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Voltage Mapping

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https://www.readbyqxmd.com/read/28340110/peri-mitral-atrial-flutter-personalized-ablation-strategy-based-on-arrhythmogenic-substrate
#1
Jinbo Yu, Kai Chen, Bing Yang, Fengxiang Zhang, Weizhu Ju, Hongwu Chen, Gang Yang, Mingfang Li, Benqi Wang, Kai Gu, Feifan Ouyang, Siew Yen Ho, Sunny Po, Minglong Chen
Aims: The aim of this study is to characterize the arrhythmogenic substrate for peri-mitral atrial flutter (PMAFL), thereby determining a personalized ablation strategy to treat PMAFL. Methods and results: Thirty-six consecutive PMAFL patients (mean age: 63.8 ± 11.3, 23 males) underwent detailed three-dimensional electroanatomic mapping in left atrium (LA). The LA was divided into septal-anterior wall (SAW), posterior inferior wall (PIW), and mitral isthmus (MI) region, respectively...
March 1, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28339804/intra-cardiac-and-peripheral-levels-of-biochemical-markers-of-fibrosis-in-patients-undergoing-catheter-ablation-for-atrial-fibrillation
#2
Gordon A Begg, Rashed Karim, Tobias Oesterlein, Lee N Graham, Andrew J Hogarth, Stephen P Page, Christopher B Pepper, Kawal Rhode, Gregory Y H Lip, Arun V Holden, Sven Plein, Muzahir H Tayebjee
Aims: Measurement of circulating biomarkers of fibrosis may have a role in selecting patients and treatment strategy for catheter ablation. Pro-collagen type III N-terminal pro-peptide (PIIINP), C-telopeptide of type I collagen (ICTP), fibroblast growth factor 23 (FGF-23), and galectin 3 (gal-3) have all been suggested as possible biomarkers for this indication, but studies assessing whether peripheral levels reflect intra-cardiac levels are scarce. Methods and results: We studied 93 patients undergoing ablation for paroxysmal atrial fibrillation (AF) (n = 63) or non-paroxysmal AF (n = 30)...
February 27, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28334181/uncovering-the-spatial-profile-of-contour-integration-from-fixational-saccades-evidence-for-widespread-processing-in-v1
#3
Ariel Gilad, Roy Oz, Hamutal Slovin
During contour integration, neuronal populations in the primary visual cortex (V1) enhance their responses to the contour while suppressing their responses to the noisy background. However, the spatial extent and profile of these responses are not fully understood. To investigate this question, 2 monkeys were trained on a contour detection task while we measured population responses in V1 using voltage-sensitive dyes. During stimulus presentation the animals made few fixational saccades, and we used their changing gaze position to image and analyze neuronal responses from large part of the stimulus, encoding multiple contour/background elements...
October 5, 2016: Cerebral Cortex
https://www.readbyqxmd.com/read/28315127/inherited-ventricular-arrhythmias-the-role-of-the-multi-subunit-structure-of-the-l-type-calcium-channel-complex
#4
Julie Briot, Marie-Philippe Tétreault, Benoîte Bourdin, Lucie Parent
The normal heartbeat is conditioned by transient increases in the intracellular free Ca(2+) concentration. Ca(2+) influx in cardiomyocytes is regulated by the activity of the heteromeric L-type voltage-activated CaV1.2 channel. A complex network of interactions between the different proteins forming the ion channel supports the kinetics and the activation gating of the Ca(2+) influx. Alterations in the biophysical and biochemical properties or in the biogenesis in any of these proteins can lead to serious disturbances in the cardiac rhythm...
March 18, 2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28269147/electrocardiogram-reconstruction-from-high-resolution-voltage-optical-mapping
#5
Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton
Electrocardiogram recordings during opucal mapping experiments in heart tissue are commonly used tu monitor the health of the preparation and to obtain dominant frequencies during arrhythmic and defibrillatory studies. However the use of ECG reconstructed from optical mapping is seldom used and to date it has not been strictly validated. In this manuscript we present the first detailed validation and comparison of Optical Mapping ECG, or OM-ECG, with standard ECG recordings by calculating the electrostatic potential in space as a function of the voltage measured optically and describe the different approximations that can be used to obtain unipolar or bipolar ECG recordings...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269146/motion-invariant-contrast-enhancement-of-optical-imaging-data-in-the-gradient-domain
#6
Philipp Flotho, Alejandro Romero-Santiago, Karsten Schwerdtfeger, Jacek Szczygielski, Matthias Hulser, Lars Haab, Daniel J Strauss
Functional optical imaging (OI) of intrinsic signals (like blood oxygenation coupled reflection changes) and of extrinsic properties of voltage sensitive probes (like voltage-sensitive dyes (VSD)) forms a group of neuroimaging techniques that possess up to date highest temporal and spatial resolution on a meso-to macroscopic scale. An inherent problem of OI is a very low signal to noise ratio (SNR), which restricts the recordings to be completely motionless and requires detailed knowledge of the properties of the different noise sources...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28267430/mapping-the-function-of-neuronal-ion-channels-in-model-and-experiment
#7
William F Podlaski, Alexander Seeholzer, Lukas N Groschner, Gero Miesenböck, Rajnish Ranjan, Tim P Vogels
Ion channel models are the building blocks of computational neuron models. Their biological fidelity is therefore crucial for the interpretation of simulations. However, the number of published models, and the lack of standardization, make the comparison of ion channel models with one another and with experimental data difficult. Here, we present a framework for the automated large-scale classification of ion channel models. Using annotated metadata and responses to a set of voltage-clamp protocols, we assigned 2378 models of voltage- and calcium-gated ion channels coded in NEURON to 211 clusters...
March 6, 2017: ELife
https://www.readbyqxmd.com/read/28267401/clinical-electrophysiological-and-imaging-predictors-of-atrial-fibrillation-ablation-outcome
#8
Louisa O'Neill, James Harrison, Mark O'Neill, Steven E Williams
Significant technological advances for catheter ablation of atrial fibrillation (AF) have occurred over the last decade, with a consequent increase in numbers of patients referred for AF ablation worldwide. Despite this, long-term success rates, particularly in those with persistent AF, remain modest. The patient population presenting for AF ablation are heterogeneous with regard to age, type of AF and presence of associated cardiovascular disease. Improved understanding of factors predicting response to AF ablation may therefore help to improve patient selection for ablation procedures...
March 7, 2017: Expert Review of Cardiovascular Therapy
https://www.readbyqxmd.com/read/28250418/pado-a-fluorescent-protein-with-proton-channel-activity-can-optically-monitor-membrane-potential-intracellular-ph-and-map-gap-junctions
#9
Bok Eum Kang, Bradley J Baker
An in silico search strategy was developed to identify potential voltage-sensing domains (VSD) for the development of genetically encoded voltage indicators (GEVIs). Using a conserved charge distribution in the S2 α-helix, a single in silico search yielded most voltage-sensing proteins including voltage-gated potassium channels, voltage-gated calcium channels, voltage-gated sodium channels, voltage-gated proton channels, and voltage-sensing phosphatases from organisms ranging from mammals to bacteria and plants...
July 2016: Scientific Reports
https://www.readbyqxmd.com/read/28240274/low-cost-optical-mapping-systems-for-panoramic-imaging-of-complex-arrhythmias-and-drug-action-in-translational-heart-models
#10
Peter Lee, Conrado J Calvo, José M Alfonso-Almazán, Jorge G Quintanilla, Francisco J Chorro, Ping Yan, Leslie M Loew, David Filgueiras-Rama, José Millet
Panoramic optical mapping is the primary method for imaging electrophysiological activity from the entire outer surface of Langendorff-perfused hearts. To date, it is the only method of simultaneously measuring multiple key electrophysiological parameters, such as transmembrane voltage and intracellular free calcium, at high spatial and temporal resolution. Despite the impact it has already had on the fields of cardiac arrhythmias and whole-heart computational modeling, present-day system designs precludes its adoption by the broader cardiovascular research community because of their high costs...
February 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28236155/cardiac-magnetic-resonance-imaging-and-electroanatomic-voltage-discordance-in-non-ischemic-left-ventricle-ventricular-tachycardia-and-premature-ventricular-depolarizations
#11
Brian P Betensky, Wei Dong, Benjamin A D'Souza, Erica S Zado, Yuchi Han, Francis E Marchlinski
PURPOSE: Magnetic resonance imaging (MRI) with late gadolinium enhancement is commonly performed in patients with non-ischemic LV ventricular tachycardia/ventricular premature depolarizations (non-ischemic LV-VT/VPDs) to define VT substrate prior to catheter ablation. We investigated the prevalence of abnormal voltage and VT localized to areas of the myocardium not reported to have late gadolinium enhancement (LGE) on routine pre-procedural MRI and sought to determine if quantitative MRI analysis could reduce this discordance...
February 24, 2017: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/28227376/electrocardiogram-reconstruction-from-high-resolution-voltage-optical-mapping
#12
Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton, Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton, Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton
Electrocardiogram recordings during opucal mapping experiments in heart tissue are commonly used tu monitor the health of the preparation and to obtain dominant frequencies during arrhythmic and defibrillatory studies. However the use of ECG reconstructed from optical mapping is seldom used and to date it has not been strictly validated. In this manuscript we present the first detailed validation and comparison of Optical Mapping ECG, or OM-ECG, with standard ECG recordings by calculating the electrostatic potential in space as a function of the voltage measured optically and describe the different approximations that can be used to obtain unipolar or bipolar ECG recordings...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227375/motion-invariant-contrast-enhancement-of-optical-imaging-data-in-the-gradient-domain
#13
Philipp Flotho, Alejandro Romero-Santiago, Karsten Schwerdtfeger, Jacek Szczygielski, Matthias Hulser, Lars Haab, Daniel J Strauss, Philipp Flotho, Alejandro Romero-Santiago, Karsten Schwerdtfeger, Jacek Szczygielski, Matthias Hulser, Lars Haab, Daniel J Strauss, Daniel J Strauss, Alejandro Romero-Santiago, Jacek Szczygielski, Karsten Schwerdtfeger, Philipp Flotho, Lars Haab
Functional optical imaging (OI) of intrinsic signals (like blood oxygenation coupled reflection changes) and of extrinsic properties of voltage sensitive probes (like voltage-sensitive dyes (VSD)) forms a group of neuroimaging techniques that possess up to date highest temporal and spatial resolution on a meso-to macroscopic scale. An inherent problem of OI is a very low signal to noise ratio (SNR), which restricts the recordings to be completely motionless and requires detailed knowledge of the properties of the different noise sources...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28220076/actions-and-mechanisms-of-polyunsaturated-fatty-acids-on-voltage-gated-ion-channels
#14
REVIEW
Fredrik Elinder, Sara I Liin
Polyunsaturated fatty acids (PUFAs) act on most ion channels, thereby having significant physiological and pharmacological effects. In this review we summarize data from numerous PUFAs on voltage-gated ion channels containing one or several voltage-sensor domains, such as voltage-gated sodium (NaV), potassium (KV), calcium (CaV), and proton (HV) channels, as well as calcium-activated potassium (KCa), and transient receptor potential (TRP) channels. Some effects of fatty acids appear to be channel specific, whereas others seem to be more general...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28219725/planar-implantable-sensor-for-in-vivo-measurement-of-cellular-oxygen-metabolism-in-brain-tissue
#15
Vassiliy Tsytsarev, Fatih Akkentli, Elena Pumbo, Qinggong Tang, Yu Chen, Reha S Erzurumlu, Dmitri B Papkovsky
BACKGROUND: Brain imaging methods are continually improving. Imaging of the cerebral cortex is widely used in both animal experiments and charting human brain function in health and disease. Among the animal models, the rodent cerebral cortex has been widely used because of patterned neural representation of the whiskers on the snout and relative ease of activating cortical tissue with whisker stimulation. NEW METHOD: We tested a new planar solid-state oxygen sensor comprising a polymeric film with a phosphorescent oxygen-sensitive coating on the working side, to monitor dynamics of oxygen metabolism in the cerebral cortex following sensory stimulation...
February 20, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28211132/comparison-of-left-atrial-voltage-between-sinus-rhythm-and-atrial-fibrillation-in-association-with-electrogram-wave-form
#16
Masaharu Masuda, Masashi Fujita, Osamu Iida, Shin Okamoto, Takayuki Ishihara, Kiyonori Nanto, Takashi Kanda, Akihiro Sunaga, Takuya Tsujimura, Yasuhiro Matsuda, Takuya Ohashi, Masaaki Uematsu
BACKGROUND: The efficacy of low-voltage-guided ablation in addition to pulmonary vein (PV) isolation for atrial fibrillation (AF) has been reported with voltage mapping being performed during sinus rhythm (SR) or AF. The study aimed to compare the left atrial voltage between SR and AF in association with the electrogram wave form. METHODS: This prospective observational study included 30 consecutive patients with persistent AF. After completion of PV isolation, electrogram points were taken during both SR and AF at the identical locations evenly throughout the left atrium...
February 16, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28202723/mapping-of-voltage-sensor-positions-in-resting-and-inactivated-mammalian-sodium-channels-by-lret
#17
Tomoya Kubota, Thomas Durek, Bobo Dang, Rocio K Finol-Urdaneta, David J Craik, Stephen B H Kent, Robert J French, Francisco Bezanilla, Ana M Correa
Voltage-gated sodium channels (Navs) play crucial roles in excitable cells. Although vertebrate Nav function has been extensively studied, the detailed structural basis for voltage-dependent gating mechanisms remain obscure. We have assessed the structural changes of the Nav voltage sensor domain using lanthanide-based resonance energy transfer (LRET) between the rat skeletal muscle voltage-gated sodium channel (Nav1.4) and fluorescently labeled Nav1.4-targeting toxins. We generated donor constructs with genetically encoded lanthanide-binding tags (LBTs) inserted at the extracellular end of the S4 segment of each domain (with a single LBT per construct)...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28199072/genetic-risk-score-analysis-in-early-onset-bipolar-disorder
#18
Paul E Croarkin, Joan L Luby, Kelly Cercy, Jennifer R Geske, Marin Veldic, Matthew Simonson, Paramjit T Joshi, Karen Dineen Wagner, John T Walkup, Malik M Nassan, Alfredo B Cuellar-Barboza, Leah Casuto, Susan L McElroy, Peter S Jensen, Mark A Frye, Joanna M Biernacka
OBJECTIVE: In this study, we performed a candidate genetic risk score (GRS) analysis of early-onset bipolar disorder (BD). METHODS: Treatment of Early Age Mania (TEAM) study enrollment and sample collection took place from 2003 to 2008. Mayo Clinic Bipolar Biobank samples were collected from 2009 to 2013. Genotyping and analyses for the present study took place from 2013 to 2014. The diagnosis of BD was based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria...
February 14, 2017: Journal of Clinical Psychiatry
https://www.readbyqxmd.com/read/28193560/electron-beam-induced-current-and-active-secondary-electron-voltage-contrast-with-aberration-corrected-electron-probes
#19
Myung-Geun Han, Joseph A Garlow, Matthew S J Marshall, Amanda L Tiano, Stanislaus S Wong, Sang-Wook Cheong, Frederick J Walker, Charles H Ahn, Yimei Zhu
The ability to map out electrostatic potentials in materials is critical for the development and the design of nanoscale electronic and spintronic devices in modern industry. Electron holography has been an important tool for revealing electric and magnetic field distributions in microelectronics and magnetic-based memory devices, however, its utility is hindered by several practical constraints, such as charging artifacts and limitations in sensitivity and in field of view. In this article, we report electron-beam-induced-current (EBIC) and secondary-electron voltage-contrast (SE-VC) with an aberration-corrected electron probe in a transmission electron microscope (TEM), as complementary techniques to electron holography, to measure electric fields and surface potentials, respectively...
February 6, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28178296/identification-of-a-vacuolar-proton-channel-that-triggers-the-bioluminescent-flash-in-dinoflagellates
#20
Juan D Rodriguez, Saddef Haq, Tsvetan Bachvaroff, Kristine F Nowak, Scott J Nowak, Deri Morgan, Vladimir V Cherny, Maredith M Sapp, Steven Bernstein, Andrew Bolt, Thomas E DeCoursey, Allen R Place, Susan M E Smith
In 1972, J. Woodland Hastings and colleagues predicted the existence of a proton selective channel (HV1) that opens in response to depolarizing voltage across the vacuole membrane of bioluminescent dinoflagellates and conducts protons into specialized luminescence compartments (scintillons), thereby causing a pH drop that triggers light emission. HV1 channels were subsequently identified and demonstrated to have important functions in a multitude of eukaryotic cells. Here we report a predicted protein from Lingulodinium polyedrum that displays hallmark properties of bona fide HV1, including time-dependent opening with depolarization, perfect proton selectivity, and characteristic ΔpH dependent gating...
2017: PloS One
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