Osteoarthritic synovial fibroblasts possess an increased level of tumor necrosis factor-receptor 55 (TNF-R55) that mediates biological activation by TNF-alpha.

Objective: To investigate the presence, number, and level of expression of tumor necrosis factor receptors (TNF-R) in normal and osteoarthritic (OA) human synovial fibroblasts; to examine which receptor isotype mediates the biological response of these cells to TNF-alpha; and to study homologous regulatory mechanisms of TNF-R by TNF-alpha.

Methods: We used radioligand binding assay with [125I]TNF-alpha and flow cytometric analysis with specific antireceptor antibodies to characterize receptor populations, densities, and ligand induced internalization of TNF-R. Inducible cyclooxygenase (COX-2) synthesis, prostaglandin E2 (PGE2) release, and TNF-R shedding (soluble receptors, TNF-sR) were measured after incubation with TNF-alpha the presence or absence of receptor specific blocking antibodies.

Inhibitory tyrosine protein kinase p50csk is associated with protein-tyrosine phosphatase PTP-PEST in hemopoietic and non-hemopoietic cells.

p50(csk) is a cytosolic tyrosine protein kinase expressed in all cell types. Accumulating data show that it inhibits multiple cellular processes, as a consequence of its ability to repress the enzymatic activity of Src family tyrosine protein kinases. We previously demonstrated that, via its Src homology 3 (SH3) domain, Csk is tightly bound to PEP, a protein-tyrosine phosphatase (PTP) exclusively expressed in hemopoietic cells.

Sequence and mutational analysis of the 6.7-kb region containing nodAFEG genes of Rhizobium sp. strain N33: evidence of DNA rearrangements.

A 6.7-kb region upstream of nodBC genes in Rhizobium sp. strain N33 was shown to contain the nodAFEG genes and an open reading frame designated orfZ.

Association of inhibitory tyrosine protein kinase p50csk with protein tyrosine phosphatase PEP in T cells and other hemopoietic cells.

p50csk is a tyrosine protein kinase (TPK) that represses the activity of Src family TPKs. We previously showed that Csk is a potent negative regulator of antigen receptor signaling in T lymphocytes and that its Src homology (SH) 3 and SH2 domains are required to inhibit these signals. To test the idea that the Csk SH3 and SH2 domains mediate interactions with other cellular proteins, we attempted to identify Csk-associated polypeptides using the yeast two-hybrid system.

Sequence and mutational analysis of the common nodBCIJ region of Rhizobium sp. (Oxytropis arctobia) strain N33, a nitrogen-fixing microsymbiont of both arctic and temperate legumes.

By heterologous hybridization, we have identified the common nodulation genes nodBCIJ of Rhizobium sp. strain N33 within a 8.2-kb PstI fragment.

Normal expression of type 1 insulin-like growth factor receptor by human osteoarthritic chondrocytes with increased expression and synthesis of insulin-like growth factor binding proteins.

Objective: Our previous research demonstrated that, in contrast to normal chondrocytes, human osteoarthritic (OA) chondrocytes were hyporesponsive to stimulation by insulin-like growth factor 1 (IGF-1). The aim of the present investigation was to examine whether this finding was due to an alteration in the level of IGF receptors (IGFRs) and/or IGF binding proteins (IGFBP).

Methods: A quantitative reverse transcriptase polymerase chain reaction technique (RT-PCR) was used to measure the type 1 IGFR messenger RNA (mRNA) level, and Northern blotting was used to measure type 2 IGFR and IGFBP mRNA levels.

The new collagenase, collagenase-3, is expressed and synthesized by human chondrocytes but not by synoviocytes. A role in osteoarthritis.

Recently, a new human collagenase, collagenase-3 has been identified. Since collagen changes are of particular importance in cartilage degeneration, we investigated if collagenase-3 plays a role in osteoarthritis (OA). Reverse transcriptase-PCR analysis revealed that in articular tissues collagenase-3 was expressed by the chondrocytes but not by the synoviocytes.

[Influence of the tibial slope on tibial translation and mobility of non-constrained total knee prosthesis].

Purpose Of The Study: We determined retrospectively the influence of posterior tibial slope and anterior cruciate ligament (ACL) sparing on anterior tibial translation in 68 Cloutier total knee prosthesis. We also precised the influence of posterior tibial slope on knee functional score and appearance of tibial prosthetic interfaces.

Material: 38 Cloutier total knee prosthesis (62 patients mean aged 62 +/- 10 years (36-76) at surgery) reviewed at systematic follow-up control, after a mean period of 5.

Requirement of the SH3 and SH2 domains for the inhibitory function of tyrosine protein kinase p50csk in T lymphocytes.

Previous studies from our laboratory have shown that the cytosolic tyrosine protein kinase p50csk is involved in the negative regulation of T-cell activation (L.M. L.

Human synovial fibroblasts coexpress IL-1 receptor type I and type II mRNA. The increased level of the IL-1 receptor in osteoarthritic cells is related to an increased level of the type I receptor.

Background: Cytokines, in particular IL-1, are believed to be responsible for mediating cartilage degradation in osteoarthritis (OA). To investigate the role of the IL-1 system in this disease, we studied in normal and OA human synovial fibroblasts the nature, the number, and the level of expression of the IL-1 receptor (IL-1R) and through which receptor the biologic stimulation of these cells by IL-1 is mediated.

Experimental Design: We determined the IL-1R level by radioligand assay, the type of IL-1R with the use of specific antibodies and by the reverse transcriptase-PCR (RT-PCR), and the mRNA level of the type I IL-1R by slot blot analysis.

Increased insulin-like growth factor 1 production by human osteoarthritic chondrocytes is not dependent on growth hormone action.

Objective: To investigate insulin-like growth factor 1 (IGF-1) production in normal and osteoarthritis (OA) chondrocytes and to further examine the role of growth hormone (GH) in adult human cartilage and, in particular, in diseased tissue.

Methods: IGF-1 production was measured with a radioimmunoassay. Binding assay, Northern blot, and reverse transcriptase polymerase chain reaction (RT-PCR) techniques were used for GH receptor (GHR) detection.

Regulation of Zap-70 by Src family tyrosine protein kinases in an antigen-specific T-cell line.

To further understand the interactions between Zap-70, Src family kinases, and other T-cell proteins, we have examined the regulation of Zap-70 in the antigen-specific T-cell line BI-141. By analyzing derivatives containing an activated version of either p56lck or p59fynT, it was observed that the two Src-related enzymes augmented T-cell receptor (TCR)-mediated tyrosine phosphorylation of Zap-70, as well as its association with components of the antigen receptor complex. Importantly, the accumulation of TCR.

Synthesis of metalloproteases and interleukin 6 (IL-6) in human osteoarthritic synovial membrane is an IL-1 mediated process.

We investigated the nature of cytokines synthesized by human osteoarthritic (OA) synovium, particularly interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), and tumor necrosis factor alpha (TNF alpha). We examined the capacity of recombinant human interleukin 1 receptor antagonist (rhIL-1ra) to block the synthesis of metalloproteases (collagenase and stromelysin), IL-1 beta, and IL-6 in osteoarthritis (OA) synovium. Human OA synovium were incubated in the presence or absence of lipopolysaccharide (LPS) or increasing concentrations of rhIL-1ra.

Cost-effectiveness in ambulatory care: alternative approaches.

By relating health care resources and their use to health outcomes, through a coherent macro resource allocation framework, one can examine the health care system for allocative efficiencies. In this article, costs and outcomes are analyzed in such a framework, scenarios for optimizing the use of health care resources--while still maintaining existing health outcomes--are explored, and the implications for ambulatory care are discussed. The research clearly shows that much can be done to make health care systems more efficient without jeopardizing health outcomes.

Excess of metalloproteases over tissue inhibitor of metalloprotease may contribute to cartilage degradation in osteoarthritis and rheumatoid arthritis.

Background: In an attempt to identify the factor(s) involved in the modulation of the degradative pathway of articular cartilage, we previously reported a possible imbalance between the levels of biologically active forms of metalloproteases and tissue inhibitor of metalloprotease (TIMP) in osteoarthritis (OA) cartilage.

Experimental Design: We extended our analysis on the protein level and the synthesis of stromelysin-1, collagenase, TIMP-1, and TIMP-2 in normal, OA, and RA cartilages, and provided information on the synthesis pattern of these proteins in respect to the action of interleukin-1 (IL-1). These protein concentrations were determined by specific sandwich EIA assays.

Regulation of human normal and osteoarthritic chondrocyte interleukin-1 receptor by antirheumatic drugs.

Objective: To determine the effect of antirheumatic drugs and corticosteroids on interleukin-1 receptor (IL-1R) levels in, and IL-1-stimulated metalloprotease synthesis and expression by, normal and osteoarthritic (OA) human articular chondrocytes.

Methods: IL-1R affinity and density of human chondrocytes were determined using radioligand binding experiments. Collagenase and stromelysin synthesis activities were analyzed by 14C-labeled type I collagen and Azocoll assays, respectively.

Distinct expression pattern of early- and late-response genes in normal and osteoarthritic human synovial membranes.

The significance of activating proteins (AP-1), c-fos, c-jun and jun B relative to the AP-1 responsive metallothionein, collagenase and stromelysin gene expression in the pathophysiology of osteoarthritis (OA) was investigated. The 'early' c-fos, c-jun and jun-B mRNAs were ubiquitously expressed in normal and OA human knee synovial membranes. There was no strict correlation between expression of these and the AP-1 responsive, collagenase and stromelysin gene expression.

Reduced expression of glucocorticoid receptor levels in human osteoarthritic chondrocytes. Role in the suppression of metalloprotease synthesis.

Glucocorticoid occupancy of a large percentage of glucocorticoid receptor (GR) is necessary for the suppression of matrix metalloprotease synthesis by human articular chondrocytes. In this study, we evaluated the levels of GR binding, cellular GR protein, and messenger RNA expression in both normal and osteoarthritic (OA) human articular chondrocytes and compared the degree of suppression of collagenase synthesis by glucocorticoids in cultures of the two cell types in order to investigate whether or not the GR system played an important role in the pathophysiology of OA. By radioreceptor binding assay, we recorded 56,320 +/- 8,230 sites per cell (mean +/- SE, n = 9) in primary cultures of normal chondrocytes and 27,480 +/- 14,240 sites in OA cells (n = 10, P < 0.

Elevated metalloproteinase and tissue inhibitor of metalloproteinase mRNA in human osteoarthritic synovia.

The levels of metalloproteases and inhibitor expression in synovial membranes were measured by analyzing mRNA of collagenase, stromelysin, and tissue inhibitor of metalloproteinase (TIMP-1) in this tissue from 20 healthy persons and 20 patients with osteoarthritis (OA). Our results indicated that while most of the normal synovia expressed TIMP-1 mRNA at low levels, very few expressed metalloproteinase mRNA. In contrast 40% of patients with OA expressed a moderate level of collagenase compared to 55 and 80% cases with considerably elevated stromelysin and TIMP-1 mRNA, respectively.

In vitro effects of NSAIDs and corticosteroids on the synthesis and secretion of interleukin 1 by human osteoarthritic synovial membranes.

The mechanism(s) of action of NSAIDs and corticosteroids in arthritic diseases has been the subject of intensive investigation in recent years. Although NSAIDs and corticosteroids have many effects, their possible ability to modify the disease course in patients has not been fully documented. In an attempt to characterize the mechanism(s) involved in the effect of some NSAIDs in joint diseases, we investigated the effect of three concentrations within the pharmacological (260 micrograms/ml) and therapeutic (26 and 2.

Heat and cold shock protein synthesis in arctic and temperate strains of rhizobia.

We compared heat shock proteins (HSPs) and cold shock proteins (CSPs) produced by different species of Rhizobium having different growth temperature ranges. Several HSPs and CSPs were induced when cells of three arctic (psychrotrophic) and three temperate (mesophilic) strains of rhizobia were shifted from their optimal growth temperatures (arctic, 25 degrees C; temperate, 30 degrees C) to shock temperatures outside their growth temperature ranges. At heat shock temperatures, three major HSPs of high molecular weight (106,900, 83,100, and 59,500) were present in all strains for all shock treatments (29, 32, 36.

Expression of c-fos, c-jun, jun-B, metallothionein and metalloproteinase genes in human chondrocyte.

Normal and osteoarthritic (OA) human articular cartilage chondrocytes, released enzymatically in the presence of 0.5% fetal calf serum, display constitutive expression of early response activating protein (AP-1) genes; c-fos, c-jun and jun-B. Among the late AP-1 responsive genes, total metallothionein (MT) and stromelysin mRNAs were expressed at high levels in both normal and OA chondrocytes, while collagenase and hMT-IIA mRNA levels were elevated only in OA individuals.

Proteoglycan structural changes in human rheumatoid articular cartilage.

Human rheumatoid arthritic (RA) cartilage contains elevated levels of proteolytic enzymes in which the metalloproteases are believed to be the prime enzyme system involved in cartilage metabolism. We examined the effects of these enzymes and the serine proteases on endogenous proteoglycans (PGs) and newly synthesized PGs of seven RA cartilages. The data was further analyzed with regard to the therapy received by the patients prior to surgery.