Objective To examine by immunohistochemistry the relative distributions of 6 matrix metalloproteinases (MMPs 1, 2, 3, 8, 9, and 13) and the 2 proinflammatory cytokines interleukin‐1β (IL‐1β) and tumor necrosis factor α (TNFα) in osteoarthritic (OA) cartilage compared with normal, age‐matched articular cartilage. Methods Articular cartilage samples were obtained from the tibial plateau of OA knees removed at arthroplasty and from normal, nonarthritic, knees obtained at autopsy. Specimens were promptly fixed in Carnoy's fixative, processed, embedded in paraffin, sectioned, and examined by immunohistochemistry for MMP and cytokine production. In addition, human articular chondrocytes (HAC) were treated in vitro with either IL‐1β, TNFα, or phorbol myristate acetate (PMA) to assess their potential to produce each of the MMPs, as determined by Western blotting and gelatin zymography. Results Immunodetection of the collagenases (MMPs 1, 8, and 13) and stromelysin 1 (MMP‐3) was demonstrated in a proportion of chondrocytes in the superficial zone of almost all of the OA specimens that had degenerative matrix changes. The gelatinases (MMPs 2 and 9) were also demonstrated by immunohistochemistry but were not so prominent. IL‐1β– and TNFα‐positive chondrocytes were also observed in a proportion of cells in the superficial zones of OA specimens. Much less immunostaining for MMPs and cytokines was observed in the deep zone of all OA specimens, where the cartilage matrix and chondrocyte morphology appeared normal. In contrast, full‐thickness normal cartilage specimens showed virtually no immunostaining for these MMPs or cytokines. Confirmation that chondrocytes can produce these 6 MMPs was obtained from HAC cultures treated with either IL‐1β, TNFα, or PMA; conditioned medium from activated HAC contained all the MMPs demonstrated by immunohistochemistry. Dual immunolocalization studies of OA cartilage specimens demonstrated the coexpression of IL‐1 with MMP‐8 by individual chondrocytes in situ. Conclusion These results indicate that the superficial zone of OA cartilage specimens, which is characterized by fibrillations, chondrocyte clusters, and degenerative matrix changes, contains a variable proportion of cells that immunostain for IL‐1β, TNFα, and 6 different MMPs. These observations support the concept that cytokine–MMP associations reflect a modified chondrocyte phenotype and an intrinsic process of cartilage degradation in OA.

Objective.To examine by immunohistochemistry the relative distributions of 6 matrix metalloproteinases (MMPs 1, 2, 3, 8, 9, and 13) and the 2 proinflammatory cytokines interleukin-1␤ (IL-1␤) and tumor necrosis factor ␣ (TNF␣) in osteoarthritic (OA) cartilage compared with normal, age-matched articular cartilage.Methods. Articular cartilage samples were obtained from the tibial plateau of OA knees removed at arthroplasty and from normal, nonarthritic, knees obtained at autopsy. Specimens were promptly fixed in Carnoy's fixative, processed, embedded in paraffin, sectioned, and examined by immunohistochemistry for MMP and cytokine production. In addition, human articular chondrocytes (HAC) were treated in vitro with either IL-1␤, TNF␣, or phorbol myristate acetate (PMA) to assess their potential to produce each of the MMPs, as determined by Western blotting and gelatin zymography.Results. Immunodetection of the collagenases (MMPs 1, 8, and 13) and stromelysin 1 (MMP-3) was demonstrated in a proportion of chondrocytes in the superficial zone of almost all of the OA specimens that had degenerative matrix changes. The gelatinases (MMPs 2 and 9) were also demonstrated by immunohistochemistry but were not so prominent. IL-1␤-and TNF␣-positive chondrocytes were also observed in a proportion of cells in the superficial zones of OA specimens. Much less immunostaining for MMPs and cytokines was observed in the deep zone of all OA specimens, where the cartilage matrix and chondrocyte morphology appeared normal. In contrast, fullthickness normal cartilage specimens showed virtually no immunostaining for these MMPs or cytokines. Confirmation that chondrocytes can produce these 6 MMPs was obtained from HAC cultures treated with either IL-1␤, TNF␣, or PMA; conditioned medium from activated HAC contained all the MMPs demonstrated by immunohistochemistry. Dual immunolocalization studies of OA cartilage specimens demonstrated the coexpression of IL-1 with MMP-8 by individual chondrocytes in situ.Conclusion. These results indicate that the superficial zone of OA cartilage specimens, which is characterized by fibrillations, chondrocyte clusters, and degenerative matrix changes, contains a variable proportion of cells that immunostain for IL-1␤, TNF␣, and 6 different MMPs. These observations support the concept that cytokine-MMP associations reflect a modified chondrocyte phenotype and an intrinsic process of cartilage degradation in OA.Osteoarthritis (OA) is the most prevalent disease of articular joints and is the major cause of disability in the elderly (1). Degeneration and loss of articular cartilage are characteristic features of OA. The appearance of fibrillations, matrix depletion, cell clusters, and changes in matrix composition reflect the aberrant behavior of resident chondrocytes (2). Although biomechanical factors are strongly implicated, at present it is unclear which stimuli regulate the hyperactive pheno-

Objectives-To examine the distribution and activation of mast cells (MCs)

Metformin therapy has a beneficial treatment effect over placebo for BMI-SDS, fasting glucose, ALT, and ALR ratio at 3 months, with changes in BMI-SDS sustained at 6 months.

In comparison with other series, the cure rate in this study is significantly lower. The success in reducing GH levels below 30 mU/l post-operatively is difficult to compare with previously published studies, as few groups have analysed their data in this manner. Nonetheless, of our acromegalic patients with a pretreatment GH level in excess of 30 mU/l, nearly 50% have similar GH status postoperatively, thereby rendering them less amenable to cure by alternative therapeutic modalities. This highlights the importance of a specialist pituitary surgeon, not only for GH secreting microadenomas but also for GH secreting macroadenomas. If these patients are not 'cured', the cost of continuing therapy becomes a significant burden on health-care costs. In addition, if the postoperative GH levels remain above 30 mU/l the chances of achieving adequate control of GH levels are greatly reduced, thereby increasing mortality rates as well as morbidity in these patients.