Ellagic Acid Suppresses ApoB Secretion and Enhances ApoA-1 Secretion from Human Hepatoma Cells,HepG2

The effect of ellagic acid (EA), a naturally occurring polyphenolic compound, on the secretion of apolipoproteins from human hepatocytes, HepG2, was investigated. The levels of apoB and apoA-1 secreted in the cell culture medium were determined by sandwich ELISA. EA did not affect cell viability at the tested concentrations (up to 50 µM). EA suppressed the secretion of apoB and enhanced that of apoA-1 from HepG2 cells. However, cellular apoB levels were increased, suggesting that EA inhibited the trafficking of apoB during the process of secretion. In contrast, the increase in the cellular levels of apoA-1 was consistent with its secreted levels. These results indicate that EA inhibits the secretion of apoB from hepatocytes and increases the secretion of apoA-1. Both of these effects are beneficial for lipoprotein metabolism in the prevention of lifestyle-related diseases. The detailed mechanism underlying these effects of EA on lipoprotein metabolism should be elucidated in the future, but this naturally occurring polyphenolic compound might be antihyperlipidemic. Based on these results, EA is suggested as a candidate food-derived compound for the prevention of hyperlipidemia.     

Kinetics of phase transformation from hBN to cBN in the presence of Mg3BN3 catalyst

Abstract

Transformation kinetics from hBN to cBN has been studied at 6 GPa with changing reaction temperature and content of catalyst mixed with hBN powder. At lower catalyst content (3–10 wt %), rate of transformation was extraordinary rapid between 1300 and 1350 C. At higher catalyst content (30–50 wt %), rate of transformation was decreased. Normal nucleation kinetics was observed at about 1500 C. The rapid transformation temperature region correlates characteristic behavior of the sintering process.     

Triplet state sublevel spectroscopy applied to proteins

Triplet state sublevel spectroscopy using optical detection of magnetic resonance (ODMR) in zero magnetic field can be successfully employed to study (i) the environment of tryptophan (Trp) residues in a protein by observing the position and structure of phosphorescence spectra, zero field ODMR transitions and triplet state sublevel kinetics, (ii) the energy transfer among Trp residues, and (iii) whether any cysteine (Cys) residue is within van der Waals distance of any Trp residue by studying the complex of the protein with methylmercury(II) iodide (CH₃HgI) which binds to Cys residues. These studies are particularly important where crystal structure study is not possible. Study of the S₁ state often gives ambiguous results since fluorescence is always broad and shows multi-exponential decay. Our results on bacteriophage lysozyme T4 which contains three Trp residues at positions 126, 138 and 158 are presented. Measurements were facilitated by the use of a mutated enzyme containing one or two Trp-Tyr substitutions. The results indicate that (i) Trp 126 and 158 are solvent exposed, whereas Trp 138 is buried in a hydrophobic environment, (ii)S ↔S non-radiative energy transfer takes place predominantly from Trp 126 to Trp 158, and (iii) only Trp-158 undergoes a heavy atom perturbation, which affects selectively the z-sublevel (z is an out-of-plane axis of the indole plane) as a result of CH₃HgI binding to nearby Cys 97. We suggest that the Hg atom is located on the z-axis of Trp 158 in the complex. This interpretation is based on our investigations on the effect of orientation of heavy atom perturbers in some naphthalene-crown ether metal ion complexes.     

Anisotropic spin—lattice relaxation in the triplet state of naphtralene-h8 in n-pentane

The temperature dependence of the individual spin—lattice relaxation rate constants (W_ij) between the lowest triplet sublevels of naphthalene-h₈ in a polycrystalline Shpol'skii matrix of n-pentane have been measured between 1.2 and 2.4 K in zero field. The total sublevel decay constants are evaluated and found to be independent of temperature. The W_ij are found to be highly anisotropic, but the anisotropy pattern differs from that observed previously in a durene matrix.     

Surface electronic structure of binary metal oxide catalyst ZrO2/SiO2

The surface electronic structure of the binary metal oxide ZrO₂/SiO₂ was studied by means of XPS and the decrete variational (DV) Xα cluster model calculation. The results show that when ZrO₂, was supported on SiO₂, the SiO bond of SiO₂, neighboring ZrO₄, became stronger and that the Brönsted acid site H which is located on the SiO₄ unit exhibits stronger acidity.     

Production of direct single electrons in proton-nucleus collisions at 13 GeV/c

Direct production of single electrons in proton-nucleus collisions at 13 GeV/c has been measured. A rising $\text{e}\text{π}$ ratio with decreasing p_T above the 10^?4 level is observed for low p_T single electrons. The source of the rising $\text{e}\text{π}$ ratio at low $\text{e}\text{π}$ ratio at low p_T is discussed in connection with the low mass dielectron continuum below the ? mass region.     

Giant Nernst effect in the pseudogap phase of high Tc superconductors

We have investigated theoretically the Nernst effect in unconventional (d-wave) charge and spin density waves (UDW). In the presence of magnetic field, Landau levels are formed, and the gapless behaviour of the low energy excitations change into gapped behaviour. When additional electric field is applied, the quasiparticles drift with a velocity of E × B/B², and carry entropy. From this, the Nernst coefficient can be calculated using the Kelvin relation. The present results account very nicely for the measured Nernst signal in the pseudogap phase of high T_c superconductor La_2−xSr_xCuO₄ and Bi₂Sr_2−yLa_yCuO₆. This indicates that the large Nernst effect is a clear signiture of UDW.