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  • 1
    ISSN: 0003-276X
    Keywords: Tooth development ; Mouse ; Protein translocation ; Amelogenin ; Epithelial-mesenchymal interactions ; Intercellular communication ; Immunocytochemistry ; Differential gene expression ; In vitro organ culture ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The developmental problem of how dental epithelia and/or dental papilla ectomesenchyme induce and/or up- or down-regulate tooth formation are as yet unresolved issues. We have desinged studies to map the synthesis and fate pathways of secreted amelogenin proteins from Kallenbach differentiation zones II-IV during in vivo and in vitro mouse mandibular first molar tooth development (M1). Tooth organs from cap, bell, and crown stages were processed for reverse transcriptase/polymerase chain reaction (RT-PCR) and high resolution Protein A immunocytochemistry using anti-amelogenin and anti-peptide antibodies. Cap stage M1 were cultured for periods ranging from 10-21 days in vitro using either serumless, or 15% fetal calf sera-supplemented, chemically-defined medium. Amelogenin transcripts are expressed in the mouse embryonic molar from E15 through early postnatal development. Amelogenin antigens were first detected in Kallenbach's differentiation zone II. Amelogenin proteins secreted from preameloblasts were identified along cell processes and cell surfaces of odontoblasts adjacent to forming mantle dentine extracellular matrix (ECM) prior to biomineralization. Amelogenin proteins were restricted to forming endocytotic vesicles, clathrin-coated vesicles, and lysozomes within odontoblasts. At later stages (e.g. 2 days postnatal development), enamel proteins were not identified in odontoblasts or predentine matrix following mineralization. Comparable observations for stages of development were noted for in vitro cultured tooth explants. Preameloblasts synthesize and secrete amelogenin proteins which bind to odontoblast cell surfaces possibly through the process of receptor-mediated endocytosis. We conclude that amelogenin proteins secreted from preameloblasts, prior to the initiation of biomineralization, were translocated to odontoblasts to serve as yet unknown biological functions. © 1994 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 29 (1994), S. 204-210 
    ISSN: 1059-910X
    Keywords: Desipramine ; Mepacrine ; 4-Bromphenacyl bromide ; Arachidonic acid ; 6-Hydroxydopamine ; Depression ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In previous experiments, we have shown that antidepressants such as desipramine (DMI) can induce axonal regeneration of noradrenergic locus coeruleus neurons. In this article, we suggest that phospholipase A2 is involved in the molecular mechanism of the antidepressant-induced regeneration of brain noradrenergic axons. The effects of the PLA2 inhibitors, mepacrine (MEP) or 4-bromphenacyl bromide (BPB), upon the DMI-induced regeneration of noradrenergic axons in the rat cerebral cortex were assessed by either histofluorescence or immunohistochemistry using an antibody to dopamine-beta-hydroxylase. Symmetrical sites of the frontal cortex in both hemispheres were pretreated with 6-hydroxydopamine (6-OHDA). Then, the same cortical site of one hemisphere was infused with DMI by means of osmotic minipumps for more than 2 weeks, while the corresponding cortical site of the other hemisphere was infused with DMI plus MEP or BPB. It was found that the PLA2 inhibitors could attenuate the DMI-induced regeneration of noradrenergic axons. Thus, if axonal retraction or degeneration of brain noradrenergic neurons is involved in the pathogenesis of clinical depression, elucidating the malfunction of the PLA2 systems may provide substantial evidence to aid in our understanding of the cause of depression at the molecular level. © 1994 Wiley-Liss, Inc.
    Additional Material: 8 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 159 (1994), S. 213-220 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Endothelin-1 (ET-1) is an endothelium-derived 21 amino acid vasoconstrictor peptide possessing two intrachain disulfide bridges. Recently it has become evident that isoforms of ET (ET-1, -2, and -3) have a wide range of pharmacological effects in various tissues and act as autocrine/paracrine factors. We demonstrate here that ET-1 is secreted from normal human keratinocytes and may work as an autocrine growth factor through a specific receptor. In this study, human foreskin keratinocytes were cultured in serum-free MCDB 153 medium. Cell growth and [3H] thymidine incorporation in low and high Ca++ concentration media was stimulated by ET-1, -2, and -3 with similar potencies. The strongest response was observed at 10 nM ETs, whereas stimulatory activity was reduced at 100 nM. ETs suppressed keratinocyte differentiation as measured by reactivity with involucrin antibody. Plasminogen activator activity (mainly urokinase) in the medium was also stimulated by the addition of 10 nM ETs. ET-1-like immunoreactivity measured by radioimmunoassay was 1.4 fmol/day/106 cells in non-treated condition medium. Among the various cytokines, tumor necrosis factor-α (TNF-α), interleukin-1α, and transforming growth factor-β stimulated ET-1 secretion in a dose-dependent manner. The strongest response (ten-fold) was observed upon the addition of 10 ng/ml TNF-α. Scatchard plot analysis of [125I] ET-1 binding to keratinocytes revealed the presence of a single class of high affinity receptors (KD 50 pM, 9 x 103 sites/cell). Binding was competitively inhibited by the addition of unlabeled ET-1 and -2 with similar affinities and by ET-3 with weaker affinity. ET-1 mRNA expression in keratinocytes was detected by reverse transcription-polymerase chain reaction and was increased by treatment with 10 ng/ml TNF-α. These results suggest that ET-1 acts as an autocrine growth factor for keratinocytes through a specific receptor. © 1994 wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 159 (1994), S. 415-422 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We wished to determine whether hyaluronan would affect the attachment of epithelial cells to extracellular matrix proteins. Multiwell tissue culture plates were coated with human plasma fibronectin, laminin, or collagen type IV (0.01-10.0 μg/ml). Single-cell suspensions of rabbit corneal epithelial cells were placed in the wells, and after 45 minutes incubation the cells adhering to the matrix proteins were stained and counted. Cells attached to all three types of proteins. Preincubation of the matrix proteins with hyaluronan (0.1-1.0 mg/ml) significantly increased the number of cells attached to the fibronectin matrix, but it did not increase the numbers of cells attached to laminin or collagen type IV. Hyaluronidase inhibited this stimulatory effect. Glycosaminoglcyans other than hyaluronan (chondroitin sulfate, keratan sulfate, or heparan sulfate) failed to increase the numbers of attached cells. Treatment of the fibronectin matrix with monoclonal antibodies against the cell-binding domain of fibronectin (FN12-8 or FN30-8, 0.03-0.3 mg/ml, for 1 hour), before or after hyaluronan treatment, significantly decreased the numbers of attached cells. Monoclonal antibody against the fibrin- and heparin-binding domain at the N-terminal (FN9-1), however, significantly decreased the number of attached cells only when this antibody treatment preceded the hyaluronan treatment. Preincubation of the cells with hyaluronan had no effect; preincubation with GRGDSP (1 mg/ml), a synthetic peptide that blocks the cell surface receptor for fibronectin, significantly decreased cell attachment whether the fibronectin matrix was treated with hyaluronan or not. Further studies demonstrated that monoclonal antibody against the fibrin- and heparin-binding domain at the N-terminal of plasma fibronectin prevented radiolabeled hyaluronan from binding to fibronectin; likewise, the isolated N-terminal fragment, coupled with Sepharose 4B, bound to hyaluronan in columns. We conclude that hyaluronan binds to a fibrin- and heparin-binding domain at the N-terminal of plasma fibronectin and facilitates the attachment of epithelial cells. © 1994 wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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