Influence of the KCNQ1 S140G Mutation on Human Ventricular Arrhythmogenesis and Pumping Performance: Simulation Study

The KCNQ1 S140G mutation, which is involved in IKs current, affects atrial fibrillation. However, little is known about its effect on the mechanical behavior of the heart. Therefore, we assessed the influence of the KCNQ1 S140G mutation on ventricular electrophysiological stability and mechanical pumping performance using a multi-scale model of cardiac electromechanics. An image-based electromechanical model was used to assess the effect on electrical propagation and arrhythmogenesis of the KCNQ1 S140G mutation. In addition, it was used to compare the mechanical response under the wild-type (WT) and S140G mutation conditions. The intracellular calcium transient obtained from the electrophysiological model was applied as an input parameter to a mechanical model to implement excitation–contraction coupling. The IKs current equation was modified to account for expression of the KCNQ1 S140G mutation, and it included a scaling factor (ϕ) for mutant expressivity. The WT and S140G mutation conditions were compared at the single-cell and three-dimensional (3D) tissue levels. The action potential duration (APD) was reduced by 60% by the augmented IKs current under the S140G mutation condition, which resulted in shorter QT interval. This reduced the 3D sinus rhythm wavelength by 60% and the sustained re-entry by 56%. However, pumping efficiency of mutant ventricles was superior in sinus rhythm condition. In addition, the shortened wavelength in cardiac tissue allowed a re-entrant circuit to form and increased the probability of sustaining ventricular tachycardia and ventricular fibrillation. In contrast, under the WT condition, a normal wavelength (20.8 cm) was unlikely to initiate and sustain re-entry in the cardiac tissue. Subsequently, the S140G mutant ventricles developed a higher dominant frequency distribution range (2.0–5.3 Hz) than the WT condition (2.8–3.7 Hz). In addition, stroke volume of mutant ventricles was reduced by 65% in sustained re-entry compared to the WT condition. In conclusion, signs of the S140G mutation might be difficult to identify in sinus rhythm even though the mutant ventricles show shortened QT interval. This suggests that the KCNQ1 S140G mutation increases the risk of death by sudden cardiac arrest. In addition, the KCNQ1 S140G mutation can induce ventricular arrhythmia and lessen ventricular contractility under re-entrant conditions

qInward variability-based in-silico proarrhythmic risk assessment of drugs using deep learning model

Many researchers have suggested evaluation methods and Torsades de Pointes (TdP) metrics to assess the proarrhythmic risk of a drug based on the in silico simulation, as part of the Comprehensive in-vitro Proarrhythmia Assay (CiPA) project. In the previous study, we validated the robustness of 12 in silico features using the ordinal logistic regression (OLR) model by comparing the classification performances of metrics according to the in-vitro experimental datasets used; however, the OLR model using 12 in silico features did not provide desirable results. This study proposed a convolutional neural network (CNN) model using the variability of promising in silico TdP metrics hypothesizing that the variability of in silico features based on beats has more information than the single value of in silico features. We performed the action potential (AP) simulation using a human ventricular myocyte model to calculate seven in silico features representing the electrophysiological cell states of drug effects over 1,000 beats: qNet, qInward, intracellular calcium duration at returning to 50% baseline (CaD50) and 90% baseline (CaD90), AP duration at 50% repolarization (APD50) and 90% repolarization (APD90), and dVm/dtMax_repol. The proposed CNN classifier was trained using 12 train drugs and tested using 16 test drugs among CiPA drugs. The torsadogenic risk of drugs was classified as high, intermediate, and low risks. We determined the CNN classifier by comparing the classification performance according to the variabilities of seven in silico biomarkers computed from the in silico drug simulation using the Chantest dataset. The proposed CNN classifier performed the best when using qInward variability to classify the TdP-risk drugs with 0.94 AUC for high risk and 0.93 AUC for low risk. In addition, the final CNN classifier was validated using the qInward variability obtained after merging three in-vitro datasets, but the model performance decreased to a moderate level of 0.75 and 0.78 AUC. These results suggest the need for the proposed CNN model to be trained and tested using various types of drugs

Normalization of Red Cell Enolase Level Following Allogeneic Bone Marrow Transplantation in a Child with Diamond-Blackfan Anemia

We describe a girl with Diamond-Blackfan anemia with accompanying red cell enolase deficiency. At the age of 9 yr old, the patient received allogeneic bone marrow transplantation from her HLA-identical sister who had normal red cell enolase activity. While the post transplant DNA analysis with short tandem repeat has continuously demonstrated a stable mixed chimerism on follow-up, the patient remains transfusion independent and continues to show a steady increase in red cell enolase activity for over two and a half years following bone marrow transplantation

Assessment of the proarrhythmic effects of repurposed antimalarials for COVID-19 treatment using a comprehensive in vitro proarrhythmia assay (CiPA)

Due to the outbreak of the SARS-CoV-2 virus, drug repurposing and Emergency Use Authorization have been proposed to treat the coronavirus disease 2019 (COVID-19) during the pandemic. While the efficiency of the drugs has been discussed, it was identified that certain compounds, such as chloroquine and hydroxychloroquine, cause QT interval prolongation and potential cardiotoxic effects. Drug-induced cardiotoxicity and QT prolongation may lead to life-threatening arrhythmias such as torsades de pointes (TdP), a potentially fatal arrhythmic symptom. Here, we evaluated the risk of repurposed pyronaridine or artesunate-mediated cardiac arrhythmias alone and in combination for COVID-19 treatment through in vitro and in silico investigations using the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative. The potential effects of each drug or in combinations on cardiac action potential (AP) and ion channels were explored using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and Chinese hamster ovary (CHO) cells transiently expressing cardiac ion channels (Nav1.5, Cav1.2, and hERG). We also performed in silico computer simulation using the optimized O’Hara-Rudy human ventricular myocyte model (ORd model) to classify TdP risk. Artesunate and dihydroartemisinin (DHA), the active metabolite of artesunate, are classified as a low risk of inducing TdP based on the torsade metric score (TMS). Moreover, artesunate does not significantly affect the cardiac APs of hiPSC-CMs even at concentrations up to 100 times the maximum serum concentration (Cmax). DHA modestly prolonged at APD90 (10.16%) at 100 times the Cmax. When considering Cmax, pyronaridine, and the combination of both drugs (pyronaridine and artesunate) are classified as having an intermediate risk of inducing TdP. However, when considering the unbound concentration (the free fraction not bound to carrier proteins or other tissues inducing pharmacological activity), both drugs are classified as having a low risk of inducing TdP. In summary, pyronaridine, artesunate, and a combination of both drugs have been confirmed to pose a low proarrhythmogenic risk at therapeutic and supratherapeutic (up to 4 times) free Cmax. Additionally, the CiPA initiative may be suitable for regulatory use and provide novel insights for evaluating drug-induced cardiotoxicity

Targeted mutagenesis in mouse cells and embryos using an enhanced prime editor

Prime editors, novel genome-editing tools consisting of a CRISPR-Cas9 nickase and an engineered reverse transcriptase, can induce targeted mutagenesis. Nevertheless, much effort is required to optimize and improve the efficiency of prime-editing. Herein, we introduce two strategies to improve the editing efficiency using proximal dead sgRNA and chromatin-modulating peptides. We used enhanced prime-editing to generate Igf2 mutant mice with editing frequencies of up to 47% and observed germline transmission, no off-target effects, and a dwarf phenotype. This improved prime-editing method can be efficiently applied to cell research and to generate mouse models.This study was supported by the Chung Yang, Cha Young Sun, & Jang Hi Joo Memorial Fund. This study was also supported by the Bio & Medical Technology Development Program of the National Research Foundation (NRF) of Korea (Korea Mouse Phenotyping Project, NRF-2013M3A9D5072550, NRF-2020M3A9D5A01082439, NRF2019R1A2C2087198, and NRF- 2019M3A9H1103792)

Procyanidins from Wild Grape (Vitis amurensis) Seeds Regulate ARE-Mediated Enzyme Expression via Nrf2 Coupled with p38 and PI3K/Akt Pathway in HepG2 Cells

Procyanidins, polymers of flavan-3-ol units, have been reported to exhibit many beneficial health effects such as antioxidant and anti-carcinogenic effects. In this study, we investigated the cancer chemopreventive properties of procyanidins from wild grape (Vitis amurensis) seeds in particular their roles in inducing phase II detoxifying/antioxidant enzymes as well as in modulating the upstream kinases. Ethanolic extract of V. amurensis seeds was fractionated with a series of organic solvents and finally separated into six fractions, F1–F6. Chemical properties of the procyanidins were analyzed by vanillin assay, BuOH-HCl test, and depolymerization with phloroglucinol followed by LC/MS analysis. The F5 had the highest procyanidin content among all the fractions and strongly induced the reporter activity of antioxidant response element as well as the protein expression of nuclear factor E2-related factor (Nrf2) in HepG2 human hepatocarcinoma cells. The procyanidin-rich F5 also strongly induced the expression of the phase II detoxifying and antioxidant enzymes such as NAD(P)H:quinone oxidoreductase1 and hemeoxygenase1. Phosphorylations of the upstream kinases such as MAPKs and PI3K/Akt were significantly increased by treatment with procyanidin fraction. In addition, the procyanidin-mediated Nrf2 expression was partly attenuated by PI3K inhibitor LY294002, and almost completely by p38 inhibitor SB202190, but neither by JNK inhibitor SP600125 nor by MEK1/2 inhibitor U0126. Taken together, the procyanidins from wild grape seeds could be used as a potential natural chemopreventive agent through Nrf2/ARE-mediated phase II detoxifying/antioxidant enzymes induction via p38 and PI3K/Akt pathway

Association of plasma amyloid-β oligomerization with theta/beta ratio in older adults

BackgroundOligomeric Aβ (OAβ) is a promising candidate marker for Alzheimer’s disease (AD) diagnosis. Electroencephalography (EEG) is a potential tool for early detection of AD. Still, whether EEG power ratios, particularly the theta/alpha ratio (TAR) and theta/beta ratio (TBR), reflect Aβ burden—a primary mechanism underlying cognitive impairment and AD. This study investigated the association of TAR and TBR with amyloid burden in older adults based on MDS-OAβ levels.Methods529 individuals (aged ≥60 years) were recruited. All participants underwent EEG (MINDD SCAN, Ybrain Inc., South Korea) and AlzOn™ test (PeopleBio Inc., Gyeonggi-do, Republic of Korea) for quantifying MDS-OAβ values in the plasma. EEG variables were log-transformed to normalize the data distribution. Using the MDS-OAβ cutoff value (0.78 ng/mL), all participants were classified into two groups: high MDS-OAβ and low MDS-OAβ.ResultsParticipants with high MDS-OAβ levels had significantly higher TARs and TBRs than those with low MDS-OAβ levels. The log-transformed TBRs in the central lobe (β = 0.161, p = 0.0026), frontal lobe (β = 0.145, p = 0.0044), parietal lobe (β = 0.166, p = 0.0028), occipital lobe (β = 0.158, p = 0.0058), and temporal lobe (beta = 0.162, p = 0.0042) were significantly and positively associated with increases in MDS-OAβ levels. After adjusting for the Bonferroni correction, the TBRs in all lobe regions, except the occipital lobe, were significantly associated with increased MDS-OAβ levels.ConclusionWe found a significant association of MDS-OAβ with TBR in older adults. This finding indicates that an increase in amyloid burden may be associated with an increase in the low-frequency band and a decrease in the relatively high-frequency band

A placebo-controlled trial of Korean red ginseng extract for preventing Influenza-like illness in healthy adults

<p>Abstracts</p> <p>Background</p> <p>Standardized Korean red ginseng extract has become the best-selling influenza-like illness (ILI) remedy in Korea, yet much controversy regarding the efficacy of the Korean red ginseng (KRG) in reducing ILI incidence remains. The aim of the study is to assess the efficacy of the KRG extract on the ILI incidence in healthy adults.</p> <p>Methods/Design</p> <p>We will conduct a randomized, double-blind, placebo-controlled study at the onset of the influenza seasons. A total of 100 subjects 30-70 years of age will be recruited from the general populations. The subjects will be instructed to take 9 capsules per day of either the KRG extract or a placebo for a period of 3 months. The primary outcome measure is to assess the frequency of ILI onset in participated subjects. Secondary variable measures will be included severity and duration of ILI symptoms. The ILI symptoms will be scored by subjects using a 4-point scale.</p> <p>Discussion</p> <p>This study is a randomized placebo controlled trial to evaluate the efficacy of the KRG extract compared to placebo and will be provided valuable new information about the clinical and physiological effects of the KRG extract on reduction of ILI incidence including flu and upper respiratory tract infections. The study has been pragmatically designed to ensure that the study findings can be implemented into clinical practice if KRG extract can be shown to be an effective reduction strategy in ILI incidence.</p> <p>Trial Registration</p> <p><a href="http://www.clinicaltrials.gov/ct2/show/NCT01478009">NCT01478009</a>.</p