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  • Computational Chemistry and Molecular Modeling  (5)
  • thyroxine  (3)
  • 36.40.+d  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 49 (1993), S. 329-331 
    ISSN: 1420-9071
    Keywords: Pineal ; thyroxine ; deiodinase ; phenylephrine ; isoproterenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the present study we show, for the first time, that phenylephrine (PHE), an α-adrenergic receptor agonist, potentiates the effect of isoproterenol (ISO), a β-adrenergic agonist, in activating pineal type II5′-deiodinase (5′-D) activity. The potentiating effect of PHE was observed only at doses of ISO which induce submaximal activation of the enzyme. However, at doses which lead to maximal activation of the enzyme, PHE was ineffective. The results suggest that not only β-, but also α-adrenergic receptors, are involved in the sympathetic noradrenergic regulation of pineal 5′-D activity in the adult rat.
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  • 2
    ISSN: 1573-4935
    Keywords: deiodinase ; thyroxine ; Swiss mouse ; pineal ; Harderian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Type II thyroxine 5′-deiodinase (5′-D) activity in both pineal and Harderian glands of the Swiss mouse was studied. Pineal 5′-D activity exhibited a nyctohemeral profile with a maximal peak value at 05.00 h, which coincides with that for pineal melatonin production. However, no rhythm of 5′-D activity in the Harderian gland could be found. In pineal gland, light at night inhibited the nocturnal increase in 5′-D activity, while isoproterenol, a β-adrenergic agonist, could not stimulate the enzyme. In the Harderian gland, neither darkness, nor light at night, or isoproterenol were capable of modifying basal values of 5′-D activity.
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  • 3
    ISSN: 1573-4935
    Keywords: ethanol ; deiodinase ; N-acetyltransferase ; thyroxine ; pineal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Chronic ethanol intake resulted in a significant decrease in the rate of rat ponderal growth and an impaired nyctohemeral profile of pineal N-acetyltransferase (NAT) activity. In ethanol-treated animals, the onset of the nocturnal NAT increase is delayed by 2 hours when compared to control animals. Moreover, pineal NAT nocturnal peak was reached at 4 h (2 hours later than controls), while pineal type II thyroxine 5′-deiodinase (5′-D) nyctohemeral profile was not modified by ethanol administration. The effect of ethanol administration (12 weeks) on 5′-D activity in different tissues was also studied. Ethanol induced a 5′-D activity increase in hypothesis and brain frontal cortex, when compared to control animals. No change in 5′-D activity is observed in either pineal gland, Harderian gland, or brown adipose tissue. Since basal values of 5′-D activity in hypophysis or brain frontal cortex are particularly dependent on serum thyroxine (T4) concentration, the effect of chronic ethanol administration on thyroid hormone levels was studied. Serum T4 levels in ethanol-treated animals were significantly decreased when compared to controls at any time point studied. However, no change in serum 3′,3,5-triiodothyronine (T3) levels were found.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 26 (1993), S. 284-286 
    ISSN: 1434-6079
    Keywords: 73.20.Mf ; 36.40.+d ; 31.20.Sy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the origin of the discrepancy between the photoabsorption cross sections of small jellium spheres calculated by the time dependent local density approximation (TDLDA) and experiments for small metallic clusters. We have specifically studied Na 21 + . We conclude that both non-local exchange-correlation effects beyond the LDA and geometrical effects beyond the jellium approximation should be taken in the same calculation. We also present local and non-local calculations for Na n − (n=19, 91 and 197) within the framework of the jellium model. The large anions show a fragmentation of the plasmon due to its interference with the ionization threshold. This feature is absent in the TDLDA results.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 45 (1993), S. 333-347 
    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: The nonlocal weighted density approximation (WDA) to the exchange and kinetic energy functionals of many-electron systems proposed several years ago by Alonso and Girifalco in the context of density functional theory is used to compute, within the framework of the spherical jellium model, the ground-state electronic density, chemical potential, and total energy of neutral and negatively and positively charged sodium clusters containing up to N = 800 atoms. From these calculations, we study the behavior of the total energies per atom, chemical potentials, ionization potentials, I(N), and electron affinities, A(N). These results are compared with analogous calculations using the well-known Thomas-Fermi-Weizsäcker-Dirac (TFWD) approximation for the kinetic (TFW) and exchange (D) energy functionals. Calculations including the local density approximation (LDA) to the correlation energy in both WDA and TFWD functionals are also presented. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 56 (1995), S. 499-508 
    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: The local density approximation (LDA) to exchange and correlation effects has well-known limitations. The nonlocal weighted density approximation (WDA) corrects some of those defects. This is illustrated here by applications to free atoms and small atomic clusters. The WDA also induces a nonlocal kinetic energy functional that is tested for atoms. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 44 (1992), S. 347-358 
    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: The nonlocal weighted density approximation (WDA) to the exchange and kinetic-energy functionals of many electron systems proposed several years ago by Alonso and Girifalco is used to compute, within the framework of density functional theory, the ground-state electronic density and total energy of noble gas atoms and of neutral jellium-like sodium clusters containing up to 500 atoms. These results are compared with analogous calculations using the well known Thomas-Fermi-Weizsäcker-Dirac (TFWD) approximations for the kinetic (TFW) and exchange (D) energy density functionals. An outstanding improvement of the total and exchange energies, of the density at the nucleus and of the 〈r-1〉 expectation values is obtained for atoms within the WDA scheme. For sodium clusters we notice a sizeable contribution of the nonlocal effects to the total energy and to the density profiles. In the limit of very large clusters these effects should affect the surface energy of the bulk metal. © 1992 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 993-1010 
    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: We calculate the first ionization potential of atoms (3 ≤ Z ≤ 54) by means of a nonlocal density functional approach and the results are compared with those obtained using other recent density functional approaches based on density gradients. In these calculations, we use a nonlocal weighted spin-density approximation of exchange effects and a local spin-density approximation of Coulomb correlation, both based on novel forms of the pair-correlation functions. We also calculate the total energies of the He, Be, and Ne isoelectronic series. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 171-184 
    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: The search for a density functional theory (DFT) free of one-electron orbitals needs the development of good kinetic energy functionals beyond the venerable Thomas-Fermi and gradient expansion functionals. With this goal in mind, we previously solved for several atoms and positive ions the Euler equation associated with the exchange and kinetic energy functionals of the nonlocal weighted density approximation (WDA). In this work, we improve the theory by enforcing the correct asymptotic behavior of the exchange potential following a prescription of Przybilsky and Borstel (PB). We have calculated electronic densities, density moments 〈rn〉 (n = -1,1,2) and the density at the nucleus ρ(0), as well as total and exchange energies and chemical potentials for neutral and charged atoms. All those quantities show a better agreement with Hartree-Fock results than those obtained using gradient-corrected Thomas-Fermi functionals. The radial densities, 4πr2(r), show two local maxima at positions close to those of the first two maxima of Hartree-Fock radial densities. This effect, which is absent in the self-consistent densities from the usual gradient-corrected Thomas-Fermi functions, can be interpreted, in our view as an incipient emergence of the shell effect. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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