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Biomedical subjects

D A Kalbhen

Publications and source records attributed to D A Kalbhen.

At least 19 recordsLinked to original sources
PubMed1997

The proteoglycan metabolism, morphology and viability of articular cartilage treated with a synthetic matrix metalloproteinase inhibitor.

Matrix metalloproteinases (MMP) are among the key enzymes responsible for the proteolytic destruction of articular cartilage during chronic rheumatic diseases. Articular cartilage is one potential target for drugs designed to inhibit the activity of MMPs in order to stop or to slow down the proteolytic destruction of the extracellular matrix of cartilage. The purpose of this study was to investigate the effect of the synthetic inhibitor of MMPs U-24522 for its ability (1) to inhibit in vitro the activity of MMP-proteoglycanases; (2) to modulate the morphology and viability of cartilage explants; and (3) to modify the biosynthesis and release of proteoglycans from articular cartilage explants. U-24522 dose-dependently inhibited the activity of MMP-proteoglycanases and significantly reduced the release of proteoglycans from interleukin-1 treated bovine articular cartilage explants when tested at concentrations ranging from 10(-4) to 10(-9) M. This hydroxamic acid derivative proved not to be harmful to chondrocyte viability and cartilage morphology. In addition, U-24522 had no effect on the rate of proteoglycan biosynthesis of interleukin-1 treated cartilage explants and increased the percentage of newly synthesized proteoglycans to form macromolecular aggregates. Thus U-24522 combines direct inhibitory potential on the activity of MMP-proteoglycanases with the inhibition of interleukin-1 stimulated proteoglycan loss from articular cartilage explants without affecting the morphology, viability and biosynthesis of proteoglycans of bovine articular cartilage explants.

Animals↗
PubMed1997

Effects of the hydroxamic acid derivate Ro 31-4724 on the metabolism and morphology of interleukin-1-treated cartilage explants.

Matrix metalloproteinases (MMPs) belong to the key enzymes of the proteolytic destruction of cartilage matrix during chronic rheumatic diseases. Our work focused on the inhibitory potential of the hydroxamate Ro 31-4724 on the activity of MMP-proteoglycanases as well as on the viability, morphology and proteoglycan metabolism of interleukin-1 (IL-1)-treated bovine articular cartilage explants. The in vitro activity of MMP-proteoglycanases as well as the release of proteoglycans from IL-1-treated cartilage explants were significantly and concentration-dependently inhibited by Ro 31-4724 tested at concentrations ranging from 1 nmol/l to 10 mumol/l. Histopathological evaluation of sections from cartilage explants treated with this drug revealed no microscopically discernible alterations, and did not show any cytotoxic effects of Ro 31-4724. In addition, Ro 31-4724 had no effect on the rate of proteoglycan biosynthesis by IL-1-treated cartilage explants and increased the percentage of newly synthesized proteoglycans to form macromolecular aggregates. In conclusion, Ro 31-4724 displayed MMP-proteoglycanase inhibitory activity both in vitro and ex vivo and proved to be not harmful to the morphology, viability and proteoglycan biosynthesis of bovine articular cartilage explants.

Animals↗
PubMed1996

The inhibitory effects of antirheumatic drugs on the activity of human leukocyte elastase and cathepsin G.

The serine proteinases elastase and cathepsin G from polymorphonuclear granulocytes play a critical role in articular cartilage degradation, not only as proteolytic enzymes able to degrade the extracellular matrix but also by additionally modulating the level of active matrix metalloproteinases, key enzymes of the proteolytic destruction of cartilage during rheumatoid arthritis. The aim of our study was to examine whether anti-inflammatory drugs and selected compounds inhibited elastase and cathepsin G, and also to determine whether it is necessary to use a highly purified elastase preparation to screen drugs for their ability to block the activity of this enzyme. Eglin C and the glycosaminoglycan-peptide complex DAK-16, at concentrations ranging from 10(-9) to 10(-4) M, dose-dependently inhibited elastase and cathepsin G while the nonsteroidal anti-inflammatory drugs oxyphenbutazone, phenylbutazone, sulfinpyrazone and diclofenac-Na required high concentrations to demonstrate some inhibitory effects on the activity of both enzymes. None of the other anti-inflammatory drugs tested at a concentration of 10(-4) M such as acetylsalicylic acid, dexamethasone, indomethacin, ketoprofen, naproxen, oxaceprol, pirprofen and tiaprofenic acid demonstrated any marked inhibitory activity on either of these proteinases. Only a few drugs, when dosed therapeutically, achieved synovial fluid concentrations sufficient to inhibit the activities of both proteinases. The antirheumatic drugs demonstrated similar inhibition profiles in purified or partially purified elastase preparations. Thus the leukocyte extract containing the partially purified elastase and cathepsin G which can be rapidly and easily prepared at low costs appears to be an efficient mean of screening potentially new therapeutic agents for their ability to inhibit leukocyte elastase and cathepsin G.

Antirheumatic Agents↗
PubMed1995

Influence of chloroquine and other substances on the collagenolytic activity in human osteoarthritic cartilage in vitro.

To investigate the influence of certain drugs and agents upon collagenolytic activity in human cartilage, homogenized articular cartilage from osteoarthritic human hips was incubated with dexamethasone, diclofenac, indometacin, phenazone, phenylbutazone, tiaprofenic acid, sulfasalazine, penicillamine, chloroquine, cysteine and a glycosaminoglycan-peptide complex (DAK-16). Collagenolytic activity was quantitated by the release of soluble hydroxyproline-containing peptides. The presence of collagenase in osteoarthritic cartilage was proved by the typical 75:25 cleavage products of type I collagen. Enzymatic collagen breakdown was found to be inhibited by chloroquine, cysteine, DAK-16, and sulfasalazine whereas the other tested agents had no significant effect. The inhibitory potency of chloroquine at therapeutical dose levels may be of pharmacological and therapeutic relevance.

Animals↗
PubMed1993

Immunohistochemical localization of articular cartilage proteoglycan and link protein in situ using monoclonal antibodies and lectin-binding methods.

Lectins have specificity for certain carbohydrate structures in macromolecules. Lectins are, therefore, useful histochemical tools for demonstrating the composition and localization of components of connective tissue matrices, such as articular cartilage. In order to assess the significance of observed lectin-binding patterns, experiments were performed in which monoclonal antibodies against chondroitin sulphate- and keratan sulphate-containing proteoglycans and link proteins were applied to sections of bovine articular cartilage after enzymatic digestion with chondroitinase ABC and keratanase. The following conclusions were made: (1) Binding of peanut agglutinin (PNA) in the interterritorial matrix predominantly indicates the presence of keratan sulphate, but may also detect O-linked oligosaccharides of proteoglycans. (2) In normal cartilage wheat germ agglutinin (WGA) binds nearly exclusively to keratan sulphate. In cartilage degraded with chondroitinase ABC and keratanase this lectin may also detect carbohydrates in link protein due to enhanced accessibility. Binding of WGA to O-linked oligosaccharides may eventually occur. (3) In enzymatically digested cartilage matrix, staining with soybean agglutinin (SBA) may be due to link protein, but not to chondroitin sulphate, because specific breakdown of the glycosaminoglycan chain is required for binding of SBA. (4) Ulex europaeus agglutinin I (UEA I) binding sites are only detectable in digested cartilage matrix.

Animals↗
PubMed1993

Histomorphological studies on the effect of recombinant human superoxide dismutase in biochemically induced osteoarthritis.

Enzymatic scavenging of .O-2 radicals by injections of superoxide dismutase has been described to inhibit the free radical reactions resulting in tissue damage. Using a biochemically induced model of osteoarthritis (OA) in the knee joints of hens, we investigated the histomorphological alterations under therapy with recombinant human superoxide dismutase (rH-SOD) in various doses by histological-histochemical grading. Treatment of experimental OA with rH-SOD (0.1 mg/0.1 ml intra-articularly) led to a significant reduction in the intensity of cartilage degradation. The pathomorphological alterations in the osteoarthritic cartilage of hens treated with rH-SOD were quantitatively but not qualitatively different from the placebo-treated group. Our results indicate that rH-SOD exerts an inhibitory effect on the deleterious processes on articular cartilage tissue during the course of OA and may counteract cartilage degradations induced or accelerated by oxygen radicals.

Animals↗
PubMed1993

Prolonged effect of iodoacetate on articular cartilage and its modification by an anti-rheumatic drug.

The intra-articular injection of iodoacetate into the knee joint of rats produced changes in the articular cartilage which resembled those of osteoarthritis. It caused virtually total loss of many of the oxidative enzymes, indicating inhibition of the main oxidative pathways. Treatment with an anti-rheumatic drug had little early effect but ultimately led to partial restoration of these pathways. The reduced progression of cartilage degradation induced by this drug was accompanied by some unusual histological features.

Animals↗
PubMed1992

Structural and metabolic changes in articular cartilage induced by iodoacetate.

The chemically induced injury to articular cartilage, caused by two successive intra-articular injections of sodium iodoacetate, has been used in studies on the effects of anti-inflammatory and of potentially chondroprotective agents. It has been assumed that the injurious effects are caused by inhibition of the glycolytic pathway. In the present study this inhibition has been shown to be greater than expected from in vitro studies, and to influence equally other oxidative pathways. However, the response is clearly not a simple one in that some of the surface chondrocytes, and synovial lining cells in close proximity to the cartilage, show virtually no inhibition.

Animals↗
PubMed1992

Human recombinant interleukin-1 alpha and beta and articular tissue integrity. An in vivo study on hens and rats.

Human recombinant interleukin-1 alpha or beta was injected intraarticularly several times into the knee joints of rats and hens at different dosages (50-2000 ng) and intervals. No loss of cartilage detectable by width of the radiological joint space and no degenerative changes of subchondral bone could be observed during 16 weeks using X-ray analysis. The macroscopical examination of articular cartilage of hens after this period and of rats after one year showed no morphological cartilage damages. These data suggest that human recombinant Il-1 alpha and beta alone may not be sufficient to induce a progressing osteoarthritic process in these animals.

Animals↗
PubMed1991

Influence of some natural and semisynthetic agents on elastase and cathepsin G from polymorphonuclear granulocytes.

The in vitro effect of eglin C, glycosaminoglycan-peptide complex "DAK 16", glycosaminoglycan polysulfate and sodium pentosan polysulfate on the PMN-enzymes elastase and cathepsin G was investigated. The activity of elastase and cathepsin G was measured with the highly specific chromogenic substrates methoxysuccinyl-l-ala-l-ala-l-pro-l-val-p-nitroaniline and succinyl-l-ala-l-ala-l-pro-l-phenyl-alanin-p-nitroaniline. Eglin C and DAK 16 displayed a pronounced inhibition of PMN-elastase and PMN-cathepsin G. Surprisingly a higher amount of product in the elastase containing assays were found in the presence of glycosaminoglycan polysulfate and sodium pentosan polysulfate. The higher cleavage of the elastase substrate is related back to an electrostatic interaction of the polysulfates with this substrate. Both polysulfates strongly inhibited cathepsin G. The qualitatively and quantitatively different behavior of the drugs on elastase and cathepsin G are discussed with regard to their in vivo contribution to the therapy of chronic inflammatory joint diseases.

Cathepsin G↗
PubMed1990

[Pharmacologic studies on the antidegenerative effect of ademetionine in experimental arthritis in animals].

A standardized pharmacological model of biochemically induced osteoarthritis in the knee joint of laboratory animals was used for the study of a possible antidegenerative effect of ademetionine (S-adenosyl-methionine, active substance of Gumbaral) in-vivo. Four days after the initial induction of osteoarthritis by 2 intraarticular injections of 0.6 mg sodium iodoacetate into the left knee joint of adult hens, the therapy started with once-weekly intraarticular doses of 0.5 mg, 1.0 mg and 2.0 mg ademetionine over a period of 14 weeks. Quantitative monitoring of the intensity and progression of osteoarthritis was performed every 2 weeks by joint space measurements, topographic-radiological evaluations, and by a macroscopic post-mortem assessment of the joint cartilage and bone. These objective analytical parameters clearly demonstrated that weekly intraarticular doses of 1.0 mg ademetionine significantly reduced the intensity of degenerative processes compared to the placebo (saline) treated joints. The antidegenerative effect of doses of 0.5 mg or 2.0 mg ademetionine were less pronounced and of no statistical significance. Our findings indicate an interesting therapeutic potency of ademetionine in experimental osteoarthritis and confirm the positive clinical observations as well as in-vitro results with this new drug by other researchers.

Animals↗
PubMed1990

Pharmacological influence on polymorphonuclear granulocytes elastase under various test conditions.

The effect of diclofenac-Na, glycosaminoglycanpolysulfate (GAGPS), eglin C and alpha 1-proteinase inhibitor on the activity of elastase from polymorphonuclear granulocytes (PMN-elastase) was tested under various conditions. The synthetic substrate methoxysuccinyl-1-ala-1-pro-1-val-p-nitroaniline was used to measure the activity of the enzyme. The inhibition or activation of PMN-elastase by the test substances was dependent on the type and concentration of buffer, the pH, the presence of a tenside and most notably, the presence of electrolytes. Components of the synovial fluid changed the effects of these electrolytes. Therefore, it is as yet unclear, to what degree the inhibition of PMN-elastase contributes to the therapeutical effects of non-steroidal anti-inflammatory drugs and anti-osteoarthritic drugs.

Diclofenac↗
PubMed1989

[The effect of anti-inflammatory agents on the granulocyte enzymes elastase and cathepsin G].

Effect of Nonsteroidal Anti-inflammatory Drugs on the Activity of Elastase and Cathepsin G from Human Polymorphonuclear Leukocytes. Several anti-inflammatory drugs display qualitative and quantitative different effects upon elastase and cathepsin G. Phenylbutazone, oxyphenbutazone, sulfinpyrazone and diclofenac-sodium proved to be the most efficient inhibitors of elastase and cathepsin G. A less marked inhibition of the proteinases of granulocytes was observed when indomethacin, ketoprofen, naproxen, pirprofen and tiaprofenic acid were tested. Acetylsalicylic acid, dexamethasone and oxaceprol were ineffective. Marked inhibition by these drugs was only observed at concentrations greater than those found naturally in the synovial fluid. Therefore it remains unknown, wether or to what extent an inhibition of the elastase and cathepsin G contributes to or participates in the therapeutic effects of nonsteroidal antirheumatic drugs.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Histomorphological and lectin-histochemical confirmation of the antidegenerative effect of diclofenac in experimental osteoarthrosis.

The integrity of cartilage matrix depends on the homeostasis of synthetic and degradative processes. Any disturbance of the rate of synthesis and catabolism may alter the amount of matrix components (e.g. proteoglycans). Based upon a biochemically induced osteoarthrosis (OA) in the knee joints of rats we investigated the histomorphological alterations under therapy with diclofenac sodium by histological-histochemical grading. Lectin-binding techniques using labelled wheat germ agglutinin (WGA), concanavalin A (Con A), Ulex europeus agglutinin I (UEA I), soybean agglutinin (SBA), and peanut agglutinin (PNA) were applied to analyze the cellular as well as the extracellular glycoconjugates in situ. Lectin-binding patterns quantitatively describe the topographical localization of structural components of the cartilage matrix which carry certain sugar residues. The therapy of the experimental OA with diclofenac sodium (2.0 mg/kg s.c.) led to a marked reduction of cartilage degenerations. Our results indicate antidegenerative properties of this compound. These findings are consistent with the fluorescent analytical data which show a stimulating effect on the anabolic activity of chondrocytes in the osteoarthritic joints under the treatment with diclofenac sodium. Fluorescein isothiocyanate labelled lectins are useful histochemical tools to determine alterations in the integrity of cartilage by their specific binding patterns, because zonal differentiation in physiological function and morphological structure of cartilage tissue as well as cellular, pericellular, and interterritorial local events are characterized.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

The influence of NSAIDs on morphology of articular cartilage.

A large number of experimental data have given evidence that many NSAIDs can inhibit the synthetic processes of connective tissue in-vitro and ex-vivo. During the past 18 years we have investigated the in-vivo effect of antirheumatic drugs on knee joint cartilage using rats and hens. Single or once-weekly intraarticular injections of salicylates, indomethacin, phenylbutazone, naproxen, ibuprofen, clofezone, fufenamic acid, niflumic acid, or dexamethasone induced morphological alterations in the joint cartilage and subchondral bone, which were demonstrable by means of histology, stereoelectron-microscopy, biochemistry and X-ray. The cartilage of these laboratory animals had a faster turnover compared to man, and the degenerative and destructive processes occurred within 8-12 weeks and were identical or very similar to osteoarthritis in man. In contrast to the general opinion that all NSAIDs possess more or less the same pharmacological properties, the influence of these drugs on articular cartilage was, surprisingly, quite different. In our animal experiments we found that comparable doses between NSAIDs, such as fenbufen, ketoprofen, diclofenac, and tiaprofenic acid, did not induce any degenerative processes in cartilage and subchondral bone in-vivo. A documentation of our radiographical, macroscopical and histomorphological results demonstrated the pronounced differences between NSAIDs on joint tissue. Our experimental data suggested that in the pharmacotherapy of osteoarthritis a specific selection of NSAIDs between those with catabolic and those with non-catabolic characteristics in regard to connective tissue metabolism was important and beneficial.

Animals↗
PubMed1987

Chemical model of osteoarthritis--a pharmacological evaluation.

For pharmacological testing of drugs with antidegenerative potency we developed an animal model of biochemically induced osteoarthritis (OA) by blocking the glycolytic energy metabolism and synthetic processes in articular chondrocytes. After local injection of sodium iodoacetate osteoarthritic reactions will progress within 2-4 months. Using a standardized radiological, histological, and macroscopical grading we could demonstrate that corticosteroids and some NSAID exert negative effects on articular cartilage, while a few other NSAID showed no influence. Diclofenac had even a pronounced antidegenerative potency which was comparable to the antiosteoarthritic properties of two glycosaminoglycan derivatives investigated in the model of biochemically induced OA in the knee joint of hens and rats.

Adrenal Cortex Hormones↗
PubMed1983

Histological investigations of the antiarthrotic effect of tribenoside (Glyvenol) in experimental osteoarthrosis.

Experiments in adult hens with chemically induced osteoarthrosis or osteoarthritis (OA) of the knee joint have shown that daily treatment with tribenoside (Glyvenol) in single oral doses of 50 mg/kg or 150 mg/kg markedly reduced the intensity and frequency of joint degeneration. We investigated the inhibitory effect of tribenoside on OA by histological techniques. Comparisons of articular cartilage from untreated and treated animals showed no qualitative differences in the alterations of the morphology and histopathology of the tribenoside treated specimens. Only the frequency and intensity of degenerative alterations were markedly reduced in the drug treated animals.

Animals↗