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Biomedical subjects

F Doljanski

Publications and source records attributed to F Doljanski.

At least 19 recordsLinked to original sources
PubMed1992

On the generation of form by the continuous interactions between cells and their extracellular matrix.

The central issue of this essay is the problem of how multicellular organisms develop and maintain the complex architecture and intricate shape of tissues and organs. The concepts pattern formation, morphogenesis and differentiation are defined and discussed suggesting a distinction between processes that underlie uniformity (e.g. basic body plans) and those underlying inter- and intra-species variation. The initial stage of limb bone development--the formation of the mesenchymal condensation--is described in detail. On the basis of these data and many additional example from other developmental systems, the central role of continuous cell-ECM interactions in the generation of form is deduced. Evidence is provided as to the leading role of the mesenchymal-fibroblast-like cells in sculpturing tissue and organ architecture. It is proposed that a group of cells within their ECM, rather than the single cell, is the functional unit relevant to the generation of form. The continuous cell-ECM interactions lead to the generation of form not by a detailed obligate pathway, but rather by a process of 'selective stabilization' (Kirschner & Mitchison, 1986), i.e. a gradual organization into more stable structures, where existing structural configuration serve to increase the likelihood of certain configurations and reduce that of others. Data are quoted to support the notion that even cell division does not erase all the structural information imprinted in the cell. The role of the metazoan genome in morphogenesis is discussed in the light of the process of selective stabilization.

Animals↗
PubMed1990

Turnover of proteoglycans in skin fibroblast cultures derived from patients with mucopolysaccharidoses.

The turnover of proteoglycans in the extracellular matrix was studied in fibroblasts cultures derived from patients with mucopolysaccharidosis (MPS) and healthy donors. The cells were labelled with 35S-sulfate and 14C-glucosamine and it was found that in MPS-fibroblasts the rate of extracellular matrix turnover was hardly affected, where as the intracellular turnover was severely inhibited. Similar results were obtained with normal fibroblasts treated with 20 mM ammonia. Autoradiography revealed that MPS fibroblasts have a preferential accumulation of 35S-sulfate labelled material in the nuclear area, indicating that the nucleus may also be affected in MPS pathology. It is suggested that, although lysosomal enzymes are an important factor in intracellular proteoglycan turnover, they do not play a crucial role in the turnover of extracellular matrix proteoglycans.

Autoradiography↗
PubMed1986

Immunofluorescent characterization of fibronectin, laminin, and keratin in normal and neoplastic human mammary epithelial cells in culture and in breast tissue sections.

Employing indirect immunofluorescent staining, primary and secondary serum-free cultures and frozen sections of human mammary tissue, normal and neoplastic, were examined for the presence and distribution of fibronectin (FN) and keratin, and frozen sections also for laminin (LM). The epithelial cell purity of the cultures was confirmed by the observation that all cells stained with anti-keratin antibody. In confluent cultures, FN was absent at the apical cell surface, and was seen as a fibrillar matrix exclusively beneath the epithelial monolayer, at the cell-substratum interface. No differences were noted between normal and neoplastic cells in vitro. In sections of normal breast tissue, FN was localized in the basement membrane zone (BMZ) and in the connective tissue stroma. A distinguishing feature of the neoplastic tissue was the considerably more intensive anti-FN immunofluorescence of the stroma. In normal tissue sections, LM was present exclusively in the BMZ, where it formed a continuous, well-delineated, smooth line; this line was found to be distorted, interrupted, and sometimes entirely absent in the neoplastic tissue. The cytoplasm of all cultured cells, neoplastic as well as normal, exhibited a dense network of keratin filaments that was especially prominent around the nucleus. In the sections, keratin was ubiquitously present in the epithelial cells, predominantly along the interior border of the surface membrane; in the neoplastic tissue, this pattern was markedly disorganized, and some of the cells failed to express the substance.

Breast↗
PubMed1985

Presence of normal human cell surface antigens in plasma of athymic mice bearing a human colon carcinoma and in normal human plasma.

The mixed haemadsorption (MHA) method was employed for detection of several normal antigenic components on the surface of human colon carcinoma cells (HT-29). The antigens were expressed by cells in monolayer cultures and in suspensions prepared by monolayer trypsinization, and by cells of tumours growing progressively in athymic mice. The plasma of such animals bearing medium sized and large, non-necrotic tumours contained all the antigens, as determined by the radial diffusion immune haemolysis method (RDIH); the plasma of animals with small or large heavily necrotic tumours did not contain detectable amounts of any of the determinants. The half-life of the determinants in the circulation as extracellular entities was ca. 20 h. The same antigens, and fibronectin, were found to be ubiquitously represented in normal human plasma. It is proposed that the presence of membrane antigens in plasma is the result of physiological shedding of cell surface constituents by living cells.

Adenocarcinoma↗
PubMed1985

Cell interaction with the extracellular matrices produced by endothelial cells and fibroblasts.

The extracellular matrices (ECM) produced by cultured bovine corneal endothelial cells and chick embryo fibroblasts were compared for their induction of cell attachment, proliferation and differentiation. The corneal endothelial ECM (cECM) induced a comparable and rapid attachment and flattening of both human Ewing's sarcoma and colon carcinoma cells which utilize fibronectin and laminin as adhesive glycoproteins, respectively. In contrast, the ECM produced by fibroblasts (fECM) readily supported the attachment and flattening of Ewing's sarcoma cells but had only a small effect on the carcinoma cells. Vascular endothelial cells were stimulated to proliferate by both types of matrices, but to a lesser extent by the fECM. In contrast, the formation of a closely apposed, non-overlapping and contact-inhibited endothelial cell monolayer was only dictated by the cECM. Vascular endothelial cells cultured on fECM grew on top of each other and incorporated [3H]thymidine even late at confluency. Neurite outgrowth (ciliary ganglion cells) and network formation (adult rat oligodendrocytes) were promoted by both types of matrices but in a more consistent manner with the cECM. It is likely that the small amounts of laminin deposited by chick embryo fibroblasts into their ECM are responsible for its efficient induction of neurite outgrowth and for the limited degree of carcinoma cell attachment and flattening. It is thus demonstrated that differences in chemical composition and supramolecular arrangement between cECM and fECM result not only in differences in the attachment, spreading and proliferative responses of cells but also in the expression of their characteristic morphological appearance and differentiated functions.

Animals↗
PubMed1984

Patterns of fibronectin deposition in normal and neoplastic fibroblasts and mammary tissue.

Deposition of fibronectin (FN) was studied by indirect immunofluorescent staining, employing monospecific rabbit anti-human FN antibody, in the following 3 systems: cultures of cells derived from Rous sarcomas of chickens and of normal chick fibroblasts; frozen sections of chicken Rous sarcomas; and frozen sections of mouse and human mammary tissue, normal and neoplastic. The normal fibroblasts produced a well-oriented, delicate, fibrillar FN network. The sarcoma cells in culture also formed a FN-positive matrix, but one very different in appearance, consisting of coarse, unoriented strands. FN was also present abundantly between the cells of the sarcomas in vivo. In normal mammary tissue, FN was localized predominantly in the basal lamina region, well delineated from the surrounding FN-reactive stroma. The epithelial cells were generally, but not always, FN-negative. In apparently normal tissue areas of the breasts of mammary carcinoma patients, epithelial cells with highly reactive cell peripheries were frequently seen; the stroma surrounding the positive cells was often poor in FN and the basal lamina region lacked the substance. Mammary carcinoma cells were almost always negative, but it was characteristic of these tumours that the surrounding stroma displayed FN richly.

Animals↗
PubMed1980

Cell-surface shedding by fibroblasts in culture.

The metabolic fate of cell-surface components was studied by labeling the surface of cultured chick embryo cells with [14C]glucosamine for 24 h, or by lactoperoxidase-catalyzed radioiodination. The cells were then cultured further in label-free medium for 24 h. At different time intervals thereafter, cells and culture medium were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The radioactivity profile of the metabolically labeled material in the medium was similar to that of the [125I]lactoperoxidase-labeled cells. The rate of disappearance of labeled macromolecular components from the cell surface was a mirror image of the rate of accumulation of these components in the medium. Analysis on 7 to 20% acrylamide gradient slab gel revealed that most of the labeled macromolecules in the medium comigrate with the surface micromolecules obtained from intact cells. It thus appears that at least some cell-surface components are shed in undegraded form. The possible biomedical implications of the detection of intact cellular membrane components in the circulation are discussed.

Animals↗
PubMed1975

Reactivity of serum from rous-sarcoma-bearing chickens with autochthonous and with allogeneic tumor cells: preferential autochthonous recognition.

Complement-medicated cytotoxicity and indirect immunofluorescence assays showed that sera from random-bred chickens bearing Rous sarcoma (RS) tumors are usually more reactive in vitro against RS cells of autochthonous than of allogeneic origin. Absorption of such sera with autochthonous, but not with allogeneic, RS cells abrogated the fluorescence staining capacity. Sera from tumor-bearing birds did not stain normal chicken embryo cells (CEC), but reacted with a higher proportion of CEC transformed by the RS virus than with cultured PS tumor cells. Tumor cells incubated at 37 degrees C with autochthonous serum and fluorescent horse anti-chicken immunoglobulin conjugate displayed cell surface fluorescence patching.

Animals↗
PubMed1975

Osmotic behavior of normal and leukemic lymphocytes.

The response of normal human peripheral blood lymphocytes to a hypotonic environment may be divided into two phases: the cells first exhibit rapid osmotic swelling, followed by a slower shrinking phase, during which they regain their initial physiologic volume. This osmotic behavior is characteristic of most mammalian and avian nucleated cells so far examined. The normal human blood lymphocyte, however, shows the most rapid recovery phase (5 min). Lymphocytes from chronic lymphatic leukemia patients, in comparison, show a strikingly slower rate of return to their initial isotonic volumes. The mechanism underlying osmotic cell volume regulation and its significance are discussed.

Adolescent↗