Hepatitis B virus (HBV) infection is associated with a wide spectrum of clinical manifestations i... more Hepatitis B virus (HBV) infection is associated with a wide spectrum of clinical manifestations including cirrhosis and hepatocellular carcinoma (HCC). Endoplasmic reticulum (ER) stress and subsequent oxidative stress have been implicated in liver carcinogenesis and disease progression with chronic inflammation. In our previous study, several mutations in the preC/C region of HBV genotype C were identified from 70 Korean chronic patients, and the mutations were associated with HCC and/or HBeAg serostatus. Here, we found that the naturally occurring mutations P5T/H/L of the HBV core region (HBcAg) induced endoplasmic reticulum (ER) stress. The upregulation of ER stress resulted in higher reactive oxygen species production, intracellular calcium concentration, inflammatory cytokines, as well as surface antigen production and apoptosis of cells. This study suggests that these mutations may contribute to the progression of liver disease in chronic patients.
Journal of the American Chemical Society, Jan 23, 2008
Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for t... more Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for the investigation of electrocatalytic formic acid oxidation. The binary particles exhibited much less self-poisoning and a lower activation energy relative to Pt nanocubes, consistent with the single crystal study.
World journal of gastroenterology : WJG, Jan 14, 2015
To elucidate the molecular mechanisms underlying hepatitis B virus (HBV) occult infection of geno... more To elucidate the molecular mechanisms underlying hepatitis B virus (HBV) occult infection of genotype C. A total of 10 types of hepatitis B surface antigen (HBsAg) variants from a Korean occult cohort were used. After a complete HBV genome plasmid mutated such that it does not express HBsAg and plasmid encoding, each HBsAg variant was transiently co-transfected into HuH-7 cells. The secretion capacity and intracellular expression of the HBV virions and HBsAgs in their respective variants were analyzed using real-time quantitative polymerase chain reaction assays and commercial HBsAg enzyme-linked immunosorbent assays, respectively. All variants exhibited lower levels of HBsAg secretion into the medium compared with the wild type. In particular, in eight of the ten variants, very low levels of HBsAg secretion that were similar to the negative control were detected. In contrast, most variants (9/10) exhibited normal virion secretion capacities comparable with, or even higher than, the...
The journal of physical chemistry. B, Jan 17, 2005
Zeolites and molecular sieves are synthesized using organic structure-directing agents (SDAs) tha... more Zeolites and molecular sieves are synthesized using organic structure-directing agents (SDAs) that have the potential to be degraded into fragments within the pore space so that they can be readily extracted at mild conditions. The zeolites and molecular sieves, VPI-8, ZSM-12, and ZSM-5, are synthesized using the ketal-containing SDA, 8,8-dimethyl-1,4-dioxa-8-azoniaspiro[4,5]decane (SDA-1). As expected, solids with unidimensional pore systems (VPI-8, ZSM-12) are much more difficult to process by this methodology than solids containing multidimensional pore systems (ZSM-5). Pore-filling agents (PFAs) such as isobutylamine and cyclopentylamine are used together with the ketal-containing SDA-1 to prepare ZSM-5. Extraction of the PFA is shown to be feasible, and its removal provides space for components to enter the zeolite micropores where they react with and cleave SDA-1. Removal of the cleavage fragments from SDA-1 gives ZSM-5 that has the appropriate pore volume, framework aluminum ...
A series of ionic liquid-derived imidazolium metal halide complexes, (1-R-3- methylimidazolium)bM... more A series of ionic liquid-derived imidazolium metal halide complexes, (1-R-3- methylimidazolium)bMXaYb (M = Zn, Fe, Mn, In; R = CH3, C2H5, n-C4H9, CH2C6H5; X, Y = Cl, Br; a, b = 2, 3) were prepared by reacting metal halide, MXa with an equivalent of (1-R- 3-methylimidazolium)Y and their activities were tested for the coupling reactions of ethylene oxide and CO2 to produce ethylene carbonate. Among (1-R-3-methylimidazolium)bMXaYb tested, imidazolium zinc tetrahalide exhibited the highest activities. The catalytic activity of imidazolium metal halide was greatly influenced by the nature of halide ligands.
Little is known about the mechanisms underlying the effects of Cyclosporin A (CsA) on the fate of... more Little is known about the mechanisms underlying the effects of Cyclosporin A (CsA) on the fate of stem cells, including cardiomyogenic differentiation. Therefore, we investigated the effects and the molecular mechanisms behind the actions of CsA on cell lineage determination of P19 cells. CsA induced cardiomyocyte-specific differentiation of P19 cells, with the highest efficiency at a concentration of 0.32 μM during embryoid body (EB) formation via activation of the Wnt signaling pathway molecules, Wnt3a, Wnt5a, and Wnt8a, and the cardiac mesoderm markers, Mixl1, Mesp1, and Mesp2. Interestingly, cotreatment of P19 cells with CsA plus dimethyl sulfoxide (DMSO) during EB formation significantly increases cardiac differentiation. In contrast, mRNA expression levels of hematopoietic and endothelial lineage markers, including Flk1 and Er71, were severely reduced in CsA-treated P19 cells. Furthermore, expression of Flk1 protein and the percentage of Flk1+ cells were severely reduced in 0....
A series of lithium chloride-imidazolium chloride (LiCl-(imidazolium)Cl) melts were prepared and ... more A series of lithium chloride-imidazolium chloride (LiCl-(imidazolium)Cl) melts were prepared and their catalytic activities were evaluated for the coupling reactions of propylene oxide and CO2. At the constant mole of LiCl, the catalytic activities of LiCl-(imidazolium)Cl melts increased with increasing molar ratio of (imidazolium)Cl/LiCl up to 2, but thereafter decreased rapidly. The variation of alkyl groups on the imidazolium ring
Mesoporous silica was synthesized as a support for the removal of copper ions in aqueous solution... more Mesoporous silica was synthesized as a support for the removal of copper ions in aqueous solutions. The Sol-gel method in conjunction with neutral surfactants was used. The remaining surfactants were removed by either the Soxhlet or microwave extraction method. Both ...
Chronic inflammation is fundamental for the induction of insulin resistance in the muscle tissue ... more Chronic inflammation is fundamental for the induction of insulin resistance in the muscle tissue of vertebrates. Although several miRNAs are thought to be involved in the development of insulin resistance, the role of miRNAs in the association between inflammation and insulin resistance in muscle tissue is poorly understood. Herein, we investigated the aberrant expression of miRNAs by conducting miRNA microarray analysis of TNF-α-treated mouse C2C12 myotubes. We identified two miRNAs that were upregulated and six that were downregulated by a >1.5-fold change compared to normal cells. Among the findings, qRT-PCR analysis confirmed that miR-494 is consistently upregulated by TNF-α-induced inflammation. Overexpression of miR-494 in CHO(IR/IRS1) and C2C12 myoblasts suppressed insulin action by down-regulating phosphorylations of GSK-3α/β, AS160 and p70S6K, downstream of Akt. Moreover, overexpression of miR-494 did not regulate TNF-α-mediated inflammation . Among genes bearing the seed site for miR-494, RT-PCR analysis showed that the expression of Stxbp5, an inhibitor of glucose transport, was downregulated following miR-494 inhibition. In contrast, the expression of PTEN decreased in the cells analyzed, thus showing that both positive and negative regulators of insulin action may be simultaneously controlled by miR-494. To investigate the overall effect of miR-494 on insulin signaling, we performed a PCR array analysis containing 84 genes related to the insulin signaling pathway, and we observed that 25% of genes were downregulated (P<0.05) and 11% were upregulated (P<0.05). These results confirm that miR-494 might contribute to insulin sensitivity by positive and negative regulation of the expression of diverse genes. Of note, PCR array data showed downregulation of Slc2A4, a coding gene for Glut4. Altogether, the present study concludes that the upregulation of miR-494 expression by TNF-α-mediated inflammation exacerbates insulin resistance. Therefore, we suggest that miR-494 could prove an important target for the diagnosis and therapy of inflammation-mediated insulin resistance in muscle.
Zeolites are mainly used for the adsorption and separation of ions and small molecules, and as he... more Zeolites are mainly used for the adsorption and separation of ions and small molecules, and as heterogeneous catalysts. More recently, these materials are receiving attention in other applications, such as medical diagnosis and as components in electronic devices. Modern synthetic methodologies for preparing zeolites and zeolite-like materials typically involve the use of organic molecules that direct the assembly pathway and ultimately fill the pore space. Removal of these enclathrated species normally requires high temperature combustion that destroys this high cost component, and the associated energy release in combination with the formed water can be extremely detrimental to the inorganic structure. Here we report a synthetic methodology that avoids these difficulties by creating organic structure-directing agents (SDAs) that can be disassembled within the zeolite pore space to allow removal of their fragments for possible use again by reassembly. The methodology is shown for the synthesis of zeolite ZSM-5 using a SDA that contains a cyclic ketal group that is removed from the SDA while it is inside the zeolite without destruction of the inorganic framework. This approach should be applicable to the synthesis of a wide variety of inorganic and organometallic structures.
The first asymmetric total syntheses of the dihalogenated medium-sized dioxabicyclic marine natur... more The first asymmetric total syntheses of the dihalogenated medium-sized dioxabicyclic marine natural products (+)-3-(Z)-isolaureatin (1) and (+)-3-(Z)-laureatin (2) have been accomplished. Notable features of the highly stereo-, regio-, and chemoselective syntheses of these alpha,alpha'-trans-oxocene natural products include an intramolecular amide enolate alkylation to construct the alpha,alpha'-cis-oxocene, novel "lone pair-lone pair interaction-controlled" epimerizations to the alpha,alpha'-trans-oxocenes, various strategies for stereoselective introduction of halogen atoms, and novel olefin cross-metatheses for construction of the (Z)-enyne systems.
Hepatitis B virus (HBV) infection is associated with a wide spectrum of clinical manifestations i... more Hepatitis B virus (HBV) infection is associated with a wide spectrum of clinical manifestations including cirrhosis and hepatocellular carcinoma (HCC). Endoplasmic reticulum (ER) stress and subsequent oxidative stress have been implicated in liver carcinogenesis and disease progression with chronic inflammation. In our previous study, several mutations in the preC/C region of HBV genotype C were identified from 70 Korean chronic patients, and the mutations were associated with HCC and/or HBeAg serostatus. Here, we found that the naturally occurring mutations P5T/H/L of the HBV core region (HBcAg) induced endoplasmic reticulum (ER) stress. The upregulation of ER stress resulted in higher reactive oxygen species production, intracellular calcium concentration, inflammatory cytokines, as well as surface antigen production and apoptosis of cells. This study suggests that these mutations may contribute to the progression of liver disease in chronic patients.
Journal of the American Chemical Society, Jan 23, 2008
Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for t... more Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for the investigation of electrocatalytic formic acid oxidation. The binary particles exhibited much less self-poisoning and a lower activation energy relative to Pt nanocubes, consistent with the single crystal study.
World journal of gastroenterology : WJG, Jan 14, 2015
To elucidate the molecular mechanisms underlying hepatitis B virus (HBV) occult infection of geno... more To elucidate the molecular mechanisms underlying hepatitis B virus (HBV) occult infection of genotype C. A total of 10 types of hepatitis B surface antigen (HBsAg) variants from a Korean occult cohort were used. After a complete HBV genome plasmid mutated such that it does not express HBsAg and plasmid encoding, each HBsAg variant was transiently co-transfected into HuH-7 cells. The secretion capacity and intracellular expression of the HBV virions and HBsAgs in their respective variants were analyzed using real-time quantitative polymerase chain reaction assays and commercial HBsAg enzyme-linked immunosorbent assays, respectively. All variants exhibited lower levels of HBsAg secretion into the medium compared with the wild type. In particular, in eight of the ten variants, very low levels of HBsAg secretion that were similar to the negative control were detected. In contrast, most variants (9/10) exhibited normal virion secretion capacities comparable with, or even higher than, the...
The journal of physical chemistry. B, Jan 17, 2005
Zeolites and molecular sieves are synthesized using organic structure-directing agents (SDAs) tha... more Zeolites and molecular sieves are synthesized using organic structure-directing agents (SDAs) that have the potential to be degraded into fragments within the pore space so that they can be readily extracted at mild conditions. The zeolites and molecular sieves, VPI-8, ZSM-12, and ZSM-5, are synthesized using the ketal-containing SDA, 8,8-dimethyl-1,4-dioxa-8-azoniaspiro[4,5]decane (SDA-1). As expected, solids with unidimensional pore systems (VPI-8, ZSM-12) are much more difficult to process by this methodology than solids containing multidimensional pore systems (ZSM-5). Pore-filling agents (PFAs) such as isobutylamine and cyclopentylamine are used together with the ketal-containing SDA-1 to prepare ZSM-5. Extraction of the PFA is shown to be feasible, and its removal provides space for components to enter the zeolite micropores where they react with and cleave SDA-1. Removal of the cleavage fragments from SDA-1 gives ZSM-5 that has the appropriate pore volume, framework aluminum ...
A series of ionic liquid-derived imidazolium metal halide complexes, (1-R-3- methylimidazolium)bM... more A series of ionic liquid-derived imidazolium metal halide complexes, (1-R-3- methylimidazolium)bMXaYb (M = Zn, Fe, Mn, In; R = CH3, C2H5, n-C4H9, CH2C6H5; X, Y = Cl, Br; a, b = 2, 3) were prepared by reacting metal halide, MXa with an equivalent of (1-R- 3-methylimidazolium)Y and their activities were tested for the coupling reactions of ethylene oxide and CO2 to produce ethylene carbonate. Among (1-R-3-methylimidazolium)bMXaYb tested, imidazolium zinc tetrahalide exhibited the highest activities. The catalytic activity of imidazolium metal halide was greatly influenced by the nature of halide ligands.
Little is known about the mechanisms underlying the effects of Cyclosporin A (CsA) on the fate of... more Little is known about the mechanisms underlying the effects of Cyclosporin A (CsA) on the fate of stem cells, including cardiomyogenic differentiation. Therefore, we investigated the effects and the molecular mechanisms behind the actions of CsA on cell lineage determination of P19 cells. CsA induced cardiomyocyte-specific differentiation of P19 cells, with the highest efficiency at a concentration of 0.32 μM during embryoid body (EB) formation via activation of the Wnt signaling pathway molecules, Wnt3a, Wnt5a, and Wnt8a, and the cardiac mesoderm markers, Mixl1, Mesp1, and Mesp2. Interestingly, cotreatment of P19 cells with CsA plus dimethyl sulfoxide (DMSO) during EB formation significantly increases cardiac differentiation. In contrast, mRNA expression levels of hematopoietic and endothelial lineage markers, including Flk1 and Er71, were severely reduced in CsA-treated P19 cells. Furthermore, expression of Flk1 protein and the percentage of Flk1+ cells were severely reduced in 0....
A series of lithium chloride-imidazolium chloride (LiCl-(imidazolium)Cl) melts were prepared and ... more A series of lithium chloride-imidazolium chloride (LiCl-(imidazolium)Cl) melts were prepared and their catalytic activities were evaluated for the coupling reactions of propylene oxide and CO2. At the constant mole of LiCl, the catalytic activities of LiCl-(imidazolium)Cl melts increased with increasing molar ratio of (imidazolium)Cl/LiCl up to 2, but thereafter decreased rapidly. The variation of alkyl groups on the imidazolium ring
Mesoporous silica was synthesized as a support for the removal of copper ions in aqueous solution... more Mesoporous silica was synthesized as a support for the removal of copper ions in aqueous solutions. The Sol-gel method in conjunction with neutral surfactants was used. The remaining surfactants were removed by either the Soxhlet or microwave extraction method. Both ...
Chronic inflammation is fundamental for the induction of insulin resistance in the muscle tissue ... more Chronic inflammation is fundamental for the induction of insulin resistance in the muscle tissue of vertebrates. Although several miRNAs are thought to be involved in the development of insulin resistance, the role of miRNAs in the association between inflammation and insulin resistance in muscle tissue is poorly understood. Herein, we investigated the aberrant expression of miRNAs by conducting miRNA microarray analysis of TNF-α-treated mouse C2C12 myotubes. We identified two miRNAs that were upregulated and six that were downregulated by a >1.5-fold change compared to normal cells. Among the findings, qRT-PCR analysis confirmed that miR-494 is consistently upregulated by TNF-α-induced inflammation. Overexpression of miR-494 in CHO(IR/IRS1) and C2C12 myoblasts suppressed insulin action by down-regulating phosphorylations of GSK-3α/β, AS160 and p70S6K, downstream of Akt. Moreover, overexpression of miR-494 did not regulate TNF-α-mediated inflammation . Among genes bearing the seed site for miR-494, RT-PCR analysis showed that the expression of Stxbp5, an inhibitor of glucose transport, was downregulated following miR-494 inhibition. In contrast, the expression of PTEN decreased in the cells analyzed, thus showing that both positive and negative regulators of insulin action may be simultaneously controlled by miR-494. To investigate the overall effect of miR-494 on insulin signaling, we performed a PCR array analysis containing 84 genes related to the insulin signaling pathway, and we observed that 25% of genes were downregulated (P<0.05) and 11% were upregulated (P<0.05). These results confirm that miR-494 might contribute to insulin sensitivity by positive and negative regulation of the expression of diverse genes. Of note, PCR array data showed downregulation of Slc2A4, a coding gene for Glut4. Altogether, the present study concludes that the upregulation of miR-494 expression by TNF-α-mediated inflammation exacerbates insulin resistance. Therefore, we suggest that miR-494 could prove an important target for the diagnosis and therapy of inflammation-mediated insulin resistance in muscle.
Zeolites are mainly used for the adsorption and separation of ions and small molecules, and as he... more Zeolites are mainly used for the adsorption and separation of ions and small molecules, and as heterogeneous catalysts. More recently, these materials are receiving attention in other applications, such as medical diagnosis and as components in electronic devices. Modern synthetic methodologies for preparing zeolites and zeolite-like materials typically involve the use of organic molecules that direct the assembly pathway and ultimately fill the pore space. Removal of these enclathrated species normally requires high temperature combustion that destroys this high cost component, and the associated energy release in combination with the formed water can be extremely detrimental to the inorganic structure. Here we report a synthetic methodology that avoids these difficulties by creating organic structure-directing agents (SDAs) that can be disassembled within the zeolite pore space to allow removal of their fragments for possible use again by reassembly. The methodology is shown for the synthesis of zeolite ZSM-5 using a SDA that contains a cyclic ketal group that is removed from the SDA while it is inside the zeolite without destruction of the inorganic framework. This approach should be applicable to the synthesis of a wide variety of inorganic and organometallic structures.
The first asymmetric total syntheses of the dihalogenated medium-sized dioxabicyclic marine natur... more The first asymmetric total syntheses of the dihalogenated medium-sized dioxabicyclic marine natural products (+)-3-(Z)-isolaureatin (1) and (+)-3-(Z)-laureatin (2) have been accomplished. Notable features of the highly stereo-, regio-, and chemoselective syntheses of these alpha,alpha'-trans-oxocene natural products include an intramolecular amide enolate alkylation to construct the alpha,alpha'-cis-oxocene, novel "lone pair-lone pair interaction-controlled" epimerizations to the alpha,alpha'-trans-oxocenes, various strategies for stereoselective introduction of halogen atoms, and novel olefin cross-metatheses for construction of the (Z)-enyne systems.
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