Activation Patterns of Purkinje Fibers During Long-Duration Ventricular Fibrillation in an Isolated Canine Heart Model |...
Thank you for your interest in spreading the word on Circulation.. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address. ...http://circ.ahajournals.org/content/early/2007/08/13/CIRCULATIONAHA.107.699264
High-Resolution Optical Mapping of the Right Bundle Branch in Connexin40 Knockout Mice Reveals Slow Conduction in the...
Intercellular coupling via gap junction channels is an important determinant of impulse propagation in the heart.1 These channels provide a low resistance pathway that is essential for the coordinated spread of electrical activation, which subsequently triggers the contraction of the heart. Recent studies have indicated that alterations in the expression pattern of cardiac connexin proteins may lead to abnormal electrical coupling and arrhythmias.2 3 4 5 6 Therefore, understanding the role of intercellular communication in impulse propagation is essential.. Three connexins, Cx40, Cx43, and Cx45, are thought to be involved in impulse propagation in the myocardium. Detailed immunolocalization studies have shown that each of these proteins has a unique pattern of expression in the adult heart;6 7 8 however, the functional role of connexin proteins in impulse propagation remains poorly understood. The presence and expression levels of these connexins vary considerably in cardiac tissues with ...http://circres.ahajournals.org/content/87/10/929
Laser Focus World April 2009
Wu's team uses voltage-sensitive dye imaging that visualizes patterns in the brain's cortex. Neocortical columns-containing as many as 60,000 neurons- correspond to a sensory stimulus input to the human body. When imaged in motion, patterns such as spiraling waves can be seen during epileptic seizures and in the heart during cardiac fibrillation, shedding light on the relationship of brain patterns to trauma and disease. Because voltage-sensitive dye signals are small (typically a 0.1% to 1.0% change in illumination intensity), extreme vibration isolation is required to exclude external vibrations from air conditioning or ambulatory movement of lab personnel, insuring that only the neuronal fluctuations are imaged. Contact David Platus at firstname.lastname@example.org ...https://www.minusk.com/content/in-the-news/LasFocW_0409.html
RAPID REPORT: Initiation of simple and complex spikes in cerebellar Purkinje cells - Palmer - 2010 - The Journal of Physiology ...
A comparison of the distance dependence of axosomatic delays measured using three different techniques (extracellular recording, voltage-sensitive dye imaging and cell-attached capacitive current recording) is shown in Fig. 3. Cell-attached recordings were compiled from previously published data (Clark et al. 2005) together with additional new data points. For each method, raw pooled data are shown in Fig. 3A. By smoothing this data either by binning (Fig. 3B) or by using a 10-point moving average (Fig. 3C) the location of distinct minima (i.e. points of longest delay; arrows, Fig. 3C) becomes apparent. Unlike a bilinear fit (Clark et al. 2005; Meeks et al. 2005), the 10-point moving average does not impose a specific hypothesis regarding the shape of the distance-delay relationship on the data. Both the extracellular (left column of Fig. 3C) and the voltage-sensitive dye data (middle column ...http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2010.188300/full
Similar papers for Spiral Wave Dynamics in Neocortex - Semantic Scholar
Although spiral waves are ubiquitous features of nature and have been observed in many biological systems, their existence and potential function in mammalian cerebral cortex remain uncertain. Using voltage-sensitive dye imaging, we found that spiral waves occur frequently in the neocortex in vivo, both during pharmacologically induced oscillations and during sleep-like states. While their life span is limited, spiral waves can modify ongoing cortical activity by influencing oscillation frequencies and spatial coherence and by reducing amplitude in the area surrounding the spiral phase singularity. During sleep-like states, the rate of occurrence of spiral waves varies greatly depending on brain states. These results support the hypothesis that spiral waves, as an emergent activity pattern, can organize and modulate cortical population activity on the mesoscopic scale and may contribute to both normal cortical processing and ...https://www.semanticscholar.org/paper/Spiral-Wave-Dynamics-in-Neocortex-Huang-Xu/9bda415d86889f6b4540a2cb461a49de5c7de2c7?tab=relatedPapers
Voltage-sensitive fluorescence imaging on the heart surface | (2004) | Popp | Publications | Spie
Optical methods provide a rather precise insight into cardiac electrical activity. Voltage-sensitive dyes like di 4-ANEPPS convert the electric signal into a fluorescent signal that can be measured by standard optical methods. A realistic picture of the dynamic patterns that govern electrical activity in the human heart can be obtained only with thick tissue preparations, from large animals. We measure the fluorescence signal of an approximately 2.5 x 2.5 cm area on the surface of 8 mm thick porcine right ventricle preparations with a fast CCD camera at low magnification, and perform advanced simulations of the macroscopic dynamic features involved. To extract meaningful qualitative and quantitative data from these signals, details of the conversion from electrical to optical signal have to be known, and the problem of the 2D surface signal originating from a 3D distribution below has to be addressed. We compare experiment to simulation results applying a ...http://spie.org/Publications/Proceedings/Paper/10.1117/12.529244
OSA | Using optical mapping of the internal signal to test the function of the visual cerebral cortex in mammals
Optical mapping of the internal signal is a unique method of studying the brain and makes it possible to investigate the functional anatomy of the cerebral cortex with high spatial resolution. Modern modifications of this method make it possible to shorten the time to obtain individual functional maps, and this opens up new prospects of using the given approach in neurophysiological experiments. It is shown to be possible in principle to use optical mapping of the internal signal to objectively test the visual function: As the contrast of the visual stimulus changes, changes have been observed in both the amplitude of the metabolic response in the cortex and in the structure of the functional maps.. © 2011 OSA. PDF Article ...https://www.osapublishing.org/jot/abstract.cfm?uri=jot-78-12-777
UAB - School of Engineering - Cardiac Electrophysiology
Much electrophysiology work involves recording electrical potentials. CRML is equipped to record such potentials from single cells, cultured cell monolayers, isolated heart preparations, and in situ hearts. Cardiac mapping is the process of recording from many spatially distributed sites simultaneously. CRML has electrical mapping systems that can record signals from over 1000 extracellular electrodes. Optical mapping uses voltage-sensitive dyes to transduce electrical potentials into fluorescence. CRML is equipped to record this information with both photodiode arrays and high-speed video cameras. CRML is also equipped to record from intracellular and extracellular microelectrodes ...http://www.uab.edu/engineering/home/2013-symposium/aboutbme/13-departments-research/dept-biomedical-eng/779-bme-research-cardiac-electrophysiology
Patent US4954380 - Optical recording medium and process for production thereof - Google Patents
An optical recording medium comprises an optical recording layer on a transparent substrate. The optical recording layer is then selectively irradiated with an energy beam to form therein a tracking region for guiding a laser beam for recording and reproduction. The tracking region is free of unevenness and has an optical characteristic different from that of the portion of the optical recording constituting a data recording region which has not been irradiated with the laser beam.http://www.google.ca/patents/US4954380
Abstract 13633: ZP1210, a Novel Gap Junction Modulator, Attenuates Conduction Slowing and Prevents Cx43 Dephosphorylation...
Background: ZP1210 is a novel peptide from the same family as rotigaptide (ZP123) and AAP10, which are agents known to prevent gap junctional uncoupling. We used optical mapping to assess the effects of ZP1210 on conduction and action potentials in a model of metabolic stress and used immunoblotting to assess its effects on Cx43 phophorylation in the context of regional ischaemia.. Methods: Eight Sprague-Dawley rat hearts were isolated, perfused and loaded with the voltage-sensitive dye RH237. Hearts were perfused with either 50nM ZP1210 (n=3) or control (n=5) for 20 minutes, before being subjected to metabolic stress (hypoxic hypoperfusion at 5ml/min) for 30 minutes, and a subsequent 10 minutes of reperfusion with oxygenated perfusate at normal coronary flow rates. Epicardial activation was optically mapped every minute using a 256-photodiode array. A further 7 hearts were subjected to regional left anterior descending artery ischaemia (ZP1210: n=4, control ...http://circ.ahajournals.org/content/122/Suppl_21/A13633
Optical Mapping of Action Potentials and Calcium Transients in the Mouse Heart | Protocol
This paper details the dissection procedure, instrumental setup, and experimental conditions during optical mapping of transmembrane...https://www.jove.com/video/3275/optical-mapping-action-potentials-calcium-transients-mouse
Laboratory Equipment July 2009
Voltage-sensitive dye is a compound that stains neuronal membrane and changes its color when the neuron is excited,' Wu continues. 'This allows us to visualize population neuronal activity dynamically in the cortex. We study how individual neurons in the neocortex interact to generate population neuronal activities that underlie sensory and motor processing functions. Population activities are composed of the coordinated activity of up to billions of neurons. Currently, we study how oscillations and propagating waves can be generated by small ensembles of neocortical neurons ...https://www.minusk.com/content/in-the-news/LabEqu_0709.html
Brain Cell Biology [Journal] Publications and Abstracts | PubFacts.com
We have assessed the utility of five new long-wavelength fluorescent voltage-sensitive dyes (VSD) for imaging the activity of populations of neurons in mouse brain slices. Although all the five were capable of detecting activity resulting from activation of the Schaffer collateral-CA1 pyramidal cell synapse, they differed significantly in their properties, most notably in the signal-to-noise ratio of the changes in dye fluorescence associated with neuronal activity. Two of these dyes, Di-2-ANBDQPQ and Di-1-APEFEQPQ, should prove particularly useful for imaging activity in brain tissue and for combining VSD imaging with the control of neuronal activity via light-activated proteins such as channelrhodopsin-2 and halorhodopsin. Read More ...https://www.pubfacts.com/search/Brain+Cell+Biology%0D%09+%0D%5BJournal%5D
Here we monitor VSD signals that report changes in membrane potential over large regions of the mouse cortex to study the spatial and temporal dynamics of spontaneous cortical oscillations present in the anesthetized and quiet awake mouse brain. This activity is highly synchronized across multiple brain regions and both hemispheres and, in particular, association cortices located in midline regions. Previous studies, using fMRI to measure much slower brain oscillations (infra-slow oscillations ,0.1 Hz) have shown a similar regional pattern (Fox et al., 2006). This pattern may reflect a default network of regions that are active during rest and tasked with global monitoring of internal environment and multimodal integration of information (Alkire et al., 2008). Our results are generally consistent with this hypothesis and now extend the observation to significantly higher frequencies. As in infra-slow activity in the human and primate brain, higher-frequency slow-wave oscillation in the mouse ...http://www.jneurosci.org/content/30/10/3745
Reinduction of Atrial Fibrillation Immediately After Termination of the Arrhythmia Is Mediated by Late Phase 3 Early...
IRAF after electrical cardioversion has been reported in a sizable fraction of patients (13% to 27%).1-5 The IRAF is caused by an atrial extrasystole,1,2 the mechanism of development of which is largely unknown. In the present study, we have developed an experimental model that recapitulates these clinical phenomena, permitting evaluation of the cellular mechanisms involved. The model consists of a coronary-perfused canine right atrial preparation in which cholinergically mediated AF can be readily induced by rapid pacing and in which transmembrane, ECG, and mechanical data can be correlated.. Our study provides evidence in support of the hypothesis that very rapid rates of excitation, as occur during AF, lead to an elevation of intracellular calcium, which in turn can contribute to the development of EAD-induced extrasystoles capable of reinitiating AF soon after termination of the arrhythmia.. The mechanism responsible for the transient increase in contractility immediately after the ...http://circ.ahajournals.org/content/107/18/2355
The role of photon scattering in voltage-calcium fluorescent recordings of ventricular fibrillation - Physiology, Anatomy and...
Recent optical mapping studies of cardiac tissue suggest that membrane voltage (V m ) and intracellular calcium concentrations (Ca) become dissociated during ventricular fibrillation (VF), generating a proarrhythmic substrate. However, experimental methods used in these studies may accentuate measured dissociation due to differences in fluorescent emission wavelengths of optical voltage/calcium (V opt /Ca opt ) signals. Here, we simulate dual voltage-calcium optical mapping experiments using a monodomain-Luo-Rudy ventricular-tissue model coupled to a photon-diffusion model. Dissociation of both electrical, V m /Ca, and optical, V opt /Ca opt , signals is quantified by calculating mutual information (MI) for VF and rapid pacing protocols. We find that photon scattering decreases MI of V opt /Ca opt signals by 23% compared to unscattered V m /Ca signals during VF. Scattering effects are amplified by increasing wavelength separation between ...https://www.dpag.ox.ac.uk/publications/179750
Patent US5645910 - Formazan-cyanine copolymers dyes for optical recording layers and elements - Google Patents
A copolymer comprising 70 to 100 mole percent of repeating units comprising a formazan dye radical and a cyanine dye radical. The copolymers are useful in recording layers of optical recording elements.http://www.google.com.au/patents/US5645910
Patent US6746746 - Laser beam optical recording medium featuring several read/write levels - Google Patents
The inventions relates to a laser beam optical recording medium which features several read/write levels, comprising a first half-transparent level and at least a second level, the first one being close to the laser transmitting source, each level comprising a phase changing material layer with two stable states controlled by a laser beam, where the phase changing material is a metallic alloy whose chemical formula writes as: [(GeyTe1-y)a(SbzTe1-z)1-a]1-b(In1-xTex)b with: 0.4≦y≦0.6 0.3≦z≦0.5 0.4≦x≦0.6 0.3≦a≦0.5 0.01≦b≦0.3 the reflection coefficient of the first level being in the range from 10% to 30%, the transmission coefficient being at least 45%, the writing power being lower than 23 mW and the erasing power being lower than 10 mW.http://www.google.com/patents/US6746746?dq=6,163,776
Gentaur Molecular :Biotium \ DI 8 ANEPPS \ 61012
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KAKEN - Research Projects | Molecular Mechanism and its Clinical Significance of Abnormalities in Voltage-Sensitive Calcium...
Principal Investigator：KASHIWAGI Atsunori, Project Period (FY)：1989 - 1990, Research Category：Grant-in-Aid for General Scientific Research (C), Research Field：内科学一般https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01570357/
Clcnka MGI Mouse Gene Detail - MGI:1329026 - chloride channel, voltage-sensitive Ka
View mouse Clcnka Chr4:141384610-141398724 with: phenotypes, sequences, polymorphisms, proteins, references, function, expressionhttp://www.informatics.jax.org/marker/MGI:1329026
A bipolar low-voltage quarter-square multiplier with a resistive-input based on the bias offset technique - IEEE Journals &...
A bipolar low-voltage quarter-square multiplier is presented. The proposed multiplier is very simple because the multiplier cell is built from four identichttp://ieeexplore.ieee.org/document/551920/?reload=true&arnumber=551920&contentType=Journals+%26+Magazines
Patent US4095163 - Transient voltage suppression circuit - Google Patents
Circuit for reducing voltage oscillations created by transient pulses in the supply circuit in which a voltage-sensitive breakdown device is placed in series with the capacitor of an inductor-capacitor low pass filter. The breakdown device, having a finite threshold, provides a discontinuity in conduction during the noise pulse excursions to thereby damp any resulting oscillations.http://www.google.ca/patents/US4095163
Smarter, friendlier deal - CNET
Smart and Friendly strikes a deal with Macromedia to bundle its optical recording devices with Macromedia's Web publishing and graphic design tools so that Webmasters can back up sites.https://www.cnet.com/au/news/smarter-friendlier-deal/
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