Article
Biochemical Research Methods
Shawn A. Means, Mathias W. Roesler, Amy S. Garrett, Leo Cheng, Alys R. Clark
Summary: Explored the feasibility of extensive reduction of order for a cell model based on the Hodkgin-Huxley formalism. Substituting dynamic ion channel variables with steady-state approximations significantly improved time-to-solve and accurately reproduced the full model.
PLOS COMPUTATIONAL BIOLOGY
(2023)
Article
Cell Biology
Ji Yeon Lee, Haifeng Zheng, Kenton M. Sanders, Sang Don Koh
Summary: In murine antral smooth muscle cells, low-voltage-activated inward currents are generated by K+ influx via KA channels, rather than T-type Ca2+ channels, Ca2+-activated Cl- channels, or nonselective cation channels.
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY
(2021)
Article
Cardiac & Cardiovascular Systems
Quentin Lachaud, Muhamad Hifzhudin Noor Aziz, Francis L. Burton, Niall Macquaide, Rachel C. Myles, Radostin D. Simitev, Godfrey L. Smith
Summary: The aim of this study is to assess intra-regional differences in the action potential waveform and quantify the contribution of specific ion channels to the action potential duration (APD) in rabbit ventricular cells. The results show that there is considerable inter-cell variation in channel/pump/exchanger activity in ventricular tissue, and specific interrelationships between ionic conductances are necessary for stable repolarization despite large inter-cell variation of individual conductances, which explains the variable sensitivity to ion channel block.
CARDIOVASCULAR RESEARCH
(2022)
Article
Biochemistry & Molecular Biology
Wei Hu, Robert B. Clark, Wayne R. Giles, Erwin Shibata, Henggui Zhang
Summary: Through anatomical, electrophysiological, molecular methods, and mathematical modeling approaches, the mechanisms of generating sinoatrial node action potentials and depolarizations have been thoroughly characterized.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2021)
Article
Physiology
Arsenii Dokuchaev, Alexander Kursanov, Nathalie A. Balakina-Vikulova, Leonid B. Katsnelson, Olga Solovyova
Summary: This study investigates the role of cardiomyocyte mechanical activity under different mechanical conditions in the generation, calibration, and validation of a population of electro-mechanical models of human cardiomyocytes. More than 10% of the models calibrated on electrophysiological data failed mechanical tests and were rejected from the population due to excitation abnormalities at reduced preload or afterload for cell contraction. The final population of accepted models yielded action potential, calcium transient, and force/shortening outputs consistent with experimental data.
FRONTIERS IN PHYSIOLOGY
(2023)
Article
Optics
Yonghao Mi, Kyle Johnston, Valentina Shumakova, Soren H. Moller, Kamalesh Jana, Chunmei Zhang, Andre Staudte, Shawn Sederberg, Paul B. Corkum
Summary: Intense laser fields focused in ambient air can generate high-bandwidth current densities, with the amplitude and sign of these currents controlled by adjusting the relative phase. Two-color filamentation in gas targets allows for increasing the energy of terahertz pulses. However, controlling the waveform stability is challenging. By comparing current density detection and terahertz field detection, a clear connection between phase-dependent plasma currents and terahertz radiation is established. Current measurement can be used as a feedback parameter to stabilize the terahertz waveform, providing a route to energetic terahertz pulses with exceptional waveform stability.
PHOTONICS RESEARCH
(2022)
Article
Multidisciplinary Sciences
Carlos A. H. Fernandes, Dania Zuniga, Charline Fagnen, Valerie Kugler, Rosa Scala, Gerard Pehau-Arnaudet, Renaud Wagner, David Perahia, Said Bendahhou, Catherine Venien-Bryan
Summary: This study revealed the unique structural features of human Kir2.1 channels, as well as the connection between the G-loop and gating, shedding light on the pathological mechanisms associated with this channel.
Article
Physiology
Michael Clerx, Gary R. Mirams, Albert J. Rogers, Sanjiv M. Narayan, Wayne R. Giles
Summary: This study investigates the effects of clinical hypokalemia on the human atrial action potential using mathematical models, finding that changes in plasma K+ levels can lead to electrophysiological alterations in the heart and potentially trigger arrhythmias. The rapid response involves modifications in the K+-sensing mechanism of the inward rectifier current, while a slower response results from shifts in intracellular electrolyte balance, affecting the Na+/K+ pump and changing the electrophysiological substrate of the human atrium.
FRONTIERS IN PHYSIOLOGY
(2021)
Article
Physiology
Vishwanath Jogini, Morten O. Jensen, David E. E. Shaw
Summary: This article presents the results of long-timescale molecular dynamics simulations to describe the lipid-dependent gating and spermine-induced inward rectification of the inward-rectifier potassium channel Kir2.2. PIP2 binding increases the stability of the channel in its open and conducting state, while spermine binds to a site located between the pore cavity and the selectivity filter. Additionally, charged residues in the cytoplasmic domain modulate conduction and rectification through finely tuned charge density.
JOURNAL OF GENERAL PHYSIOLOGY
(2022)
Article
Biochemistry & Molecular Biology
Yukiko Himeno, Yixin Zhang, Suzuka Enomoto, Hiroto Nomura, Natsuki Yamamoto, Shotaro Kiyokawa, Mirei Ujihara, Yuttamol Muangkram, Akinori Noma, Akira Amano
Summary: This study investigates the propagation mechanism of repolarization in cardiac tissue using a mathematical model. The results indicate that late sodium current, L-type calcium current, delayed rectifier potassium current, and inward rectifier potassium channel play important roles in the propagation of repolarization in the myocyte strand.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Cardiac & Cardiovascular Systems
Bastiaan J. D. Boukens, Michael Dacey, Veronique M. F. Meijborg, Michiel J. Janse, Joseph Hadaya, Peter Hanna, M. Amer Swid, Tobias Opthof, Jeffrey L. Ardell, Kalyanam Shivkumar, Ruben Coronel
Summary: Enhanced sympathetic activity during acute ischemia causes arrhythmias, with a mechanism involving a diastolic current flowing from the ischemic to non-ischemic myocardium. Stimulation of the left stellate ganglion shortens repolarization in non-ischemic myocardium, leading to more negative T waves in the ischemic zone and ventricular premature beats from normal tissue nearby.
CARDIOVASCULAR RESEARCH
(2021)
Article
Multidisciplinary Sciences
Daniel T. Citron, Carlos A. Guerra, Andrew J. Dolgert, Sean L. Wu, John M. Henry, Hector M. C. Sanchez, David L. Smith
Summary: Newly available datasets offer opportunities to investigate the role of human population movement in the spread of infectious diseases globally, but leveraging the data to parameterize movement models and understanding their impact on disease outcomes remains a question. Adaptations of infectious disease models with different movement models show significant impact on epidemiological outcomes, highlighting the importance of choosing an appropriate movement model in disease modeling.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Mechanics
M. Ungarish
Summary: The study investigates the propagation of a gravity current generated from a moving source of buoyancy in deep-sea mining and related technologies. The researchers present a simple box model to gain further insights and useful analytical approximations for the flow system. The model confirms that the main governing parameter is the ratio of the speed of the source to the speed of buoyancy propagation. The study highlights the importance of the front-jump Froude number in determining the behavior of the gravity current.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
Roberto Barrio, M. Angeles Martinez, Sergio Serrano, Esther Pueyo
Summary: In this study, the dynamical mechanisms underlying the formation of arrhythmogenic early afterdepolarizations (EADs) in cardiac cellular electrophysiology were analyzed using two mathematical models. The results identified the point of origin for the first EAD and proposed a theoretical scheme involving a hysteresis mechanism with the creation of alternans and EADs. The findings were consistent with experimental data and offer potential for novel methods in predicting arrhythmia risk related to EAD generation.
Article
Engineering, Biomedical
James A. Beauchamp, Gregory E. P. Pearcey, Obaid U. Khurram, Matthieu Chardon, Y. Curtis Wang, Randall K. Powers, Julius P. A. Dewald, C. J. Heckman
Summary: This study presents a novel geometric approach to estimate the contribution of neuromodulatory and inhibitory inputs to motor unit (MU) discharge. By exploiting the discharge nonlinearities introduced by persistent inward currents (PIC) amplification, we quantify the deviation from linear discharge (brace height) and the rate of change in discharge (acceleration slope, attenuation slope, angle). These metrics provide intuitive methods for assessing neuromodulatory and inhibitory drive to individual MUs.
JOURNAL OF NEURAL ENGINEERING
(2023)