• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.16-20
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• 2000

The aqueous extract from the cultural mycelium of Paecilomyces japonica showed cytotoxicity against several tumor cells including Jurkat, U937, HL-60, HepG2, BW5147.G.1.4, and NIH3T3. When the aqueous extract was fractionated by sequential organic solvent extractions using n-hexane and ethyl acetate, the ethyl acetate fraction appeared to contain the most cytotoxic activity, and the $IC_{50}$ values for various tumor cells were in the range from 1.5 to $10.0{\;}\mu\textrm{g}/ml$. To elucidate the cellular mechanism underlying the induced cytotoxicity, the apoptotic DNA fragmentation along with the cell cycle proression was examined in Jurkat T cells following the ethyl acetate fraction treatment. In the presence of $2.5{\;}\mu\textrm{g}/ml$ of the ethyl acetate fraction, apoptotic DNA fragmentation of the cells was detected within 1 h and increased upto 24 h in a time-dependent manner. Under the same conditions, a sub-G1 peak was detectable by flow cytometry. These results indicate that the cytotoxic effect of P. japonica on tumor cells is attributable to the induced apoptosis.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.6
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• pp.311-316
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• 2003

Endothelins secreted from keratinocytes are intrinsic mitogens and melanogens of human melanocytes in UVB-induced hyperpigmentation. To elucidate the cellular mechanism of antimelanogenic activity of bamboo extract, the effects of three ingredients of bamboo extract on endothelin 1 (ET-1)-induced $Ca^{2+}$ mobilization were investigated in cultured human melanocytes. ET-1 receptors in human melanocytes were characterized by using specific antagonist, and ET-1 was found to increase intracellular $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) by activating ET-B receptor. SM709 (1,2-O-diferulyl-glycerol), an ingredient of bamboo extract, inhibited ET-1-induced $[Ca^{2+}]_i$ increase in a concentration- and time-dependent manner, although another ingredients SM707 and SM708 had no effect on ET-1-induced $[Ca^{2+}]_i$ increase in human melanocytes. SM709 ($100{\mu}M$), however, did not affect $[Ca^{2+}]_i$ increase induced by thapsigargin and caffeine, suggesting that SM709 has no effect on the $Ca^{2+}$ store in melanocytes. Furthermore, SM709 did not affect $[Ca^{2+}]_i$ increase induced by LPA or ATP, known as G protein-mediated PLC activators like ET-1. Taken together, it is suggested that SM709 antagonizes ET-1-induced transmembrane signaling through ET-B receptor, which maybe a possible underlying mechanism of antimelanogenic activity of bamboo extract in human melanocytes.

• Journal of Korean Neurosurgical Society
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• v.40 no.2
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• pp.103-109
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• 2006

Objective : Activated endothelial cells mediate the cascade of reactions in response to hypoxia for adaptation to the stress. It has been suggested that hypoxia, by itself, without reperfusion, can activate the endothelial cells and initiate complex responses. In this study, we investigated whether hypoxia-induced endothelial products alter the endothelial permeability and have a direct cytotoxic effect on nerve cells. Methods : Hypoxic condition of primary human umbilical vein endothelial cells[HUVEC] was induced by $CoCl_2$ treatment in culture medium. Cell growth was evaluated by 3,4,5-dimethyl thiazole-3,5-diphenyl tetrazolium bromide [MTT] assay Hypoxia-induced products [$IL-1{\beta},\;TGF-{\beta}1,\;IFN-{\gamma},\;TNF-{\alpha}$, IL-10, IL-6, IL-8, MCP-l and VEGF] were assessed by enzyme-linked immunosorbent assay. Endothelial permeability was evaluated by Western blotting. Results : Prolonged hypoxia caused endothelial cells to secrete IL -6, IL -8, MCP-1 and VEGF. However, the levels of IL -1, IL -10, $TNF-{\alpha},\;TGF-{\beta},\;IFN-{\gamma}$ and nitric oxide remained unchanged over 48 h hypoxia. Hypoxic exposure to endothelial cells induced the time-dependent down regulation of the expression of cadherin and catenin protein. The conditioned medium taken from hypoxic HUVECs had the cytotoxic effect selectively on neuroblastoma cells, but not on astroglioma cells. Conclusion : These results suggest the possibility that endothelial cell derived cytokines or other secreted products with the increased endothelial permeability might directly contribute to nerve cell injury followed by hypoxia.

• Journal of Nutrition and Health
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• v.39 no.8
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• pp.742-747
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• 2006

This study was performed to investigate the lipolytic effects of Portulaca oleracea L. extract in 3T3-L1 adipocytes. The Portulaca oleracea L. was extracted with extrusion method using twin-screw extruder under $58{\sim}60rpm$ screw speed, $4{\sim}5kg/hr$ feed rate, $140^{\circ}C$ extrusion temperature. The lipolytic action of Portulaca oleracea L. extract was estimated by measuring the amount of glycerol and free fatty acids (FFA) released from 3T3-L1 adipocytes and by measuring the cellular lipid content in 3T3-L1 adipocytes. The hormone sensitive lipase (HSL) mRNA level was analyzed using quantitative real-time PCR. The Portulaca oleracea L. extract at 1 to $100{\mu}g/ml$ suppressed lipid accumulation. The release of glycerol and FFA into the medium, and the mRNA level of HSL were significantly increased by the addition of Portulaca oleracea L. extract at dose-dependent manner. In conclusion, the Portulaca oleracea L. extract was suggested to have the lipolytic effect through release of lipolytic products (FFA and glycerol) of triacylglyceride to the culture medium and suppression of lipid accumulation via up-regulation of HSL gene expression in 3T3-L1 adipocytes.

• The Korean Journal of Physiology
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• v.22 no.2
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• pp.219-230
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• 1988

The effect of glycine, structurally the most simple amino acid was investigated on the electrophysiological characteristics of the isolated superfused atrial muscle and sinus node cells of the rabbit heart. Superfusion of the sinus node cell with glycine solution (3, 5 and 8 mM) produced concentration-dependent increments of OS (overshoot potential) and MDP (maximum diastolic potential). Generally action potential amplitude increased as a result of greater increment of OS than that of MDP. The changes in action potential of the sinus node cell peaked in $7{\sim}10{\;}minutes$ after onset of superfusioin. On the contrary to the response to intravenously administered glycine, the rate of spontaneous firing of sinus node cell was invariably increased following superfusion with glycine. Action potential duration manifested as $APD_{60}$ (time to 60% repolarization) was significantly shortened by glycine. And the electrophysiological effects of glycine on the atrial muscle cell were similar to that on the sinus node cells. The results of present study suggest that glycine can exert direct effects on the atrial muscle and sinus node cells of the rabbit heart.

• YAKHAK HOEJI
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• v.54 no.4
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• pp.252-257
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• 2010

The aim of this study was to investigate the effect of resveratrol on the pharmacokinetics of nifedipine in rats. The pharmacokinetic parameters of nifedipine were measured after the oral administration of nifenipine (6 mg/kg) in the presence or absence of resveratrol (0.5, 2.5 and 10 mg/kg, respectively). The effect of resveratrol on the P-glycoprotein (Pgp), CYP 3A4 activity was also evaluated. Resveratrol inhibited CYP3A4 enzyme activity in a concentration-dependent manner with 50% inhibition concentration ($IC_{50}$) of 0.94 ${\mu}M$. In addition, resveratrol significantly enhanced the cellular accumulation of rhodamine 123 in MCF-7/ADR cells overexpressing P-gp. Compared to the control groups, the presence of 2.5 mg/kg and 10 mg/kg of resveratrol significantly (p<0.05, p<0.01) increased the area under the plasma concentrationtime curve (AUC) of nifedipine by 49~75%, and the peak concentration ($C_{max}$) of nifedipine by 48~66%. The absolute bioavailability (AB%) of nifedipine was significantly (p<0.05) increased by 22.9-34.8% compared to the control (19.8%). The terminal half-life ($T_{1/2}$) of nifedipine was significantly (p<0.05) increased compared to the control. While there was no significant change in the time to reach the peak plasma concentration ($T_{max}$) of nifedipine in the presence of resveratrol. It might be suggested that resveratrol altered disposition of nifedipine by inhibition of both the CYP3A and P-glycoprotein efflux pump in the small intestine of rats. In conclusion, the presence of resveratrol significantly enhanced the oral bioavailability of nifedipine, suggesting that concurrent use of resveratrol or resveratrol-containing dietary supplenment with nifedipine should require close monitoring for potential drug interation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.105-113
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• 2017

Network externality can be defined as the effect that one user of a good or service has on the value of that product to other people. When a network externality is present, the value of a product or service is dependent on the number of others using it. There exist asymmetries in network externalities between the online and traditional offline marketing channels. Technological capabilities such as interactivity and real-time communications enable the creation of virtual communities. These user communities generate significant direct as well as indirect network externalities by creating added value through user ratings, reviews and feedback, which contributes to eliminate consumers' concern for buying products without the experience of 'touch and feel'. The offline channel offers much less scope for such community building, and consequently, almost no possibility for the creation of network externality. In this study, we analyze the effect of network externality on the competition between online and conventional offline marketing channels using game theory. To do this, we first set up a two-period game model to represent the competition between online and offline marketing channels under network externalities. Numerical analysis of the Nash equilibrium solutions of the game showed that the pricing strategies of online and offline channels heavily depend not only on the strength of network externality but on the relative efficiency of online channel. When the relative efficiency of online channel is high, the online channel can greatly benefit by the network externality. On the other hand, if the relative efficiency of online channel is low, the online channel may not benefit at all by the network externality.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.173-177
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• 2013

Backgrounds: Tanshinone IIA (TIIA), a phenanthrenequinone derivative extracted from Salvia miltiorrhiza BUNGE, has been reported to be a natural anti-cancer agent in a variety of tumor cells. However, the effect of TIIA on gastric cancer cells remains unknown. In the present study, we investigated the influence of TIIA on the malignant phenotype of SGC7901 gastric cancer cells. Methods: Cells cultured in vitro were treated with TIIA (0, 1, 5, $10{\mu}g/ml$) and after incubation for different periods, cell proliferation was measured by MTT method and cell apoptosis and cell cycling were assessed by flow cytometry (FCM). The sensitivity of SGC7901 gastric cancer cells to anticancer chemotherapy was investigated with the MTT method, while cell migration and invasion were examined by wound-healing and transwell assays, respectively. Results: TIIA (1, 5, $10{\mu}g/ml$) exerted powerful inhibitory effects on cell proliferation (P < 0.05, and P < 0.01), and this effect was time- and dose-dependent. FCM results showed that TIIA induced apoptosis of SGC7901 cells, reduced the number of cells in S phase and increased those in G0/G1 phase. TIIA also significantly increased the sensitivity of SGC7901 gastric cancer cells to ADR and Fu. Moreover, wound-healing and transwell assays showed that TIIA markedly decreased migratory and invasive abilities of SGC7901 cells. Conclusions: TIIA can reverse the malignant phenotype of SGC7901 gastric cancer cells, indicating that it may be a promising therapeutic agent.

• IMMUNE NETWORK
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• v.5 no.4
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• pp.247-251
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• 2005

Background: Natural killer (NK) cells are CD3 (-) CD14 (-) CD56 (+) lymphocytes. They play an important role in the body's innate immune response. They can induce spontaneous killing of cancer cells or virus-infected cells via the Fas/Fas ligand or the granzyme/perforin systems. The corticotropin-releasing hormone (CRH) is an important regulator for the body's stress response. It promotes proliferation and migration of various cancer cells through the CRH type 1 receptor under stress, and also inhibits NK or T cell activity. However, the relationship of CRH and NK cell migration to the target has not been confirmed. Herein, we study the effect of CRH on NK cell migration. Methods: We used the human NK cell line, NK-92MI, and tested the expression of CRH receptor type 1 on NK-92MI by RT-PCR. This was to examine the effect of CRH on tumor and NK cell migration, thus NK cells (NK-92MI) were incubated with or without CRH and then each CRH treated cell's migration ability compared to that of the CRH untreated group. Results: We confirmed that CRH receptor type 1 is expressed in NK-92MI. CRH can decrease NK cell migration in a time-/dose-dependent manner. Conclusion: These data suggest CRH can inhibit NK cell migration to target cells.

• Journal of Digital Convergence
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• v.16 no.4
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• pp.363-369
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• 2018

This study examines the effects of mindfulness training on job stress, burnout, and teacher efficacy for middle school and high school teachers. For this study, twenty-four middle school and high school teachers were divided into experimental and control groups. Data analysis was performed using a Mixed ANOVA for teacher's job stress, burnout, and teacher efficacy according to pre-training, post-training and delayed post-training periods. As a result, we found support for time interval and between-group interaction effects for all the dependent variables. In order to investigate any delayed effects, a t-test was performed to analyze measurements taken one month after the completion of training period. The delayed post-training results indicated a significant effect between pre and post scores, meaning the program effects were sustained. Therefore, this study indicates that the mindfulness training program implemented in this research is an effective method for preventing job stress and burnout, as well as influencing the efficiency of work performance for middle school and high school teachers.