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Sangil Jeon,한승훈,Jongtae Lee,Taegon Hong,임동석 대한약리학회 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.4
We analyzed the pharmacokinetics of C3G on data from twelve subjects, after 2-week multiple dosing of black bean (Phaseolus vulgaris, Cheongjakong-3-ho) seed coat extract, using the mixed effect analysis method (NONMEM, Ver. 6.2), as well as the conventional non-compartmental method. We also examined the safety and tolerability. The PK analysis used plasma concentrations of the C3G on day 1 and 14. There was no observed accumulation of C3G after 2-week multiple dosing of black bean seed coat extract. The typical point estimates of PK were CL (clearance)=3,420 l/h, V (volume)=7,280L, Ka (absorption constant)=9.94 h-1, ALAG (lag time)=0.217 h. The black bean seed coat extract was well tolerated and there were no serious adverse events. In this study, we confirmed that a significant amount of C3G was absorbed in human after given the black bean seed coat extract.
Surface strain effects on the adsorption and the diffusion of Au atoms on MgO(001) surfaces
Jeon, Junjin,Yu, Byung Deok,Hyun, Sangil 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.
<P>The effects of surface strain on the adsorption and the diffusion properties of a Au adatom on MgO(001) surfaces are studied using first-principles electronic-structure calculations based on the density functional theory. The adsorption of Au on MgO(001) is found to become stronger with increasing surface strain. In addition, the adsorption site of Au changes from a site on top of a surface O atom of MgO(001) to a site near a surface O atom for tensile surface strains over +4 %. In the case of a tensile surface strain of +7 %, the adsorption energy changes from -0.87 eV for unstrained MgO(001) to -1.17 eV. The variation in the charge states of Au on MgO(001) with surface strain, based on a Bader charge analysis, is also presented. The Bader charges of Au are found to become more negative as the surface strain increases. For a tensile surface strain of +7 %, the Bader charge is -0.38 |e|, more negative than the value of -0.29 |e| for unstrained MgO(001). Contrary to the adsorption energies and the charge states of Au, the variation in the surface diffusion barriers of Au on MgO(001) is found to be very small, less than 0.03 eV.</P>
최수인,Sangil Jeon,한승훈 대한임상약리학회 2018 Translational and Clinical Pharmacology Vol.26 No.1
Metformin, an oral antihyperglycemic agent, is widely used as the first-line pharmacotherapyfor type 2 diabetes mellitus (T2DM). It has been in use for several decades as numerous differentformulations. However, despite its use, population pharmacokinetic (PK) modeling of metforminis not well developed. The aim of the present study was to evaluate the effect of formulation on PKparameters by developing a population PK model of metformin in Koreans and using this model toassess bioequivalence. We used a comparative PK study of a single agent and a fixed-dose combinationof metformin in 36 healthy volunteers. The population PK model of metformin was developedusing NONMEM (version 7.3). Visual predictive checks and bootstrap methods were performed todetermine the adequacy of the model. The plasma concentration.time profile was best describedby a two-compartment, first-order elimination model with first-order absorption followed by zeroorderabsorption with lag time. From the covariate analysis, formulation had significant effect (p <0.01) on relative bioavailability (F = 0.94) and first-order absorption constant (Ka = 0.83), but thedifference was within the range of bioequivalence criteria. No other covariate was shown to havesignificant effect on PK parameters. The PK profile of the disposition phase was consistent with thepublished literature. However, in the present study, the multiple peaks found during the absorptionphase implied the possible diversity of absorption PK profile depending on formulation or population. Unlike traditional bioequivalence analysis, the population PK model reflects formulation differenceson specific parameters and reflected simulation can be performed.
현상일(Sangil Hyun),전재성(Jae Sung Jeon),김영석(Young-Suk Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Finite-element methods are used to study non-adhesive, frictionless rough contact of elastic and plastic solids. Roughness on spherical surfaces is realized by self-affine fractal. True contact area between the rough surfaces and nat rigid surfaces increases with power law under external normal loads. The power exponent is sensitive to surface roughness as well as the curvature of spherical geometry. Surface contact pressures are analyzed and compared for the elastic and plastic solids. Distributions of local contact pressure are shown dependent on the surface roughness and the yield stress of plastic solids.
Surface Strain Effects on the Adsorption and the Diffusion of Au Atoms on MgO(001) Surfaces
Junjin Jeon,유병덕,Sangil Hyun 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.12
The effects of surface strain on the adsorption and the diffusion properties of a Au adatom on MgO(001) surfaces are studied using first-principles electronic-structure calculations based on the density functional theory. The adsorption of Au on MgO(001) is found to become stronger with increasing surface strain. In addition, the adsorption site of Au changes from a site on top of a surface O atom of MgO(001) to a site near a surface O atom for tensile surface strains over +4 %. In the case of a tensile surface strain of +7 %, the adsorption energy changes from −0.87 eV for unstrained MgO(001) to −1.17 eV. The variation in the charge states of Au on MgO(001) with surface strain, based on a Bader charge analysis, is also presented. The Bader charges of Au are found to become more negative as the surface strain increases. For a tensile surface strain of +7 %, the Bader charge is −0.38 |e|, more negative than the value of −0.29 |e| for unstrained MgO(001). Contrary to the adsorption energies and the charge states of Au, the variation in the surface diffusion barriers of Au on MgO(001) is found to be very small, less than 0.03 eV.
Lee, Jongtae,Jeon, Sangil,Hong, Taegon,Han, Seunghoon,Yim, Dong-Seok Springer 2015 European journal of clinical pharmacology Vol.71 No.11
<P>This study aimed to determine the effect of PET scan timings on the reliability of occupancy parameter estimates and to identify the scan timing design that gives the most reliable occupancy parameter estimates.</P>
Han, Seunghoon,Jeon, Sangil,Hong, Taegon,Lee, Jongtae,Bae, Soo Hyeon,Park, Wan-su,Park, Gab-jin,Youn, Sunil,Jang, Doo Yeon,Kim, Kyung-Soo,Yim, Dong-Seok Dove Medical Press 2015 Drug design, development and therapy Vol.9 No.-
<P>No wholly successful weight-control drugs have been developed to date, despite the tremendous demand. We present an exposure–response model of sibutramine mesylate that can be applied during clinical development of other weight-control drugs. Additionally, we provide a model-based evaluation of sibutramine efficacy. Data from a double-blind, randomized, placebo-controlled, multicenter study were used (N=120). Subjects in the treatment arm were initially given 8.37 mg sibutramine base daily, and those who lost <2 kg after 4 weeks’ treatment were escalated to 12.55 mg. The duration of treatment was 24 weeks. Drug concentration and body weight were measured predose and at 4 weeks, 8 weeks, and 24 weeks after treatment initiation. Exposure and response to sibutramine, including the placebo effect, were modeled using NONMEM 7.2. An asymptotic model approaching the final body weight was chosen to describe the time course of weight loss. Extent of weight loss was described successfully using a sigmoidal exposure–response relationship of the drug with a constant placebo effect in each individual. The placebo effect was influenced by subjects’ sex and baseline body mass index. Maximal weight loss was predicted to occur around 1 year after treatment initiation. The difference in mean weight loss between the sibutramine (daily 12.55 mg) and placebo groups was predicted to be 4.5% in a simulation of 1 year of treatment, with considerable overlap of prediction intervals. Our exposure–response model, which included the placebo effect, is the first example of a quantitative model that can be used to predict the efficacy of weight-control drugs. Similar approaches can help decision-making during clinical development of novel weight-loss drugs.</P>
Yunjung Hong,Sangil Jeon,Suein Choi,Sungpil Han,Maria Park,Seunghoon Han 대한생리학회-대한약리학회 2021 The Korean Journal of Physiology & Pharmacology Vol.25 No.6
Fixed-dose combinations development requires pharmacokinetic drugdrug interaction (DDI) studies between active ingredients. For some drugs, pharmacokinetic properties such as long half-life or delayed distribution, make it difficult to conduct such clinical trials and to estimate the exact magnitude of DDI. In this study, the conventional (non-compartmental analysis and bioequivalence [BE]) and modelbased analyses were compared for their performance to evaluate DDI using amlodipine as an example. Raw data without DDI or simulated data using pharmacokinetic models were compared to the data obtained after concomitant administration. Regardless of the methodology, all the results fell within the classical BE limit. It was shown that the model-based approach may be valid as the conventional approach and reduce the possibility of DDI overestimation. Several advantages (i.e., quantitative changes in parameters and precision of confidence interval) of the model-based approach were demonstrated, and possible application methods were proposed. Therefore, it is expected that the model-based analysis is appropriately utilized according to the situation and purpose.