Neuroprotective effect of peroxiredoxin 6 against hypoxia-induced retinal ganglion cell damage

Background  

The ability to respond to changes in the extra-intracellular environment is prerequisite for cell survival. Cellular responses to the environment include elevating defense systems, such as the antioxidant defense system. Hypoxia-evoked reactive oxygen species (ROS)-driven oxidative stress is an underlying mechanism of retinal ganglion cell (RGC) death that leads to blinding disorders. The protein peroxiredoxin 6 (PRDX6) plays a pleiotropic role in negatively regulating death signaling in response to stressors, and thereby stabilizes cellular homeostasis.     

Protection of cortical cells by equine estrogens against glutamate-induced excitotoxicity is mediated through a calcium independent mechanism

Background  

High concentrations of glutamate can accumulate in the brain and may be involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease. This form of neurotoxicity involves changes in the regulation of cellular calcium (Ca²⁺) and generation of free radicals such as peroxynitrite (ONOO^-). Estrogen may protect against glutamate-induced cell death by reducing the excitotoxic Ca²⁺ influx associated with glutamate excitotoxicity. In this study, the inhibition of N-methyl-D-aspartate (NMDA) receptor and nitric oxide synthase (NOS) along with the effect of 17β-estradiol (17β-E₂) and a more potent antioxidant Δ⁸, 17β-estradiol (Δ⁸, 17β-E₂) on cell viability and intracellular Ca²⁺ ([Ca²⁺]_i), following treatment of rat cortical cells with glutamate, was investigated.     

Giant core-exciton effects on Si(111) 7 × 7 surfaces

We present the first direct experimental evidence for a large surface influenced core-exciton effect on silicon. The Si(111) 7 × 7 L_2,3 absorption edge has been studied with core-level electron energy loss (ELS) and X-ray photoemission spectroscopy (XPS). An excitonic shift of ～1–2 eV have been found for transitions from Si(2p) to empty surface states.     

Both systemic and local application of Granulocyte-colony stimulating factor (G-CSF) is neuroprotective after retinal ganglion cell axotomy

Background  

The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules.     

Proton ENDOR study of copper(II) bis(dithiocarbamate)

The proton hyperfine coupling tensors of the methylene protons in methyl-deuterated copper(II) bis(N,N-diethyldithiocarbamate) in a diamagnetic host crystal of the corresponding nickel complex have been measured by ENDOR spectroscopy. Two intermolecular and all four intramolecular proton coupling tensors could be determined. With the aid of spin densities, obtained from extended Hückel molecular orbital calculations, the anisotropic part of the tensors can be reproduced quantitatively, taking into account all two- and three-centre contributions. Comparison of the transition frequencies which are computed from the theoretical tensors with the experimental transitions enables the tracing of another five tensors which cannot be completely determined experimentally.     

The effects of crystal structure on optical absorption/photoluminescence of bis(8-hydroxyquinoline)zinc

In this paper, the transformation processes of two types of bis(8-hydroxyquinoline)zinc: Znq₂ dihydrate and anhydrous (Znq₂)₄ were investigated by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The effects of crystal structure on optical properties of bis(8-hydroxyquinoiline)zinc were analyzed. Znq₂ dihydrate can be transformed into anhydrous (Znq₂)₄ during heating under vacuum. Reversal transformation occurs by the interaction between chloroform and (Znq₂)₄. But (Znq₂)₄ was partially transformed into Znq₂ dihydrate by the interaction between ethanol and (Znq₂)₄. The different molecular structure results in different crystal stacking and electronic structure, thereby affect its optical properties.     

Die Reaktion7Li (d, α)5He im Energiegebiet von 0,6 bis 2,0 MeV

The excitation function of the reaction⁷Li(d, α)⁵He has been measured between 0.6 and 2.0 MeV in steps of 50 keV. The two resonances at 0.75 and 1.00 MeV corresponding to the levels at 17.28 and 17.48 of the compound nucleus⁹Be were resolved. Angular distribution measurements were performed at 14 different energies mainly near the 1.00 MeV resonance. From the analysis of the data the 17.28 MeV level seems to be a positive parity state (3/2⁺ → 7/2⁺) whilst a negative parity (7/2^? or 9/2^?) is indicated for the 17.48 MeV level. This is contrary to the order of parities as given in the literature.     

The ENDOR spectrum of bis(p-methoxyphenyl)nitroxide

In this paper we develop useful expansions for the differential cross section in terms of the frequency moments of Van Hove's scattering function, i.e. the Placzek [1] and Wick [3] series. Using only the density independent terms of these series we compare their predictions with those obtained from the models described in paper I. It is concluded that for nitrogen, deuterium chloride and hydrogen chloride the single molecule interference term is given to high accuracy by our Placzek series, so that no density dependent terms are required. For the self terms of nitrogen, and chloride in the HCl and DCl molecules Placzek's series is satisfactory over the range of angles used in most experiments although Wick's series may be needed for angles near 180°. For the self term of D in DCl Wick's series is good over a moderate range of angles, but a realistic model for the rotational behaviour is needed over a wider range and also for all cases involving H in HCl.

The results presented here may be used for the interpretation of a wide range of neutron diffraction experiments, and are shown to be accurate for many cases to ～1 per cent.     

Assignment of bis(methylenedithio)tetrathiafulvalene vibrational spectra

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 4, pp. 622–627, April, 1990.     

Intrinsic d-wave effects in YBa(2)Cu(3)O(7-delta) grain boundary Josephson junctions

We have measured the angular dependence of the Josephson critical current density (J(C)) in c-axis tilt biepitaxial grain boundary YBa(2)Cu(3)O(7-delta) junctions. We observe for the first time intrinsic d-wave pairing symmetry effects manifested as an oscillatory dependence of J(C) on angle. This intrinsic effect is evident even though spontaneous currents, possibly induced by faceting or barrier impurities, are observed in the grain boundaries.     

Mechanochemical and thermal phase transition of bis(n-cyclohexylsalicylideneaminato) copper(II)

The mechanochemical and thermal properties of bis(N-cyclohexylsalicylideneaminato)copper(II) were investigated by means of DSC and X-ray diffractometry. The triclinic crystals (brown) of the complex were found to transform into monoclinic crystals (green) at 163°C with ΔH = 13.3 ± 0.3 kJ/mol. On pulverization at room temperature, the monoclinic green crystals were converted into the triclinic form; the accumulated strain in the green crystals being presumed to cause such a mechanochemical polymorphic transition.     

EPR studies of Cu<Superscript>2+</Superscript>-doped bis(saccharinato)bis(pyridine)zinc(II) single crystals

The electron paramagnetic resonance spectra of Cu²⁺ impurities in bis(saccharinato)bis(pyridine)zinc(II) single crystals have been studied at room temperature in three mutually perpendicular planes. The angular variation of the spectra indicates the substitution of the host Zn²⁺ with Cu²⁺. Two magnetically inequivalent sites for Cu²⁺ have been observed. The spectra were fitted to the rhombic spin Hamiltonian. The spin Hamiltonian parameters and the molecular orbital coefficients were evaluated for the two sites. The ground-state wave function of Cu²⁺ ion in the lattice has been constructed.     

Spectral studies of tetrabutylammonium bis(thiocyanate-S)phenylpyridinate(C,N)platinate(II)

The spectral and luminescent properties of tetrabutylammonium bis(thiocyanate-S)phenylpyridinate(C, N)platinate(II) were studied at 77 and 298 K in the polycrystalline state, frozen solutions, and polystyrene and polymethyl methacrylate films. The nature and properties of the electronically excited state of the complex responsible for its luminescence are determined.     

Theoretical investigation of a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives as high-energy-density materials

Using density functional theory (DFT), a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives with different linkages and substituents are investigated theoretically as potential high-energy-density materials (HEDMs). The heat of formation (HOF), detonation properties, natural bond orbital (NBO) and thermal stabilities are calculated and reported. The introduction of a furazan ring, an –N=N– bridge group and an –N₃ substituent is beneficial to increase the HOF of the title compounds. NBO analysis shows that there are electronic delocalisation effects among the bridge groups, furazan and tetrazole rings, and substituted groups. The conjugation effects and electronic transitions are influenced by the different linkages and substituents. The estimated detonation velocities and pressures indicate that the –ONO₂ and –NO₂ groups and the –N=N– linkage play important roles in enhancing the detonation properties. The bond dissociation energy (BDE) calculations reveal that the –NO₂ group is the substituent group which causes the least thermal stability. The bond between the substituent group and the tetrazole ring is the weakest bond in the title molecules. Considering the detonation performance and the thermal stability, 17 compounds may be promising candidates for HEDMs with good performance. Eight of them (A3, A4, C3, C4, D3, F3, G1 and G3) have better detonation properties than HMX.     

High‐resolution Brillouin scattering and heat capacity studies of bis(guanidinium)zirconium bis(nitrilotriacetate)hydrate, [C(NH2)3]2Zr[N(CH2COO)3]2·H2O

High‐resolution micro‐Brillouin scattering and heat capacitiy studies of polar bis(guanidinium)zirconium bis(nitrilotriacetate)hydrate were performed in the temperature range 230–305 K. Strong anomalies in the Brillouin shift and the attenuation were observed near 290 K upon cooling for the sound waves corresponding to the c₂₂ elastic constant. For this elastic constant, the coupling between the order parameter and the elastic strains is linear quadratic. In case of the c₄₄ and c₆₆, the coupling is biquadratic, giving rise to an increase of these parameters below 290 K. The analysis of the acoustic anomalies and heat capacity results near 290 K revealed that they correspond to a second‐order, cell‐multiplying, displacive phase transition. The second phase transition leads to weak acoustic anomalies at approximately 284 K. Copyright © 2009 John Wiley & Sons, Ltd.     

Structure of bis(4-Methyl Pyridine) Cadmium Tetracyanonickelate

Abstract

The structure, C₁₆H₁₄CdN₆Ni, consist of corrugated polymeric networks made up of tetracyanonickelate ions coordinated to Cd. The 4-methyl pyridine molecules bound to Cd in trans positions are located on both sides of the network. The bonding in the networks occurs because of a departure of the Ni-C-N-Cd sequence of atoms from linearity at the C and N positions. The crystal structure of the title compound was determined as monoclinic by single crystal X-Ray diffraction technique. The crystal parameters of this compound are as follows: monoclinic C2/m, a=18.156(2) Å, b=7.581(2) Å. c= 6.983(2) Å, β = 110.09(2)°, V = 902.6(5) ų Z=2, Dx = 1.698 g/cm³, F(000) - 456, λ (MoKα) = 0.71070 Å, μ = 2.121 mm^?1. The structure was solved by SHELXS-86 and refined by SHELXL-93. R = 0.02 for 1074 observed reflections with I > 2[sgrave] (I).     

EPR Studies on the intermolecular interactions of bis(di-ethanol-dithiocarbamato) copper(II)

The interaction of the title complex, [Cu(EtOH-dtc)₂], with I₂, Br₂ and different metal salts known as electron acceptors is studied in water-ethanol solution. Mixed-ligand complexes Cu(EtOH-dtc)⁺…X^? (X = Cl, Br, I, NO₃) are formed with X^? in the second coordination sphere of the metal ion. Cu(EtOH-dtc)₂ interacts with chloral-hydrate only in the presence of weak Lewis bases and Cu(EtOH-dtc)⁺…Cl^? mixed-ligand complex is formed. The interactions with metal chelates cause the formation of mixed-ligand chelate complexes. Cu(EtOH-dtc)₂ interacts with H₂O₂ and the appearance of mixed-ligand complexes as intermediate products is detected. The final product obtained is CuSO₄. In the presence of O₂ Cu(EtOH-dtc)₂ yielded spectra similar to the above intermediate products. The proposed mechanisms of all studied reactions are discussed on the ground of the recorded spectra.     

Comparison of the Si(111) (7 × 7) and (1×1)surfaces

High-resolution electron energy-loss spectroscopy and monochromatic low-energy electron diffraction have been applied to the study of the Si(111)(7 × 7) surface and the thermally-quenched Si(111) (1 × 1) surface. For the (1 × 1) surface, the inelastic continuum, observed for the (7 × 7) surface, due to the Drude absorption of electrons in the dangling-bond surface states is not existent, which indicates that the surface-state band associated with the dangling-bonds of the (1 × 1) surface is insulating. The observed electronic transitions indicate that the (7 × 7) and (1 × 1) surfaces have similar local band geometries and that they differ only in long-range order. The (1 × 1) surface is considered to have a disordered structure. The defect model is favored for the (7 × 7) structure.     

Molecular Spectral Analysis and Ab Initio Calculations of bis(3-aminopyridinium) Tetrachlorocuprate (II), 3-Ammoniumpyridinium Tetrachlorocuprate (II), and bis(3-aminopyridinium) Hexachlorodicuprate (II)

The aromatic character, distortion, and stabilization as a result of single and double protonation of 3-aminopyridine like three different complex salts were studied by infrared-, ultraviolet spectral analysis, proton nuclear magnetic resonance, and quantum chemical ab initio calculations. Linear-dichroic infrared spectroscopy was applied for identification of the infrared bands. The correlation structure-spectroscopic properties of the model systems are determined: bis(3-aminopyridinium) tetrachlorocuprate (II) salt, where the ring nitrogen atom participates in protonation; 3-ammoniumpyridinium tetrachlorocuprate (II) salt, where both nitrogen atoms are protonated; and a complex with copper (II) bis(3-aminopyridinium) hexachlorodicuprate (II), where the metal ion is coordinated through amino group.