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H Muir

Publications and source records attributed to H Muir.

142 records · Page 8Linked to original sources
PubMed1969

Studies on protein-polysaccharides from pig laryngeal cartilage. Extraction and purification.

1. Protein-polysaccharides of chondroitin sulphate were extracted from fresh laryngeal cartilage at pH6.8 by two procedures. Procedure I consisted of brief low-speed homogenization in 0.15m (iso-osmotic) sodium acetate and procedure II consisted of longer homogenization followed by prolonged extraction in 10% calcium chloride solution. 2. The protein-polysaccharides in both extracts were isolated and purified by precipitation with 9-aminoacridine hydrochloride. They were free from serum proteins, collagen and nucleic acids and also of degradative enzymes. The absence of such enzymes was shown by viscosity measurements on solutions of protein-polysaccharides incubated for up to 24hr. at pH4 and 6.8. 3. Mannose, glucose or fucose were not detected by paper chromatography and only traces of sialic acid were present. 4. The yield with procedure II was twice that with procedure I and the products differed in their protein and glucosamine contents. 5. Hyaluronic acid was unlikely to have been precipitated at an acid pH, so the glucosamine was attributed to keratan sulphate, as serum proteins were absent. There was no free keratan sulphate in the preparation. 6. Both preparations were heterogeneous in the ultracentrifuge, showing at least three components.

Animals↗
PubMed1969

Studies on protein-polysaccharides from pig laryngeal cartilage. Heterogeneity, fractionation and characterization.

1. Protein-polysaccharides from pig laryngeal cartilage extracted by two procedures described in the preceding paper (Tsiganos & Muir, 1969) were shown to consist of macromolecules of various sizes as assessed by gel filtration in 4% and 6% agarose. 2. A larger proportion of the smaller molecules was present in the preparation obtained by brief extraction in iso-osmotic sodium acetate (procedure I) than in that obtained by more prolonged extraction in 10% (w/v) calcium chloride (procedure II). 3. Two fractions were separated by gel filtration in 6% agarose and by electrophoresis in compressed glass fibre. These fractions differed in chemical composition and in antigenic determinants. The gel-retarded fraction R and that of higher electrophoretic mobility possessed the same single antigen, whereas the gel-excluded fraction E and the slower electrophoretic fraction contained all the antigens of the starting material including that of fraction R. 4. Five N-terminal amino acid residues were identified in preparation I and fraction E, only two of which were present in fraction R. 5. The relative proportions of gel-excluded and gel-retarded fractions did not change when solutions of high ionic strength, urea or guanidine hydrochloride were used for elution. 6. The differences in chemical and amino acid composition between fractions R and E showed that the latter was not a simple aggregate of the former. Fraction E contained more basic and aromatic amino acids, and some methionine and cystine; the last two were absent from fraction R. Hydroxyproline was not detected in either fraction. 7. The number of glycosidic linkages in both fractions was estimated by alkaline beta-elimination. Appreciable amounts of threonine as well as serine were destroyed in both fractions. An average chain length for chondroitin sulphate was calculated from the galactosamine content of both fractions and the amounts of hydroxy amino acid destroyed. Average chain lengths were also calculated from the xylose and galactosamine content of each fraction. Each independent method gave a value of approximately 28 disaccharide units for the chain length in both fractions and hence their difference in size could not be explained by differences in the length of carbohydrate chains. 8. All fractions contained glucosamine, which was attributed to keratan sulphate. Content of both protein and keratan sulphate increased with the size of the macromolecules. 9. It is suggested, from these results, that chondroitin sulphate-protein complexes normally exist as a heterogeneous population of macromolecules in cartilage, and that keratan sulphate is involved in the formation of larger molecules.

Amino Acids↗
PubMed1969

Characterization of protein-polysaccharides of articular cartilage from mature and immature pigs.

Protein-polysaccharides of femoral articular cartilage from pigs of ages 9 months and 5 weeks were compared after extraction at pH6.8 with iso-osmotic sodium acetate followed by 0.63m-calcium acetate. The cartilage from the younger animals had a higher moisture content and contained considerably larger amounts of protein-polysaccharide, but less than half as much collagen/g. dry weight, than cartilage from the older pigs. There was notably less keratan sulphate in the fractions from the less mature animals. After gel filtration on 6% agarose, elution profiles of the calcium acetate extracts were similar to those of the sodium acetate extracts of the same tissue. Chemical analyses, however, showed that in both age-groups the extraction procedure had achieved a sequential solubilization of protein-polysaccharides in that the initial extracts contained a higher proportion of keratan sulphate than those that were extracted subsequently. Both extracts from the older animals contained up to 25% of a relatively small protein-polysaccharide that was retarded on 6% agarose and that had a lower protein content and less keratan sulphate than the larger protein-polysaccharides. In contrast, in extracts from the less mature cartilage only about 5% of the protein-polysaccharides were small enough to be retarded by 6% agarose, suggesting that the small components may not be precursors of the larger. The average length of chondroitin sulphate chains, as calculated from the analytical data, was the same in the smaller protein-polysaccharides as in the larger.

Animals↗
PubMed1967

Protein-polysaccharides of pig laryngeal cartilage.

1. Protein-polysaccharides of chondroitin 4-sulphate were extracted with neutral calcium chloride from pig laryngeal cartilage that was not completely homogenized. The protein-polysaccharides were purified by precipitation with 9-aminoacridine. On zone electrophoresis in compressed glass fibre at pH7.2 it was separated into two fractions, although two distinct zones were not obtained. These fractions, which had already been shown to differ in their antigenic determinants, also differed considerably in amino acid composition, total protein, hexose and glucosamine contents. 2. The fraction of higher mobility contained approx. 2% of protein and only traces of glucosamine. Serine and glycine accounted for over half the total amino acid residues, but aromatic, basic and sulphur-containing amino acids were not detected. The weight-average molecular weight, determined by sedimentation, was 230000. 3. Assuming that there was the same sequence of neutral sugars at the linkage points as in PP-L fraction (protein-polysaccharide light fraction), the approximate molar ratio of hexose to serine suggested that most of the serine residues were linked to chondroitin sulphate chains. Support for this was derived from the agreement between the weight-average molecular weight of the chondroitin sulphate-peptide after proteolysis, and the chain weight calculated from its serine content. The chain weight based on the serine content of the fraction of higher electrophoretic mobility was approximately similar. 4. In contrast, the fraction of lower electrophoretic mobility resembled PP-L fraction in its amino acid composition, protein and glucosamine contents. The presence of glucosamine, together with the higher hexose content, suggested that this fraction contained some keratan sulphate. 5. The relatively low molecular weight of the fraction of higher mobility enabled it to be extracted without complete disintegration of the cartilage. The unlikelihood of its being produced by autolytic enzymes is discussed.

Acridines↗
PubMedDate not supplied

Direct enzyme transfer from lymphocytes is specific.

Lymphocytes are known to interact directly with other cells in vivo and in vitro, and have recently been shown to transfer the lysosomal enzyme, beta-glucuronidase, to fibroblasts from patients with an inherited deficiency of the enzyme. This process requires cell-cell contact, is unaffected by inhibitors of 'classical' receptor-mediated endocytosis and is abolished by inhibitors of protein synthesis. Although it is not yet known to what extent the transfer of enzymes by direct cellular interaction is a general phenomenon, a similar mechanism could possibly be involved in the transfer of other lysosomal enzymes in vivo and in the exchange of protein in vitro. We show here that the direct transfer of enzymes from lymphocytes to fibroblasts is restricted to only certain lysosomal enzymes.

Animals↗
PubMedDate not supplied

1980 Volvo award in basic science. Proteoglycans in experimental intervertebral disc degeneration.

An animal model of intervertebral disc degeneration induced surgically by ventral nuclear herniation in the rabbit produces morphologic changes of disc degeneration. Histologic characteristics and proteoglycan changes have been studied at various times after herniation. After injury, there was metaplasia into fibrocartilage originating from the cells along the margins of the annular wound, with proliferation of cells changing almost the entire disc space into fibrocartilage. A vertebral osteophyte occurred through an endochondral ossification sequence. Aggregating proteoglycans had two periods of repletion in the early course of degeneration. The water content of the disc was rapidly but only transiently restored in the first two days after herniation, whilst the changes in the total proteoglycan content of the disc paralleled these changes. Hyaluronic acid content decreased rapidly after herniation, but the size of the proteoglycan monomers did not change with degeneration. It is suggested that loss of confined fluid mechanics signals an abortive repair attempt rather than that of biochemical changes in proteoglycans initiate disc degeneration.

Animals↗