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Biomedical subjects

J Steinmeyer

Publications and source records attributed to J Steinmeyer.

28 records · Page 2Linked to original sources
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↗
PubMed1993

A new pressure chamber to study the biosynthetic response of articular cartilage to mechanical loading.

A prototype chamber was used to apply a precise cyclic or static load on articular cartilage explants under sterile conditions. A variable pressure, pneumatic controller was constructed to power the chamber's air cylinder, capable of applying, with a porous load platen, loads of up to 10 MPa at cycles ranging from 0 to 10 Hz. Pig articular cartilage explants were maintained successfully in this chamber for 2 days under cyclic mechanical loading of 0.5 Hz, 0.5 MPa. Explants remained sterile, viable and metabolically active. Cartilage responded to this load with a decreased synthesis of fibronectin and a small but statistically significant elevation in proteoglycan content. Similar but less extensive effects on fibronectin synthesis were observed with the small static load (0.016 MPa) inherent in the design of the chamber.

Animals↗
PubMed1992

Fibronectin and keratan sulfate synthesis by canine articular chondrocytes in culture is modulated by dibutyryl cyclic adenosine monophosphate.

The ability of cyclic adenosine monophosphate (cAMP) to maintain differentiated properties of canine articular chondrocytes in culture is reported. Treatment with 0.5 mM dibutyryl cAMP (DBcAMP) caused the cells to adopt a more rounded morphology. This change in morphology seems to have no effect on the overall biosynthetic rates of the cells. After a pulse with 35S-methionine, there was no difference in the concentration of labeled proteins between cultures treated with DBcAMP and control cultures. After 6 days, the amount of fibronectin (FN) in the media of DBcAMP-treated cultures detected by an enzyme-linked immunosorbent assay was specifically reduced by 30%. The amount of 35S-FN purified by gelatin-affinity chromatography decreased 33%. Moreover, the percentage of FN containing the extra domain A sequence was reduced from 19.4 +/- 8.7% in control cultures to 9.6 +/- 4.2%. Concomitant with the decrease in FN, there was an increase in the concentration of keratan sulfate in the media of DBcAMP-treated cultures. After 6 days, treated cultures had 47% more keratan sulfate than controls did. These changes appear not to be the result of a change in the deposition of FN or keratan sulfate, because the amount of these molecules that could be extracted from the cell layer was typically below the limit of detection of the assays. Instead, it seems there is a phenotypic change in the chondrocytes pertaining to the production of FN and keratan sulfate.

Animals↗
PubMed1992

Effects of three antiarthritic drugs on fibronectin and keratan sulfate synthesis by cultured canine articular cartilage chondrocytes.

Because articular chondrocytes are a target for drugs that can influence the integrity of cartilage, we investigated the effects of 3 antiarthritic drugs, glycosaminoglycan polysulfate, diclofenac-Na, and S-adenosylmethionine sulfate p-toluenesulfonate on total protein, fibronectin, and DNA synthesis, as well as on extradomain-A fibronectin and keratan sulfate content. Glycosaminoglycan polysulfate stimulated dose-dependent incorporation of [35S]methionine into protein and fibronectin, whereas incorporation of [3H]thymidine into DNA was unaffected. Total fibronectin, extradomain-A fibronectin, and keratan sulfate content were high in chondrocyte cultures treated with glycosaminoglycan polysulfate. In contrast, fibronectin and DNA synthesis, as well as extradomain-A fibronectin and keratan sulfate content were unaffected by diclofenac-Na. S-Adenosyl-methionine decreased dose-dependently the synthesis of fibronectin, as well as the content of fibronectin and keratan sulfate. At the highest concentration of S-adenosyl-methionine tested, findings suggest that cell viability was impaired as assessed by the release of lactate dehydrogenase into the media.

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↗
PubMed1991

Modulation of fibronectin and proteoglycan synthesis by chondrocytes.

Synthesis of fibronectin and proteoglycan by chondrocytes in both cell and organ culture was affected by the culture conditions. Less than 2% of the fibronectin extracted from cartilage contained the ED-III-A sequence, however, chondrocytes placed in primary culture began to synthesize increased amounts of ED-III-A fibronectin (up to 36% of the total fibronectin). Expression of ED-III-A fibronectin was selectively reduced when the chondrocytes were cultured in the presence of 0.5 mM dibutyryl cyclic AMP. The amount of fibronectin in the media of DBcAMP treated cultures was reduced by 30% but there was no effect on the overall protein biosynthetic rates of the cells. Concomitant with the decrease in fibronectin was an increase in the concentration of keratan sulfate in the media of treated cultures. Treatment with 0.5 mM dibutyryl cAMP caused the cells to adopt a more rounded morphology. Proteoglycan synthesis in cartilage explants was maintained at levels comparable to those at Day 0 for up to twelve days in a medium supplemented with insulin. Fibronectin and collagen synthesis, however, declined relative to Day 0 levels in this medium. The addition of TGF-beta at 2 and 10 ng/ml to the medium not only prevented the decline in fibronectin synthesis but progressively increased its rate of synthesis until the Day 0 levels were exceeded 4-fold. Experiments were initiated to study also the effects of mechanical factors on cartilage explant metabolism.

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↗