INDUCTION OF MITOCHONDRIAL DNA DELETION BY IONIZING RADIATION IN HUMAN LUNG FIBROBLAST IMR-90 CELLS

엄현수,박혜란,정우희,조성기 대한방사선방어학회 2009 방사선방어학회지 Vol.34 No.2

Mitochondrial DNA (mtDNA) deletion is a well-known marker for oxidative stress and aging and also contributes to their unfavorable effects in cultured cells and animal tissues. This study was conducted to investigate the effect of ionizing radiation (IR) on mtDNA deletion and the involvement of reactive oxygen species (ROS) in this process in human lung fibroblast (IMR-90) cells. Young IMR-90 cells at population doubling (PD) 39 were irradiated with 137Cs -rays and the intracellular ROS level was determined by 2',7'-dichlorofluorescein diacetate (DCFH-DA) and mtDNA common deletion (4977bp) was detected by nested PCR. Old cells at PD 55 and H2O2-treated young cells were compared as the positive control. IR increased the intracellular ROS level and mtDNA 4977 bp deletion in IMR-90 cells dose-dependently. The increases of ROS level and mtDNA deletion were also observed in old cells and H2O2-treated young cells. To confirm the increased ROS level is essential for mtDNA deletion in irradiated cells, the effects of N-acetylcysteine (NAC) on IRinduced ROS and mtDNA deletion were examined. 5 mM NAC significantly attenuated the IR-induced ROS increase and mtDNA deletion. These results suggest that IR induces the mtDNA deletion and this process is mediated by ROS in IMR-90 cells.

Risk Assessment of Chemicals in Consumer Use

엄현수 한국공업화학회 2021 한국공업화학회 연구논문 초록집 Vol.2021 No.-

MITOCHONDRIAL DNA DELETION AND IMPAIRMENT OF MITOCHONDRIAL BIOGENESIS ARE MEDIATED BY REACTIVE OXYGEN SPECIES IN IONIZING RADIATION‐INDUCED PREMATURE SENESCENCE

엄현수,정우희,조성기,김영상 대한방사선방어학회 2011 방사선방어학회지 Vol.36 No.3

Mitochondrial DNA (mtDNA) deletion is a well‐known marker for oxidative stress and aging, and contributes to harmful effects in cultured cells and animal tissues. mtDNA biogenesis genes (NRF‐1, TFAM) are essential for the maintenance of mtDNA, as well as the transcription and replication of mitochondrial genomes. Considering that oxidative stress is known to affect mitochondrial biogenesis, we hypothesized that ionizing radiation (IR)‐induced reactive oxygen species (ROS) causes mtDNA deletion by modulating the mitochondrial biogenesis, thereby leading to cellular senescence. Therefore, we examined the effects of IR on ROS levels, cellular senescence, mitochondrial biogenesis, and mtDNA deletion in IMR‐90 human lung fibroblast cells. Young IMR‐90 cells at population doubling (PD) 39 were irradiated at 4 or 8 Gy. Old cells at PD55, and H2O2‐treated young cells at PD 39, were compared as a positive control. The IR increased the intracellular ROS level, senescence‐associated β‐galactosidase (SA‐β‐gal) activity, and mtDNA common deletion (4977 bp), and it decreased the mRNA expression of NRF‐1 and TFAM in IMR‐90 cells. Similar results were also observed in old cells (PD 55) and H2O2‐treated young cells. To confirm that a increase in ROS level is essential for mtDNA deletion and changes of mitochondrial biogenesis in irradiated cells, the effects of N‐acetylcysteine (NAC) were examined. In irradiated and H2O2–treated cells, 5 mM NAC significantly attenuated the increases of ROS, mtDNA deletion, and SA‐β‐gal activity, and recovered from decreased expressions of NRF‐1 and TFAM mRNA. These results suggest that ROS is a key cause of IR‐induced mtDNA deletion, and the suppression of the mitochondrial biogenesis gene may mediate this process.

층류 부상화염에서의 곡률효과

엄현수(Hyen Soo Um),박정(Jeong Park),하지수(Ji Soo Ha),김태권(Tae Kwon Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.6

Effects of lifted flame curvature on lift-off height in a nonpremixed laminar flame have been studied experimentally. The liftoff heights as a function of dilution ratio of helium gas, which is employed to vary the Schmidt number(Sc) of the fuel, were measured for small nozzle exit diameters of 0.12 and 0.25㎜. First, it is confirmed that, similar to the results of Chen, R.-H., et al.<SUP>(6)</SUP>, the flame liftoff height shows a variation with the dilution ratio of helium gas. Secondly, the liftoff height was founded to depend not only on the Schmidt number(Sc), types of fuel and dilution gas reported by Chen, R-H., et a1.<SUP>(6)</SUP>, but also on the nozzle diameter, which affects both the flame curvature and strain rate.

자외선 C에 의한 사람 적혈구 용혈에 대한 프로폴리스의 보호효과

엄현수(Hyeon-Soo Eom),유병선(Byung-Sun Yoo) 한국양봉학회 2006 韓國養蜂學會誌 Vol.21 No.1

노즐 직경 변화가 층류부상화염 거동에 미치는 영향

엄현수(Hyen Soo Um),김경호(Kyung Ho Kim),하지수(Ji Soo Ha),김태권(Tae Kwon Kim),박정(Jeong Park) 한국가스학회 2008 한국가스학회지 Vol.12 No.2

제트상사성 이론에 의해 잘 이해되어온 층류부상화염의 부상화염 거동에 대해 연료 노즐 직경 변화 효과를 통한 부력효과의 중요성을 밝히기 위한 실험적 연구를 수행하였다. 부력 효과를 평가하기 위해 연료노즐 직경을 0.1~6 mm 정도의 크기까지 변화시켰고, 헬륨을 희석제로 프로판과 메탄 화염을 순수 연료로부터 희석하면서 부상 거동을 체계적으로 관찰하였다. 부상화염 거동 설명을 위해 중요 물리 변수인 희석율로 표현되는 연료강도, 화염 스트레치, 화염 곡률 효과로 부상 거동을 체계적으로 설명하기 위해 척도 법칙(scaling law)을 통한 중요 물리 변수를 실험 변수로 유도하였다. 노즐 직경이 큰 경우와 연료 희석율이 큰 경우에 대해서는 부력 효과가 중요하다는 것을 실험 결과로부터 입증하였다. 또한, Chen 등의 결과에 따라 0.5 < Sc < 1에서 안정된 화염 부상이 존재하였던 점을 연료 노즐에 따라 평가하는 결과들이 제시된다. Experimental study was conducted to clarify the importance of buoyancy effects in laminar lifted flames which have been well understood by cold jet similarity theory. To evaluate buoyancy effects, lifted flame behaviors were systematically observed in methane and propane lifted flames diluted with He as changing the fuel nozzle diameter from 0.1 to 6 mm. Important physical parameters such as fuel strength, flame stretch and flame curvature, which were derived through simple physical scaling laws, were estimated. It is experimentally proven that buoyancy effects are important in relatively large fuel nozzle diameter and large fuel dilution with He. The results of Chen et al., which displayed the existence of stably lifted flames for 0.5 < Sc < 1, are also reviewed according to fuel nozzle diameter.

차량용 후드 힌지의 작동력 해석

엄현수(H. S. Eom),박현태(H. T. Park),안성진(S. J. Ahn),유영일(Y. I. Young),손인수(I. S. Son) 한국기계가공학회 2015 한국기계가공학회 춘추계학술대회 논문집 Vol.2015 No.4

BLDC 전동기를 이용한 차량용 파워 슬라이딩 도어의 구동 방법

문관영,엄현수,박영수 전력전자학회 2023 전력전자학회 논문지 Vol.28 No.2

This study proposes an operation method of power sliding door in vehicles using BLDC motor. The power sliding door in vehicles is a device for improving the convenience of the passenger. It is mainly used in the rear door of the van. A DC motor with an advantage of high starting torque is generally used to drive the power sliding door in vehicles. However, it has low durability due to commutator and brush for mechanical commutation. Therefore, the DC motor is unsuitable for the power sliding door in vehicles. Recently, research on power sliding door in vehicles using BLDC motor with high durability, high efficiency, and rapid dynamic response has been actively conducted. In this study, the operation method of power sliding door in vehicles using BLDC motor is presented. Its validity is also verified by simulation and experimental results.

In vitro and in vivo Biological Responses of Proton Irradiation from MC-50 Cyclotron

정우희,엄현수,정권,박혜란,조성기 한국방사선산업학회 2012 방사선산업학회지 Vol.6 No.3

In this study, we investigated the biological damage and stress responses induced byion beam (proton beam) irradiation as a basis for the development of protective measures againstspace radiation. We examined the biological effects of proton beam produced by MC-50 cyclotronat KIRAMS on the cultured cells and mice. The proton beam energy used in this study was 34.9MeV and the absorption dose rate for cells and mice were 0.509 Gy sec-1 and 0.65 Gy sec-1, respectively. The cell survival rates measured by plating efficiency showed the different sensitivity anddose-relationship between CHO cells and Balb/3T3 cells. HGPRT gene mutation frequency in Balb/3T3 was 15×10-6 Gy-1, which was similar to the reported value of X-ray. When stress signalingproteins were examined in Balb/3T3 cells, IκB-α decreased markedly whereas p53, phospho-p53,and Rb increased after proton beam irradiation, which implied that the stress signaling pathwayswere activated by proton beam irradiation. In addition, cellular senescence was induced in IMR-90 cells. In the experiments with C57BL/6 mouse, the immune cells (white blood cells, lymphocytes)in the peripheral blood were greatly reduced following proton beam irradiation whereas red bloodcells and platelets showed relatively little change. These results can be utilized as basic data forstudying the biological effects of proton beam using MC-50 cyclotron with respect to proton therapyresearch as well as space radiation research.

포천지역 계류 (부소천)의 수 질과 부 착조류 생물량에 온배수와 수소이온농도 (pH) 영향

전경혜,엄현수,정진호,황순진,신재기 한국수생태학회(구 한국하천호수학회) 2017 생태와 환경 Vol.50 No.1

Understanding effects of thermal pollution and acidification has long been a concern of aquatic ecologists, but it remains largely unknown in Korea. This study was performed to elucidate the effects of thermal wastewater effluent (TWE) and acid rain on water quality and attached algae in a small mountain stream, the Buso Stream, a tributary located in the Hantan River basin. A total of five study sites were selected in the upstream area including the inflowing point of hot-spring wastewater (HSW), one upstream site (BSU), and three sites below thermal effluent merged into the stream (1 m, 10 m and 300 m for BSD1, BSD2, and BSD3, respectively). Field surveys and laboratory analyses were carried out every month from December 2015 to September 2016. Water temperature ranged 1.7~28.8°C with a mean of 15.0°C among all sites. Due to the effect of thermal effluent, water temperature at HSW site was sustained at high level during the study period from 17.5°C (January) to 28.8°C (September) with a mean of 24.2±3.7°C, which was significantly higher than other sites. Thermal wastewater effluent also brought in high concentration of nutrients (N, P). The effect of TWE was particularly apparent during dry season and low temperature period (December~March). Temperature effect of TWE did not last toward downstream, while nutrient effect seemed to maintain in longer distance. pH ranged 5.1~8.4 with a mean of 6.9 among all sites during the study period. The pH decrease was attributed to seasonal acid rain and snow fall, and their effects was identified by acidophilic diatoms dominated mainly by Eunotia pectinalis and Tabellaria flocculosa during March and August. These findings indicated that water quality and periphyton assemblages in the upstream region of Buso Stream were affected by thermal pollution, eutrophication, and acidification, and their confounding effects were seasonally variable.