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J Belke

Publications and source records attributed to J Belke.

6 recordsLinked to original sources
PubMed1998

Epithelial-mesenchymal transdifferentiation and extracellular matrix gene expression in pleomorphic adenomas of the parotid salivary gland.

Mesenchymal and epithelial cell differentiation are assumed to be dichotomic primary events in embryonic development. In this study, pleomorphic adenomas of the parotid gland were analysed as a model which shows morphological features of both epithelial and mesenchymal tissue types. Using matrix gene expression profiles as a supplementary criterion for the identification of cellular phenotypes, areas with unequivocal epithelial and mesenchymal differentiation could be demonstrated. Many areas displayed a transitional phenotype with cells showing both epithelial and mesenchymal features. The data provide evidence that epithelial-mesenchymal transitions represent the basic principle of the tisuse heterogeneity in pleomorphic adenomas. Thus, pleomorphic adenomas demonstrate the potential of adult (neoplastic) epithelial cells to transdifferentiate into mesenchymal cells in vivo.

Adenoma, Pleomorphic↗
PubMed1997

Extracellular matrix composition and gene expression in collagenous colitis.

BACKGROUND & AIMS: Collagenous colitis is a rare diarrheal disease of unknown pathophysiology that is histologically defined by subepithelial bandlike structures. The objective of this study was to elucidate the biochemical composition and the origin of the bandlike structures in collagenous colitis. METHODS: Immunohistochemical and in situ hybridization analyses were performed on endoscopic specimens using specific antibodies and riboprobes for collagen types I, III, IV, and VI and for the glycoprotein tenascin. RESULTS: In collagenous colitis, the mucosal matrix with the exception of the bands retained a normal architecture and extracellular matrix composition. The bands stained most prominently for type VI collagen and tenascin. Less abundant staining for both proteins was also found in the subepithelial matrix of the normal mucosa. In situ hybridization showed no significant increase in collagen type VI messenger RNA expression in cells around and entrapped in the bands in collagenous colitis compared with normal specimens. CONCLUSIONS: The results support the suggestion that collagenous colitis is a localized alteration of the extracellular matrix, which involves the pericryptal-subepithelial myofibroblast sheath. The data suggest that reduced matrix degradation and not overactivation of matrix synthesis may be the reason for the subepithelial accumulation of matrix proteins.

Adult↗
PubMed1996

Chondrocytic cell differentiation in clear cell chondrosarcoma.

Clear cell chondrosarcoma is a rare mesenchymal neoplasm of unclear differentiation. Besides having a chondrogenic nature, an osteogenic differentiation was also proposed. In this study, expression analysis of extracellular matrix genes, which are specific for different mesenchymal cell differentiation pathways, were used to get a better understanding of origin and differentiation pattern of the clear cell chondrosarcoma tumor cells. Our in situ analysis of two cases shows that (1) chondrocytic cell differentiation as marked by the expression of cartilage collagen type II and proteoglycans is a characteristic feature within the development of the neoplasm, (2) multifocal chondrocyte hypertrophy as shown by the expression of type X collagen does occur, and (3) no significant expression of collagen type I, the main gene product of osteoblastic cells, is found by the neoplastic cells. Thus, our study indicates that clear cell chondrosarcoma shows a chondrogenic, but not osteogenic, differentiation and represents a true chondrosarcoma. The unusual scarcity of its extracellular and the multifocal expression of type X collagen marks clear cell chondrosarcoma as a chondrosarcoma tumor entity of a particular cell differentiation pattern. The expression of cartilage type collagens represents a distinct marker from bone metastases of clear cell neoplasms of other origins.

Adult↗
PubMed1996

[Inflammatory cytokine mediated anti-anabolic effects: a potential mechanism in rheumatoid cartilage degeneration].

Increased levels of inflammatory cytokines such as II-1 and TNF-alpha are described in rheumatoid and osteoarthritic synovial fluid. These mediators are also very well established anti-anabolic modulators of chondrocyte synthetic activity in vitro. Our study aimed to investigate, whether chondrocytes in rheumatoid and osteoarthritic cartilage in situ show reaction pattern compatible with the putative effects of these modulatory agents. Immunohistochemical analysis using type II collagen specific antibodies showed considerable loss of staining in many sites of osteoarthritic and rheumatoid articular cartilage. mRNA analysis showed besides an overall activation of synthetic activity in rheumatoid and osteoarthritic cartilage, a decreased expression of cartilage matrix proteins in the upper zone. The cease of the anabolic activity of rheumatoid and osteoarthritic chondrocytes and the increased catabolism of matrix components contributes to the anabolic-catabolic imbalance in rheumatoid and osteoarthritic cartilage and is suggestive to be a crucial event in the progress of the disease. It correlates well to the putative anti-anabolic effect of inflammatory cytokines such as II-1 and TNF-alpha and could indicate a potential role of these mediators in rheumatoid and osteoarthritic cartilage destruction.

Arthritis, Rheumatoid↗