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https://www.readbyqxmd.com/read/28521025/mechanism-of-as2o3-induced-action-potential-prolongation-and-using-hips-cms-to-evaluate-the-rescue-efficacy-of-drugs-with-different-rescue-mechanism
#1
Meng Yan, Lifang Feng, Yanhui Shi, Junnan Wang, Yan Liu, Fengmei Li, Baoxin Li
Arsenic trioxide (As2O3) has been verified as a breakthrough in the management of acute promyelocytic leukemia in recent decades. However, cardiotoxicity, especially long QT syndrome (LQTS) has become the most important issue during As2O3 treatment. The characterized mechanisms behind this adverse effect are inhibition of cardiac hERG channel trafficking and increase of cardiac calcium currents. In our study, we found a new pathway underlying As2O3-induced cardiotoxicity that As2O3 accelerates lysosomal degradation of hERG on plasma membrane after using brefeldin A (BFA) to block protein trafficking...
May 17, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
https://www.readbyqxmd.com/read/28499268/first-universal-pharmacophore-model-for-herg1-k-channel-activators-acther
#2
Serdar Durdagi, Ismail Erol, Ramin Ekhteiari Salmas, Matthew Patterson, Sergei Y Noskov
The intra-cavitary drug blockade of hERG1 channel has been extensively studied, both experimentally and theoretically. Structurally diverse ligands inadvertently block the hERG1 K(+) channel currents lead to drug induced Long QT Syndrome (LQTS). Accordingly, designing either hERG1 channel openers or current activators, with the potential to target other binding pockets of the channel, has been introduced as a viable approach in modern anti-arrhythmia drug development. However, reports and investigations on the molecular mechanisms underlying activators binding to the hERG1 channel remain sparse and the overall molecular design principles are largely unknown...
April 5, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28495999/%C3%AE-arrestin-mediated-regulation-of-the-human-ether-a-go-go-related-gene-herg-potassium-channel
#3
Matthew G Sangoi, Shawn M Lamothe, Jun Guo, Tonghua Yang, Wentao Li, Ellen G Avery, John T Fisher, Shetuan Zhang
The rapidly activating delayed rectifier K(+) channel (IKr) is encoded by the human ether-a-go-go-related gene (hERG), which is important for the repolarization of the cardiac action potential. Mutations in hERG or drugs can impair the function or decrease the expression level of hERG channels, leading to long QT syndrome (LQTS). Thus, it is important to understand hERG channel trafficking and its regulation. For this purpose, G protein-coupled receptors (GPCRs), which regulate a vast array of cellular processes, represent a useful route...
May 11, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/28492533/gene-patents-still-alive-and-kicking-their-impact-on-provision-of-genetic-testing-for-long-qt-syndrome-in-the-canadian-public-health-care-system
#4
Sarah E Ali-Khan, E Richard Gold
PurposeAlthough the Supreme Court of the United States limited their availability in Association for Molecular Pathology v. Myriad Genetics, gene patents remain important around the world. We examine the situation in Canada, where gene patents continue to exist, in light of recent litigation relating to familial long QT syndrome (LQTS).MethodsWe conducted in-depth semistructured interviews with 25 stakeholders across five Canadian provinces and supplemented this with a case analysis of the litigation.ResultsThe majority of LQTS testing was carried out outside Canada...
May 11, 2017: Genetics in Medicine: Official Journal of the American College of Medical Genetics
https://www.readbyqxmd.com/read/28490617/systemic-inflammation-as-a-novel-qt-prolonging-risk-factor-in-patients-with-torsades-de-pointes
#5
Pietro Enea Lazzerini, Franco Laghi-Pasini, Iacopo Bertolozzi, Gabriella Morozzi, Sauro Lorenzini, Antonella Simpatico, Enrico Selvi, Maria Romana Bacarelli, Francesco Finizola, Francesca Vanni, Deana Lazaro, Ademuyiwa Aromolaran, Nabil El Sherif, Mohamed Boutjdir, Pier Leopoldo Capecchi
OBJECTIVE: Increasing evidence indicates systemic inflammation as a new potential cause of acquired long QT syndrome (LQTS), via cytokine-mediated changes in cardiomyocyte ion channels. Torsade de pointes (TdP) is a life-threatening polymorphic ventricular tachycardia occurring in patients with LQTS, usually when multiple QT-prolonging factors are simultaneously present. Since classical risk factors cannot fully explain TdP events in a number of patients, we hypothesised that systemic inflammation may represent a currently overlooked risk factor contributing to TdP development in the general population...
May 10, 2017: Heart: Official Journal of the British Cardiac Society
https://www.readbyqxmd.com/read/28479515/phase-contrast-magnet-resonance-imaging-reveals-regional-transmural-and-base-to-apex-dispersion-of-mechanical-dysfunction-in-long-qt-syndrome-patients
#6
Johannes Brado, Markus J Dechant, Marius Menza, Adriana Komancsek, Corinna N Lang, Heiko Bugger, Daniela Foell, Bernd A Jung, Brigitte Stiller, Christoph Bode, Katja E Odening
BACKGROUND: Regional dispersion of prolonged repolarization is a hallmark of long QT syndrome (LQTS). We have revealed regional heterogeneities also in mechanical dysfunction in transgenic LQTS rabbit models. OBJECTIVE: In this clinical pilot study, we investigated whether LQTS patients exhibit dispersion of mechanical/diastolic dysfunction. METHODS: 9 pediatric patients with genotyped LQTS (12.2±3.3y) and 9 age- and sex-matched healthy controls (10...
May 4, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28477086/effects-of-salvianolic-acid-b-on-l-type-calcium-channels-and-myocardial-contractility-in-isolated-rat-ventricular-myocytes-and-herg-k-channels-expressed-in-hek293-cells
#7
Qiongtao Song, Xue Han, Yuchong Xue, Tao Song, Xi Chu, Xuan Zhang, Yuanyuan Zhang, Ying Zhang, Jianping Zhang, Li Chu
Salvianolic acid B (Sal B), one of the chief water-soluble constituents in Radix Salviae Milthiorrhizae, has often been reported to possess considerable cardiovascular regulatory effects. However, the underlying biochemical and cellular mechanisms of its cardioprotection remain unclear. This study was designed to evaluate the role of Sal B regulation in L-type Ca(2+) channel currents (ICa,L) and cell contractility in rat cardiomyocytes and hERG K(+) channels expressed in HEK293 cells with the patch-clamp and Ca(2+) imaging techniques to clarify its underlying cardioprotective mechanisms...
May 5, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28438721/clinical-profile-and-mutation-spectrum-of-long-qt-syndrome-in-saudi-arabia-the-impact-of-consanguinity
#8
Zuhair N Al-Hassnan, Majid Al-Fayyadh, Bander Al-Ghamdi, Azam Shafquat, Yaseen Mallawi, Faten Al-Hadeq, Sahar Tulbah, Zarghuna M A Shinwari, Abdulrahman Almesned, Ali Alakhfash, Fadel Al Fadly, Ahmed S Hersi, Abdullah Alhayani, Amal Al-Hashem, Dia Arafah, Nduna Dzimiri, Brian Meyer, Monther Rababh, Waleed Al-Manea
BACKGROUND: Congenital long QT syndrome (LQTS) is an inherited, potentially fatal arrhythmogenic disorder. At least 16 genes have been implicated in LQTS; the yield of genetic analysis of 3 genes (KCNQ1, KCNH2, and SCN5A) is about 70%, with KCNQ1 mutations accounting for ∼50% of positive cases. LQTS is mostly inherited in an autosomal dominant pattern. Systemic analysis of LQTS has not been previously conducted in a population with a high degree of consanguinity. OBJECTIVES: To describe the clinical and molecular profiles of LQTS in the highly consanguineous Saudi population...
April 22, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28429460/automated-t-wave-analysis-can-differentiate-acquired-qt-prolongation-from-congenital-long-qt-syndrome
#9
Alan Sugrue, Peter A Noseworthy, Vaclav Kremen, J Martijn Bos, Bo Qiang, Ram K Rohatgi, Yehu Sapir, Zachi I Attia, Peter Brady, Pedro J Caraballo, Samuel J Asirvatham, Paul A Friedman, Michael J Ackerman
BACKGROUND: Prolongation of the QT on the surface electrocardiogram can be due to either genetic or acquired causes. Distinguishing congenital long QT syndrome (LQTS) from acquired QT prolongation has important prognostic and management implications. We aimed to investigate if quantitative T-wave analysis could provide a tool for the physician to differentiate between congenital and acquired QT prolongation. METHODS: Patients were identified through an institution-wide computer-based QT screening system which alerts the physician if the QTc ≥ 500 ms...
April 21, 2017: Annals of Noninvasive Electrocardiology
https://www.readbyqxmd.com/read/28416468/cardiac-transplantation-in-children-and-adolescents-with-long-qt-syndrome
#10
Angela M Kelle, J Martijn Bos, Susan P Etheridge, Bryan C Cannon, Randall M Bryant, Jonathan N Johnson, Michael J Ackerman
BACKGROUND: Long QT syndrome (LQTS) is a potentially lethal, yet highly treatable, cardiac channelopathy. Cardiac transplantation has been reported anecdotally for patients with severe LQTS refractory to standard therapies. OBJECTIVE: The purpose of this study was to evaluate the incidence of and risk factors for cardiac transplantation in children evaluated and treated in an LQTS specialty center. METHODS: This was a retrospective review of 349 children with LQTS (mean age at diagnosis, 8...
April 14, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28413954/computational-models-for-understanding-of-structure-function-and-pharmacology-of-the-cardiac-potassium-channel-kv11-1-herg
#11
Sören Wacker, Sergei Yu Noskov, Laura L Perissinotti
The rapid delayed rectifier current IKr is one of the major K+ currents involved into repolarization of the human cardiac action potential. Various inherited or drug-induced forms of the long QT syndrome (LQTS) in humans are linked to functional and structural modifications in the IKr conducting channels. IKr is carried by the potassium channel Kv11.1 encoded by the gene KCNH2 (commonly referred to as human ether-a-go-go-related gene or hERG) [1][2]. The first necessary step for predicting emergent drug effects on the heart is determining and modeling the binding thermodynamics and kinetics of primary and major off-target drug interactions with subcellular targets...
April 14, 2017: Current Topics in Medicinal Chemistry
https://www.readbyqxmd.com/read/28412158/lidocaine-attenuation-testing-an-in%C3%A2-vivo-investigation-of-putative-lqt3-associated-variants-in-the-scn5a-encoded-sodium-channel
#12
Heather N Anderson, J Martijn Bos, Jamie D Kapplinger, Jana M Meskill, Dan Ye, Michael J Ackerman
BACKGROUND: Long QT syndrome type 3 (LQT3) accounts for 5%-10% of long QT syndrome and results from gain-of-function mutations in the SCN5A-encoded sodium channel. Approximately 2% of healthy individuals host rare SCN5A variants of uncertain significance (VUS). Distinction of true LQT3-causative mutations from background genetic noise is essential. OBJECTIVE: The purpose of this study was to assess the use of the lidocaine attenuation test (LAT) in evaluating patients with possible LQT3...
April 13, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28405995/recurrent-ventricular-tachycardia-due-to-long-qt-syndrome
#13
Rambabu Singh, Kshitiz Nath, Archana
Long QT syndrome (LQTS) is a rare inherited heart condition in which delayed repolarization of the heart following a heartbeat, increases the risk of episodes of Torsades de pointes (TdP, a form of irregular heartbeat that originates from the ventricles). These episodes may lead to palpitations, fainting, and sudden death due to ventricular fibrillation. Episodes may be provoked by various stimuli, depending on the subtype of the condition. We are reporting a case of 37 years old male whom we diagnosed to have long QT syndrome on the basis of clinical and ECG findings...
December 2016: Journal of the Association of Physicians of India
https://www.readbyqxmd.com/read/28400316/glucose-ingestion-causes-cardiac-repolarization-disturbances-in-type-1-long-qt-syndrome-patients-and-healthy-subjects
#14
Louise Hyltén-Cavallius, Eva W Iepsen, Michael Christiansen, Claus Graff, Allan Linneberg, Oluf Pedersen, Jens J Holst, Torben Hansen, Signe S Torekov, Jørgen K Kanters
BACKGROUND: Both hypoglycemia and severe hyperglycemia constitute known risk factors for cardiac repolarization changes potentially leading to malignant arrhythmias. Patients with loss of function mutations in KCNQ1 are characterized by long QT syndrome (LQTS) and may be at increased risk for glucose-induced repolarization disturbances. OBJECTIVE: The purpose of this study was to test the hypothesis that KCNQ1 LQTS patients are at particular risk for cardiac repolarization changes during the relative hyperglycemia that occurs after an oral glucose load...
April 9, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28391114/genotype-phenotype-dilemma-in-a-case-of-sudden-cardiac-death-with-the-e1053k-mutation-and-a-deletion-in-the-scn5a-gene
#15
T Jenewein, B M Beckmann, S Rose, H H Osterhues, U Schmidt, C Wolpert, P Miny, C Marschall, M Alders, C R Bezzina, A A M Wilde, S Kääb, S Kauferstein
Mutations in the cardiac sodium channel gene SCN5A may result in various arrhythmia syndromes such as long QT syndrome type 3 (LQTS), Brugada syndrome (BrS), sick sinus syndrome (SSS), cardiac conduction diseases (CCD) and possibly dilated cardiomyopathy (DCM). In most of these inherited cardiac arrhythmia syndromes the phenotypical expression may range from asymptomatic phenotypes to sudden cardiac death (SCD). A 16-year-old female died during sleep. Autopsy did not reveal any explanation for her death and a genetic analysis was performed...
March 20, 2017: Forensic Science International
https://www.readbyqxmd.com/read/28382321/electrophysiological-mechanisms-of-long-and-short-qt-syndromes
#16
REVIEW
Gary Tse, Yin Wah Fiona Chan, Wendy Keung, Bryan P Yan
The QT interval on the human electrocardiogram is normally in the order of 450 ms, and reflects the summated durations of action potential (AP) depolarization and repolarization of ventricular myocytes. Both prolongation and shortening in the QT interval have been associated with ventricular tachy-arrhythmias, which predispose affected individuals to sudden cardiac death. In this article, the molecular determinants of the AP duration and the causes of long and short QT syndromes (LQTS and SQTS) are explored...
March 2017: IJC Heart & Vasculature
https://www.readbyqxmd.com/read/28369767/multiple-targets-for-flecainide-action-implications-for-cardiac-arrhythmogenesis
#17
REVIEW
Samantha C Salvage, Karthik H Chandrasekharan, Kamalan Jeevaratnam, Angela F Dulhunty, Andrew J Thompson, Antony P Jackson, Christopher L-H Huang
Flecainide suppresses cardiac tachyarrhythmias including paroxysmal atrial fibrillation, supraventricular tachycardia and arrhythmic long QT syndromes (LQTS), as well as the Ca(2+) -mediated, catecholaminergic polymorphic ventricular tachycardia (CPVT). However, flecainide can also exert pro-arrhythmic effects most notably following myocardial infarction and when used to diagnose Brugada syndrome (BrS). These divergent actions result from its physiological and pharmacological actions at multiple, interacting levels of cellular organization...
April 3, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28343764/channelopathies-genetic-testing-and-risk-stratification
#18
Arthur A M Wilde, Ahmad Amin
The cardiac channelopathies are a group of diseases with (disease-) specific electrocardiographic (ECG) characteristics and a disease-specific risk of sudden cardiac death (SCD). This group includes the Long QT Syndromes (LQTS), Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), Brugada Syndrome (BrS), Short QT Syndromes (SQTS), and Early Repolarization Syndrome (ERS). In the past 2 decades the genetic basis for these disease entities has largely been unraveled and that, together with the identification of the genetic basis of the cardiomyopathies, has paved the way for the complete new field of Cardiogenetics...
March 18, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28340026/high-rate-of-subcutaneous-implantable-cardioverter-defibrillator-sensing-screening-failure-in-patients-with-brugada-syndrome-a-comparison-with-other-inherited-primary-arrhythmia-syndromes
#19
Giulio Conte, Mihoko Kawabata, Carlo de Asmundis, Erika Taravelli, Francesco Petracca, Diego Ruggiero, Maria Luce Caputo, François Regoli, Gian-Battista Chierchia, Alessandra Chiodini, Alessandro Del Bufalo, Tiziano Moccetti, Masahiko Goya, Kenzo Hirao, Alessandro Vicentini, Gaetano M De Ferrari, Pedro Brugada, Angelo Auricchio
Aims: Subcutaneous implantable cardioverter-defibrillator (S-ICD) can avoid important complications associated with transvenous leads in patients with inherited primary arrhythmia syndromes, who do not need pacing therapy. Few data are available on the percentage of patients with inherited arrhythmia syndromes eligible for S-ICD implantation. Aim of this study was to analyse the eligibility for S-ICD in a series of patients with Brugada syndrome (BrS), and to compare it with patients with other channelopathies...
March 7, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28336205/andersen-tawil-syndrome-clinical-presentation-and-predictors-of-symptomatic-arrhythmias-possible-role-of-polymorphisms-k897t-in-kcnh2-and-h558r-in-scn5a-gene
#20
Michalina Krych, Elżbieta Katarzyna Biernacka, Joanna Ponińska, Piotr Kukla, Artur Filipecki, Robert Gajda, Can Hasdemir, Charles Antzelevitch, Agnieszka Kosiec, Małgorzata Szperl, Rafał Płoski, Maria Trusz-Gluza, Katarzyna Mizia-Stec, Piotr Hoffman
BACKGROUND: Andersen-Tawil syndrome (ATS) is rare channelopathy caused by KCNJ2 mutation and probably KCNJ5. It is characterized by arrhythmias, neurological symptoms, and dysmorphic features. The present study retrospectively examined the characteristics of 11 unrelated families with ATS. METHODS: This study consisted of 11 probands positive for KCNJ2 variants and 33 family members (mean age 30.0±17.3 years, female n=31). Additional genetic screening of 3 LQTS genes (KCNQ1, KCNH2, SCN5A) was performed in 9 families...
March 20, 2017: Journal of Cardiology
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