Brief Communication2022-05-01 Clinical Microbiology
Junhyup Song 
, M.D., Shinyoung Yoon , M.D., Yongha In , Ph.D., Daewon Kim , M.D., Hyukmin Lee , M.D., Dongeun Yong , M.D., Ph.D., and Kyoungwon Lee , M.D.
Abstract : Identifying Mycobacterium using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is challenging. We evaluated the performance of MALDI-TOF MS in identifying nontuberculous mycobacteria (NTM) using the ASTA MicroIDSys system (ASTA Inc., Suwon, Korea) with the MycoDB v1.95s and upgraded MycoDB v2.0-beta databases. We tested 124 NTM isolates collected from Ogawa medium at Severance Hospital, Seoul, Korea, between January and April 2019. MicroIDSys scores were categorized into three groups: ≥140, reliable identification; 130–139, ambiguous identification; and
Original Article2022-11-01 Clinical Chemistry
Hyunjung Gu , M.D., Ph.D., Juhee Lee , M.T., Jinyoung Hong , M.D., Woochang Lee , M.D., Ph.D., Yeo-Min Yun , M.D., Ph.D., Sail Chun , M.D., Ph.D., Woo-In Lee , M.D., Ph.D., and Won-Ki Min , M.D., Ph.D.
Abstract : Background: The top-down (TD) approach using internal quality control (IQC) data is regarded a practical method for estimating measurement uncertainty (MU) in clinical laboratories. We estimated the MU of 14 clinical chemistry analytes using the TD approach and evaluated the effect of lot changes on the MU. Methods: MU values were estimated using subgrouping by reagent lot changes or using the data as a whole, and both methods were compared. Reagent lot change was simulated using randomly generated data, and the mean values and MU for two IQC datasets (different QC material lots) were compared using statistical methods. Results: All MU values calculated using subgrouping were lower than the total values; however, the average differences were minimal. The simulation showed that the greater the increase in the extent of the average shift, the larger the difference in MU. In IQC data comparison, the mean values and MU exhibited statistically significant differences for most analytes. The MU calculation methods gave rise to minimal differences, suggesting that IQC data in clinical laboratories show no significant shift. However, the simulation results demonstrated that notable differences in the MU can arise from significant variations in IQC results before and after a reagent lot change. Additionally, IQC material lots should be treated separately when IQC data are collected for MU estimation. Conclusions: Lot changes in IQC data are a key factor affecting MU estimation and should not be overlooked during MU estimation.
Letter to the Editor2022-03-01 Diagnostic Hematology
Shinae Yu , M.D., Sae Am Song , M.D., Ph.D., Kyung Ran Jun , M.D., Ph.D., Ha Young Park , M.D., and Jeong Nyeo Lee , M.D., Ph.D.
Original Article2022-05-01 Diagnostic Genetics
Sun Joo Yoon , M.D. , Won Kyung Kwon , M.D., Ph.D., Geehay Hong , M.D., Ja-Hyun Jang , M.D., Ph.D., Byong Chang Jeong , M.D., Ph.D., Jae Hyeon Kim , M.D., Ph.D., and Jong-Won Kim , M.D., Ph.D.
Abstract : Background: von Hippel–Lindau (VHL) disease is an autosomal dominant disorder caused by variants of the VHL tumor suppressor gene (VHL). Early detection and treatment are essential to prevent morbidity and mortality. We evaluated the effectiveness of surveillance strategies and the utility of a VHL clinic with a multidisciplinary team for the first time in Korea. Methods: The VHL clinic was organized at the Samsung Medical Center in 2011 and consisted of a multidisciplinary team, including an endocrinologist, urologist, general surgeon, neurosurgeon, ophthalmologist, otolaryngologist, and radiologist. Biochemical and imaging surveillance and personalized genetic counseling were conducted at the VHL clinic and patients were referred to the necessary departments upon detection of disease manifestation. We divided the patients in three groups (I–III) based on their compliance to VHL clinic attendance. Results: Between 2011 and 2018, 50 VHL patients were identified by VHL molecular analysis and referred to the VHL clinic. Most patients regularly participated in imaging of the central nervous system (43/50, 86.0%) and of the abdomen (46/50, 92.0%). However, there were differences in compliance to determination of the catecholamine level, audiometry, and ophthalmic examination among the three groups. Conclusions: We present the results of using a multidisciplinary team approach and showed that the VHL clinic strategy is useful for the comprehensive surveillance and management of VHL disease. We hope that VHL clinics will be widely set up in hospitals to improve prognosis in patients with VHL.
Original Article2022-11-01 Transfusion and Cell Therapy
Young Ae Lim , M.D., Ph.D., Seo-Jin Park , M.D., Ph.D., and Hyun Soo Cho , M.S.
Abstract : Background: A paucity of studies evaluating failed cases of ABO grouping using autoanalyzers exists. We investigated autoanalyzer rejected cases, including serologically suspicious ABO subgroups and discrepant ABO blood grouping results from Erytra Eflexis (Grifols, Spain), to demonstrate efficient use of autoanalyzers for ABO grouping. Methods: Samples requested for ABO grouping throughout 2020 were tested using two Eflexis instruments and standard ABO RhD and reverse grouping cards. Neonatal cards were not used. When necessary, a conventional tube technique (TUBE) was used to resolve rejected/discrepant Eflexis ABO grouping results. Results: The overall sample rejection rate (RR) was 3.2% (628/19,466), 1.3% of which were due to various error flags and 1.9% for discrepant results. Cases from neonates ≤1 year old accounted for 35.3% of the rejected cases based on Eflexis results. The ABO groups with the highest and lowest RR (excluding neonates) were A and O, respectively. The 628 samples resulted in 682 rejections, which were frequently associated with reverse grouping, including 28.4% against A1 and 54.5% for B red cells. Among 14 serologically weakened A and/or B blood groups, six A2BW and two ABw, which had been missed by Eflexis, were detected using TUBE and our follow-up laboratory criteria. Conclusions: The ABO group and a proportion of neonatal samples influenced the RR due to weak reverse grouping reactivity, especially toward B red cells. Confirmatory ABO grouping by TUBE in a new patient and/or extra rejection criteria for forward grouping are needed to detect cis-AB, which is relatively common in Korea.
Original Article2022-07-01 Clinical Chemistry
Weiyan Zhou , M.D., Yuhang Deng , M.D., Haijian Zhao , M.D., and Chuanbao Zhang , M.D.
Abstract : Background: Accurate measurements of serum insulin and C-peptide are needed for the therapy and classification of diabetes. This study investigated the status of serum insulin and C-peptide measurements in China by analyzing the results of five pooled serum samples measured in 94 laboratories. Methods: Patient serum samples were pooled into five groups according to insulin and C-peptide concentrations and measured in 94 laboratories using different measurement systems. The inter- and intra-laboratory %CV as well as inter- and intra-measurement system %CV were calculated to assess the status of insulin and C-peptide measurements. To verify whether the disagreement between laboratories was due to different calibrators, as reported in previous studies, one low-level and one high-level sample extracted from the five pooled serum samples were used to recalibrate clinical measurement systems. Results: The mean intra-laboratory, intra-measurement system, inter-laboratory, and inter-measurement system %CVs were 2.7%, 4.8%, 21.8%, and 22.4%, respectively, for insulin and 2.3%, 6.7%, 16.4%, and 24.5%, respectively, for C-peptide. The inter- and intra-laboratory %CVs for insulin decreased with increasing concentration. After recalibration with low- and high-level samples, the mean inter-measurement %CV decreased from 22.4% to 17.2% for insulin and from 24.5% to 5.7% for C-peptide. Conclusions: The intra-laboratory and intra-measurement system imprecision values are satisfactory for serum insulin and C-peptide measurements. However, the results from laboratories using different measurement systems were not comparable, and there is still much work needed to achieve the standardization or harmonization of serum insulin and C-peptide measurements.
Letter to the Editor2023-03-01 Diagnostic Genetics
Jihoon G. Yoon , M.D., Ph.D., Seungbok Lee , M.D., Ph.D., Sheehyun Kim , M.D., Man Jin Kim , M.D., Ph.D., Yoon Hwan Chang , M.D., Ph.D., Jin Kyun Park , M.D., Ph.D., Dong-Yeop Shin , M.D., Ph.D., and Jangsup Moon , M.D., Ph.D.
Original Article2023-01-01 Clinical Chemistry
Sung-Eun Cho , M.D., Jungsun Han , M.S., Ju-Hee Park , B.S., Euna Park , M.T., Geun Young Kim , M.T., Jun Hyung Lee , M.D., Ahram Yi , M.D., Sang Gon Lee , M.D., Eun Hee Lee , M.D., and Yeo-Min Yun , M.D.
Abstract : Background: Mass spectrometry methods exhibit higher accuracy and lower variability than immunoassays at low testosterone concentrations. We developed and validated an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay for quantifying serum total testosterone. Methods: We used an ExionLC UPLC (Sciex, Framingham, MA, USA) system and a Sciex Triple Quad 6500+ (Sciex) MS/MS system in electrospray ionization and positive ion modes with multiple reaction monitoring transitions to evaluate precision, accuracy, linearity, lower limit of quantitation (LLOQ), carryover, ion suppression, stability, and reference intervals. For method comparison, we measured serum testosterone concentrations using this method in 40 subjects whose testosterone concentrations ranged from 0.14 to 55.48 nmol/L as determined using the Architect i2000 immunoassay (Abbott Diagnostics, Abbott Park, IL, USA) and in an additional 160 sera with testosterone concentrations
Brief Communication2022-11-01 Diagnostic Hematology
Sang Mee Hwang , M.D., Ph.D., Beom Joon Kim , M.D., Jee-Soo Lee , M.D., Moon-Woo Seong , M.D., Ph.D., Soo Hyun Seo , M.D., Ph.D., Jin Ho Paik , M.D., Ph.D., Sang-A Kim , M.D., Ji Yun Lee , M.D., Jeong-Ok Lee , M.D., Ph.D., Yoon Hwan Chang , M.D., Ph.D., and Soo Mee Bang , M.D., Ph.D.
Abstract : Systemic mastocytosis with associated hematological neoplasm (SM-AHN) poses diagnostic challenges because of the coexistence of atypical mast cell proliferation and hematological neoplasms. We assessed the presence of SM-AHN in patients with acute myeloid leukemia (AML) with RUNX1::RUNX1T1 from 2014 to 2020. Bone marrow (BM) samples were evaluated for mast cell aggregates using CD117 and CD25 immunohistochemical (IHC) staining. The KIT D816V variant burden at diagnosis and post induction was assessed using droplet digital PCR. Among 23 patients diagnosed as having AML with RUNX1::RUNX1T1, four (17.4%) were also diagnosed as having SM-AHN. No significant differences in clinical characteristics or overall survival (P=0.565) were observed between patients with or without SM-AHN, except for the presence of KIT variants (P=0.040). After induction therapy, IHC staining revealed the presence of mast cell aggregates in the BM, and the KIT D816V variant burden decreased with decreasing blast count and was similar in BM aspirates, smear slides, and sections. Concomitant SM-AHN was not infrequent in AML patients with RUNX1::RUNX1T1. This study showed the importance of CD117 and CD25 IHC staining after induction chemotherapy for SM-AHN screening, especially in patients with KIT variants.
Original Article2022-07-01 Clinical Microbiology
Hyoshim Shin , M.D., Takashi Takahashi , M.D., Ph.D., Seungjun Lee , M.D., Eun Hwa Choi , M.D., Ph.D., Takahiro Maeda , B.P., Yasuto Fukushima , B.P., and Sunjoo Kim , M.D., Ph.D.
Abstract : Background: Few studies have investigated the invasiveness of Streptococcus pyogenes based on whole-genome sequencing (WGS). Using WGS, we determined the genomic features associated with invasiveness of S. pyogenes strains in Korea. Methods: Forty-five S. pyogenes strains from 1997, 2006, and 2017, including common emm types, were selected from the repository at Gyeongsang National University Hospital in Korea. In addition, 48 S. pyogenes strains were randomly selected depending on their invasiveness between 1997 and 2017 to evaluate the genetic evolution and the associations between invasiveness and genetic profiles. Using WGS datasets, we conducted virulence-associated DNA sequence determination, emm genotyping, multi-locus sequence typing (MLST), and superantigen gene profiling. Results: In total, 87 strains were included in this study. There were no significant differences in the genomic features throughout the study periods. Four genes, csn1, ispE, nisK, and citC, were detected only in invasive strains. There was a significant association between invasiveness and emm cluster type A-C3, including, emm1.0, emm1.18, emm1.3, and emm1.76 (P
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