observed for anticoagulant activities of less than 200 units/mg.

Animals↗
PubMed1979

Structural basis for the anticoagulant activity of heparin. 2. Relationship of anticoagulant activity to the thermodynamics and fluorescence fading kinetics of acridine orange-heparin complexes.

Complexing heparin or dermatan sulfate with the fluorescent probe acridine orange provides a means of studying electrostatic as well as static and dynamic conformational aspects of these glycosaminoglycans via the thermodynamic and photochemical (fluorescence fading) properties of these complexes. The cooperative binding constants (Kq), fluorescence fading rate parameters (r''), and anticoagulant activities of heparins fractionated according to anionic density all showed qualitatively the same dependence upon anionic density. When Kq and r'' were plotted against anticoagulant activity, empirical relationships were observed. Interestingly, the corresponding values for unfractionated dermatan sulfate fell on the lines defined by the heparin fractions. Temperature-dependence, studies demonstrated that differences in fading rate observed for heparins of different anionic densities are entropic in origin and reflect differences in the ability to assume a special configuration. Differences in activation entropy for fluorescence fading can be empirically correlated with anticoagulant activity. The latter correlation suggests a physical similarity in the roles played by anionic density in both fluorescence fading and anticoagulant activity.

Acridine Orange↗
PubMed1978

Biochemical composition and heterogeneity of heparan sulfates isolated from AH-130 ascites hepatoma cells and fluid.

The glycosaminoglycan composition of AH-130 ascites hepatoma cells and fluid were examined using enzymatic digestion, electrophoresis, and sequential partition fractionation. The cell-associated glycosaminoglycans were found to consist of 93% heparan sulfate, with the remainder consisting primarily of chondroitin sulfate. The glycosaminoglycans isolated from the ascitic fluid were found to consist of 58% heparan sulfate, 26% hyaluronic acid and 16% chondroitin sulfate. Dermatan sulfate was not detected in either cells or fluid. The heparan sulfate isolated from AH-130 cells in low-sulfate and highly heterogeneous with respect to biochemical composition. Fractions isolated by partition fractionation varied from 0.14 mol sulfate/mol uronic acid to 0.6 mol sulfate/mol uronic acid. Of the total sulfate 70--80% is N-sulfate in the former and 50% in the latter. Electrophoresis in 0.1 M HCl showed a highly heterogeneous material with mobility between that of hyaluronic acid and beef lung heparan sulfate. The heparan sulfate isolated from the fluid was similar to that isolated from the cells but was, however, somewhat more homogeneous with respect to charge.

Animals↗
PubMed1978

Isolation and characterization of glycosaminoglycans from the Furth murine mastocytoma.

New methods for isolation and fractionation by partition are described and compared with existing techniques. Substantially purer products were isolated by partition as compared to precipitation with hexadecylpyridinium chloride. The glycosaminoglycans isolated fron Furth murine mastocytoma tumor were found to consist of 78-80% heparin, 12-13% chondroitin sulfate, and 8-9% hyaluronate. Dermatan sulfate was not detected. Two heparin-like glycosaminoglycans could be isolated by partition fractionation in the phase system 1-butanol/aqueous NaCl containing hexadecylpyridinium chloride. The composition of one was typical of heparins. However, the other glycosaminoglycan contained only 0.47 moles N-sulfate/mole uronate, but had electrophoretic and partition properties characteristic of heparin.

Animals↗
PubMed1977

The partition of glycosaminoglycan-quaternary ammonium complexes, II. The effects of polymer molecular weight and sulfation.

Previous results have shown the possibility for obtaining high-resolution separations of glycosaminoglycans by partition in butanol/aqueous two-phase systems containing quaternary ammonium salts. In this paper, the effects on partition behavior of both polymer molecular weight and sulfation were examined. Two series of fractionated chondroitin sulfate polymers were isolated in which the molecular weight and sulfation varied systematically. In the molecular weight series the six samples, spanned the range from 3200 +/- 300 to 19 700 +/- 500 and each sample carried 0.8 sulfate groups per uronic acid residue. In the sulfation series, each sample had an essentially constant molecular weight of 13 000, but the sulfation varied from 0.58 to 0.88 sulfate groups per uronic acid. The C50 of each of these samples was determined in the 1-butanol/aqueous NaCl phase system containing 1% hexadecylpyridinium chloride. In the series wherein the molecular weight varied, the C50 increased with molecular weight up to 12 000 where a limiting value was reached. In the series wherein the sulfation varied, a linear relationship was found between the C50 and the square of the number of anionic substituents per disaccharide. These results show that fractionation by partition techniques will be sensitive to the anionic nature of the polymer, but for the common connective tissue glycosaminoglycan, there will be no fractionation according to molecular weight.

Chondroitin Sulfates↗
PubMed1976

The partition of glycosaminoglycan-quaternary ammonium complexes. I. The effect of phase composition.

The complexes formed between quaternary ammonium cations and polyanionic glycosaminoglycans can be partitioned between partially miscible aqueous inorganic salt and alcohol phases. Small changes in salt concentration can completely shift the complex from one phase to the other. The effect of the phase composition variables: the type of inorganic salt, the type of quaternary ammonium salt, and the alcohol used, were systematically investigated. The sharp transition from solubility in the upper non-aqueous phase to solubility in the lower, aqueous phase was found to be strongly affected by the type of inorganic salt. This transition occurred at higher salt concentrations when NaCl, KCl, or LiCl were used than when CaCl2 or MgCl2 were used. Differences in behavior among glycosaminoglycans were larger for NaCl than for CaCl2. The complex is stabilized to dissociation by salt by increasing hydrophobicity of the non-aqueous phase. However, aggregation of the complex into an insoluble form is also favored by an increasingly hydrophobic environment. The most consistent partition was observed with 1- and 2-butanol. The partition isotherm of chondroitin 4-sulfate was investigated at constant salt concentration. It was found that the partition coefficient varies with the concentration of chondroitin 4-sulfate, although the magnitude of this effect could be diminished by increasing the quaternary ammonium salt concentration.

Butanols↗
PubMed1976

A method for the quantitative determination of urinary glycosaminoglycans.

A method is presented by which the urinary glycosaminoglycans can be isolated in a macromolecular fraction with complete recovery by preparative gel filtration. The urinary glycosaminoglycans can be quantitated by determinations of uronic acid and sulfaminohexose in the macromolecular fraction. Using untreated, random urine specimens of less than 5 ml volume, clinical mucopolysaccharidoses types I, II, and III could be readily distinguished.

Diagnosis, Differential↗