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Biomedical subjects

E D Harris

Publications and source records attributed to E D Harris.

At least 19 recordsLinked to original sources
PubMed1979

Native cross-links in collagen fibrils induce resistance to human synovial collagenase.

A model system consisting of highly purified lysyl oxidase and reconstituted lathyritic chick bone collagen fibrils was used to study the effect of collagen cross-linking on collagen degradation by mammalian collagenase. The results indicate that synthesis of approx. 0.1 Schiff-base cross-link per collagen molecule results in a 2--3-fold resistance to human synovial collagenase when compared with un-cross-linked controls or samples incubated in the presence of beta-aminopropionitrile to inhibit cross-linking. These results confirm previous studies utilizing artificially cross-linked collagens, or collagens isolated as insoluble material after cross-linking in vivo, and suggest that increased resistance to collagenase may be one of the earliest effects of cross-linking in vivo. The extent of intermolecular cross-linking among collagen fibrils may provide a mechanism for regulating the rate of collagen catabolism relative to synthesis in normal and pathological conditions.

Aminopropionitrile↗
PubMed1979

Inhibitor of human collagenase from cultures of human tendon.

A potent inhibitor of human collagenases, released from human tendon explants in culture, has been purified and partially characterized. The tendon inhibitor has an estimated molecular weight of 25,000. It is relatively heat-stable but undergoes loss of activity following exposure to trypsin. It inhibits trypsin-activated rheumatoid synovial collagenase as well as the enzyme obtained from polymorphonuclear leukocytes. No inhibition of collagenase from Clostridium histolyticum (clostridiopeptidase A, EC 3.4.24.3) was noted. This collagenase inhibitor may be a factor in the regulation of extracellular connective tissue catabolism.

Cells, Cultured↗
PubMed1979

Collagenase production by synovial fibroblasts treated with phorbol myristate acetate.

A series of intracellular events occurring after treatment of rabbit synovial fibroblasts with 0.01 micrograms/ml phorbol myristate acetate (PMA) were measured. Ten minutes after addition of PMA, there was a temporary increase in intracellular cyclic AMP levels, followed by a transient decrease in incorporation of 3H-thymidine into DNA. Approximately 500 ng/mg cell protein of PGE2 were found in culture medium from the 12- to 24-hour incubation period, but significant collagenase was not detectable until 24 to 36 hours. Treatment with aspirin or indomethacin abolished PGE2 production but did not affect collagenase levels. Production of enzyme was associated with a cessation of cell proliferation, measured by protein content/culture and cell number. No enzyme was detectable in untreated cultures. Synovial fibroblasts treated with phorbol myristate acetate may provide a good model for studies on the mechanism of induction of collagenase production.

Animals↗
PubMed1979

Collagenase production by rheumatoid synovial cells: morphological and immunohistochemical studies of the dendritic cell.

The dendritic cells of dissociated, adherent rheumatoid synovial cell cultures are recognised by their distinctive morphological features--compact cytoplasm around the nucleus and long, branched cytoplasmic extensions. Such cells usually composed approximately 10% of the total adherent cell population but could vary from as few as 2% to as many as 40% with different synovial specimens. Histological studies have shown the cells to contain many mitochondria and large, spherical cytoplasmic inclusions which often distort the dendritic extensions. Although lysosomes were observed, no evidence for phagocytic activity was obtained. Immunolocalisation studies by means of a monospecific antibody to human collagenase have shown that the dendritic cell attached to a collagenous substratum produces and releases this enzyme in vitro. In contrast collagenase was detected in only a few of the fibroblast- and macrophage-like cells, and it was always intracellular. It is proposed that the dendritic cell may have an important role in the pathophysiology of the rheumatoid joint, particularly with regard to collagenase-mediated cartilage destruction.

Arthritis, Rheumatoid↗
PubMed1979

Rheumatoid arthritis: failure of daily heat therapy to affect its progression.

Seventeen volunteers with symmetrical rheumatoid arthritis (RA) applied heat to 1 hand twice daily for 2 years. Joint swelling, joint tenderness and grip strength were measured at intervals. The proliferative aspect of the disease was assessed by roentgenograms using a scoring system. There was no difference between experimental hand and control hand in any of the factors measured. The patients found the heat soothing and comforting. Thus, daily heat therapy did not accelerate the proliferative lesion in RA and may remain as an adjunct to therapy.

Adult↗
PubMed1978

Collagenase immunolocalization in cultures of rheumatoid synovial cells.

Cultures of rheumatoid synovial cells that have been enzymatically dissociated and are adherent to a culture vessel are morphologically heterogeneous. When these cells are cultured on a collagenous substrate for 2 to 6 days at 37 degrees C in serum-free medium, they produce collagenase. A monospecific antibody to human collagenase has localized the enzyme extracellularly around cytoplasmic extensions of dendritic cells and intracellularly within a few macrophage-like and fibroblast-like cells.

Arthritis, Rheumatoid↗
PubMed1978

Binding of latent rheumatoid synovial collagenase to collagen fibrils.

Collagenase released from rheumatoid synovial cells in culture is in a latent form. Subsequently, it may be activated by limited proteolysis. This study was designed to determine whether latent enzyme could bind to collagen fibrils and await activation. The data showed that latent collagenase bound to fibrils equally well at 24 degrees C and 37 degrees C, but that this represented little more than half the binding achieved by active enzyme at temperatures lower than that at which fibrils can be degraded. Binding was not inhibited by the presence of alpha2 macroglobulin, the principal proteinase inhibitor of plasma which cannot complex with inactive or latent collagenase but readily complexes with active species of enzyme. The data support the hypotheses that inactive forms of collagenase accumulate in tissues by binding to substrate, and that activation by proteases such as plasmin initiates collagen breakdown.

Arthritis, Rheumatoid↗
PubMed1978

Non-giant cell temporal arteritis. Three cases and a review of the literature.

We report two cases of polyarteritis and some of hypersensitivity angiitis diagnosed by temporal artery biopsy. Autopsies showed no evidence of giant cell arteritis. A review of the English literature provides seven further autopsy cases of necrotizing vasculitis diagnosed by temporal artery biopsy. The term temporal arteritis includes many types of vasculitis, giant cell arteritis being one of them.

Diagnosis, Differential↗
PubMed1978

Cellular control of collagen breakdown in rheumatoid arthritis.

Remodelling of connective tissue and its destruction in rheumatoid arthritis is related to collagenolysis. Study of collagenase released by rheumatoid synovial cels has indicated that the enzyme is released as latent form from adherent synovial cells in culture. As a latent enzyme it is protected from complexing with alpha2 macroglobulin, the principal proteinase inhibitor. Activation in vivo is very likely caused by proteases which destroy or complex with a portion of collagenase responsible for its latency. Recent data suggest that the latent collagenase is an enzyme-inhibitor complex and not a true zymogen.

Arthritis, Rheumatoid↗
PubMed1978

Activation in vitro of rheumatoid synovial collagenase from cell cultures.

Rheumatoid synovial cells dissociated from matrix and adherent to culture dishes released a latent form of collagenase into culture medium. Previous studies have shown that the latent enzyme does not complex with alpha2-macroglobulin and binds to fibrillar substrate. We now show that serum-free culture medium of the synovial cells contains an inhibitor of collagenase as well as latent enzyme; the two were separated on a column of acrylamide/agarose. Latent collagenase (estimated mol wt 45,000-49,000) was transformed by trypsin to active collagenase of approximately equal to mol wt 33,000. When mixed with inhibitor the active enzyme formed an inactive complex again with approximately equal to mol wt 45,000-49,000. The inhibitor(s) itself was found in one major peak of mol wt 33,000-35,000 and several minor peaks eluting with lower apparent molecular weight. Mersalyl, an organic mercurial compound, effectively activated latent collagenase producing an active enzyme with approximately equal to mol wt 33,000. Bacterial collagenase did not activate latent enzyme. We suggest that latent rheumatoid synovial collagenase, as it is harvested from synovial cells in culture, is an enzyme-inhibitor complex.

Arthritis, Rheumatoid↗
PubMed1977

Endogenous activation of latent collagenase by rheumatoid synovial cells. Evidence for a role of plasminogen activator.

To elucidate the mechanism of synovial damage in rheumatoid arthritis, we studied the activation of latent collagenases released from adherent rheumatoid synovial cells in culture. Latent enzyme was not complexed with alpha2 macroglobulin, the prinicpal proteinase inhibitor in serum, and could be activated by trypsin in the presence of alpha2 macroglobulin if sufficient proteinase was added to saturate inhibitor. Latent collagenase bound half as effectively to collagen fibrils as active enzyme. Plasmin was a threefold better activator of latent enzyme than trypsin and could be generated by addition of plasminogen to synovial-cell cultures. Production of both collagenase and plasminogen activator was inhibited by dexamethasone (10(-9) M). These studies emphasize in importance of control of activation in regulation collagenase activity, It is likely that rheumatoid synovium produces both latent collagenase and plasminogen activator; plasmin is activated from its zymogen, plasminogen, present in inflamed tissues, and in turn activates collagenase.

Arthritis, Rheumatoid↗
PubMed1977

Intracellular collagen fibers at the pannus-cartilage junction in rheumatoid arthritis.

Sections of the pannus-articular cartilage junction from a patient with rheumatoid arthritis (RA) were prepared for electron microscopy. Cells at this interface contained membrane-bound collagen fibrils, apparently in various stages of digestion. Previous studies have demonstrated intracellular collagen fibrils at sites of very active and rapid collagen resorption. It is suggested that at certain times in certain patients with RA, phagocytosis of cartilage collagen fragments and subsequent intracellular digestion may serve as a supplemental pathway to extracellular collagen degradation.

Arthritis, Rheumatoid↗
PubMed1977

Treatment of rheumatoid arthritis with L-histidine: a randomized, placebo-controlled, double-blind trial.

A randomized cooperative double-blind trial of oral L-histidine for the treatment of rheumatoid arthritis was carried out. Patients were treated with either L-histidine 4.5 g daily, or placebo, for 30 weeks. None of the clinical measurements showed an advantage of histidine over placebo. A small decrease in rheumatoid factor titer and a small increase in hematocrit were found only in the histidine group. There was suggestive evidence of a beneficial effect of histidine in patients with more active and prolonged disease, based upon subjective doubld-blind evaluations by physicians and patients. No adverse effects of histidine therapy were noted. Histidine cannot be advocated as a therapeutic agent in rheumatoid arthritis, but further studies in certain groups of patients seem justified.

Arthritis, Rheumatoid↗
PubMed1976

Cleavage of Type II and III collagens with mammalian collagenase: site of cleavage and primary structure at the NH2-terminal portion of the smaller fragment released from both collagens.

Collagenase cleavage of human Type II and III collagens has been studied using a highly purified preparation of rabbit tumor collagenase. Progress of the reactions in solution was followed by viscometry and the results indicated that under the conditions employed Type III collagen molecules were cleaved at approximately five times the rate of Type II molecules. Cleavage products of the reactions were isolated in denatured form by agarose molecular sieve chromatography. The molecular weights and amino acid compositions of the products demonstrated that Type II and III molecules had been cleaved at the characteristic three-quarter, one-quarter locus, giving rise to a large fragment derived from the NH2-terminal portion of the molecule and a smaller fragment representing the COOH-terminal region. The amino acid sequence at the NH2-terminal portion of the smaller fragment derived from Type II collagen was determined to be Ile-Ala-Gly-Gln-Arg, and the corresponding region from Type III collagen was found to have the sequence Leu-Ala Gly-Leu-Arg. These sequences for alpha1(II) and alpha1(III) chains adjacent to the site of collagenase cleavage along with previous data for alpha1(I) and alpha2 chains indicate that the minimum specific sequence required for collagenase cleavage is Gly-Ile-Ala or Gly-Leu-Ala. Inspection of the available sequence data for collagen alpha chains indicates that the latter sequences are found in at least three additional locations at which collagenase cleavage does not occur. Each of the sequences which are apparently not substrates for collagenase, however, are followed by a Gly-X-Hyp sequence. We suggest, then, that a minimum of five residues in collagen alpha chains COOH-terminal to the cleavage site comprise the substrate recognition site.

Amino Acid Sequence↗