A cooperative group study of clinical efficacy of the liver SPECT

The purpose of this study is to evaluate the clinical efficacy of the liver SPECT about detectability of SOLs (space occupying lesion). The images were interpreted with the planar scintigram (PS) only and combination of PS and SPECT (single photon emission computed tomography) by 11 physicians. Changes of false positive and false negative rate were calculated to evaluate the influence of the diffuse parenchymal liver disease and the localization of the SOLs. Addition of SPECT to PS in the cases who are suspected SOLs is effective in right hepatic lobe (right anterior and posterior segment) to detect the SOLs, but not effective in left lateral segment. Addition of SPECT to PS in the cases with diffuse parenchymal liver disease and SOLs increases the false positive rate.     

Some exponential type bounds for hitting time distributions of storage processes

We consider a storage process with finite or infinite capacity having a compound Poisson process as input and general release rule. For this process we derive some exponential type upper and lower bounds for hitting time distributions by means of martingale theory.     

Total syntheses of natural tubelactomicins B, D, and E: establishment of their stereochemistries

Total syntheses of the antimicrobial tricyclic 16-membered macrolides, (+)-tubelactomicin B, (+)-tubelactomicin D, and (+)-tubelactomicin E, have been accomplished for the first time with common synthetic approaches. These total syntheses established the relative and absolute configurations of the three tubelactomicins, for which planar structures had solely been reported. The total synthesis of (+)-tubelactomicin D included a newly developed stereoselective intramolecular Diels-Alder reaction for constructing the highly functionalized octahydronaphthalene substructures.     

Highly enantioselective and efficient synthesis of flavanones including pinostrobin through the rhodium-catalyzed asymmetric 1,4-addition

An efficient synthesis of bioactive chiral flavanones (1) was achieved through the Rh-catalyzed asymmetric 1,4-addition of arylboronic acid to chromone. The reaction in toluene proceeded smoothly at room temperature in the presence of 0.5% Rh catalyst with electron-poor chiral diphosphine MeO-F(12)-BIPHEP. In this reaction, the 1,2-addition to (S)-1 frequently occurred to yield (2S,4R)-2,4-diaryl-4-chromanol as a byproduct, which could be reduced by changing the reaction solvent to CH(2)Cl(2) to deactivate the Rh catalyst (3% required).     

Preparations of polystyrene/aluminum hydroxide and polystyrene/alumina composite particles in an ionic liquid

Polystyrene (PS)/aluminum hydroxide (Al(OH)(3)) composite particles were successfully prepared by the sol-gel process of aluminum isopropoxide (Al(OPr(i))(3)) in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) using ammonium hydroxide (NH(4)OH) as a catalyst in the presence of PS seed. Transmission electron microscopy observation of ultrathin cross-sections of the composite particles revealed that the composite particles had a core-shell morphology consisting of a PS core and a Al(OH)(3) shell having high crystallinity. The amount of secondary nucleated Al(OH)(3) could be reduced by dropwise addition of NH(4)OH. Moreover, PS/η-Al(2)O(3) composite particles were successfully prepared by heat treatment of PS/Al(OH)(3) at 300 °C in N(2) atmosphere, which is below the decomposition temperature of PS.     

Metallation of a cyclic chlorophyll hetero-dyad, and the optical properties of synthetic metallo-dyads

A cyclic chlorophyll hetero-dyad 1-H₂H₂, prepared by double ester linking of two structurally different pyropheophorbide-a moieties through 3-CH₂OCO-13²′ and 17²-COOCH₂-3′, was metallated with zinc and copper to give mono and di-metallated complexes 1-MH₂ or 1-H₂M and 1-MM. The metallation proceeded stepwise and regioselectively, with predominant synthesis of one of the two mono-metallated complexes 1-MH₂ as intermediate. The di-zinc complex produced, 1-ZnZn, was demetallated exclusively via the same mono-zinc complex 1-ZnH₂ as was the major intermediate during metallation. Visible and/or circular dichroism spectra of 1-H₂H₂, 1-MH₂, 1-H₂M, and 1-MM (M = Ni, Cu, or Zn) were measured in organic solvents. Intramolecular interaction of chlorin chromophores is discussed and compared with that of the corresponding monomeric species.     

Synthesis and hybridization properties of 2′-O-(tetrazol-5-yl)ethyl-modified oligonucleotides

2′-O-(1H-Tetrazol-5-yl)ethyladenosine was synthesized using 2′-O-cyanoethyladenosine derivative as a key intermediate. The 2′-O-(1H-tetrazol-5-yl)ethyl modifications exhibited intriguing properties such as the change in the structure of the tetrazole residue between a protonated and a deprotonated form. The T_m experiments of various oligodeoxynucleotides having a 2′-O-(1H-tetrazol-5-yl)ethyl-modified adenosine showed reduced hybridization affinity in comparison to the unmodified oligonucleotides toward their complementary oligodeoxynucleotides. The mechanism of the reduced hybridization affinity was discussed on the basis of the structure and the physicochemical properties of the tetrazole moiety.     

Preparation and applications of novel fluoroalkyl end-capped 2-acrylamido-2-methylpropanesulfonic acid oligomer/clay nanocomposites

New fluoroalkyl end-capped 2-acrylamido-2-methylpropanesulfonic acid oligomers/clay composites were prepared by reaction of fluoroalkanoyl peroxide with the corresponding monomer in the presence of clay in aqueous solutions. These obtained fluorinated composites were nanometer size-controlled and were found to exhibit a good dispersibility in water and polar organic solvents such as methanol. The contents of clay in these nanocomposites were estimated to be 3～19% by the thermogravimetric analysis measurements. X-ray diffraction spectra showed the successful intercalation of fluorinated oligomers into the interlayer spaces of clay. These fluorinated clay nanocomposites were applied to the surface modification of poly(vinyl alcohol). In addition, these fluorinated nanocomposites were found to interact with methylene blue effectively to afford the fluorinated oligomers/clay/methylene blue nanocomposites.