• Biomedical Science Letters
• /
• v.24 no.1
• /
• pp.50-54
• /
• 2018

N-nitroso-N-methylurea (NMU) and N-nitroso-N-ethylurea (NEU), direct alkylating chemical mutagens and carcinogens, are shown to be the upregulators of cellular $NF-{\kappa}B$, regulating various genes that mediate tumorigenesis and carcinogenesis. Nitric oxide (NO), a toxic reactive radical gas, has been known to induce programmed cell death or apoptosis in various cells. Therefore, the assessment of NO production was examined to elucidate the possible contribution of NO release to the chemical carcinogenic potency of NMU and NEU in human skin cells. NMU and NEU did not alter the NO production, but they caused a significant downregulation of the NO generation on lipopolysaccharide (LPS)-induced NO production at concentrations ranging from $2{\sim}5{\mu}M$. The degree of downregulation of NO by NMU and NEU decreased up to 15% and 20%, respectively, compared to the control. These results demonstrate that the LPS-inducible keratinocytes NO synthase is involved in modulating carcinogenic potency by NMU and NEU, and the regulation of the cellular $NF-{\kappa}B$ activity by NMU and NEU is negatively correlated with the level of LPS-induced NO production in human skin cells. The findings of this study suggest the hypothesis that NMU and NEU-induced carcinogenesis may be associated with the downregulation of NO production, and the inducible NO may play an important role in NMU and NEU-induced carcinogenicity in human epidermal keratinocytes.

• BMB Reports
• /
• v.39 no.6
• /
• pp.759-765
• /
• 2006

In this study, we investigate Nitric oxide synthase (NOS) expressions in adriamycin (ADR)-induced cadiomyopathy in rats. Sixty male Wistar rats were randomly divided into two main groups: control and ADR groups. Myocardial histopathological observation was performed; Expressions of 3 isoforms of NOS genes were examined by RT-PCR analysis; Expressions of 3 isoforms of NOS protein was assessed by Western blot analysis. Myocardium exhibited intensive morphological changes after 8 weeks of ADR treatment. The expression levels of inducible NOS (iNOS) gene and protein were significantly increased in ADR-treated rats after 8 weeks of treatment and then slightly increased at weeks 9 and 10. No significantly difference of neuronal NOS (nNOS) or endothelial NOS (eNOS) gene and protein were observed in the myocardium obtained from the control rats and ADR-injected rats at any time point. iNOS gene expression is selectively induced by ADR in heart. The upregulation of iNOS gene and protein may be somehow correlated with morphological changes seen in heart of rat treated with ADR.

• Applied Science and Convergence Technology
• /
• v.23 no.6
• /
• pp.317-327
• /
• 2014

In order to develop nano-devices with much lower power consumption for beyond-CMOS applications, the fundamental understanding and precise control of the electronic properties of ultrathin transition metal oxide (TMO) films are strongly required. The metal-insulator transition (MIT) is not only an important issue in solid state physics, but also a useful phenomenon for device applications like switching or memory devices. For potential use in such application, the electronic structures of MIT, observed for TMO nano-structures, have been investigated using a synchrotron radiation angle-resolved photoelectron spectroscopy system combined with a laser molecular beam epitaxy chamber and a scanning photoelectron microscopy system with 70 nm spatial resolution. In this review article, electronic structures revealed by soft X-ray nano-spectroscopy are presented for i) polarity-dependent MIT and thickness-dependent MIT of TMO ultrathin films of $LaAlO_3/SrTiO_3$ and $SrVO_3/SrTiO_3$, respectively, and ii) electric field-induced MIT of TMO nano-structures showing resistance switching behaviors due to interfacial redox reactions and/or filamentary path formation. These electronic structures have been successfully correlated with the electrical properties of nano-structured films and nano-devices.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.42 no.5
• /
• pp.62-66
• /
• 2010

Cellulosic materials were dissolved by NMMO(N-methylmorpholine-N-oxide) and CED (Cupriethylene diamine), respectively, to measure their DPs (degrees of polymerization) by using viscometer. We changed cellulose DPs by applying various amounts of low intensity electron-beam radiation to the cellulosic materials. NMMO is environmental-friendly, non-toxic, and biodegradable organic cellulose solvent and used industrially because of its high cellulose dissolving power and high solvent recovery ratio. The cellulose DP measurement results using these two different chemicals were correlated highly ($R^2$ >0.95). It was also found that cellulose with high DP was dissolved more easily in NMMO than CED. In addition, NMMO method gave more higher resolution in the measurement.

• Nutritional Sciences
• /
• v.7 no.4
• /
• pp.214-217
• /
• 2004

Dietary intervention and simvastatin is beneficial in the prevention cardiovascular diseases by lowering plasma lipid levels. Endothelial dysfunction is associated with coronary artery disease and its risk factors and is reversed by dietary intervention. It has been suggested that hyperlipidemia contributes to the development of atherosclerosis by increasing inducible nitric oxide synthase (iNOS) expression via intimal thickening. Statins treatment has been found to decrease iNOS expression and atherogenensis in animal models. We hypothesized that dietary intervention and simvastatin therapy could decrease plasma nitric oxide in hypercholesterolemic patients, which would suggest the opportunity for modulation of iNOS expression through the use of statins in a clinical situation. We measured the plasma levels of nitrite and nitrate (NOx) in 19 hyperlipidemia patients. The subjects were under dietary intervention following simvastatin therapy for 12 weeks. As a result, the plasma level of NOx, stable metabolites of nitric oxide (NO), saw a two-fold elevation in hyperlipidemic patients as compared to normal levels. Although 12 weeks of dietary intervention did not lower NOx levels, subsequent 12-week simvastatin (10 mg/day) treatment, along with dietary intervention, lowered NOx levels significantly. This NOx reduction, induced by simvastatin therapy, positively correlated with lowered coronary risk factors (r=0.40, p=0.02). It indicated that simvastatin therapy decreases plasma NOx levels by, perhaps, decreasing iNOS expression or activity leading to the attenuation of the development of neointima.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.12
• /
• pp.1881-1888
• /
• 2004

A series of $NiO-TiO_2$/$WO_3$ catalysts was prepared by drying powdered $Ni(OH)_2-Ti(OH)_4$ with ammonium metatungstate aqueous solution, followed by calcining in air at high temperature. Characterization of prepared catalysts was performed by using FTIR, Raman, XPS, XRD, and DSC and by measuring surface area. Upon the addition of tungsten oxide to titania up to 25 wt%, the specific surface area and acidity of catalysts increased in proportion to the tungsten oxide content due to the interaction between tungsten oxide and titania. Since the -$TiO_2$/stabilizes the tungsten oxide species, for the samples equal to or less than 25 wt%, tungsten oxide was well dispersed on the surface of titania, but for the samples containing above 25 wt%, the triclinic phase of $WO_3$ was observed at calcination temperature above 400 $^{\circ}C$. The catalytic activities of 10-NiO-$TiO_2$/$WO_3$ for 2-propanol dehydration and cumene dealkylation were correlated with the acidity of catalysts measured by ammonia chemisorption method. NiO may attract reactants and enhance the local concentration of reactants near the acid sites, consequently showing the increased catalytic activities.

• Journal of Powder Materials
• /
• v.4 no.1
• /
• pp.48-54
• /
• 1997

NiAl powders containing oxide dispersoids have been produced by mechanical alloying process in a controlled atmosphere using high energy attrition mill. The powders have been consolidated by hot extrusion and hot pressing followed by isothermal annealing to induce microstructure coarsening to improve high temperature properties. Grain growth and dispersoid coarsening kinetics have been investigated as functions of annealing time and temperature. Coarsening of dispersion strengthen NiAl and dispersoid has been discussed. Some clues of secondary recrystallization have been investigated. Mechanical property measurements have been also made and correlated with the microstructures.

• Proceedings of the Korean Society of Toxicology Conference
• /
• 2002.11b
• /
• pp.155-155
• /
• 2002

Several epidemiological studies have suggested that exposure to arsenic is strongly correlated with the development of cardiovascular diseases such as hypertension. To determine whether arsenic affects vasomotor tone in blood vessels, we investigated the effect of arsenic on vasorelaxation using isolated rat aortic rings in an organ bath system.(omitted)

• The Korean Journal of Physiology and Pharmacology
• /
• v.8 no.4
• /
• pp.213-218
• /
• 2004

Primary fish-odor syndrome (FOS) is a genetic disorder caused by defective flavin-containing mono-oxygenase 3 gene (FMO3) with deficient N-oxidation of trimethylamine (TMA), causing trimethylaminuria (TMAU). By contrast, secondary FOS can be acquired by decreased FMO activities in patients with chronic liver diseases, but the underlying mechanisms are unknown. In the present study, we examined plasma NOx concentrations and viral DNA contents as well as in vivo FMO activities and their correlations in chronic viral hepatitis (CVH) patients. Plasma concentration of NOx was significantly increased by 2.1 fold $(56.2{\pm}26.5\;vs.\;26.6{\pm}5.4\;{\mu}M,\;p<0.01)$, and it was positively correlated with plasma hepatitis B virus (HBV) DNA contents $(r^2=0.2838,\;p=0.0107)$. Furthermore, the elevated plasma NOx values were inversely and significantly correlated with in vivo FMO activities detected by ranitidine-challenged test $(8.3%\;vs.\;20.0%,\;r^2=0.2109,\;p=\0.0315)$. TMA N-oxidation activities determined in CVH patients without challenge test were also significantly low (73.6% vs. 95.7%, p< 0.05). In conclusion, these results suggested that secondary FOS could be acquired by the endogenously elevated NO in patients with CVH.

• IMMUNE NETWORK
• /
• v.7 no.1
• /
• pp.31-38
• /
• 2007

Background: Mizoribine (MZR) is an imidazole nucleoside isolated from Eupenicillium brefeldianum. MZR is currendy in clinical use for patients who have undergone renal transplantation. Therapeutic efficacy of MZR has also been demonstrated in rheumatoid arthritis and lupus nephritis. MZR has been shown to inhibit the proliferation or lymphocytes by interfering with inosine monophosphate dehydrogenase. Since the exact mechanism by which MZR benefits rheumatoid arthritis (RA) is not clear, we investigated the ability of MZR to direct its immunosuppressive influences on other antigen presenting cells, such as macrophages. Methods: Mouse macrophage RAW264.7 cells were stimulated with lipopolysaccharide in the presence of MZR. To elucidate the mechanism of the therapeutic efficacy in chronic inflammatory diseases, we examined the effects of MZR on the production of pro-inflammatory cytokines, nitric oxide (NO) and prostaglandin $E_2\;(PGE_2)$ in macrophages. Results: MZR dose-dependendy decreased the production of nitric oxide and pro- inflammatory cytokines such as tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukins $1{\beta}$ (IL-${\beta}$ and IL-6 $PGE_2$. Examination of gene expression levels showed that the anti-inflammatory effect correlated with the down-regulation of inducible nitiric oxide synthase expression, cycloxygenase-2 expression and TNF-${\alpha}$ gene expression. Conclusion: In this work, we resulted whether MZR $(1.25{\sim}10{\mu}g/ml)$ inhibited macrophage activation by inhibiting secretion of pro-inflammatory cytokines, NO and $PGE_2$. These findings provide an explanation for the therapeutic efficacy of MZR in chronic inflammation-associated diseases.