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Search Results: 1 - 10 of 46148 matches for " Dong-Hyun Kim "
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Synthesis and Characterization of Multifunctional Chitosan- MnFe2O4 Nanoparticles for Magnetic Hyperthermia and Drug Delivery
Dong-Hyun Kim,David E. Nikles,Christopher S. Brazel
Materials , 2010, DOI: 10.3390/ma3074051
Abstract: Multifunctional nanoparticles composed of MnFe 2O 4 were encapsulated in chitosan for investigation of system to combine magnetically-triggered drug delivery and localized hyperthermia for cancer treatment with the previously published capacity of MnFe 2O 4 to be used as an efficient MRI contrast agent for cancer diagnosis. This paper focuses on the synthesis and characterization of magnetic MnFe 2O 4 nanoparticles, their dispersion in water and their incorporation in chitosan, which serves as a drug carrier. The surface of the MnFe 2O 4 nanoparticles was modified with meso-2,3-di-mercaptosuccinic acid (DMSA) to develop stable aqueous dispersions. The nanoparticles were coated with chitosan, and the magnetic properties, heat generation and hydrodynamic size of chitosan-coated MnFe 2O 4 were evaluated for various linker concentrations and in a range of pH conditions.
Poincare Geometry-Characterized Arrhythmia Identification Scheme in Grid
Dong-Hyun Kim,Jin-Ho Kim,,Chan-Hyun Youn.
International Journal of Engineering Science and Technology , 2009,
Abstract: In this paper, we propose a new scheme of Poincare geometry-characterized ECG analysis for cardiac disease identification. Based on reliable P-wave detection we created P-P Poincare plot applying P-P intervals of ECG signal. By the new geometric Poincare plot analysis, which combines R-R intervals and P-P intervals, weidentified geometric differences of normal and arrhythmia ECG databases at PhysioBank in Physionet. Poincare descriptors show that the analysis scheme can classify two ECG signals reliably. Furthermore, we discuss a cardiac disease estimation system that may be applicable to estimate the occurrence of arrhythmia in healthy person.
Determination of S- and R-Amlodipine in Rat Plasma using LC-MS/MS After Oral Administration of S-Amlodipine and Racemic Amlodipine
Hye Hyun Yoo,Tae Kon Kim,Bong-Yong Lee,Dong-Hyun Kim
Mass Spectrometry Letters , 2011,
Abstract: The pharmacokinetic properties of S-amlodipine were studied using racemic amlodipine and single S-enantiomer(SK310) administration to rats. Plasma levels of the drug were determined using chiral liquid chromatography coupled with tandemmass spectrometry following solid phase extraction. The stereospecific analysis of amlodipine was performed on an α-acidglycoprotein (AGP) column using a mobile phase comprising 10 mM ammonium acetate (pH 4.0) and propanol at a flow rate of0.2 mL/min. This method was used to perform a comparative study of the pharmacokinetics of amlodipine and SK310. Theresults revealed that the pharmacokinetic profile of S-amlodipine after the administration of SK310 was comparable to thatfollowing the administration of the racemic mixture.
Targeting the PI3K/Akt Cell Survival Pathway to Induce Cell Death of HIV-1 Infected Macrophages with Alkylphospholipid Compounds
Amanda Lucas,Yuri Kim,Omayra Rivera-Pabon,Sunju Chae,Dong-Hyun Kim,Baek Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013121
Abstract: HIV-1 infected macrophages and microglia are long-lived viral reservoirs persistently producing viral progenies. HIV-1 infection extends the life span of macrophages by promoting the stress-induced activation of the PI3K/Akt cell survival pathway. Importantly, various cancers also display the PI3K/Akt activation for long-term cell survival and outgrowth, and Akt inhibitors have been extensively searched as anti-cancer agents. This led us to investigate whether Akt inhibitors could antagonize long-term survival and cytoprotective phenotype of HIV-1 infected macrophages.
Novel PI3K/Akt Inhibitors Screened by the Cytoprotective Function of Human Immunodeficiency Virus Type 1 Tat
Yuri Kim, Joseph A. Hollenbaugh, Dong-Hyun Kim, Baek Kim
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021781
Abstract: The PI3K/Akt pathway regulates various stress-related cellular responses such as cell survival, cell proliferation, metabolism and protein synthesis. Many cancer cell types display the activation of this pathway, and compounds inhibiting this cell survival pathway have been extensively evaluated as anti-cancer agents. In addition to cancers, several human viruses, such as HTLV, HPV, HCV and HIV-1, also modulate this pathway, presumably in order to extend the life span of the infected target cells for productive viral replication. The expression of HIV-1 Tat protein exhibited the cytoprotective effect in macrophages and a human microglial cell line by inhibiting the negative regulator of this pathway, PTEN. This cytoprotective effect of HIV-1 appears to contribute to the long-term survival and persistent HIV-1 production in human macrophage reservoirs. In this study we exploited the PI3K/Akt dependent cytoprotective effect of Tat-expressing CHME5 cells. We screened a collection of compounds known to modulate inflammation, and identified three novel compounds: Lancemaside A, Compound K and Arctigenin that abolished the cytoprotective phenotype of Tat-expressing CHME5 cells. All three compounds antagonized the kinase activity of Akt. Further detailed signaling studies revealed that each of these three compounds targeted different steps of the PI3K/Akt pathway. Arctigenin regulates the upstream PI3K enzyme from converting PIP2 to PIP3. Lancemaside A1 inhibited the movement of Akt to the plasma membrane, a critical step for Akt activation. Compound K inhibited Akt phosphorylation. This study supports that Tat-expressing CHME5 cells are an effective model system for screening novel PI3K/Akt inhibitors.
Dextran sulfate sodium and 2,4,6-trinitrobenzene sulfonic acid induce lipid peroxidation by the proliferation of intestinal gram-negative bacteria in mice
In-Ah Lee, Eun-Ah Bae, Yang-Jin Hyun, Dong-Hyun Kim
Journal of Inflammation , 2010, DOI: 10.1186/1476-9255-7-7
Abstract: Orally administered DSS and intrarectally injected TNBS all caused severe inflammation, manifested by shortened colons in both mice. These agents increased intestinal myeloperoxidase activity and the expression of the proinflammatory cytokines, IL-1β, TNF-α and IL-6, in the colon.DSS and TNBS induced the protein expression of TLR-4 and activated transcription factor NF-κB. However, these colitic agents did not express TLR-4 in C3H/HeJ mice. Of proinflammatory cytokines, IL-1β was most potently expressed in C3H/HeN mice. IL-1β potently induced NF-κB activation in CaCo-2 cells, but did not induce TLR-4 expression. DSS and TNBS increased lipid peroxide (malondialdehyde) and 4-hydroxy-2-nonenal content in the colon, but reduced glutathione content and superoxide dismutase and catalase activities. These colitic inducers increased the number of Enterobacteriaceae grown in DHL agar plates in both mice, although the number of anaerobes and bifidobacteria grown in GAM and BL agar plates was reduced. E. coli, K. pneumoniae and Proteus mirabilis isolated in DHL agar plates increased lipid peroxidation in liposomes prepared by L-α-phosphatidylcholine, but B. animalis and B. cholerium isolated from BL agar plates inhibited it.These findings suggest that DSS and TNBS may cause colitis by inducing lipid peroxidation and enterobacterial proliferation, which may deteriorate the colitis by regulating proinflammatory cytokines via TLR-4-linked NF-κB activation pathway.Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn disease, are chronically relapsing disorders of the intestine [1,2]. Its pathogenic mechanism is assumed to be a dysregulation of the intestinal immune response to intestinal environmental antigens, such as intestinal microflora, and characterized by the activation of lymphocytes, macrophages, enterocytes and endothelial cells, which cause the production of inflammatory mediators, such as IL-1β, IL-6 and TNF-α [3,4]. Intestinal microflora may play a
Hybrid Workflow Policy Management for Heart Disease Identification
Dong-Hyun Kim,Woo-Ram Jung,Chan-Hyun Youn.
International Journal of Engineering Science and Technology , 2009,
Abstract: As science technology grows, medical application is becoming more complex to solve the physiological problems within expected time. Workflow management systems (WMS) in Grid computing are promisingsolution to solve the sophisticated problem such as genomic analysis, drug discovery, disease identification, etc. Although existing WMS can provide basic management functionality in Grid environment, consideration of user requirements such as performance, reliability and interaction with user is missing. In this paper, we proposehybrid workflow management system for heart disease identification and discuss how to guarantee different user requirements according to user SLA. The proposed system is applied to Physio-Grid e-health platform to identify human heart disease with ECG analysis and Virtual Heart Simulation (VHS) workflow applications.
Hybrid Workflow Policy Management for Heart Disease Identification
Dong-Hyun Kim,Woo-Ram Jung,Chan-Hyun Youn
Physics , 2010,
Abstract: As science technology grows, medical application is becoming more complex to solve the physiological problems within expected time. Workflow management systems (WMS) in Grid computing are promising solution to solve the sophisticated problem such as genomic analysis, drug discovery, disease identification, etc. Although existing WMS can provide basic management functionality in Grid environment, consideration of user requirements such as performance, reliability and interaction with user is missing. In this paper, we propose hybrid workflow management system for heart disease identification and discuss how to guarantee different user requirements according to user SLA. The proposed system is applied to Physio-Grid e-health platform to identify human heart disease with ECG analysis and Virtual Heart Simulation (VHS) workflow applications.
Pleckstrin Homology Domain of Akt Kinase: A Proof of Principle for Highly Specific and Effective Non-Enzymatic Anti-Cancer Target
Eun-Ha Joh, Joseph A. Hollenbaugh, Baek Kim, Dong-Hyun Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050424
Abstract: While pharmacological inhibition of Akt kinase has been regarded as a promising anti-cancer strategy, most of the Akt inhibitors that have been developed are enzymatic inhibitors that target the kinase active site of Akt. Another key cellular regulatory event for Akt activation is the translocation of Akt kinase to the cell membrane from the cytoplasm, which is accomplished through the pleckstrin homology (PH) domain of Akt. However, compounds specifically interacting with the PH domain of Akt to inhibit Akt activation are currently limited. Here we identified a compound, lancemaside A (LAN-A), which specifically binds to the PH domain of Akt kinase. First, our mass spectra analysis of cellular Akt kinase isolated from cells treated with LAN-A revealed that LAN-A specifically binds to the PH domain of cellular Akt kinase. Second, we observed that LAN-A inhibits the translocation of Akt kinase to the membrane and thus Akt activation, as examined by the phosphorylation of various downstream targets of Akt such as GSK3β, mTOR and BAD. Third, in a co-cultured cell model containing human lung epithelial cancer cells (A549) and normal human primary lung fibroblasts, LAN-A specifically restricts the growth of the A549 cells. LAN-A also displayed anti-proliferative effects on various human cancer cell lines. Finally, in the A549-luciferase mouse transplant model, LAN-A effectively inhibited A549 cell growth with little evident cytotoxicity. Indeed, the therapeutic index of LAN-A in this mouse model was >250, supporting that LAN-A is a potential lead compound for PH domain targeting as a safe anti-cancer Akt inhibitor.
Preparation and Characteristics of SiOx Coated Carbon Nanotubes with High Surface Area
Aeran Kim,Seongyop Lim,Dong-Hyun Peck,Sang-Kyung Kim,Byungrok Lee,Doohwan Jung
Nanomaterials , 2012, DOI: 10.3390/nano2020206
Abstract: An easy method to synthesize SiO x coated carbon nanotubes (SiO x-CNT) through thermal decomposition of polycarbomethylsilane adsorbed on the surface of CNTs is reported. Physical properties of SiO x-CNT samples depending on various Si contents and synthesis conditions are examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen isotherm, scanning electron microscope (SEM), and transmission electron microscope (TEM). Morphology of the SiO x-CNT appears to be perfectly identical to that of the pristine CNT. It is confirmed that SiO x is formed in a thin layer of approximately 1 nm thickness over the surface of CNTs. The specific surface area is significantly increased by the coating, because thin layer of SiO x is highly porous. The surface properties such as porosity and thickness of SiO x layers are found to be controlled by SiO x contents and heat treatment conditions. The preparation method in this study is to provide useful nano-hybrid composite materials with multi-functional surface properties.
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