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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 60 (1993), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Phosphatidylethanol is formed by phospholipase D in animal cells exposed to ethanol. Previous reports have demonstrated that the degradation of phosphatidylethanol is slow, indicating that this lipid may be present in the cells after ethanol itself has disappeared. Accumulation of an abnormal alcohol metabolite may influence cellular functions. In the present study, cultivation of NG108–15 neuroblastoma × glioma hybrid cells in the presence of ethanol resulted in an accumulation of phosphatidylethanol and a simultaneous increase in basal inositol 1,4,5-trisphosphate levels. The direct effects of phosphatidylethanol on the phosphoinositide signal transduction system were examined through incorporation of exogenous phosphatidylethanol into membranes of ethanol-naive cells. An incorporation amounting to 2.8% of cellular phospholipids was achieved after a 5-h incubation with 30 μM phosphatidylethanol. Phosphatidylethanol was found to cause a time-and dose-dependent increase in the basal levels of inositol 1,4,5-trisphosphate. The effects on inositol 1,4,5-trisphosphate levels of exogenously added phosphatidylethanol and ethanol exposure for 2 days were not additive. No effect on bradykinin-stimulated inositol 1,4,5-trisphosphate production could be detected. However, the increase in basal inositol 1,4,5-trisphosphate levels indicates that phosphatidylethanol affects inositol 1,4,5-trisphosphate turnover and emphasizes the importance of considering phosphatidylethanol as a possible mediator of ethanol-induced effects on cellular processes.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 59 (1992), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: The effects of MgCl2 on the binding of tritiated ligands to opioid binding sites in homogenates of guinea-pig brain in HEPES buffer have been studied. The binding of tritiated μ-, δ, and κ-opioid agonists was promoted in a concentration-dependent manner over a range of MgCl2 concentrations from 0.1 mM to 10 mM, as was binding of the nonselective antagonists [3H]diprenorphine and [3H]naloxone. At concentrations of MgCl2 above 10 mM reversal of this effect was observed. The effects of MgCl2 on binding parameters differed at each site. The promoting effects of MgCl2 were mimicked by MnCl2, CaCl2, and MgSO4, but CoCl2 and ZnCl2 were inhibitory. Following treatment of guinea-pig brain synaptosomes at pH 11.5 to eliminate G proteins, the binding of the μ-opioid agonist [3H][D-Ala2, MePhe4, Gly-ol5]enkephalin and [3H]naloxone was much reduced but binding of [3H]diprenorphine was unaffected. Under these conditions MgCl2 still promoted binding of [3H]diprenorphine. The results suggest that Mg2+ ions promote binding by an action at the opioid receptor, even in the absence of G protein, and that opioid antagonists may differ in their recognition of opioid receptor binding sites.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Long-term ethanol exposure is known to inhibit bradykinin-stimulated phosphoinositide hydrolysis in cultures of neuroblastoma × glioma 108–15 cells. In the present study, [3H]bradykinin binding, GTP-binding protein function, and phospholipase C activity were assayed in cells grown for 4 days in 100 mM ethanol with the aim of elucidating the molecular target of ethanol on signal transduction coupled to inositol trisphosphate and diacylglycerol formation. Ethanol exposure reduced guanosine 5′-O-(3-thiotriphosphate) [GTP(S)]- and, to a lesser extent, NaF/AlCl3-stimulated phosphoinositide hydrolysis, whereas it had no effect on the enzymatic activity of a phosphatidylinositol 4,5-bisphosphate-specific phospholipase C. [3H]Bradykinin binding in the absence of GTP(S) was not influenced by ethanol exposure. However, the reduction in [3H]bradykinin binding seen in control cells after addition of GTP analogue was inhibited in cells grown in ethanol-containing medium. The results indicate that long-term ethanol exposure exerts its effects on receptor-stimulated phosphoinositide hydrolysis primarily at the level of the GTP-binding protein.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 7414-7417 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The surface resistance R of melt-processing samples is investigated as a function of the radio wave amplitude H in the low frequency range. We found an unusual dependence R(H) for samples with high critical current density. The rate of change of R(H) has a minimum at amplitudes H around the lower critical magnetic field Hc. This phenomenon is explained within the proposed theoretical model which takes into account the critical intercrystallite currents as well as the intracrystallite ones. The nature of the effect is connected with the increase of the crystallite screening capability which occurs at the transition of the crystallites to the Bean critical state.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6370-6377 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The influence of the electromagnetic properties of the substrate upon the size effect in hard superconductors is theoretically studied. Within the frame of the critical state model we calculate the distribution of the magnetic induction and the electric field inside a superconducting plate subject to unilateral electromagnetic excitation. This calculation allows to obtain the dependences of surface impedance and absorptivity on the amplitude of the external signal. We find that the manifestation of the size effect in the ac response of the superconducting plate depends strongly on the value of the dielectric constant of the substrate. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 1060-1067 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The time-dependent tracer-diffusion properties of a nonspherical Brownian particle that interacts with a suspension of spherical particles are studied in terms of an idealized but nontrivial model system for which the predictions of the generalized Langevin equation approach to tracer diffusion can be calculated, and compared with the results of a computer simulation experiment. In the model, the nonspherical particle is represented by a linear array of NT (=2 or 3) spherical particles with nearest-neighbor separation ΔL. For this model, we calculate the rotational and the (transversal and longitudinal) translational mean squared displacements, both, directly from the computer simulation, and approximately using the generalized Langevin equation approach. The theory is found to reproduce qualitatively and quantitatively the main features of the results of the simulation experiment for these properties. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 1049-1059 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We present a Brownian dynamic simulation of the translational and rotational motion of an interacting nonspherical Brownian particle. This simulation experiment involves an idealized model system of a suspension of spherical colloidal particles with which the nonspherical particle interacts. The latter is represented as a rigid linear array of (two or three) spherical particles. The direct pair interactions between all the spheres in the system (including those of the tracer particle) are modeled by a repulsive Yukawa potential. For simplicity, the two-dimensional version of this simulation experiment is considered, and hydrodynamic interactions are ignored. From the simulation experiment, we determine the translational and rotational mean-square-displacement of the nonspherical tracer particle. Here we focus only on the early deviations, due to the direct interactions, from the short-time, free-diffusion regime. In the analysis of these results, use is made of the recently developed Generalized Langevin equation theory of tracer diffusion of nonspherical Brownian particles. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    International journal of cosmetic science 16 (1994), S. 0 
    ISSN: 1468-2494
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Nowadays, cosmetic as well as pharmaceutical forms must undergo many controls, i.e. in-process controls on the finished product and stability testing. The authors suggest using first derivative spectroscopy for active ingredients assay presenting an ultra-violet absorption. It offers the advantage of a direct assay through simple dilution and without active ingredient extraction.Tests were made on classic mixtures of the sunscreens benzimidazol and cinnamate derivative (pair 1), and a mixture of two benzophenones (pair 2). The studied forms were solutions in propylene glycol and commercialized W/O and O/W creams.After analytical method validation for each sunscreen by precision, reproducibility and repeatability studies, the percentages of error of the various assays have been reported in various preparations (solutions or creams).A comparative study between HPLC assay (traditionally used) and the proposed method was carried out. The results show that a highly significant linear correlation exists between the two methods for the four sunscreens (R 〉 0.992). The speed and simplicity of the first derivative spectrometric method should find applications in routine control or in development of cosmetic or pharmaceutical preparations.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the European Academy of Dermatology and Venereology 3 (1994), S. 0 
    ISSN: 1468-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: A case of β–δ thalassaemia and pseudoxanthoma elasticum without angioid streaks is reported. To the best of our knowledge, this association has not been reported previously. The possible pathogenic mechanisms of pseudoxanthoma elasticum in relation to chronic hemolytic diseases are discussed.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Industrial & engineering chemistry 46 (1954), S. 2509-2511 
    ISSN: 1520-5045
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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