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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 303 (1978), S. 139-144 
    ISSN: 1432-1912
    Keywords: α-Adrenoceptors ; Renin ; Isoprenaline ; Tyramine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of the indirect sympathomimetic agent tyramine on the isoprenaline-induced increase in plasma renin concentration was investigated in conscious rats. Tyramine caused a dose-dependent decrease in the isoprenaline-induced elevation of plasma renin concentration. Pretreatment of the rats with reserpine abolished this effect of tyramine, indicating that tyramine released catecholamines which acted on the inhibitory adrenoceptors. Pretreatment with phenoxybenzamine, an α-adrenoceptor antagonist, also abolished the inhibitory effect of tyramine on renin release, indicating that α-adrenoceptors mediated the observed inhibition of renin release. In rats with chronically denervated kidneys tyramine did not inhibit renin release. It is concluded that catecholamines which are released from renal sympathetic nerve endings can suppress renin release by activating α-adrenoceptors.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1912
    Keywords: α-Adrenoceptors ; Isoprenaline ; Renin ; Sympathetic nervous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The importance of the sympatho-adrenal system for the isoprenaline-induced increase in plasma renin concentration was investigated in conscious rats. Ganglionic blockade by trimethidinium (10 mg kg−1) increased the dose-dependent elevation of plasma renin concentration induced by isoprenaline (0.03–0.48 μg kg−1 min−1). Also treatment of the rats with guanethidine (6 mg kg−1) or reserpine (2.5 mg kg−1, given 16 and 7 h prior to the experiments) further increased the effect of isoprenaline (0.5 μg kg−1 min−1) on plasma renin concentration. Unilateral renal denervation combined with contralateral nephrectomy doubled the effect of the β-sympathomimetic amine on renin release. The α-adrenoceptor antagonist phenoxybenzamine (3 mg kg−1) also enhanced the effect of isoprenaline on this parameter. It is concluded that apart from a stimulation of renin release via β-adrenoceptors the sympathetic nervous system may inhibit renin release via stimulation of α-adrenoceptors.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 290 (1975), S. 315-321 
    ISSN: 1432-1912
    Keywords: Isoprenaline ; Renin ; Vasoconstrictors ; Macula densa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The mechanism of the increase in plasma renin concentration caused by the β-sympathomimetic agent isoprenaline has been further investigated. Rats were pretreated by occluding the left renal artery for 2 hrs, thus rendering the macula densa cells of this kidney nonfunctioning. After contralateral nephrectomy infusion of isoprenaline (1.5 μg/kg min) still caused a strong increase in plasma renin concentration. This increase was significantly suppressed by simultaneous infusion of angiotensin II (1.0 μg/kg min), the α-sympathomimetic amine phenylephrine (60 μg/kg min) or octapressin (10 mU/kg min). The results exclude any mediator-role of the macula densa receptors in the isoprenaline-induced release of renin. The possibility of a stimulation of renin release via the baroreceptors or a direct “secretomotoric” action of isoprenaline is discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 1365-1379 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The four-center solid-state photopolymerization of distyrylpyrazine (DSP) and of 2,6-naphthalene bis(acrylic acid-2,4-dichloro phenyl ester) (NBA-DCP) was investigated by x-ray and microscopic techniques. In both cases the polymer grows as a separate product phase topotactically well arranged with respect to the monomer matrix. In the case of polymerization of DSP the space group of the monomer (Pbca) is not maintained but the polymer phase has space group P21ca. Nucleation and growth of the polymer phase was observed by light and electron microscopy. Nucleation occurs at defect sites. The polymer grows at different rates in different crystallographic directions which were identified by electron diffraction in the case of DSP. Polymerization thus occurs in the transition region between monomer crystal and product phase and not in the bulk of the crystal so that the four-center-type photopolymerization is best described as a heterogeneous solid-state reaction.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1881-1891 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A terpolymer of butadiene-styrene-vinylpyridine has been crosslinked by addition of iron chloride. Differential enthalpic analysis gives evidence of a two-phase system. Electron microscope studies at 0.1 and 1 MeV show the existence of precipitates. The majority of these ironrich aggregates have diameters less than 100 Å. Their form is polyhedral but very nearly spherical. No crystallinity has been detected inside the clusters. Thus the existence of strong interactions as in crystals of FeCl3 hydrates is excluded.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 569-581 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A butadiene, styrene, 4-vinylpyridine terpolymer has been crosslinked by coordination of the pyridine groups with iron chloride. The distribution and structure of the iron complexes have been studied. Electron microscopy has given evidence of clustering of the iron complexes. The size distribution of these clusters has been evaluated by small-angle x-ray and neutron scattering. Mössbauer spectroscopy and magnetization measurements have shown the presence of three different kinds of iron complexes: (a) complexes with a speromagnetic structure in the clusters previously found, (b) dimers with antiferromagnetic coupling, and (c) quasi-isolated complexes with weak ferromagnetic coupling. The percentages of these different iron complexes have been measured.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 2005-2014 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High-resolution electron microscopy studies have been carried out on four glassy polymers examined in previous small-angle x-ray scattering (SAXS) investigations. The polymers include polycarbonate, poly(ethylene terephthalate), poly(vinyl chloride), and polystyrene. For all four polymers, both bright field and dark-field observations indicate the general absence of microstructural features of a size down to the resolution limit of the electron microscope. Only “pepper and salt” features on a scale ca. 5 Å are seen as characteristic of the structures. These features reflect simple interferences as the resolution limit is approached, and are seen for single crystal and oxide glasses as well as for the polymers. The present results, taken together with structural information from light scattering, SAXS, and small-angle neutron scattering, indicate that glassy polymers should be regarded as having rendom structures. The combined results are inconsistent with heterogeneous microstructures having regions of locally high order present in large volume fractions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1057-1061 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 2225-2228 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The technique of quasielastic light scattering is utilized to determine the viscosity of fluids subjected to large hydrostatic pressures. In this method, a small concentration of insoluble polystyrene spheres of known diameter, 0.109 μm, is added to the fluid. The high-pressure cell in which the fluid is contained has three optical windows. The laser light scattered from the suspended spheres is analyzed to determine the diffusion coefficient of the spheres. Since, by the Stokes law, the viscosity of the fluid is determined from the measured diffusion coefficient and known particle radius r. A small correction is required for the contraction of the spheres and for refractive-index change of the water under pressure. Results on the viscosity of water at 25°C up to pressures of 2.5 kbar are reported and compared with published results. This method is applicable to lubricants and polymer solutions where the viscosity is many orders of magnitude greater than that of water.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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