1
|
Maciunas K, Snipas M, Kraujalis T, Kraujalienė L, Panfilov AV. The role of the Cx43/Cx45 gap junction voltage gating on wave propagation and arrhythmogenic activity in cardiac tissue. Sci Rep 2023; 13:14863. [PMID: 37684404 PMCID: PMC10491658 DOI: 10.1038/s41598-023-41796-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023] Open
Abstract
Gap junctions (GJs) formed of connexin (Cx) protein are the main conduits of electrical signals in the heart. Studies indicate that the transitional zone of the atrioventricular (AV) node contains heterotypic Cx43/Cx45 GJ channels which are highly sensitive to transjunctional voltage (Vj). To investigate the putative role of Vj gating of Cx43/Cx45 channels, we performed electrophysiological recordings in cell cultures and developed a novel mathematical/computational model which, for the first time, combines GJ channel Vj gating with a model of membrane excitability to simulate a spread of electrical pulses in 2D. Our simulation and electrophysiological data show that Vj transients during the spread of cardiac excitation can significantly affect the junctional conductance (gj) of Cx43/Cx45 GJs in a direction- and frequency-dependent manner. Subsequent simulation data indicate that such pulse-rate-dependent regulation of gj may have a physiological role in delaying impulse propagation through the AV node. We have also considered the putative role of the Cx43/Cx45 channel gating during pathological impulse propagation. Our simulation data show that Vj gating-induced changes in gj can cause the drift and subsequent termination of spiral waves of excitation. As a result, the development of fibrillation-like processes was significantly reduced in 2D clusters, which contained Vj-sensitive Cx43/Cx45 channels.
Collapse
Affiliation(s)
- Kestutis Maciunas
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Mindaugas Snipas
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
- Department of Mathematical Modelling, Kaunas University of Technology, Kaunas, Lithuania.
| | - Tadas Kraujalis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
- Department of Applied Informatics, Kaunas University of Technology, Kaunas, Lithuania
| | - Lina Kraujalienė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Alexander V Panfilov
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| |
Collapse
|
2
|
Maltsev AV, Stern MD, Lakatta EG, Maltsev VA. Functional Heterogeneity of Cell Populations Increases Robustness of Pacemaker Function in a Numerical Model of the Sinoatrial Node Tissue. Front Physiol 2022; 13:845634. [PMID: 35574456 PMCID: PMC9091312 DOI: 10.3389/fphys.2022.845634] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/15/2022] [Indexed: 11/19/2022] Open
Abstract
Each heartbeat is initiated by specialized pacemaker cells operating within the sinoatrial node (SAN). While individual cells within SAN tissue exhibit substantial heterogeneity of their electrophysiological parameters and Ca cycling, the role of this heterogeneity for cardiac pacemaker function remains mainly unknown. Here we investigated the problem numerically in a 25 × 25 square grid of connected coupled-clock Maltsev-Lakatta cell models. The tissue models were populated by cells with different degree of heterogeneity of the two key model parameters, maximum L-type Ca current conductance (gCaL) and sarcoplasmic reticulum Ca pumping rate (Pup). Our simulations showed that in the areas of Pup-gCaL parametric space at the edge of the system stability, where action potential (AP) firing is absent or dysrhythmic in SAN tissue models populated with identical cells, rhythmic AP firing can be rescued by populating the tissues with heterogeneous cells. This robust SAN function is synergistic with respect to heterogeneity in gCaL and Pup and can be further strengthened by clustering of cells with similar properties. The effect of cell heterogeneity is not due to a simple summation of activity of intrinsically firing cells naturally present in heterogeneous SAN; rather AP firing cells locally and critically interact with non-firing/dormant cells. When firing cells prevail, they recruit many dormant cells to fire, strongly enhancing overall SAN function; and vice versa, prevailing dormant cells suppress AP firing in cells with intrinsic automaticity and halt SAN function. The transitions between firing and non-firing states of the system are sharp, resembling phase transitions in statistical physics. Furthermore, robust function of heterogeneous SAN tissue requires weak cell coupling, a known property of the central area of SAN where cardiac impulse emerges; stronger cell coupling reduces AP firing rate and ultimately halts SAN automaticity at the edge of stability.
Collapse
|
3
|
Dunham CS, Mackenzie ME, Nakano H, Kim AR, Juda MB, Nakano A, Stieg AZ, Gimzewski JK. Pacemaker translocations and power laws in 2D stem cell-derived cardiomyocyte cultures. PLoS One 2022; 17:e0263976. [PMID: 35286321 PMCID: PMC8920264 DOI: 10.1371/journal.pone.0263976] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/01/2022] [Indexed: 11/18/2022] Open
Abstract
Power laws are of interest to several scientific disciplines because they can provide important information about the underlying dynamics (e.g. scale invariance and self-similarity) of a given system. Because power laws are of increasing interest to the cardiac sciences as potential indicators of cardiac dysfunction, it is essential that rigorous, standardized analytical methods are employed in the evaluation of power laws. This study compares the methods currently used in the fields of condensed matter physics, geoscience, neuroscience, and cardiology in order to provide a robust analytical framework for evaluating power laws in stem cell-derived cardiomyocyte cultures. One potential power law-obeying phenomenon observed in these cultures is pacemaker translocations, or the spatial and temporal instability of the pacemaker region, in a 2D cell culture. Power law analysis of translocation data was performed using increasingly rigorous methods in order to illustrate how differences in analytical robustness can result in misleading power law interpretations. Non-robust methods concluded that pacemaker translocations adhere to a power law while robust methods convincingly demonstrated that they obey a doubly truncated power law. The results of this study highlight the importance of employing comprehensive methods during power law analysis of cardiomyocyte cultures.
Collapse
Affiliation(s)
- Christopher S. Dunham
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, United States of America
| | - Madelynn E. Mackenzie
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, California, United States of America
| | - Haruko Nakano
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California, United States of America
| | - Alexis R. Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, United States of America
| | - Michal B. Juda
- Molecular Biology Institute, University of California, Los Angeles, California, United States of America
| | - Atsushi Nakano
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California, United States of America
- Molecular Biology Institute, University of California, Los Angeles, California, United States of America
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, California, United States of America
- Division of Cardiology, Department of Medicine, University of California, Los Angeles, California, United States of America
- Department of Cell Physiology, The Jikei University, Tokyo, Japan
| | - Adam Z. Stieg
- California NanoSystems Institute, University of California, Los Angeles, California, United States of America
- International Center for Materials Nanoarchitectonics (MANA), National Institute of Materials Science, Tsukuba, Japan
| | - James K. Gimzewski
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California, Los Angeles, California, United States of America
- International Center for Materials Nanoarchitectonics (MANA), National Institute of Materials Science, Tsukuba, Japan
| |
Collapse
|
4
|
Phillips B, Anand M, Bauch CT. Spatial early warning signals of social and epidemiological tipping points in a coupled behaviour-disease network. Sci Rep 2020; 10:7611. [PMID: 32376908 PMCID: PMC7203335 DOI: 10.1038/s41598-020-63849-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 04/06/2020] [Indexed: 01/12/2023] Open
Abstract
The resurgence of infectious diseases due to vaccine refusal has highlighted the role of interactions between disease dynamics and the spread of vaccine opinion on social networks. Shifts between disease elimination and outbreak regimes often occur through tipping points. It is known that tipping points can be predicted by early warning signals (EWS) based on characteristic dynamics near the critical transition, but the study of EWS in coupled behaviour-disease networks has received little attention. Here, we test several EWS indicators measuring spatial coherence and autocorrelation for their ability to predict a critical transition corresponding to disease outbreaks and vaccine refusal in a multiplex network model. The model couples paediatric infectious disease spread through a contact network to binary opinion dynamics of vaccine opinion on a social network. Through change point detection, we find that mutual information and join count indicators provided the best EWS. We also show the paediatric infectious disease natural history generates a discrepancy between population-level vaccine opinions and vaccine immunity status, such that transitions in the social network may occur before epidemiological transitions. These results suggest that monitoring social media for EWS of paediatric infectious disease outbreaks using these spatial indicators could be successful.
Collapse
Affiliation(s)
- Brendon Phillips
- University of Waterloo, Department of Mathematics, Waterloo, N2L 3G1, Canada.
| | - Madhur Anand
- University of Guelph, School of Environmental Sciences, Guelph, N1G 2W1, Canada
| | - Chris T Bauch
- University of Waterloo, Department of Mathematics, Waterloo, N2L 3G1, Canada
| |
Collapse
|
5
|
Abstract
Generated and collected data have been rising with the popularization of technologies such as Internet of Things, social media, and smartphone, leading big data term creation. One class of big data hidden information is causality. Among the tools to infer causal relationships, there is Delay Transfer Entropy (DTE); however, it has a high demanding processing power. Many approaches were proposed to overcome DTE performance issues such as GPU and FPGA implementations. Our study compared different parallel strategies to calculate DTE from big data series using a heterogeneous Beowulf cluster. Task Parallelism was significantly faster in comparison to Data Parallelism. With big data trend in sight, these results may enable bigger datasets analysis or better statistical evidence.
Collapse
|
6
|
Costabal FS, Matsuno K, Yao J, Perdikaris P, Kuhl E. Machine learning in drug development: Characterizing the effect of 30 drugs on the QT interval using Gaussian process regression, sensitivity analysis, and uncertainty quantification. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2019; 348:313-333. [PMID: 32863454 PMCID: PMC7454226 DOI: 10.1016/j.cma.2019.01.033] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Prolonged QT intervals are a major risk factor for ventricular arrhythmias and a leading cause of sudden cardiac death. Various drugs are known to trigger QT interval prolongation and increase the proarrhythmic potential. Yet, how precisely the action of drugs on the cellular level translates into QT interval prolongation on the whole organ level remains insufficiently understood. Here we use machine learning techniques to systematically characterize the effect of 30 common drugs on the QT interval. We combine information from high fidelity three-dimensional human heart simulations with low fidelity one-dimensional cable simulations to build a surrogate model for the QT interval using multi-fidelity Gaussian process regression. Once trained and cross-validated, we apply our surrogate model to perform sensitivity analysis and uncertainty quantification. Our sensitivity analysis suggests that compounds that block the rapid delayed rectifier potassium current I Kr have the greatest prolonging effect of the QT interval, and that blocking the L-type calcium current I CaL and late sodium current I NaL shortens the QT interval. Our uncertainty quantification allows us to propagate the experimental variability from individual block-concentration measurements into the QT interval and reveals that QT interval uncertainty is mainly driven by the variability in I Kr block. In a final validation study, we demonstrate an excellent agreement between our predicted QT interval changes and the changes observed in a randomized clinical trial for the drugs dofetilide, quinidine, ranolazine, and verapamil. We anticipate that both the machine learning methods and the results of this study will have great potential in the efficient development of safer drugs.
Collapse
Affiliation(s)
| | - Kristen Matsuno
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jiang Yao
- Dassault Systèmes Simulia Corporation, Johnston, RI 02919, USA
| | - Paris Perdikaris
- Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ellen Kuhl
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
| |
Collapse
|
7
|
Khaluf Y, Simoens P, Hamann H. The Neglected Pieces of Designing Collective Decision-Making Processes. Front Robot AI 2019; 6:16. [PMID: 33501032 PMCID: PMC7805907 DOI: 10.3389/frobt.2019.00016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 02/28/2019] [Indexed: 12/01/2022] Open
Abstract
Autonomous decision-making is a fundamental requirement for the intelligent behavior of individual agents and systems. For artificial systems, one of the key design prerequisites is providing the system with the ability to make proper decisions. Current literature on collective artificial systems designs decision-making mechanisms inspired mostly by the successful natural systems. Nevertheless, most of the approaches focus on voting mechanisms and miss other fundamental aspects. In this paper, we aim to draw attention to the missed pieces for the design of efficient collective decision-making, mainly information processes in its two types of stimuli and options set.
Collapse
Affiliation(s)
- Yara Khaluf
- IDLab, Ghent University-Imec, Ghent, Belgium
| | | | - Heiko Hamann
- Institute of Computer Engineering, University of Lübeck, Lübeck, Germany
| |
Collapse
|
8
|
Sohn D, Aronis K, Ashikaga H. Scale-invariant structures of spiral waves. Comput Biol Med 2018; 104:291-298. [PMID: 30458961 DOI: 10.1016/j.compbiomed.2018.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 11/06/2018] [Accepted: 11/07/2018] [Indexed: 01/13/2023]
Abstract
BACKGROUND Spiral waves are considered to be one of the potential mechanisms that maintain complex arrhythmias such as atrial and ventricular fibrillation. The aim of the present study was to quantify the complex dynamics of spiral waves as the organizing manifolds of information flow at multiple scales. METHOD We simulated spiral waves using a numerical model of cardiac excitation in a two-dimensional (2-D) lattice. We created a renormalization group by coarse graining and re-scaling the original time series in multiple spatiotemporal scales, and quantified the Lagrangian coherent structures (LCS) of the information flow underlying the spiral waves. To quantify the scale-invariant structures, we compared the value of the finite-time Lyapunov exponent between the corresponding components of the 2-D lattice in each spatiotemporal scale of the renormalization group with that of the original scale. RESULTS Both the repelling and the attracting LCS changed across the different spatial and temporal scales of the renormalization group. However, despite the change across the scales, some LCS were scale-invariant. The patterns of those scale-invariant structures were not obvious from the trajectory of the spiral waves based on voltage mapping of the lattice. CONCLUSIONS Some Lagrangian coherent structures of information flow underlying spiral waves are preserved across multiple spatiotemporal scales.
Collapse
Affiliation(s)
- Daniel Sohn
- Cardiac Arrhythmia Service, Johns Hopkins University School of Medicine, 600 N Wolfe Street, Carnegie 568, Baltimore, MD, USA
| | - Konstantinos Aronis
- Cardiac Arrhythmia Service, Johns Hopkins University School of Medicine, 600 N Wolfe Street, Carnegie 568, Baltimore, MD, USA
| | - Hiroshi Ashikaga
- Cardiac Arrhythmia Service, Johns Hopkins University School of Medicine, 600 N Wolfe Street, Carnegie 568, Baltimore, MD, USA; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600, Pessac-Bordeaux, France.
| |
Collapse
|
9
|
Ashikaga H, James RG. Inter-scale information flow as a surrogate for downward causation that maintains spiral waves. CHAOS (WOODBURY, N.Y.) 2018; 28:075306. [PMID: 30070515 DOI: 10.1063/1.5017534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A rotor, the rotation center of spiral waves, has been proposed as a causal mechanism to maintain atrial fibrillation (AF) in human. However, our current understanding of the causality between rotors and spiral waves remains incomplete. One approach to improving our understanding is to determine the relationship between rotors and downward causation from the macro-scale collective behavior of spiral waves to the micro-scale behavior of individual components in a cardiac system. This downward causation is quantifiable as inter-scale information flow that can be used as a surrogate for the mechanism that maintains spiral waves. We used a numerical model of a cardiac system and generated a renormalization group with system descriptions at multiple scales. We found that transfer entropy quantified the upward and downward inter-scale information flow between micro- and macro-scale descriptions of the cardiac system with spiral waves. In addition, because the spatial profile of transfer entropy and intrinsic transfer entropy was identical, there were no synergistic effects in the system. Furthermore, inter-scale information flow significantly decreased as the description of the system became more macro-scale. Finally, downward information flow was significantly correlated with the number of rotors, but the higher numbers of rotors were not necessarily associated with higher downward information flow. This finding contradicts the concept that the rotors are the causal mechanism that maintains spiral waves, and may account for the conflicting evidence from clinical studies targeting rotors to eliminate AF.
Collapse
Affiliation(s)
- Hiroshi Ashikaga
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600 Pessac-Bordeaux, France
| | - Ryan G James
- Department of Physics, Complexity Sciences Center, University of California, Davis, One Shields Avenue, Davis, California 95616-8572, USA
| |
Collapse
|