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Kang PW, Woodbury L, Angsutararux P, Sambare N, Shi J, Marras M, Abella C, Bedi A, Zinn D, Cui J, Silva JR. Arrhythmia-associated calmodulin variants interact with KCNQ1 to confer aberrant membrane trafficking and function. PNAS Nexus 2023; 2:pgad335. [PMID: 37965565 PMCID: PMC10642763 DOI: 10.1093/pnasnexus/pgad335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 10/04/2023] [Indexed: 11/16/2023]
Abstract
Missense variants in calmodulin (CaM) predispose patients to arrhythmias associated with high mortality rates ("calmodulinopathy"). As CaM regulates many key cardiac ion channels, an understanding of disease mechanism associated with CaM variant arrhythmias requires elucidating individual CaM variant effects on distinct channels. One key CaM regulatory target is the KCNQ1 (KV7.1) voltage-gated potassium channel that carries the IKs current. Yet, relatively little is known as to how CaM variants interact with KCNQ1 or affect its function. Here, we take a multipronged approach employing a live-cell fluorescence resonance energy transfer binding assay, fluorescence trafficking assay, and functional electrophysiology to characterize >10 arrhythmia-associated CaM variants for effect on KCNQ1 CaM binding, membrane trafficking, and channel function. We identify one variant (G114W) that exhibits severely weakened binding to KCNQ1 but find that most other CaM variants interact with similar binding affinity to KCNQ1 when compared with CaM wild-type over physiological Ca2+ ranges. We further identify several CaM variants that affect KCNQ1 and IKs membrane trafficking and/or baseline current activation kinetics, thereby delineating KCNQ1 dysfunction in calmodulinopathy. Lastly, we identify CaM variants with no effect on KCNQ1 function. This study provides extensive functional data that reveal how CaM variants contribute to creating a proarrhythmic substrate by causing abnormal KCNQ1 membrane trafficking and current conduction. We find that CaM variant regulation of KCNQ1 is not uniform with effects varying from benign to significant loss of function, suggesting how CaM variants predispose patients to arrhythmia via the dysregulation of multiple cardiac ion channels. Classification: Biological, Health, and Medical Sciences, Physiology.
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Affiliation(s)
- Po wei Kang
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Lucy Woodbury
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Namit Sambare
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Martina Marras
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Carlota Abella
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Anish Bedi
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - DeShawn Zinn
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
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2
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Lesage A, Lorenzini M, Burel S, Sarlandie M, Bibault F, Lindskog C, Maloney D, Silva JR, Townsend RR, Nerbonne JM, Marionneau C. Determinants of iFGF13-mediated regulation of myocardial voltage-gated sodium (NaV) channels in mouse. J Gen Physiol 2023; 155:e202213293. [PMID: 37516919 PMCID: PMC10374952 DOI: 10.1085/jgp.202213293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/14/2023] [Accepted: 06/30/2023] [Indexed: 07/31/2023] Open
Abstract
Posttranslational regulation of cardiac NaV1.5 channels is critical in modulating channel expression and function, yet their regulation by phosphorylation of accessory proteins has gone largely unexplored. Using phosphoproteomic analysis of NaV channel complexes from adult mouse left ventricles, we identified nine phosphorylation sites on intracellular fibroblast growth factor 13 (iFGF13). To explore the potential roles of these phosphosites in regulating cardiac NaV currents, we abolished expression of iFGF13 in neonatal and adult mouse ventricular myocytes and rescued it with wild-type (WT), phosphosilent, or phosphomimetic iFGF13-VY. While the increased rate of closed-state inactivation of NaV channels induced by Fgf13 knockout in adult cardiomyocytes was completely restored by adenoviral-mediated expression of WT iFGF13-VY, only partial rescue was observed in neonatal cardiomyocytes after knockdown. The knockdown of iFGF13 in neonatal ventricular myocytes also shifted the voltage dependence of channel activation toward hyperpolarized potentials, a shift that was not reversed by WT iFGF13-VY expression. Additionally, we found that iFGF13-VY is the predominant isoform in adult ventricular myocytes, whereas both iFGF13-VY and iFGF13-S are expressed comparably in neonatal ventricular myocytes. Similar to WT iFGF13-VY, each of the iFGF13-VY phosphomutants studied restored NaV channel inactivation properties in both models. Lastly, Fgf13 knockout also increased the late Na+ current in adult cardiomyocytes, and this effect was restored with expression of WT and phosphosilent iFGF13-VY. Together, our results demonstrate that iFGF13 is highly phosphorylated and displays differential isoform expression in neonatal and adult ventricular myocytes. While we found no roles for iFGF13 phosphorylation, our results demonstrate differential effects of iFGF13 on neonatal and adult mouse ventricular NaV channels.
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Affiliation(s)
- Adrien Lesage
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Maxime Lorenzini
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Sophie Burel
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Marine Sarlandie
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Floriane Bibault
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Cecilia Lindskog
- Department of Immunology, Genetics and Pathology, Cancer Precision Medicine, Uppsala University, Uppsala, Sweden
| | | | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - R. Reid Townsend
- Department of Cell Biology and Physiology, Washington University Medical School, St. Louis, MO, USA
- Department of Medicine, Washington University Medical School, St. Louis, MO, USA
| | - Jeanne M. Nerbonne
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
- Department of Medicine, Washington University Medical School, St. Louis, MO, USA
- Department of Developmental Biology, Washington University Medical School, St. Louis, MO, USA
| | - Céline Marionneau
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
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3
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Bloom D, Catherall D, Miller N, Southworth MK, Glatz AC, Silva JR, Avari Silva JN. Use of a mixed reality system for navigational mapping during cardiac electrophysiological testing does not prolong case duration: A subanalysis from the Cardiac Augmented REality study. Cardiovasc Digit Health J 2023; 4:111-117. [PMID: 37600447 PMCID: PMC10435945 DOI: 10.1016/j.cvdhj.2023.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2023] Open
Abstract
Background CommandEP™ is a mixed reality (MXR) system for cardiac electrophysiological (EP) procedures that provides a real-time 3-dimensional digital image of cardiac geometry and catheter locations. In a previous study, physicians using the system demonstrated improved navigational accuracy. This study investigated the impact of the CommandEP system on EP procedural times compared to the standard-of-care electroanatomic mapping system (EAMS) display. Objective The purpose of this retrospective case-controlled analysis was to evaluate the impact of a novel MXR interface on EP procedural times compared to a case-matched cohort. Methods Cases from the Cardiac Augmented REality (CARE) study were matched for diagnosis and weight using a contemporary cohort. Procedural time was compared from the roll-in and full implementation cohort. During routine EP procedures, operators performed tasks during the postablation waiting phase, including creation of cardiac geometry and 5-point navigation under 2 conditions: (1) EAMS first; and (2) CommandEP. Results From a total of 16 CARE study patients, the 10 full implementation patients were matched to a cohort of 20 control patients (2 controls:1 CARE, matched according to pathology and age/weight). No statistical difference in total case times between CARE study patients vs control group (118 ± 29 minutes vs 97 ± 20 minutes; P = .07) or fluoroscopy times (6 ± 4 minutes vs 7 ± 6 minutes; P = .9). No significant difference in case duration for CARE study patients comparing roll-in vs full-implementation cohort (121 ± 26 minutes vs 118 ± 29 minutes; P = .96). CommandEP wear time during cases was significantly longer in full implementation cases (53 ± 24 minutes vs 24 ± 5 minutes; P = .0009). During creation of a single cardiac geometry, no significant time difference was noted between CommandEP vs EAMS (284 ± 45 seconds vs 268 ± 43 seconds; P = .1) or fluoroscopy use (9 ± 19 seconds vs 6 ± 18 seconds; P = .25). During point navigation tasks, there was no difference in total time (CommandEP 31 ± 14 seconds vs EAMS 28 ± 15 seconds; P = .16) or fluoroscopy time (CommandEP 0 second vs EAMS 0 second). Conclusion MXR did not prolong overall procedural time compared to a matched cohort. There was no prolongation in study task completion time. Future studies with experienced CommandEP users directly assessing procedural time and task completion time in a randomized study population would be of interest.
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Affiliation(s)
- David Bloom
- Department of Pediatrics, Division of Cardiology, Washington University in St. Louis, School of Medicine, St. Louis, Missouri
| | - David Catherall
- School of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Nathan Miller
- Pediatric Cardiology/Electrophysiology, St. Louis Children’s Hospital, St. Louis, Missouri
| | | | - Andrew C. Glatz
- Department of Pediatrics, Division of Cardiology, Washington University in St. Louis, School of Medicine, St. Louis, Missouri
| | - Jonathan R. Silva
- SentiAR, Inc., St. Louis, Missouri
- Department of Biomedical Engineering. Washington University in St. Louis, McKelvey School of Engineering, St. Louis, Missouri
| | - Jennifer N. Avari Silva
- Department of Pediatrics, Division of Cardiology, Washington University in St. Louis, School of Medicine, St. Louis, Missouri
- SentiAR, Inc., St. Louis, Missouri
- Department of Biomedical Engineering. Washington University in St. Louis, McKelvey School of Engineering, St. Louis, Missouri
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Hanson A, McClenaghan C, Weng KC, Colijn S, Stratman AN, Halabi CM, Grange DK, Silva JR, Nichols CG. Electrophysiology of human iPSC-derived vascular smooth muscle cells and cell autonomous consequences of Cantu Syndrome mutations. bioRxiv 2023:2023.06.29.547088. [PMID: 37425756 PMCID: PMC10327170 DOI: 10.1101/2023.06.29.547088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Objective Cantu Syndrome (CS), a multisystem disease with a complex cardiovascular phenotype, is caused by GoF variants in the Kir6.1/SUR2 subunits of ATP-sensitive potassium (K ATP ) channels, and is characterized by low systemic vascular resistance, as well as tortuous, dilated vessels, and decreased pulse-wave velocity. Thus, CS vascular dysfunction is multifactorial, with distinct hypomyotonic and hyperelastic components. To dissect whether such complexities arise cell-autonomously within vascular smooth muscle cells (VSMCs), or as secondary responses to the pathophysiological milieu, we assessed electrical properties and gene expression in human induced pluripotent stem cell-derived VSMCs (hiPSC-VSMCs), differentiated from control and CS patient-derived hiPSCs, and in native mouse control and CS VSMCs. Approach and Results Whole-cell voltage-clamp of isolated aortic and mesenteric VSMCs isolated from wild type (WT) and Kir6.1[V65M] (CS) mice revealed no difference in voltage-gated K + (K v ) or Ca 2+ currents. K v and Ca 2+ currents were also not different between validated hiPSC-VSMCs differentiated from control and CS patient-derived hiPSCs. Pinacidil-sensitive K ATP currents in control hiPSC-VSMCs were consistent with those in WT mouse VSMCs, and were considerably larger in CS hiPSC-VSMCs. Consistent with lack of any compensatory modulation of other currents, this resulted in membrane hyperpolarization, explaining the hypomyotonic basis of CS vasculopathy. Increased compliance and dilation in isolated CS mouse aortae, was associated with increased elastin mRNA expression. This was consistent with higher levels of elastin mRNA in CS hiPSC-VSMCs, suggesting that the hyperelastic component of CS vasculopathy is a cell-autonomous consequence of vascular K ATP GoF. Conclusions The results show that hiPSC-VSMCs reiterate expression of the same major ion currents as primary VSMCs, validating the use of these cells to study vascular disease. The results further indicate that both the hypomyotonic and hyperelastic components of CS vasculopathy are cell-autonomous phenomena driven by K ATP overactivity within VSMCs.
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5
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Angsutararux P, Dutta AK, Marras M, Abella C, Mellor RL, Shi J, Nerbonne JM, Silva JR. Differential regulation of cardiac sodium channels by intracellular fibroblast growth factors. J Gen Physiol 2023; 155:e202213300. [PMID: 36944081 PMCID: PMC10038838 DOI: 10.1085/jgp.202213300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/17/2023] [Accepted: 02/09/2023] [Indexed: 03/23/2023] Open
Abstract
Voltage-gated sodium (NaV) channels are responsible for the initiation and propagation of action potentials. In the heart, the predominant NaV1.5 α subunit is composed of four homologous repeats (I-IV) and forms a macromolecular complex with multiple accessory proteins, including intracellular fibroblast growth factors (iFGF). In spite of high homology, each of the iFGFs, iFGF11-iFGF14, as well as the individual iFGF splice variants, differentially regulates NaV channel gating, and the mechanisms underlying these differential effects remain elusive. Much of the work exploring iFGF regulation of NaV1.5 has been performed in mouse and rat ventricular myocytes in which iFGF13VY is the predominant iFGF expressed, whereas investigation into NaV1.5 regulation by the human heart-dominant iFGF12B is lacking. In this study, we used a mouse model with cardiac-specific Fgf13 deletion to study the consequences of iFGF13VY and iFGF12B expression. We observed distinct effects on the voltage-dependences of activation and inactivation of the sodium currents (INa), as well as on the kinetics of peak INa decay. Results in native myocytes were recapitulated with human NaV1.5 heterologously expressed in Xenopus oocytes, and additional experiments using voltage-clamp fluorometry (VCF) revealed iFGF-specific effects on the activation of the NaV1.5 voltage sensor domain in repeat IV (VSD-IV). iFGF chimeras further unveiled roles for all three iFGF domains (i.e., the N-terminus, core, and C-terminus) on the regulation of VSD-IV, and a slower time domain of inactivation. We present here a novel mechanism of iFGF regulation that is specific to individual iFGF isoforms and that leads to distinct functional effects on NaV channel/current kinetics.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Amal K. Dutta
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Martina Marras
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Carlota Abella
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Rebecca L. Mellor
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jeanne M. Nerbonne
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jonathan R. Silva
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
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6
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Moreno JD, Silva JR. Emerging methods to model cardiac ion channel and myocyte electrophysiology. Biophys Rev (Melville) 2023; 4:011315. [PMID: 37034130 PMCID: PMC10071990 DOI: 10.1063/5.0127713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 02/28/2023] [Indexed: 04/03/2023]
Abstract
In the field of cardiac electrophysiology, modeling has played a central role for many decades. However, even though the effort is well-established, it has recently seen a rapid and sustained evolution in the complexity and predictive power of the models being created. In particular, new approaches to modeling have allowed the tracking of parallel and interconnected processes that span from the nanometers and femtoseconds that determine ion channel gating to the centimeters and minutes needed to describe an arrhythmia. The connection between scales has brought unprecedented insight into cardiac arrhythmia mechanisms and drug therapies. This review focuses on the generation of these models from first principles, generation of detailed models to describe ion channel kinetics, algorithms to create and numerically solve kinetic models, and new approaches toward data gathering that parameterize these models. While we focus on application of these models for cardiac arrhythmia, these concepts are widely applicable to model the physiology and pathophysiology of any excitable cell.
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Affiliation(s)
- Jonathan D. Moreno
- Division of Cardiology, Department of Medicine, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
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7
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Lee L, Moreno JD, Silva JR. Predicting patient-specific single-cell parameters in computational cardiac models using machine learning. Biophys J 2023; 122:381a. [PMID: 36783939 DOI: 10.1016/j.bpj.2022.11.2090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Lucas Lee
- Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | | | - Jonathan R Silva
- Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
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8
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Lesage A, Lorenzini M, Burel S, Sarlandie M, Bibault F, Maloney D, Silva JR, Reid Townsend R, Nerbonne JM, Marionneau C. FHF2 phosphorylation and regulation of native myocardial Na V 1.5 channels. bioRxiv 2023:2023.01.31.526475. [PMID: 36778222 PMCID: PMC9915605 DOI: 10.1101/2023.01.31.526475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Phosphorylation of the cardiac Na V 1.5 channel pore-forming subunit is extensive and critical in modulating channel expression and function, yet the regulation of Na V 1.5 by phosphorylation of its accessory proteins remains elusive. Using a phosphoproteomic analysis of Na V channel complexes purified from mouse left ventricles, we identified nine phosphorylation sites on Fibroblast growth factor Homologous Factor 2 (FHF2). To determine the roles of phosphosites in regulating Na V 1.5, we developed two models from neonatal and adult mouse ventricular cardiomyocytes in which FHF2 expression is knockdown and rescued by WT, phosphosilent or phosphomimetic FHF2-VY. While the increased rates of closed-state and open-state inactivation of Na V channels induced by the FHF2 knockdown are completely restored by the FHF2-VY isoform in adult cardiomyocytes, sole a partial rescue is obtained in neonatal cardiomyocytes. The FHF2 knockdown also shifts the voltage-dependence of activation towards hyperpolarized potentials in neonatal cardiomyocytes, which is not rescued by FHF2-VY. Parallel investigations showed that the FHF2-VY isoform is predominant in adult cardiomyocytes, while expression of FHF2-VY and FHF2-A is comparable in neonatal cardiomyocytes. Similar to WT FHF2-VY, however, each FHF2-VY phosphomutant restores the Na V channel inactivation properties in both models, preventing identification of FHF2 phosphosite roles. FHF2 knockdown also increases the late Na + current in adult cardiomyocytes, which is restored similarly by WT and phosphosilent FHF2-VY. Together, our results demonstrate that ventricular FHF2 is highly phosphorylated, implicate differential roles for FHF2 in regulating neonatal and adult mouse ventricular Na V 1.5, and suggest that the regulation of Na V 1.5 by FHF2 phosphorylation is highly complex. eTOC Summary Lesage et al . identify the phosphorylation sites of FHF2 from mouse left ventricular Na V 1.5 channel complexes. While no roles for FHF2 phosphosites could be recognized yet, the findings demonstrate differential FHF2-dependent regulation of neonatal and adult mouse ventricular Na V 1.5 channels.
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9
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Kang PW, Woodbury L, Angsutararux P, Sambare N, Shi J, Marras M, Abella C, Bedi A, Zinn D, Cui J, Silva JR. Arrhythmia-associated Calmodulin Variants Interact with KCNQ1 to Confer Aberrant Membrane Trafficking and Function. bioRxiv 2023:2023.01.28.526031. [PMID: 36747728 PMCID: PMC9900995 DOI: 10.1101/2023.01.28.526031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Rationale Missense variants in calmodulin (CaM) predispose patients to arrhythmias associated with high mortality rates. As CaM regulates several key cardiac ion channels, a mechanistic understanding of CaM variant-associated arrhythmias requires elucidating individual CaM variant effect on distinct channels. One key CaM regulatory target is the KCNQ1 (K V 7.1) voltage-gated potassium channel that underlie the I Ks current. Yet, relatively little is known as to how CaM variants interact with KCNQ1 or affect its function. Objective To observe how arrhythmia-associated CaM variants affect binding to KCNQ1, channel membrane trafficking, and KCNQ1 function. Methods and Results We combine a live-cell FRET binding assay, fluorescence trafficking assay, and functional electrophysiology to characterize >10 arrhythmia-associated CaM variants effect on KCNQ1. We identify one variant (G114W) that exhibits severely weakened binding to KCNQ1 but find that most other CaM variants interact with similar binding affinity to KCNQ1 when compared to CaM wild-type over physiological Ca 2+ ranges. We further identify several CaM variants that affect KCNQ1 and I Ks membrane trafficking and/or baseline current activation kinetics, thereby contextualizing KCNQ1 dysfunction in calmodulinopathy. Lastly, we delineate CaM variants with no effect on KCNQ1 function. Conclusions This study provides comprehensive functional data that reveal how CaM variants contribute to creating a pro-arrhythmic substrate by causing abnormal KCNQ1 membrane trafficking and current conduction. We find that CaM variant regulation of KCNQ1 is not uniform with effects varying from benign to significant loss of function. This study provides a new approach to collecting details of CaM binding that are key for understanding how CaM variants predispose patients to arrhythmia via the dysregulation of multiple cardiac ion channels.
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10
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Zhang G, Xu X, Jia Z, Geng Y, Liang H, Shi J, Marras M, Abella C, Magleby KL, Silva JR, Chen J, Zou X, Cui J. An allosteric modulator activates BK channels by perturbing coupling between Ca 2+ binding and pore opening. Nat Commun 2022; 13:6784. [PMID: 36351900 PMCID: PMC9646747 DOI: 10.1038/s41467-022-34359-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 10/21/2022] [Indexed: 11/10/2022] Open
Abstract
BK type Ca2+-activated K+ channels activate in response to both voltage and Ca2+. The membrane-spanning voltage sensor domain (VSD) activation and Ca2+ binding to the cytosolic tail domain (CTD) open the pore across the membrane, but the mechanisms that couple VSD activation and Ca2+ binding to pore opening are not clear. Here we show that a compound, BC5, identified from in silico screening, interacts with the CTD-VSD interface and specifically modulates the Ca2+ dependent activation mechanism. BC5 activates the channel in the absence of Ca2+ binding but Ca2+ binding inhibits BC5 effects. Thus, BC5 perturbs a pathway that couples Ca2+ binding to pore opening to allosterically affect both, which is further supported by atomistic simulations and mutagenesis. The results suggest that the CTD-VSD interaction makes a major contribution to the mechanism of Ca2+ dependent activation and is an important site for allosteric agonists to modulate BK channel activation.
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Affiliation(s)
- Guohui Zhang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Xianjin Xu
- Dalton Cardiovascular Research Center, University of Missouri - Columbia, Columbia, MO, USA.,Department of Physics and Astronomy, University of Missouri - Columbia, Columbia, MO, USA.,Department of Biochemistry, University of Missouri - Columbia, Columbia, MO, USA.,Institute for Data Science and Informatics, University of Missouri - Columbia, Columbia, MO, USA
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA.,Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA
| | - Yanyan Geng
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Hongwu Liang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Martina Marras
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Carlota Abella
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Karl L Magleby
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA.
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA. .,Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA.
| | - Xiaoqin Zou
- Dalton Cardiovascular Research Center, University of Missouri - Columbia, Columbia, MO, USA. .,Department of Physics and Astronomy, University of Missouri - Columbia, Columbia, MO, USA. .,Department of Biochemistry, University of Missouri - Columbia, Columbia, MO, USA. .,Institute for Data Science and Informatics, University of Missouri - Columbia, Columbia, MO, USA.
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA.
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11
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Bloom D, K Southworth M, R Silva J, N Avari Silva J. The Expanding Uses of Medical Extended Reality in the Cardiac
Catheterization Laboratory: Pre-procedural Planning,
Intraprocedural Guidance, and Intraprocedural Navigation. US Cardiology Review 2022. [DOI: 10.15420/usc.2021.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The use of innovative imaging practices in the field of interventional cardiology and electrophysiology has led to significant progress in both diagnostic and therapeutic capabilities. 3D reconstructions of 2D images allows a proceduralist to develop a superior understanding of patient anatomy. Medical extended reality (MXR) technologies employ 3D interactive images for the user to improve depth perception and spatial awareness. Although MXR procedural navigation is a relatively new concept, the potential for use within interventional cardiology and EP is significant with the eventual goal of improving patient outcomes and reducing patient harm. This review article will discuss the current landscape of MXR use in the catheterization lab including pre-procedural planning, intraprocedural planning and intraprocedural guidance in diagnostic cardiac catheterization, valvar and coronary interventions, electrophysiology studies, and device implants.
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Affiliation(s)
- David Bloom
- Division of Pediatric Cardiology, School of Medicine, Washington University in St. Louis, St. Louis, MO
| | | | | | - Jennifer N Avari Silva
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO
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12
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Peres PVO, Silva JR, Cardoso RF, Costa VGM, Barbosa MR, Gabriel LHR, Borges MAF, Fernandes RD. O DESABASTECIMENTO DE IMUNOGLOBULINA INTRAVENOSA E O USO DE PLASMAFÉRESE EM PRIMEIRA LINHA NA SÍNDROME DE GUILLAIN – BARRÉ EM PACIENTE PEDIÁTRICO: RELATO DE CASO E REVISÃO DE LITERATURA. Hematol Transfus Cell Ther 2022. [DOI: 10.1016/j.htct.2022.09.853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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13
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Belchior SNF, Vidal ECF, Correia JG, Rodovalho LAB, Paiva LV, Lucena ALM, Biscuccia FA, Coutinho NB, Souza PC, Silva JR. IMPLANTAÇÃO DOS TESTES MICROBIOLÓGICOS EM 100% DAS PLAQUETAS PRODUZIDAS NO HEMOCENTRO REGIONAL DE CRATO NO CEARÁ: RELATO DE EXPERIÊNCIA. Hematol Transfus Cell Ther 2022. [DOI: 10.1016/j.htct.2022.09.621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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14
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Oguntuyo K, Schuftan D, Guo J, Simmons D, Bhagavan D, Moreno JD, Kang PW, Miller E, Silva JR, Huebsch N. Robust, Automated Analysis of Electrophysiology in Induced Pluripotent Stem Cell-Derived Micro-Heart Muscle for Drug Toxicity. Tissue Eng Part C Methods 2022; 28:457-468. [PMID: 35925789 PMCID: PMC9527045 DOI: 10.1089/ten.tec.2022.0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/19/2022] [Indexed: 11/12/2022] Open
Abstract
Drugs are often removed from clinical trials or market progression owing to their unforeseen effects on cardiac action potential and calcium handling. Induced pluripotent stem cell-derived cardiomyocytes and tissues fabricated from these cells are promising as screening tools for early identification of these potential cardiac liabilities. In this study, we describe an automated, open-source MATLAB-based analysis software for calculating cardiac action potentials and calcium transients from fluorescent reporters. We first identified the most robust manner in which to automatically identify the initiation point for action potentials and calcium transients in a user-independent manner, and used this approach to quantify the duration and morphology of these signals. We then demonstrate the software by assessing changes to action potentials and calcium transients in our micro-heart muscles after exposure to hydroxychloroquine, an antimalarial drug with known cardiac liability. Consistent with clinical observations, our system predicted mild action potential prolongation. However, we also observed marked calcium transient suppression, highlighting the advantage of testing multiple physiologic readouts in cardiomyocytes rather than relying on heterologous overexpression of single channels such as the human ether-a-go-go-related gene channel. This open-source software can serve as a useful, high-throughput tool for analyzing cardiomyocyte physiology from fluorescence imaging.
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Affiliation(s)
- Kasoorelope Oguntuyo
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - David Schuftan
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jingxuan Guo
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Daniel Simmons
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Druv Bhagavan
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jonathan D. Moreno
- Division of Cardiology, Department of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Po Wei Kang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Evan Miller
- Department of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Nathaniel Huebsch
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
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15
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Bloom D, Colombo JN, Miller N, Southworth MK, Andrews C, Henry A, Orr WB, Silva JR, Avari Silva JN. Early preclinical experience of a mixed reality ultrasound system with active GUIDance for NEedle-based interventions: The GUIDE study. Cardiovascular Digital Health Journal 2022; 3:232-240. [PMID: 36310686 PMCID: PMC9596321 DOI: 10.1016/j.cvdhj.2022.07.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Background Use of ultrasound (US) to facilitate vascular access has increased compared to landmark-based procedures despite ergonomic challenges and need for extrapolation of 2-dimensional images to understand needle position. The MantUS™ system (Sentiar, Inc.,) uses a mixed reality (MxR) interface to display US images and integrate real-time needle tracking. Objective The purpose of this prospective preclinical study was to evaluate the feasibility and usability of MantUS in a simulated environment. Methods Participants were recruited from pediatric cardiology and critical care. Access was obtained in 2 vascular access training models: a femoral access model and a head and neck model for a total of 4 vascular access sites under 2 conditions—conventional US and MantUS. Participants were randomized for order of completion. Videos were obtained, and quality of access including time required, repositions, number of attempts, and angle of approach were quantified. Results Use of MantUS resulted in an overall reduction in number of needle repositions (P = .03) and improvement in quality of access as measured by distance (P <.0001) and angle of elevation (P = .006). These findings were even more evident in the right femoral vein (RFV) access site, which was a simulated anatomic variant with a deeper more oblique vascular course. Use of MantUS resulted in faster time to access (P = .04), fewer number of both access attempts (P = .02), and number of needle repositions (P <.0001) compared to conventional US. Postparticipant survey showed high levels of usability (87%) and a belief that MantUS may decrease adverse outcomes (73%) and failed access attempts (83%). Conclusion Use of MantUS improved vascular access among all comers, including the quality of access. This improvement was even more notable in the vascular variant (RFV). MantUS readily benefited users by providing improved spatial understanding. Further development of MantUS will focus on improving user interface and experience, with larger clinical usage and in-human studies.
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Affiliation(s)
- David Bloom
- Division of Pediatric Cardiology, Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Jamie N. Colombo
- Division of Pediatric Cardiology, Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Nathan Miller
- Pediatric Electrophysiology Laboratory, St. Louis Children’s Hospital, St. Louis, Missouri
| | | | | | | | - William B. Orr
- Division of Pediatric Cardiology, Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Jonathan R. Silva
- Sentiar, Inc., St. Louis, Missouri
- Department of Biomedical Engineering, Washington University McKelvey School of Engineering, St. Louis, Missouri
| | - Jennifer N. Avari Silva
- Division of Pediatric Cardiology, Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
- Sentiar, Inc., St. Louis, Missouri
- Department of Biomedical Engineering, Washington University McKelvey School of Engineering, St. Louis, Missouri
- Address reprint requests and correspondence: Dr Jennifer N. Avari Silva, Division of Pediatric Cardiology, Washington University School of Medicine, 1 Children’s Place, CB 8116 NWT, St. Louis, MO 63110.; OR Dr Jonathan R. Silva, Department of Biomedical Engineering, Washington University McKelvey School of Engineering, 1 Brookings Place, St. Louis, MO 63130.
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16
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Angsutararux P, Marras M, Abella C, Voelker TL, Malcolm C, Shi J, Nerbonne JM, Silva JR. The NaV1.5 accessory subunit FGF12A inhibits pro-arrhythmic late sodium current. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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17
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Sabino VD, Súarez YR, Andrade LHC, Lima SM, Morais GR, Guimarães FB, Bento AC, Baesso ML, Silva JR. Photoacoustic for thermal diffusivity determination of fish scale: A methodology for environmental integrity monitoring. J Photochem Photobiol B 2022; 227:112379. [PMID: 34998114 DOI: 10.1016/j.jphotobiol.2021.112379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 10/09/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
In this work the thermal diffusivity (D) of Astyanax lacustris fish scale is investigated aiming to use it for environmental integrity certification. The D values were obtained by a relatively simple procedure by a photoacoustic method. The chosen fish species is from wide occurrence in Brasil's basins. It has short migration, and it has also been used as environmental bioindicator. The results obtained in 195 scales sampled from three different streams in the Midwest region in Brazil gives an average value of D ~ 4 × 10-3 cm2/s. ANCOVA analysis demonstrated that D values are able to differentiate among the three basins and indicates that it is dependent on the scales thickness and water conductivity. This last one is strongly affected by biotic and abiotic actions, so that D values measured by photoacoustic method can be used for interpreting the environmental integrity from where the fishes were sampled.
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Affiliation(s)
- V D Sabino
- Centro de Estudos em Recursos Naturais- CERNA, Universidade Estadual de Mato Grosso do Sul-UEMS, 351, Dourados, MS, Brazil
| | - Y R Súarez
- Centro de Estudos em Recursos Naturais- CERNA, Universidade Estadual de Mato Grosso do Sul-UEMS, 351, Dourados, MS, Brazil
| | - L H C Andrade
- Centro de Estudos em Recursos Naturais- CERNA, Universidade Estadual de Mato Grosso do Sul-UEMS, 351, Dourados, MS, Brazil
| | - S M Lima
- Centro de Estudos em Recursos Naturais- CERNA, Universidade Estadual de Mato Grosso do Sul-UEMS, 351, Dourados, MS, Brazil
| | - G R Morais
- Campus Estreito/Centro de Ciências Agrárias, Naturais e Letras, Universidade Estadual da Região Tocantina do Maranhão-UEMASUL, 65976-000 Estreito, MS, Brazil
| | - F B Guimarães
- Departamento de Física, Universidade Estadual de Maringá-UEM, 87020-900 Maringá, PR, Brazil
| | - A C Bento
- Departamento de Física, Universidade Estadual de Maringá-UEM, 87020-900 Maringá, PR, Brazil
| | - M L Baesso
- Departamento de Física, Universidade Estadual de Maringá-UEM, 87020-900 Maringá, PR, Brazil
| | - J R Silva
- Centro de Estudos em Recursos Naturais- CERNA, Universidade Estadual de Mato Grosso do Sul-UEMS, 351, Dourados, MS, Brazil.
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18
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Mangold KE, Zhou Z, Schoening M, Moreno JD, Silva JR. Creating Ion Channel Kinetic Models Using Cloud Computing. Curr Protoc 2022; 2:e374. [PMID: 35175690 PMCID: PMC9006544 DOI: 10.1002/cpz1.374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Computational modeling of ion channels provides key insight into experimental electrophysiology results and can be used to connect channel dynamics to emergent phenomena observed at the tissue and organ levels. However, creation of these models requires substantial mathematical and computational background. This tutorial seeks to lower the barrier to creating these models by providing an automated pipeline for creating Markov models of an ion channel kinetics dataset. We start by detailing how to encode sample voltage-clamp protocols and experimental data into the program and its implementation in a cloud computing environment. We guide the reader on how to build a containerized instance, push the machine image, and finally run the routine on cluster nodes. While providing open-source code has become more standard in computational studies, this tutorial provides unprecedented detail on the use of the program and the creation of channel models, starting from inputting the raw experimental data. © 2022 Wiley Periodicals LLC. Basic Protocol: Creation of ion channel kinetic models with a cloud computing environment Alternate Protocol: Instructions for use in a standard high-performance compute cluster.
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Affiliation(s)
- Kathryn E. Mangold
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130
| | - Zhuodong Zhou
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130
| | - Max Schoening
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130
| | - Jonathan D. Moreno
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130,Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO 63110
| | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130,Corresponding author: Jonathan R. Silva, , +1 314-935-8837
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19
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Zhang G, Xu X, Jia Z, Geng Y, Liang H, Shi J, Marras M, Abella C, Magleby KL, Silva JR, Chen J, Zou X, Cui J. Coupling between Ca2+ binding and the activation gate opening in BK channels probed by an allosteric activator. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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20
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Bhagavan D, Moreno JD, Kernik DC, Guo J, Huebsch N, Silva JR. Integrated electrophysiologic analyses of amiodarone in human iPSC-derived cardiomyocytes. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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21
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Wei Kang P, Woodbury LS, Angsutararux P, Sambare N, Shi J, Marras M, Abella C, Bedi A, Zinn D, Cui J, Silva JR. Disease associated CaM variants interact with KCNQ1 to confer aberrant membrane trafficking and function. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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22
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Moreno JD, Bhagavan D, Li A, Gerstner NC, Miller EW, Huebsch N, Cresci S, Silva JR. Pulsus Alternans in Cardiogenic Shock Recapitulated in Single Cell Fluorescence Imaging of a Patient's Cardiomyocyte. Circ Heart Fail 2022; 15:e008855. [PMID: 34886677 PMCID: PMC8847329 DOI: 10.1161/circheartfailure.121.008855] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Jonathan D. Moreno
- Division of Cardiology, Department of Medicine, Washington University in St. Louis
| | - Druv Bhagavan
- Department of Biomedical Engineering, Washington University in St. Louis
| | - Allie Li
- Division of Cardiology, Department of Medicine, Washington University in St. Louis
| | - Nels C. Gerstner
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley
| | - Evan W. Miller
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley
| | - Nathaniel Huebsch
- Department of Biomedical Engineering, Washington University in St. Louis
| | - Sharon Cresci
- Division of Cardiology, Department of Medicine, Washington University in St. Louis,Correspondence: Sharon Cresci, MD, 660 South Euclid Avenue, Box 8086, St. Louis, MO, 63130, Phone: 314-362-5363, Fax: 314-747-4758,
| | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis,Jonathan R. Silva, PhD, One Brookings Drive, Whitaker Hall, Room 290G, Saint Louis, Missouri, 63130, United States. Phone number: 314-935-8837,
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23
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Ransdell JL, Moreno JD, Bhagavan D, Silva JR, Nerbonne JM. Intrinsic mechanisms in the gating of resurgent Na + currents. eLife 2022; 11:70173. [PMID: 35076394 PMCID: PMC8824471 DOI: 10.7554/elife.70173] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 01/24/2022] [Indexed: 11/13/2022] Open
Abstract
The resurgent component of the voltage-gated sodium current (INaR) is a depolarizing conductance, revealed on membrane hyperpolarizations following brief depolarizing voltage steps, which has been shown to contribute to regulating the firing properties of numerous neuronal cell types throughout the central and peripheral nervous systems. Although mediated by the same voltage-gated sodium (Nav) channels that underlie the transient and persistent Nav current components, the gating mechanisms that contribute to the generation of INaR remain unclear. Here, we characterized Nav currents in mouse cerebellar Purkinje neurons, and used tailored voltage-clamp protocols to define how the voltage and the duration of the initial membrane depolarization affect the amplitudes and kinetics of INaR. Using the acquired voltage-clamp data, we developed a novel Markov kinetic state model with parallel (fast and slow) inactivation pathways and, we show that this model reproduces the properties of the resurgent, as well as the transient and persistent, Nav currents recorded in (mouse) cerebellar Purkinje neurons. Based on the acquired experimental data and the simulations, we propose that resurgent Na+ influx occurs as a result of fast inactivating Nav channels transitioning into an open/conducting state on membrane hyperpolarization, and that the decay of INaR reflects the slow accumulation of recovered/opened Nav channels into a second, alternative and more slowly populated, inactivated state. Additional simulations reveal that extrinsic factors that affect the kinetics of fast or slow Nav channel inactivation and/or impact the relative distribution of Nav channels in the fast- and slow-inactivated states, such as the accessory Navβ4 channel subunit, can modulate the amplitude of INaR.
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Affiliation(s)
- Joseph L Ransdell
- Department of Medicine, Washington University in Saint Louis, Saint Louis, United States
| | - Jonathan D Moreno
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, United States
| | - Druv Bhagavan
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, United States
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, United States
| | - Jeanne M Nerbonne
- Department of Medicine, Washington University in Saint Louis, Saint Louis, United States
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24
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Abstract
The voltage-gated Na+ channel regulates the initiation and propagation of the action potential in excitable cells. The major cardiac isoform NaV1.5, encoded by SCN5A, comprises a monomer with four homologous repeats (I-IV) that each contain a voltage sensing domain (VSD) and pore domain. In native myocytes, NaV1.5 forms a macromolecular complex with NaVβ subunits and other regulatory proteins within the myocyte membrane to maintain normal cardiac function. Disturbance of the NaV complex may manifest as deadly cardiac arrhythmias. Although SCN5A has long been identified as a gene associated with familial atrial fibrillation (AF) and Brugada Syndrome (BrS), other genetic contributors remain poorly understood. Emerging evidence suggests that mutations in the non-covalently interacting NaVβ1 and NaVβ3 are linked to both AF and BrS. Here, we investigated the molecular pathologies of 8 variants in NaVβ1 and NaVβ3. Our results reveal that NaVβ1 and NaVβ3 variants contribute to AF and BrS disease phenotypes by modulating both NaV1.5 expression and gating properties. Most AF-linked variants in the NaVβ1 subunit do not alter the gating kinetics of the sodium channel, but rather modify the channel expression. In contrast, AF-related NaVβ3 variants directly affect channel gating, altering voltage-dependent activation and the time course of recovery from inactivation via the modulation of VSD activation.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
| | - Wandi Zhu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States.,Department of Medicine, Brigham and Women's Hospital, Boston, MA, United States
| | - Taylor L Voelker
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
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25
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Jung C, Wolff G, Wernly B, Bruno RR, Franz M, Schulze PC, Silva JNA, Silva JR, Bhatt DL, Kelm M. Virtual and Augmented Reality in Cardiovascular Care: State-of-the-Art and Future Perspectives. JACC Cardiovasc Imaging 2021; 15:519-532. [PMID: 34656478 DOI: 10.1016/j.jcmg.2021.08.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/17/2021] [Indexed: 12/19/2022]
Abstract
Applications of virtual reality (VR) and augmented reality (AR) assist both health care providers and patients in cardiovascular education, complementing traditional learning methods. Interventionalists have successfully used VR to plan difficult procedures and AR to facilitate complex interventions. VR/AR has already been used to treat patients, during interventions in rehabilitation programs and in immobilized intensive care patients. There are numerous additional potential applications in the catheterization laboratory. By using AR, interventionalists could combine visual fluoroscopy information projected and registered on the patient body with data derived from preprocedural imaging and live fusion of different imaging modalities such as fluoroscopy with echocardiography. Persistent technical challenges to overcome include the integration of different imaging modalities into VR/AR and the harmonization of data flow and interfaces. Cybersickness might exclude some patients and users from the potential benefits of VR/AR. Critical ethical considerations arise in the application of VR/AR in vulnerable patients. In addition, digital applications must not distract physicians from the patient. It is our duty as physicians to participate in the development of these innovations to ensure a virtual health reality benefit for our patients in a real-world setting. The purpose of this review is to summarize the current and future role of VR and AR in different fields within cardiology, its challenges, and perspectives.
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Affiliation(s)
- Christian Jung
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, Heinrich-Heine-University, University Hospital Düsseldorf, Düsseldorf, Germany.
| | - Georg Wolff
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, Heinrich-Heine-University, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Bernhard Wernly
- Department of Anesthesiology and Intensive Care, Paracelsus Medical University of Salzburg, Salzburg, Austria; Division of Cardiology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Raphael Romano Bruno
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, Heinrich-Heine-University, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Marcus Franz
- Department of Internal Medicine I, Medical Faculty, Friedrich Schiller University Jena, University Hospital Jena, Jena, Germany
| | - P Christian Schulze
- Department of Internal Medicine I, Medical Faculty, Friedrich Schiller University Jena, University Hospital Jena, Jena, Germany
| | - Jennifer N Avari Silva
- Pediatric Cardiology Division, Department of Pediatrics, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri, USA; Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in Saint Louis, Saint Louis, Missouri, USA; SentiAR, Saint Louis, Missouri, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in Saint Louis, Saint Louis, Missouri, USA; SentiAR, Saint Louis, Missouri, USA
| | - Deepak L Bhatt
- Brigham and Women's Hospital Heart and Vascular Center, Harvard Medical School, Boston, Massachusetts, USA. https://twitter.com/DLBHATTMD
| | - Malte Kelm
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, Heinrich-Heine-University, University Hospital Düsseldorf, Düsseldorf, Germany; Cardiovascular Research Institute Duesseldorf, Düsseldorf, Germany
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26
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Angsutararux P, Kang PW, Zhu W, Silva JR. Conformations of voltage-sensing domain III differentially define NaV channel closed- and open-state inactivation. J Gen Physiol 2021; 153:212533. [PMID: 34347027 PMCID: PMC8348240 DOI: 10.1085/jgp.202112891] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/14/2021] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated Na+ (NaV) channels underlie the initiation and propagation of action potentials (APs). Rapid inactivation after NaV channel opening, known as open-state inactivation, plays a critical role in limiting the AP duration. However, NaV channel inactivation can also occur before opening, namely closed-state inactivation, to tune the cellular excitability. The voltage-sensing domain (VSD) within repeat IV (VSD-IV) of the pseudotetrameric NaV channel α-subunit is known to be a critical regulator of NaV channel inactivation. Yet, the two processes of open- and closed-state inactivation predominate at different voltage ranges and feature distinct kinetics. How inactivation occurs over these different ranges to give rise to the complexity of NaV channel dynamics is unclear. Past functional studies and recent cryo-electron microscopy structures, however, reveal significant inactivation regulation from other NaV channel components. In this Hypothesis paper, we propose that the VSD of NaV repeat III (VSD-III), together with VSD-IV, orchestrates the inactivation-state occupancy of NaV channels by modulating the affinity of the intracellular binding site of the IFMT motif on the III-IV linker. We review and outline substantial evidence that VSD-III activates in two distinct steps, with the intermediate and fully activated conformation regulating closed- and open-state inactivation state occupancy by altering the formation and affinity of the IFMT crevice. A role of VSD-III in determining inactivation-state occupancy and recovery from inactivation suggests a regulatory mechanism for the state-dependent block by small-molecule anti-arrhythmic and anesthetic therapies.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Po Wei Kang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Wandi Zhu
- Department of Medicine, Brigham and Women's Hospital, Boston, MA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
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27
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Mangold KE, Wang W, Johnson EK, Bhagavan D, Moreno JD, Nerbonne JM, Silva JR. Identification of structures for ion channel kinetic models. PLoS Comput Biol 2021; 17:e1008932. [PMID: 34398881 PMCID: PMC8389848 DOI: 10.1371/journal.pcbi.1008932] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/26/2021] [Accepted: 07/16/2021] [Indexed: 12/22/2022] Open
Abstract
Markov models of ion channel dynamics have evolved as experimental advances have improved our understanding of channel function. Past studies have examined limited sets of various topologies for Markov models of channel dynamics. We present a systematic method for identification of all possible Markov model topologies using experimental data for two types of native voltage-gated ion channel currents: mouse atrial sodium currents and human left ventricular fast transient outward potassium currents. Successful models identified with this approach have certain characteristics in common, suggesting that aspects of the model topology are determined by the experimental data. Incorporating these channel models into cell and tissue simulations to assess model performance within protocols that were not used for training provided validation and further narrowing of the number of acceptable models. The success of this approach suggests a channel model creation pipeline may be feasible where the structure of the model is not specified a priori. Markov models of ion channel dynamics have evolved as experimental advances have improved our understanding of channel function. Past studies have examined limited sets of various structures for Markov models of channel dynamics. Here, we present a computational routine designed to thoroughly search for Markov model topologies for simulating whole-cell currents. We tested this method on two distinct types of voltage-gated cardiac ion channels and found the number of states and connectivity required to recapitulate experimentally observed kinetics. Successful models identified with this approach have certain characteristics in common, suggesting that model structures are determined by the experimental data. Incorporation of these models into higher scale action potential and cable (an approximation of one-dimensional action potential propagation) simulations, identified key channel phenomena that were required for proper function. These methods provide a route to create functional channel models that can be used for action potential simulation without pre-defining their structure ahead of time.
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Affiliation(s)
- Kathryn E. Mangold
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Wei Wang
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis Missouri, United States of America
| | - Eric K. Johnson
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis Missouri, United States of America
| | - Druv Bhagavan
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Jonathan D. Moreno
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis Missouri, United States of America
| | - Jeanne M. Nerbonne
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis Missouri, United States of America
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- * E-mail:
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28
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Zhu W, Wang W, Angsutararux P, Mellor RL, Isom LL, Nerbonne JM, Silva JR. Modulation of the effects of class Ib antiarrhythmics on cardiac NaV1.5-encoded channels by accessory NaVβ subunits. JCI Insight 2021; 6:e143092. [PMID: 34156986 PMCID: PMC8410097 DOI: 10.1172/jci.insight.143092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 06/17/2021] [Indexed: 01/28/2023] Open
Abstract
Native myocardial voltage-gated sodium (NaV) channels function in macromolecular complexes comprising a pore-forming (α) subunit and multiple accessory proteins. Here, we investigated the impact of accessory NaVβ1 and NaVβ3 subunits on the functional effects of 2 well-known class Ib antiarrhythmics, lidocaine and ranolazine, on the predominant NaV channel α subunit, NaV1.5, expressed in the mammalian heart. We showed that both drugs stabilized the activated conformation of the voltage sensor of domain-III (DIII-VSD) in NaV1.5. In the presence of NaVβ1, the effect of lidocaine on the DIII-VSD was enhanced, whereas the effect of ranolazine was abolished. Mutating the main class Ib drug-binding site, F1760, affected but did not abolish the modulation of drug block by NaVβ1/β3. Recordings from adult mouse ventricular myocytes demonstrated that loss of Scn1b (NaVβ1) differentially affected the potencies of lidocaine and ranolazine. In vivo experiments revealed distinct ECG responses to i.p. injection of ranolazine or lidocaine in WT and Scn1b-null animals, suggesting that NaVβ1 modulated drug responses at the whole-heart level. In the human heart, we found that SCN1B transcript expression was 3 times higher in the atria than ventricles, differences that could, in combination with inherited or acquired cardiovascular disease, dramatically affect patient response to class Ib antiarrhythmic therapies.
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Affiliation(s)
- Wandi Zhu
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, Missouri, USA.,Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Wei Wang
- Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Paweorn Angsutararux
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Rebecca L Mellor
- Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Lori L Isom
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Jeanne M Nerbonne
- Department of Internal Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA.,Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
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29
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Gholami Derami H, Gupta P, Weng KC, Seth A, Gupta R, Silva JR, Raman B, Singamaneni S. Reversible Photothermal Modulation of Electrical Activity of Excitable Cells using Polydopamine Nanoparticles. Adv Mater 2021; 33:e2008809. [PMID: 34216406 PMCID: PMC8363531 DOI: 10.1002/adma.202008809] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 04/15/2021] [Indexed: 05/17/2023]
Abstract
Advances in the design and synthesis of nanomaterials with desired biophysicochemical properties can be harnessed to develop non-invasive neuromodulation technologies. Here, the reversible modulation of the electrical activity of neurons and cardiomyocytes is demonstrated using polydopamine (PDA) nanoparticles as photothermal nanotransducers. In addition to their broad light absorption and excellent photothermal activity, PDA nanoparticles are highly biocompatible and biodegradable, making them excellent candidates for both in vitro and in vivo applications. The modulation of the activity (i.e., spike rate of the neurons and beating rate of cardiomyocytes) of excitable cells can be finely controlled by varying the excitation power density and irradiation duration. Under optimal conditions, reversible suppression (≈100%) of neural activity and reversible enhancement (two-fold) in the beating rate of cardiomyocytes is demonstrated. To improve the ease of interfacing of photothermal transducers with these excitable cells and enable spatial localization of the photothermal stimulus, a collagen/PDA nanoparticle foam is realized, which can be used as an "add-on patch" for photothermal stimulation. The non-genetic optical neuromodulation approach using biocompatible and biodegradable nanoparticles represents a minimally invasive method for controlling the activity of excitable cells with potential applications in nano-neuroscience and engineering.
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Affiliation(s)
- Hamed Gholami Derami
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Prashant Gupta
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Kuo-Chan Weng
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Anushree Seth
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Rohit Gupta
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Baranidharan Raman
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Srikanth Singamaneni
- Department of Mechanical Engineering and Materials Science, Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
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30
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Silva JNA, Southworth MK, Andrews CM, Privitera MB, Henry AB, Silva JR. Design Considerations for Interacting and Navigating with 2 Dimensional and 3 Dimensional Medical Images in Virtual, Augmented and Mixed Reality Medical Applications. Virtual Augment Mixed Real (2021) 2021; 12770:117-133. [PMID: 35079751 PMCID: PMC8786214 DOI: 10.1007/978-3-030-77599-5_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The extended realities, including virtual, augmented, and mixed realities (VAMR) have recently experienced significant hardware improvement resulting in an expansion in medical applications. These applications can be classified by the target end user (for instance, classifying applications as patient-centric, physician-centric, or both) or by use case (for instance educational, diagnostic tools, therapeutic tools, or some combination). When developing medical applications in VAMR, careful consideration of both the target end user and use case must heavily influence design considerations, particularly methods and tools for interaction and navigation. Medical imaging consists of both 2-dimensional and 3-dimensional medical imaging which impacts design, interaction, and navigation. Additionally, medical applications need to comply with regulatory considerations which will also influence interaction and design considerations. In this manuscript, the authors explore these considerations using three VAMR tools being developed for cardiac electrophysiology procedures.
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Affiliation(s)
- Jennifer N Avari Silva
- Department of Pediatrics, Cardiology, Washington University in St Louis, School of Medicine, St Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St Louis, McKelvey School of Engineering, St Louis, MO, USA
- SentiAR, Inc, St Louis, MO, USA
| | | | | | | | | | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St Louis, McKelvey School of Engineering, St Louis, MO, USA
- SentiAR, Inc, St Louis, MO, USA
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31
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Prakosa A, Southworth MK, Avari Silva JN, Silva JR, Trayanova NA. Impact of augmented-reality improvement in ablation catheter navigation as assessed by virtual-heart simulations of ventricular tachycardia ablation. Comput Biol Med 2021; 133:104366. [PMID: 33836448 PMCID: PMC8169616 DOI: 10.1016/j.compbiomed.2021.104366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/29/2021] [Accepted: 03/29/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Recently, an augmented reality (AR) solution allows the physician to place the ablation catheter at the designated lesion site more accurately during cardiac electrophysiology studies. The improvement in navigation accuracy may positively affect ventricular tachycardia (VT) ablation termination, however assessment of this in the clinic would be difficult. Novel personalized virtual heart technology enables non-invasive identification of optimal lesion targets for infarct-related VT. This study aims to evaluate the potential impact of such catheter navigation accuracy improvement in virtual VT ablations. METHODS 2 MRI-based virtual hearts with 2 in silico induced VTs (VT 1, VT 2) were included. VTs were terminated with virtual "ground truth" endocardial ablation lesions. 106 navigation error values that were previously assessed in a clinical study evaluating the improvement of ablation catheter navigation accuracy guided with AR (53 with, 53 without) were used to displace the "ground truth" ablation targets. The corresponding ablations were simulated based on these errors and VT termination for each simulation was assessed. RESULTS In 54 VT 1 ablation simulations, smaller error with AR significantly resulted in more VT termination (25) compared to the error without AR (16) (P < 0.01). In 52 VT 2 ablation simulations, no significant difference was observed from error with (11) and without AR (13) (P = 0.58). The substrate characteristic may impact the effect of improved accuracy to an improved VT termination. CONCLUSION Virtual heart shows that the increased catheter navigation accuracy provided by AR guidance can affect the VT termination.
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Affiliation(s)
- Adityo Prakosa
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD, USA.
| | | | - Jennifer N Avari Silva
- Department of Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Natalia A Trayanova
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
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32
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Lorenzini M, Burel S, Lesage A, Wagner E, Charrière C, Chevillard PM, Evrard B, Maloney D, Ruff KM, Pappu RV, Wagner S, Nerbonne JM, Silva JR, Townsend RR, Maier LS, Marionneau C. Proteomic and functional mapping of cardiac NaV1.5 channel phosphorylation sites. J Gen Physiol 2021; 153:211660. [PMID: 33410863 PMCID: PMC7797897 DOI: 10.1085/jgp.202012646] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 10/23/2020] [Accepted: 12/03/2020] [Indexed: 12/16/2022] Open
Abstract
Phosphorylation of the voltage-gated Na+ (NaV) channel NaV1.5 regulates cardiac excitability, yet the phosphorylation sites regulating its function and the underlying mechanisms remain largely unknown. Using a systematic, quantitative phosphoproteomic approach, we analyzed NaV1.5 channel complexes purified from nonfailing and failing mouse left ventricles, and we identified 42 phosphorylation sites on NaV1.5. Most sites are clustered, and three of these clusters are highly phosphorylated. Analyses of phosphosilent and phosphomimetic NaV1.5 mutants revealed the roles of three phosphosites in regulating NaV1.5 channel expression and gating. The phosphorylated serines S664 and S667 regulate the voltage dependence of channel activation in a cumulative manner, whereas the nearby S671, the phosphorylation of which is increased in failing hearts, regulates cell surface NaV1.5 expression and peak Na+ current. No additional roles could be assigned to the other clusters of phosphosites. Taken together, our results demonstrate that ventricular NaV1.5 is highly phosphorylated and that the phosphorylation-dependent regulation of NaV1.5 channels is highly complex, site specific, and dynamic.
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Affiliation(s)
- Maxime Lorenzini
- Université de Nantes, Centre national de la recherche scientifique, Institut National de la Santé et de la Recherche Médicale, l'Institut du thorax, Nantes, France
| | - Sophie Burel
- Université de Nantes, Centre national de la recherche scientifique, Institut National de la Santé et de la Recherche Médicale, l'Institut du thorax, Nantes, France
| | - Adrien Lesage
- Université de Nantes, Centre national de la recherche scientifique, Institut National de la Santé et de la Recherche Médicale, l'Institut du thorax, Nantes, France
| | - Emily Wagner
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO
| | - Camille Charrière
- Université de Nantes, Centre national de la recherche scientifique, Institut National de la Santé et de la Recherche Médicale, l'Institut du thorax, Nantes, France
| | - Pierre-Marie Chevillard
- Université de Nantes, Centre national de la recherche scientifique, Institut National de la Santé et de la Recherche Médicale, l'Institut du thorax, Nantes, France
| | - Bérangère Evrard
- Université de Nantes, Centre national de la recherche scientifique, Institut National de la Santé et de la Recherche Médicale, l'Institut du thorax, Nantes, France
| | - Dan Maloney
- Bioinformatics Solutions Inc., Waterloo, Ontario, Canada
| | - Kiersten M Ruff
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO
| | - Rohit V Pappu
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO
| | - Stefan Wagner
- Department of Internal Medicine II, University Heart Center, University Hospital Regensburg, Regensburg, Germany
| | - Jeanne M Nerbonne
- Department of Developmental Biology, Washington University Medical School, St. Louis, MO.,Department of Medicine, Washington University Medical School, St. Louis, MO
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO
| | - R Reid Townsend
- Department of Medicine, Washington University Medical School, St. Louis, MO.,Department of Cell Biology and Physiology, Washington University Medical School, St. Louis, MO
| | - Lars S Maier
- Department of Internal Medicine II, University Heart Center, University Hospital Regensburg, Regensburg, Germany
| | - Céline Marionneau
- Université de Nantes, Centre national de la recherche scientifique, Institut National de la Santé et de la Recherche Médicale, l'Institut du thorax, Nantes, France
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33
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Andrews CM, Henry AB, Soriano IM, Southworth MK, Silva JR. Registration Techniques for Clinical Applications of Three-Dimensional Augmented Reality Devices. IEEE J Transl Eng Health Med 2020; 9:4900214. [PMID: 33489483 PMCID: PMC7819530 DOI: 10.1109/jtehm.2020.3045642] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 11/13/2020] [Accepted: 12/03/2020] [Indexed: 12/15/2022]
Abstract
Many clinical procedures would benefit from direct and intuitive real-time visualization of anatomy, surgical plans, or other information crucial to the procedure. Three-dimensional augmented reality (3D-AR) is an emerging technology that has the potential to assist physicians with spatial reasoning during clinical interventions. The most intriguing applications of 3D-AR involve visualizations of anatomy or surgical plans that appear directly on the patient. However, commercially available 3D-AR devices have spatial localization errors that are too large for many clinical procedures. For this reason, a variety of approaches for improving 3D-AR registration accuracy have been explored. The focus of this review is on the methods, accuracy, and clinical applications of registering 3D-AR devices with the clinical environment. The works cited represent a variety of approaches for registering holograms to patients, including manual registration, computer vision-based registration, and registrations that incorporate external tracking systems. Evaluations of user accuracy when performing clinically relevant tasks suggest that accuracies of approximately 2 mm are feasible. 3D-AR device limitations due to the vergence-accommodation conflict or other factors attributable to the headset hardware add on the order of 1.5 mm of error compared to conventional guidance. Continued improvements to 3D-AR hardware will decrease these sources of error.
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Affiliation(s)
- Christopher M. Andrews
- Department of Biomedical EngineeringWashington University in St Louis, McKelvey School of EngineeringSt LouisMO63130USA
- SentiAR, Inc.St. LouisMO63108USA
| | | | | | | | - Jonathan R. Silva
- Department of Biomedical EngineeringWashington University in St Louis, McKelvey School of EngineeringSt LouisMO63130USA
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34
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Kang PW, Westerlund AM, Shi J, White KM, Dou AK, Cui AH, Silva JR, Delemotte L, Cui J. Calmodulin acts as a state-dependent switch to control a cardiac potassium channel opening. Sci Adv 2020; 6:6/50/eabd6798. [PMID: 33310856 PMCID: PMC7732179 DOI: 10.1126/sciadv.abd6798] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/27/2020] [Indexed: 05/09/2023]
Abstract
Calmodulin (CaM) and phosphatidylinositol 4,5-bisphosphate (PIP2) are potent regulators of the voltage-gated potassium channel KCNQ1 (KV7.1), which conducts the cardiac I Ks current. Although cryo-electron microscopy structures revealed intricate interactions between the KCNQ1 voltage-sensing domain (VSD), CaM, and PIP2, the functional consequences of these interactions remain unknown. Here, we show that CaM-VSD interactions act as a state-dependent switch to control KCNQ1 pore opening. Combined electrophysiology and molecular dynamics network analysis suggest that VSD transition into the fully activated state allows PIP2 to compete with CaM for binding to VSD. This leads to conformational changes that alter VSD-pore coupling to stabilize open states. We identify a motif in the KCNQ1 cytosolic domain, which works downstream of CaM-VSD interactions to facilitate the conformational change. Our findings suggest a gating mechanism that integrates PIP2 and CaM in KCNQ1 voltage-dependent activation, yielding insights into how KCNQ1 gains the phenotypes critical for its physiological function.
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Affiliation(s)
- Po Wei Kang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Annie M Westerlund
- Department of Applied Physics, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Kelli McFarland White
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Alex K Dou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Amy H Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Lucie Delemotte
- Department of Applied Physics, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden.
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA.
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Martins ACF, Pereira PL, Mafra ACCN, Miraglia JL, Monteiro CN, Silva JR, Almeida ES, Oliveira JS, Santos VS, Borges LM. The implementation of a mobile application to support community-based health workers. Eur J Public Health 2020. [DOI: 10.1093/eurpub/ckaa166.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Issue
Real-time access to up-to-date population information is essential to the strategic planning of primary health care (PHC). In the Brazilian public health system community-based health workers (CHWs), working as part of PHC teams, collect health, demographic and socio-economic data from individuals mainly through paper-based forms that are later entered manually into electronic information systems. Mobile applications could help to improve the quality and speed of this process facilitating the CHWs day-to-day work while improving the access to the collected information.
Description of the Problem
During September of 2019, a mobile application installed in tablets for the collection of health, demographic and socio-economic data was deployed for 432 CHWs of 87 PHC teams in the southern region of São Paulo, Brazil, serving a total population of 283,324 individuals. During implementation, the acceptability and challenges faced by CHWs were evaluated and the time taken to complete data entry.
Results
Seventy-two hours of training were offered to CHWs and other 139 professionals including managers, nurses and administrative staff (AS). Some CHWs reported concerns about the process change and fear of not being able to operate the application, especially those unfamiliar to the technology. With training and team support, fear was transformed into satisfaction with the realization of the benefits of the system. The main infrastructure challenge was the need for installation of Wi-Fi routers in some health care units, in addition to the replacement 4.4% of damaged tablets. In four months 97.6% of the total population was registered in the application.
Lessons
A WhatsApp group was created to clarify AS doubts, receive suggestions and disseminate guidelines. AS remained as the reference point at healthcare units and data completeness still needs to be reinforced.
Key messages
A mobile application was well-accepted by CHWs and could facilitate the collection of population data. A tablet app proved to be a useful tool to generate information for the PHC teams.
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Affiliation(s)
- A C F Martins
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - P L Pereira
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - A C C N Mafra
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - J L Miraglia
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - C N Monteiro
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - J R Silva
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - E S Almeida
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - J S Oliveira
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - V S Santos
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - L M Borges
- Hospital Israelita Albert Einstein, São Paulo, Brazil
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36
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Silva JNA, Privitera MB, Southworth MK, Silva JR. Development and Human Factors Considerations for Extended Reality Applications in Medicine: The Enhanced ELectrophysiology Visualization and Interaction System (ĒLVIS). Virtual Augment Mixed Real (2020) 2020; 12191:341-356. [PMID: 34327520 PMCID: PMC8317914 DOI: 10.1007/978-3-030-49698-2_23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
With the rapid expansion of hardware options in the extended realities (XRs), there has been widespread development of applications throughout many fields, including engineering, entertainment and medicine. Development of medical applications for the XRs have a unique set of considerations during development and human factors testing. Additionally, understanding the constraints of the user and the use case allow for iterative improvement. In this manuscript, the authors discuss the considerations when developing and performing human factors testing for XR applications, using the Enhanced ELectrophysiology Visualization and Interaction System (ĒLVIS) as an example. Additionally, usability and critical interpersonal interaction data from first-in-human testing of ĒLVIS are presented.
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Affiliation(s)
- Jennifer N Avari Silva
- Department of Pediatrics, Cardiology. Washington University in St Louis, School of Medicine, St Louis, MO
- Department of Biomedical Engineering. Washington University in St Louis, McKelvey School of Engineering, St Louis, MO
- SentiAR, Inc, St Louis, MO
| | | | | | - Jonathan R Silva
- Department of Biomedical Engineering. Washington University in St Louis, McKelvey School of Engineering, St Louis, MO
- SentiAR, Inc, St Louis, MO
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Avari Silva JN, Southworth MK, Blume WM, Andrews C, Van Hare GF, Dalal AS, Miller N, Sodhi SS, Silva JR. First-In-Human Use of a Mixed Reality Display During Cardiac Ablation Procedures. JACC Clin Electrophysiol 2020; 6:1023-1025. [PMID: 32819517 DOI: 10.1016/j.jacep.2020.04.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 10/23/2022]
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Southworth MK, Silva JNA, Blume WM, Van Hare GF, Dalal AS, Silva JR. Performance Evaluation of Mixed Reality Display for Guidance During Transcatheter Cardiac Mapping and Ablation. IEEE J Transl Eng Health Med 2020; 8:1900810. [PMID: 32742821 PMCID: PMC7390021 DOI: 10.1109/jtehm.2020.3007031] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/23/2020] [Accepted: 06/24/2020] [Indexed: 01/18/2023]
Abstract
Cardiac electrophysiology procedures present the physician with a wealth of 3D information, typically presented on fixed 2D monitors. New developments in wearable mixed reality displays offer the potential to simplify and enhance 3D visualization while providing hands-free, dynamic control of devices within the procedure room. OBJECTIVE This work aims to evaluate the performance and quality of a mixed reality system designed for intraprocedural use in cardiac electrophysiology. METHOD The Enhanced Electrophysiology Visualization and Interaction System (ĒLVIS) mixed reality system performance criteria, including image quality, hardware performance, and usability were evaluated using existing display validation procedures adapted to the electrophysiology specific use case. Additional performance and user validation were performed through a 10 patient, in-human observational study, the Engineering ĒLVIS (E2) Study. RESULTS The ĒLVIS system achieved acceptable frame rate, latency, and battery runtime with acceptable dynamic range and depth distortion as well as minimal geometric distortion. Bench testing results corresponded with physician feedback in the observational study, and potential improvements in geometric understanding were noted. CONCLUSION The ĒLVIS system, based on current commercially available mixed reality hardware, is capable of meeting the hardware performance, image quality, and usability requirements of the electroanatomic mapping display for intraprocedural, real-time use in electrophysiology procedures. Verifying off the shelf mixed reality hardware for specific clinical use can accelerate the adoption of this transformative technology and provide novel visualization, understanding, and control of clinically relevant data in real-time.
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Affiliation(s)
| | - Jennifer N. Avari Silva
- SentiAR, Inc.St. LouisMO63108USA
- Department of PediatricsSchool of MedicineWashington University in St. LouisSt. LouisMO63130USA
| | | | - George F. Van Hare
- Department of PediatricsSchool of MedicineWashington University in St. LouisSt. LouisMO63130USA
| | - Aarti S. Dalal
- Department of PediatricsSchool of MedicineWashington University in St. LouisSt. LouisMO63130USA
| | - Jonathan R. Silva
- SentiAR, Inc.St. LouisMO63108USA
- Department of Biomedical EngineeringWashington University in St. LouisSt. LouisMO63130USA
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Zhu W, Li T, Silva JR, Chen J. Conservation and divergence in NaChBac and Na V1.7 pharmacology reveals novel drug interaction mechanisms. Sci Rep 2020; 10:10730. [PMID: 32612253 PMCID: PMC7329812 DOI: 10.1038/s41598-020-67761-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/13/2020] [Indexed: 01/16/2023] Open
Abstract
Voltage-gated Na+ (NaV) channels regulate homeostasis in bacteria and control membrane electrical excitability in mammals. Compared to their mammalian counterparts, bacterial NaV channels possess a simpler, fourfold symmetric structure and have facilitated studies of the structural basis of channel gating. However, the pharmacology of bacterial NaV remains largely unexplored. Here we systematically screened 39 NaV modulators on a bacterial channel (NaChBac) and characterized a selection of compounds on NaChBac and a mammalian channel (human NaV1.7). We found that while many compounds interact with both channels, they exhibit distinct functional effects. For example, the local anesthetics ambroxol and lidocaine block both NaV1.7 and NaChBac but affect activation and inactivation of the two channels to different extents. The voltage-sensing domain targeting toxin BDS-I increases NaV1.7 but decreases NaChBac peak currents. The pore binding toxins aconitine and veratridine block peak currents of NaV1.7 and shift activation (aconitine) and inactivation (veratridine) respectively. In NaChBac, they block the peak current by binding to the pore residue F224. Nonetheless, aconitine has no effect on activation or inactivation, while veratridine only modulates activation of NaChBac. The conservation and divergence in the pharmacology of bacterial and mammalian NaV channels provide insights into the molecular basis of channel gating and will facilitate organism-specific drug discovery.
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Affiliation(s)
- Wandi Zhu
- Biochemical and Cellular Pharmacology, Genentech Inc., 103 DNA Way, South San Francisco, CA, USA. .,Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.
| | - Tianbo Li
- Biochemical and Cellular Pharmacology, Genentech Inc., 103 DNA Way, South San Francisco, CA, USA
| | - Jonathan R Silva
- Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jun Chen
- Biochemical and Cellular Pharmacology, Genentech Inc., 103 DNA Way, South San Francisco, CA, USA.
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Angsutararux P, Voelker TL, Malcolm C, Zhu W, Silva JR. Revisiting NaV Channel Inactivation: The Role of Fibroblast Growth Factor Homologous Factor (FHF). Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Kang PW, Westerlund AM, Shi J, McFarland White K, Dou AK, Silva JR, Delemotte L, Cui J. Calmodulin Functionally Couples the KCNQ1 Channel Voltage-Sensing and Pore Domains. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Zhu W, Mazzanti A, Voelker TL, Hou P, Moreno JD, Angsutararux P, Naegle KM, Priori SG, Silva JR. Predicting Patient Response to the Antiarrhythmic Mexiletine Based on Genetic Variation. Circ Res 2019; 124:539-552. [PMID: 30566038 DOI: 10.1161/circresaha.118.314050] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Mutations in the SCN5A gene, encoding the α subunit of the Nav1.5 channel, cause a life-threatening form of cardiac arrhythmia, long QT syndrome type 3 (LQT3). Mexiletine, which is structurally related to the Na+ channel-blocking anesthetic lidocaine, is used to treat LQT3 patients. However, the patient response is variable, depending on the genetic mutation in SCN5A. OBJECTIVE The goal of this study is to understand the molecular basis of patients' variable responses and build a predictive statistical model that can be used to personalize mexiletine treatment based on patient's genetic variant. METHODS AND RESULTS We monitored the cardiac Na+ channel voltage-sensing domain (VSD) conformational dynamics simultaneously with other gating properties for the LQT3 variants. To systematically identify the relationship between mexiletine block and channel biophysical properties, we used a system-based statistical modeling approach to connect the multivariate properties to patient phenotype. We found that mexiletine altered the conformation of the Domain III VSD, which is the same VSD that many tested LQT3 mutations affect. Analysis of 15 LQT3 variants showed a strong correlation between the activation of the Domain III-VSD and the strength of the inhibition of the channel by mexiletine. Based on this improved molecular-level understanding, we generated a systems-based model based on a dataset of 32 LQT3 patients, which then successfully predicted the response of 7 out of 8 patients to mexiletine in a blinded, retrospective trial. CONCLUSIONS Our results imply that the modulated receptor theory of local anesthetic action, which confines local anesthetic binding effects to the channel pore, should be revised to include drug interaction with the Domain III-VSD. Using an algorithm that incorporates this mode of action, we can predict patient-specific responses to mexiletine, improving therapeutic decision making.
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Affiliation(s)
- Wandi Zhu
- From the Department of Biomedical Engineering (W.Z., T.L.V., P.H., J.D.M., P.A., K.M.N., J.R.S.), Washington University in St Louis, MO
| | - Andrea Mazzanti
- Molecular Cardiology, IRCCS Salvatore Maugeri Foundation, Pavia, Italy (A.M., S.G.P.)
| | - Taylor L Voelker
- From the Department of Biomedical Engineering (W.Z., T.L.V., P.H., J.D.M., P.A., K.M.N., J.R.S.), Washington University in St Louis, MO
| | - Panpan Hou
- From the Department of Biomedical Engineering (W.Z., T.L.V., P.H., J.D.M., P.A., K.M.N., J.R.S.), Washington University in St Louis, MO
| | - Jonathan D Moreno
- From the Department of Biomedical Engineering (W.Z., T.L.V., P.H., J.D.M., P.A., K.M.N., J.R.S.), Washington University in St Louis, MO.,Division of Cardiology, Department of Medicine (J.D.M.), Washington University in St Louis, MO
| | - Paweorn Angsutararux
- From the Department of Biomedical Engineering (W.Z., T.L.V., P.H., J.D.M., P.A., K.M.N., J.R.S.), Washington University in St Louis, MO
| | - Kristen M Naegle
- From the Department of Biomedical Engineering (W.Z., T.L.V., P.H., J.D.M., P.A., K.M.N., J.R.S.), Washington University in St Louis, MO
| | - Silvia G Priori
- Molecular Cardiology, IRCCS Salvatore Maugeri Foundation, Pavia, Italy (A.M., S.G.P.).,Department of Molecular Medicine, University of Pavia, Italy (S.G.P.)
| | - Jonathan R Silva
- From the Department of Biomedical Engineering (W.Z., T.L.V., P.H., J.D.M., P.A., K.M.N., J.R.S.), Washington University in St Louis, MO
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Salvage SC, Zhu W, Habib ZF, Hwang SS, Irons JR, Huang CLH, Silva JR, Jackson AP. Gating control of the cardiac sodium channel Nav1.5 by its β3-subunit involves distinct roles for a transmembrane glutamic acid and the extracellular domain. J Biol Chem 2019; 294:19752-19763. [PMID: 31659116 PMCID: PMC6926464 DOI: 10.1074/jbc.ra119.010283] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/24/2019] [Indexed: 11/06/2022] Open
Abstract
The auxiliary β3-subunit is an important functional regulator of the cardiac sodium channel Nav1.5, and some β3 mutations predispose individuals to cardiac arrhythmias. The β3-subunit uses its transmembrane α-helix and extracellular domain to bind to Nav1.5. Here, we investigated the role of an unusually located and highly conserved glutamic acid (Glu-176) within the β3 transmembrane region and its potential for functionally synergizing with the β3 extracellular domain (ECD). We substituted Glu-176 with lysine (E176K) in the WT β3-subunit and in a β3-subunit lacking the ECD. Patch-clamp experiments indicated that the E176K substitution does not affect the previously observed β3-dependent depolarizing shift of V½ of steady-state inactivation but does attenuate the accelerated recovery from inactivation conferred by the WT β3-subunit. Removal of the β3-ECD abrogated both the depolarizing shift of steady-state inactivation and the accelerated recovery, irrespective of the presence or absence of the Glu-176 residue. We found that steady-state inactivation and recovery from inactivation involve movements of the S4 helices within the DIII and DIV voltage sensors in response to membrane potential changes. Voltage-clamp fluorometry revealed that the E176K substitution alters DIII voltage sensor dynamics without affecting DIV. In contrast, removal of the ECD significantly altered the dynamics of both DIII and DIV. These results imply distinct roles for the β3-Glu-176 residue and the β3-ECD in regulating the conformational changes of the voltage sensors that determine channel inactivation and recovery from inactivation.
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Affiliation(s)
- Samantha C Salvage
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Wandi Zhu
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130-489
| | - Zaki F Habib
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, United Kingdom
| | - Soyon S Hwang
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130-489
| | - Jennifer R Irons
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Christopher L H Huang
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom .,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, United Kingdom
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130-489
| | - Antony P Jackson
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
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Moreno JD, Zhu W, Mangold K, Chung W, Silva JR. A Molecularly Detailed Na V1.5 Model Reveals a New Class I Antiarrhythmic Target. JACC Basic Transl Sci 2019; 4:736-751. [PMID: 31709321 PMCID: PMC6834944 DOI: 10.1016/j.jacbts.2019.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/07/2019] [Accepted: 06/07/2019] [Indexed: 12/17/2022]
Abstract
Antiarrhythmic therapies remain suboptimal due to our inability to predict how drug interactions with ion channels will affect the ability of the tissue to initiate and sustain an arrhythmia. We built a computational framework that allows for in silico design of precision-targeted therapeutic agents that simultaneously assesses antiarrhythmic markers of success and failure at multiple spatial and time scales. Using this framework, a novel in silico mexiletine “booster” was designed that may dramatically improve the efficacy of mexiletine in suppression of arrhythmia triggers. These results provide a roadmap for the design of novel molecular-based therapy to treat myriad arrhythmia syndromes, including ventricular tachycardia, heart failure arrhythmias, and inherited arrhythmia syndromes. In summary, computational modeling approaches to drug discovery represent a novel tool to design and test precision-targeted therapeutic agents. By exploiting nontraditional ion channel drug targets, an entirely new dimension can be added to the wide parameter space of traditional antiarrhythmic drugs to develop more precision-targeted and potent Class I therapeutic agents.
Antiarrhythmic treatment strategies remain suboptimal due to our inability to predict how drug interactions with ion channels will affect the ability of the tissues to initiate and sustain an arrhythmia. We built a multiscale molecular model of the Na+ channel domain III (domain III voltage-sensing domain) to highlight the molecular underpinnings responsible for mexiletine drug efficacy. This model predicts that a hyperpolarizing shift in the domain III voltage-sensing domain is critical for drug efficacy and may be leveraged to design more potent Class I molecules. The model was therefore used to design, in silico, a theoretical mexiletine booster that can dramatically rescue a mutant resistant to the potent antiarrhythmic effects of mexiletine. Our framework provides a strategy for in silico design of precision-targeted therapeutic agents that simultaneously assesses antiarrhythmic markers of success and failure at multiple spatial and time scales. This approach provides a roadmap for the design of novel molecular-based therapy to treat myriad arrhythmia syndromes, including ventricular tachycardia, heart failure arrhythmias, and inherited arrhythmia syndromes.
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Key Words
- APD, action potential duration
- BCL2000, basic cycle length of 2,000 ms
- DIII-VSD, domain III voltage-sensing domain
- EAD, early afterdepolarization
- IC50, half-maximal inhibitory voltage
- LQT3, long QT syndrome type 3
- RFI, recovery from inactivation
- SSA, steady-state availability
- UDB, use-dependent block
- V1/2, half-maximal voltage
- VSD, voltage-sensing domain
- arrhythmias
- computational biology
- ion channels
- pharmacology
- translational studies
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Affiliation(s)
- Jonathan D Moreno
- Division of Cardiology, Department of Medicine, Washington University in St. Louis, St. Louis, Missouri.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Wandi Zhu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Kathryn Mangold
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Woenho Chung
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri
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Li B, Silva JR, Lu X, Luo L, Wang Y, Xu L, Aierken A, Shynykul Z, Kamau PM, Luo A, Yang J, Su D, Yang F, Cui J, Yang S, Lai R. Molecular game theory for a toxin-dominant food chain model. Natl Sci Rev 2019; 6:1191-1200. [PMID: 34691998 PMCID: PMC8291550 DOI: 10.1093/nsr/nwz097] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/23/2019] [Accepted: 07/02/2019] [Indexed: 12/30/2022] Open
Abstract
Animal toxins that are used to subdue prey and deter predators act as the key drivers in natural food chains and ecosystems. However, the predators of venomous animals may exploit feeding adaptation strategies to overcome toxins their prey produce. Much remains unknown about the genetic and molecular game process in the toxin-dominant food chain model. Here, we show an evolutionary strategy in different trophic levels of scorpion-eating amphibians, scorpions and insects, representing each predation relationship in habitats dominated by the paralytic toxins of scorpions. For scorpions preying on insects, we found that the scorpion α-toxins irreversibly activate the skeletal muscle sodium channel of their prey (insect, BgNaV1) through a membrane delivery mechanism and an efficient binding with the Asp/Lys-Tyr motif of BgNaV1. However, in the predatory game between frogs and scorpions, with a single point mutation (Lys to Glu) in this motif of the frog's skeletal muscle sodium channel (fNaV1.4), fNaV1.4 breaks this interaction and diminishes muscular toxicity to the frog; thus, frogs can regularly prey on scorpions without showing paralysis. Interestingly, this molecular strategy also has been employed by some other scorpion-eating amphibians, especially anurans. In contrast to these amphibians, the Asp/Lys-Tyr motifs are structurally and functionally conserved in other animals that do not prey on scorpions. Together, our findings elucidate the protein-protein interacting mechanism of a toxin-dominant predator-prey system, implying the evolutionary game theory at a molecular level.
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Affiliation(s)
- Bowen Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University St. Louis, MO 63130, UK
| | - Xiancui Lu
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Luo
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Yunfei Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Lizhen Xu
- Key Laboratory of Medical Neurobiology, Department of Biophysics and Kidney Disease Center, First Affiliated Hospital, Institute of Neuroscience, National Health Commission and Chinese Academy of Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Aerziguli Aierken
- Key Laboratory of Medical Neurobiology, Department of Biophysics and Kidney Disease Center, First Affiliated Hospital, Institute of Neuroscience, National Health Commission and Chinese Academy of Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Zhanserik Shynykul
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Peter Muiruri Kamau
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Anna Luo
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Jian Yang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
- Department of Biological Sciences, Columbia University, New York, NY 10027, UK
| | - Deyuan Su
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Fan Yang
- Key Laboratory of Medical Neurobiology, Department of Biophysics and Kidney Disease Center, First Affiliated Hospital, Institute of Neuroscience, National Health Commission and Chinese Academy of Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University St. Louis, MO 63130, UK
| | - Shilong Yang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
| | - Ren Lai
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming 650223, China
- KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming 650223, China
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Abstract
Recent miniaturization of electronic components and advances in image processing software have facilitated the entry of extended reality technology into clinical practice. In the last several years, the number of applications in cardiology has multiplied, with many promising to become standard of care. We review many of these applications in the areas of patient and physician education, cardiac rehabilitation, pre-procedural planning and intraprocedural use. The rapid integration of these approaches into the many facets of cardiology suggests that they will one day become an every-day part of physician practice.
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Affiliation(s)
| | - Jonathan R Silva
- Sentiar, Inc, Saint Louis, MO, United States; Department of Biomedical Engineering, Washington University School of Engineering and Applied Science, Saint Louis, MO, United States.
| | - Jennifer N Avari Silva
- Sentiar, Inc, Saint Louis, MO, United States; Department of Biomedical Engineering, Washington University School of Engineering and Applied Science, Saint Louis, MO, United States; Division of Pediatric Cardiology, Washington University School of Medicine, Saint Louis, MO, United States.
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Abstract
PURPOSE OF REVIEW Advances in display technology and computing have led to new devices capable of overlaying digital information onto the physical world or incorporating aspects of the physical world into virtual scenes. These combinations of digital and physical environments are referred to as extended realities. Extended reality (XR) devices offer many advantages for medical applications including realistic 3D visualization and touch-free interfaces that can be used in sterile environments. This review introduces extended reality and describes how it can be applied to medical practice. RECENT FINDINGS The 3D displays of extended reality devices are valuable in situations where spatial information such as patient anatomy and medical instrument position is important. Applications that take advantage of these 3D capabilities include teaching and pre-operative planning. The utility of extended reality during interventional procedures has been demonstrated with through 3D visualizations of patient anatomy, scar visualization, and real-time catheter tracking with touch-free software control. Extended reality devices have been applied to education, pre-procedural planning, and cardiac interventions. These devices excel in settings where traditional devices are difficult to use, such as in the cardiac catheterization lab. New applications of extended reality in cardiology will continue to emerge as the technology improves.
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Affiliation(s)
- Christopher Andrews
- Department of Biomedical Engineering, Washington University in St Louis School of Engineering and Applied Science, 1 Brookings Drive, Campus Box 1097, St. Louis, MO, 63130-4899, USA
| | | | - Jennifer N A Silva
- Department of Biomedical Engineering, Washington University in St Louis School of Engineering and Applied Science, 1 Brookings Drive, Campus Box 1097, St. Louis, MO, 63130-4899, USA. .,SentiAR, Inc, 212 N Kingshighway Blvd, Suite #115, St. Louis, MO, 63108, USA. .,Department of Pediatrics, Division of Cardiology, Washington University in St Louis School of Medicine, 1 Children's Place, CB 8116 NWT, St Louis, MO, 63110, USA.
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St Louis School of Engineering and Applied Science, 1 Brookings Drive, Campus Box 1097, St. Louis, MO, 63130-4899, USA. .,SentiAR, Inc, 212 N Kingshighway Blvd, Suite #115, St. Louis, MO, 63108, USA.
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49
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Cruz CS, Costa EP, Machado JA, Silva JN, Romeiro NC, Moraes J, Silva JR, Fonseca RN, Vaz IS, Logullo C, Campos E. A soluble inorganic pyrophosphatase from the cattle tick Rhipicephalus microplus capable of hydrolysing polyphosphates. Insect Mol Biol 2018; 27:260-267. [PMID: 29271528 DOI: 10.1111/imb.12369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Polyphosphates have been found in all cell types examined to date and play diverse roles depending on the cell type. In eukaryotic organisms, polyphosphates have been investigated mainly in mammalian cells, and only a few studies have addressed arthropods. Pyrophosphatases have been shown to regulate polyphosphate metabolism. However, these studies were restricted to trypanosomatids. Here we focus on the tick Rhipicephalus microplus, a haematophagous ectoparasite that is highly harmful to cattle. We produced a recombinant R. microplus pyrophosphatase (rRmPPase) with the aim of investigating its kinetic parameters using polyphosphates as substrate. Molecular docking assays of RmPPase with polyphosphates were also carried out. The kinetic and Hill coefficient parameters indicated that rRmPPase has a greater affinity, higher catalytic efficiency and increased cooperativity for sodium phosphate glass type 15 (polyP15 ) than for sodium tripolyphosphate (polyP3 ). Through molecular docking, we found that polyP3 binds close to the Mg2+ atoms in the catalytic region of the protein, participating in their coordination network, whereas polyP15 interactions involve negatively charged phosphate groups and basic amino acid residues, such as Lys56, Arg58 and Lys193; polyP15 has a more favourable theoretical binding affinity than polyP3 , thus supporting the kinetic data. This study shows, for the first time in arthropods, a pyrophosphatase with polyphosphatase activity, suggesting its participation in polyphosphate metabolism.
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Affiliation(s)
- C S Cruz
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
| | - E P Costa
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - J A Machado
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - J N Silva
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - N C Romeiro
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
| | - J Moraes
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - J R Silva
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - R N Fonseca
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - I S Vaz
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
- Centro de Biotecnologia e Faculdade de Veterinária, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil
| | - C Logullo
- Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal - CBB - UENF, Horto, Campos dos Goytacazes, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
| | - E Campos
- Laboratório Integrado de Bioquímica - Hatisaburo Masuda, UFRJ, NUPEM, São José do Barreto, Macaé, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular, Rio de Janeiro, Brazil
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Zhu W, Voelker TL, Moreno JD, Mazzanti A, Priori SG, Silva JR. Molecular Basis of Mexiletine Response Variability in Sodium Channels with Long QT Mutations. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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