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Lee, So Jung,Kay, Chul-Seoung,Kim, Yeon-Sil,Son, Seok Hyun,Kim, Myungsoo,Lee, Sea-Won,Kang, Hye Jin The Korean Society for Radiation Oncology 2017 Radiation Oncology Journal Vol.35 No.4
Purpose: To investigate the predictive role of maximum standardized uptake value ($SUV_{max}$) of 2-[$^{18}F$]fluoro-2-deoxy-D-glucose($^{18}F-FDG$) positron emission tomography/computed tomography (PET/CT) in nasopharyngeal cancer patients treated with intensity-modulated radiotherapy (IMRT). Materials and Methods: Between October 2006 and April 2016, 53 patients were treated with IMRT in two institutions and their PET/CT at the time of diagnosis was reviewed. The $SUV_{max}$ of their nasopharyngeal lesions and metastatic lymph nodes (LN) was recorded. IMRT was delivered using helical tomotherapy. All patients except for one were treated with concurrent chemoradiation therapy (CCRT). Correlations between $SUV_{max}$ and patients' survival and recurrence were analyzed. Results: At a median follow-up time of 31.5 months (range, 3.4 to 98.7 months), the 3-year overall survival (OS) and disease-free survival (DFS) rates were 83.2% and 77.5%, respectively. In univariate analysis, patients with a higher nodal pre-treatment $SUV_{max}$ (${\geq}13.4$) demonstrated significantly lower 3-year OS (93.1% vs. 55.5%; p = 0.003), DFS (92.7% vs. 38.5%; p < 0.001), locoregional recurrence-free survival (100% vs. 50.5%; p < 0.001), and distant metastasis-free survival (100% vs. 69.2%; p = 0.004), respectively. In multivariate analysis, high pre-treatment nodal $SUV_{max}$ (${\geq}13.4$) was a negative prognostic factor for OS (hazard ratio [HR], 7.799; 95% confidence interval [CI], 1.506-40.397; p = 0.014) and DFS (HR, 9.392; 95% CI, 1.989-44.339; p = 0.005). Conclusions: High pre-treatment nodal $SUV_{max}$ was an independent prognosticator of survival and disease progression in nasopharyngeal carcinoma patients treated with IMRT in our cohort. Therefore, nodal $SUV_{max}$ may provide important information for identifying patients who require more aggressive treatment.
Kay, Hee Yeon,Won Yang, Jin,Kim, Tae Hyun,Lee, Da Yeon,Kang, Bomi,Ryu, Jae-Ha,Jeon, Raok,Kim, Sang Geon Wistar Institute of Anatomy and Biology 2010 The Journal of nutrition Vol.140 No.7
<P>Cytoprotective effects of chemopreventive agents may be attributed to the induction of antioxidant enzymes. Among these, the induction of glutamate-cysteine ligase (GCL) protects cells from oxidative injury by increasing glutathione (GSH) content. Nuclear factor erythroid-2-related factor 2 (Nrf2) transcriptionally regulates the expression of genes encoding for GCL and other cysteine-metabolizing enzymes. Despite extensive studies on the components in garlic, little information is available on organosulfur by-products made from garlic. In this study, we investigated whether ajoene, a chemically stable garlic by-product, has the ability to activate Nrf2 and induce GCL, and, if so, what is the role of activating Nrf2 in cytoprotection against oxidative stress. Immunoblottings and reporter gene assays were performed in HepG2 cells. Ajoene treatment activated Nrf2, as indicated by increased phosphorylation and nuclear accumulation of Nrf2, decreased interaction with Kelch-like ECH-associated protein-1, and decreased Nrf2 ubiquitination. Consistently, treatment of ajoene increased antioxidant response element reporter gene activity and the mRNA and protein levels of GCL subunits. Ajoene activated protein kinase C-delta (PKCdelta). Inhibition of PKCdelta activation by rottlerin abrogated its ability to activate Nrf2 and induce GCL, suggesting that ajoene promotes the Nrf2-dependent antioxidant defense system via PKCdelta activation. Consequently, ajoene prevented cell death, GSH depletion, and hydrogen peroxide production elicited by tert-butylhydroperoxide. The important role of Nrf2 in cytoprotection was verified by the reversal of ajoene's ability to protect hepatocytes in Nrf2-knockout mice. Our results demonstrate that ajoene increases PKCdelta-dependent Nrf2 activation, GCL induction, and the cellular GSH concentration, which may contribute to protecting cells from oxidative stress.</P>
이계원(Lee Kay-Won) 조선대학교 지식경영연구원 2004 지역개발연구 Vol.9 No.2
Stock split indicates a division of face value. The reason why firms split their stock is to secure liquidity and to achieve easier trade with an increase of the number of stock. In general. face split is actively progressed in a perspective of liquidity reinforcement in stock price increase period while face merger is intended rather than split because of anxiety on resource burden in stock price decrease period. Expectation is based on experiences on markets. This study demonstrated whether the results of previous studies on positive excess earning rate of stock split may be applied for the recent stock market from 1999 to late 2003 after a foreign exchange crisis. For the study. 88 firms which officially disclosed stock split from 1999 to 2003 were finally selected. To demonstrate the effect of stock split in varied viewpoints. this study classified the subject according to the date of decision-making on stock split by a board of directors and general meeting of stockholders, split ratio. total assets. number of stock issued. and stock price and compared them. The results of the study are summarized as follows: First. official announcement of stock split shows statistically significant positive excess returns in our stock market. However. the effect is shown on the date of announcement and the next day, and further persistent increase was not found. Accumulated excess returns reaches at peak on the date of announcement and the next day. and then gradually decreases. Persistence of stock reaction after split announcement was not found in this study. but it is found that it has some influence on the increase in the stock price level. Second. the announcement by the board of directors shows higher returns than that by the stockholders meeting. which indicates that information effect is more reflected on the date when the board of directors decides the announcement. Third. small firms and those with higher split ratios and more number of stock issued showed higher excess returns. which indicates that higher reinforcement of liquidity influences positively on stock prices.
이계원(Lee Kay-Won) 조선대학교 지식경영연구원 2003 지역개발연구 Vol.8 No.2
I provide evidence on the level and value of corporate diversification using a sample of korean firms. I find that the level of diversification is positively related to firm size and debt ratio. but negatively related to the equity ownership of inside blockholders. I find evidence that insider ownership has a significant impact on the 5% level of diversification only for those groups, suggesting that value-reducing diversification stems from agency problems. Foreign ownership does not have a significant impact on the value of diversification. Thus, while outside blockholders may act as a deterrent on the level of diversification. there is no evidence that they can effectively reduce the agency problems for those firms with low managerial ownership.
이계원(Lee Kay-Won) 조선대학교 지식경영연구원 2005 지역개발연구 Vol.10 No.1
This study investigate the information effect of the inquired disclosure by the disclosure type, timing of disclosure and the firm's response pattern. To this purpose, this study tests the hypothesis that the cumulative abnormal return(CAR) at the announcement day, which disclose a change of supply contract, M&A, and business purpose, has positive returns. Empirical results show that the inquired disclosure with a firm's new supply contract. M&A, a stock price fluctuation have significantly positive CAR. Furthermore, the timing of inquired disclosure highly effective information since the volatility is increasing after the release the inquired disclosure.
이계원(Lee Kay-Won) 조선대학교 지식경영연구원 2003 지역개발연구 Vol.8 No.1
This study is purposed to test the market efficiency of KOSDAQ which present the adequate information to the investor in the second board market-I examine the impact of main board listing information on the stock price of KOSDAQ. I find that stock returns as measured by CAR are significantly increasing from disclosure day. which listing on KSE, to the after 30 business day. The positive correlation found between stock returns and listing announcement is also supportive of the view that KOSDAQ market has a lower degree of market efficiency than KSE. My findings can be summarized as follows. First, I find that listing on KSE is a good news for the investor in KOSDAQ. Second, CAR of listing firms from KOSDAQ is higher than the firms without KOSDAQ after listing day.