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  • 1990-1994  (3)
  • Atomic, Molecular and Optical Physics  (2)
  • contractileproteins  (1)
  • Blank bias error
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 86 (1991), S. 219-226 
    ISSN: 1435-1803
    Keywords: “stunned”myocardium ; ischemia ; contractileproteins ; myofibrillarATPase ; phosphorylation ofcontractileproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The isolated working rabbit heart preparation was used to study whether the “contractile machinery” remains unchanged in globally stunned myocardium. The function of the heart has been measured in nonischemic and postischemic conditions. The effect of isoprenaline or calcium chloride administration in both conditions was also studied. Myocardial contractile function was significantly depressed after 20-min global ischemia and returned to normal after CaCl2 and supranormal values after isoprenaline administration. From hearts used in experiments myofibrils were prepared and their ATPase activity was determined. It was observed that myofibrils prepared from “stunned” myocardium showed about 50 % increase in ATPase activity in the presence of CaCl2. Subjection of the heart to ischemia caused a decrease in calcium sensitivity of the myofibrillar ATPase. Myofibrils obtained from ischemic hearts but subjected to isoprenaline or CaCl2 administration exhibited increased calcium sensitivity over that of control heart. These effects were accompanied by changes in the extent of phosphorylation of troponin I (TNI) and myosin light chains. The modification of contractile apparatus in the postischemic period described in this paper may contribute to the overall mechanism of myocardial stunning.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 48 (1993), S. 175-186 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An ab initio perturbed ion study using X-ray diffraction data has been carried out for ZrSiO4 (zircon), ZrO2 (monoclinic zirconia, baddeleyite), and SiO2 (α-cristobalite) crystal lattice structures. The different substitutions of V4+ for Zr4+ and Si4+ occurring in these host lattices have been analyzed. Geometry optimizations have been performed with the aim of determining the relative stability, cell parameters, and force constants of radial displacement associated with the local relaxation for pure and doped structures. Numerical results are confronted against experimental data and compared with previous results. The geometrical cell parameters of different structures obtained by computer simulation and the results of the X-ray diffraction studies agree with previous experimental data. For the zircon lattice, the substitution of V4+ for Zr4+ at an eightfold-coordinated site is energetically favorable while the substitution of V4+ for Si4+ at a fourfold-coordinated site is unstable. For ZrO2, the substitution of V4+ for Zr4+ is energetically favorable while the substitution of V4+ for Si4+ in SiO2 is energetically unfavorable. There is less sensitive influence of the crystal lattice parameters for substitutions occurring at the eightfold-coordinated ion site in ZrSiO4 and SiO2 structures. The doping process produces a decrease of force constant (k) values associated with the breathing fundamental vibrational mode for all structures. The k associated with the radial displacement in dodecahedral substitution in the ZrSiO4 structure is especially high. The force constants for this movement in tetrahedral substitution in the ZrSiO4, ZrO2, and SiO2 structures have a lower value. The differences between ionic radii reported by Shannon and Prewitt of the species concerned in the doping process are not capable of explaining the relaxation of crystal lattice parameters in the ZrO2 and SiO2 structures. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 48 (1993), S. 643-653 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: AM1 and MNDO semiempirical electronic calculations have been carried out for ZnO surface ((ZnO)n, n = 11, 16, 22, 24, 33, 42, and 44) cluster models. The theoretical results can be summarized as follows: (i) the energy gap HOMO-LUMO is shown to be dependent on the cluster size and geometry optimization; however, better agreement of this gap with experimental data is obtained with cluster of limited size (n = 16, 22, and 24). (ii) The Mulliken charge of the cluster zinc ion is invariant with the optimization procedure, showing an average value of 0.52 a.u. (MNDO) and 0.62 a.u. (AM1). © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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