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Long qt syndrome

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https://www.readbyqxmd.com/read/28096388/competition-of-calcified-calmodulin-n-lobe-and-pip2-to-an-lqt-mutation-site-in-kv7-1-channel
#1
William Sam Tobelaim, Meidan Dvir, Guy Lebel, Meng Cui, Tal Buki, Asher Peretz, Milit Marom, Yoni Haitin, Diomedes E Logothetis, Joel Alan Hirsch, Bernard Attali
Voltage-gated potassium 7.1 (Kv7.1) channel and KCNE1 protein coassembly forms the slow potassium current IKS that repolarizes the cardiac action potential. The physiological importance of the IKS channel is underscored by the existence of mutations in human Kv7.1 and KCNE1 genes, which cause cardiac arrhythmias, such as the long-QT syndrome (LQT) and atrial fibrillation. The proximal Kv7.1 C terminus (CT) binds calmodulin (CaM) and phosphatidylinositol-4,5-bisphosphate (PIP2), but the role of CaM in channel function is still unclear, and its possible interaction with PIP2 is unknown...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28066143/acepromazine-inhibits-herg-potassium-ion-channels-expressed-in-human-embryonic-kidney-293-cells
#2
Young Shin Joo, Hong Joon Lee, Jin-Sung Choi, Ki-Wug Sung
The effects of acepromazine on human ether-à-go-go-related gene (hERG) potassium channels were investigated using whole-cell voltage-clamp technique in human embryonic kidney (HEK293) cells transfected with hERG. The hERG currents were recorded with or without acepromazine, and the steady-state and peak tail currents were analyzed for the evaluating the drug effects. Acepromazine inhibited the hERG currents in a concentration-dependent manner with an IC50 value of 1.5 µM and Hill coefficient of 1.1. Acepromazine blocked hERG currents in a voltage-dependent manner between -40 and +10 mV...
January 2017: Korean Journal of Physiology & Pharmacology
https://www.readbyqxmd.com/read/28055993/-fever-and-sudden-death-a-reality-illustrative-case-report
#3
Carlos Rodríguez-Artuza, Juan Osorio, Freddy Madueño, Agustín Payares
The connection between fever and sudden death due to ventricular tachycardia has been usually reported in Brugada Syndrome. However the thermosensitive effects caused by fever have been recently described as a possible cause of sudden death in congenital long QT type II syndrome and in idiopathic ventricular fibrillation syndrome. We present a case where fever unmasked a congenital long QT type II syndrome.
November 21, 2016: Medwave
https://www.readbyqxmd.com/read/28049825/tbx20-controls-the-expression-of-the-kcnh2-gene-and-of-herg-channels
#4
Ricardo Caballero, Raquel G Utrilla, Irene Amorós, Marcos Matamoros, Marta Pérez-Hernández, David Tinaquero, Silvia Alfayate, Paloma Nieto-Marín, Guadalupe Guerrero-Serna, Qing-Hua Liu, Roberto Ramos-Mondragón, Daniela Ponce-Balbuena, Todd Herron, Katherine F Campbell, David Filgueiras-Rama, Rafael Peinado, José L López-Sendón, José Jalife, Eva Delpón, Juan Tamargo
Long QT syndrome (LQTS) exhibits great phenotype variability among family members carrying the same mutation, which can be partially attributed to genetic factors. We functionally analyzed the KCNH2 (encoding for Kv11.1 or hERG channels) and TBX20 (encoding for the transcription factor Tbx20) variants found by next-generation sequencing in two siblings with LQTS in a Spanish family of African ancestry. Affected relatives harbor a heterozygous mutation in KCNH2 that encodes for p.T152HfsX180 Kv11.1 (hERG). This peptide, by itself, failed to generate any current when transfected into Chinese hamster ovary (CHO) cells but, surprisingly, exerted "chaperone-like" effects over native hERG channels in both CHO cells and mouse atrial-derived HL-1 cells...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28039126/are-olympic-athletes-free-from-cardiovascular-diseases-systematic-investigation-in-2352-participants-from-athens-2004-to-sochi-2014
#5
Antonio Pelliccia, Paolo Emilio Adami, Filippo Quattrini, Maria Rosaria Squeo, Stefano Caselli, Luisa Verdile, Viviana Maestrini, Fernando Di Paolo, Cataldo Pisicchio, Roberto Ciardo, Antonio Spataro
CONTEXT: Olympic athletes represent model of success in our society, by enduring strenuous conditioning programmes and achieving astonishing performances. They also raise scientific and clinical interest, with regard to medical care and prevalence of cardiovascular (CV) abnormalities. OBJECTIVE: Our aim was to assess the prevalence and type of CV abnormalities in this selected athlete's cohort. DESIGN, SETTING AND PARTICIPANTS: 2352 Olympic athletes, mean age 25±6, 64% men, competing in 31 summer or 15 winter sports, were examined with history, physical examination, 12-lead and exercise ECG and echocardiography...
December 30, 2016: British Journal of Sports Medicine
https://www.readbyqxmd.com/read/28024120/ion-channels-long-qt-syndrome-and-arrhythmogenesis-in-ageing
#6
Kamalan Jeevaratnam, Karan R Chadda, Samantha C Salvage, Haseeb Valli, Shiraz Ahmad, Andrew A Grace, Christopher L-H Huang
Ageing is associated with increased prevalences of both atrial and ventricular arrhythmias, reflecting disruption of the normal sequence of ion channel activation and inactivation generating the propagated cardiac action potential. Experimental models with specific ion channel genetic modifications have helped clarify the interacting functional roles of ion channels and how their dysregulation contributes to arrhythmogenic processes at the cellular and systems level. They have also investigated interactions between these ion channel abnormalities and age-related processes in producing arrhythmic tendency...
December 26, 2016: Clinical and Experimental Pharmacology & Physiology
https://www.readbyqxmd.com/read/28012188/video-assisted-thoracoscopic-left-cardiac-sympathetic-denervation-in-patients-with-hereditary-ventricular-arrhythmias
#7
Se Yong Jang, Yongkeun Cho, Nam Kyun Kim, Chang-Yeon Kim, Jihyun Sohn, Jae-Hyung Roh, Myung Hwan Bae, Jang Hoon Lee, Dong Heon Yang, Hun Sik Park, Shung Chull Chae, Tak-Hyuk Oh, Gun Jik Kim
BACKGROUND: Left cardiac sympathetic denervation (LCSD) has been underutilized in patients with hereditary ventricular arrhythmia syndromes such as congenital long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). The purpose of this study was to investigate the safety and efficacy of video-assisted thoracoscopic (VATS) LCSD in such patients. METHODS: Fifteen patients (4 men, 24.6 ± 10.5 years old) who underwent VATS-LCSD between November 2010 and January 2015 for hereditary ventricular arrhythmia syndromes at Kyungpook National University Hospital were enrolled in this study...
December 24, 2016: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28011106/a-novel-scn5a-mutation-found-in-a-familial-case-of-long-qt-syndrome-complicated-by-severe-left-ventricular-dysfunction
#8
Mai Kimura, Takashi Kohno, Yoshiyasu Aizawa, Taku Inohara, Yasuyuki Shiraishi, Yoshinori Katsumata, Toru Egashira, Hiroyuki Fukushima, Kenjiro Kosaki, Keiichi Fukuda
A 16-year-old boy with long QT syndrome type 3 (LQT3) was admitted for decompensated heart failure resulting from dilated cardiomyopathy (DCM). His brother was also diagnosed with LQT3 and DCM. A comprehensive genetic analysis identified a novel SCN5A missense mutation-p.Q371E-in these 2 affected living family members. It might be important to suspect the coexistence of DCM and LQT3 (which is rare according to previous articles) in cases with this novel SCN5A missense mutation.
October 20, 2016: Canadian Journal of Cardiology
https://www.readbyqxmd.com/read/28003625/gene-targeted-analysis-of-clinically-diagnosed-long-qt-russian-families
#9
Paolo Enrico Maltese, Nina Orlova, Eugenia Krasikova, Elena Emelyanchik, Anna Cheremisina, Alina Kuscaeva, Alla Salmina, Roberta Miotto, Alice Bonizzato, Giulia Guerri, Monia Zuntini, Svetlana Nicoulina, Matteo Bertelli
Long QT syndrome (LQTS) has great genetic heterogeneity: more than 500 mutations have been described in several genes. Despite many advances, a genetic diagnosis still cannot be established in 25-30% of patients. The aim of the present study was to perform genetic evaluation in 9 Russian families with LQTS; here we report the results of 4 positive probands and their relatives (a total of 16 individuals). All subjects underwent clinical examination, 12-lead ECG, and Holter monitoring. Genetic analysis of the 14 genes mainly involved in LQTS was performed using a next-generation sequencing approach...
December 21, 2016: International Heart Journal
https://www.readbyqxmd.com/read/27998983/bag1-promotes-trc8-dependent-degradation-of-misfolded-herg-potassium-channels
#10
Christine Hantouche, Brittany Williamson, William C Valinsky, Joshua Solomon, Alvin Shrier, Jason C Young
Cardiac long QT syndrome type 2 is caused by mutations in the hERG potassium channel, many of which cause misfolding and degradation at the endoplasmic reticulum, instead of normal trafficking to the cell surface. The Hsc70/Hsp70 chaperones assist the folding of the hERG cytosolic domains. Here, we demonstrate that the Hsp70 nucleotide exchange factor Bag1 promotes hERG degradation by the ubiquitin-proteasome system at the endoplasmic reticulum, to regulate hERG levels and channel activity. Dissociation of hERG complexes containing Hsp70 and the E3 ubiquitin ligase CHIP requires the interaction of Bag1 with Hsp70 but this does not involve the Bag1 ubiquitin-like domain...
December 20, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27997884/the-natural-plant-product-rottlerin-activates-kv7-1-kcne1-channels
#11
Veronika Matschke, Ilaria Piccini, Janina Schubert, Eva Wrobel, Florian Lang, Johann Matschke, Elsie Amedonu, Sven G Meuth, Timo Strünker, Nathalie Strutz-Seebohm, Boris Greber, Jürgen Scherkenbeck, Guiscard Seebohm
BACKGROUND/AIMS: Acquired as well as inherited channelopathies are disorders that are caused by altered ion channel function. A family of channels whose malfunction is associated with different channelopathies is the Kv7 K+ channel family; and restoration of normal Kv7 channel function by small molecule modulators is a promising approach for treatment of these often fatal diseases. METHODS: Here, we show the modulation of Kv7 channels by the natural compound Rottlerin heterologously expressed in Xenopus laevis oocytes and on iPSC cardiomyocytes overexpressing Kv7...
2016: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/27996317/cardiac-arrest-with-clozapine-and-olanzapine-revealing-long-qt-syndrome
#12
Edward Woloszyn, Nishant Whig, Eileen Trigoboff, Jeffery J Grace
The authors describe a rare case of "concealed" congenital Long QT Syndrome (LQTS) Type 3 in a patient with treatment resistant schizophrenia and no known personal or family history of cardiac disease. The patient in this Case Report had a hidden genetic condition revealed only following the essential administration of antipsychotics. As a result, this patient experienced an aborted cardiac arrest and a total of five episodes of ventricular tachycardia (VT) requiring cardioversion. Successful control of the VT occurred with an Automatic Internal Defibrillator (AID), judicious use of antipsychotic medications, and anti-arrhythmic medications...
December 20, 2016: Clinical Schizophrenia & related Psychoses
https://www.readbyqxmd.com/read/27988060/syncope-and-risk-of-sudden-cardiac-arrest-in-coronary-artery-disease
#13
Aapo L Aro, Carmen Rusinaru, Audrey Uy-Evanado, Kyndaron Reinier, Derek Phan, Karen Gunson, Jonathan Jui, Sumeet S Chugh
BACKGROUND: Syncope has been associated with increased risk of sudden cardiac arrest (SCA) in specific patient populations, such as hypertrophic cardiomyopathy, heart failure, and long QT syndrome, but data are lacking on the risk of SCA associated with syncope among patients with coronary artery disease (CAD), the most common cause of SCA. We investigated this association among CAD patients in the community. METHODS: All cases of SCA due to CAD were prospectively identified in Portland, Oregon (population approximately 1 million) as part of the Oregon Sudden Unexpected Death Study 2002-2015, and compared to geographical controls...
December 12, 2016: International Journal of Cardiology
https://www.readbyqxmd.com/read/27968776/the-electrocardiogram-of-the-neonate-and-infant
#14
Konrad Brockmeier, Rewa Nazal, Narayanswami Sreeram
The ECG in children has a number of characteristic differences compared to the ECG of the adult. The transition of the ECG in neonates after birth represents dynamic changes of the circulatory system due to the postnatal adaptation, different physiologic properties of the fetal and neonatal myocardium, the location and orientation of the heart in the chest and influence of body mass during that period and later on in childhood. The complexity of the changes implies a broad variation of ECG changes during the first days and weeks of life, whose interpretation requires expert knowledge...
November 2016: Journal of Electrocardiology
https://www.readbyqxmd.com/read/27936942/implantable-cardioverter-defibrillator-treatment-in-long-qt-syndrome-patients-a-national-study-on-adherence-to-international-guidelines
#15
Emilia Sundström, Steen M Jensen, Ulla-Britt Diamant, Annika Rydberg
OBJECTIVES: Implantable cardioverter defibrillator (ICD) treatment is effective among long QT syndrome (LQTS) patients at a high risk of sudden cardiac death. Previous studies show that the international guidelines are not always followed, and that risk stratification may be based on genotype rather than individual risk profile. We analysed data from the Swedish ICD & Pacemaker Registry and medical records to examine how international guidelines were followed with regards to phenotype and genotype...
December 30, 2016: Scandinavian Cardiovascular Journal: SCJ
https://www.readbyqxmd.com/read/27921062/long-qt-syndrome-and-duodenal-ampullary-adenoma-a-new-association
#16
F N U Asad-Ur-Rahman, Laura Hughes, Muhammad Talha Khan, Muhammad Khalid Hasan, Irteza Inayat
KCNQ1 gene mutation has a well-known association with long QT syndrome (LQTS). However, recent studies suggest that it may be implicated in intestinal neoplasia. We present a 27-year-old Hispanic man with a known history of LQTS secondary to KCNQ1 mutation, who presented with painless jaundice. Endoscopic retrograde pancreatic cholangiography revealed a prominent ampulla, with histology consistent with ampullary adenoma with high-grade dysplasia. Further endoscopic studies did not suggest familial adenomatous polyposis...
August 2016: ACG Case Reports Journal
https://www.readbyqxmd.com/read/27920829/clinical-and-genetic-features-of-australian-families-with-long-qt-syndrome-a-registry-based-study
#17
Charlotte Burns, Jodie Ingles, Andrew M Davis, Vanessa Connell, Belinda Gray, Lauren Hunt, Julie McGaughran, Christopher Semsarian
BACKGROUND: Familial long QT syndrome (LQTS) is a primary arrhythmogenic disorder caused by mutations in ion channel genes. The phenotype ranges from asymptomatic individuals to sudden cardiac arrest and death. LQTS is a rare but significant health problem for which global data should exist. This study sought to provide the first clinical and genetic description of Australian families with LQTS. METHODS: We performed a cross-sectional study to evaluate clinical and genetic features of families with LQTS...
December 2016: Journal of Arrhythmia
https://www.readbyqxmd.com/read/27916661/tetrameric-assembly-of-k-channels-requires-er-located-chaperone-proteins
#18
Kai Li, Qiang Jiang, Xue Bai, Yi-Feng Yang, Mei-Yu Ruan, Shi-Qing Cai
Tetrameric assembly of channel subunits in the endoplasmic reticulum (ER) is essential for surface expression and function of K(+) channels, but the molecular mechanism underlying this process remains unclear. In this study, we found through genetic screening that ER-located J-domain-containing chaperone proteins (J-proteins) are critical for the biogenesis and physiological function of ether-a-go-go-related gene (ERG) K(+) channels in both Caenorhabditis elegans and human cells. Human J-proteins DNAJB12 and DNAJB14 promoted tetrameric assembly of ERG (and Kv4...
January 5, 2017: Molecular Cell
https://www.readbyqxmd.com/read/27915266/systematic-ajmaline-challenge-in-patients-with-long-qt-3-syndrome-caused-by-the-most-common-mutation-a-multicentre-study
#19
Stephan Hohmann, Boris Rudic, Torsten Konrad, David Duncker, Thorben König, Erol Tülümen, Thomas Rostock, Martin Borggrefe, Christian Veltmann
AIMS: Overlap syndromes of long QT 3 syndrome (LQT3) and the Brugada syndrome (BrS) have been reported. Identification of patients with an overlapping phenotype is crucial before initiation of Class I antiarrhythmic drugs for LQT3. Aim of the present study was to elucidate the yield of ajmaline challenge in unmasking the Brugada phenotype in patients with LQT3 caused by the most common mutation, SCN5A-E1784K. METHODS AND RESULTS: Consecutive families in tertiary referral centres diagnosed with LQT3 caused by SCN5A-E1784K were included in the study...
December 2, 2016: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/27903879/the-analysis-of-qt-interval-and-repolarization-morphology-of-the-heart-in-chronic-exposure-to-lead
#20
J Kiełtucki, M Dobrakowski, N Pawlas, B Średniawa, M Boroń, S Kasperczyk
There are no common recommendations regarding electrocardiographic monitoring in occupationally exposed workers. Therefore, the present study was designed to investigate whether exposure to lead results in an increase of selected electrocardiography (ECG) pathologies, such as QT interval prolongation and repolarization disorders, in occupationally exposed workers. The study group included 180 workers occupationally exposed to lead compounds. The exposed group was divided according to the median of the mean blood lead level (PbBmean) calculated based on a series of measurements performed during 5-year observation period (35 µg/dl) into two subgroups: low exposure (LE, PbBmean = 20...
November 30, 2016: Human & Experimental Toxicology
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