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Biomedical subjects

H Muir

Publications and source records attributed to H Muir.

At least 73 records · Page 4Linked to original sources
PubMed1980

Immunochemical localization of collagen types and proteoglycan in pig intervertebral discs.

Antisera were produced which recognized specifically native type I and type II collagens and proteoglycan. These were used in immunofluorescence studies to investigate the distribution of collagens and proteoglycan in intervertebral discs from adult and newborn pigs. Cervical, thoracic and lumbar discs gave similar staining patterns. In the adult, the outer 1 mm of the annulus fibrosus resembled a perichondrium and was negative for type II collagen. The inner regions of the annulus contained proteoglycan and both types of collagen, but these molecules appeared to have separate distributions. The nucleus showed no staining for type I collagen. Newborn pig discs differed from those of the adult in that type II collagen was restricted to the central notochord and to a narrow zone surrounding it. The newborn annulus was negative for type II collagen but reacted strongly with antibodies to both type I collagen and proteoglycan. It is suggested that during development of the pig annulus fibrosus, cells producing type II collagen may migrate into this area from the central regions.

Animals↗
PubMed1979

Proteoglycans of the intervertebral disc. Homology of structure with laryngeal proteoglycans.

The structure of the proteoglycans from normal pig nucleus pulposus and relatively normal human annulus fibrosus and nucleus pulposus was investigated in detail and the results were compared with the current structural model of proteoglycans of hyaline cartilage. Like proteoglycans of cartilage, those of intervertebral disc contain keratan sulphate and chondroitin sulphate attached to a protein core; they are able to aggregate to hyaluronic acid; the protein core likewise has three regions, one lacking glycosaminoglycans, another rich in keratan sulphate and a third region rich in chondroitin sulphate. However, disc proteoglycans contain more keratan sulphate and protein and less chondroitin sulphate and are also considerably smaller than cartilage proteoglycans. In proteoglycans of human discs, these differences appeared to be due principally to a shorter region of the core protein bearing the chondroitin sulphate chains, whereas in proteoglycans of pig discs their smaller size and relatively low uronic acid content were due to shorter chondroitin sulphate chains. There were subtle differences between proteoglycans from the nucleus and annulus of human discs. In the latter a higher proportion of proteoglycans was capable of binding to hyaluronate.

Adolescent↗
PubMed1979

Proteoglycans of the intervertebral disc. Absence of degradation during the isolation of proteoglycans from the intervertebral disc.

Proteoglycans extracted with 4M-guanidinium chloride from pig intervetebral discs, and purified by equilibrium density-gradient centrifugation in CsCl, were of smaller hydrodynamic size than those extracted and purified in the same way from the laryngeal cartilage of the same animal. Whether this difference in size arose from degradation during the extraction and purification of the proteoglycans of the disc was investigated. Purified proteoglycans labelled either in the chondroitin sulphate chains or in the core protein were obtained from laryngeal cartilage by short-term organ culture. These labelled proteoglycans were added at the beginning of the extraction of the disc proteoglycans, and labelled cartilage and unlabelled disc proteoglycans were isolated and purified together. There was no appreciable loss of radioactivity after density-gradient centrifugation nor decrease in hydrodynamic size of the labelled cartilage proteoglycans on chromatography on Sepharose 2B, when these were present during the extraction of disc proteoglycans. It is concluded that disc proteoglycans are intrinsically of smaller size than cartilage proteoglycans and this difference in size does not arise from degradation during the extraction.

Animals↗
PubMed1979

Synthesis of sulphated proteoglycans by rheumatoid and normal synovial tissue in culture.

Synthesis of sulphated proteoglycans by cell lines derived from explants of 7 rheumatoid and 9 normal specimens of synovial tissue, as well as by 7 lines of skin fibroblasts from non-rheumatoid patients, was examined. Cells of all 3 types were cultured as monolayers. They were then disaggregated and their capacity to synthesise proteoglycan estimated in cell suspensions by the incorporation of [35S]-sulphate into CPC-precipitable material during 2 hours of incubation. Cell suspensions incorporated somewhat more [35S]-sulphate than corresponding duplicate monolayers. Synovial cells from rheumatoid patients incorporated 2 to 3 times as much [35S]-sulphate as synovial cells from normals. Skin fibroblasts, however, incorporated less [35S]-sulphate than rheumatoid or normal synovial cells up to the fifth passage. Thereafter their incorporation gradually increased to overtake that of synovial cells. About one-half to one-third of the total [35S]-sulphate labelled material was closely associated with cells from synovial tissues and fibroblasts respectively.

Adolescent↗
PubMed1979

Enzyme replacement therapy by fibroblast transplantation: long-term biochemical study in three cases of Hunter's syndrome.

We have assessed the effectiveness of transplanted histocompatible fibroblasts as a long-lived source of lysosomal enzymes for replacement therapy in three patients with Hunter's syndrome, over periods ranging from 2.5 to 3.75 yr. The level of Hunter corrective factor excreted by all three patients increased after transplantation, as did the activity of alpha-L-idurono-2-sulfate sulfatase in serum, when measured directly with a radioactive disulfated disaccharide substrate. Sulfatase activity was also raised in leukocyte homogenates from the two patients that we were able to assess. These increases in enzyme activity were accompanied by corresponding increases in catabolism of heparan and dermatan sulfates, as shown by (a) a decrease in sulfate:uronic ratios of urinary oligosaccharides, (b) an increase in iduronic acid monosaccharide, and (c) a normalization of Bio-Gel P-2 gel filtration profiles. Both the increase in enzyme activity and increased catabolism were maintained during the period of study and were not affected by either a gradual decrease or total withdrawal of immunosuppressive therapy.

Child↗
PubMed1978

Characterization of proteoglycan and the proteoglycan--hyaluronic acid complex by electric birefringence.

An electric field causes partial alignment of macromolecules in a dilute solution. The accompanying changes in the solution birefringence offer a sensitive and quick means of monitoring the rates of particle orientation and hence the size of the solute molecules. Such measurements are reported for dilute solutions of proteoglycans in the absence and presence of added hyaluronic acid. The proteoglycan molecules are shown to be some 580 nm long. In the presence of hyaluronic acid they form aggregates that appear to be consistent with the model previously proposed in which the proteoglycans attach radially to the extended hyaluronic acid chain. The electric-birefringence relaxation rates indicate aggregates of similar length to that of the extended hyaluronic acid chain, with the proteoglycans spaced on average at 29nm intervals. A proteoglycan sample the cystine residues of which had been reduced and alkylated showed no evidence of aggregation with hyaluronic acid up to the concentrations of the acid corresponding to 1% of the total uronic acid content. The electric-birefringence method is shown to have a large potential in the study of associating polysaccharide solutions.

Alkylation↗
PubMed1977

Synthesis of cartilage-specific proteoglycan by suspension cultures of adult chondrocytes.

Chondrocytes isolated from larynges of adult pigs were cultured as cell suspensions for at least 4 days before use. During continuous-labelling experiments in nutrient medium for 18h with 35SO42- and [3H]glucosamine as precursors, some macromolecular polyanionic material was synthesized which behaved on gel chromatography as proteoglycan. Gel chromatography on Sepharose 2B showed that a proportion of the proteoglycans in the medium appeared to be aggregated, and was dissociated in 4M-guanidinium chloride. Moreover the dissociated proteoglycan interacted with hyaluronic acid. Newly synthesized proteoglycan was larger than the average total cetylpyridinium chloride-precipitable material assayed as uronic acid alone.

Animals↗
PubMed1977

Biochemical aspects of development and ageing of human lumbar intervertebral discs.

Nucleus pulposus and annulus fibrosus from individual normal discs of different ages have been separately examined, and the topographical distribution of constituents across the annulus fibrosus has been determined. Collagen content, including the molecular species, and proteoglycans have been estimated. Type I collagen was found in the outermost regions of the annulus and type II in the innermost, whereas the nucleus contained type II collagen. In older spines the collagen content of the annuli increased both outwards in the disc, and downwards along the spinal levels. Proteoglycan content was higher in the nucleus, and the proportion of keratan to chondroitin sulphate increased with age, as did the hyaluronate content. It is concluded that differences in mechanical function may be reflected by differences in chemical composition of the discs, and that mechanical failure could result from local variations in chemical composition.

Adolescent↗
PubMed1977

Synthesis of proteoglycans by suspension and monolayer cultures of adult chondrocytes and de novo cartilage nodules-the effect of hyaluronic acid.

Chondrocytes were isolated from adult laryngeal cartilage by an enzymic procedure that included 6 h digestion with collagenase. The level of 35SO4(2-) incorporation into cetylpyridinium chloride-precipitable material by these cells depended upon the subsequent culturing conditions. Suspension cultures incorporated more 35SO4(2-)/cell than monolayer cultures. Hyaluronic acid in the medium inhibited 35SO4(2-) incorporation only when the cells were in primary suspension cultures. It had no effect on monolayer cultures, or monolayers organized into nodules, or suspension cultures derived from monolayers. Mild pretreatment with EDTA, however, rendered these susceptible to hyaluronic acid inhibition. In contrast EDTA abolished the inhibitory effect of hyaluronic acid on primary suspension cultures. Oligosaccharides, derived from hyaluronidase digestion of hyaluronic acid that were larger than decassaccharide, had some inhibitor effect on 35SO4(2-) incorporation by monolayer cultures. The total 35SO4(2-) incorporation was less in primary suspension cultures of chondrocytes isolated after 12 h than after 6 h digestion of cartilage and the inhibition by hyaluronic acid was also less. These differences persisted during 12 days of culture. It is suggested that the method of isolating chondrocytes and subsequent culture conditions may modify the cell surface and mask or abolish specific binding sites for hyaluronic acid.

Animals↗
PubMed1977

An experimental model of osteoarthritis; early morphological and biochemical changes.

An experimental model of osteoarthritis resulting from laxity of the joint was induced in eighteen mature dogs (at least two years old) by sectioning the anterior cruciate ligament of the right knee (stifle) with a stab incision, the left knee providing a control. A sham operation was also performed in three other dogs, in which a stab incision was made but the ligament left intact. The dogs were killed at various intervals from one to forty-eight weeks later. Morphological changes in bone, cartilage, synovial membrane and joint capsule were examined in all the joints and biochemical changes in the cartilage of three dogs killed after two, eight, and sixteen weeks. All the changes resulting from the operation progressed with time and became indistinguishable from those found in three dogs with natural osteoarthritis of the knee. There were no changes in the joints which had sham operations. As the time of onset is known, this experimental model in a larger species enables a study to be made of the biochemical as well as the morphological changes in the early stages of osteoarthritis.

Animals↗