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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4942-4950 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have extended the fully variational molecular orbital (FVMO) method to the full-configuration interaction (CI) wave function (full-CI FVMO). All variational parameters in the full-CI scheme, i.e., exponents and centers in Gaussian-type function (GTF) basis set, and nuclear positions, as well as the CI coefficients, are simultaneously optimized by using their analytical gradients. We have applied the full-CI FVMO method to the ground and electronic excited states of hydrogen molecule. In the ground state, the total energy (−1.174 015 hartree) and the internuclear distance (1.4016 bohr) obtained by the full-CI FVMO calculation with [8s4p2d] GTFs agree very well with the high-level calculation by the 249 term expansion in elliptic coordinates (−1.174 476 hartree and 1.4010 bohr, respectively). The excitation energies to the 1Σu+, 1Πu, 3Σg+, and 3Πu Rydberg states calculated by the full-CI FVMO method with [8s4p2d] GTFs coincide with the experimental values within 52 cm−1. The present result can not be obtained with the conventional basis set approach because of the fact that our full-CI FVMO calculation gives an extremely accurate wave function with a relatively small number of basis functions owing to the extension of flexibility in the variational space. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 3062-3072 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Nonadditivity contribution to the three-body interaction energy is studied in terms of the symmetry-adapted perturbation theory for many-electron systems. Each component of energy, particularly the second-order exchange dispersion and exchange induction contributions, is given by a combination of electrostatic interaction energies in Longuet–Higgins representation of the intermolecular charge distribution. The formulas of these energies are derived with the Hartree–Fock approximation and by taking triple-electronic exchanges among three monomers into account. Numerical calculation has been performed for the cyclic planar H2O and HF trimers, considering only single-electronic exchanges between molecules. The three-body effect of the second-order exchange energy has been found to be repulsive, while the main part of attractive contribution is due to the induction. The ratio of three-body energy to two-body one for the dispersion is much smaller than that for the induction, though the latter decreases more rapidly than the former as the angle between monomers increases. As a result, the three-body contribution lowers the total interaction energy slightly near the van der Waals minimum in both trimers. The contribution of two-body energies is also shown.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 1995-2009 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular interaction energy is studied in terms of the double symmetry-adapted perturbation theory, taking account of both the electronic exchange between molecules and the intracorrelation fluctuation for individual monomers. The energy is divided into physically meaningful components, such as electrostatic, first-order exchange, second-order polarization, and second-order exchange terms. The algebraic expressions of second-order component energy terms, especially second-order exchange ones, are derived for the interaction of two-electron systems by considering only single-electronic exchanges between molecules. Our result for the He dimer is compared with that produced when the explicitly correlated Gaussian-type geminal is employed. The ratio of intracorrelation energy to Hartree–Fock energy in the second-order exchange is larger than those in the second-order polarization as well as in the first-order energies. The interaction energies of the H2 dimer including intracorrelation effect are computed in four orientations, i.e., linear, parallel, T, and X types.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 5925-5928 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio calculations are made to examine theoretically the possibility of stable existence of [OH−;e+] system. Diffuse functions are added to the conventional 6-31G basis set, considering the wide spread of positron orbital. Moreover, the Møller–Plesset perturbation of the second order is calculated to take the electron correlation into account. These two improvements are found to be very effective for the stable existence of the system. The positron affinity of OH− is computed to be 4.9 eV, and the binding energy of positronium to OH as 0.7 eV which is in good agreement with experimental estimate.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of this study was to elucidate the mechanisms of blood-to-retina creatine transport across the blood–retinal barrier (BRB) in vivo and in vitro, and to identify the responsible transporter(s). The creatine transport across the BRB in vivo and creatine uptake in an in vitro model of the inner BRB (TR-iBRB2 cells) were examined using [14C]creatine. Identification and localization of the creatine transporter (CRT) were carried out by RT-PCR, western blot, and immunoperoxidase electron microscopic analyses. An in vivo intravenous administration study suggested that [14C]creatine is transported from the blood to the retina against the creatine concentration gradient that exists between the retina and blood. [14C]Creatine uptake by TR-iBRB2 cells was saturable, Na+- and Cl–-dependent and inhibited by CRT inhibitors, suggesting that CRT is involved in creatine transport at the inner BRB. RT-PCR and western blot analyses demonstrated that CRT is expressed in rat retina and TR-iBRB2 cells. Moreover, using an immunoperoxidase electron microscopic analysis, CRT immunoreactivity was found at both the luminal and abluminal membranes of the rat retinal capillary endothelial cells. In conclusion, CRT is expressed at the inner BRB and plays a role in blood-to-retina creatine transport across the inner BRB.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: ATP-binding cassette (ABC) transporter A4 is a member of the ABC transporter subfamily A which has been reported to be exclusively expressed in the retina. In contrast, a previous report has suggested a possible relationship between ABCA4 and CNS function. The purpose of the present study was to investigate the localization of ABCA4 mRNA and protein in rat brain. In situ hybridization analysis revealed that ABCA4 mRNA was localized in the lateral ventricles. RT–PCR analysis detected ABCA4 mRNA in isolated rat choroid plexus and conditionally immortalized rat choroid plexus epithelial cells (TR-CSFB). Furthermore, ABCA4 protein was also detected in the isolated rat choroid plexus at about 250 kDa by western blot analysis, and its apparent molecular size was reduced by N-glycosidase F treatment. These results suggest that glycosylated ABCA4 protein is expressed in rat choroid plexus epithelial cells. ABCA4 may play a role in the function of the blood–cerebrospinal fluid barrier and affect CSF conditions.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In this study, the internalization mechanism of basic fibroblast growth factor (bFGF) at the blood–brain barrier (BBB) was investigated using a conditionally immortalized mouse brain capillary endothelial cell line (TM-BBB4 cells) as an in vitro model of the BBB and the corresponding receptor was identified using immunohistochemical analysis. The heparin-resistant binding of [125I]bFGF to TM-BBB4 cells was found to be time-, temperature-, osmolarity- and concentration-dependent. Kinetic analysis of the cell-surface binding of [125I]bFGF to TM-BBB4 cells revealed saturable binding with a half-saturation constant of 76 ± 24 nm and a maximal binding capacity of 183 ± 17 pmol/mg protein. The heparin-resistant binding of [125I]bFGF to TM-BBB4 was significantly inhibited by a cationic polypeptide poly-L-lysine (300 µm), and compounds which contain a sulfate moiety, e.g. heparin and chondroitin sulfate-B (each 10 µg/mL). Moreover, the heparin-resistant binding of [125I]bFGF in TM-BBB4 cells was significantly reduced by 50% following treatment with sodium chlorate, suggesting the loss of perlecan (a core protein of heparan sulfate proteoglycan, HSPG) from the extracellular matrix of the cells. This type of binding is consistent with the involvement HSPG-mediated endocytosis. RT-PCR analysis revealed that HSPG mRNA and FGFR1 and FGFR2 (tyrosine-kinase receptors for bFGF) mRNA are expressed in TM-BBB4 cells. Moreover, immunohistochemical analysis demonstrated that perlecan is expressed on the abluminal membrane of the mouse brain capillary. These results suggest that bFGF is internalized via HSPG, which is expressed on the abluminal membrane of the BBB. HSPG at the BBB may play a role in maintaining the BBB function due to acceptance of the bFGF secreted from astrocytes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of the present study was to clarify the expression, transport properties and regulation of ATP-binding cassette G2 (ABCG2) transporter at the rat blood–brain barrier (BBB). The rat homologue of ABCG2 (rABCG2) was cloned from rat brain capillary fraction. In rABCG2-transfected HEK293 cells, rABCG2 was detected as a glycoprotein complex bridged by disulfide bonds, possibly a homodimer. The protein transported mitoxantrone and BODIPY-prazosin. In rat brain capillary fraction, rABCG2 protein was also detected as a glycosylated and disulfide-linked complex. Immunohistochemical analysis revealed that rABCG2 was localized mainly on the luminal side of rat brain capillaries, suggesting that rABCG2 is involved in brain-to-blood efflux transport. For the regulation study, conditionally immortalized rat brain capillary endothelial (TR-BBB13), astrocyte (TR-AST4) and pericyte (TR-PCT1) cell lines were used as an in vitro BBB model. Following treatment of TR-BBB13 cells with conditioned medium of TR-AST4 cells, the Ko143 (an ABCG2-specific inhibitor)-sensitive transport activity and rABCG2 mRNA level were significantly increased, whereas conditioned medium of TR-PCT1 cells had no effect. These results suggest that rat brain capillaries express functional rABCG2 protein and that the transport activity of the protein is up-regulated by astrocyte-derived soluble factor(s) concomitantly with the induction of rABCG2 mRNA.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Using in situ hybridization for the mouse brain, we analyzed developmental changes in gene expression for the ATP-binding cassette (ABC) transporter subfamilies ABCA1–4 and 7, and ABCG1, 2, 4, 5 and 8. In the embryonic brains, ABCA1 and A7 were highly expressed in the ventricular (or germinal) zone, whereas ABCA2, A3 and G4 were enriched in the mantle (or differentiating) zone. At the postnatal stages, ABCA1 was detected in both the gray and white matter and in the choroid plexus. On the other hand, ABCA2, A3 and A7 were distributed in the gray matter. In addition, marked up-regulation of ABCA2 occurred in the white matter at 14 days-of-age when various myelin protein genes are known to be up-regulated. In marked contrast, ABCA4 was selective to the choroid plexus throughout development. ABCG1 was expressed in both the gray and white matters, whereas ABCG4 was confined to the gray matter. ABCG2 was diffusely and weakly detected throughout the brain at all stages examined. Immunohistochemistry of ABCG2 showed its preferential expression on the luminal membrane of brain capillaries. Expression signals for ABCG5 and G8 were barely detected at any stages. The distinct spatio-temporal expressions of individual ABCA and G transporters may reflect their distinct cellular expressions in the developing and adult brains, presumably, to regulate and maintain lipid homeostasis in the brain.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The creatine/phosphocreatine shuttle system, as catalysed reversibly by creatine kinases, is thought to be essential for the storing and buffering of high phosphate-bound energy in tissues with high energy demand. In the present study, we aimed to clarify the cellular system of creatine biosynthesis and its energy metabolism in the mouse brain by immunohistochemistry for creatine biosynthetic enzyme S-adenosylmethionine:guanidinoacetate N-methyltransferase (GAMT), ubiquitous mitochondrial creatine kinase (uCK-Mi) and brain-type cytoplasmic creatine kinase (CK-B). GAMT was expressed highly in oligodendrocytes and olfactory ensheathing glia and moderately in astrocytes, whereas GAMT was very low in neurons and microglia. By contrast, uCK-Mi was expressed selectively in neurons and localized in their mitochondria in dendrites, cell bodies, axons and terminals. The distinct and almost complementary distribution of GAMT and uCK-Mi suggests that the creatine in neuronal mitochondria is derived not only from the circulation, but also from local glial cells associated with these neuronal elements. By contrast, CK-B was selective to astrocytes among glial populations, and was exclusive to inhibitory neurons among neuronal populations. Interestingly, these cells with high CK-B immunoreactivity are known to be highly resistant to acute energy loss, such as hypoxia and hypoglycemia. Considering that phosphocreatine generates ATP much faster than the processes of glycolysis and oxidative phosphorylation, the highly regulated cellular expressions of creatine biosynthetic and metabolic enzymes suggest that the creatine/phosphocreatine shuttle system plays a role in brain energy homeostasis through a novel neuron–glial relationship.
    Type of Medium: Electronic Resource
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