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Roh YH, Kim YH, Choi HJ, Lee KE, Roh MS. Syndecan-1 expression in gallbladder cancer and its prognostic significance. ACTA ACUST UNITED AC 2008; 41:245-50. [PMID: 18544939 DOI: 10.1159/000137667] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 01/11/2008] [Indexed: 11/19/2022]
Abstract
AIM To determine whether the immunohistochemical detection of syndecan-1 could provide useful information as a novel therapeutic or prognostic factor in primary gallbladder (GB) cancer. MATERIALS AND METHODS Forty-three GB cancer tissues were evaluated by immunohistochemistry for syndecan-1 expression. The relationship between syndecan-1 expression and clinicopathological characteristics, and the univariate survival analysis for the influence of the syndecan-1 expression on the overall survival were analysed. RESULTS Epithelial syndecan-1 immunoreactivity was observed in 25 (58.1%) of the 43 GB cancer cases. The tumors with a positive syndecan-1 expression more frequently showed lymph node metastasis (p = 0.037). Although there was no statistically significant association, the tumors with a positive syndecan-1 expression tended to show a deeper invasion depth (p = 0.087) and more frequent lymphovascular invasion (p = 0.064). The Kaplan-Meier survival curves demonstrated that patients with positive syndecan-1 expression had a significantly shorter survival time than those patients with negative syndecan-1 expression (p = 0.05). CONCLUSIONS A subset of GB cancers revealed an epithelial overexpression of syndecan-1, which was associated with a progressive pathological feature and an aggressive clinical course. Therefore, epithelial syndecan-1 expression may be a predictor for a poor prognosis in patients with GB cancer.
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Park BJ, Sung JH, Park JH, Choi JS, Choi HJ. Poly(vinyl acetate)/clay nanocomposite materials for organic thin film transistor application. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2008; 8:2676-2679. [PMID: 18572706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nanocomposite materials of poly(vinyl acetate) (PVAc) and organoclay were fabricated, in order to be utilized as dielectric materials of the organic thin film transistor (OTFT). Spin coating condition of the nanocomposite solution was examined considering shear viscosity of the composite materials dissolved in chloroform. Intercalated structure of the PVAc/clay nanocomposites was characterized using both wide-angle X-ray diffraction and TEM. Fracture morphology of the composite film on silicon wafer was also observed by SEM. Dielectric constant (4.15) of the nanocomposite materials shows that the PVAc/clay nanocomposites are applicable for the gate dielectric materials.
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Kang YH, Kim BR, Choi HJ, Seo JG, Kim BH, Han MS. Enhancement of algicidal activity by immobilization of algicidal bacteria antagonistic to Stephanodiscus hantzschii (Bacillariophyceae). J Appl Microbiol 2008; 103:1983-94. [PMID: 17953609 DOI: 10.1111/j.1365-2672.2007.03439.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS Enhancement of algicidal activity by immobilization of algicidal bacteria antagonistic to Stephanodiscus hantzschii. METHODS AND RESULTS In laboratory studies, A diatom-lysing bacterium, Pseudomonas fluorescens HYK0210-SK09 showed strong algicidal activity against S. hantzschii, but a natural mesocosm study revealed that this bacterium failed to fully control natural blooms of Stephanodiscus at the low water temperatures that favour these blooms. Here, we sought to develop an effective immobilization strategy for enhancing the algicidal activity of HYK0210-SK09 in the natural setting. Bacterium HYK0210-SK09 was immobilized with various carriers including agar, alginate, polyurethane and cellulose sponge. The bacterial cells immobilized with cellulose sponge (CIS) induced more rapid and complete lysis of S. hantzschii than other carriers, and had a higher packing ability than polyurethane. Furthermore, CIS-immobilized cells showed higher lysis of S. hantzschii at the same concentrations as that of free cells (< or =1 x 10(7) cells ml(-1)), and had especially strong algicidal activity at the low temperatures (<10 degrees C). Based on these laboratory studies, we assessed the possible application of HYK0210-SK09 cells in the field by performing a mesocosm study during the winter season. The CIS-immobilized cells with species-specific activity towards the genera Stephanodiscus showed extremely high algicidal activity (up to 95%) against a bloom of Stephanodiscus hantzschii even at low water temperatures, because of high cell packing and subsequent cell protection against low temperatures and predators, whereas free cells showed negligible algicidal activities under these conditions. CONCLUSION Immobilizing cells of HYK0210-SK09 in CIS foam, rather than in the other matrices tested, could achieve more efficient control of Stephanodiscus blooms and showed a significant algicidal activity on in vitro and in vivo blooms, even at low water temperature. SIGNIFICANCE AND IMPACT OF THE STUDY Collectively, these results indicate that CIS of algicidal bacteria may form an important strategy for effective management of Stephanodiscus blooms at low water temperatures.
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Choi HJ, Song BJ, Gong YD, Gwak WJ, Soh Y. Rapid degradation of hypoxia-inducible factor-1alpha by KRH102053, a new activator of prolyl hydroxylase 2. Br J Pharmacol 2008; 154:114-25. [PMID: 18332861 DOI: 10.1038/bjp.2008.70] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Hypoxia-inducible factor (HIF) is a transcription factor induced by hypoxia and degraded by ubiquitin-dependent proteasomes in normoxic conditions. Under hypoxic conditions, hydroxylation of HIF-1alpha subunit by prolyl hydroxylase (PHD) is suppressed, thus leading to increased levels of HIF. Although PHD2 plays a key role in regulating the levels of HIF, chemical activators of PHD2 are relatively unknown. The aim of this study was to identify small molecule activators of PHD2 that could be used, eventually, to suppress the level of HIF-1alpha. EXPERIMENTAL APPROACH By using the overproduced PHD2 as a target, a molecular library consisting of more than 600 small molecules with a benzopyran structure was screened with an HPLC assay method. KEY RESULTS We found a potent activator of PHD2, KRH102053 (2-amino-4-methylsulphanyl-butylic acid-4-methoxy-6-(4-methoxy-benzylamino)-2,2-dimethyl-chroman-3-yl ester). The effects of KRH102053 on controlling HIF were studied in human HOS osteosarcoma, rat PC12 phaeochromocytoma and human HepG2 hepatoma cells. Under our experimental conditions, KRH102053 decreased the protein level of HIF-1alpha and the mRNA levels of HIF-regulated downstream target genes, such as vascular endothelial growth factor, aldolase A, enolase 1 and monocarboxylate transporter 4. Consistent with these results, KRH102053 also inhibited the rates of HIF-related migration and invasion of HOS cells as well as the degree of tube formation in human umbilical vein endothelium cells. CONCLUSIONS AND IMPLICATIONS These results suggest that KRH102053 and its structural analogues have the potential for use as therapeutic agents against various diseases associated with HIF.
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Strang AJ, Choi HJ, Berg WP. The effect of exhausting aerobic exercise on the timing of anticipatory postural adjustments. J Sports Med Phys Fitness 2008; 48:9-16. [PMID: 18212704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
AIM The aim of the study was to investigate the influence of exhausting aerobic exercise on the timing of anticipatory postural adjustments (APAs). METHODS The APAs of 12 participants were recorded at baseline, after a .VO2max running test, and again following a 45-min rest period. APAs were induced using a rapid bilateral arm-raising maneuver, and were analyzed in the rectus abdominis, hamstring group, gluteal group, and lumbar and thoracic paraspinal muscles using electromyography. Postural stability was assessed by monitoring anterior/posterior displacement of the center of pressure using a force plate. We hypothesized that APA onset would be ear lier following exhausting aerobic exercise as compared to the baseline measures, but that this effect would be transient (i.e., APA onset following the rest period would not differ from that at baseline). RESULTS Exhausting aerobic exercise resulted in a significantly earlier APA in one of the 5 muscles evaluated, the thoracic paraspinal group, and this effect persisted 45-min postexercise. Exhausting aerobic exercise did not affect postural stability during the rapid arm-raising maneuver. CONCLUSION The findings lend tentative support for the notion that earlier APAs constitute a functional adaptation by the motor system to maintain postural stability in the presence of fatigue.
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Leem CS, Kim BJ, Kim C, Park SR, Ohta T, Bostwick A, Rotenberg E, Kim HD, Kim MK, Choi HJ, Kim C. Effect of linear density of states on the quasiparticle dynamics and small electron-phonon coupling in graphite. PHYSICAL REVIEW LETTERS 2008; 100:016802. [PMID: 18232802 DOI: 10.1103/physrevlett.100.016802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Indexed: 05/25/2023]
Abstract
We obtained the spectral function of very high quality natural graphite single crystals using angle-resolved photoelectron spectroscopy. A clear separation of nonbonding and bonding bands and asymmetric lineshape are observed. The asymmetric line shapes are well accounted for by the finite photoelectron escape depth and the band structure. The extracted width of the spectral function (inverse of the photohole life time) near the K point is, beyond the maximum phonon energy, approximately proportional to the energy as expected from the linear density of states near the Fermi energy. The upper bound for the electron-phonon coupling constant is about 0.2, a much smaller value than the previously reported one.
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Kim HA, Kim S, Seo YI, Choi HJ, Seong SC, Song YW, Hunter D, Zhang Y. The epidemiology of total knee replacement in South Korea: national registry data. Rheumatology (Oxford) 2008; 47:88-91. [PMID: 18077497 DOI: 10.1093/rheumatology/kem308] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVE Knee osteoarthritis (OA) is prevalent among the elderly in Asian countries; however, the utilization of total knee replacement (TKR) is unknown. Using data from a national registry, we sought to estimate the incidence of TKR by age and sex, and the trend for TKR utilization from 2002 to 2005 in South Korea. METHODS Reimbursement records from all hospitals in South Korea were extracted from the Health Insurance Review Agency (HIRA) database. Records with both the procedure code corresponding to a TKR and the diagnosis code of knee OA were selected. We estimated the age- and sex-specific rates of TKR. To compare the rate of TKR between men and women, we calculated age-standardized risk ratios. A TKR registry from a single centre containing more clinical information was analysed, and the differences in the clinical features between men and women were compared. RESULTS From 2002 to 2005, 47 961 TKRs were performed in subjects over the age of 40 yrs due to OA. The rate of TKR has increased over the 4 yrs and was much higher in women than in men. Compared with men, the age-standardized rate ratios for TKR in women ranged from 7.4 to 8.0. The single-centre registry data revealed that there was no difference in age, disease duration and the Kellgren-Lawrence grade at the time of surgery between men and women. CONCLUSION Using a national database, we found that the rate of TKR increased steadily from 2002 to 2005 in South Korea. The TKR rate in women was much higher than that in men. Risk factors that account for such disparity in TKR utilization need to be further investigated.
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Jung DC, Choi HJ, Ju W, Kim SC, Choi KG. Discordant MRI/FDG-PET imaging for the diagnosis of borderline ovarian tumors. Int J Gynecol Cancer 2007; 18:637-41. [PMID: 17944914 DOI: 10.1111/j.1525-1438.2007.01116.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The objective of this study was to assess the role of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) for the characterization of ovarian masses that were diagnosed as ovarian malignancies by magnetic resonance imaging (MRI). We performed a retrospective review of eight patients with pathologically confirmed borderline ovarian tumors (BOT) who underwent MRI and FDG-PET before surgical staging from August 2005 to March 2007. We assessed the PET imaging of the BOT, measured the FDG uptake and quantified the findings as a standardized uptake value (SUV). The FDG-PET scans, of all eight patients, showed uptake of FDG with a mean SUV of less than 2.0 in the solid portion of the masses evaluated. We conclude that the MRI-PET differences may help differentiate borderline from malignant ovarian tumors.
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Song JK, Choi HJ, Chin I. Preparation and properties of electrophoretic microcapsules for electronic paper. J Microencapsul 2007; 24:11-9. [PMID: 17438939 DOI: 10.1080/02652040601058384] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This paper shows two types of microcapsules used for electrophoretic display. One is prepared by in-situ polymerization which is based on urea, melamine and formaldehyde and another by complex coacervation, which is composed of gelatin and gum Arabic. Microcapsules attract interests of many research groups for longer lifetime of electrophoretic display by reducing agglomerization or lateral movements of nanoparticles. The gelatin microcapsules were more attractive in providing more uniform microcapsule coverage on electrodes due to their flexibility as compared to the melamine-urea microcapsules. The properties of microcapsules were characterized by FTIR, OM, SEM and TGA. Migration of nanoparticles in the two types of microcapsules was also observed when an electric field was applied.
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Choi HJ, Kim YJ, Yim JH, Kim MY, Kim HO, Park YM. Unusual presentation of solitary cutaneous myxoma. J Eur Acad Dermatol Venereol 2007; 21:403-4. [PMID: 17309474 DOI: 10.1111/j.1468-3083.2006.01881.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Chung DR, Lee SS, Lee HR, Kim HB, Choi HJ, Eom JS, Kim JS, Choi YH, Lee JS, Chung MH, Kim YS, Lee H, Lee MS, Park CK. Emerging invasive liver abscess caused by K1 serotype Klebsiella pneumoniae in Korea. J Infect 2006; 54:578-83. [PMID: 17175028 DOI: 10.1016/j.jinf.2006.11.008] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2006] [Revised: 11/07/2006] [Accepted: 11/07/2006] [Indexed: 12/20/2022]
Abstract
OBJECTIVES The high incidence of invasive liver abscess caused by Klebsiella pneumoniae in Taiwan, contrasted with the rareness of this disease in Western countries, has aroused special interest. There have been few detailed reports from other Asian countries. To investigate a current epidemiology of K. pneumoniae liver abscess in Korea and to determine K serotype distribution in K. pneumoniae strains causing liver abscess, we performed a nationwide prospective study. METHODS Community-acquired, culture-proven liver abscess cases were enrolled between 2004 and 2005. Etiologies and clinical features were analyzed. K. pneumoniae isolates were serotyped according to K antigen. Meta-analysis was done to determine the time trend of the etiologies of liver abscess in Korea. RESULTS Out of 371 cases collected prospectively, 290 (78.2%) were caused by K. pneumoniae. Most K. pneumoniae liver abscesses were monomicrobial. Diabetes mellitus was the most common underlying disease (39.9%). Distant metastatic infections were frequently observed (8.7%). magA PCR revealed that 95 (59.4%) out of 160 K. pneumoniae isolates belonged to the K1 serotype. CONCLUSIONS Our study indicates that K. pneumoniae has emerged as a major etiologic agent of liver abscess in Korea, and these emerging infections seem to be attributable to invasive K. pneumoniae strains with capsular K1 serotype.
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Han SY, Chang EJ, Choi HJ, Kwak CS, Suh SI, Bae JH, Park SB, Kim HC, Mun KC. Effect of tacrolimus on the production of oxygen free radicals in hepatic mitochondria. Transplant Proc 2006; 38:2242-3. [PMID: 16980054 DOI: 10.1016/j.transproceed.2006.06.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Cyclosporine (CsA) causes side effects that occur mainly in the kidney but also in the liver. Several reports have strongly suggested that the production of oxygen free radicals (OFRs) is a common mechanism of CsA toxicity. However, tacrolimus is believed to suppress the production of OFRs. METHODS We obtained the mitochondrial fraction with 96% purity from rat liver using a sucrose density gradient solution. Zero to 100 micromol/L tacrolimus was incubated with the mitochondrial fraction for 6 hours at 37 degrees C. OFRs were evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2,7-dichlorefluorescein using a VICTOR3 multilabel counter. RESULTS The fluorescence units for OFR production were increased as the time of exposure to tacrolimus passed from 1 to 6 hours. The fluorescence units in 0.1 micromol/L tacrolimus were 6.0 x 10(5) at 1 hour, 7.8 x 10(5) at 2 hours, 9.0 x 10(5) at 3 hours, 10.0 x 10(5) at 4 hours, 11.1 x 10(5) at 5 hours, and 11.4 x 10(5) at 6 hours. However, the fluorescence units were similar although the tacrolimus concentration increases from 0.1 to 100 micromol/L. CONCLUSIONS The results in this experiment suggested that tacrolimus induced the production of OFRs depending on the exposure time.
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Han SY, Chang EJ, Choi HJ, Kwak CS, Park SB, Kim HC, Mun KC. Apoptosis by cyclosporine in mesangial cells. Transplant Proc 2006; 38:2244-6. [PMID: 16980055 DOI: 10.1016/j.transproceed.2006.06.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
INTRODUCTION The immunosuppressive agent cyclosporine (CsA) is widely used to treat allograft rejection and various autoimmune disorders. A major limiting factor in the use of CsA is chronic nephrotoxicity. The pathogenesis of CsA-induced nephrotoxicity is not fully understood. Several recent studies have suggested that CsA treatment directly induces apoptosis in several cell types. The present study was undertaken to investigate the effects of CsA on apoptosis of cultured rat mesangial cells (RMCs). METHODS RMCs were treated with CsA at concentrations of 0.1 to 40 mumol/L. Cell viability was determined by MTT assay. Apoptotic protein expression was determined by Western blot analysis. RESULTS Cell viability was decreased with increasing concentrations of CsA in dose-dependent manner. CsA produced dose-dependent induction of p53, caspase-6, and Bax protein expression. CsA treatment caused proteolytic cleavage of caspase-3 and induced the degradation of 116-kDa PARP into 89-kDa fragment. RMCs with CsA reduced Bcl-2 and cIAP expression. CONCLUSIONS In this study, CsA induced apoptosis by up-regulating proapoptotic factors, caspase-3 and -6, p53, Bax, cleaving PARP, and down-regulating antiapoptotic factor, Bcl-2, and cIAP. These results suggested that the increased cell apoptosis exerted by CsA may be one of the mechanisms promoting CsA-induced nephrotoxicity.
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Han SY, Chang EJ, Choi HJ, Nam SI, Lee NH, Kwak CS, Park SB, Kim HC, Mun KC. Total antioxidant status and oxygen free radicals during hepatic regeneration. Transplant Proc 2006; 38:2214-5. [PMID: 16980046 DOI: 10.1016/j.transproceed.2006.07.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The damage induced by oxygen free radicals (OFRs) is caused by an imbalance of the production of versus the antioxidant defenses against OFRs. METHODS To understand hepatic damage induced by oxygen free radicals after hepatectomy in rats, total antioxidant status and total production of oxygen free radicals were serially measured in regeneration liver. At 1, 2, 3, 7, and 10 days after hepatectomy of Sprague-Dawley rats, blood was obtained into a capillary tube from a tail vein. Total antioxidant status and total production of oxygen free radicals were measured using the Randox kit, a colorimetric method, and the Free Radical Analytical System. We also measured the amount of malonyldialdehyde, which provides an indirect index of oxidative injury. RESULTS The level of malonyldialdehyde after hepatectomy was higher compared with that before hepatectomy. The level of total oxygen free radicals after hepatectomy was higher compared with that before hepatectomy. Total antioxidant status after hepatectomy was lower compared with that before hepatectomy. CONCLUSIONS The results suggested that the damage by OFRs to the regenerating liver was caused by increased production of OFRs and decreased antioxidant defense against OFRs.
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Han SY, Mun KC, Choi HJ, Kwak CS, Bae JH, Suh SI, Park SB, Kim HC, Chang EJ. Effects of cyclosporine and tacrolimus on the oxidative stress in cultured mesangial cells. Transplant Proc 2006; 38:2240-1. [PMID: 16980053 DOI: 10.1016/j.transproceed.2006.06.078] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Cyclosporine (CsA) and tacrolimus (Tac) are two primary immunosuppressive agents used for the prevention of graft rejection. However, their use is associated with significant side effects, most notably nephrotoxicity. The mechanisms of this toxicity are not fully understood, but they seem to be associated with increases in the production of oxygen free radicals (OFRs). This present work examined the effect of CsA and Tac on the production of OFRs in cultured rat renal mesangial cells (RMCs). METHODS Varying concentrations of CsA and Tac (0 to 40 micromol/L) were added to RMCs and incubated for 60 minutes at 37 degrees C. The production of OFRs was evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2', 7'-dichlorofluorescin. RESULTS At 60 minutes, the relative fluorescence units (RFU) for OFRs production in RMCs exposure to CsA were increased by 2.5%, 11.5%, 22.5%, 57.2%, and 174% at 2.5, 5, 10, 20, and 40 micromol/L, respectively. Tac increased the RFU by 15.9%, 13.6%, 14.8%, 13.2%, 21.4%, 13.2%, and 28.1% at 0.1, 1, 2.5, 5, 10, 20, and 40 micromol/L, respectively. In RMCs, the RFU produced by CsA was higher than that by Tac. CONCLUSIONS The results of this experiment suggest that CsA and Tac induced renal injury by OFRs.
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Lee KH, Park BJ, Choi HJ. Comment on "An enhanced polarization mechanism for the metal cations modified amorphous TiO2 based electrorheological materials" by Qing Wu, Bin Yuan Zhao, Chen Fang and Ke Ao Hu. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 21:387-9. [PMID: 17245543 DOI: 10.1140/epje/i2006-10071-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Accepted: 01/02/2007] [Indexed: 05/13/2023]
Abstract
Comments on a recent article on an enhanced polarization mechanism for the metal cations modified amorphous TiO2 based electrorheological materials are presented, based upon an examination of the yield stress, which is a function of electric-field strength, of the materials. Using the deduced critical electric-field strengths, we find that the universal yield stress equation proposed collapses the data given by Qing Wu, Bin Yuan Zhao, Chen Fang, Ke Ao Hu, Eur. Phys. J. E 17, 63 (2005), onto a single curve.
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Cho NH, Kang S, Hong S, Jeong GB, Choi IW, Choi HJ, Choi HK. Multinucleation of koilocytes is actually multilobation. Int J Gynecol Cancer 2006; 16:686-9. [PMID: 16681748 DOI: 10.1111/j.1525-1438.2006.00371.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
In order to clarify the complete cytomorphology of cytopathic changes as a consequence of human papillomavirus (HPV) infection, we performed three-dimensional (3D) reconstruction from confocal fluorescent images. After confirming 22 HPV types using a DNA chip, we performed 3D confocal image restoration in human uterine cervical swab samples and corresponding tumor tissues. On restoration of 3D confocal images, the multinucleated feature of koilocytes was revealed to be multilobation of a single nucleus, as opposed to true multinucleation.
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Oh YL, Han SY, Mun KH, Choi HJ, Kim HY, Hwang EA, Park SB, Kim HC, Chang EJ. Cyclosporine-Induced Apoptosis in Osteosarcoma Cells. Transplant Proc 2006; 38:2237-9. [PMID: 16980052 DOI: 10.1016/j.transproceed.2006.06.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Posttransplant bone disease is one of the complications of cyclosporine (CsA), which is widely used as an immunosuppressive agent in the field of kidney transplantation. Cyclosporine treatment causes osteopenia as a result of altered bone turnover, but the pathogenic mechanisms of this process remain unclear. This study examined the ability of CsA to induce apoptosis in a rat osteoblast cell line. RESULTS We induced apoptosis in rat osteoblastic ROS 17/2.8 cells by exposure to CsA. MTT assay showed that CsA exhibited significant cytotoxic effects on ROS 17/2.8 cells in a dose-dependent manner. Western blot analysis showed enhanced processing of caspase-8, Bax, and p53 after CsA treatment. Expression of cleaved poly (ADP-ribose) polymerase (PARP) was elevated by CsA treatment. Pro-caspase-3 and Bcl-2 proteins were decreased by CsA. CONCLUSIONS These results suggested that CsA induced apoptosis of osteoblasts.
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Min YS, Yim SH, Bai KL, Choi HJ, Jeong JH, Song HJ, Park SY, Ham I, Whang WK, Sohn UD. The effects of apigenin-7-O-beta-D-glucuronopyranoside on reflux oesophagitis and gastritis in rats. ACTA ACUST UNITED AC 2006; 25:85-91. [PMID: 15955027 DOI: 10.1111/j.1474-8673.2005.00332.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
1. This study evaluated the inhibitory action of apigenin-7-O-beta-D-glucuronopyranoside (AGC), apigenin, and omeprazole on reflux oesophagitis and gastritis in rats. AGC was isolated from Clerodendron trichotomum leaves. 2. Oesophagitis and gastritis were induced by surgical procedure and the administration of indomethacin, respectively. The intraduodenal (i.d.) administration of AGC decreased the volume of gastric juice and increased the gastric pH compared with apigenin and omeprazole. The acid output was more inhibited by AGC in a dose-dependent manner than by apigenin and omeprazole. Compared with apigenin and omeprazole, AGC significantly decreased the size of gastric lesions, which were induced by exposure of the gastric mucosa to indomethacin. 3. Malondialdehyde (MDA) content, which is the end product of lipid peroxidation, was increased significantly after the induction of reflux oesophagitis. The MDA content was decreased by AGC (i.d. 3 mg kg(-1)), but not by either apigenin or omeprazole. This suggests that AGC has an antioxidative effect. In the oesophagitis group, the mucosal levels of glutathione (GSH) were significantly lower than that in the normal group. However, the GSH levels were preserved after administering the AGC, suggesting that AGC possesses scavenging activity. 4. In summary, AGC is more potent than apigenin and omeprazole at inhibiting reflux oesophagitis and gastritis and may therefore be a promising drug for their treatment.
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Kim TH, Lee SY, Cho NK, Seong HK, Choi HJ, Jung SW, Lee SK. Dielectrophoretic alignment of gallium nitride nanowires (GaN NWs) for use in device applications. NANOTECHNOLOGY 2006; 17:3394-9. [PMID: 19661581 DOI: 10.1088/0957-4484/17/14/009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We report on a simple and effective ac and dc dielectrophoresis (DEP) method that can be used to align and manipulate semiconductor gallium nitride (GaN) nanowires (NWs) with variations in the type of electrical fields as well as variations of frequency. We observed that the ability of the alignment and the formation of the assembling nanowires (single or a bundle configuration) strongly depend on the magnitude of both the ac and dc electric fields. The yield results indicate that the GaN NWs, using ac DEP, are better aligned with a higher yield rate of approximately 80% over the entire array in the chip than by using dc DEP. In addition, we first demonstrated the simple hybrid p-n junction structures assembled by n-type GaN nanowires together with a p-type silicon substrate (n-GaN NW/p-Si substrate) using dielectrophoresis. From the transport measurements, the p-n junction structures show well-defined current rectifying behaviour with a low reverse leakage current of approximately 3 x 10(-4) A at -25 V. We believe that our unique p-n junction structures can be useful for electronic and optoelectronic nanodevices such as rectifiers and UV nano-LEDs.
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Choi HJ, Ku JK, Kim MY, Kang H, Cho SH, Kim HO, Park YM. Possible role of Fas/Fas ligand-mediated apoptosis in the pathogenesis of fixed drug eruption. Br J Dermatol 2006; 154:419-25. [PMID: 16445769 DOI: 10.1111/j.1365-2133.2005.07057.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Although epidermal and dermal T cells play roles in the pathogenesis of fixed drug eruption (FDE), not much is known about keratinocyte death and its precise mechanism in FDE. OBJECTIVES Our aim is to elucidate the mechanism that underlies keratinocyte death in FDE, that is, the role of apoptosis and its signalling pathway. METHODS We first examined the involvement of apoptosis in the active FDE lesions by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL) assay and immunohistochemical analysis of caspase-3. We then examined the expressions of Fas and Fas ligand (FasL) to deduce the possible upstream signalling pathway of apoptosis, if apoptosis were involved. We finally characterized the infiltrated T-cell subpopulations in the active FDE lesions. RESULTS In the active FDE lesions, TUNEL positivity was strongly observed in the basal keratinocytes, and also weakly observed in the upper dermal infiltrates as well as in a few keratinocytes in the granular layer. The distribution of TUNEL-positive cells was similar to that of the strong staining of active capase-3. Fas was found mainly in the keratinocytes and some infiltrated dermal cells, whereas FasL was identified predominantly in the intraepidermal and dermal infiltrated cells and in some basal keratinocytes. Overlapping expression of Fas and FasL was accompanied by apoptosis in the FDE lesions. Many of the infiltrated mononuclear cells were CD8+. Perforin was rarely observed in the FDE lesions. CONCLUSIONS These findings suggest that apoptosis of the keratinocyte is highly likely to be involved in the pathogenesis of FDE, and this cytotoxicity might be predominantly mediated by the FasL of the infiltrating CD8+ T cells, possibly also playing an inflammatory role.
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Kim TS, Chung YB, Choi HJ, Yang HJ. Changes of serum cytokine profiles in Korean vivax malarial patients after chemotherapy. Parasitol Res 2006; 100:183-5. [PMID: 16832700 DOI: 10.1007/s00436-006-0263-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Accepted: 06/13/2006] [Indexed: 10/24/2022]
Abstract
Changes of serum cytokines including interferon gamma inducible protein-10 (IP-10) chemokine were analyzed in a total of eight vivax malarial patients before and after chemotherapy by immunostaining for human cytokine antibodies attached to membranes. IP-10 was strongly reactive in the period before chloroquine/primaquine combined chemotherapy and disappeared after chemotherapy in all patients. Therefore, IP-10 chemokine may be of importance in the pathogenesis of vivax malaria and a good marker of a complete cure.
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Lee JY, Choi HJ, Park IN, Hong SB, Oh YM, Lim CM, Lee SD, Koh Y, Kim WS, Kim DS, Kim WD, Shim TS. Comparison of two commercial interferon- assays for diagnosing Mycobacterium tuberculosis infection. Eur Respir J 2006; 28:24-30. [PMID: 16611658 DOI: 10.1183/09031936.06.00016906] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The clinical usefulness of ex vivo interferon-gamma assays may largely depend on the assay format and epidemiological status of tuberculosis (TB) in the region studied. From July 2004 to June 2005 a prospective comparison study was undertaken at a tertiary referral hospital in South Korea. The results of tuberculin skin tests (TST) and the commercially available QuantiFERON-TB Gold (QFT-G) and T SPOT-TB (SPOT) assays were compared in an intermediate TB-burden country. Of the 224 participants studied, results from all three tests (TST, QFT-G, and SPOT) were available in 218; 87 with active TB and 131 at a low risk for TB. Using 10 mm as a cut-off for TST, SPOT sensitivity (96.6%) was significantly higher than that seen for TST (66.7%) and QFT-G (70.1%). QFT-G showed superior specificity over TST (91.6 versus 78.6%). Although the specificity of QFT-G was higher than that of SPOT (91.6 versus 84.7%), the difference was not statistically significant. Whilst some differences were found in the performance of the two commercialised interferon-gamma assays, they seemed to be superior in their detection of Mycobacterium tuberculosis infection compared with tuberculin skin tests. The most appropriate choice of interferon-gamma assay to use may depend on the clinical setting.
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Choi HJ, Lee IS, Sung JH, Park BJ, Jhon MS. Comment on “Preparation and electrorheological property of rare earth modified amorphous BaxSr1−xTiO3 gel electrorheological fluid”. J Colloid Interface Sci 2006; 295:291-3. [PMID: 16165145 DOI: 10.1016/j.jcis.2005.08.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2005] [Revised: 08/04/2005] [Accepted: 08/06/2005] [Indexed: 11/15/2022]
Abstract
The comments on the recent results on electrorheological (ER) property of rare earth modified amorphous barium strontium titanate gel based ER fluid are given via analysis of its dynamic yield stress data as a function of applied electric field strengths. Using our previously reported universal yield stress equation, we obtained the critical electric field strength and collapsed their data onto a single curve.
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Cho NH, Kang S, Hong S, Jeong GB, Choi IW, Choi HJ, Choi HK. Multinucleation of koilocytes is in fact multilobation and is related to aberration of the G2 checkpoint. J Clin Pathol 2005; 58:576-82. [PMID: 15917406 PMCID: PMC1770684 DOI: 10.1136/jcp.2004.022152] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To clarify the fine structure of koilocytes and correlate this with genetic aberration of the G2 checkpoint. METHODS Three dimensional reconstruction from confocal fluorescent images, together with functional assays for key molecules of the G2 checkpoint-cdc2 and cyclin B1-was performed in human uterine cervical samples. After confirming 22 human papillomavirus (HPV) types using a DNA chip from 30 cervical swabs, previously confirmed as 15 cervical low grade and 15 high grade intraepithelial lesions, the activity of molecules involved in the G2 checkpoint was evaluated using western blotting for cyclin B1, cdc2, and phospho-cdc2 (Y15 and T161), a nuclear extraction fractional assay, and a reverse transcription polymerase chain reaction assay. In addition, three dimensional confocal image restoration was performed on confirmed cervical intraepithelial neoplasia tissue samples. RESULTS T161 phospho-cdc2 and cyclin B1 expression was higher in HPV infected cervical lesions than in normal samples. Immunofluorescence, revealed that cyclin B1 was present predominantly in the nuclei of HPV infected cells, confirming the results of the nuclear fractional assay. On restoration of three dimensional confocal images, the multinucleation of koilocytes was revealed to be multilobation of a single nucleus, rather than true multinucleation. This multilobation appeared to be associated with chromosomal instability and aberration of the G2 checkpoint. CONCLUSIONS The multiple nuclei of koilocytes are in fact multilobation of a single nucleus, and this phenomenon is associated with upregulation of gene products related to the G2 checkpoint.
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