Evaluation of diagnostic performance of SARS-CoV-2 infection using digital droplet polymerase chain reaction in individuals with or without COVID-19 symptoms.

BACKGROUND: Reverse transcription-quantitative PCR (RT-qPCR) is commonly used to diagnose SARS-CoV-2, but it has limited sensitivity in detecting the virus in asymptomatic close contacts and convalescent patients. In this study, we propose the use of reverse transcription-digital droplet PCR (RT-ddPCR) to detect SARS-CoV-2 in clinical samples. METHODS: The clinical performance of RT-ddPCR targeting of ORF1ab and N genes was evaluated in parallel with RT-qPCR using 200 respiratory samples collected from close contacts and patients at different phases of infection. RESULTS: The limits of detection (LODs) for RT-ddPCR assays were determined using six dilutions of ACCUPLEX SARS-Cov-2 reference material. The LODs of ORF1ab and N genes were 3.7 copies/reaction and 2.2 copies/reaction, respectively. Compared to RT-qPCR, RT-ddPCR increased the positive rate by 12.0% in 142 samples from SARS-CoV-2-infected patients. Additionally, RT-ddPCR detected SARS-CoV-2 in three of 26 specimens from close contacts that tested negative by RT-qPCR, and infection was confirmed using follow-up samples. Finally, RT-ddPCR improved the equivocal results from RT-qPCR in 56.3% (9/16) of convalescent patient samples. CONCLUSIONS: Detecting SARS-CoV-2 in samples with low viral loads using RT-qPCR can be challenging. However, our study suggests that RT-ddPCR, with its higher sensitivity and accuracy, is better suited for detecting low viral copies in samples, particularly those from close contacts and convalescent patients.

The validity of the assignment book-based structured interview in predicting academic performance in medical schools: a retrospective cohort study.

PURPOSE: Structured interviews have become essential in the medical schools admission selection because structured interviews predict academic achievement after admission. The purpose of this study was to determine validity and fairness of the new structural interview technique, assignment book-based structured interview (ABSI), in predicting future academic achievement of the medical students. METHODS: The validity of this new interview technique and academic achievement was evaluated based on the data of all the applicants and successful applicants who applied for on-time admission between the year 2011 and 2014. RESULTS: The ABSI technique showed a significant correlation and predictive validity for academic achievement in the medical school. The retention group received significantly lower T-scores of ABSI compared with the superior student group. CONCLUSION: The results indicate that ABSI is a feasible, reliable, fair and valid admission selection tool. The ABSI may be meaningful and fair method for predicting academic achievements, and it could be incorporated as one of the contents in the multiple mini-interview.

Development of a multiplex Loop-Mediated Isothermal Amplification (LAMP) assay for on-site diagnosis of SARS CoV-2.

A newly identified coronavirus, designated as severe acute respiratory syndrome coronavirus 2 (SARS CoV-2), has spread rapidly from its epicenter in China to more than 150 countries across six continents. In this study, we have designed three reverse-transcription loop-mediated isothermal amplification (RT-LAMP) primer sets to detect the RNA-dependent RNA polymerase (RdRP), Envelope (E) and Nucleocapsid protein (N) genes of SARS CoV-2. For one tube reaction, the detection limits for five combination SARS CoV-2 LAMP primer sets (RdRP/E, RdRP/N, E/N, RdRP/E/N and RdRP/N/Internal control (actin beta)) were evaluated with a clinical nasopharyngeal swab sample. Among the five combination, the RdRP/E and RdRP/N/IC multiplex LAMP assays showed low detection limits. The sensitivity and specificity of the RT-LAMP assay were evaluated and compared to that of the widely used Allplex™ 2019-nCoV Assay (Seegene, Inc., Seoul, South Korea) and PowerChek™ 2019-nCoV Real-time PCR kit (Kogenebiotech, Seoul, South Korea) for 130 clinical samples from 91 SARS CoV-2 patients and 162 NP specimens from individuals with (72) and without (90) viral respiratory infections. The multiplex RdRP (FAM)/N (CY5)/IC (Hex) RT-LAMP assay showed comparable sensitivities (RdRP: 93.85%, N: 94.62% and RdRP/N: 96.92%) to that of the Allplex™ 2019-nCoV Assay (100%) and superior to those of PowerChek™ 2019-nCoV Real-time PCR kit (RdRP: 92.31%, E: 93.85% and RdRP/E: 95.38%).

Multiple mini-interviews as a predictor of academic achievements during the first 2 years of medical school.

BACKGROUND: Recently, conventional interviews have been replaced with the multiple mini-interviews (MMI) for medical student selection in Korea. We first introduced the MMI as a new admissions tool in Korea. The aim of this study is to determine whether the MMI accurately predicts academic achievement on both written and performance-based examinations during the first 2 years of medical school. METHODS: The original scores of each station were standardized to T-scores in the candidates group. Three cohorts of students were included depending upon the year they entered medical school. Pearson's correlations were calculated to estimate the correlations between MMI scores and academic achievements. Additional correlated factors were run through multiple stepwise linear regression analysis to estimate predictive validity. RESULTS: There were no differences between T-scores or grade point averages (GPA) among the cohorts. The correlation coefficients between total MMI scores and academic achievement in Year 1 and the Year 2 performance-based examinations ranged from 0.17 to 0.43. Station 1 significantly predicted academic achievement over the second year. Station 3 significantly predicted only performance-based examination performance over the second year. CONCLUSION: MMI is a useful tool to assist with medical student selection. In particular, critical thinking, professionalism, and presentation and communication skills may be meaningful topics for predicting academic achievements, especially in performance-based subjects.

Very early onset of amiodarone-induced pulmonary toxicity.

Amiodarone is a widely used antiarrhythmic agent. Among its various adverse effects, amiodarone-induced pulmonary toxicity (APT) is the most life threatening complication, which has been described mostly in patients who have been in treatment with high accumulative doses for a long duration of time. However, amiodarone therapy in short-term duration induced APT was rarely reported. We describe a case of a 54-year-old man who is presented with symptoms of APT after a few days of therapy for post-myocardial infarction ventricular tachycardia. For early diagnosis and successful treatment, awareness and high suspicion of this rare type of early onset APT is crucial in patients with amiodarone therapy.

Acute myeloid leukemia (AML-M2) associated with variant t(8;21): report of three cases.

Variants of the t(8;21)(q22;q22) involving chromosome 8, 21, and other chromosomes account for approximately 3% of all t(8;21)(q22;q22) found in patients with acute myeloid leukemia (AML). The clinicopathologic features of AML with the variant t(8;21) have not been well established. We report three cases of AML with variants of t(8;21) characterized, respectively, by derivative 8 with the interstitial inverted insertion of 21q and concurrent monosomy 21, t(8;18;21)(p22;q11.3;q22), and t(2;21;8)(q11.2;q22;q22). Fluorescence in situ hybridization or reverse transcriptase-polymerase chain reaction assay confirmed the presence of RUNX1-RUNX1T1 gene (previously AML1-ETO) rearrangements. Among these cases, three-way breakpoints 18p11.3 and 2q11.2 have not been previously reported. The present report deals with the results of hematologic, immunophenotypic, cytogenetic, fluorescence in situ hybridization, and molecular analyses of these variants. The possible role of the genes in this region in leukemogenesis, response to treatment, and clinical implications are discussed.

Establishment of an HBsAg mixed titer performance panel and HBsAg working standard for quality control of HBsAg diagnostic kits in Korea.

BACKGROUND: International Standards or commercial panels used for performance validation of diagnostic kits might not reflect the viral characteristics common in Korea. Also, continuous use of these materials is difficult because of limited quantity and high cost. OBJECTIVES: Establishment of HBsAg reference materials to be used as National Standards for validation of HBsAg diagnostic kits. STUDY DESIGN: 568 plasma units with OD less than 2.0 on HBsAg EIA were collected. HBsAg testing with 3 EIAs and 1 CIA was performed on all units. HBsAg positive units were subjected to HBV DNA quantification, genotyping and subtyping. Candidates for the mixed titer performance panel and working standard were confirmed for HBsAg by neutralization. A collaborative study was conducted for the candidates of the mixed titer performance panel and the working standard. RESULTS: Based on the results of the collaborative study, a working standard (KFDA08/024) consisting of a series of four-fold dilutions of 2 materials, one with genotype/subtype C2/adr and the other with C1/adw, was established. A mixed titer performance panel composed of 2 negative and 16 positive samples was also established. A G1896A and a T/I126S mutant are included in the positive samples. CONCLUSIONS: An HBsAg mixed titer performance panel and a working standard reflecting HBV genotypes/subtypes prevalent in Korea have been established as National Standards. This will enable consistent supply of validation materials, improve the validation system of HBsAg diagnostic kits in Korea and lead to quality improvement of diagnostic kits.

Vasogenic edema in striatum following ingestion of glufosinate-containing herbicide.

Glufosinate-ammonium (GLA) is a broad-spectrum herbicide used worldwide. We report a patient who attempted suicide by ingesting a liquid herbicide containing GLA. A diffusion-weighted MRI showed cytotoxic edema in the hippocampus as well as vasogenic edema in the striata. To our knowledge, vasogenic edema caused by GLA-containing herbicide involving the striatum has not been reported in association with cytotoxic edema in the hippocampus. We assume that this herbicide affected the central nervous system via different mechanisms to produce both cytotoxic and vasogenic edema in the same patient.

Co-localization of inducible nitric oxide synthase and phosphorylated Akt in the lesional skins of patients with melasma.

Activation of the inducible nitric oxide synthase (iNOS)/nitric oxide (NO) pathway in keratinocytes has been reported to be associated with the pathogenesis of melanogenesis. Akt activation plays an important role in the activation of the transcription factor nuclear factor (NF)-kappaB and subsequent elevation of iNOS expression. In the present study, we highly detected both iNOS protein and Akt phosphorylation in keratinocytes of the basal layer of the epidermis at the junction with the dermis of melasma skin biopsy specimens, but not in normal skin tissues, from nine patients using immunohistological analysis. iNOS protein and phosphorylated Akt were co-localized in the lesional skins, and their levels were highly correlated R2= 0.69). Furthermore, iNOS mRNA was also detected in an additional three skin biopsy specimens, but not in normal skin, by reverse transcription polymerase chain reaction. Our results describe that iNOS expression is elevated in human melasma lesions, probably via activation of the Akt/NF-kappaB pathway, indicating that NO production plays an important role in the mechanism of hyperpigmentation in human facial melasma.

Efficacy of imatinib mesylate (STI571) in chronic neutrophilic leukemia with t(15;19): case report.

Chronic neutrophilic leukemia (CNL) is a rare hematologic disorder, for which there is no standard therapy. Recently, STI (imatinib mesylate) has been shown to be effective in treating patients with chronic myeloproliferative disorder (CMPD) displaying the translocation of the PDGFbetaR gene. Here, we present a case of a patient with CNL carrying t(15;19)(q13;p13.3) who achieved a cytogenetic remission following treatment with imatinib, 400 mg daily. After failure of alpha interferon and hydroxyurea therapy, a durable and complete clinical and cytogenic remission was induced by imatinib. To our knowledge, this is the first case with CNL who showed complete response with cytogenic remission after treatment of imatinib. The mechanism of response to this molecule is unknown in our case (other oncogenes than c-kit, tyrosine kinase, or PDGFR may be involved). The patient remains in complete remission with an excellent performance status after 7 months of therapy. We demonstrate here that imatinib can induce a clinical and cytogenetic response in a case of CNL associated with a novel translocation other than a 5q33 rearrangement. Further studies including the molecular cloning of the t(15;19)(q13;p13.3) will be important in understanding the pathophysiology of CNL with a heterogeneous clinical course and the exploitation of the basic mechanisms of imatinib treatment.