Jae Won Yang

Seoul National University of Science and Technology, Sŏul, Seoul, South Korea

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Publications (44)118.89 Total impact

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    ABSTRACT: Copeptin has been considered as a useful marker for diagnosis and prediction of prognosis in heart diseases. However, copeptin has not been investigated sufficiently in hemodialysis patients. This study aimed to investigate the general features of copeptin in hemodialysis and to examine the usefulness of copeptin in hemodialysis patients with left ventricular dysfunction (LV dysfunction). This study included 41 patients on regular hemodialysis. Routine laboratory data and peptides such as the N-terminal of the prohormone brain natriuretic peptide and copeptin were measured on the day of hemodialysis. Body fluid volume was estimated by bioimpedance spectroscopy, and the E/Ea ratio was estimated by echocardiography. Copeptin increased to 171.4 pg/mL before hemodialysis. The copeptin had a positive correlation with pre-dialysis body fluid volume (r=0.314; p=0.04). The copeptin level decreased along with body fluid volume and plasma osmolality during hemodialysis. The copeptin increased in the patients with LV dysfunction more than in those with normal LV function (218.7 pg/mL vs. 77.6 pg/mL; p=0.01). Receiver operating characteristic curve analysis showed that copeptin had a diagnostic value in the hemodialysis patients with LV dysfunction (area under curve 0.737; p=0.02) and that the cut-off value was 125.48 pg/mL (sensitivity 0.7, specificity 0.8, positive predictive value 0.9, negative predictive value 0.6). Copeptin increases in hemodialysis patients and is higher in patients with LV dysfunction. We believe that copeptin can be a useful marker for the diagnosis of LV dysfunction in hemodialysis patients.
    Yonsei medical journal 07/2015; 56(4):976-980. DOI:10.3349/ymj.2015.56.4.976 · 1.26 Impact Factor
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    ABSTRACT: The Oxford classification of immunoglobulin A nephropathy (IgAN) is a pathology-based prognostic classification system. However, further study is needed to determine its validity. We studied the relationships between the Oxford classification and established prognostic factors and renal survival. We also examined associations between electron microscopy findings and these parameters.
    01/2015; 88(4):397. DOI:10.3904/kjm.2015.88.4.397
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    ABSTRACT: The polymer-supported transfer of chemical vapor deposition (CVD)-grown graphene provides large-area and high-quality graphene on a target substrate; however, the polymer and organic solvent residues left by the transfer process hinder the application of CVD-grown graphene in electronic and photonic devices. Here, we describe an inverse transfer method (ITM) that permits the simultaneous transfer and doping of graphene without generating undesirable residues by using polymers with different functional groups. Unlike conventional wet transfer methods, the polymer supporting layer used in the ITM serves as a graphene doping layer placed at the interface between the graphene and the substrate. Polymers bearing functional groups can induce n-doping or p-doping into the graphene depending on the electron donating or withdrawing characteristics of functional groups. Theoretical models of dipole layer-induced graphene doping offered insights into the experimentally measured change in the work function and the Dirac point of the graphene. Finally, the electrical properties of pentacene field effect transistors prepared using graphene electrodes could be enhanced by employing the ITM to introduce a polymer layer that tuned the work function of graphene. The versatility of polymer functional groups suggests that the method developed here will provide valuable routes to the development of applications of CVD-grown graphene in organic electronic devices.
    ACS Nano 07/2014; 8(8). DOI:10.1021/nn503329s · 12.03 Impact Factor
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    ABSTRACT: Oxalate nephropathy is commonly caused by ethylene glycol, vitamin C, and foods like star fruit that contain a lot of oxalate. Peanuts also have high oxalate contents. However, case reports of peanut-induced oxalate nephropathy are not common. Here, we describe a case of peanut-induced acute oxalate nephropathy with acute kidney injury and intend to demonstrate the conditions under which peanut-induced oxalate nephropathy is likely to occur.
    06/2014; 33(2). DOI:10.1016/j.krcp.2014.03.003
  • Jae‐Won Yang, Hyun‐Lark Do
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    ABSTRACT: SUMMARYA soft-switching high step-up DC-DC converter with a single magnetic component is presented in this paper. The proposed converter can provide high voltage gain with a relatively low turn ratio of a transformer. Voltage doubler structure is selected for the output stage. Due to this structure, the voltage gain can be increased, and the voltage stresses of output diodes are clamped as the output voltage. Moreover, the output diode currents are controlled by a leakage inductance of a transformer, and the reverse-recovery loss of the output diodes is significantly reduced. Two power switches in the proposed converter can operate with soft-switching due to the reflected secondary current. The voltages across the power switches are confined to the clamping capacitor voltage. Steady-state analysis, simulation, and experimental results for the proposed converter are presented to validate the feasibility and the performance of the proposed converter. Copyright © 2012 John Wiley & Sons, Ltd.
    International Journal of Circuit Theory and Applications 06/2014; 42(6). DOI:10.1002/cta.1876 · 1.21 Impact Factor
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    ABSTRACT: Aims: Urinary cystatin C has been suggested as a useful biomarker for diagnosis of acute kidney injury (AKI). Multiple myeloma is often complicated by AKI. Therefore, we investigated whether the urinary cystatin C was available for diagnosis of AKI in multiple myeloma. Materials and methods: This study included 39 patients with monoclonal gammopathy of undetermined significance (MGUS) or multiple myeloma. We reviewed the medical records retrospectively and investigated whether urinary γ-globulin and myeloma progression had effects on urinary cystatin C excretion. Results: Spearman's correlation analysis showed that serum β2-microglobulin and serum cystatin C had a significant positive correlation with the urinary cystatin C excretion (r = 0.513, p = 0.001, r = 0.659, p < 0.001) and FEcystatinC (r = 0.585, p = 0.002, r = 0.711, p < 0.001). The GFRcr also had a significant negative correlation with the urinary cystatin C excretion (r = -0.582, p < 0.001) and FEcystatinC (r = -0.474, p = 0.002). In addition, the urinary γ-globulin had a significant positive correlation with the urinary cystatin C excretion (r = 0.678, p < 0.001) and FEcystatinC (r = 0.731, p < 0.001). Urinary γ-globulin was the most significant factor to influence urinary cystatin C excretion in multiple regression test. Conclusion: These results indicate that urinary γ-globulin and myeloma progression can increase the fractional and total excretion of urinary cystatin C. Therefore, it is believed that the urinary cystatin C can be affected by urinary γ-globulin and myeloma progression in the diagnosis of AKI in multiple myeloma. In addition, urinary γ-globulin is believed to be the most significant factor to influence on urinary cystatin C.
    Clinical nephrology 05/2014; 81(5):345-349. DOI:10.5414/CN107963 · 1.23 Impact Factor
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    ABSTRACT: Purpose: Estimation of body fluid volume in hyponatremia is useful for diagnosis and therapeutic decision-making. Physical examination has been generally used to estimate body fluid volume, but it depends on the physician's abilities. Bioimpedance spectroscopy has been suggested to be a reliable method for the estimation of body fluid volume. Therefore, this study investigated whether bioimpedance spectroscopy could replace physical examination in hyponatremia. Materials and Methods: The study included 30 patients with hyponatremia. At the time of the initial visit, body fluid volume was estimated simultaneously by both physical examination and bioimpedance spectroscopy. Estimation of body fluid status by clinical diagnosis was performed as well, which determined body fluid status corresponds with the most likely cause of hyponatremia (clinical body fluid estimation). Results: The results of body fluid volume estimated by physical examination, bioimpedance spectroscopy, and clinical body fluid estimation showed that 9, 10, and 9 patients, respectively, were hypervolemic; 13, 15 and 16 patients, respectively, were euvolemic; and 8, 5, and 5 patients, respectively, were hypovolemic. Cohen's kappa analysis showed a significant agreement between physical examination and bioimpedance spectroscopy (kappa coefficient, 0.632, p<0.001). In addition, bioimpedance spectroscopy showed a higher level of agreement with clinical body fluid estimation than physical examination (kappa coefficient, 0.602 vs. 0.524). Conclusion: This study suggests that bioimpedance spectroscopy could replace physical examination for estimating body fluid status in hyponatremia. In addition, bioimpedance spectroscopy might correspond better with clinical diagnosis than physical examination in the estimation of body fluid status in hyponatremia.
    Yonsei medical journal 03/2014; 55(2):482-6. DOI:10.3349/ymj.2014.55.2.482 · 1.26 Impact Factor
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    ABSTRACT: Kidney transplantation is the preferred treatment in end stage renal disease for autosomal dominant polycystic kidney disease (ADPKD) patients. Removal of the native kidney is not usually recommended for ADPKD patients during a transplantation procedure because the operation time may be prolonged or the risk of bleeding may be higher. Therefore, native kidney removal is indicated for patients with chronic pain by enlarged kidney, frequent complications from cysts, such as infection or bleeding, and renal tumor development. Here, we report a case of a patient whose native kidneys were removed during a kidney transplantation procedure, and multifocal adenomas were identified in the removed kidneys after the procedure.
    01/2014; 28(4):246. DOI:10.4285/jkstn.2014.28.4.246
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    ABSTRACT: Epitaxial semiconductor/graphene double heterostructures are fabricated by vapor-phase van der Waals epitaxy of InAs on both sides of suspended graphene, as reported on page 6847. K. S. Kim, Y. J. Hong and co-workers demonstrate that the weak van der Waals attraction facilitates a preferential growth direction of InAs exclusively along the As-polar direction, which results in a polarity inversion of the double heterostructures. The first-principles and density functional calculations clarify why and how the conductive graphene layer yields the polarity inversion for sp(3) /sp(2) /sp(3) -type double heterostructures.
    Advanced Materials 12/2013; 25(47):6914. DOI:10.1002/adma.201370295 · 15.41 Impact Factor
  • 11/2013; 215(1). DOI:10.1016/j.psychres.2013.11.006
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    ABSTRACT: Background: Autism spectrum disorder (ASD) is a neurobiological disorder characterized by distinctive impairments in cognitive function, language, and behavior. Linkage and population studies suggest a genetic association between solute carrier family 6 member 4 (SLC6A4) variants and ASD. Method: Logistic regression was used to identify associations between single-nucleotide polymorphisms (SNPs) and ASD with 3 alternative models (additive, dominant, and recessive). Linear regression analysis was performed to determine the influence of SNPs on Childhood Autism Rating Scale (CARS) scores as a quantitative phenotype. Results: In the present study, we examined the associations of SNPs in the SLC6A4 gene and the fibrinogen alpha chain (FGA) gene. Logistic regression analysis showed a significant association between the risk of ASD and rs2070025 and rs2070011 in the FGA gene. The gene-gene interaction between SLC6A4 and FGA was not significantly associated with ASD susceptibility. However, polymorphisms in both SLC6A4 and the FGA gene significantly affected the symptoms of ASD. Conclusion: Our findings indicate that FGA and SLC6A4 gene interactions may contribute to the phenotypes of ASD rather than the incidence of ASD. © 2013 S. Karger AG, Basel.
    Neuropsychobiology 11/2013; 68(4):212-220. DOI:10.1159/000355299 · 2.30 Impact Factor
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    ABSTRACT: In the management of mallet deformities, oblique retinacular ligament (ORL) reconstruction provides a mechanism for automatic distal interphalangeal (DIP) joint extension upon active proximal interphalangeal joint extension. The two variants of ORL reconstruction utilize either the lateral band or a free tendon graft. This study aims to compare these two surgical techniques and to assess any differences in functional outcome. As a secondary measure, the Mitek bone anchor and pull-in suture methods are compared. A single-institutional retrospective review of ORL reconstruction was performed. The standard patient demographics, injury mechanism, type of ORL reconstruction, and pre/postoperative degree of extension lag were collected for the 27 cases identified. The cases were divided into lateral band (group A, n=15) and free tendon graft groups (group B, n=12). Group B was subdivided into the pull-in suture technique (B-I) and the Mitek bone anchor method (B-II). Overall, ORL reconstructions had improved the mean DIP extension lag by 10° (P=0.027). Neither the reconstructive technique choice nor bone fixation method identified any statistically meaningful difference in functional outcome (P=0.51 and P=0.83, respectively). Soft-tissue injury was associated with 30.8° of improvement in the extension lag. The most common complications were tendon adhesion and rupture. The choice of the ORL reconstructive technique or the bone anchor method did not influence the primary functional outcome of extension lag in this study. Both lateral band and free tendon graft ORL reconstructions are valid treatment methods in the management of chronic mallet deformity.
    11/2013; 40(6):773-778. DOI:10.5999/aps.2013.40.6.773
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    ABSTRACT: Nurr1 is an orphan nuclear receptor best known for its essential role in the development and maintenance of midbrain dopaminergic (DA) neurons. During DA neurogenesis, Nurr1 directly targets human tyrosine hydroxylase (hTH). Here we investigated this targeting to identify the molecular mechanisms by which Nurr1 regulates DA neurogenesis. We previously cloned the hTH promoter and found three consensus elements for Nurr1 binding: NBRE-A, -B, and -C. In the present study, gel retardation and luciferase assays using hTH constructs showed that Nurr1 preferentially bound to NBRE-A, through which it mediated transcriptional activity. Furthermore, Nurr1 displayed dual-function transcriptional activities depending on the cell type. In DA-like SH-SY5Y cells, Nurr1 dose-dependently stimulated hTH-3174 promoter activity by 7- to 11-fold. However, in the human neural stem cell (hNSC) line HB1.F3, Nurr1 strongly repressed transcription from the same promoter. This repression was relieved by mutation of only the NBRE-A element and by nicotinamide [an inhibitor of class III histone deacetylases (HDACs), such as SIRT1], but not by trichostatin A (an inhibitor of class I and II HDACs). SIRT1 was strongly expressed in the nucleus of HB1.F3 cells, while it was localized in the cytoplasm in SH-SY5Y cells. ChIP assays of HB1.F3 cells showed that Nurr1 overexpression significantly increased the SIRT1 occupancy of the NBRE-A hTH promoter region, while low SIRT1 levels were observed in control cells. In contrast, no significant SIRT1 recruitment was observed in SH-SY5Y cells. These results indicate that differential SIRT1 localization may be involved in hTH gene regulation. Overall, our findings suggest that Nurr1 exists in dual transcriptional complexes, including co-repressor complexes that can be remodeled to become co-activators and can fine-tune hTH gene transcription during human DA neurogenesis.
    PLoS ONE 08/2013; 8(8):e71469. DOI:10.1371/journal.pone.0071469 · 3.53 Impact Factor
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    ABSTRACT: The reconstruction of volar surface defects is difficult because of the special histologic nature of the tissue involved. The plantar surface is the most homologous in shape and function and could be considered the most ideal of reconstructive options in select cases of volar surface defects. In this paper, we evaluate a single institutional case series of volar tissue defects managed with second toe plantar free flaps. A single-institution retrospective review was performed on 12 cases of reconstruction using a second toe plantar free flap. The mean age was 33 years (range, 9 to 54 years) with a male-to-female ratio of 5-to-1. The predominant mechanism was crush injury (8 cases) followed by amputations (3 cases) and a single case of burn injury. Half of the indications (6 cases) were for soft-tissue defects with the other half for scar contracture. All of the flaps survived through the follow-up period. Sensory recovery was related to the time interval between injury and reconstruction-with delayed operations portending worse outcomes. There were no postoperative complications in this series. Flexion contracture is the key functional deficit of volar tissue defects. The second toe plantar free flap is the singular flap whose histology most closely matches those of the original volar tissue. In our experience, this flap is the superior reconstructive option within the specific indications dictated by the defect size and location.
    05/2013; 40(3):226-31. DOI:10.5999/aps.2013.40.3.226
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    ABSTRACT: Autism spectrum disorder (ASD) is a neurodevelopmental syndrome associated with impairments of reciprocal communication and cognitive function. Associations between single-nucleotide polymorphisms (SNPs) and ASD were analysed by logistic regression. Polymorphisms in FNDC3A exhibited significant associations in genotype and diplotype analyses. We conclude that FNDC3A influences the prevalence of ASD.
    04/2013; DOI:10.1016/j.psychres.2013.02.028
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    ABSTRACT: Background: The cyclosporin A (CsA) nephrotoxicity limits its usefulness as an immunosuppression. We studied the administration of both nitroprusside and phosphodiesterase-5 inhibitor (udenafil) in order to determine whether these agents could ameliorate the renal injury in CsA nephrotoxicity. Methods: 30 8-week-old SD rats were divided into 5 groups: the control (1), SQ with 15 mg/kg CsA (Group 2), CsA along with 5 mg/kg IP nitroprusside (Group 3), CsA with 10 mg/kg PO udenafil (Group 4), and CsA with udenafil and nitroprusside (Group 5). Results: Group showed an increase in creatinine compared o the control group. Group 5 showed a decrease in creatinine compared to Group 2. In TUNEL, Group 2 increased apoptosis in proximal tubules compared to control. Group 5 showed a decrease in apoptosis compared to Groups 2, 3, and 4. In IHC, the eNOS in Group 2 was stronger than in the controls. Groups 3, 4, and 5 showed decreased staining intensity compared to Group 2. In IHC, the VEGF in Groups 2, 3, and 4 increased compared to the controls. The eNOS protein expression was increased in both Groups 3 and 5 compared to the controls. The VEGF protein expression was increased in Groups 3 and 5 compared to Group 2. The eNOS mRNA was decreased in Group 2 compared to the control group and tended to increase in Groups 3, 4, and 5 compared to Group 2. The VEGF mRNA was increased in Group 2 and tended to increase more in Groups 3 and 5. Conclusion: The udenafil and nitroprusside ameliorated renal injury in rat model of CsA nephrotoxicity. The mechanism appears to be associated with decreasing tubular apoptosis by decreasing eNOS and increasing VEGF.
    Clinical nephrology 02/2013; 80(07). DOI:10.5414/CN107571 · 1.23 Impact Factor
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    ABSTRACT: BACKGROUND:: Genetic variations in interleukin 28B (IL28B) have been strongly associated with a sustained virological response (SVR) in European and African-American patients. Genetic variation of IL28B was investigated in healthy controls and chronic hepatitis C (CHC) patients, and the treatment response in the CHC patients was analyzed according to IL28B polymorphism in the Korean population. METHODS:: IL28B polymorphisms (rs12979860 and rs8099917) were studied in 200 healthy controls and in 167 CHC patients who were treated with peginterferon-α and ribavirin. RESULTS:: The prevalence of rs12979860 in healthy controls is as follows: the CC-genotype was 88.5%, the CT-genotype was 11.5%, and the TT-genotype was not found. The prevalence of rs8099917 in healthy controls is as follows: the TT-genotype was 89.5%, the TG-genotype was 10.5%, and the GG-genotype was not found. The CC-genotype of rs12979860 and the TT-genotype of rs8099917 were found to be closely related (linkage disequilibrium; D'=1.0, χ=0.9082). In 106 CHC patients treated with peginterferon and ribavirin, the SVR was 67.2% (n=58) for 1b, 91.6% (n=47) for 2a. In hepatitis C virus (HCV) genotype 1b with respect to rs12979860, the SVR in CC-genotype was 72.9% and that in CT-genotype was 40.0%. On investigating predictive factors for SVR, pretreatment low-HCV RNA levels, HCV genotype non-1, early virological response, and also the IL28B CC-genotype for rs12979860 were good indicators of an SVR. CONCLUSIONS:: In Korea, genetic variation of IL28B is different from that in western countries in view of high prevalence of rs12979860 CC-genotype. It seems likely that a high SVR in Korean patients with genotype 1 CHC patients is due to the genetic polymorphism in IL28B.
    Journal of clinical gastroenterology 02/2013; DOI:10.1097/MCG.0b013e3182896abf · 3.19 Impact Factor
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    ABSTRACT: Despite intense studies of carbon nanotubes for decades, the separation of semiconducting and metallic single-walled carbon nanotubes (SWNTs) remains to be one of the most important tasks to be resolved. Here we demonstrate that a K atom binds the semiconducting SWNTs more strongly than the metallic SWNTs, while this binding strength hierarchy is reversed for a K+ ion, consistent with experimental reports. This was shown by first-principles calculations, which properly describe the van der Waals interactions, and the origin of such results is explained. These results could be exploited as useful guidance toward separating semiconducting and metallic SWNTs via noncovalent functionalization.
    The Journal of Physical Chemistry C 02/2013; 117(8):4309–4313. DOI:10.1021/jp3123902 · 4.84 Impact Factor
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    ABSTRACT: Here, we report a substrate-induced intercalation phenomenon of an organic solvent at the interface between monolayer graphene and a target substrate. A simple dipping of the transferred chemical vapor deposition (CVD)-grown graphene on the SiO(2) substrate into chloroform (CHCl(3), CF), a common organic solvent, induces a spontaneous formation of CF clusters beneath the basal plane of the graphene as well as inside the wrinkles. The microscopic and spectroscopic observations showed the doping behavior of monolayer graphene, which indicates the adsorption of CF to monolayer graphene. Interestingly, the intercalated organic solvent showed remarkable stability for over 40 days under ambient conditions. To reveal the underlying mechanism of the stable solvent intercalation, desorption energy of CF molecules at the graphene/substrate interface was measured using Arrhenius plots of the conductance change upon time and temperature. Two stages of solvent intercalations with high desorption energies (70 and 370 meV) were observed along with the consecutive shrinkage of the solvent clusters at the basal plane and the wrinkles, respectively. Moreover, the theoretical calculation based on density functional theory (DFT) also shows the strong intercalation energy of CF between monolayer graphene and the SiO(2) substrate, which results from the stabilization of the graphene-SiO(2) interactions. Furthermore, the thermal response of the conductance could be utilized to maintain a certain degree of p-doping of monolayer graphene, which provides the facile, sustainable, and controllable large-area doping method of graphene for future generation of printed flexible electronics.
    ACS Nano 01/2013; 7(2). DOI:10.1021/nn306012p · 12.03 Impact Factor

Publication Stats

243 Citations
118.89 Total Impact Points

Institutions

  • 2014
    • Seoul National University of Science and Technology
      • Department of Electric Information System Engineering
      Sŏul, Seoul, South Korea
  • 2011–2014
    • Pohang University of Science and Technology
      • • Department of Chemical Engineering
      • • Department of Physics
      Geijitsu, Gyeongsangbuk-do, South Korea
  • 2009–2014
    • Yonsei University
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea
  • 2013
    • Korea University
      • Department of Psychiatry
      Sŏul, Seoul, South Korea
    • The Advanced Institutes of Convergence Technology
      Yeoncheon Gun, South Korea
  • 2008–2013
    • Yonsei University Hospital
      • Department of Internal Medicine
      Seoul, Seoul, South Korea
  • 2006–2013
    • Ajou University
      • • Brain Disease Research Center
      • • Institute for Medical Sciences
      Sŏul, Seoul, South Korea
  • 2007
    • Samsung Medical Center
      Sŏul, Seoul, South Korea