Effects of Organotin Compounds on Follicular Steroidogenesis in Frogs

Kwon Hyuk-Bang,Kim Seung-Chang,Kim An-Na,Lee Sung-Ho,Ahn Ryun-Sup 한국발생생물학회 2009 발생과 생식 Vol.13 No.3

Some organotin compounds such as butyltins and phenyltins are known to induce impo-sex in various marine animals and are considered to be endocrine disruptors. In this study, the effect of organotins on follicular steroidogenesis in amphibians was examined using ovarian follicles of Rana dybowskii and Rana catesbeiana. Isolated follicles were cultured for 6 or 18 h in the presence and absence of frog pituitary homogenate (FPH) or various steroid precursors, and the levels of product steroids in the culture media oassay. Among the butyltin compounds, tributyltin (TBT) strongly and dose-dependently inhibited the FPH-induced synthesis of pregnenolone () and progesterone () by the follicles. TBT also strongly suppressed the conversion of cholesterol to and partially suppressed the conversion of to . A high concentration of dibutyltin (DBT) also inhibited steroidogenesis by the follicles while monobutyltin and tetrabutyltin had negligible effects. The toxic effect of TBT or DBT was irreversible and a short time of exposure (30 min) was enough to suppress steroidogenesis. All the phenyltin compounds significantly inhibited FPH-induced synthesis by the follicles. The effective dose of 50% inhibition by diphenyltin was and those of monophenyltin and triphenyltin were and , respectively. However, none of the phenyltin compounds significantly suppressed the conversion of to -hydroxyprogesterone (-OHP) (by -hydroxylase), -OHP to androstenedione (AD) (by lyase), or AD to testosterone by the follicles. Taken together, the data show that among the steroidogenic enzymes, P450scc in the follicles is the most sensitive to organotin compounds and that an amphibian follicle culture system can be a useful screening model for endocrine disruptors.

Effects of Puromycin and Actinomycin D on the HCG-Induced Expansion of Cumulus Oophorus in vitro

Kwon, Hyuk-Bang The Korean Society for Integrative Biology 1983 동물학회지 Vol.26 No.4

哺乳動物의 排卵時 濾胞卵子의 成熟再開와 더불어 卵子를 緻密하게 둘러싸고 있는 卵子細胞들의 分散이 일어난다. 이 現象은 生殖巢刺戟호르몬의 促進을 받은 卵丘細胞들이 細胞間隔에 多量의 뮤코量을 分泌함으로써 이루어지는데 이 때 cAMP가 第二 傳達者로 作用을 한다고 알려져 있다. 본 實驗에서는 卵子-卵丘 複合體를 培養하면서 HCG (10 IU/ml)에 의해 誘導된 卵丘細胞의 分散에 puromycin과 actinomycin D가 미치는 영향을 調査한 바 다음과 같은 缺課를 얻었다. 1. Puromycin은 2 $\\mu$g/ml의 濃度에서 卵丘細胞의 分散을 현저히 抑制하였으며 이 效果는 可逆的이었다. 2. Puromycin의 分散抑制效果는 HCG의 刺戟기간 (3시간) 뿐 아니라 뮤코量의 合成時期 ($3\\sim18$시간)에서도 나타났다. 3. Actinomycin D는 0.025 $\\mu$g/ml의 濃度에서부터 卵丘細胞의 分散을 抑制하기 시작했다. 4. Actinomycin D의 分散抑制效果는 부분적인 可逆性을 나타내었으며 0.1 $\\mu$g/ml의 濃度에서는 非可逆的인 災害效果를 나타내었다. 위의 缺課로부터 HCG의 卵丘細胞 分散誘導過程에는 蛋白質 내지 RNA의 合成過程이 관여하는 것으로 測定되며 따라서 cAMP는 轉寫 내지 解讀水準에서 卵丘細胞의 分散을 調節하는 것 같다. In order to know the mode of the action of gondotrophic hormone on the expansion of cumuli oophori, oocyte-cumulus complexes isolated from Graafian follicles of mice were stimulated to expand in vitro with human chorionic gonadotrophin (HCG), and the effects of puromycin and actinomycin D on the expansion were examined. THe complexes were cultured in medium TC 199 containing 10% bovine serum in the presence or absence of HCG and the inhibitors. Puromycin in the medium (0.5-4 $\\mu$g/ml) suppresseed the HCG-induced cumulus expansion dose-dependently. This effect of puromycin was reversible. Puromycin affected the complexes throughout the HCG-stimulating stage (3 hours) and hyaluronic acid synthesis stage (3-18 hours). Actinomycin D also inhibited the expansion of the cumulus from the concentration of 0.025 $\\mu$g/ml. But the effect of actinomycin D was not completely reversible and the drug appeared to give an irreversible damage to the complexes at 0.1 $\\mu$g/ml. From the above results, it is suggested that RNA or protein synthesis is involved in the process in which HCG stimulates the cumulus cells to expand therefore cAMP elevated by te gonadotrophin may control expansion at the transcriptional or translational level.

MODELING THE HYDRAULIC CHARACTERISTICS OF A FRACTURED ROCK MASS WITH CORRELATED FRACTURE LENGTH AND APERTURE: APPLICATION IN THE UNDERGROUND RESEARCH TUNNEL AT KAERI

Bang, Sang-Hyuk,Jeon, Seok-Won,Kwon, Sang-Ki Korean Nuclear Society 2012 Nuclear Engineering and Technology Vol.44 No.6

A three-dimensional discrete fracture network model was developed in order to simulate the hydraulic characteristics of a granitic rock mass at Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT). The model used a three-dimensional discrete fracture network (DFN), assuming a correlation between the length and aperture of the fractures, and a trapezoid flow path in the fractures. These assumptions that previous studies have not considered could make the developed model more practical and reasonable. The geologic and hydraulic data of the fractures were obtained in the rock mass at the KURT. Then, these data were applied to the developed fracture discrete network model. The model was applied in estimating the representative elementary volume (REV), the equivalent hydraulic conductivity tensors, and the amount of groundwater inflow into the tunnel. The developed discrete fracture network model can determine the REV size for the rock mass with respect to the hydraulic behavior and estimate the groundwater flow into the tunnel at the KURT. Therefore, the assumptions that the fracture length is correlated to the fracture aperture and the flow in a fracture occurs in a trapezoid shape appear to be effective in the DFN analysis used to estimate the hydraulic behavior of the fractured rock mass.

시간평균 홀로그래픽 간섭계를 이용한 진동판의 미소 변위 측정

房香伊,權進赫 嶺南大學校 基礎科學硏究所 1993 基礎科學硏究 Vol.13 No.-

Time- average holographic interferometry was used to measure the vibrational displacement of the speaker with the light source He-Ne laser 5mW. The vibrating obiect was the aluminum plate of the thickness 0.05mm that was attached in front of a speaker. The vibration frequency was waried between 200Hz and 2500Hz. Each vibrating mode pattern was compared to the other patterns. With the increase fo the frequency, the difference between the theory and experiment had been steadily increased. That dependended on the tension of the plate and the instability of the system. In each mode, we could measure the small displacement of the vibration and the observed values were coincided the theoretical values.

고주파 치료기를 사용한 치핵치료에 대한 만족도 조사

권기범,구창훈,권혁중,김경곤,윤방부,이건오,노광수 대한가정의학회 2001 Korean Journal of Family Medicine Vol.22 No.7

생쥐 초기배아에 미치는 스테로이드 홀-몬의 영향

권혁방,정순오 최신의학사 1976 最新醫學 Vol.19 No.2

The experiments were undertaken in order to study the effect of various steroid hormones on germinal vesicle break-down of mouse oocytes and to determine if there was a different sensitivity of various aged preimplantation mouse embryos to progesterone. Follicular oocytes were obtained from ovaries of A-strain female mouse and early embryos were flushed from their fallopian tubes after an appropriate time of mating. The incubation medium was a modified Krebs-Ringer bicarbonate sol. supplemented with 0.4% bovine serum alumin (BSA). A microtube culture method (Cho, 1974) for the oocytes and embryos were adopted to avoid contamination of steroid hormones which are soluble in oil. Ten to twenty oocytes or embryos were placed in the culture medium in microtube and cultured at 37°C, gassed with 5% CO2 in air humidified in an incubator. After culture, the oocytes or embryos were observed directly through the microtube under an inverted phase microscope. The results from the experiments were as follows. 1. The activity of the steroid hormones on germinal vesicle break-kown of mouse oocytes was dependent upon specificity of the hormones. 2. Oocyte was very resistant to progesterone in germinal vesicle break-down whereas fertilized ova was very sensitive to that by blocking the development of the embryos, from 1-cell to 2-cell stage. 3. When 1-cell, 2-cell, 8-16 cell embryos were cultured for 24 hours in medium containing progesterone, 8-16 cell embryos were more resistant to progesterone than the others in cleavage inhibition. 4. When the embryos were exposed to progesterone long, they became more sensitive to the hormone.

국면전환 로그노말 모형 하에서의 옵션가격에 대한 소고

고방원 ( Bang Won Ko ),권혁성 ( Hyuk Sung Kwon ) 한국계리학회 2010 계리학연구 Vol.2 No.1

Weldability of Aluminum Alloy and Hot Dip Galvanized Steel by AC Pulse MIG Brazing

Yong-Hyuk Kwon,Sol-Choi,Hye-Seul Yoon,Hee-Seon Bang 대한용접·접합학회 2021 대한용접·접합학회지 Vol.39 No.2

This study investigates the weldability of dissimilar materials, such as Al6061-T6 aluminum alloy and hot dip galvanized (GI) steel, via AC pulse metal inert gas (MIG) brazing. Notably, the brazing mechanism was investigated for different electrode negative (EN) ratios. The results showed that as the amount of deposition increased with the EN ratio, throat thickness, wetting length, and leg length also tended to increase. Furthermore, it was confirmed that as the EN ratio increased, a thin intermetallic compound (IMC) layer was deposited due to the suppression of IMC growth caused by the low heat input at the joint interface.

Programmable Image Codec Using Data Flow Architecture for MPEG , JPEG and H.261

Lee, Bang Won,Kwon, Hyuk S. 대한전자공학회 1993 ICVC : International Conference on VLSI and CAD Vol.3 No.1

Digital video compression and decompression play an important role of multimedia applications. Many digital video processors are proposed to satisfy international standards such as 1PEG, MPEG, and H.261. In this paper, a programmable digital video processor based on a static data flow architecture is described. Since each modularized processing element in this proposed architecture operates asynchronously in data-driven scheme, the peak computational capability that is given as summation of computing capability of individual processing unit is over 1 billion operations per second. 'this proposed DSP is fabricated in a 0.8 micron triple metal technology with 16 mm × lb mm die area aver 1.5 million transistors. This DSP can be programmed for any DCT-based digital video compression.

Deacetylation of XBP1s by sirtuin 6 confers resistance to ER stress-induced hepatic steatosis

In Hyuk Bang,Oh Kwang Kwon,Lihua Hao,Dami Park,Myung-Ja Chung,Byung-Chul Oh,Sangkyu Lee,Eun-ju Bae,Byung-Hyun Park 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

The active spliced form of X-box-binding protein 1 (XBP1s) is a key modulator of ER stress, but the functional role of its post-translational modification remains unclear. Here, we demonstrate that XBP1s is a deacetylation target of Sirt6 and that its deacetylation protects against ER stress-induced hepatic steatosis. Specifically, the abundance of acetylated XBP1s and concordant hepatic steatosis were increased in hepatocyte-specific Sirt6 knockout and obese mice but were decreased by genetic overexpression and pharmacological activation of Sirt6. Mechanistically, we identified that Sirt6 deacetylated a transactivation domain of XBP1s at Lys257 and Lys297 and promoted XBP1s protein degradation through the ubiquitin-proteasome system. Overexpression of XBP1s, but not its deacetylation mutant 2KR (K257/297R), in mice increased lipid accumulation in the liver. Importantly, in liver tissues obtained from patients with nonalcoholic fatty liver disease (NAFLD), the extent of XBP1s acetylation correlated positively with the NAFLD activity score but negatively with the Sirt6 level. Collectively, we present direct evidence supporting the importance of XBP1 acetylation in ER stress-induced hepatic steatosis.