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Choi, Joon-Sig,Choi, Young-Hun,Park, Jong-Sang Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.7
A hybrid linear polymer-dendrimer block copolymer, poly(ethylene glycol)-block-poly(L-lysine) dendrimer, was synthesized and introduced to form polyionic complexes with DNA. The copolymer formed core-shell type nanoparticles with plasmid DNA. From dynamic light scattering experiments, the mean diameter of the polyplexes was observed to be 154.4 nm. The complex showed much increased water solubility compared to poly(L-lysine). The plasmid DNA in polyplexes was efficiently protected from the enzymatic digestion of DNase I. The cytotoxicity and transfection efficiency for 293 cells was measured in comparison with poly(Llysine).
Choi, Joon-Sig,Shin, Jeong-Sook,Choi, Hong-Sug,Park, Jong-Sang Korean Society for Biochemistry and Molecular Biol 1997 Journal of biochemistry and molecular biology Vol.30 No.2
The present paper reports characteristics and specificity of the inhibitory action of $N^{\alpha}-tosyl-L-lysine-chloromethyl\;ketone$ (TLCK) and $N^{\alpha}-tosyl-L-phenylalanine-chloromethyl\;ketone$ (TPCK) on the glucose6-phosphate transporter of rat liver microsomes. The TLCK-induced inhibition was pH dependent. The inhibition constants for TPCK were determined by following pseudo-Lst order reaction mechanism. The inhibition was protected by preincubation with excess amount of glucose-6-phosphate. The results proved that (a) TLCK inactivates the microsomal glucose-6-phosphate transporter, (b) the inhibition results from the modification of sulfhydryl groups of the transporter.
Choi, Joon-Sig,Choi, Min-Ji,Go, Gyeong-Su,Rhee, Byoung-Doo,KimPak, Young-Mi,Bang, In-Seok,Lee, Min-Hyung Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.9
It has been found that a number of diseases are associated with mutations in the mitochondrial DNA. Therapeutic gene delivery to mitochondria has been suggested as a clinical option for these diseases. In this study, we developed a gene carrier to mitochondria by the conjugation of mitochondrial leader peptide (LP) to polyethylenimine (PEI). Mitochondrial LP conjugated PEI (PEI-LP) was synthesized with low molecular weight PEI (2,000 Da, PEI2K). Gel retardation assay showed that PEI2K-LP formed complexes at a 1.0/1 weight ratio. In addition, PEI2K-LP protected DNA from the enzymatic degradation for at least 60 min, while naked DNA was completely degraded within 20 min. PEI2K-LP was compared with LP conjugated high molecular weight PEI (25,000 Da, PEI25K) in terms of toxicity and delivery efficiency. MTT assay showed that PEI2K-LP had much lower cytotoxicity than PEI25K-LP to 293 cells. In addition, cell-free DNA delivery assay showed that PEI2K-LP delivered more DNA to mitochondria at a 1.8/1 weight ratio than naked DNA or PEI. This result suggests that PEI2K-LP may be useful for the development of mitochondrial gene therapy system with lower cytotoxicity.
Effect of Dexamethasone Preincubation on Polymer-Mediated Gene Delivery
Choi, Joon-Sig,Lee, Min-Hyung Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.8
Nuclear membrane is one of the main barriers in intracellular delivery of genetic materials. The previous report showed that glucocorticoid receptor dilated the nuclear pore to 60 nm in the presence of a ligand. It was also suggested that the transport of genetic material to nucleus might be facilitated by glucocorticoid. In this study, the effect of glucocorticoid preincubation in the polymeric gene delivery was investigated. The cells were preincubated with dexamethasone, a potent glucocorticoid, and transfection assays were performed with polyethylenimine (PEI) and polyamidoamine (PAMAM) dendrimer. As a result, the transfection efficiency of PEI or PAMAM to the cells in the presence of dexamethasone was enhanced, compared to the cells without dexamethasone. This effect was not observed in the cells preincubated with cholesterol. The polymer/DNA complex was stable in the presence of dexamethasone. In addition, the cytotoxicities of the polymeric carriers to the cells were observed in the presence of dexamethasone. In conclusion, dexamethasone enhances the transfection efficiency of polymeric carriers and may be useful in the development of polymeric gene carriers.
Choi, Joon Sig,Nam, Kihoon,Park, Jong-yeun,Kim, Jung-Bin,Lee, Ja-Kyeong,Park, Jong-sang Elsevier 2004 Journal of controlled release Vol.99 No.3
<P><B>Abstract</B></P><P>We designed a novel type of arginine-rich dendrimer, with a structure based on the well-defined dendrimer, polyamidoamine dendrimer (PAMAM). Further characterization was performed to prove that the polymer is a potent nonviral gene delivery carrier. The primary amines located on the surface of PAMAM were conjugated with <SMALL>L</SMALL>-arginine to generate an <SMALL>L</SMALL>-arginine-grafted-PAMAM dendrimer (PAMAM-Arg). For comparison, an <SMALL>L</SMALL>-lysine-grafted-PAMAM dendrimer (PAMAM-Lys) was also generated and compared as a control reagent. The polymers were found to self-assemble electrostatically with plasmid DNA, forming nanometer-scale complexes. From dynamic light scattering experiments, the mean diameter of the polyplexes was observed to be around 200 nm. We used PicoGreen reagent as an efficient probe for assaying complex formation of polymers with plasmid DNA. The complex composed of PAMAM-Arg/DNA showed increased gene delivery potency compared to native PAMAM dendrimer and PAMAM-Lys. The cytotoxicity and transfection efficiencies for 293, HepG2, and Neuro 2A cells were measured by comparison with PEI and PAMAM. In addition, transfection experiments were performed in primary rat vascular smooth muscle cells, and PAMAM-Arg showed much enhanced transfection efficiency. These findings suggest that the <SMALL>L</SMALL>-arginine-grafted-PAMAM dendrimer possesses the potential to be a novel gene delivery carrier for gene therapy.</P>
Choi, Joon-Sig,Lee, Eun-Jung,Jang, Hyung-Suk,Park, Jong-Sang Korean Society for Biochemistry and Molecular Biol 2000 Journal of biochemistry and molecular biology Vol.33 No.6
In this paper, we report a new cationic lipid composed of L-lysinamide and cholesterol as a potent gene delivery vector. $3{\beta}$[L-Lysinamide-carbamoyl] cholesterol could self-assemble with plasmid DNA forming discrete lipoplexes. From atomic force microscopic images of the complexes, the size distribution was observed to range from 100 to 150 nm in diameter. The transfection efficiency of this amphiphile on different cell lines was evaluated as a micellar solution in the absence of the fusogenic helper lipid, dioleoyl phosphatidyletbanolamine (DOPE). Transfection experiments were performed as a function of charge ratio (lipid/DNA) and transfection time. Cytotoxicity and in vitro transfection efficiency of the amphiphile was demonstrated and compared with those of commercially available Lipofectin and polyethylenimine (PEI).
90~93년도 서울 지역에 출하된 돼지의 Aujeszky`s병 감염 실태 조사
최준식 ( Joon Sig Choi ),육동현 ( Dong Hyeun Yuk ),김성삼 ( Sung Sham Kim ),문현칠 ( Hyeun Chil Mon ) 한국가축위생학회 1994 韓國家畜衛生學會誌 Vol.17 No.1
The porcine Aujeszky`s disease was surveyed by Enzyme Immunodiffusion method and serologic neutralization test to the slaughtered pigs at slaughtehouse only in Seoul from March, 1990 to October, 1993. After detecting the positive by enzyme immunodiffusion method primary, we decided finally the positive by serologic neutralization test secondary. Results obtained through the experiments were summarized as followed; 1. The positive of Aujeszky`s disease in March, 1990 was 2 of 1,000 sera. 2 positive were decided as the consigned pigs in Kalsan, HongSung, Chungnam. 2. The positive of Aujezsky`s disease in May, 1991 was decided 1 serum at Pogok, Yongin, Kyeonggi. 3. All of the positive detected by Enzyme Immunodiffusion Method in 1993 were decided finally in the negative sera. 4. The positive sera detected in 1992 were decided 32 sera at Gyeonggi, 6 at Chungnam, and 1 at Gangwon. Especially, the positive sera percentage detected by Kit Latex Aujeszky Test appeared 78.04% at Gyonggi and by enzyme immunodiffusion Method appeared 11.11% at Chungnam and Gangwon.