Phosphorylation of phospholipase D1 and the modulation of its interaction with RhoA by cAMP-dependent protein kinase

Agents that elevate cellular cAMP are known to inhibit the activation of phospholipase D (PLD). We investigated whether PLD can be phosphorylated by cAMP-dependent protein kinase (PKA) and PKA-mediated phosphorylation affects the interaction between PLD and RhoA, a membrane regulator of PLD. PLD1, but not PLD2 was found to be phosphorylated in vivo by the treatment of dibutyryl cAMP (dbcAMP) and in vitro by PKA. PKA inhibitor (KT5720) abolished the dbcAMP-induced phosphorylation of PLD1, but dibutyryl cGMP (dbcGMP) failed to phosphorylate PLD1. The association between PLD1 and Val14RhoA in an immunoprecipitation assay was abolished by both dbcAMP and dbcGMP. Moreover, RhoA but not PLD1 was dissociated from the membrane to the cytosolic fraction in dbcAMP-treated cells. These results suggest that both PLD1 and RhoA are phosphorylated by PKA and the interaction between PLD1 and RhoA is inhibited by the phosphorylation of RhoA rather than by the phosphorylation of PLD1.     

Electrochemical and Electrochromic Properties of Ni Oxide Thin Films Prepared by a Sol–Gel Method

Nickel oxide thin films, which are well known anodic coloration materials that are used in electrochromic devices, were prepared by a sol–gel method, and their electrochemical and electrochromic properties were investigated. The sol was prepared from Ni(OH)₂ powder with an average size of 7 nm, in a mixture of ethylene glycol and absolute ethanol. The films were coated on an ITO substrate using the powder, dispersed in the solution. When additive materials, acetyl acetone and glycerol, were added to the sol its hardness and adhesion properties were improved. The optimized thin film formed an amorphous, porous structure, and showed a large current density during continuous potential and pulse potential cycling. The film also was transparent and had a high coloration efficiency (33.5 cm²/C) and a rapid response time (1.0–2.5 s) during the coloring/bleaching process.     

Growth promotion of HepG2 hepatoma cells by antisense-mediated knockdown of glypican-3 is independent of insulin-like growth factor 2 signaling

Glypican-3 (GPC3) encodes a cell-surface heparan- sulfate proteoglycan and its expression is frequently silenced in ovarian cancer, mesotheliomas, and breast cancer cell lines and ectopic expression of GPC3 inhibited the growth of these cells, suggesting that GPC3 plays a negative role in cell proliferation. In contrast, up-regulation of GPC3 is often observed in hepatoma, neuroblastoma, and Wilms' tumor. Whether GPC3 plays the same growth inhibitory role in these tumors remains to be studied. Here we report that antisense-mediated knockdown of GPC3 in the HepG2 hepatoma cells significantly promotes the growth of hepatoma cells. In addition, we show that this growth promotion is independent of insulin-like growth factor 2 (IGF2) signaling. Our data suggest that GPC3 plays a growth-suppressing role in hepatoma and provide cell biological evidence inconsistent with the hypothesis that GPC3 acts as a growth suppressor by downregulating IGF2.     

Infrared-visible and visible-visible double resonance spectroscopy of 1-hydroxy-9,10-anthraquinone-(H2O)n (n=1,2) complexes

The structures of hydrated 1-hydroxyanthraquinone complexes (1-HAQ), 1-HAQ(H2O)n=1,2, with intramolecular and intermolecular hydrogen bonding interactions were studied using laser spectroscopic methods such as laser induced fluorescence, fluorescence-detected infrared, infrared-visible hole burning, and visible-visible hole burning spectroscopy. In the 1:1 complex 1-HAQ(H2O)1, the water binds to the free carbonyl group of 1-HAQ not associated with intramolecular hydrogen bond. The second water in the 1:2 complex, 1-HAQ(H2O)2, binds to the first water of the 1:1 complex rather than other hydrogen bonding sites of 1-HAQ. A pair of two geometric isomers was produced in a supersonic jet for each of the 1:1 and 1:2 complexes. Both isomers of each complex have the same vibrational spectra in the region of the OH stretching vibration of water, but have different energies for the 0-0 band of vibronic transition due to the asymmetry of the two phenyl rings in 1-HAQ. The 0-0 bands for all four species of 1-HAQ(H2O)n=1,2 were unambiguously assigned by comparing with the results of ab initio calculations, which yielded the structures, vibrational frequencies, and relative energies of the frontier molecular orbitals.     

The kinetics of cation exchange reaction of europium propylenediaminetetraacetate with ytterbium ion

The kinetics of cation exchange reaction of Eu(III) propylenediaminetetraacetate with Yb(III) has been studied in an aqueous solution by the polarographic procedure. The measurements were made at 25°C and at an ionic strength of 0.5 M KCl. The dissociation of the europium complex has been found to be catalyzed by hydrogen ions. The influences of the inductive effect and the steric hindrance of a C-methyl group on the ethylene of PDTA are discussed by comparing it to analogous EDTA and CyDTA system.     

The molecular structure of norbornene as determined by electron diffraction and microwave spectroscopy

The molecular structure of norbornene has been investigated in the gas phase by combining electron diffraction data with microwave spectroscopic rotational constants. The interatomic distances (r_g) and bond angles were obtained by applying a least squares program to the refined experimental molecular diffraction intensities. The CC bond length was found to be 1.336 ± 0.002 Å while the

) bond length was 1. 529 ± 0.007 Å. Other bond lengths and angles included (IUPAC numbering system was used for norbornene): C₁-C₆ = 1.550 ± 0.020 Å, C₁-C₇ = 1.566± 0.005 Å, C₅-C₆ = 1.556 ± 0.005 Å, C-H_ave. = 1.103 ± 0.003 Å, ∠C₁C₂C₄ = 95.3°. The dihedral angle between planes C₁C₂C₃C₄ and C₁C₆C₅C₄ is 110.8 ± 1.5° while that between C₁C₂C₃C₄ and C₁C₇C₄ is 122.3°. The moments of inertia calculated from ED structure are in good agreement with microwave spectroscopic values.     

The Structure of the Antibiotic Hedamycin. I. Chemical,Physical and Spectral Properties

Interpretation of the chemical and spectral (IR., UV., ¹H- and ¹³C-NMR.) properties of the antitumor antibiotic hedamycin (C₄₁H₅₀N₂O₁₁) suggests that the molecule contains a methyl substituted 1-hydroxyanthraquinone nucleus, an α, β-unsaturated ketone, two sugar-like tetrahydropyran rings ( 4 and 8 ) and an aliphatic chain 2 , presumably with an epoxy group (see the Scheme).     

Identification of flavonoids using liquid chromatography with electrospray ionization and ion trap tandem mass spectrometry with an MS/MS library

Searchable MS/MS spectra libraries, constructed using the results of liquid chromatography coupled with electrospray ionization (ESI) tandem mass spectrometry (LC/MS/MS) with data-dependent acquisition on an ion trap mass spectrometer, are presented with regard to the identification and confirmation of a variety of closely related flavonoids in a set of biological samples. Flavonoids were found to exhibit a maximum amount of structurally specific MS/MS spectra at 45% of normalized collision energy on the instrument used, without wideband activation. These MS/MS spectra were then searched automatically against a 297-substance MS/MS library that contains many previously acquired spectra of standard flavonoids. The possible applications of this powerful technique to biological samples are also discussed. Daidzein and genistein were identified through the MS/MS spectra library while searching through LC/MS/MS data for plant and microbial extracts. Moreover, these compounds proved completely distinguishable from other flavonoids of closely related structures in the MS/MS spectra library, using the NIST MS search program. The applicability of the library-searchable spectra at low concentrations was demonstrated by successful identification of daidzein and genistein at 0.05 and 0.5 microg/mL, respectively.     

Efficient total synthesis of pulchellalactam,a CD45 protein tyrosine phosphatase inhibitor

A new approach to a CD45 protein tyrosine phosphatase inhibitor, pulchellalactam, is described. The key step of the sequence involves addition and elimination of an enolic lactam in a single step and 70% yield, employing an organocuprate reagent. The resulting alpha,beta-unsaturated lactam could be condensed with isobutyraldehyde to produce Z-pulchellalactam or converted into siloxypyrrole, which was subjected to the BF(3) x Et(2)O-promoted coupling reaction with isobutyraldehyde to afford E-pulchellalactam after E1-cB elimination and TFA deprotection. This first total synthesis afforded Z-pulchellalactam in six steps and 32% overall yield from Boc-glycine. The same sequence of reactions could also be applied to the liquid- or solid-phase synthesis of trifunctionalized pulchellalactam derivatives.     

Surface modification of γ-alumina membranes by silane coupling for CO2 separation

Top layers of γ-Al₂O₃ composite membranes have been modified by the silane coupling technique using phenyltriethoxysilane for improving the separation factor of CO₂ to N₂. The separation efficiency of the modified membranes was strongly dependent upon the hydroxylation tendency of the support materials and the amount of the special functional group (i.e. phenyl radical) which was coupled onto a top layer. The separation factor through the TiO₂ supported γ-Al₂O₃ membrane was found to be fairly enhanced by silane coupling, but in case of the -Al₂O₃ supported membrane was not. The CO₂/N₂ separation factor through the modified γ-Al₂O₃/TiO₂ composite membrane is 1.7 at 90°C and ΔP = 2 × 10⁵ Pa for the binary mixture containing 50 vol% CO₂. The separation factor is proportional to the CO₂ concentration in the gas mixture, and the modified membrane is stable up to 100°C. The main mechanism of the CO₂ transport through the modified γ-Al₂O₃ layer is known to be a surface diffusion.