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난용성 의약품의 생체이용률 증진을 위한 무정형 초미립자의 조제 : UDCA와 SLS의 혼합분쇄 효과
정한영(Han Young Chung),곽성신(Seong Shin Kwak),김현일(Hyun Il Kim),최우식(Woo Sik Choi) 대한약학회 2002 약학회지 Vol.46 No.2
The particle size of medicinal materials is an important physical property which affects the pharmaceutical behaviors such as dissolution, chemical stability; compressibility and bioavailability of solid dosage forms. The size reduction of raw pharmaceutical powder is needed to formulize insoluble drugs or slightly soluble drugs and to improve the pharmaceutical properties such as the solubility the pharmaceutical mixing and the dispersion. The objective of the present study is to evaluate the grinding characteristics of ursodeoxycholic acid(UDCA) as a model of insoluble drugs. The effects of the grinding time and the amount of additive on particle size distribution of ground UDCA were investigated. Grinding of insoluble drug, UDCA and a series of dry co-grinding experiments of UDCA with sodium lauryl sulfate(SLS) as an additive were carried out uslng a planetary ball mill. It was measured that the median diameter and the particle size distribution of ground products with grinding WCh and additive SLS by Mastersizer. As a result of co-grinding of UDCA and SLS, the particle size of co-grinding products was decreased more than single grinding one. Howeverl it was observed that co-grindins products were reaggregated to larger particles after 120 min.
Ursodeoxycholic acid 의 무정형 초미립자제제들의 CCI4 유도 간손상 생쥐에 대한 보호 효과
정한영(Han Young Chung),김애라(Ae Ra Kim),정해영(Hae Young Chung),곽신성(Sin Seung Kwak),최우식(Woo Sik Choi),이지현(Ji Hyoen Lee),박태현(Tae Hyun Park),김유정(You Jung Kim),김현일(Hyun Il Kim) 한국응용약물학회 2002 Biomolecules & Therapeutics(구 응용약물학회지) Vol.10 No.1
N/A The particle size of medicinal materials is an important physical property that affects the pharmaceutical behaviors such as dissolution, chemical stability, and bioavailability of solid dosage forms. The size reduction of raw medicinal powder is needed to formulate insoluble drugs or slightly soluble medicines and to improve the pharmaceutical properties such as the solubility, the pharmaceutical mixing, and the dispersion. The objective of the present study is to evaluate physiological activity of amorphous and nano-particle preparations of insoluble drug, ursodeoxycholic acid (UDCA), which were made by three types of fine grinding mills. The change of physical properties of ground UDCA was conformed by Mastersiger microplus and X-ray diffraction. We have investigated hepatoprotective effects of the nano-particle preparations of UDCA by planetary mill, vibration rod mill and jet mill in CCl_4-induced oxidatively injured mouse liver. The results showed that nano-particle preparations of UDCA all decreased reactive oxygen sepecies generation and lipid peroxidation in CCl_4-induced oxidative stress mice. Among them, nano-particle preparations by vibration rod mill and jet mill showed more significantly hepatoprotective effects compared to intact UDCA and planetary millground UDCA. These results suggest that ground UDCA with vibration rod mill and jet mill shows a high amorphous state and the improved dissolution.
Ginseonside Rb2 가 노화촉진마우스 ( SAM - R / 1 ) 의 항산화물질에 미치는 영향
오미현,정해영,양한석,김규원,정한영,오우라히코끼치,요꼬자와다까꼬 ( Mi Hyune Oh,Hae Young Chung,Han Suk Yong,Kyu Won Kim,Han Young Chung,Hikokichi Oura,Takako Yokozawa ) 생화학분자생물학회 1992 BMB Reports Vol.25 No.5
During aging, its chance of tissue damage by active oxygen species increases, which causes the abnormal aging as well as diseases like cancer. In biological system, there are enzymes such as superoxide dismutase, catalase and glutathione peroxidase which scavenge active oxygen species as well as antioxidant agents such as ceruloplasmin, albumin and nonprotein-bound SH including glutathione related to defense mechanism. In this study, superoxide dismutase, catalase, serum albumin, protein-bound SH and nonprotein-bound SH levels were increased in SAM-R/1 mice treated with 2.5 or 5.0 ㎎/㎏ ginsenoside Rb₂. But malondialdehyde which is the product of lipid peroxidation was significantly decreased. These results suggest that increase of antioxidants by ginsenoside Rb₂ results in the protective effects against active oxygen species.
Coagulation-promoting activity induced by polystyrene nanoplastics in RBCs
Eun-Hye Kim(김은혜),Han Young Chung(정한영),Sang Ho Choi(최상호),Ok-Nam Bae(배옥남) 환경독성보건학회 2021 한국독성학회 심포지움 및 학술발표회 Vol.2021 No.5
Micro/nanoplastics in the environment can enter the body by various routes. Micro/nanoplastics entering the body translocate from the exposure site to the circulatory system. There is an urgent need to evaluate the toxicity of cardiovascular tissues such as blood cells and vessels that may be exposed to micro/nanoplastics. We investigated whether nanoplastics influence the coagulation promoting activity of red blood cells (RBCs). We have tested several types of polystyrene nanoplastics (PS-NP) using freshly isolated human RBCs. We measured the time course of hemolysis, phosphatidylserine (PS) exposure, and microvesicle (MV) to determine effect of PS-NP on human RBCs. The morphological change of RBCs by PS-NP were observed by Scanning- or Transmission-Electron Microscopy. To elucidate the underlying mechanism of procoagulation activation by PS-NP, the changes of the oxidative stress, calcium level, GSH level, ATP level, and caspase-3 activities were monitored. The enzymatic activity for PS translocation was also detected. To elucidate the functional alteration, we measured the adhesion of RBCs to endothelial cells (HUVECs) and thrombin generation. Consistent to the observations in human RBCs, exposure to PS-NP increased hemolysis, PS exposure, and thrombin generation in rat RBCs. After administrating of PS-NP by intravenous injection, we observed enhanced thrombus formation in vein using rat venous thrombosis model in vivo. Here, we suggest that PS-NP can promote prothrombotic risks on RBCs. Our study will contribute to understand the toxicity of micro/nanoplastics on RBCs and cardiovascular systems.
Increased prothrombotic activity of red blood cells by 2-n-octyl-4-isothiazolinone
Sungbin Choi(최성빈),Han Young Chung(정한영),Sang Ho Choi(최상호),Ok-Nam Bae(배옥남) 환경독성보건학회 2021 한국독성학회 심포지움 및 학술발표회 Vol.2021 No.5
Thirty percent of the world population has died from cardiovascular diseases, such as thrombotic disease, hyperlipidemia, and stroke. Since xenobiotics entering the body move through the bloodstream, the blood and vascular systems are inevitably the primary targets of the xenobiotics. Isothiazolinone (IT) derivatives are used as preservatives in various fields, posing a high exposure potential. Among them, 2-n-octyl-4-isothiazolinone (OIT) is used in non-cosmetic products such as chemical products and household detergents. Although OIT is commonly used and can circulate the bloodstream, the effects of OIT on blood cells remain unclear. Here, we demonstrated that OIT may increase the risk of thrombotic diseases by promoting the procoagulant activity of red blood cells (RBCs). In freshly isolated human RBCs, OIT in sub-hemolytic concentration changed the shape of the RBCs from discocytes to echinocytes or spherocytes, and increased phosphatidylserine (PS) exposure, microvesicle (MV) generation, MV-PS exposure, and thrombin generation. An increase of intracellular Ca2+ level was found to be the mechanism that causes PS exposure by OIT, rather than the increase of intracellular oxidative stress or activation of caspase-3. The effects of OIT in human RBCs were also found in isolated male rat RBCs. In the rat in vivo thrombosis model, intravenously treated OIT significantly promoted the formation of venous thrombosis. Collectively, we demonstrated that OIT may contribute to the thrombotic risk by promoting the procoagulant activity of RBCs.
On the Optimum Time Points in Stochastic Processes
Chung, Han-Young 서울대학교 교양과정부 1974 論文集 Vol.6 No.-
In approximating a random variable Y by the linear combination of observations (X_t1,…,X_tn) from a stochastic process {X_t, t∈T}, it is natural to consider how th select time points (t_1, …, t_n) optimully for a fixed n so that the expected mean square error is to be minimized. Since the expected mean square error is represented as a function of covariance between (Y, X_t1,…,X_tn), the optimum selectin of time points (t_1,…,t_n) can be obtained based on the informations about them. When T is discrete and finite, the problem is regarded as a sort of integer programming, and the solution can be obtained by investigating all possible combinations of (t_1,…,t_n). When T is continuons, informations of covariance functions are needed to solve the problem under the assumption that the process is weakly stationary. When the process is weakly stationary and has Markov property in the wide sense, covariance function C(_s)=E{X_((t+s))X_t} is represented as σ^2e^-λs where E{X_t}=0 and E{X_t^2}=σ^2. Then the optimum time points sampling can be made analtyticaly.