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Biomedical subjects

E D Harris

Publications and source records attributed to E D Harris.

At least 127 records · Page 7Linked to original sources
PubMed1982

Effects of all-trans-retinoic acid (retinoic acid) and 4-hydroxyphenylretinamide on synovial cells and articular cartilage.

We studied the effects of two retinoids, naturally occurring all-trans-retinoic acid (retinoic acid) and the synthetic 4-hydroxyphenylretinamide (4-OH-PRT) on monolayer cultures of rabbit synovial fibroblasts and on explants of rabbit articular cartilage. Treatment of fibroblasts with phorbol myristate acetate (PMA; 10(-8) M) induced the synthesis and secretion of large amounts of collagenase: this was inhibited if the cells were treated with retinoic acid (10(-6) M) or dexamethasone (10(-7 M). Combined treatment with retinoic acid and the steroid prednisolone, at concentrations as low as 19(-10) M, gave an additive inhibition of collagenase production. Both retinoids inhibited collagenase production, but only 4-OH-PRT prevented the increase in prostaglandin E2 (PGE2) induced by PMA. Levels of plasminogen activator were also increased by treatment with PMA, and concomitant addition of either retinoid further enhanced this stimulation. Possible toxicity was assessed by measuring release of glycosaminoglycans (GAG) from explants of articular cartilage. Treatment with retinoic acid induced release of 80% of the total GAG, whereas treatment with 4-OH-PRT resulted in release of 40% of the total, a finding similar to that seen with untreated samples. 4-OH-PRT inhibited production of collagenase and PGE2 by rabbit synovial fibroblasts but was not toxic to articular cartilage.

Animals↗
PubMed1981

A precursor form of latent collagenase produced in a cell-free system with mRNA from rabbit synovial cells.

mRNA extracted from rabbit synovial fibroblasts which had been induced to produce large amounts of collagenase (EC 3.4.23.7) by urate crystals was translated in a cell-free wheat germ system. Collagenase was identified by immunoprecipitation using mono-specific antibody to rabbit synovial collagenase. In the absence of microsomal membranes, a single precursor with Mr = 59,000 was synthesized. This polypeptide was susceptible to proteolytic degradation. In the presence of canine pancreatic microsomes, the nascent protein was processed to a polypeptide with Mr = 57,000 (identical in mobility on sodium dodecyl sulfate-gel electrophoresis to the major latent collagenase secreted from cells) and was protected from tryptic digestion unless a detergent was used to disrupt the membranes. In addition to Mr = 57,000 material, cells secreted immunologically reactive latent collagenase with Mr = 61,000. High molecular weight collagenase was separated from Mr = 57,000 species by binding to concanavalin a-Sepharose, suggesting that this enzyme was a product of post-translational glycosylation. Both latent enzymes were activated by trypsin and human plasma kallikrein to Mr = 45,000 and 49,000. The evidence indicates that rabbit synovial fibroblast collagenase is synthesized and secreted as a single polypeptide zymogen, not as an enzyme-inhibitor complex.

Animals↗
PubMed1981

Proliferative diseases.

A unifying concept that excessive proliferation of cells and turnover of cellular matrix contribute significantly to the pathogenesis of several diseases, including cancer, atherosclerosis, rheumatoid arthritis, psoriasis, idiopathic pulmonary fibrosis, scleroderma and cirrhosis of the liver, is presented. As corollaries to this concept, the following topics are considered: (1) the role of polypeptide hormones and hormone-like mediators in the initiation, promotion and maintenance of proliferative responses; (2) alterations in collagen metabolism and collagenase activity; (3) the role of proteinases; (4) the potential use of inhibitors of proteinases for prevention of disease; and (5) the potential use of inhibitors of proliferative polypeptide hormones for prevention of disease. As specific proteolytic and proliferative biochemical mechanisms which contribute to the pathogenesis of disease become identified, there is a unique opportunity to develop new pharmacologic methods of prevention.

Cell Division↗
PubMed1981

Preparation of a monospecific antibody to purified rabbit synovial fibroblast collagenase.

Collagenase produced by monolayer cultures of rabbit synovial fibroblasts was purified from serum-free culture medium. Antiserum to the pure preparation was raised in sheep. The IgG fraction has been isolated and characterized and shown to be specific for collagenase. The antibody is capable of precipitating and inhibiting the activity of both latent and activated rabbit synovial fibroblast collagenase. Cross-reactivity with human antigen from rheumatoid synovial cell culture medium is described.

Animals↗
PubMed1981

A postabsorption effect of L-ascorbic acid on copper metabolism in chicks.

We have studied the effect of L-ascorbic acid (vitamin C) on copper metabolism using copper-deficient chicks and the activation of lysyl oxidase copper-dependent enzyme, to assess bioavailability of copper. When administered intraperitoneally with (or 75 minutes before) CuSO4, L-ascorbate significantly impared the effectiveness of copper to restore lysyl oxidase activity in deficient chicks. L-ascorbate given 75 minutes after CuSO4 (i.e., in the post-absorption period), however, produced a substantial increase in copper-induced enzyme activation. L-ascorbate by itself showed no direct stimulating effect in deficient chicks. When the L-ascorbate was given to chicks that had received adequate dietary copper, there was a strong rise in ceruloplasmin and a slight, but significant increase in lysyl oxidase. An increase in ceruloplasmin in response to copper was also seen in deficient chicks and L-ascorbate also augmented that increase. Substituting D-isoascorbic acid for antagonistic properties of L-ascorbic acid on copper metabolism, but they also reveal possible sterospecific postabsorption roles for L-ascorbate in the metabolism of copper.

Absorption↗
PubMed1981

Iron increases collagenase production by rabbit synovial fibroblasts.

Ionic iron, as the chelate FeNTA, was taken up by rabbit synovial fibroblasts in monolayer culture. Uptake was accompanied by increased production of latent collagenase and PGE2. Concomitant addition of desferrioxamine, a specific chelator of Fe+++, prevented iron uptake and induction of collagenase and PGE2. Collagenase induced by iron may have a role in the pathogenesis of certain disease states associated with abnormal iron deposition.

Animals↗
PubMed1981

Survival of rheumatoid synovium implanted into nude mice.

The gross morphologic features, histologic features, and synthesis of collagenase and prostaglandin E2 by rheumatoid synovial cells injected into athymic nude mice were studied. A single cell suspension of 2 X 10(7) cells was inoculated subcutaneously into the dorsum of each mouse. In 8 out of 9 mice injected with cells from 6 different patients, rheumatoid synovial cells remained at the injection site for 20-30 days. During this time they became organized into a pannuslike structure with fibroblasts, occasional multinucleated cells, numerous blood vessels, and diffuse collagen fibers. No lymphocytes were seen. Compared with cells cultured in vitro at Day 0, removal, dissociation, and culture of the implanted material at Day 21 revealed a decrease in the percentage of dendritic (stellate) cells known to be associated with collagenase and PGE2 production. However, cells passed through nude mice retained the ability to synthesize both of these compounds. Implantation of rheumatoid synovium into nude mice may provide a way of studying factors influencing the proliferative and destructive lesion of rheumatoid arthritis.

Animals↗
PubMed1980

Localization of lysyl oxidase in hen oviduct: implications in egg shell membrane formation and composition.

Lysyl oxidase activity was found in the isthmus (the membrane-forming region) of the hen's oviduct in a copper-rich region proximal to the shell gland. Desmosine and isodesmosine, cross-linking compounds associated with mature elastin, were found in hydrolysates of the shell membrane, confirming the necessity for lysyl oxidase in its biosynthesis. Shell membranes from hens fed a copper-deficient diet or a diet supplemented with beta-aminopropionitrile had a reduced content of desmosine and isodesmosine.

Amino Acid Oxidoreductases↗
PubMed1980

Copper and the synthesis of elastin and collagen.

Copper's role in connective tissue is linked to the enzyme lysyl oxidase. From a biochemical perspective, copper is a cofactor for the enzyme and a determinant of its activity in connective tissues. Lysyl oxidase catalyses a post-translational oxidation of certain lysine and hydroxylysine residues. The peptidyl aldehydes so formed become active centres for the formation of cross-links in collagen and elastin. Less well understood is how copper controls the steady-state activity of lysyl oxidase; the enzyme fails in copper deficiency. Giving copper to a deprived animal increases lysyl oxidase activity in aortic tissue. Such activation in vivo appears to require caeruloplasmin. Suspending aortic tissue in a copper-enriched growth medium also activates lysyl oxidase provided that tissue structure is kept intact. Activation in vitro occurs with the binding of copper to a large-molecular-weight component, presumably the enzyme. Binding will not occur if protein synthesis is blocked. These studies clearly show that the synthesis of mature elastin and collagen can be controlled by the availability of copper. They further suggest that transport of copper to aortic tissue and its engagement to lysyl oxidase are linked to the synthesis or lysyl oxidase, an extracellular carrier, or both.

Amino Acid Oxidoreductases↗
PubMed1980

Elevated levels of collagenase and prostaglandin E2 from synovium associated with erosion of cartilage and bone in a patient with chronic Lyme arthritis.

A patient with chronic Lyme arthritis and roentgenographic evidence of bony erosion underwent a synovectomy; proliferative synovium (pannus), containing aggregates of small lymphocytes, was found adherent to eroded cartilage and bone. During 8 days in tissue culture, the synovial cells produced large amounts of collagenase and prostaglandin E2, but only low levels of both neutral and acid proteinases. Sixty-seven percent of the lymphocytes from the synovium were T cells; 19% were B cells. Attempts to identify agent/antigen in the synovial cells were unsuccessful. Thus, the synovium of this patient, whose disease appears to be tick-transmitted, resembles that of rheumatoid arthritis. This finding further supports the hypothesis that many possible agents, including infectious ones, trigger a common pathway in synovium, which leads to joint destruction.

Adult↗