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Biomedical subjects

J T Dingle

Publications and source records attributed to J T Dingle.

At least 37 records · Page 2Linked to original sources
PubMed1986

Porcine heart valves produce a protein that induces cell-mediated connective tissue degradation: I. Biological properties.

Cultured porcine heart valves secrete a factor that induces cells to degrade their extracellular matrix. This activity was routinely monitored by measuring the release of glycosaminoglycans from proteoglycan in cultured bovine nasal cartilage. It was observed that factor-mediated matrix degradation was dose dependent and required live target cells, while factor production by valves was inhibited by cycloheximide and declined with reduced cell viability. The effect of various steroidal and nonsteroidal anti-inflammatory drugs on the production and activity of the factor is discussed with reference to similar cytokines. It is concluded that there is a close similarity between the cardiac catabolic factor described here and catabolin, a protein isolated from porcine synovia and leukocytes, as shown by the neutralization of biological activity with antisera raised to porcine catabolin (interleukin-1).

Animals↗
PubMed1986

Porcine heart valves produce a protein that induces cell-mediated connective tissue degradation: II. Biochemical properties of the partially purified protein.

A cardiac catabolic factor (CCF) has been partially purified from serum-free medium conditioned by minced porcine heart valves. CCF was prepared by a series of chromatographic techniques and compared directly with porcine synovial catabolin purified by the same protocol. CCF displayed a somewhat higher molecular weight (Mr 21,000) and isoelectric point (pI 5.2) than did synovial catabolin (Mr 18,000 and pI 4.8), but the two factors clearly resemble one another closely. CCF stimulated the release of glycosaminoglycans from cultured cartilage and mitral valve and provoked porcine valves to degrade their own collagen extracellular matrix. The release of hydroxyproline was inhibited by corticosteroids, whereas proteoglycan breakdown was not. Partially pure preparations of CCF and synovial catabolin stimulated murine thymocyte proliferation; moreover, that activity was almost totally abolished by an antibody raised against pure porcine interleukin-1. These observations suggest that CCF may represent a catabolic factor that belongs to the interleukin-1 family and that it could potentially regulate the composition of valvular connective tissue.

Animals↗
PubMed1986

Characterization of a specific antiserum for mammalian collagenase from several species: immunolocalization of collagenase in rabbit chondrocytes and uterus.

A specific antiserum to rabbit bone collagenase was raised in a sheep and shown to react with collagenase from several mammalian species. This antiserum was used to demonstrate that only active collagenase binds to and can be immunolocalized on collagen fibrils and, by indirect immunofluorescence, the secretion of latent collagenase by stimulated rabbit chondrocytes and cells of the post-partum involuting rabbit uterus. The ionophore monensin was used to demonstrate intracellular accumulation of collagenase in the Golgi apparatus of both stimulated chondrocytes and involuting uterine cells. Collagenase was not detectable in either normal cartilage or non-gravid uterus. These results are discussed in relation to other studies of collagenase immunolocalization reported in the literature.

Animals↗
PubMed1985

A catabolin-like factor from porcine kidney.

Explants of pig kidney cortex and medulla release a catabolin-like factor (CLF). The CLF of both kidney cortex and medulla can be precipitated with ammonium sulphate, mainly in the 60-95 per cent fraction. By gel chromatography the kidney CLF showed a major active fraction at a molecular weight of around 22 500. Whole glomeruli and dissociated glomerular cells in culture also released into the medium a CLF that could be bioassayed in live cartilage but displayed no effect on dead cartilage. The possible role of such a local hormone is discussed.

Animals↗
PubMed1984

The effect of synovial catabolin on cartilage synthetic activity.

The effect of porcine synovial catabolin on the incorporation of [3H]amino acids and [35S]sulfate into bovine nasal cartilage was investigated. The rapid breakdown of matrix caused by partially purified catabolin had little affect on the incorporation of [3H]amino acids but there was inhibition of [35S]sulfate uptake. While the 35S-labelled material released into the medium was largely incapable of aggregation with hyaluronate, this was only a small part (less than 10%) of the total incorporated. The principal inhibitory action was in the formation of large molecular size material (guanidinium chloride extractable). The amount of newly synthesized glycosaminoglycans (GAG) during the 8 day culture period was too low (less than 0.8%) to influence the very rapid breakdown of the matrix under catabolin stimulation. Cartilage organ cultures recovered from inhibition of [35S]sulfate incorporation and from the catabolic stimulation after removal of catabolin. It is suggested that the two properties of the catabolin preparation demonstrated in this study may work synergistically both in causing and prolonging cartilage damage in vivo.

Animals↗
PubMed1983

Intracellular catabolin-like activity in cultured synovial tissue.

The time course of the synthesis and secretion of catabolin-like activity by porcine synovial tissue was determined. Ex vivo tissue had no demonstrable activity, but short-term culture (less than 1 h) induced cellular accumulation of activity. This accumulation, which preceded secretion, was reversibly inhibited by cycloheximide. The activity was localized in the cystol fraction.

Animals↗
PubMed1983

The role of catabolin in the control of cartilage matrix integrity.

Living articular cartilage may be stimulated to degrade its matrix totally by the influence of catabolic messengers. One such messenger which has been isolated and purified from synovial tissue and blood leukocytes is catabolin. This is a 20,000 molecular weight pI 4.5 protein, which acts on living chondrocytes in subnanogram concentrations. Studies on its synthesis, translocation, and secretion from synovial tissue are reported. Its secretion, but not its principal function, is inhibited by cortisol. Its mode of action appears to be in invoking catabolic responses from effector cells. It may also inhibit the synthesis of matrix components. The possible role of catabolin and other messengers in arthritis will be considered.

Arthritis, Rheumatoid↗
PubMed1982

Cardiac catabolic factors: the degradation of heart valve intercellular matrix.

Cultures of porcine heart valves and aorta secrete a factor that stimulates the degradation of cartilage matrix in a fashion similar to that displayed by synovial catabolin. The heart valve factor also induces the release of chondroitin sulfate and hydroxyproline from isolated heart valve cultures. The present observations support the hypothesis that tissues producing catabolic factors (catabolins) may well be responsive to them and that these messengers may play a role in the cellular regulation of the degradation of intercellular macromolecules.

Animals↗
PubMed1982

Evidence that extracellular cathepsin D is not responsible for the resorption of cartilage matrix in culture.

Cathepsin D, the major lysosomal aspartic proteinase, is responsible for the autolysis of cartilage at slightly acidic pH, and it has been suspected of making a significant contribution to the breakdown of the living tissue, such as in stimulated by retinol. Our finding, however, has been that neither inhibitory antibodies against cathepsin D, nor chemical inhibition with pepstatin, significantly decreases the rate of degradation of proteoglycan in the organ culture system. Most of the other proteinase inhibitors tested were similarly ineffective, although the EDTA and 1,10-phenanthroline inhibited the resorption by a cytotoxic effect. We conclude that although cartilage matrix degradation has clear characteristics of proteolytic process, the identity of the enzyme(s) responsible remains obscure.

Animals↗
PubMed1982

Effects of antirheumatoid drugs on the production and action of porcine catabolin.

We report the effects of some common antirheumatic drugs on the production of catabolin from synovium and on its action on cartilage. A method is described to generate reproducible amounts of catabolin from synovial mince. Aspirin, Clozic (ICI 55,897), and gold were without effect on the catabolin system. Penicillamine at high doses enhanced the action of catabolin, while chloroquine inhibited catabolin's effect on cartilage. Prednisolone inhibited the production of catabolin without affecting its action. This inhibition was produced by very low doses of prednisolone (25 ng/ml) and was dose-dependent.

Animals↗
PubMed1981

A possible role for catabolin in tissue remodelling and repair.

Catabolin is a recently discovered polypeptide of 17 000 molecular weight which stimulates connective and skeletal tissue cells to degrade their extracellular matrix. It is produced by a variety of cell types and is believed to be part of a family of cellular messengers which interact to control tissue remodelling and repair in both physiological and pathological situations.

Animals↗
PubMed1981

Human mononuclear cell factors mediate cartilage matrix degradation through chondrocyte activation.

Human blood mononuclear cells (BMC) in short-term culture secrete one or more factors that induce degradation of matrix proteoglycan and collagen in cartilage explants in organ culture. Induction of matrix degradation took place both in nasal septum and articular cartilage explants in the presence of the mononuclear cell supernates. Cartilage degradation in this system was absolutely dependent on the presence of live chondrocytes. Matrix depletion did not occur in dead cartilage explants cultured with active supernates. Supernates obtained from unstimulated BMC showed variable cartilage matrix degrading activity (MDA). BMC stimulated with phytohemagglutinin (PHA) showed increased MDA, which in one dilution experiment was found to be five times higher than that in the unstimulated control supernate. Concanavalin A and pokeweed mitogen were also shown to stimulate release of MDA. Time experiments showed that most of the degrading activity was released by the mononuclear cells during the first day of culture. The cellular origin of MDA was investigated with the aid of partially purified BMC subpopulations. Removal of adherent cells resulted in a decrease of MDA release. Purified T lymphocytes failed to show enhanced MDA release in spite of their ability to mount a virtually intact proliferative response to PHA. Purified adherent cells also failed to show enhanced PHA-dependent MDA release. Nevertheless, restoration of PHA-dependent MDA release took place in reconstituted cell populations containing both T lymphocytes and monocytes. These experiments suggest that MDA may be released by adherent mononuclear cells, presumably monocytes, and that the PHA-dependent increase in MDA release may be mediated by T lymphocytes. Partial characterization of MDA by gel chromatography showed one active fraction corresponding to an apparent molecular weight ranging from 12,000 to 20,000. The fraction was also shown to degrade cartilage matrix only in the presence of live chondrocytes. These results demonstrate that factors released by human BMC mediate degradation of matrix proteoglycan and collagen in intact cartilage explants through chondrocyte activation. This pathogenic mechanism may play a role in in vivo cartilage destruction in chronic inflammatory joint diseases.

Animals↗
PubMed1981

Catabolin--a cartilage catabolic factor from synovium.

Resorption of cartilage matrix is usually considered to be due to extrinsic proteases, generally thought to be the neutral metalloproteases, including collagenase. Such enzymes can be secreted from synovial tissue and in acute forms of arthritis they are believed to be the main agents of pannus erosion. However, such enzyme secretion has not been clearly demonstrated to be the causative agent in either rheumatoid arthritis or in osteoarthritis. For example, no specific inhibitors of these proteinases have yet been proved effective in vivo. Recent experiments at the Strangeways Research Laboratory have demonstrated that viable chondrocytes of animal and human articular cartilage are capable of resorbing their surrounding matrix without the aid of extrinsic enzymes. We now know that such resorption can be stimulated by the action of a low molecular weight peptide released from living synovial and other connective tissues. These messengers (catabolins) are capable of stimulating chondrocytes to degrade totally both proteoglycan and collagen. The purification, properties, regulation and action of catabolism are under investigation to determine the role for catabolin in arthritis.

Animals↗
PubMed1980

Interaction of dinitrophenyl-pepstatins with human cathepsin D and with anti-dinitrophenyl antibody. Development of potential reagents for the localization in vivo of active proteinases at sites of tissue injury.

Extracellular cathepsin D has been observed by various cytochemical methods at sites of tissue injury. However, the role of this enzyme in connective tissue matrix degradation is uncertain because there are no histochemical methods for determining whether or not the cathepsin D is active at such sites in living tissues. We considered that the combined use of a labelled tight-binding inhibitor with immunoprecipitation of the enzymes might overcome this problem. We have explored the application of derivatives of the inhibitor pepstatin, as only active cathepsin D binds pepstatin tightly. A series of N-pepstatinyl-N'-dinitrophenyl-alpha, omega-diaminoalkanes were synthesized with alkyl-chain lengths of two, four and six carbon atoms. These compounds were tight-binding inhibitors of human cathepsin D. In fluorescence-quenching titrations the dinitrophenyl groups were also fully available to bind high-affinity anti-dinitrophenyl antibody. It was shown by immunodiffusion in gels and by gel permeation chromatography that N-pepstatinyl-N'-dinitrophenyl-1,6-diaminohexane was a bifunction inhibitor able to bind cathepsin D and anti-dinitrophenyl antibody at the same time.

Antibody Affinity↗
PubMed1980

The site of cartilage matrix degradation.

1. A 'cavity' organ culture method was developed, which allowed the insertion within bovine nasal cartilage of 10 microliter of 35S-labelled proteoglycan aggregate. 2. Stimulation of the tissue with retinol or catabolin led to degradation of both the cartilage matrix and the proteoglycan within the cavity. 3. Proteoglycan aggregate trapped in polyacrylamide beads was not broken down in the cavities of living cartilage, except under autolytic conditions. 4. It is suggested that degradation of proteoglycan aggregate by chondrocytes occurs in a pericellular region.

Acrylamides↗
PubMed1980

Lysosomal alterations in hypoxic and reoxygenated hearts. II. Immunohistochemical and biochemical changes in cathepsin D.

Sublethal hypoxic injury in rat and rabbit hearts was accompanied by a biochemical redistribution of cathepsin D activity from the particulate to the supernatant fraction of the tissue homogenate, which was partially reversible on reoxygenation. Immunofluorescent staining for cathepsin D failed to reveal major anatomic release of the acid hydrolase until necrosis was present, suggesting that the earlier biochemical redistribution was primarily a result of increased lysosomal fragility during homogenization, with significant intracellular diffusion of the enzyme occurring only as irreversible damage took place. Hypoxia produced enlargement of both cathepsin-D-staining lysosomes and nonstaining vacuoles, as well as their aggregation. These changes were intensified during reoxygenation and recovery of reversibly damaged hearts, suggesting a possible role for the lysosomal-vacuolar apparatus in myocytic repair following hypoxic injury.

Animals↗