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31.
Hong SH Hong B- Kim DC Rho MS Park JI Rha SH Jun HS Jeong JS 《Experimental & molecular medicine》2004,36(5):493-498
Hydroxyurea is commonly used to treat hematologic disorders and some type of solid tumors, but the mechanism for its therapeutic effect is not clearly known. In this study, we examined the effect of hydroxyurea on rat hepatoma McA-RH7777 cells, specifically, on the role of mitogen-activated protein (MAP) kinase signal transduction pathways and p21(Waf1), p27(Kip1) and p53. Rat hepatoma McA-RH7777 cells treated with hydroxyurea for 7 days, caused the inhibition of cell growth in a dose-dependent manner. But, this growth inhibition was not caused by necrosis or apoptosis but instead was associated with cell senescence-like change as evidenced by senescence associated-beta-galactosidase staining, and cells arrest at G1 phase of cell cycle. Phosphorylation of MAP kinases, such as ERK, JNK, and p38, was found to be decreased after treatment of cells with hydroxyurea. But, the expression of p21(Waf1) was increased, while p27(Kip1) and p53 were not detected in hydroxyurea treated rat hepatoma cells. Hydroxyurea treatment induced G1 arrest and a senescence-like changes in rat hepatoma McA-RH7777 cells may be the likely results of signal disruption of MAP kinases (ERK, JNK, and p38 MAP kinase) and p21(Waf1) over-expression. 相似文献
32.
Surface properties of fluorinated single-walled carbon nanotubes 总被引:1,自引:0,他引:1
Young Seak Lee Tae Hyun Cho Byoung Ky Lee Jae Seong Rho Kay Hyeok An Young Hee Lee 《Journal of fluorine chemistry》2003,120(2):99-104
Single-walled carbon nanotubes (SWCNTs) were fluorinated at several different temperatures. The change of atomic and electronic structures of fluorinated SWCNTs was investigated using X-ray photoelectron spectroscopy (XPS), electrical resistivity measurements and transmission electron microscopy (TEM). The amount of doped fluorine increases with increasing doping temperature, and the fluorine atoms are covalently attached to the side-wall of the SWCNTs. From Raman spectra and HRTEM study, the strong fluorination on the SWCNTs leads to the breaking of carbon–carbon bonds and the disintegration of tube structure. Several intermediate phases of fluorinated SWCNTs are observed during e-beam irradiation in HRTEM. 相似文献
33.
34.
We construct a new effective field theory approach to the equation of state(EoS), dubbed pseudo-confomal model "PCM", for nuclear and compact star matter entirely in terms of effective hadron degrees of freedom. The possible transition at n ~(2-4)n_0(where n_0 is the normal nuclear matter density) from hadron degrees of freedom to strongly-coupled quark degrees of freedom,giving rise to a soft-to-hard changeover in the EoS that can accommodate the massive stars observed, is effectuated by the topology change at n_(1/2)~ 2n_0 from skyrmions to half-skyrmions without involving local order-parameter fields. The mechanism exploits possible emergence of hidden scale and local symmetries of QCD at high density, leading to a precocious "pseudo-conformal"sound velocity v_s~2= 1/3(in unit of c = 1) for n~ 3n_0. The resulting prediction signals a drastic departure from standard nuclear many-body theory in the density regime involved in the massive stars. We suggest that the tidal deformability implemented in gravitational waves coming from coalescing neutron stars in LIGO/Virgo-type observations could pin down the location of the topology change density n_(1/2). 相似文献
35.
Kang Jung Ae Rho Jong Kook Park Sang Hyun 《Journal of Radioanalytical and Nuclear Chemistry》2019,319(3):1103-1110
Journal of Radioanalytical and Nuclear Chemistry - In this study, a radioisotope (RI) detection-assisted biochip was developed for the evaluation of the inhibitory effects of natural products on... 相似文献
36.
We report polarized and resonant Raman study of InAs/GaAs quantum dot solar cell (QDSC) structures. Raman spectra obtained from the top surfaces of the samples suggested that the formation of InAs QDs induced tensile strain in the overgrown GaAs layers. Furthermore, a longitudinal optical phonon-plasmon (LPP) coupled modes were observed in the p-type GaAs layers. The tensile strain was increased with an increase in the QD size. The hole concentrations estimated by fitting the individual LPP coupled modes were in the range of 2.4–3.5 × 1018 cm?3. Resonant Raman spectra obtained from the cleaved sides, where the QDs were located, showed a 225 cm?1 mode in parallel polarization configurations. Based on accurate analysis, this mode was identified as the LA(X) phonon of GaAs. 相似文献
37.
Faisal SN Pereira CM Rho S Lee HJ 《Physical chemistry chemical physics : PCCP》2010,12(46):15184-15189
A new cost-effective amperometric proton selective sensor utilizing a single microhole interface between two immiscible electrolyte solutions (ITIES) is developed. The sensing methodology is based on measuring currents associated with proton transfer across the interface assisted by a proton selective ionophore. The ellipse shaped micro-interface was first fabricated by simple mechanical punching with a sharp needle on a thin PVC film (12 μm thick) commercially available as a food wrapping material. The microhole was then filled up with a gellified polyvinylchloride (PVC)-2-nitrophenyloctylether (NPOE) to create a single microhole liquid/liquid interface. Direct ion transfer reactions across the polarized interface serving as ion sensing platforms were studied using cyclic voltammetry. In order to enhance the selectivity of proton sensing, a proton selective ionophore, octadecyl isonicotinate (ETH1778), was incorporated into the organic gel layer and their electrochemical sensing characteristics were investigated using cyclic voltammetry and differential pulse stripping voltammetry. As an example, we employed the proton selective sensor for the determination of glucose concentrations. The detection scheme involves two steps: (i) protons are first generated by the oxidation of glucose with glucose oxidase in the aqueous phase; and (ii) the current associated with the proton transfer across the interface is then measured for correlating the concentration of glucose. 相似文献
38.
Treatment of α,β-dihydroxy ketones with carbonyldiimidazole resulted in the formation of α-diketones based on the elimination of the cyclic carbonates formed in situ. 相似文献
39.
Yang JY Koo BS Kang MK Rho HW Sohn HS Jhee EC Park JW 《Experimental & molecular medicine》2002,34(5):353-360
The present study was undertaken to explore whether retinoids, which are known to have immunomodulatory actions, could attenuate tumor necrosis factor-alpha (TNF)-stimulated inducible nitric oxide synthase (iNOS) expression in 3T3-L1 adipocytes. Adipocytes incubated with TNF induced dose- and time-dependent accumulation of nitrite in the culture medium through the iNOS induction as confirmed by Western blotting. Treatment of cells with TNF in the presence of all-trans-retinoic acid (RA) significantly decreased their ability to produce nitrite and iNOS induction. Both 13-cis- and all- trans-RA-induced suppression was dose-dependent, and all-trans-RA was somewhat potent than 13-cis-RA. The inhibitory effect of RA on TNF-induced iNOS induction was reversible, completely recovered after 2 days, and was exerted through the inhibition of NF-kappaB activation. TNF also suppressed the lipoprotein lipase (LPL) activity of 3T3-L1 adipocytes. RA could not reverse the TNF- induced LPL suppression at RA levels causing near complete inhibition of the TNF-induced NO production. These results indicate that RAs attenuate iNOS expression reversibly in TNF-stimulated 3T3-L1 adipocytes, and that the TNF-induced LPL suppression is not the result of NO overproduction. 相似文献
40.
It is suggested that muon absorption and doubly radiative pion absorption in nuclei can complement each other in probing the pion field in the nuclear medium. The relevant issues we consider are possible pion condensation and nuclear “renormalization” of weak and electromagnetic vertices, the adequate understanding of which is necessary to extract from nuclear experiments useful information on basic form factors in the weak Hamiltonian. 相似文献