• Nuclear Engineering and Technology
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• 제40권4호
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• pp.299-304
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• 2008

A detection system was set up to measure the neutron generation rate of a recently developed D-D neutron generator. The system is composed of a Si detector, He-3 detector, and electronics for pulse height analysis. The neutron generation rate was measured by counting protons using the Si detector, and the data was crosschecked by counting neutrons with the He-3 detector. The efficiencies of the Si and He-3 detectors were calibrated independently by using a standard alpha particle source $^{241}Am$ and a bare isotopic neutron source $^{252}Cf$, respectively. The effect of the cross-sectional difference between the D(d,p)T and $D(d,n)^3He$ reactions was evaluated for the case of a thick target. The neutron generation rate was theoretically corrected for the anisotropic emission of protons and neutrons in the D-D reactions. The attenuations of neutron on the path to the He-3 detector by the target assembly and vacuum flange of the neutron generator were considered by the Monte Carlo method using the MCNP 4C2 code. As a result, the neutron generation rate based on the Si detector measurement was determined with a relative uncertainty of ${\pm}5%$, and the two rates measured by both detectors corroborated within 20%.

• BMB Reports
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• 제42권5호
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• pp.265-270
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• 2009

Due to their multiple biological activities, flavonoids have gained attention as potentially useful therapeutics for a variety of diseases including cancer, cardiovascular diseases, and autoimmune diseases. In this study, we demonstrated that several flavonoids, including kaempferol, quercetin, fisetin, and chrysin block TNF-$\alpha$ induced IL-8 promoter activation and gene expression in HEK 293 cells. In addition, phosphorylation and degradation of $I{\kappa}B{\alpha}$ and translocation of NF-${\kappa}B$ p65 were inhibited by these flavonoids in TNF-$\alpha$-stimulated HEK 293 cells. Furthermore, generation of reactive oxygen species (ROS) in response to TNF-$\alpha$ was reduced by the flavonoids. Moreover, although pretreatment with fisetin, quercetin, or chrysin decreased cell viability, kaempferol did not. Taken together, these findings suggest that kaempferol would be useful for the treatment of TNF-$\alpha$-induced inflammatory diseases.

• 생약학회지
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• 제34권3호통권134호
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• pp.223-227
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• 2003

In the present study, anti-inflammatory activity of amygdalin isolated from persicae Semen have been evaluated on lipopolysaccharide (LPS)-induced release of nitric oxide (NO), prostaglandin $E_2\;(PGE_2)$ and tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$) by the macrophage RAW 264.7 cells. Amygdalin significantly inhibited generation of NO and $TNF-{\alpha}$ on LPS-stimulated RAW264.7 cells in a concentration-dependent manner. Consistent with these observations, the expression of inducible NO synthase (iNOS) enzyme was also inhibited by amygdalin in a concentration-dependent manner. However, amygdalin did not show any influence on the synthesis of $PGE_2$ and the expression of COX-2. Thus, this study suggests that amygdalin-mediated inhibition of iNOS expression, and $TNF-{\alpha}$ release may be one of the mechanisms responsible for the anti-inflammatory effects of Persicae Semen.

• Applied Biological Chemistry
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• 제40권4호
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• pp.283-288
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• 1997

1% linoleic acid를 함유하는 수용성 완충용액과 LDL(low-density lipoprotein, 1 mg protein/ml)을 함유하는 수용성 완충용액 각각에 $H_2O_2$와 $FeCl_2$를 가하여 유발된 산화과정 중 한국산 홍삼 extract(red ginseng extract; RGE)에 대한 산화방지활성을 비교물질로 ${\alpha}-tocopherol$을 사용하여, HPLC를 이용한 MDA(malondialdehyde) 정량법과 fluorometry를 이용하여 측정 비교하였다. LDL(0.25 mg protein/ml)에서 생성된 conjugated diene도 spectrometry로 측정하였다. Linoleic acid를 기질로 사용한 경우, MDA 생성량으로 비교한 산화방지효과에 있어서 1000 ppm RGE의 첨가로 71.8%의 우수한 산화저해율이 나타났으며, 이때 비교물질로 사용한 100 ppm ${\alpha}-tocopherol$의 경우에는 76.1%이었다. LDL(1 mg/ml)을 기질로 사용하였을 경우에는 RGE 200 ppm 첨가시 가장 우수한 항산화효과가 나타났으며, 이때의 산화저해율은 25.2%이었고, 100 ppm ${\alpha}-tocopherol$의 경우는 21.2%이었다. 또한 LDL(0.25 mg protein/ml)을 기질로 사용하여 생성된 c-diene을 측정한 경우에도 50 ppm RGE의 첨가로 44.2% 저해효과가 입증되었다.

• 약학회지
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• 제54권4호
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• pp.215-225
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• 2010

To investigate effects of pine essential oil isolated by steam distillation from Pinus densiflora needles (PN) and twigs (PT) on anti-oxidant and anti-aging activities, the experiments were carried out to determine anti-oxidant and antiaging activities on DPPH radical scavenging activity, NBT/xanthine oxidase-superoxide scavenging activity, silica-induced intracellular $H_2O_2$ and hydroxyl radical generation in RAW264.7 cells, hyaluronidase and elastase activities in vitro. Essential oil of PN and PT were contained 0.225 and 0.176 (w/v) %, respectively. PN was contained with 30 kinds of essential oil and its major constituent is $\alpha$-pinene (21.5%). Further PT was contained with 40 kinds of essential oil and its major constituent is $\beta$-pinene (22.4%) in GC/MS assay. Other essential oils of PN were $\beta$-pinene, camphene, myrcene, limonene, terpinolene, $\alpha$-terpineol, bornyl acetate, $\alpha$-copaene, caryophellene and humulene and PT were $\alpha$-pinene, camphene, phellandrene, limonene, terpinolene, $\alpha$-terpineol, bornyl acetate, $\alpha$-copaene, caryophellene and humulene. The essential oil of PT have more active than that of PN in anti-oxidant activity which has significant DPPH radical and superoxide scavenging activity, and significant inhibitory activities on silica-induced intracellular $H_2O_2$ and hydroxyl radical generation, as well as, significantly inhibited elastase and hyaluronidase activities. Further, phellandrene, myrcene and $\alpha$-pinene have DPPH radical and superoxide scavenging activities, $\beta$-pinene, terpinolene, myrcene and phellandrene inhibited silica-induced intracellular $H_2O_2$ and hydroxyl radical generations. And also phellandrene and $\beta$-pinene inhibited hyaluronidase and elastase activities. In conclusion, the essential oils isolated from PN and PT have anti-oxidant and anti-aging activities.

• 대한화장품학회지
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• 제32권4호
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• pp.241-247
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• 2006

본 연구는 피부에 안전하고 부작용이 없는 식물성 원료를 이용한 항염 소재를 개발하여 피부 진정 및 여드름, 아토피 피부에 적용되어질 수 있는 피부 자극 완화제를 개발하고자 하였다. 이에 따라 전통적으로 염증 질환 치료에 사용되어진 오동나무(Paulownia coreana Uyeki)를 소재로 하여 오동나무 잎 추출물의 항산화 효능과 항염 효능을 알아봄으로써 화장품 원료로의 가능성을 확인하였다. EPR을 이용하여 오동나무 잎 추출물의 superoxide anion radical 소거능을 확인하였으며 대식세포주에서의 LPS 처리에 의해 유도되어지는 NO의 생성을 저해시키는 효능을 확인하였다. 그 결과 추출물의 우수한 NO 생성 저해능을 확인하여 오동나무 잎 추출물의 항염 효능 메카니즘을 규명하였다. ELISA 기법을 이용하여 $PGE_2$ 생성 억제 효능을 확인하였으며 NO와 $PGE_2$ 생성 단백질인 iNOS와 COX-2의 발현 여부를 확인한 결과 오동나무 잎 추출물 처리에 의해 두 단백질의 발현이 확연히 감소되는 것을 확인하였다. 또한 염증 반응의 초기 단계에 관여하는 $IkB-{\alpha}$ 단백질의 분해정도를 시간별로 확인한 결과 LPS 처리 30 min 후 $IkB-{\alpha}$ 단백질의 분해가 일어나게 되는데 오동나무 잎 추출물을 함께 처리하였을 경우 시간이 경과되어도 $IkB-{\alpha}$ 단백질의 분해가 일어나지 않는 것을 확인하였다. 이로써 오동나무 잎 추출물의 항염 효능은 염증 반응 신호 전달의 초기 단계에 해당하는 $IkB-{\alpha}$ 단백질의 분해를 억제함으로써 결과적으로 NO와 $PGE_2$의 생성을 감소시킴을 확인하였다. 또한 CCD-986sk와 Raw 264.7 세포에 대한 세포 독성이 존재하지 않음을 확인함으로써 오동나무 잎의 항염 효능을 이용한 피부 자극완화제로서의 개발 가능성을 확인하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(4)
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• pp.133-138
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• 1996

For the application of hydrogenated amorphous silicon (a-Si:H) p-i-n structural diode as the alpha particle spectroscopy, the induced charge collection was simulated based on a relevant non-uniform charge generation model. The simulation was accomplished for two extreme cases of the incident direction of alpha particle, p-and n-side, respectively. As expected, for the complete charge collection, the hole collection should be severely considered due to its poor mobility and the full depletion bias required. For the comparison of signal corresponding to the detector configuration or structure, although n-i-p configuration shows a wider range of linearity to the energy, p-i-n configuration is more suitable in the viewpoint of linearity and signal value for the considering energy range.

• Reproductive and Developmental Biology
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• 제39권3호
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• pp.59-67
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• 2015

동물의 장기를 인간에게 이식하게 되면 초급성거부반응(Hyperacute rejection, HAR)이 일어난다. 초급성거부반응은 면역계의 구성요소 중 보체(complement)에 의해 일어나는 거부반응으로 돼지의 혈관세포 표면에 있는 $Gal{\alpha}$(1,3)Gal 당분자에 인간의 항체가 즉각 반응하기 때문에 일어나며, ${\alpha}1,3$-galactosyltransferase(${\alpha}1,3$-GT) 유전자는 돼지 혈관세포 표면의 $Gal{\alpha}$(1,3)Gal 당분자 생성에 관여한다. 따라서 인간에게 돼지의 장기를 이식하기 위해서는 ${\alpha}1,3$-galactosyltransferase 유전자를 제거하는 것이 필요한 것으로 알려져 있다. 본 연구실의 이전 연구에서, 시카고 미니돼지 귀체세포에서 상동 재조합(Homologous recombination)을 통해 ${\alpha}1,3$-galactosyltransferase 유전자가 제거된 체세포를 개발한 바 있으며, 이 체세포를 통하여 ${\alpha}1,3$-GT 유전자가 제거된 돼지도 생산된 바 있다. 본 연구에서는, human serum 처리 시 돼지 세포를 보호해 준다고 보고되고 있는 human complement regulator인 human Decay-accelerating factor(hDAF)와 human ${\alpha}1,2$-fucosyltransferase(hHT)유전자를 ${\alpha}1,3$-GT 유전자 위치에 gene targeting하여 동시에 hDAF와 hHT가 발현하는 체세포를 개발하였다. Knock-in vector는 hDAF와 hHT 두 유전자가 발현할 수 있도록 IRES로 연결하였으며, ${\alpha}1,3$-GT 유전자의 start codon을 이용하여 발현할 수 있도록 구축하였다. 구축한 vector는 electroporation을 통해 미니 돼지 체세포에 도입하였으며, PCR 결과, ${\alpha}1,3$-GT 유전자 위치에서 상동 재조합이 일어났음을 확인하였다. Positive-negative 선별 방법을 통해 얻은 gene targeting 된 체세포는 RT-PCR에 의해 hDAF와 hHT 유전자의 발현이 확인되었으며, 대조군(NIH minipig)에 비해 ${\alpha}1,3$-GT 유전자의 발현이 감소하였다. 또한 이들 세포에 100% human complement serum을 처리하였을 때 knock-in 세포가 대조군에 비해 30% 정도 더 높은 생존율을 보였다. 따라서 개발된 체세포는 이종간 장기이식을 위한 돼지 생산과 함께 이를 이용한 이종간의 장기 이식 시 초급성 거부반응을 억제하는 데 사용될 수 있을 것으로 생각된다.

• BMB Reports
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• 제44권7호
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• pp.462-467
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• 2011

Up-regulation of selected matrix metalloproteinases (MMPs) such as MMP-9 contributes to inflammatory processes during the development of various skin diseases, such as atopic dermatitis. In this study, we examined the effect of a cell-permeable superoxide dismutase (Tat-SOD) on TNF-${\alpha}$-induced MMP-9 expression in human keratinocyte cells (HaCaT). When Tat-SOD was added to the culture medium of HaCaT cells, it rapidly entered the cells in dose- and time-dependent manners. Tat-SOD decreased TNF-${\alpha}$-induced reactive oxygen species (ROS) generation. Tat-SOD also inhibited TNF-${\alpha}$-induced NF-${\kappa}B$ DNA binding activity. Treatment of HaCaT cells with Tat-SOD significantly inhibited TNF-${\alpha}$-induced mRNA and protein expression of MMP-9, as measured by RT-PCR and Western blot analysis. In addition, Tat-SOD suppressed TNF-${\alpha}$-induced gelatinolytic activity of MMP-9. Taken together, our results indicate that Tat-SOD can suppress TNF-${\alpha}$-induced MMP-9 expression via ROS-NF-${\kappa}B$-dependent mechanisms in keratinocytes, and therefore can be used as an immunomodulatory agent against inflammatory skin diseases related to oxidative stress.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1303-1309
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• 2018

In the present paper, we study the entropy analysis of boundary layer flow over a slender stretching sheet under the action of a non uniform magnetic field that is acting perpendicular to the flow direction. The effects of viscous dissipation and Joule heating are included in the energy equation. Using similarity transformation technique the momentum and thermal boundary layer equations to a system of nonlinear differential equations. Numerical solutions are obtained using the shooting and fourth-order Runge-Kutta method. The expressions for the entropy generation number and Bejan number are also obtained using a suggested similarity transformation. The main objective of this article is to investigate the effects of different governing parameters such as the magnetic parameter ($M^2$), Prandtl number (Pr), Eckert number (Ec), velocity index parameter (m), wall thickness parameter (${\alpha}$), temperature difference parameter (${\Omega}$), entropy generation number (Ns) and Bejan number (Be). All these effects are portrayed graphically and discussed in detail. The analysis reveals that entropy generation reduces with decreasing wall thickness parameter and increasing temperature difference between the stretching sheet and the fluid outside the boundary layer. The viscous and magnetic irreversibilities are dominant in the vicinity of the stretching surface.