Gold nanoparticles stabilized by phosphine-decorated polymer immobilized ionic liquids (AuNP@PPh2-PIILP) is an extremely efficient multiproduct selective catalyst for the sodium borohydride-mediated reduction of nitrobenzene giving N-phenylhydroxylamine, azoxybenzene, or aniline as the sole product under mild conditions and a very low catalyst loading. The use of a single nanoparticle-based catalyst for the partial and complete reduction of nitroarenes to afford three different products with exceptionally high selectivities is unprecedented. Under optimum conditions, thermodynamically unfavorable N-phenylhydroxylamine can be obtained as the sole product in near quantitative yield in water, whereas a change in reaction solvent to ethanol results in a dramatic switch in selectivity to afford azoxybenzene. The key to obtaining such a high selectivity for N-phenylhydroxylamine is the use of a nitrogen atmosphere at room temperature as reactions conducted under an inert atmosphere occur via the direct pathway and are essentially irreversible, while reactions in air afford significant amounts of azoxy-based products by virtue of competing condensation due to reversible formation of N-phenylhydroxylamine. Ultimately, aniline can also be obtained quantitatively and selectively by adjusting the reaction temperature and time accordingly. Introduction of PEG onto the polyionic liquid resulted in a dramatic improvement in catalyst efficiency such that N-phenylhydroxylamine could be obtained with a turnover number (TON) of 100 000 (turnover frequency (TOF) of 73 000 h–1, with >99% selectivity), azoxybenzene with a TON of 55 000 (TOF of 37 000 h–1 with 100% selectivity), and aniline with a TON of 500 000 (TOF of 62 500 h–1, with 100% selectivity). As the combination of ionic liquid and phosphine is required to achieve high activity and selectivity, further studies are currently underway to explore whether interfacial electronic effects influence adsorption and thereby selectivity and whether channeling of the substrate by the electrostatic potential around the AuNPs is responsible for the high activity. This is the first report of a AuNP-based system that can selectively reduce nitroarenes to either of two synthetically important intermediates as well as aniline and, in this regard, is an exciting discovery that will form the basis to develop a continuous flow process enabling facile scale-up.

BackgroundPrevious studies have shown that disruption of GABA signaling in mice via mutations in the Gad1, Gabrb3 or Viaat genes leads to the development of non-neural developmental defects such as cleft palate. Studies of the Gabrb3 and Gad1 mutant mice have suggested that GABA function could be required either in the central nervous system or in the palate itself for normal palatogenesis.Methodology/Principal FindingsTo further examine the role of GABA signaling in palatogenesis we used three independent experimental approaches to test whether Gad1 or Viaat function is required in the fetal CNS for normal palate development. We used oral explant cultures to demonstrate that the Gad1 and Viaat mutant palates were able to undergo palatogenesis in culture, suggesting that there is no defect in the palate tissue itself in these mice. In a second series of experiments we found that the GABAA receptor agonist muscimol could rescue the cleft palate phenotype in Gad1 and Viaat mutant embryos. This suggested that normal multimeric GABAA receptors in the CNS were necessary for normal palatogenesis. In addition, we showed that CNS-specific inactivation of Gad1 was sufficient to disrupt palate development.Conclusions/SignificanceOur results are consistent with a role for Gad1 and Viaat in the central nervous system for normal development of the palate. We suggest that the alterations in GABA signaling lead to non-neural defects such as cleft palate as a secondary effect due to alterations in or elimination of fetal movements.

A point mutation leading to amino acid substitution N1922S in the A3 domain of factor VIII (fVIII) results in moderate to severe hemophilia A. A heterologous expression system comparing N1922S-fVIII and wild-type fVIII (wt-fVIII) demonstrated similar specific coagulant activities but poor secretion of N1922S-fVIII. Immunocytochemical analysis revealed that intracellular levels of N1922S-fVIII were similar to those of wt-fVIII. The specific activity of intracellular N1922S-fVIII was 10% of that of wt-fVIII, indicating the presence of large amounts of a nonfunctional N1922S-fVIIIfolding intermediate. wt-fVIII colocalized with both endoplasmic reticulum (ER)-and Golgi-resident proteins. In contrast, N1922S-fVIII colocalized only with ERresident proteins, indicating a block in transit from the ER to the Golgi. A panel of conformation-dependent monoclonal antibodies was used to determine native or nonnative folding of N1922S-fVIII. Intracellular N1922S-fVIII but not secreted N1922S-fVIII displayed abnormal folding in the A3 and C1 domains, indicating that the A1, A2, and C2 domains fold independently into antigenically intact tertiary structures, but that folding is stalled in the mutant A3 and its contiguous C1 domain. In summary, the N1922S substitution results in poor secretion of a functional protein, and the domain-specific defect in folding and intracellular trafficking of N1922S-fVIII is a novel mechanism for secretion defects leading to hemophilia A. (Blood. 2011;117(11):3190-3198) IntroductionHemophilia A is an X-linked bleeding disorder caused by a deficiency of factor VIII (fVIII). It is classified as mild, moderate, or severe based on plasma fVIII levels of greater than 0.05-0.4 U/mL, 0.01-0.05 U/mL, or less than 0.01 U/mL, respectively. 1 With some exceptions, this classification correlates well with the bleeding diathesis such that patients with mild disease have abnormal bleeding only after trauma or surgery, whereas severe hemophilia A is characterized by spontaneous bleeding into joints or soft tissues. 2 FVIII is synthesized as an ϳ 300-kDa glycoprotein by hepatocytes, liver sinusoidal endothelial cells, and certain types of extrahepatic endothelial cells. [3][4][5][6] It contains a domain sequence designated A1-A2-B-ap-A3-C1-C2 and circulates as an A1-A2-B/ ap-A3-C1-C2 heterodimer bound noncovalently to von Willebrand factor (VWF), which protects it from rapid clearance. 7 The homologous ϳ 40-kDa A1, A2, and A3 domains are each made up of 2 cupredoxin-like subdomains that form an extensive interface. [8][9][10] During the activation of fVIII by thrombin to fVIIIa, the B domain and an ap activation peptide are released, and cleavage between the A1 and A2 domains produces an A1/A2/A3-C1-C2 fVIIIa heterotrimer. 11 FVIIIa is a cofactor for factor IXa during the proteolytic activation of factor X on relevant phospholipid membrane surfaces. At physiologic concentrations, the A2 subunit spontaneously dissociates, leading to loss of fVIIIa cofactor activity. 12 Mild and moderate hemophilia A are caused by ...

No abstract

PBFC has high sensitivity and specificity for the diagnosis of childhood acute leukemia. The predictive value of PBFC remains high for patients without visible circulating blasts and may enhance the diagnostic process for determining the indications for marrow testing.