Reduction of amine N-oxides by diboron reagents

Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis(pinacolato)- and in some cases bis(catecholato)diboron [(pinB)(2) and (catB)(2), respectively]. Reductions occur upon simply mixing the amine N-oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N'-dioxide of (S)-(-)-nicotine. Because it was observed that (pinB)(2) was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)(2), triethylborane reduced alkylamino-N-oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)(2) has been probed by (1)H and (11)B NMR.     

AGR2, a mucinous ovarian cancer marker, promotes cell proliferation and migration

Ovarian cancer is a leading cause of death in women. Early detection of ovarian cancer is essential to decrease mortality. However, the early diagnosis of ovarian cancer is difficult due to a lack of clinical symptoms and suitable molecular diagnostic markers. Thus, identification of meaningful tumor biomarkers with potential clinical application is clearly needed. To search for a biomarker for the early detection of ovarian cancer, we identified human anterior gradient 2 (AGR2) from our systematic analysis of paired normal and ovarian tumor tissue cDNA microarray. We noted a marked overexpression of AGR2 mRNA and protein in early stage mucinous ovarian tumors compared to normal ovarian tissues and serous type ovarian tumors by Western blot analysis and immunohistochemistry. To further elucidate the role of AGR2 in ovarian tumorigenesis, stable 2774 human ovarian cancer cell lines overexpressing AGR2 were established. Forced expression of AGR2 in 2774 cells enhanced the growth and migration of ovarian cancer cells. AGR2 protein was detected in the serum of mucinous ovarian cancer patients by Western blot and ELISA analysis. Thus, AGR2 is a potential biomarker for the diagnosis of mucinous ovarian cancer and an ELISA assay may facilitate the early detection of mucinous ovarian cancer using patient serum.     

Suppression of hepatic tumor growth and metastasis by metronomic therapy in a rat model of hepatocellular carcinoma

Although continuous low-dose (metronomic [MET]) therapy exerts anti-cancer efficacy in various cancer models, the effect of long-term MET therapy for hepatocellular carcinoma (HCC) remains unknown. This study assessed the long-term efficacy of MET on suppression of tumor growth and spontaneous metastasis in a rat model of HCC induced by administration of diethylnitrosamine for 16 wk. The rats were divided into 3 groups: MTD group received intraperitoneal (i.p.) injections of 40 mg/kg cyclophosphamide on days 1, 3, and 5 of a 21-day cycle; Control and MET groups received i.p. injections of saline and 20 mg/kg cyclophosphamide twice a week, respectively. Anti-tumor and anti-angiogenic effects and anti-metastatic mechanisms including matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were evaluated. Twelve wk of MET therapy resulted in a significant reduction in intrahepatic tumors than control or MTD therapy. The MET group had fewer proliferating cell nuclear antigen-positive cells and decreased hypoxia-inducible factor-1α levels and microvessel density. Lung metastases were detected in 100%, 80%, and 42.9% in the control, MTD, and MET groups, respectively. MET therapy significantly decreased expression of TIMP-1, MMP-2 and -9. For mediators of pro-MMP-2 activation, MET therapy induced significant suppression in the TIMP-2 and MMP-14 level. The survival in the MET group was significantly prolonged compared to the control and MTD groups. Long-term MET scheduling suppresses tumor growth and metastasis via its potent anti-angiogenic properties and a decrease in MMPs and TIMPs activities. These results provide a rationale for long-term MET dosing in future clinical trials of HCC treatment.     

Polybenzimidazole block sulfonated poly(arylene ether sulfone) ionomers

Novel ionomers based on polybenzimidazole block sulfonated poly(arylene ether sulfone) show excellent thermal properties. The ionic aggregation of sulfonic acid groups leads to well-developed phase separated morphology and thus high proton conductivity at wide humidity range, up to 65 mS cm(-1) at 90% relative humidity.     

The synthesis and spectral properties of a stimuli-responsive D-π-A charge transfer dye

A new donor-π-acceptor (D-π-A) type isophorone dye was synthesized by the condensation reaction between 2-(3,5,5-trimethylcyclohex-2-enylidene)-malononitrile and indole-3-carboxaldehyde. The chemical structure of the dye was characterized by 1H NMR, EA and MS. A novel, chromogenic, fluorescent dye based on indol as donor unit and isophorone as acceptor unit displayed marked UV-visible absorption changes and highly selective fluorescence quenching in the presence of fluoride ion. The dye also exhibited sizeable colour changes when used as a pH-induced molecular switch and as a detector for volatile organic compounds. The absorption and fluorescent intensity of the dye can be reversibly selected by protonation/deprotonation of the amine moiety via control of intramolecular charge transfer (ICT), leading to a molecular switch with "on" and "off" states.     

Highly sensitive phototransistor with crystalline microribbons from new π-extended pyrene derivative via solution-phase self-assembly

A new pyrene-cored π-conjugated molecule has been synthesized through Sonogashira coupling reaction. The single-crystalline microribbon-based FET exhibited the highest mobility of 0.7 cm(2) V(-1) s(-1) (I(on)/I(off) > 10(6)). Single-crystalline microribbons were employed to operate in an organic phototransistor (OPT) under very low light intensity (I = 5.6 μW cm(-2)).     

Fractionation of herbaceous biomass by ammonia-hydrogen peroxide percolation treatment

Applied Biochemistry and Biotechnology - Treatment with ammonia and hydrogen peroxide was investigated as a means of fractionating herbaceous biomass. The main feature of this process is that...     

Crystallinity and morphology dependent luminescence of Li-doped Y2−xGdxO3:Eu thin film phosphors

The influence of lithium doping on the crystallization, the surface morphology, and the luminescent properties of pulsed laser deposited Y_2−xGd_xO₃:Eu³⁺ thin film phosphors was investigated. The crystallinity, the surface morphology, and the photoluminescence (PL) of films depended highly on the Li-doping and the Gd content. The relationship between the crystalline and morphological structures and the luminescent properties was studied, and Li⁺ doping was found to effectively enhance not only the crystallinity but also the luminescent brightness of Y_2−xGd_xO₃:Eu³⁺ thin films. In particular, the incorporation of Li and Gd into the Y₂O₃ lattice could induce remarkable increase in the PL. The highest emission intensity was observed Li-doped Y_1.35Gd_0.6O₃:Eu³⁺ thin films whose brightness was increased by a factor of 4.6 in comparison with that of Li-doped Y₂O₃:Eu³⁺ thin films.     

Bidirectional WDM Self-Healing Ring Network for Hub/Remote Nodes

We demonstrate a bidirectional WDM self-healing ring network for hub/remote nodes with one fiber. In this network, self-healing can be achieved within 8 ms. The transmission capacity can be doubled in the operating state.