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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 353 (1995), S. 1-10 
    ISSN: 1432-1912
    Keywords: Key words Cyclic nucleotide-gated channels ; Second messenger ; Cyclic GMP ; Calcium ; Nitric oxide ; Molecular cloning ; Gene family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cyclic nucleotide-gated cation channels (CNG channels) form a multi-gene family consisting of at least five distinct members (CNG1–5). Expression studies have indicated that only CNG1–3 are able to form functional homooligomeric channels. Although structurally related, the cDNAs of CNG4–5 fail to induce cyclic nucleotide-dependent currents when expressed alone. However, when co-expressed with CNG1–3 they confer some of the physiologically observed properties of native CNG channels which are absent from the homooligomeric CNG1–3 channels. CNG channels are expressed in several tissues and cell types pointing to a general function of these channels in a wide variety of cellular systems. There is now increasing evidence that a major function of CNG channels may consist in providing a second messenger-regulated pathway for Ca2+ influx.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: dihydropyridine receptor ; L-type calcium channel ; voltage sensor ; subunits ; patch clamp ; site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A histidine substitution for the outermost arginine in II/S4 of the α1 subunit of the human skeletal muscle dihydropyridine (DHP) receptor has been reported to cause hypokalaemic periodic paralysis (HypoPP). This mutation shifts the voltage dependence of L-type Ca current inactivation in myotubes from HypoPP patients by −40 mV without affecting activation. Based on the strong homology of II/S4 in cardiac and skeletal muscle α1, we introduced the corresponding mutation into the rabbit cardiac α1 subunit (R650H). Wild type (WT) and mutant constructs were transiently transfected in HEK cells together with β and α2δ subunits and Ca and Ba currents were studied using the whole-cell patch-clamp technique. In contrast to the results obtained from human myotubes, R650H produced a small (−5 mV) but significant shift of both the steady-state activation and inactivation curves. When external pH was increased from 7.4 to 8.4 in order to favour deprotonization of H650, the only difference between WT and mutant channels was a slightly reduced steepness of the inactivation curve. Additional cotransfection of the γ subunit which is only found in skeletal but not in heart muscle, shifted the inactivation curves of both WT and R650H by −20 mV. We conclude that R650 plays a different role in voltage-dependent gating of the cardiac L-type Ca channel than the corresponding residue in the human skeletal muscle L-type channel, since a distinct and selective effect on the midpoint voltage of steady-state inactivation could not be found for R650H.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 281-291 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Investigation of Laser Beam Joining Properties for Eye Glass Frame ManufactureIn the production of high-grade eye glass frames of stainless steel increase the application of laserbeam joining technology in comparison to conventional processes. In a study it should be established, with which process (brazing or welding), the practical requirements of eye glass frames could be realized. Profiles made of Cr-Ni-steel which are used in practice due to their corrosion resistance, were joined with laser beam. To characterize the properties of joints, the quality of specimens were tested concerning mechanical properties (hardness, strength, ductility) and structural constitution. In relation to the requirement of good ductility of the joints, it was possible to proof the advantages of the welded samples.
    Notes: Bei der Fertigung von hochwertigen Brillengestellen aus nichtrostenden Stählen gewinnt der Einsatz der Laserstrahlfügeverfahren im Vergleich zu konventionellen Verfahren zunehmend an Bedeutung. Im Rahmen einer Studie sollte festgestellt werden, welches der beiden Verfahren Löten und Schweißen die in der Praxis gestellten Anforderungen an Brillengestelle besser erfüllt. Hierzu wurden Profile aus Cr-Ni-Stahl, wie sie in der Praxis wegen ihrer besonderen Langzeitstabilität gegenüber Korrosion eingesetzt werden, mittels Laserstrahl gefügt. Zur Charakterisierung der metallurgischen Eigenschaften der Fügeverbindungen wurden die Qualitätsmerkmale der Proben hinsichtlich mechanischer Eigenschaften (Härte, Festigkeit und Verformbarkeit) sowie die Gefügeausbildung untersucht. Im Hinblick auf die geforderte gute Verformbarkeit der Verbindungen konnte für die geschweißten Proben ein Vorteil gegenüber dem Laserstrahllöten nachgewiesen werden.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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