109 results on '"Sejong Chun"'
Search Results
2. Comprehensive analysis of oncogenic signatures and consequent repurposed drugs in TMPRSS2:ERG fusion‐positive prostate cancer
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Jae Won Yun, Sejoon Lee, Sejong Chun, Kwang Woo Lee, Jongsu Kim, and Hong Sook Kim
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Medicine (General) ,R5-920 - Published
- 2021
- Full Text
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3. Evaluation of a Fully Automated Antinuclear Antibody Indirect Immunofluorescence Assay in Routine Use
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Hyun-Woo Choi, Yong Jun Kwon, Ju-Heon Park, Seung-Yeob Lee, Sejong Chun, Eun Jeong Won, Jun Hyung Lee, Hyun-Jung Choi, Soo Hyun Kim, Myung-Geun Shin, Jong-Hee Shin, and Seung-Jung Kee
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antinuclear antibody ,immunofluorescence assay ,automation ,pattern recognition ,titer estimation ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Indirect immunofluorescence assay (IFA) using HEp-2 cells as a substrate is the gold standard for detecting antinuclear antibodies (ANA) in patient serum. However, the ANA IFA has labor-intensive nature of the procedure and lacks adequate standardization. To overcome these drawbacks, the automation has been developed and implemented to the clinical laboratory. The purposes of this study were to evaluate the analytical performance of a fully automated Helios ANA IFA analyzer in a real-life laboratory setting, and to compare the time and the cost of ANA IFA testing before and after adopting the Helios system. A total of 3,276 consecutive serum samples were analyzed for ANA using the Helios system from May to August 2019. The positive/negative results, staining patterns, and endpoint titers were compared between Helios and visual readings. Furthermore, the turnaround time and the number of wells used were compared before and after the introduction of Helios system. Of the 3,276 samples tested, 748 were positive and 2,528 were negative based on visual readings. Using visual reading as the reference standard, the overall relative sensitivity, relative specificity, and concordance of Helios reading were 73.3, 99.4, and 93.4% (κ = 0.80), respectively. For pattern recognition, the overall agreement was 70.1% (298/425) for single patterns, and 72.4% (89/123) for mixed patterns. For titration, there was an agreement of 75.9% (211/278) between automated and classical endpoint titers by regarding within ± one titer difference as acceptable. Helios significantly shortened the median turnaround time from 100.6 to 55.7 h (P < 0.0001). Furthermore, routine use of the system reduced the average number of wells used per test from 4 to 1.5. Helios shows good agreement in distinguishing between positive and negative results. However, it still has limitations in positive/negative discrimination, pattern recognition, and endpoint titer prediction, requiring additional validation of results by human observers. Helios provides significant advantages in routine laboratory ANA IFA work in terms of labor, time, and cost savings. We hope that upgrading and developing softwares with more reliable capabilities will allow automated ANA IFA analyzers to be fully integrated into the routine operations of the clinical laboratory.
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- 2020
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4. Double-filtered leukoreduction as a method for risk reduction of transfusion-associated graft-versus-host disease.
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Sejong Chun, Minh-Trang Thi Phan, Saetbyul Hong, Jehoon Yang, Yeup Yoon, Sangbin Han, Jungwon Kang, Mark H Yazer, Jaehyun Kim, and Duck Cho
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Medicine ,Science - Abstract
BackgroundTransfusion-associated graft-versus-host disease (TA-GvHD) is caused by leukocytes, specifically T cells within a transfused blood product. Currently, the prevention of transfusion-associated graft-versus-host disease is performed by irradiation of blood products. With a sufficient reduction of leukocytes, the risk for TA-GvHD can be decreased. With consistent advances in current state-of-the-art blood filters, we herein propose that double filtration can sufficiently reduce leukocytes to reduce the risk for TA-GvHD.MaterialsThirty RBC concentrates were filtered with leukocyte filters, followed by storage at 1-6 oC for 72 hours, and then a second filtration was performed. Residual leukocytes in the double-filtered RBC units (n = 30) were assessed with flow cytometric methods, and an additional assay with isolated peripheral blood mononuclear cells (PBMCs) (n = 6) was done by both flow cytometric methods and an automated hematology analyzer. Quality of the RBCs after filtration was evaluated by hematological and biochemical tests. In vitro T cell expansion was performed using anti-CD3/CD28-coated Dynabeads or anti-CD3 (OKT3). In vivo experiment for GvHD was performed by using NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice.ResultsDouble-filtered blood products showed residual leukocyte levels below detection limits, which calculated to be below 1200-2500 cells per blood unit. In vitro expansion rate of T cells showed that 6x103 and 1x103 cell-seeded specimens showed 60.8±10.6 fold and 10.2±9.7-fold expansion, respectively. Cell expansion was not sufficiently observed in wells planted with 1x102 or 10 cells. In vivo experiments showed that mice injected with 1x105 or more cells cause fatal GvHD. GvHD induced inflammation was observed in mice injected with 1x104 or more cells. No evidence of GvHD was found in mice injected with 103 cells.ConclusionsOur study suggests that additional removal of contaminating lymphocytes by a second leukodepletion step may further reduce the risk for TA-GvHD.
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- 2020
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5. Expansion of Human NK Cells Using K562 Cells Expressing OX40 Ligand and Short Exposure to IL-21
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SoonHo Kweon, Minh-Trang Thi Phan, Sejong Chun, HongBi Yu, Jinho Kim, Seokho Kim, Jaemin Lee, Alaa Kassim Ali, Seung-Hwan Lee, Sang-Ki Kim, Junsang Doh, and Duck Cho
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natural killer cells ,expansion ,IL-21 ,K562 ,OX40 ligand ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Background: Natural Killer (NK) cell-based immunotherapy used to treat cancer requires the adoptive transfer of a large number of activated NK cells. Here, we report a new effective method to expand human NK cells ex vivo using K562 cells genetically engineered (GE) to express OX40 ligand (K562-OX40L) in combination with a short exposure to soluble IL-21. In addition, we describe a possible mechanism of the NK cell expansion through the OX40 receptor-OX40 ligand axis which is dependent on NK cell homotypic interaction.Methods: K562-OX40L cells were generated by lentiviral transduction and were used as feeder cells to expand and activate NK cells from PBMCs in the presence of IL-2/IL-15. Soluble IL-21 was also added in various concentrations only once at the beginning of the culture. NK cells were expanded for 4–5 weeks, and the purity, expansion rate, phenotype and function (cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC), cytokine production, CD107a degranulation) of these expanded NK cells were compared to those generated by using K562 feeder cells.Results: The culture of NK cells with K562-OX40L cells in combination with the transient exposure to IL-21 highly enhanced NK cell expansion to approximately 2,000-fold after 4 weeks of culture, compared to a 303-fold expansion using the conventional K562 cells. Mechanistically, the OX40-OX40L axis between the feeder cells and NK cells as well as the homotypic interaction between NK cells through the OX40-OX40L axis were both necessary for NK cell expansion. The short exposure of NK cells to IL-21 had a synergistic effect with OX40 signaling for NK cell expansion. Apart from their enhanced expansion, NK cells grown with K562-OX40L feeder cells were similar to those grown with conventional K562 cells in regard to the surface expression of various receptors, cytotoxicity, ADCC, cytokine secretion, and CD107 degranulation.Conclusion: Our data suggest that OX40 ligand is a potent co-stimulant for the robust expansion of human NK cells and the homotypic NK cell interactions through the OX40-OX40L axis is a mechanism of NK cell expansion.
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- 2019
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6. Evaluation of alpha-fetoprotein as a screening marker for hepatocellular carcinoma in hepatitis prevalent areas
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Sejong Chun, Su Yeon Rhie, Chang-Seok Ki, Jee Eun Kim, and Hyung-Doo Park
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Alpha-fetoprotein ,Hepatocellular carcinoma ,Liver cancer ,Screening ,Specialties of internal medicine ,RC581-951 - Abstract
The objective of this study was to establish modified cutoff values of serum alpha-fetoprotein (AFP) according to hepatitis status. While AFP is used as a serum marker in the diagnosis or monitoring of hepatocellular carcinoma (HCC), its use as a screening method to the general population is controversial. We evaluated its screening performance in a hepatitis prevalent East Asian population, and suggest different cutoff values according to the individual’s hepatitis status. We evaluated the performance of AFP as a screening test in 48,123 consecutive Koreans during the period from March, 2012 to August, 2013 who underwent routine health checks at a single institution. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated with fixed cutoff and with modified cutoffs according the individual’s hepatitis status. A total of 24 out of 48,123 subject (0.05%) were newly diagnosed with HCC after screening. Among the 1,874 subject with positive hepatitis B virus surface antigen (HBsAg), 17 (0.91%) developed HCC, compared with two out of 393 (0.51%) individuals with hepatitis C virus antibody (anti-HCV). Five out of 45,855 (0.01%) subject with neither HBsAg nor anti-HCV developed HCC. Compared to the performance of a fixed cutoff, specificity, PPV, and NPV improved without sacrificing sensitivity when applying modified cutoff. In conclusion, our findings suggest that AFP with modified cutoffs according to the individual’s hepatitis status might be a useful screening marker for HCC in hepatitis prevalent areas.
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- 2015
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7. Clinical Significance of Isolates Known to Be Blood Culture Contaminants in Pediatric Patients
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Sejong Chun, Cheol-In Kang, Yae-Jean Kim, and Nam Yong Lee
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pediatric bacteremia ,blood stream infection ,contaminant ,viridans group streptococcus ,coagulase-negative staphylococcus ,true infection ,Medicine (General) ,R5-920 - Abstract
Background and objectives: The objective of this study was to investigate the clinical significance of isolates from blood stream infection known to be blood culture contaminants in pediatric patients. Materials and Methods: Microbiological reports and medical records of all blood culture tests issued from 2002 to 2012 (n = 76,331) were retrospectively reviewed. Evaluation for potential contaminants were done by reviewing medical records of patients with the following isolates: coagulase-negative Staphylococcus, viridans group Streptococcus, Bacillus, Corynebacterium, Micrococcus, Aerococcus, and Proprionibacterium species. Repeated cultures with same isolates were considered as a single case. Cases were evaluated for their status as a pathogen. Results: Coagulase-negative Staphylococcus had clinical significance in 23.8% of all cases. Its rate of being a true pathogen was particularly high in patients with malignancy (43.7%). Viridans group Streptococcus showed clinical significance in 46.2% of all cases. Its rate of being a true pathogen was similar regardless of the underlying morbidity of the patient. The rate of being a true pathogens for remaining isolates was 27.7% for Bacillus and 19.0% for Corynebacterium species. Conclusions: Coagulase-negative Staphylococcus and viridans group Streptococcus isolates showed high probability of being true pathogens in the pediatric population, especially in patients with underlying malignancy.
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- 2019
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8. Elucidation of Novel Therapeutic Targets for Acute Myeloid Leukemias with RUNX1-RUNX1T1 Fusion
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Jae Won Yun, Yoon Kyung Bae, So Yeong Cho, Harim Koo, Hee-Jin Kim, Do-Hyun Nam, Sun-Hee Kim, Sejong Chun, Kyeung Min Joo, and Woong-Yang Park
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acute myeloid leukemia ,RUNX1-RUNX1T1 ,oncogenes ,transcription factor ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The RUNX1-RUNX1T1 fusion is a frequent chromosomal alteration in acute myeloid leukemias (AMLs). Although RUNX1-RUNX1T1 fusion protein has pivotal roles in the development of AMLs with the fusion, RUNX1-RUNX1T1, fusion protein is difficult to target, as it lacks kinase activities. Here, we used bioinformatic tools to elucidate targetable signaling pathways in AMLs with RUNX1-RUNX1T1 fusion. After analysis of 93 AML cases from The Cancer Genome Atlas (TCGA) database, we found expression of 293 genes that correlated to the expression of the RUNX1-RUNX1T1 fusion gene. Based on these 293 genes, the cyclooxygenase (COX), vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR) pathways were predicted to be specifically activated in AMLs with RUNX1-RUNX1T1 fusion. Moreover, the in vitro proliferation of AML cells with RUNX1-RUNX1T1 fusion decreased significantly more than that of AML cells without the fusion, when the pathways were inhibited pharmacologically. The results indicate that novel targetable signaling pathways could be identified by the analysis of the gene expression features of AMLs with non-targetable genetic alterations. The elucidation of specific molecular targets for AMLs that have a specific genetic alteration would promote personalized treatment of AMLs and improve clinical outcomes.
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- 2019
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9. Paul’s Galatian Mission and Southern-Galatian Theory
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Sejong Chun
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- 2021
10. Low CtBP2 expression is associated with a stem cell-like signature and adverse clinical outcome in childhood B-cell lymphoblastic leukemia
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Sun-Hee Kim, Joseph L. Wiemels, Seung-Tae Lee, Hyun-Young Kim, Hee Jin Kim, Keon Hee Yoo, Sejong Chun, Mi Zhou, and Hong Hoe Koo
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Cancer Research ,Text mining ,Oncology ,business.industry ,Cancer research ,Hematology ,B-Cell Lymphoblastic Leukemia ,Stem cell ,Biology ,business ,CTBP2 - Published
- 2021
11. Survey on the Preparation Status of Medical Institutions Regarding the Full Revision of the Korean Blood Inventory Monitoring System
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Jun Nyun Kim, Kyeong Eun Jeong, Ji Seon Choi, Jeong Won Shin, Jin A Oh, Young Ae Lim, Sejong Chun, and Yung Zoon Jung
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business.industry ,Medicine ,Monitoring system ,Blood supply ,Medical emergency ,business ,medicine.disease - Published
- 2020
12. Low Temperature Testing of Ultrasound Sensors in Liquid Nitrogen
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Michael Myung-Sub Lee, Sejong Chun, Joseph Chul Chung, and Inseok Yang
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Materials science ,chemistry ,business.industry ,Optoelectronics ,chemistry.chemical_element ,Ultrasonic sensor ,Liquid nitrogen ,business ,Nitrogen ,Temperature testing - Abstract
Ultrasonic flow metering is one of flow measurement techniques applicable to low temperature environment. Unlike pipe provers or Coriolis mass flowmeters, ultrasonic flowmeters require waveguides in front of ultrasound sensors. The waveguides can prevent heat conduction from the ultrasound sensors to low temperature liquids, such as liquid nitrogen. The ultrasound sensors can maintain its piezoelectricity within the specified temperature ranges by thermal insulation of the waveguides. In this study, low temperature testing on a pair of ultrasound sensors was performed to see if ultrasound waves could be transmitted normally through liquid nitrogen. A flowmeter cell with diameter of 300 mm (equivalently, 12”) was used as a container for liquid nitrogen. Three pairs of ultrasound sensors were installed in the flowmeter cell. Fiber-optic sensors were also attached on its inner wall to measure the temperature of liquid nitrogen. As a result, ultrasound waves were successfully transmitted between a pair of ultrasound sensors by using a preamplifier. The fiber-optic sensors could measure the temperature of liquid nitrogen although the sensors were not calibrated by the reference temperature scale at KRISS.
- Published
- 2021
13. Comprehensive analysis of oncogenic signatures and consequent repurposed drugs in TMPRSS2:ERG fusion‐positive prostate cancer
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Hong Sook Kim, Jongsu Kim, Sejong Chun, Sejoon Lee, Jae Won Yun, and Kwang Woo Lee
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Male ,Medicine (General) ,business.industry ,Gene Expression Profiling ,Serine Endopeptidases ,Drug Repositioning ,Prostatic Neoplasms ,Medicine (miscellaneous) ,Antineoplastic Agents ,medicine.disease ,Letter to Editor ,TMPRSS2 ,Prostate cancer ,R5-920 ,Text mining ,Transcriptional Regulator ERG ,medicine ,Cancer research ,Humans ,Molecular Medicine ,Gene Fusion ,business ,Erg - Published
- 2021
14. A Study on Yonggi Cho’s Contributions and Limitations for the Growth of the Korean Church
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Sejong Chun
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Political science ,Religious studies ,Church Growth - Published
- 2019
15. Case of D-Variant from a Frameshift MutationRHD711delC
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HongBi Yu, Myung Geun Shin, Duck Cho, Sejong Chun, Suhak Jeon, and Taeo Ma
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Genetics ,Genotype ,Biology ,Frameshift mutation - Published
- 2019
16. Born From Above: Meaning and Function of γεννηθῇ ἄνωθεν in John 3:3
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Sejong Chun
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Vocabulary ,Expression (architecture) ,Judaism ,media_common.quotation_subject ,Rhetorical device ,Identity (social science) ,Context (language use) ,Meaning (existential) ,Sociology ,Excommunication ,Genealogy ,media_common - Abstract
In this paper, I have attempted to suggest possible meaning and function of the phrase, “γeννηθῇ ἄνωθeν” in the context of the Johannine community and in understanding Nicodemus. The Johannine community which was experiencing a crisis caused by the excommunication from the Jewish synagogue and inner conflicts among members tried to establish a new identity of “those who were born from above” and create a communal unity through the expression, “γeννηθῇ ἄνωθeν.” Although “γeννηθῇ ἄνωθeν” has a role of an “anti-language” and a rhetorical device of “misunderstanding,” it actually functions as an “invitational language” for Nicodemus in terms of being part of the vocabulary of Jesus-followers who accept a new identity of being “born from above” through water and the Spirit.
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- 2019
17. Red Blood Cell Alloimmunization in Korean Patients With Myelodysplastic Syndrome and Liver Cirrhosis
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Eun Jung Cho, Hyun-Young Kim, Kyeong Hee Kim, Duck Cho, and Sejong Chun
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medicine.medical_specialty ,Cirrhosis ,business.industry ,Biochemistry (medical) ,Clinical Biochemistry ,General Medicine ,030204 cardiovascular system & hematology ,medicine.disease ,Gastroenterology ,Cumulative risk ,03 medical and health sciences ,Red blood cell ,0302 clinical medicine ,medicine.anatomical_structure ,Interquartile range ,Internal medicine ,medicine ,In patient ,business ,030215 immunology - Abstract
Red blood cell (RBC) alloimmunization varies across human populations and ethnic groups. We evaluated the characteristics of RBC alloimmunization and compared the risk of alloimmunization in Korean patients with myelodysplastic syndrome (MDS) and liver cirrhosis (LC), two representative diseases in which chronic transfusion is required. In total, 115 MDS patients and 202 LC patients transfused with RBCs between 2013 and 2015 were retrospectively included. Twenty patients (6.3%) were newly alloimmunized (five MDS patients, 4.3%; 15 LC patients, 7.4%). The median number of RBC units transfused in alloimmunized patients was nine (interquartile range, 4-15 units). As the number of transfused RBC units increased, the cumulative risk of alloimmunization was higher in LC than in MDS patients (P=0.001). The most common alloantibody detected in patients was anti-E (45%), followed by anti-c (17%), anti-e (10%), anti-C (7%), anti-Fyb (7%), and anti-Jka (7%). The present data indicate the need for matching of extended RBC antigens (Rh, Duffy, and Kidd systems) for chronically transfused patients with MDS and LC in Korea.
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- 2019
18. Cis-AB, the Blood Group of Many Faces, Is a Conundrum to the Novice Eye
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Sooin Choi, HongBi Yu, Duck Cho, and Sejong Chun
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Genetics ,Blood type ,ABO ,Genotyping ,Transfusion Medicine ,Biochemistry (medical) ,Clinical Biochemistry ,cis-AB ,General Medicine ,Cis AB ,Review Article ,030204 cardiovascular system & hematology ,Biology ,Phenotype ,03 medical and health sciences ,0302 clinical medicine ,Serology ,ABO blood group system ,Mutation (genetic algorithm) ,Clinical significance ,Allele ,Gene ,030215 immunology - Abstract
Cis-AB, a rare ABO variant, is caused by a gene mutation that results in a single glycosyltransferase enzyme with dual A and B glycosyltransferase activities. It is the most frequent ABO subgroup in Korea, and it occurs more frequently in the East Asian region than in the rest of the world. The typical phenotype of cis-AB is A2B3, but it can express various phenotypes when paired with an A or B allele, which can lead to misclassification in the ABO grouping and consequently to adverse hemolytic transfusion reactions. While cis-AB was first discovered as having an unusual inheritance pattern, it was later found that both A and B antigens are expressed from the same allele inherited from a single parent; hence, the name cis-AB. Earlier studies relied on serological and familial investigation of cis-AB subjects, but its detection has become much easier with the introduction of molecular methods. This review will summarize the serological variety, genetic basis and inheritance pattern, laboratory methods of investigation, clinical significance, and the blood type of choice for transfusion for the cis-AB blood group.
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- 2018
19. Initial experience with high-volume plasma exchange in patients with acute liver failure
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Dong Hyun Sinn, Wonseok Kang, Gyu-Seong Choi, Ji Eun Kim, Nam Joong Kim, Jae-Won Joh, Duck Cho, Semi Kim, Sejong Chun, and Jong Man Kim
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Adult ,Male ,medicine.medical_specialty ,Bilirubin ,medicine.medical_treatment ,Ammonia levels ,030204 cardiovascular system & hematology ,Liver transplantation ,Gastroenterology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,medicine ,Humans ,In patient ,Alanine aminotransferase ,Hepatic encephalopathy ,Retrospective Studies ,Plasma Exchange ,business.industry ,Liver failure ,Hematology ,General Medicine ,Liver Failure, Acute ,Middle Aged ,medicine.disease ,chemistry ,Female ,Fresh frozen plasma ,business ,030215 immunology - Abstract
BACKGROUND/AIMS High-volume plasma exchange (HVPE), defined as an exchange of 8 to 12 L per day per procedure or 15% of the ideal body weight with fresh frozen plasma, has shown promising results in improving the survival of patients with acute liver failure (ALF). However, clinical evidence is limited. The aim of this study was to report our initial experience using HVPE as a bridge treatment in patients with ALF. METHODS We retrospectively reviewed 32 consecutive patients awaiting liver transplantation (LT) due to ALF between 2013 and 2020 at Samsung Medical Center in Korea. HVPE has been used for patients with ALF since May 2016 at our institution. RESULTS During the study period, 16 patients received HVPE. After HVPE, coagulopathies (INR, 4.46 [2.32-6.02] vs 1.48 [1.33-1.76], P
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- 2020
20. Paul’s New Creation : Vision for a New World and Community
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Sejong Chun and Sejong Chun
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- Bible. Epistles of Paul--Criticism, interpretati
- Abstract
In Paul's New Creation: Vision for a New World and Community, Sejong Chun presents inter(con)textual readings of Paul's new creation passages from the perspective of the Korean immigrant church in America. Chun focuses on Paul's new creation's cosmic dimension and ecclesiastical character and proposes the ekklēsia as a tangible embodiment. The author suggests that Paul, as a middleman, accomplishes the collective project of the Jerusalem collection with his Gentile churches to declare independence from the Jerusalem church authority and to demonstrate God's alternative economy against the exploitative system of the Roman Empire.
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- 2023
21. Low CtBP2 expression is associated with a stem cell-like signature and adverse clinical outcome in childhood B-cell lymphoblastic leukemia
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Sejong, Chun, Hyun-Young, Kim, Hee-Jin, Kim, Hong Hoe, Koo, Keon Hee, Yoo, Sun-Hee, Kim, Mi, Zhou, Seung-Tae, Lee, and Joseph L, Wiemels
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Adult ,Male ,Adolescent ,Infant ,Prognosis ,Survival Rate ,Alcohol Oxidoreductases ,Young Adult ,Child, Preschool ,Precursor B-Cell Lymphoblastic Leukemia-Lymphoma ,Antineoplastic Combined Chemotherapy Protocols ,Biomarkers, Tumor ,Neoplastic Stem Cells ,Humans ,Female ,Child ,Co-Repressor Proteins ,Follow-Up Studies - Published
- 2020
22. Uncertainty Evaluation of Flow Meter Calibration by Gravimetric Water Flow Standards at KRISS
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Byung-Ro Yoon and Sejong Chun
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Water flow ,Calibration ,Environmental science ,Gravimetric analysis ,Flow measurement ,Remote sensing - Abstract
Petrochemical and electric power plants are using flow meters, of which capacity is larger than 1000 m3/h. They require the accuracy of flow meters better than ±0.3% if the flow meters are being used for custody transfer or allocation measurement. However, the number of national metrology institutes, which can handle this issue, is very limited, including PTB (Germany), NMIJ/AIST (Japan), MIKES (Finland), CEESI-NIST (USA), and TÜV-NEL (UK). Large-capacity flow measurement standards are also needed to make better quality control for process engineering in the Republic of Korea. This study aims at establishing the water flow measurement standards up to 2000 m3/h with uncertainty better than 0.06%. How to evaluate the measurement uncertainty is discussed for establishing the large-capacity water flow standards at KRISS.
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- 2020
23. Flow Measurement With a Helical Strake Type Thermowell in Flow Measurement Standard Systems
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Sejong Chun, Sibok Lee, and Kisung Kim
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Vibration ,Pressure measurement ,Materials science ,law ,Mechanics ,Strake ,Thermowell ,Flow measurement ,Kármán vortex street ,law.invention - Abstract
Helical strake type thermowells are replacing standard thermowells according to ASME PTC 19.3 TW-2016 in various industrial sectors. It is because the helical strakes can suppress the flow-induced vibration by Kármán vortex street over a thermowell. However, the ASME PTC 19.3 TW-2016 does not regulate the helical strakes because their design rules are too complicated to be specified. This study attempts to characterize the effect of helical strakes on the thermowell vibrations by measuring pressure and strain signals at the same time. The pressure signal is expected to give information on the Kármán vortex street while the strain signal gives the flow-induced vibration on the thermowells. Relative vibration energy or relative vibration amplitude is defined to calculate the efficiency of suppressing the Kármán vortex street around the thermowells.
- Published
- 2020
24. A new<scp>RHD</scp>variant allele (<scp>RHDGly339Val</scp>) shows weakened D expression compared to<scp>RHDGly339Glu</scp>and<scp>Gly339Arg</scp>mutants
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Ho-Jin Lee, Duck Cho, and Sejong Chun
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Genetics ,Rh-Hr Blood-Group System ,Amino Acid Substitution ,Gene Expression Regulation ,Immunology ,Mutant ,Mutation, Missense ,Humans ,Immunology and Allergy ,Hematology ,Variant allele ,Biology ,Alleles - Published
- 2020
25. Performance Evaluation of VITEK MS for the Identification of a Wide Spectrum of Clinically Relevant Filamentous Fungi Using a Korean Collection
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Jun Hyung Lee, Soo Hyun Kim, Myung Geun Shin, Ju Hyeon Shin, Sejong Chun, Hyun-Jung Choi, Hyun-Woo Choi, Eun Jeong Won, Seung-Jung Kee, Seung Yeob Lee, Jong Hee Shin, and Dain Lee
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0301 basic medicine ,Identification ,Filamentous fungi ,Dermatophytes ,Performance ,030106 microbiology ,Clinical Biochemistry ,VITEK MS ,Brief Communication ,Microbiology ,Identification rate ,03 medical and health sciences ,Republic of Korea ,Humans ,Evaluation ,Aspergillus ,biology ,Mass spectrometry ,Biochemistry (medical) ,Fungi ,General Medicine ,biology.organism_classification ,Multiple species ,Clinical Microbiology ,030104 developmental biology ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Identification (biology) - Abstract
The correct identification of filamentous fungi is challenging. We evaluated the performance of the VITEK MS v3.0 system (bioMerieux, Marcy-l'Etoile, France) for the identification of a wide spectrum of clinically relevant filamentous fungi using a Korean collection. Strains that were added to the upgraded v3.2 database were additionally identified by the VITEK MS v3.2 system. Of the 105 tested isolates, including 37 Aspergillus (nine species), 41 dermatophytes (seven species), and 27 other molds (17 species), 43 (41.0%) showed "no identification" or "multiple species identification" results at the initial VITEK MS testing; these isolates were retested using the same method. Compared with sequence-based identification, the correct identification rate using VITEK MS for Aspergillus, dermatophytes, other molds, and total mold isolates was 67.6%, 56.1%, 48.1%, and 58.1% at the initial testing and 94.6%, 78.0%, 55.6%, and 78.1% with retesting, respectively. Following retesting, 19 (18.1%) and two (1.9%) isolates showed "no identification" and "misidentification" results, respectively. VITEK MS reliably identified various filamentous fungi recovered in Korea, with a very low rate of misidentification.
- Published
- 2020
26. Final report of the APMP water flow supplementary comparison (APMP.M.FF-S1)
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Sejong Chun and Noriyuki Furuichi
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General Engineering - Abstract
Main text A supplementary comparison, entitled as APMP.M.FF-S1, has been undertaken between KRISS and NMIJ, AIST under the supervision by the Technical Committee for Fluid Flow (TCFF) in the Asia Pacific Metrology Programme (APMP). The purpose of this supplementary comparison was to prove the measurement equivalence between NMIJ, AIST and KRISS for water flow measurement standards from 300 m3/h to 1 200 m3/h. This supplementary comparison was meaningful because there has not been an international comparison for water flows greater than 300 m3/h. Previous key comparisons have been performed only from 30 m3/h to 200 m3/h [1]. Therefore, this supplementary comparison became the first inter-laboratory comparison to cover the flow range for large-capacity water flow measurement standards. In fact, the inter-laboratory comparison between NMIJ, AIST and PTB (Berlin) has been already done for such flowrate range [2], however, this inter-laboratory comparison has not been supervised by APMP or EURAMET, such that the result of inter-laboratory comparison is published in a research journal, not in the BIPM KCDB for inter-laboratory comparisons. A turbine flow meter with the pipe diameter of 250 mm was chosen as a transfer standard in this supplementary comparison. A flow conditioner was used to define inflow conditions upstream of the turbine flow meter. The flow conditioner was a perforated plate with a well-known design. The turbine flow meter was calibrated in two ways: with or without the flow conditioner. The calibration of turbine flow meter with the flow conditioner was according to the revised test protocol for this supplementary comparison. The other calibration without the flow conditioner was performed to investigate the flow characteristics of the turbine flow meter. K-factor was the measurand to evaluate the measurement equivalence between NMIJ, AIST and KRISS. The K-factor was corrected by considering the temperature change between the water temperature and the reference temperature of 20 oC [3]. The measurement uncertainty of the K-factor included uncertainty factors such as repeatability, day-to-day reproducibility, re-installation effect, long-term stability, and the influence by temperature change. Inconclusiveness test was also performed to see whether the K-factor was suitable for evaluating the number of equivalence between NMIJ, AIST and KRISS. The number of equivalence was found to be less than 1. The number of equivalence became better in the case without the flow conditioner than the case with the flow conditioner. The number of equivalence was found to be conclusive because the inconclusiveness index was less than 2. Therefore, the measurement equivalence between NMIJ, AIST and KRISS has been proven by this supplementary comparison. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
- Published
- 2022
27. An Experience of Various Pretransfusion Test Protocols in a Tertiary Referral Hospital
- Author
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Duck Cho, Sooin Choi, Sejong Chun, HongBi Yu, Ji Young Seo, and Sunghwan Shin
- Subjects
03 medical and health sciences ,medicine.medical_specialty ,0302 clinical medicine ,business.industry ,030220 oncology & carcinogenesis ,Emergency medicine ,medicine ,030204 cardiovascular system & hematology ,business ,Tertiary referral hospital ,Massive transfusion ,Test (assessment) - Published
- 2018
28. ABO Mistyping of cis-AB Blood Group by the Automated Microplate Technique
- Author
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Mi Ra Ryu, Seung-Yeon Cha, Sejong Chun, Duck Cho, and Ji Young Seo
- Subjects
congenital, hereditary, and neonatal diseases and abnormalities ,030213 general clinical medicine ,medicine.medical_specialty ,business.industry ,Hematology ,Cis AB ,030204 cardiovascular system & hematology ,Abo gene ,Gastroenterology ,biological factors ,03 medical and health sciences ,0302 clinical medicine ,hemic and lymphatic diseases ,ABO blood group system ,Internal medicine ,parasitic diseases ,Immunology and Allergy ,Medicine ,Allele ,business ,Genotyping - Abstract
Background: The cis-AB phenotype, although rare, is the relatively most frequent of ABO subgroups in Koreans. To prevent ABO mistyping of cis-AB samples, our hospital has applied a combination of the manual tile method with automated devices. Herein, we report cases of ABO mistyping detected by the combination testing system. Methods: Cases that showed discrepant results by automated devices and the manual tile method were evaluated. These samples were also tested by the standard tube method. The automated devices used in this study were a QWALYS-3 and Galileo NEO. Exons 6 and 7 of the ABO gene were sequenced. Results: 13 cases that had the cis-AB allele showed results suggestive of the cis-AB subgroup by manual methods, but were interpreted as AB by either automated device. This happened in 87.5% of these cases by QWALYS-3 and 70.0% by Galileo NEO. Genotyping results showed that 12 cases were ABO*cis-AB01/ABO*O01 or ABO*cis-AB01/ABO*O02, and one case was ABO*cis-AB01/ ABO*A102. Conclusion: Cis-AB samples were mistyped as AB by the automated microplate technique in some cases. We suggest that the manual tile method can be a simple supplemental test for the detection of the cis-AB phenotype, especially in countries with relatively high cis-AB prevalence.
- Published
- 2018
29. Planned Transfusion of D-Positive Blood Components in an Asia Type DEL Patient: Proposed Modification of the Korean National Guidelines for Blood Transfusion
- Author
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Ji Hyuk Yang, Sejong Chun, Ji Young Seo, Duck Cho, and Sooin Choi
- Subjects
Tachycardia ,medicine.medical_specialty ,Blood transfusion ,Transfusion Medicine ,business.industry ,medicine.medical_treatment ,Biochemistry (medical) ,Clinical Biochemistry ,MEDLINE ,General Medicine ,Platelet transfusion ,Internal medicine ,medicine ,medicine.symptom ,business ,Letter to the Editor - Published
- 2019
30. Identification of Anti-G in Pregnant Women with RhD Negative Blood: The First Case in Korea
- Author
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Duck Cho, Ji Young Seo, Sun Joo Yoon, Sooin Choi, Soo-young Oh, and Sejong Chun
- Subjects
03 medical and health sciences ,0302 clinical medicine ,business.industry ,Immunology ,RhD negative ,Medicine ,Identification (biology) ,030204 cardiovascular system & hematology ,business ,030215 immunology - Published
- 2017
31. Proficiency Test of Water Flow Rate for Measurement Equivalence Among KOLAS Accredited Laboratories
- Author
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Soo-Jin Kim, Sejong Chun, and Byung-Ro Yoon
- Subjects
Water flow ,Statistics ,Proficiency test ,Equivalence (measure theory) ,Mathematics - Published
- 2017
32. Interference of Unexpected Antibody Detection Test in Patients Administering Daratumumab
- Author
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Ji Young Seo, Sejong Chun, Sunghwan Shin, Eun Hye Cho, Duck Cho, Sooin Choi, and Eun Young Kim
- Subjects
03 medical and health sciences ,0302 clinical medicine ,business.industry ,Immunology ,Daratumumab ,Medicine ,In patient ,030204 cardiovascular system & hematology ,business ,Interference (genetic) ,030215 immunology ,Antibody detection - Published
- 2017
33. Water flow meter calibration with a master meter method
- Author
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Sejong Chun, Byung-Ro Yoon, Hae-Man Choi, and Yong Bong Lee
- Subjects
Engineering ,Measure (data warehouse) ,Water flow ,business.industry ,Mechanical Engineering ,020208 electrical & electronic engineering ,Flow (psychology) ,Mechanical engineering ,02 engineering and technology ,Gas meter prover ,01 natural sciences ,Industrial and Manufacturing Engineering ,Flow measurement ,010309 optics ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Calibration ,Metre ,Measurement uncertainty ,Electrical and Electronic Engineering ,business ,Simulation - Abstract
Master meter method is an efficient way to calibrate flow meters with less time and costs. The master meter method has simpler flow configuration than the gravimetric flow measurement method requires. Maintenance efforts of the master meter method are easier than the gravimetric method. However, the guidelines of master meter method have not been established completely. It is because the notion of relative deviations, which are used as a measure and for comparison calibration, is not clearly understood. On the other hand, the system uncertainty, which is typically used as the calibration and measurement capability of the gravimetric flow standards, are understood very well. In this study, a complete explanation on the master meter method is attempted. First, appropriate calibration conditions are assumed. Second, a suitable calibration procedure is suggested. Third, a mathematical model for the relative deviations is described. Fourth, uncertainty factors of the relative deviations are evaluated. Finally, two examples of the comparison calibration are explained in detail. The master meter method is compatible with the guide to the expression of uncertainty in measurement (GUM, ISO/IEC Guide 98-3:2008). In the examples, it is found that the master meter method can achieve the measurement uncertainty as low as 0.20%.
- Published
- 2017
34. Anti-LW Showing Anti-D Mimicking Specificity: A Case Report
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Ji Young Seo, Duck Cho, Sunghwan Shin, Sejong Chun, and Sooin Choi
- Subjects
03 medical and health sciences ,0302 clinical medicine ,business.industry ,Medicine ,030204 cardiovascular system & hematology ,business ,030215 immunology - Published
- 2017
35. Implementation of unscented transform to estimate the uncertainty of a liquid flow standard system
- Author
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Byung-Ro Yoon, Sejong Chun, Hae-Man Choi, and Woong Kang
- Subjects
Mathematical optimization ,Engineering ,Ideal (set theory) ,business.industry ,Mechanical Engineering ,Monte Carlo method ,01 natural sciences ,Expression (mathematics) ,010309 optics ,Operator (computer programming) ,Mechanics of Materials ,Completeness (order theory) ,0103 physical sciences ,Measurement uncertainty ,Partial derivative ,Unscented transform ,010306 general physics ,business - Abstract
First-order partial derivatives of a mathematical model are an essential part of evaluating the measurement uncertainty of a liquid flow standard system according to the Guide to the expression of uncertainty in measurement (GUM). Although the GUM provides a straight-forward method to evaluate the measurement uncertainty of volume flow rate, the first-order partial derivatives can be complicated. The mathematical model of volume flow rate in a liquid flow standard system has a cross-correlation between liquid density and buoyancy correction factor. This cross-correlation can make derivation of the first-order partial derivatives difficult. Monte Carlo simulation can be used as an alternative method to circumvent the difficulty in partial derivation. However, the Monte Carlo simulation requires large computational resources for a correct simulation because it considers the completeness issue whether an ideal or a real operator conducts an experiment to evaluate the measurement uncertainty. Thus, the Monte Carlo simulation needs a large number of samples to ensure that the uncertainty evaluation is as close to the GUM as possible. Unscented transform can alleviate this problem because unscented transform can be regarded as a Monte Carlo simulation with an infinite number of samples. This idea means that unscented transform considers the uncertainty evaluation with respect to the ideal operator. Thus, unscented transform can evaluate the measurement uncertainty the same as the uncertainty that the GUM provides.
- Published
- 2017
36. Double-filtered leukoreduction as a method for risk reduction of transfusion-associated graft-versus-host disease
- Author
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Jaehyun Kim, Mark H. Yazer, Saetbyul Hong, Jehoon Yang, Sejong Chun, Minh-Trang Thi Phan, Sangbin Han, Yeup Yoon, Duck Cho, and Jungwon Kang
- Subjects
Blood transfusion ,Physiology ,medicine.medical_treatment ,T-Lymphocytes ,Graft vs Host Disease ,030204 cardiovascular system & hematology ,Dynabeads ,Leukocyte Count ,White Blood Cells ,0302 clinical medicine ,Blood product ,Mice, Inbred NOD ,Animal Cells ,Specimen Storage ,Blood plasma ,Medicine and Health Sciences ,Medicine ,Cells, Cultured ,Multidisciplinary ,T Cells ,Animal Models ,Hematology ,Clinical Laboratory Sciences ,Body Fluids ,Separation Processes ,Leukoreduction ,medicine.anatomical_structure ,Blood ,Experimental Organism Systems ,Anatomy ,Cellular Types ,Research Article ,T cell ,Science ,Immune Cells ,Immunology ,Mouse Models ,Research and Analysis Methods ,Peripheral blood mononuclear cell ,Blood Plasma ,Transfusion-associated graft versus host disease ,Andrology ,03 medical and health sciences ,Model Organisms ,Diagnostic Medicine ,Animals ,Humans ,Blood Transfusion ,Cell Proliferation ,Inflammation ,Blood Cells ,business.industry ,Transfusion Medicine ,Reproducibility of Results ,Biology and Life Sciences ,Cell Biology ,medicine.disease ,Disease Models, Animal ,Storage and Handling ,Animal Studies ,business ,Risk Reduction Behavior ,Filtration ,030215 immunology - Abstract
BackgroundTransfusion-associated graft-versus-host disease (TA-GvHD) is caused by leukocytes, specifically T cells within a transfused blood product. Currently, the prevention of transfusion-associated graft-versus-host disease is performed by irradiation of blood products. With a sufficient reduction of leukocytes, the risk for TA-GvHD can be decreased. With consistent advances in current state-of-the-art blood filters, we herein propose that double filtration can sufficiently reduce leukocytes to reduce the risk for TA-GvHD.MaterialsThirty RBC concentrates were filtered with leukocyte filters, followed by storage at 1-6 oC for 72 hours, and then a second filtration was performed. Residual leukocytes in the double-filtered RBC units (n = 30) were assessed with flow cytometric methods, and an additional assay with isolated peripheral blood mononuclear cells (PBMCs) (n = 6) was done by both flow cytometric methods and an automated hematology analyzer. Quality of the RBCs after filtration was evaluated by hematological and biochemical tests. In vitro T cell expansion was performed using anti-CD3/CD28-coated Dynabeads or anti-CD3 (OKT3). In vivo experiment for GvHD was performed by using NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice.ResultsDouble-filtered blood products showed residual leukocyte levels below detection limits, which calculated to be below 1200-2500 cells per blood unit. In vitro expansion rate of T cells showed that 6x103 and 1x103 cell-seeded specimens showed 60.8±10.6 fold and 10.2±9.7-fold expansion, respectively. Cell expansion was not sufficiently observed in wells planted with 1x102 or 10 cells. In vivo experiments showed that mice injected with 1x105 or more cells cause fatal GvHD. GvHD induced inflammation was observed in mice injected with 1x104 or more cells. No evidence of GvHD was found in mice injected with 103 cells.ConclusionsOur study suggests that additional removal of contaminating lymphocytes by a second leukodepletion step may further reduce the risk for TA-GvHD.
- Published
- 2019
37. A Novel Type of Blood Biomarker: Distinct Changes of Cytokine-Induced STAT Phosphorylation in Blood T Cells Between Colorectal Cancer Patients and Healthy Individuals
- Author
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Hee Cheol Kim, Sejong Chun, Hye Mi Kim, Jae Won Yun, Sejoon Lee, Eun Suk Kang, and Edgar G. Engleman
- Subjects
0301 basic medicine ,Oncology ,Cancer Research ,medicine.medical_specialty ,Colorectal cancer ,medicine.medical_treatment ,colorectal cancer ,lcsh:RC254-282 ,stat ,Article ,03 medical and health sciences ,0302 clinical medicine ,Immune system ,Immunophenotyping ,Internal medicine ,medicine ,Liquid biopsy ,STAT transcription factors ,neoplasms ,liquid biopsy ,Tumor-infiltrating lymphocytes ,business.industry ,medicine.disease ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,digestive system diseases ,cytokines ,030104 developmental biology ,Cytokine ,tumor infiltrating lymphocytes ,030220 oncology & carcinogenesis ,Cohort ,business - Abstract
Background: Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Although early diagnosis and treatment is the most successful strategy for improving patient survival, feasible and sensitive blood biomarkers for CRC screening remain elusive. Methods: Sixty-five CRC patients and thirty-three healthy individuals were enrolled. Peripheral blood (PB) and tumor tissues from CRC patients, and PB from healthy individuals were subjected to immunophenotyping and phospho-flow analysis of cytokine-induced phosphorylated STAT (CIPS). Logistic regression was used as a classifier that separates CRC patients from healthy individuals. Results: The proportion of regulatory T cells was increased in PB from CRC patients compared to PB from healthy individuals (p <, 0.05). Interestingly, peripheral T cells share several cytokine-induced phosphorylated STAT (CIPS) signatures with T cells from CRC tumor-sites. Additionally, a classifier was made using two signatures distinct between T cells from CRC patients and T cells from healthy individuals. The AUCs (area under curves) of the classifier were 0.88 in initial cohort and 0.94 in the additional validation cohort. Overall AUC was 0.94 with sensitivity of 91% and specificity of 88%. Conclusion: This study highlights that immune cell signatures in peripheral blood could offer a new type of biomarker for CRC screening.
- Published
- 2019
- Full Text
- View/download PDF
38. Development of a Surface Flow Sensor for Measuring Turbulent Drag Force
- Author
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Ji-Ho Chang, Sejong Chun, Il-Bum Kwon, and Il Doh
- Subjects
Surface (mathematics) ,Materials science ,Turbulence ,Drag ,Development (differential geometry) ,Flow sensor ,Mechanics - Abstract
A surface flow sensor is needed if turbulent drag force is to be measured over a vehicle, such as a car, a ship, and an airplane. In case of automobile industry, there are no automobile manufacturers which measure surface flow velocity over a car for wind tunnel testing. Instead, they rely on particle image velocimetry (PIV), pressure sensitive paint (PSP), laser Doppler anemometry (LDA), pitot tubes, and tufts to get information regarding the turbulent drag force. Surface flow sensors have not devised yet. This study aims at developing a surface flow sensor for measuring turbulent drag force over a rigid body in a wind tunnel. Two sensing schemes were designed for the fiber-optic distributed sensor and the thermal mass flow sensor. These concepts are introduced in this paper. As the first attempt, a thermal mass flow sensor has been fabricated. It was flush-mounted on the surface of a test section in the wind tunnel to measure the surface flow velocity. The thermal mass flow sensor was operated by either constant current or constant resistance modes. Resistance ratio was changed as the electric current was increased by the constant current mode, while power ratio was saturated as the resistance was increased by the constant resistance mode. Either the resistance ratio or the power ratio was changed with the flow velocity measured by a Pitot tube, located at the center of test section.
- Published
- 2019
39. Clinical significance of isolates known for being a blood culture contaminant: a study on the pediatric population
- Author
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Sejong Chun
- Abstract
Clinical significance of isolates known for being a blood culture contaminant: a study on the pediatric population
- Published
- 2019
- Full Text
- View/download PDF
40. RHD genotyping is recommended for all patients with serological weak-D phenotypes in Asian populations - Cases with coexistence of weak-D and Asia type DEL alleles results in complete expression of D-antigen
- Author
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Hyungsuk Kim, Ji Young Seo, Duck Cho, Sejong Chun, HongBi Yu, and Jae Won Yun
- Subjects
Male ,Genotyping Techniques ,Rho(D) Immune Globulin ,030204 cardiovascular system & hematology ,Biology ,Epitope ,Rho(D) immune globulin ,Serology ,03 medical and health sciences ,0302 clinical medicine ,Antigen ,Asian People ,medicine ,Humans ,Allele ,Genotyping ,Genetics ,Rh-Hr Blood-Group System ,Hematology ,Middle Aged ,Phenotype ,biology.protein ,Blood Group Antigens ,Antibody ,030215 immunology ,medicine.drug - Abstract
Weak D types 1, 2, 3 and Asia type DEL (RHD 1227 G > A) can be treated as D-positive for purposes of Rho(D) immune globulin (RhIG) administration or selection of blood components for transfusion. To confirm these D variants, RHD genotyping can be used as a complementary to serologic tests. While ruling out weak D types 1,2,3 is useful in Caucasian populations, these are extremely rare in the Asian population, while Asia type DEL is relatively common. Distinguishing between true D-negative and Asia type DEL (RHD 1227 G > A) by genotyping has the same utility of distinguishing weak D types 1, 2, 3. The main difference between weak D and Asia type DEL is that the latter appears as D negative in conventional serologic methods, while the former will show positive in indirect anti-human immunoglobulin tests. RHD genotyping in apparent D-negative Asian patients has been established, yet the utility of genotyping in Asian patients with weakened D phenotypes require further investigation. We have observed cases of weak D patients with coexistence of a weak D allele and an Asia type DEL (RHD 1227 G > A) allele, we have found that antigen expression of D is as the weak D in indirect antiglobulin testing, yet all epitopes are detected with adsorption and elution assays. This is indicative of completeness of the D antigen epitope, and thus we suggest that all Asian patients with weakened D phenotypes can benefit from RHD genotyping.
- Published
- 2019
41. Candida auris Clinical Isolates from South Korea: Identification, Antifungal Susceptibility, and Genotyping
- Author
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Jun Hyung Lee, Hyun-Jung Choi, Seung A Byun, Sejong Chun, Seung-Jung Kee, Yong Jun Kwon, Soo Hyun Kim, Myung Geun Shin, Seung Yeob Lee, Dain Lee, Jong Hee Shin, Eun Jeong Won, and Min Ji Choi
- Subjects
0301 basic medicine ,Microbiology (medical) ,Antifungal ,Antifungal Agents ,Echinocandin ,Genotype ,medicine.drug_class ,030106 microbiology ,Mycology ,Microbial Sensitivity Tests ,Biology ,Microbiology ,Fungal Proteins ,03 medical and health sciences ,Drug Resistance, Multiple, Fungal ,Republic of Korea ,medicine ,Pulsed-field gel electrophoresis ,Humans ,Mycological Typing Techniques ,Genotyping ,Candida ,Candidiasis ,bacterial infections and mycoses ,Hospitals ,Multiple drug resistance ,030104 developmental biology ,Candida auris ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Multilocus sequence typing ,Fluconazole ,medicine.drug ,Multilocus Sequence Typing - Abstract
Candida auris is an emerging worldwide fungal pathogen. Over the past 20 years, 61 patient isolates of C. auris (4 blood and 57 ear) have been obtained from 13 hospitals in Korea. Here, we reanalyzed those molecularly identified isolates using two matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) systems, including Biotyper and Vitek MS, followed by antifungal susceptibility testing, sequencing of the ERG11 gene, and genotyping. With a research-use-only (RUO) library, 83.6% and 93.4% of the isolates were correctly identified by Biotyper and Vitek MS, respectively. Using an in vitro diagnostic (IVD) library of Vitek MS, 96.7% of the isolates were correctly identified. Fluconazole-resistant isolates made up 62.3% of the isolates, while echinocandin- or multidrug-resistant isolates were not found. Excellent essential (within two dilutions, 96.7%) and categorical agreements (93.4%) between the Clinical and Laboratory Standards Institute (CLSI) and Vitek 2 (AST-YS07 card) methods were observed for fluconazole. Sequencing ERG11 for all 61 isolates revealed that only 3 fluconazole-resistant isolates showed the Erg11p amino acid substitution K143R. All 61 isolates showed identical multilocus sequence typing (MLST). Pulsed-field gel electrophoresis (PFGE) analyses revealed that both blood and ear isolates had the same or similar patterns. These results show that MALDI-TOF MS and Vitek 2 antifungal susceptibility systems can be reliable diagnostic tools for testing C. auris isolates from Korean hospitals. The Erg11p mutation was seldom found among Korean isolates of C. auris, and multidrug resistance was not found. Both MLST and PFGE analyses suggest that these isolates are genetically similar.
- Published
- 2019
42. Expansion of Human NK Cells Using K562 Cells Expressing OX40 Ligand and Short Exposure to IL-21
- Author
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SoonHo Kweon, Minh-Trang Thi Phan, Sejong Chun, HongBi Yu, Jinho Kim, Seokho Kim, Jaemin Lee, Alaa Kassim Ali, Seung-Hwan Lee, Sang-Ki Kim, Junsang Doh, and Duck Cho
- Subjects
lcsh:Immunologic diseases. Allergy ,0301 basic medicine ,Adoptive cell transfer ,medicine.medical_treatment ,Cell ,Immunology ,Gene Expression ,OX40 Ligand ,Lymphocyte Activation ,Immunophenotyping ,03 medical and health sciences ,0302 clinical medicine ,expansion ,IL-21 ,medicine ,Immunology and Allergy ,Humans ,education ,Original Research ,Cell Proliferation ,Antibody-dependent cell-mediated cytotoxicity ,education.field_of_study ,natural killer cells ,Chemistry ,Interleukins ,Degranulation ,Antibody-Dependent Cell Cytotoxicity ,Receptors, OX40 ,Coculture Techniques ,Cell biology ,OX40 ligand ,Killer Cells, Natural ,030104 developmental biology ,Cytokine ,medicine.anatomical_structure ,Cytokines ,Cytokine secretion ,K562 ,lcsh:RC581-607 ,Genetic Engineering ,K562 Cells ,Biomarkers ,030215 immunology ,K562 cells - Abstract
Background: Natural Killer (NK) cell-based immunotherapy used to treat cancer requires the adoptive transfer of a large number of activated NK cells. Here, we report a new effective method to expand human NK cells ex vivo using K562 cells genetically engineered (GE) to express OX40 ligand (K562-OX40L) in combination with a short exposure to soluble IL-21. In addition, we describe a possible mechanism of the NK cell expansion through the OX40 receptor-OX40 ligand axis which is dependent on NK cell homotypic interaction. Methods: K562-OX40L cells were generated by lentiviral transduction and were used as feeder cells to expand and activate NK cells from PBMCs in the presence of IL-2/IL-15. Soluble IL-21 was also added in various concentrations only once at the beginning of the culture. NK cells were expanded for 4-5 weeks, and the purity, expansion rate, phenotype and function (cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC), cytokine production, CD107a degranulation) of these expanded NK cells were compared to those generated by using K562 feeder cells. Results: The culture of NK cells with K562-OX40L cells in combination with the transient exposure to IL-21 highly enhanced NK cell expansion to approximately 2,000-fold after 4 weeks of culture, compared to a 303-fold expansion using the conventional K562 cells. Mechanistically, the OX40-OX40L axis between the feeder cells and NK cells as well as the homotypic interaction between NK cells through the OX40-OX40L axis were both necessary for NK cell expansion. The short exposure of NK cells to IL-21 had a synergistic effect with OX40 signaling for NK cell expansion. Apart from their enhanced expansion, NK cells grown with K562-OX40L feeder cells were similar to those grown with conventional K562 cells in regard to the surface expression of various receptors, cytotoxicity, ADCC, cytokine secretion, and CD107 degranulation. Conclusion: Our data suggest that OX40 ligand is a potent co-stimulant for the robust expansion of human NK cells and the homotypic NK cell interactions through the OX40-OX40L axis is a mechanism of NK cell expansion.
- Published
- 2018
43. Dynamic Performance Evaluation of Blood Flow Simulator Based on Windkessel Models
- Author
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Jonghan Jin and Sejong Chun
- Subjects
03 medical and health sciences ,0302 clinical medicine ,Computer science ,Mechanical Engineering ,0103 physical sciences ,Blood flow ,030204 cardiovascular system & hematology ,Safety, Risk, Reliability and Quality ,01 natural sciences ,Industrial and Manufacturing Engineering ,Simulation ,010305 fluids & plasmas - Published
- 2016
44. Evaluation of alpha-fetoprotein as a screening marker for hepatocellular carcinoma in hepatitis prevalent areas
- Author
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Jee Eun Kim, Chang-Seok Ki, Hyung-Doo Park, Sejong Chun, and Su Yeon Rhie
- Subjects
medicine.medical_specialty ,HBsAg ,Carcinoma, Hepatocellular ,Hepatocellular carcinoma ,Population ,Specialties of internal medicine ,Gastroenterology ,Predictive Value of Tests ,Internal medicine ,Republic of Korea ,Prevalence ,medicine ,Humans ,education ,Early Detection of Cancer ,Aged ,Aged, 80 and over ,Hepatitis ,education.field_of_study ,Hepatology ,business.industry ,Liver Neoplasms ,Reproducibility of Results ,General Medicine ,Hepatitis C ,Middle Aged ,Hepatitis B ,medicine.disease ,digestive system diseases ,ROC Curve ,RC581-951 ,Area Under Curve ,Alpha-fetoprotein ,Predictive value of tests ,Immunology ,Screening ,alpha-Fetoproteins ,Liver cancer ,business - Abstract
The objective of this study was to establish modified cutoff values of serum alpha-fetoprotein (AFP) according to hepatitis status. While AFP is used as a serum marker in the diagnosis or monitoring of hepatocellular carcinoma (HCC), its use as a screening method to the general population is controversial. We evaluated its screening performance in a hepatitis prevalent East Asian population, and suggest different cutoff values according to the individual's hepatitis status. We evaluated the performance of AFP as a screening test in 48,123 consecutive Koreans during the period from March, 2012 to August, 2013 who underwent routine health checks at a single institution. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated with fixed cutoff and with modified cutoffs according the individual's hepatitis status. A total of 24 out of 48,123 subject (0.05%) were newly diagnosed with HCC after screening. Among the 1,874 subject with positive hepatitis B virus surface antigen (HBsAg), 17 (0.91%) developed HCC, compared with two out of 393 (0.51%) individuals with hepatitis C virus antibody (anti-HCV). Five out of 45,855 (0.01%) subject with neither HBsAg nor anti-HCV developed HCC. Compared to the performance of a fixed cutoff, specificity, PPV, and NPV improved without sacrificing sensitivity when applying modified cutoff. In conclusion, our findings suggest that AFP with modified cutoffs according to the individual's hepatitis status might be a useful screening marker for HCC in hepatitis prevalent areas.
- Published
- 2015
45. Diverse Phenotypes of Cis-AB Blood Group and Transfusion Strategy
- Author
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Duck Cho, Chun Hee Lee, Sejong Chun, and Min-Seung Park
- Subjects
03 medical and health sciences ,0302 clinical medicine ,Immunology ,Cis AB ,030204 cardiovascular system & hematology ,Biology ,Phenotype ,030215 immunology - Published
- 2016
46. X-ray as Irradiation Alternative for K562 Feeder Cell Inactivation in Human Natural Killer Cell Expansion
- Author
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Duck Cho, Soon Ho Kweon, Hoang-Nguyen Dang, Sejong Chun, Gwang Ho Kim, and Minh-Trang Thi Phan
- Subjects
Cancer Research ,medicine.diagnostic_test ,Chemistry ,Receptor expression ,X-Rays ,Feeder Cells ,Cell Differentiation ,General Medicine ,Molecular biology ,Peripheral blood mononuclear cell ,Coculture Techniques ,Natural killer cell ,Flow cytometry ,Killer Cells, Natural ,Cell expansion ,medicine.anatomical_structure ,Oncology ,Feeder Cell ,medicine ,Humans ,Irradiation ,K562 Cells ,K562 cells ,Cell Proliferation - Abstract
Background/aim γ-Irradiation has been proven to be the most effective method to inactivate K562 cells, but γ-irradiators are not available in some institutes. This study was designed to compare the effects of X-ray and γ-irradiation on K562 cells in natural killer (NK) cell expansion. Materials and methods To expand NK cells, isolated peripheral blood mononuclear cells (PBMCs) were co-cultured with γ-irradiated or X-ray-treated K562 cells plus IL-2 and IL-15. Characteristics of expanded NK cells were identified by flow cytometry. Results NK cell expansion rate tended be to lower in the X-ray-treated group (68.9±32.6) than the γ-irradiated group (78±28.7), but the difference was not significant (p=0.39). Furthermore, NK cell functions or receptor expression were similar in the two groups. Conclusion Our results suggest that X-ray treatment can be used as an alternative to γ-irradiation for K562 cells inactivation in human NK cell expansion.
- Published
- 2018
47. The first case of congenital blood chimerism in two of the triplets in Korea
- Author
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Sejong Chun, Ji Seon Choi, Duck Cho, Myung Hyun Nam, Yoo Na Chung, Minh-Trang Thi Phan, and Byung Min Choi
- Subjects
Microbiology (medical) ,medicine.drug_class ,Clinical Biochemistry ,030204 cardiovascular system & hematology ,Biology ,Monoclonal antibody ,Chimerism ,law.invention ,ABO Blood-Group System ,03 medical and health sciences ,Chimera (genetics) ,0302 clinical medicine ,law ,ABO blood group system ,Genotype ,Republic of Korea ,medicine ,Immunology and Allergy ,Humans ,030212 general & internal medicine ,Polymerase chain reaction ,Triplets ,Direct sequencing ,Brief Report ,Biochemistry (medical) ,Public Health, Environmental and Occupational Health ,Infant, Newborn ,Hematology ,Molecular biology ,Molecular analysis ,Pedigree ,Medical Laboratory Technology ,Molecular Diagnostic Techniques - Abstract
Background Chimeras are composed of two or more different populations that originated from different zygotes. Blood chimerism arising from twins have been reported in the literature. Herein, we report the first blood group chimerism in triplets. Methods ABO blood grouping was carried out by manual tile methods (Merck Millipore, UK) and micro-column agglutination method (Bio-Rad, Cressier sur Morat, Switzerland). Flow cytometric analysis was performed with Anti-A-PE conjugated monoclonal antibodies (BD Biosciences, San Jose, CA, USA) and FACS Canto II (BD Biosciences). Molecular analysis was performed with allele-specific polymerase chain reaction (AS-PCR) and direct sequencing of the exons 6 and 7. Results Mixed-field agglutination and weak agglutination against anti-A were revealed by ABO blood grouping. Flow cytometric analysis revealed the presence of both A cells and O cells. AS-PCR and sequencing showed two neonates with chimerism, with each neonate`s genotype being A102/O01/O02. Conclusion This is the first recorded case of blood chimera from a triplet in Korea. We recommend full investigation of blood group chimerism in neonates with ABO discrepancy, as blood chimerism is subject to certain caution in the clinical environment.
- Published
- 2018
48. Reply to Aubry and Veziris: Smear Microscopy Complements Xpert MTB/RIF When Considering Nontuberculous Mycobacterial Infections
- Author
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Sejong Chun, Taeo Ma, Jong-Hee Shin, Yong Soo Kwon, Hyun-Woo Choi, Seung-Jung Kee, Ju-Hyeon Shin, Hyun Seung Lee, and Eun Jeong Won
- Subjects
Pulmonary and Respiratory Medicine ,Microscopy ,Tuberculosis ,business.industry ,Critical Care and Intensive Care Medicine ,medicine.disease ,Virology ,Smear microscopy ,Correspondence ,Tuberculosis, Multidrug-Resistant ,Medicine ,Humans ,business ,Tuberculosis, Pulmonary - Published
- 2019
49. Weak D Testing is not Required for D- Patients With C-E- Phenotype
- Author
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Hwan Tae Lee, Sejong Chun, HongBi Yu, Ji Young Seo, Sooin Choi, and Duck Cho
- Subjects
Test strategy ,Genotype ,Cost effectiveness ,D typing ,Clinical Biochemistry ,030204 cardiovascular system & hematology ,Tertiary Care Centers ,03 medical and health sciences ,0302 clinical medicine ,Humans ,Testing time ,RHD genotyping ,Mathematics ,Retrospective Studies ,Antihuman globulin ,Rh-Hr Blood-Group System ,business.industry ,Transfusion Medicine ,Biochemistry (medical) ,General Medicine ,Algorithm ,Phenotype ,Blood Grouping and Crossmatching ,Weak D testing ,030220 oncology & carcinogenesis ,C−E− phenotype ,RhD blood type ,Original Article ,Nuclear medicine ,business ,Algorithms - Abstract
BACKGROUND Although testing to detect weak D antigens using the antihuman globulin reagent is not required for D- patients in many countries, it is routinely performed in Korea. However, weak D testing can be omitted in D- patients with a C-E- phenotype as this indicates complete deletion of the RHD gene, except in rare cases. We designed a new algorithm for weak D testing, which consisted of RhCE phenotyping followed by weak D testing in C+ or E+ samples, and compared it with the current algorithm with respect to time and cost-effectiveness. METHODS In this retrospective study, 74,889 test results from January to July 2017 in a tertiary hospital in Korea were analyzed. Agreement between the current and proposed algorithms was evaluated, and total number of tests, time required for testing, and test costs were compared. With both algorithms, RHD genotyping was conducted for samples that were C+ or E+ and negative for weak D testing. RESULTS The algorithms showed perfect agreement (agreement=100%; κ=1.00). By applying the proposed algorithm, 29.56% (115/389 tests/yr) of tests could be omitted, time required for testing could be reduced by 36% (8,672/24,084 min/yr), and the test cost could be reduced by 16.53% (536.11/3,241.08 USD/yr). CONCLUSIONS Our algorithm omitting weak D testing in D- patients with C-E- phenotype may be a cost-effective testing strategy in Korea.
- Published
- 2017
50. Species-Specific Difference in Antimicrobial Susceptibility Among Viridans Group Streptococci
- Author
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Hee Jae Huh, Sejong Chun, and Nam Yong Lee
- Subjects
Viridans streptococci ,medicine.drug_class ,Resistance ,Clinical Biochemistry ,Antibiotics ,Antimicrobial susceptibility ,Microbial Sensitivity Tests ,Penicillins ,Drug resistance ,Biology ,Microbiology ,Microbial ,Antibiotic resistance ,Anti-Infective Agents ,Streptococcal Infections ,Streptococcus mitis ,Drug Resistance, Bacterial ,medicine ,Humans ,Biochemistry (medical) ,General Medicine ,Penicillin ,Antimicrobial ,biology.organism_classification ,Body Fluids ,Clinical Microbiology ,Original Article ,medicine.drug - Abstract
Background Viridans group streptococci (VGS) are both commensal microbes and potential pathogens. Increasing resistance to penicillin in VGS is an ongoing issue in the clinical environment. We investigated the difference in susceptibility and resistance to penicillin among various VGS species. Methods In total 1,448 VGS isolated from various clinical specimens were analyzed over a two-yr period. Identification and antimicrobial susceptibility test was performed by the automated VITEK 2 system (bioMerieux, France) or the MicroScan MICroSTREP system (Siemens, Germany). Results Among the 1,448 isolates, 412 were isolated from blood (28.4%). Streptococcus mitis group was the most frequently isolated (589 isolates, 40.7%), followed by the S. anginosus group (290 isolates, 20.0%), S. sanguinis group (179 isolates, 12.4%) and S. salivarius group (57 isolates, 3.9%). In total, 314 isolates could not be identified up to the species level. The overall non-susceptibility to penicillin was observed to be 40.0% (resistant, 11.2% and intermediately resistant, 28.8%) with uneven distribution among groups; 40.2% in S. sanguinis group (resistant, 5.0% and intermediately resistant, 35.2%), 60.3% in S. mitis group (resistant, 20.9% and intermediately resistant, 39.4%), 78.9% in S. salivarius group (resistant, 8.8% and intermediately resistant, 70.1%), and 6.2% in S. anginosus group (resistant, 1.7% and intermediately resistant, 4.5%). Conclusions Antimicrobial resistance patterns towards penicillin show differences among various VGS; this should be considered while devising an effective antimicrobial treatment against VGS.
- Published
- 2015
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