Biomedical subjects

Eun Young Choi

Publications and source records attributed to Eun Young Choi.

At least 19 recordsLinked to original sources

PubMed2026

Clinical Utility of Ultra-Widefield Swept-Source OCT for Intraocular Tumors: Comparison With Ultrasonography, SD-OCT, and MRI.

PURPOSE: To evaluate the clinical performance of ultra-widefield swept-source optical coherence tomography (UWF-OCT) in the assessment of choroidal tumors and to compare it with ultrasonography (US), spectral-domain (SD)-OCT, and magnetic resonance imaging (MRI). DESIGN: Retrospective diagnostic comparison. SUBJECTS: Thirty-nine eyes from 39 patients diagnosed with choroidal tumors at a single tertiary referral center. METHODS: This retrospective diagnostic comparison evaluated patients diagnosed with choroidal tumors at a single tertiary referral center between January 2023 and August 2025. All patients underwent UWF-OCT imaging at diagnosis. Tumor measurements obtained with UWF-OCT were compared with US, SD-OCT, and MRI. Comparative analysis among imaging modalities and predictors affecting UWF-OCT applicability was performed. MAIN OUTCOME MEASURES: Tumor thickness (mm) and largest basal diameter (LBD, mm) measurements, and complete measurability rate across different tumor size categories. RESULTS: Thirty-nine eyes from 39 patients (mean age 59.2 ± 16.9 years) were analyzed, including 27 choroidal melanomas (69.2%), 5 metastatic tumors (12.8%), 4 hemangiomas (10.3%), 2 osteomas (5.1%), and 1 (2.6%) indeterminate choroidal melanocytic lesion. UWF-OCT successfully measured both tumor thickness and largest basal diameter (LBD) in 100% (31/31) of small and medium choroidal tumors, substantially outperforming SD-OCT (complete measurement achieved in 63.6% of small tumors, and 0% of medium or large tumors). UWF-OCT measurements were systematically smaller than ultrasonography (thickness: -32.3%, P < .01; LBD: -11.1%, P < .01) and MRI (thickness: -29.2%, P < .01). Mushroom-shaped tumor morphology was the strongest negative predictor of UWF-OCT quality (OR = 0.015, 95% CI 0.001-0.196, P < .01). UWF-OCT's complete measurability was limited in large tumors (12.5%, 1/8). CONCLUSIONS: UWF-OCT provides precise, noninvasive, single-scan assessment of small-to-medium choroidal tumors with detailed structural visualization. It may be particularly useful for dome-shaped tumors, while multimodal imaging with US and MRI remains optimal for complex morphologies. Overall, UWF-OCT represents a valuable tool for diagnosis and treatment planning, with potential utility for longitudinal follow-up in choroidal tumor management.

Humans↗

PubMed2007

Enhancing dendritic cell vaccine potency by combining a BAK/BAX siRNA-mediated antiapoptotic strategy to prolong dendritic cell life with an intracellular strategy to target antigen to lysosomal compartments.

Dendritic cell (DC)-based vaccines have become important in immunotherapeutics as a measure for generating antitumor immune responses. We have previously demonstrated that linkage of the antigen gene to a lysosomal targeting signal, a sorting signal of the lysosome-associated membrane protein type 1 (LAMP-1), enhances the potency of DC-based vaccines. DCs have a limited life span, hindering their long-term ability to prime antigen-specific T cells. In this study, we attempted to further improve the potency of a DC vaccine that targets human papilloma virus 16 (HPV16) E7 to a lysosomal compartment (DC-Sig/E7/LAMP-1) by combining a strategy to prolong DC life. We show that small interfering RNA-targeting Bak and Bax proteins can be used to allow transfected DCs to resist being killed by T cells. This is done by downregulating these proapoptotic proteins, which have been known as so-called gate keepers in mitochondria-mediated apoptosis. DCs expressing intact E7 or Sig/E7/LAMP-1 became resistant to attack by CD8+ T cells after transfection with BAK/BAX siRNA, leading to enhanced E7-specific T cell activation in vitro and in vivo. More importantly, vaccination with E7-presenting DCs transfected with BAK/BAX siRNA generated a strong therapeutic effect against an E7-expressing tumor in vaccinated mice, compared with DCs transfected with control siRNA. Our data indicate that a combination of strategies to enhance intracellular Ag processing and to prolong DC life may offer a promising strategy for improving DC vaccine potency.

Animals↗

PubMed2006

Intergeneric relationship between the Aspergillus ochraceous virus F and the Penicillium stoloniferum virus S.

It was reported that the "slow" component (PsV-S) of Penicillium stoloniferum virus complex also occurred in a second genus, Aspergillus ochraceous. The responsible virus for this intergeneric occurrence was considered to be the "fast" component (AoV-F) of A. ochraceous virus complex. In this investigation, AoV dsRNA 1, that was previously shown to cross-hybridize with PsV-S dsRNA, has been cloned. It was 1754 bp in length and contained one open reading frame of 539 amino acids (p63), had the same genome organization as PsV-S dsRNA S1 and also had the conserved sequence motif of the PsV-S dsRNAs (5'-GCGCAAAA-3') at the 5' terminus. A BLAST search indicated that p63 was a putative dsRNA-dependent RNA polymerase (RdRp), had 81% of sequence homology to members of the genus Partitivirus, and grouped together with PsV-S in phylogenetic analysis. But immunoblot analysis showed that the capsid protein (P3) of AoV-F virus component did not reacted against PsV-S antiserum. These evidences suggest that the cross serological relationship between AoV-F and PsV-S previously observed may have been due to the RdRps of the respective viruses rather than between their respective capsid proteins as was assumed in 1985.

Aspergillus ochraceus↗

PubMed2006

Proteomics studies of post-translational modifications in plants.

Post-translational modifications of proteins greatly increase protein complexity and dynamics, co-ordinating the intricate regulation of biological events. The global identification of post-translational modifications is a difficult task that is currently accelerated by advances in proteomics techniques. There has been significant development in sample preparation methods and mass spectrometry instrumentation. To reduce the complexity and to increase the amount of modified proteins available for analysis, proteins are usually subjected to prefractionation such as chromatographic purification and affinity enrichment. In this review, the post-translational modification studies in plants are summarized. The sample preparation strategies applied to each study are also described. These include affinity-based enrichment methods, immobilized metal affinity chromatography and immunoprecipitation used for phosphorylation and ubiquitination studies, respectively, and the phase partitioning approach for glycosylphosphatidylinositol modification studies.

Chromatography, Affinity↗

PubMed2006

Regulation of hepatocyte growth factor-mediated urokinase plasminogen activator secretion by MEK/ERK activation in human stomach cancer cell lines.

The regulatory mechanisms for the proliferation and the particular invasive phenotypes of stomach cancers are not still fully understood. Up-regulations of hepatocytes growth factor (HGF), its receptor (c-Met), and urokinase-type plasminogen activator (uPA) are correlated with the development and metastasis of cancers. In order to investigate roles of HGF/c-Met signaling in tumor progression and metastasis in stomach cancers, we determined effects of a specific MEK1 inhibitor (PD098059) and a p38 kinase inhibitor (SB203580) on HGF-mediated cell proliferation and uPA expression in stomach cancer cell lines (NUGC-3 and MKN-28). HGF treatment induced the phosphorylations of ERK and p38 kinase in time- and dose- dependent manners. Pre-treatment with PD098059 reduced HGF-mediated cell proliferation and uPA secretion. In contrast, SB203580 pre-treatment enhanced cell proliferation and uPA secretion due to induction of ERK phosphorylation. Stable expression of dominant negative-MEK1 in NUGC-3 cells showed a decrease in HGF-mediated uPA secretion. These results suggest that interaction of a MEK/ERK and a p38 kinase might play an important role in proliferation and invasiveness of stomach cancer cells.

Cell Line, Tumor↗

PubMed2006

Association of C-reactive protein with the metabolic risk factors among young and middle-aged Koreans.

We investigated the relationship between the clustering of risk factors for metabolic syndrome and the plasma C-reactive protein (CRP) concentration as measured by high-sensitive CRP assay. Body mass index, waist circumference, triglycerides (TGs), high-density lipoprotein cholesterol, fasting glucose, systolic and diastolic blood pressures, insulin, and CRP were measured in 1046 Korean adults (560 males; age, 18-64 years) in 2003 to 2004. There were statistically significant positive correlations for log CRP with body mass index, waist circumference, log TG, log insulin, and log homeostasis model assessment in both sexes after adjusting for age and smoking status. High-density lipoprotein cholesterol showed a significant negative correlation with log CRP in both sexes. For both sexes, the mean level of log CRP increased with increasing number of risk factors of metabolic syndrome (P for trend <.01 for males and <.001 for females). Stepwise multivariate linear regression analysis showed that waist circumference contributed the largest portion of the variance in CRP levels in both sexes. Log homeostasis model assessment and log TG were independently associated with log CRP levels only in females. These results indicate that CRP, a marker of inflammation that underlies atherosclerosis, is associated with the clustering of each metabolic syndrome risk factor and, furthermore, that abdominal obesity is the strongest predictor of CRP level in the Korean adult population.

Adolescent↗

PubMed2006

Overexpression of CIITA in T cells aggravates Th2-mediated colitis in mice.

The MHC class II transactivator (CIITA) is the master transcriptional regulator of genes involved in MHC class II restricted antigen presentation. Previously we suggested another role of CIITA in Th1/Th2 balance by demonstrating that forced expression of CIITA in murine T cells repressed Th1 immunity both in vitro and in vivo. However, the results were contradictory to the report that CIITA functioned to suppress the production of Th2 cytokine by CD4+ T cells in CIITA deficient mice. In this study, we investigated the influence of constitutive expression of CIITA in T cells on Th2 immune response in vivo using murine experimental colitis model. In the dextran sodium sulfate-induced acute colitis, a disease involving innate immunity, CIITA transgenic mice and wild type control mice showed similar progression of the disease. However, the development of oxazolone-induced colitis, a colitis mediated by predominantly Th2 immune response, was aggravated in CIITA-transgenic mice. And, CD4+ T cells from the mesenteric lymph node of CIITA-transgenic mice treated with oxazolone exhibited a high level of IL-4 secretion. Together, these data demonstrate that constitutive expression of CIITA in T cells skews immune response to Th2, resulting in aggravation of Th2-mediated colitis in vivo.

Animals↗

PubMed2006

Hepatocyte growth factor/c-met signaling in regulating urokinase plasminogen activator in human stomach cancer: A potential therapeutic target for human stomach cancer.

BACKGROUND: Up-regulation of the hepatocyte growth factor (HGF), its transmembrane tyrosine kinase receptor (c-Met), and urokinase type plasminogen activator (uPA), is associated with the development and metastasis of various types of cancers. However, the mechanisms by which HGF/c-Met signaling mediates cancer progression and metastasis are unclear. METHODS: We investigated the roles of HGF/c-Met in tumor progression and metastasis in NUGC-3 and MKN-28 stomach cancer cell lines. RESULTS: Treatment with HGF increased c-Met phosphorylation in a dose-dependent manner, as well as increasing cell proliferation. HGF treatment also increased the protein level and the activity of uPA in NUGC-3 and MKN-28 cells. A monoclonal antibody against human uPA receptor (uPAR), mAb 3936, inhibited HGF-mediated tumor cell invasion in a dose-dependent manner. Down-regulation of uPA using uPA-shRNA induced a decrease in in vitro cell invasion in NUGC-3 cells. CONCLUSIONS: These results suggest that NUGC-3 and MKN-28 cells express functional c-Met, which may provide a therapeutic target for interfering with metastases of cancer cells by inhibiting uPA and uPAR-mediated proteolysis.

Adenocarcinoma↗

PubMed2006

Users' satisfaction on the electronic nursing record system.

Seoul National University Bundang Hospital is the first full digital hospital with an electronic nursing record (ENR) system in Korea. We analyzed the satisfaction of users on the ENR system, 1 and 1/4 years from its implementation. A total of 503 nurses participated in this study. The questionnaire was composed of 4 domains: satisfaction for paper records vs. ENR, work efficiency, user interface, and the advantages and disadvantages of an ENR system. Most nurses were more satisfied with the ENR system than with paper records. They also showed satisfaction for most of user interfaces, which seemed to be related with working efficiency. In conclusion, users seem to be satisfied with the ENR system and we hope that this study will provide helpful data for many hospitals that are planning to adopt ENR systems in the near future.

Consumer Behavior↗

PubMed2006

Analysis of electronic nursing records based on the ICNP.

The ENR System of Seoul National University Bundang Hospital was made after analyzing paper-based narrative nursing records with ICNP, a combinatorial nursing terminology. In this study, we analyzed paper-based narrative nursing records with ICNP on surgical patients and evaluated practical use of the terminology and the system after building and applying ENR System. We found that we need to add new concepts to the ICNP to improve expression of nursing records especially in describing nursing actions.

Humans↗

PubMed2005

Regulation of NMDA receptor trafficking by amyloid-beta.

Amyloid-beta peptide is elevated in the brains of patients with Alzheimer disease and is believed to be causative in the disease process. Amyloid-beta reduces glutamatergic transmission and inhibits synaptic plasticity, although the underlying mechanisms are unknown. We found that application of amyloid-beta promoted endocytosis of NMDA receptors in cortical neurons. In addition, neurons from a genetic mouse model of Alzheimer disease expressed reduced amounts of surface NMDA receptors. Reducing amyloid-beta by treating neurons with a gamma-secretase inhibitor restored surface expression of NMDA receptors. Consistent with these data, amyloid-beta application produced a rapid and persistent depression of NMDA-evoked currents in cortical neurons. Amyloid-beta-dependent endocytosis of NMDA receptors required the alpha-7 nicotinic receptor, protein phosphatase 2B (PP2B) and the tyrosine phosphatase STEP. Dephosphorylation of the NMDA receptor subunit NR2B at Tyr1472 correlated with receptor endocytosis. These data indicate a new mechanism by which amyloid-beta can cause synaptic dysfunction and contribute to Alzheimer disease pathology.

Alzheimer Disease↗

PubMed2005

Diversification of hydrothermal reaction products induced by naphthalene molecules.

Hydrothermal reactions in the system of Ni(II), 1,3,5-benzenetricarboxylic acid (btcH3), and 4,4'-bipyridine (bpy) with or without naphthalene produced three new coordination polymers, [Ni2(bpy)3(btcH)2.(H2O)].(H2O) (2), [Ni2(bpy)2(btcH)2].(C10H8)3 (3), and Ni(bpy)(btcH2)2 (4), in addition to previously reported [Ni2(bpy)2(btcH)2].(C10H8)(0.75).H2O (1). Polymer 2 is the only product when naphthalene is absent in the reaction, and it is composed of 2D layers of coordination polymers with guest water molecules between them. When naphthalene is added to the system, compounds 1, 3, or 4 are formed depending on composition. Compound 3 has a 3D framework structure with naphthalene guests, and 4 has a 1D chainlike structure with no guest. Details of the synthesis condition and crystal structures of each compound are discussed. Crystallographic data: 2, C2/c, a = 22.500(3) A, b = 20.053(3) A, c = 19.625(3) A, beta = 99.314(3) degrees ; 3, P2(1)/c, a = 11.248(2) A, b = 16.801(4) A, c = 14.945(3) A, beta = 103.732(4) degrees ; 4, C2/c, a = 10.692(2) A, b = 11.114(3) A, c = 21.962(5) A, beta = 106.268(11) degrees.

Journal Article↗

PubMed2005

Genome organization and expression of the Penicillium stoloniferum virus F.

The complete sequences of three double-stranded (ds) RNAs (referred to F1, F2 and F3) of Penicillium stoloniferum virus F (PsV-F) were established. The F1 dsRNA was 1677 bp in length, and it contained one open reading frame (ORF) of 538 amino acids (molecular weight of 63 kDa, referred to P63), The F2 dsRNA was 1500 by in length, and also it contained one ORF of 420 amino acids (molecular weight of 46 kDa, referred to P46). The F3 dsRNA was 677 bp in length, but contained a small ORF with unknown function. A sequence motif of (5'-CGTAAAA-3') was found only at the 5' termini of the F1 and F2 dsRNAs, and a sequence motif of (5'-TAAAAAAAAA-3') was found at the 3' termini of all three dsRNA segments. The predicted amino acid sequence of F1 showed 38-48% sequence homology with the putative dsRNA-dependent RNA polymerases (RdRp) of dsRNA viruses, but the predicted amino acid of F2 showed no homology. Phylogenetic analysis using the RdRp sequences of the various Partitiviruses and Alphacryptoviruses revealed that PsV-F clustered well with Partitiviruses, but showed remote relationship with PsV-S. Near full-length and positive-sense single-stranded (ss) RNAs derived from the Fl, F2 and F3 dsRNAs were detected from the PsV-infected host cell. The expressed proteins of P63 and P46 showed a positive reaction against PsV-F antiserum, indicating P63 and P46 as RdRp and capsid protein, respectively. These results suggest that PsV-F can be a member of Partitivirus, but it is quite distinct from PsV-S electrophoretically, serologically and genetically, though both viruses coexist in the same cell.

Amino Acid Sequence↗

PubMed2005

Thymocyte-thymocyte interaction for efficient positive selection and maturation of CD4 T cells.

Despite numerous reports on MHC class II expression by T cells from a wide spectrum of mammalian species including humans, the biological relevance of this phenomenon has never been tested with appropriately designed animal models. To address this issue, we developed mouse models in which immature thymocytes are the only positively selecting antigen-presenting cells in the thymus. In these mice, CD4+ T cells were generated with the appropriate maturation phenotype and showed a diverse repertoire of TCR Vbetas. The CD4+ T cells were functionally competent, mediating effective allogeneic responses that involved polyclonal TCR Vbetas. These results suggest that the thymocyte-thymocyte (T-T) interaction operates as an independent pathway for CD4+ T cell selection in the thymi of species with MHC II-positive thymocytes. This T-T interaction appears to be the basis for the generation of donor MHC-restricted CD4+ T cells in xenogeneic hosts.

Animals↗

PubMed2005

Salvage chemotherapy with irinotecan and cisplatin in patients with metastatic gastric cancer failing both 5-fluorouracil and taxanes.

We conducted a phase II study to assess the efficacy and tolerability of irinotecan and cisplatin as salvage chemotherapy in patients with advanced gastric adenocarcinoma, progressing after both 5-fluorouracil (5-FU)- and taxane-containing regimen. Patients with measurable metastatic gastric cancer, progressive after previous chemotherapy that consisted either of a 5-FU-based regimen followed by second-line chemotherapy containing taxanes or a 5-FU and taxane combination were treated with irinotecan and cisplatin. Irinotecan 70 mg/m(2) was administered on day 1 and day 15; cisplatin 70 mg/m(2) was administered on day 1. Treatment was repeated every 4 weeks. For 28 patients registered, a total of 94 chemotherapy cycles were administered. The patients' median age was 51 years and 27 (96%) had an ECOG performance status of 1 or below. In an intent-to-treat analysis, seven patients (25%) achieved a partial response, which maintained for 6.3 months (95% confidence interval 6.2-6.4 months). The median progression-free and overall survival were 3.5 and 5.6 months, respectively. Major toxic effects included nausea, diarrhea and neurotoxicity. Although there was one possible treatment-related death, toxicity profiles were generally predictable and manageable. We conclude that irinotecan and cisplatin is an active combination for patients with metastatic gastric cancer in whom previous chemotherapy with 5-FU and taxanes has failed.

Adenocarcinoma↗

PubMed2004

T cell expression of CIITA represses Th1 immunity.

Despite the fact that major histocompatibility complex class II transactivator (CIITA) has been known to be involved in Th1/Th2 balance in addition to its major role as a master regulator for the expression of MHC class II genes, the exact role of CIITA in Th1/Th2 balance is still controversial. To investigate whether the Th1/Th2 balance could be modulated by T cell specific expression of CIITA, we generated CIITA-transgenic mice, in which the CIITA expression is controlled by the distal promoter of p56lck, resulting in constitutive expression of CIITA predominantly in peripheral T cells. Naive CD4+ T cells from CIITA-transgenic mice exhibited a low level of IFN-gamma secretion as well as impaired Th1 polarization in vitro, while IL-4 secretion was enhanced under Th2 condition. In addition, the development of experimental autoimmune encephalomyelitis (EAE), a prototype of Th1-mediated disease, was repressed in CIITA-transgenic mice. Resistance to EAE was correlated with reduced production of IFN-gamma in response to MOG35-55, while the proliferation of MOG35-55 -specific T cells was not affected in CIITA-transgenic mice. Together, these data demonstrate that overexpression of CIITA in T cells inhibits Th1 differentiation and function, suggesting that the expression of CIITA in T cells might play a role in the regulation of the Th1/Th2 balance during the T cell lineage commitment.

Animals↗

PubMed2004

Involvement of MAPK pathway in hypoxia-induced up-regulation of urokinase plasminogen activator receptor in a human prostatic cancer cell line, PC3MLN4.

Clinical studies have shown that tumor hypoxia is associated with invasive growth and metastasis and may be an important prognostic factor adversely influencing survival in patients with tumors. To investigate the mechanisms involved in hypoxia-induced invasive growth and metastasis, hypoxia-mediated urokinase plasmalogen activator receptor (uPAR) expression, cellular invasiveness, and mitogen activated protein kinase (MAPK) activation were measured in a prostate cancer cell line, PC3MLN4. The levels of uPAR expression and cellular invasiveness were increased in hypoxic cells. Hypoxia-induced cellular invasiveness was blocked by an anti-uPAR monoclonal antibody. Phosphorylations of ERK and p38 kinases were also more extensive in hypoxic cells than in normoxic cells. Hypoxia-induced uPAR up-regulation was inhibited by pre-treatments with a specific inhibitor of MEK, PD98059 and a specific inhibitor of p38 MAP kinase, SB203580. Cell growth also increased in hypoxic cells. From these results, hypoxia increased tumor cell invasion by up-regulating uPAR expression, which might be mediated through ERK and p38 kinase signaling pathways in PC3MLN4 prostate cancer cell line.

Animals↗

PubMed2004

TCR-independent and caspase-independent apoptosis of murine thymocytes by CD24 cross-linking.

CD24, also referred to as the heat-stable Ag, is a T cell differentiation Ag that is highly expressed on both CD4-CD8- double negative and CD4+CD8+ double positive thymocytes. Here, we report that CD24 ligation by a new anti-CD24 Ab, mT-20, induced the apoptosis of both double negative and double positive thymocytes, as well as the Scid.adh thymic lymphoma cell line, in the absence of TCR/CD3 engagement. CD24-mediated apoptosis of mouse thymocytes and its signaling pathway appeared not to be associated with p53, CD95, TNFR, or caspases. Furthermore, we found that cell death was blocked by the addition of scavengers of reactive oxygen species or by Bcl-2 overexpression, implying the role of CD24 signaling in the mitochondrial regulation. In this study, we suggest that CD24 ligation induced the apoptosis of immature thymocytes independently of both caspase and TCR.

Animals↗