• 한국어병학회지
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• 제19권2호
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• pp.173-181
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• 2006

Miamiensis avidus는 넙치에 폐사를 일으키는 스쿠티카 섬모충이다. M. avidus에 대한 넙치의 면역반응을 측정하기 위하여 FKC (formalin killed cell)를 마리당 2.6 × 106 cells을 복강주사하고, FKC를 초음파처리한 것을 2.4 × 106 cells/㎖로 14.9 cm (26.8 g)의 넙치에 2주 간격으로 두 번 면역하였다. 면역한 넙치의 항체는 충체의 운동성둔화 (immobilization)와 응집 (agglutination)을 유발하였다. 면역한 그룹은 면역하지 않은 그룹보다 높은 ELISA항체가를 나타내었다. 또한, 복강주사로 면역한 넙치에서 유의적으로 높은 phagocytic ratio, phagocytic index와 주화활성을 나타내었다. FKC의 면역방어효과를 검증하기 위하여 8.6 cm (6.3 g)의 넙치에 마리당 1.43 × 105 cells을 복강주사면역하고 2.2 ×105 cells/㎖의 농도로 침지면역했다. 2주 간격으로 두 번 면역하고 2.0 × 104과 2.0 × 103 cells/㎖ 농도로 침지 공격 감염시킨 후 폐사율을 관찰하였다. 감염시킨 3주 후 폐사율은 복강주사구에서 감소하였고 침지면역구는 폐사가 지연되었다. 위의 결과로부터 M. avidus의 불활화백신을 넙치에 면역하면 충에 대한 특이면역이 증강되며 증강된 면역반응이 방어력을 제공했을 것으로 생각되었다.

• Journal of Radiation Protection and Research
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• 제28권3호
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• pp.233-237
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• 2003

It has been known that ATM plays a central role in response of cells to ionizing radiation by enhancing DNA repair. We have investigated the feasibility of increasing radiosensitivity of tumor cells with the use of ATM inhibitors such as caffeine, pentoxifylline and wortmannin. Human colorectal cancer RKO.C cells and RKO-ATM cells (RKO cells overexpressing ATM) were used in the present study. The clonogenic cell survival in vitro indicated that RKO-ATM cells were markdely radioresistant than RKO.C cells. Treatment with 3 mM of caffeine significantly increased the radiosensitivity of cells, particulary the RKO-ATM cells, so that the radiosensitivity of RKO.C cells and RKO-ATM cells were almost similar. The radiation induced G2/M arrest in RKO-ATM cells was noticeably longer than that in RKO.C cells and caffeine treatment significantly reduced the length of the radiation induced G2/M arrest in both RKO.C and RKO-ATM cells. Pentoxifylline and wortmannin were also less effective than caffeine to radiosensitize RKO.C or RKO-ATM cells. However, wortmannin was more effective than caffeine against human lung adenocarcinoma A549 cells indicating the efficacy of ATM inhibitor to increase radiosensitivity is cell line dependent. For in vivo study, RKO.C cells were injected s.c. into the hind-leg of BALB/C-nuslc nude mice, and allowed to grow to 130mm3 tumor. The mice were i.p. injected with caffeine solution or saline and the tumors irradiated with 10 Gy of X-rays. The radiation induced growth delay was markedly increased by 1-2 mg/g of caffeine. It was concluded that caffeine increases radiosensitivity of tumor cells by inhibiting ATM kinase function, thereby inhibiting DNA repair, that occurs during the G2/M arrest after radiation.

• Journal of Microbiology
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• 제45권1호
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• pp.34-40
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• 2007

In budding yeast, G2/M transition is tightly correlated with bud morphogenesis regulated by Swel and septin that plays as a scaffold to recruits protein components. BNI5 isolated as a suppressor for septin defect is implicated in septin organization and cytokinesis. The mechanism by which Bni5 regulates normal septin function is not completely understood. Here, we show that Bni5 phosphorylation is required for mitotic entry regulated by Swel pathway. Bni5 modification was evident from late mitosis to G1 phase, and CIP treatment in vitro of affinity-purified Bni5 removed the modification, indicative of phosphorylation on Bni5. The phosphorylation-deficient mutant of BNI5 (bni5-4A) was defective in both growth at semi-restrictive temperature and suppression of septin defect. Loss of Bni5 phosphorylation resulted in abnormal bud morphology and cell cycle delay at G2 phase, as evidenced by the formation of elongated cells with multinuclei. However, deletion of Swel completely eliminated the elongated-bud phenotypes of both bni5 deletion and bni5-4A mutants. These results suggest that the bud morphogenesis and mitotic entry are positively regulated by phosphorylation-dependent function of Bni5 which is under the control of Swel morphogenesis pathway.

• Preventive Nutrition and Food Science
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• 제15권4호
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• pp.255-261
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• 2010

Ischemic stroke, a major cause of death and disability worldwide, is caused by occlusion of cerebral arteries that, coupled with or without reperfusion, results in prolonged ischemia (hypoxia and hypoglycemia) and, ultimately, brain damage. In this study, we examined whether methanol extract of the whole plant of Cassia mimosoides var. nomame Makino that grows naturally in Korea, as well as Japan and China, and some of its fractions obtained by partitioning with organic solvents could protect human hepatocellular carcinoma cells (HepG2) under hypoxic condition by inhibiting apoptosis. We also investigated if these extracts could attenuate brain damage in a rat model of 2 hr of ischemia, generated by middle cerebral artery occlusion, and 22 hr of reperfusion. The whole extract ($100{\mu}g$/mL) maintained the cell number at more than half of that initially plated, even after 24 hr of cell culture under hypoxic condition (3% $O_2$). In the absence of the whole extract, almost all of the cells were dead by this time point. This improvement of cell viability came from a delay of apoptosis, which was confirmed by observing the timing of the formation of a DNA ladder when assessed by gel electrophoresis. Of fractions soluble in hexane, ethyl acetate (EA), butanol and water, EA extracts were selected for the animal experiments, as they improved cell viability at the lowest concentration ($10{\mu}g$/mL). The whole extract (200 mg/kg) and EA extract (10 and 20 mg/kg) significantly reduced infarct size, a measure of brain damage, by 34.7, 33.8 and 45.2.0%, respectively, when assessed by 2,3,5-triphenyl tetrazolium chloride staining. The results suggest that intake of Cassia mimosoides var. nomame Makino might be beneficial for preventing ischemic stroke through inhibition of brain cell apoptosis.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.957-967
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• 2017

첨가제와 점화 보조제가 적용된 고체연료 램젯 용 연료 그레인의 연소시험을 수행하여 점화 지연과 연소 효율을 확인하였다. 연료 그레인은 HTPB에 AP 파우더 15 wt.% 보론 입자 5 wt.%가 혼합된 형태로 구성되어 있다. 연료 그레인에 $NC/BKNO_3$와 Composite 추진제로 이루어진 점화보조제를 도포하여 우수한 점화성능을 확보하였다. 에탄올 블렌딩 과산화수소 가스발생기를 통해 램젯 연소실의 공기와 가깝도록 온도, 압력, 산소 조성을 조절한 산화제 가스를 유속 $200kg/m^2s$ 으로 흐르도록 설정하였다. 실험 결과, 점화보조제의 작동을 통해 연료그레인에서 0.5초의 점화 지연시간을 파악하였다. 또한 보론의 연소를 통해 8 bar의 일정한 연소실 압력과 0.86의 높은 연소 효율을 확인하였다.

• 천문학회보
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• 제41권1호
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• pp.70.4-71
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• 2016

The links between super-massive black hole masses and their host galaxy properties are observed, indicating that black hole growth and host galaxy evolution are closely related. Reverberation mapping, which uses the time delay from the central black hole to broad line regions, is one of the best methods to estimate masses of black holes of active galactic nuclei (AGNs). However, only masses of about 50 black holes have been determined in reverberation mapping studies so far, and most of them are limited to optical luminosities below 10^45 erg/s due to the challenges of long-term time domain observations in both photometry and spectroscopy. In this project, we expand reverberation mapping samples to higher luminosities of > 10^44.5 erg/s at 0.1 < z < 0.35, that have expected time lags of 40 - 250 light days. Photometric (using LOAO 1-m and MDM 1.3-m) and spectroscopic (using MDM 2.4-m and Lick 3-m) monitoring campaigns are being conducted for a 3 year duration and 20 day cadence. Precedent photometric observations in 2015B show some targets with variability and follow-up spectroscopic observations are on-going. In this presentation, we introduce our project, present reverberation mapping simulation results, and preliminary results on photometry. These reverberation mapping masses of relatively high luminous AGNs will provide a strong constraint on black hole mass calibration, e.g., the single-epoch mass estimation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.479-481
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• 2006

This paper describes a 2.5V, 320MHz low-noise and low-power Phase Locked Loop(PLL) using a noise-rejected Voltage Controlled ring Oscillator(VCO) fabricated in a TSMC 0.25um CMOS technology. In order to improve the power consumption and oscillation frequency of the PLL, The VCO consist of three-stage fully differential delay cells that can obtain the characteristic of high speed, low power and low phase noise. The VCO operates at 7MHz -670MHz. The oscillator consumes l.58mA from a 320MHz frequency and 2.5V supply. When the PLL with fully-differential ring VCO is locked 320MHz, the jitter and phase noise measured 26ps (rms), 157ps (p-p) and -97.09dB at 100kHz offset. We introduce and analysis the conditions in which ring VCO can oscillate for low-power operation.

• 생명과학회지
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• 제27권1호
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• pp.32-37
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• 2017

Cyanidin-3-O-glucoside (C3G)는 오디와 붉은색의 과일에 풍부하게 함유되어 있으며, 항염증과 항산화 효과와 관련하여 보고되어있다. 그러나, C3G의 식후 혈당에 관한 연구 결과는 보고되지 않았다. ${\alpha}-glucosidase$ 억제제는 소장에서 탄수화물 소화의 속도를 방해함으로써 식후 고혈당을 조절한다. 본 연구에서는 C3G가 ${\alpha}$-글루코시다아제와 ${\alpha}$-아밀라아제에 미치는 억제효과 및 스트렙토조토신(STZ)이 유발하는 당뇨병 생쥐의 식후고혈당에 미치는 완화 효과를 조사하였다. ICR 마우스와 streptozothocin (STZ)으로 유도된 당뇨병 마우스에 수용성 전분(2 g/kg body weigh)으로 경구부하 후 C3G (10 mg/kg body weight) 또는 acarbose (10 mg/kg body weight)를 단독 또는 함께 투여하였다. 혈액 샘플은 꼬리에서 0, 30, 60, 120분 간격으로 채취하였다. ${\alpha}$-글루코시다아제와 ${\alpha}$-아밀라아제에 대한 C3G의 $IC_{50}$ 값은 각각 13.72와 $7.5\;{\mu}M$의 결과값을 나타내어, 양성대조군인 acarbose보다 더 효과적이었다. STZ으로 유발된 당뇨 쥐의 식후 혈당 수치는 대조군에 비해 C3G 투여시 유의적으로 더 낮았다. 게다가, C3G 투여는 당뇨병 흰쥐에서 포도당 반응에 대한 곡선하면적 감소와 관련이 있었다. 그러므로, C3G는 ${\alpha}$-글루코시다아제의 강력한 억제제이며 식이 탄수화물의 흡수를 지연시킬 수 있음을 나타낸다.

• Asian-Australasian Journal of Animal Sciences
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• 제14권9호
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• pp.1216-1220
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• 2001

Effect of hydroquinone (HQ) on rumen urease activity was studied. Hydroquinone at concentrations of 0.01 ppm, 0.1 ppm, 1 ppm, and 10 ppm inhibited urease activity of intact rumen microbes in vitro by 25%, 34%, 55% and 64% respectively. In the presence of low concentrations of $\beta$-mercaptoethanol, rumen urease could be solubilized and partially purified. The Km for the enzyme was $2{\times}10^{-3}$ M with Vmax of $319.4{\mu}moles/mg$ min. The kinetics of inhibition with partially purified rumen urease was investigated. The result showed that the inhibitory effect was not eliminated by increasing urea concentrations indicating a noncompetitive effect in nature with an inhibition constant $1.2{\times}10^{-5}$ M. Hydroquinone at the concentration of 10 ppm produced 64% urease inhibition, did not affect ruminal total dehydrogenase and proteolytic enzyme (p>0.05), but increased cellulase activity by 28% (p<0.05) in vitro. These results indicated that hydroquinone was a effective inhibitor of rumen urease and could effectively delay urea hydrolysis without a negative effect. The inhibitor appeared to offer a potential to improve nitrogen utilization by ruminants fed diets containing urea.

• Korean Chemical Engineering Research
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• 제43권4호
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• pp.503-510
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• 2005

본 연구는 졸-겔법을 이용하여 복합 알루미나를 제조하였고, 다양한 첨가제의 첨가에 의한 복합 알루미나의 열적 안정성을 고찰하였다. $1,200^{\circ}C$에서 소성시킨 복합 알루미나의 열적 안정성은 사용된 첨가제에 따라서 $Si{\fallingdotseq}La$ > Ti > $Ba{\fallingdotseq}Ce$ > Y > $Zr{\fallingdotseq}Mg$ 순으로 나타났다. 특히 실리카 첨가시 ${\alpha}$-알루미나로의 상전이 온도를 $150^{\circ}C$이상 높여 $1,200^{\circ}C$에서 소성 후에도 ${\gamma}$-형에서 ${\delta}$-형의 알루미나 상을 유지함을 알 수 있었고, 비표면적이 $3m^2/g$인 ${\alpha}$-알루미나에 비해 $71m^2/g$(비표면적) 범위까지 증가됨을 보였다. 이러한 알루미나 입자의 특성변화는 실리카 첨가 알루미나의 경우 고온으로 소성시 Si-O-Al의 결합의 증가로 인하여 알루미나의 상전이를 지연시키는 결과로 나타나고, 란타늄 첨가 알루미나의 경우 $LaAlO_3$ 구조의 존재로 인해 알루미나의 입자간 소결을 지연시킴을 알 수 있었다. 또한 란타늄 첨가시 $1,000^{\circ}C$ 이하에서 소성시킨 경우 란타늄이 알루미나 표면에 $La_2O_3$ 구조로 존재하나 $1,000^{\circ}C$ 이상에서는 $LaAlO_3$의 perovskite 구조로 존재하고, $1,300^{\circ}C$ 이상에서는 $LaAl_{11}O_{18}$의 magneto-plumbite 구조로 존재함을 XRD와 XPS 분석 결과에 의해 확인할 수 있었다.