• 대한한의학회지
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• 제30권2호
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• pp.88-103
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• 2009

Objectives: There is currently increased interest in the identification of natural antioxidant compounds derived from various plants. Peony Root (PR) is used worldwide for the treatment of many types of cardiovascular disease including atherosclerosis and hypertension. It has been used in Korean traditional medicine for the treatment of glycosuria, hypertension and cancer. However, to date, no studies concerning the antioxidant properties of PR have been conducted. Therefore, this study was conducted to evaluate the in vitro scavenging activity, inhibitory effect of LDL oxidation of pro-oxidant reactive species and anti-thrombosis effect in response to treatment with PR using various screening methods including biological and non-biological oxidants. Methods: In this study, the antioxidant activity of extract from PR was studied with in vitro methods by measuring the antioxidant activity by TEAC, measuring the scavenging effects on reactive oxygen species (ROS) [superoxide anion, hydroxyl radical] and on reactive nitrogen species (RNS) [nitric oxide and peroxynitrite] as well as measuring the inhibitory effect on $Cu^{2+}$-induced human LDL oxidation and the inhibitory effect on collagen-induced platelet aggregation. Results: The PR extracts were found to have a potent scavenging activity of oxidative stress [DPPH, superoxide anion, hydroxyl radical, nitric oxide and peroxynitrite, etc.] as well as an inhibitory effect on LDL oxidation and on platelet aggregation. Conclusions: The PR extracts have anti-oxidative and anti-atherosclerotic effects in vitro system, which can be used for developing pharmaceutical drugs against oxidative stress and atherosclerosis.

• 한국자기공명학회논문지
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• 제19권3호
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• pp.99-105
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• 2015

Hsp33 is a prokaryotic molecular chaperon that exerts a holdase activity upon response to an oxidative stress at raised temperature. In particular, intramolecular disulfide bond formation between the four conserved cysteines that bind a zinc ion in reduced state is known to be critically associated with the redox sensing. Here we report the backbone NMR assignment results of the half-oxidized Hsp33, where only two of the four cysteines form an intramolecular disulfide bond. Almost all of the resolved peaks could be unambiguously assigned, although the total assignments extent reached just about 50%. Majority of the missing assignments could be attributed to a significant spectral collapse, largely due to the oxidation-induced unfolding of the C-terminal redox-switch domain. These results support two previous suggestions: conformational change in the first oxidation step is localized mainly in the C-terminal zinc-binding domain, and the half-oxidized form would be still inactive. However, some additional regions appeared to be potentially changed from the reduced state, which suggest that the half-oxidized conformation would be an intermediate state that is more labile to heat and/or further oxidation.

• 동의생리병리학회지
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• 제23권3호
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• pp.631-638
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• 2009

GLEDITSIAE SPINA (GS) has been used as folk remedies traditionally for treatment of antiphlogistic and antifebrile agents. An ethanol extract and its fraction of GS were assessed to determine the mechanism of its antioxidant activity. Also, inhibitory effect of extract from GS and its fraction measuring the inhibitory effect on $Cu^{2+}$-induced human low-density lipoprotein (LDL) oxidation. GS ethanol extract and its fraction exhibited a concentration-dependent reactive oxygen species (ROS) and reactive nitrogen species (RNS) scavenging activities, including trolox equivalent antioxidant capacity (TEAC), OPPH radical, superoxide anion, hydroxyl radicals, peroxynitrite and nitric oxide, using different assay systems. Furthermore, the GS ethanol extract and its fraction showed dose-dependent protection of LDL oxidation induced by $CuSO_4$. In addition, the GS ethanol extract and its fraction were characterized as containing a high amount of total phenolics. These results suggest that GS ethanol extract and its fraction might be helpful for preventing oxidative stress and protecting LDL oxidation.

• 대한한의학회지
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• 제25권2호
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• pp.194-206
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• 2004

Objectives : JiaoTeng-Yuan(교등원) is said to be a prescription for preservation of health in $\ulcorner$HuaTuo.ZhongZangJing (화타.중장경)$\lrcorner$. It is known to have the effect of Bu-Shen (보신: strengthening kidney) and Yi-Shou (익수: prolonging the span of one's life). This study investigates whether JTY is effective on inhibition of oxidation stress. Methods : Sprague-Dawley rats (12-week-old, weight $300{\pm}20g$) were divided into 3 groups. The normal group (n=8) was injected with PBS (1ml/body, s.c) subcutaneously behind the neck. The control group (n=8) was injected with D-galactose (50mg/kg, 1ml PBS/body, s.c) to induce pathological animals. The JTY group was injected with the same treatment as the control group, and fed containing JTY (10%). All groups were treated 1 time per day for 6 weeks. After the rats were sacrificed anti-oxidant enzyme (SOD, CAT, G-px) activity, GSH quantity of RBC and tissue (heart, liver and kidney), and plasma Vit-C quantity were examined. Also, the MDA levels of liver and kidney, lipofuscin of heart and endurance of erythrocyte membrane were measured. Results : In the JTY group, RBC's SOD activity decline was halted by 21 % of the normal level, compared to the control group, G-px activity (unit/g of Hb) increased significantly, compared to the normal group, and the level of Vit-C in plasma increased by 16%. Heart's SOD activity was kept at the same level as that of the normal group; and CAT activity decline was halted by 26%. Kidney's CAT and G-px activities were kept at the same level as that shown in the normal group, implying the existence of a halting effect. Liver also showed a slight halting effect against the decline of anti-oxidant ability, but the effect was not significant (${\alpha}=0.05$). A comparison between the levels of peroxide in SD rats showed that the level of TBARS in plasma increased significantly in the control group and that it was normal in the JTY group. The livers in the JTY group, compared to those in the control group, showed 36% halting effect of the normal level while their kidney's indicated the level significantly lower than the normal level. Heart's lipofuscin increased significantly in the control group, but was alike in both the JTY and the normal groups. Endurance of erythrocyte membrane (%) decreased significantly in the control group while it was kept at the similar level in both the JTY and the normal groups, indicating the halting effect. Conclusions : This study suggests that JTY is effective to defend oxidation stress caused by D-galactose in the animals. It showed that the anti-oxidant ability was maintained and strengthened. On the other hand, it reduced the level of peroxide in animals. In sum, JTY appeared to have the equilibrium normal physiological function in SD rat.

• 한국세라믹학회지
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• 제34권5호
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• pp.535-543
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• 1997

The surface of SiC particles were partially oxidized to produce SiO2 layers on the SiC particles to prepare Al2O3/SiC composite by formation of mullite bonds between the grains of Al2O3 and SiC during sintering at 1$600^{\circ}C$. This process is considered to enable the sintering of Al2O3/SiC composite at lower temperature and also to relieve the stress, produced by thermal expansion mismatch between Al2O3 and SiC. In fact, Al2O3/SiC composite prepared by oxidation of SiC was observed to be more effectively sintered and densified at lower temperature. Maximum density, flexural strength and microhardness were obtained with 5.65 vol% of mullite content in Al2O3/SiC composite.

• 전자공학회논문지A
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• 제32A권8호
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• pp.107-118
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• 1995

Three-dimensional simulator for thermal oxidation process is developed. The simulator is consisted by two individual module, one is analytic-model module and the other is numerical-model module. The analytic-model which uses simple complementary-error function guarantees fast calculation in prediction of multi-dimensional oxidation process. The numerical-model which is based on boundary element method (BEM), has a good accuracy and suitable for various process conditions. The results of this study show that oxide growth is retarded at the corner of hole structure and enhanced at the corner of island structure. These effects are reson of different distribution of oxidant diffusion and mask stress. The utility of models and simulator developed in this study is demonstrated by using it to predict not only traditional shape of LOCOS but also process effects in small geometry.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.188-191
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• 2003

In this wort. the effect of anodic oxidation on surface characteristics of high strength PAN-based carbon fibers is investigated in terms of surface and mechanical interfacial properties of the composites. As a result, the acidity of carbon fiber surfaces is increased, due to the development of oxygen functional groups in the presence of anodic oxidation. Also. it is found that the critical stress intensity factor ($K_{IC}$) is improved in the oxidized fibers-reinforced composites. which can be attributed to the good wettability between fibers and epoxy resin matrix.

• 동의생리병리학회지
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• 제25권2호
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• pp.280-293
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• 2011

There is currently increased interest in the identification of antioxidant compounds that are pharmacologically potent and have low or no side effects. Plants produce significant amounts of antioxidants to prevent the oxidative stress caused by photons and oxygen, therefore they represent a potential source of new compounds with antioxidant activity. FARFARE FLOS has been frequently used on the respiratory system including bronchitis, phthisis. In this study, the antioxidant activity of extract from FF was studied in vitro methods by measuring the antioxidant activity by TEAC, measuring the scavenging effects on reactive oxygen species (ROS) [superoxide anion, hydroxyl radical] and on reactive nitrogen species (RNS) [nitric oxide and peroxynitrite] as well as measuring the inhibitory effect on Cu2+-induced human LDL oxidation. The FF extracts were found to have a potent scavenging activity, as well as an inhibitory effect on LDL oxidation. And this study was designed to evaluate whether FFEA may ameliorate oxidative stress and inflammatory status through the antioxidative mechanism in LPS-stimulated RAW 264.7 murine macrophage cell line. Treatment of RAW 264.7 cells with FFEA significantly reduced LPS-stimulated inflammatory response in a dose-dependent manner. In conclusion, the FF extracts have anti-oxidative and anti-inflammatory effects in vitro system, which can be used for developing pharmaceutical drug against oxidative stress and atherosclerosis.

• Animal Bioscience
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• 제35권1호
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• pp.22-28
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• 2022

Objective: Endoplasmic reticulum (ER) stress engages the unfolded protein response (UPR) that serves as an important mechanism for modulating hepatic fatty acid oxidation and lipogenesis. Chronic fasting in mice induced the UPR activation to regulate lipid metabolism. However, there is no direct evidence of whether negative energy balance (NEB) induces ER stress in the liver of cows. This study aimed to elucidate the relationship between the NEB attributed to feed deprivation and ER stress in bovine hepatocytes. Methods: Blood samples and liver biopsy tissues were collected from 6 non-lactating cows before and after their starvation for 48 h. The blood non-esterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA) and glucose level were analyzed. Real-time quantitative polymerase chain reaction and Western blotting were used to explore the regulation of genes associated with UPR and lipid metabolism. Results: The starvation increased the plasma BHBA and NEFA levels and decreased the glucose level. Additionally, the starvation caused significant increases in the mRNA expression level of spliced X-box binding protein 1 (XBP1s) and the protein level of phosphorylated inositol-requiring kinase 1 alpha (p-IRE1α; an upstream protein of XBP1) in the liver. The mRNA expression levels of peroxisome proliferator-activated receptor alpha and its target fatty acid oxidation- and ketogenesis-related genes were significantly upregulated by the starvation-mediated NEB. Furthermore, we found that the mRNA expression levels of lipogenic genes were not significantly changed after starvation. Conclusion: These findings suggest that in the initial stage of NEB in dairy cows, the liver coordinates an adaptive response by activating the IRE1 arm of the UPR to enhance ketogenesis, thereby avoiding a fatty liver status.

• Corrosion Science and Technology
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• 제21권6호
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• pp.466-475
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• 2022

Surface oxides and intergranular (IG) oxidation phenomena in Alloy 600 depending on hydrogen concentration were characterized to obtain clear insight into the primary water stress corrosion cracking (PWSCC) behavior upon exposure to pressurized water reactor primary water. When hydrogen concentration was between 5 and 30 cm³ H₂/kg H₂O, NiFe₂O₄ and NiO type oxides were found on the surface. NiO type oxides were found inside the oxidized grain boundary when hydrogen concentration was 5 cm³ H₂/kg H₂O. However, only NiFe₂O₄ spinel on the surface and Ni enrichment were observed when hydrogen concentration was 30 cm³ H₂/kg H₂O. These results indicate that the oxidation/reduction reaction of Ni in Alloy 600 depending on hydrogen concentration can considerably affect surface oxidation behavior. It appears that the formation of NiO type oxides in a Ni oxidation state and Ni enrichment in a Ni reduction (or metallic) state are common in primary water. It is believed that the above different oxidation/reduction reactions of Ni in Alloy 600 depending on hydrogen concentration can also significantly affect the resistance to PWSCC of Alloy 600.