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961.
Chung BH Kim S Kim JD Lee JJ Baek YY Jeoung D Lee H Choe J Ha KS Won MH Kwon YG Kim YM 《Experimental & molecular medicine》2012,44(3):191-201
Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an important role in vascular functions, including vasorelaxation. We here investigated the pharmacological effect of the natural product syringaresinol on vascular relaxation and eNOS-mediated NO production as well as its underlying biochemical mechanism in endothelial cells. Treatment of aortic rings from wild type, but not eNOS(-/-) mice, with syringaresinol induced endothelium-dependent relaxation, which was abolished by addition of the NOS inhibitor N(G)-monomethyl-L-arginine. Treatment of human endothelial cells and mouse aortic rings with syringaresinol increased NO production, which was correlated with eNOS phosphorylation via the activation of Akt and AMP kinase (AMPK) as well as elevation of intracellular Ca(2+) levels. A phospholipase C (PLC) inhibitor blocked the increases in intracellular Ca(2+) levels, AMPK-dependent eNOS phosphorylation, and NO production, but not Akt activation, in syringaresinol- treated endothelial cells. Syringaresinol-induced AMPK activation was inhibited by co-treatment with PLC inhibitor, Ca(2+) chelator, calmodulin antagonist, and CaMKKβ siRNA. This compound also increased eNOS dimerization, which was inhibited by a PLC inhibitor and a Ca(2+)-chelator. The chemicals that inhibit eNOS phosphorylation and dimerization attenuated vasorelaxation and cGMP production. These results suggest that syringaresinol induces vasorelaxation by enhancing NO production in endothelial cells via two distinct mechanisms, phosphatidylinositol 3-kinase/Akt- and PLC/Ca(2+)/CaMKKβ-dependent eNOS phosphorylation and Ca(2+)-dependent eNOS dimerization. 相似文献
962.
Overexpression of HER2 correlates with more aggressive tumors and increased resistance to cancer chemotherapy. However, a functional comparison between the HER2(high)/HER3 and the HER2(low)/HER3 dimers on tumor metastasis has not been conducted. Herein we examined the regulation mechanism of heregulin- β1 (HRG)-induced MMP-1 and -9 expression in breast cancer cell lines. Our results showed that the basal levels of MMP-1 and -9 mRNA and protein expression were increased by HRG treatment. In addition, HRG-induced MMP-1 and -9 expression was significantly decreased by MEK1/2 inhibitor, U0126 but not by phosphatidylinositol 3-kinase (PI-3K) inhibitor, LY294002. To confirm the role of MEK/ERK pathway on HRG-induced MMP-1 and -9 expression, MCF7 cells were transfected with constitutively active adenoviral- MEK (CA-MEK). The level of MMP-1 and -9 expressions was increased by CA-MEK. MMP-1 and -9 mRNA and protein expressions in response to HRG were higher in HER2 overexpressed cells than in vector alone. The phosphorylation of HER2, HER3, ERK, Akt, and JNK were also significantly increased in HER2 overexpressed MCF7 cells compared with vector alone. HRG-induced MMP-1 and -9 expressions were significantly decreased by lapatinib, which inhibits HER1 and HER2 activity, in both vector alone and HER2 overexpressed MCF7 cells. Finally, HRG-induced MMP-1 and MMP-9 expression was decreased by HER3 siRNA overexpression. Taken together, we suggested that HRG-induced MMP-1 and MMP-9 expression is mediated through HER3 dependent pathway and highly expressed HER2 may be associated with more aggressive metastasis than the low expressed HER2 in breast cancer cells. 相似文献
963.
WS Chi JW Han S Yang DK Roh H Lee JH Kim 《Chemical communications (Cambridge, England)》2012,48(76):9501-9503
A low cost, low-temperature processable, highly efficient nickel sulfide counter electrode is demonstrated. Using the tailored, preformed nickel sulfide nanoparticles and electrostatic self-assembly, a novel counter electrode was fabricated that exceeded the efficiency of a conventional Pt-based cell. 相似文献
964.
Koo BH Lim KS Ryu DW Lee WR Koh EK Hong CS 《Chemical communications (Cambridge, England)》2012,48(19):2519-2521
A tetranuclear Er(III) compound chelated with N(2)O(2) donors of a tetradentate Schiff base was produced from the self-assembly of the corresponding chemical species. This intriguing cluster shows field-induced slow relaxation of magnetization. 相似文献
965.
The conjunction of porous ZIF-8 with polystyrene spheres is demonstrated to induce the formation of polystyrene@ZIF-8 core-shell structures. A subsequent etching process on polystyrene@ZIF-8 core-shells to remove polystyrene cores results in a unique hollow ZIF-8. 相似文献
966.
We show that the Kerr metric does not exist as a fully rotating black hole solution to modified Hořava–Lifshitz (HL) gravity
with Λ
W
=0 and λ=1. We do this by showing that the Kerr metric does not satisfy the full equations derived from modified HL gravity. 相似文献
967.
Deok‐Yong Cho Hyung‐Suk Jung Il‐Hyuk Yu Won Goo Park Suyeon Cho Useong Kim Se‐Jung Oh Byeong‐Gyu Park Fan‐Hsiu Chang Hong‐Ji Lin Cheol Seong Hwang 《固体物理学:研究快报》2012,6(4):181-183
The unoccupied electronic structures of 5 nm thick high permittivity (k) oxides (HfO2, ZrO2, and Al2O3) and SiO2 films on Ge substrates were examined using O K‐edge X‐ray absorption spectroscopy. Comparative studies with those on Si substrates showed contrasts in the conduction bands, which should be due to the formation of interface states. In the Al2O3 and SiO2 films, GeO2 layers are formed at the interface and they suppress in part the formation of detrimental germanate phases. In contrast, in the HfO2 and ZrO2 films, no signature of the Ge‐oxide phase is observed but some germanate phases are expected to prevail, suggesting a degradation of the gate oxide characteristics. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
968.
We consider a discrete-time single server N -policy GI/Geo/1 queueing system. The server stops servicing whenever the system becomes empty, and resumes its service as soon as the number of waiting customers in the queue reaches N. Using an embedded Markov chain and a trial solution approach, the stationary queue length distribution at arrival epochs is obtained. Furthermore, we obtain the stationary queue length distribution at arbitrary epochs by using the preceding result and a semi-Markov process. The sojourn time distribution is also presented. 相似文献
969.
Ki Won Lim Jin Yong Jun Byeong Jun Lee 《Journal of Thermal Analysis and Calorimetry》2012,109(1):487-494
The calorific value is defined as the amount of heat which would be released by the complete combustion in air, in such a way that the pressure remains constant, all the combustion products except water are gaseous states and all the products returned to the temperature of the reactants. Recently, the mixed fuel like LPG, LNG, hythane, etc., become more popular. But the composition of these fuels changes with time and place where it was produced, which give direct impacts on the calorific value and performance of the heating apparatus. Therefore, the accurate measurements of the calorific value become an issue in the refinery industries and the national standardization fields. So, flame calorimeter was manufactured and characterized to measure calorific value of the gaseous fuel in the flow situations. Electric substitution method initiated by Alexandrov was adopted. Peltier elements were used to emit the heat supplied by a heater and a flame to the cooling water. Freon-11 was used as a heat carrier. To get the accurate calorific value by the experiments conducting in the normal laboratory conditions, correction methods were proposed to count variations in the experimental conditions such as temperatures, electric powers, etc. It was found out that the corrected calorific value of pure methane had 0.36% relative deviation to the standard value. 相似文献
970.
Xiao L Ha JW Wei L Wang G Fang N 《Angewandte Chemie (International ed. in English)》2012,51(31):7734-7738
Keeping track: By combining differential interference contrast (DIC) image pattern recognition with DIC polarization anisotropy, the exact full three-dimensional angular information of individual tilted gold nanorods positioned in the focal plane of the objective lens can be readily determined. The angular rotational modes and kinetics of individual in-focus gold nanorods can thus be resolved dynamically. 相似文献