• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.4
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• pp.313-322
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• 2013

Ultraviolet irradiation in the cells and skin produces reactive oxygen species (ROS), which induces the synthesis of matrix metalloproteinases (MMPs) causing skin photoaging. Using the human dermal fibroblast (HDF), we investigated the antioxidative and anti-aging effects of the extracts from Talinum paniculatum. Talinum paniculatum leaf and stem extracts (LSE) showed free radical scavenging effect by 98.45% at 500 ${\mu}g/mL$ and superoxide radical scavenging effect by 97.01% at 500 ${\mu}g/mL$ in the xanthine/xanthine oxidase system. The photoprotective potential of LSE was tested in HDF exposed to ultraviolet irradiation. It was revealed that LSE had an inhibitory effect on MMP-1 expression in UVA-irradiated HDF without any significant cytotoxicity. The treatment of UVA-irradiated HDF with LSE resulted in dose-dependent decreases in the expression levels of MMP-1 mRNA and protein. Also, UVB-induced cytotoxicity and cell death were effectively suppressed by treatment of LSE. Additionally, the senescence-associated ${\beta}$- galactosidase (SA-${\beta}$-gal) activity was decreased in the presence of LSE. These results suggest that Talinum paniculatum leaf and stem extracts (LSE) may have anti-aging effects and can be used as new functional materials against oxidative stress-mediated skin damages.

• The Korea Journal of Herbology
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• v.20 no.3
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• pp.29-41
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• 2005

Objectives : The use of natural products with therapeutic properties is as ancient as human civilisation and, for a long time, mineral, plant and animal products were the main sources of drugs. Catalposide, the major iridoid glycoside isolated from the stem bark of Catalpa ovata G. Don (Bignoniceae) has been shown to possess anti-microbial and anti-tumoral properties. Heme oxygenase-1 (HO-1) is a stress response protein and is known to play a protective role against the oxidative injury. In this study, we examined whether catalposide could protect Neuro 2A cells, a kind of neuronal cell lines, from oxidative damage through the induction of HO-1 protein expression and HO activity. We also examined the effects of catalposide on the productions of tumor necrosis $factor-{\alpha}\;(TNF-{\alpha})$ and nitric oxide (NO) on RAW 264.7 macrophages activated with the endotoxin lipopolysaccharide. Methods : HO-1 expression in Neuro 2A cells was measured by Western blotting analysis. NO and $TNF--{\alpha}$ produced by RAW 264.7 macrophage were measured by Griess reagent and enzyme-linked immunosorbent assay, respectively. Results : The treatment of the cells with catalposide resulted in dose- and time-dependent up-regulations of both HO-1 protein expression and HO activity. Catalposide protected the cells from hydrogen peroxide-induced cell death. The protective effect of catalposide on hydrogen peroxide-induced cell death was abrogated by zinc protoporphyrin IX, a HO inhibitor. Additional experiments revealed the involvement of CO in the cytoprotective effect of catalposide-induced HO-1. In addition, catalposide inhibited the productions of $TNF--{\alpha}$ and NO with significant decreases in mRNA levels of $TNF--{\alpha}$ and inducible NO synthase. Conclusions : Our results indicate that catalposide is a potent inducer of HO-1 and HO-1 induction is responsible for the catalposide-mediated cytoprotection against oxidative damage and that catalposide may have therapeutic potential in the control of inflammatory disorders.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.111-137
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• 1991

Although a number of studies have been performed to assure that residual stress caused by a mismatch of alloy porcelain thermal expansion can contribute to clinical failure of a ceramometal restoratoin, the interactive influence of cooling rate on the magnitude of thermal expansion difference and on bond strength between them have not been extensively analyzed. The objective of this study was to determine the influence of cooling rate and the number of firing cycles on the expansion mismatch and the flexural failure resistance of metal porcelain strip. Tested alloys included one Pd-Ag alloy, one Ni-Cr-Be alloy with two kinds of porcelain, Vita and Ceramco. Metal specimens were cast into rods with a height of 13mm and a diameter of 5mm. Subsequently, the castings were subjected to scheduled firing cycles without porcelain. And the porcelain specimens after being fired were trimmed into a bar with a final dimension of 5 x 5 x 25mm. Thermal expansions of the alloys and porcelains were measured by using a push rod or a differential dialometer respectively. Porcelain glass transition temperatures and expansion values were derived alloy- porcelain pairs were assessed by comparing expansion values of the components at a porcelain glass transition temperature. Calculations were made using combinations of a Ni-Cr alloy or Pd-Ag alloy with each of two porcelain products. Metal- porcelain strip specimens were subjected to four point loading in an Instron testing machine until crack occured at the metal-cramic interface at the time of sharp decrease of load on recorder. On the basis of this study, the following conclusions may be stated : 1. Regardless of the kinds of ceramometal combinations, both of calculated and experimental data revealed that the double fired specimens exhibited a significantly lower flexural strength. 2. By the rise of the amount of mismatch, bond strength were decreased. 3. Thermal expansion value of Pd-Ag alloys were higher than of Ni-Cr alloys. 4. Expansion curves of metal were proportional to the increase of temperature and were not affected by the experimental conditions, however porcelains did not show the same magnitude of metal, and a shift of the glass transition temperature to higher temperatures was observed when cooled rapidly. 5. Alloy- porcelain thermal compatibility appeared more dependent on the porcelain than the alloy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.2
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• pp.119-127
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• 1986

The rheological properties of mayonnaise were studied with cylindrindrical viscometer. It was observed that mayonnaise showed pseudoplastic behavior, yield stress and time dependent characteristics. In the initial period of shear time, the decay of viscosity of mayonnaise was followed by a second-order kinetic equation. The influence of temperature on viscosity could be described by Arrhenius equation. The apparent viscosity of mayonnaise markedly increased with an rise in the concentration of egg yolk; and the emulsion was most stable at the concentration of 12%. At the concentration of $65{\sim}75%$ oil, the apparent viscosity was increased; the maximum value was reached at 75% oil, and above 75% oil, the remarkable decreased was observed. The size of oil drops was decreased with an increase in oil concentration of 75% oil. The apparent viscosity of mayonnaise was increased with an rise in water contents, while being decreased with one in the concentration of vinegar.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.3
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• pp.239-245
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• 2017

Aging is a physiological and irreversible, progressive process involving changes in the ability to maintain cellular functionality. It affects tissues, organs and the whole organism and thus finally cause to death. Oxidative stress has been postulated to contribute significantly to the accelerated accumulation of advanced glycation endproducts (AGEs) in collagen, which is implicated in the process of skin aging. In the present study, glycation inhibitory activity of methoxy PEG-45 thioctate (LA-PEG), and its inhibitory effect of cellular oxidation and senescence was investigated. Treatment of LA-PEG significantly showed lower fluorescent intensity induced by AGEs. In addition, LA-PEG was significantly reduced the formation of ROS induced by AGEs. High antioxidant and anti-glycation activities of LA-PEG in glycated collagen model indicated its contribution to anti-aging process. Cellular senescence leads to an increase in senescence-associated ${\beta}$-galactosidase ($SA-{\beta}-gal$) activity, which can be used as a biomarker to identify senescent cells. Treatment with LA-PEG showed a dose-dependent, statistically significant decreased in $SA-{\beta}-gal$ indicating reduced senescence. These results suggest that LA-PEG may have potent anti-aging effects and can be used as new functional materials against cellular accumulation of AGEs.

• Journal of Life Science
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• v.13 no.3
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• pp.241-247
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• 2003

While the DNA-protein kinase (DNA-PK) complex, comprised of DNA-PKcs and Ku80, is primary involved in the repair of DNA double-strand breaks, it is also believed to participate in additional cellular processes. Here, treatment of embryo fibroblasts (MEFs) derived from either wild-type (Wt) or DNA-PKcs-null (DNA-$PKcs^{-/-}$) mice with various stress inducing agents revealed that adriamycin was markedly more cytotoxic for $Ku80^{-/-}MEFs$ and led to their long-term accumulation in the $G_2$/M phase. This differential response was not due to differences in DNA repair, since adrimycin-triggered DNA damage was repaired with comparable efficiency in both Wt and $Ku80^{-/-}MEFs$, but was associated with differences in the expression of important cell cycle regulatory genes. Our results support the notion that Ku80-mediated cytoprotection and $G_2$/M-progression are not only dependent on the cell's DNA repair but also may reflect Ku80's influence on additional cellular processes such as gene expression.

• Journal of Life Science
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• v.23 no.12
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• pp.1428-1435
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• 2013

The aim of this study is to investigate the melanogenic effect of Oenanthe javanica ethanolic extracts (OJE) containing quercetin and kaempferol in melanoma cells (B16F1). In order to determine whether OJE inhibits melanin synthesis at the cellular level, the melanoma cells were cultured in the presence of different concentrations of OJE. In the present study, the antioxidant effects of OJE on DPPH radical scavenging, power reduction, lipid peroxidation, and DNA oxidation were evaluated in a cell free system. Furthermore, the effect of OJE on the production of melanin was determined by dopaquinone (DOPA) assay and tyrosinase activity. In addition, the protein expression of tyrosinase, as well as antioxidant enzymes such as superoxide dismutase (SOD)-1, SOD-2 and glutathione reductase (GSH), were examined using Western blot analysis. In this study, it was observed that OJE exhibited an inhibitory effect on lipid peroxidation and blocked the DNA oxidation induced by the hydroxyl radical produced by Fenton's reagent. OJE increased melanin synthesis above 50 ${\mu}g/ml$ and tyrosinase activity was detected above 50 ${\mu}g/ml$. In Western blot analysis, OJE increased the expression levels of tyrosinase, SOD-1, SOD-2, and GSH in a dose-dependent manner. These findings indicate that OJE with antioxidant activity can regulate the tyrosinase activity and melanin production in melanocyte, suggesting that it could promote the development of black hair as well as protect skin from oxidative stress.

• Resources Recycling
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• v.29 no.3
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• pp.11-23
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• 2020

This study aims to investigate breakage and liberation characteristics of iron ore from Shinyemi mine, Jeongseon by ball mill. Parameters of breakage functions for three grade samples of iron ore were obtained using single-sized-feed breakage test and back-calculation based on nonlinear programming. The results showed that with the increase in the grade of iron ore, the breakage rate factor decrease whereas the particle size sensitivity decreases. This results from retardation of microcrack-propagation by magnetite grain in the ore. Breakage distribution analysis showed that the breakage mechanism appear to be impact fracture dominant with the increase of grade owing to the stress distribution effect by magnetite grain. Degree of liberation (DOL) increased with the increase in grade and decrease in particle size, respectively. Using the breakage function and size-DOL relationship, a model that can predict time-dependent-DOL is established. When scale-up factors from operating condition are available, the model is expected to be capable of predicting size and DOL with time in actual mining process.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.290-299
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• 2006

Objectives: The purpose of this study is to evaluate the effect of ethylene glycol analogs on modulus of elasticity and ultimate tensile strength of moist, demineralized dentin matrix. Methods: Dentin disks 0.5 mrn thick were prepared from mid-coronal dentin of extracted. unerupted, human third molars. 'I' beam and hour-glass shaped specimens were prepared from the disks, the ends protected with nail varnish and the central regions completely demineralized in 0.5M EDTA for 5 days. Ultimate tensile stress (UTS) and low strain modulus of elasticity (E) were determined with specimens immersed for 60 min in distilled water $(H_{2}O)$, ethylene glycol $(HO-CH_{2}-CH_{2}-OH)$, 2-methoxyethanol $(H_{3}CO-CH_{2}-CH_{2}-OH)$, and 1,2-dimethoxyethane $(H_{3}CO-CH_{2}-CH_{3}-OCH_{3})$ prior to testing in those same media. Modulus of elasticity was measured on the same specimens in a repeated measures experimental design. The results were analyzed with a one-way ANOVA on ranks, followed by Dunn's test at ${\alpha}\;=\;0.05$. Regression analysis examined the relationship between UTS or E and hoy's solubility parameter for hydrogen bonding $({\delta}_{h})$ of each solvent. Results: The UTS of demineralized dentin in water, ethylene glycol, 2-methoxyethanol, and 1,2-dimethoxyethane was 24 (3), 30 (5), 37 (6), and 45 (6) MPa, ${\times}$ (SD) N = 10. Low strain E for the same media were 16 (13), 23 (14), 52 (24), and 62 (22) MPa. Regression analysis of UTS vs ${\delta}_{h}$ revealed a significant $(p\;<\;0.0001,\;r\;=\;-0.99,\;R^{2}\;=\;0.98)$ inverse, exponential relationship. A similar inverse relationship was obtained between low strain E vs ${\delta}_{h}\;(p\;<\;0.0005,\;r\;=\;-0.93,\;R^{2}\;=\;0.86)$. Significance: The tensile properties of demineralized dentin are dependent upon the hydrogen bonding ability of polar solvents $({\delta}_{h})$. Solvents with low ${\delta}_{h}$ values may permit new interpeptide H-bonding in collagen that increases its tensile properties. Solvents with high ${\delta}_{h}$ values prevent the development of these new interpeptide H-bonds.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.63-67
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• 2007

The neuroprotective effect of methanolic extracts from Dendrobium nobile Lindl. (DME) against $H_{2}O_{2}$-induced neurotoxicity in PC12 cells was investigated. The treatment of PC12 cells with various DME concentrations under $H_{2}O_{2}$ resulted in the induction of protective effect in a dose-dependent manner, as determined by the results of an MTT reduction assay, an LDH release assays, and a morphological assay. Interestingly, we also detected reduction of apoptotic bodies and inhibition of caspase-3 activity by DME in $H_{2}O_{2}$-indeced PC12 cells. These data show that the neuroprotective effect of DME against PC12 cells might be related to the suppression of caspase-3 activation. Therefore, these results suggest that DME could be a new potential candidate as chemotherapeutic agents against neuronal diseases.