• 생명과학회지
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• 제20권7호
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• pp.977-982
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• 2010

본 연구에서는 오미자에서 분리된 dibenzocyclooctadiene lignan의 일종인 gomisin A와 gomisin N에 대한 항암효능을 U937 인체혈구암세포를 대상으로 조사하였다. Gomisin N은 처리농도의 증가에 따라 U937 세포의 증식을 억제하였으나 동일조건에서 gomisin A는 세포독성 효과를 나타내지 못하였으며, gomisin N에 의한 U937 세포의 증식억제는 세포주기 G1 arrest 유발에 의한 것이었다. Gomisin N에 의한 G1 arrest는 cyclin E, cyclin-dependent kinase (Cdk) 2 및 Cdk4의 발현 억제와 Cdk inhibitor인 p16 (INK4A) 및 p21 (WAF1/CIP1)의 발현 증가와 연관성이 있었으나, gomisin A는 세포주기 인자들의 발현에 유의적인 변화를 유발하지 않았다. 또한 gomisin N은 retinoblastoma 단백질군인 pRB 및 p130의 인산화를 억제하였으며, 전사조절인자인 E2F 단백질들의 발현을 억제하였다. 본 연구의 결과에서 gomisin N에 의한 U937 세포의 증식억제는 세포주기 조절인자들의 발현 변화를 통한 G1 arrest 유발에 의한 것임을 알 수 있었으며, gomisin N은 암예방 및 항암활성 후보불질로서의 개발 가능성이 있음을 알 수 있었다.

• Radiation Oncology Journal
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• 제11권2호
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• pp.285-294
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• 1993

A total of forty patients with resected N2 stage non-small cell lung cancer treated with postoperative adjuvant radiation therapy between Jan. 1975 and Dec. 1990 at the Department of Radiation Oncology, Yonsei University College of Medicine, Yonsei Cancer Center were retrospectively analysed to evaluate whether postoperative radiation therapy improves survival. Patterns of failure and prognostic factors affecting survival were also analysed. The 5 year overall and disease free survival rate were $26.3\%,\;27.3\%$ and median survival 23.5 months. The 5 year survival rates by T-stage were $T1\;66.7\%,\;T2\;25.6\%\;and\;T3\;12.5\%.$ Loco-regional failure rate was $14.3\%$ and distant metastasis rate was $42.9\%$ and both $2.9\%.$ Statistically significant factor affecting distant failure rate was number of postitive lymph nodes(>=4). This retrospective study suggests that postoperative radiation therapy in resected N2 stage non-small cell lung cancer can reduce loco-regional recurrence and may improve survival rate as compared with other studies which were treated by surgery alone. Further study of systemic control is also needed due to high rate of distant metastasis.

• 대한임상검사과학회지
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• 제43권4호
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• pp.161-170
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• 2011

Quercetin is one of the most distributed flavonoids in the plant kingdom and occurs naturally in a wide range of fruits and vegetables. This study was undertaken to determine whether quercetin exerts beneficial effect against necrotic and apoptotic cell death induced by hydrogen peroxide ($H_2O2$) in intestinal cells using the human-derived cultured T84 colonic epithelial cell line. Necrotic cell death was induced by exposing cells to 0.5 mM $H_2O_2$ for 2 h and apoptosis was induced by incubating cells in normal culture medium for 18 h following exposure of cells to 0.5 mM $H_2O2$ for 2 h. Cell viability was evaluated by the trypan blue exclusion assay and apoptosis was assessed by Hoechst 33258 staining and flow cytometry. $H_2O_2$ induced necrotic cell death in a time and dose-dependent fashion. Both necrotic and apoptotic cell deaths were not prevented by the antioxidants N,N'-diphenyl-p-phenylenediamine(DPPD) and Trolox, whereas both cell deaths induced by the organic hydroperoxide t-butylhydroperoxide (tBHP) were prevented by DPPD, suggesting that $H_2O_2$ induces cell death through a lipid peroxidation-independent mechanism. $H_2O2$-induced necrotic death was prevented by deferoxamine and 3-aminobenzamide, while the apoptotic cell death was not affected by these agents. Quercetin prevented both necrotic and apoptotic cell deaths induced by $H_2O_2$ in a dose-dependent manner. $H_2O_2$ caused activation of poly (ADP-ribose) polmerase (PARP), which was inhibited by deferoxamine, 3-aminobenzamide, and quercetin, but not DPPD. These results indicate that quercetin inhibits both necroticand apoptotic deaths of T84 cells. The anti-necrotic effect of quercetin may be attributed to its iron chelator activity rather than a direct $H_2O_2$ scavenging capacity and antioxidant. The present study suggests that quercetin may play a therapeutic role in the treatment of human gastrointestinal diseases mediated by oxidants.

• Macromolecular Research
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• 제14권4호
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• pp.438-442
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• 2006

Novel sulfonated poly(aryl ether ketones) containing benzoxazole were directly synthesized by aromatic nucleophilic polycondensation using various ratios of 2,2'-bi[2-( 4-flurophenyl)benzoxazol-6-yl]hexafluoropropane to sodium 5,5'-carbonylbis(2-fluorobenzenesulfonate). The copolymers were soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide at a relatively high solid composition (>15 wt%) and formed tough, flexible and transparent membranes. The membranes exhibited a degradation temperature of above $290^{\circ}C$. The exact dissolution times of these membranes at $80^{\circ}C$ in Fenton's reagent (3 wt% $H_2O_2$ containing 2 ppm $FeSO_4$) were undetectable, confirming their excellent chemical stability in fuel cell application. The membranes showed a moderate increase in water uptake with respect to increasing temperature. The proton conductivities of the membranes were dependent on the composition and ranged from $1.10{\times}10^{-2}$ to $5.50{\times}10^{-2}Scm^{-1}$ at $80^{\circ}C$ and 95% relative humidity (RH). At $120^{\circ}C$ without externally humidified conditions, the conductivities increased above $10^{-2}Scm^{-1}$ with respect to increasing benzoxazole content, which suggested that the benzoxazole moieties contributed to the proton conduction.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.75-75
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• 2003

Since the establishment of embryonic stem cell, pluripotency of the cells was known to allow differentiation of the cells into various cell types consisting whole body. Several protocols have been developed to induce expression of specific genes.. However, no precise protocol that will generate a single type of the cells from stem cells has been reported. In order to produce cells suitable for transplantion into brain of PD animal model, which arouse due to a progressive degeneration of dopaminergic neurons in midbrain, human embryonic stem cell (hESC, MB03) was transfected with cDNAs cording for tyrosine hydroxylase (TH). Successful transfection was confirmed by western immunoblotting. Newly transfected cell line (TH#2/MB03) was induced to differentiate by the two neurogenic factors retinoic acid (RA) and b-FGF. Exp. I) Upon differentiation using RA/ascorbic acid (AA), embryoid bodies (EB, for 4days) derived from hES cells were exposed to RA (10$^{-6}$ M)/AA (50 mM) for 4 days, and were allowed to differentiate in N2 medium for 7, 14, 21, or 28 days. Exp. II) When bFGF was used, neuronal precursor cells were selected for 8 days in N2 medium after EB formation. After selection, cells were expanded at the presence of bFGF (20 ng/ml) for another 6 days followed by a final differentiation in N2 medium for 7, 14, 21 or 28 days. By indirect immunocytochemical studies, proportion of cells expressing NF200 increased rapidly from 20% at 7 days to 70 % at 28 days in RA/AA-treated group, while those cells expressing NF160 decreased from 80% at 7 days to 10% at 28 days upon differentiation in N2 medium. However, in differentiation by RA/AA treatment system, there was a significant increase in proportion of neuron maturity (73%) at day 14 after N2 medium. TH#2/MB03 cells expressing TH are >90% when matured at the absence of either bDNF or TGF-$\alpha$. These results suggested that TH#2/MB03 cells could be differentiated in vitro into mature neurons by RA/AA.

• 대한의생명과학회지
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• 제8권4호
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• pp.251-256
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• 2002

This study was undertaken to determine the underlying mechanisms of reactive oxygen species-induced cell injury in renal epithelial cells and whether there is a difference in the role of lipid peroxidation between freshly isolated renal cells and cultured renal cells. Rabbit renal cortical slices were used as a model of freshly isolated cells and opossum kidney (OK) cells as a model of cultured cells. Cell injury was estimated by measuring lactate dehydrogenase (LDH) release in renal cortical slices and frypan blue exclusion in OK cells. $H_2O$$_2$ was used as a drug model of reactive oxygen species. $H_2O$$_2$ induced cell injury in a dose-dependent manner in both cell types. However, renal cortical slices were resistant to $H_2O$$_2$ approximately 50-fold than OK cells. $H_2O$$_2$-induced cell injury was prevented by thiols (glutathione and dithiothreitol) and iron chelators (deferoxamine and phenanthroline) in both cell types. $H_2O$$_2$-induced cell injury in renal cortical slices was completely prevented by antioxidants N,N-diphenyl-p -phenylenediamine and Trolox, but the cell injury was not affected by these antioxidants in OK cells. $H_2O$$_2$ increased lipid peroxidation in both cell types, which was completely inhibited by the antioxidants. These results suggest that $H_2O$$_2$ induces cell injury through a lipid peroxidation-dependent mechanism in freshly isolated renal cells, but via a mechanism independent of lipid peronidation in cultured cells.

• 전자공학회논문지A
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• 제28A권1호
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• pp.30-39
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• 1991

The influence of physical parameters (Al mole fraction, thickness, doping concentration) in the window and emitter on the efficiency characteristics of heteroface p-$Al_{x}Ga_{1-x}As/p-GaAs/n-GaAs/n^{+}$-GaAs solar cell is investigated. The maximum efficiency theoretically calculated in this device is obtained when a thickness of the window is in a range of (400-1000))$\AA$and a thickness/doping concentration of the emitter is in a range of (0.5-0.8)$\mu$m/(1-7)${\times}10^{17}cm^{-3}$, respectively. Also is the efficiency improved according to the increase of Al mole fraction in the indirect gap window(0.41${\le}x{\le}1.0$). The optimum designed heteroface cell with an area of 0.165cm$^2$fabricated using MOCVD exhibits an active area conversion efficiency of 17%, having a short circuit current density of 21.2mA/cm\ulcorner an open circuit voltage of 0.94V, and a fill factor of 0.75 under ELH-100mW/cm$^2$illumination.

• Current Photovoltaic Research
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• 제2권4호
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• pp.147-151
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• 2014

A boron doping process using a boron tri-bromide ($BBr_3$) as a boron source was applied to form a $p^+$ emitter layer on an n-type mono-crystalline CZ substrate. Nitrogen ($N_2$) gas as an additive of the diffusion process was varied in order to study the variations in sheet resistance and the uniformity of doped layer. The flow rate of $N_2$ gas flow was changed in the range 3 slm~10 slm. The sheet resistance uniformity however was found to be variable with the variation of the $N_2$ flow rate. The optimal flow rate for $N_2$ gas was found to be 4 slm, resulting in a sheet resistance value of $50{\Omega}/sq$ and having a uniformity of less than 10%. The process temperature was also varied in order to study its influence on the sheet resistance and minority carrier lifetimes. A higher lifetime value of $1727.72{\mu}s$ was achieved for the emitter having $51.74{\Omega}/sq$ sheet resistances. The thickness of the boron rich layer (BRL) was found to increase with the increase in the process temperature and a decrease in the sheet resistance was observed with the increase in the process temperature. Furthermore, a passivated emitter solar cell (PESC) type solar cell structure comprised of a boron doped emitter and phosphorus doped back surface field (BSF) having Ni/Cu contacts yielding 15.32% efficiency is fabricated.

• 한국전자통신학회논문지
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• 제5권1호
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• pp.10-16
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• 2010

전이 규칙 90과 150만을 사용하는 90/150 CA는 최소다항식과 특성다항식이 같은 CA로 랜덤성이 우수하여 LFSR의 대안으로 사용되어왔다. 90 Uniform CA와 150 uniform CA는 모든 셀에 동일한 전이규칙이 적용되는 CA로 기밀성과 인증을 제공하는 Sarkar의 암호기법에 사용되었다. 본 논문에서는 전이규칙이 90 또는 150인 uniform CA에 대하여 분석하고 특별한 전이규칙을 갖는 n-셀 90/150 CA를 이용하여 2n-셀 uniform CA와 (2n+1)-셀 uniform CA를 합성하고 대응하는 특성다항식을 계산하는 효율적 방법을 제안한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.332.2-332.2
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• 2016

Two dimensional transition-metal dichalcogenides (TMDs) semiconductors are attractive materials for optoelectric devices because of their direct energy bandgap and transparency. To investigate the feasibility of transparent p-n junctions, we have fabricated a p-n heterojunction consisting of p-type WSe2 and n-type MoS2 flakes since WSe2 and MoS2 with proper electrode metals exhibit p-type and n-type behaviors, respectively. These heterojunctions exhibits gate-tunable rectifying behaviors and photovoltaic effects (ECE ~ 0.2%) indicating that p-n junctions were formed. In addition, photocurrent and photovoltaic effects were observed under light illumination, which were dependent on the gate voltage. In addition, the photocurrent mapping images indicate that the photovoltaic effects comes from the junction area. Possible origins of gate-tunability are discussed.