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  • Cell & Developmental Biology  (3)
  • Organic Chemistry  (3)
  • Root  (2)
  • 1990-1994  (8)
  • 1945-1949
  • 1905-1909
  • 1
    Electronic Resource
    Electronic Resource
    Al3+-Ca2+ interactions in aluminum rhizotoxicity (1993)
    Springer
    Planta 192 (1993), S. 104-109 
    Details
    ISSN: 1432-2048
    Keywords: Aluminum toxicity ; Calcium displacement ; Electrical potential ; Root ; Triticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several mineral rhizotoxicities, including those induced by Al3+, H+, and Na+, can be relieved by elevated Ca2+ in the rooting medium. This leads to the hypothesis that the toxic cations displace Ca2+ from transport channels or surface ligands that must be occupied by Ca2+ in order for root elongation to occur. In this study with wheat (Triticum aestivum L.) seedlings, we have determined, in the case of Al3+, that (i) Ca2+, Mg2+, and Sr2+ are equally ameliorative, (ii) that root elongation does not increase as Ca2+ replaces Mg2+ or Sr2+ in the rooting media, and (iii) that rhizotoxicity is a function solely of Al3+ activity at the root-cell membrane surface as computed by a Gouy-Chapman-Stern model. The rhizotoxicity was indifferent to the computed membrane-surface Ca2+ activity. The rhizotoxicity induced by high levels of tris(ethylenediamine)cobaltic ion (TEC3+), in contrast to Al3+, was specifically relieved by Ca2+ at the membrane surface. The rhizotoxicity induced by H+ exhibited a weak specific response to Ca2+ at the membrane surface. We conclude that the Ca2+-displacement hypothesis fails in the case of Al3+ rhizotoxicity and that amelioration by cations (including monovalent cations) occurs because of decreased membrane-surface negativity and the consequent decrease in the membrane-surface activity of Al3+. However, TEC3+, but not Al3+, may be toxic because it inhibits Ca2+ uptake. The nature of the specific H+-Ca2+ interaction is uncertain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198699
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  • 2
    Electronic Resource
    Electronic Resource
    Al3+-Ca2+ interactions in aluminum rhizotoxicity (1993)
    Springer
    Planta 192 (1993), S. 98-103 
    Details
    ISSN: 1432-2048
    Keywords: Aluminum toxicity ; Calcium uptake ; Growth inhibition ; Root ; Triticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cation Al3+ is toxic to plants at micromolar concentrations and can severely inhibit root growth in solution experiments. Trivalent aluminum hydrolyzes in solution, and, apart from the Al3+ ion, which dominates speciation below pH 5.0, various mononuclear and polynuclear hydroxy-Al species can also occur (Kinraide 1991). Accumulating evidence suggests that Al3+ is the rhizotoxic species under the experimental conditions used in the present study (Kinraide 1991; Kinraide et al. 1992). The inhibition of Ca2+ uptake in roots by Al3+ has been proposed as a possible mechanism for Al3+ toxicity, and in this study the hypothesis was tested directly. Root growth and Ca2+ uptake were measured in 5-d-old seedlings of wheat (Triticum aestivum L. Thell) during exposure to Al3+ in a low-Ca2+ basal medium, and to Al3+ in the presence of added cations. Uptake of Ca2+ in whole roots and translocation to the shoot were measured using 45Ca2+, and localized measurements of net Ca2+ flux were also made at the root apex using the technique of microelectrode ion-flux estimation. Treatment with 2.64 μM AlCl3 in 226 μM CaCl2, at pH 4.5, severely inhibited root growth without affecting Ca2+ uptake. Addition of 30 mM Na2+, 3 mM Mg2+ or 50 μM tris(ethylenediamine)cobalt(III) to this Al3+ treatment restored root growth but significantly reduced Ca2+ uptake measured over the entire root system and at the root apex. The Al3+ and Ca2+ concentrations were adjusted so that the activities of the Al3+ and Ca2+ ions were constant in all solutions (1.5 μM and 200 μM, respectively). Root growth can be severely inhibited by Al3+ concentrations that do not affect Ca2+ uptake, while the addition of ameliorating cations depresses Ca2+ uptake. These results argue against the hypothesis that Al3+ inhibits root growth by reducing Ca2+ uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198698
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics of neuronal intermediate filaments: A developmental perspective (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 22 (1992), S. 81-91 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970220202
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  • 4
    Electronic Resource
    Electronic Resource
    Produktzusammensetzung der Kohlenwasserstoffgemische nach der BIRCH-Reduktion substituierter Benzene und säurekatalysierte Addition von Alkoholen an alkylsubstituierte Cyclohexene und Cyclohexa-1,4-diene (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 481-488 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Composition of Mixtures of Hydrocarbons after BIRCH-Reduction of Substituted Benzenes and Acid Catalyzed Addition of Alcohols to Alkylsubstituted Cyclohexenes and Cyclohexa-1,4-dienes.10 different benzene hydrocarbons 1, indane, tetraline, anisol and phenol are reduced by sodium in liquid ammonia in the presence of methanol to the BIRCH products 2. The product mixture compositions are determined through capillary GLC. On storage at + 6°C some rearomatization of the 1,4-cyclohexadienes 2 occurs. Data of the 1H- and 13C-n.m.r. spectra and also mass spectra of the BIRCH 1,4-dienes 2 are given. For comparison 4-alkoxycyclohexenes 4 and 1-alkoxy-1-methylcyclohexanes 8 are prepared and spectroscopically characterized. Acid-catalyzed addition of alcohols to the 1,4-cyclohexadiene systems is a slow process and gives the 4-alkoxy-4-alkylcyclohex-1-enes (4) only in moderate yields up to 30 %. Most of the products are dimers 5 and also oligomers 6 of the parent hydrocarbons 2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19913330315
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  • 5
    Electronic Resource
    Electronic Resource
    Dreikomponentenreaktionen. XX. Methoxymercurierung von Cyclohexa-1,4-dienen (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 447-453 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three Component Reactions. XX. Methoxymercuration of Cyclohexa-1,4-dienes.The methoxymercuration of several cyclohexa-1,4-dienes leads to insoluble mixtures of mono- and bismercuricompounds 2-4 and 5-7. After reduction with NaBH4/NaOH mixtures of methoxycyclohexenes and bismethoxycyclohexanes result. The result of capillary gaschromatographic analyses and n.m.r. spectra allow a semiquantitative evaluation of the reaction pathways.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19913330310
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  • 6
    Electronic Resource
    Electronic Resource
    1H-NMR Untersuchungen der Komplexbildung von Strontium mit Amidopodanden (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 1088-1092 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H.-N.M.R. Spectroscopic Evidence for the Complex Formation of Strontium Ions by Amido Podands
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320629
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  • 7
    Electronic Resource
    Electronic Resource
    Binding and activation of plasminogen on the surface of osteosarcoma cells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 159 (1994), S. 1-10 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Plasmin (Pm) is a broad action serine protease implicated in numerous physiological functions. In bone, Pm may play a role in growth, resorption, metastasis, and the activation of growth factors. The various components of the Pm system are known to bind and function on the cell surface of various cell types, but no pertinent data are available describing membrane-bound Pm or its zymogen, plasminogen (Pg), in either normal or neoplastic bone cells. We report here that Pg binds to the surface of the human osteosarcoma cell line MG-63 and is activated to Pm by endogenous urokinase plasminogen activator (uPA). These conclusions are based on experiments utilizing radiolabeled compounds and a cell surface proteolytic assay measuring amidolytic activity of Pm. 125I-Pg binding to cells was time dependent, saturable, reversible, and specific. Binding was characterized by a relatively low affinity (Kd ∼0.9 μM) and a high capacity (∼7.5 x 106 sites/cell). The binding of 125I-Pg was associated with lysine binding sites of the plasminogen molecule. Activation of 125I-Pg to 125I-Pm occurred on the cell surface and was dependent upon cell bound uPA, as determined by inhibitory antibodies. Binding of Pg to MG-63 monolayers represented ∼80% bound specifically to the cell surface and the remainder to the surrounding extracellular matrix. Either co-incubation with uPA or pre-incubation with Pm resulted in increased 125I-Pg binding to osteosarcoma cells. Cell surface Pm proteolytic activity was confirmed by an amidolytic chromogenic assay. Both Pm and Pg bound to cells with Pg being activated by endogenous uPA. Plasmin activated on the cell surface was partially protected from inhibition by α2-antiPm (requiring Pm lysine binding site interaction) but inhibited by aprotinin, (interacting directly with the Pm catalytic site). Resistance of cell bound Pm to α2-antiPm inhibition suggests that cell surface proteolysis can occur in the presence of a soluble Pm inhibitor known to exist in the extracellular space. Based on these results, we speculate that the various bone physiological processes implicating Pm may occur at or near the bone cell surface. © 1994 wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041590102
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  • 8
    Electronic Resource
    Electronic Resource
    Association of increased basement membrane invasiveness with absence of estrogen receptor and expression of vimentin in human breast cancer cell lines (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 150 (1992), S. 534-544 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lack of estrogen receptor (ER) and presence of vimentin (VIM) associate with poor prognosis in human breast cancer. We have explored the relationships between ER, VIM, and invasiveness in human breast cancer cell lines. In the matrigel outgrowth assay, ER+/VIM- (MCF-7, T47D, ZR-75-1), and ER-/VIM- (MDA-MB-468, SK-Br-3) cell lines were uninvasive, while ER-/VIM+ (BT549, MDA-MB-231, MDA-MB-435, MDA-MB-436, Hs578T) lines formed invasive, penetrating colonies. Similarly, ER-/VIM+ cell lines were significantly more invasive than either the ER+/VIM- or ER-/VIM- cell lines in the Boyden chamber chemoinvasion assay. Invasive activity in nude mice was only seen with ER-/VIM+ cell lines MDA-MB-231, MDA-MB-435 and MDA-MB-436. Hs578T cells (ER-/VIM +) showed hematogenous dissemination to the lungs in one of five mice, but lacked local invasion. The ER-/VIM+ MCF-7ADR subline was significantly more active than the MCF-7 cells in vitro, but resembled the wild-type MCF-7 parent in in vivo activity. Data from these cell lines suggest that human breast cancer progression results first in the loss of ER, and subsequently in VIM acquisition, the latter being associated with increased metastatic potential through enhanced invasiveness. The MCF-7ADR data provide evidence that this transition can occur in human breast cancer cells. Vimentin expression may provide useful insights into mechanisms of invasion and/or breast cancer cell progression.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041500314
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