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  • 1
    Publication Date: 1977-05-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 2
    Publication Date: 2001-10-15
    Description: In monolayer cultures human rheumatoid synovial fibroblasts (HRSF) secrete gelatinase A (MMP-2) and, unlike other human fibroblasts, to a minor extent also gelatinase B (MMP-9) as inactive proenzymes. In this regard HRSF resemble the fibrosarcoma cell line HT-1080. Unlike HT-1080, however, HRSF do not increase the secretion of MMP-9 in response to phorbol-12-myristate-13-acetate. This indicates that in HRSF the protein kinase C pathway for an enhanced MMP-9 secretion is inactive. None of the substances used in our study increased MMP-9 secretion, but some of them inhibited MMP-9 secretion. The secretion of MMP-2 could not be enhanced either, not even by dbcAMP, which has been reported to be effective in Sertoli and peritubular cells. Activation of MMP-2 in HRSF could be induced by treatment with concanavalin A (ConA) or cytochalasin D, as was shown for other cell types. This activation was not accompanied by a significant change in the amount of secreted TIMP-1 and TIMP-2. In contrast to reports on human skin fibroblasts, however, the activation of MMP-2 could not be induced in HRSF by treatment of the cells with monensin or sodium orthovanadate. Moreover, monensin was shown to act as an inhibitor of ConA or cytochalasin Dmediated activation. Additionally, and in contrast to a report on a rat fibroblast cell line, MMP-2 activation is not mediated via the MAP kinase pathway in HRSF: PD 98059, a specific inhibitor of MAP kinase kinase, did not inhibit the activation of MMP-2. Similarly ineffective were PD 169316, an inhibitor for p38 MAP kinase, other inhibitors for protein kinases as lavendustin A, Gö 6983, wortmannin, rapamycin, as well as the protein tyrosine kinase inhibitors herbimycin A and genistein. Only staurosporin, a broad spectrum inhibitor of protein kinases, and the ionophores monensin and A 23187 effectively inhibited MMP-2 activation in HRSF. Our results demonstrate that MMP-2 can be activated by quite different pathways, and that different cells, even when belonging to the fibroblast family, do not necessarily use the same activating pathways.
    Print ISSN: 1431-6730
    Electronic ISSN: 1437-4315
    Topics: Biology , Chemistry and Pharmacology
    Published by De Gruyter
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Cell Differentiation and Development 25 (1988), S. 145-154 
    ISSN: 0922-3371
    Keywords: Calvarial cell ; Mineralization in vitro ; Organoid culture
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 180 (1977), S. 383-401 
    ISSN: 1432-0878
    Keywords: Oral epithelium ; Epithelial differentiation ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Epithel der normalen menschlichen Alveolarschleimhaut im vorderen Vestibulum wurde einer stereologischen Analyse unterworfen. Acht Biopsien wurden in der Mitte zwischen mukogingivaler Grenzlinie und Fornix bei 20 bis 50 Jahre alten Frauen entnommen und für licht- und elektronenmikroskopische Studien verarbeitet. Auf zwei Vergrößerungsstufen wurden Stichproben elektronenmikroskopischer Aufnahmen aus vier Schichten im Bereich epithelialer Leisten entnommen. Insgesamt 860 Bilder wurden mit Hilfe stereologischer Punktzählverfahren analysiert. Das Alveolarepithel war im Durchschnitt 0,26 mm dick, wurde gelegentlich von kurzen, schlanken Bindegewebspapillen durchzogen und bestand aus einem schmalen basalen und suprabasalen, sowie einem breiten, homogen-strukturierten Ober-flächenkompartiment. Es wies ein Differenzierungsmuster auf, das, in der Mehrzahl der Fälle, große Ähnlichkeit mit dem des menschlichen Wangenepithels zeigte, aber durchschnittlich weniger stark ausgereifte Oberflächenzellen hervorbrachte. Dieses Muster wurde zur Hauptsache durch einen Anstieg der Filamentdichte (der Filamentdurchmesser betrug etwa 98 Å), einen entsprechenden Abfall der Volumendichte der zytoplasmatischen Grundsubstanz, der Bildung von membranversteifenden Granula und durch individuell unterschiedlich stark ausgeprägte Glykogenablagerungen geprägt. In einigen Fällen wurde ein gemischtes Differenzierungsmuster gefunden. Die strukturelle Organisation des Alveolarepithels, wie auch die des Wangenepithels, ist mit der funktionellen Dehnbarkeit dieser Schleimhautregionen vereinbar.
    Notes: Summary The epithelium of normal human alveolar mucosa originating from the anterior vestibulum was subjected to stereologic analysis. Eight biopsies were collected half-way between the muco gingival junction and the vestibular fornix from 20 to 50 year-old females, and processed for light and electron microscopy. At two levels of magnification, electron micrographs were sampled from four artificially selected strata in regions of epithelial ridges. Stereologic point counting based on a computer-aided system for analyzing stratified epithelia served for examining a total of about 860 electron micrographs. The alveolar epithelium was 0.26 mm thick, occasionally interdigitated by short, slender connective tissue papillae, and consisted of (1) a narrow basal and suprabasal, and (2) a broad spinous and surface compartment. It displayed a differentiation pattern which, in most subjects studied, was similar to that of normal human buccal epithelium, however, on the average, produced less mature surface cells. This pattern was expressed mainly by a density increase of cytoplasmic filaments (98 Å in diameter), a concomitant decrease of the cytoplasmic ground substance, the formation of dark-cored membrane coating granules, and individually variable amounts of glycogen deposition. In some subjects, a mixed differentiation pattern was found. The structural organization of alveolar epithelium, in analogy to cheek epithelium, was compatible with the function of distensibility.
    Type of Medium: Electronic Resource
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