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.

Performance evaluation of four rapid antibody tests for the detection of severe acute respiratory syndrome coronavirus 2.

BACKGROUND: The prompt detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is important in the therapeutic management of infected patients. Rapid diagnostic tests are widely used for this purpose. This study aimed to evaluate the clinical performance of four SARS-CoV-2 immunoglobulin IgG/IgM rapid diagnostic tests in the detection of SARS-CoV-2. METHODS: Nasopharyngeal and oropharyngeal swabs and/or sputum were collected from 30 patients infected with SARS-CoV-2 and 30 healthy volunteers. All specimens were tested using four SARS-CoV-2 IgG/IgM rapid diagnostic tests and real-time polymerase chain reaction. We assessed the clinical sensitivity and specificity of the tests. RESULTS: The clinical sensitivity of FREND™, SsmarTest™, BIOCREDIT™, and IVDLAB™ was 96.67%, 100.00%, 100.00%, and 96.67%, respectively, compared to real-time polymerase chain reaction. The clinical specificity was 96.67%, 100.00%, 86.67%, and 96.67%, respectively. CONCLUSION: These findings could expedite the detection of SARS-CoV-2 and thus reduce the risk of further transmission of the virus.

Comparison of Six Antifungal Susceptibilities of 11 Candida Species Using the VITEK2 AST-YS08 Card and Broth Microdilution Method.

We used a Vitek 2 AST-YS08 (YS08) system and the broth microdilution method (BMD) adopted by the Clinical and Laboratory Standards Institute (CLSI) to compare the susceptibility of 184 isolates of 11 Candida species to fluconazole, voriconazole, micafungin, caspofungin, amphotericin B, and flucytosine. In Candida albicans, the categorical agreement (CA) was 79.2%, 91.7%, 95.8%, and 95.8% for fluconazole, voriconazole, micafungin, and caspofungin, respectively. About 12.5% and 4.2% of very major errors were detected for fluconazole and voriconazole, respectively. C. glabrata showed excellent essential agreements (EAs) (>90%) for azoles but different MIC distributions for fluconazole and caspofungin. The CA between BMD fluconazole MICs and YS08 voriconazole MICs by the method-specific clinical breakpoint (CBP) was 90% in C. glabrata. Over 80% of C. glabrata and C. krusei isolates identified as micafungin-susceptible were labeled intermediate or resistant to caspofungin in YS08. In C. parapsilosis, 5.3% of very major errors and 10.5% of minor errors were found, whereas 33.3% of minor errors were observed in C. tropicalis for fluconazole. For C. tropicalis, 13 (61.9%) non-wild type (WT) isolates of fluconazole and 7 (33.3%) non-WTs of voriconazole were classified in YS08 as WT. For C. auris, the EAs were 93.3%, 100%, 82.2%, 97.8%, and 97.8% for fluconazole, voriconazole, micafungin, caspofungin, and amphotericin B, respectively. YS08 showed comparable results to the BMD. However, considering the lower YS08 fluconazole MIC results compared with BMD in Candida species and YS08 caspofungin results in C. glabrata and C. krusei, improvements are needed. IMPORTANCE The new Vitek 2 AST-YS08 (YS08) card has been updated to reflect the recently revised Clinical and Laboratory Standards Institute (CLSI) guideline. In this study, antifungal drug susceptibility tests were performed using the YS08 card and compared with the CLSI broth microdilution (BMD) method. In conclusion, YS08 showed similar results to BMD, including with C. auris. However, about 12.5% and 4.2% of major errors were detected for fluconazole and voriconazole, respectively, in C. albicans. More than 80% of C. glabrata and C. krusei isolates identified as susceptible to micafungin were labeled moderate or resistant to caspofungin in YS08. The categorical agreement between BMD fluconazole MICs and YS08 voriconazole MICs was 90% by the method-specific CBP of voriconazole, 80% by the current epidemiological cutoff value (ECV) (0.25 µg/mL) of voriconazole, and 85% by the previous ECV (0.5 µg/mL) of voriconazole. Further improvements in YS08 for the detection of fluconazole and echinocandin resistance are thus needed.

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%).

Erratum: COVID-19 Molecular Testing in Korea: Practical Essentials and Answers From Experts Based on Experiences of Emergency Use Authorization Assays.

[This corrects the article on p. 439 in vol. 40.].

Multilaboratory Evaluation of the MALDI-TOF Mass Spectrometry System, MicroIDSys Elite, for the Identification of Medically Important Filamentous Fungi.

With the increasing number of fungal infections and immunocompromised patients, rapid and accurate fungal identification is required in clinical microbiology laboratories. We evaluated the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) system, MicroIDSys Elite (ASTA Corp., South Korea) for the identification of medically important filamentous fungi. A total of 505 strains comprising 37 genera and 90 species collected from 11 Korean hospitals were sent to the microbiology laboratory of International St. Mary's Hospital. All isolates were tested using MicroIDSys Elite, and data were analyzed using the MoldDB v.1.22 database (ASTA). Correct identification rates were compared with the multigene sequencing results. MicroIDSys Elite correctly identified 86.5% (437/505) and 88.9% (449/505) of all tested isolates at the species and genus level, respectively. About 98.2% of Aspergillus isolates were identified at the species level, including cryptic and rare species of A. calidoustus, A. tamarii, A. lentulus, A. versicolor and A. aculeatus. MicroIDSys Elite identified 75.0% of basidiomycetes, including Schizophyllum commune, and 84.3% of the dermatophytes. It also distinguished Sprothrix globosa at the species level. The mean scores of total isolates corresponding to correct species identification were significantly higher than those obtained for genus-level identification (253.5 ± 50.7 vs. 168.6 ± 30.3, P < 0.001). MicroIDSys Elite showed high accuracy for the identification of filamentous fungi, including cryptic and rare Aspergillus species. It is suitable for use in clinical laboratories as a rapid and efficient tool for clinical mold identification. Further evaluations are recommended for MicroIDSys Elite as a rapid and efficient tool for the identification of medically important filamentous fungi.

COVID-19 Molecular Testing in Korea: Practical Essentials and Answers From Experts Based on Experiences of Emergency Use Authorization Assays.

Coronavirus disease 2019 (COVID-19) is a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Early detection of COVID-19 and immediate isolation of infected patients from the naive population are important to prevent further pandemic spread of the infection. Real-time reverse transcription (RT)-PCR to detect SARS-CoV-2 RNA is currently the most reliable diagnostic method for confirming COVID-19 worldwide. Guidelines for clinical laboratories on the COVID-19 diagnosis have been recently published by Korean Society for Laboratory Medicine and the Korea Centers for Disease Control and Prevention. However, these formal guidelines do not address common practical laboratory issues related to COVID-19 real-time RT-PCR testing and their solutions. Therefore, this guideline is intended as a practical and technical supplement to the "Guidelines for Laboratory Diagnosis of COVID-19 in Korea".

Protriptyline, a tricyclic antidepressant, inhibits voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells.

In this study, we explore the inhibitory effects of protriptyline, a tricyclic antidepressant drug, on voltage-dependent K+ (Kv) channels of rabbit coronary arterial smooth muscle cells using a whole-cell patch clamp technique. Protriptyline inhibited the vascular Kv current in a concentration-dependent manner, with an IC50 value of 5.05 ± 0.97 µM and a Hill coefficient of 0.73 ± 0.04. Protriptyline did not affect the steady-state activation kinetics. However, the drug shifted the steady-state inactivation curve to the left, suggesting that protriptyline inhibited the Kv channels by changing their voltage sensitivity. Application of 20 repetitive train pulses (1 or 2 Hz) progressively increased the protriptyline-induced inhibition of the Kv current, suggesting that protriptyline inhibited Kv channels in a use (state)-dependent manner. The extent of Kv current inhibition by protriptyline was similar during the first, second, and third step pulses. These results suggest that protriptyline-induced inhibition of the Kv current mainly occurs principally in the closed state. The increase in the inactivation recovery time constant in the presence of protriptyline also supported use (state)-dependent inhibition of Kv channels by the drug. In the presence of the Kv1.5 inhibitor, protriptyline did not induce further inhibition of the Kv channels. However, pretreatment with a Kv2.1 or Kv7 inhibitor induced further inhibition of Kv current to a similar extent to that observed with protriptyline alone. Thus, we conclude that protriptyline inhibits the vascular Kv channels in a concentration- and use-dependent manner by changing their gating properties. Furthermore, protriptyline-induced inhibition of Kv channels mainly involves the Kv1.5.

Comparison of three rapid influenza diagnostic tests with digital readout systems and one conventional rapid influenza diagnostic test.

BACKGROUND: Rapid influenza diagnostic tests (RIDTs) show variable sensitivities in clinical settings. We aimed to compare three digital RIDTs and one conventional RIDT. METHODS: We assessed 218 nasopharyngeal swabs from patients between neonates and 90 years old in 2016. Three digital RIDTs were BUDDI, Sofia Influenza A+B Fluorescence Immunoassay, Veritor System Flu A+B assay. One conventional test was the SD Bioline Influenza Ag A/B/A(H1N1/2009). All test results were compared with those from the Anyplex Flu A/B Typing Real-time Detection real-time PCR. The four RIDTs were tested with diluted solutions from the National Institute for Biological Standards and Control (NIBSC) to compare lower detection limit. Cross-reactivity of four RIDTs within other respiratory viruses was identified. RESULTS: For influenza A, BUDDI, Sofia, Veritor, and Bioline showed 87.7%, 94.5%, 87.7%, and 72.6% sensitivity, and 100%, 97.7%, 96.5%, and 100% specificity. For influenza B, BUDDI, Sofia, Veritor, and Bioline showed 81.7%, 91.7%, 81.7%, and 78.3% sensitivity, and 100%, 95.3%, 100%, and 100% specificity, respectively. Each RIDT could detect diluted NIBSC solution, according to the level of dilution and specific influenza subtypes. Cross-reactivity of four RIDTs with other respiratory viruses was not noted. CONCLUSIONS: Sofia showed the highest sensitivity for influenza A and B detection. BUDDI and Veritor showed higher detection sensitivity than a conventional RIDT for influenza A detection, but similar results for influenza B detection. Further study is needed to compare the test performance of RIDTs according to specific, prevalent influenza subtypes.

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.

Multicatalytic colloids with highly scalable, adjustable, and stable functionalities in organic and aqueous media.

Despite a large number of developments of noble metal (or metal oxide) NP-based catalysts, it has been a great challenge to prepare high-performance recyclable catalysts with integrated functionalities that can be used in various solvent media. Here, we report on layer-by-layer (LbL) assembled multicatalysts with high catalytic performance, showing high dispersion and recycling stability in organic and aqueous media. The remarkable advantages of our approach are as follows. (i) Various metal or metal oxide NPs with desired catalytic performance can be easily incorporated into multilayered shells, forming densely packed arrays that allow one colloid to be used as a multicatalyst with highly integrated and controllable catalytic properties. (ii) Additionally, the dispersion stability of catalytic colloids in a desired solvent can be determined by the type of ultrathin outermost layer coating each colloid. (iii) Lastly, the covalent bonding between inorganic NPs and dendrimers within multilayer shells enhances the recycling stability of multicatalytic colloids. The resulting core-shell colloids including OA-Fe3O4 NPs, TOABr-Pd NPs, and OA-TiO2 NPs exhibited excellent performance in the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) and photocatalysis in aqueous media and in the Sonogashira coupling reaction (99% yield) in organic media. Given that the catalytic properties of recyclable colloids reported to date have entirely depended on the functionality of a single catalytic NP layer deposited onto colloids in selective solvent media, our approach provides a basis for the design and exploitation of high-performance recyclable colloids with integrated multicatalytic properties and high dispersion stability in a variety of solvents.

Amphiphilic layer-by-layer assembly overcoming solvent polarity between aqueous and nonpolar media.

We introduce a general and versatile methodology that allows a facile incorporation of the functional components with completely different chemistry of hydrophilic/hydrophobic properties within nanocomposite films, and furthermore combine a number of the distinctive advantages of traditional electrostatic layer-by-layer (LbL) assembly in aqueous media and covalent LbL assembly in nonpolar media. Our approach, amphiphilic LbL assembly, is based on the high affinity between sulfonic (or phosphonic) acid-functionalized materials in aqueous media and hydrophobic metal oxide (or metal) NPs stabilized by oleic acid (OA) in nonpolar solvent. For demonstrating the effectiveness of our approach, we show that amphiphilic LbL assembly can be easily applied to the preparation of functional colloid materials allowing the reversible phase transfer between aqueous and nonpolar media, and supercapacitor electrodes with high volumetric capacitance (280 F·cm(-3) at 10 mV·s(-1)) using reduced graphene oxide with sulfonic acid moieties and well-defined OA-Fe3O4 NPs.

Transistor memory devices with large memory windows, using multi-stacking of densely packed, hydrophobic charge trapping metal nanoparticle array.

Organic field-effect transistor (OFET) memories have rapidly evolved from low-cost and flexible electronics with relatively low-memory capacities to memory devices that require high-capacity memory such as smart memory cards or solid-state hard drives. Here, we report the high-capacity OFET memories based on the multilayer stacking of densely packed hydrophobic metal NP layers in place of the traditional transistor memory systems based on a single charge trapping layer. We demonstrated that the memory performances of devices could be significantly enhanced by controlling the adsorption isotherm behavior, multilayer stacking structure and hydrophobicity of the metal NPs. For this study, tetraoctylammonium (TOA)-stabilized Au nanoparticles (TOA-Au(NPs)) were consecutively layer-by-layer (LbL) assembled with an amine-functionalized poly(amidoamine) dendrimer (PAD). The formed (PAD/TOA-Au(NP))(n) films were used as a multilayer stacked charge trapping layer at the interface between the tunneling dielectric layer and the SiO2 gate dielectric layer. For a single AuNP layer (i.e. PAD/TOA-Au(NP))1) with a number density of 1.82 × 10(12) cm(-2), the memory window of the OFET memory device was measured to be approximately 97 V. The multilayer stacked OFET memory devices prepared with four Au(NP) layers exhibited excellent programmable memory properties (i.e. a large memory window (ΔV(th)) exceeding 145 V, a fast switching speed (1 µs), a high program/erase (P/E) current ratio (greater than 10(6)) and good electrical reliability) during writing and erasing over a relatively short time scale under an operation voltage of 100 V applied at the gate.

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.

[Down-Turner syndrome (45,X/47,XY,+21): case report and review].

We report the case of a 3-yr-old boy with Down-Turner mosaicism and review the previous reports of Down-Turner syndrome with documented karyotyping and clinical features. The patient showed clinical features of Down syndrome without significant stigma of Turner syndrome. Cytogenetic analysis of peripheral blood preparations by using G-banding revealed mosaicism with 2 cell lines (45,X[29]/47,XY,+21[4]). FISH analysis revealed that 87.5% of the cells had monosomy X karyotype and 12.5% of the cells had XY karyotype; trisomy 21 was only detected in the Y-positive cells. We suggest that additional cells should be analyzed and molecular genetic studies should be conducted to rule out double aneuploidy when karyotypes with sex chromosome aneuploidies and mosaicism are encountered, as in our case of Down syndrome mosaic with sex chromosome aneuploidy.