• Journal of Nutrition and Health
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• v.42 no.2
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• pp.107-118
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• 2009

In patients with type 2 diabetes, oxidative stress could be increased by their metabolic changes. Elevated plasma homocysteine is considered as one of markers of enhanced oxidative stress. Due to oxidative stress, some complications like cardiovascular or renal diseases may develop in type 2 diabetes patients. Plasma homocysteine concentration may be increased if folate status were inadequate. Protective effects against oxidative stress may be diminished if the status of anti-oxidative nutrient as vitamin C was poor. It is, therefore, important to maintain adequate status of folate and vitamin C in type 2 diabetes patients. Thus, this study was performed to determine the effects of supplementation of folate and/or ascorbate on blood glycated hemoglobin ($HbA_{1c}$) level, serum concentrations of homocysteine and cholesterol, plasma oxidized low density-lipoprotein (LDL), concentration and plasma glutathione peroxidase (GSH-Px) activity in the patients with type 2 diabetes. A total of 92 type 2 diabetes patients participated voluntarily with written consents. They were divided into one of the four experimental groups; Control (C), Folate-supplemented (F), Ascorbate-supplemented (A), and Folate plus ascorbate-supplemented (FA). The subjects in C were taken placebo, those in F were supplemented 1 mg of folate, those in A received 1,000 mg of ascorbate, and those in FA were given 1 mg of folate plus 1,000 mg of ascorbate daily for 4 weeks. Supplementation of folate or ascorbate resulted to increase serum folate level or plasma ascorbate concentration apparently, respectively. Folate supplementation not ascorbate seemed to decrease plasma concentrations of homocysteine and oxidized LDL and reduce plasma GSH-Px activity. There might not be synergic effect of the supplementation of folate plus ascorbate. The results indicate that oxidative stress in the patients with type 2 diabetes may lower mainly by folate supplementation.

• Steel and Composite Structures
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• v.18 no.6
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• pp.1465-1478
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• 2015

The effect of cutting off fibers on transient load in a polymeric matrix composite lamina was studied in this paper. The behavior of fibers was considered to be linear elastic and the matrix behavior was considered to be linear viscoelastic. To model the viscoelastic behavior of matrix, a three parameter solid model was employed. To conduct this research, finite difference method was used. The governing equations were obtained using Shear-lag theory and were solved using boundary and initial conditions before and after the development of break. Using finite difference method, the governing integro-differential equations were developed and normal stress in the fibers is obtained. Particular attention is paid the dynamic overshoot resulting when the fibers are suddenly broken. Results show that considering viscoelastic properties of matrix causes a decrease in dynamic load concentration factor and an increase in static load concentration factor. Also with increases the number of broken fibers, trend of increasing load concentration factor decreases gradually. Furthermore, the overshoot of load in fibers adjacent to the break in a polymeric matrix with high transient time is lower than a matrix with lower transient time, but the load concentration factor in the matrix with high transient time is lower.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.95-101
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• 2002

To investigate the changes in the composition and pool size of nitrogen metabolites under drought stress, white clover (Trifolium repens L.) were exposed to -0.04MPa (well-watered, control) or to -0.12MPa (drought-stressed) of soil water potential during 28 days. Dry weight of leaves in drought-stressed plants was remarkably decreased by 45% and 74% within 14 days and 28 days, respectively, compared with control. For nitrate concentration after 28 days of treatment, a significant difference (1.6 times higher in drought-stressed plants) was observed only in stolon. NH$_3$-NH$_4$$^{+}$ concentration in all three organs of drought-stressed plants linearly increased to more than 1.6 times higher level at 28 day when compared to the initial level (day 0), while the increasing rate in control was much less than that of drought-stressed plants. Proline concentrations in drought-stressed plants remarkably increased and reached to 7, 13 and 17 times higher level at 28 day compared to control. Protein concentration in leaves of drought-stressed plants tended to decrease, while it slightly increased during the first 14 days and reached a plateau afterward in control. There was not significant difference in the proteins concentration of stolon and roots throughout experimental period. On SDS-PAGE analysis, two major proteins specifically induced by drought stress (16-kD and 18-kD) were detected in stolon.n.

• Archives of Pharmacal Research
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• v.23 no.5
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• pp.495-500
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• 2000

We investigated whether S-adenosylmethionine (SAM) treatment improved ischemic injury using perfused rat liver after sequential periods of 24 h cold and 20 min re-warming ischemia. SAM (100 $\mu\textrm{mol/L}$) was added to University of Wisconsin (UW) solution and Ringers lactate solution. After cold and sequential warm ischemia, releases of lactate dehydrogenase (LDH) and purine nucleoside phosphorylase (PNP) markedly increased during repefusion. The increase in PNP was significantly reduced by SAM treatment. While the concentration of reduced glutathione (GSH) in ischemic livers significantly decreased, the concentration of glutathione disulfide (GSSG) increased. This decrease in GSH and increase in GSSG were suppressed by SAM treatment. Lipid peroxidation was elevated in cold and warm ischemic and reperfused livers, but this elevation was also prevented by SAM treatment. Hepatic ATP levels were decreased in the ischemic and reperfused livers to 42% of the control levels. However, treatment with SAM resulted in significantly higher ATP levels and preserved the concentration of AMP in ischemic livers. Our findings suggest that SAM prevents oxidative stress and lipid peroxidation and helps preserve hepatic energy metabolism.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.617-628
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• 2000

In this study, the 4-point bending test has been performed in order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strength of as-welded specimens has been satisfied the grade of fatigue strength prescribed in specifications of domestics and AASHTO & JSSC, and fatigue strength at $2{\times}106cycles$ of TIG-dressing specimens has been increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks have been occurred at several points, where the radius of curvature and flank angle in the weld bead toes are low, and grown as semi-elliptical cracks, then approached to fracture. As a result of finite element analysis, stress concentration factor in weld bead toes has been closely related to the flank angel and radius of curvature, and between these, the radius of curvature has more largely affected in stress concentration factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has been largely affected on stress gradient correction factor in case a/t is below 0.4. From the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.5
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• pp.583-596
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• 2004

Statement of problem : Stress concentration on the neck bone affects the bone resorption, and finally the implant survival. Purpose: In order to examine the stress distribution on the neck bone and prosthesis abutment for implants, decreasing abutment sizes were used. Material and methods : Axisymmetric models were used to obtain the data required. These models were composed of 4mm implants with 3.4mm and 4mm abutments, 5mm implants with 3.4mm and 5mm abutments and 6mm implants with 3.4mm and 6mm abutments. All abutments were designed to received a 10mm high by 10mm diameter gold crown. Functional element analysis was used to obtain these results using data that consisted of 50 N vertical and 45 degree inclination forces. Results : 1. Changing the diameter of the abutment on the implant affects the effect of the inclination forces more than the effect of the vortical forces. 2. Changing the diameter of the abutment on the implant affect the effect of the inclination forces more than the effect of the vertical forces. 3. Experimentation showed that the larger diameter implants provided a decreased neck bone stress, whereas a larger diameter abutment provided a decrease marginal abutment stress. 4. Experimentation showed that the neck bone and abutment received more stress from inclination forces than vertical forces, Conclusions: By decreasing the size of the abutment on the implant we were able to diminishneck bone stress.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.867-874
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• 2021

Epalrestat (EPS) is a brain penetrant aldose reductase inhibitor, an approved drug currently used for the treatment of diabetic neuropathy. At near-plasma concentration, EPS induces glutathione biosynthesis, which in turn reduces oxidative stress in the neuronal cells. In this study, we found that EPS reduces neurodegeneration by inhibiting reactive oxygen species (ROS)-induced oxidative injury, mitochondrial membrane damage, apoptosis and tauopathy. EPS treatment up to 50 µM did not show any toxic effect on SH-SY5Y cell line (neuroblastoma cells). However, we observed toxic effect at a concentration of 100 µM and above. At 50 µM concentration, EPS showed better antioxidant activity against H₂O₂ (100 µM)-induced cytotoxicity, ROS formation and mitochondrial membrane damage in retinoic acid-differentiated SH-SY5Y cell line. Furthermore, our study revealed that 50 µM of EPS concentration reduced the glycogen synthase kinase-3 β (GSK3-β) expression and total tau protein level in H₂O₂ (100 µM)-treated cells. Findings from this study confirms the therapeutic efficacy of EPS on regulating Alzheimer's disease (AD) by regulating GSK3-β and total tau proteins phosphorylation, which helped to restore the cellular viability. This process could also reduce toxic fibrillary tangle formation and disease progression of AD. Therefore, it is our view that an optimal concentration of EPS therapy could decrease AD pathology by reducing tau phosphorylation through regulating the expression level of GSK3-β.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.1
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• pp.21-27
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• 1999

In this study, stress intensity factors KI, KII, KIII are existing at the same time to a hollow cylindrical bar of three dimension inclination crack. In order to investigate by experimentally the effect of the inclination angle $\psi$ of crack, artificial inclination cracks in the circumferential direction are put in the surface of a hollow cylindrical bar made by the epoxy-resin. Experimentally, stress analysis methods of stress intensity factors were proposed. But, suitable method are the caustic method and the photoelastic stress freezing method. The mixed mode of KI, and KII, were determined by the photoelastic method of the classical approach method and the FORTRAN language program of the used smallest square method.

• Asian Journal of Turfgrass Science
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• v.10 no.4
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• pp.315-329
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• 1996

The changes of growth and protein synthesis pattern by aluminum (Al), cadmium (Cd), zinc (Zn) treatments were studied in Cyanobacterium synechocystis sp. PCC 6803. When exposed to Al from 5ppm to 3oppm, synechocystis grows normally. But more than that retard the growth of algae notably. The 0.05ppm Cd additions had no effect on the growth of algae. 0.1, 0.2, and 0.5ppm Cd inhibited growth. Under 1 and 2ppm Cd stress, growth was greatly diminished. Zn had dual effects. The growth of algae in media containing 5ppm was stimulated. As concentration increases more than l5ppm, growth inbition increases. Under 25ppm Zn stress, growth was greatly diminished. According to logistic theory, r and K values of each heavy metal-treated groups were estimated. Correlation analysis of r and K values with metal concentration shows that there is negative correlation between K and concentration in Cd and Zn treatments. Critical concentration which shows lethal or sublethal effect was estimated by t-test of each r and K value. The cells cultured in 10, 20, 30, 40 and 5oppm of Al, 1 and 2ppm of Cd, and 10, 15, 20, 25 and 30ppm of Zn for 4 days was used for protein analysis. Analysis of protein synthesis with SDS-PACE showed alterations of protein synthesis pattern. The synthesis of protein about 220kD increased markedly. In this study, it showed that resistance mechanism against Al, Cd, and Zn is K selection and that metal stress induced the change of protein synthesis in Cyanobacterium synechocystis sp. PCC 6803.Key words:Cyanobacterium synechocystis sp. FCC 6803, Heavy metals, Aluminum, Cadmiutm Zinc, Crowth, Frotein synthesis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1220-1226
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• 2001

This study was conducted to investigate the effect of water-soluble extract from roasted chicory on the lipid metabolism and oxidative stress in male Sprague-Dawley rats. The experimental groups were divided into three groups ; the normal group, the cholesterol group and the chicory group. Roasted chicory extract was supplemented at 5.0% (w/w) level in the cholesterol diet. Concentration of total cholesterol in serum was significantly higher in the cholesterol group than in the normal group, but this increase in the cholesterol group was significantly decreased by the cholesterol diet supplemented with chicory extract. Concentration of HDL-cholesterol in serum was significantly lower in the cholesterol group than in the normal group, but this decrease in the cholesterol group tended to increase in the chicory group. However, concentrations of triglyceride, phospholipid and nonesterified fatty acid in serum were not significantly different among the groups. Concentrations of triglyceride and cholesterol in liver were significantly higher in the cholesterol and chicory groups than in the normal group. Feces weight and the excretion of cholesterol and bile acid into feces were significantly higher in the chicory group than in other groups. Concentrations of thiobarbituric acid reactive substances (TBARS) in homogenates and microsomal fractions of liver were not significantly different among the groups. On the other hand, concentration of 8-hydroxydeoxyguanosine (8-OHdG) as an useful marker of oxidative stress in urine was lower in the chicory group than in other groups. Concentration of serum glucose was signnificantly lower in the cholesterol group than in the normal group, but that of the chicory group was significantly higher than in the normal group. These results demonstrated that dietary chicory extract exerted the decreasing effect of cholesterol level and oxidative stress in cholesteral-fed rats.