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  • 1995-1999  (149)
  • 1955-1959  (17)
  • 1880-1889  (3)
  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 65 (1995), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: We examined the interdependence of calpain and protein kinase C (PKC) activities on neurite outgrowth in SH-SY-5Y human neuroblastoma cells. SH-SY-5Y cells elaborated neurites when deprived of serum or after a specific thrombin inhibitor, hirudin, was added to serum-containing medium. The extent of neurite outgrowth under these conditions was enhanced by treatment of cells with the cell-permeant cysteine protease inhibitors N-acetyl-leucyl-leucyl-norleucinal (“C1”) and calpeptin or by the phospholipid-mediated intracellular delivery of either a recombinant peptide corresponding to a conserved inhibitory sequence of human calpastatin or a neutralizing anti-calpain antisera. Calpain inhibition in intact cells was confirmed by immunoblot analysis showing inhibition of calpain autolysis and reduced proteolysis of the known calpain substrates fodrin and microtubule-associated protein 1. The above inhibitory peptides and antiserum did not induce neurites in medium containing serum but lacking hirudin, suggesting that increased surface protein adhesiveness is a prerequisite for enhancement of neurite outgrowth by calpain inhibition. Treatment of cells with the PKC inhibitor H7, staurosporine, or sphingosine induced neurite outgrowth independently of serum concentration. Because calpain is thought to regulate PKC activity, we examined this potential interrelationship during neurite outgrowth. Simultaneous treatment with calpain and PKC inhibitors did not produce additive or synergistic effects on neurite outgrowth. PKC activation by 2-O-tetradecanoylphorbol 13-acetate (TPA) prevented and reversed both neurite initiation by serum deprivation and its enhancement by calpain inhibitors. Treatment of cells with the calpain inhibitor C1 retarded PKC down-regulation following TPA treatment. Cell-free analyses demonstrated the relative specificity of various protease and kinase inhibitors for calpain and PKC and confirmed the ability of millimolar calcium-requiring calpain to cleave the SH-SY-5Y PKC regulatory subunit from the catalytic subunit, yielding a free catalytic subunit (protein kinase M). These findings suggest that the influence of PKC on neurite outgrowth is downstream from that of surface adhesiveness and calpain activity.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Calcium influx into SH-SY5Y human neuroblastoma cells after ionophore treatment or transient permeabilization in calcium-containing medium increased ALZ-50 immunoreactivity markedly. This increase was prevented by inhibitors active against calpain or against protein kinase C (PKC), suggesting that both of these enzymes were required to mediate the effect of calcium influx on ALZ-50 immunoreactivity. Treatment with PKC activator TPA increased ALZ-50 immunoreactivity in the absence of calcium influx or after intracellular delivery of the specific calpain inhibitor calpastatin, indicating that the influence of PKC was downstream from that of calpain. Calcium influx also resulted in μ-calpain autolysis (one index of calpain activation) and the transient appearance of PKM (i.e., free PKC catalytic subunits, generated by calpain-mediated cleavage of the regulatory and catalytic PKC domains). Inhibition of calpain within intact cells resulted in a dramatic increase in steady-state levels of total τ (migrating at 46–52 kDa) but resulted in a relatively minor increase in 68-kDa ALZ-50-immunoreactive τ isoforms. Although calcium influx into intact cells resulted in accumulation of ALZ-50 immunoreactivity, total τ levels were, by contrast, rapidly depleted. Incubation of isolated fractions with calpain in the presence of calcium indicated that ALZ-50-immunoreactive τ isoforms were more resistant to calpain-mediated proteolysis than were non-ALZ-50 reactive τ isoforms. These data therefore indicate that calpain may regulate τ levels directly via proteolysis and indirectly through PKC activation. A consequence of the latter action is altered τ phosphorylation, perhaps involving one or more kinase cascades, and the preferential accumulation of ALZ-50-immunoreactive τ isoforms due to their relative resistance to degradation. These findings provide a basis for the possibility that disregulation of calcium homeostasis may contribute to the pathological levels of conversion of τ to A68 by hyperactivation of the calpain/PKC system.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1520-6041
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Industrial & engineering chemistry 47 (1955), S. 83-85 
    ISSN: 1520-5045
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Industrial & engineering chemistry 48 (1956), S. 1990-1995 
    ISSN: 1520-5045
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Chemistry of materials 7 (1995), S. 2342-2349 
    ISSN: 1520-5002
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 1238-1243 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Ultra-short-pulse reflectometry is studied by means of the numerical integration of one- and two-dimensional full-wave equations for ordinary and extraordinary modes propagating in a plasma. The numerical calculations illustrate the use of the reflection of ultra-short-pulse microwaves as an effective probe of the density or magnetic profile in the presence of density or magnetic fluctuations in the plasma. Bragg resonance effects can be identified in the reflected signals, which give information on fluctuations. It is also demonstrated that ultra-short-pulse reflectometry can be used to perform correlation reflectometry measurements in which correlation lengths for density fluctuations are deduced from the observed cross-correlation function of phase shifts as a function of frequency. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 477-477 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Ultra-short-pulse reflectometry is studied by means of the numerical integration of one- and two-dimensional full-wave equations for ordinary and extraordinary modes propagating in a plasma. The numerical calculations illustrate the use of the reflection of ultra-short-pulse microwaves as an effective probe of the density or magnetic profile in the presence of density or magnetic fluctuations in the plasma. Bragg resonance effects can be identified in the reflected signals, which give information on fluctuations. It is also demonstrated that ultra-short-pulse reflectometry can be used to perform correlation reflectometry measurements in which correlation lengths for density fluctuations are deduced from the observed cross-correlation function of phase shifts as a function of frequency. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 8 (1996), S. 1945-1953 
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present the results of a study of the structure of a parallel compressible mixing layer in a binary mixture of gases. The gases included in this study are hydrogen (H2), helium (He), nitrogen (N2), oxygen (O2), neon (Ne) and argon (Ar). Profiles of the variation of the Lewis and Prandtl numbers across the mixing layer for all 30 combinations of gases are given. It is shown that the Lewis number can vary by as much as a factor of 8 and the Prandtl number by a factor of 2 across the mixing layer. Thus assuming constant values for the Lewis and Prandtl numbers of a binary gas mixture in the shear layer, as is done in many theoretical studies, is a poor approximation. We also present profiles of the velocity, mass fraction, temperature and density for representative binary gas mixtures at zero and supersonic Mach numbers. We show that the shape of these profiles is strongly dependent on which gases are in the mixture as well as on whether the denser gas is in the fast stream or the slow stream. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 117 (1995), S. 6396-6397 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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