Publications by authors named "Sung W Choi"

Objective: We developed a Revised Korean version of the Geriatric Depression Scale (GDS-KR) and examined its reliability, validity, and factor structures. We also estimated its optimal cutoff scores for major depressive disorder (MDD) and minor depressive disorder (MnDD) stratified by age and education.

Methods: The GDS-KR was administered to 888 subjects (61 MDD patients, 45 MnDD patients, and 782 normal elders).

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For therapeutic applications of small interfering RNA (siRNA), serum stability, enhanced cellular uptake, and facile endosome escape are key issues for designing carriers. In this study, green fluorescent protein (GFP) siRNA was conjugated to a six-arm polyethylene glycol (PEG) derivative via a reducible disulfide linkage (6PEG-siRNA). The 6PEG-siRNA conjugate was also functionalized with a cell penetrating peptide, Hph1 to enhance its cellular uptake property (6PEG-siRNA-Hph1).

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Purpose Of Review: Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT), despite improvements in our understanding of its pathophysiology as well as the generation of new monoclonal antibodies, immunomodulatory chemotherapy, cellular therapeutics and supportive care. Herein, we review therapies that have proven effective as well as newer agents that have recently improved GVHD response rates and survival following HCT.

Recent Findings: Novel approaches to prevent or treat GVHD are often based on evidence from experimental models.

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Objectives: The aim of this study was to investigate the association of blood pressure levels with the common carotid artery intima-media thickness (CCA-IMT) and carotid plaques.

Methods: Data were obtained from 2,635 subjects, aged 50 years and over, who participated in the Community Health Survey (a population-based, cross-sectional study) in Dong-gu, Gwangju city between 2007 and 2008. Participants were categorized into three groups according to blood pressure levels; normotensives (<120/80 mmHg), prehypertensives (120-139/80-89 mmHg), and hypertensives (> or =140/90 mmHg).

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Autologous chondrocyte implantation (ACI) is widely used to treat symptomatic articular cartilage injury of the knee. Fibrin ACI is a new tissue-engineering technique for the treatment of full-thickness articular cartilage defects, in which autologous chondrocytes are inserted into a three-dimensional scaffold provided by fibrin gel. The objective of this study is to document and compare mean changes in overall clinical scores at both baseline and follow-up.

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Respirometry using modified cell culture microplates offers an increase in throughput and a decrease in biological material required for each assay. Plate based respirometers are susceptible to a range of diffusion phenomena; as O(2) is consumed by the specimen, atmospheric O(2) leaks into the measurement volume. Oxygen also dissolves in and diffuses passively through the polystyrene commonly used as a microplate material.

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Pre-synaptic nerve terminals (synaptosomes) require ATP for neurotransmitter exocytosis and recovery and for ionic homeostasis, and are consequently abundantly furnished with mitochondria. Pre-synaptic mitochondrial dysfunction is implicated in a variety of neurodegenerative disorders, although there is no precise definition of the term 'dysfunction'. In this study, we test the hypothesis that partial restriction of electron transport through Complexes I and II in synaptosomes to mimic possible defects associated with Parkinson's and Huntington's diseases respectively, sensitizes individual terminals to mitochondrial depolarization under conditions of enhanced proton current utilization, even though these stresses are within the respiratory capacity of the synaptosomes when averaged over the entire population.

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Purpose: This study examined the rate of degeneration of acetabular cartilage by the bipolar head according to time, and also which clinical factors are related to the degeneration of acetabular cartilage.

Materials And Methods: Among 192 patients (226 hip joints) who received bipolar hemiarthroplasty from August 1996 to August 2002, 61 patients (65 hip joints) were enrolled in this study, who were followed up for more than 2 years and showed no signs of dislocation, infection, or functional problems. A modified form of a computer assisted vector wear analysis program was used to measure the rate of degeneration of the acetabular cartilage.

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No validated biomarkers exist for acute graft-versus-host disease (GVHD). We screened plasma with antibody microarrays for 120 proteins in a discovery set of 42 patients who underwent transplantation that revealed 8 potential biomarkers for diagnostic of GVHD. We then measured by enzyme-linked immunosorbent assay (ELISA) the levels of these biomarkers in samples from 424 patients who underwent transplantation randomly divided into training (n = 282) and validation (n = 142) sets.

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Peroxiredoxin 6 (Prdx6) is a bifunctional enzyme with peroxidase activity and Ca2+-independent phospholipase A2 (iPLA2) activity. Here, we report that H2O2-induced cellular toxicity acts through Prdx6 hyperoxidation. Under high concentrations of H2O2 (> 100 microm), Prdx6, and 2-Cys Prdxs were hyperoxidized.

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Purpose: We developed a numerical model that predicts cardiovascular system response to hemodialysis, focusing on the effect of sodium profile during treatment.

Materials And Methods: The model consists of a 2-compartment solute kinetics model, 3-compartment body fluid model, and 12-lumped-parameter representation of the cardiovascular circulation model connected to set-point models of the arterial baroreflexes. The solute kinetics model includes the dynamics of solutes in the intracellular and extracellular pools and a fluid balance model for the intracellular, interstitial, and plasma volumes.

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Poly( L-lysine)- graft-dextran (PLL- g-dex), graft copolymers with dextran side chains grafted onto a poly( L-lysine) backbone, previously shown to be effective as stabilizers of DNA triple helices and as carriers of functional genes to target cells or tissues, were employed in this work to prevent nonspecific adsorption of proteins, as determined by means of optical waveguide lightmode spectroscopy. PLL- g-dex copolymers readily adsorb from aqueous solution onto negatively charged oxide surfaces and significantly reduce nonspecific protein adsorption onto bare silica-titania surfaces. While effective and equivalent surface adsorption and antifouling properties were observed for PLL- g-dex copolymers in a variety of architectures, nanotribological analysis by atomic force microscopy was able to distinguish between the different brush densities produced.

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Tumor necrosis factor-alpha (TNF-alpha) is known to play a role in the pathogenesis of graft-versus-host disease (GVHD), a cause of significant morbidity and treatment-related mortality (TRM) after allogeneic hematopoietic stem cell transplantation (HCT). We measured the concentration of TNF-Receptor-1 (TNFR1) in the plasma of HCT recipients as a surrogate marker for TNF-alpha both prior to transplant and at day 7 in 82 children who underwent a myeloablative allogeneic HCT at the University of Michigan between 2000 and 2005. GVHD grade II-IV developed in 39% of patients at a median of 20 days after HCT.

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Background: The chevron osteotomy is an acceptable method for correction of mild and moderate hallux valgus, but can result in instability at the osteotomy site. The purpose of this study was to present clinical and radiological results with our modified technique of osteotomy.

Materials And Methods: We performed a modified technique of distal osteotomy of the first metatarsal on 77 feet of 46 patients with symptomatic hallux valgus; followed up for an average of 52 months.

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Acute graft-versus-host disease (GVHD) remains a significant cause of mortality after hematopoietic cell transplantation (HCT). Tumor necrosis factor-alpha (TNF-alpha) mediates GVHD by amplifying donor immune responses to host tissues and by direct toxicity to target organs. We measured TNF receptor 1 (TNFR1) as a surrogate marker for TNF-alpha in 438 recipients of myeloablative HCT before transplantation and at day 7 after transplantation.

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On the basis of high binding affinity of 3'-aminoadenosine derivatives 2b at the human A3 adenosine receptor (AR), 3'-acetamidoadenosine derivatives 3a-e were synthesized from 1,2:5,6-di-O-isopropylidene-D-glucose via stereoselective hydroboration as a key step. Although all synthesized compounds were totally devoid of binding affinity at the human A3AR, our results revealed that 3'-position of adenosine can only be tolerated with small size of a hydrogen bonding donor like hydroxyl or amino group in the binding site of human A3AR.

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A series of poly(ethylene glycol)-block-poly(epsilon-caprolactone)-block-poly(ethylene glycol) (PEO-PCL-PEO) triblock copolymers were prepared and then used for the investigation of the effects of the ratio of epsilon-caprolactone to poly(ethylene glycol) (i.e., [CL]/[EO]) on the physical properties of water-in-oil-in-water (W(1)/O/W(2)) multiple emulsions containing a model reagent, ascorbic acid-2-glucoside (AA2G).

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Background: The management of acute acromioclavicular (AC) joint dislocation is controversial.

Purpose: The authors describe a surgical technique involving securing the clavicle to the coracoid process using suture anchors for the treatment of acute AC joint injury.

Study Design: Case series; Level of evidence, 4.

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Cationic comb-type copolymer (CCC) consisting of a polycationic backbone and abundant graft water-soluble chains exhibited considerable stabilization effect on DNA hybrids, such as double- and triple-stranded DNAs. Here, we describe the effect of CCC on antiparallel G-quadruplex folding of human telomeric DNA, d(GGGTTA)(n) in the presence of sodium ions. CCC did not significantly alter the circular dichroism (CD) spectra of d((GGGTTA)(3)GGG) and d((GGGTTA)(7)GGG) indicating that the CCC did not influence the antiparallel folding of the telomeric repeats.

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Graft-versus-host disease (GVHD) is a principal cause of morbidity following allogeneic hematopoietic cell transplantation (HCT). Standard therapy for GVHD, high-dose steroids, results in complete responses (CRs) in 35% of patients. Because tumor necrosis factor-alpha (TNFalpha) is an important effector of experimental GVHD, we treated patients with new-onset GVHD with steroids plus the TNFalpha inhibitor etanercept on a previously reported pilot trial (n = 20) and a phase 2 trial (n = 41).

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We have previously reported that poly(l-lysine)-graft-dextran cationic comb-type copolymers accelerate strand exchange reaction between duplex DNA and its complementary single strand by >4 orders of magnitude, while stabilizing duplex. However, the stabilization of the duplex is considered principally unfavourable for the accelerating activity since the strand exchange reaction requires, at least, partial melting of the initial duplex. Here we report the effects of different cationic moieties of cationic comb-type copolymers on the accelerating activity.

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A 4 base-pair deletion mutation in the Distal-less 3 (DLX3) gene is etiologic for Tricho-Dento-Osseous syndrome (TDO). A cardinal feature of TDO is an increased thickness and density of bone. We tested the effects of the DLX3 gene mutation responsible for TDO on the osteoblastic differentiation of preosteoblastic MC3T3E1 cells and multipontent mesenchymal C2C12 cells.

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Acute graft-versus-host disease (GVHD) and leukemic relapse are serious complications of allogeneic stem-cell transplantation (SCT). Recruitment of activated T cells to host target tissues or sites of leukemic infiltration (graft-versus-leukemia [GVL]) is likely mediated by chemokine receptor-ligand interactions. We examined the contribution of donor cell CCR1 expression to the development of GVHD and GVL using a well-established murine SCT model (B6 --> B6D2F1) and CCR1-deficient mice (CCR1(-/-)).

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