[The Evaluation of the MRSA Selective Agar Medium Using Chromogenic Enzyme Substrate from Clinical Specimens].

We evaluated MRSA-CI agar (Kyokuto Pharmaceutical Industrial Co., Ltd.) and BD BBL CHROMagar MRSA II agar (BD Japan) for the detection of Methicillin-resistant Staphylococcus aureus (MRSA). We used 129 specimens in this study. The positive rate of MRSA-CI agar was 19.4% (25/129 samples), whereas BD BBL CHROMagar MRSA II was 17.8% (23/129 samples). It is suggested that MRSA selective agar medium including enzyme substrate compounds is a useful medium to detect MRSA.

Ethereal C-O Bond Cleavage Mediated by Ni(0)-Ate Complex: A DFT Study.

Density functional theory calculations were performed to explore the mechanism of Ni-catalyzed cross-coupling reactions involving organo-lithium and -zinc reagents through ethereal C-O bond cleavage. Based on this work, together with our previous mechanistic study on etheric Kumada-Tamao reaction, we identify and characterize a novel catalytic cycle for cross-coupling mediated by Ni(0)-ate complex.

In Situ Generation of Silyl Anion Species through Si-B Bond Activation for the Concerted Nucleophilic Aromatic Substitution of Fluoroarenes.

In situ generated silyl anion species enable the concerted nucleophilic aromatic substitution of fluoroarenes. Model DFT calculations indicated that addition of a base to a silylborane would thermodynamically form a silyl borate complex and then kinetically release a silyl anion species through Si-B bond cleavage, and that the in situ generated silyl anion equivalent would further react with a fluoroarene through a concerted nucleophilic aromatic substitution pathway with an activation barrier of ca. 20 kcal/mol to afford the silylated product with a large energy gain. Experiments confirmed that the defluorosilylation reaction took place smoothly at room temperature simply upon mixing fluoroarenes with commercially available silylborane and NaOt Bu. Radical scavenger and radical clock reaction experiments provide further evidence for the in situ generation of the silyl anion.

Native prion protein homodimers are destabilized by oligomeric amyloid ß 1-42 species as shown by single-molecule imaging.

Prion proteins (PrPc) are receptors for amyloid ß 1-42 (Aß1-42) oligomers, but we do not know the impact of Aß1-42 binding to PrPc on the interaction of membrane-bound PrPc with molecules that regulate downstream biological pathways. Stability of the PrPc dimeric complex and subsequent intermolecular interactions with membranous or cytoplasmic molecules are important for physiological functions of PrPc including neuroprotection. The principal aim of this study was to determine whether homodimer lifetime of PrPc is affected by the presence of Aß1-42 oligomers. Single-molecule imaging analysis was carried out by total internal reflection fluorescence microscopy in PrPc-transfected CHO-K1 cells in the absence or presence of characterized Aß1-42 oligomers. The contribution of different Aß1-42 oligomer conformations to Alzheimer's disease pathophysiology and to the associated neurotoxicity is unknown. To be precise, with the oligomeric species used in our study, we biochemically analyzed the molecular weight of oligomers formed from Aß1-42 monomers under our experimental conditions. The lifetime of PrPc homodimers was 210 ms, and in the presence of Aß1-42 oligomers, the lifetime was significantly reduced (to 92 ms). The reduction of PrPc homodimer lifetime by Aß1-42 oligomers may impair PrPc-mediated downstream neuroprotective signaling.

CD52 is a novel costimulatory molecule for induction of CD4+ regulatory T cells.

We previously reported that 4C8 monoclonal antibody (mAb) provides a costimulatory signal to human CD4+ T cells and consequently induces regulatory T (Treg) cells, which are hypo-responsive and suppress the polyclonal response of bystander CD4+ cells in a contact-dependent manner. In this study, we identified the antigen of 4C8 mAb as CD52. Costimulation with Campath-1H, a humanized anti-CD52 mAb, also induced Treg cells. Anti-CD52-induced Treg cells suppressed the proliferation of both CD4+ and CD8+ T cells provided with polyclonal or allogeneic stimulation. When Treg cells were induced from Staphylococcal enterotoxin B (SEB) treated cells, they suppressed the response to SEB more efficiently than that to another superantigen, SEA. Furthermore, anti-CD52-induced Treg cells could be expanded by culture with IL-2 followed by CD52-costimulation, and co-injection of expanded Treg cells suppressed lethal xenogeneic graft versus host disease (GvHD) reactions in SCID mice caused by human peripheral blood mononuclear cells (PBMCs).

cAMP modulation of Ca(2+)-regulated exocytosis in ACh-stimulated antral mucous cells of guinea pig.

Effects of cAMP accumulation on ATP-dependent priming and Ca(2+)-dependent fusion in Ca(2+)-regulated exocytosis were examined in antral mucous cells of guinea pigs by using video-enhanced contrast microscopy. The Ca(2+)-regulated exocytosis activated by 1 microM ACh consisted of two phases, an initial transient phase followed by a sustained phase, which were potentiated by cAMP accumulation. Depletion of ATP by 100 microM dinitrophenol (uncoupler of oxidative phosphorylation) or anoxia induced the sustained phase without the initial transient phase in Ca(2+)-regulated exocytosis. However, accumulation of cAMP before depletion of ATP induced and potentiated an initial transient phase followed by a sustained phase in Ca(2+)-regulated exocytosis. This suggests that the initial transient phase of Ca(2+)-regulated exocytosis is induced by fusion of all primed granules maintained by ATP and that accumulation of cAMP accelerates ATP-dependent priming of the exocytotic cycle. Moreover, ACh and Ca(2+) dose-response studies showed that accumulation of cAMP shifted the dose-response curves to the low concentration side, suggesting that it increases Ca(2+) sensitivity in the fusion of the exocytotic cycle. In conclusion, cAMP accumulation increases the number of primed granules and Ca(2+) sensitivity of the fusion, which potentiates Ca(2+)-regulated exocytosis in antral mucous cells.