The articular cartilage consists of resident chondrocytes embedded within the extracellular matrix which contains several components such as collagen and hyaluronic acids (HA). CD44 is a major cell surface receptor for HA and is homologous to cartilage-link proteins. Although CD44 is present in cartilage, it is not clear if chondrocytes adhere to HA through CD44 or whether such adhesion changes the function of chondrocytes. We studied the molecular mechanisms of CD44-related chondrocyte adhesion to HA and the effects of such adhesion on chondrocyte function. Experiments were performed using the human chondrosarcoma-

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The two major processes of bone metabolism--bone formation and resorption--are regulated by cellular interactions. Osteoblasts and osteoclasts play a significant role in bone metabolism, which is known to be regulated by local soluble factors and systemic hormones. Although bone is a heterogeneous tissue comprised of osteogenic and hematopoietic cells, cellular adhesion of osteoblasts and its regulation remains to be understood. We first demonstrate that cellular adhesion by which osteoblasts communicate with opposing cells in bone milieu is involved in the osteoblast activation: (a) purified human osteoblasts obtained from osteoarthritis patients expressed particular adhesion molecules, ICAM-1, VCAM-1, and LFA-3; (b) toe osteoblasts adhered to T cells which were used as representative adhesive partners, since T cells possess all the receptors to these adhesion molecules; (c) mRNA transcription and secretion of IL-1beta and IL-6 were induced in the osteoblasts by the cellular adhesion to T cells and they were reduced by interrupting the adhesion; (d) cross-linking of ICAM-1 and VCAM-1 on the osteoblasts induced IL-6 secretion from the osteoblasts. These results indicate that osteoblasts adhere to opposing cells through particular adhesion molecules on their surface and that the adhesion molecules on the osteoblasts not only function as glue with opposing partners but transduce activation signals that facilitate the production of bone-resorbing cytokines. We propose that cellular adhesion of osteoblasts as well as soluble factors is significant for the regulation of bone metabolism.

Wedescribe a familial occurrence of primary hyperparathyroidism. The proband is a 60-yearold womanwho had a parathyroid adenoma. Her older sister had a parathyroid adenoma with cementifying jaw fibroma and her younger sister died of parathyroid adenocarcinoma with pulmonarymetastasis at the age of 38.Wehave not yet obtained evidence for other endocrine disorders suggesting multiple endocrine neoplasia (MEN)in this pedigree. The proband is complicated with Wilms' tumor. It is now widely accepted that respective predisposed genes of MENtype 1 and Wilms' tumor, and PTHgene are located on chromosome ll. The manifestation observed in this case maybe related to mutational abnormalities on chromosomell. (Internal Medicine 33: 123-126, 1994)