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J Mollenhauer

Publications and source records attributed to J Mollenhauer.

78 records · Page 5Linked to original sources
PubMed1986

Donor-age-related changes in the morphology, growth potential, and collagen biosynthesis in rat fibroblast subpopulations in vitro.

Primary explant, mass and clonal fibroblast cultures established from BN rat skin and lungs were used to examine changes in cell behaviour associated with aging. Three distinct fibroblast cell types, i.e. FI, FII and FIII, could be identified on the basis of their morphological and proliferative properties. They could also be distinguished from each other by the amount and type of collagen they synthesized in clonal cultures. FI cells are diploid, spindle shaped and highly proliferative, and they synthesize low levels of type-I and -III collagen. Epithelioid FII cells are also diploid, proliferate slowly, and exhibited elevated collagen synthesis as compared to FI cells. FIII fibroblasts are large, stellate, tetraploid cells that proliferate more slowly than the other types but synthesize large amounts of collagen. In comparison to FI cells, the level of type-III-collagen synthesis is slightly elevated in FIII fibroblasts. In primary explant, mass and clonal cultures, the relative proportions of FI, FII and FIII cells were found to change as a function of the age of the donor animal. The increasing predominance of FIII cells in mass cultures of fibroblasts obtained from donors of increasing ages was consistent with the increased level of collagen synthesis in these cultures. Our observations indicate that the differentiation of normal BN rat fibroblasts occurs via a three-phase process. We discuss the age-related changes in the relative abundance of FI, FII and FIII cells in vivo in the context of alterations in fibroblast replacement and changes in connective tissue that occur during aging.

Aging↗
PubMed1984

Role of anchorin CII, a 31,000-mol-wt membrane protein, in the interaction of chondrocytes with type II collagen.

We have previously reported the isolation of a hydrophobic, type-II collagen-binding glycoprotein of molecular weight 31,000 (31,000-mol-wt protein) from chick chondrocyte membranes (Mollenhauer, J., and K. von der Mark, EMBO Eur. Mol. Biol. Organ. J., 2:45-50). The function of this protein in anchoring pericellular type II collagen to the chondrocyte surface was inferred from its ability to bind native type-II collagen either when detergent solubilized or when inserted into liposomes. In the present study we have used specific antibodies to localize this protein, which we now call anchorin CII, to the surface of chondrocytes in both cartilage sections, and in cell culture. In immunofluorescence studies of isolated chondrocytes we observed a dense, punctate distribution of anchorin CII on the cell surface when chondrocytes were enclosed by a pericellular type II collagen matrix. Removal of the pericellular matrix with trypsin also removed anchorin CII. The membrane protein character of anchorin CII was indicated by the demonstration of antibody-induced patching and capping on the chondrocyte surface at 22 degrees C and 37 degrees C, respectively. In monolayer culture, the amount of anchorin CII appeared reduced on flattened chondrocytes lacking a pericellular type II collagen matrix but was prominent upon intercellular cell processes. Fab' fragments prepared from either anchorin CII antiserum or an antiserum directed against the entire chondrocyte membrane inhibited the attachment of chondrocytes to a type II collagen substrate. In each case, the inhibition of attachment was neutralized by preincubation of Fab' fragments with purified anchorin CII.

Animals↗
PubMed1983

Isolation and characterization of a collagen-binding glycoprotein from chondrocyte membranes.

A collagen-binding glycoprotein was isolated from purified chick chondrocyte surface membranes by affinity chromatography on type II collagen-Sepharose. The purified glycoprotein has an apparent mol. wt. of 31,000 and binds to native chick collagen types I, II, III, V and M. Although it contains 30% carbohydrates, the majority of which is fucose, it is hydrophobic and soluble only in detergents. The integral membrane protein character of the 31-K protein became apparent from its ability to insert into lecithin vesicles. Liposome-inserted 31-K protein binds 125I-labelled type II collagen in the presence of 0.5 M NaCl, while detergent-solubilized 31-K protein is dissociated from type II collagen by 0.05-0.1 M NaCl. Electron microscopic studies employing the rotary shadowing technique indicate that 31-K protein particles bind to the ends of collagen molecules. We propose that this glycoprotein serves as anchorage site for extracellular collagen to the chondrocyte membrane and thus may be involved in cell-matrix interactions in cartilage.

Animals↗
PubMedDate not supplied

[Indications and implementation of recommendations of the working group "Tissue Regeneration and Tissue Substitutes" for autologous chondrocyte transplantation (ACT)].

For the treatment of full-thickness articular cartilage lesions of the knee joint, as a result of trauma or osteochondritis dissecans, a variety of biological reconstruction techniques have been developed. Different studies, some of which were performed as randomised, prospective clinical studies, showed that the autologous chondrocyte transplantation (ACT) provides the most satisfying and reliable method of cartilage reconstruction in the adult when applied to defects exceeding 4 cm (2). Based on these results, ACT seems to be of economic benefit, as the risk of developing osteoarthritis correlates significantly with the size of the cartilage defect, when not treated properly and in time. Surveying the studies on basic scientific aspects of ACT, cartilage defect animal models and clinical studies, it can be concluded that clinical results of ACT depend on a variety of factors. In this review, published by the joined advisory board of the German Societies of Traumatology (DGU) and Orthopaedic Surgery (DGOOC), we summarize the current knowledge available and the state of the art concerning ACT. Especially we discuss the advantages of different procedures, methods for treating knee cartilage defects and factors that influence the outcome of the different treatment regimens, with the aim to develop guidelines for the correct indication and application of the ACT.

Adult↗
PubMedDate not supplied

[Do calcium and zinc ions influence matrix molecule synthesis of chondrocytes?].

The experiments described here tested the effect of various calcium (Ca) and Zinc (Zn) concentrations on cell proliferation and matrix molecule synthesis of fetal and adult bovine chondrocytes in monolayer cultures. Levels of Ca < 0.2 mM in a culture medium or the addition of Zn (0.1-50 microM) selectively promoted the production of collagen but did not affect significantly synthesis of proteoglycans. No change in proliferation of fetal and adult chondrocytes could be observed. In contrast 10 mM Ca promoted the hypertrophic differentiation of chondrocytes (e.g. expression of collagen type X). The results are related to calcium channel configurations in chondrocytes in the discussion.

Animals↗