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Hwang S, Kim KH, Song GW, Yu YD, Park GC, Kim KW, Choi NK, Park PJ, Choi YI, Jung DH, Ahn CS, Moon DB, Ha TY, Lee SG. Peritransplant monitoring of immune cell function in adult living donor liver transplantation. Transplant Proc 2011; 42:2567-71. [PMID: 20832545 DOI: 10.1016/j.transproceed.2010.04.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 04/21/2010] [Indexed: 01/12/2023]
Abstract
PURPOSE We evaluated the clinical utility of peritransplant in vitro assays of immune cell function in adult living donor liver transplant (LDLT) recipients. METHODS In particular, we measured immune cell function, using the ImmuKnow assay, in 107 adult LDLT recipients and 200 potential living liver donors (control group) admitted to our center between July 2008 and January 2009. RESULTS In the control group, the mean proportion of T-helper/inducer cells was 36.8% ± 8.2%. The degree of immune response was strong in 12%, moderate in 77%, and low in 11%. In the study group, the degree of immune response within the first month was strong in 4.6%, moderate in 38.2%, and low in 57.2%, thus significantly lower than in the control group (P < .001). ImmuKnow results and tacrolimus levels did not show a significant correlation (r(2) = .002, P = .392). Although six patients showed biopsy-proven acute cellular rejection, none showed a strong immune response. Patients with overt infection showed a lower immune response. CONCLUSIONS These results indicate that peritransplant assessment of immune response using the ImmuKnow assay does not reliably predict the occurrence of acute rejection. Additional studies are necessary to accurately assess the clinical utility of immune response monitoring.
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Lee JH, Kim JK, Kim TH, Park MS, Yu JS, Choi JY, Kim JH, Kim YB, Kim KW. MRI features of serous oligocystic adenoma of the pancreas: differentiation from mucinous cystic neoplasm of the pancreas. Br J Radiol 2011; 85:571-6. [PMID: 21304008 DOI: 10.1259/bjr/42007785] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
OBJECTIVES The purpose of this study was to describe the MRI features of the benign pancreatic neoplasm serous oligocystic adenoma (SOA) that differ from those of mucinous cystic neoplasm (MCN), a neoplasm with the potential for malignant degeneration. METHODS Seven patients with SOA (seven women; mean age 36.6 years) and eight patients with MCN (eight women: mean age 39.9 years) were included. Several imaging features were reviewed: mass size, location, shape, wall thickness, cyst configuration (Type I, unilocular; Type II, multiple clustered cyst; Type III, cyst with internal septation) and signal intensity of the lesion with heterogeneity. RESULTS SOA lesions were smaller (3.4 cm) than those of MCN (9.3 cm) (p=0.023). The commonest lesion shape was lobulated (85.7%) for SOA, but oval (50.0%) or lobulated (37.5%) for MCN (p=0.015). The most common cyst configuration was Type II (85.7%) for SOA and Type III (75.0%) for MCN (p=0.008). Heterogeneity of each locule in T(1) weighted images was visible in all cases of MCN, but in no case for SOA (p=0.004). CONCLUSION SOA could be differentiated from MCN by identifying the imaging features of lobulated contour with multiple clustered cyst configurations and homogeneity of each locule in T(1) weighted MR images.
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Dubroka A, Rössle M, Kim KW, Malik VK, Munzar D, Basov DN, Schafgans AA, Moon SJ, Lin CT, Haug D, Hinkov V, Keimer B, Wolf T, Storey JG, Tallon JL, Bernhard C. Evidence of a precursor superconducting phase at temperatures as high as 180 K in RBa2Cu3O(7-δ) (R=Y, Gd, Eu) superconducting crystals from infrared spectroscopy. PHYSICAL REVIEW LETTERS 2011; 106:047006. [PMID: 21405352 DOI: 10.1103/physrevlett.106.047006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Indexed: 05/30/2023]
Abstract
We show that a multilayer analysis of the infrared c-axis response of RBa2Cu3O(7-δ) (R=Y, Gd, Eu) provides important new information about the anomalous normal-state properties of underdoped cuprate high temperature superconductors. In addition to competing correlations which give rise to a pseudogap that depletes the low-energy electronic states below T*≫T(c), it enables us to identify the onset of a precursor superconducting state below T(ons)>T(c). We map out the doping phase diagram of T(ons) which reaches a maximum of 180 K at strong underdoping and present magnetic field dependent data which confirm our conclusions.
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Kim KW, Lee HS, Choi JS, Seo KH, Oh MH, Jou SS, Kim YH, Na JO. Single Small Bowel Metastasis after Curative Operation in a Pleomorphic Lung Carcinoma. Tuberc Respir Dis (Seoul) 2011. [DOI: 10.4046/trd.2011.71.2.139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Mo SI, Lee HG, Cho AR, Chung HK, Kim KW, Lee HM, Kang BI, Ko GB, Lee SW, Nah SS. A Case of Klinefelter's Syndrome Associated with Rheumatoid Arthritis. JOURNAL OF RHEUMATIC DISEASES 2011. [DOI: 10.4078/jrd.2011.18.1.60] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Choi JS, Kim MJ, Kim JH, Choi JY, Chung YE, Park MS, Kim KW. Comparison of multi-echo and single-echo gradient-recalled echo sequences for SPIO-enhanced liver MRI at 3 T. Clin Radiol 2010; 65:916-23. [PMID: 20933647 DOI: 10.1016/j.crad.2010.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 07/02/2010] [Accepted: 07/14/2010] [Indexed: 01/04/2023]
Abstract
AIM To assess the utility of a T2*-weighted, multi-echo data imaging combination sequenced on superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) using a 3 T system. MATERIALS AND METHODS Fifty patients underwent SPIO-enhanced MRI at 3 T using T2*-weighted, single-echo, gradient-recalled echo (GRE) sequences [fast imaging with steady precession; repetition time (TR)/echo time (TE), 126 ms/9 ms; flip angle, 30°] and multi-echo GRE (multi-echo data image combination) sequences (TR/TE, 186 ms/9 ms; flip angle, 30°). Three radiologists independently reviewed the images in a random order. The sensitivity and accuracy for the detection of focal hepatic lesions (a total of 76 lesions in 33 patients; 48 solid lesions, 28 non-solid lesions) were compared by analysing the area under the receiver operating characteristic curves. Image artefacts (flow artefacts, susceptibility artefacts, dielectric artefacts, and motion artefacts), lesion conspicuity, and overall image quality were evaluated according to a four-point scale: 1, poor; 2, fair; 3, good; 4, excellent. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the lesions were compared. RESULTS Image artefacts were more frequent with single-echo GRE (p<0.05). The mean scale of image quality assessment for flow, susceptibility, dielectric, and motion artefacts were 2.76, 3.13, 3.42, and 2.89 with single-echo, respectively, compared with 3.47, 3.43, 3.47, and 3.39, respectively, with multi-echo GRE. There was no significant difference in lesion conspicuity between single-echo (3.15) and multi-echo (3.30) GRE sequences. The overall image quality was significantly (p<0.05) better with multi-echo (3.37) than with single-echo GRE (2.89). The mean SNR and CNR of the lesions were significantly (p<0.05) higher on multi-echo (79±23 and 128±59, respectively) images than on single-echo (38±11 and 102±44, respectively) images. Lesion detection accuracy and sensitivity were not significantly different between the two sequences. Mean accuracies and sensitivities were 0.864 and 0.785 for single-echo and 0.847 and 0.785 for multi-echo GRE, respectively. CONCLUSION At 3 T, the T2*-weighted, multi-echo data image combination sequence performs comparably to the T2*-weighted, single-echo GRE sequence for SPIO-enhanced MRI with good overall image quality and a decrease in undesired artefacts.
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Kim YC, Park MS, Chung YE, Kim MJ, Park YN, Kang JH, Kim KA, Kim KW. MRI findings of uncommon non-hepatocyte origin primary liver tumours with pathological correlation. Br J Radiol 2010; 83:1080-6. [PMID: 20923912 DOI: 10.1259/bjr/61140265] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The objective of this article was to illustrate the MRI findings of uncommon non-hepatocyte origin primary liver tumours, correlate them with the pathological features and discuss differential diagnoses. In conclusion, the MRI findings of uncommon benign and malignant non-hepatocyte-origin primary liver tumours vary. Awareness of characteristic MRI features can aid differential diagnosis and prevent unnecessary surgery.
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Park HK, Hong I, Kim M, Yun GS, Lee W, Kim J, Tobias B, Domier CW, Luhmann NC, Kim KW. Microwave imaging reflectometry studies for turbulence diagnostics on KSTAR. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:10D933. [PMID: 21033961 DOI: 10.1063/1.3499606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The first prototype microwave imaging reflectometry (MIR) system [H. Park et al., Rev. Sci. Instrum. 74, 4239 (2004)] clearly demonstrated the shortcomings of conventional reflectometry when the probe beam encountered a large amplitude and/or high fluctuation wavenumber at the reflection layer in laboratory tests, the distinctive advantages shown in these tests were not fully realized in the plasma operation. To understand the discrepancies, the MIR system performance has been thoroughly investigated at POSTECH. In this paper, a possible cause of the MIR performance degradation on TEXTOR will be presented together with a concept of multifrequency MIR system design that will be developed for KSTAR.
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Kim TH, Lee JY, Lee HM, Lee SH, Cho WS, Ju YH, Park EH, Kim KW, Lee SH. Remodelling of nasal mucosa in mild and severe persistent allergic rhinitis with special reference to the distribution of collagen, proteoglycans, and lymphatic vessels. Clin Exp Allergy 2010; 40:1742-54. [PMID: 20860724 DOI: 10.1111/j.1365-2222.2010.03612.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Small leucine-rich repeat proteoglycans (decorin, biglycan, and lumican), collagen, and lymphangiogenesis are involved in tissue remodelling of various organs with inflammatory diseases. OBJECTIVE We determined the expression level and the distribution pattern of small leucine-rich repeat proteoglycans (decorin, biglycan, and lumican), collagen and lymphatic vessels in healthy, mild, and severe persistent allergic nasal mucosa. METHODS The distribution pattern of collagen, proteoglycans, and lymphatic vessels in healthy, mild, and severe persistent allergic nasal mucosa was evaluated by the van Gieson staining, immunohistochemistry, RT-PCR, and Western blotting. Quantitative analyses of collagen deposition were calculated as the median of the total percentage area in the tissue specimen. For the evaluation of proteoglycans, the percentage area stained and median optical density were measured for each image. Lymphatic vessels were identified by D2-40 antibody and calculated using the lymphatic vessel density and endothelial length density in tissue specimens. The expression of MMP 2 and 9, TIMP1 and 2 was evaluated with RT-PCR and Western blotting. RESULTS In mild and severe persistent allergic nasal mucosa, compared with healthy nasal mucosa, collagen showed more intense staining in the superficial and submucosal layer. In healthy and allergic nasal mucosa, decorin was lightly stained without significant differences in the percentage area and optical density of staining. However, lumican and biglycan showed strong immunoreactivity in mild and severe persistent allergic nasal mucosa, which was verified by Western blotting. The number and endothelial length density of lymphatic vessels were increased in mild and severe persistent allergic nasal mucosa compared with healthy nasal mucosa. The expression of MMP 9 was increased in severe persistent allergic rhinitis. CONCLUSION AND CLINICAL RELEVANCE These results suggest that the altered distribution pattern of collagen, proteoglycans, and lymphatic vessels could potentially modulate the remodelling of nasal mucosa in mild and severe persistent allergic nasal mucosa.
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Chen Y, Jayasekera T, Calzolari A, Kim KW, Nardelli MB. Thermoelectric properties of graphene nanoribbons, junctions and superlattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:372202. [PMID: 21403189 DOI: 10.1088/0953-8984/22/37/372202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Using model interaction Hamiltonians for both electrons and phonons and Green's function formalism for ballistic transport, we have studied the thermal conductance and the thermoelectric properties of graphene nanoribbons (GNR), GNR junctions and periodic superlattices. Among our findings we have established the role that interfaces play in determining the thermoelectric response of GNR systems both across single junctions and in periodic superlattices. In general, increasing the number of interfaces in a single GNR system increases the peak ZT values that are thus maximized in a periodic superlattice. Moreover, we proved that the thermoelectric behavior is largely controlled by the width of the narrower component of the junction. Finally, we have demonstrated that chevron-type GNRs recently synthesized should display superior thermoelectric properties.
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Hong HS, Byun JH, Won HJ, Kim KW, Lee SS, Lee MG, Yun SC. Characterization of liver metastases: the efficacy of biphasic magnetic resonance imaging with ferucarbotran-enhancement. Clin Radiol 2010; 65:701-7. [PMID: 20696297 DOI: 10.1016/j.crad.2010.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Revised: 04/19/2010] [Accepted: 04/25/2010] [Indexed: 11/26/2022]
Abstract
AIM To retrospectively evaluate the efficacy of biphasic magnetic resonance imaging (MRI) of the liver with ferucarbotran-enhancement for the characterization of hepatic metastases. MATERIALS AND METHODS Thirty-six patients underwent MRI of the liver with separate acquisition of double-contrast enhancement consisting of gadolinium and ferucarbotran. A total of 106 focal hepatic lesions (51 metastases, 31 cysts, 23 haemangiomas, and one eosinophilic abscess) were included. Two sets of MRI were analysed: (1) ferucarbotran set: ferucarbotran-enhanced T1-weighted (T1W) dynamic imaging combined with ferucarbotran-enhanced T2*-weighted (T2*W) delayed imaging and (2) double set: gadolinium-enhanced T1W dynamic imaging combined with ferucarbotran-enhanced T2*W delayed imaging. The diagnostic accuracy of the two sets was evaluated using alternative free-response receiver operating characteristic curve analysis. Sensitivity and specificity were compared using the McNemar test. The enhancement pattern of focal hepatic lesions was analysed on gadolinium and ferucarbotran-enhanced T1W dynamic imaging. RESULTS There was no significant difference in the accuracy of characterizing hepatic metastases between the two sets. Sensitivity and specificity were not significantly different between the sets (p>0.05). Peripheral rim enhancement was exhibited in 57% of metastatic lesions on ferucarbotran-enhanced T1W dynamic imaging. The majority (96%) of hepatic haemangiomas demonstrated typical peripheral nodular enhancement with progression on ferucarbotran-enhanced T1W dynamic imaging and were easily differentiated from metastases. CONCLUSION Biphasic MRI of the liver with ferucarbotran-enhancement alone provided comparable diagnostic efficacy to double-contrast MRI for the characterization of hepatic metastases.
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Pashkin A, Porer M, Beyer M, Kim KW, Dubroka A, Bernhard C, Yao X, Dagan Y, Hackl R, Erb A, Demsar J, Huber R, Leitenstorfer A. Femtosecond response of quasiparticles and phonons in superconducting YBa(2)Cu(3)O(7-δ) studied by wideband terahertz spectroscopy. PHYSICAL REVIEW LETTERS 2010; 105:067001. [PMID: 20867998 DOI: 10.1103/physrevlett.105.067001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Indexed: 05/29/2023]
Abstract
We measure the anisotropic midinfrared response of electrons and phonons in bulk YBa(2)Cu(3)O(7-δ) after femtosecond photoexcitation. A line shape analysis of specific lattice modes reveals their transient occupation and coupling to the superconducting condensate. The apex oxygen vibration is strongly excited within 150 fs, demonstrating that the lattice absorbs a major portion of the pump energy before the quasiparticles are thermalized. Our results attest to substantial electron-phonon scattering and introduce a powerful concept probing electron-lattice interactions in a variety of complex materials.
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Marsik P, Kim KW, Dubroka A, Rössle M, Malik VK, Schulz L, Wang CN, Niedermayer C, Drew AJ, Willis M, Wolf T, Bernhard C. Coexistence and competition of magnetism and superconductivity on the nanometer scale in underdoped BaFe1.89Co0.11As2. PHYSICAL REVIEW LETTERS 2010; 105:057001. [PMID: 20867947 DOI: 10.1103/physrevlett.105.057001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Indexed: 05/29/2023]
Abstract
We report muon spin rotation (μSR) and infrared spectroscopy experiments on underdoped BaFe1.89Co0.11As2 which show that bulk magnetism and superconductivity (SC) coexist and compete on the nanometer length scale. Our combined data reveal a bulk magnetic order, likely due to an incommensurate spin density wave (SDW), which develops below T(mag)≈32 K and becomes reduced in magnitude (but not in volume) below Tc=21.7 K. A slowly fluctuating precursor of the SDW seems to develop already below the structural transition at T(s)≈50 K. The bulk nature of SC is established by the μSR data which show a bulk SC vortex lattice and the IR data which reveal that the majority of low-energy states is gapped and participates in the condensate at T≪T(c).
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Hong JY, Lee KE, Kim KW, Sohn MH, Kim KE. Chitinase induce the release of IL-8 in human airway epithelial cells, via Ca2+-dependent PKC and ERK pathways. Scand J Immunol 2010; 72:15-21. [PMID: 20591071 DOI: 10.1111/j.1365-3083.2010.02404.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chitinases are produced in significant quantities by hosts defending against infections with chitin-containing organisms. However, little is known about the immune response of exogenous chitinase in human epithelial cells. IL-8 has been suggested to have a role in the pathogenesis of the allergenic inflammation of bronchial asthma. We examined whether Streptomyces griseus (S. griseus) chitinase-induced IL-8 on airway epithelium and identified the involvement of intracellular signalling pathways. H292 cells were treated with S. griseus chitinase with different concentrations and times. The IL-8 levels were determined by specific human IL-8 enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction. Using a series of pharmacological inhibitors, we examined the upstream signalling pathway responsible for IL-8 expression in response to S. griseus chitinase. Cells exposed to S. griseus chitinase showed higher level of IL-8 protein production and mRNA expression. Cells stimulated by S. griseus chitinase resulted in the activation of protein kinase C (PKC), extracellular signal-regulated kinase (ERK) and nuclear factor kappa-B (NF-kB) pathways. Inhibitors of Ca(2+)-dependent PKC (Ro-31-8220, calphostin C and Go6976) significantly abolished chitinase-induced expression of IL-8. However, Ca(2+)-independent PKC inhibitor (rottlerin) did not inhibit IL-8 expression. Through ERK inhibitor (U0126) and NF-kB inhibitor (caffeine acid phenethyl ester) treatment, it was proven that ERK and NF-kB regulated chitinase-induced IL-8 expression. We concluded that S. griseus chitinase-induced IL-8 expression was regulated by the activation of Ca(2+/-)-dependent PKC, ERK and NF-kB in human airway epithelial cells.
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Véniant MM, Hale C, Hungate RW, Gahm K, Emery MG, Jona J, Joseph S, Adams J, Hague A, Moniz G, Zhang J, Bartberger MD, Li V, Syed R, Jordan S, Komorowski R, Chen MM, Cupples R, Kim KW, St. Jean DJ, Johansson L, Henriksson MA, Williams M, Vallgårda J, Fotsch C, Wang M. Discovery of a Potent, Orally Active 11β-Hydroxysteroid Dehydrogenase Type 1 Inhibitor for Clinical Study: Identification of (S)-2-((1S,2S,4R)-Bicyclo[2.2.1]heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5H)-one (AMG 221). J Med Chem 2010; 53:4481-7. [DOI: 10.1021/jm100242d] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dubroka A, Rössle M, Kim KW, Malik VK, Schultz L, Thiel S, Schneider CW, Mannhart J, Herranz G, Copie O, Bibes M, Barthélémy A, Bernhard C. Dynamical response and confinement of the electrons at the LaAlO3/SrTiO3 interface. PHYSICAL REVIEW LETTERS 2010; 104:156807. [PMID: 20482010 DOI: 10.1103/physrevlett.104.156807] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Indexed: 05/29/2023]
Abstract
With infrared ellipsometry and transport measurements we investigated the electrons at the interface between LaAlO3 and SrTiO3. We obtained a sheet carrier concentration of N(s) approximately = 5-9x10(13) cm(-2), an effective mass of m*=3.2+/-0.4m(e), and a strongly frequency dependent mobility. The latter are similar as in bulk SrTi(1-x)Nb(x)O3 and therefore suggestive of polaronic correlations. We also determined the vertical concentration profile which has a strongly asymmetric shape with a rapid initial decay over the first 2 nm and a pronounced tail that extends to about 11 nm.
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Jayasekera T, Kong BD, Kim KW, Buongiorno Nardelli M. Band engineering and magnetic doping of epitaxial graphene on SiC (0001). PHYSICAL REVIEW LETTERS 2010; 104:146801. [PMID: 20481952 DOI: 10.1103/physrevlett.104.146801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Indexed: 05/29/2023]
Abstract
Using calculations from first principles we show how specific interface modifications can lead to a fine-tuning of the doping and band alignment in epitaxial graphene on SiC. Upon different choices of dopants, we demonstrate that one can achieve a variation of the valence band offset between the graphene Dirac point and the valence band edge of SiC up to 1.5 eV. Finally, via appropriate magnetic doping one can induce a half-metallic behavior in the first graphene monolayer. These results clearly establish the potential for graphene utilization in innovative electronic and spintronic devices.
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Jhoo JH, Yoon IY, Kim YK, Chung S, Kim JM, Lee SB, Kim TH, Moon SH, Kim SE, Kim KW. Availability of brain serotonin transporters in patients with restless legs syndrome. Neurology 2010; 74:513-8. [PMID: 20142619 DOI: 10.1212/wnl.0b013e3181cef824] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Selective serotonin reuptake inhibitors have been associated with the risk of restless legs syndrome (RLS), suggesting that dysregulation of serotonergic neurotransmission may provoke or exacerbate RLS. METHODS We compared the availability of serotonin transporter (SERT) between 16 drug-naïve patients with RLS and 16 healthy controls. SERT was measured in the pons and medulla via [(123)I]-2beta-carbomethoxy-3beta-(4-iodophenyl) tropane (beta-CIT) SPECT. A ratio of specific to nonspecific brain uptake (V(3)'') was used for all comparisons. RLS was diagnosed according to the criteria proposed by the National Institute of Health, and its severity was measured using the International RLS Study Group (IRLSSG) Severity Scale. RESULTS The availability of SERT was similar in the RLS group and the control group with regards to the pons (1.24 +/- 0.31 vs 1.24 +/- 0.25, p > 0.1) and the medulla (0.99 +/- 0.25 vs 1.00 +/- 0.23, p > 0.1). However, IRLSSG Severity Scale scores increased with decrease of SERT availability in both the pons (beta = -0.50, t = -3.19, p = 0.009) and the medulla (beta = -0.42, t = -2.44, p = 0.03). CONCLUSIONS Although serotonin transporter (SERT) availability in pons and medulla was similar in the restless legs syndrome (RLS) group and the control group, the severity of RLS symptoms increased as the availability of SERT decreased. These data partially support the hypothesis that an increase of serotonergic neurotransmission in the brainstem may exacerbate RLS, possibly via dual modulations on striatal dopaminergic neurotransmission and on the activities of spinal motor and sensory neurons.
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Park KS, Kim YS, Kim JH, Choi BK, Kim SH, Oh SH, Ahn YR, Lee MS, Lee MK, Park JB, Kwon CH, Joh JW, Kim KW, Kim SJ. Influence of human allogenic bone marrow and cord blood-derived mesenchymal stem cell secreting trophic factors on ATP (adenosine-5'-triphosphate)/ADP (adenosine-5'-diphosphate) ratio and insulin secretory function of isolated human islets from cadaveric donor. Transplant Proc 2010; 41:3813-8. [PMID: 19917393 DOI: 10.1016/j.transproceed.2009.06.193] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 06/15/2009] [Indexed: 10/20/2022]
Abstract
Successful islet transplantation (ITx) is not only dependent on the number of islets, but also their quality, including viability, metabolic activity, and function. Islet quality decreases during cultivation after the isolation procedure. To overcome this obstacle, we established the practice of islet and mesenchymal stem cells (MSCs) coculture. This coculture condition improved the ATP (adenosine-5'-triphosphate)/ADP (adenosine-5'-diphosphate) ratio and insulin secretory function in vitro. It is believed that the enhancement of islet quality in islet-MSCs cocultures may be caused by the secretion of active agents by MSCs. Herein we have shown that interleukin-6 (IL-6), vascular endothelial growth factor-A (VEGF-A), hepatocyte growth factor (HGF), and transforming growth factor-beta (TGF-beta) were significantly increased as measured by enzyme-linked immunosorbent assay (ELISA) in MSCs-cultured medium, factors that have been shown to improve the survival, function, and angiogenesis/revascularization of islets. These results indicated that the quality of human islets was enhanced by trophic molecules secreted by MSCs, which influence the intracellular islet ATP content and insulin secretory function.
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Kam HJ, Shin YM, Cho SM, Kim SY, Kim KW, Park RW. Development of a Decision Support Model for Screening Attention-deficit Hyperactivity Disorder with Actigraph-based Measurements of Classroom Activity. Appl Clin Inform 2010; 1:377-93. [PMID: 23616848 DOI: 10.4338/aci-2010-05-ra-0033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 10/10/2010] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Questionnaire-based ADHD screening tests may not always be objective or accurate, owing to both subjectivity and prejudice. Despite attempts to develop objective measures to characterize ADHD, no widely applicable index currently exists. The principal aim of this study was to develop a decision support model for ADHD screening by monitoring children's school activities using a 3-axial actigraph. METHODS Actigraphs were placed on the non-dominant wrists of 153 children for 3 hours, while they were at school. Children who scored high on the questionnaires were clinically examined by child psychiatrists, who then confirmed ADHD. Mean, variance, and ratios of low-level (0.5-1.0G) and high-level (1.6-3.2G) activity were extracted as activity features from 142 children (10 ADHD, 132 non-ADHD). Two decision-tree models were constructed using the C5.0 algorithm: [A] from whole hours (class + playtime) and [B] during classes. Accuracy, sensitivity, and specificity were evaluated. PPV, NPV, likelihood ratio, and AUC were also calculated for evaluation. RESULTS [Model A] One child without ADHD was misclassified, resulting in an accuracy score of 99.30%. Sensitivity and NPV were 1.0000. Specificity and PPV were 0.992 and 0.803-0.909, respectively. [Model B] Two children without ADHD were misclassified, resulting in an accuracy score of 98.59%. Specificity and PPV were scored at 0.985 and 0.671-0.832, respectively. CONCLUSION The selected features were consistent with the findings of previous studies. Objective screening of latent patients with ADHD can be accomplished with a simple watch-like sensor, which is worn for just a few hours while the child attends school. The model proposed herein can be applied to a great many children without heavy cost in time and manpower cost, and would generate valuable results from a public health perspective.
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Jeong WK, Kim KW, Kim MY, Shin YM, Kim PN, Kim Y, Song GW, Ha TY, Hwang S, Lee SG. Increase of modified retrograde to antegrade flow ratio on doppler ultrasounds of the hepatic vein indicating tricuspid regurgitation during follow-up of liver transplantation: correlation with echocardiographic results. Transplant Proc 2009; 41:4238-42. [PMID: 20005376 DOI: 10.1016/j.transproceed.2009.07.110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 07/28/2009] [Indexed: 11/15/2022]
Abstract
The purpose of this study was to explore the best parameter of hepatic vein (HV) Doppler ultrasounds (DUS) that correlated with echocardiographic findings of and particularly the optimal cutoff value for tricuspid regurgitation (TR) following liver transplantation (LT). Thirty-six patients underwent echocardiography and DUS after LT from January 2006 to July 2007. Echocardiographic records were searched for TR grade and peak velocity of TR flow. The HV DUS parameters included peak velocity of retrograde flow (R), peak velocity of antegrade flow (A), the difference between R and A (R-A), the ratio of R to A (R/A ratio), and a modified R/A ratio, namely, the product of the R/A ratio and the R/A duration ratio. Correlation tests and receiver-operator characteristic analyses explored their interrelations and to obtained cutoff values to diagnose moderate and severe TR. TR grade best correlated with the modified R/A ratio (rho = 0.585), followed by the R/A ratio (rho = 0.503) and R (rho = 0.455). The modified R/A ratio was the most accurate parameter for the diagnosis of moderate and severe TR (Az = 0.825 and 0.895, respectively); its cutoff value was > or =0.11 for moderate TR (sensitivity and specificity both 77.78%) and 0.13 for severe TR (sensitivity, 100%; specificity, 81.2%). The modified R/A ratio best correlated with echocardiographic results of TR, although the strength of correlation was only moderate. Additionally, the modified R/A ratio was an accurate DUS parameter to diagnose moderate and severe TR among patients following LT.
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Kim YK, Yoon IY, Kim JM, Jeong SH, Kim KW, Shin YK, Kim BS, Kim SE. The implication of nigrostriatal dopaminergic degeneration in the pathogenesis of REM sleep behavior disorder. Eur J Neurol 2009; 17:487-92. [PMID: 19968708 DOI: 10.1111/j.1468-1331.2009.02854.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE The pathogenesis of rapid eye movement (REM) sleep behavior disorder (RBD) is not clear despite its frequent association with Parkinson's disease (PD). We investigated whether the nigrostriatal dopaminergic system is involved in the development of idiopathic RBD. METHODS Fourteen patients with RBD, 14 patients with PD and 12 normal controls were included in the study. The diagnosis of RBD was confirmed on polysomnography. All the participants performed single-photon emission computed tomography imaging 3 h after injection of [(123)I]FP-CIT. During REM sleep of the RBD patients, each 30-s epoch was rated as 'tonic' when there was at least 50% of tonically maintained chin electromyography (EMG) activity in the epoch. Phasic EMG activities were calculated as the percentage of 3-s mini-epoch containing phasic EMG events (leg and chin, separately). RESULTS The RBD patients showed a trend of lower binding in the striatum than the normal controls (P = 0.07), and the significance was revealed in the putamen (P = 0.02). However, in 11 individual cases of the 14 RBD patients, the dopamine transporter (DAT) densities in the putamen still remained within the normal range. In the RBD patients, there was no correlation between EMG activities and DAT densities. CONCLUSIONS Nigrostriatal dopaminergic degeneration could be a part of the pathogenesis of RBD, but not essential for the development of RBD. The lack of correlation between RBD severity and DAT densities suggests that another pathogenic process not related to nigrostriatal dopaminergic transmission may be implicated in RBD.
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Cho JY, Moon MH, Lee YH, Kim KW, Kim SH. Measurement of compensatory hyperplasia of the contralateral kidney: usefulness for differential diagnosis of fetal unilateral empty renal fossa. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2009; 34:515-520. [PMID: 19852048 DOI: 10.1002/uog.7336] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
OBJECTIVE To assess the usefulness of sonographic evaluation of compensatory hyperplasia of the contralateral kidney for the differential diagnosis of fetal unilateral empty renal fossa (ERF). METHODS We retrospectively measured the ratio of the anteroposterior (AP) and transverse (TR) diameters of the contralateral kidney in 24 fetuses with unilateral ERF including 12 cases of unilateral renal agenesis, six cases of a unilateral pelvic kidney and six cases of a unilateral ectopic multicystic dysplastic kidney (MCDK). For the normal reference value, we calculated the AP : TR diameter ratios of both kidneys in 20 normal fetuses in the second and third trimesters. We calculated the accuracy of the AP : TR ratio to detect contralateral compensatory hyperplasia. RESULTS The median (range) AP : TR diameter ratios of the normal kidneys were 0.84 (0.72-0.89) in the second trimester and 0.81 (0.65-0.89) in the third trimester. All cases of unilateral renal agenesis and ectopic MCDK showed the presence of compensatory hyperplasia, while no case of renal ectopy was seen with compensatory hyperplasia. The median (range) ratios for unilateral renal agenesis and ectopic MCDK were 1.0 (0.95-1.02) and 1.1 (1-1.25) in the second and third trimesters, respectively. The median ratios for a unilateral pelvic kidney were 0.8 (0.74-0.85) and 0.77 (0.74-0.84) in the second and third trimesters, respectively. Using 0.9 as the discriminating value, the sensitivity, specificity, and accuracy of the AP : TR diameter ratio for the prenatal diagnosis of compensatory renal hyperplasia was 100%. CONCLUSION Sonographic evaluation of compensatory hyperplasia of the contralateral kidney may be useful for the differential diagnosis of a fetal unilateral ERF. Prospective studies are warranted.
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Jee HM, Kim KW, Hong JY, Sohn MH, Kim KE. Increased serum B cell-activating factor level in children with atopic dermatitis. Clin Exp Dermatol 2009; 35:593-8. [PMID: 19874366 DOI: 10.1111/j.1365-2230.2009.03635.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND B cell-activating factor (BAFF) is a tumour necrosis factor superfamily member best known for its role in the survival and maturation of B cells. BAFF activity is seen in naïve and effector/memory T cells. AIM To investigate the level and role of BAFF in serum of patients with atopic dermatitis (AD). METHODS Levels of serum BAFF, a proliferation-inducing ligand (APRIL) and total serum IgE level, and total eosinophil count were measured in 245 children. RESULTS Patients were characterized as having atopic eczema (AE) (n = 90) or non-AE (n = 77); the remainder were healthy control subjects (n = 78). Serum BAFF level in children with AE (1625.04 +/- 708.32 pg/mL) was significantly higher than in non-AE children (1194.69 +/- 448.44 pg/mL, P < 0.0001) or healthy controls (1062.89 +/- 444.74 pg/mL, P < 0.0001). Serum APRIL level was not different between the three groups. Serum BAFF level significantly correlated with total serum IgE level (gamma = 0.42, P < 0.0001) and total eosinophil count. It was also positively correlated with serum BAFF and egg-specific IgE level (gamma = 0.252, P = 0.045) in AE. CONCLUSIONS Serum BAFF level is high in AE and might be a useful marker for AE.
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Beher D, Wu J, Cumine S, Kim KW, Lu SC, Atangan L, Wang M. Resveratrol is not a direct activator of SIRT1 enzyme activity. Chem Biol Drug Des 2009; 74:619-24. [PMID: 19843076 DOI: 10.1111/j.1747-0285.2009.00901.x] [Citation(s) in RCA: 330] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Resveratrol is a plant polyphenol capable of exerting beneficial metabolic effects which are thought to be mediated in large by the activation of the NAD(+)-dependent protein deacetylase SIRT1. Although resveratrol has been claimed to be a bona fide SIRT1 activator using a peptide substrate (Fluor de Lys-SIRT1 peptide substrate), recent reports indicate that this finding might be an experimental artifact and need to be clarified. Here, we show that: (i) the Fluor de Lys-SIRT1 peptide is an artificial SIRT1 substrate because in the absence of the covalently linked fluorophore the peptide itself is not a substrate of the enzyme, (ii) resveratrol does not activate SIRT1 in vitro in the presence of either a p53-derived peptide substrate or acetylated PGC-1alpha isolated from cells, and (iii) although SIRT1 deacetylates PGC-1alpha in both in vitro and cell-based assays, resveratrol did not activate SIRT1 under these conditions. Based on these observations, we conclude that the pharmacological effects of resveratrol in various models are unlikely to be mediated by a direct enhancement of the catalytic activity of the SIRT1 enzyme. In consequence, our data challenge the overall utility of resveratrol as a pharmacological tool to directly activate SIRT1.
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