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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 108 (1991), S. 133-140 
    ISSN: 1573-4919
    Keywords: plasminogen ; receptors ; endothelial cells ; fibrinolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract To identify and characterize endothelial cell surface components that bind plasminogen, we used ligand-blotting to study binding of plasminogen to sodium dodecyl sulphate solubilized extracts of human umbilical vein endothelial cells. It was observed that glu-plasminogen bound predominantly to a 45 kDa endothelial cell polypeptide. The interaction of labelled glu-plasminogen with this polypeptide was reversible and specific as the binding could be inhibited by both excess cold lysine and unlabelled glu-plasminogen but not by unrelated proteins. Binding of glu-plasminogen to cell extracts prepared from endothelial cells that had been pretreated with proteinase K was significantly reduced indicating that the 45 kDa polypeptide is a cell-surface protein. The cell-surface localization of the 45 kDa polypeptide was also indicated by the positive interaction of glu-plasminogen with membrane fractions of endothelial cells. Lys-plasminogen also interacted with the 45 kDa polypeptide in a specific manner and reversibility experiments indicated that lysplasminogen could also displace the bound glu-plasminogen. Since binding of plasminogen to the 45 kDa endothelial cell surface polypeptide was very similar to plasminogen binding to intact endothelial cells, we propose that the 45 kDa protein represents one of the major receptors for plasminogen on human endothelial cells.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 91 (1977), S. 69-77 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A method, based on the differing capacities of cells to adhere to a column of polyester fibres, has been described for separating human bone marrow cells into a nonadherent and an adherent fraction. The effect of this cell separation procedure on colony formation by erythroid progenitor cells was investigated. In contrast to the unseparated population, it was found that erythropoietin-dependent erythroid colony formation by nonadherent cells could be considerably enhanced by the addition of leukocyte conditioned medium to the cultures. Similar erythroid enhancing activity was also detected in a partially purified preparation of granulocytic colony stimulating activity obtained from human embryo kidney culture supernatants.Erythroid colony formation in the absence of added erythropoietin, by non-adherent bone marrow cells from patients with polycythemia rubra vera, were also enhanced by the addition of LCM to the cultures. This finding suggests that the enhancing factor in LCM may not be dependent on the presence of erythropoietin in the cultures for its activity.While the cellular mechanisms by which leukocyte conditioned medium enhances eyrthroid growth remain to be determined, the data presented provides strong evidence for the view that the plating efficiency of erythroid progenitor cells is determined not only be the concentration of erythropoietin, but also by the presence of leukocyte conditioned medium in the cultures.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 114 (1983), S. 209-214 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of 12-O-tetradecanoylphorbol 13-acetate (TPA) on human hematopoietic cells has been investigated. It was found that 1-10 ng/ml of TPA totally abrogated erythroid and granulocytic colony growth and, simultaneously in the presence of PHA, stimulated T-lymphocyte colony formation. TPA concentrations insufficient to inhibit myeloid colony growth also failed to stimulate lymphocyte colony formation. Optimal culture conditions for the growth of these colonies required the presence of TPA, PHA, and leukocyte-conditioned medium in the cultures. Cells within the colonies were 80-90% E-rosette positive and by monoclonal antibody characterization contained 45-66% OKT3-positive cells. Colony-forming cells were found in both E-rosette-positive and-negative fractions. Although by cell surface marker characterization the cells within the colonies had properties of T-cells, the exact relationship of cells forming colonies under these conditions to those detected in other T-cell colony assays remain to be determined.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The maintenance of hemopoietic precursors in long-term liquid bone marrow cultures (LTBMC) is associated with the presence of an adherent stromal layer composed of heterogeneous cell populations. We have used a culture assay to promote the growth of one of its cellular components and characterize its properties. Freshly obtained bone marrow cells and cells derived from the adherent layer of LTBMC were grown in methylcellulose-clotted plasma in the presence of phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM), hydrocortisone (HC), and citrated normal human plasma. Both sources contained cells (CFU-RF) that gave rise to colonies of cells with a reticulofibroblastoid appearance. In the presence of HC, most colonies contained lipid-laden cells. Colonies could be further propagated as adherent layers when transferred into liquid cultures. These cells produced laminin, fibronectin, and collagen types I, III, IV, and V. They were negative for Von Willebrand factor VIII. The ability to synthesize laminin and collagen type IV distinguished these cells from a population of previously described bone marrow fibroblasts (CFU-F). The relationship of CFU-RF to hemopoietic precursors was investigated using patients with chronic myeloid leukemia and bone marrow transplant recipients. Cells within CFU-RF-derived colonies were uniformly negative for the Philadelphia chromosome, thus making it unlikely that they belonged to the malignant hemopoietic clone. CFU-RF-derived colonies in bone marrow transplant recipients were found to be exclusively of host origin. Both observations support the view that CFU-RF is not part of the repertoire of hemopoietic stem cells.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 99 (1979), S. 233-238 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ability of human serum to support erythroid an dgranulocytic colony formation has been investigated. It was found that normal human serum could replace fetal calf serum in the cultures and was able to support the growth of these hemopoietic colonies. Serum fractions enriched for low density lipoproteins, either by precipitation with Heparin-Mn++ or by ultra-centrifugation, was found to contain this growth supporting activity of human serum.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 154 (1993), S. 496-505 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously shown that although DDAVP (1-deamino-8-D-arginine vasopressin), a synthetic analogue of the natural hormone arginine vasopressin, does not directly promote release of vWf from human umbilical vein endothelial cells (ECs), enhanced release does occur when ECs were exposed to either monocytes or to supernatants recovered from DDAVP-treated monocytes. In the present study, we have found that exposure of monocytes to DDAVP did not increase secretion of interleukins (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF-α), growth factors G-CSF (granulocyte-), GM-CSF (granulocyte, monocyte-colony stimulating factor), prostaglandins (PG) E2, PGF2α, or PGI2 or purine nucleotides such as ATP and ADP. However, increased levels of platelet-activating factor (PAF) were secreted by DDAVP-treated monocytes in a time- and dose-dependent manner that positively correlated with the enhancement in vWf release from ECs. Moreover, this effect could also be elicited when lipid extracts of these supernatants or purified PAF were added directly to ECs. This response could be inhibited with (±)-trans-2,5-Bis(3,4,5-trimethoxyphenyl)-1,3-dioxolane, a specific PAF receptor antagonist, when the ECs were exposed to supernatants from DDAVP-treated monocytes or to pure PAF. The present data indicate that enhanced secretion of PAF from monocytes is one mechanism whereby DDAVP can provoke release of vWf from ECs. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 148 (1991), S. 440-445 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using long-term culture techniques, it has been shown that stromal cells in the marrow microenvironment are essential for the continued production and self-renewal of hematopoietic stem cells. We previously reported the development of a methylcellulose colony assay for a population of marrow stromal progenitors called CFU-RF. In this paper, a method is described for subculturing cells from individual CFU-RF-derived colonies to allow conditioned medium production (StCM). StCM, prepared in this way, was found to possess an erythroid lineage-specific activity that stimulated the formation of macroscopic erythroid colonies in cultures containing erythropoietin (epo). Using dose-response curves, the KG1 colony assay, and antibody neutralization, it was shown that the activity could not be attributed to interleukin 3 (IL3) or granulocyte-macrophage colony-stimulating factor (GM-CSF). However, it was further shown that a monolayer of stromal cells, which had earlier been producing the erythroid activity, could be stimulated by IL1 to produce granulocytic colony-stimulating activity, but only as long as IL1 was present in the culture medium. These findings indicate a mechanism whereby the same stromal population could be modulated to promote growth and differentiation of different hematopoietic lineages.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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