Solid-phase syntheses of olefin-containing inhibitors for HTLV-1 protease using the Horner-Emmons reaction

[reaction: see text] The solid-phase Horner-Emmons reaction was successfully applied for the convenient syntheses of olefin-containing protease inhibitors. The isomerization during the solid-phase Horner-Emmons reaction can be minimized simply by the use of an appropriate amount of the base. The synthesized olefin peptides, which have an olefin gamma-amino acid at the scissile site, were found to act as effective inhibitors for the HTLV-1 protease for the first time.     

Conformation of solvent N,N-dimethylpropionamide in the coordination sphere of the zinc(II) ion studied by Raman spectroscopy and DFT calculations

Solvation structure of the zinc(II) ion in N,N-dimethylpropionamide (DMPA) was studied by Raman spectroscopy at varying temperature and by quantum mechanical calculations. No significant ion-pair formation was found for the Zn(ClO4)2 solution in the molality range m(Zn) < 1.5 mol kg(-1), and the solvation number of the zinc(II) ion was determined to be 4, indicating that 6-coordination of DMPA is sterically hindered. Interestingly, DMPA molecules are under equilibrium between planar cis and nonplanar staggered conformers, and the latter is more preferred in the coordination sphere, while the reverse is the case in the bulk. The DeltaG degrees , DeltaH degrees , and TDeltaS degrees values of conformational change from planar cis to nonplanar staggered in the coordination sphere were obtained to be -0.9, -8.5, and -7.5 kJ mol(-1), respectively. Density functional theory (DFT) calculations show that the planar cis conformer is more favorable than the nonplanar staggered one in the 1:2 cluster, as is the case for a single DMPA molecule and H(DMPA)+, indicating that there hardly occurs solvent-solvent interaction through the metal ion in the Zn2+-DMPA 1:2 cluster. On the other hand, the SCF energy of [Zn(planar cis-DMPA)4-n(nonplanar staggered DMPA)n]2+ (n = 0-4) decreases with increasing n, implying that the nonplanar staggered conformer is preferred in the solvate ion. It is thus concluded that solvent-solvent interaction through space, or solvation steric effect, plays a crucial role in the conformational equilibrium in the coordination sphere of the four-solvate metal ion.     

Effect of tetrabutylphosphonium cation on the physico-chemical properties of amino-acid ionic liquids

Tetraalkylphosphonium-based amino-acid ionic liquids show lower viscosities and higher decomposition temperatures (>300 degrees C) than previously reported ammonium-based amino-acid ionic liquids.     

Enantioselective synthesis mediated by chiral crystal of achiral hippuric acid in conjunction with asymmetric autocatalysis

Enantiomorphous crystals composed of achiral hippuric acid, i.e., naturally occurring N-benzoylglycine, have been used successfully as chiral inducers in enantioselective synthesis in combination with asymmetric autocatalysis to afford the product with extremely high enantiomeric excess.     

Structural study of NO adsorbed on the reconstructed Pt(110)-(1 x 2) surface with X-ray photoelectron diffraction and near-edge X-ray absorption fine structure spectroscopy

The adsorption structure of NO on the reconstructed Pt(110)-(1 x 2) surface was studied with X-ray photoelectron spectroscopy (XPS), X-ray photoelectron diffraction (XPD), low-energy scanned-angle photoelectron diffraction (LESA-PD), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The experiments were performed at 180 K, where no surface lifting from (1 x 2) to (1 x 1) takes place after NO adsorption. XPS indicates that the (1 x 2) unit cell of the Pt(110) surface contains 1.5 NO molecules at the saturated coverage. XPD and LESA-PD analyses allow us to propose a structural model for the NO adlayer, where two-thirds of the NO molecules in the (1 x 2) unit cell are adsorbed on the atop site of the close-packed Pt rows (ridges) along the [10] direction with an inclined geometry and one-third of the NO molecules adsorb on the bridge site between the Pt ridges with an upright configuration. This model is supported by the N K-edge NEXAFS experiments and is consistent with the recently reported model based on the density functional theory (Orita, H.; Nakamura, I.; Fujitani, T. J. Phys. Chem. B 2005, 109, 10312).     

Differences in dual-task performance and prefrontal cortex activation between younger and older adults

Background

The purpose of this study was to examine task-related changes in prefrontal cortex (PFC) activity during a dual-task in both healthy young and older adults and compare patterns of activation between the age groups. We also sought to determine whether brain activation during a dual-task relates to executive/attentional function and how measured factors associated with both of these functions vary between older and younger adults.

Results

Thirty-five healthy volunteers (20 young and 15 elderly) participated in this study. Near-infrared spectroscopy (NIRS) was employed to measure PFC activation during a single-task (performing calculations or stepping) and dual-task (performing both single-tasks at once). Cognitive function was assessed in the older patients with the Trail-making test part B (TMT-B). Major outcomes were task performance, brain activation during task (oxygenated haemoglobin: Oxy-Hb) measured by NIRS, and TMT-B score. Mixed ANOVAs were used to compare task factors and age groups in task performance. Mixed ANOVAs also compared task factors, age group and time factors in task-induced changes in measured Oxy-Hb. Among the older participants, correlations between the TMT-B score and Oxy-Hb values measured in each single-task and in the dual-task were examined using a Pearson correlation coefficient. Oxy-Hb values were significantly increased in both the calculation task and the dual-task within patients in both age groups. However, the Oxy-Hb values associated with there were higher in the older group during the post-task period for the dual-task. Also, there were significant negative correlations between both task-performance accuracy and Oxy-Hb values during the dual-task and participant TMT-B scores.

Conclusions

Older adults demonstrated age-specific PFC activation in response to dual-task challenge. There was also a significant negative correlation between PFC activation during dual-task and executive/attentional function. These findings suggest that the high cognitive load induced by dual-task activity generates increased PFC activity in older adults. However, this relationship appeared to be strongest in participants with better baseline attention and executive functions.     

Study of Strangeness Photoproduction on the Neutron in the Threshold Region

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K ⁰ with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K ⁰ + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K ₁, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K ⁺ Λ.