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허재혁,원혜연,임동규,김정희,김희태,안진영,Heo, Jae-Hyeok,Won, Hye-Yeon,Im, Dong-Gyu,Kim, Jung-Hee,Kim, Hee-Tae,Ahn, Jin-Young The Korean Society of Clinical Neurophysiology 2015 Annals of Clinical Neurophysiology Vol.17 No.2
Background: The effects of omega-3 polyunsaturated fatty acids (PUFAs) on cerebral vessels have not been clarified until now. Thus we investigated the efficacy of omega-3 PUFAs supplementation on cerebral blood flow velocity and vascular resistance via transcranial doppler (TCD). Methods: Consecutive twenty patients (13 male and 7 female) with at least 1 cerebrovascular risk factor or a known cerebrovascular disease were enrolled. Patients were treated with omega-3 PUFAs (1 g, two times per day) for 12 weeks. Cerebral blood flow velocity, resistance index, and pulsatile index were checked before and after 12 weeks of treatment using TCD. Results: The change of resistance index in right MCA (from $0.58{\pm}0.07$ to $0.55{\pm}0.07$, p = 0.042) and left PCA (from $0.56{\pm}0.07$ to $0.53{\pm}0.06$, p = 0.037) showed significant improvement after 12 weeks of omega-3 PUFAs treatment. The changes in other vessels, however, failed to show any significant changes compared to the baseline. Conclusions: Omega-3 PUFAs treatment showed feasible efficacies for cerebral vascular resistances in this open label trial. To confirm these results, larger samples of patients and longer period of follow-up is warranted.
티타늄 평활관 및 전열촉진관에서 R-l34a의 관외측 풀비등 열전달 특성에 대한 연구
허재혁,윤린,정진택,문영준,김용찬,Heo Jae-Hyeok,Yun Rin,Chung Jin-Taek,Moon Young-lune,Kim Yongchan 대한기계학회 2005 大韓機械學會論文集B Vol.29 No.7
Pool boiling heat transfer characteristics of R-134a were investigated in titanium plain and low finned tubes. The diameter of test tube was 15.88 mm and the fin density was 33 fpi. Tests were conducted at saturation temperatures of $20^{\circ}C$ and $30^{\circ}C$. Heat fluxes varied from 5000 W/$m^2$ to 50,000 W/$m^2$ based on surface area of the plain tube. The pool boiling heat transfer coefficients of the titanium horizontal plain tube are lower than those of the copper plain tube by $8.2\%$. The boiling heat transfer coefficients of the low finned tube are averagely higher than those of the plain tubes by $34\%$. The average deviation of the Slipcevic correlation from the present data for the low finned tube is $20\%$.
오미자칠해목 추출물의 과산화수소로 유발된 PC12뇌세포 사멸과 스코폴라민으로 유발된 렛드 동물모델에 대한 개선 효과
박은국,한경훈,허재혁,김남기,배문형,서영하,용윤중,정선용,최춘환,Park, Eun-kuk,Han, Kyung-Hoon,Heo, Jae-Hyeok,Kim, Nam-Ki,Bae, Mun-Hyoung,Seo, Young-Ha,Yong, Yoon-joong,Jeong, Seon-Yong,Choi, Chun-Whan 한국식품영양학회 2020 韓國食品營養學會誌 Vol.33 No.3
Cognitive impairment is considered to be key research topics in the field of neurodegenerative diseases and in understanding of learning and memory. In the present study, we investigated neuroprotective effects of Schisandra chinensis (SC) and Ribes fasciculatum (RF) extracts in hydrogen peroxide-induced neuronal cell death in vitro and scopolamine-induced cognitive impairment in Sprague Dawley<sup>®</sup> (SD) rat in vivo. Apoptotic cell death in neuroblastic PC12 cell line was induced by hydrogen peroxide for 1 hour at 100 μM. However, mixture of SC and RF treatment prevented peroxide induced PC12 cell death with no neurotoxic effects. For in vivo experiment, the effect of SC and RF extracts on scopolamine-induced cognitive impairment in SD rat was evaluated by spontaneous alternation behavior in Y-Maze test. After 30 min scopolamine injection, the scopolamine-induced rats presented significantly decreased % spontaneous alteration and acetylcholine level, compared to non-induced group. However, treatment of SC+RF extracts rescued the reduced % spontaneous alteration with acetylcholine concentration from hippocampus in scopolamine-induced rats. These results suggested that mixture of SC and RF extract may be a potential natural therapeutic agent for the prevention of cognitive impairment.
이현종(Hyun-Jong Lee),허재혁(Heo-Jae Hyeok),황두성(Doosung Hwang) 한국컴퓨터정보학회 2018 한국컴퓨터정보학회 학술발표논문집 Vol.26 No.1
서명기반 악성코드 탐지는 악성 파일의 고유 해싱 값을 사용하거나 패턴화된 공격 규칙을 이용하므로, 변형된 악성코드 탐지에 취약한 단점이 있다. 기계 학습을 적용한 악성코드 탐지는 이러한 취약점을 극복할 수 있는 방안으로 인식되고 있다. 본 논문은 정적 분석으로 n-gram과 API 특징점을 추출해 특징 벡터로 구성하여 XGBoost, k-최근접 이웃 알고리즘, 지지 벡터 기기, 신경망 알고리즘, 심층 학습 알고리즘의 일반화 성능을 비교한다. 실험 결과로 XGBoost가 일반화 성능이 99%로 가장 우수했으며 k-최근접 이웃 알고리즘이 학습 시간이 가장 적게 소요됐다. 일반화 성능과 시간 복잡도 측면에서 XGBoost가 비교 대상 알고리즘에 비해 우수한 성능을 보였다.
박민호,원혜연,임동규,변경민,허재혁,Park, Min-Ho,Won, Hye-Yeon,Im, Dong-Gyu,Byeon, Kyoung-Min,Heo, Jae-Hyeok 대한임상신경생리학회 2015 Annals of Clinical Neurophysiology Vol.17 No.2
Syncopes are the most common non-epileptic attacks mimicking epileptic seizures. Among them, cardiogenic syncope is potentially life threatening. A 49 year old man was refered for the recurrent episodes of loss of consciousness with tonic posture and upward eyes deviation. The electrocardiogram showed polymorphologic ventricular tachycardia during attacks, which normalized after that. He was treated with isoproterenol and symptoms subsided. Here, we report a case of ventricular tachycardia manifested as epileptic seizures.
스트렙토조토신으로 유도된 신경세포사멸에서 비타민 C의 보호 기전 연구
이승희,한경훈,김현준,박광성,한성희,김정희,허재혁,Lee, Seung-Hee,Han, Kyung-Hoon,Kim, Hyun-Jun,Park, Kwang-Sung,Han, Sung-Hee,Kim, Jung-Hee,Heo, Jae-Hyeok 한국식품영양학회 2018 韓國食品營養學會誌 Vol.31 No.4
In this study, we analyzed the protective effects of the vitamin C in the streptozotocin (STZ)-induced apoptosis using the SH-SY5Y, a neuroblastoma cell line. The cells were pretreated with the vitamin C ($100{\mu}g$) for 30 min, followed by the 24-hr treatment with the 2.5-mM STZ. The cell-viability assay using the Cell Counting Kit (CCK)-8 revealed the cell-survival rate increased by 15% following the vitamin-C pretreatment compared to the STZ-only treatment. Moreover, we conducted the western-blot analysis to determine the protective effect of the vitamin C regarding the apoptosis. Compared to those in the STZ-only-treatment group, the p-ERK and Bcl-2 expressions increased in the vitamin-C-pretreatment group, whereas the p-JNK and Bax expressions decreased. The vitamin-C pretreatment increased the expression of the SOD-1, an antioxidant enzyme, by more than 30%, indicating its protective role in the STZ-induced oxidative stress. Also, we found both the intrinsic- and extrinsic-pathway mechanisms of the STZ-induced apoptosis. The results of this study $s{\mu}ggest$ vitamin C may help prevent the neurodegenerative diseases.
산화적 스트레스에 대한 여주 (Momordica charantia) 추출물의 항산화 효과 및 세포사멸 억제 기전을 통한 신경세포보호효과
김꽃별(Kkot Byeol Kim),이선아(Seonah Lee),허재혁(Jae Hyeok Heo),김정희(Jung hee Kim) 한국영양학회 2017 Journal of Nutrition and Health Vol.50 No.5
건 여주로부터 얻은 70%에탄올 추출물의 항산화 효과를 측정하고, H₂O₂에 의해 유도된 산화적 스트레스에 대한 신경세포 보호효과를 알아보기 위해 human neuroblastoma cell인 SK-N-MC세포를 이용하여 실험을 수행하였다. 여주 추출물의 총 폴리페놀과 플라보노이드 함량은 각각 28.51 mg gallic acid/extract g과 3.95 mg catechin/extract g 이었고, 추출물의 DPPH 라디칼 소거능 (IC50)은 506.95 μg/ml 이었다. 여주추출물을 신경세포에 전 처리한 후 H₂O₂을 처리하여 산화적 스트레스를 유도했을 때, 여주 추출물에 의해 세포생존율은 증가되었고 세포내 ROS는 감소되는 것을 확인하였다. 그리고 세포내 항산화 방어시스템인 항산화효소 (SOD-1,2와 GPx-1)의 mRNA 발현이 여주추출물 처리에 의해 control 수준으로 회복되거나 control 보다 증가되는 결과를 보였으며, ROS 의존적 세포사멸과 연관 있는 것으로 알려진 MAPK pathway 중 p38과 JNK의 인산화를 여주추출물이 억제하였다. 또한 cleaved caspase-3와 cleaved PARP의 발현도 여주추출물의 처리에 의해 감소되었다. 본 연구 결과에서 70% 에탄올 여주추출물은 항산화효능이 우수하여 ROS를 직접적으로 제거할 뿐 아니라 세포내 ROS 축적을 억제시키는 효과를 보여주었다. 그리고 신경세포 내 항산화효소들의 발현 증가 기전과 p38, JNK의 인산화 억제 및 cleaved caspase-3, cleaved PARP의 발현 억제를 통한 세포사멸 억제 기전을 통해 산화적 스트레스로부터 신경세포를 보호하는 효과가 있음을 제시하고 있다. 따라서 여주추출물은 산화적 스트레스에 의한 알츠하이머병이나 파킨슨병 등과 같은 신경변성질환 (neurodegenerative disease)에 대한 예방 및 치료제의 소재로써 이용가치가 충분한 것으로 사료된다. Purpose: Many studies have suggested that neuronal cells protect against oxidative stress-induced apoptotic cell death by polyphenolic compounds. We investigated the neuroprotective effects and the mechanism of action of Momordica charantia ethanol extract (MCE) against H₂O₂-induced cell death of human neuroblastoma SK-N-MC cells. Methods: The antioxidant activity of MCE was measured by the quantity of total phenolic acid compounds (TPC), quantity of total flavonoid compounds (TFC), and 2,2-Diphenyl-1-pycrylhydrazyl (DPPH) radical scavenging activity. Cytotoxicity and cell viability were determined by CCK-8 assay. The formation of reactive oxygen species (ROS) was measured using 2,7- dichlorofluorescein diacetate (DCF-DA) assay. Antioxidant enzyme (SOD-1,2 and GPx-1) expression was determined by real-time PCR. Mitogen-activated protein kinases (MAPK) pathway and apoptosis signal expression was measured by Western blotting. Results: The TPC and TFC quantities of MCE were 28.51 mg gallic acid equivalents/extract g and 3.95 mg catechin equivalents/extract g, respectively. The IC50 value for DPPH radical scavenging activity was 506.95 μg/ml for MCE. Pre-treatment with MCE showed protective effects against H₂O₂-induced cell death and inhibited ROS generation by oxidative stress. SOD-1,2 and GPx-1 mRNA expression was recovered by pre-treatment with MCE compared with the presence of H₂O₂. Pre-treatment with MCE inhibited phosphorylation of p38 and the JNK pathway and down-regulated cleaved caspase-3 and cleaved PARP by H₂O₂. Conclusion: The neuroprotective effects of MCE in terms of recovery of antioxidant enzyme gene expression, down-regulation of MAPK pathways, and inhibition apoptosis is associated with reduced oxidative stress in SK-N-MC cells.