WorldWideScience

Sample records for action potential imaging

  1. Action Principle for Potential Flows

    CERN Document Server

    Frønsdal, Christian

    2014-01-01

    The restriction of hydrodynamics to non-viscous, potential (gradient, irrotational) flows is a theory both simple and elegant; a favorite topic of introductory textbooks. It is known that this theory (under the stated limitations) can be formulated as an action principle. It finds its principle application to adiabatic systems and cannot account for viscosity or dissipation. However, it can be generalized to include non-potential flows, as this paper shows. The new theory is a combination of Eulerian and Lagrangian hydrodynamics, with an extension to thermodynamics. It describes adiabatic phenomena but does not account for viscosity or dissipation. Nevertheless, it is an approach within which quasi-static processes can be described. In the adiabatic context it appears to be an improvement of the Navier-Stokes equation, the principal advantage being a natural concept of energy in the form of a first integral of the motion, conserved by virtue of the Euler-Lagrange equations.

  2. Light-triggered action potentials in plants

    OpenAIRE

    Kazimierz Trębacz

    2014-01-01

    Special attention is paid in this paper to the criteria of the light-triggered action potential, namely the all-or-none law, propagation, the occurrence of refractory periods. Such action potentials have been recorded in Acetabularia mediterranea, Asplenium trichomanes, Bryum pseudotriquetrum, Eremosphaera viridis and Concephalum conicum. In Acetabularia, action potentials are generated after sudden cessation of light stimuli of sufficient intensity. The depolarization phase of the action pot...

  3. Abstract Action Potential Models for Toxin Recognition

    OpenAIRE

    Peterson, James; Khan, Taufiquar

    2005-01-01

    In this paper, we present a robust methodology using mathematical pattern recognition schemes to detect and classify events in action potentials for recognizing toxins in biological cells. We focus on event detection in action potential via abstraction of information content into a low dimensional feature vector within the constrained computational environment of a biosensor. We use generated families of action potentials from a classic Hodgkin–Huxley model to verify our methodology and build...

  4. Correlation of action potentials in adjacent neurons

    CERN Document Server

    Shneider, M N

    2015-01-01

    A possible mechanism for the synchronization of action potential propagation along a bundle of neurons (ephaptic coupling) is considered. It is shown that this mechanism is similar to the salutatory conduction of the action potential between the nodes of Ranvier in myelinated axons. The proposed model allows us to estimate the scale of the correlation, i.e., the distance between neurons in the nervous tissue, wherein their synchronization becomes possible. The possibility for experimental verification of the proposed model of synchronization is discussed.

  5. Imager displays free fall in stop action

    Science.gov (United States)

    Frazer, R. E.

    1981-01-01

    Microprocessor-controlled imaging system displays sequence of "frozen" images of free-falling object, using video cameras positioned along fall. Strobe lights flash as object passes each camera's viewfield. Sequence stored on video disk and displayed on television monitor is stop-action record of fall dynamics. With modification, system monitiors other high speed phenomena.

  6. Screening action potentials: The power of light

    Directory of Open Access Journals (Sweden)

    Lars eKaestner

    2011-07-01

    Full Text Available Action potentials reflect the concerted activity of all electrogenic constituents in the plasma membrane during the excitation of a cell. Therefore, the action potential is an integrated readout and a promising parameter to detect electrophysiological failures or modifications thereof in diagnosis as well as in drug screens. Cellular action potentials can be recorded by optical approaches. To fulfill the pre-requirements to scale up for e.g. pharmacological screens the following preparatory work has to be provided: (i model cells under investigation need to represent target cells in the best possible manner; (ii optical sensors that can be either small molecule dyes or genetically encoded potential probes need to provide a reliable readout with minimal interaction with the naive behavior of the cells and (iii devices need to be capable to stimulate the cells, read out the signals with the appropriate speed as well as provide the capacity for a sufficient throughput. Here we discuss several scenarios for all three categories in the field of cardiac physiology and pharmacology and provide a perspective to use the power of light in screening cardiac action potentials.

  7. Introducing the Action Potential to Psychology Students

    Science.gov (United States)

    Simon-Dack, Stephanie L.

    2014-01-01

    For this simple active learning technique for teaching, students are assigned "roles" and act out the process of the action potential (AP), including the firing threshold, ion-specific channels for ions to enter and leave the cell, diffusion, and the refractory period. Pre-post test results indicated that students demonstrated increased…

  8. expression, physiological actions and therapeutic potential

    OpenAIRE

    Steckelings, Ulrike

    2012-01-01

    Angiotensin II mediates its action via 2 receptor subtypes: the AT1- and AT2-receptor. The existence of more than one receptor for angiotensin II has been discovered not earlier than 1989. This "Habilitationsschrift" is based on six publications which represent mosaic stones within the growing picture of AT2-receptor expression, regulation of expression, physiological and patho-physiological function as well as potential therapeutic use. The first part is dealing with tissue specific ex...

  9. The Potential of Deweyan-Inspired Action Research

    OpenAIRE

    Stark, Jody L.

    2014-01-01

    In its broadest sense, pragmatism could be said to be the philosophical orientation of all action research. Action research is characterized by research, action, and participation grounded in democratic principles and guided by the aim of social improvement. Furthermore, action research is an active process of inquiry that does not admit separation between action and reflection or theory and practice. This paper considers the potential of action research informed specifically by Deweyan pragm...

  10. Warm body temperature facilitates energy efficient cortical action potentials.

    Directory of Open Access Journals (Sweden)

    Yuguo Yu

    Full Text Available The energy efficiency of neural signal transmission is important not only as a limiting factor in brain architecture, but it also influences the interpretation of functional brain imaging signals. Action potential generation in mammalian, versus invertebrate, axons is remarkably energy efficient. Here we demonstrate that this increase in energy efficiency is due largely to a warmer body temperature. Increases in temperature result in an exponential increase in energy efficiency for single action potentials by increasing the rate of Na(+ channel inactivation, resulting in a marked reduction in overlap of the inward Na(+, and outward K(+, currents and a shortening of action potential duration. This increase in single spike efficiency is, however, counterbalanced by a temperature-dependent decrease in the amplitude and duration of the spike afterhyperpolarization, resulting in a nonlinear increase in the spike firing rate, particularly at temperatures above approximately 35°C. Interestingly, the total energy cost, as measured by the multiplication of total Na(+ entry per spike and average firing rate in response to a constant input, reaches a global minimum between 37-42°C. Our results indicate that increases in temperature result in an unexpected increase in energy efficiency, especially near normal body temperature, thus allowing the brain to utilize an energy efficient neural code.

  11. Action potential broadening in a presynaptic channelopathy

    Science.gov (United States)

    Begum, Rahima; Bakiri, Yamina; Volynski, Kirill E.; Kullmann, Dimitri M.

    2016-07-01

    Brain development and interictal function are unaffected in many paroxysmal neurological channelopathies, possibly explained by homoeostatic plasticity of synaptic transmission. Episodic ataxia type 1 is caused by missense mutations of the potassium channel Kv1.1, which is abundantly expressed in the terminals of cerebellar basket cells. Presynaptic action potentials of small inhibitory terminals have not been characterized, and it is not known whether developmental plasticity compensates for the effects of Kv1.1 dysfunction. Here we use visually targeted patch-clamp recordings from basket cell terminals of mice harbouring an ataxia-associated mutation and their wild-type littermates. Presynaptic spikes are followed by a pronounced afterdepolarization, and are broadened by pharmacological blockade of Kv1.1 or by a dominant ataxia-associated mutation. Somatic recordings fail to detect such changes. Spike broadening leads to increased Ca2+ influx and GABA release, and decreased spontaneous Purkinje cell firing. We find no evidence for developmental compensation for inherited Kv1.1 dysfunction.

  12. Teachers in Action Research: Assumptions and Potentials

    Science.gov (United States)

    Li, Yuen-Ling

    2008-01-01

    Research literature has long indicated that action research may stimulate practitioners themselves to actively evaluate the quality of their practice. This study is designed to report the use of action research for the development of early years professional practice by analyzing the pre-project and the post-project video-filmed teaching events.…

  13. Action potential initiation in the hodgkin-huxley model.

    OpenAIRE

    Colwell, Lucy J; Brenner, Michael P.

    2009-01-01

    A recent paper of B. Naundorf et al. described an intriguing negative correlation between variability of the onset potential at which an action potential occurs (the onset span) and the rapidity of action potential initiation (the onset rapidity). This correlation was demonstrated in numerical simulations of the Hodgkin-Huxley model. Due to this antagonism, it is argued that Hodgkin-Huxley-type models are unable to explain action potential initiation observed in cortical neurons in vivo or in...

  14. Spectral action, Weyl anomaly and the Higgs-Dilaton potential

    OpenAIRE

    Andrianov, A.A.(V.A. Fock Department of Theoretical Physics, Saint-Petersburg State University, 1 ul. Ulyanovskaya, St. Petersburg, 198504, Russia); Kurkov, M.A.; Lizzi, Fedele

    2011-01-01

    We show how the bosonic spectral action emerges from the fermionic action by the renormalization group flow in the presence of a dilaton and the Weyl anomaly. The induced action comes out to be basically the Chamseddine-Connes spectral action introduced in the context of noncommutative geometry. The entire spectral action describes gauge and Higgs fields coupled with gravity. We then consider the effective potential and show, that it has the desired features of a broken and an unbroken phase,...

  15. Action potentials reliably invade axonal arbors of rat neocortical neurons

    OpenAIRE

    Cox, Charles L.; Denk, Winfried; Tank, David W.; Svoboda, Karel

    2000-01-01

    Neocortical pyramidal neurons have extensive axonal arborizations that make thousands of synapses. Action potentials can invade these arbors and cause calcium influx that is required for neurotransmitter release and excitation of postsynaptic targets. Thus, the regulation of action potential invasion in axonal branches might shape the spread of excitation in cortical neural networks. To measure the reliability and extent of action potential invasion into axonal arbors, we have used two-photon...

  16. Conduction velocity of antigravity muscle action potentials.

    Science.gov (United States)

    Christova, L; Kosarov, D; Christova, P

    1992-01-01

    The conduction velocity of the impulses along the muscle fibers is one of the parameters of the extraterritorial potentials of the motor units allowing for the evaluation of the functional state of the muscles. There are no data about the conduction velocities of antigravity muscleaction potentials. In this paper we offer a method for measuring conduction velocity of potentials of single MUs and the averaged potentials of the interference electromiogram (IEMG) lead-off by surface electrodes from mm. sternocleidomastoideus, trapezius, deltoideus (caput laterale) and vastus medialis. The measured mean values of the conduction velocity of antigravity muscles potentials can be used for testing the functional state of the muscles.

  17. [Individualised medicine - potentials and need for action].

    Science.gov (United States)

    Hüsing, Bärbel

    2010-01-01

    Individualised medicine aims to classify seemingly homogenous patient groups into smaller clinically relevant subgroups (stratification) in order to be able to treat them differently, thus contributing to the improvement of health care services, to the prevention of inappropriate treatments and to the reduction of adverse effects. This article summarises a report to the Office of Technology Assessment at the German Bundestag and points out the need for action for transferring individualised medicine from research to clinical application: significant incentives are required in order to prove the clinical validity of newly identified biomarkers of complex diseases. Sustainable business models for the joint development of new applications by research institutions, biotechnology companies, pharmaceuticals and medical devices companies are required. Instruments for transferring knowledge from bench to bedside (translational research) and the existing regulatory framework should be further developed in order to strike an appropriate balance between incentives for accelerating the transfer of innovative technology to the health care sector while, at the same time, ensuring patient safety, high quality and clinical utility. PMID:21147435

  18. Angle-action estimation in a general axisymmetric potential

    OpenAIRE

    Sanders, Jason

    2012-01-01

    The usefulness of angle-action variables in galaxy dynamics is well known, but their use is limited due to the difficulty of their calculation in realistic galaxy potentials. Here we present a method for estimating angle-action variables in a realistic Milky Way axisymmetric potential by locally fitting a St\\"ackel potential over the region an orbit probes. The quality of the method is assessed by comparison with other known methods for estimating angle-action variables of a range of disc and...

  19. Radial propagation of muscle action potential along the tubular system examined by potential-sensitive dyes

    OpenAIRE

    Nakajima, S.; Gilai, A.

    1980-01-01

    Isolated single (Xenopus) muscle fibers were stained with a non-permeant potential-probing dye, merocyanine rhodanine (WW375) or merocyanine oxazolone (NK2367). When the fiber was massively stimulated, an absorption change (wave a), which seemed to reflect the action potential, occurred. Simultaneous recording of optical changes and intracellular action potentials revealed that the time-course of wave a was slower than the action potential: the peak of wave a was attained at 1 ms, and the pea...

  20. Critical Utopian Action Research: The Potential of Action Research in the Democratization of Society

    DEFF Research Database (Denmark)

    Nielsen, Birger Steen; Nielsen, Kurt Aagaard

    2016-01-01

    The specific concept of critical utopian action research is presented and discussed, as to its origin, use and potentials. The inspiration from Robert Jungk and his future creating workshops is elaborated....

  1. Foundation ActionScript 30 Image Effects

    CERN Document Server

    Yard, Todd

    2009-01-01

    Flash has always been a tool for delivering compelling and unique experiences through dynamic visual presentation. The Flash platform has grown to include application development in Flex, video streaming with the Flash Media Server, and desktop delivery through AIR, but all of that content still comes down to pixels on the screen, and all of those pixels can be manipulated through the power of the ActionScript language. In this book, you will find in-depth coverage of the graphics capabilities of ActionScript 3.0: the enhanced drawing API in Flash Player 10 that allows you to draw vector shape

  2. Role of Sodium Channel on Cardiac Action Potential

    Directory of Open Access Journals (Sweden)

    S. H. Sabzpoushan

    2012-06-01

    Full Text Available Sudden cardiac death is a major cause of death worldwide. In most cases, it's caused by abnormal action potential propagation that leads to cardiac arrhythmia. The aim of this article is to study the abnormal action potential propagation through sodium ion concentration variations. We use a new electrophysiological model that is both detailed and computationally efficient. This efficient model is based on the partial differential equation method. The central finite difference method is used for numerical solving of the two-dimensional (2D wave propagation equation. Simulations are implemented in two stages, as a single cardiac cell and as a two-dimensional grid of cells. In both stages, the normal action potential formation in case of a single cell and it's normal propagation in case of a two-dimensional grid of cells were simulated with nominal sodium ion conductance. Then, the effect of sodium ion concentration on the action potential signal was studied by reducing the sodium ion conductance. It is concluded that reducing the sodium ion conductance, decreases both passing ability and conduction velocity of the action potential wave front.

  3. Membrane, action, and oscillatory potentials in simulated protocells

    Science.gov (United States)

    Przybylski, Aleksander T.; Stratten, Wilford P.; Syren, Robert M.; Fox, Sidney W.

    1982-12-01

    Electrical membrane potentials, oscillations, and action potentials are observed in proteinoid microspheres impaled with (3 M KCl) microelectrodes. Although effects are of greater magnitude when the vesicles contain glycerol and natural or synthetic lecithin, the results in the purely synthetic thermal protein structures are substantial, attaining 20 mV amplitude in some cases. The results add the property of electrical potential to the other known properties of proteinoid microspheres, in their role as models for protocells.

  4. Membrane, action, and oscillatory potentials in simulated protocells

    Science.gov (United States)

    Syren, R. M.; Fox, S. W.; Przybylski, A. T.; Stratten, W. P.

    1982-01-01

    Electrical membrane potentials, oscillations, and action potentials are observed in proteinoid microspheres impaled with (3 M KCl) microelectrodes. Although effects are of greater magnitude when the vesicles contain glycerol and natural or synthetic lecithin, the results in the purely synthetic thermal protein structures are substantial, attaining 20 mV amplitude in some cases. The results add the property of electrical potential to the other known properties of proteinoid microspheres, in their role as models for protocells.

  5. Theophylline-induced potentiation of the antinociceptive action of baclofen.

    OpenAIRE

    Sawynok, J

    1983-01-01

    1--Theophylline (35, 50 mg/kg) potentiated the antinociceptive action of intraperitoneally administered baclofen in the tail flick and hot plate tests. Potentiation was most marked when the pretreatment time was 1 h, but some potentiation was still apparent following a 2 h pretreatment. 2--Theophylline alone (50 mg/kg) produced only slight alterations in reaction latency in the two tests. 3--When baclofen was applied directly into the spinal subarachnoid space, a 1 h pretreatment with theophy...

  6. Action prediction based on anticipatory brain potentials during simulated driving

    Science.gov (United States)

    Khaliliardali, Zahra; Chavarriaga, Ricardo; Gheorghe, Lucian Andrei; Millán, José del R.

    2015-12-01

    Objective. The ability of an automobile to infer the driver’s upcoming actions directly from neural signals could enrich the interaction of the car with its driver. Intelligent vehicles fitted with an on-board brain-computer interface able to decode the driver’s intentions can use this information to improve the driving experience. In this study we investigate the neural signatures of anticipation of specific actions, namely braking and accelerating. Approach. We investigated anticipatory slow cortical potentials in electroencephalogram recorded from 18 healthy participants in a driving simulator using a variant of the contingent negative variation (CNV) paradigm with Go and No-go conditions: count-down numbers followed by ‘Start’/‘Stop’ cue. We report decoding performance before the action onset using a quadratic discriminant analysis classifier based on temporal features. Main results. (i) Despite the visual and driving related cognitive distractions, we show the presence of anticipatory event related potentials locked to the stimuli onset similar to the widely reported CNV signal (with an average peak value of -8 μV at electrode Cz). (ii) We demonstrate the discrimination between cases requiring to perform an action upon imperative subsequent stimulus (Go condition, e.g. a ‘Red’ traffic light) versus events that do not require such action (No-go condition; e.g. a ‘Yellow’ light); with an average single trial classification performance of 0.83 ± 0.13 for braking and 0.79 ± 0.12 for accelerating (area under the curve). (iii) We show that the centro-medial anticipatory potentials are observed as early as 320 ± 200 ms before the action with a detection rate of 0.77 ± 0.12 in offline analysis. Significance. We show for the first time the feasibility of predicting the driver’s intention through decoding anticipatory related potentials during simulated car driving with high recognition rates.

  7. Propagation of Action Potentials: An Active Participation Exercise.

    Science.gov (United States)

    Felsten, Gary

    1998-01-01

    Describes an active participation exercise that demonstrates the propagation of action potentials (the ability to transmit information through the neural network, dependent upon chemical interactions in the brain). Students assume the structure and function of the network by lining up around the room and communicating through hand signals and…

  8. Uncertainty propagation in nerve impulses through the action potential mechanism

    NARCIS (Netherlands)

    Torres Valderrama, A.; Witteveen, J.A.S.; Navarro Jimenez, M.I.; Blom, J.G.

    2015-01-01

    We investigate the propagation of probabilistic uncertainty through the action potential mechanism in nerve cells. Using the Hodgkin-Huxley (H-H) model and Stochastic Collocation on Sparse Grids, we obtain an accurate probabilistic interpretation of the deterministic dynamics of the transmembrane po

  9. Compound muscle action potentials in newborn infants with spina bifida.

    NARCIS (Netherlands)

    Geerdink, N.; Pasman, J.W.; Rotteveel, J.J.; Roeleveld, N.; Mullaart, R.A.

    2008-01-01

    The aim of this study was to investigate the relationship between compound muscle action potentials (CMAPs) and neurological impairment in newborn infants with spina bifida. Thirty-one newborn infants (17 males, 14 females, mean gestational age 39 wks [SD 2]; mean birthweight 3336 g [SD 496]) with s

  10. Sodium and potassium conductance changes during a membrane action potential.

    Science.gov (United States)

    Bezanilla, F; Rojas, E; Taylor, R E

    1970-12-01

    1. A method for turning a membrane potential control system on and off in less than 10 musec is described. This method was used to record membrane currents in perfused giant axons from Dosidicus gigas and Loligo forbesi after turning on the voltage clamp system at various times during the course of a membrane action potential.2. The membrane current measured just after the capacity charging transient was found to have an almost linear relation to the controlled membrane potential.3. The total membrane conductance taken from these current-voltage curves was found to have a time course during the action potential similar to that found by Cole & Curtis (1939).4. The instantaneous current voltage curves were linear enough to make it possible to obtain a good estimate of the individual sodium and potassium channel conductances, either algebraically or by clamping to the sodium, or potassium, reversal potentials. Good general agreement was obtained with the predictions of the Hodgkin-Huxley equations.5. We consider these results to constitute the first direct experimental demonstration of the conductance changes to sodium and potassium during the course of an action potential. PMID:5505231

  11. Action potential initiation in the hodgkin-huxley model.

    Directory of Open Access Journals (Sweden)

    Lucy J Colwell

    2009-01-01

    Full Text Available A recent paper of B. Naundorf et al. described an intriguing negative correlation between variability of the onset potential at which an action potential occurs (the onset span and the rapidity of action potential initiation (the onset rapidity. This correlation was demonstrated in numerical simulations of the Hodgkin-Huxley model. Due to this antagonism, it is argued that Hodgkin-Huxley-type models are unable to explain action potential initiation observed in cortical neurons in vivo or in vitro. Here we apply a method from theoretical physics to derive an analytical characterization of this problem. We analytically compute the probability distribution of onset potentials and analytically derive the inverse relationship between onset span and onset rapidity. We find that the relationship between onset span and onset rapidity depends on the level of synaptic background activity. Hence we are able to elucidate the regions of parameter space for which the Hodgkin-Huxley model is able to accurately describe the behavior of this system.

  12. Compound sensory action potential in normal and pathological human nerves

    DEFF Research Database (Denmark)

    Krarup, Christian

    2004-01-01

    The compound sensory nerve action potential (SNAP) is the result of phase summation and cancellation of single fiber potentials (SFAPs) with amplitudes that depend on fiber diameter, and the amplitude and shape of the SNAP is determined by the distribution of fiber diameters. Conduction velocities...... at different conduction distances are determined by summation of SFAPs of varying fiber diameters, and differ in this respect, also, from the compound muscle action potential (CMAP) for which conduction velocities are determined by the very fastest fibers in the nerve. The effect and extent of temporal......, with fiber loss or increased conduction velocity variability changes of the SNAP may be smaller than expected from normal nerve. The biophysical characteristics of sensory and motor fibers differ, and this may to some extent determine divergent pathophysiological changes in sensory and motor fibers...

  13. Imaging membrane potential in dendritic spines

    OpenAIRE

    Nuriya, Mutsuo; Jiang, Jiang; Nemet, Boaz; Eisenthal, Kenneth B.; Yuste, Rafael

    2006-01-01

    Dendritic spines mediate most excitatory inputs in the brain. Although it is clear that spines compartmentalize calcium, it is still unknown what role, if any, they play in integrating synaptic inputs. To investigate the electrical function of spines directly, we used second harmonic generation (SHG) imaging of membrane potential in pyramidal neurons from hippocampal cultures and neocortical brain slices. With FM 4-64 as an intracellular SHG chromophore, we imaged membrane potential in the so...

  14. Generalized Row-Action Methods for Tomographic Imaging

    DEFF Research Database (Denmark)

    Andersen, Martin Skovgaard; Hansen, Per Christian

    2014-01-01

    Row-action methods play an important role in tomographic image reconstruction. Many such methods can be viewed as incremental gradient methods for minimizing a sum of a large number of convex functions, and despite their relatively poor global rate of convergence, these methods often exhibit fast...... initial convergence which is desirable in applications where a low-accuracy solution is acceptable. In this paper, we propose relaxed variants of a class of incremental proximal gradient methods, and these variants generalize many existing row-action methods for tomographic imaging. Moreover, they allow...... us to derive new incremental algorithms for tomographic imaging that incorporate different types of prior information via regularization. We demonstrate the efficacy of the approach with some numerical examples....

  15. Implementing participatory action research in Lithuania: potential and challenges

    Directory of Open Access Journals (Sweden)

    Gabija Jarašiūnaitė

    2015-12-01

    Full Text Available Participatory action research is a quite new approach to research in Lithuania. The aim of an article was to disscuss the potential and challenges of participatory action research while implementing it in Lithuanian organizations. The qualitative approach was chosen for the study using the method of Focus groups. 20 researchers from social and biomedicine sciences from six institutions of High education in Lithuania participated in the study. The results of the study showed that participatory action reasearch is seen as an approach with many possibilities because of a wide range of used methods, constant interactions with research participants and the lenght of the research process. Researchers value the possibility to access organization at the begining, during research process and evaluate the effectiveness of the changes after the process. The research challenges are associated with the competence of a researcher including his/her sensitivity during process, ability to involve active participation of organization members in the ongoing process by creating safe and trusting environment. Some specific challenges associated with Lithuanian organizations are organizations‘ tiredness of researches and lack of faith of the benefits of researches because of some previous experiences. Keywords: Participatory Action Research, Organization, Lithuania.

  16. Depth-Resolved Measurement of Transient Structural Changes during Action Potential Propagation

    OpenAIRE

    Akkin, T.; Joo, C.; Boer

    2007-01-01

    We report noncontact optical measurement of fast transient structural changes in the crustacean nerve during action potential propagation without the need for exogenous chemicals or reflection coatings. The technique, spectral domain optical coherence tomography, provides real-time cross-sectional images of the nerve with micron-scale resolution to select a specific region for functional assessment and interferometric phase sensitivity for subnanometer-scale motion detection. Noncontact optic...

  17. Flexible graphene transistors for recording cell action potentials

    Science.gov (United States)

    Blaschke, Benno M.; Lottner, Martin; Drieschner, Simon; Bonaccini Calia, Andrea; Stoiber, Karolina; Rousseau, Lionel; Lissourges, Gaëlle; Garrido, Jose A.

    2016-06-01

    Graphene solution-gated field-effect transistors (SGFETs) are a promising platform for the recording of cell action potentials due to the intrinsic high signal amplification of graphene transistors. In addition, graphene technology fulfills important key requirements for in-vivo applications, such as biocompability, mechanical flexibility, as well as ease of high density integration. In this paper we demonstrate the fabrication of flexible arrays of graphene SGFETs on polyimide, a biocompatible polymeric substrate. We investigate the transistor’s transconductance and intrinsic electronic noise which are key parameters for the device sensitivity, confirming that the obtained values are comparable to those of rigid graphene SGFETs. Furthermore, we show that the devices do not degrade during repeated bending and the transconductance, governed by the electronic properties of graphene, is unaffected by bending. After cell culture, we demonstrate the recording of cell action potentials from cardiomyocyte-like cells with a high signal-to-noise ratio that is higher or comparable to competing state of the art technologies. Our results highlight the great capabilities of flexible graphene SGFETs in bioelectronics, providing a solid foundation for in-vivo experiments and, eventually, for graphene-based neuroprosthetics.

  18. The Potential of Deweyan-Inspired Action Research

    Science.gov (United States)

    Stark, Jody L.

    2014-01-01

    In its broadest sense, pragmatism could be said to be the philosophical orientation of all action research. Action research is characterized by research, action, and participation grounded in democratic principles and guided by the aim of social improvement. Furthermore, action research is an active process of inquiry that does not admit…

  19. Pressure wave model for action potential propagation in excitable cells

    CERN Document Server

    Rvachev, M M

    2003-01-01

    Speed of propagation of small-amplitude pressure waves through the cytoplasmic interior of myelinated and unmyelinated axons of different diameters is theoretically estimated and is found to generally agree with the action potential (AP) conduction velocities. This remarkable coincidence allows to surmise a model in which AP spread along axon is propelled not by straggling ionic currents as in the widely accepted local circuit theory, but by mechanoactivation of the membrane ion channels by a traveling pressure pulse. Hydraulic pulses propagating in the viscous axoplasm are calculated to decay over ~1 mm distances, and it is further hypothesized that it is the role of influxing during the AP calcium ions to activate membrane skeletal protein network attached to the membrane cytoplasmic side for a brief radial contraction amplifying the pressure pulse and preventing its decay. The model correctly predicts that the AP conduction velocity should vary as the one-half power of axon diameter for large unmyelinated ...

  20. Compound sensory action potential in normal and pathological human nerves

    DEFF Research Database (Denmark)

    Krarup, Christian

    2004-01-01

    at different conduction distances are determined by summation of SFAPs of varying fiber diameters, and differ in this respect, also, from the compound muscle action potential (CMAP) for which conduction velocities are determined by the very fastest fibers in the nerve. The effect and extent of temporal...... dispersion over increasing conduction distance is greater for the SNAP than CMAP, and demonstration of conduction block is therefore difficult. In addition, the effect of temporal dispersion on amplitude and shape is strongly dependent on the number of conducting fibers and their distribution, and...... in different polyneuropathies. In this review, different factors that characterize sensory fibers and set the SNAP apart from the CMAP are discussed to emphasize the supplementary and complementary information that can be obtained from sensory conduction studies. Sensory conduction studies require particular...

  1. Modelling Action Potential Generation and Propagation in Fibroblastic Cells

    Science.gov (United States)

    Torres, J. J.; Cornelisse, L. N.; Harks, E. G. A.; Theuvenet, A. P. R.; Ypey, D. L.

    2003-04-01

    Using a standard Hodgkin-Huxley (HH) formalism, we present a mathematical model for action potential (AP) generation and intercellular AP propagation in quiescent (serum-deprived) normal rat kidney (NRK) fibroblasts [1], based on the recent experimental identification of the ion channels involved [2]. The principal ion channels described are those of an inwardly rectifying K+ conductance (GKIR), an L-type calcium conductance (GCaL), an intracellular calcium activated Cl- conductance (GCl(Ca)), a residual leak conductance Gleak, and gap junctional channels between the cells (Ggj). The role of each one of these components in the particular shape of the AP wave-form has been analyzed and compared with experimental observations. In addition, we have studied the role of subcellular processes like intracellular calcium dynamics and calcium buffering in AP generation. AP propagation between cells was reconstructed in a hexagonal model of cells coupled by Ggj with physiological conductance values. The model revealed an excitability mechanism of quiescent NRK cells with a particular role of intracellular calcium dynamics. It allows further explorations of the mechanism of signal generation and transmission in NRK cell cultures and its dependence on growth conditions.

  2. Pharmacological actions of statins: potential utility in COPD

    Directory of Open Access Journals (Sweden)

    T. E. Eaton

    2009-12-01

    Full Text Available Chronic obstructive pulmonary disease (COPD is characterised by minimally reversible airflow limitation and features of systemic inflammation. Current therapies for COPD have been shown to reduce symptoms and infective exacerbations and to improve quality of life. However, these drugs have little effect on the natural history of the disease (progressive decline in lung function and exercise tolerance and do not improve mortality. The anti-inflammatory effects of statins on both pulmonary and systemic inflammation through inhibition of guanosine triphosphatase and nuclear factor-B mediated activation of inflammatory and matrix remodelling pathways could have substantial benefits in patients with COPD due to the following. 1 Inhibition of cytokine production (tumour necrosis factor-, interleukin (IL-6 and IL-8 and neutrophil infiltration into the lung; 2 inhibition of the fibrotic activity in the lung leading to small airways fibrosis and irreversible airflow limitation; 3 antioxidant and anti-inflammatory (IL-6 mediated effects on skeletal muscle; 4 reduced inflammatory response to pulmonary infection; and 5 inhibition of the development (or reversal of epithelial-mesenchymal transition, a precursor event to lung cancer. This review examines the pleiotropic pharmacological action of statins which inhibit key inflammatory and remodelling pathways in COPD and concludes that statins have considerable potential as adjunct therapy in COPD.

  3. Pharmacological actions of statins: potential utility in COPD.

    Science.gov (United States)

    Young, R P; Hopkins, R; Eaton, T E

    2009-12-01

    Chronic obstructive pulmonary disease (COPD) is characterised by minimally reversible airflow limitation and features of systemic inflammation. Current therapies for COPD have been shown to reduce symptoms and infective exacerbations and to improve quality of life. However, these drugs have little effect on the natural history of the disease (progressive decline in lung function and exercise tolerance) and do not improve mortality. The anti-inflammatory effects of statins on both pulmonary and systemic inflammation through inhibition of guanosine triphosphatase and nuclear factor-κB mediated activation of inflammatory and matrix remodelling pathways could have substantial benefits in patients with COPD due to the following. 1) Inhibition of cytokine production (tumour necrosis factor-α, interleukin (IL)-6 and IL-8) and neutrophil infiltration into the lung; 2) inhibition of the fibrotic activity in the lung leading to small airways fibrosis and irreversible airflow limitation; 3) antioxidant and anti-inflammatory (IL-6 mediated) effects on skeletal muscle; 4) reduced inflammatory response to pulmonary infection; and 5) inhibition of the development (or reversal) of epithelial-mesenchymal transition, a precursor event to lung cancer. This review examines the pleiotropic pharmacological action of statins which inhibit key inflammatory and remodelling pathways in COPD and concludes that statins have considerable potential as adjunct therapy in COPD. PMID:20956147

  4. Acute nerve stretch and the compound motor action potential

    Directory of Open Access Journals (Sweden)

    Wolfe Jacob

    2011-08-01

    Full Text Available Abstract In this paper, the acute changes in the compound motor action potential (CMAP during mechanical stretch were studied in hamster sciatic nerve and compared to the changes that occur during compression. In response to stretch, the nerve physically broke when a mean force of 331 gm (3.3 N was applied while the CMAP disappeared at an average stretch force of 73 gm (0.73 N. There were 5 primary measures of the CMAP used to describe the changes during the experiment: the normalized peak to peak amplitude, the normalized area under the curve (AUC, the normalized duration, the normalized velocity and the normalized velocity corrected for the additional path length the impulses travel when the nerve is stretched. Each of these measures was shown to contain information not available in the others. During stretch, the earliest change is a reduction in conduction velocity followed at higher stretch forces by declines in the amplitude of the CMAP. This is associated with the appearance of spontaneous EMG activity. With stretch forces Multiple means of predicting when a change in the CMAP suggests a significant stretch are discussed and it is clear that a multifactorial approach using both velocity and amplitude parameters is important. In the case of pure compression, it is only the amplitude of the CMAP that is critical in predicting which changes in the CMAP are associated with significant compression.

  5. Short latency compound action potentials from mammalian gravity receptor organs

    Science.gov (United States)

    Jones, T. A.; Jones, S. M.

    1999-01-01

    Gravity receptor function was characterized in four mammalian species using far-field vestibular evoked potentials (VsEPs). VsEPs are compound action potentials of the vestibular nerve and central relays that are elicited by linear acceleration ramps applied to the cranium. Rats, mice, guinea pigs, and gerbils were studied. In all species, response onset occurred within 1.5 ms of the stimulus onset. Responses persisted during intense (116 dBSPL) wide-band (50 to 50 inverted question mark omitted inverted question mark000 Hz) forward masking, whereas auditory responses to intense clicks (112 dBpeSPL) were eliminated under the same conditions. VsEPs remained after cochlear extirpation but were eliminated following bilateral labyrinthectomy. Responses included a series of positive and negative peaks that occurred within 8 ms of stimulus onset (range of means at +6 dBre: 1.0 g/ms: P1=908 to 1062 micros, N1=1342 to 1475 micros, P2=1632 to 1952 micros, N2=2038 to 2387 micros). Mean response amplitudes at +6 dBre: 1.0 g/ms ranged from 0.14 to 0.99 microV. VsEP input/output functions revealed latency slopes that varied across peaks and species ranging from -19 to -51 micros/dB. Amplitude-intensity slopes also varied ranging from 0.04 to 0.08 microV/dB for rats and mice. Latency values were comparable to those of birds although amplitudes were substantially smaller in mammals. VsEP threshold values were considerably higher in mammals compared to birds and ranged from -8.1 to -10.5 dBre 1.0 g/ms across species. These results support the hypothesis that mammalian gravity receptors are less sensitive to dynamic stimuli than are those of birds.

  6. Reconstruction-Free Action Inference from Compressive Imagers.

    Science.gov (United States)

    Kulkarni, Kuldeep; Turaga, Pavan

    2016-04-01

    Persistent surveillance from camera networks, such as at parking lots, UAVs, etc., often results in large amounts of video data, resulting in significant challenges for inference in terms of storage, communication and computation. Compressive cameras have emerged as a potential solution to deal with the data deluge issues in such applications. However, inference tasks such as action recognition require high quality features which implies reconstructing the original video data. Much work in compressive sensing (CS) theory is geared towards solving the reconstruction problem, where state-of-the-art methods are computationally intensive and provide low-quality results at high compression rates. Thus, reconstruction-free methods for inference are much desired. In this paper, we propose reconstruction-free methods for action recognition from compressive cameras at high compression ratios of 100 and above. Recognizing actions directly from CS measurements requires features which are mostly nonlinear and thus not easily applicable. This leads us to search for such properties that are preserved in compressive measurements. To this end, we propose the use of spatio-temporal smashed filters, which are compressive domain versions of pixel-domain matched filters. We conduct experiments on publicly available databases and show that one can obtain recognition rates that are comparable to the oracle method in uncompressed setup, even for high compression ratios.

  7. Dynamics of the inward rectifier K+ current during the action potential of guinea pig ventricular myocytes.

    OpenAIRE

    Ibarra, J; Morley, G E; Delmar, M

    1991-01-01

    The potassium selective, inward rectifier current (IK1) is known to be responsible for maintaining the resting membrane potential of quiescent ventricular myocytes. However, the contribution of this current to the different phases of the cardiac action potential has not been adequately established. In the present study, we have used the action potential clamp (APC) technique to characterize the dynamic changes of a cesium-sensitive (i.e., Ik1) current which occur during the action potential. ...

  8. Zodiac II: Debris Disk Imaging Potential

    Science.gov (United States)

    Traub Wesley; Bryden, Geoff; Stapelfeldt, Karl; Chen, Pin; Trauger, John

    2011-01-01

    Zodiac II is a proposed coronagraph on a balloon-borne platform, for the purpose of observing debris disks around nearby stars. Zodiac II will have a 1.2-m diameter telescope mounted in a balloon-borne gondola capable of arcsecond quality pointing, and with the capability to make long-duration (several week) flights. Zodiac II will have a coronagraph able to make images of debris disks, meaning that its scattered light speckles will be at or below an average contrast level of about 10(exp -7) in three narrow (7 percent) bands centered on the V band, and one broad (20%) one at I band. We will discuss the potential science to be done with Zodiac II.

  9. Membrane potential dynamics of axons in cultured hippocampal neurons probed by second-harmonic-generation imaging

    Science.gov (United States)

    Nuriya, Mutsuo; Yasui, Masato

    2010-03-01

    The electrical properties of axons critically influence the nature of communication between neurons. However, due to their small size, direct measurement of membrane potential dynamics in intact and complex mammalian axons has been a challenge. Furthermore, quantitative optical measurements of axonal membrane potential dynamics have not been available. To characterize the basic principles of somatic voltage signal propagation in intact axonal arbors, second-harmonic-generation (SHG) imaging is applied to cultured mouse hippocampal neurons. When FM4-64 is applied extracellularly to dissociated neurons, whole axonal arbors are visualized by SHG imaging. Upon action potential generation by somatic current injection, nonattenuating action potentials are recorded in intact axonal arbors. Interestingly, however, both current- and voltage-clamp recordings suggest that nonregenerative subthreshold somatic voltage changes at the soma are poorly conveyed to these axonal sites. These results reveal the nature of membrane potential dynamics of cultured hippocampal neurons, and further show the possibility of SHG imaging in physiological investigations of axons.

  10. Scaling of the quark-antiquark potential and improved actions in SU(2) lattice gauge theory

    International Nuclear Information System (INIS)

    The scaling behaviour of the quark-antiquark potential is investigated by a high statistics Monte Carlo calculation in SU(2) lattice gauge theory. Besides the standard one-plaquette action we also use Symanzik's tree-level improved action and Wilson's block-spin improved action. No significant differences between Symanzik's action and the standard action have been observed. For small β Wilson's action scales differently. The string tension value chi extracted from the data corresponds to Λsub(latt) = (0.018 +- 0.001) √chi for the one-plaquette action. (orig.)

  11. Circadian- and Light-Dependent Regulation of Resting Membrane Potential and Spontaneous Action Potential Firing of Drosophila Circadian Pacemaker Neurons

    OpenAIRE

    Sheeba, Vasu; Gu, Huaiyu; Sharma, Vijay K.; O'Dowd, Diane K.; Holmes, Todd C.

    2007-01-01

    The ventral lateral neurons (LNvs) of adult Drosophila brain express oscillating clock proteins and regulate circadian behavior. Whole cell current-clamp recordings of large LNvs in freshly dissected Drosophila whole brain preparations reveal two spontaneous activity patterns that correlate with two underlying patterns of oscillating membrane potential: tonic and burst firing of sodium-dependent action potentials. Resting membrane potential and spontaneous action potential firing are rapidly ...

  12. Ontogeny of vestibular compound action potentials in the domestic chicken

    Science.gov (United States)

    Jones, S. M.; Jones, T. A.

    2000-01-01

    Compound action potentials of the vestibular nerve were measured from the surface of the scalp in 148 chickens (Gallus domesticus). Ages ranged from incubation day 18 (E18) to 22 days posthatch (P22). Responses were elicited using linear acceleration cranial pulses. Response thresholds decreased at an average rate of -0.45 dB/day. The decrease was best fit by an exponential model with half-maturity time constant of 5.1 days and asymptote of approximately -25.9 dB re:1.0 g/ms. Mean threshold approached within 3 dB of the asymptote by ages P6-P9. Similarly, response latencies decreased exponentially to within 3% of mature values at ages beyond P9. The half-maturity time constant for peripheral response peak latencies P1, N1, and P2 was comparable to thresholds and ranged from approximately 4.6 to 6.2 days, whereas central peaks (N2, P3, and N3) ranged from 2.9 to 3.4 days. Latency-intensity slopes for P1, N1, and P2 tended to decrease with age, reaching mature values within approximately 100 hours of hatching. Amplitudes increased as a function of age with average growth rates for response peaks ranging from 0.04 to 0.09 microV/day. There was no obvious asymptote to the growth of amplitudes over the ages studied. Amplitude-intensity slopes also increased modestly with age. The results show that gravity receptors are responsive to transient cranial stimuli as early as E19 in the chicken embryo. The functional response of gravity receptors continues to develop for many days after all major morphological structures are in place. Distinct maturational processes can be identified in central and peripheral neural relays. Functional improvements during maturation may result from refinements in the receptor epithelia, improvements in central and peripheral synaptic transmission, increased neural myelination, as well as changes in the mechanical coupling between the cranium and receptor organ.

  13. Distribution of Action Potential Duration and T-wave Morphology: a Simulation Study

    CERN Document Server

    Ryzhii, Elena; Wei, Daming

    2009-01-01

    The results of a simulation study of the action potential duration (APD) distribution and T-wave morphology taking into account the midmyocardial cells (M-cells) concept are described. To investigate the effect of M-cells we present a computer model in which ion channel action potential formulations are incorporated into three-dimensional whole heart model. We implemented inhomogeneous continuous action potential duration distribution based on different distributions of maximal slow delayed rectifier current conductance. Using the proposed action potential distribution procedure midmural zeniths with longest action potential length were created as islands of model cells in the depth of thickest areas of ventricular tissue. Different spatial functions on layer indexes were simulated and their influences on electrocardiogram waveforms were analyzed. Changing parameters of ion channel model we varied duration of minimal and maximal action potential and investigated T-wave amplitude, Q-Tpeak and QT intervals vari...

  14. Understanding the Electrical Behavior of the Action Potential in Terms of Elementary Electrical Sources

    Science.gov (United States)

    Rodriguez-Falces, Javier

    2015-01-01

    A concept of major importance in human electrophysiology studies is the process by which activation of an excitable cell results in a rapid rise and fall of the electrical membrane potential, the so-called action potential. Hodgkin and Huxley proposed a model to explain the ionic mechanisms underlying the formation of action potentials. However,…

  15. Mathematical Distinction in Action Potential between Primo-Vessels and Smooth Muscle

    OpenAIRE

    Seong-Jin Cho; Sang-Hun Lee; Wenji Zhang; Sae-Bhom Lee; Kwang-Ho Choi; Sun-Mi Choi; Yeon-Hee Ryu

    2012-01-01

    We studied the action potential of Primo-vessels in rats to determine the electrophysiological characteristics of these structures. We introduced a mathematical analysis method, a normalized Fourier transform that displays the sine and cosine components separately, to compare the action potentials of Primo-vessels with those for the smooth muscle. We found that Primo-vessels generated two types of action potential pulses that differed from those of smooth muscle: (1) Type I pulse had rapid de...

  16. Distribution of Action Potential Duration and T-wave Morphology: a Simulation Study

    OpenAIRE

    Ryzhii, Elena; Ryzhii, Maxim; Wei, Daming

    2009-01-01

    The results of a simulation study of the action potential duration (APD) distribution and T-wave morphology taking into account the midmyocardial cells (M-cells) concept are described. To investigate the effect of M-cells we present a computer model in which ion channel action potential formulations are incorporated into three-dimensional whole heart model. We implemented inhomogeneous continuous action potential duration distribution based on different distributions of maximal slow delayed r...

  17. A Rabbit Ventricular Action Potential Model Replicating Cardiac Dynamics at Rapid Heart Rates

    OpenAIRE

    Mahajan, Aman; Shiferaw, Yohannes; Sato, Daisuke; Baher, Ali; Olcese, Riccardo; Xie, Lai-Hua; Yang, Ming-Jim; Chen, Peng-Sheng; Restrepo, Juan G.; Karma, Alain; Garfinkel, Alan; Qu, Zhilin; Weiss, James N.

    2008-01-01

    Mathematical modeling of the cardiac action potential has proven to be a powerful tool for illuminating various aspects of cardiac function, including cardiac arrhythmias. However, no currently available detailed action potential model accurately reproduces the dynamics of the cardiac action potential and intracellular calcium (Cai) cycling at rapid heart rates relevant to ventricular tachycardia and fibrillation. The aim of this study was to develop such a model. Using an existing rabbit ven...

  18. Consumer-Related Food Waste: Causes and Potential for Action

    DEFF Research Database (Denmark)

    Aschemann-Witzel, Jessica; Hooge, Ilona de; Amani, Pegah;

    2015-01-01

    interviews on factors causing consumer-related food waste in households and supply chains. Results show that consumers’ motivation to avoid food waste, their management skills of food provisioning and food handling and their trade-offs between priorities have an extensive influence on their food waste...... behaviors. We identify actions that governments, societal stakeholders and retailers can undertake to reduce consumer-related food waste, highlighting that synergistic actions between all parties are most promising. Further research should focus on exploring specific food waste contexts and interactions...

  19. Effect of a prenylamine analog (MG8926) on spontaneous action potentials in isolated rabbit sinoatrial node.

    Science.gov (United States)

    Nakanishi, H; Matsuoka, I; Ono, T; Yoshida, H; Uchibori, T; Kogi, K

    1996-12-01

    Effects of verapamil, prenylamine and a prenylamine analog, MG8926 on the intracellular spontaneous action potentials recorded from the isolated rabbit sinoatrial (SA) node were studied. Verapamil (1 microM), a selective inhibitor for slow Ca2+ channels, prolonged the cycle length, decreased the rate of diastolic depolarization, the rate of rise of action potential, the amplitude of action potential and the maximal diastolic potential, and usually arrested showing subthreshold fluctuation of the membrane potential within several ten min. Prenylamine (10 microM), a nonselective inhibitor for slow Ca2+ channels, tended to prolong the cycle length to decrease the diastolic depolarization, the rate of rise of action potential, the amplitude of action potential. However, these changes were statistically insignificant. Prenylamine at the concentration of 10 microM had no effect on the maximal diastolic potential. MG8926 (10 microM) prolonged the cycle length, decreased the rate of diastolic depolarization, the rate of rise of action potential and tended to decrease the amplitude of action potential. MG8926 at the concentration of 10 microM had almost no effect on the maximal diastolic potential. The present findings may indicate that replacement of phenyl residue of prenylamine by cyclohexyl residue increases the inhibitory action on the slow Ca2+ channels in rabbit SA node.

  20. Mechanisms of action and potential therapeutic uses of thalidomide.

    Science.gov (United States)

    Mujagić, Hamza; Chabner, Bruce A; Mujagić, Zlata

    2002-06-01

    Thalidomide was first introduced to the market in Germany under the brand name of Contergan in 1956, as a non-barbiturate hypnotic, advocated to ensure a good nights sleep and to prevent morning sickness in pregnancy. It was advertised for its prompt action, lack of hangover, and apparent safety. It has been banned from the market since 1963 after it caused the worldwide teratogenic disaster: babies exposed to thalidomide in utero during the first 34-50 days of pregnancy were born with severe life-threatening birth defects. Despite its unfortunate history, thalidomide has attracted scientific interest again because of its recently discovered action against inflammatory diseases and cancer. Its broad range of biological activities stems from its ability to moderate cytokine action in cancer and inflammatory diseases. Early studies examined its anxiolytic, mild hypnotic, antiemetic, and adjuvant analgesic properties. Subsequently, thalidomide was found to be highly effective in managing the cutaneous manifestations of leprosy, being superior to Aspirin in controlling leprosy-associated fever. Recent research has shown promising results with thalidomide in patients with myeloma, myelodysplastic syndrome, a variety of infectious diseases, autoimmune diseases, cancer, and progressive body weight loss related to advanced cancer and AIDS. Here we review the history of its development, pharmacokinetics, metabolism, biologic effects, and the results of clinical trials conducted thus far. Further research in this field should be directed towards better understanding of thalidomide metabolism, its mechanism of action, and the development of less toxic and more active analogs. PMID:12035132

  1. On the excitation of action potentials by protons and its potential implications for cholinergic transmission

    CERN Document Server

    Fillafer, Christian

    2014-01-01

    One of the most conserved mechanisms for transmission of a nerve pulse across a synapse relies on acetylcholine. Ever since the Nobel-prize winning works of Dale and Loewi, it has been assumed that acetylcholine - subsequent to its action on a postsynaptic cell - is split into inactive by-products by acetylcholinesterase. Herein, this widespread assumption is falsified. Excitable cells (Chara australis internodes), which had previously been unresponsive to acetylcholine, became acetylcholine-sensitive in presence of acetylcholinesterase. The latter was evidenced by a striking difference in cell membrane depolarisation upon exposure to 10 mM intact acetylcholine (deltaV=-2plus/minus5 mV) and its hydrolysate respectively (deltaV=81plus/minus19 mV) for 60 sec. This pronounced depolarization, which also triggered action potentials, was clearly attributed to one of the hydrolysis products: acetic acid (deltaV=87plus/minus9 mV at pH 4.0; choline ineffective in range 1-10 mM). In agreement with our findings, numerou...

  2. Potential involvement of serotonergic signaling in ketamine's antidepressant actions

    DEFF Research Database (Denmark)

    du Jardin, Kristian Gaarn; Müller, Heidi Kaastrup; Elfving, Betina;

    2016-01-01

    A single i.v. infusion of ketamine, classified as an N-methyl-D-aspartate (NMDA) receptor antagonist, may alleviate depressive symptoms within hours of administration in treatment resistant depressed patients, and the antidepressant effect may last for several weeks. These unique therapeutic...... properties have prompted researchers to explore the mechanisms mediating the antidepressant effects of ketamine, but despite many efforts, no consensus on its antidepressant mechanism of action has been reached. Recent preclinical reports have associated the neurotransmitter serotonin (5-hydroxytryptamine; 5......-HT) with the antidepressant-like action of ketamine. Here, we review the current evidence for a serotonergic role in ketamine's antidepressant effects. The pharmacological profile of ketamine may include equipotent activity on several non-NMDA targets, and the current hypotheses for the mechanisms...

  3. Making Class Actions Work: The Untapped Potential of the Internet

    Directory of Open Access Journals (Sweden)

    Robert H. Klonoff

    2008-04-01

    Full Text Available Over twenty years ago, the Supreme Court recognized that in class action litigation, absent class members “must receive notice plus an opportunity to be heard and participate in the litigation, whether in person or through counsel.” Although the absent class members’ rights to receive notice and an opportunity to opt out are of vital importance, the ability to be heard and participate in the litigation are also important.

  4. Dynamics of action potential initiation in the GABAergic thalamic reticular nucleus in vivo.

    Directory of Open Access Journals (Sweden)

    Fabián Muñoz

    Full Text Available Understanding the neural mechanisms of action potential generation is critical to establish the way neural circuits generate and coordinate activity. Accordingly, we investigated the dynamics of action potential initiation in the GABAergic thalamic reticular nucleus (TRN using in vivo intracellular recordings in cats in order to preserve anatomically-intact axo-dendritic distributions and naturally-occurring spatiotemporal patterns of synaptic activity in this structure that regulates the thalamic relay to neocortex. We found a wide operational range of voltage thresholds for action potentials, mostly due to intrinsic voltage-gated conductances and not synaptic activity driven by network oscillations. Varying levels of synchronous synaptic inputs produced fast rates of membrane potential depolarization preceding the action potential onset that were associated with lower thresholds and increased excitability, consistent with TRN neurons performing as coincidence detectors. On the other hand the presence of action potentials preceding any given spike was associated with more depolarized thresholds. The phase-plane trajectory of the action potential showed somato-dendritic propagation, but no obvious axon initial segment component, prominent in other neuronal classes and allegedly responsible for the high onset speed. Overall, our results suggest that TRN neurons could flexibly integrate synaptic inputs to discharge action potentials over wide voltage ranges, and perform as coincidence detectors and temporal integrators, supported by a dynamic action potential threshold.

  5. Analysis of toxin induced changes in action potential shape for drug development

    OpenAIRE

    Akanda, Nesar; Molnar, Peter; Stancescu, Maria; Hickman, James J.

    2009-01-01

    The generation of an action potential is a complex process in excitable cells which involves the temporal opening and closing of several voltage-dependent ion channels in the cell membrane. The shape of an action potential can carry information concerning the state of the involved ion channels and their relationship to cellular processes. Alteration of these ion channels by the administration of toxins, drugs, and biochemicals can change the action potential’s shape in a specific way which ca...

  6. Fish oil curtails the human action potential dome in a heterogeneous manner: Implication for arrhythmogenesis

    NARCIS (Netherlands)

    A.O. Verkerk; H.M. den Ruijter; N. de Jonge; R. Coronel

    2009-01-01

    Omega-3 polyunsaturated fatty acids (omega3-PUFAs) from fish oil modulate various ion channels, including the L-type calcium current (I(Ca,L)). As a result, fish oil shortens the cardiac action potential and may cause a loss of the dome of the action potential (AP). Under conditions of increased pre

  7. Back-propagation of physiological action potential output in dendrites of slender-tufted L5A pyramidal neurons

    OpenAIRE

    Grewe, Benjamin F.; Audrey Bonnan; Andreas Frick

    2010-01-01

    Pyramidal neurons of layer 5A are a major neocortical output type and clearly distinguished from layer 5B pyramidal neurons with respect to morphology, in vivo firing patterns, and connectivity; yet knowledge of their dendritic properties is scant. We used a combination of whole-cell recordings and Ca2+ imaging techniques in vitro to explore the specific dendritic signalling role of physiological action potential patterns recorded in vivo in layer 5A pyramidal neurons of the whisker-related &...

  8. Quantitative assessment of the distributions of membrane conductances involved in action potential backpropagation along basal dendrites.

    Science.gov (United States)

    Acker, Corey D; Antic, Srdjan D

    2009-03-01

    Basal dendrites of prefrontal cortical neurons receive strong synaptic drive from recurrent excitatory synaptic inputs. Synaptic integration within basal dendrites is therefore likely to play an important role in cortical information processing. Both synaptic integration and synaptic plasticity depend crucially on dendritic membrane excitability and the backpropagation of action potentials. We carried out multisite voltage-sensitive dye imaging of membrane potential transients from thin basal branches of prefrontal cortical pyramidal neurons before and after application of channel blockers. We found that backpropagating action potentials (bAPs) are predominantly controlled by voltage-gated sodium and A-type potassium channels. In contrast, pharmacologically blocking the delayed rectifier potassium, voltage-gated calcium, or I(h) conductance had little effect on dendritic AP propagation. Optically recorded bAP waveforms were quantified and multicompartmental modeling was used to link the observed behavior with the underlying biophysical properties. The best-fit model included a nonuniform sodium channel distribution with decreasing conductance with distance from the soma, together with a nonuniform (increasing) A-type potassium conductance. AP amplitudes decline with distance in this model, but to a lesser extent than previously thought. We used this model to explore the mechanisms underlying two sets of published data involving high-frequency trains of APs and the local generation of sodium spikelets. We also explored the conditions under which I(A) down-regulation would produce branch strength potentiation in the proposed model. Finally, we discuss the hypothesis that a fraction of basal branches may have different membrane properties compared with sister branches in the same dendritic tree. PMID:19118105

  9. Consumer-Related Food Waste: Causes and Potential for Action

    Directory of Open Access Journals (Sweden)

    Jessica Aschemann-Witzel

    2015-05-01

    Full Text Available In the past decade, food waste has received increased attention on both academic and societal levels. As a cause of negative economic, environmental and social effects, food waste is considered to be one of the sustainability issues that needs to be addressed. In developed countries, consumers are one of the biggest sources of food waste. To successfully reduce consumer-related food waste, it is necessary to have a clear understanding of the factors influencing food waste-related consumer perceptions and behaviors. The present paper presents the results of a literature review and expert interviews on factors causing consumer-related food waste in households and supply chains. Results show that consumers’ motivation to avoid food waste, their management skills of food provisioning and food handling and their trade-offs between priorities have an extensive influence on their food waste behaviors. We identify actions that governments, societal stakeholders and retailers can undertake to reduce consumer-related food waste, highlighting that synergistic actions between all parties are most promising. Further research should focus on exploring specific food waste contexts and interactions more in-depth. Experiments and interventions in particular can contribute to a shift from analysis to solutions.

  10. Time-Dependent Action in φ~6 Potential

    Institute of Scientific and Technical Information of China (English)

    Hatem Widyan; Mashhoor Al-Wardat

    2012-01-01

    The false vacuum decay in field theory from a coherently oscillating initial state is studied for φ6 potential. An oscillating bubble solution is obtained. The instantaneous bubble nucleation rate is calculated.

  11. A model for thermal exchange in axons during action potential propagation.

    OpenAIRE

    Masson, Jean-Baptiste; Gallot, Guilhem

    2008-01-01

    International audience Several experiments have shown that during propagation of the action potential in axons, thermal energy is locally exchanged. In this paper, we use a simple model based on statistical physics to show that an important part of this exchange comes from the physics of the effusion. We evaluate, during the action potential propagation, the variation of internal energy and of the energy associated with the chemical potential of the effusion of water and ions to extract th...

  12. Potential synergy of phytochemicals in cancer prevention: mechanism of action.

    Science.gov (United States)

    Liu, Rui Hai

    2004-12-01

    Epidemiological studies have consistently shown that regular consumption of fruits and vegetables is strongly associated with reduced risk of developing chronic diseases, such as cancer and cardiovascular disease. It is now widely believed that the actions of the antioxidant nutrients alone do not explain the observed health benefits of diets rich in fruits and vegetables, because taken alone, the individual antioxidants studied in clinical trials do not appear to have consistent preventive effects. Work performed by our group and others has shown that fruits and vegetable phytochemical extracts exhibit strong antioxidant and antiproliferative activities and that the major part of total antioxidant activity is from the combination of phytochemicals. We proposed that the additive and synergistic effects of phytochemicals in fruits and vegetables are responsible for these potent antioxidant and anticancer activities and that the benefit of a diet rich in fruits and vegetables is attributed to the complex mixture of phytochemicals present in whole foods. This explains why no single antioxidant can replace the combination of natural phytochemicals in fruits and vegetables to achieve the health benefits. The evidence suggests that antioxidants or bioactive compounds are best acquired through whole-food consumption, not from expensive dietary supplements. We believe that a recommendation that consumers eat 5 to 10 servings of a wide variety of fruits and vegetables daily is an appropriate strategy for significantly reducing the risk of chronic diseases and to meet their nutrient requirements for optimum health.

  13. Neuronal oscillations enhance stimulus discrimination by ensuring action potential precision

    DEFF Research Database (Denmark)

    Schaefer, Andreas T; Angelo, Kamilla; Spors, Hartwig;

    2006-01-01

    Although oscillations in membrane potential are a prominent feature of sensory, motor, and cognitive function, their precise role in signal processing remains elusive. Here we show, using a combination of in vivo, in vitro, and theoretical approaches, that both synaptically and intrinsically......--permitted accurate discernment of up to 1,000 different stimuli. At low oscillation frequencies, stimulus discrimination showed a clear phase dependence whereby inputs arriving during the trough and the early rising phase of an oscillation cycle were most robustly discriminated. Thus, by ensuring AP precision...

  14. Consequences of converting graded to action potentials upon neural information coding and energy efficiency.

    Science.gov (United States)

    Sengupta, Biswa; Laughlin, Simon Barry; Niven, Jeremy Edward

    2014-01-01

    Information is encoded in neural circuits using both graded and action potentials, converting between them within single neurons and successive processing layers. This conversion is accompanied by information loss and a drop in energy efficiency. We investigate the biophysical causes of this loss of information and efficiency by comparing spiking neuron models, containing stochastic voltage-gated Na(+) and K(+) channels, with generator potential and graded potential models lacking voltage-gated Na(+) channels. We identify three causes of information loss in the generator potential that are the by-product of action potential generation: (1) the voltage-gated Na(+) channels necessary for action potential generation increase intrinsic noise and (2) introduce non-linearities, and (3) the finite duration of the action potential creates a 'footprint' in the generator potential that obscures incoming signals. These three processes reduce information rates by ∼50% in generator potentials, to ∼3 times that of spike trains. Both generator potentials and graded potentials consume almost an order of magnitude less energy per second than spike trains. Because of the lower information rates of generator potentials they are substantially less energy efficient than graded potentials. However, both are an order of magnitude more efficient than spike trains due to the higher energy costs and low information content of spikes, emphasizing that there is a two-fold cost of converting analogue to digital; information loss and cost inflation.

  15. More evidence for a refined Gribov-Zwanziger action based on an effective potential approach

    OpenAIRE

    Vandersickel, N.; Dudal, D.; Sorella, S.P.

    2011-01-01

    The purpose of this proceeding is twofold. Firstly, we shall make the refining of the Gribov-Zwanziger action more complete by taking into account more condensates than considered so far. Secondly, we shall provide more evidence for the refined Gribov-Zwanziger action based on an effective potential approach.

  16. Action potential detection by non-linear microscopy

    Science.gov (United States)

    Sacconi, Leonardo; Lotti, Jacopo; O'Connor, Rodney P.; Mapelli, Jonathan; Gandolfi, Daniela; D'Angelo, Egidio; Pavone, Francesco S.

    2009-02-01

    In this work, we combined the advantages of second-harmonic generation (SHG) with a random access (RA) excitation scheme to realize a new microscope (RA-SHG) capable of optically recording fast membrane potential events occurring in a wide-field configuration. The RA-SHG microscope in combination with a bulk staining method with FM4-64 was used to simultaneously record electrical activity from clusters of Purkinje cells (PCs) in acute cerebellar slices. Spontaneous electrical activity was also monitored simultaneously in pairs of neurons, where APs were recorded in a single trial without averaging. These results show the strength of this technique to describe the temporal dynamics of neuronal assemblies.

  17. 7 CFR 1945.19 - Reporting potential natural disasters and initial actions.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 13 2010-01-01 2009-01-01 true Reporting potential natural disasters and initial... Assistance-General § 1945.19 Reporting potential natural disasters and initial actions. (a) Purpose. The purpose of reporting potential natural disasters is to provide a systematic procedure for rapid...

  18. Spatial and frequency domain ring source models for the single muscle fiber action potential

    DEFF Research Database (Denmark)

    Henneberg, Kaj-åge; R., Plonsey

    1994-01-01

    In the paper, single-fibre models for the extracellular action potential are developed that will allow the potential to the evaluated at an arbitrary field point in the extracellular space. Fourier-domain models are restricted in that they evaluate potentials at equidistant points along a line...

  19. Control of Secretion by Encodes of Action Potentials in Neuronal Cells

    Institute of Scientific and Technical Information of China (English)

    Kailai Duan; Zhuan Zhou

    2003-01-01

    @@ Action potentials (APs) are principle physiological stimuli of neurotransmitter secretion or synaptic transmis sion. Most studies on stimulus-secretion-coupling have been performed under voltage clamp using artificial electric stimulations.

  20. Optimisation of Ionic Models to Fit Tissue Action Potentials: Application to 3D Atrial Modelling

    Directory of Open Access Journals (Sweden)

    Amr Al Abed

    2013-01-01

    Full Text Available A 3D model of atrial electrical activity has been developed with spatially heterogeneous electrophysiological properties. The atrial geometry, reconstructed from the male Visible Human dataset, included gross anatomical features such as the central and peripheral sinoatrial node (SAN, intra-atrial connections, pulmonary veins, inferior and superior vena cava, and the coronary sinus. Membrane potentials of myocytes from spontaneously active or electrically paced in vitro rabbit cardiac tissue preparations were recorded using intracellular glass microelectrodes. Action potentials of central and peripheral SAN, right and left atrial, and pulmonary vein myocytes were each fitted using a generic ionic model having three phenomenological ionic current components: one time-dependent inward, one time-dependent outward, and one leakage current. To bridge the gap between the single-cell ionic models and the gross electrical behaviour of the 3D whole-atrial model, a simplified 2D tissue disc with heterogeneous regions was optimised to arrive at parameters for each cell type under electrotonic load. Parameters were then incorporated into the 3D atrial model, which as a result exhibited a spontaneously active SAN able to rhythmically excite the atria. The tissue-based optimisation of ionic models and the modelling process outlined are generic and applicable to image-based computer reconstruction and simulation of excitable tissue.

  1. Dynamics of Action Potential Initiation in the GABAergic Thalamic Reticular Nucleus In Vivo

    OpenAIRE

    Fabián Muñoz; Pablo Fuentealba

    2012-01-01

    Understanding the neural mechanisms of action potential generation is critical to establish the way neural circuits generate and coordinate activity. Accordingly, we investigated the dynamics of action potential initiation in the GABAergic thalamic reticular nucleus (TRN) using in vivo intracellular recordings in cats in order to preserve anatomically-intact axo-dendritic distributions and naturally-occurring spatiotemporal patterns of synaptic activity in this structure that regulates the th...

  2. Cortical Action Potential Backpropagation Explains Spike Threshold Variability and Rapid-Onset Kinetics

    OpenAIRE

    Yu, Yuguo; Shu, Yousheng; McCormick, David A.

    2008-01-01

    Neocortical action potential responses in vivo are characterized by considerable threshold variability, and thus timing and rate variability, even under seemingly identical conditions. This finding suggests that cortical ensembles are required for accurate sensorimotor integration and processing. Intracellularly, trial-to-trial variability results not only from variation in synaptic activities, but also in the transformation of these into patterns of action potentials. Through simultaneous ax...

  3. NeuroGrid: recording action potentials from the surface of the brain

    OpenAIRE

    Khodagholy, Dion; Gelinas, Jennifer N.; Thesen, Thomas; Doyle, Werner; Devinsky, Orrin; Malliaras, George G.; Buzsáki, György

    2014-01-01

    Recording from neural networks at the resolution of action potentials is critical for understanding how information is processed in the brain. Here, we address this challenge by developing an organic material-based, ultra-conformable, biocompatible and scalable neural interface array (the ‘NeuroGrid’) that can record both LFP and action potentials from superficial cortical neurons without penetrating the brain surface. Spikes with features of interneurons and pyramidal cells were simultaneous...

  4. POTENTIAL OF AIRBORNE IMAGING SPECTROSCOPY AT CZECHGLOBE

    Directory of Open Access Journals (Sweden)

    J. Hanuš

    2016-06-01

    Full Text Available Ecosystems, their services, structures and functions are affected by complex environmental processes, which are both natural and human-induced and globally changing. In order to understand how ecosystems behave in globally changing environment, it is important to monitor the current status of ecosystems and their structural and functional changes in time and space. An essential tool allowing monitoring of ecosystems is remote sensing (RS. Many ecosystems variables are being translated into a spectral response recorded by RS instruments. It is however important to understand the complexity and synergies of the key ecosystem variables influencing the reflected signal. This can be achieved by analysing high resolution RS data from multiple sources acquired simultaneously from the same platform. Such a system has been recently built at CzechGlobe - Global Change Research Institute (The Czech Academy of Sciences. CzechGlobe has been significantly extending its research infrastructure in the last years, which allows advanced monitoring of ecosystem changes at hierarchical levels spanning from molecules to entire ecosystems. One of the CzechGlobe components is a laboratory of imaging spectroscopy. The laboratory is now operating a new platform for advanced remote sensing observations called FLIS (Flying Laboratory of Imaging Spectroscopy. FLIS consists of an airborne carrier equipped with passive RS systems. The core instrument of FLIS is a hyperspectral imaging system provided by Itres Ltd. The hyperspectral system consists of three spectroradiometers (CASI 1500, SASI 600 and TASI 600 that cover the reflective spectral range from 380 to 2450 nm, as well as the thermal range from 8 to 11.5 μm. The airborne platform is prepared for mounting of full-waveform laser scanner Riegl-Q780 as well, however a laser scanner is not a permanent part of FLIS. In 2014 the installation of the hyperspectral scanners was completed and the first flights were carried out

  5. Potential of Airborne Imaging Spectroscopy at Czechglobe

    Science.gov (United States)

    Hanuš, J.; Fabiánek, T.; Fajmon, L.

    2016-06-01

    Ecosystems, their services, structures and functions are affected by complex environmental processes, which are both natural and human-induced and globally changing. In order to understand how ecosystems behave in globally changing environment, it is important to monitor the current status of ecosystems and their structural and functional changes in time and space. An essential tool allowing monitoring of ecosystems is remote sensing (RS). Many ecosystems variables are being translated into a spectral response recorded by RS instruments. It is however important to understand the complexity and synergies of the key ecosystem variables influencing the reflected signal. This can be achieved by analysing high resolution RS data from multiple sources acquired simultaneously from the same platform. Such a system has been recently built at CzechGlobe - Global Change Research Institute (The Czech Academy of Sciences). CzechGlobe has been significantly extending its research infrastructure in the last years, which allows advanced monitoring of ecosystem changes at hierarchical levels spanning from molecules to entire ecosystems. One of the CzechGlobe components is a laboratory of imaging spectroscopy. The laboratory is now operating a new platform for advanced remote sensing observations called FLIS (Flying Laboratory of Imaging Spectroscopy). FLIS consists of an airborne carrier equipped with passive RS systems. The core instrument of FLIS is a hyperspectral imaging system provided by Itres Ltd. The hyperspectral system consists of three spectroradiometers (CASI 1500, SASI 600 and TASI 600) that cover the reflective spectral range from 380 to 2450 nm, as well as the thermal range from 8 to 11.5 μm. The airborne platform is prepared for mounting of full-waveform laser scanner Riegl-Q780 as well, however a laser scanner is not a permanent part of FLIS. In 2014 the installation of the hyperspectral scanners was completed and the first flights were carried out with all

  6. Detection of Variability of the Motor Unit Action Potential Shape by Means of the Firing Patterns

    DEFF Research Database (Denmark)

    Krarup, Christian; Nikolic, Mile; Dahl, Kristian;

    1997-01-01

    The motor unit action potential is a summation of the potentials of the individual muscle fibers from the same motor unit.By using a newly developed automatic EMG decomposition system, variability of the firing patterns of the muscle fibers are analyzed.......The motor unit action potential is a summation of the potentials of the individual muscle fibers from the same motor unit.By using a newly developed automatic EMG decomposition system, variability of the firing patterns of the muscle fibers are analyzed....

  7. Distinct electrophysiological potentials for intention in action and prior intention for action

    DEFF Research Database (Denmark)

    Vinding, Mikkel C; Jensen, Mads; Overgaard, Morten

    2014-01-01

    The role of conscious intention in relation to motoric movements has become a major topic of investigation in neuroscience. Traditionally, reports of conscious intention have been compared to various features of the readiness-potential (RP) – an electrophysiological signal that appears before...... voluntary movements. Experiments, however, tend to study intentions in immediate relation to movements (proximal intentions), thus ignoring other aspects of intentions such as planning or deciding in advance of movement (distal intentions). The current study examines the difference in electrophysiological...... activity between proximal intention and distal intention, using electroencephalography (EEG). Participants had to form an intention to move and then wait 2.5 sec before performing the actual movement. In this way, the electrophysiological activity related to forming a conscious intention was separated from...

  8. Animal imaging studies of potential brain damage

    Science.gov (United States)

    Gatley, S. J.; Vazquez, M. E.; Rice, O.

    To date, animal studies have not been able to predict the likelihood of problems in human neurological health due to HZE particle exposure during space missions outside the Earth's magnetosphere. In ongoing studies in mice, we have demonstrated that cocaine stimulated locomotor activity is reduced by a moderate dose (120 cGy) of 1 GeV 56Fe particles. We postulate that imaging experiments in animals may provide more sensitive and earlier indicators of damage due to HZE particles than behavioral tests. Since the small size of the mouse brain is not well suited to the spatial resolution offered by microPET, we are now repeating some of our studies in a rat model. We anticipate that this will enable us to identify imaging correlates of behavioral endpoints. A specific hypothesis of our studies is that changes in the metabolic rate for glucose in striatum of animals will be correlated with alterations in locomotor activity. We will also evaluate whether the neuroprotective drug L-deprenyl reduces the effect of radiation on locomotor activity. In addition, we will conduct microPET studies of brain monoamine oxidase A and monoamine oxidase B in rats before and at various times after irradiation with HZE particles. The hypothesis is that monoamine oxidase A, which is located in nerve terminals, will be unchanged or decreased after irradiation, while monoamine oxidase B, which is located in glial cells, will be increased after irradiation. Neurochemical effects that could be measured using PET could in principle be applied in astronauts, in terms of detecting and monitoring subtle neurological damage that might have occurred during long space missions. More speculative uses of PET are in screening candidates for prolonged space missions (for example, for adequate reserve in critical brain circuits) and in optimizing medications to treat impairments after missions.

  9. Potential involvement of serotonergic signaling in ketamine's antidepressant actions: A critical review.

    Science.gov (United States)

    du Jardin, Kristian Gaarn; Müller, Heidi Kaastrup; Elfving, Betina; Dale, Elena; Wegener, Gregers; Sanchez, Connie

    2016-11-01

    A single i.v. infusion of ketamine, classified as an N-methyl-d-aspartate (NMDA) receptor antagonist, may alleviate depressive symptoms within hours of administration in treatment resistant depressed patients, and the antidepressant effect may last for several weeks. These unique therapeutic properties have prompted researchers to explore the mechanisms mediating the antidepressant effects of ketamine, but despite many efforts, no consensus on its antidepressant mechanism of action has been reached. Recent preclinical reports have associated the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT) with the antidepressant-like action of ketamine. Here, we review the current evidence for a serotonergic role in ketamine's antidepressant effects. The pharmacological profile of ketamine may include equipotent activity on several non-NMDA targets, and the current hypotheses for the mechanisms responsible for ketamine's antidepressant activity do not appear to preclude the possibility that non-glutamate neurotransmitters are involved in the antidepressant effects. At multiple levels, the serotonergic and glutamatergic systems interact, and such crosstalk could support the notion that changes in serotonergic neurotransmission may impact ketamine's antidepressant potential. In line with these prospects, ketamine may increase 5-HT levels in the prefrontal cortex of rats, plausibly via hippocampal NMDA receptor inhibition and activation of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. In addition, a number of preclinical studies suggest that the antidepressant-like effects of ketamine may depend on endogenous activation of 5-HT receptors. Recent imaging and behavioral data predominantly support a role for 5-HT1A or 5-HT1B receptors, but the full range of 5-HT receptors has currently not been systematically investigated in this context. Furthermore, the nature of any 5-HT dependent mechanism in ketamine's antidepressant effect is currently not

  10. Fraudulent retouching of digital radiographic images - a potential risk

    Energy Technology Data Exchange (ETDEWEB)

    Chang, H.J.; Oh, S.N.; Park, M.Y.; Rha, S.E. [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, Catholic University of Korea, 505 Banpo-Dong, Seocho-Ku, Seoul 137-040 (Korea, Republic of); Choi, B.G., E-mail: cbg@catholic.ac.k [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, Catholic University of Korea, 505 Banpo-Dong, Seocho-Ku, Seoul 137-040 (Korea, Republic of)

    2010-12-15

    Aim: To determine whether radiologists can recognize images retouched to include sham lesions. Materials and methods: Ten representative key images were selected of aortic dissection, hepatocellular carcinoma, renal cell carcinoma, colon cancer, liver metastasis, hepatic cyst, gallbladder stones, splenic artery aneurysm, adrenal adenoma, and stomach cancer from abdominal computed tomography (CT) imaging performed in 2008. Five of the key images were replaced with retouched images using image-editing software. The time to complete retouching was recorded for each image. Radiologists were requested to make a diagnosis for the 10 images, and were then asked to identify possible retouched images. The time taken to reach a decision in each case was recorded. Thirty radiologists (13 residents and 17 attending radiologists) participated as reviewers. Results: The time to complete retouching was 15.2 {+-} 3.15 min. None of the reviewers recognized that some images were retouched during diagnosis. The rate of correct diagnosis was 90% (range 71.7-100%). After reviewers were informed of possible image retouching, the detection rate of retouched images was 50% (40-58.3%). This rate was statistically the same as random choice (p = 0.876). There was no significant difference between residents and attending radiologists in the detection rate of retouched images (p = 0.786). The time to diagnosis and the time to detection of the retouched images were 15 (14-17) and 6 (5-7) min, respectively. Conclusion: Digital images can be easily retouched, and radiologists have difficulty in identifying retouched images. Radiologists should be aware of the potential fraudulent use of retouched images.

  11. Effects of acetylcholine and noradrenalin on action potentials of isolated rabbit sinoatrial and atrial myocytes

    Directory of Open Access Journals (Sweden)

    Arie O. Verkerk

    2012-05-01

    Full Text Available The autonomic nervous system controls heart rate and contractility through sympathetic and parasympathetic inputs to the cardiac tissue, with acetylcholine (ACh and noradrenalin (NA as the chemical transmitters. In recent years, it has become clear that specific Regulators of G protein Signalling proteins (RGS proteins suppress muscarinic sensitivity and parasympathetic tone, identifying RGS proteins as intriguing potential therapeutic targets. In the present study, we have identified the effects of 1 µM ACh and 1 µM NA on the intrinsic action potentials of sinotrial (SA nodal and atrial myocytes. Single cells were enzymatically isolated from the SA node or from the left atrium of rabbit hearts. Action potentials were recorded using the amphotericin-perforated patch-clamp technique in the absence and presence of ACh, NA or a combination of both. In SA nodal myocytes, ACh increased cycle length and decreased diastolic depolarization rate, whereas NA decreased cycle length and increased diastolic depolarization rate. Both ACh and NA increased maximum upstroke velocity. Furthermore, ACh hyperpolarized the maximum diastolic potential. In atrial myocytes stimulated at 2 Hz, both ACh and NA hyperpolarized the maximum diastolic potential, increased the action potential amplitude, and increased the maximum upstroke velocity. Action potential duration at 50 and 90% repolarization was decreased by ACh, but increased by NA. The effects of both ACh and NA on action potential duration showed a dose dependence in the range of 1–1,000 nM, while a clear-cut frequency dependence in the range of 1–4 Hz was absent. Intermediate results were obtained in the combined presence of ACh and NA in both SA nodal and atrial myocytes. Our data uncover the extent to which SA nodal and atrial action potentials are intrinsically dependent on ACh, NA or a combination of both and may thus guide further experiments with RGS proteins.

  12. Application of functional multineuron calcium imaging technology in observing action potentials of hippocampal neurons%功能性多神经元钙成像技术在海马神经元动作电位观察中的应用

    Institute of Scientific and Technical Information of China (English)

    孙懿; 松木则夫; 池谷裕二; 蒲小平

    2013-01-01

    Objective-. To observe the electric activity of large neuron populations in acutely cultured hippocampal slices. Methods; Sprague Dawley rats at postnatal 7 days were deeply anesthetized by hypothermia and decapitated. The brains were removed and horizontally cut into slices which were cultured on 6-well plates. Male C57-BL/6J mice at postnatal 3-5 weeks were decapitated with deep ether anesthesia. The brains were quickly isolated and horizontally cut into slices which were transferred to oxygenated modified artificial cerebrospinal fluid ( pre-warmed at 37 °C ) and stored for more than 60 min. The hippocampal slices were loaded with calcium-sensitive fluorescence indicator and monitored by functional multineuron calcium imaging (fMCI). Results: Action potentials-evoked calcium transients were simultaneously imaged from large neuron populations. Conclusion; fMCI provides a kind of powerful tool to morphologically and functionally reveal hippocampal network activity and evaluate new central nervous system drugs.%目的:观察海马脑片中锥体细胞层群体神经元的电活动.方法:取出生后7d的Sprague Dawley大鼠全脑,无菌条件下水平方向切片,转至6孔板中培养;另取出生后3~5周的C57-BL/6J小鼠全脑,无菌条件下水平方向切片,转至37℃氧饱和的人工脑脊液中稳定至少60 min备用.大鼠培养脑片及小鼠急性脑片负载钙离子荧光指示剂,采用功能性多神经元钙成像技术检测海马锥体细胞层中大规模神经元与动作电位相关的钙瞬变.结果:大鼠培养脑片及小鼠急性脑片中记录到大量单个神经元的与动作电位相关的钙瞬变.结论:功能性多神经元钙成像技术是揭示海马神经网络活动及中枢神经系统有关创新药物评价的全新且有效的研究方法.

  13. 76 FR 21938 - Potential Environmental Impacts of the Proposed Runway 13 Extension and Associated Actions for...

    Science.gov (United States)

    2011-04-19

    ... Federal Aviation Administration Potential Environmental Impacts of the Proposed Runway 13 Extension and... Administration (FAA), Department of Transportation (DOT). ACTION: Notice of availability of a final EA and FONSI/ROD for the evaluation of the potential environmental impacts associated with the proposed Runway...

  14. Perturbation analysis of spontaneous action potential initiation by stochastic ion channels

    KAUST Repository

    Keener, James P.

    2011-07-01

    A stochastic interpretation of spontaneous action potential initiation is developed for the Morris-Lecar equations. Initiation of a spontaneous action potential can be interpreted as the escape from one of the wells of a double well potential, and we develop an asymptotic approximation of the mean exit time using a recently developed quasistationary perturbation method. Using the fact that the activating ionic channel\\'s random openings and closings are fast relative to other processes, we derive an accurate estimate for the mean time to fire an action potential (MFT), which is valid for a below-threshold applied current. Previous studies have found that for above-threshold applied current, where there is only a single stable fixed point, a diffusion approximation can be used. We also explore why different diffusion approximation techniques fail to estimate the MFT. © 2011 American Physical Society.

  15. Sodium and calcium currents shape action potentials in immature mouse inner hair cells.

    Science.gov (United States)

    Marcotti, Walter; Johnson, Stuart L; Rusch, Alfons; Kros, Corne J

    2003-11-01

    Before the onset of hearing at postnatal day 12, mouse inner hair cells (IHCs) produce spontaneous and evoked action potentials. These spikes are likely to induce neurotransmitter release onto auditory nerve fibres. Since immature IHCs express both alpha1D (Cav1.3) Ca2+ and Na+ currents that activate near the resting potential, we examined whether these two conductances are involved in shaping the action potentials. Both had extremely rapid activation kinetics, followed by fast and complete voltage-dependent inactivation for the Na+ current, and slower, partially Ca2+-dependent inactivation for the Ca2+ current. Only the Ca2+ current is necessary for spontaneous and induced action potentials, and 29 % of cells lacked a Na+ current. The Na+ current does, however, shorten the time to reach the action-potential threshold, whereas the Ca2+ current is mainly involved, together with the K+ currents, in determining the speed and size of the spikes. Both currents increased in size up to the end of the first postnatal week. After this, the Ca2+ current reduced to about 30 % of its maximum size and persisted in mature IHCs. The Na+ current was downregulated around the onset of hearing, when the spiking is also known to disappear. Although the Na+ current was observed as early as embryonic day 16.5, its role in action-potential generation was only evident from just after birth, when the resting membrane potential became sufficiently negative to remove a sizeable fraction of the inactivation (half inactivation was at -71 mV). The size of both currents was positively correlated with the developmental change in action-potential frequency.

  16. Docosahexaenoic acid has influence on action potentials and transient outward potassium currents of ventricular myocytes

    Directory of Open Access Journals (Sweden)

    Yang Zhen-Yu

    2010-04-01

    Full Text Available Abstract Background There are many reports about the anti-arrhythmic effects of ω-3 polyunsaturated fatty acids, however, the mechanisms are still not completely delineated. The purpose of this study was to investigate the characteristics of action potentials and transient outward potassium currents (Ito of Sprague-Dawley rat ventricular myocytes and the effects of docosahexaenoic acid (DHA on action potentials and Ito. Methods The calcium-tolerant rat ventricular myocytes were isolated by enzyme digestion. Action potentials and Ito of epicardial, mid-cardial and endocardial ventricular myocytes were recorded by whole-cell patch clamp technique. Results 1. Action potential durations (APDs were prolonged from epicardial to endocardial ventricular myocytes (P 2. Ito current densities were decreased from epicardial to endocardial ventricular myocytes, which were 59.50 ± 15.99 pA/pF, 29.15 ± 5.53 pA/pF, and 12.29 ± 3.62 pA/pF, respectively at +70 mV test potential (P 3. APDs were gradually prolonged with the increase of DHA concentrations from 1 μmol/L to 100 μmol/L, however, APDs changes were not significant as DHA concentrations were in the range of 0 μmol/L to 1 μmol/L. 4. Ito currents were gradually reduced with the increase of DHA concentrations from 1 μmol/L to 100 μmol/L, and its half-inhibited concentration was 5.3 μmol/L. The results showed that there were regional differences in the distribution of action potentials and Ito in rat epicardial, mid-cardial and endocardial ventricular myocytes. APDs were prolonged and Ito current densities were gradually reduced with the increase of DHA concentrations. Conclusion The anti-arrhythmia mechanisms of DHA are complex, however, the effects of DHA on action potentials and Ito may be one of the important causes.

  17. Optical magnetic detection of single-neuron action potentials using NV-diamond

    Science.gov (United States)

    Turner, Matthew; Barry, John; Schloss, Jennifer; Glenn, David; Walsworth, Ron

    2016-05-01

    A key challenge for neuroscience is noninvasive, label-free sensing of action potential dynamics in whole organisms with single-neuron resolution. Here, we report a new approach to this problem: using nitrogen-vacancy (NV) color centers in diamond to measure the time-dependent magnetic fields produced by single-neuron action potentials. We demonstrate our method using excised single neurons from two invertebrate species, marine worm and squid; and then by single-neuron action potential magnetic sensing exterior to whole, live, opaque marine worms for extended periods with no adverse effect. The results lay the groundwork for real-time, noninvasive 3D magnetic mapping of functional mammalian neuronal networks.

  18. Modeling and simulation of ion channels and action potentials in taste receptor cells

    Institute of Scientific and Technical Information of China (English)

    CHEN PeiHua; LIU Xiaodong; ZHANG Wei; ZHOU Jun; WANG Ping; YANG Wei; LUO JianHong

    2009-01-01

    Based on patch clamp data on the ionic currents of rat taste receptor cells,a mathematical model of mammalian taste receptor cells was constructed to simulate the action potentials of taste receptor cells and their corresponding ionic components,including voltage-gated Na~+ currents and outward delayed rectifier K~+ currents.Our simulations reproduced the action potentials of taste receptor cells in response to electrical stimuli or sour tastants.The kinetics of ion channels and their roles in action potentials of taste receptor cells were also analyzed.Our prototype model of single taste receptor cell and simulation results presented in this paper provide the basis for the further study of taste information processing in the gustatory system.

  19. Phase lagging model of brain response to external stimuli - modeling of single action potential

    CERN Document Server

    Seetharaman, Karthik; Kulish, Vladimir V

    2012-01-01

    In this paper we detail a phase lagging model of brain response to external stimuli. The model is derived using the basic laws of physics like conservation of energy law. This model eliminates the paradox of instantaneous propagation of the action potential in the brain. The solution of this model is then presented. The model is further applied in the case of a single neuron and is verified by simulating a single action potential. The results of this modeling are useful not only for the fundamental understanding of single action potential generation, but also they can be applied in case of neuronal interactions where the results can be verified against the real EEG signal.

  20. Modeling and simulation of ion channels and action potentials in taste receptor cells

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on patch clamp data on the ionic currents of rat taste receptor cells, a mathematical model of mammalian taste receptor cells was constructed to simulate the action potentials of taste receptor cells and their corresponding ionic components, including voltage-gated Na+ currents and outward delayed rectifier K+ currents. Our simulations reproduced the action potentials of taste receptor cells in response to electrical stimuli or sour tastants. The kinetics of ion channels and their roles in action potentials of taste receptor cells were also analyzed. Our prototype model of single taste receptor cell and simulation results presented in this paper provide the basis for the further study of taste information processing in the gustatory system.

  1. A phantom axon setup for validating models of action potential recordings.

    Science.gov (United States)

    Rossel, Olivier; Soulier, Fabien; Bernard, Serge; Guiraud, David; Cathébras, Guy

    2016-08-01

    Electrode designs and strategies for electroneurogram recordings are often tested first by computer simulations and then by animal models, but they are rarely implanted for long-term evaluation in humans. The models show that the amplitude of the potential at the surface of an axon is higher in front of the nodes of Ranvier than at the internodes; however, this has not been investigated through in vivo measurements. An original experimental method is presented to emulate a single fiber action potential in an infinite conductive volume, allowing the potential of an axon to be recorded at both the nodes of Ranvier and the internodes, for a wide range of electrode-to-fiber radial distances. The paper particularly investigates the differences in the action potential amplitude along the longitudinal axis of an axon. At a short radial distance, the action potential amplitude measured in front of a node of Ranvier is two times larger than in the middle of two nodes. Moreover, farther from the phantom axon, the measured action potential amplitude is almost constant along the longitudinal axis. The results of this new method confirm the computer simulations, with a correlation of 97.6 %. PMID:27016364

  2. Image potential states at metal-dielectric interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Merry, W.R. Jr.

    1992-04-01

    Angle-resolved two-photon laser photoemission was used to observe the image potential electronic states on the (111) face of a silver single crystal. The transient image potential states were excited from the occupied bulk bands with photons whose energy was tunable around 4 eV. Photoemission of the image potential states was accomplished with photons of energy tunable around 2 eV. Image potential states were found to persist in the presence of physisorbed adlayers of xenon and cyclohexane. On clean Ag(111), the effective mass of the n=1 image potential state was found to be 1.4{plus_minus}0.1 times the mass of a free electron (m{sub e}). A binding energy of 0.77 eV, measured by earlier workers, was assumed in analysis of the data for the clean surface. On Ag(111), at 75 K covered by one monolayer of xenon, the binding energy of the n=1 image potential state was unchanged relative to its value on the clean surface. An effective mass of (1.00{plus_minus}0.05) {center_dot} m{sub e} was obtained. On Ag(111) at 167 K, covered by one monolayer of cyclohexane, the binding energy of the n=2 member of the image potential series was 0.30{plus_minus}0.05 eV. The energy of the n=1 state was again unchanged by deposition of the adsorbate. The effective masses of both states were (0.90{plus_minus}0.1) {center_dot} m{sub e}.

  3. Image potential states at metal-dielectric interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Merry, W.R. Jr.

    1992-04-01

    Angle-resolved two-photon laser photoemission was used to observe the image potential electronic states on the (111) face of a silver single crystal. The transient image potential states were excited from the occupied bulk bands with photons whose energy was tunable around 4 eV. Photoemission of the image potential states was accomplished with photons of energy tunable around 2 eV. Image potential states were found to persist in the presence of physisorbed adlayers of xenon and cyclohexane. On clean Ag(111), the effective mass of the n=1 image potential state was found to be 1.4{plus minus}0.1 times the mass of a free electron (m{sub e}). A binding energy of 0.77 eV, measured by earlier workers, was assumed in analysis of the data for the clean surface. On Ag(111), at 75 K covered by one monolayer of xenon, the binding energy of the n=1 image potential state was unchanged relative to its value on the clean surface. An effective mass of (1.00{plus minus}0.05) {center dot} m{sub e} was obtained. On Ag(111) at 167 K, covered by one monolayer of cyclohexane, the binding energy of the n=2 member of the image potential series was 0.30{plus minus}0.05 eV. The energy of the n=1 state was again unchanged by deposition of the adsorbate. The effective masses of both states were (0.90{plus minus}0.1) {center dot} m{sub e}.

  4. Incorporated fish oil fatty acids prevent action potential shortening induced by circulating fish oil fatty acids

    Directory of Open Access Journals (Sweden)

    Hester M Den Ruijter

    2010-11-01

    Full Text Available Increased consumption of fatty fish, rich in omega-3 polyunsaturated fatty acids (3-PUFAs reduces the severity and number of arrhythmias. Long term 3-PUFA-intake modulates the activity of several cardiac ion channels leading to cardiac action potential shortening. Circulating 3-PUFAs in the bloodstream and incorporated 3-PUFAs in the cardiac membrane have a different mechanism to shorten the action potential. It is, however, unknown whether circulating 3-PUFAs in the bloodstream enhance or diminish the effects of incorporated 3-PUFAs. In the present study, we address this issue. Rabbits were fed a diet rich in fish oil (3 or sunflower oil (9, as control for 3 weeks. Ventricular myocytes were isolated by enzymatic dissociation and action potentials were measured using the perforated patch clamp technique in the absence and presence of acutely administered 3-PUFAs. Plasma of 3 fed rabbits contained more free eicosapentaenoic acid (EPA and isolated myocytes of 3 fed rabbits contained higher amounts of both EPA and docosahexaenoic acid (DHA in their sarcolemma compared to control. In the absence of acutely administered fatty acids, 3 myocytes had a shorter action potential with a more negative plateau than 9 myocytes. In the 9 myocytes, but not in the 3 myocytes, acute administration of a mixture of EPA+DHA shortened the action potential significantly. From these data we conclude that incorporated 3-PUFAs into the sarcolemma and acutely administered 3 fatty acids do not have a cumulative effect on action potential duration and morphology. As a consequence, patients with a high cardiac 3-PUFA status will probably not benefit from short term 3 supplementation as an antiarrhythmic therapy.

  5. Differential effects of thioridazine enantiomers on action potential duration in rabbit papillary muscle

    DEFF Research Database (Denmark)

    Jensen, Ask Schou; Pennisi, Cristian Pablo; Sevcencu, Cristian;

    2015-01-01

    with (+)-thioridazine. In this study we for the first time investigate the cardiotoxicity of the isolated thioridazine enantiomers and show their effects on ventricular repolarization. The effects of (+)-thioridazine, (-)-thioridazine, and racemate on the rabbit ventricular action potential duration (APD) were...... investigated in a randomized controlled blinded experiment. Action potentials were measured in papillary muscles isolated from 21 female rabbits, and the drug effect on 90% APD in comparison with control (DeltaDelta-APD90) was evaluated. Increasing concentrations of (+)-thioridazine and the racemate caused...

  6. Wogonin potentiates the antitumor action of etoposide and ameliorates its adverse effects.

    Science.gov (United States)

    Enomoto, Riyo; Koshiba, Chika; Suzuki, Chie; Lee, Eibai

    2011-05-01

    Wogonin, a flavone in the roots of Scutellaria baicalensis, reduced etoposide-induced apoptotic cell death in normal cells, such as bone marrow cells and thymocytes. On the other hand, wogonin potentiated the proapoptotic or cytotoxic action of etoposide in tumor cells, such as Jurkat, HL-60, A549, and NCI-H226. These contradictory actions of wogonin on apoptosis are distinguished by normal or cancer cell types. Wogonin had no effect on apoptosis induced by other anticancer agents in the tumor cells. Thus, the potentiation effect of wogonin was observed only in etoposide-induced apoptosis in tumor cells. In a functional assay for P-glycoprotein (P-gp), wogonin suppressed excretion of calcein, a substrate for P-gp, in these tumor cells. Moreover, wogonin decreased the excretion of radiolabeled etoposide and accordingly increased intracellular content of this agent in the cells. P-gp inhibitors showed a similar potentiation effect on etoposide-induced apoptosis in these tumor cells. Thus, wogonin is likely to potentiate the anticancer action of etoposide due to P-gp inhibition and accumulation of this agent. These findings suggest that wogonin may be a useful chemotherapeutic adjuvant to potentiate the pharmacological action of etoposide and ameliorate its adverse effects. PMID:20658136

  7. Investigating a Potential Auxin-Related Mode of Hormetic/Inhibitory Action of the Phytotoxin Parthenin.

    Science.gov (United States)

    Belz, Regina G

    2016-01-01

    Parthenin is a metabolite of Parthenium hysterophorus and is believed to contribute to the weed's invasiveness via allelopathy. Despite the potential of parthenin to suppress competitors, low doses stimulate plant growth. This biphasic action was hypothesized to be auxin-like and, therefore, an auxin-related mode of parthenin action was investigated using two approaches: joint action experiments with Lactuca sativa, and dose-response experiments with auxin/antiauxin-resistant Arabidopsis thaliana genotypes. The joint action approach comprised binary mixtures of subinhibitory doses of the auxin 3-indoleacetic acid (IAA) mixed with parthenin or one of three reference compounds [indole-3-butyric acid (IBA), 2,3,5-triiodobenzoic acid (TIBA), 2-(p-chlorophenoxy)-2-methylpropionic acid (PCIB)]. The reference compounds significantly interacted with IAA at all doses, but parthenin interacted only at low doses indicating that parthenin hormesis may be auxin-related, in contrast to its inhibitory action. The genetic approach investigated the response of four auxin/antiauxin-resistant mutants and a wildtype to parthenin or two reference compounds (IAA, PCIB). The responses of mutant plants to the reference compounds confirmed previous reports, but differed from the responses observed for parthenin. Parthenin stimulated and inhibited all mutants independent of resistance. This provided no indication for an auxin-related action of parthenin. Therefore, the hypothesis of an auxin-related inhibitory action of parthenin was rejected in two independent experimental approaches, while the hypothesis of an auxin-related stimulatory effect could not be rejected. PMID:26686984

  8. Inhibition by TRPA1 agonists of compound action potentials in the frog sciatic nerve

    International Nuclear Information System (INIS)

    Highlights: •TRPA1 agonists inhibited compound action potentials in frog sciatic nerves. •This inhibition was not mediated by TRPA1 channels. •This efficacy was comparable to those of lidocaine and cocaine. •We found for the first time an ability of TRPA1 agonists to inhibit nerve conduction. -- Abstract: Although TRPV1 and TRPM8 agonists (vanilloid capsaicin and menthol, respectively) at high concentrations inhibit action potential conduction, it remains to be unknown whether TRPA1 agonists have a similar action. The present study examined the actions of TRPA1 agonists, cinnamaldehyde (CA) and allyl isothiocyanate (AITC), which differ in chemical structure from each other, on compound action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. CA and AITC concentration-dependently reduced the peak amplitude of the CAP with the IC50 values of 1.2 and 1.5 mM, respectively; these activities were resistant to a non-selective TRP antagonist ruthenium red or a selective TRPA1 antagonist HC-030031. The CA and AITC actions were distinct in property; the latter but not former action was delayed in onset and partially reversible, and CA but not AITC increased thresholds to elicit CAPs. A CAP inhibition was seen by hydroxy-α-sanshool (by 60% at 0.05 mM), which activates both TRPA1 and TRPV1 channels, a non-vanilloid TRPV1 agonist piperine (by 20% at 0.07 mM) and tetrahydrolavandulol (where the six-membered ring of menthol is opened; IC50 = 0.38 mM). It is suggested that TRPA1 agonists as well as TRPV1 and TRPM8 agonists have an ability to inhibit nerve conduction without TRP activation, although their agonists are quite different in chemical structure from each other

  9. Inhibition by TRPA1 agonists of compound action potentials in the frog sciatic nerve

    Energy Technology Data Exchange (ETDEWEB)

    Matsushita, Akitomo; Ohtsubo, Sena; Fujita, Tsugumi; Kumamoto, Eiichi, E-mail: kumamote@cc.saga-u.ac.jp

    2013-04-26

    Highlights: •TRPA1 agonists inhibited compound action potentials in frog sciatic nerves. •This inhibition was not mediated by TRPA1 channels. •This efficacy was comparable to those of lidocaine and cocaine. •We found for the first time an ability of TRPA1 agonists to inhibit nerve conduction. -- Abstract: Although TRPV1 and TRPM8 agonists (vanilloid capsaicin and menthol, respectively) at high concentrations inhibit action potential conduction, it remains to be unknown whether TRPA1 agonists have a similar action. The present study examined the actions of TRPA1 agonists, cinnamaldehyde (CA) and allyl isothiocyanate (AITC), which differ in chemical structure from each other, on compound action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. CA and AITC concentration-dependently reduced the peak amplitude of the CAP with the IC{sub 50} values of 1.2 and 1.5 mM, respectively; these activities were resistant to a non-selective TRP antagonist ruthenium red or a selective TRPA1 antagonist HC-030031. The CA and AITC actions were distinct in property; the latter but not former action was delayed in onset and partially reversible, and CA but not AITC increased thresholds to elicit CAPs. A CAP inhibition was seen by hydroxy-α-sanshool (by 60% at 0.05 mM), which activates both TRPA1 and TRPV1 channels, a non-vanilloid TRPV1 agonist piperine (by 20% at 0.07 mM) and tetrahydrolavandulol (where the six-membered ring of menthol is opened; IC{sub 50} = 0.38 mM). It is suggested that TRPA1 agonists as well as TRPV1 and TRPM8 agonists have an ability to inhibit nerve conduction without TRP activation, although their agonists are quite different in chemical structure from each other.

  10. Photoacoustic imaging: a potential new tool for arthritis

    Science.gov (United States)

    Wang, Xueding

    2012-12-01

    The potential application of photoacoustic imaging (PAI) technology to diagnostic imaging and therapeutic monitoring of inflammatory arthritis has been explored. The feasibility of our bench-top joint imaging systems in delineating soft articular tissue structures in a noninvasive manner was validated first on rat models and then on human peripheral joints. Based on the study on commonly used arthritis rat models, the capability of PAI to differentiate arthritic joints from the normal was also examined. With sufficient imaging depth, PAI can realize tomographic imaging of a human peripheral joint or a small-animal joint as a whole organ noninvasively. By presenting additional optical contrast and tissue functional information such as blood volume and blood oxygen saturation, PAI may provide an opportunity for early diagnosis of inflammatory joint disorders, e.g. rheumatoid arthritis, and for monitoring of therapeutic outcomes with improved sensitivity and accuracy.

  11. Multiple modes of action potential initiation and propagation in mitral cell primary dendrite

    DEFF Research Database (Denmark)

    Chen, Wei R; Shen, Gongyu Y; Shepherd, Gordon M;

    2002-01-01

    to support the back-propagation of the evoked somatic action potential to produce the second dendritic spike. In summary, the balance of spatially distributed excitatory and inhibitory inputs can dynamically switch the mitral cell firing among four different modes: axo-somatic initiation with back...

  12. Quantitative analysis of single muscle fibre action potentials recorded at known distances

    NARCIS (Netherlands)

    Albers, B.A.; Put, J.H.M.; Wallinga, W.; Wirtz, P.

    1989-01-01

    In vivo records of single fibre action potentials (SFAPs) have always been obtained at unknown distance from the active muscle fibre. A new experimental method has been developed enabling the derivation of the recording distance in animal experiments. A single fibre is stimulated with an intracellu

  13. Triangulation of the monophasic action potential causes flattening of the electrocardiographic T-wave

    DEFF Research Database (Denmark)

    Bhuiyan, Tanveer Ahmed; Graff, Claus; Thomsen, Morten Bækgaard;

    2012-01-01

    It has been proposed that triangulation on the cardiac action potential manifests as a broadened, more flat and notched T-wave on the ECG but to what extent such morphology characteristics are indicative of triangulation is more unclear. In this paper, we have analyzed the morphological changes...

  14. Youth Participatory Action Research and Educational Transformation: The Potential of Intertextuality as a Methodological Tool

    Science.gov (United States)

    Bertrand, Melanie

    2016-01-01

    In this article, Melanie Bertrand explores the potential of using the concept of intertextuality--which captures the way snippets of written or spoken text from one source become incorporated into other sources--in the study and practice of youth participatory action research (YPAR). Though this collective and youth-centered form of research…

  15. ACTION OF PROGESTERONE ON THE DEPOLARIZATION OF THE MEMBRANE POTENTIAL IN TOAD OOCYTES INDUCED BY LEUCINE

    Institute of Scientific and Technical Information of China (English)

    WANGYu-Feng

    1989-01-01

    The depolarization of the membrane potential in toad oocytes induced by leucine was found in our previous experiment. In this paper, a possible action or progesterone in the process was further investigated. After oocytes had been incubated for 16 to 24 hours with

  16. A dual potassium channel activator improves repolarization reserve and normalizes ventricular action potentials

    DEFF Research Database (Denmark)

    Calloe, Kirstine; Di Diego, José M; Hansen, Rie Schultz;

    2016-01-01

    cultured canine cardiac myocytes and determined whether a dual K(+) current activator can normalize K(+) currents and restore action potential (AP) configuration. METHODS AND RESULTS: Ventricular myocytes were isolated and cultured for up to 48h. Current and voltage clamp recordings were made using patch...... of EADs. Our results suggest a potential benefit of K(+) current activators under conditions of reduced repolarization reserve including heart failure....

  17. Effects of benactyzine on action potentials and contractile force of guinea pig papillary muscles

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Aim:To explore the effects of benactyzine (BEN) on the action potential and contractile force in guinea pig papillary muscles.Methods:Conventional microelectrode technique was used to record the fast action potentials (FAP) and slow action potentials (SAP) of guinea pig papillary muscles.Results:Benactyzine 5,10,50 μmol·L-1 suppressed the maximal upstroke velocity (vmax) of FAP and contractile force (Fc) concentration-dependently while prolonged the action potential duration at 50%,90% repolarization (APD50,APD90) and effective refractory period (ERP) of FAP.The suppression on the vmax was frequency-dependent.Benactyzine 5,10,50μmol·L-1 lengthened the APD50,APD90 of SAP induced by isoprenaline or histamine when perfused with KCl 22 mmol·L-1 Tyrode's solution.The vmax of the SAP was not decreased by benactyzine 5,10 μmol·L-1 but by 50 μmol·L-1.The effects on the SAP were antagonized by elevation of the extracellular calcium from 2.0 to 5.6 mmol·L-1.The effects of benactyzine on SAP elicited by tetrodotoxin resembled that by isoprenaline or histamine except the more pronounced suppression on vmax and action potential amplitude (APA).The persistent rapid spontaneous activity and triggered tachyarrhythmia induced by ouabain were also abolished immediately by benactyzine 5 μmol·L-1.Conclusion:Benactyzine can inhibit Na+,K+,Ca2+ transmembrane movement and intracellular Ca2+ mobilization in the myocardium,and this may be the electrophysiological basis of its effects against experimental arrhythmias.

  18. Whey protein potentiates the intestinotrophic action of glucagon-like peptide-2 in parenterally fed rats

    DEFF Research Database (Denmark)

    Liu, Xiaowen; Murali, Sangita G; Holst, Jens J;

    2009-01-01

    Glucagon-like peptide-2 (GLP-2) is a nutrient-regulated intestinotrophic hormone derived from proglucagon in the distal intestine. Enteral nutrients (EN) potentiate the action of GLP-2 to reverse parenteral nutrition (PN)-induced mucosal hypoplasia. The objective was to determine what enteral...... was associated with decreased DPP-IV activity in ileum and colon compared with casein, soy, or PN+GLP-2 alone, P action of GLP-2 to reverse PN-induced mucosal hypoplasia in association with decreased intestinal DPP-IV activity....

  19. 'Catching the waves' - slow cortical potentials as moderator of voluntary action.

    Science.gov (United States)

    Schmidt, Stefan; Jo, Han-Gue; Wittmann, Marc; Hinterberger, Thilo

    2016-09-01

    The readiness potential is an ongoing negativity in the EEG preceding a self-initiated movement by approximately 1.5s. So far it has predominantly been interpreted as a preparatory signal with a causal link to the upcoming movement. Here a different hypothesis is suggested which we call the selective slow cortical potential sampling hypothesis. In this review of recent research results we argue that the initiation of a voluntary action is more likely during negative fluctuations of the slow cortical potential and that the sampling and averaging of many trials leads to the observed negativity. That is, empirical evidence indicates that the early readiness potential is not a neural correlate of preconscious motor preparation and thus a determinant of action. Our hypothesis thereafter challenges the classic interpretation of the Libet experiment which is often taken as proof that there is no free will. We furthermore suggest that slow cortical potentials are related to an urge to act but are not a neural indicator of the decision process of action initiation.

  20. Acute NMDA receptor antagonism disrupts synchronization of action potential firing in rat prefrontal cortex.

    Directory of Open Access Journals (Sweden)

    Leonardo A Molina

    Full Text Available Antagonists of N-methyl-D-aspartate receptors (NMDAR have psychotomimetic effects in humans and are used to model schizophrenia in animals. We used high-density electrophysiological recordings to assess the effects of acute systemic injection of an NMDAR antagonist (MK-801 on ensemble neural processing in the medial prefrontal cortex of freely moving rats. Although MK-801 increased neuron firing rates and the amplitude of gamma-frequency oscillations in field potentials, the synchronization of action potential firing decreased and spike trains became more Poisson-like. This disorganization of action potential firing following MK-801 administration is consistent with changes in simulated cortical networks as the functional connections among pyramidal neurons become less clustered. Such loss of functional heterogeneity of the cortical microcircuit may disrupt information processing dependent on spike timing or the activation of discrete cortical neural ensembles, and thereby contribute to hallucinations and other features of psychosis induced by NMDAR antagonists.

  1. Voltage-gated sodium channel expression and action potential generation in differentiated NG108-15 cells

    OpenAIRE

    Liu Jinxu; Tu Huiyin; Zhang Dongze; Zheng Hong; Li Yu-Long

    2012-01-01

    Abstract Background The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na+ channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na+ channels, Na+ currents, and cell membrane excitability were investigated in NG108-15 cells. Result...

  2. Simulation and calculation of the contribution of hyperpolarization-activated cyclic nucleotide-gated channels to action potentials

    OpenAIRE

    Liao Liping; Lin Xianguang; Hu Jielin; Wu Xin; Yang Xiaofei; Wang Wei; Li Chenhong

    2016-01-01

    The hyperpolarization-activated cyclic nucleotide-gated (HCN) channel, which mediates the influx of cations, has an important role in action potential generation. In this article, we describe the contribution of the HCN channel to action potential generation. We simulated several common ion channels in neuron membranes based on data from rat dorsal root ganglion cells and modeled the action potential. The ion channel models employed in this paper were based...

  3. Potential of biological images for radiation therapy of cancer

    International Nuclear Information System (INIS)

    Full text: Recent technical advances in 3D conformal and intensity modulated radiotherapy (3DCRT and IMRT) based, on patient-specific CT and MRI images, have the potential of delivering exquisitely conformal dose distributions to the target volume while avoiding critical structures. Emerging clinical results in terms of reducing treatment-related morbidity and increasing local control appear promising. Recent developments in imaging have suggested that biological images may further positively impact cancer diagnosis, characterization and therapy. While in the past radiological images are largely anatomical, the new types of images can provide metabolic, biochemical, physiological, functional and molecular (genotypic and phenotypic) information. For radiation therapy, images that give information about factors (e.g. tumor hypoxia, Tpot) that influence radiosensitivity and treatment outcome can be regarded as radiobiological images. The ability of IMRT to 'paint' (in 2D) or 'sculpt' (in 3D) the dose, and produce exquisitely conformal dose distributions begs the '64 million dollar question' as to how to paint or sculpt, and whether biological imaging may provide the pertinent information. Can this new approach provide 'radiobiological phenotypes' non-invasively, and incrementally improve upon the predictive assays of radiobiological characteristics such as proliferative activity (Tpot - the potential doubling time), radiosensitivity (SF2 - the surviving fraction at a dose of 2 Gy), energy status (relative to sublethal damage repair), pH (a possible surrogate of hypoxia), tumor hypoxia, etc. as prognosticator(s) of radiation treatment outcome. Important for IMRT, the spatial (geometrical) distribution of the radiobiological phenotypes provide the basis for dose distribution design to conform to both the physical (geometrical) and the biological attributes. Copyright (2001) Australasian College of Physical Scientists and Engineers in Medicine

  4. An experimental study on a function of the cupula. Effect of cupula removal on the ampullary nerve action potential.

    Science.gov (United States)

    Suzuki, M; Harada, Y; Sugata, Y

    1984-01-01

    We used a posterior semicircular canal that had been isolated from a frog. From the utricular side the ampulla was cut open at a position one third of the way along the long axis. The cupula was removed through this opening using a glass micropipette. The action potential from the posterior ampullary nerve was recorded before and after removal of the cupula. After removal, the action potential disappeared almost completely. When the cupula was put back on the crista, the action potential was restored. When the cupula was put back upside down, the action potential recovered, but to a lesser extent.

  5. The mode of action of quinidine on isolated rabbit atria interpreted from intracellular potential records.

    Science.gov (United States)

    VAUGHAN WILLIAMS, E M

    1958-09-01

    An attempt has been made to show why quinidine, which has long been known not to lengthen the duration of the cardiac action potential, measured with external electrodes, and also not to lengthen, and sometimes to shorten, the absolute refractory period, nevertheless reduces the maximum frequency at which atria can respond to a stimulus. Simultaneous measurements have been made in electrically driven isolated rabbit atria of contractions, conduction velocity and intracellular potentials before and during exposure to a wide range of concentrations of quinidine sulphate. The resting potential remained undiminished, in contrast to the effect of quinidine on Purkinje fibres. In the therapeutic range of doses, up to 10 mg./l., the half-time for repolarization was either shortened or unchanged, thus providing an explanation for the failure of quinidine to prolong the absolute refractory period. In contrast, even at low concentrations of quinidine, conduction velocity and the rate of rise of the action potential were greatly slowed, and the height of the overshoot was reduced. The terminal phase of the action potential was prolonged. It is known that the rate of rise of the action potential is a function of the level of repolarization at which an impulse takes off (the more negative the take-off point, the faster the rate of rise). Normally, a stimulus introduced when repolarization has proceeded to 2/3 of the resting potential evokes a response with a rate of rise fast enough for propagation, so that the duration of the terminal 1/3 of the phase of repolarization has no influence upon the length of the effective refractory period. In the presence of quinidine, however, the rate of rise itself was directly reduced, thus repolarization had to proceed further before the critical take-off point was reached at which the rate of rise was fast enough for propagation, and the duration of the terminal phase of repolarization thus became significant. It has been concluded that

  6. The DBI Action, Higher-derivative Supergravity, and Flattening Inflaton Potentials

    CERN Document Server

    Bielleman, Sjoerd; Pedro, Francisco G; Valenzuela, Irene; Wieck, Clemens

    2016-01-01

    In string theory compactifications it is common to find an effective Lagrangian for the scalar fields with a non-canonical kinetic term. We study the effective action of the scalar position moduli of Type II D$p$-branes. In many instances the kinetic terms are in fact modified by a term proportional to the scalar potential itself. This can be linked to the appearance of higher-dimensional supersymmetric operators correcting the K\\"ahler potential. We identify the supersymmetric dimension-eight operators describing the $\\alpha'$ corrections captured by the D-brane Dirac-Born-Infeld action. Our analysis then allows an embedding of the D-brane moduli effective action into an $\\mathcal N = 1$ supergravity formulation. The effects of the potential-dependent kinetic terms may be very important if one of the scalars is the inflaton, since they lead to a flattening of the scalar potential. We analyze this flattening effect in detail and compute its impact on the CMB observables for single-field inflation with monomia...

  7. Radioprotective cerium oxide nanoparticles: Molecular imaging investigations of conps' pharmacokinetics, efficacy, and mechanisms of action

    Science.gov (United States)

    McDonagh, Philip Reed Wills, III

    Cerium oxide nanoparticles (CONPs) are being investigated for several anti-oxidant applications in medicine. One of their most promising applications is as a radioprotective drug, an area of research in need due to the severe side effects from radiation therapy. In this work, the potential of CONPs as a radioprotective drug is examined using four criteria: favorable biodistribution/pharmacokinetics, low toxicity, ability to protect normal tissue from radiation damage, and lack of protection of tumor. The mechanisms of action of CONPs are also studied. Biodistribution was determined in radiolabeled CONPs with surface coatings including citrate, dextran T10-amine (DT10-NH2), dextran T10-polyethylene glycol (DT10-PEG), dextran T10-sulfobetaine (DT10-SB) and poly(acrylic acid) (PAA), and compared to uncoated. 89Zr was incorporated into CONPs for positron emission tomography (PET) imaging and ex vivo tissue analysis in tumor bearing mice. Compared to uncoated [ 89Zr]CONPs, coated [89Zr]CONPs showed improved biodistribution, including significantly enhanced renal clearance of PAA- [89Zr]CONPs. The toxicity of CONPs was evaluated in vitro and in vivo, with low toxicity at therapeutic doses. After clinically mimetic radiation therapy, pre-treatment of mice with coated and uncoated CONPs showed greater than 50% reduction of cell death in normal colon tissue, comparable to the clinically available radioprotective drug amifostine. Tumor control after irradiation of spontaneous colon tumors was unchanged with PAA-CONP pre-treatment, while citrate, DT10-PEG, and uncoated CONP pre-treatment had slightly less tumor control. Xenograft tumors were irradiated after pH normalizing treatment with sodium bicarbonate and PAA-CONP pre-treatment. Treatment of these tumors showed slightly less tumor control than irradiation alone or PAA-CONP plus irradiation, demonstrating that the acidic pH of the tumor microenvironment may be the basis of preventing CONPs' radioprotective properties in

  8. Potentiators of Defective ΔF508-CFTR Gating that Do Not Interfere with Corrector Action.

    Science.gov (United States)

    Phuan, Puay-Wah; Veit, Guido; Tan, Joseph A; Finkbeiner, Walter E; Lukacs, Gergely L; Verkman, A S

    2015-10-01

    Combination drug therapies under development for cystic fibrosis caused by the ∆F508 mutation in cystic fibrosis transmembrane conductance regulator (CFTR) include a "corrector" to improve its cellular processing and a "potentiator" to improve its chloride channel function. Recently, it was reported that the approved potentiator N-(2,4-di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide (Ivacaftor) reduces ∆F508-CFTR cellular stability and the efficacy of investigational correctors, including 3-(6-[([1-(2,2-difluoro-1,3-benzodioxol-5-yl)cyclopropyl]carbonyl) amino]-3-methyl-2-pyridinyl)-benzoic acid and 1-(2,2-difluoro-1,3-benzodioxol-5-yl)-N-(1-[(2R)-2,3-dihydroxypropyl]-6-fluoro-2-(2-hydroxy-1,1-dimethylethyl)-1H-indol-5-yl), which might contribute to the modest reported efficacy of combination therapy in clinical trials. Here, we report the identification and characterization of potentiators that do not interfere with ∆F508-CFTR stability or corrector action. High-throughput screening and structure-activity analysis identified several classes of potentiators that do not impair corrector action, including tetrahydrobenzothiophenes, thiooxoaminothiazoles, and pyrazole-pyrrole-isoxazoles. The most potent compounds have an EC(50) for ∆F508-CFTR potentiation down to 18 nM and do not reduce corrector efficacy in heterologous ∆F508-CFTR-expressing cells or primary cultures of ∆F508/∆F508 human bronchial epithelia. The ΔF508-CFTR potentiators also activated wild-type and G551D CFTR, albeit weakly. The efficacy of combination therapy for cystic fibrosis caused by the ∆F508 mutation may be improved by replacement of Ivacaftor with a potentiator that does not interfere with corrector action. PMID:26245207

  9. Application of Emergency Action Levels from Potential Release at Research Reactor HANARO

    International Nuclear Information System (INIS)

    Execution of the protective action promptly is possible that Emergency Action Levels (EALs) must be established for a radiological release from nuclear facility. The EALs for electric power reactor are already developed and applied to recognize an emergency situation rapidly. Recently the IAEA published the safety report including the EALs for research reactor. This paper describes the EALs to apply for a potential release pathway at the research reactor HANARO. The results of table 1 and 2 will be higher than actual because the weather condition in real situation is difference. However, the EALs applying the potential stack release, ground release and site can be useful for research reactor HANARO making the emergency declaration. The EALs at the site boundary of the table 3 can be applied to protect the off-site public

  10. Bimodal action of menthol on the transient receptor potential channel TRPA1

    OpenAIRE

    Karashima, Yuji; Damann, Nils; Prenen, Jean; Talavera Pérez, Karel; Segal Stanciu, Andrei; Voets, Thomas; Nilius, Bernd

    2007-01-01

    TRPA1 is a calcium-permeable nonselective cation transient receptor potential (TRP) channel that functions as an excitatory ionotropic receptor in nociceptive neurons. TRPA1 is robustly activated by pungent substances in mustard oil, cinnamon, and garlic and mediates the inflammatory actions of environmental irritants and proalgesic agents. Here, we demonstrate a bimodal sensitivity of TRPA1 to menthol, a widely used cooling agent and known activator of the related cold receptor TRPM8. In who...

  11. Action Potential Morphology Influences Intracellular Calcium Handling Stability and the Occurrence of Alternans

    OpenAIRE

    Jordan, Peter N; Christini, David J

    2005-01-01

    Instability in the intracellular Ca2+ handling system leading to Ca2+ alternans is hypothesized to be an underlying cause of electrical alternans. The highly coupled nature of membrane voltage and Ca2+ regulation suggests that there should be reciprocal effects of membrane voltage on the stability of the Ca2+ handling system. We investigated such effects using a mathematical model of the cardiac intracellular Ca2+ handling system. We found that the morphology of the action potential has a sig...

  12. Variability of Action Potentials Within and Among Cardiac Cell Clusters Derived from Human Embryonic Stem Cells

    OpenAIRE

    Renjun Zhu; Millrod, Michal A.; Zambidis, Elias T.; Leslie Tung

    2016-01-01

    Electrophysiological variability in cardiomyocytes derived from pluripotent stem cells continues to be an impediment for their scientific and translational applications. We studied the variability of action potentials (APs) recorded from clusters of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) using high-resolution optical mapping. Over 23,000 APs were analyzed through four parameters: APD30, APD80, triangulation and fractional repolarization. Although measures were taken to re...

  13. Action Potential Energy Efficiency Varies Among Neuron Types in Vertebrates and Invertebrates

    OpenAIRE

    Biswa Sengupta; Martin Stemmler; Simon B Laughlin; Niven, Jeremy E.

    2010-01-01

    The initiation and propagation of action potentials (APs) places high demands on the energetic resources of neural tissue. Each AP forces ATP-driven ion pumps to work harder to restore the ionic concentration gradients, thus consuming more energy. Here, we ask whether the ionic currents underlying the AP can be predicted theoretically from the principle of minimum energy consumption. A long-held supposition that APs are energetically wasteful, based on theoretical analysis of the squid giant ...

  14. Variety of the Wave Change in Compound Muscle Action Potential in an Animal Model

    OpenAIRE

    ITO, ZENYA; Imagama, Shiro; Ando, Kei; Muramoto, Akio; Kobayashi, Kazuyoshi; Hida, Tetsuro; Ito, Kenyu; Ishikawa, Yoshimoto; Tsushima, Mikito; Matsumoto, Akiyuki; Tanaka, Satoshi; Morozumi, Masayoshi; Matsuyama, Yukihiro; Ishiguro, Naoki

    2015-01-01

    Study Design Animal study. Purpose To review the present warning point criteria of the compound muscle action potential (CMAP) and investigate new criteria for spinal surgery safety using an animal model. Overview of Literature Little is known about correlation palesis and amplitude of spinal cord monitoring. Methods After laminectomy of the tenth thoracic spinal lamina, 2-140 g force was delivered to the spinal cord with a tension gage to create a bilateral contusion injury. The study morpho...

  15. Comparative investigations of manual action representations: evidence that chimpanzees represent the costs of potential future actions involving tools

    OpenAIRE

    Frey, Scott H.; POVINELLI, DANIEL J.

    2012-01-01

    The ability to adjust one's ongoing actions in the anticipation of forthcoming task demands is considered as strong evidence for the existence of internal action representations. Studies of action selection in tool use reveal that the behaviours that we choose in the present moment differ depending on what we intend to do next. Further, they point to a specialized role for mechanisms within the human cerebellum and dominant left cerebral hemisphere in representing the likely sensory costs of ...

  16. Magnetic Imaging of Applied and Propagating Action Currents in Cardiac Tissue Slices: Determination of Anisotropic Electrical Conductivities in a Two-Dimensional Bidomain.

    Science.gov (United States)

    Staton, Daniel Joseph

    We describe the first, high-resolution magnetic images of applied currents and propagating action currents in slices of canine cardiac tissue. This tissue was maintained in vitro at 37^circC. Our main conclusions are summarized as follows: the action currents produce magnetic fields which are measurable; during the initial stages of the propagating action potential, small, expanding, quatrefoil loops of current develop; the magnetic fields produced by repolarization currents are larger than previously anticipated. Most of the current associated with the propagating action potential is confined within the wavefront and should be magnetically silent; however, differences in the intracellular and extracellular electrical conductivities, in both the longitudinal and transverse fiber directions, are great enough that expanding quatrefoil current densities are associated with the wavefront and produce measurable magnetic fields. Since action currents are affected by the electrical conductivities, it is of interest to determine their values, which depend not only upon the tissue characteristics, but also on the mathematical model used to interpret the measured data. In our analysis of current injection, we use the anisotropic bidomain model which incorporates a passive, linear membrane. We introduce theoretical techniques to calculate the anisotropic conductivities of a two-dimensional bidomain. To apply these techniques to magnetic fields resulting from current injection into cardiac tissue slices, we need to improve the higher spatial frequency content of our present measurements. This may be done by measuring the magnetic field closer to the cardiac slice (presently 2.5 mm), decreasing the sampling interval of the measurement, and increasing the sampling area of the field. Magnetic fields are produced by propagating action currents, which are in turn the result of the propagating action potential. From the magnetic field, we directly image isochronal transmembrane

  17. Noisy unmaskers of multistability of periodic rhythms in a model of the ventricular cardiac action potential

    Science.gov (United States)

    Surovyatkina, Elena; Egorchenkov, Roman; Ivanov, Guennady

    2007-06-01

    The coexistence of different dynamical regimes of cardiac cell-model at a fixed set of stimulation parameters, i.e. multistability, revealed by noise is presented in this paper. Numerical simulations are performed using Luo-Rudy (LR1) action potential model. Numerical experiments with LR1 model conducted via noisy periodical stimulation showed the coexistence of several periodic rhythms. Weak noise in period of stimulation causes a hopping process between all the (meta-) stable rhythms of cell-model. This process is reflected in several parallel branches of the bifurcation diagram: noise unveils new, invisible before, stable rhythms which could appear in this model at different initial conditions. The phenomenon of multistability is directly evidenced by other numerical experiments: we have established the multistability property of a cell consisting in the fact that different initial conditions of stimulation (different extrasystole application times) lead to different stable periodic rhythms. We have obtained the shaping of attraction basins on the action potential curves. Such basins of attraction contain a set of initial conditions which determinate a stable periodic rhythm. We have found a close association between the attraction basins of the complex rhythms on the curves of action potential and the cardiac vulnerable windows on ECG record, during which extra stimuli can induce life threatening arrhythmias. Obtained results allow us to make a conclusion that multistability is very important for the electrical conduction system of the heart from the cell level to the integrated function of the heart.

  18. ER Stress-Mediated Signaling: Action Potential and Ca2+ as Key Players

    Science.gov (United States)

    Bahar, Entaz; Kim, Hyongsuk; Yoon, Hyonok

    2016-01-01

    The proper functioning of the endoplasmic reticulum (ER) is crucial for multiple cellular activities and survival. Disturbances in the normal ER functions lead to the accumulation and aggregation of unfolded proteins, which initiates an adaptive response, the unfolded protein response (UPR), in order to regain normal ER functions. Failure to activate the adaptive response initiates the process of programmed cell death or apoptosis. Apoptosis plays an important role in cell elimination, which is essential for embryogenesis, development, and tissue homeostasis. Impaired apoptosis can lead to the development of various pathological conditions, such as neurodegenerative and autoimmune diseases, cancer, or acquired immune deficiency syndrome (AIDS). Calcium (Ca2+) is one of the key regulators of cell survival and it can induce ER stress-mediated apoptosis in response to various conditions. Ca2+ regulates cell death both at the early and late stages of apoptosis. Severe Ca2+ dysregulation can promote cell death through apoptosis. Action potential, an electrical signal transmitted along the neurons and muscle fibers, is important for conveying information to, from, and within the brain. Upon the initiation of the action potential, increased levels of cytosolic Ca2+ (depolarization) lead to the activation of the ER stress response involved in the initiation of apoptosis. In this review, we discuss the involvement of Ca2+ and action potential in ER stress-mediated apoptosis. PMID:27649160

  19. Compound action potentials recorded in the human spinal cord during neurostimulation for pain relief.

    Science.gov (United States)

    Parker, John L; Karantonis, Dean M; Single, Peter S; Obradovic, Milan; Cousins, Michael J

    2012-03-01

    Electrical stimulation of the spinal cord provides effective pain relief to hundreds of thousands of chronic neuropathic pain sufferers. The therapy involves implantation of an electrode array into the epidural space of the subject and then stimulation of the dorsal column with electrical pulses. The stimulation depolarises axons and generates propagating action potentials that interfere with the perception of pain. Despite the long-term clinical experience with spinal cord stimulation, the mechanism of action is not understood, and no direct evidence of the properties of neurons being stimulated has been presented. Here we report novel measurements of evoked compound action potentials from the spinal cords of patients undergoing stimulation for pain relief. The results reveal that Aβ sensory nerve fibres are recruited at therapeutic stimulation levels and the Aβ potential amplitude correlates with the degree of coverage of the painful area. Aβ-evoked responses are not measurable below a threshold stimulation level, and their amplitude increases with increasing stimulation current. At high currents, additional late responses are observed. Our results contribute towards efforts to define the mechanism of spinal cord stimulation. The minimally invasive recording technique we have developed provides data previously obtained only through microelectrode techniques in spinal cords of animals. Our observations also allow the development of systems that use neuronal recording in a feedback loop to control neurostimulation on a continuous basis and deliver more effective pain relief. This is one of numerous benefits that in vivo electrophysiological recording can bring to a broad range of neuromodulation therapies. PMID:22188868

  20. Features of undiagnosed breast cancers at screening breast MR imaging and potential utility of computer-aided evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Mirinae; Cho, Nariya; Bea, Min Sun; Koo, Hye Ryoung; Kim, Won Hwa; Lee, Su Hyun; Chu, A Jung [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of)

    2016-02-15

    To retrospectively evaluate the features of undiagnosed breast cancers on prior screening breast magnetic resonance (MR) images in patients who were subsequently diagnosed with breast cancer, as well as the potential utility of MR-computer-aided evaluation (CAE). Between March 2004 and May 2013, of the 72 consecutive pairs of prior negative MR images and subsequent MR images with diagnosed cancers (median interval, 32.8 months; range, 5.4-104.6 months), 36 (50%) had visible findings (mean size, 1.0 cm; range, 0.3-5.2 cm). The visible findings were divided into either actionable or under threshold groups by the blinded review by 5 radiologists. MR imaging features, reasons for missed cancer, and MR-CAE features according to actionability were evaluated. Of the 36 visible findings on prior MR images, 33.3% (12 of 36) of the lesions were determined to be actionable and 66.7% (24 of 36) were underthreshold; 85.7% (6 of 7) of masses and 31.6% (6 of 19) of non-mass enhancements were classified as actionable lesions. Mimicking physiologic enhancements (27.8%, 10 of 36) and small lesion size (27.8%, 10 of 36) were the most common reasons for missed cancer. Actionable findings tended to show more washout or plateau kinetic patterns on MR-CAE than underthreshold findings, as the 100% of actionable findings and 46.7% of underthreshold findings showed washout or plateau (p = 0.008). MR-CAE has the potential for reducing the number of undiagnosed breast cancers on screening breast MR images, the majority of which are caused by mimicking physiologic enhancements or small lesion size.

  1. Detection of potential mosquito breeding sites based on community sourced geotagged images

    Science.gov (United States)

    Agarwal, Ankit; Chaudhuri, Usashi; Chaudhuri, Subhasis; Seetharaman, Guna

    2014-06-01

    Various initiatives have been taken all over the world to involve the citizens in the collection and reporting of data to make better and informed data-driven decisions. Our work shows how the geotagged images collected through the general population can be used to combat Malaria and Dengue by identifying and visualizing localities that contain potential mosquito breeding sites. Our method first employs image quality assessment on the client side to reject the images with distortions like blur and artifacts. Each geotagged image received on the server is converted into a feature vector using the bag of visual words model. We train an SVM classifier on a histogram-based feature vector obtained after the vector quantization of SIFT features to discriminate images containing either a small stagnant water body like puddle, or open containers and tires, bushes etc. from those that contain flowing water, manicured lawns, tires attached to a vehicle etc. A geographical heat map is generated by assigning a specific location a probability value of it being a potential mosquito breeding ground of mosquito using feature level fusion or the max approach presented in the paper. The heat map thus generated can be used by concerned health authorities to take appropriate action and to promote civic awareness.

  2. Antibacterial free fatty acids: activities, mechanisms of action and biotechnological potential.

    Science.gov (United States)

    Desbois, Andrew P; Smith, Valerie J

    2010-02-01

    Amongst the diverse and potent biological activities of free fatty acids (FFAs) is the ability to kill or inhibit the growth of bacteria. The antibacterial properties of FFAs are used by many organisms to defend against parasitic or pathogenic bacteria. Whilst their antibacterial mode of action is still poorly understood, the prime target of FFA action is the cell membrane, where FFAs disrupt the electron transport chain and oxidative phosphorylation. Besides interfering with cellular energy production, FFA action may also result from the inhibition of enzyme activity, impairment of nutrient uptake, generation of peroxidation and auto-oxidation degradation products or direct lysis of bacterial cells. Their broad spectrum of activity, non-specific mode of action and safety makes them attractive as antibacterial agents for various applications in medicine, agriculture and food preservation, especially where the use of conventional antibiotics is undesirable or prohibited. Moreover, the evolution of inducible FFA-resistant phenotypes is less problematic than with conventional antibiotics. The potential for commercial or biomedical exploitation of antibacterial FFAs, especially for those from natural sources, is discussed.

  3. An Excel-based implementation of the spectral method of action potential alternans analysis.

    Science.gov (United States)

    Pearman, Charles M

    2014-12-01

    Action potential (AP) alternans has been well established as a mechanism of arrhythmogenesis and sudden cardiac death. Proper interpretation of AP alternans requires a robust method of alternans quantification. Traditional methods of alternans analysis neglect higher order periodicities that may have greater pro-arrhythmic potential than classical 2:1 alternans. The spectral method of alternans analysis, already widely used in the related study of microvolt T-wave alternans, has also been used to study AP alternans. Software to meet the specific needs of AP alternans analysis is not currently available in the public domain. An AP analysis tool is implemented here, written in Visual Basic for Applications and using Microsoft Excel as a shell. This performs a sophisticated analysis of alternans behavior allowing reliable distinction of alternans from random fluctuations, quantification of alternans magnitude, and identification of which phases of the AP are most affected. In addition, the spectral method has been adapted to allow detection and quantification of higher order regular oscillations. Analysis of action potential morphology is also performed. A simple user interface enables easy import, analysis, and export of collated results.

  4. Population of Computational Rabbit-Specific Ventricular Action Potential Models for Investigating Sources of Variability in Cellular Repolarisation

    OpenAIRE

    Philip Gemmell; Kevin Burrage; Blanca Rodriguez; T Alexander Quinn

    2014-01-01

    Variability is observed at all levels of cardiac electrophysiology. Yet, the underlying causes and importance of this variability are generally unknown, and difficult to investigate with current experimental techniques. The aim of the present study was to generate populations of computational ventricular action potential models that reproduce experimentally observed intercellular variability of repolarisation (represented by action potential duration) and to identify its potential causes. A s...

  5. Hyperpolarized Renal Magnetic Resonance Imaging: Potential and Pitfalls

    Directory of Open Access Journals (Sweden)

    Christoffer eLaustsen

    2016-03-01

    Full Text Available The introduction of dissolution dynamic nuclear polarization (d-DNP technology has enabled a new paradigm for renal imaging investigations. It allows standard magnetic resonance imaging complementary renal metabolic and functional fingerprints within seconds without the use of ionizing radiation. Increasing evidence supports its utility in preclinical research in which the real-time interrogation of metabolic turnover can aid the physiological and pathophysiological metabolic and functional effects in ex vivo and in vivo models. The method has already been translated to humans, although the clinical value of this technology is unknown. In this paper, I review the potential benefits and pitfalls associated with dissolution dynamic nuclear polarization in preclinical research and its translation to renal patients.

  6. Effects of terpineol on the compound action potential of the rat sciatic nerve

    OpenAIRE

    M.R. Moreira; G.M.P. Cruz; Lopes, M S; A.A.C. Albuquerque; J.H. Leal-Cardoso

    2001-01-01

    Terpineol, a volatile terpenoid alcohol of low toxicity, is widely used in the perfumery industry. It is an important chemical constituent of the essential oil of many plants with widespread applications in folk medicine and in aromatherapy. The effects of terpineol on the compound action potential (CAP) of rat sciatic nerve were studied. Terpineol induced a dose-dependent blockade of the CAP. At 100 µM, terpineol had no demonstrable effect. At 300 µM terpineol, peak-to-peak amplitude and con...

  7. Effects of Potassium Currents upon Action Potential of Cardiac Cells Exposed to External Electric fields

    Institute of Scientific and Technical Information of China (English)

    An-Ying Zhang; Xiao-Feng Pang

    2008-01-01

    Previous studies show that exposure to high-voltage electric fields would influence the electro cardiogram both in experimental animate and human beings. The effects of the external electric fields upon action potential of cardiac cells are studied in this paper based on the dynamical model, LR91. Fourth order Runger-Kuta is used to analyze the change of potassium ion channels exposed to external electric fields in detail. Results indicate that external electric fields could influence the current of potassium ion by adding an induced component voltage on membrane. This phenomenon might be one of the reasons of heart rate anomaly under the high-voltage electric fields.

  8. On modelling of physical effects accompanying the propagation of action potentials in nerve fibres

    CERN Document Server

    Engelbrecht, Jüri; Tamm, Kert; Laasmaa, Martin; Vendelin, Marko

    2016-01-01

    The recent theoretical and experimental studies have revealed many details of signal propagation in nervous systems. In this paper an attempt is made to unify various mathematical models which describe the signal propagation in nerve fibres. The analysis of existing single models permits to select the leading physiological effects. As a result, a more general mathematical model is described based on the coupling of action potentials with mechanical waves in a nerve fibre. The crucial issue is how to model coupling effects which are strongly linked to the ion currents through biomembranes.

  9. The optimal distance between two electrode tips during recording of compound nerve action potentials in the rat median nerve

    Institute of Scientific and Technical Information of China (English)

    Yongping Li; Jie Lao; Xin Zhao; Dong Tian; Yi Zhu; Xiaochun Wei

    2014-01-01

    The distance between the two electrode tips can greatly inlfuence the parameters used for record-ing compound nerve action potentials. To investigate the optimal parameters for these recordings in the rat median nerve, we dissociated the nerve using different methods and compound nerve action potentials were orthodromically or antidromically recorded with different electrode spac-ings. Compound nerve action potentials could be consistently recorded using a method in which the middle part of the median nerve was intact, with both ends dissociated from the surrounding fascia and a ground wire inserted into the muscle close to the intact part. When the distance be-tween two stimulating electrode tips was increased, the threshold and supramaximal stimulating intensity of compound nerve action potentials were gradually decreased, but the amplitude was not changed signiifcantly. When the distance between two recording electrode tips was increased, the amplitude was gradually increased, but the threshold and supramaximal stimulating intensity exhibited no signiifcant change. Different distances between recording and stimulating sites did not produce signiifcant effects on the aforementioned parameters. A distance of 5 mm between recording and stimulating electrodes and a distance of 10 mm between recording and stimulating sites were found to be optimal for compound nerve action potential recording in the rat median nerve. In addition, the orthodromic compound action potential, with a biphasic waveform that was more stable and displayed less interference (however also required a higher threshold and higher supramaximal stimulus), was found to be superior to the antidromic compound action potential.

  10. Characterization of action potential-triggered [Ca2+]i transients in single smooth muscle cells of guinea-pig ileum

    OpenAIRE

    Kohda, M.; Komori, S.; Unno, T; Ohashi, H

    1997-01-01

    To characterize increases in cytosolic free Ca2+ concentration ([Ca2+]i) associated with discharge of action potentials, membrane potential and [Ca2+]i were simultaneously recorded from single smooth muscle cells of guinea-pig ileum by use of a combination of nystatin-perforated patch clamp and fura-2 fluorimetry techniques.A single action potential in response to a depolarizing current pulse elicited a transient rise in [Ca2+]i. When the duration of the current pulse was prolonged, action po...

  11. Three-dimensional mapping and regulation of action potential propagation in nanoelectronics-innervated tissues

    Science.gov (United States)

    Dai, Xiaochuan; Zhou, Wei; Gao, Teng; Liu, Jia; Lieber, Charles M.

    2016-09-01

    Real-time mapping and manipulation of electrophysiology in three-dimensional (3D) tissues could have important impacts on fundamental scientific and clinical studies, yet realization is hampered by a lack of effective methods. Here we introduce tissue-scaffold-mimicking 3D nanoelectronic arrays consisting of 64 addressable devices with subcellular dimensions and a submillisecond temporal resolution. Real-time extracellular action potential (AP) recordings reveal quantitative maps of AP propagation in 3D cardiac tissues, enable in situ tracing of the evolving topology of 3D conducting pathways in developing cardiac tissues and probe the dynamics of AP conduction characteristics in a transient arrhythmia disease model and subsequent tissue self-adaptation. We further demonstrate simultaneous multisite stimulation and mapping to actively manipulate the frequency and direction of AP propagation. These results establish new methodologies for 3D spatiotemporal tissue recording and control, and demonstrate the potential to impact regenerative medicine, pharmacology and electronic therapeutics.

  12. Action of hallucinogens on raphe-evoked dorsal root potentials (DRPs) in the cat.

    Science.gov (United States)

    Larson, A A; Anderson, E G

    1986-02-01

    The dorsal root potential (DRP) evoked by stimulation of the inferior central nucleus (ICN) of the cat is affected by administration of a variety of hallucinogenic agents. It has been previously shown that a single low dose of LSD is unique in that it potentiates this DRP, while injections of 5-methoxy-N,N- dimethyltryptamine (5-MeODMT), ketamine or phencyclidine (PCP) inhibit its production. Tolerance develops to the facilitatory effect of low doses of LSD on the DRP, but not to the inhibitory action of 5-MeODMT. Repeated injections of ketamine every 30 minutes also fail to produce tachyphylaxis to the inhibitory effect of this dissociative anesthetic. The raphe-evoked DRP is a long latency potential that is inhibited by a wide variety of putative serotonin antagonists and has therefore been traditionally thought to be mediated by serotonin. However, in light of the inability of either tryptophan or fluoxetine to potentiate this DRP, and the resistance of this DRP to blockade by parachlorophenylalanine, reserpine or intrathecally administered 5,7-dihydroxytryptamine, it appears that this potential may in fact be mediated, at least in part, by a non-serotonergic transmitter. PMID:3952125

  13. Potential pitfalls of strain rate imaging: angle dependency

    Science.gov (United States)

    Castro, P. L.; Greenberg, N. L.; Drinko, J.; Garcia, M. J.; Thomas, J. D.

    2000-01-01

    Strain Rate Imaging (SRI) is a new echocardiographic technique that allows for the real-time determination of myocardial SR, which may be used for the early and accurate detection of coronary artery disease. We sought to study whether SR is affected by scan line alignment in a computer simulation and an in vivo experiment. Through the computer simulation and the in vivo experiment we generated and validated safe scanning sectors within the ultrasound scan sector and showed that while SRI will be an extremely valuable tool in detecting coronary artery disease there are potential pitfalls for the unwary clinician. Only after accounting for these affects due to angle dependency, can clinicians utilize SRI's potential as a valuable tool in detecting coronary artery disease.

  14. The characteristics of action potential and nonselective cation current of cardiomyocytes in rabbit superior vena cava

    Institute of Scientific and Technical Information of China (English)

    WANG Pan; YANG XinChun; LIU XiuLan; BAO RongFeng; LIU TaiFeng

    2008-01-01

    As s special focus in initiating and maintaining atrial fibrillation (AF), cardiomyocytes in superior vena cavs (SVC) have distinctive electrophysiological characters. In this study, we found that comparing with the right atrial (RA) cardiomyoctyes, the SVC cardiomyoctyes had longer APD90 at the different basic cycle lengths; the conduction block could be observed on both RA and SVC cardiomyoctyes. A few of SVC cardiomyoctyes showed slow response action potentials with automatic activity and some others showed early afterdepolarization (EAD) spontaneously. Further more, we found that there are nonselective cation current (INs) in both SVC and RA cardiomyocytes. The peak density of INs in SVC cardiomyocytes was smaller than that in RA cardiomyocytes. Removal of extracellular divalent cation and glucose could increase INs in SVC cardiomyocytes. The agonist or the antagonist of INs may increase or decrease APD. To sum up, some SVC cardiomyocytes possess the ability of spontaneous activity; the difference of transmembrane action potentials between SVC and RA cardiomyocytes is partly because of the different density of INs between them; the agonist or the antagonist of INs can increase or decrease APD leading to the enhancement or reduction of EAD genesis in SVC cardiomyocytes. INs in rabbit myocytes is fairly similar to TRPC3 current in electrophysiological property, which might play an important role in the mechanisms of AF.

  15. Potassium conductances mediate bidirectional state-dependent modulation of action potential evoked dendritic calcium signals in dentate gyrus granule cells

    Directory of Open Access Journals (Sweden)

    János Brunner

    2014-03-01

    Full Text Available Backpropagating action potentials (bAPs and local calcium signals that they trigger are fundamental for dendritic functions. Here we addressed the question what extent the changes of local dendritic membrane properties can contribute to the shaping of the coupling between dendritic action potentials and the local calcium responses. Using a combination of in vitro electrophysiological and confocal imaging techniques we found that activation of dendritic GIRK channels via mGlu2 or GABAB receptors enhanced the bAP¬-triggered calcium signals in the dendrites of dentate gyrus granule cells (GCs. The enhancement of calcium signals was significant only in those dendritic regions, where these receptors are predominantly expressed. Similarly to GIRK channel activation, somatic hyperpolarization by DC current injection (from -64 mV to -77 mV, significantly increased bAP-associated calcium signals in the proximal dendrites. The hyperpolarization was associated with a decrease in the input resistance due to the rectification of the membrane potential of GCs. The effect of hyperpolarization on the calcium signals was maintained when T-type calcium currents were blocked but it decreased when GIRK channels were inhibited. Simultaneous dual somato-dendritic recordings from GCs showed that somatic hyperpolarization accelerated the repolarization phase of dendritic bAP in the proximal region whereas the rising phase and peak amplitude was not affected. We hypothesize that the larger driving force for calcium ions during the faster repolarization can contribute to the increasing in calcium signals. Employment of previously recorded dendritic bAP waveforms from hyperpolarized membrane potential as voltage command evoked larger calcium currents in nucleated patches compared to bAP waveform from the same recording at depolarized membrane potential. Furthermore, addition of native, high-voltage activated, inactivating potassium conductance by somatic dynamic clamp

  16. Urocortin2 prolongs action potential duration and modulates potassium currents in guinea pig myocytes and HEK293 cells.

    Science.gov (United States)

    Yang, Li-Zhen; Zhu, Yi-Chun

    2015-07-01

    We previously reported that activation of corticotropin releasing factor receptor type 2 by urocortin2 up-regulates both L-type Ca(2+) channels and intracellular Ca(2+) concentration in ventricular myocytes and plays an important role in cardiac contractility and arrhythmogenesis. This study goal was to further test the hypothesis that urocortin2 may modulate action potentials as well as rapidly and slowly activating delayed rectifier potassium currents. With whole cell patch-clamp techniques, action potentials and slowly activating delayed rectifier potassium currents were recorded in isolated guinea pig ventricular myocytes, respectively. And rapidly activating delayed rectifier potassium currents were tested in hERG-HEK293 cells. Urocortin2 produced a time- and concentration-dependent prolongation of action potential duration. The EC50 values of action potential duration and action potential duration at 90% of repolarization were 14.73 and 24.3nM respectively. The prolongation of action potential duration of urocortin2 was almost completely or partly abolished by H-89 (protein kinase A inhibitor) or KB-R7943 (Na(+)/Ca(2+) exchange inhibitor) pretreatment respectively. And urocortin2 caused reduction of rapidly activating delayed rectifier potassium currents in hERG-HEK293 cells. In addition, urocortin2 slowed the rate of slowly activating delayed rectifier potassium channel activation, and rightward shifted the threshold of slowly activating delayed rectifier potassium currents to more positive potentials. Urocortin2 prolonged action potential duration via activation of protein kinase A and Na(+)/ Ca(2+) exchange in isolated guinea pig ventricular myocytes in a time- and concentration- dependent manner. In hERG-HEK293 cells, urocortin2 reduced rapidly activating delayed rectifier potassium current density which may contribute to action potential duration prolongation.

  17. Regulation of action potential waveforms by axonal GABAA receptors in cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Yang Xia

    Full Text Available GABAA receptors distributed in somatodendritic compartments play critical roles in regulating neuronal activities, including spike timing and firing pattern; however, the properties and functions of GABAA receptors at the axon are still poorly understood. By recording from the cut end (bleb of the main axon trunk of layer -5 pyramidal neurons in prefrontal cortical slices, we found that currents evoked by GABA iontophoresis could be blocked by picrotoxin, indicating the expression of GABAA receptors in axons. Stationary noise analysis revealed that single-channel properties of axonal GABAA receptors were similar to those of somatic receptors. Perforated patch recording with gramicidin revealed that the reversal potential of the GABA response was more negative than the resting membrane potential at the axon trunk, suggesting that GABA may hyperpolarize the axonal membrane potential. Further experiments demonstrated that the activation of axonal GABAA receptors regulated the amplitude and duration of action potentials (APs and decreased the AP-induced Ca2+ transients at the axon. Together, our results indicate that the waveform of axonal APs and the downstream Ca2+ signals are modulated by axonal GABAA receptors.

  18. Ventricular filling slows epicardial conduction and increases action potential duration in an optical mapping study of the isolated rabbit heart

    Science.gov (United States)

    Sung, Derrick; Mills, Robert W.; Schettler, Jan; Narayan, Sanjiv M.; Omens, Jeffrey H.; McCulloch, Andrew D.; McCullough, A. D. (Principal Investigator)

    2003-01-01

    INTRODUCTION: Mechanical stimulation can induce electrophysiologic changes in cardiac myocytes, but how mechanoelectric feedback in the intact heart affects action potential propagation remains unclear. METHODS AND RESULTS: Changes in action potential propagation and repolarization with increased left ventricular end-diastolic pressure from 0 to 30 mmHg were investigated using optical mapping in isolated perfused rabbit hearts. With respect to 0 mmHg, epicardial strain at 30 mmHg in the anterior left ventricle averaged 0.040 +/- 0.004 in the muscle fiber direction and 0.032 +/- 0.006 in the cross-fiber direction. An increase in ventricular loading increased average epicardial activation time by 25%+/- 3% (P action potential duration at 20% repolarization (APD20) but did at 80% repolarization (APD80), from 179 +/- 7 msec to 207 +/- 5 msec (P action potential duration by a load-dependent mechanism that may not involve stretch-activated channels.

  19. The Belem Framework for Action: Harnessing the Power and Potential of Adult Learning and Education for a Viable Future

    Science.gov (United States)

    Adult Learning, 2012

    2012-01-01

    This article presents the Belem Framework for Action. This framework focuses on harnessing the power and potential of adult learning and education for a viable future. This framework begins with a preamble on adult education and towards lifelong learning.

  20. Chitosan oligosaccharide based Gd-DTPA complex as a potential bimodal magnetic resonance imaging contrast agent.

    Science.gov (United States)

    Huang, Yan; Cao, Juan; Zhang, Qi; Lu, Zheng-rong; Hua, Ming-qing; Zhang, Xiao-yan; Gao, Hu

    2016-01-01

    A new gadolinium diethylenetriamine pentaacetic acid (DTPA) complex (Gd-DTPA-DMABA-CS11) as a potential bimodal magnetic resonance imaging (MRI) contrast agent with fluorescence was synthesized. It was synthesized by the incorporation of 4-dimethylaminobenzaldehyde (DMABA) and chitosan oligosaccharide (CSn; n=11) with low polydispersity index to DTPA anhydride and then chelated with gadolinium chloride. The structure was characterized by Fourier transform infrared (FTIR), (1)H NMR, elemental analysis and size exclusion chromatography (SEC). MRI measurements in vitro were evaluated. The results indicated that Gd-DTPA-DMABA-CS11 provided higher molar longitudinal relaxivity (r1) (12.95mM(-1)·s(-1)) than that of commercial Gd-DTPA (3.63mM(-1)·s(-1)) at 0.5T. Gd-DTPA-DMABA-CS11 also emitted fluorescence, and the intensity was much stronger than that of Gd-DTPA. Therefore, it can be meanwhile used in fluorescent imaging for improving the sensitivity in clinic diagnosis. Gd-DTPA-DMABA-CS11 as a potential contrast agent is preliminarily stable in vitro. The results of thermodynamic action between Gd-DTPA-DMABA-CS11 and bovine serum albumin (BSA) illustrated that the binding process was exothermic and spontaneous, and the main force was van der Waals' interaction and hydrogen bond. The preliminary study suggested that Gd-DTPA-DMABA-CS11 could be used in both magnetic resonance and fluorescent imaging as a promising bimodal contrast agent.

  1. Action potential-simulated weak electric fields can directly initiate myelination

    Institute of Scientific and Technical Information of China (English)

    Lei Liu; Shifu Zhao; Haiming Wang

    2008-01-01

    BACKGROUND: Myelination is a process whereby glial cells identify, adhere, wrap and enclose axons to form a spiral myelin sheath.OBJECTIVE: To investigate the effects of action potential-simulated weak electric fields on myelination in the central nervous system.DESIGN AND SETTING: This single-sample observation study was performed at the 324 Hospital of Chinese PLA.MATERIALS: Two 5 μm carbon fibers were provided by the Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. One Sprague Dawley rat, aged 1 day, was used.METHODS: Cerebral cortex was harvested from the rat to prepare a suspension [(1-2)×105/mL] containing neurons and glial cells. To simulate the axon, carbon fibers were placed at the bottom of the neuron-glial cell coculture dish, and were electrified with a single phase square wave current, 1×10-2, 1×10-3, 1×10-4, and 1×10-5 seconds, 1 Hz, 40 mV, and 10 μA, 30 minutes each, once aday for 10 consecutive days to simulate weak negative electric fields during action potential conduction.MAIN OUTCOME MEASURES: Glial cell growth and wrapping of carbon fibers were observed by phase contrast microscopy and immunohistochemistry.RESULTS: On culture day 7, cell groups were found to adhere to negative carbon fibers in the 1×10-3 seconds square wave group. Cell membrane-like substances grew out of cell groups, wrapped the carbon fibers, and stretched to the ends of carbon fibers. Only some small and round cells close to negative carbon fibers were found on culture day 12. In the 1×10-4 and 1×10-3 seconds square wave groups, the negative carbon fibers were wrapped by oligodendrocytes or their progenitor cells.CONCLUSION: The local negative electric field which is generated by action potentials at 1×(10-4-10-3)seconds, 40 mV can directly initiate and participate in myelination in the central nervous system.

  2. Intracellular recordings of action potentials by an extracellular nanoscale field-effect transistor

    Science.gov (United States)

    Duan, Xiaojie; Gao, Ruixuan; Xie, Ping; Cohen-Karni, Tzahi; Qing, Quan; Choe, Hwan Sung; Tian, Bozhi; Jiang, Xiaocheng; Lieber, Charles M.

    2012-03-01

    The ability to make electrical measurements inside cells has led to many important advances in electrophysiology. The patch clamp technique, in which a glass micropipette filled with electrolyte is inserted into a cell, offers both high signal-to-noise ratio and temporal resolution. Ideally, the micropipette should be as small as possible to increase the spatial resolution and reduce the invasiveness of the measurement, but the overall performance of the technique depends on the impedance of the interface between the micropipette and the cell interior, which limits how small the micropipette can be. Techniques that involve inserting metal or carbon microelectrodes into cells are subject to similar constraints. Field-effect transistors (FETs) can also record electric potentials inside cells, and because their performance does not depend on impedance, they can be made much smaller than micropipettes and microelectrodes. Moreover, FET arrays are better suited for multiplexed measurements. Previously, we have demonstrated FET-based intracellular recording with kinked nanowire structures, but the kink configuration and device design places limits on the probe size and the potential for multiplexing. Here, we report a new approach in which a SiO2 nanotube is synthetically integrated on top of a nanoscale FET. This nanotube penetrates the cell membrane, bringing the cell cytosol into contact with the FET, which is then able to record the intracellular transmembrane potential. Simulations show that the bandwidth of this branched intracellular nanotube FET (BIT-FET) is high enough for it to record fast action potentials even when the nanotube diameter is decreased to 3 nm, a length scale well below that accessible with other methods. Studies of cardiomyocyte cells demonstrate that when phospholipid-modified BIT-FETs are brought close to cells, the nanotubes can spontaneously penetrate the cell membrane to allow the full-amplitude intracellular action potential to be

  3. A potential mode of action for Anakinra in patients with arthrofibrosis following total knee arthroplasty.

    Science.gov (United States)

    Dixon, David; Coates, Jonathon; del Carpio Pons, Alicia; Horabin, Joanna; Walker, Andrew; Abdul, Nicole; Kalson, Nicholas S; Brewster, Nigel T; Weir, David J; Deehan, David J; Mann, Derek A; Borthwick, Lee A

    2015-01-01

    Arthrofibrosis is a fibroproliferative disease characterised by excessive deposition of extracellular matrix components intra-articularly leading to pain and restricted range of movement. Although frequently observed following total knee arthroplasty (TKA) no therapeutic options exist. A pilot study demonstrated that intra-articular injection of Anakinra, an IL-1R antagonist, improved range of movement and pain in patients with arthrofibrosis however the mechanism of action is unknown. We hypothesise that IL-1α/β will drive an inflammatory phenotype in fibroblasts isolated from the knee, therefore identifying a potential mechanism of action for Anakinra in arthrofibrosis following TKA. Fibroblasts isolated from synovial membranes and infra-patellar fat pad of patients undergoing TKA express high levels of IL-1R1. Stimulation with IL-1α/β induced a pro-inflammatory phenotype characterised by increased secretion of GMCSF, IL-6 and IL-8. No significant difference in the inflammatory response was observed between fibroblasts isolated from synovial membrane or infra-patellar fat pad. IL-1α/β treatments induced a pro-inflammatory phenotype in fibroblasts from both synovial membrane and infra-patellar fat pad and therefore Anakinra can likely have an inhibitory effect on fibroblasts present in both tissues in vivo. It is also likely that fibroblast responses in the tissues are controlled by IL-1α/β availability and not their ability to respond to it. PMID:26553966

  4. Cancer Driver Log (CanDL): Catalog of Potentially Actionable Cancer Mutations.

    Science.gov (United States)

    Damodaran, Senthilkumar; Miya, Jharna; Kautto, Esko; Zhu, Eliot; Samorodnitsky, Eric; Datta, Jharna; Reeser, Julie W; Roychowdhury, Sameek

    2015-09-01

    Massively parallel sequencing technologies have enabled characterization of genomic alterations across multiple tumor types. Efforts have focused on identifying driver mutations because they represent potential targets for therapy. However, because of the presence of driver and passenger mutations, it is often challenging to assign the clinical relevance of specific mutations observed in patients. Currently, there are multiple databases and tools that provide in silico assessment for potential drivers; however, there is no comprehensive resource for mutations with functional characterization. Therefore, we created an expert-curated database of potentially actionable driver mutations for molecular pathologists to facilitate annotation of cancer genomic testing. We reviewed scientific literature to identify variants that have been functionally characterized in vitro or in vivo as driver mutations. We obtained the chromosome location and all possible nucleotide positions for each amino acid change and uploaded them to the Cancer Driver Log (CanDL) database with associated literature reference indicating functional driver evidence. In addition to a simple interface, the database allows users to download all or selected genes as a comma-separated values file for incorporation into their own analysis pipeline. Furthermore, the database includes a mechanism for third-party contributions to support updates for novel driver mutations. Overall, this freely available database will facilitate rapid annotation of cancer genomic testing in molecular pathology laboratories for mutations. PMID:26320871

  5. Electrophysiological Motor Unit Number Estimation (MUNE) Measuring Compound Muscle Action Potential (CMAP) in Mouse Hindlimb Muscles.

    Science.gov (United States)

    Arnold, W David; Sheth, Kajri A; Wier, Christopher G; Kissel, John T; Burghes, Arthur H; Kolb, Stephen J

    2015-01-01

    Compound muscle action potential (CMAP) and motor unit number estimation (MUNE) are electrophysiological techniques that can be used to monitor the functional status of a motor unit pool in vivo. These measures can provide insight into the normal development and degeneration of the neuromuscular system. These measures have clear translational potential because they are routinely applied in diagnostic and clinical human studies. We present electrophysiological techniques similar to those employed in humans to allow recordings of mouse sciatic nerve function. The CMAP response represents the electrophysiological output from a muscle or group of muscles following supramaximal stimulation of a peripheral nerve. MUNE is an electrophysiological technique that is based on modifications of the CMAP response. MUNE is a calculated value that represents the estimated number of motor neurons or axons (motor control input) supplying the muscle or group of muscles being tested. We present methods for recording CMAP responses from the proximal leg muscles using surface recording electrodes following the stimulation of the sciatic nerve in mice. An incremental MUNE technique is described using submaximal stimuli to determine the average single motor unit potential (SMUP) size. MUNE is calculated by dividing the CMAP amplitude (peak-to-peak) by the SMUP amplitude (peak-to-peak). These electrophysiological techniques allow repeated measures in both neonatal and adult mice in such a manner that facilitates rapid analysis and data collection while reducing the number of animals required for experimental testing. Furthermore, these measures are similar to those recorded in human studies allowing more direct comparisons. PMID:26436455

  6. Anthropomorphizing the Mouse Cardiac Action Potential via a Novel Dynamic Clamp Method

    Science.gov (United States)

    Ahrens-Nicklas, Rebecca C.; Christini, David J.

    2009-01-01

    Abstract Interspecies differences can limit the translational value of excitable cells isolated from model organisms. It can be difficult to extrapolate from a drug- or mutation-induced phenotype in mice to human pathophysiology because mouse and human cardiac electrodynamics differ greatly. We present a hybrid computational-experimental technique, the cell-type transforming clamp, which is designed to overcome such differences by using a calculated compensatory current to convert the macroscopic electrical behavior of an isolated cell into that of a different cell type. We demonstrate the technique's utility by evaluating drug arrhythmogenicity in murine cardiomyocytes that are transformed to behave like human myocytes. Whereas we use the cell-type transforming clamp in this work to convert between mouse and human electrodynamics, the technique could be adapted to convert between the action potential morphologies of any two cell types of interest. PMID:19917221

  7. Mechanism of Action and Clinical Potential of Fingolimod for the Treatment of Stroke

    Directory of Open Access Journals (Sweden)

    Wentao Li

    2016-08-01

    Full Text Available Fingolimod (FTY720 is an orally bio-available immunomodulatory drug currently approved by the FDA for the treatment of multiple sclerosis. Currently, there is a significant interest in the potential benefits of FTY720 on stroke outcomes. FTY720 and the sphingolipid signaling pathway it modulates has a ubiquitous presence in the central nervous system and both rodent models and pilot clinical trials seem to indicate that the drug may improve overall functional recovery in different stroke subtypes. Although the precise mechanisms behind these beneficial effects are yet unclear, there is evidence that FTY720 has a role in regulating cerebrovascular responses, blood brain barrier permeability, and cell survival in the event of cerebrovascular insult. In this article, we critically review the data obtained from the latest laboratory findings and clinical trials involving both ischemic and hemorrhagic stroke, and attempt to form a cohesive picture of FTY720’s mechanisms of action in stroke

  8. Effect of sampling frequency on the measurement of phase-locked action potentials.

    Directory of Open Access Journals (Sweden)

    Go eAshida

    2010-09-01

    Full Text Available Phase-locked spikes in various types of neurons encode temporal information. To quantify the degree of phase-locking, the metric called vector strength (VS has been most widely used. Since VS is derived from spike timing information, error in measurement of spike occurrence should result in errors in VS calculation. In electrophysiological experiments, the timing of an action potential is detected with finite temporal precision, which is determined by the sampling frequency. In order to evaluate the effects of the sampling frequency on the measurement of VS, we derive theoretical upper and lower bounds of VS from spikes collected with finite sampling rates. We next estimate errors in VS assuming random sampling effects, and show that our theoretical calculation agrees with data from electrophysiological recordings in vivo. Our results provide a practical guide for choosing the appropriate sampling frequency in measuring VS.

  9. Optical magnetic detection of single-neuron action potentials using quantum defects in diamond

    CERN Document Server

    Barry, J F; Schloss, J M; Glenn, D R; Song, Y; Lukin, M D; Park, H; Walsworth, R L

    2016-01-01

    A key challenge for neuroscience is noninvasive, label-free sensing of action potential (AP) dynamics in whole organisms with single-neuron resolution. Here, we present a new approach to this problem: using nitrogen-vacancy (NV) quantum defects in diamond to measure the time-dependent magnetic fields produced by single-neuron APs. Our technique has a unique combination of features: (i) it is noninvasive, as the light that probes the NV sensors stays within the biocompatible diamond chip and does not enter the organism, enabling activity monitoring over extended periods; (ii) it is label-free and should be widely applicable to most organisms; (iii) it provides high spatial and temporal resolution, allowing precise measurement of the AP waveforms and conduction velocities of individual neurons; (iv) it directly determines AP propagation direction through the inherent sensitivity of NVs to the associated AP magnetic field vector; (v) it is applicable to neurons located within optically opaque tissue or whole org...

  10. BK channels regulate spontaneous action potential rhythmicity in the suprachiasmatic nucleus.

    Directory of Open Access Journals (Sweden)

    Jack Kent

    Full Text Available BACKGROUND: Circadian ( approximately 24 hr rhythms are generated by the central pacemaker localized to the suprachiasmatic nucleus (SCN of the hypothalamus. Although the basis for intrinsic rhythmicity is generally understood to rely on transcription factors encoded by "clock genes", less is known about the daily regulation of SCN neuronal activity patterns that communicate a circadian time signal to downstream behaviors and physiological systems. Action potentials in the SCN are necessary for the circadian timing of behavior, and individual SCN neurons modulate their spontaneous firing rate (SFR over the daily cycle, suggesting that the circadian patterning of neuronal activity is necessary for normal behavioral rhythm expression. The BK K(+ channel plays an important role in suppressing spontaneous firing at night in SCN neurons. Deletion of the Kcnma1 gene, encoding the BK channel, causes degradation of circadian behavioral and physiological rhythms. METHODOLOGY/PRINCIPAL FINDINGS: To test the hypothesis that loss of robust behavioral rhythmicity in Kcnma1(-/- mice is due to the disruption of SFR rhythms in the SCN, we used multi-electrode arrays to record extracellular action potentials from acute wild-type (WT and Kcnma1(-/- slices. Patterns of activity in the SCN were tracked simultaneously for up to 3 days, and the phase, period, and synchronization of SFR rhythms were examined. Loss of BK channels increased arrhythmicity but also altered the amplitude and period of rhythmic activity. Unexpectedly, Kcnma1(-/- SCNs showed increased variability in the timing of the daily SFR peak. CONCLUSIONS/SIGNIFICANCE: These results suggest that BK channels regulate multiple aspects of the circadian patterning of neuronal activity in the SCN. In addition, these data illustrate the characteristics of a disrupted SCN rhythm downstream of clock gene-mediated timekeeping and its relationship to behavioral rhythms.

  11. The potential of using brain images for authentication.

    Science.gov (United States)

    Chen, Fanglin; Zhou, Zongtan; Shen, Hui; Hu, Dewen

    2014-01-01

    Biometric recognition (also known as biometrics) refers to the automated recognition of individuals based on their biological or behavioral traits. Examples of biometric traits include fingerprint, palmprint, iris, and face. The brain is the most important and complex organ in the human body. Can it be used as a biometric trait? In this study, we analyze the uniqueness of the brain and try to use the brain for identity authentication. The proposed brain-based verification system operates in two stages: gray matter extraction and gray matter matching. A modified brain segmentation algorithm is implemented for extracting gray matter from an input brain image. Then, an alignment-based matching algorithm is developed for brain matching. Experimental results on two data sets show that the proposed brain recognition system meets the high accuracy requirement of identity authentication. Though currently the acquisition of the brain is still time consuming and expensive, brain images are highly unique and have the potential possibility for authentication in view of pattern recognition. PMID:25126604

  12. Potential Beneficiaries of the Obama Administration’s Executive Action Programs Deeply Embedded in US Society

    Directory of Open Access Journals (Sweden)

    Donald Kerwin

    2016-03-01

    Full Text Available The Obama administration has developed two broad programs to defer immigration enforcement actions against undocumented persons living in the United States: (1 Deferred Action for Parents of Americans and Lawful Permanent Residents (DAPA; and (2 Deferred Action for Childhood Arrivals (DACA. The DACA program, which began in August 2012, was expanded on November 20, 2014. DAPA and the DACA expansion (hereinafter referred to as “DACA-plus” are currently under review by the US Supreme Court and subject to an active injunction.This paper offers a statistical portrait of the intended direct beneficiaries of DAPA, DACA, and DACA-plus. It finds that potential DAPA, DACA, and DACA-plus recipients are deeply embedded in US society, with high employment rates, extensive US family ties, long tenure, and substantial rates of English-language proficiency. The paper also notes various groups that would benefit indirectly from the full implementation of DAPA and DACA or, conversely, would suffer from the removal of potential beneficiaries of these programs. For example, all those who would rely on the retirement programs of the US government will benefit from the high employment rates and relative youth of the DACA population, while many US citizens who rely on the income of a DAPA-eligible parent would fall into poverty or extreme poverty should that parent be removed from the United States.This paper offers an analysis of potential DAPA and DACA beneficiaries. In an earlier study, the authors made the case for immigration reform based on long-term trends related to the US undocumented population, including potential DAPA and DACA beneficiaries (Warren and Kerwin 2015. By contrast, this paper details the degree to which these populations have become embedded in US society. It also compares persons eligible for the original DACA program with those eligible for DACA-plus.As stated, the great majority of potential DAPA and DACA recipients enjoy strong family

  13. Modulation of hERG potassium channel gating normalizes action potential duration prolonged by dysfunctional KCNQ1 potassium channel

    Science.gov (United States)

    Zhang, Hongkang; Zou, Beiyan; Yu, Haibo; Moretti, Alessandra; Wang, Xiaoying; Yan, Wei; Babcock, Joseph J.; Bellin, Milena; McManus, Owen B.; Tomaselli, Gordon; Nan, Fajun; Laugwitz, Karl-Ludwig; Li, Min

    2012-01-01

    Long QT syndrome (LQTS) is a genetic disease characterized by a prolonged QT interval in an electrocardiogram (ECG), leading to higher risk of sudden cardiac death. Among the 12 identified genes causal to heritable LQTS, ∼90% of affected individuals harbor mutations in either KCNQ1 or human ether-a-go-go related genes (hERG), which encode two repolarizing potassium currents known as IKs and IKr. The ability to quantitatively assess contributions of different current components is therefore important for investigating disease phenotypes and testing effectiveness of pharmacological modulation. Here we report a quantitative analysis by simulating cardiac action potentials of cultured human cardiomyocytes to match the experimental waveforms of both healthy control and LQT syndrome type 1 (LQT1) action potentials. The quantitative evaluation suggests that elevation of IKr by reducing voltage sensitivity of inactivation, not via slowing of deactivation, could more effectively restore normal QT duration if IKs is reduced. Using a unique specific chemical activator for IKr that has a primary effect of causing a right shift of V1/2 for inactivation, we then examined the duration changes of autonomous action potentials from differentiated human cardiomyocytes. Indeed, this activator causes dose-dependent shortening of the action potential durations and is able to normalize action potentials of cells of patients with LQT1. In contrast, an IKr chemical activator of primary effects in slowing channel deactivation was not effective in modulating action potential durations. Our studies provide both the theoretical basis and experimental support for compensatory normalization of action potential duration by a pharmacological agent. PMID:22745159

  14. Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds.

    Science.gov (United States)

    DeVries, Lindsay; Scheperle, Rachel; Bierer, Julie Arenberg

    2016-06-01

    Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes. PMID:26926152

  15. Optophysiological approach to resolve neuronal action potentials with high spatial and temporal resolution in cultured neurons

    Directory of Open Access Journals (Sweden)

    Stephane ePages

    2011-10-01

    Full Text Available Cell to cell communication in the central nervous system is encoded into transient and local membrane potential changes (ΔVm. Deciphering the rules that govern synaptic transmission and plasticity entails to be able to perform Vm recordings throughout the entire neuronal arborization. Classical electrophysiology is, in most cases, not able to do so within small and fragile neuronal subcompartments. Thus, optical techniques based on the use of fluorescent voltage-sensitive dyes (VSDs have been developed. However, reporting spontaneous or small ΔVm from neuronal ramifications has been challenging, in part due to the limited sensitivity and phototoxicity of VSD-based optical measurements. Here we demonstrate the use of water soluble VSD, ANNINE-6plus, with laser scanning microscopy to optically record ΔVm in cultured neurons. We show that the sensitivity (> 10 % of fluorescence change for 100 mV depolarization and time response (submillisecond of the dye allows the robust detection of action potentials (APs even without averaging, allowing the measurement of spontaneous neuronal firing patterns. In addition, we show that back-propagating APs can be recorded, along distinct dendritic sites and within dendritic spines. Importantly, our approach does not induce any detectable phototoxic effect on cultured neurons. This optophysiological approach provides a simple, minimally invasive and versatile optical method to measure electrical activity in cultured neurons with high temporal (ms resolution and high spatial (µm resolution.

  16. Variability of Action Potentials Within and Among Cardiac Cell Clusters Derived from Human Embryonic Stem Cells.

    Science.gov (United States)

    Zhu, Renjun; Millrod, Michal A; Zambidis, Elias T; Tung, Leslie

    2016-01-01

    Electrophysiological variability in cardiomyocytes derived from pluripotent stem cells continues to be an impediment for their scientific and translational applications. We studied the variability of action potentials (APs) recorded from clusters of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) using high-resolution optical mapping. Over 23,000 APs were analyzed through four parameters: APD30, APD80, triangulation and fractional repolarization. Although measures were taken to reduce variability due to cell culture conditions and rate-dependency of APs, we still observed significant variability in APs among and within the clusters. However, similar APs were found in spatial locations with close proximity, and in some clusters formed distinct regions having different AP characteristics that were reflected as separate peaks in the AP parameter distributions, suggesting multiple electrophysiological phenotypes. Using a recently developed automated method to group cells based on their entire AP shape, we identified distinct regions of different phenotypes within single clusters and common phenotypes across different clusters when separating APs into 2 or 3 subpopulations. The systematic analysis of the heterogeneity and potential phenotypes of large populations of hESC-CMs can be used to evaluate strategies to improve the quality of pluripotent stem cell-derived cardiomyocytes for use in diagnostic and therapeutic applications and in drug screening. PMID:26729331

  17. Small-conductance calcium-activated potassium (SK) channels contribute to action potential repolarization in human atria

    DEFF Research Database (Denmark)

    Skibsbye, Lasse; Poulet, Claire; Diness, Jonas Goldin;

    2014-01-01

    (+) currents by ∼15% and prolonged action potential duration (APD), but no effect was observed in myocytes from AF patients. In trabeculae muscle strips from right atrial appendages of SR patients, both compounds increased APD and effective refractory period, and depolarized the resting membrane potential...

  18. Image potential states mediated STM imaging of cobalt phthalocyanine on NaCl/Cu(100)

    Science.gov (United States)

    Qinmin, Guo; Zhihui, Qin; Min, Huang; Vladimir, N. Mantsevich; Gengyu, Cao

    2016-03-01

    The adsorption and electronic properties of isolated cobalt phthalocyanine (CoPc) molecule on an ultrathin layer of NaCl have been investigated. High-resolution STM images give a detailed picture of the lowest unoccupied molecular orbital (LUMO) of an isolated CoPc. It is shown that the NaCl ultrathin layer efficiently decouples the interaction of the molecules from the underneath metal substrate, which makes it an ideal substrate for studying the properties of single molecules. Moreover, strong dependence of the appearance of the molecules on the sample bias in the region of relatively high bias (> 3.1 V) is ascribed to the image potential states (IPSs) of NaCl/Cu(100), which may provide us with a possible method to fabricate quantum storage devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 21203239 and 21311120059) and RFBR (Grant No. 13-02-91180).

  19. Surface electrocardiogram and action potential in mice lacking urea transporter UT-B

    Institute of Scientific and Technical Information of China (English)

    MENG Yan; ZHAO ChunYan; ZHANG XueXin; ZHAO HuaShan; GUO LiRong; Lü Bin; ZHAO XueJian; YANG BaoXue

    2009-01-01

    UT-B is a urea transporter protein expressed in the kidney and in many non-renal tissues including erythrocytes, brain, heart, bladder and the testis. The objective of this study was to determine the phenotype of UT-B deletion in the heart. UT-B expression in the heart was studied in wild-type mice vs UT-B null mice by utilizing RT-PCR and Western blot. A surface electrocardiogram (ECG) recording (lead Ⅱ) was measured in wild-type mice and UT-B null mice at the ages of 6, 16 and 52 weeks. For the action potential recording, the ventricular myocytes of 16 w mice were isolated and recorded by float-ing microelectrode method. The sodium current was recorded by the patch clamp technique. RT-PCR and Western blot showed the UT-B expression in the heart of wild-type mice. No UT-B transcript and protein was found in UT-B null mice. The ECG recording showed that the P-R interval was significantly prolonged in UT-B null mice ((43.5±4.2), (45.5±6.9) and (43.8±7.6) ms at ages of 6, 16 and 52 weeks) vs wild-type mice ((38.6±2.9), (38.7±5.6) and (38.2±7.3) ms, P<0.05). The atrial ventricular heart block type Ⅱ and Ⅲ only appeared in the aging UT-B null mice (52 w old). The amplitude of action potential and Vmax decreased significantly in UT-B null mice ((92.17±10.56) and (101.89±9.54) mV/s) vs those in wild-type mice (vs (110.51±10.38) and (109.53±10.64) mV/s, P<0.05). The action potential duration at 50% and 90% (APD50 and APD90) was significantly prolonged in UT-B null mice ((123.83±11.17) and (195.43±16.41) ms) vs that in wild-type mice ((108.27±10.85) and (171.00±15.53) ms, P<0.05). The maximal sodium current decreased significantly in UT-B null mice (-8.80±0.92) nA vs that in wild-type mice ((-5.98±1.07) nA, P<0.05). These results provide the first evidence that UT-B deletion causes progressive heart block in mice.

  20. Surface electrocardiogram and action potential in mice lacking urea transporter UT-B

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    UT-B is a urea transporter protein expressed in the kidney and in many non-renal tissues including erythrocytes, brain, heart, bladder and the testis. The objective of this study was to determine the phenotype of UT-B deletion in the heart. UT-B expression in the heart was studied in wild-type mice vs UT-B null mice by utilizing RT-PCR and Western blot. A surface electrocardiogram (ECG) recording (lead II) was measured in wild-type mice and UT-B null mice at the ages of 6, 16 and 52 weeks. For the action potential recording, the ventricular myocytes of 16 w mice were isolated and recorded by floating microelectrode method. The sodium current was recorded by the patch clamp technique. RT-PCR and Western blot showed the UT-B expression in the heart of wild-type mice. No UT-B transcript and protein was found in UT-B null mice. The ECG recording showed that the P-R interval was significantly prolonged in UT-B null mice ((43.5 ± 4.2), (45.5 ± 6.9) and (43.8 ± 7.6) ms at ages of 6, 16 and 52 weeks) vs wild-type mice ((38.6 ± 2.9), (38.7 ± 5.6) and (38.2 ± 7.3) ms, P<0.05). The atrial ventricular heart block type II and III only appeared in the aging UT-B null mice (52 w old). The amplitude of action potential and Vmax decreased significantly in UT-B null mice ((92.17 ± 10.56) and (101.89 ± 9.54) mV/s) vs those in wild-type mice (vs (110.51 ± 10.38) and (109.53 ± 10.64) mV/s, P<0.05). The action potential duration at 50% and 90% (APD50 and APD90) was significantly prolonged in UT-B null mice ((123.83 ± 11.17) and (195.43 ± 16.41) ms) vs that in wild-type mice ((108.27 ± 10.85) and (171.00 ± 15.53) ms, P<0.05). The maximal sodium current decreased significantly in UT-B null mice (-8.80 ± 0.92) nA vs that in wild-type mice ((-5.98 ± 1.07) nA, P<0.05). These results provide the first evidence that UT-B deletion causes progressive heart block in mice.

  1. An experimental study on the physical properties of the cupula. Effect of cupular sectioning on the ampullary nerve action potential.

    Science.gov (United States)

    Suzuki, M; Harada, Y; Kishimoto, A

    1985-01-01

    The frog posterior semicircular canal (PSC) was isolated and a part of the ampullary wall was cut to allow removal of the cupula from the crista. The cupula was replaced on the crista and the PSC ampullary action potential was recorded. The cupula was again removed and was sectioned in half, either in the plane vertical to the crista (vertical sectioning), or in the plane parallel to the crista (horizontal sectioning). The sectioned half of the cupula was then replaced on the crista. The action potentials after replacement of the vertical or horizontal segments of the cupula were compared to those achieved when the entire cupula was replaced. After vertical sectioning, the action potentials were significantly reduced; they were 50.3% of the completely replaced cupula when a small stimulus was used and 79.1% when a large stimulus was used. A reduced attachment surface between the cupular base and the crista is possibly responsible for the decreased action potential in the vertically sectioned specimen. After horizontal sectioning, the action potentials were 64.5% for the small stimulus and 108.2% for the large stimulus. These results indicate that elicited responses are related to the height of the cupula and the deflection angle. This further suggests that the movement of the cupula is represented by that of the elastic system.

  2. CLINICAL AND EXPERIMENTAL STUDIES OF LARGE AMPLITUDE ACTION POTENTIAL OF THE SUFFERED FACIAL MUSCLES IN INTRATEMPORAL FACIAL NERVE PARALYSIS

    Institute of Scientific and Technical Information of China (English)

    任重; 惠莲

    1999-01-01

    Objctive. To testify the phenomenon that large amplitude action potential appears at the early stage oil facial paralysis, and to search for the mechanism through clinical and experimental studies. Patients(aninmls) and methods. The action potentials of the orbicular ocular and oral museles were recorded in 34 normal persons by electromyogram instrtiments. The normal range of amplitude percentage was found out according to the normal distribution, One hundred patients with facial paralysis were also studied. The action potentials of facial muscles were recorded ia 17 guinea pigs before and after the facial nerve was comp~ and the facial nerve was examined under electromicroscope before and after the compression.Results. The amplitude percentage of the suffered side to the healthy side was more than 153 percent in 6 of the 100 patients. Large amplitude action potential occured in 35 per cent guinea pigs which were performed the experiment of facial nerve compression. Electromicroscopic examination revealed separation of the lammae of the facial nerve's myelin sheath in the guinea pigs which exhibited large amplitude action potential Conclusion. The facial nerve exhibited a temporary over-excitability at the early stage of facial nerve injury in scane patients and guinea pigs. If the injury was limited in the myelin sheath, the prognods was relatively good.

  3. CLINICAL AND EXPERIMENTAL STUDIES OF LARGE AMPLITUDE ACTION POTENTIAL OF THE SUFFERED FACIAL MUSCLES IN INTRATEMPORAL FACIAL NERVE PARALYSIS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Ojective. To testify the phenomenon that large amplitude action potential appears at the early stage of facial paralysis, and to search for the mechanism through clinical and experimental studies. Patients(animals) and methods. The action potentials of the orbicular ocular and oral muscles were recorded in 34 normal persons by electromyogram instruments. The normal range of amplitude percentage was found out according to he normal distribution. One hundred patients with facial paralysis were also studied. The action potentials of facial muscles were recorded in 17 guinea pigs before and after the facial nerve was compressed and the facial nerve was examined under electromicroscope before and after the compression.Results. The amplitude percentage of the suffered ide to the healthy side was more than 153 percent in 6 of the 100 patients. Lare amplitude action potential ocured in 35 per cent guinea pigs which were performed the experiment of facial nrve compression. Electromicroscopic examination revealed separation of the lammae of the facial nerve's myelin sheath in the guinea pigs which exhibited large amplitude action potential.Conclusion. The facial nerve exhibited a temporary over-exciability at the early stage of facial nerve injury in some patients and guinea pigs. If the injury waslimited in the myelin sheath, te prognosis was relatively good.

  4. Computer vision and action recognition a guide for image processing and computer vision community for action understanding

    CERN Document Server

    Ahad, Md Atiqur Rahman

    2011-01-01

    Human action analyses and recognition are challenging problems due to large variations in human motion and appearance, camera viewpoint and environment settings. The field of action and activity representation and recognition is relatively old, yet not well-understood by the students and research community. Some important but common motion recognition problems are even now unsolved properly by the computer vision community. However, in the last decade, a number of good approaches are proposed and evaluated subsequently by many researchers. Among those methods, some methods get significant atte

  5. Prospective on the potential of imaging gene expression

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Scott E; Budinger, Thomas F.

    2000-06-01

    The feasibility of the non-invasive imaging of gene expression is explored. Calculations of the possibility of the direct imaging of specific messenger RNA with radiolabeled antisense are discussed. In addition, possible mechanism for the amplification of the biological signal to enhance image detection are discussed.

  6. Study of crotoxin mechanism of action to mammary carcinomas and evaluation of its potential as a radiopharmaceutical

    International Nuclear Information System (INIS)

    radiolabeled polypeptide interaction showed low specificity toward to MCF-7 (37%). EGF reduced 20% of 125I-Crotoxin specific binding, so specific binding sites of Crotoxin on Ehrlich tumor cells partially overlap to EGFR. Crotoxin biodistribution studies showed significant uptake in the tumor paw (tumor/skeletal muscle ratio= 18.55), three hours after administration. SPECT imaging also showed tumor uptake confirming in vivo interaction with Ehrlich tumor cells. Crotoxin had an antitumoral effect on Ehrlich tumor cells and this action is due, at least partially, to the specific interaction with low and high affinity binding sites. Low affinity binding sites correlate EGFR and high affinity binding sites still need identification. These results confirm Crotoxin as a template for radiopharmaceutical design for cancer diagnosis and as a tool for cancer studies, increasing its biotechnological potential. (author)

  7. The transformative potential of action research and ICT in the Second Language (L2 classroom

    Directory of Open Access Journals (Sweden)

    Farren Margaret

    2015-12-01

    Full Text Available This study shows the transformative potential of action research and information and communications technology (ICT in the second language (L2 classroom. Two enquiries from teacher-researchers are detailed in the article. Their engagement in a collaborative professional development Masters programme was pivotal in designing and implementing ICT creatively in their classroom. Gee (2008 advocates the use of the preferred media of our classroom students in order to address their learning. Prensky (2001 urges us to feel the fear and do it anyway with our digital native classes. A post-primary teacher and a primary teacher show us how they felt the fear, did it and transformed aspects of their own teaching in the process. The Masters programme required the teachers to engage with innovative practices, informed by their own values, and integrate technologies that were new to them into their repertoire of classroom strategies. Peer validation meetings with colleagues enabled meaningful insights to emerge from the research. The teachers improve and transform their second language (L2 practice in collaboration and validation with others.

  8. Effects of terpineol on the compound action potential of the rat sciatic nerve

    Directory of Open Access Journals (Sweden)

    M.R. Moreira

    2001-10-01

    Full Text Available Terpineol, a volatile terpenoid alcohol of low toxicity, is widely used in the perfumery industry. It is an important chemical constituent of the essential oil of many plants with widespread applications in folk medicine and in aromatherapy. The effects of terpineol on the compound action potential (CAP of rat sciatic nerve were studied. Terpineol induced a dose-dependent blockade of the CAP. At 100 µM, terpineol had no demonstrable effect. At 300 µM terpineol, peak-to-peak amplitude and conduction velocity of CAP were significantly reduced at the end of 180-min exposure of the nerve to the drug, from 3.28 ± 0.22 mV and 33.5 ± 7.05 m/s, respectively, to 1.91 ± 0.51 mV and 26.2 ± 4.55 m/s. At 600 µM, terpineol significantly reduced peak-to-peak amplitude and conduction velocity from 2.97 ± 0.55 mV and 32.8 ± 3.91 m/s to 0.24 ± 0.23 mV and 2.72 ± 2.72 m/s, respectively (N = 5. All these effects developed slowly and were reversible upon 180-min washout.

  9. Adhesion to carbon nanotube conductive scaffolds forces action-potential appearance in immature rat spinal neurons.

    Science.gov (United States)

    Fabbro, Alessandra; Sucapane, Antonietta; Toma, Francesca Maria; Calura, Enrica; Rizzetto, Lisa; Carrieri, Claudia; Roncaglia, Paola; Martinelli, Valentina; Scaini, Denis; Masten, Lara; Turco, Antonio; Gustincich, Stefano; Prato, Maurizio; Ballerini, Laura

    2013-01-01

    In the last decade, carbon nanotube growth substrates have been used to investigate neurons and neuronal networks formation in vitro when guided by artificial nano-scaled cues. Besides, nanotube-based interfaces are being developed, such as prosthesis for monitoring brain activity. We recently described how carbon nanotube substrates alter the electrophysiological and synaptic responses of hippocampal neurons in culture. This observation highlighted the exceptional ability of this material in interfering with nerve tissue growth. Here we test the hypothesis that carbon nanotube scaffolds promote the development of immature neurons isolated from the neonatal rat spinal cord, and maintained in vitro. To address this issue we performed electrophysiological studies associated to gene expression analysis. Our results indicate that spinal neurons plated on electro-conductive carbon nanotubes show a facilitated development. Spinal neurons anticipate the expression of functional markers of maturation, such as the generation of voltage dependent currents or action potentials. These changes are accompanied by a selective modulation of gene expression, involving neuronal and non-neuronal components. Our microarray experiments suggest that carbon nanotube platforms trigger reparative activities involving microglia, in the absence of reactive gliosis. Hence, future tissue scaffolds blended with conductive nanotubes may be exploited to promote cell differentiation and reparative pathways in neural regeneration strategies.

  10. Action potential energy efficiency varies among neuron types in vertebrates and invertebrates.

    Science.gov (United States)

    Sengupta, Biswa; Stemmler, Martin; Laughlin, Simon B; Niven, Jeremy E

    2010-01-01

    The initiation and propagation of action potentials (APs) places high demands on the energetic resources of neural tissue. Each AP forces ATP-driven ion pumps to work harder to restore the ionic concentration gradients, thus consuming more energy. Here, we ask whether the ionic currents underlying the AP can be predicted theoretically from the principle of minimum energy consumption. A long-held supposition that APs are energetically wasteful, based on theoretical analysis of the squid giant axon AP, has recently been overturned by studies that measured the currents contributing to the AP in several mammalian neurons. In the single compartment models studied here, AP energy consumption varies greatly among vertebrate and invertebrate neurons, with several mammalian neuron models using close to the capacitive minimum of energy needed. Strikingly, energy consumption can increase by more than ten-fold simply by changing the overlap of the Na(+) and K(+) currents during the AP without changing the APs shape. As a consequence, the height and width of the AP are poor predictors of energy consumption. In the Hodgkin-Huxley model of the squid axon, optimizing the kinetics or number of Na(+) and K(+) channels can whittle down the number of ATP molecules needed for each AP by a factor of four. In contrast to the squid AP, the temporal profile of the currents underlying APs of some mammalian neurons are nearly perfectly matched to the optimized properties of ionic conductances so as to minimize the ATP cost. PMID:20617202

  11. Action potential energy efficiency varies among neuron types in vertebrates and invertebrates.

    Directory of Open Access Journals (Sweden)

    Biswa Sengupta

    Full Text Available The initiation and propagation of action potentials (APs places high demands on the energetic resources of neural tissue. Each AP forces ATP-driven ion pumps to work harder to restore the ionic concentration gradients, thus consuming more energy. Here, we ask whether the ionic currents underlying the AP can be predicted theoretically from the principle of minimum energy consumption. A long-held supposition that APs are energetically wasteful, based on theoretical analysis of the squid giant axon AP, has recently been overturned by studies that measured the currents contributing to the AP in several mammalian neurons. In the single compartment models studied here, AP energy consumption varies greatly among vertebrate and invertebrate neurons, with several mammalian neuron models using close to the capacitive minimum of energy needed. Strikingly, energy consumption can increase by more than ten-fold simply by changing the overlap of the Na(+ and K(+ currents during the AP without changing the APs shape. As a consequence, the height and width of the AP are poor predictors of energy consumption. In the Hodgkin-Huxley model of the squid axon, optimizing the kinetics or number of Na(+ and K(+ channels can whittle down the number of ATP molecules needed for each AP by a factor of four. In contrast to the squid AP, the temporal profile of the currents underlying APs of some mammalian neurons are nearly perfectly matched to the optimized properties of ionic conductances so as to minimize the ATP cost.

  12. Dispersion of compound muscle action potential in hereditary neuropathies and chronic inflammatory demyelinating polyneuropathy.

    Science.gov (United States)

    Stanton, Michael; Pannoni, Valerie; Lewis, Richard A; Logigian, Eric L; Naguib, Demian; Shy, Michael E; Cleland, James; Herrmann, David N

    2006-10-01

    Distal compound muscle action potential (DCMAP) dispersion, defined as a DCMAP duration > or = 9 ms, and proximal-distal (P-D) CMAP dispersion are considered useful in the electrodiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP). Distal and P-D CMAP dispersion have not been fully studied in hereditary neuropathies, and it is not known whether these measures distinguish hereditary from acquired demyelination. We compared DCMAP duration and P-D CMAP dispersion in 91 genetically characterized hereditary neuropathies and 33 subjects with CIDP. DCMAP dispersion was more frequent in nerves affected by CIDP (41.5%) than in Charcot-Marie-Tooth disease (CMT)1A (24.4%), CMT1B (7.4%), hereditary neuropathy with liability to pressure palsies (HNPP) (10.5%), or CMTX (9.8%). P-D CMAP dispersion was more frequent in CIDP (27.7% of nerves) than in hereditary neuropathies (16.3%) when applying American Academy of Neurology (AAN) criteria; however, its frequency was similar in CIDP and the hereditary neuropathies using the more restrictive criteria of the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM). Although dispersion is more common in CIDP than in the hereditary neuropathies, DCMAP and P-D dispersion occur in at least one motor nerve in a significant proportion of hereditary neuropathies, and cannot be used in isolation to distinguish acquired from hereditary demyelination.

  13. Sensitivity analysis of potential events affecting the double-shell tank system and fallback actions

    Energy Technology Data Exchange (ETDEWEB)

    Knutson, B.J.

    1996-09-27

    Sensitivity analyses were performed for fall-back positions (i.e., management actions) to accommodate potential off-normal and programmatic change events overlaid on the waste volume projections and their uncertainties. These sensitivity analyses allowed determining and ranking tank system high-risk parameters and fall- back positions that will accommodate the respective impacts. This quantification of tank system impacts shows periods where tank capacity is sensitive to certain variables that must be carefully managed and/or evaluated. Identifying these sensitive variables and quantifying their impact will allow decision makers to prepare fall-back positions and focus available resources on the highest impact parameters where technical data are needed to reduce waste projection uncertainties. For noncomplexed waste, the period of capacity vulnerability occurs during the years of single-shell tank (SST) retrieval (after approximately 2009) due to the sensitivity to several variables. Ranked by importance these variables include the pretreatment rate and 200-East SST solids transfer volume. For complexed waste, the period of capacity vulnerability occurs during the period after approximately 2005 due to the sensitivity to several variables. Ranked by importance these variables include the pretreatment rate. 200-East SST solids transfer volume. complexed waste reduction factor using evaporation, and 200-west saltwell liquid porosity.

  14. Latencies in action potential stimulation in a two-dimensional bidomain: A numerical simulation

    Science.gov (United States)

    Barach, John Paul

    1991-05-01

    A numerical simulation is performed in which a uniform planar slab of idealized cardiac tissue is stimulated at the center. The cardiac slab is modeled as an anisotropic bidomain; within each domain current flow is determined by a forced diffusion equation in which the transmembrane current connecting the domains provides the forcing term. An action potential (AP) propagates outward after a time latency dependent upon the stimulus size and the physiological variables. Its isochrones are elliptical with an asymmetry that is a small fraction of the imposed asymmetry in resistivity. External voltages resemble the first derivative of those in the internal domain and tests with continuing stimuli exhibit a relaxation time of about 3 ms and space constants that agree with other work. The AP latency increases very strongly near threshold stimulus and decreases as the log (stimulus) for large stimuli in the ``virtual cathode'' range. Latencies in the longitudinal, transverse, and diagonal directions are found to be the same over a wide range of stimulus size and type.

  15. Burst analysis tool for developing neuronal networks exhibiting highly varying action potential dynamics

    Directory of Open Access Journals (Sweden)

    Fikret Emre eKapucu

    2012-06-01

    Full Text Available In this paper we propose a firing statistics based neuronal network burst detection algorithm for neuronal networks exhibiting highly variable action potential dynamics. Electrical activity of neuronal networks is generally analyzed by the occurrences of spikes and bursts both in time and space. Commonly accepted analysis tools employ burst detection algorithms based on predefined criteria. However, maturing neuronal networks, such as those originating from human embryonic stem cells (hESC, exhibit highly variable network structure and time-varying dynamics. To explore the developing burst/spike activities of such networks, we propose a burst detection algorithm which utilizes the firing statistics based on interspike interval (ISI histograms. Moreover, the algorithm calculates interspike interval thresholds for burst spikes as well as for pre-burst spikes and burst tails by evaluating the cumulative moving average and skewness of the ISI histogram. Because of the adaptive nature of the proposed algorithm, its analysis power is not limited by the type of neuronal cell network at hand. We demonstrate the functionality of our algorithm with two different types of microelectrode array (MEA data recorded from spontaneously active hESC-derived neuronal cell networks. The same data was also analyzed by two commonly employed burst detection algorithms and the differences in burst detection results are illustrated. The results demonstrate that our method is both adaptive to the firing statistics of the network and yields successful burst detection from the data. In conclusion, the proposed method is a potential tool for analyzing of hESC-derived neuronal cell networks and thus can be utilized in studies aiming to understand the development and functioning of human neuronal networks and as an analysis tool for in vitro drug screening and neurotoxicity assays.

  16. Antifungal potential of Sideroxylon obtusifolium and Syzygium cumini and their mode of action against Candida albicans.

    Science.gov (United States)

    Pereira, Jozinete Vieira; Freires, Irlan Almeida; Castilho, Aline Rogéria; da Cunha, Marcos Guilherme; Alves, Harley da Silva; Rosalen, Pedro Luiz

    2016-10-01

    Context The emergence of resistant pathogens and toxicity of antifungals have encouraged an active search for novel candidates to manage Candida biofilms. Objective In this study, the little known species Sideroxylon obtusifolium T.D. Penn (Sapotacea) and Syzygium cumini (L.) Skeels (Myrtaceae), from the Caatinga biome in Brazil were chemically characterized and explored for their antifungal potential against C. albicans. Materials and methods We determined the effects of hydroalcoholic extracts/fractions upon fungal growth (minimum inhibitory and fungicidal concentrations, MIC/MFC), biofilm morphology (scanning electron microscopy) and viability (confocal laser scanning microscopy), proposed their mode of action (sorbitol and ergosterol assays), and finally investigated their effects against macrophage and keratinocyte cells in a cell-based assay. Data were analysed using one-way analysis of variance with Tukey-Kramer post-test (α = 0.05). Results The n-butanol (Nb) fraction from S. obtusifolium and S. cumini extract (Sc) showed flavonoids (39.11 ± 6.62 mg/g) and saponins (820.35 ± 225.38 mg/g), respectively, in their chemical composition and demonstrated antifungal activity, with MICs of 62.5 and 125 μg/mL, respectively. Nb and Sc may complex with ergosterol as there was a 4-16-fold increase in MICs in the presence of exogenous ergosterol, leading to disrupted permeability of cell membrane. Deleterious effects were observed on morphology and viability of treated biofilms from concentrations as low as their MICs and higher. Sc was not toxic to macrophages and keratinocytes at these concentrations (p > 0.05), unlike Nb. Conclusions Nb and Sc demonstrated considerable antifungal activity and should be further investigated as potential alternative candidates to treat Candida biofilms. PMID:26987037

  17. The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake.

    Science.gov (United States)

    Böhm, Jennifer; Scherzer, Sönke; Krol, Elzbieta; Kreuzer, Ines; von Meyer, Katharina; Lorey, Christian; Mueller, Thomas D; Shabala, Lana; Monte, Isabel; Solano, Roberto; Al-Rasheid, Khaled A S; Rennenberg, Heinz; Shabala, Sergey; Neher, Erwin; Hedrich, Rainer

    2016-02-01

    Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na(+)-rich animal and nutrition for the plant. PMID:26804557

  18. The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake.

    Science.gov (United States)

    Böhm, Jennifer; Scherzer, Sönke; Krol, Elzbieta; Kreuzer, Ines; von Meyer, Katharina; Lorey, Christian; Mueller, Thomas D; Shabala, Lana; Monte, Isabel; Solano, Roberto; Al-Rasheid, Khaled A S; Rennenberg, Heinz; Shabala, Sergey; Neher, Erwin; Hedrich, Rainer

    2016-02-01

    Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na(+)-rich animal and nutrition for the plant.

  19. Ionic mechanisms maintaining action potential conduction velocity at high firing frequencies in an unmyelinated axon.

    Science.gov (United States)

    Cross, Kevin P; Robertson, R Meldrum

    2016-05-01

    The descending contralateral movement detector (DCMD) is a high-performance interneuron in locusts with an axon capable of transmitting action potentials (AP) at more than 500 Hz. We investigated biophysical mechanisms for fidelity of high-frequency transmission in this axon. We measured conduction velocities (CVs) at room temperature during exposure to 10 mmol/L cadmium, a calcium current antagonist, and found significant reduction in CV with reduction at frequencies >200 Hz of ~10%. Higher temperatures induced greater CV reductions during exposure to cadmium across all frequencies of ~20-30%. Intracellular recordings during 15 min of exposure to cadmium or nickel, also a calcium current antagonist, revealed an increase in the magnitude of the afterhyperpolarization potential (AHP) and the time to recover to baseline after the AHP (Medians for Control: -19.8%; Nickel: 167.2%; Cadmium: 387.2%), that could be due to a T-type calcium current. However, the removal of extracellular calcium did not mimic divalent cation exposure suggesting calcium currents are not the cause of the AHP increase. Computational modeling showed that the effects of the divalent cations could be modeled with a persistent sodium current which could be blocked by high concentrations of divalent cations. Persistent sodium current shortened the AHP duration in our models and increased CV for high-frequency APs. We suggest that faithful, high-frequency axonal conduction in the DCMD is enabled by a mechanism that shortens the AHP duration like a persistent or resurgent sodium current. PMID:27225630

  20. MCH and apomorphine in combination enhance action potential firing of nucleus accumbens shell neurons in vitro

    Directory of Open Access Journals (Sweden)

    F Woodward Hopf

    2013-04-01

    Full Text Available The MCH and dopamine receptor systems have been shown to modulate a number of behaviors related to reward processing, addiction, and neuropsychiatric conditions such as schizophrenia and depression. In addition, MCH and dopamine receptors can interact in a positive manner, for example in the expression of cocaine self-administration. A recent report (Chung et al., 2011a showed that the DA1/DA2 dopamine receptor activator apomorphine suppresses pre-pulse inhibition, a preclinical model for some aspects of schizophrenia. Importantly, MCH can enhance the effects of lower doses of apomorphine, suggesting that co-modulation of dopamine and MCH receptors might alleviate some symptoms of schizophrenia with a lower dose of dopamine receptor modulator and thus fewer potential side effects. Here, we investigated whether MCH and apomorphine could enhance action potential firing in vitro in the nucleus accumbens shell (NAshell, a region which has previously been shown to mediate some behavioral effects of MCH. Using whole-cell patch-clamp electrophysiology, we found that MCH, which has no effect on firing on its own, was able to increase NAshell firing when combined with a subthreshold dose of apomorphine. Further, this MCH/apomorphine increase in firing was prevented by an antagonist of either a DA1 or a DA2 receptor, suggesting that apomorphine acts through both receptor types to enhance NAshell firing. The MCH/apomorphine-mediated firing increase was also prevented by an MCH receptor antagonist or a PKA inhibitor. Taken together, our results suggest that MCH can interact with lower doses of apomorphine to enhance NAshell firing, and thus that MCH and apomorphine might interact in vivo within the NAshell to suppress pre-pulse inhibition.

  1. Burst analysis tool for developing neuronal networks exhibiting highly varying action potential dynamics.

    Science.gov (United States)

    Kapucu, Fikret E; Tanskanen, Jarno M A; Mikkonen, Jarno E; Ylä-Outinen, Laura; Narkilahti, Susanna; Hyttinen, Jari A K

    2012-01-01

    In this paper we propose a firing statistics based neuronal network burst detection algorithm for neuronal networks exhibiting highly variable action potential dynamics. Electrical activity of neuronal networks is generally analyzed by the occurrences of spikes and bursts both in time and space. Commonly accepted analysis tools employ burst detection algorithms based on predefined criteria. However, maturing neuronal networks, such as those originating from human embryonic stem cells (hESCs), exhibit highly variable network structure and time-varying dynamics. To explore the developing burst/spike activities of such networks, we propose a burst detection algorithm which utilizes the firing statistics based on interspike interval (ISI) histograms. Moreover, the algorithm calculates ISI thresholds for burst spikes as well as for pre-burst spikes and burst tails by evaluating the cumulative moving average (CMA) and skewness of the ISI histogram. Because of the adaptive nature of the proposed algorithm, its analysis power is not limited by the type of neuronal cell network at hand. We demonstrate the functionality of our algorithm with two different types of microelectrode array (MEA) data recorded from spontaneously active hESC-derived neuronal cell networks. The same data was also analyzed by two commonly employed burst detection algorithms and the differences in burst detection results are illustrated. The results demonstrate that our method is both adaptive to the firing statistics of the network and yields successful burst detection from the data. In conclusion, the proposed method is a potential tool for analyzing of hESC-derived neuronal cell networks and thus can be utilized in studies aiming to understand the development and functioning of human neuronal networks and as an analysis tool for in vitro drug screening and neurotoxicity assays.

  2. Design of [2]rotaxane through image threshold segmentation of electrostatic potential image.

    Science.gov (United States)

    Liu, Pingying; Chen, Qiufeng; Ma, Jing

    2016-09-15

    An electrostatic potential (ESP)-based image segmentation method has been used to estimate the ability of proton donation and acceptance involved in ring-rod recognition. The relative binding strength of [2]rotaxane has also been further estimated from the difference of the characteristic image-segmentation derived ESP between proton donor and proton acceptor. The size and electrostatic compatibility criteria are introduced to guide the design of interlocked [2]rotaxane. A library of 75 thermodynamically stable [2]rotaxane candidates has been generated, including 16 experimentally known systems. The theoretical results for 16 experimentally known [2]rotaxanes are in good agreement with both the experimental association constants and density functional theory-calculated binding energies. Our ESP-based image segmentation model is also applicable to the tristable [2]rotaxane molecular shuttle as well as [1]rotaxane with self-inclusion function, indicating this simple method is generic in the field of constructing other supramolecular architectures formed with donor/acceptor molecular recognition. © 2016 Wiley Periodicals, Inc. PMID:27439676

  3. Toxicity, sublethal effects, and potential modes of action of select fungicides on freshwater fish and invertebrates

    Science.gov (United States)

    Elskus, Adria A.

    2012-01-01

    Despite decades of agricultural and urban use of fungicides and widespread detection of these pesticides in surface waters, relatively few data are available on the effects of fungicides on fish and invertebrates in the aquatic environment. Nine fungicides are reviewed in this report: azoxystrobin, boscalid, chlorothalonil, fludioxonil, myclobutanil, fenarimol, pyraclostrobin, pyrimethanil, and zoxamide. These fungicides were identified as emerging chemicals of concern because of their high or increasing global use rates, detection frequency in surface waters, or likely persistence in the environment. A review of the literature revealed significant sublethal effects of fungicides on fish, aquatic invertebrates, and ecosystems, including zooplankton and fish reproduction, fish immune function, zooplankton community composition, metabolic enzymes, and ecosystem processes, such as leaf decomposition in streams, among other biological effects. Some of these effects can occur at fungicide concentrations well below single-species acute lethality values (48- or 96-hour concentration that effects a response in 50 percent of the organisms, that is, effective concentration killing 50 percent of the organisms in 48 or 96 hours) and chronic sublethal values (for example, 21-day no observed adverse effects concentration), indicating that single-species toxicity values may dramatically underestimate the toxic potency of some fungicides. Fungicide modes of toxic action in fungi can sometimes reflect the biochemical and (or) physiological effects of fungicides observed in vertebrates and invertebrates; however, far more studies are needed to explore the potential to predict effects in nontarget organisms based on specific fungicide modes of toxic action. Fungicides can also have additive and (or) synergistic effects when used with other fungicides and insecticides, highlighting the need to study pesticide mixtures that occur in surface waters. For fungicides that partition to

  4. A potential amyloid-imaging probe for Alzheimer's disease

    International Nuclear Information System (INIS)

    sequencing data demonstrated that the gene was consisted of 768 bp and the deduced amino acids sequence confirmed its typical antibody structure. After cloning the antibody gene into the protokayotic system, the His6-tagged single-chain antibody was expressed as the expected size. The SDS-PAGE, Western blotting and ELISA testing demonstrated that the single-chain antibody we purified from the inclusion bodies is pure and active. Conclusions: After five rounds of bio-panning and subsequently serial ELISA testing, the specific antibody clones against amyloid β peptide 40 were screened out successfully. The binding epitope of the antibody from the 5 clones was between first to sixteenth amino acids at amino-end of amyloid β peptide 40. The His6-tagged was expressed and purified as an active form, which is a potential amyloid imaging probe for Alzheimer's disease. (authors)

  5. Radioactive smart probe for potential corrected matrix metalloproteinase imaging.

    Science.gov (United States)

    Huang, Chiun-Wei; Li, Zibo; Conti, Peter S

    2012-11-21

    Although various activatable optical probes have been developed to visualize metalloproteinase (MMP) activities in vivo, precise quantification of the enzyme activity is limited due to the inherent scattering and attenuation (limited depth penetration) properties of optical imaging. In this investigation, a novel activatable peptide probe (64)Cu-BBQ650-PLGVR-K(Cy5.5)-E-K(DOTA)-OH was constructed to detect tumor MMP activity in vivo. This agent is optically quenched in its native form, but releases strong fluorescence upon cleavage by selected enzymes. MMP specificity was confirmed both in vitro and in vivo by fluorescent imaging studies. The use of a single modality to image biomarkers/processes may lead to erroneous interpretation of imaging data. The introduction of a quantitative imaging modality, such as PET, would make it feasible to correct the enzyme activity determined from optical imaging. In this proof of principle report, we demonstrated the feasibility of correcting the activatable optical imaging data through the PET signal. This approach provides an attractive new strategy for accurate imaging of MMP activity, which may also be applied for other protease imaging. PMID:23025637

  6. Facilitating Youth to Take Sustainability Actions: The Potential of Peer Education

    Science.gov (United States)

    de Vreede, Catherine; Warner, Alan; Pitter, Robert

    2014-01-01

    Peer education is an understudied yet valuable strategy for sustainability educators in shifting youth to take action for sustainability. This case study conceptualizes the change process in facilitating youth to take sustainability actions, and explores the benefits, dynamics, and challenges of peer education as a strategy in facilitating change.…

  7. Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids.

    Science.gov (United States)

    Covey, Dan P; Bunner, Kendra D; Schuweiler, Douglas R; Cheer, Joseph F; Garris, Paul A

    2016-06-01

    The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement

  8. A Review on Potential Issues and Challenges in MR Imaging

    Directory of Open Access Journals (Sweden)

    Srinivasan Kathiravan

    2013-01-01

    Full Text Available Magnetic resonance imaging is a noninvasive technique that has been developed for its excellent depiction of soft tissue contrasts. Instruments capable of ultra-high field strengths, ≥7 Tesla, were recently engineered and have resulted in higher signal-to-noise and higher resolution images. This paper presents various subsystems of the MR imaging systems like the magnet subsystem, gradient subsystem, and also various issues which arise due to the magnet. Further, it also portrays finer details about the RF coils and transceiver and also various limitations of the RF coils and transceiver. Moreover, the concept behind the data processing system and the challenges related to it were also depicted. Finally, the various artifacts associated with the MR imaging were clearly pointed out. It also presents a brief overview about all the challenges related to MR imaging systems.

  9. Automated image analysis with the potential for process quality control applications in stem cell maintenance and differentiation.

    Science.gov (United States)

    Smith, David; Glen, Katie; Thomas, Robert

    2016-01-01

    The translation of laboratory processes into scaled production systems suitable for manufacture is a significant challenge for cell based therapies; in particular there is a lack of analytical methods that are informative and efficient for process control. Here the potential of image analysis as one part of the solution to this issue is explored, using pluripotent stem cell colonies as a valuable and challenging exemplar. The Cell-IQ live cell imaging platform was used to build image libraries of morphological culture attributes such as colony "edge," "core periphery" or "core" cells. Conventional biomarkers, such as Oct3/4, Nanog, and Sox-2, were shown to correspond to specific morphologies using immunostaining and flow cytometry techniques. Quantitative monitoring of these morphological attributes in-process using the reference image libraries showed rapid sensitivity to changes induced by different media exchange regimes or the addition of mesoderm lineage inducing cytokine BMP4. The imaging sample size to precision relationship was defined for each morphological attribute to show that this sensitivity could be achieved with a relatively low imaging sample. Further, the morphological state of single colonies could be correlated to individual colony outcomes; smaller colonies were identified as optimum for homogenous early mesoderm differentiation, while larger colonies maintained a morphologically pluripotent core. Finally, we show the potential of the same image libraries to assess cell number in culture with accuracy comparable to sacrificial digestion and counting. The data supports a potentially powerful role for quantitative image analysis in the setting of in-process specifications, and also for screening the effects of process actions during development, which is highly complementary to current analysis in optimization and manufacture.

  10. Effect of knockout of α2δ-1 on action potentials in mouse sensory neurons.

    Science.gov (United States)

    Margas, Wojciech; Ferron, Laurent; Nieto-Rostro, Manuela; Schwartz, Arnold; Dolphin, Annette C

    2016-08-01

    Gene deletion of the voltage-gated calcium channel auxiliary subunit α2δ-1 has been shown previously to have a cardiovascular phenotype, and a reduction in mechano- and cold sensitivity, coupled with delayed development of neuropathic allodynia. We have also previously shown that dorsal root ganglion (DRG) neuron calcium channel currents were significantly reduced in α2δ-1 knockout mice. To extend our findings in these sensory neurons, we have examined here the properties of action potentials (APs) in DRG neurons from α2δ-1 knockout mice in comparison to their wild-type (WT) littermates, in order to dissect how the calcium channels that are affected by α2δ-1 knockout are involved in setting the duration of individual APs and their firing frequency. Our main findings are that there is reduced Ca(2+) entry on single AP stimulation, particularly in the axon proximal segment, reduced AP duration and reduced firing frequency to a 400 ms stimulation in α2δ-1 knockout neurons, consistent with the expected role of voltage-gated calcium channels in these events. Furthermore, lower intracellular Ca(2+) buffering also resulted in reduced AP duration, and a lower frequency of AP firing in WT neurons, mimicking the effect of α2δ-1 knockout. By contrast, we did not obtain any consistent evidence for the involvement of Ca(2+)-activation of large conductance calcium-activated potassium (BK) and small conductance calcium-activated potassium (SK) channels in these events. In conclusion, the reduced Ca(2+) elevation as a result of single AP stimulation is likely to result from the reduced duration of the AP in α2δ-1 knockout sensory neurons.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'. PMID:27377724

  11. Effects of estragole on the compound action potential of the rat sciatic nerve

    Directory of Open Access Journals (Sweden)

    J.H. Leal-Cardoso

    2004-08-01

    Full Text Available Estragole, a relatively nontoxic terpenoid ether, is an important constituent of many essential oils with widespread applications in folk medicine and aromatherapy and known to have potent local anesthetic activity. We investigated the effects of estragole on the compound action potential (CAP of the rat sciatic nerve. The experiments were carried out on sciatic nerves dissected from Wistar rats. Nerves, mounted in a moist chamber, were stimulated at a frequency of 0.2 Hz, with electric pulses of 50-100-µs duration at 10-20 V, and evoked CAP were monitored on an oscilloscope and recorded on a computer. CAP control parameters were: peak-to-peak amplitude (PPA, 9.9 ± 0.55 mV (N = 15, conduction velocity, 92.2 ± 4.36 m/s (N = 15, chronaxy, 45.6 ± 3.74 µs (N = 5, and rheobase, 3.9 ± 0.78 V (N = 5. Estragole induced a dose-dependent blockade of the CAP. At 0.6 mM, estragole had no demonstrable effect. At 2.0 and 6.0 mM estragole, PPA was significantly reduced at the end of 180-min exposure of the nerve to the drug to 85.6 ± 3.96 and 13.04 ± 1.80% of control, respectively. At 4.0 mM, estragole significantly altered PPA, conduction velocity, chronaxy, and rheobase (P <= 0.05, ANOVA; N = 5 to 49.3 ± 6.21 and 77.7 ± 3.84, 125.9 ± 10.43 and 116.7 ± 4.59%, of control, respectively. All of these effects developed slowly and were reversible upon a 300-min wash-out. The data show that estragole dose-dependently blocks nerve excitability.

  12. Natural cures for type 1 diabetes: a review of phytochemicals, biological actions, and clinical potential.

    Science.gov (United States)

    Chang, C L T; Chen, Yi-Ching; Chen, Hui-Ming; Yang, Ning-Sun; Yang, Wen-Chin

    2013-01-01

    Autoimmune diseases are the third largest category of illness in the industrialized world, following cardiovascular diseases and cancers. Among them, type 1 diabetes, also named autoimmune diabetes, afflicts 10 million people worldwide. This disease is caused by autoimmunity-mediated destruction of pancreatic β-cells, leading to insulin deficiency, hyperglycemia and complications. Currently, there is no cure for type 1 diabetes. Insulin injection is the only medication; however, it accompanies serious medical complications. Current strategies to cure type 1 diabetes include immunotherapy, replacement therapy, and combination therapy. Despite recent advances in anti-diabetic strategies, no strategy is clinically successful. How to cure type 1 diabetes without undesirable side effects still remains a formidable challenge in drug research and development. Plants provide an extraordinary source of natural medicines for different diseases. Moreover, secondary metabolites of plant origin serve as an invaluable chemical library for drug discovery and current medicinal chemistry in the pharmaceutical industry. Over the past 25 years, 50% of prescription drugs have been developed from natural products and their derivatives. In this article, we review more than 20 plant compounds and extracts reported in the literature to prevent and treat type-1 diabetes. Emphasis is placed on their chemistry and biology in terms of regulation of immune cells and pancreatic β-cells. We summarize recent progress in understanding the biological actions, mechanisms and therapeutic potential of the compounds and extracts of plant origin in type 1 diabetes. New views on phytocompound-based strategies for prevention and treatment of type 1 diabetes are also discussed. PMID:23210779

  13. Acute alterations of somatodendritic action potential dynamics in hippocampal CA1 pyramidal cells after kainate-induced status epilepticus in mice.

    Directory of Open Access Journals (Sweden)

    Daniel Minge

    Full Text Available Pathophysiological remodeling processes at an early stage of an acquired epilepsy are critical but not well understood. Therefore, we examined acute changes in action potential (AP dynamics immediately following status epilepticus (SE in mice. SE was induced by intraperitoneal (i.p. injection of kainate, and behavioral manifestation of SE was monitored for 3-4 h. After this time interval CA1 pyramidal cells were studied ex vivo with whole-cell current-clamp and Ca(2+ imaging techniques in a hippocampal slice preparation. Following acute SE both resting potential and firing threshold were modestly depolarized (2-5 mV. No changes were seen in input resistance or membrane time constant, but AP latency was prolonged and AP upstroke velocity reduced following acute SE. All cells showed an increase in AP halfwidth and regular (rather than burst firing, and in a fraction of cells the notch, typically preceding spike afterdepolarization (ADP, was absent following acute SE. Notably, the typical attenuation of backpropagating action potential (b-AP-induced Ca(2+ signals along the apical dendrite was strengthened following acute SE. The effects of acute SE on the retrograde spread of excitation were mimicked by applying the Kv4 current potentiating drug NS5806. Our data unveil a reduced somatodendritic excitability in hippocampal CA1 pyramidal cells immediately after acute SE with a possible involvement of both Na(+ and K(+ current components.

  14. Inter-subject variability in human atrial action potential in sinus rhythm versus chronic atrial fibrillation.

    Directory of Open Access Journals (Sweden)

    Carlos Sánchez

    Full Text Available Human atrial electrophysiology exhibits high inter-subject variability in both sinus rhythm (SR and chronic atrial fibrillation (cAF patients. Variability is however rarely investigated in experimental and theoretical electrophysiological studies, thus hampering the understanding of its underlying causes but also its implications in explaining differences in the response to disease and treatment. In our study, we aim at investigating the ability of populations of human atrial cell models to capture the inter-subject variability in action potential (AP recorded in 363 patients both under SR and cAF conditions.Human AP recordings in atrial trabeculae (n = 469 from SR and cAF patients were used to calibrate populations of computational SR and cAF atrial AP models. Three populations of over 2000 sampled models were generated, based on three different human atrial AP models. Experimental calibration selected populations of AP models yielding AP with morphology and duration in range with experimental recordings. Populations using the three original models can mimic variability in experimental AP in both SR and cAF, with median conductance values in SR for most ionic currents deviating less than 30% from their original peak values. All cAF populations show similar variations in G(K1, G(Kur and G(to, consistent with AF-related remodeling as reported in experiments. In all SR and cAF model populations, inter-subject variability in I(K1 and I(NaK underlies variability in APD90, variability in I(Kur, I(CaL and I(NaK modulates variability in APD50 and combined variability in Ito and I(Kur determines variability in APD20. The large variability in human atrial AP triangulation is mostly determined by I(K1 and either I(NaK or I(NaCa depending on the model.Experimentally-calibrated human atrial AP models populations mimic AP variability in SR and cAF patient recordings, and identify potential ionic determinants of inter-subject variability in human atrial AP

  15. Synthesis of a dendritic estrogen cluster: A potential tool for studies of nuclear versus extranuclear pathways of estrogen actions

    Institute of Scientific and Technical Information of China (English)

    Jian Chen; Hu Zheng; Yan Song; Yu Feng Liang; Qing Rong Qi

    2012-01-01

    A novel estrogen dendrimer has been synthesized through a combination of divergent and convergent approaches in 9 practical steps and in good yields.It was characterized and confirmed by elemental analysis,FT-IR,MS,1H NMR,13C NMR.The dendrimer contains 16 estrone units and is potentially a useful tool for the studies of estrogen actions.

  16. Flattening of the electrocardiographic T-wave is a sign of proarrhythmic risk and a reflection of action potential triangulation

    DEFF Research Database (Denmark)

    Bhuiyan, Tanveer Ahmed; Graff, Claus; Kanters, J.K.;

    2013-01-01

    Drug-induced triangulation of the cardiac action potential is associated with increased risk of arrhythmic events. It has been suggested that triangulation causes a flattening of the electrocardiographic T-wave but the relationship between triangulation, T-wave flattening and onset of arrhythmia...

  17. Determination of the onset of beta-methyl-digoxin action by potentiation of the adenosine response in guinea pigs.

    Directory of Open Access Journals (Sweden)

    Fukuda,Tamotsu

    1985-06-01

    Full Text Available The onset of beta-methyl-digoxin action was investigated by the potentiation of the adenosine response in guinea pigs and rats, and compared with that of digoxin and dipyridamole. A number of i.v. infusions of adenosine were given to determine the mean control adenosine response and its 95% confidence limits. After oral administration of the drugs, successive infusions of adenosine were continued until a drug-induced potentiation of the adenosine response was observed. The time of appearance of the potentiated adenosine response was marked as the onset of action of the drugs. The onset of action in guinea pigs was 9 to 12 min for 0.2 to 0.4 mg/kg of beta-methyl-digoxin, 90 to 100 min for 0.2 mg/kg of digoxin and 25 min for 5 mg/kg of dipyridamole. The maximal potentiation was 48.8 to 53.8% at 18 to 21 min for beta-methyl-digoxin, 74.5% at 130 min for digoxin and 74.8% at 80 min for dipyridamole. Adenosine infused i.v. into rats produced heart block, as in guinea pigs. However, in rats, the adenosine response was not potentiated by beta-methyl-digoxin and digoxin. Dipyridamole at a dose as high as 200 mg/kg produced 25.8% potentiation at 36 min after oral administration to rats.

  18. Assessing the Potential Impact of a Nationwide Class-Based Affirmative Action System

    OpenAIRE

    Xiang, Alice; Rubin, Donald B.

    2015-01-01

    We examine the possible consequences of a change in law school admissions in the United States from an affirmative action system based on race to one based on socioeconomic class. Using data from the 1991-1996 Law School Admission Council Bar Passage Study, students were reassigned attendance by simulation to law school tiers by transferring the affirmative action advantage for black students to students from low socioeconomic backgrounds. The hypothetical academic outcomes for the students w...

  19. Antibacterial free fatty acids : activities, mechanisms of action and biotechnological potential

    OpenAIRE

    Desbois, Andrew Paul; Smith, Valerie Jane

    2010-01-01

    Amongst the diverse and potent biological activities of free fatty acids (FFAs) is the ability to kill or inhibit the growth of bacteria. The antibacterial properties of FFAs are used by many organisms to defend against parasitic or pathogenic bacteria. Whilst their antibacterial mode of action is still poorly understood, the prime target of FFA action is the cell membrane, where FFAs disrupt the electron transport chain and oxidative phosphorylation. Besides interfering with cellular energy ...

  20. Mode of action of Bacillus thuringiensis Cry and Cyt toxins and their potential for insect control

    OpenAIRE

    Bravo, Alejandra; Gill, Sarjeet S.; Soberón, Mario

    2006-01-01

    Bacillus thuringiensis Cry and Cyt protein families are a diverse group of proteins with activity against insects of different orders - Lepidoptera, Coleoptera, Diptera and also against other invertebrates such as nematodes. Their primary action is to lyse midgut epithelial cells by inserting into the target membrane and forming pores. Among this group of proteins, members of the 3-Domain Cry family are used worldwide for insect control, and their mode of action has been characterized in some...

  1. The afterhyperpolarizing potential following a train of action potentials is suppressed in an acute epilepsy model in the rat Cornu Ammonis 1 area.

    Science.gov (United States)

    Kernig, K; Kirschstein, T; Würdemann, T; Rohde, M; Köhling, R

    2012-01-10

    In hippocampal Cornu Ammonis 1 (CA1) neurons, a prolonged depolarization evokes a train of action potentials followed by a prominent afterhyperpolarizing potential (AHP), which critically dampens neuronal excitability. Because it is not known whether epileptiform activity alters the AHP and whether any alteration of the AHP is independent of inhibition, we acutely induced epileptiform activity by bath application of the GABA(A) receptor blocker gabazine (5 μM) in the rat hippocampal slice preparation and studied its impact on the AHP using intracellular recordings. Following 10 min of gabazine wash-in, slices started to develop spontaneous epileptiform discharges. This disinhibition was accompanied by a significant shift of the resting membrane potential of CA1 neurons to more depolarized values. Prolonged depolarizations (600 ms) elicited a train of action potentials, the number of which was not different between baseline and gabazine treatment. However, the AHP following the train of action potentials was significantly reduced after 20 min of gabazine treatment. When the induction of epileptiform activity was prevented by co-application of 6-cyano-7-nitroquinoxaline-2,3-dione disodium (CNQX, 10 μM) and D-(-)-2-amino-5-phosphonopentanoic acid (D-AP5, 50 μM) to block α-amino-3-hydroxy-5-methylisoxazolepropionate (AMPA) and N-methyl-d-aspartate (NMDA) receptors, respectively, the AHP was preserved despite of GABA(A) receptor inhibition suggesting that the epileptiform activity was required to suppress the AHP. Moreover, the AHP was also preserved when the slices were treated with the protein kinase blockers H-9 (100 μM) and H-89 (1 μM). These results demonstrate that the AHP following a train of action potentials is rapidly suppressed by acutely induced epileptiform activity due to a phosphorylation process-presumably involving protein kinase A.

  2. Potential dual imaging nanoparticle: Gd2O3 nanoparticle

    OpenAIRE

    Ahmad, Md. Wasi; Xu, Wenlong; Kim, Sung June; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Park, Ji Ae; Kim, Tae Jeong; Lee, Gang Ho

    2015-01-01

    Gadolinium (Gd) is a unique and powerful element in chemistry and biomedicine which can be applied simultaneously to magnetic resonance imaging (MRI), X-ray computed tomography (CT), and neutron capture therapy for cancers. This multifunctionality can be maximized using gadolinium oxide (Gd2O3) nanoparticles (GNPs) because of the large amount of Gd per GNP, making both diagnosis and therapy (i.e., theragnosis) for cancers possible using only GNPs. In this study, the T1 MRI and CT dual imaging...

  3. Potentiality and evocation in the meanings conveyed by the image

    Directory of Open Access Journals (Sweden)

    Solange Maria da Silva

    2013-08-01

    Full Text Available The aim of the investigation in this study was to understand how the evocation power is produced in an image and the influence of its incorporation into the meaning yielded by the visual content. A correlation was established between a list of properties drawn from these images, considering the end to which there are meant, and their ability to preserve the artistic appeal featured on them at the moment they were composed. Three key fundamentals were focused as presuppositions: a Nowadays, images are conveyed by the cultural industry in a frenetic and continuous path; b A great number of such images are capable of producing such an evocation power that can induce the viewer to changes in attitude, persuading him/her to uncontrolled consumerism and to standardization; c Others are capable of a considerable strength to evoke violence, through high dramatic and tragic contents. Data were collected from photography and pictorial works, sorted by criteria of their being built for a purpose. The analyses were effected by way of three correlations from their technical plasticity: image and a travel experience, image and urban chaos experience, image and aesthetic experience. The methodological procedures were built through the semiotic concepts as stated by the theory of signs by Charles S. Peirce and their dialogue with the notions of informativity, Jackobson?s language functions, and the constitution of poetic communication. The indications found in these images made it possible to infer on the presence of an immanent artistry that can either be responsible for instigating the receptor, as well as projecting him/her to the multiplicity of meanings found within the miscellaneous hybrid languages and styles typical of the complexity of contemporary society.

  4. Cardiovascular CT angiography in neonates and children : Image quality and potential for radiation dose reduction with iterative image reconstruction techniques

    NARCIS (Netherlands)

    Tricarico, Francesco; Hlavacek, Anthony M.; Schoepf, U. Joseph; Ebersberger, Ullrich; Nance, John W.; Vliegenthart, Rozemarijn; Cho, Young Jun; Spears, J. Reid; Secchi, Francesco; Savino, Giancarlo; Marano, Riccardo; Schoenberg, Stefan O.; Bonomo, Lorenzo; Apfaltrer, Paul

    2013-01-01

    To evaluate image quality (IQ) of low-radiation-dose paediatric cardiovascular CT angiography (CTA), comparing iterative reconstruction in image space (IRIS) and sinogram-affirmed iterative reconstruction (SAFIRE) with filtered back-projection (FBP) and estimate the potential for further dose reduct

  5. Governance issues, potentials and failures of participative collective action in the Kafue Flats, Zambia

    Directory of Open Access Journals (Sweden)

    Harry Nixon Chabwela

    2010-09-01

    2004 for creating by-laws based on initiatives of local staff of the Department of Fisheries, local interest groups and researchers. A broad local debate on how to manage the fisheries in a sustainable way and develop locally based by-laws for joint management of fisheries gives good potential for success and appears promising for the future of fisheries in Kafue Flats. Despite many difficulties it is an example of local collective action in order to scale up governance of common-pool resources.

  6. Effects of nerve growth factor on the action potential duration and repolarizing currents in a rabbit model of myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    Yun-Feng Lan; Yang Li; Jian-Cheng Zhang; Jin-Lao Gao; Xue-Ping Wang; Zhou Fang; Yi-Cheng Fu; Mei-Yan Chen; Min Lin; Qiao Xue

    2013-01-01

    Objectives To investigate the effect of nerve growth factor (NGF) on the action potential and potassium currents of non-infarcted myocardium in the myocardial infarcted rabbit model. Methods Rabbits with occlusion of the left anterior descending coronary artery were prepared and allowed to recover for eight weeks (healed myocardial infarction, HMI). During ligation surgery of the left coronary artery, a polyethylene tube was placed near the left stellate ganglion in the subcutis of the neck for the purpose of administering NGF 400 U/d for eight weeks (HMI + NGF group). Cardiomyocytes were isolated from regions of the non-infarcted left ventricular wall and the action potentials and ion currents in these cells were recorded using whole-cell patch clamps. Results Compared with HMI and control cardiomyocytes, significant prolongation of APD50 or APD90 (Action potential duration (APD) measured at 50% and 90% of repolarization) in HMI + NGF cardiomyocytes was found. The results showed that the 4-aminopyridine sensitive transient outward potassium current (Ito), the rapidly activated omponent of delayed rectifier potassium current (IKr), the slowly activated component of delayed rectifier potassium current (IKs), and the L-type calcium current (ICaL) were significantly altered in NGF + HMI cardiomyocytes compared with HMI and control cells. Conclusions Our results suggest that NGF treatment significantly prolongs APD in HMI cardiomyocytes and that a decrease in outward potassium currents and an increase of inward Ca2+ current are likely the underlying mechanism of action.

  7. MR imaging of the lungs. Clinical applications and potential research

    International Nuclear Information System (INIS)

    MR imaging of the lung is handicapped by three negative influences. First, the low proton spin density in lung tissue results in a low signal-to-noise ratio relative to the surrounding structures. Second, cardiac and respiratory motion induce artifacts that tend to obscure fine structural detail in the lung. Third, a considerable magnetic susceptibility gradient, arising from the large surface areas of air and tissue interfaces, produces a very low value for T2*. MR imaging can be used to stage the activity of interstitial lung disease and for the diagnosis of lipoid pneumonia and pulmonary infarction. In combination with MR angiography, perfusion MR imaging might eventually become a test for pulmonary embolisms. (authors)

  8. Potential of imaging spectroscopy as tool for pasture management

    NARCIS (Netherlands)

    Schut, A.G.T.; Lokhorst, C.; Hendriks, M.M.W.B.; Kornet, J.G.; Kasper, G.J.

    2005-01-01

    The use of imaging spectroscopy to predict the herbage mass of dry matter (DM), DM content of herbage and crude fibre, ash, total sugars and mineral (N, P, K, S, Ca, Mg, Mn, Zn and Fe) concentrations was evaluated. The experimental system used measured reflectance between 404 and 1650 nm at high spa

  9. The potential of imaging subsurface heterogeneities by local, natural earthquakes

    NARCIS (Netherlands)

    Nishitsuji, Y.; Doi, I.; Draganov, D.S.

    2014-01-01

    We have developed a new imaging technique of subsurface heterogeneities that uses Sp-waves from natural earthquakes. This technique can be used as a first screening tool in frontier exploration areas before conventional active exploration. Analyzing Sp-waves from 28 earthquakes (Mj 2.0 to 4.2) recor

  10. Radiolabeled Zn-DPA as a potential infection imaging agent

    International Nuclear Information System (INIS)

    Introduction: A zinc-dipicolylamine analog (Zn-DPA) conjugated with a fluorophore (PSVue®794) has been shown to image bacterial infections in mice. However, radiolabeled Zn-DPA has not previously been considered for nuclear imaging of infection. Methods: Both 111In-labeled DOTA-biotin and Zn-DPA-biotin were combined using streptavidin (SA) as a noncovalent linker. Mice injected intramuscularly with Streptococcus pyogenes (infection model) or with lipopolysaccharide (LPS) (inflammation model) were coinjected intravenously with 6 μg of DPA as PSVue794 and as 111In-DOTA-biotin/SA/biotin-Zn-DPA. Periodic fluorescent and SPECT (single photon emission computed tomography)/CT (computed tomography) images were acquired, and biodistributions were obtained at 22 h. Results: Histological examination confirmed the validity of both the infection and inflammation animal models. Both the whole-body optical and nuclear images showed obvious accumulations in the target thigh in both models at all time points. At 22 h, the average target thigh accumulation of 111In was 1.66%ID/g (S.D. 0.15) in the infection mice compared to 0.58%ID/g (S.D. 0.07) in the inflammation mice (P111In target/normal thigh ratio was 2.8 fold higher in the infection animals compared to the inflammation animals. Conclusions: These preliminary results show that Zn-DPA within streptavidin targets S. pyogenes-infected mice similarly to its free fluorescent analogue. The significantly higher accumulation in the live bacterial infection thigh compared to that of the LPS-induced inflammation thigh suggests that Zn-DPA may be a promising imaging agent to distinguish between bacterial infections and sterile inflammations.

  11. Potentiating action of propofol at GABAA receptors of retinal bipolar cells

    DEFF Research Database (Denmark)

    Yue, Lan; Xie, An; Bruzik, Karol S;

    2011-01-01

    specific retinal neurons. The authors investigated the action of propofol on GABA-elicited membrane current responses of retinal bipolar cells, which have both GABA(A) and GABA(C) receptors. Methods. Single, enzymatically dissociated bipolar cells obtained from rat retina were treated with propofol...

  12. Preparing Social Justice Oriented Teachers: The Potential Role of Action Research in the PDS

    Science.gov (United States)

    Dodman, Stephanie L.; Lai, Kerri; Campet, Melissa; Cavallero-Lotocki, Renee; Hopkins, Aaron; Onidi, Christine

    2014-01-01

    Deliberate investigation into practice is an essential of the National Association for Professional Development Schools' defining elements of a Professional Development School (PDS). This article reports on the pilot efforts of one PDS as it initiated deliberate investigation through action research with a small group of teacher candidates.…

  13. The Potential of General Classroom Observation: Turkish EFL Teachers' Perceptions, Sentiments, and Readiness for Action

    Science.gov (United States)

    Merç, Ali

    2015-01-01

    The purpose of this study was to determine Turkish EFL teachers' attitudes towards classroom observation. 204 teachers from different school settings responded to an online questionnaire. Data were analyzed according to three types of attitudes towards classroom observation: perceptions, sentiments, and readiness for action. The findings revealed…

  14. Mode of action of Bacillus thuringiensis Cry and Cyt toxins and their potential for insect control.

    Science.gov (United States)

    Bravo, Alejandra; Gill, Sarjeet S; Soberón, Mario

    2007-03-15

    Bacillus thuringiensis Crystal (Cry) and Cytolitic (Cyt) protein families are a diverse group of proteins with activity against insects of different orders--Lepidoptera, Coleoptera, Diptera and also against other invertebrates such as nematodes. Their primary action is to lyse midgut epithelial cells by inserting into the target membrane and forming pores. Among this group of proteins, members of the 3-Domain Cry family are used worldwide for insect control, and their mode of action has been characterized in some detail. Phylogenetic analyses established that the diversity of the 3-Domain Cry family evolved by the independent evolution of the three domains and by swapping of domain III among toxins. Like other pore-forming toxins (PFT) that affect mammals, Cry toxins interact with specific receptors located on the host cell surface and are activated by host proteases following receptor binding resulting in the formation of a pre-pore oligomeric structure that is insertion competent. In contrast, Cyt toxins directly interact with membrane lipids and insert into the membrane. Recent evidence suggests that Cyt synergize or overcome resistance to mosquitocidal-Cry proteins by functioning as a Cry-membrane bound receptor. In this review we summarize recent findings on the mode of action of Cry and Cyt toxins, and compare them to the mode of action of other bacterial PFT. Also, we discuss their use in the control of agricultural insect pests and insect vectors of human diseases. PMID:17198720

  15. Doubts about actions and flanker incongruity-related potentials and performance

    NARCIS (Netherlands)

    Tops, Mattie; Wijers, Albertus A.

    2012-01-01

    The brain networks that are involved in flanker incongruity and error processing are also consistently implicated in mental disorders such as obsessive compulsive disorder (OCD) that feature increased "Doubts about Actions" (DaA) scores. In the present study we investigated whether DaA scores, simil

  16. Quantum entanglement in the voltage dependent sodium channel can reproduce the salient features of neuronal action potential initiation

    CERN Document Server

    Summhammer, Johann

    2007-01-01

    We investigate the effects of a quantum entanglement regime within an ion conducting molecule (ion channel) of the neuronal plasma membrane on the onset dynamics of propagating nerve pulses (action potentials). In particular, we model the onset parameters of the sodium current in the Hodgkin Huxley equation as three similar but independent probabilistic mechanisms which become quantum entangled. The underlying physics is general and can involve entanglement between various degrees of freedom underlaying ion transition states or 'gating states' during conduction, e.g. Na$^+$ ions in different channel locations, or different 'affinity' states of ions with atoms lining the sub-regions of the channel protein ('filter-states'). We find that the 'quantum corrected' Hodgkin Huxley equation incorporating entangled systems states can reproduce action potential pulses with the critical onset dynamics observed recently in neocortical neurons in vivo by Naundorf et al. [Nature {\\bf 440}, 1060 (20 April 2006)]. Interestin...

  17. Morphological Characterization of the Action Potential Initiation Segment in GnRH Neuron Dendrites and Axons of Male Mice.

    Science.gov (United States)

    Herde, Michel K; Herbison, Allan E

    2015-11-01

    GnRH neurons are the final output neurons of the hypothalamic network controlling fertility in mammals. In the present study, we used ankyrin G immunohistochemistry and neurobiotin filling of live GnRH neurons in brain slices from GnRH-green fluorescent protein transgenic male mice to examine in detail the location of action potential initiation in GnRH neurons with somata residing at different locations in the basal forebrain. We found that the vast majority of GnRH neurons are bipolar in morphology, elaborating a thick (primary) and thinner (secondary) dendrite from opposite poles of the soma. In addition, an axon-like process arising predominantly from a proximal dendrite was observed in a subpopulation of GnRH neurons. Ankyrin G immunohistochemistry revealed the presence of a single action potential initiation zone ∼27 μm in length primarily in the secondary dendrite of GnRH neurons and located 30 to 140 μm distant from the cell soma, depending on the type of process and location of the cell body. In addition to dendrites, the GnRH neurons with cell bodies located close to hypothalamic circumventricular organs often elaborated ankyrin G-positive axon-like structures. Almost all GnRH neurons (>90%) had their action potential initiation site in a process that initially, or ultimately after a hairpin loop, was coursing in the direction of the median eminence. These studies indicate that action potentials are initiated in different dendritic and axonal compartments of the GnRH neuron in a manner that is dependent partly on the neuroanatomical location of the cell body.

  18. Neural Networks for Template Matching: Application to Real-Time Classification of the Action Potentials of Real Neurons

    OpenAIRE

    Wong, Yiu-fai; Banik, Jashojiban; Bower, James M.

    1988-01-01

    Much experimental study of real neural networks relies on the proper classification of extracellulary sampled neural signals (i .e. action potentials) recorded from the brains of experimental animals. In most neurophysiology laboratories this classification task is simplified by limiting investigations to single, electrically well-isolated neurons recorded one at a time. However, for those interested in sampling the activities of many single neurons simultaneously, waveform cla...

  19. Corticospinal neurons in macaque ventral premotor cortex with mirror properties: a potential mechanism for action suppression?

    Science.gov (United States)

    Kraskov, Alexander; Dancause, Numa; Quallo, Marsha M; Shepherd, Samantha; Lemon, Roger N

    2009-12-24

    The discovery of "mirror neurons" in area F5 of the ventral premotor cortex has prompted many theories as to their possible function. However, the identity of mirror neurons remains unknown. Here, we investigated whether identified pyramidal tract neurons (PTNs) in area F5 of two adult macaques exhibited "mirror-like" activity. About half of the 64 PTNs tested showed significant modulation of their activity while monkeys observed precision grip of an object carried out by an experimenter, with somewhat fewer showing modulation during precision grip without an object or grasping concealed from the monkey. Therefore, mirror-like activity can be transmitted directly to the spinal cord via PTNs. A novel finding is that many PTNs (17/64) showed complete suppression of discharge during action observation, while firing actively when the monkey grasped food rewards. We speculate that this suppression of PTN discharge might be involved in the inhibition of self-movement during action observation.

  20. Potential pathways of pesticide action on erectile function-a contributory factor in male infertility

    Institute of Scientific and Technical Information of China (English)

    RP Kaur; V Gupta; AF Christopher; P Bansal

    2015-01-01

    One of the important objectives of this manuscript is to focus on the place of erectile dysfunction as an important factor for infertility. The review is about correlating the indiscriminate use of pesticides and to find out and highlight the evidences for mechanism of action of these pesticides for erectile dysfunction and find out the most used and most dangerous pesticide from erectile dysfunction point of view. The review suggests that erectile dysfunction is having a significant place as a causal factor for infertility. Study infers that pesticides are having multiple mechanisms of action through which these cause erectile dysfunction. It also reflects that acetamiprid is having most devastating effect causing erectile dysfunction as it acts through multiple inhibitory pathways. The review successfully highlights the indiscriminate regional use of pesticides.

  1. Carnosine: can understanding its actions on energy metabolism and protein homeostasis inform its therapeutic potential?

    OpenAIRE

    Hipkiss, Alan R; Cartwright, Stephanie P.; Bromley, Clare; Gross, Stephane R.; Bill, Roslyn M.

    2013-01-01

    The dipeptide carnosine (β-alanyl-L-histidine) has contrasting but beneficial effects on cellular activity. It delays cellular senescence and rejuvenates cultured senescent mammalian cells. However, it also inhibits the growth of cultured tumour cells. Based on studies in several organisms, we speculate that carnosine exerts these apparently opposing actions by affecting energy metabolism and/or protein homeostasis (proteostasis). Specific effects on energy metabolism include the dipeptide’s ...

  2. A potential mode of action for Anakinra in patients with arthrofibrosis following total knee arthroplasty

    OpenAIRE

    David Dixon; Jonathon Coates; Alicia del Carpio Pons; Joanna Horabin; Andrew Walker; Nicole Abdul; Kalson, Nicholas S; Brewster, Nigel T.; Weir, David J.; Deehan, David J; Mann, Derek A.; Lee A Borthwick

    2015-01-01

    Arthrofibrosis is a fibroproliferative disease characterised by excessive deposition of extracellular matrix components intra-articularly leading to pain and restricted range of movement. Although frequently observed following total knee arthroplasty (TKA) no therapeutic options exist. A pilot study demonstrated that intra-articular injection of Anakinra, an IL-1R antagonist, improved range of movement and pain in patients with arthrofibrosis however the mechanism of action is unknown. We hyp...

  3. Reading Humboldt through the theory of communicative action: the democratic potential of symbolic interaction

    OpenAIRE

    McLuskie, Ed

    2015-01-01

    Wilhelm von Humboldt's studies of language during the nineteenth century anticipated twentieth-century symbolic interactionism, suggesting a two-century intellectual history stressing the communicating subject as an intersubjective actor. Jürgen Habermas's theory of communicative action, well known for its inclusion of George Herbert Mead's symbolic interactionism, appeals in the same breath to von Humboldt's work, thus inviting a critical re-appropriation of Mead beyond the social-psychologi...

  4. Reading Humboldt through the theory of communicative action: the democratic potential of symbolic interaction:

    OpenAIRE

    McLuskie, Ed

    2003-01-01

    Wilhelm von Humboldt's studies of language during the nineteenth century anticipated twentieth-century symbolic interactionism, suggesting a two-century intellectual history stressing the communicating subject as an intersubjective actor. Jürgen Habermas's theory of communicative action, well known for its inclusion of George Herbert Mead's symbolic interactionism, appeals in the same breath to von Humboldt's work, thus inviting a critical re-appropriation of Mead beyond the social-psychologi...

  5. Ventricular filling slows epicardial conduction and increases action potential duration in an optical mapping study of the isolated rabbit heart

    Science.gov (United States)

    Sung, Derrick; Mills, Robert W.; Schettler, Jan; Narayan, Sanjiv M.; Omens, Jeffrey H.; McCulloch, Andrew D.; McCullough, A. D. (Principal Investigator)

    2003-01-01

    INTRODUCTION: Mechanical stimulation can induce electrophysiologic changes in cardiac myocytes, but how mechanoelectric feedback in the intact heart affects action potential propagation remains unclear. METHODS AND RESULTS: Changes in action potential propagation and repolarization with increased left ventricular end-diastolic pressure from 0 to 30 mmHg were investigated using optical mapping in isolated perfused rabbit hearts. With respect to 0 mmHg, epicardial strain at 30 mmHg in the anterior left ventricle averaged 0.040 +/- 0.004 in the muscle fiber direction and 0.032 +/- 0.006 in the cross-fiber direction. An increase in ventricular loading increased average epicardial activation time by 25%+/- 3% (P myocardial perfusion or the presence of an electromechanical decoupling agent (butanedione monoxime) during optical mapping. CONCLUSION: Acute loading of the left ventricle of the isolated rabbit heart decreased apparent epicardial conduction velocity and increased action potential duration by a load-dependent mechanism that may not involve stretch-activated channels.

  6. Amplitude of sensory nerve action potential in early stage diabetic peripheral neuropathy:an analysis of 500 cases

    Institute of Scientific and Technical Information of China (English)

    Yunqian Zhang; Jintao Li; Tingjuan Wang; Jianlin Wang

    2014-01-01

    Early diagnosis of diabetic peripheral neuropathy is important for the successful treatment of diabetes mellitus. In the present study, we recruited 500 diabetic patients from the Fourth Afifl-iated Hospital of Kunming Medical University in China from June 2008 to September 2013: 221 cases showed symptoms of peripheral neuropathy (symptomatic group) and 279 cases had no symptoms of peripheral impairment (asymptomatic group). One hundred healthy control sub-jects were also recruited. Nerve conduction studies revealed that distal motor latency was longer, sensory nerve conduction velocity was slower, and sensory nerve action potential and amplitude of compound muscle action potential were signiifcantly lower in the median, ulnar, posterior tibial and common peroneal nerve in the diabetic groups compared with control subjects. More-over, the alterations were more obvious in patients with symptoms of peripheral neuropathy. Of the 500 diabetic patients, neural conduction abnormalities were detected in 358 cases (71.6%), among which impairment of the common peroneal nerve was most prominent. Sensory nerve abnormality was more obvious than motor nerve abnormality in the diabetic groups. The ampli-tude of sensory nerve action potential was the most sensitive measure of peripheral neuropathy. Our results reveal that varying degrees of nerve conduction changes are present in the early, as-ymptomatic stage of diabetic peripheral neuropathy.

  7. Complex Dynamic Thresholds and Generation of the Action Potentials in the Neural-Activity Model

    Science.gov (United States)

    Kirillov, S. Yu.; Nekorkin, V. I.

    2016-05-01

    This work is devoted to studying the processes of activation of the neurons whose excitation thresholds are not constant and vary in time (the so-called dynamic thresholds). The neuron dynamics is described by the FitzHugh-Nagumo model with nonlinear behavior of the recovery variable. The neuron response to the external pulsed activating action in the presence of a slowly varying synaptic current is studied within the framework of this model. The structure of the dynamic threshold is studied and its properties depending on the external-action parameters are established. It is found that the formation of the "folds" in the separatrix threshold manifold in the model phase space is a typical feature of the complex dynamic threshold. High neuron sensitivity to the action of the comparatively weak slow control signals is established. This explains the capability of the neurons to perform flexible tuning of their selective properties for detecting various external signals in sufficiently short times (of the order of duration of several spikes).

  8. Imaging when acting: picture but not word cues induce action-related biases of visual attention.

    Science.gov (United States)

    Wykowska, Agnieszka; Hommel, Bernhard; Schubö, Anna

    2012-01-01

    In line with the Theory of Event Coding (Hommel et al., 2001a), action planning has been shown to affect perceptual processing - an effect that has been attributed to a so-called intentional weighting mechanism (Wykowska et al., 2009; Memelink and Hommel, 2012), whose functional role is to provide information for open parameters of online action adjustment (Hommel, 2010). The aim of this study was to test whether different types of action representations induce intentional weighting to various degrees. To meet this aim, we introduced a paradigm in which participants performed a visual search task while preparing to grasp or to point. The to-be performed movement was signaled either by a picture of a required action or a word cue. We reasoned that picture cues might trigger a more concrete action representation that would be more likely to activate the intentional weighting of perceptual dimensions that provide information for online action control. In contrast, word cues were expected to trigger a more abstract action representation that would be less likely to induce intentional weighting. In two experiments, preparing for an action facilitated the processing of targets in an unrelated search task if they differed from distractors on a dimension that provided information for online action control. As predicted, however, this effect was observed only if action preparation was signaled by picture cues but not if it was signaled by word cues. We conclude that picture cues are more efficient than word cues in activating the intentional weighting of perceptual dimensions, presumably by specifying not only invariant characteristics of the planned action but also the dimensions of action-specific parameters.

  9. Imaging when acting: picture but not word cues induce action-related biases of visual attention

    Directory of Open Access Journals (Sweden)

    Agnieszka eWykowska

    2012-10-01

    Full Text Available In line with the Theory of Event Coding (Hommel et al., 2001, action planning has been shown to affect perceptual processing—an effect that has been attributed to a so-called intentional weighting mechanism (Memelink & Hommel, in press; Wykowska, Schubö, & Hommel, 2009, whose functional role is to provide information for open parameters of online action adjustment (Hommel, 2010. The aim of this study was to test whether different types of action representations induce intentional weighting to various degrees. To meet this aim, we introduced a paradigm in which participants performed a visual search task while preparing to grasp or to point. The to-be performed movement was signaled either by a picture of a required action or a word cue. We reasoned that picture cues might trigger a more concrete action representation that would be more likely to activate the intentional weighting of perceptual dimensions that provide information for online action control. In contrast, word cues were expected to trigger a more abstract action representation that would be less likely to induce intentional weighting. In two experiments, preparing for an action facilitated the processing of targets in an unrelated search task if they differed from distractors on a dimension that provided information for online action control. As predicted, however, this effect was observed only if action preparation was signaled by picture cues but not if it was signaled by word cues. We conclude that picture cues are more efficient than word cues in activating the intentional weighting of perceptual dimensions, presumably by specifying not only invariant characteristics of the planned action but also the dimensions of action-specific parameters.

  10. Imaging When Acting: Picture but Not Word Cues Induce Action-Related Biases of Visual Attention

    OpenAIRE

    AgnieszkaWykowska; BernhardHommel; AnnaSchubö

    2012-01-01

    In line with the Theory of Event Coding (Hommel et al., 2001), action planning has been shown to affect perceptual processing—an effect that has been attributed to a so-called intentional weighting mechanism (Memelink & Hommel, in press; Wykowska, Schubö, & Hommel, 2009), whose functional role is to provide information for open parameters of online action adjustment (Hommel, 2010). The aim of this study was to test whether different types of action representations induce intentio...

  11. Comparison of radiation dosimetry for several potential myocardial imaging agents

    International Nuclear Information System (INIS)

    Although myocardial imaging is currently dominated by Tl-201, several alternative agents with improved physiologic or radionuclidic properties have been proposed. Based on human and animal studies in the literature, the metabolism of several of these compounds was studied for the purpose of generating radiation dose estimates. Dose estimates are listed for several I-123-labeled free fatty acids, an I-123-labeled phosphonium compound, Rb-82, Cu-64, F-18 FDG (all compounds which are taken up by the normal myocardium), and for Tc-99m pyrophosphate (PYP) (which localizes in myocardial infarcts). Dose estimates could not be generated for C-11 palmitate, but his compound was included in a comparison of myocardial retention times. For the I-123-labeled compounds, I-124 was included as a contaminant in generating the dose estimates. Radiation doses were lowest for Rb-82 (gonads 0.3-0.4 Gy/MBq, kidneys 8.6 Gy/MBq). Doses for the I-123-labeled fatty acids were similar to one another, with IPPA being the lowest (gonads 15 Gy/MBq, heart wall 18 Gy/MBq). Doses for Tc-99m PYP were also low (gonads 4-7 Gy/MBq, heart wall 4 Gy/MBq, skeleton 15 Gy/MBq). The desirability of these compounds is discussed briefly, considering half-life, imaging mode and energy, and dosimetry, including a comparison of the effective whole body dose equivalents. 37 references, 11 tables

  12. Conservation laws of wave action and potential enstrophy for Rossby waves in a stratified atmosphere

    Science.gov (United States)

    Straus, D. M.

    1983-01-01

    The evolution of wave energy, enstrophy, and wave motion for atmospheric Rossby waves in a variable mean flow are discussed from a theoretical and pedagogic standpoint. In the absence of mean flow gradients, the wave energy density satisfies a local conservation law, with the appropriate flow velocity being the group velocity. In the presence of mean flow variations, wave energy is not conserved, but wave action is, provided the mean flow is independent of longitude. Wave enstrophy is conserved for arbitrary variations of the mean flow. Connections with Eliassen-Palm flux are also discussed.

  13. Optical imaging for the diagnosis of oral cancer and oral potentially malignant disorders

    Science.gov (United States)

    Yoshida, K.

    2016-03-01

    Optical Imaging is being conducted as a therapeutic non-invasive. Many kinds of the light source are selected for this purpose. Recently the oral cancer screening is conducted by using light-induced tissue autofluorescence examination such as several kinds of handheld devices. However, the mechanism of its action is still not clear. Therefore basic experimental research was conducted. One of auto fluorescence Imaging (AFI) device, VELscopeTM and near-infrared (NIR) fluorescence imaging using ICG-labeled antibody as a probe were compared using oral squamous cell carcinoma (OSCC) mouse models. The experiments revealed that intracutaneous tumor was successfully visualized as low density image by VELscopeTM and high density image by NIR image. In addition, VELscopeTM showed higher sensitivity and lower specificity than that of NIR fluorescence imaging and the sensitivity of identification of carcinoma areas with the VELscopeTM was good results. However, further more studies were needed to enhance the screening and diagnostic uses, sensitivity and specificity for detecting malignant lesions and differentiation from premalignant or benign lesions. Therefore, additional studies were conducted using a new developed near infrared (NIR) fluorescence imaging method targeting podoplanine (PDPN) which consists of indocyanine green (ICG)-labeled anti-human podoplanin antibody as a probe and IVIS imaging system or a handy realtime ICG imaging device that is overexpressed in oral malignant neoplasm to improve imaging for detection of early oral malignant neoplasm. Then evaluated for its sensitivity and specificity for detection of oral malignant neoplasm in xenografted mice model and compared with VELscopeTM. The results revealed that ICG fluorescence imaging method and VELscopeTM had the almost the same sensitivity for detection of oral malignant neoplasm. The current topics of optical imaging about oral malignant neoplasm were reviewed.

  14. Waveform Similarity Analysis: A Simple Template Comparing Approach for Detecting and Quantifying Noisy Evoked Compound Action Potentials.

    Directory of Open Access Journals (Sweden)

    Jason Robert Potas

    Full Text Available Experimental electrophysiological assessment of evoked responses from regenerating nerves is challenging due to the typical complex response of events dispersed over various latencies and poor signal-to-noise ratio. Our objective was to automate the detection of compound action potential events and derive their latencies and magnitudes using a simple cross-correlation template comparison approach. For this, we developed an algorithm called Waveform Similarity Analysis. To test the algorithm, challenging signals were generated in vivo by stimulating sural and sciatic nerves, whilst recording evoked potentials at the sciatic nerve and tibialis anterior muscle, respectively, in animals recovering from sciatic nerve transection. Our template for the algorithm was generated based on responses evoked from the intact side. We also simulated noisy signals and examined the output of the Waveform Similarity Analysis algorithm with imperfect templates. Signals were detected and quantified using Waveform Similarity Analysis, which was compared to event detection, latency and magnitude measurements of the same signals performed by a trained observer, a process we called Trained Eye Analysis. The Waveform Similarity Analysis algorithm could successfully detect and quantify simple or complex responses from nerve and muscle compound action potentials of intact or regenerated nerves. Incorrectly specifying the template outperformed Trained Eye Analysis for predicting signal amplitude, but produced consistent latency errors for the simulated signals examined. Compared to the trained eye, Waveform Similarity Analysis is automatic, objective, does not rely on the observer to identify and/or measure peaks, and can detect small clustered events even when signal-to-noise ratio is poor. Waveform Similarity Analysis provides a simple, reliable and convenient approach to quantify latencies and magnitudes of complex waveforms and therefore serves as a useful tool for

  15. Modulatory action of acetylcholine on the Na+-dependent action potentials in Kenyon cells isolated from the mushroom body of the cricket brain.

    Science.gov (United States)

    Terazima, E; Yoshino, M

    2010-12-01

    Kenyon cells, intrinsic neurons of the insect mushroom body, have been assumed to be a site of conditioning stimulus (CS) and unconditioned stimulus (US) association in olfactory learning and memory. Acetylcholine (ACh) has been implicated to be a neurotransmitter mediating CS reception in Kenyon cells, causing rapid membrane depolarization via nicotinic ACh receptors. However, the long-term effects of ACh on the membrane excitability of Kenyon cells are not fully understood. In this study, we examined the effects of ACh on Na(+) dependent action potentials (Na(+) spikes) elicited by depolarizing current injection and on net membrane currents under the voltage clamp condition in Kenyon cells isolated from the mushroom body of the cricket Gryllus bimaculatus. Current-clamp studies using amphotericin B perforated-patch recordings showed that freshly dispersed cricket Kenyon cells could produce repetitive Na(+) spikes in response to prolonged depolarizing current injection. Bath application of ACh increased both the instantaneous frequency and the amplitudes of Na(+) spikes. This excitatory action of ACh on Kenyon cells is attenuated by the pre-treatment of the cells with the muscarinic receptor antagonists, atropine and scopolamine, but not by the nicotinic receptor antagonist mecamylamine. Voltage-clamp studies further showed that bath application of ACh caused an increase in net inward currents that are sensitive to TTX, whereas outward currents were decreased by this treatment. These results indicate that in order to mediate CS, ACh may modulate the firing properties of Na(+) spikes of Kenyon cells through muscarinic receptor activation, thus increasing Na conductance and decreasing K conductance.

  16. Opposing actions of chronic Δ9-tetrahydrocannabinol and cannabinoid antagonists on hippocampal long-term potentiation

    OpenAIRE

    Hoffman, Alexander F; Oz, Murat; Yang, Ruiqin; Lichtman, Aron H.; Carl R Lupica

    2007-01-01

    Memory deficits produced by marijuana arise partly via interaction of the psychoactive component, Δ9-tetrahydrocannabinol (Δ9-THC), with cannabinoid receptors in the hippocampus. Although cannabinoids acutely reduce glutamate release and block hippocampal long-term potentiation (LTP), a potential substrate for learning and memory, the consequences of prolonged exposure to Δ9-THC for hippocampal function are poorly understood. Rats were injected with Δ9-THC (10 mg/kg, i.p., q.d.) for 1, 3, or ...

  17. Characterising action potential in virtual game worlds applied with the mind module

    OpenAIRE

    Eladhari, Mirjam Palosaari

    2009-01-01

    Because games set in persistent virtual game worlds (VGWs) have massive numbers of players, these games need methods of characterisation for playable characters (PCs) that differ from the methods used in traditional narrative media. VGWs have a number of particularly interesting qualities. Firstly, VGWs are places where players interact with and create elements carrying narrative potential. Secondly, players add goals, motives and driving forces to the narrative potential of a VGW, which some...

  18. Computational modeling of voltage-gated Ca channels inhibition: identification of different effects on uterine and cardiac action potentials

    Directory of Open Access Journals (Sweden)

    Wing Chiu eTong

    2014-10-01

    Full Text Available The uterus and heart share the important physiological feature whereby contractile activation of the muscle tissue is regulated by the generation of periodic, spontaneous electrical action potentials (APs. Preterm birth arising from premature uterine contractions is a major complication of pregnancy and there remains a need to pursue avenues of research that facilitate the use of drugs, tocolytics, to limit these inappropriate contractions without deleterious actions on cardiac electrical excitation. A novel approach is to make use of mathematical models of uterine and cardiac APs, which incorporate many ionic currents contributing to the AP forms, and test the cell-specific responses to interventions. We have used three such models – of uterine smooth muscle cells (USMC, cardiac sinoatrial node cells (SAN and ventricular cells – to investigate the relative effects of reducing two important voltage-gated Ca currents – the L-type (ICaL and T-type (ICaT Ca currents. Reduction of ICaL (10% alone, or ICaT (40% alone, blunted USMC APs with little effect on ventricular APs and only mild effects on SAN activity. Larger reductions in either current further attenuated the USMC APs but with also greater effects on SAN APs. Encouragingly, a combination of ICaL and ICaT reduction did blunt USMC APs as intended with little detriment to APs of either cardiac cell type. Subsequent overlapping maps of ICaL and ICaT inhibition profiles from each model revealed a range of combined reductions of ICaL and ICaT over which an appreciable diminution of USMC APs could be achieved with no deleterious action on cardiac SAN or ventricular APs. This novel approach illustrates the potential for computational biology to inform us of possible uterine and cardiac cell-specific mechanisms. Incorporating such computational approaches in future studies directed at designing new, or repurposing existing, tocolytics will be beneficial for establishing a desired uterine

  19. Assessing potential targets of calcium action in light-modulated gravitropism

    Science.gov (United States)

    Roux, S. J.

    1995-01-01

    Light, through the mediation of the pigment phytochrome, modulates the gravitropic response of the shoots and roots of many plants. The transduction of both light and gravity stimuli appears to involve Ca(2+)-regulated steps, one or more of which may represent points of intersection between the two transduction chains. To be confident that Ca2+ plays a critical role in stimulus-response coupling for gravitropism, it will be important to identify specific targets of Ca2+ action whose function can be clearly linked to the regulation of growth. Calcium typically exerts its influence on cell metabolism through binding to and activating key regulatory proteins. The three best characterized of these proteins in plants are the calmodulins, calcium-dependent protein kinases, and annexins. In this review we summarize what is known about the structure and function of these proteins and speculate on how their activation by Ca2+ could influence the differential growth response of gravitropism.

  20. 3D Seismic Imaging over a Potential Collapse Structure

    Science.gov (United States)

    Gritto, Roland; O'Connell, Daniel; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

    2016-04-01

    The Middle-East has seen a recent boom in construction including the planning and development of complete new sub-sections of metropolitan areas. Before planning and construction can commence, however, the development areas need to be investigated to determine their suitability for the planned project. Subsurface parameters such as the type of material (soil/rock), thickness of top soil or rock layers, depth and elastic parameters of basement, for example, comprise important information needed before a decision concerning the suitability of the site for construction can be made. A similar problem arises in environmental impact studies, when subsurface parameters are needed to assess the geological heterogeneity of the subsurface. Environmental impact studies are typically required for each construction project, particularly for the scale of the aforementioned building boom in the Middle East. The current study was conducted in Qatar at the location of a future highway interchange to evaluate a suite of 3D seismic techniques in their effectiveness to interrogate the subsurface for the presence of karst-like collapse structures. The survey comprised an area of approximately 10,000 m2 and consisted of 550 source- and 192 receiver locations. The seismic source was an accelerated weight drop while the geophones consisted of 3-component 10 Hz velocity sensors. At present, we analyzed over 100,000 P-wave phase arrivals and performed high-resolution 3-D tomographic imaging of the shallow subsurface. Furthermore, dispersion analysis of recorded surface waves will be performed to obtain S-wave velocity profiles of the subsurface. Both results, in conjunction with density estimates, will be utilized to determine the elastic moduli of the subsurface rock layers.

  1. Generation of slow wave type action potentials in the mouse small intestine involves a non-L-type calcium channel.

    Science.gov (United States)

    Malysz, J; Richardson, D; Farraway, L; Christen, M O; Huizinga, J D

    1995-10-01

    Intrinsic electrical activities in various isolated segments of the mouse small intestine were recorded (i) to characterize action potential generation and (ii) to obtain a profile on the ion channels involved in initiating the slow wave type action potentials (slow waves). Gradients in slow wave frequency, resting membrane potential, and occurrence of spiking activity were found, with the proximal intestine exhibiting the highest frequency, the most hyperpolarized cell membrane, and the greatest occurrence of spikes. The slow waves were only partially sensitive to L-type calcium channel blockers. Nifedipine, verapamil, and pinaverium bromide abolished spikes that occurred on the plateau phase of the slow waves in all tissues. The activity that remained in the presence of L-type calcium channel blockers, the upstroke potential, retained a similar amplitude to the original slow wave and was of identical frequency. The upstroke potential was not sensitive to a reduction in extracellular chloride or to the sodium channel blockers tetrodotoxin and mexiletine. Abolishment of the Na+ gradient by removal of 120 mM extracellular Na+ reduced the upstroke potential frequency by 13 - 18% and its amplitude by 50 - 70% in the ileum. The amplitude was similarly reduced by Ni2+ (up to 5 mM), and by flufenamic acid (100 mu M), a nonspecific cation and chloride channel blocker. Gadolinium, a nonspecific blocker of cation and stretch-activated channels, had no effect. Throughout these pharmacological manipulations, a robust oscillation remained at 5 - 10 mV. This oscillation likely reflects pacemaker activity. It was rapidly abolished by removal of extracellular calcium but not affected by L-type calcium channel blockers. In summary, the mouse small intestine has been established as a model for research into slow wave generation and electrical pacemaker activity. The upstroke part of the slow wave has two components, the pacemaker component involves a non-L-type calcium channel

  2. Bursting regimes in a reaction-diffusion system with action potential-dependent equilibrium.

    Directory of Open Access Journals (Sweden)

    Stephen R Meier

    Full Text Available The equilibrium Nernst potential plays a critical role in neural cell dynamics. A common approximation used in studying electrical dynamics of excitable cells is that the ionic concentrations inside and outside the cell membranes act as charge reservoirs and remain effectively constant during excitation events. Research into brain electrical activity suggests that relaxing this assumption may provide a better understanding of normal and pathophysiological functioning of the brain. In this paper we explore time-dependent ionic concentrations by allowing the ion-specific Nernst potentials to vary with developing transmembrane potential. As a specific implementation, we incorporate the potential-dependent Nernst shift into a one-dimensional Morris-Lecar reaction-diffusion model. Our main findings result from a region in parameter space where self-sustaining oscillations occur without external forcing. Studying the system close to the bifurcation boundary, we explore the vulnerability of the system with respect to external stimulations which disrupt these oscillations and send the system to a stable equilibrium. We also present results for an extended, one-dimensional cable of excitable tissue tuned to this parameter regime and stimulated, giving rise to complex spatiotemporal pattern formation. Potential applications to the emergence of neuronal bursting in similar two-variable systems and to pathophysiological seizure-like activity are discussed.

  3. Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors.

    Science.gov (United States)

    Lee, Sungmoo; Piao, Hong Hua; Sepheri-Rad, Masoud; Jung, Arong; Sung, Uhna; Song, Yoon-Kyu; Baker, Bradley J

    2016-02-04

    Genetically encoded voltage indicators (GEVIs) have improved to the point where they are beginning to be useful for in vivo recordings. While the ultimate goal is to image neuronal activity in vivo, one must be able to image activity of a single cell to ensure successful in vivo preparations. This procedure will describe how to image membrane potential in a single cell to provide a foundation to eventually image in vivo. Here we describe methods for imaging GEVIs consisting of a voltage-sensing domain fused to either a single fluorescent protein (FP) or two fluorescent proteins capable of Förster resonance energy transfer (FRET) in vitro. Using an image splitter enables the projection of images created by two different wavelengths onto the same charge-coupled device (CCD) camera simultaneously. The image splitter positions a second filter cube in the light path. This second filter cube consists of a dichroic and two emission filters to separate the donor and acceptor fluorescent wavelengths depending on the FPs of the GEVI. This setup enables the simultaneous recording of both the acceptor and donor fluorescent partners while the membrane potential is manipulated via whole cell patch clamp configuration. When using a GEVI consisting of a single FP, the second filter cube can be removed allowing the mirrors in the image splitter to project a single image onto the CCD camera.

  4. Adaptation decision-making in the Nordic Countries: assessing the potential for joint action

    DEFF Research Database (Denmark)

    Juhola, Sirkku; Goodsite, Michael Evan; Davis, Marion;

    2014-01-01

    and in precipitation, although regional variations can be significant. The countries’ robust institutions and economies give them a strong capacity to adapt to these changes. Still, the need for adaptation to the changing climate has been and still is substantial, and in most of the region, there has been progress...... on the issue. This paper explores the potential for Nordic cooperation on adaptation; specifically, for the development of a regional adaptation strategy. In particular, it addresses two questions (1) What is the current state of adaptation in the Nordic countries? and (2) What are the potential benefits...... and weaknesses of a Nordic strategy for adaptation? In order to answer these two questions, this paper examines reviews the current national adaptation policies of each Nordic country and discusses the challenges facing a Nordic strategy and finally assesses the potential for common Nordic adaptation policy...

  5. EFFECTS OF DESENSITIZATION AND REBOUND TO ADENOSINE ON ACTION POTENTIAL AND CONTRACTILITY IN ATRIAL CELLS IN GUINEA-PIGS

    Institute of Scientific and Technical Information of China (English)

    张凤杰; 臧伟进; 于晓江; 胡浩; 张春虹; 孙强; 吕军

    2002-01-01

    Objective To investigate the effects of desensitization and rebound to adenosine(Ado) on action potential duration(APD) and contractility in guinea-pig atrial cells. Methods Electrical activity was recorded using standard intracellular microelectrode technique and contractility was recorded using. We studied the effects of adenosine on the action potential and desensitization of contractility and rebound of contractility. Results The results showed that action potential duration were shortened by 1,10,100μmol*L-1Ado, the ratio of shortened APD was (9.58±1.40)%,(13.80±2.26)%,(24.80±3.19)%, respectively. 1μmol*L-1Ado had no desensitization (P>0.05), but the time of desensitization of 10μmol*L-1 Ado and 100μmol*L-1 Ado was 1 minute(P<0.05) and 5 minutes(P<0.05), respectively. The desensitization of contractility of 10*!μmol*L-1 Ado was obvious in atrial cells, the decrease of contractility of 10*!μmol*L-1 Ado was obvious in atrial cells, the decrease of contractility was changed from (31.4±16.04)%(2 minutes) to (50.60±15.87)% (4 minutes), compared with control. After washing out Ado, contractility was shown to rebound, the ratio of increase of contractility by 1,10,100μmol*L-1 Ado was (12.38±7.50)%,(19.00±8.14)% and (27.60±13.44)%, respectively. Conclusion Ado can abbreviate APD in atrial cells. The desensitization of Ado on APD is characterized by concentration-dependent and time-dependent in atrial cells, and the desensitization of contractility of Ado is obvious and contractility was shown to rebound after washing out Ado.

  6. Tracking motor unit action potentials in the tibialis anterior during fatigue.

    NARCIS (Netherlands)

    Beck, R.B.; O'Malley, M.J.; Stegeman, D.F.; Houtman, C.J.; Connolly, S.; Zwarts, M.J.

    2005-01-01

    New surface electromyogram (SEMG) techniques offer the potential to advance knowledge of healthy and diseased motor units. Conduction velocity (CV) estimates, obtained from indwelling electrodes, may provide diagnostic information, but the standard method of CV estimation from SEMG may be of only li

  7. Potential food applications of biobased materials. An EU- concerted action project

    DEFF Research Database (Denmark)

    Haugaard, V.K.; Udsen, A.M.; Mortensen, G.;

    2001-01-01

    The objective of the study was to ascertain the state of the art with regard to the applicability of biobased packaging materials to foods and to identify potential food applications for biobased materials. The study revealed relatively few examples of biobased materials used as primary, secondary...

  8. Motor unit action potential topography and its use in motor unit number estimation.

    NARCIS (Netherlands)

    Blok, J.H.; Dijk, J.P. van; Zwarts, M.J.; Stegeman, D.F.

    2005-01-01

    High-density multichannel electromyography (EMG) recordings add spatial information to the temporal information content of the surface EMG (sEMG) signal. This study explores the potential value of such multichannel information at a single motor unit level, in particular for the improvement of motor

  9. Immunomodulatory effects of fluoxetine: A new potential pharmacological action for a classic antidepressant drug?

    Science.gov (United States)

    Di Rosso, María Emilia; Palumbo, María Laura; Genaro, Ana María

    2016-07-01

    Selective serotonin reuptake inhibitors are frequently used antidepressants. In particular, fluoxetine is usually chosen for the treatment of the symptoms of depression, obsessive-compulsive, panic attack and bulimia nervosa. Antidepressant therapy has been associated with immune dysfunction. However, there is contradictory evidence about the effect of fluoxetine on the immune system. Experimental findings indicate that lymphocytes express the serotonin transporter. Moreover it has been shown that fluoxetine is able to modulate the immune function through a serotonin-dependent pathway and through a novel independent mechanism. In addition, several studies have shown that fluoxetine can alter tumor cell viability. Thus, it was recently demonstrated in vivo that chronic fluoxetine treatment inhibits tumor growth by increasing antitumor T-cell activity. Here we briefly review some of the literature referring to how fluoxetine is able to modify, for better or worse, the functionality of the immune system. These results of our analysis point to the relevance of the novel pharmacological action of this drug as an immunomodulator helping to treat several pathologies in which immune deficiency and/or deregulation is present. PMID:26644208

  10. Molecular actions and therapeutic potential of lithium in preclinical and clinical studies of CNS disorders

    OpenAIRE

    Chiu, Chi-Tso; Chuang, De-Maw

    2010-01-01

    Lithium has been used clinically to treat bipolar disorder for over half a century, and remains a fundamental pharmacological therapy for patients with this illness. Although lithium’s therapeutic mechanisms are not fully understood, substantial in vitro and in vivo evidence suggests that it has neuroprotective/neurotrophic properties against various insults, and considerable clinical potential for the treatment of several neurodegenerative conditions. Evidence from pharmacological and gene m...

  11. New European-wide cooperative action for the application of neutron imaging to the development of new materials

    Science.gov (United States)

    Chirco, Piero L.; Zanarini, Martina

    1999-10-01

    Neutron imagin techniques are known since a long time as a possible tool for non-destructive testings. However, they found a reduced number of applications out of the inspection of the nuclear fuel so that their diffusion was limited to some centers. This is particularly true in Europe because industries and the army are not used to carry out extensive programs for R and D in the field of NDT. A new European- wide cooperative action was agreed in order to solve this problem. This action is currently running under the COST framework of the European Commission and is comprised of excellence universities, nuclear centers and industries from 10 European countries. Main purpose of this action is the application of neutron imaging - non limiting to transmission radiography and tomography - to the development of advanced materials to be used in the fields of aerospace, civil engineering and mechanics. The initial cumulative results of this action will be presented; furthermore the possibilities for future enlargement of this activity to other European and non-European countries will be explained as well.

  12. Analysis for the Potential Function of the Digital Microstructure Image of Porous Media

    Institute of Scientific and Technical Information of China (English)

    XUYou-Sheng; LINJi; LIHua-Mei; WUPeng-Min

    2003-01-01

    Making use of the full information obtained in our previous discussions, a new analytical solutions for the potential function of the digital microstructure image of porous media is reported in this paper. It is demonstrated that the distribution of potential function depends on the zeroth order Bessel function. All these will be helpful for analyzing the similar subjects in porous media.

  13. The characteristics of action potential and nonselec-tive cation current of cardiomyocytes in rabbit superior vena cava

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    As a special focus in initiating and maintaining atrial fibrillation (AF), cardiomyocytes in superior vena cava (SVC) have distinctive electrophysiological characters. In this study, we found that comparing with the right atrial (RA) cardiomyoctyes, the SVC cardiomyoctyes had longer APD90 at the different basic cycle lengths; the conduction block could be observed on both RA and SVC cardiomyoctyes. A few of SVC cardiomyoctyes showed slow response action potentials with automatic activity and some others showed early afterdepolarization (EAD) spontaneously. Further more, we found that there are nonselective cation current (INs) in both SVC and RA cardiomyocytes. The peak density of INs in SVC cardiomyocytes was smaller than that in RA cardiomyocytes. Removal of extracellular divalent cation and glucose could increase INs in SVC cardiomyocytes. The agonist or the antagonist of INs may in-crease or decrease APD. To sum up, some SVC cardiomyocytes possess the ability of spontaneous activity; the difference of transmembrane action potentials between SVC and RA cardiomyocytes is partly because of the different density of INs between them; the agonist or the antagonist of INs can in-crease or decrease APD leading to the enhancement or reduction of EAD genesis in SVC cardiomyo-cytes. INs in rabbit myocytes is fairly similar to TRPC3 current in electrophysiological property, which might play an important role in the mechanisms of AF.

  14. Effects of rapid and slow potassium repolarization currents and calcium dynamics on hysteresis in restitution of action potential duration.

    Science.gov (United States)

    Wu, Runze; Patwardhan, Abhijit

    2007-04-01

    We used a mathematical model to investigate effects of repolarizing currents I(kr) and I(ks), calcium (Ca) current I(CaL), and Ca dynamics in network sarcoplasmic reticulum and junctional sarcoplasmic reticulum (JSR) on hysteresis in restitution of action potential duration. Enhanced I(kr) increased slope of restitution, hysteresis loop thickness, and delay between peaks of diastolic intervals and action potential duration. Increase in I(ks) decreased loop thickness and peak delay. Decrease in I(CaL) had effects similar to increasing I(kr), except slope of restitution decreased markedly. Uptake of Ca into the network sarcoplasmic reticulum had less effect on hysteresis than transfer of Ca into JSR. Faster transfer of Ca into JSR markedly decreased loop thickness and peak delay. Our results provide insight into mechanisms responsible for this newly identified property of restitution. Such information will be valuable in studies where modification of hysteresis is used to investigate its role in arrhythmogenesis. PMID:16895773

  15. Markov models of use-dependence and reverse use-dependence during the mouse cardiac action potential.

    Directory of Open Access Journals (Sweden)

    Qinlian Zhou

    Full Text Available The fast component of the cardiac transient outward current, I(Ktof, is blocked by a number of drugs. The major molecular bases of I(Ktof are Kv4.2/Kv4.3 voltage-gated potassium channels. Drugs with similar potencies but different blocking mechanisms have differing effects on action potential duration (APD. We used in silico analysis to determine the effect of I(Ktof-blocking drugs with different blocking mechanisms on mouse ventricular myocytes. We used our existing mouse model of the action potential, and developed 4 new Markov formulations for I(Ktof, I(Ktos, I(Kur, I(Ks. We compared effects of theoretical I(Ktof-specific channel blockers: (1 a closed state, and (2 an open channel blocker. At concentrations lower or close to IC(50, the drug which bound to the open state always had a much greater effect on APD than the drug which bound to the closed state. At concentrations much higher than IC(50, both mechanisms had similar effects at very low pacing rates. However, an open state binding drug had a greater effect on APD at faster pacing rates, particularly around 10 Hz. In summary, our data indicate that drug effects on APD are strongly dependent not only on IC(50, but also on the drug binding state.

  16. Effects of imidapril on heterogeneity of action potential and calcium current of ventriclar myocytes in infarcted rabbits

    Institute of Scientific and Technical Information of China (English)

    YangLI; QiaoXUE; JieMA; Cun-taiZHANG; PingQIU; LinWANG; WeiGAO; ReiCHENG; Zai-yinLU; Shi-wenWANG

    2004-01-01

    AIM: To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy. METHODS: Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks. Myocytes were isolated from subendocardial, midmyocardial, and subepicardial regions of the noninfarcted left ventricular wall. Action potentials and calcium current were recorded using whole-cell patch clamp technique. RESULTS: The action potential duration of repolarization 90 % (APD90) was more prolonged in midmyocardium rather than in subepicardium and subendocardium with healed myocardial infarction. The transmural dispersion of repolarization (TDR) was increased in the three ventricular regions. The amplitude of/Ca-L was enhanced but its density was decreased in noninfarcted ventricular myocytes due to increased cell membrane capacitance. The increased differences of calcium currents among subepicardium, midmyocardium, and subendocardium were also discovered. Normalization of heterogeneous changes in repolarization after treatment with imidapril was observed and decrease of TDR in noninfarcted area was measured. Early after depolarization (EAD) events of noninfarcted midmyocardium were markedly decreased by imidapril. CONCLUSION: Imidapril reduced the electrophysiologic heterogeneities in noninfarcted area in rabbits after myocardial infarction. This ability of imidapril may contribute to its antiarrhythmic efficacy.

  17. Effects of imidapril on heterogeneity of action potential and calcium current of ventriclar myocytes in infarcted rabbits

    Institute of Scientific and Technical Information of China (English)

    Yang LI; Shi-wen WANG; Qiao XUE; Jie MA; Cun-tai ZHANG; Ping QIU; Lin WANG; Wei GAO; Rei CHENG; Zai-ying LU

    2004-01-01

    AIM: To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy. METHODS: Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks.Myocytes were isolated from subendocardial, midmyocardial, and subepicardial regions of the noninfarcted left ventricular wall. Action potentials and calcium current were recorded using whole-cell patch clamp technique.RESULTS: The action potential duration of repolarization 90 % (APD90)was more prolonged in midmyocardium rather than in subepicardium and subendocardium with healed myocardial infarction. The transmural dispersion of repolarization (TDR) was increased in the three ventricular regions. The amplitude of ICa-L was enhanced but its density was decreased in noninfarcted ventricular myocytes due to increased cell membrane capacitance. The increased differences of calcium currents among subepicardium, midmyocardium, and subendocardium were also discovered. Normalization of heterogeneous changes in repolarization after treatment with imidapril was observed and decrease of TDR in noninfarcted area was measvred. Early after depolarization (EAD) events of noninfarcted midmyocardium were markedly decreased by imidapril. CONCLUSION: Imidapril reduced the electrophysiologic heterogeneities in noninfarcted area in rabbits after myocardial infarction. This ability of imidapril may contribute to its antiarrhythmic efficacy.

  18. Effects of changes in frequency on guinea pig ventricular action potential duration and on QT interval under different experimental conditions.

    Science.gov (United States)

    von Savigny, L; Hohnloser, S; Antoni, H

    1981-01-01

    Isolated perfused guinea pig hearts (Langendorff preparation) were arrested by carbachol (0.1-0.2 mg/l) and electrically stimulated in the region of the av-conducting system. The QT interval was determined by means of extracellular electrodes at different driving frequencies. Separate experiments were performed on papillary muscles from the right ventricle to measure the duration of the transmembrane action potential under comparable conditions. At 35 degrees C (Ke+ 5.4 mmol/l) increasing the frequency of stimulation (range 12-120/min) caused the action potential duration (APD) to decrease to a greater extent than the QT interval. Stepwise rising of the external K+ concentration up to 16.2 mmol/l produced a nearly parallel shift to the APD-frequency relation to lower values. Again, the QT interval was less affected by increasing the external K+ concentration than the APD. Stepwise reduction of the temperature down to 20 degrees C prolonged the APD as well as the QT interval, the effects being more pronounced at lower than at higher stimulation frequencies. Under all examined experimental conditions, the APD proved to be markedly shorter than the QT interval even when the latter is diminished by the duration of QRS. The results suggest that no close relation exists between the APD and the QT interval. The observed divergencies may be due to functional differences among various parts of the ventricles.

  19. Sensitivity of Rabbit Ventricular Action Potential and Ca2+ Dynamics to Small Variations in Membrane Currents and Ion Diffusion Coefficients

    Directory of Open Access Journals (Sweden)

    Yuan Hung Lo

    2013-01-01

    Full Text Available Little is known about how small variations in ionic currents and Ca2+ and Na+ diffusion coefficients impact action potential and Ca2+ dynamics in rabbit ventricular myocytes. We applied sensitivity analysis to quantify the sensitivity of Shannon et al. model (Biophys. J., 2004 to 5%–10% changes in currents conductance, channels distribution, and ion diffusion in rabbit ventricular cells. We found that action potential duration and Ca2+ peaks are highly sensitive to 10% increase in L-type Ca2+ current; moderately influenced by 10% increase in Na+-Ca2+ exchanger, Na+-K+ pump, rapid delayed and slow transient outward K+ currents, and Cl− background current; insensitive to 10% increases in all other ionic currents and sarcoplasmic reticulum Ca2+ fluxes. Cell electrical activity is strongly affected by 5% shift of L-type Ca2+ channels and Na+-Ca2+ exchanger in between junctional and submembrane spaces while Ca2+-activated Cl−-channel redistribution has the modest effect. Small changes in submembrane and cytosolic diffusion coefficients for Ca2+, but not in Na+ transfer, may alter notably myocyte contraction. Our studies highlight the need for more precise measurements and further extending and testing of the Shannon et al. model. Our results demonstrate usefulness of sensitivity analysis to identify specific knowledge gaps and controversies related to ventricular cell electrophysiology and Ca2+ signaling.

  20. Propagation of action potentials along complex axonal trees. Model and implementation.

    Science.gov (United States)

    Manor, Y; Gonczarowski, J; Segev, I

    1991-01-01

    Axonal trees are typically morphologically and physiologically complicated structures. Because of this complexity, axonal trees show a large repertoire of behavior: from transmission lines with delay, to frequency filtering devices in both temporal and spatial domains. Detailed theoretical exploration of the electrical behavior of realistically complex axonal trees is notably lacking, mainly because of the absence of a simple modeling tool. AXONTREE is an attempt to provide such a simulator. It is written in C for the SUN workstation and implements both a detailed compartmental modeling of Hodgkin and Huxley-like kinetics, and a more abstract, event-driven, modeling approach. The computing module of AXONTREE is introduced together with its input/output features. These features allow graphical construction of arbitrary trees directly on the computer screen, and superimposition of the results on the simulated structure. Several numerical improvements that increase the computational efficiency by a factor of 5-10 are presented; most notable is a novel method of dynamic lumping of the modeled tree into simpler representations ("equivalent cables"). AXONTREE's performance is examined using a reconstructed terminal of an axon from a Y cell in cat visual cortex. It is demonstrated that realistically complicated axonal trees can be handled efficiently. The application of AXONTREE for the study of propagation delays along axonal trees is presented in the companion paper (Manor et al., 1991). Images FIGURE 4 PMID:1777566

  1. Image potential resonances of the aluminum (100) surface; Bildpotentialresonanzen der Aluminium-(100)-Oberflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Winter, Matthias

    2011-07-08

    Image-potential resonances on the (100) surface of pure Aluminum are investigated experimentally and theoretically. The experiments are conducted both energy- and time-resolved using the method of two-photon photoemission spectroscopy. The main attention of the theoretical examination and extensive numerical calculations is devoted to the interaction between surface and bulk states. Image-potential resonances on Al(100) are a system in which a complete series of discrete Rydberg states strongly couples to a continuum of states. As a simple metal it also provides a good opportunity to test theoretical models of the structure of the potential at metal surfaces. This work represents the first high-resolution investigation of image-potential resonances with such strong resonance character. For the first time, it is demonstrated experimentally that isolated image-potential resonances exist on an Aluminum surface. On the (100) surface of Aluminum the second through fifth image-potential resonance are resolved and both, their energies and lifetimes are measured. The binding energies of the image-potential resonances form a Rydberg series of states {epsilon}{sub n}=-(0,85 eV)/((n+a){sup 2}). Within the accuracy of the measurement it is not necessary to introduce a quantum defect a (a=0.022{+-}0.035). Using angle-resolved two-photon photoemission spectroscopy the effective mass of electrons in the second image-potential resonance is measured to 1.01{+-}0.11 electron masses. The lifetimes of the resonances increase as {tau}{sub n} = (1.0{+-}0.2)fs.n{sup 3} starting from n=2. Calculations using the density matrix formalism show that the experimentally observed lifetimes can be explained well by electrons decaying into the bulk. The effect of resonance trapping leads to extended lifetimes in the process. Contrary to common theoretical models of image-potential states at metal surfaces the first image-potential resonance cannot be observed in two-photon photoemission on Al(100

  2. Cardiovascular CT angiography in neonates and children: Image quality and potential for radiation dose reduction with iterative image reconstruction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Tricarico, Francesco [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); Catholic University of the Sacred Heart, ' ' A. Gemelli' ' Hospital, Department of Bioimaging and Radiological Sciences, Rome (Italy); Hlavacek, Anthony M. [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); Children' s Hospital, Medical University of South Carolina, Division of Pediatric Cardiology, Charleston, SC (United States); Schoepf, U.J. [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); Children' s Hospital, Medical University of South Carolina, Division of Pediatric Cardiology, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Ebersberger, Ullrich [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); Heart Centre Munich-Bogenhausen, Department of Cardiology and Intensive Care Medicine, Munich (Germany); Nance, John W. [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); Johns Hopkins Hospital, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Vliegenthart, Rozemarijn [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); University Medical Centre Groningen/University of Groningen, Centre for Medical Imaging - North East Netherlands, Department of Radiology, Groningen (Netherlands); Cho, Young Jun [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); Konyang University School of Medicine, Department of Radiology, Daejeon (Korea, Republic of); Spears, J.R. [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); Secchi, Francesco [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Milan School of Medicine IRCCS Policlinico San Donato, Department of Medical and Surgical Sciences, Radiology Unit, Milan (Italy); Savino, Giancarlo; Marano, Riccardo; Bonomo, Lorenzo [Catholic University of the Sacred Heart, ' ' A. Gemelli' ' Hospital, Department of Bioimaging and Radiological Sciences, Rome (Italy); Schoenberg, Stefan O. [University Medical Centre Mannheim, Medical Faculty Mannheim - Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, Mannheim (Germany); Apfaltrer, Paul [Medical University of South Carolina, Ashley River Tower, Department of Radiology and Radiological Science, Charleston, SC (United States); University Medical Centre Mannheim, Medical Faculty Mannheim - Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, Mannheim (Germany)

    2013-05-15

    To evaluate image quality (IQ) of low-radiation-dose paediatric cardiovascular CT angiography (CTA), comparing iterative reconstruction in image space (IRIS) and sinogram-affirmed iterative reconstruction (SAFIRE) with filtered back-projection (FBP) and estimate the potential for further dose reductions. Forty neonates and children underwent low radiation CTA with or without ECG synchronisation. Data were reconstructed with FBP, IRIS and SAFIRE. For ECG-synchronised studies, half-dose image acquisitions were simulated. Signal noise was measured and IQ graded. Effective dose (ED) was estimated. Mean absolute and relative image noise with IRIS and full-dose SAFIRE was lower than with FBP (P < 0.001), while SNR and CNR were higher (P < 0.001). Image noise was also lower and SNR and CNR higher in half-dose SAFIRE studies compared with full-and half-dose FBP studies (P < 0.001). IQ scores were higher for IRIS, full-dose SAFIRE and half-dose SAFIRE than for full-dose FBP and higher for half-dose SAFIRE than for half-dose FBP (P < 0.05). Median weight-specific ED was 0.3 mSv without and 1.36 mSv with ECG synchronisation. The estimated ED of half-dose SAFIRE studies was 0.68 mSv. IR improves image noise, SNR, CNR and subjective IQ compared with FBP in low-radiation-dose paediatric CTA and allows further dose reductions without compromising diagnostic IQ. (orig.)

  3. Cardiovascular CT angiography in neonates and children: Image quality and potential for radiation dose reduction with iterative image reconstruction techniques

    International Nuclear Information System (INIS)

    To evaluate image quality (IQ) of low-radiation-dose paediatric cardiovascular CT angiography (CTA), comparing iterative reconstruction in image space (IRIS) and sinogram-affirmed iterative reconstruction (SAFIRE) with filtered back-projection (FBP) and estimate the potential for further dose reductions. Forty neonates and children underwent low radiation CTA with or without ECG synchronisation. Data were reconstructed with FBP, IRIS and SAFIRE. For ECG-synchronised studies, half-dose image acquisitions were simulated. Signal noise was measured and IQ graded. Effective dose (ED) was estimated. Mean absolute and relative image noise with IRIS and full-dose SAFIRE was lower than with FBP (P < 0.001), while SNR and CNR were higher (P < 0.001). Image noise was also lower and SNR and CNR higher in half-dose SAFIRE studies compared with full-and half-dose FBP studies (P < 0.001). IQ scores were higher for IRIS, full-dose SAFIRE and half-dose SAFIRE than for full-dose FBP and higher for half-dose SAFIRE than for half-dose FBP (P < 0.05). Median weight-specific ED was 0.3 mSv without and 1.36 mSv with ECG synchronisation. The estimated ED of half-dose SAFIRE studies was 0.68 mSv. IR improves image noise, SNR, CNR and subjective IQ compared with FBP in low-radiation-dose paediatric CTA and allows further dose reductions without compromising diagnostic IQ. (orig.)

  4. Imaging the potential distribution of charged adsorbates on graphene by low-energy electron holography

    CERN Document Server

    Latychevskaia, Tatiana; Escher, Conrad; Fink, Hans-Werner

    2016-01-01

    While imaging individual atoms can routinely be achieved in high resolution transmission electron microscopy, visualizing the potential distribution of individually charged adsorbates leading to a phase shift of the probing electron wave is still a challenging task. Since low-energy electrons are sensitive to localized potential gradients, we employed this tool in the 30 eV kinetic energy range to visualize the potential distribution of localized charged adsorbates present on free-standing graphene.

  5. MIF-1 potentiates the action of tricyclic antidepressants in an animal model of depression.

    Science.gov (United States)

    Kostowski, W; Danysz, W; Dyr, W; Jankowska, E; Krzaścik, P; Pałejko, W; Stefański, R; Płaźnik, A

    1991-01-01

    In the present paper, the effect of simultaneous treatment of rats with low doses of MIF-1 and tricyclic antidepressants on rat behavior in the forced swim test was studied. It was found that MIF-1 stimulated in a dose-dependent manner "active" behavior of animals in this paradigm. The effect of MIF-1 appeared to be independent of changes in rats' locomotion in the open field test. The combined treatment of rats with MIF-1 (0.01 mg/kg IP) and amitriptyline (5 mg/kg IP) or desipramine (1.25 mg/kg) IP) significantly stimulated active behavior in the forced swim test above the level obtained with each of the drugs given separately. The present data suggest the potential clinical efficacy of a combined therapy of depressive patients with MIF-1 and small doses of tricyclic antidepressants.

  6. 'Working' cardiomyocytes exhibiting plateau action potentials from human placenta-derived extraembryonic mesodermal cells.

    Science.gov (United States)

    Okamoto, Kazuma; Miyoshi, Shunichiro; Toyoda, Masashi; Hida, Naoko; Ikegami, Yukinori; Makino, Hatsune; Nishiyama, Nobuhiro; Tsuji, Hiroko; Cui, Chang-Hao; Segawa, Kaoru; Uyama, Taro; Kami, Daisuke; Miyado, Kenji; Asada, Hironori; Matsumoto, Kenji; Saito, Hirohisa; Yoshimura, Yasunori; Ogawa, Satoshi; Aeba, Ryo; Yozu, Ryohei; Umezawa, Akihiro

    2007-07-15

    The clinical application of cell transplantation for severe heart failure is a promising strategy to improve impaired cardiac function. Recently, an array of cell types, including bone marrow cells, endothelial progenitors, mesenchymal stem cells, resident cardiac stem cells, and embryonic stem cells, have become important candidates for cell sources for cardiac repair. In the present study, we focused on the placenta as a cell source. Cells from the chorionic plate in the fetal portion of the human placenta were obtained after delivery by the primary culture method, and the cells generated in this study had the Y sex chromosome, indicating that the cells were derived from the fetus. The cells potentially expressed 'working' cardiomyocyte-specific genes such as cardiac myosin heavy chain 7beta, atrial myosin light chain, cardiac alpha-actin by gene chip analysis, and Csx/Nkx2.5, GATA4 by RT-PCR, cardiac troponin-I and connexin 43 by immunohistochemistry. These cells were able to differentiate into cardiomyocytes. Cardiac troponin-I and connexin 43 displayed a discontinuous pattern of localization at intercellular contact sites after cardiomyogenic differentiation, suggesting that the chorionic mesoderm contained a large number of cells with cardiomyogenic potential. The cells began spontaneously beating 3 days after co-cultivation with murine fetal cardiomyocytes and the frequency of beating cells reached a maximum on day 10. The contraction of the cardiomyocytes was rhythmical and synchronous, suggesting the presence of electrical communication between the cells. Placenta-derived human fetal cells may be useful for patients who cannot supply bone marrow cells but want to receive stem cell-based cardiac therapy.

  7. Methanol extract of Tephrosia vogelii leaves potentiates the contractile action of acetylcholine on isolated rabbit jejunum

    Institute of Scientific and Technical Information of China (English)

    Tavershima Dzenda; Joseph Olusegun Ayo; Alexander Babatunde Adelaiye; Ambrose Osemattah Adaudi

    2015-01-01

    To investigate the modulating role of methanol extract of Tephrosia vogelii leaves on acetylcholine (ACh)-induced contraction of isolated rabbit jejunum. Methods: Rabbit jejunum segment was removed and placed in an organ bath containing Tyrode’s solution, and its contractions were recorded isometrically. Results: ACh (2.0 × 10-10 g/mL) and the extract (2.0 × 10-4 g/mL) individually increased the frequency of contraction (mean ± SEM) of the isolated smooth muscle tissue by 47.6% ± 9.5%and 77.8% ± 66.5%, respectively. When ACh and the extract were combined, the frequency of contraction of the tissue was increased by 222.2% ± 25.9%, representing a 366.7% increase (P < 0.001) over the effect of ACh alone. Similarly, ACh (2.0 × 10-9 g/mL) and the extract individually increased significantly (P < 0.001) the amplitude of contraction of the tissue by 685.7% ± 61.1% and 455.2% ± 38.1%, respectively. When ACh and the extract were combined, the amplitude of contraction of the tissue rose by 1263.8% ± 69.0%, representing 84.3% increase over the effect of ACh alone. Conclusions: The findings demonstrate that methanol extract of Tephrosia vogelii leaves potentiates the contractile effect of ACh on intestinal smooth muscle, supporting the traditional claim that the plant is purgative.

  8. Control of Postharvest Bacterial Soft Rot by Gamma Irradiation and its Potential Modes of Action

    Directory of Open Access Journals (Sweden)

    Rae-Dong Jeong

    2016-04-01

    Full Text Available Gamma irradiation was evaluated for its in vitro and in vivo antibacterial activity against a postharvest bacterial pathogen, Erwinia carotovora subsp. carotovora (Ecc. Gamma irradiation in a bacteria cell suspension resulted in a dramatic reduction of the viable counts as well as an increase in the amounts of DNA and protein released from the cells. Gamma irradiation showed complete inactivation of Ecc, especially at a dose of 0.6 kGy. In addition, scanning electron microscopy of irradiated cells revealed severe damage on the surface of most bacterial cells. Along with the morphological changes of cells by gamma irradiation, it also affected the membrane integrity in a dose-dependent manner. The mechanisms by which the gamma irradiation decreased the bacterial soft rot can be directly associated with the disruption of the cell membrane of the bacterial pathogen, along with DNA fragmentation, results in dose-dependent cell inactivation. These findings suggest that gamma irradiation has potential as an antibacterial approach to reduce the severity of the soft rot of paprika.

  9. Methanol extract of Tephrosia vogelii leaves potentiates the contractile action of acetylcholine on isolated rabbit jejunum

    Institute of Scientific and Technical Information of China (English)

    Tavershima; Dzenda; Joseph; Olusegun; Ayo; Alexander; Babatunde; Adelaiye; Ambrose; Osemattah; Adaudi

    2015-01-01

    Objective:To investigate the modulating role of methanol extract of Tephrosia vogelii leaves on acetylcholine(ACh)-induced contraction of isolated rabbit jejunum.Methods: Rabbit jejunum segment was removed and placed in an organ bath containing Tyrode’s solution, and its contractions were recorded isometrically.Results: ACh(2.0 × 10-10 g/m L) and the extract(2.0 × 10-4 g/m L) individually increased the frequency of contraction(mean ± SEM) of the isolated smooth muscle tissue by 47.6% ± 9.5% and 77.8% ± 66.5%, respectively. When ACh and the extract were combined, the frequency of contraction of the tissue was increased by 222.2% ± 25.9%, representing a 366.7% increase(P < 0.001) over the effect of ACh alone. Similarly, ACh(2.0 × 10-9 g/m L) and the extract individually increased significantly(P < 0.001) the amplitude of contraction of the tissue by 685.7% ± 61.1% and 455.2% ± 38.1%, respectively. When ACh and the extract were combined, the amplitude of contraction of the tissue rose by 1263.8% ± 69.0%, representing 84.3% increase over the ef ect of ACh alone. Conclusions: The findings demonstrate that methanol extract of Tephrosia vogelii leaves potentiates the contractile ef ect of ACh on intestinal smooth muscle, supporting the traditional claim that the plant is purgative.

  10. Microelectrode array recordings of cardiac action potentials as a high throughput method to evaluate pesticide toxicity.

    Science.gov (United States)

    Natarajan, A; Molnar, P; Sieverdes, K; Jamshidi, A; Hickman, J J

    2006-04-01

    The threat of environmental pollution, biological warfare agent dissemination and new diseases in recent decades has increased research into cell-based biosensors. The creation of this class of sensors could specifically aid the detection of toxic chemicals and their effects in the environment, such as pyrethroid pesticides. Pyrethroids are synthetic pesticides that have been used increasingly over the last decade to replace other pesticides like DDT. In this study we used a high-throughput method to detect pyrethroids by using multielectrode extracellular recordings from cardiac cells. The data from this cell-electrode hybrid system was compared to published results obtained with patch-clamp electrophysiology and also used as an alternative method to further understand pyrethroid effects. Our biosensor consisted of a confluent monolayer of cardiac myocytes cultured on microelectrode arrays (MEA) composed of 60 substrate-integrated electrodes. Spontaneous activity of these beating cells produced extracellular field potentials in the range of 100 microV to nearly 1200 microV with a beating frequency of 0.5-4 Hz. All of the tested pyrethroids; alpha-Cypermethrin, Tetramethrin and Tefluthrin, produced similar changes in the electrophysiological properties of the cardiac myocytes, namely reduced beating frequency and amplitude. The sensitivity of our toxin detection method was comparable to earlier patch-clamp studies, which indicates that, in specific applications, high-throughput extracellular methods can replace single-cell studies. Moreover, the similar effect of all three pyrethroids on the measured parameters suggests, that not only detection of the toxins but, their classification might also be possible with this method. Overall our results support the idea that whole cell biosensors might be viable alternatives when compared to current toxin detection methods. PMID:16198528

  11. Investigations on the usefulness of CEACAMs as potential imaging targets for molecular imaging purposes.

    Directory of Open Access Journals (Sweden)

    Markus Heine

    Full Text Available Members of the carcinoembryonic antigen cell adhesion molecules (CEACAMs family are the prototype of tumour markers. Classically they are used as serum markers, however, CEACAMs could serve as targets for molecular imaging as well.In order to test the anti CEACAM monoclonal antibody T84.1 for imaging purposes, CEACAM expression was analysed using this antibody. Twelve human cancer cell lines from different entities were screened for their CEACAM expression using qPCR, Western Blot and FACS analysis. In addition, CEACAM expression was analyzed in primary tumour xenografts of these cells. Nine of 12 tumour cell lines expressed CEACAM mRNA and protein when grown in vitro. Pancreatic and colon cancer cell lines showed the highest expression levels with good correlation of mRNA and protein level. However, when grown in vivo, the CEACAM expression was generally downregulated except for the melanoma cell lines. As the CEACAM expression showed pronounced expression in FemX-1 primary tumours, this model system was used for further experiments. As the accessibility of the antibody after i.v. application is critical for its use in molecular imaging, the binding of the T84.1 monoclonal antibody was assessed after i.v. injection into SCID mice harbouring a FemX-1 primary tumour. When applied i.v., the CEACAM specific T84.1 antibody bound to tumour cells in the vicinity of blood vessels. This binding pattern was particularly pronounced in the periphery of the tumour xenograft, however, some antibody binding was also observed in the central areas of the tumour around blood vessels. Still, a general penetration of the tumour by i.v. application of the anti CEACAM antibody could not be achieved despite homogenous CEACAM expression of all melanoma cells when analysed in tissue sections. This lack of penetration is probably due to the increased interstitial fluid pressure in tumours caused by the absence of functional lymphatic vessels.

  12. Savinase action on bovine serum albumin (BSA) monolayers demonstrated with measurements at the air-water interface and liquid Atomic Force Microscopy (AFM) imaging

    DEFF Research Database (Denmark)

    Balashev, Konstantin; Callisen, Thomas H; Svendsen, Allan;

    2011-01-01

    We studied the enzymatic action of Savinase on bovine serum albumin (BSA) organized in a monolayer spread at the air/water interface or adsorbed at the mica surface. We carried out two types of experiments. In the first one we followed the degradation of the protein monolayer by measuring...... the surface pressure and surface area decrease versus time. In the second approach we applied AFM imaging of the supported BSA monolayers adsorbed on mica solid supports and extracted information for the enzyme action by analyzing the obtained images of the surface topography in the course of enzyme action...

  13. Image processing for the rest of us: the potential utility of inexpensive computerized image analysis in clinical pathology and radiology.

    Science.gov (United States)

    McEachron, D L; Hess, S; Knecht, L B; True, L D

    1989-01-01

    Recent progress in computer technology in both hardware and software, combined with marked cost reductions, have placed quantitatively accurate video densitometry systems within the reach of the individual clinician, biomedical researcher, and community hospital. While much of the attention generated by advances in image processing has focussed on larger scale procedures, such as CAT, chemical shift, and positron emission tomography, important applications can be found for considerably more modest systems. In this article, we discuss three such applications of DUMAS, a personal computer-based imaging system developed by the Image Processing Center at Drexel University. A potential technique for quantifying numbers of estrogen receptors in tumorous breast tissue samples as a predictor of patient responsiveness to hormonal therapy is described first, along with possible sources of error. The second application, also related to clinical pathology and cancer, outlines methods for relating changes in nuclear and cell morphology to the diagnosis of Sezary Cell Syndrome. The utility of binary image filtering methods in the classification of cell types is discussed. The third application involves the development of a semi-automatic procedure for the determination of vessel diameter in arteriograms. A detailed description of the optimization and curve-fitting algorithms is provided along with preliminary test results comparing various approaches. The need for user demand to fuel research and development in small-scale imaging systems is also discussed. PMID:2647281

  14. Cordycepin Decreases Compound Action Potential Conduction of Frog Sciatic Nerve In Vitro Involving Ca2+-Dependent Mechanisms

    Directory of Open Access Journals (Sweden)

    Li-Hua Yao

    2015-01-01

    Full Text Available Cordycepin has been widely used in oriental countries to maintain health and improve physical performance. Compound nerve action potential (CNAP, which is critical in signal conduction in the peripheral nervous system, is necessary to regulate physical performance, including motor system physiological and pathological processes. Therefore, regulatory effects of cordycepin on CNAP conduction should be elucidated. In this study, the conduction ability of CNAP in isolated frog sciatic nerves was investigated. Results revealed that cordycepin significantly decreased CNAP amplitude and conductive velocity in a reversible and concentration-dependent manner. At 50 mg/L cordycepin, CNAP amplitude and conductive velocity decreased by 62.18 ± 8.06% and 57.34% ± 6.14% compared with the control amplitude and conductive velocity, respectively. However, the depressive action of cordycepin on amplitude and conductive velocity was not observed in Ca2+-free medium or in the presence of Ca2+ channel blockers (CdCl2/LaCl3. Pretreatment with L-type Ca2+ channel antagonist (nifedipine/deltiazem also blocked cordycepin-induced responses; by contrast, T-type and P-type Ca2+ channel antagonists (Ni2+ failed to block such responses. Therefore, cordycepin decreased the conduction ability of CNAP in isolated frog sciatic nerves via L-type Ca2+ channel-dependent mechanism.

  15. Potential Causes of Significant Inventory Differences at Bulk Handling Facilities and the Importance of Inventory Difference Action Levels

    International Nuclear Information System (INIS)

    Accountancy for nuclear material can be split into two categories. Firstly, where possible, accountancy should be in terms of items that can be transferred as discrete packages and their contents fixed at the time of their creation. All items must remain accounted for at all times, and a single missing item is considered significant. Secondly, where nuclear material is unconstrained, for example in a reprocessing plant where it can change form, there is an uncertainty that relates to the amount of material present in any location. Cumulatively, these uncertainties can be summed and provide a context for any estimate of material in a process. Any apparent loss or gain between what has been physically measured within a facility during its physical inventory take and what is reported within its nuclear material accounts is known as an inventory difference. The cumulative measurement uncertainties can be used to set an action level for the inventory difference so that if an inventory difference is observed outside of such action levels, the difference is classified as significant and an investigation to find the root cause(s) is required. The purpose of this paper is to explore the potential causes of significant inventory differences and to provide a framework within which an inventory difference investigation can be carried out.

  16. Promoting HIV Vaccine Research in African American Communities: Does the Theory of Reasoned Action Explain Potential Outcomes of Involvement?

    Science.gov (United States)

    Frew, Paula M; Archibald, Matthew; Martinez, Nina; del Rio, Carlos; Mulligan, Mark J

    2007-01-01

    The HIV/AIDS pandemic continues to challenge the African American community with disproportionate rates of infection, particularly among young women ages 25 to 34 years. Development of a preventive HIV vaccine may bring a substantial turning point in this health crisis. Engagement of the African American community is necessary to improve awareness of the effort and favorably influence attitudes and referent norms. The Theory of Reasoned Action (TRA) may be a useful framework for exploration of community engagement outcomes including future attendance, community mobilization, and study participation. Within the context of HIV vaccine outreach, we conducted a cross-sectional survey in early 2007 with 175 African-American adults (>/= 18 years). Confirmatory factor analysis and structural equation modeling were performed and the findings support the potential of the model in understanding behavioral intentions toward HIV vaccine research.

  17. Dendritic Na(+) spikes enable cortical input to drive action potential output from hippocampal CA2 pyramidal neurons.

    Science.gov (United States)

    Sun, Qian; Srinivas, Kalyan V; Sotayo, Alaba; Siegelbaum, Steven A

    2014-01-01

    Synaptic inputs from different brain areas are often targeted to distinct regions of neuronal dendritic arbors. Inputs to proximal dendrites usually produce large somatic EPSPs that efficiently trigger action potential (AP) output, whereas inputs to distal dendrites are greatly attenuated and may largely modulate AP output. In contrast to most other cortical and hippocampal neurons, hippocampal CA2 pyramidal neurons show unusually strong excitation by their distal dendritic inputs from entorhinal cortex (EC). In this study, we demonstrate that the ability of these EC inputs to drive CA2 AP output requires the firing of local dendritic Na(+) spikes. Furthermore, we find that CA2 dendritic geometry contributes to the efficient coupling of dendritic Na(+) spikes to AP output. These results provide a striking example of how dendritic spikes enable direct cortical inputs to overcome unfavorable distal synaptic locale to trigger axonal AP output and thereby enable efficient cortico-hippocampal information flow.

  18. Resveratrol exhibits a strong cytotoxic activity in cultured cells and has an antiviral action against polyomavirus: potential clinical use

    Directory of Open Access Journals (Sweden)

    Galati Gaspare

    2009-07-01

    Full Text Available Abstract Background Resveratrol is a non flavonoid polyphenol compound present in many plants and fruits and, at especially high concentrations, in the grape berries of Vitis vinifera. This compound has a strong bioactivity and its cytoprotective action has been demonstrated, however at high concentrations the drug exhibits also an effective anti-proliferative action. We recently showed its ability to abolish the effects of oxidative stress in cultured cells. In this work we assayed the bioactivity of resveratrol as antiproliferative and antiviral drug in cultured fibroblasts. Studies by other Authors showed that this natural compound inhibits the proliferation of different viruses such as herpes simplex, varicella-zoster and influenza A. The results presented here show an evident toxic activity of the drug at high concentrations, on the other hand at sub-cytotoxic concentrations, resveratrol can effectively inhibit the synthesis of polyomavirus DNA. A possible interpretation is that, due to the damage caused by resveratrol to the plasma membrane, the transfer of the virus from the endoplasmic reticulum to the nucleus, may be hindered thus inhibiting the production of viral DNA. Methods The mouse fibroblast line 3T6 and the human tumor line HL60 were used throughout the work. Cell viability and vital cell count were assessed respectively, by the MTT assay and Trypan Blue staining. Cytotoxic properties and evaluation of viral DNA production by agarose gel electrophoresis were performed according to standard protocols. Results Our results show a clear dose dependent both cytotoxic and antiviral effect of resveratrol respectively at high and low concentrations. The cytotoxic action is exerted towards a stabilized cell-line (3T6 as well as a tumor-line (HL60. Furthermore the antiviral action is evident after the phase of virion entry, therefore data suggest that the drug acts during the synthesis of the viral progeny DNA. Conclusion Resveratrol is

  19. Effects of the histamine H1 receptor antagonist hydroxyzine on hERG K+ channels and cardiac action potential duration

    Institute of Scientific and Technical Information of China (English)

    Byung Hoon LEE; Seung Ho LEE; Daehyun CHU; Jin Won HYUN; Han CHOE; Bok Hee CHOI; Su-Hyun JO

    2011-01-01

    To investigate the effects of hydroxyzine on human ether-a-go-go-related gene (hERG) channels to determine the electrolphysiological basis for its proarrhythmic effects.Methods:hERG channels were expressed in Xenopus oocytes and HEK293 cells,and the effects of hydroxyzine on the channels were examined using two-microelectrode voltage-clamp and patch-clamp techniques,respectively.The effects of hydroxyzine on action potential duration were examined in guinea pig ventricular myocytes using current clamp.Results:Hydroxyzine (0.2 and 2 μmol/L) significantly increased the action potential duration at 90% repolarization (APD90) in both concentration- and time-dependent manners.Hydroxyzine (0.03-3 μmol/L) blocked both the steady-state and tail hERG currents.The block was voltage-dependent,and the values of IC50 for blocking the steady-state and tail currents at +20 mV was 0.18±0.02 μmol/L and 0.16±0.01 μmol/L,respectively,in HEK293 cells.Hydroxyzine (5 μmol/L) affected both the activated and the inactivated states of the channels,but not the closed state.The S6 domain mutation Y652A attenuated the blocking of hERG current by ~6-fold.Conclusion:The results suggest that hydroxyzine could block hERG channels and prolong APD.The tyrosine at position 652 in the channel may be responsible for the proarrhythmic effects of hydroxyzine.

  20. Potential usefulness of a video printer for producing secondary images from digitized chest radiographs

    Science.gov (United States)

    Nishikawa, Robert M.; MacMahon, Heber; Doi, Kunio; Bosworth, Eric

    1991-05-01

    Communication between radiologists and clinicians could be improved if a secondary image (copy of the original image) accompanied the radiologic report. In addition, the number of lost original radiographs could be decreased, since clinicians would have less need to borrow films. The secondary image should be simple and inexpensive to produce, while providing sufficient image quality for verification of the diagnosis. We are investigating the potential usefulness of a video printer for producing copies of radiographs, i.e. images printed on thermal paper. The video printer we examined (Seikosha model VP-3500) can provide 64 shades of gray. It is capable of recording images up to 1,280 pixels by 1,240 lines and can accept any raster-type video signal. The video printer was characterized in terms of its linearity, contrast, latitude, resolution, and noise properties. The quality of video-printer images was also evaluated in an observer study using portable chest radiographs. We found that observers could confirm up to 90 of the reported findings in the thorax using video- printer images, when the original radiographs were of high quality. The number of verified findings was diminished when high spatial resolution was required (e.g. detection of a subtle pneumothorax) or when a low-contrast finding was located in the mediastinal area or below the diaphragm (e.g. nasogastric tubes).

  1. The use and abuse of image analysis in geophysical potential field interpretation

    Science.gov (United States)

    McDonald, Andrew J. W.

    1991-11-01

    Images of geophysical potential field data are becoming more common as a result of the increased availability of image analysis systems. These data are processed using techniques originally developed for remotely sensed satellite imagery. In general, geophysicists are not familiar with such techniques and may apply them without due consideration. This can lead to abuses of the geophysical data and reduce the validity of the interpretation. This paper describes some critical processes which can introduce errors to the data. The production of a regular grid from scattered data is fundamental to image processing. The choice of cell size is paramount and must balance the spatial distribution of the data. The necessary scaling of data from real values into a byte format for display purposes can result in small anomalies being masked. Contrast stretching of grey level images is often applied but can alter the shape of anomalies by varying degrees and should be avoided. Filters are often used to produce shaded relief images but without due regard to their frequency response and the effect on images expanded to fill the display space. The generation of spurious numerical artefacts can be reduced by ensuring that the filter is applied at real precision to the original data grid. The resultant images can then be processed for display. The use of image analysis systems for data integration requires careful consideration of the sampling strategy and information content of each dataset. It is proposed that such procedures are more appropriately conducted on a geographic information system.

  2. The effects of propofol on local field potential spectra, action potential firing rate, and their temporal relationship in humans and felines

    Directory of Open Access Journals (Sweden)

    Sara eHanrahan

    2013-04-01

    Full Text Available Propofol is an intravenous sedative hypnotic, which, acting as a GABAA agonist, results in neocortical inhibition. While propofol has been well studied at the molecular and clinical level, less is known about the effects of propofol at the level of individual neurons and local neocortical networks. We used Utah Electrode Arrays (UEAs to investigate the effects of propofol anesthesia on action potentials (APs and local field potentials (LFPs. UEAs were implanted into the neocortex of two humans and three felines. The two human patients and one feline received propofol by bolus injection, while the other two felines received target-controlled infusions. We examined the changes in LFP power spectra and AP firing at different levels of anesthesia. Increased propofol concentration correlated with decreased high-frequency power in LFP spectra and decreased AP firing rates, and the generation of large amplitude spike-like LFP activity; however, the temporal relationship between APs and LFPs remained relatively consistent at all levels of propofol. The probability that an AP would fire at this local minimum of the LFP increased with propofol administration. The propofol-induced suppression of neocortical network activity allowed LFPs to be dominated by low-frequency spike-like activity, and correlated with sedation and unconsciousness. As the low-frequency spike-like activity increased and the AP-LFP relationship became more predictable firing rate encoding capacity is impaired. This suggests a mechanism for decreased information processing in the neocortex that accounts for propofol-induced unconsciousness.

  3. Extraction of the magnetohydrodynamic blood flow potential from the surface electrocardiogram in magnetic resonance imaging.

    Science.gov (United States)

    Nijm, Grace M; Swiryn, Steven; Larson, Andrew C; Sahakian, Alan V

    2008-07-01

    The magnetohydrodynamic effect generates voltages related to blood flow, which are superimposed on the electrocardiogram (ECG) used for gating during cardiac magnetic resonance imaging (MRI). A method is presented for extracting the magnetohydrodynamic signal from the ECG. The extracted magnetohydrodynamic blood flow potential may be physiologically meaningful due to its relationship to blood flow. Removal of the magnetohydrodynamic voltages from the ECG can potentially lead to improved gating and diagnostically useful ECGs.

  4. Whole-slide imaging in pathology: the potential impact on PACS

    Science.gov (United States)

    Horii, Steven C.

    2007-03-01

    Pathology, the medical specialty charged with the evaluation of macroscopic and microscopic aspects of disease, is increasingly turning to digital imaging. While the conventional tissue blocks and glass slides form an "archive" that pathology departments must maintain, digital images acquired from microscopes or digital slide scanners are increasingly used for telepathology, consultation, and intra-facility communication. Since many healthcare facilities are moving to "enterprise PACS" with departments in addition to radiology using the infrastructure of such systems, some understanding of the potential of whole-slide digital images is important. Network and storage designers, in particular, are very likely to be impacted if a significant number of such images are to be moved on, or stored (even temporarily) in, enterprise PACS. As an example, a typical commercial whole-slide imaging system typically generates 15 gigabytes per slide scanned (per focal plane). Many of these whole-slide scanners have a throughput of 1000 slides per day. If that full capacity is used and all the resulting digital data is moved to the enterprise PACS, it amounts to 15 terabytes per day; the amount of data a large radiology department might generate in a year or two. This paper will review both the clinical scenarios of whole-slide imaging as well as the resulting data volumes. The author will emphasize the potential PACS infrastructure impact of such huge data volumes.

  5. Neurochemistry of Drug Action: Insights from Proton Magnetic Resonance Spectroscopic Imaging And Their Relevance to Addiction

    OpenAIRE

    Licata, Stephanie C.; Renshaw, Perry F.

    2010-01-01

    Proton magnetic resonance spectroscopy (1H MRS) is a non-invasive imaging technique that permits measurement of particular compounds or metabolites within the tissue of interest. In the brain, 1H MRS provides a snapshot of the neurochemical environment within a defined volume of interest. A search of the literature demonstrates the widespread utility of this technique for characterizing tumors, tracking the progress of neurodegenerative disease, and for understanding the neurobiological basis...

  6. Self-consistent density functional calculation of the image potential at a metal surface

    International Nuclear Information System (INIS)

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z0), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z0, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description

  7. Self-consistent density functional calculation of the image potential at a metal surface

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Alvarellos, J E [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Chacon, E [Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); GarcIa-Gonzalez, P [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain)

    2007-07-04

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z{sub 0}), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z{sub 0}, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.

  8. Detection of blood-related signal from a series of fingerprint images acquired during an input action

    Science.gov (United States)

    Fujieda, Ichiro; Hori, Atsushi; Kurita, Masashi

    2007-09-01

    When a finger is pressed against a flat plate and deformed, blood inside the finger moves away from the deformed area. This causes the finger to change its appearance from reddish to white. As the finger leaves the plate, the blood comes back and it looks reddish again. We have proposed to use this color change to distinguish genuine fingers from artificial ones for un-attended fingerprint identification systems. This blood-related signal may reflect the stiffness of the peripheral blood vessels and therefore it may be correlated with some health conditions such as blood pressure. In experiments, we used a fingerprint sensor based on scattered light detection. Because the spectra of the light scattered by the deformed fingers showed large changes mostly in the green portion, an LED emitting at 525 nm at peak strength was used. First, we compared series of fingerprint images acquired during a normal input action and those obtained while a rubber band occluded the blood flow. The occluded finger required a larger force to exhibit a similar change for these pixel values than the finger without the rubber band. Second, we analyzed fingerprint images recorded by six volunteers. We defined some indices based on the pixel values of the fingerprint images and the pressure applied to the fingers. The correlation coefficient of one of such indices and the average blood pressure of the participants was 0.86. Although the number of the subjects is small, this initial result is encouraging.

  9. High-speed and thermal imaging of the mechanism of action of the cavitron ultrasonic surgical aspirator (CUSA)

    Science.gov (United States)

    Verdaasdonck, Rudolf M.; van Swol, Christiaan F. P.; Grimbergen, Matthijs C. M.; Priem, Gert

    1998-04-01

    The Cavitron Ultrasonic Surgical Aspirator (CUSA) is being used, especially in neuro- and liver surgery, to resect selectively soft and hard tissue in favor of elastic tissues like blood vessels, enabling the removal of tumors with minimal loss of blood. In this study the phenomena associated with CUSA were visualized to expand the understanding of the mechanism of action of the CUSA. Real- time high-speed imaging techniques were applied to capture cavitation phenomena during application of the CUSA under physiological settings: in water, at tissue surfaces and inside artificial tissue. Close-up photography using a 1 microsecond(s) flashlight showed the expanding and imploding cavitation bubbles around the rim of the ultrasonic vibrating hollow tip. Shock waves generated by imploding cavitation bubbles were observed using Schlieren techniques with a temporal resolution of 10 ns and synchronized with the duty cycle of the vibrating tip. In addition, thermal effects associated with friction between the vibrating tip and tissue were visualized sing a thermal imaging technique. The CUSA mechanism has proven to be a combined effect of cavitation induced fragmentation, mechanical cutting and thermal deterioration of tissue depending on the irrigation/aspiration flow, intermittent vibration regime and degree of tissue contact. The impact of the shock waves observed is undetermined yet. These real-time imaging techniques will contribute to expand the understanding of the working mechanism of CUSA and to show the characteristics of probe designs and influence of driving frequency.

  10. Safety and efficacy for new techniques and imaging using new equipment to support European legislation: An EU coordination action

    International Nuclear Information System (INIS)

    The past two decades have witnessed a technologically driven revolution in radiology. At the centre of these developments has been the use of computing. These developments have also been driven by the introduction of new detector and imaging devices in radiology and nuclear medicine, as well as the widespread application of computing techniques to enhance and extract information within the images acquired. Further advances have been introduced into digital practice. These technological developments, however, have not been matched by justification and optimisation studies to ensure that these new imaging devices and techniques are as effective as they might be, or performed at the lowest possible dose. The work programme of the SENTINEL Coordination Action was subdivided into eight work packages: functional performance and standards; efficacy and safety in digital radiology, dentistry and nuclear medicine, cardiology, interventional radiology, population screening/sensitive groups; justification, ethics and efficacy; good practice guidance and training; and project management. The intention of the work programme was to underwrite the safety, efficacy and ethical aspects of digital practice as well as to protect and add value to the equipment used in radiology. (authors)

  11. Analysis for the Potential Function of the Digital Microstructure Image of Porous Media

    Institute of Scientific and Technical Information of China (English)

    XU You-Sheng; LIN Ji; LI Hua-Mei; WU Feng-Min

    2003-01-01

    Making use of the full information obtained in our previous discussions, a new analytical solutions for thepotential function of the digital microstructure image of porous media is reported in this paper. It is demonstrated that the distribution of potential function depends on the zeroth order Bessel function. All these will be helpful for analyzingthe similar subjects in porous media.

  12. Potential of ultraviolet widefield imaging and multiphoton microscopy for analysis of dehydroergosterol in cellular membranes

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Brewer, Jonathan R.; Bagatolli, Luis;

    2011-01-01

    Dehydroergosterol (DHE) is an intrinsically fluorescent sterol with absorption/emission in the ultraviolet (UV) region and biophysical properties similar to those of cholesterol. We compared the potential of UV-sensitive low-light-level wide-field (UV-WF) imaging with that of multiphoton (MP) exc...

  13. Imaging evaluation of potential donors in living-donor liver transplantation

    International Nuclear Information System (INIS)

    Liver transplants, originally obtained from deceased donors, can now be harvested from living donors as well. This technique, called living-donor liver transplantation (LDLT), provides an effective alternative means of liver transplantation and is a method of expanding the donor pool in light of the demand and supply imbalance for organ transplants. Imaging plays an important role in LDLT programmes by providing robust evaluation of potential donors to ensure that only anatomically suitable donors with no significant co-existing pathology are selected and that crucial information that allows detailed preoperative planning is available. Imaging evaluation helps to improve the outcome of LDLT for both donors and recipients, by improving the chances of graft survival and reducing the postoperative complication rate. In this review, we describe the history of LDLT and discuss in detail the application of imaging in donor assessment with emphasis on use of modern computed tomography (CT) and magnetic resonance imaging (MRI) techniques

  14. MR imaging of hand microcirculation as a potential tool for space glove testing and design

    Science.gov (United States)

    Peterson, Steven W.; Strauss, Alvin M.; Niemann, Trista A.; Lorenz, Christine H.

    1991-01-01

    The task of evaluating and designing space gloves requires accurate biomechanical characterization of the hand. The availability of magnetic resonance (MR) imaging has created new opportunities for in vivo analysis of physiological phenomena such as the relationship between circulation and fatigue. An MR imaging technique originally proposed to quantitatively evaluate cerebral perfusion has been modified to evaluate the capillary microcirculation in hand muscles. An experimental protocol was developed to acquire perfusion-weighted images in the hand before and after various levels of exercise. Preliminary results on the feasibility of applying the MR imaging technique to the study of microcirculation and fatigue in the hand are presented. The potential of this method for space glove testing and design is also discussed.

  15. Imaging evaluation of potential donors in living-donor liver transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Low, G. [Department of Radiology and Diagnostic Imaging, University of Alberta Hospital (Canada)], E-mail: timgy@yahoo.com; Wiebe, E. [Department of Radiology and Diagnostic Imaging, University of Alberta Hospital (Canada); Walji, A.H. [Division of Anatomy, Faculty of Medicine, University of Alberta (Canada); Bigam, D.L. [Department of Surgery, University of Alberta Hospital (Canada)

    2008-02-15

    Liver transplants, originally obtained from deceased donors, can now be harvested from living donors as well. This technique, called living-donor liver transplantation (LDLT), provides an effective alternative means of liver transplantation and is a method of expanding the donor pool in light of the demand and supply imbalance for organ transplants. Imaging plays an important role in LDLT programmes by providing robust evaluation of potential donors to ensure that only anatomically suitable donors with no significant co-existing pathology are selected and that crucial information that allows detailed preoperative planning is available. Imaging evaluation helps to improve the outcome of LDLT for both donors and recipients, by improving the chances of graft survival and reducing the postoperative complication rate. In this review, we describe the history of LDLT and discuss in detail the application of imaging in donor assessment with emphasis on use of modern computed tomography (CT) and magnetic resonance imaging (MRI) techniques.

  16. Concurrent Application of TMS and Near-infrared Optical Imaging: Methodological Considerations and Potential Artifacts

    Directory of Open Access Journals (Sweden)

    Nathan A Parks

    2013-09-01

    Full Text Available The simultaneous application of transcranial magnetic stimulation (TMS with non-invasive neuroimaging provides a powerful method for investigating functional connectivity in the human brain and the causal relationships between areas in distributed brain networks. TMS has been combined with numerous neuroimaging techniques including, electroencephalography (EEG, functional magnetic resonance imaging (fMRI, and positron emission tomography (PET. Recent work has also demonstrated the feasibility and utility of combining TMS with non-invasive near-infrared optical imaging techniques, functional near-infrared spectroscopy (fNIRS and the event-related optical signal (EROS. Simultaneous TMS and optical imaging affords a number of advantages over other neuroimaging methods but also involves a unique set of methodological challenges and considerations. This paper describes the methodology of concurrently performing optical imaging during the administration of TMS, focusing on experimental design, potential artifacts, and approaches to controlling for these artifacts.

  17. Effect of microbial action on the corrosion potential of austenitic alloy containers for high-level nuclear waste

    International Nuclear Information System (INIS)

    The safe disposal of high-level nuclear waste (HLW) entails the ability to ensure the integrity of waste containers for prolonged time periods. It is generally accepted that under certain conditions, microbial action may change local benign environments to those in which localized corrosion can be actively promoted. The use of repassivation potential (Erp) in relation to the value of the corrosion potential (Ecorr) has been proposed as a means of assessing the propensity of a metallic material to localized corrosion. Microbial activity is known to influence Ecorr however, the precise mechanism is unresolved. Shewanella putrefaciens, a bacteria with many of the characteristics of sulfate-reducing bacteria (SRB), are being grown under controlled conditions on 316L stainless steel (SS) surfaces to understand the relationship between Ecorr and metabolic activity. It has been observed that the growth of the bacteria under aerobic conditions, without the production of metabolic sulfide, leads to only minor variation in Ecorr. These changes possibly correlate to the periods of active bacterial growth

  18. Effect of microbial action on the corrosion potential of austenitic alloy containers for high-level nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Angell, P.; Dunn, D.S.; Cragnolino, G.A. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1996-08-01

    The safe disposal of high-level nuclear waste (HLW) entails the ability to ensure the integrity of waste containers for prolonged time periods. It is generally accepted that under certain conditions, microbial action may change local benign environments to those in which localized corrosion can be actively promoted. The use of repassivation potential (E{sub rp}) in relation to the value of the corrosion potential (E{sub corr}) has been proposed as a means of assessing the propensity of a metallic material to localized corrosion. Microbial activity is known to influence E{sub corr} however, the precise mechanism is unresolved. Shewanella putrefaciens, a bacteria with many of the characteristics of sulfate-reducing bacteria (SRB), are being grown under controlled conditions on 316L stainless steel (SS) surfaces to understand the relationship between E{sub corr} and metabolic activity. It has been observed that the growth of the bacteria under aerobic conditions, without the production of metabolic sulfide, leads to only minor variation in E{sub corr}. These changes possibly correlate to the periods of active bacterial growth.

  19. Single-Trial Event-Related Potential Based Rapid Image Triage System

    Directory of Open Access Journals (Sweden)

    Ke Yu

    2011-06-01

    Full Text Available Searching for points of interest (POI in large-volume imagery is a challenging problem with few good solutions. In this work, a neural engineering approach called rapid image triage (RIT which could offer about a ten-fold speed up in POI searching is developed. It is essentially a cortically-coupled computer vision technique, whereby the user is presented bursts of images at a speed of 6–15 images per second and then neural signals called event-related potential (ERP is used as the ‘cue’ for user seeing images of high relevance likelihood. Compared to past efforts, the implemented system has several unique features: (1 it applies overlapping frames in image chip preparation, to ensure rapid image triage performance; (2 a novel common spatial-temporal pattern (CSTP algorithm that makes use of both spatial and temporal patterns of ERP topography is proposed for high-accuracy single-trial ERP detection; (3 a weighted version of probabilistic support-vector-machine (SVM is used to address the inherent unbalanced nature of single-trial ERP detection for RIT. High accuracy, fast learning, and real-time capability of the developed system shown on 20 subjects demonstrate the feasibility of a brainmachine integrated rapid image triage system for fast detection of POI from large-volume imagery.

  20. AFM Imaging of SWI/SNF action: mapping the nucleosome remodeling and sliding

    CERN Document Server

    Montel, Fabien; Saint-Jean, Philippe; Castelnovo, Martin; Moskalenko-Faivre, Cendrine

    2007-01-01

    We propose a combined experimental (Atomic Force Microscopy) and theoretical study of the structural and dynamical properties of nucleosomes. In contrast to biochemical approaches, this method allows to determine simultaneously the DNA complexed length distribution and nucleosome position in various contexts. First, we show that differences in the nucleo-proteic structure observed between conventional H2A and H2A.Bbd variant nucleosomes induce quantitative changes in the in the length distribution of DNA complexed with histones. Then, the sliding action of remodeling complex SWI/SNF is characterized through the evolution of the nucleosome position and wrapped DNA length mapping. Using a linear energetic model for the distribution of DNA complexed length, we extract the net wrapping energy of DNA onto the histone octamer, and compare it to previous studies.

  1. Sources of actual and potential radioactive contamination at the Dnieper River basin with regard to preparation of strategic action plan

    International Nuclear Information System (INIS)

    Full text: The Dnieper River basin is one of the largest drainage areas in Europe. The modern Dnieper is a cascade of large artificial reservoirs (Kiev, Kanev, Kremenchug, Dniprodzerzhinsk, Zaporozhie, Kakhovske) carrying its water to the Black Sea. It is largest water artery of Ukraine where more then 20 million of peoples live, and which water extensively use for water supply, fishery, irrigation and recreation in the region. At the same time the Dnieper basin is the most important industrial, agricultural congested area. About 20 units of Nuclear Reactors are in operation of 6 NPP situated on the territory of Ukraine (4) and Russia (2) as well. This area was also heavy contaminated mainly with long-lived radionuclides such as Cs 137 and Sr 90 and Pu due to Chernobyl releases in 1986. In the central part of Ukraine Uranium mining and uranium ores re-processing industry are developed. At the moment most of these facilities are suspended their activity because economical reason. However the problem of uranium tailing of liquid and solid wastes are remain to be one of the serious sources for the Environmental contamination and uncertainties with its impact to the human health in the region (Zheltie Vodi town and Dnieprodzerzhinsk). The Radiation Risk Assessment of the environmental impacts of these sources ('Hot spots') in the basin and Priorities for potential actions to reduce the ecological Risks of its impacts are considering. The Results of this study are the basis for Strategic Action Plan recommended for three countries (Ukraine, Russia and Belarus) at the Dnieper River Basin obtained using Optimization Procedures and experience of Radiation Protection Practice

  2. Simultaneous recording of the action potential and its whole-cell associated ion current on NG108-15 cells cultured over a MWCNT electrode

    Science.gov (United States)

    Morales-Reyes, I.; Seseña-Rubfiaro, A.; Acosta-García, M. C.; Batina, N.; Godínez-Fernández, R.

    2016-08-01

    It is well known that, in excitable cells, the dynamics of the ion currents (I i) is extremely important to determine both the magnitude and time course of an action potential (A p). To observe these two processes simultaneously, we cultured NG108-15 cells over a multi-walled carbon nanotubes electrode (MWCNTe) surface and arranged a two independent Patch Clamp system configuration (Bi-Patch Clamp). The first system was used in the voltage or current clamp mode, using a glass micropipette as an electrode. The second system was modified to connect the MWCNTe to virtual ground. While the A p was recorded through the micropipette electrode, the MWCNTe was used to measure the underlying whole-cell current. This configuration allowed us to record both the membrane voltage (V m) and the current changes simultaneously. Images acquired by atomic force microscopy (AFM) and scanning electron microscopy (SEM) indicate that cultured cells developed a complex network of neurites, which served to establish the necessary close contact and strong adhesion to the MWCNTe surface. These features were a key factor to obtain the recording of the whole-cell I i with a high signal to noise ratio (SNR). The experimental results were satisfactorily reproduced by a theoretical model developed to simulate the proposed system. Besides the contribution to a better understanding of the fundamental mechanisms involved in cell communication, the developed method could be useful in cell physiology studies, pharmacology and diseases diagnosis.

  3. A Potential Magnetic Resonance Imaging Technique Based on Chemical Exchange Saturation Transfer for In Vivo γ-Aminobutyric Acid Imaging

    Science.gov (United States)

    Yan, Gen; Zhang, Tao; Dai, Zhuozhi; Yi, Meizhi; Jia, Yanlong; Nie, Tingting; Zhang, Handi; Xiao, Gang; Wu, Renhua

    2016-01-01

    Purpose We developed a novel magnetic resonance imaging (MRI) technique based on chemical exchange saturation transfer (CEST) for GABA imaging and investigated the concentration-dependent CEST effect ofGABA in a rat model of brain tumor with blood—brain barrier (BBB) disruption. Materials and Methods All MRI studies were performed using a 7.0-T Agilent MRI scanner. Z-spectra for GABA were acquired at 7.0 T, 37°C, and a pH of 7.0 using varying B1 amplitudes. CEST images of phantoms with different concentrations of GABA solutions (pH, 7.0) and other metabolites (glutamine, myoinositol, creatinine, and choline) were collected to investigate the concentration-dependent CEST effect of GABA and the potential contribution from other brain metabolites. CEST maps for GABA in rat brains with tumors were collected at baseline and 50 min, 1.5 h, and 2.0 h after the injection of GABA solution. Results The CEST effect of GABA was observed at approximately 2.75 parts per million(ppm) downfield from bulk water, and this effect increased with an increase in the B1 amplitude and remained steady after the B1 amplitude reached 6.0 μT (255 Hz). The CEST effect of GABA was proportional to the GABA concentration in vitro. CEST imaging of GABA in a rat brain with a tumor and compromised BBB showed a gradual increase in the CEST effect after GABA injection. Conclusion The findings of this study demonstrate the feasibility and potential of CEST MRI with the optimal B1 amplitude, which exhibits excellent spatial and temporal resolutions, to map changes in GABA. PMID:27711138

  4. Action Learning: Avoiding Conflict or Enabling Action

    Science.gov (United States)

    Corley, Aileen; Thorne, Ann

    2006-01-01

    Action learning is based on the premise that action and learning are inextricably entwined and it is this potential, to enable action, which has contributed to the growth of action learning within education and management development programmes. However has this growth in action learning lead to an evolution or a dilution of Revan's classical…

  5. Effectiveness of elite female basketball players’ technical-tactic actions and ways for their improvement at stage of maximal realization of individual potentials

    Directory of Open Access Journals (Sweden)

    Sushko R.A.

    2015-08-01

    Full Text Available Purpose: study effectiveness of elite female basketball players’ technical-tactic actions and determine the ways for their improvement at stage of maximal realization of individual potentials. Material: the authors analyzed competition functioning’s indicators of female basketball players of national combined team of Ukraine and their age characteristics. Results: effectiveness of technical-tactic actions in structure of national female basketball players’ combined team of Ukraine competition functioning at European championship. The authors present: indicators of team composition; roles in team; won and lost games; quantity of scored and skipped points; technical-tactic actions; age of sportswomen. Age indicators of elite female basketball players at stage of maximal realization have been given. Conclusions: we have composed a list of the most important technical-tactic actions in competition functioning. We also outlined ways for their perfection at stage of maximal realization of individual potentials of elite female basketball players of different game roles.

  6. Use of images in Social Studies and Science lessons: Teaching through visual semiotic potential

    Directory of Open Access Journals (Sweden)

    Valentina Haas Prieto

    2016-02-01

    Full Text Available Learners access the school curriculum through meanings created among a variety of semiotic modes (diagrams, photographs, drawings, writing, etc., this learning enables them to join a worldview as they do in each curricular discipline. From a pedagogical and semiotic gaze to classroom interaction, we focus on the use of images in teaching, in relation to their potential to create meaning in social studies and science lessons. This article is part of Fondecyt 1130684 and systematizes methodological tools from Social Semiotics and multimodality used to explore the semiotic potential of a set images used by teachers of elementary and secondary in a public school. From an audiovisual corpus of lessons of a complete curricular unit, we analyze Social Studies and Science videos from the two subjects in 3rd, 6th grade of elementary and 1st grade of secondary school. Through a Multimodal Discourse Analysis using the concepts of ideational or representational metafunction and the categories of Visual Grammar Design, we show examples of situated images anylisis. The results show how the meaning in the image is modified when teachers use them in face to face interaction. This analysis should help teachers to select and deploy images in terms of improving the learning process and teaching materials they prepare for students.

  7. Image-guided radiation therapy:basic concepts and clinical potentials

    Institute of Scientific and Technical Information of China (English)

    Omar Abdel-Rahman

    2014-01-01

    The adaptation and integration of imaging into the process of cancer detection, diagnosis, and intervention is an area of medicine that is undergoing extremely rapid development. Radiation therapy is a prime example of this change. While the objectives of these developments are clear, they raise numerous issues regarding the skil s and resources that assure these technologies are appropriately integrated and applied. We wil explore the basic concepts related to image guidance in various radiotherapy-related procedures with special emphasis on the clinical potentials of this impressive technology.

  8. Lights, Camera, Action! Antimicrobial Peptide Mechanisms Imaged in Space and Time.

    Science.gov (United States)

    Choi, Heejun; Rangarajan, Nambirajan; Weisshaar, James C

    2016-02-01

    Deeper understanding of the bacteriostatic and bactericidal mechanisms of antimicrobial peptides (AMPs) should help in the design of new antibacterial agents. Over several decades, a variety of biochemical assays have been applied to bulk bacterial cultures. While some of these bulk assays provide time resolution of the order of 1min, they do not capture faster mechanistic events. Nor can they provide subcellular spatial information or discern cell-to-cell heterogeneity within the bacterial population. Single-cell, time-resolved imaging assays bring a completely new spatiotemporal dimension to AMP mechanistic studies. We review recent work that provides new insights into the timing, sequence, and spatial distribution of AMP-induced effects on bacterial cells.

  9. Potential of activatable FAP-targeting immunoliposomes in intraoperative imaging of spontaneous metastases.

    Science.gov (United States)

    Tansi, Felista L; Rüger, Ronny; Böhm, Claudia; Kontermann, Roland E; Teichgraeber, Ulf K; Fahr, Alfred; Hilger, Ingrid

    2016-05-01

    Despite intensive research and medical advances met, metastatic disease remains the most common cause of death in cancer patients. This results from late diagnosis, poor therapeutic response and undetected micrometastases and tumor margins during surgery. One approach to overcome these challenges involves fluorescence imaging, which exploits the properties of fluorescent probes for diagnostic detection of molecular structures at the onset of transformation and for intraoperative detection of metastases and tumor margins in real time. Considering these benefits, many contrast agents suitable for fluorescence imaging have been reported. However, most reports only demonstrate the detection of primary tumors and not the detection of metastases or their application in models of image-guided surgery. In this work, we demonstrate the influence of fibroblast activation protein (FAP) on the metastatic potential of fibrosarcoma cells and elucidate the efficacy of activatable FAP-targeting immunoliposomes (FAP-IL) for image-guided detection of the spontaneous metastases in mice models. Furthermore, we characterized the biodistribution and cellular localization of the liposomal fluorescent components in mice organs and traced their excretion over time in urine and feces. Taken together, activatable FAP-IL enhances intraoperative imaging of metastases. Their high accumulation in metastases, subsequent localization in the bile canaliculi and liver kupffer cells and suitable excretion in feces substantiates their potency as contrast agents for intraoperative imaging.

  10. Potential Applications of Microtesla Magnetic Resonance ImagingDetected Using a Superconducting Quantum Interference Device

    Energy Technology Data Exchange (ETDEWEB)

    Myers, Whittier Ryan [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    This dissertation describes magnetic resonance imaging (MRI) of protons performed in a precession field of 132 μT. In order to increase the signal-to-noise ratio (SNR), a pulsed 40-300 mT magnetic field prepolarizes the sample spins and an untuned second-order superconducting gradiometer coupled to a low transition temperature superconducting quantum interference device (SQUID) detects the subsequent 5.6-kHz spin precession. Imaging sequences including multiple echoes and partial Fourier reconstruction are developed. Calculating the SNR of prepolarized SQUID-detected MRI shows that three-dimensional Fourier imaging yields higher SNR than slice-selection imaging. An experimentally demonstrated field-cycling pulse sequence and post-processing algorithm mitigate image artifacts caused by concomitant gradients in low-field MRI. The magnetic field noise of SQUID untuned detection is compared to the noise of SQUID tuned detection, conventional Faraday detection, and the Nyquist noise generated by conducting biological samples. A second-generation microtesla MRI system employing a low-noise SQUID is constructed to increase SNR. A 2.4-m cubic, eddy-current shield with 6-mm thick aluminum walls encloses the experiment to attenuate external noise. The measured noise is 0.75 fT Hz-1/2 referred to the bottom gradiometer loop. Solenoids wound from 30-strand braided wire to decrease Nyquist noise and cooled by either liquid nitrogen or water polarize the spins. Copper wire coils wound on wooden supports produce the imaging magnetic fields and field gradients. Water phantom images with 0.8 x 0.8 x 10 mm3 resolution have a SNR of 6. Three-dimensional 1.6 x 1.9 x 14 mm3 images of bell peppers and 3 x 3 x 26 mm3 in vivo images of the human arm are presented. Since contrast based on the transverse spin relaxation rate (T1) is enhanced at low magnetic fields, microtesla MRI could potentially be used for tumor imaging. The

  11. Potential Applications of Microtesla Magnetic Resonance ImagingDetected Using a Superconducting Quantum Interference Device

    Energy Technology Data Exchange (ETDEWEB)

    Myers, Whittier R.

    2006-05-18

    This dissertation describes magnetic resonance imaging (MRI) of protons performed in a precession field of 132 {micro}T. In order to increase the signal-to-noise ratio (SNR), a pulsed 40-300 mT magnetic field prepolarizes the sample spins and an untuned second-order superconducting gradiometer coupled to a low transition temperature superconducting quantum interference device (SQUID) detects the subsequent 5.6-kHz spin precession. Imaging sequences including multiple echoes and partial Fourier reconstruction are developed. Calculating the SNR of prepolarized SQUID-detected MRI shows that three-dimensional Fourier imaging yields higher SNR than slice-selection imaging. An experimentally demonstrated field-cycling pulse sequence and post-processing algorithm mitigate image artifacts caused by concomitant gradients in low-field MRI. The magnetic field noise of SQUID untuned detection is compared to the noise of SQUID tuned detection, conventional Faraday detection, and the Nyquist noise generated by conducting biological samples. A second-generation microtesla MRI system employing a low-noise SQUID is constructed to increase SNR. A 2.4-m cubic, eddy-current shield with 6-mm thick aluminum walls encloses the experiment to attenuate external noise. The measured noise is 0.75 fT Hz{sup -1/2} referred to the bottom gradiometer loop. Solenoids wound from 30-strand braided wire to decrease Nyquist noise and cooled by either liquid nitrogen or water polarize the spins. Copper wire coils wound on wooden supports produce the imaging magnetic fields and field gradients. Water phantom images with 0.8 x 0.8 x 10 mm{sup 3} resolution have a SNR of 6. Three-dimensional 1.6 x 1.9 x 14 mm{sup 3} images of bell peppers and 3 x 3 x 26 mm{sup 3} in vivo images of the human arm are presented. Since contrast based on the transverse spin relaxation rate (T{sub 1}) is enhanced at low magnetic fields, microtesla MRI could potentially be used for tumor imaging. The measured T{sub 1} of ex

  12. Potential Applications of Microtesla Magnetic Resonance Imaging Detected Using a Superconducting Quantum Interference Device

    International Nuclear Information System (INIS)

    This dissertation describes magnetic resonance imaging (MRI) of protons performed in a precession field of 132 (micro)T. In order to increase the signal-to-noise ratio (SNR), a pulsed 40-300 mT magnetic field prepolarizes the sample spins and an untuned second-order superconducting gradiometer coupled to a low transition temperature superconducting quantum interference device (SQUID) detects the subsequent 5.6-kHz spin precession. Imaging sequences including multiple echoes and partial Fourier reconstruction are developed. Calculating the SNR of prepolarized SQUID-detected MRI shows that three-dimensional Fourier imaging yields higher SNR than slice-selection imaging. An experimentally demonstrated field-cycling pulse sequence and post-processing algorithm mitigate image artifacts caused by concomitant gradients in low-field MRI. The magnetic field noise of SQUID untuned detection is compared to the noise of SQUID tuned detection, conventional Faraday detection, and the Nyquist noise generated by conducting biological samples. A second-generation microtesla MRI system employing a low-noise SQUID is constructed to increase SNR. A 2.4-m cubic, eddy-current shield with 6-mm thick aluminum walls encloses the experiment to attenuate external noise. The measured noise is 0.75 fT Hz-1/2 referred to the bottom gradiometer loop. Solenoids wound from 30-strand braided wire to decrease Nyquist noise and cooled by either liquid nitrogen or water polarize the spins. Copper wire coils wound on wooden supports produce the imaging magnetic fields and field gradients. Water phantom images with 0.8 x 0.8 x 10 mm3 resolution have a SNR of 6. Three-dimensional 1.6 x 1.9 x 14 mm3 images of bell peppers and 3 x 3 x 26 mm3 in vivo images of the human arm are presented. Since contrast based on the transverse spin relaxation rate (T1) is enhanced at low magnetic fields, microtesla MRI could potentially be used for tumor imaging. The measured T1 of ex vivo normal and cancerous prostate

  13. Serotonin spillover onto the axon initial segment of motoneurons induces central fatigue by inhibiting action potential initiation

    DEFF Research Database (Denmark)

    Cotel, Florence; Exley, Richard; Cragg, Stephanie;

    2013-01-01

    Motor fatigue induced by physical activity is an everyday experience characterized by a decreased capacity to generate motor force. Factors in both muscles and the central nervous system are involved. The central component of fatigue modulates the ability of motoneurons to activate muscle adequat......-HT during motor activity spills over from its release sites to the AIS of motoneurons. Here, activated 5-HT1A receptors inhibit firing and, thereby, muscle contraction. Hence, this is a cellular mechanism for central fatigue......Motor fatigue induced by physical activity is an everyday experience characterized by a decreased capacity to generate motor force. Factors in both muscles and the central nervous system are involved. The central component of fatigue modulates the ability of motoneurons to activate muscle......--as during motor exercise--activated 5-HT1A receptors that decreased motoneuronal excitability. Electrophysiological tests combined with pharmacology showed that focal activation of 5-HT1A receptors at the axon initial segment (AIS), but not on other motoneuronal compartments, inhibited the action potential...

  14. Liénard-type models for the simulation of the action potential of cardiac nodal cells

    Science.gov (United States)

    Podziemski, P.; Żebrowski, J. J.

    2013-10-01

    Existing models of cardiac cells which include multi-variable cardiac transmembrane current are too complex to simulate the long time dynamical properties of the heart rhythm. The large number of parameters that need to be defined and set for such models make them not only cumbersome to use but also require a large computing power. Consequently, the application of such models for the bedside analysis of heart rate of a specific patient may be difficult. Other ways of modelling need to be investigated. We consider the general problem of developing a model of cardiac pacemaker tissue that allows to combine the investigation of phenomena at a time scale of thousands of heart beats with the ability to reproduce realistic tissue-level characteristics of cell dynamics. We propose a modified van der Pol-Duffing equation-a Liénard-type oscillator-as a phenomenological model for cardiac nodal tissue, with certain important physiological similarities to ion-channel models of cardiac pacemaker cells. The model presented here is specifically designed to qualitatively reproduce mesoscopic characteristics of cell dynamics, including action potential duration (APD) restitution properties, phase response characteristics, and phase space structure. We show that these characteristics agree qualitatively with the extensive ionic models and experimental results in the literature [Anumonwo et al., 1991, [33], Cao et al., 1999, [49], Coster and Celler, 2003, [31], Qu, 2004, [45], Tsalikakis et al., 2007, [32], Inada et al., 2009, [14], Qu et al., 2010, [50

  15. Anticancer potential and mechanism of action of mango ginger (Curcuma amada Roxb.) supercritical CO₂ extract in human glioblastoma cells.

    Science.gov (United States)

    Ramachandran, Cheppail; Lollett, Ivonne V; Escalon, Enrique; Quirin, Karl-Werner; Melnick, Steven J

    2015-04-01

    Mango ginger (Curcuma amada Roxb.) is among the less-investigated species of Curcuma for anticancer properties. We have investigated the anticancer potential and the mechanism of action of a supercritical CO2 extract of mango ginger (CA) in the U-87MG human glioblastoma cell line. CA demonstrated higher cytotoxicity than temozolomide, etoposide, curcumin, and turmeric force with IC50, IC75, and IC90 values of 4.92 μg/mL, 12.87 μg/mL, and 21.30 μg/mL, respectively. Inhibitory concentration values of CA for normal embryonic mouse hypothalamus cell line (mHypoE-N1) is significantly higher than glioblastoma cell line, indicating the specificity of CA against brain tumor cells. CompuSyn analysis indicates that CA acts synergistically with temozolomide and etoposide for the cytotoxicity with combination index values of <1. CA treatment also induces apoptosis in glioblastoma cells in a dose-dependent manner and downregulates genes associated with apoptosis, cell proliferation, telomerase activity, oncogenesis, and drug resistance in glioblastoma cells.

  16. Electrophysiological evaluation of nerve function in inferior alveolar nerve injury: relationship between nerve action potentials and histomorphometric observations.

    Science.gov (United States)

    Murayama, M; Sasaki, K; Shibahara, T

    2015-12-01

    The objective of this study was to improve the accuracy of diagnosis of inferior alveolar nerve (IAN) injury by determining degrees of nerve disturbance using the sensory nerve action potential (SNAP) and sensory nerve conduction velocity (SCV). Crush and partial and complete nerve amputation injuries were applied to the IAN of rabbits, then SNAPs and histomorphometric observations were recorded at 1, 5, and 10 weeks. For crush injury, most nerves were smaller in diameter at 5 weeks than at 1 week, however after 10 weeks, extensive nerve regeneration was observed. The SNAP showed a decrease in SCV at weeks 1 and 5, followed by an increase at week 10. For partial nerve amputation, small to medium-sized nerve fibres were observed at weeks 1 and 5, then larger nerves were seen at week 10. Minimal changes in SCV were observed at weeks 1 and 5, however SCV increased at week 10. For complete nerve amputation, nerve fibres were sparse at week 1, but gradual nerve regeneration was observed at weeks 5 and 10. SNAPs were detectable from week 10, however the SCV was extremely low. This study showed SCV to be an effective factor in the evaluation of nerve injury and regeneration. PMID:26433750

  17. DCT domain feature extraction scheme based on motor unit action potential of EMG signal for neuromuscular disease classification.

    Science.gov (United States)

    Doulah, Abul Barkat Mollah Sayeed Ud; Fattah, Shaikh Anowarul; Zhu, Wei-Ping; Ahmad, M Omair

    2014-01-01

    A feature extraction scheme based on discrete cosine transform (DCT) of electromyography (EMG) signals is proposed for the classification of normal event and a neuromuscular disease, namely the amyotrophic lateral sclerosis. Instead of employing DCT directly on EMG data, it is employed on the motor unit action potentials (MUAPs) extracted from the EMG signal via a template matching-based decomposition technique. Unlike conventional MUAP-based methods, only one MUAP with maximum dynamic range is selected for DCT-based feature extraction. Magnitude and frequency values of a few high-energy DCT coefficients corresponding to the selected MUAP are used as the desired feature which not only reduces computational burden, but also offers better feature quality with high within-class compactness and between-class separation. For the purpose of classification, the K-nearest neighbourhood classifier is employed. Extensive analysis is performed on clinical EMG database and it is found that the proposed method provides a very satisfactory performance in terms of specificity, sensitivity and overall classification accuracy.

  18. Copper(II)-Bis(Thiosemicarbazonato) Complexes as Antibacterial Agents: Insights into Their Mode of Action and Potential as Therapeutics.

    Science.gov (United States)

    Djoko, Karrera Y; Goytia, Maira M; Donnelly, Paul S; Schembri, Mark A; Shafer, William M; McEwan, Alastair G

    2015-10-01

    There is increasing interest in the use of lipophilic copper (Cu)-containing complexes to combat bacterial infections. In this work, we showed that Cu complexes with bis(thiosemicarbazone) ligands [Cu(btsc)] exert antibacterial activity against a range of medically significant pathogens. Previous work using Neisseria gonorrhoeae showed that Cu(btsc) complexes may act as inhibitors of respiratory dehydrogenases in the electron transport chain. We now show that these complexes are also toxic against pathogens that lack a respiratory chain. Respiration in Escherichia coli was slightly affected by Cu(btsc) complexes, but our results indicate that, in this model bacterium, the complexes act primarily as agents that deliver toxic Cu ions efficiently into the cytoplasm. Although the chemistry of Cu(btsc) complexes may dictate their mechanism of action, their efficacy depends heavily on bacterial physiology. This is linked to the ability of the target bacterium to tolerate Cu and, additionally, the susceptibility of the respiratory chain to direct inhibition by Cu(btsc) complexes. The physiology of N. gonorrhoeae, including multidrug-resistant strains, makes it highly susceptible to damage by Cu ions and Cu(btsc) complexes, highlighting the potential of Cu(btsc) complexes (and Cu-based therapeutics) as a promising treatment against this important bacterial pathogen. PMID:26239980

  19. The Potential Protective Action of Vitamin D in Hepatic Insulin Resistance and Pancreatic Islet Dysfunction in Type 2 Diabetes Mellitus.

    Science.gov (United States)

    Leung, Po Sing

    2016-03-01

    Vitamin D deficiency (i.e., hypovitaminosis D) is associated with increased insulin resistance, impaired insulin secretion, and poorly controlled glucose homeostasis, and thus is correlated with the risk of metabolic diseases, including type 2 diabetes mellitus (T2DM). The liver plays key roles in glucose and lipid metabolism, and its dysregulation leads to abnormalities in hepatic glucose output and triglyceride accumulation. Meanwhile, the pancreatic islets are constituted in large part by insulin-secreting β cells. Consequently, islet dysfunction, such as occurs in T2DM, produces hyperglycemia. In this review, we provide a critical appraisal of the modulatory actions of vitamin D in hepatic insulin sensitivity and islet insulin secretion, and we discuss the potential roles of a local vitamin D signaling in regulating hepatic and pancreatic islet functions. This information provides a scientific basis for establishing the benefits of the maintenance, or dietary manipulation, of adequate vitamin D status in the prevention and management of obesity-induced T2DM and non-alcoholic fatty liver disease. PMID:26959059

  20. Effects of Ginkgolide B on action potential and calcium,potassium current in guinea pig ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Xiao-yan QI; Zhi-xiong ZHANG; You-qiu XU

    2004-01-01

    AIM: To investigate the effect of Ginkgolide B (GB) on action potential (AP), delayed rectifier potassium current (IK), and L-type calcium current (ICa-L) in guinea pig ventricular myocytes. METHODS: Single ventricular myocytes were isolated by an enzymatic dissociation method. AP, IK, ICa-L were recorded by whole-cell patch-clamp technique in either current or voltage clamp mode. RESULTS: GB shortened APD in a concentration-dependent manner. GB 0.1, 1, and 10 μmol/L shortened APD50 by 7.9 % (n=5, P>0.05), 18.4 % (n=5, P<0.01), and 28.9 % (n=6, P<0.01), respectively; APD90 by 12.4 % (n=5, P>0.05), 17.6 % (n=5, P<0.01), 26.4 % (n=5, P<0.01),respectively. GB increased IK in a concentration-dependent manner. GB 0.1, 1, and l0 μmol/L increased IK by 20.1% (n=6, P<0.05), 43.1% (n=6, P<0.01), 55.6 % (n=6, P<0.05); increased IKtail by 10.7 % (n=6, P<0.05),25.1% (n=6, P<0.05), and 37.7 % (n=6, P<0.05), respectively at testing potential of +50 mV and shift the I-V curve of Ik upward. But GB had no significant effect on ICa-L at above concentrations. CONCLUSION: GB significantly shortened APD in a concentration-dependent manner which mainly due to increase of IK.

  1. Percutaneous method for single-catheter multiple monophasic action potential recordings during magnetocardiographic mapping in spontaneously breathing rodents

    International Nuclear Information System (INIS)

    To test the feasibility of a novel method to combine magnetocardiographic (MCG) estimate of ventricular repolarization (VR) and multiple monophasic action potential (MultiMAP) recording in spontaneously breathing rodents with percutaneous sub-xyphoid epicardial placement of a MCG-compatible amagnetic catheter (AC), ten Wistar rats (WRs) and ten guinea pigs (GPs) were studied. Under fluoroscopic control, the AC was moved until four stable MAPs were recorded (fixed inter-electrode distance of 1.2 mm). 36-channel DC-SQUID (sensitivity 20 fT Hz–½) were used for MCG mapping. MAPs, differentially amplified (BW: DC-500 Hz), were digitized at 1 kHz. AC pacing provided local ventricular effective refractory period (VERP) estimate. MAP duration (MAPd) was measured at 50% and 90% levels of repolarization. Simultaneous MCG mapping and MultiMAP recording were successful in all animals. Average MAPd50% and MAPd90% were shorter in WRs than in GPs (26.4 ± 2.9 ms versus 110.6 ± 14.3 ms and 60.7 ± 5.4 ms versus 127.7 ± 15.3 ms, respectively). VERP was 51 ± 4.8 ms in WRs and 108.4 ± 12.9 ms in GPs, respectively. The MAP amplitude was 16.9 ± 4.5 in WRs and 16.2 ± 4.2 in GPs. MAP and MCG parameters of VR were in good agreement. All animals survived the procedure. Two also survived a second invasive study; one was followed up until natural death at 52 months. Percutaneous MultiMAP recording is minimally invasive, usually avoids animal sacrifice, is compatible with simultaneous surface MCG mapping and might be used for experimental validation of MCG VR abnormality, to study the arrhythmogenic potential of new drugs and/or animal models of ventricular arrhythmias. (paper)

  2. Comparison of sensitivity of magnetic resonance imaging and evoked potentials in the detection of brainstem involvement in multiple sclerosis

    International Nuclear Information System (INIS)

    A comparison was made of the sensitivity of magnetic resonance imaging and the combined use of Brainstem Auditory Evoked Potential and Median Somatosensory Evoked Potential in the detection of brainstem dysfunction in 54 multiple sclerosis patients. 10 refs.; 2 tabs

  3. Synthesis and Bioconjugation of Gold Nanoparticles as Potential Molecular Probes for Light-Based Imaging Techniques

    Directory of Open Access Journals (Sweden)

    Raja Gopal Rayavarapu

    2007-01-01

    Full Text Available We have synthesized and characterized gold nanoparticles (spheres and rods with optical extinction bands within the “optical imaging window.” The intense plasmon resonant driven absorption and scattering peaks of these nanoparticles make them suitable as contrast agents for optical imaging techniques. Further, we have conjugated these gold nanoparticles to a mouse monoclonal antibody specific to HER2 overexpressing SKBR3 breast carcinoma cells. The bioconjugation protocol uses noncovalent modes of binding based on a combination of electrostatic and hydrophobic interactions of the antibody and the gold surface. We discuss various aspects of the synthesis and bioconjugation protocols and the characterization results of the functionalized nanoparticles. Some proposed applications of these potential molecular probes in the field of biomedical imaging are also discussed.

  4. An exploratory investigation of various modes of action and potential adverse outcomes of fluoxetine in marine mussels

    Energy Technology Data Exchange (ETDEWEB)

    Franzellitti, Silvia, E-mail: silvia.franzellitti@unibo.it [University of Bologna, Interdepartment Centre for Environmental Science Research, via S. Alberto 163, 48123 Ravenna (Italy); University of Bologna, Department of Biological, Geological, and Environmental Sciences, via Selmi 3, 40100 Bologna (Italy); Buratti, Sara; Capolupo, Marco [University of Bologna, Interdepartment Centre for Environmental Science Research, via S. Alberto 163, 48123 Ravenna (Italy); Du, Bowen; Haddad, Samuel P. [Department of Environmental Science, Baylor University, Waco, TX 76798 (United States); Chambliss, C. Kevin [Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76798 (United States); Brooks, Bryan W. [Department of Environmental Science, Baylor University, Waco, TX 76798 (United States); Fabbri, Elena [University of Bologna, Interdepartment Centre for Environmental Science Research, via S. Alberto 163, 48123 Ravenna (Italy); University of Bologna, Department of Biological, Geological, and Environmental Sciences, via Selmi 3, 40100 Bologna (Italy)

    2014-06-01

    Highlights: • Mode of action (MOA) related endpoints and biomarkers of toxicity were assessed in mussels exposed to fluoxetine (FX). • Significant FX bioaccumulation was observed in tissues of mussels exposed to 30 and 300 ng/L FX. • Alterations of cAMP-related cell signaling were observed in exposed mussels as part of the MOA of FX. • FX reduced the health status of mussels inducing lysosomal effects in digestive gland and antioxidant responses in gills. • The importance of considering additional MOAs and adverse outcome pathways for FX impacts on mussels is highlighted. - Abstract: The present study investigated possible adverse outcome pathways (AOPs) of the antidepressant fluoxetine (FX) in the marine mussel Mytilus galloprovincialis. An evaluation of molecular endpoints involved in modes of action (MOAs) of FX and biomarkers for sub-lethal toxicity were explored in mussels after a 7-day administration of nominal FX concentrations encompassing a range of environmentally relevant values (0.03–300 ng/L). FX bioaccumulated in mussel tissues after treatment with 30 and 300 ng/L FX, resulting in bioconcentration factor (BCF) values ranging from 200 to 800, which were higher than expected based solely on hydrophobic partitioning models. Because FX acts as a selective serotonin (5-HT) re-uptake inhibitor increasing serotonergic neurotransmission at mammalian synapses, cell signaling alterations triggered by 5-HT receptor occupations were assessed. cAMP levels and PKA activities were decreased in digestive gland and mantle/gonads of FX-treated mussels, consistent with an increased occupation of 5-HT1 receptors negatively coupled to the cAMP/PKA pathway. mRNA levels of a ABCB gene encoding the P-glycoprotein were also significantly down-regulated. This membrane transporter acts in detoxification towards xenobiotics and in altering pharmacokinetics of antidepressants; moreover, it is under a cAMP/PKA transcriptional regulation in mussels. Potential stress

  5. Potential of lateral interactions of CO on Pt (111) fitted to recent STM images

    Science.gov (United States)

    Myshlyavtsev, Alexander V.; Stishenko, Pavel V.

    2015-12-01

    Monolayers of carbon monoxide (CO) on Pt(111) surfaces are one of the most studied adsorption systems. However, molecular models of this system still do not take into account the reliable potential of lateral interactions between adsorbed CO molecules. Recent advances in experimental technique have brought high-resolution real-space images of CO/Pt(111) monolayers. For example, Yang et al. (J. Phys. Chem. C 117 (2013) 16429-16437) found island structures for coverages from 0.11 to 0.25 ML. In this study we have shown that these island structures can be explained with long-range oscillating lateral interactions. Parameters of the proposed potential were fitted to experimental scanning tunneling microscopy images with a series of Monte Carlo simulations.

  6. Synthesis and evaluation of {sup 99m}Tc-moxifloxacin, a potential infection specific imaging agent

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Sankha [Radiopharmaceuticals Laboratory, Board of Radiation and Isotope Technology, Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata 700 064 (India)], E-mail: sankha@veccal.ernet.in; Saha Das, Sujata [Radiopharmaceuticals Laboratory, Board of Radiation and Isotope Technology, Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata 700 064 (India); Chandra, Susmita; De, Kakali; Mishra, Mridula [Nuclear Medicine Department, Indian Institute of Chemical Biology, Kolkata (India); Ranjan Sarkar, Bharat; Sinha, Samarendu; Ganguly, Shantanu [Regional Radiation Medicine Centre, Variable Energy Cyclotron Centre, Kolkata (India)

    2010-02-15

    To synthesize and evaluate a {sup 99m}Tc labeled fluroquinolone, moxifloxacin as a potential bacteria specific infection imaging agent. A radiolabeling formulation including moxifloxacin, [Moxicip{sup TM} injection, Cipla] (4 mg), sodium pertechnetate and stannous chloride (5 {mu}g) gave the best radiolabeling efficiency and moderately stable labeled {sup 99m}Tc moxifloxacin. Quality control analysis was performed by ITLC. Rats and rabbit with infectious intramuscular lesions induced in either thigh with E. Colli were used for studying biodistribution and scintigraphic imaging of the labeled product. Imaging of an infected thigh of a rabbit was performed with a {gamma}-camera at various intervals. A good radiolabeling efficiency (90-95%) was obtained within 5 min. No purification of the labeled product was done. Labeled product retained its radiochemical purity upto 85% even at 3 h. Scintigraphy showed uptake in infectious lesions at 30 min after injection, which remains constant upto 3 h study. Abscess-to-muscle ratios were 1.60, 1.62, 1.74 and 1.75 at 30 min, 1, 2 and 3 h, respectively. Thus, {sup 99m}Tc moxifloxacin, a new potential radiopharmaceutical has been developed for infection imaging agent.

  7. Optically induced effective mass renormalization: the case of graphite image potential states

    Science.gov (United States)

    Montagnese, M.; Pagliara, S.; Galimberti, G.; Dal Conte, S.; Ferrini, G.; van Loosdrecht, P. H. M.; Parmigiani, F.

    2016-10-01

    Many-body interactions with the underlying bulk electrons determine the properties of confined electronic states at the surface of a metal. Using momentum resolved nonlinear photoelectron spectroscopy we show that one can tailor these many-body interactions in graphite, leading to a strong renormalization of the dispersion and linewidth of the image potential state. These observations are interpreted in terms of a basic self-energy model, and may be considered as exemplary for optically induced many-body interactions.

  8. Potential Lung Nodules Identification for Characterization by Variable Multistep Threshold and Shape Indices from CT Images

    OpenAIRE

    Saleem Iqbal; Khalid Iqbal; Fahim Arif; Arslan Shaukat; Aasia Khanum

    2014-01-01

    Computed tomography (CT) is an important imaging modality. Physicians, surgeons, and oncologists prefer CT scan for diagnosis of lung cancer. However, some nodules are missed in CT scan. Computer aided diagnosis methods are useful for radiologists for detection of these nodules and early diagnosis of lung cancer. Early detection of malignant nodule is helpful for treatment. Computer aided diagnosis of lung cancer involves lung segmentation, potential nodules identification, features extractio...

  9. Molecular Imaging of Tumor Hypoxia: Existing Problems and Their Potential Model-Based Solutions.

    Science.gov (United States)

    Shi, Kuangyu; Ziegler, Sibylle I; Vaupel, Peter

    2016-01-01

    Molecular imaging of tissue hypoxia generates contrast in hypoxic areas by applying hypoxia-specific tracers in organisms. In cancer tissue, the injected tracer needs to be transported over relatively long distances and accumulates slowly in hypoxic regions. Thus, the signal-to-background ratio of hypoxia imaging is very small and a non-specific accumulation may suppress the real hypoxia-specific signals. In addition, the heterogeneous tumor microenvironment makes the assessment of the tissue oxygenation status more challenging. In this study, the diffusion potential of oxygen and of a hypoxia tracer for 4 different hypoxia subtypes: ischemic acute hypoxia, hypoxemic acute hypoxia, diffusion-limited chronic hypoxia and anemic chronic hypoxia are theoretically assessed. In particular, a reaction-diffusion equation is introduced to quantitatively analyze the interstitial diffusion of the hypoxia tracer [(18)F]FMISO. Imaging analysis strategies are explored based on reaction-diffusion simulations. For hypoxia imaging of low signal-to-background ratio, pharmacokinetic modelling has advantages to extract underlying specific binding signals from non-specific background signals and to improve the assessment of tumor oxygenation. Different pharmacokinetic models are evaluated for the analysis of the hypoxia tracer [(18)F]FMISO and optimal analysis model were identified accordingly. The improvements by model-based methods for the estimation of tumor oxygenation are in agreement with experimental data. The computational modelling offers a tool to explore molecular imaging of hypoxia and pharmacokinetic modelling is encouraged to be employed in the corresponding data analysis. PMID:27526129

  10. Benchtop and Animal Validation of a Projective Imaging System for Potential Use in Intraoperative Surgical Guidance.

    Directory of Open Access Journals (Sweden)

    Qi Gan

    Full Text Available We propose a projective navigation system for fluorescence imaging and image display in a natural mode of visual perception. The system consists of an excitation light source, a monochromatic charge coupled device (CCD camera, a host computer, a projector, a proximity sensor and a Complementary metal-oxide-semiconductor (CMOS camera. With perspective transformation and calibration, our surgical navigation system is able to achieve an overall imaging speed higher than 60 frames per second, with a latency of 330 ms, a spatial sensitivity better than 0.5 mm in both vertical and horizontal directions, and a projection bias less than 1 mm. The technical feasibility of image-guided surgery is demonstrated in both agar-agar gel phantoms and an ex vivo chicken breast model embedding Indocyanine Green (ICG. The biological utility of the system is demonstrated in vivo in a classic model of ICG hepatic metabolism. Our benchtop, ex vivo and in vivo experiments demonstrate the clinical potential for intraoperative delineation of disease margin and image-guided resection surgery.

  11. Benchtop and Animal Validation of a Projective Imaging System for Potential Use in Intraoperative Surgical Guidance

    Science.gov (United States)

    Gan, Qi; Wang, Dong; Ye, Jian; Zhang, Zeshu; Wang, Xinrui; Hu, Chuanzhen; Shao, Pengfei; Xu, Ronald X.

    2016-01-01

    We propose a projective navigation system for fluorescence imaging and image display in a natural mode of visual perception. The system consists of an excitation light source, a monochromatic charge coupled device (CCD) camera, a host computer, a projector, a proximity sensor and a Complementary metal–oxide–semiconductor (CMOS) camera. With perspective transformation and calibration, our surgical navigation system is able to achieve an overall imaging speed higher than 60 frames per second, with a latency of 330 ms, a spatial sensitivity better than 0.5 mm in both vertical and horizontal directions, and a projection bias less than 1 mm. The technical feasibility of image-guided surgery is demonstrated in both agar-agar gel phantoms and an ex vivo chicken breast model embedding Indocyanine Green (ICG). The biological utility of the system is demonstrated in vivo in a classic model of ICG hepatic metabolism. Our benchtop, ex vivo and in vivo experiments demonstrate the clinical potential for intraoperative delineation of disease margin and image-guided resection surgery. PMID:27391764

  12. Action potential energetics at the organismal level reveal a trade-off in efficiency at high firing rates.

    Science.gov (United States)

    Lewis, John E; Gilmour, Kathleen M; Moorhead, Mayron J; Perry, Steve F; Markham, Michael R

    2014-01-01

    The energetic costs of action potential (AP) production constrain the evolution of neural codes and brain networks. Cellular-level estimates of AP-related costs are typically based on voltage-dependent Na(+) currents that drive active transport by the Na(+)/K(+) ATPase to maintain the Na(+) and K(+) ion concentration gradients necessary for AP production. However, these estimates of AP cost have not been verified at the organismal level. Electric signaling in the weakly electric fish Eigenmannia virescens requires that specialized cells in an electric organ generate APs with large Na(+) currents at high rates (200-600 Hz). We measured these currents using a voltage-clamp protocol and then estimated the energetic cost at the cellular level using standard methods. We then used this energy-intensive signaling behavior to measure changes in whole-animal energetics for small changes in electric discharge rate. At low rates, the whole-animal measure of AP cost was similar to our cellular-level estimates. However, AP cost increased nonlinearly with increasing firing rates. We show, with a biophysical model, that this nonlinearity can arise from the increasing cost of maintaining AP amplitude at high rates. Our results confirm that estimates of energetic costs based on Na(+) influx are appropriate for low baseline firing rates, but that extrapolating to high firing rates may underestimate true costs in cases in which AP amplitude does not decrease. Moreover, the trade-off between energetic cost and firing rate suggests an additional constraint on the evolution of high-frequency signaling in neuronal systems. PMID:24381281

  13. Serotonin spillover onto the axon initial segment of motoneurons induces central fatigue by inhibiting action potential initiation

    Science.gov (United States)

    Cotel, Florence; Exley, Richard; Cragg, Stephanie J.; Perrier, Jean-François

    2013-01-01

    Motor fatigue induced by physical activity is an everyday experience characterized by a decreased capacity to generate motor force. Factors in both muscles and the central nervous system are involved. The central component of fatigue modulates the ability of motoneurons to activate muscle adequately independently of the muscle physiology. Indirect evidence indicates that central fatigue is caused by serotonin (5-HT), but the cellular mechanisms are unknown. In a slice preparation from the spinal cord of the adult turtle, we found that prolonged stimulation of the raphe-spinal pathway—as during motor exercise—activated 5-HT1A receptors that decreased motoneuronal excitability. Electrophysiological tests combined with pharmacology showed that focal activation of 5-HT1A receptors at the axon initial segment (AIS), but not on other motoneuronal compartments, inhibited the action potential initiation by modulating a Na+ current. Immunohistochemical staining against 5-HT revealed a high-density innervation of 5-HT terminals on the somatodendritic membrane and a complete absence on the AIS. This observation raised the hypothesis that a 5-HT spillover activates receptors at this latter compartment. We tested it by measuring the level of extracellular 5-HT with cyclic voltammetry and found that prolonged stimulations of the raphe-spinal pathway increased the level of 5-HT to a concentration sufficient to activate 5-HT1A receptors. Together our results demonstrate that prolonged release of 5-HT during motor activity spills over from its release sites to the AIS of motoneurons. Here, activated 5-HT1A receptors inhibit firing and, thereby, muscle contraction. Hence, this is a cellular mechanism for central fatigue. PMID:23487756

  14. Problems, Prescriptions and Potential in Actionable Climate Change Science - A Case Study from California Coastal Marsh Research

    Science.gov (United States)

    MacDonald, G. M.; Ambrose, R. F.; Thorne, K.; Takekawa, J.; Brown, L. N.; Fejtek, S.; Gold, M.; Rosencranz, J.

    2015-12-01

    Frustrations regarding the provision of actionable science extend to both producers and consumers. Scientists decry the lack of application of their research in shaping policy and practices while decision makers bemoan the lack of applicability of scientific research to the specific problems at hand or its narrow focus relative to the plethora of engineering, economic and social considerations that they must also consider. Incorporating climate change adds additional complexity due to uncertainties in estimating many facets of future climate, the inherent variability of climate and the decadal scales over which significant changes will develop. Recently a set of guidelines for successful science-policy interaction was derived from the analysis of transboundary water management. These are; 1 recognizing that science is a crucial but bounded input into the decision-making processes, 2 early establishment of conditions for collaboration and shared commitment among participants, 3 understanding that science-policy interactions are enhanced through greater collaboration and social or group-learning processes, 4 accepting that the collaborative production of knowledge is essential to build legitimate decision-making processes, and 5 engaging boundary organizations and informal networks as well as formal stakeholders. Here we present as a case study research on California coastal marshes, climate change and sea-level that is being conducted by university and USGS scientists under the auspices of the Southwest Climate Science Center. We also present research needs identified by a seperate analysis of best practices for coastal marsh restoration in the face of climate change that was conducted in extensive consultation with planners and managers. The initial communication, scientific research and outreach-dissemination of the marsh scientfic study are outlined and compared to best practices needs identified by planners and the science-policy guidelines outlined above

  15. Elevated heart rate triggers action potential alternans and sudden death. translational study of a homozygous KCNH2 mutation.

    Directory of Open Access Journals (Sweden)

    Ulrich Schweigmann

    Full Text Available BACKGROUND: Long QT syndrome (LQTS leads to arrhythmic events and increased risk for sudden cardiac death (SCD. Homozygous KCNH2 mutations underlying LQTS-2 have previously been termed "human HERG knockout" and typically express severe phenotypes. We studied genotype-phenotype correlations of an LQTS type 2 mutation identified in the homozygous index patient from a consanguineous Turkish family after his brother died suddenly during febrile illness. METHODS AND RESULTS: Clinical work-up, DNA sequencing, mutagenesis, cell culture, patch-clamp, in silico mathematical modelling, protein biochemistry, confocal microscopy were performed. Genetic analysis revealed a homozygous C-terminal KCNH2 mutation (p.R835Q in the index patient (QTc ∼506 ms with notched T waves. Parents were I° cousins - both heterozygous for the mutation and clinically unremarkable (QTc ∼447 ms, father and ∼396 ms, mother. Heterologous expression of KCNH2-R835Q showed mildly reduced current amplitudes. Biophysical properties of ionic currents were also only nominally changed with slight acceleration of deactivation and more negative V50 in R835Q-currents. Protein biochemistry and confocal microscopy revealed similar expression patterns and trafficking of WT and R835Q, even at elevated temperature. In silico analysis demonstrated mildly prolonged ventricular action potential duration (APD compared to WT at a cycle length of 1000 ms. At a cycle length of 350 ms M-cell APD remained stable in WT, but displayed APD alternans in R835Q. CONCLUSION: Kv11.1 channels affected by the C-terminal R835Q mutation display mildly modified biophysical properties, but leads to M-cell APD alternans with elevated heart rate and could precipitate SCD under specific clinical circumstances associated with high heart rates.

  16. Evaluation of nystatin containing chitosan hydrogels as potential dual action bio-active restorative materials: in vitro approach.

    Science.gov (United States)

    Perchyonok, V Tamara; Reher, Vanessa; Zhang, Shengmiao; Basson, Nicki; Grobler, Sias

    2014-11-28

    Healing is a specific biological process related to the general phenomenon of growth and tissue regeneration and is a process generally affected by several systemic conditions or as detrimental side-effects of chemotherapy- and radiotherapy-induced inflammation of the oral mucosa. The objectives of this study is to evaluate the novel chitosan based functional drug delivery systems, which can be successfully incorporated into "dual action bioactive restorative materials", capable of inducing in vitro improved wound healing prototype and containing an antibiotic, such as nystatin, krill oil as an antioxidant and hydroxyapatite as a molecular bone scaffold, which is naturally present in bone and is reported to be successfully used in promoting bone integration when implanted as well as promoting healing. The hydrogels were prepared using a protocol as previously reported by us. The physico-chemical features, including surface morphology (SEM), release behaviors, stability of the therapeutic agent-antioxidant-chitosan, were measured and compared to the earlier reported chitosan-antioxidant containing hydrogels. Structural investigations of the reactive surface of the hydrogel are reported. Release of nystatin was investigated for all newly prepared hydrogels. Bio-adhesive studies were performed in order to assess the suitability of these designer materials. Free radical defense capacity of the biomaterials was evaluated using established in vitro model. The bio-adhesive capacity of the materials in the in vitro system was tested and quantified. It was found that the favorable synergistic effect of free radical built-in defense mechanism of the new functional materials increased sustainable bio-adhesion and therefore acted as a functional multi-dimensional restorative material with potential application in wound healing in vitro.

  17. Evaluation of Nystatin Containing Chitosan Hydrogels as Potential Dual Action Bio-Active Restorative Materials: in Vitro Approach

    Directory of Open Access Journals (Sweden)

    V. Tamara Perchyonok

    2014-11-01

    Full Text Available Healing is a specific biological process related to the general phenomenon of growth and tissue regeneration and is a process generally affected by several systemic conditions or as detrimental side-effects of chemotherapy- and radiotherapy-induced inflammation of the oral mucosa. The objectives of this study is to evaluate the novel chitosan based functional drug delivery systems, which can be successfully incorporated into “dual action bioactive restorative materials”, capable of inducing in vitro improved wound healing prototype and containing an antibiotic, such as nystatin, krill oil as an antioxidant and hydroxyapatite as a molecular bone scaffold, which is naturally present in bone and is reported to be successfully used in promoting bone integration when implanted as well as promoting healing. The hydrogels were prepared using a protocol as previously reported by us. The physico-chemical features, including surface morphology (SEM, release behaviors, stability of the therapeutic agent-antioxidant-chitosan, were measured and compared to the earlier reported chitosan-antioxidant containing hydrogels. Structural investigations of the reactive surface of the hydrogel are reported. Release of nystatin was investigated for all newly prepared hydrogels. Bio-adhesive studies were performed in order to assess the suitability of these designer materials. Free radical defense capacity of the biomaterials was evaluated using established in vitro model. The bio-adhesive capacity of the materials in the in vitro system was tested and quantified. It was found that the favorable synergistic effect of free radical built-in defense mechanism of the new functional materials increased sustainable bio-adhesion and therefore acted as a functional multi-dimensional restorative material with potential application in wound healing in vitro.

  18. Beta-adrenergic stimulation reverses the I Kr-I Ks dominant pattern during cardiac action potential.

    Science.gov (United States)

    Banyasz, Tamas; Jian, Zhong; Horvath, Balazs; Khabbaz, Shaden; Izu, Leighton T; Chen-Izu, Ye

    2014-11-01

    β-Adrenergic stimulation differentially modulates different K(+) channels and thus fine-tunes cardiac action potential (AP) repolarization. However, it remains unclear how the proportion of I Ks, I Kr, and I K1 currents in the same cell would be altered by β-adrenergic stimulation, which would change the relative contribution of individual K(+) current to the total repolarization reserve. In this study, we used an innovative AP-clamp sequential dissection technique to directly record the dynamic I Ks, I Kr, and I K1 currents during the AP in guinea pig ventricular myocytes under physiologically relevant conditions. Our data provide quantitative measures of the magnitude and time course of I Ks, I Kr, and I K1 currents in the same cell under its own steady-state AP, in a physiological milieu, and with preserved Ca(2+) homeostasis. We found that isoproterenol treatment significantly enhanced I Ks, moderately increased I K1, but slightly decreased I Kr in a dose-dependent manner. The dominance pattern of the K(+) currents was I Kr > I K1 > I Ks at the control condition, but reversed to I Kr Kr, and I K1 to cardiac repolarization during AP at different adrenergic states. In conclusion, the β-adrenergic stimulation fine-tunes the cardiac AP morphology by shifting the power of different K(+) currents in a dose-dependent manner. This knowledge is important for designing antiarrhythmic drug strategies to treat hearts exposed to various sympathetic tones.

  19. Action potential-evoked calcium release is impaired in single skeletal muscle fibers from heart failure patients.

    Directory of Open Access Journals (Sweden)

    Marino DiFranco

    Full Text Available BACKGROUND: Exercise intolerance in chronic heart failure (HF has been attributed to abnormalities of the skeletal muscles. Muscle function depends on intact excitation-contraction coupling (ECC, but ECC studies in HF models have been inconclusive, due to deficiencies in the animal models and tools used to measure calcium (Ca2+ release, mandating investigations in skeletal muscle from HF patients. The purpose of this study was to test the hypothesis that Ca2+ release is significantly impaired in the skeletal muscle of HF patients in whom exercise capacity is severely diminished compared to age-matched healthy volunteers. METHODS AND FINDINGS: Using state-of-the-art electrophysiological and optical techniques in single muscle fibers from biopsies of the locomotive vastus lateralis muscle, we measured the action potential (AP-evoked Ca2+ release in 4 HF patients and 4 age-matched healthy controls. The mean peak Ca2+ release flux in fibers obtained from HF patients (10±1.2 µM/ms was markedly (2.6-fold and significantly (p<0.05 smaller than in fibers from healthy volunteers (28±3.3 µM/ms. This impairment in AP-evoked Ca2+ release was ubiquitous and was not explained by differences in the excitability mechanisms since single APs were indistinguishable between HF patients and healthy volunteers. CONCLUSIONS: These findings prove the feasibility of performing electrophysiological experiments in single fibers from human skeletal muscle, and offer a new approach for investigations of myopathies due to HF and other diseases. Importantly, we have demonstrated that one step in the ECC process, AP-evoked Ca2+ release, is impaired in single muscle fibers in HF patients.

  20. Repolarization of the action potential enabled by Na+ channel deactivation in PSpice simulation of cardiac muscle propagation

    Directory of Open Access Journals (Sweden)

    Sperelakis Nicholas

    2005-12-01

    Full Text Available Abstract Background In previous studies on propagation of simulated action potentials (APs in cardiac muscle using PSpice modeling, we reported that a second black-box (BB could not be inserted into the K+ leg of the basic membrane unit because that caused the PSpice program to become very unstable. Therefore, only the rising phase of the APs could be simulated. This restriction was acceptable since only the mechanism of transmission of excitation from one cell to the next was being investigated. Methods and results We have now been able to repolarize the AP by inserting a second BB into the Na+ leg of the basic units. This second BB effectively mimicked deactivation of the Na+ channel conductance. This produced repolarization of the AP, not by activation of K+ conductance, but by deactivation of the Na+ conductance. The propagation of complete APs was studied in a chain (strand of 10 cardiac muscle cells, in which various numbers of gap-junction (gj channels (assumed to be 100 pS each were inserted across the cell junctions. The shunt resistance across the junctions produced by the gj-channels (Rgj was varied from 100,000 M? (0 gj-channels to 10,000 M? (1 gj-channel, to 1,000 M? (10 channels, to 100 M? (100 channels, and 10 M? (1000 channels. The velocity of propagation (θ, in cm/s was calculated from the measured total propagation time (TPT, the time difference between when the AP rising phase of the first cell and the last cell crossed -20 mV, assuming a cell length of 150 μm. When there were no gj-channels, or only a few, the transmission of excitation between cells was produced by the electric field (EF, i.e. the negative junctional cleft potential, that is generated in the narrow junctional clefts (e.g. 100 A when the prejunctional membrane fires an AP. When there were many gj-channels (e.g. 1000 or 10,000, the transmission of excitation was produced by local-circuit current flow from one cell to the next through the gj

  1. Action Recognition using Motion Primitives

    DEFF Research Database (Denmark)

    Moeslund, Thomas B.; Fihl, Preben; Holte, Michael Boelstoft

    The number of potential applications has made automatic recognition of human actions a very active research area. Different approaches have been followed based on trajectories through some state space. In this paper we also model an action as a trajectory through a state space, but we represent...... the actions as a sequence of temporal isolated instances, denoted primitives. These primitives are each defined by four features extracted from motion images. The primitives are recognized in each frame based on a trained classifier resulting in a sequence of primitives. From this sequence we recognize...... different temporal actions using a probabilistic Edit Distance method. The method is tested on different actions with and without noise and the results show recognizing rates of 88.7% and 85.5%, respectively....

  2. Dendrite-derived supernumerary axons on adult axotomized motor neurons possess proteins that are essential for the initiation and propagation of action potentials and synaptic vesicle release

    DEFF Research Database (Denmark)

    Meehan, Claire Francesca; MacDermid, Victoria E; Montague, Steven J;

    2011-01-01

    on these processes matches the arrangement of these channels that is necessary for the initiation and conduction of action potentials. At terminal bouton-like structures they possess key proteins necessary for the release of synaptic vesicles (SV2 and synaptophysin). Thus, axon-like processes emanating from the tips...

  3. Potential Lung Nodules Identification for Characterization by Variable Multistep Threshold and Shape Indices from CT Images

    Directory of Open Access Journals (Sweden)

    Saleem Iqbal

    2014-01-01

    Full Text Available Computed tomography (CT is an important imaging modality. Physicians, surgeons, and oncologists prefer CT scan for diagnosis of lung cancer. However, some nodules are missed in CT scan. Computer aided diagnosis methods are useful for radiologists for detection of these nodules and early diagnosis of lung cancer. Early detection of malignant nodule is helpful for treatment. Computer aided diagnosis of lung cancer involves lung segmentation, potential nodules identification, features extraction from the potential nodules, and classification of the nodules. In this paper, we are presenting an automatic method for detection and segmentation of lung nodules from CT scan for subsequent features extraction and classification. Contribution of the work is the detection and segmentation of small sized nodules, low and high contrast nodules, nodules attached with vasculature, nodules attached to pleura membrane, and nodules in close vicinity of the diaphragm and lung wall in one-go. The particular techniques of the method are multistep threshold for the nodule detection and shape index threshold for false positive reduction. We used 60 CT scans of “Lung Image Database Consortium-Image Database Resource Initiative” taken by GE medical systems LightSpeed16 scanner as dataset and correctly detected 92% nodules. The results are reproducible.

  4. The potential value of intravascular ultrasound imaging in diagnosis of aortic intramural hematoma

    Institute of Scientific and Technical Information of China (English)

    Wei Hu; Francois Schiele; Nicolas Meneveau; Marie-France Seronde; Pierre Legalery; Jean-Francois Bonneville; Sidney Chocron; Jean-Pierre Bassand

    2011-01-01

    Objective To evaluate the potential value of intravascular ultrasound (IVUS) imaging in the diagnosis of aortic intramural hematoma (AIH).Methods From September 2002 to May 2005,a consecutive series of 15 patients with suspected aortic dissection (AD) underwent both IVUS imaging and spiral computed tomography (CT).Six patients diagnosed as acute type B AIH by CT or IVUS composed the present study group.Results The study group consisted of five males and one female with mean age of 66 years old.All of them had chest or back pain.In one patient,CT omitted a localized AIH and an associated penetrating atherosclerotic ulcer (PAU),which were detected by IVUS.In another patient,CT mistaken a partly thrombosed false lumen as an AIH,whereas IVUS detected a subtle intimal tear and slow moving blood in the false lumen.In the four rest patients,both CT and IVUS made the diagnosis of AIH,however,IVUS detected three PAUs in three of them,only one of them was also detected by CT,and two of them escaped initial CT and were confirmed by follow up CT or magnetic resonance imaging.Conclusions IVUS imaging is a safe examination and has high accuracy in the diagnosis of AIH,particularly for diagnosing localized AIH,distinguishing AIH with thrombosed classic AD and detecting accompanied small PAUs.

  5. Preparation and animal studies of a novel potential cerebral perfusion imaging agent

    International Nuclear Information System (INIS)

    Objective: To investigate a novel potential SPECT cerebral blood flow perfusion imaging agent. Methods: N2S tridentate α-mercaptol-propyl-1, 2-benzenediamine (MPBDA) was obtained from chemical synthesis IR and was labelled with 99Tcm. Biodistribution analysis in 25 mice was performed after intravenous injection of 100 μL 555 - 740 kBq of 99Tcm-MPBDA. Dynamic acquisition was performed after rapid intravenous injection of 218.3 - 333 MBq 99Tc-MPBDA or 99Tcm-ECD, while whole body imaging and brain perfusion imaging were done after 70 min in 2 normal monkeys. Preclinical studies including toxicity and pyrogen tests in mice and rabbits were undertaken. Results: The radiochemical synthetic yield and radiochemical purity of MPBDA labelled with 99Tcm were more than 95% and 97%, respectively. Mice biodistribution test showed the 99Tcm-MPBDA can concentrate in brain with good retention, and blood clearance Ty2 99Tcm-ECD (2.9% ID). SPECT imaging of cerebral gray and white matter showed good contrast with a clear contour. No toxic side affect in mice and rabbits after 99Tcm-MPBDA injection was found. Conclusion: Investigated 99Tcm-MPBDA has almost the same property as 99Tcm-ECD. It is safe and reliable in vivo

  6. Detection of incidental vertebral fractures in breast imaging: the potential role of MR localisers

    Energy Technology Data Exchange (ETDEWEB)

    Bazzocchi, Alberto [Orthopaedic Institute, Diagnostic and Interventional Radiology, Bologna (Italy); Bologna Univ. (Italy). Imaging Div.; Spinnato, Paolo; Garzillo, Giorgio; Ciccarese, Federica [Bologna Univ. (Italy). Imaging Div.; Albisinni, Ugo; Mignani, Stefano; Battista, Giuseppe [Orthopaedic Institute, Diagnostic and Interventional Radiology, Bologna (Italy); Rossi, Cristina [Parma Univ. (Italy). Imaging Div.

    2012-12-15

    Incidental diagnosis of vertebral fractures (VFs) may represent a key point in the assessment of bone health status. Our purpose was to retrospectively evaluate localisation sequences (MR-loc) of breast MRI as a potential tool to detect osteoporotic VFs. MR-loc sagittal images of 856 breast MRIs were reviewed by three expert musculoskeletal radiologists with a semiquantitative approach to detecting VFs. Anamnesis and data of patients were investigated. Official breast MRI and previous imaging reports were checked to understand if VFs or other relevant bone findings were known in patients' clinical history. A total of 780/856 female patients (91.1 %) undergoing MRI for oncological reasons and 76/856 (8.9 %) with non-oncological aims were recruited into the study (54.7 {+-} 12.2 years old, 21-89 years); 57/856 MR-loc images (6.7 %) were considered inadequate for diagnostic purposes and were excluded from the analysis. MR-loc detected VFs in 71/799 patients (8.9 %). VFs were neither reported nor previously known in the clinical history of 63/71 patients (88.7 %; P < 0.001). No mention of VFs was found in any breast MR reports. In four patients MR-loc identified vertebral metastases. A systematic evaluation of MR-loc may offer additional clinical information to prevent unrecognised VFs. MR-loc may screen for VFs in other imaging settings. (orig.)

  7. Imaging of human lymph nodes using optical coherence tomography: potential for staging cancer.

    Science.gov (United States)

    McLaughlin, Robert A; Scolaro, Loretta; Robbins, Peter; Hamza, Saud; Saunders, Christobel; Sampson, David D

    2010-04-01

    Histologic assessment is the gold standard technique for the identification of metastatic involvement of lymph nodes in malignant disease, but can only be performed ex vivo and often results in the unnecessary excision of healthy lymph nodes, leading to complications such as lymphedema. Optical coherence tomography (OCT) is a high-resolution, near-IR imaging modality capable of visualizing microscopic features within tissue. OCT has the potential to provide in vivo assessment of tissue involvement by cancer. In this morphologic study, we show the capability of OCT to image nodal microarchitecture through an assessment of fresh, unstained ex vivo lymph node samples. Examples include both benign human axillary lymph nodes and nodes containing metastatic breast carcinoma. Through accurate correlation with the histologic gold standard, OCT is shown to enable differentiation of lymph node tissue from surrounding adipose tissue, reveal nodal structures such as germinal centers and intranodal vessels, and show both diffuse and well circumscribed patterns of metastatic node involvement. PMID:20233873

  8. Measurement of charge transfer potential barrier in pinned photodiode CMOS image sensors

    Science.gov (United States)

    Chen, Cao; Bing, Zhang; Junfeng, Wang; Longsheng, Wu

    2016-05-01

    The charge transfer potential barrier (CTPB) formed beneath the transfer gate causes a noticeable image lag issue in pinned photodiode (PPD) CMOS image sensors (CIS), and is difficult to measure straightforwardly since it is embedded inside the device. From an understanding of the CTPB formation mechanism, we report on an alternative method to feasibly measure the CTPB height by performing a linear extrapolation coupled with a horizontal left-shift on the sensor photoresponse curve under the steady-state illumination. The theoretical study was performed in detail on the principle of the proposed method. Application of the measurements on a prototype PPD-CIS chip with an array of 160 × 160 pixels is demonstrated. Such a method intends to shine new light on the guidance for the lag-free and high-speed sensors optimization based on PPD devices. Project supported by the National Defense Pre-Research Foundation of China (No. 51311050301095).

  9. Porous Covalent Triazine Polymer as a Potential Nanocargo for Cancer Therapy and Imaging.

    Science.gov (United States)

    Rengaraj, Arunkumar; Puthiaraj, Pillaiyar; Haldorai, Yuvaraj; Heo, Nam Su; Hwang, Seung-Kyu; Han, Young-Kyu; Kwon, Soonjo; Ahn, Wha-Seung; Huh, Yun Suk

    2016-04-13

    A microporous covalent triazine polymer (CTP) network with a high surface area was synthesized via the Friedel-Crafts reaction and employed as a potential transport system for drug delivery and controlled release. The CTP was transformed to the nanoscale region by intense ultrasonication followed by filtration to yield nanoscale CTP (NCTP). This product showed excellent dispersibility in physiological solution while maintaining its chemical structure and porosity. An anticancer drug, doxorubicin (DOX), was loaded onto the NCTP through hydrophobic and π-π interactions, and its release was controlled at pH 4.8 and 7.4. The NCTP showed no toxicity toward cancer or normal cells, but the NCTP-DOX complex showed high efficacy against both types of cells in vitro. In-vitro cell imaging revealed that NCTP is a potential material for bioimaging. The potency of NCTP on cellular senescence was confirmed by the expression of senescence associated marker proteins p53 and p21. These results suggest that NCTP can be used as a new platform for drug delivery and imaging with potential applications in diagnosis and therapy. PMID:26998679

  10. A Comparative Study On The Action Potential Simulation (APS Therapy And The Routine Physiotherapy Protocol In Knee Osteoarthritisin Elderly People

    Directory of Open Access Journals (Sweden)

    Abbas Rahimi

    2012-04-01

    Full Text Available Background and Aim: Knee osteoarthritis is the most common cause for which the elderly people refere to physiotherapy outpatient clinics. This study aimed to investigate the effects of the Action Potential Stimulation (APS Therapy and the routine physiotherapy (PT protocol on relieving pain and swelling as well as the duration of the relief period in patients with knee osteoarthritis. Materials and Methods: 69 patients (62 females & 7 males with knee osteoarthritis were recruited in this study. The subjects were divided into two groups including APS Therapy (n=37, mean age: 55±13 years old and the routine PT protocol (n=32, mean age: 61±14 years old groups. A 10-session treatment period was carried out for each group; and their pain and swelling were measured at the first, fifth and tenth sessions and also one-month after the last session (follow up. The swelling was measured using measuring the circumference of the knee on the patella, 5 Cm above and 5 Cm below the patella. The routine PT protocol consisted of hot pack, ultrasound, TENS and exercise; and the APS therapy protocol included hot pack, APS Therapy and the same exercise. During the follow up, 50 out of 61 subjects were called on the phone and any pain changes were recorded.Results: In terms of swelling, the results showed significant reduction just on the patella only in the APS Therapy group (P<0.05. Visual Analogue Pain Scale (VAPS indicated a significant pain reduction in both groups. However, the APS Therapy group showed significantly pain reduction at the end of sessions five, ten and the follow up session (P<0.05. It was also revealed that while routine PT subjects showed no significant pain changes between the tenth and the follow up session, a gradual pain reduction was seen in the APS therapy group during this period (P<0.05. A gradual dosage reduction was recorded only in the APS therapy group, indicating a slight correlation with pain reduction (r=0.4.Conclusion: The

  11. Potential hazards to embryo implantation: A human endometrial in vitro model to identify unwanted antigestagenic actions of chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, L.; Deppert, W.R. [Department of Obstetrics and Gynecology, University Hospital Freiburg (Germany); Pfeifer, D. [Department of Hematology and Oncology, University Hospital Freiburg (Germany); Stanzel, S.; Weimer, M. [Department of Biostatistics, German Cancer Research Center, Heidelberg (Germany); Hanjalic-Beck, A.; Stein, A.; Straßer, M.; Zahradnik, H.P. [Department of Obstetrics and Gynecology, University Hospital Freiburg (Germany); Schaefer, W.R., E-mail: wolfgang.schaefer@uniklinik-freiburg.de [Department of Obstetrics and Gynecology, University Hospital Freiburg (Germany)

    2012-05-01

    Embryo implantation is a crucial step in human reproduction and depends on the timely development of a receptive endometrium. The human endometrium is unique among adult tissues due to its dynamic alterations during each menstrual cycle. It hosts the implantation process which is governed by progesterone, whereas 17β-estradiol regulates the preceding proliferation of the endometrium. The receptors for both steroids are targets for drugs and endocrine disrupting chemicals. Chemicals with unwanted antigestagenic actions are potentially hazardous to embryo implantation since many pharmaceutical antiprogestins adversely affect endometrial receptivity. This risk can be addressed by human tissue-specific in vitro assays. As working basis we compiled data on chemicals interacting with the PR. In our experimental work, we developed a flexible in vitro model based on human endometrial Ishikawa cells. Effects of antiprogestin compounds on pre-selected target genes were characterized by sigmoidal concentration–response curves obtained by RT-qPCR. The estrogen sulfotransferase (SULT1E1) was identified as the most responsive target gene by microarray analysis. The agonistic effect of progesterone on SULT1E1 mRNA was concentration-dependently antagonized by RU486 (mifepristone) and ZK137316 and, with lower potency, by 4-nonylphenol, bisphenol A and apigenin. The negative control methyl acetoacetate showed no effect. The effects of progesterone and RU486 were confirmed on the protein level by Western blotting. We demonstrated proof of principle that our Ishikawa model is suitable to study quantitatively effects of antiprogestin-like chemicals on endometrial target genes in comparison to pharmaceutical reference compounds. This test is useful for hazard identification and may contribute to reduce animal studies. -- Highlights: ► We compare progesterone receptor-mediated endometrial effects of chemicals and drugs. ► 4-Nonylphenol, bisphenol A and apigenin exert weak

  12. A computational model of the ionic currents, Ca2+ dynamics and action potentials underlying contraction of isolated uterine smooth muscle.

    Directory of Open Access Journals (Sweden)

    Wing-Chiu Tong

    Full Text Available Uterine contractions during labor are discretely regulated by rhythmic action potentials (AP of varying duration and form that serve to determine calcium-dependent force production. We have employed a computational biology approach to develop a fuller understanding of the complexity of excitation-contraction (E-C coupling of uterine smooth muscle cells (USMC. Our overall aim is to establish a mathematical platform of sufficient biophysical detail to quantitatively describe known uterine E-C coupling parameters and thereby inform future empirical investigations of physiological and pathophysiological mechanisms governing normal and dysfunctional labors. From published and unpublished data we construct mathematical models for fourteen ionic currents of USMCs: Ca2+ currents (L- and T-type, Na+ current, an hyperpolarization-activated current, three voltage-gated K+ currents, two Ca2+-activated K+ current, Ca2+-activated Cl current, non-specific cation current, Na+-Ca2+ exchanger, Na+-K+ pump and background current. The magnitudes and kinetics of each current system in a spindle shaped single cell with a specified surface area:volume ratio is described by differential equations, in terms of maximal conductances, electrochemical gradient, voltage-dependent activation/inactivation gating variables and temporal changes in intracellular Ca2+ computed from known Ca2+ fluxes. These quantifications are validated by the reconstruction of the individual experimental ionic currents obtained under voltage-clamp. Phasic contraction is modeled in relation to the time constant of changing [Ca2+]i. This integrated model is validated by its reconstruction of the different USMC AP configurations (spikes, plateau and bursts of spikes, the change from bursting to plateau type AP produced by estradiol and of simultaneous experimental recordings of spontaneous AP, [Ca2+]i and phasic force. In summary, our advanced mathematical model provides a powerful tool to

  13. Magnetic resonance imaging interpretation in patients with sciatica who are potential candidates for lumbar disc surgery.

    Directory of Open Access Journals (Sweden)

    Abdelilah El Barzouhi

    Full Text Available BACKGROUND: Magnetic Resonance Imaging (MRI is considered the mainstay imaging investigation in patients suspected of lumbar disc herniations. Both imaging and clinical findings determine the final decision of surgery. The objective of this study was to assess MRI observer variation in patients with sciatica who are potential candidates for lumbar disc surgery. METHODS: Patients for this study were potential candidates (n = 395 for lumbar disc surgery who underwent MRI to assess eligibility for a randomized trial. Two neuroradiologists and one neurosurgeon independently evaluated all MRIs. A four point scale was used for both probability of disc herniation and root compression, ranging from definitely present to definitely absent. Multiple characteristics of the degenerated disc herniation were scored. For inter-agreement analysis absolute agreements and kappa coefficients were used. Kappa coefficients were categorized as poor (<0.00, slight (0.00-0.20, fair (0.21-0.40, moderate (0.41-0.60, substantial (0.61-0.80 and excellent (0.81-1.00 agreement. RESULTS: Excellent agreement was found on the affected disc level (kappa range 0.81-0.86 and the nerve root that most likely caused the sciatic symptoms (kappa range 0.86-0.89. Interobserver agreement was moderate to substantial for the probability of disc herniation (kappa range 0.57-0.77 and the probability of nerve root compression (kappa range 0.42-0.69. Absolute pairwise agreement among the readers ranged from 90-94% regarding the question whether the probability of disc herniation on MRI was above or below 50%. Generally, moderate agreement was observed regarding the characteristics of the symptomatic disc level and of the herniated disc. CONCLUSION: The observer variation of MRI interpretation in potential candidates for lumbar disc surgery is satisfactory regarding characteristics most important in decision for surgery. However, there is considerable variation between observers in specific

  14. Second-Harmonic Generation Imaging of Membrane Potential with Retinal Analogues

    OpenAIRE

    Theer, Patrick; Denk, Winfried; Sheves, Mordechai; Lewis, Aaron; Detwiler, Peter B.

    2011-01-01

    Second-harmonic generation (SHG) by membrane-incorporated probes is a nonlinear optical signal that is voltage-sensitive and the basis of a sensitive method for imaging membrane potential. The voltage dependence of SHG by four different probes, three retinoids (all-trans retinal), and two new retinal analogs, 3-methyl-7-(4′-dimethylamino-phenyl)-2,4,6-heptatrienal (AR-3) and 3,7-dimethyl-9-(4′-dimethylamino-phenyl)-2,4,6,8-nonatetraenal (AR-4), and a styryl dye (FM4-64), were compared in HEK-...

  15. Imaging imagining actions

    OpenAIRE

    Olsson, CJ

    2008-01-01

    Mental training has been studied extensively for the past century but we are still not completely sure how it affects brain and behavior. The aim of this doctoral thesis was to examine one aspect of mental training i.e. motor imagery. In Study I, active high jumpers were trained for 6 weeks using a motor imagery mental training program. We measured behavioral effects in motor parameters such as total height, false attempts, take off angle, and bar clearance. A significant improvement was foun...

  16. Anti-cancer and potential chemopreventive actions of ginseng by activating Nrf2 (NFE2L2 anti-oxidative stress/anti-inflammatory pathways

    Directory of Open Access Journals (Sweden)

    Wu Qing

    2010-10-01

    Full Text Available Abstract This article reviews recent basic and clinical studies of ginseng, particularly the anti-cancer effects and the potential chemopreventive actions by activating the transcriptional factor, nuclear factor (erythroid-derived 2-like 2 (Nrf2 or NFE2L2-mediated anti-oxidative stress or anti-inflammatory pathways. Nrf2 is a novel target for cancer prevention as it regulates the antioxidant responsive element (ARE, a critical regulatory element in the promoter region of genes encoding cellular phase II detoxifying and anti-oxidative stress enzymes. The studies on the chemopreventive effects of ginseng or its components/products showed that Nrf2 could also be a target for ginseng's actions. A number of papers also demonstrated the anti-inflammatory effects of ginseng. Targeting Nrf2 pathway is a novel approach to the investigation of ginseng's cancer chemopreventive actions, including some oxidative stress and inflammatory conditions responsible for the initiation, promotion and progression of carcinogenesis.

  17. Current Clinical Applications and Future Potential of Diffusion Tensor Imaging in Traumatic Brain Injury.

    Science.gov (United States)

    Strauss, Sara; Hulkower, Miriam; Gulko, Edwin; Zampolin, Richard L; Gutman, David; Chitkara, Munish; Zughaft, Malka; Lipton, Michael L

    2015-12-01

    In the setting of acute central nervous system (CNS) emergencies, computed tomography (CT) and conventional magnetic resonance imaging (MRI) play an important role in the identification of life-threatening intracranial injury. However, the full extent or even presence of brain damage frequently escapes detection by conventional CT and MRI. Advanced MRI techniques such as diffusion tensor imaging (DTI) are emerging as important adjuncts in the diagnosis of microstructural white matter injury in the acute and postacute brain-injured patient. Although DTI aids in detection of brain injury pathology, which has been repeatedly associated with typical adverse clinical outcomes, the evolution of acute changes and their long-term prognostic implications are less clear and the subject of much active research. A major aim of current research is to identify imaging-based biomarkers that can identify the subset of TBI patients who are at risk for adverse outcome and can therefore most benefit from ongoing care and rehabilitation as well as future therapeutic interventions.The aim of this study is to introduce the current methods used to obtain DTI in the clinical setting, describe a set of common interpretation strategies with their associated advantages and pitfalls, as well as illustrate the clinical utility of DTI through a set of specific patient scenarios. We conclude with a discussion of future potential for the management of TBI.

  18. Potential damage of GM crops to the country image of the producing country.

    Science.gov (United States)

    Knight, John G; Clark, Allyson; Mather, Damien W

    2013-01-01

    Frequently heard within New Zealand are arguments that release of genetically modified organisms (GMOs) into the environment will harm the "clean green" image of the country, and therefore do irreparable harm to export markets for food products and also to the New Zealand tourism industry. But where is the evidence? To investigate the likelihood of harmful effects on New Zealand's clean green image in relation to food exports, we have previously used face-to-face interviews with gatekeepers in the food distribution channel in five countries in Europe, in China, and in India. To investigate potential impacts on the New Zealand tourism sector, we have surveyed first-time visitors to New Zealand at Auckland International Airport soon after arrival. We conclude that it is highly unlikely that introduction of GM plants into New Zealand would have any long-term deleterious effect on perceptions in overseas markets of food products sourced from New Zealand. Furthermore it is highly unlikely that New Zealand's image as a tourist destination would suffer if GM plants were introduced. PMID:24002524

  19. ASPECTS REGARDING THE FACEBOOK USER IN ROMANIA AS A POTENTIAL DESTINATION IMAGE - VECTOR

    Directory of Open Access Journals (Sweden)

    MIHAIL-CRISTIAN DIȚOIU

    2011-01-01

    Full Text Available The Internet’s rapid development from the 1.0 version to the 2.0 one has triggered the appearance of social networks. Facebook is Illustrative of them due to the number of users it attracts and its international range of dispersion. Although a beginner in communication, Facebook Romania is prone to contribute highly to the “content generator” market in what concerns its users. In order to create or maintain a brand’s positive image it is necessary to know some elements regarding the demographic aspects of the target public, and its attitudes, predilections or behaviours in general. Thus, web pages created on Facebook can “transform” its users into fans and there is a possibility that afterwards these fans become image -vectors by way of the delivered experiences. This article tries to study the fundamental elements that could make up the profile of a user from the targeted group as a potential destination image- vector.

  20. Potential damage of GM crops to the country image of the producing country.

    Science.gov (United States)

    Knight, John G; Clark, Allyson; Mather, Damien W

    2013-01-01

    Frequently heard within New Zealand are arguments that release of genetically modified organisms (GMOs) into the environment will harm the "clean green" image of the country, and therefore do irreparable harm to export markets for food products and also to the New Zealand tourism industry. But where is the evidence? To investigate the likelihood of harmful effects on New Zealand's clean green image in relation to food exports, we have previously used face-to-face interviews with gatekeepers in the food distribution channel in five countries in Europe, in China, and in India. To investigate potential impacts on the New Zealand tourism sector, we have surveyed first-time visitors to New Zealand at Auckland International Airport soon after arrival. We conclude that it is highly unlikely that introduction of GM plants into New Zealand would have any long-term deleterious effect on perceptions in overseas markets of food products sourced from New Zealand. Furthermore it is highly unlikely that New Zealand's image as a tourist destination would suffer if GM plants were introduced.

  1. ‘Out of the box’: exploring the 3D modelling potential of ancient image archives

    Directory of Open Access Journals (Sweden)

    Elías López-Romero

    2014-05-01

    Full Text Available 3D reconstructions for research and conservation of archaeological sites and objects are becoming increasingly common as laser and photogrammetric techniques are now more readily accessible to non-specialists. Most of these imaging techniques have been applied to sites and/or objects that can be physically visited, handled, measured and studied in various ways. However, little or no attention has been paid to the potential of modern 3D modelling techniques for obtaining new quantitative and qualitative information from sites and objects which have been destroyed or are no longer accessible. This paper explores the potential of Structure from Motion (SfM to provide fresh insight into the scientific exploitation of ancient image archives. Two case studies from Western France will be used to illustrate this: a series of photographs of one decorated orthostate from the Neolithic gallery grave of Kermorvan (Le Conquet, Finistère, dating from 1911-12, and a 12-minute video of the excavation of a Bronze Age mound in Kervingar (Ploudalmézeau, Finistère, dating from 1953.

  2. Molecular markers and imaging tools to identify malignant potential in Barrett’s esophagus

    Institute of Scientific and Technical Information of China (English)

    Michael; Bennett; Hiroshi; Mashimo

    2014-01-01

    Due to its rapidly rising incidence and high mortality, esophageal adenocarcinoma is a major public health concern, particularly in Western countries. The steps involved in the progression from its predisposing condition, gastroesophageal reflux disease, to its premalignant disorder, Barrett’s esophagus, and to cancer, are incompletely understood. Current screening and surveillance methods are limited by the lack of population-wide utility, incomplete sampling of standard biopsies, and subjectivity of evaluation. Advances in endoscopic ablation have raised the hope of effective therapy for eradication of high-risk Barrett’s lesions, but improvements are needed in determining when to apply this treatment and how to follow patients clinically. Researchers have evaluated numerous potential molecular biomarkers with the goal of detecting dysplasia, with varying degrees of success. The combination of biomarker panels with epidemiologic risk factors to yield clinical risk scoring systems is promising. New approaches to sample tissue may also be combined with these biomarkers for less invasive screening and sur-veillance. The development of novel endoscopic imaging tools in recent years has the potential to markedly improve detection of small foci of dysplasia in vivo. Current and future efforts will aim to determine the combination of markers and imaging modalities that will most effectively improve the rate of early detection of highrisk lesions in Barrett’s esophagus.

  3. Hyperpolarized 3He magnetic resonance imaging: Preliminary evaluation of phenotyping potential in chronic obstructive pulmonary disease

    International Nuclear Information System (INIS)

    Rationale and objectives: Emphysema and small airway obstruction are the pathological hallmarks of chronic obstructive pulmonary disease (COPD). The aim of this pilot study in a small group of chronic obstructive pulmonary disease (COPD) patients was to quantify hyperpolarized helium-3 (3He) magnetic resonance imaging (MRI) functional and structural measurements and to explore the potential role for 3He MRI in detecting the lung structural and functional COPD phenotypes. Materials and methods: We evaluated 20 ex-smokers with stage I (n = 1), stage II (n = 9) and stage III COPD (n = 10). All subjects underwent same-day plethysmography, spirometry, 1H MRI and hyperpolarized 3He MRI at 3.0 T. 3He ventilation defect percent (VDP) was generated from 3He static ventilation images and 1H thoracic images and the 3He apparent diffusion coefficient (ADC) was derived from diffusion-weighted MRI. Results: Based on the relative contribution of normalized ADC and VDP, there was evidence of a predominant 3He MRI measurement in seven patients (n = 3 mainly ventilation defects or VDP dominant (VD), n = 4 mainly increased ADC or ADC dominant (AD)). Analysis of variance (ANOVA) showed significantly lower ADC for subjects with predominantly elevated VDP (p = 0.02 compared to subjects with predominantly elevated ADC; p = 0.008 compared to mixed group) and significantly decreased VDP for subjects with predominantly elevated ADC (p = 0.003, compared to mixed group). Conclusion: In this small pilot study, a preliminary analysis shows the potential for 3He MRI to categorize or phenotype COPD ex-smokers, providing good evidence of feasibility for larger prospective studies.

  4. Characterization of potential mineralization in Afghanistan: four permissive areas identified using imaging spectroscopy data

    Science.gov (United States)

    King, Trude V.V.; Berger, Byron R.; Johnson, Michaela R.

    2014-01-01

    As part of the U.S. Geological Survey and Department of Defense Task Force for Business and Stability Operations natural resources revitalization activities in Afghanistan, four permissive areas for mineralization, Bamyan 1, Farah 1, Ghazni 1, and Ghazni 2, have been identified using imaging spectroscopy data. To support economic development, the areas of potential mineralization were selected on the occurrence of selected mineral assemblages mapped using the HyMap™ data (kaolinite, jarosite, hydrated silica, chlorite, epidote, iron-bearing carbonate, buddingtonite, dickite, and alunite) that may be indicative of past mineralization processes in areas with limited or no previous mineral resource studies. Approximately 30 sites were initially determined to be candidates for areas of potential mineralization. Additional criteria and material used to refine the selection and prioritization process included existing geologic maps, Landsat Thematic Mapper data, and published literature. The HyMapTM data were interpreted in the context of the regional geologic and tectonic setting and used the presence of alteration mineral assemblages to identify areas with the potential for undiscovered mineral resources. Further field-sampling, mapping, and supporting geochemical analyses are necessary to fully substantiate and verify the specific deposit types in the four areas of potential mineralization.

  5. Hemodynamic response imaging: a potential tool for the assessment of angiogenesis in brain tumors.

    Directory of Open Access Journals (Sweden)

    Dafna Ben Bashat

    Full Text Available Blood oxygenation level dependence (BOLD imaging under either hypercapnia or hyperoxia has been used to study neuronal activation and for assessment of various brain pathologies. We evaluated the benefit of a combined protocol of BOLD imaging during both hyperoxic and hypercapnic challenges (termed hemodynamic response imaging (HRI. Nineteen healthy controls and seven patients with primary brain tumors were included: six with glioblastoma (two newly diagnosed and four with recurrent tumors and one with atypical-meningioma. Maps of percent signal intensity changes (ΔS during hyperoxia (carbogen; 95%O2+5%CO2 and hypercapnia (95%air+5%CO2 challenges and vascular reactivity mismatch maps (VRM; voxels that responded to carbogen with reduced/absent response to CO2 were calculated. VRM values were measured in white matter (WM and gray matter (GM areas of healthy subjects and used as threshold values in patients. Significantly higher response to carbogen was detected in healthy subjects, compared to hypercapnia, with a GM/WM ratio of 3.8 during both challenges. In patients with newly diagnosed/treatment-naive tumors (n = 3, increased response to carbogen was detected with substantially increased VRM response (compared to threshold values within and around the tumors. In patients with recurrent tumors, reduced/absent response during both challenges was demonstrated. An additional finding in 2 of 4 patients with recurrent glioblastoma was a negative response during carbogen, distant from tumor location, which may indicate steal effect. In conclusion, the HRI method enables the assessment of blood vessel functionality and reactivity. Reference values from healthy subjects are presented and preliminary results demonstrate the potential of this method to complement perfusion imaging for the detection and follow up of angiogenesis in patients with brain tumors.

  6. Imaging brain gene expression profiles by antipsychotics: region-specific action of amisulpride on postsynaptic density transcripts compared to haloperidol.

    Science.gov (United States)

    de Bartolomeis, Andrea; Marmo, Federica; Buonaguro, Elisabetta Filomena; Rossi, Rodolfo; Tomasetti, Carmine; Iasevoli, Felice

    2013-11-01

    Induction of motor disorders is considered the clinical landmark differentiating typical from atypical antipsychotics, and has been mainly correlated to dopamine D2 receptors blockade in striatum. This view is challenged by benzamides, such as amisulpride, which display low liability for motor side effects despite being D2/D3 receptors high-affinity blocking agents. These effects have been explained with the prominent presynaptic action of amisulpride or with the fast dissociation at D2 receptors, but there is scarce information on the effects of amisulpride on postsynaptic signaling. We carried out a molecular imaging study of gene expression after acute administration of haloperidol (0.8 mg/kg), amisulpride (10 or 35 mg/kg), or vehicle, focusing on postsynaptic genes that are key regulators of synaptic plasticity, such as Arc, c-fos, Zif-268, Norbin, Homer. The last one has been associated to schizophrenia both in clinical and preclinical studies, and is differentially induced by antipsychotics with different D2 receptors affinity. Topography of gene expression revealed that amisulpride, unlike haloperidol, triggers transcripts expression peak in medial striatal regions. Correlation analysis of gene expression revealed a prevalent correlated gene induction within motor corticostriatal regions by haloperidol and a more balanced gene induction within limbic and motor corticostriatal regions by amisulpride. Despite the selective dopaminergic profile of both compounds, our results demonstrated a differential modulation of postsynaptic molecules by amisulpride and haloperidol, the former impacting preferentially medial regions of striatum whereas the latter inducing strong gene expression in lateral regions. Thus, we provided a possible molecular profile of amisulpride, putatively explaining its "atypical atypicality".

  7. Assessment of Tumor Radioresponsiveness and Metastatic Potential by Dynamic Contrast-Enhanced Magnetic Resonance Imaging

    International Nuclear Information System (INIS)

    Purpose: It has been suggested that gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) may provide clinically useful biomarkers for personalized cancer treatment. In this preclinical study, we investigated the potential of DCE-MRI as a noninvasive method for assessing the radioresponsiveness and metastatic potential of tumors. Methods and Materials: R-18 melanoma xenografts growing in BALB/c nu/nu mice were used as experimental tumor models. Fifty tumors were subjected to DCE-MRI, and parametric images of Ktrans (the volume transfer constant of Gd-DTPA) and ve (the fractional distribution volume of Gd-DTPA) were produced by pharmacokinetic analysis of the DCE-MRI series. The tumors were irradiated after the DCE-MRI, either with a single dose of 10 Gy for detection of radiobiological hypoxia (30 tumors) or with five fractions of 4 Gy in 48 h for assessment of radioresponsiveness (20 tumors). The host mice were then euthanized and examined for lymph node metastases, and the primary tumors were resected for measurement of cell survival in vitro. Results: Tumors with hypoxic cells showed significantly lower Ktrans values than tumors without significant hypoxia (p trans decreased with increasing cell surviving fraction for tumors given fractionated radiation treatment (p trans values than tumors in metastasis-negative mice (p e and tumor hypoxia, radioresponsiveness, or metastatic potential could not be detected. Conclusions: R-18 tumors with low Ktrans values are likely to be resistant to radiation treatment and have a high probability of developing lymph node metastases. The general validity of these observations should be investigated further by studying preclinical tumor models with biological properties different from those of the R-18 tumors.

  8. Promoting HIV Vaccine Research in African American Communities: Does the Theory of Reasoned Action Explain Potential Outcomes of Involvement?

    OpenAIRE

    Frew, Paula M; Archibald, Matthew; Martinez, Nina; del Rio, Carlos; Mulligan, Mark J.

    2007-01-01

    The HIV/AIDS pandemic continues to challenge the African American community with disproportionate rates of infection, particularly among young women ages 25 to 34 years. Development of a preventive HIV vaccine may bring a substantial turning point in this health crisis. Engagement of the African American community is necessary to improve awareness of the effort and favorably influence attitudes and referent norms. The Theory of Reasoned Action (TRA) may be a useful framework for exploration o...

  9. Early Afterdepolarizations with Growing Amplitudes via Delayed Subcritical Hopf Bifurcations and Unstable Manifolds of Saddle Foci in Cardiac Action Potential Dynamics

    Science.gov (United States)

    Kügler, Philipp

    2016-01-01

    Early afterdepolarizations (EADs) are pathological oscillations in cardiac action potentials during the repolarization phase and may be caused by drug side effects, ion channel disease or oxidative stress. The most widely observed EAD pattern is characterized by oscillations with growing amplitudes. So far, its occurence has been explained in terms of a supercritical Hopf bifurcation in the fast subsystem of the action potential dynamics from which stable limit cycles with growing amplitudes emerge. The novel contribution of this article is the introduction of two alternative explanations of EAD genesis with growing amplitudes that do not involve stable limit cycles in fast subsystems. In particular, we demonstrate that EAD patterns with growing amplitudes may alternatively arise due to a delayed subcritical Hopf bifurcation or an unstable manifold of a saddle focus fixed point in the full fast-slow system modelling the action potential. Our work extends the list of possible dynamical EAD mechanisms and may contribute to a classification of drug effects in preclinical cardiotoxicity testing. PMID:26977805

  10. Tumor imaging and targeting potential of an Hsp70-derived 14-mer peptide.

    Directory of Open Access Journals (Sweden)

    Mathias Gehrmann

    Full Text Available BACKGROUND: We have previously used a unique mouse monoclonal antibody cmHsp70.1 to demonstrate the selective presence of a membrane-bound form of Hsp70 (memHsp70 on a variety of leukemia cells and on single cell suspensions derived from solid tumors of different entities, but not on non-transformed cells or cells from corresponding 'healthy' tissue. This antibody can be used to image tumors in vivo and target them for antibody-dependent cellular cytotoxicity. Tumor-specific expression of memHsp70 therefore has the potential to be exploited for theranostic purposes. Given the advantages of peptides as imaging and targeting agents, this study assessed whether a 14-mer tumor penetrating peptide (TPP; TKDNNLLGRFELSG, the sequence of which is derived from the oligomerization domain of Hsp70 which is expressed on the cell surface of tumor cells, can also be used for targeting membrane Hsp70 positive (memHsp70+ tumor cells, in vitro. METHODOLOGY/PRINCIPAL FINDINGS: The specificity of carboxy-fluorescein (CF- labeled TPP (TPP to Hsp70 was proven in an Hsp70 knockout mammary tumor cell system. TPP specifically binds to different memHsp70+ mouse and human tumor cell lines and is rapidly taken up via endosomes. Two to four-fold higher levels of CF-labeled TPP were detected in MCF7 (82% memHsp70+ and MDA-MB-231 (75% memHsp70+ cells compared to T47D cells (29% memHsp70+ that exhibit a lower Hsp70 membrane positivity. After 90 min incubation, TPP co-localized with mitochondrial membranes in memHsp70+ tumors. Although there was no evidence that any given vesicle population was specifically localized, fluorophore-labeled cmHsp70.1 antibody and TPP preferentially accumulated in the proximity of the adherent surface of cultured cells. These findings suggest a potential association between membrane Hsp70 expression and cytoskeletal elements that are involved in adherence, the establishment of intercellular synapses and/or membrane reorganization. CONCLUSIONS

  11. Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS): features and potential applications in oncology

    Energy Technology Data Exchange (ETDEWEB)

    Kwee, Thomas C.; Takahara, Taro; Nievelstein, Rutger A.J.; Luijten, Peter R. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Ochiai, Reiji [Koga Hospital 21, Department of Radiology, Kurume (Japan)

    2008-09-15

    Diffusion-weighted magnetic resonance imaging (DWI) provides functional information and can be used for the detection and characterization of pathologic processes, including malignant tumors. The recently introduced concept of ''diffusion-weighted whole-body imaging with background body signal suppression'' (DWIBS) now allows acquisition of volumetric diffusion-weighted images of the entire body. This new concept has unique features different from conventional DWI and may play an important role in whole-body oncological imaging. This review describes and illustrates the basics of DWI, the features of DWIBS, and its potential applications in oncology. (orig.)

  12. Dynamic Contrast-Enhanced Magnetic Resonance Imaging of the Metastatic Potential of Melanoma Xenografts

    Energy Technology Data Exchange (ETDEWEB)

    Ovrebo, Kirsti Marie; Ellingsen, Christine; Galappathi, Kanthi [Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo (Norway); Rofstad, Einar K., E-mail: einar.k.rofstad@rr-research.no [Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo (Norway)

    2012-05-01

    Purpose: Gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been suggested as a useful noninvasive method for characterizing the physiologic microenvironment of tumors. In the present study, we investigated whether Gd-DTPA-based DCE-MRI has the potential to provide biomarkers for hypoxia-associated metastatic dissemination. Methods and Materials: C-10 and D-12 melanoma xenografts were used as experimental tumor models. Pimonidazole was used as a hypoxia marker. A total of 60 tumors were imaged, and parametric images of K{sup trans} (volume transfer constant of Gd-DTPA) and v{sub e} (fractional distribution volume of Gd-DTPA) were produced by pharmacokinetic analysis of the DCE-MRI series. The host mice were killed immediately after DCE-MRI, and the primary tumor and the lungs were resected and prepared for histologic assessment of the fraction of pimonidazole-positive hypoxic tissue and the presence of lung metastases, respectively. Results: Metastases were found in 11 of 26 mice with C-10 tumors and 14 of 34 mice with D-12 tumors. The primary tumors of the metastatic-positive mice had a greater fraction of hypoxic tissue (p = 0.00031, C-10; p < 0.00001, D-12), a lower median K{sup trans} (p = 0.0011, C-10; p < 0.00001, D-12), and a lower median v{sub e} (p = 0.014, C-10; p = 0.016, D-12) than the primary tumors of the metastatic-negative mice. Conclusions: These findings support the clinical attempts to establish DCE-MRI as a method for providing biomarkers for tumor aggressiveness and suggests that primary tumors characterized by low K{sup trans} and low v{sub e} values could have a high probability of hypoxia-associated metastatic spread.

  13. Evaluation of 7 {alpha}-O-IADPN as a new potential SPECT opioid receptor imaging agent

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.F.; Mao, S.Y. [Fujian Medical College, Fuzhou (China). Dept. of Nuclear Medicine; Tafani, J.A.M.; Coulais, Y.; Guiraud, R. [Hospital Purpan, Toulouse (France). Service Central de medicine Nucleaire; Zajac, J.M. [LPTF-CNRS, Toulouse (France)

    1998-03-01

    Full text: A new iodinated diprenorphine antagonist analogue, [{sup 123}I]7 {alpha}.-O-IADPN, [E] - 17-(cyclopropylmethyl) -4,5 (x-epoxy- 18,19-dihydro-3-hydroxy-6-methoxy-7 {alpha}-[1-(3-iodoallyl)oxy-1-methylethyl]-6,14-endo-ethenomorphinan for in vivo and in vitro studies as a potential central nervous system (CNS) opioid receptor imaging agent was developed. In vivo biodistribution and metabolism of 7 {alpha}-O-lADPN in rat demonstrated that 0.16% of the iodinated compound was presented in mouse brain with a degradation-resistant at the first 60 min, and that 36% of the total cerebral radioactivity and 63% of its specific binding to opioid receptors were observed 20 min after i.v. injection. The cerebral radioactivity in mouse brain concentrated in the basal ganglion and cortex, and displayed a remarkably high target-to-non-target ratio (cortex/cerebellum = 60 min post-injection). The in vitro binding studies showed that [{sup 123}I]7 {alpha}-O-IADPN binds non selectively to multiple opioid receptors {mu} = 8 K) with a very high affinity (Ki = 0.4 + 0.2 nM). Ex vivo autoradiography results in mouse further confirmed the high uptake and retention of this agent in basal ganglion region and cortex. The planar imaging of monkey brains after i.v. injection of [{sup 123}I]7 {alpha}-O-IADPN clearly displayed that multiple opioid receptors can be visualized. With the excellent in vitro affinity and in vivo stability to deiodination and high target-to-nontarget ratio, [{sup 123}I]7 {alpha}- O-IADPN appears to be useful as a CNS opioid receptor imaging probe for SPECT in primate and non-primate.

  14. Magnetic resonance imaging compared with trimodal evoked potentials in possible multiple sclerosis

    International Nuclear Information System (INIS)

    Magnetic Resonance Imaging (MRI) of the brain and Evoked Potentials (EP) can both demonstrate the presence of clinically unsuspected demyelinating lesions and have proven to be sensitive (but not specific) in the diagnosis of multiple sclerosis (MS). MRI and EP are positive in 90 to 100% of patients with a definite diagnosis of MS. However, few studies have been conducted in patients with a lesser diagnostic certainty. In possible or suspected MS they gave conflicting results, possibly because of technical discrepancies and different clinical inclusion criteria. Since a number of putative new treatments can be evaluated in patients who have a definite diagnosis of MS, but nevertheless a short duration of disease and a low disability, it was decided to compare the sensitivity of MRI and EP as diagnostic tools in possible MS patients. MRI is shown to be more sensitive, shows more multiple lesions and gives a clearer appreciation of their size and exact location than EP. 10 refs.; 3 tabs

  15. Rashba splitting in an image potential state investigated by circular dichroism two-photon photoemission spectroscopy

    Science.gov (United States)

    Nakazawa, T.; Takagi, N.; Kawai, Maki; Ishida, H.; Arafune, R.

    2016-09-01

    We have explored the band splitting and spin texture of the image potential state (IPS) on Au(001) derived from the Rashba-type spin-orbit interaction (SOI) by using angle-resolved bichromatic two-photon photoemission (2PPE) spectroscopy in combination with circular dichroism (CD). The Rashba parameter for the first (n =1 ) IPS is determined to be 48-20+8meV Å , which is consistent with the spin-polarized band structure calculated from the embedded Green's function technique for semi-infinite crystals. The present results demonstrate that bichromatic CD-2PPE spectroscopy is powerful for mapping the spin-polarized unoccupied band structures originating from SOIs in various classes of condensed matter.

  16. Primary study of a novel Tc-tricarbonyl cocaine analogue as the potential DAT imaging agent

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaobo; ZHU Lin; DING Shaoke; LIU Boli

    2005-01-01

    The convenient preparation of organometallic precursor fac-[99mTc(CO)3 (H2O)3]+ opens a new route to design new radiopharmaceuticals. Based on this precursor, a new cocaine analogue, Tropyn, is designed and synthesized, and "2+1" mixed-ligands approach is used to prepare a neutral complex [99mTc(CO)3(Tropyn)I]. Biodistribution in mice and rats proves that it has sufficient brain uptake. Rat regional brain biodistribution indicates that the complex is highly concentrated in the striatum (ST) with rapid clearance in the cortex (CT) and hippocampus (HP), which make it valuable for further investigation as the potential Second-Generation DAT imaging agent.

  17. Porous metal-organic-framework nanoscale carriers as a potential platform for drug delivery and imaging

    Science.gov (United States)

    Horcajada, Patricia; Chalati, Tamim; Serre, Christian; Gillet, Brigitte; Sebrie, Catherine; Baati, Tarek; Eubank, Jarrod F.; Heurtaux, Daniela; Clayette, Pascal; Kreuz, Christine; Chang, Jong-San; Hwang, Young Kyu; Marsaud, Veronique; Bories, Phuong-Nhi; Cynober, Luc; Gil, Sophie; Férey, Gérard; Couvreur, Patrick; Gref, Ruxandra

    2010-02-01

    In the domain of health, one important challenge is the efficient delivery of drugs in the body using non-toxic nanocarriers. Most of the existing carrier materials show poor drug loading (usually less than 5wt% of the transported drug versus the carrier material) and/or rapid release of the proportion of the drug that is simply adsorbed (or anchored) at the external surface of the nanocarrier. In this context, porous hybrid solids, with the ability to tune their structures and porosities for better drug interactions and high loadings, are well suited to serve as nanocarriers for delivery and imaging applications. Here we show that specific non-toxic porous iron(III)-based metal-organic frameworks with engineered cores and surfaces, as well as imaging properties, function as superior nanocarriers for efficient controlled delivery of challenging antitumoural and retroviral drugs (that is, busulfan, azidothymidine triphosphate, doxorubicin or cidofovir) against cancer and AIDS. In addition to their high loadings, they also potentially associate therapeutics and diagnostics, thus opening the way for theranostics, or personalized patient treatments.

  18. Mesoporous europo-gadolinosilicate nanoparticles as bimodal medical imaging agents and a potential theranostic platform.

    Science.gov (United States)

    Tse, Nicholas M K; Kennedy, Danielle F; Kirby, Nigel; Moffat, Bradford A; Muir, Benjamin W; Caruso, Rachel A; Drummond, Calum J

    2013-06-01

    The mesoporous structure of sol-gel prepared gadolinium and europium doped silicate nanoparticles has been found to be highly dependent on the formulated composition, with synthesised samples displaying both disordered and hexagonally ordered mesoporous packing symmetry. The degree of pore ordering within the nanoparticles has a strong correlation with the total lanthanide (Gd(3+) and Eu(3+) ) concentration. The gadolinosilicates are excellent magnetic resonance imaging (MRI) longitudinal (T1 ) agents. The longitudinal relaxivity (r1 ) and transverse (r2 ) relaxivity, a measure of MRI contrast agent efficiency, were up to four times higher than the clinically employed Omniscan (gadodiamide); with r1 up to 20.6 s(-1) mM(-1) and r2 of 66.2 s(-1) mM(-1) compared to 5.53 and 4.64 s(-1) mM(-1) , respectively, for Omniscan. In addition, the europium content of all the samples studied is below the self-quenching limit, which results in a strong luminescence response from the nanoparticles on excitation at 250 nm. The Eu-Gd silicate nanoparticles act as bimodal imaging agents for MRI and luminescence. These mesoporous nanoparticles also have the potential to serve as encapsulation and controlled release matrices for pharmaceuticals. They are therefore a promising multimodal theranostic platform. PMID:23296572

  19. Imaging of normal and pathologic joint synovium using nonlinear optical microscopy as a potential diagnostic tool

    Science.gov (United States)

    Tiwari, Nivedan; Chabra, Sanjay; Mehdi, Sheherbano; Sweet, Paula; Krasieva, Tatiana B.; Pool, Roy; Andrews, Brian; Peavy, George M.

    2010-09-01

    An estimated 1.3 million people in the United States suffer from rheumatoid arthritis (RA). RA causes profound changes in the synovial membrane of joints, and without early diagnosis and intervention, progresses to permanent alterations in joint structure and function. The purpose of this study is to determine if nonlinear optical microscopy (NLOM) can utilize the natural intrinsic fluorescence properties of tissue to generate images that would allow visualization of the structural and cellular composition of fresh, unfixed normal and pathologic synovial tissue. NLOM is performed on rabbit knee joint synovial samples using 730- and 800-nm excitation wavelengths. Less than 30 mW of excitation power delivered with a 40×, 0.8-NA water immersion objective is sufficient for the visualization of synovial structures to a maximum depth of 70 μm without tissue damage. NLOM imaging of normal and pathologic synovial tissue reveals the cellular structure, synoviocytes, adipocytes, collagen, vascular structures, and differential characteristics of inflammatory infiltrates without requiring tissue processing or staining. Further study to evaluate the ability of NLOM to assess the characteristics of pathologic synovial tissue and its potential role for the management of disease is warranted.

  20. Integrating Actionable User-defined Faceted Rules into the Hybrid Science Data System for Advanced Rapid Imaging & Analysis

    Science.gov (United States)

    Manipon, G. J. M.; Hua, H.; Owen, S. E.; Sacco, G. F.; Agram, P. S.; Moore, A. W.; Yun, S. H.; Fielding, E. J.; Lundgren, P.; Rosen, P. A.; Webb, F.; Liu, Z.; Smith, A. T.; Wilson, B. D.; Simons, M.; Poland, M. P.; Cervelli, P. F.

    2014-12-01

    The Hybrid Science Data System (HySDS) scalably powers the ingestion, metadata extraction, cataloging, high-volume data processing, and publication of the geodetic data products for the Advanced Rapid Imaging & Analysis for Monitoring Hazard (ARIA-MH) project at JPL. HySDS uses a heterogeneous set of worker nodes from private & public clouds as well as virtual & bare-metal machines to perform every aspect of the traditional science data system. For our science data users, the forefront of HySDS is the facet search interface, FacetView, which allows them to browse, filter, and access the published products. Users are able to explore the collection of product metadata information and apply multiple filters to constrain the result set down to their particular interests. It allows them to download these faceted products for further analysis and generation of derived products. However, we have also employed a novel approach to faceting where it is also used to apply constraints for custom monitoring of products, system resources, and triggers for automated data processing. The power of the facet search interface is well documented across various domains and its usefulness is rooted in the current state of existence of metadata. However, user needs usually extend beyond what is currently present in the data system. A user interested in synthetic aperture radar (SAR) data over Kilauea will download them from FacetView but would also want email notification of future incoming scenes. The user may even want that data pushed to a remote workstation for automated processing. Better still, these future products could trigger HySDS to run the user's analysis on its array of worker nodes, on behalf of the user, and ingest the resulting derived products. We will present our findings in integrating an ancillary, user-defined, system-driven processing system for HySDS that allows users to define faceted rules based on facet constraints and triggers actions when new SAR data

  1. Opposing Actions of Chronic[Deta][superscript 9] Tetrahydrocannabinol and Cannabinoid Antagonists on Hippocampal Long-Term Potentiation

    Science.gov (United States)

    Hoffman, Alexander F.; Oz, Murat; Yang, Ruiqin; Lichtman, Aron H.; Lupica, Carl R.

    2007-01-01

    Memory deficits produced by marijuana arise partly via interaction of the psychoactive component, [Deta][superscript 9]-tetrahydrocannabinol ([Deta][superscript 9]-THC), with cannabinoid receptors in the hippocampus. Although cannabinoids acutely reduce glutamate release and block hippocampal long-term potentiation (LTP), a potential substrate for…

  2. Synthesis and evaluation of two novel 2-nitroimidazole derivatives as potential PET radioligands for tumor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zha Zhihao; Zhu Lin [Key Laboratory of Radiopharmaceuticals, Beijing Normal University, Ministry of Education, Beijing 100875 (China); Department of Radiology, University of Pennsylvania, Philadelphia, PA 19014 (United States); Liu Yajing; Du Fenghua; Gan Hongmei; Qiao Jinping [Key Laboratory of Radiopharmaceuticals, Beijing Normal University, Ministry of Education, Beijing 100875 (China); Kung, Hank F., E-mail: kunghf@gmail.co [Key Laboratory of Radiopharmaceuticals, Beijing Normal University, Ministry of Education, Beijing 100875 (China); Department of Radiology, University of Pennsylvania, Philadelphia, PA 19014 (United States)

    2011-05-15

    Introduction: Nitroimidazole (azomycin) derivatives labeled with radioisotopes have been developed as cancer imaging and radiotherapeutic agents based on the oncological hypoxic mechanism. By attaching nitroimidazole core with different functional groups, we synthesized new nitroimidazole derivatives and evaluated their potentiality as tumor imaging agents. Methods: Starting with commercially available 2-nitroimidazole, 2-fluoro-N-(2-(2-nitro-1H-imidazol-1-yl)ethyl)acetamide (NEFA, [{sup 19}F]7) and 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl 2-fluoroacetate (NEFT, [{sup 19}F]8), as well as radiolabeling precursors, the bromo-substituted analogs were quickly synthesized through a three-step synthetic pathway. The precursors were radiolabeled with [{sup 18}F]F{sup -}/18-crown-6/KHCO{sub 3} in dimethyl sulfoxide at 90{sup o}C for 10 min followed by purification with an Oasis HLB cartridge. Biodistribution studies were carried out in EMT-6 tumor-bearing mice. The uptake (%ID/g) in tumors and normal tissues were measured at 30 min postinjection. Liquid chromatography-electrospray ionization mass spectrometry (LC/MS) was used to distinguish metabolites from parent drugs in urine and plasma of rat injected with 'cold' NEFA ([{sup 19}F]7) and NEFT ([{sup 19}F]8). Results: Two radiotracers, [{sup 18}F]NEFA ([{sup 18}F]7) and [{sup 18}F]NEFT ([{sup 18}F]8), were prepared with average yields of 6%-7% and 9%-10% (not decay corrected). Radiochemical purity for both tracers was >95% as determined by HPLC. Biodistribution studies in EMT-6 tumor-bearing mice indicated that the tumor to blood and tumor to liver ratios of both [{sup 18}F]7 (0.96, 0.61) and [{sup 18}F]8 (0.98, 1.10) at 30 min were higher than those observed for [{sup 18}F]FMISO (1) (0.91, 0.59), a well-investigated azomycin-type hypoxia radiotracer. Liquid chromatography-electrospray ionization mass spectrometry analysis demonstrated that fluoroacetate was the main in vivo metabolite for both NEFA ([{sup 19

  3. Circadian rhythm of heart rate in the rabbit: prolongation of action potential duration by sustained beta adrenoceptor blockade is not due to associated bradycardia.

    Science.gov (United States)

    Vaughan Williams, E M; Dennis, P D; Garnham, C

    1986-07-01

    Six litters of six young rabbits were injected intraperitoneally, two per litter, with saline, alinidine, or nadolol once or twice daily for two weeks. In four litters successful radiotransmissions of electrocardiograms were recorded once hourly for four days before and during treatment. Alinidine and nadolol produced an overall mean bradycardia in comparison with saline treated animals, the effect of alinidine exceeding that of nadolol. At 48-70 hours after the end of treatment the hearts were used for in vitro electrophysiological study. Nadolol, but not alinidine, induced a prolongation of action potential duration compared with that of saline treated littermates in both atrial and ventricular muscle. An incidental observation was that heart rate in the rabbit followed a circadian rhythm, heart rates being slower in the morning and faster in late afternoon and evening. The circadian rhythm was attenuated but not abolished by alinidine and nadolol. These results suggest that if prolongation of action potential duration by sustained beta blockade in patients after myocardial infarction contributes to protection against sudden death (by a class III antiarrhythmic action) then alinidine would not be expected to provide a comparable prophylaxis.

  4. [Stimulation of gastric mucosa afferents by phenylephrine potentiates anticonvulsive and eliminates sedative action of sodium valproate in the pentylenetetrazol kindling model in rats].

    Science.gov (United States)

    Serdiuk, S E; Gmiro, V E; Veselkina, O S

    2014-01-01

    Sodium valproate after chronic intragastric administration in the high dose of 100-200 mg/kg eliminates generalized clonic-tonic pentylenetetrazol seizures in 100 % of rats, but only in 33-57 % of rats it prevents local clonic kindling seizures. Strong sedation is induced by the specified doses of sodium valproate. The combined oral chronic administration of phenylephrine in threshold, noneffective alone dose of 0.2 mg/kg and sodium valproate in high doses of 100 mg/kg and 200 mg/kg potentiates anticonvulsive action of sodium valproate, because prevents both clonic-tonic kindling. seizures in 100 % of rats and clonic kindling seizures in 86-100 % of rats, and also it increases in 1.7-1.9 times anticonvulsive activity of valproate. The specified combinations of sodium valproate with phenylephrine do not produce the sedative side effect. The basis of the mechanism of potentiation of anticonvulsive action and elimination of sedative action of sodium valproate in high doses is the stimulation of gastric mucosa afferents by phenylephrine.

  5. Work functions, ionization potentials, and in-between Scaling relations based on the image charge model

    CERN Document Server

    Wong, K; Kresin, V V

    2003-01-01

    We revisit a model in which the ionization energy of a metal particle is associated with the work done by the image charge force in moving the electron from infinity to a small cut-off distance just outside the surface. We show that this model can be compactly, and productively, employed to study the size dependence of electron removal energies over the range encompassing bulk surfaces, finite clusters, and individual atoms. It accounts in a straightforward manner for the empirically known correlation between the atomic ionization potential (IP) and the metal work function (WF), IP/WF$\\sim$2. We formulate simple expressions for the model parameters, requiring only a single property (the atomic polarizability or the nearest neighbor distance) as input. Without any additional adjustable parameters, the model yields both the IP and the WF within $\\sim$10% for all metallic elements, as well as matches the size evolution of the ionization potentials of finite metal clusters for a large fraction of the experimental...

  6. Simultaneous functional near-infrared brain imaging and event-related potential studies of Stroop effect

    Science.gov (United States)

    Zhai, Jiahuan; Li, Ting; Zhang, Zhongxing; Gong, Hui

    2009-02-01

    Functional near-infrared brain imaging (fNIRI) and event-related potential (ERP) were used simultaneous to detect the prefrontal cortex (PFC) which is considered to execute cognitive control of the subjects while performing the Chinese characters color-word matching Stroop task with event-related design. The fNIRI instrument is a portable system operating at three wavelengths (735nm & 805nm &850nm) with continuous-wave. The event-related potentials were acquired by Neuroscan system. The locations of optodes corresponding to the electrodes were defined four areas symmetrically. In nine native Chinese-speaking fit volunteers, fNIRI measured the hemodynamic parameters (involving oxy-/deoxy- hemoglobin) changes when the characteristic waveforms (N500/P600) were recorded by ERP. The interference effect was obvious as a longer reaction time for incongruent than congruent and neutral stimulus. The responses of hemodynamic and electrophysiology were also stronger during incongruent compared to congruent and neutral trials, and these results are similar to those obtained with fNIRI or ERP separately. There are high correlations, even linear relationship, in the two kinds of signals. In conclusion, the multi-modality approach combining of fNIRI and ERP is feasible and could obtain more cognitive function information with hemodynamic and electrophysiology signals. It also provides a perspective to prove the neurovascular coupling mechanism.

  7. Dopamine modulates Spike Timing-Dependent Plasticity and action potential properties in CA1 pyramidal neurons of acute rat hippocampal slices

    Directory of Open Access Journals (Sweden)

    Elke eEdelmann

    2011-11-01

    Full Text Available Spike Timing-Dependent Plasticity (STDP is a cellular model of hebbian synaptic plasticity which is believed to underlie memory formation. In an attempt to establish a STDP paradigm in CA1 of acute hippocampal slices from juvenile rats (P15-20, we found that changes in excitability resulting from different slice preparation protocols correlate with the success of STDP induction. Slice preparation with sucrose containing ACSF prolonged rise time, reduced frequency adaptation, and decreased latency of action potentials in CA1 pyramidal neurons compared to preparation in conventional ASCF, while other basal electrophysiological parameters remained unaffected. Whereas we observed prominent timing-dependent (t-LTP to 171 ± 10% of controls in conventional ACSF, STDP was absent in sucrose prepared slices. This sucrose-induced STDP deficit could not be rescued by stronger STDP paradigms, applying either more pre- and/or postsynaptic stimuli, or by a higher stimulation frequency. Importantly, slice preparation with sucrose containing ACSF did not eliminate theta-burst stimulation induced LTP in CA1 in field potential recordings in our rat hippocampal slices. Application of dopamine (for 10-20 min to sucrose prepared slices completely rescued t-LTP and recovered action potential properties back to levels observed in ACSF prepared slices. Conversely, acute inhibition of D1 receptor signaling impaired t-LTP in ACSF prepared slices. No similar restoring effect for STDP as seen with dopamine was observed in response to the β-adrenergic agonist isoproterenol. ELISA measurements demonstrated a significant reduction of endogenous dopamine levels (to 61.9 ± 6.9% of ACSF values in sucrose prepared slices. These results lead us to suggest that dopamine dependent regulation of action potential properties correlates with the efficiency to elicit STDP in CA1 pyramidal neurons.

  8. Potential effect and mechanism of action of topical chamomile (Matricaria chammomila L.) oil on migraine headache: A medical hypothesis.

    Science.gov (United States)

    Zargaran, Arman; Borhani-Haghighi, Afshin; Faridi, Pouya; Daneshamouz, Saeid; Kordafshari, Gholamreza; Mohagheghzadeh, Abdolali

    2014-11-01

    Migraine is a chronic recurring headache for which no complete treatment has been found yet. Therefore, finding new treatment approaches and medicines is important. In this review, we consider the probable mechanism of action of a traditional and ethnic formulary of chamomile extract in sesame oil as a new topical medication for migraine pain relief. Chamomile oil is prepared in Traditional Persian Medicine by boiling aqueous extract of chamomile in sesame oil. To optimize the procedure, we can use a Clevenger-type apparatus to extract the essential oil and add it to the end product. The preparation includes both essential oils (chamazulene and bisabolol oxide) and polyphenols (a flavonoid such as apigenin and its derivatives). It probably possesses pain relief effects for migraines because of the following properties: (1) chamazulene and apigenin, which inhibit iNOS expression in activated macrophages and can lead to the prohibition of NO release and synthesis; (2) chamomile flavonoids, which have a strong inhibitory effect on endogenous prostaglandin E2 (PGE2) levels in RAW 264.7 macrophages and can play the role of selective COX-2 inhibitor; (3) chamomile polyphenols, which possess anti-inflammatory effects due to the inhibition of pro-inflammatory biomarkers in THP1 macrophages and which can reduce inflammation in neurovascular units (NVU) at the site of migraine pain; (4) chamomile, which has neuroprotective effects because of reduced NO levels; (5) sesamine in sesame oil, which possesses an anti-inflammatory effect. These effects are supported by main pathophysiological theories of migraine such as neural and sensitization theories. Chamomile oil is a traditional formulation still used in Iran as an ethno-medicine. Because of the mentioned mechanisms of action, it can be hypothesized that chamomile oil is a novel medicine for the relief of migraine pain. PMID:25238714

  9. Donnan effect on chloride ion distribution as a determinant of body fluid composition that allows action potentials to spread via fast sodium channels

    Directory of Open Access Journals (Sweden)

    Kurbel Sven

    2011-05-01

    Full Text Available Abstract Proteins in any solution with a pH value that differs from their isoelectric point exert both an electric Donnan effect (DE and colloid osmotic pressure. While the former alters the distribution of ions, the latter forces water diffusion. In cells with highly Cl--permeable membranes, the resting potential is more dependent on the cytoplasmic pH value, which alters the Donnan effect of cell proteins, than on the current action of Na/K pumps. Any weak (positive or negative electric disturbances of their resting potential are quickly corrected by chloride shifts. In many excitable cells, the spreading of action potentials is mediated through fast, voltage-gated sodium channels. Tissue cells share similar concentrations of cytoplasmic proteins and almost the same exposure to the interstitial fluid (IF chloride concentration. The consequence is that similar intra- and extra-cellular chloride concentrations make these cells share the same Nernst value for Cl-. Further extrapolation indicates that cells with the same chloride Nernst value and high chloride permeability should have similar resting membrane potentials, more negative than -80 mV. Fast sodium channels require potassium levels >20 times higher inside the cell than around it, while the concentration of Cl- ions needs to be >20 times higher outside the cell. When osmotic forces, electroneutrality and other ions are all taken into account, the overall osmolarity needs to be near 280 to 300 mosm/L to reach the required resting potential in excitable cells. High plasma protein concentrations keep the IF chloride concentration stable, which is important in keeping the resting membrane potential similar in all chloride-permeable cells. Probable consequences of this concept for neuron excitability, erythrocyte membrane permeability and several features of circulation design are briefly discussed.

  10. Turning eating psychopathology risk factors into action: the pervasive effect of body image-related cognitive fusion

    OpenAIRE

    Ferreira, Cláudia; Palmeira, Lara; Trindade, Inês A.

    2014-01-01

    Body image dissatisfaction and unfavourable social comparisons are significant risk factors to eating psychopathology. Nevertheless, the impact of these negative experiences depends on the cognitive and emotional processes involved. Previous research has shown that cognitive fusion is a nuclear process linked to psychological inflexibility, but its role on body image and eating difficulties remains unclear. This study aims to explore a model of the mediational role of body image-related cogni...

  11. Soft-tissue inflammatory myofibroblastic tumors (IMTs) of the limbs: potential and limits of diagnostic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Masciocchi, Carlo; Lanni, Giuseppe; Conti, Laura; Conchiglia, Armando; Fascetti, Eva; Barile, Antonio [University of L' Aquila, S. Salvatore Hospital, Department of Radiology, Coppito, L' Aquila (Italy); Flamini, Stefano [S. Salvatore Hospital, Department of Orthopaedic Surgery, Coppito, L' Aquila (Italy); Coletti, Gino [S. Salvatore Hospital, Department of Pathology, Coppito, L' Aquila (Italy)

    2012-06-15

    The objective of this work was to evaluate the potential of diagnostic imaging in the identification, localization, and characterization of soft-tissue inflammatory myofibroblastic tumors (IMTs) of limbs with correlation to differential diagnosis and therapy. From a retrospective analysis of 324 histologically verified soft-tissue lesions of limbs and extremities diagnosed in our institute from January 2002 to July 2010, we selected seven cases of histologically proven IMT. These included six males and one female, aged between 28 and 81 years (mean age, 57 years). Lesions were localized in three cases to the thigh, in two cases to the popliteal space, and in the remaining two cases, to the shoulder girdle. All patients were evaluated on the basis of US, CT, and MRI. Ultrasound detected the presence of a non-homogeneous solid formation in all cases and calcifications in three cases. CT showed the presence and type of calcification/ossification and bone reaction. On MRI, all cases had low signal intensity on SE T1-weighted sequences and an intermediate-low signal intensity on SE and FSE T2-weighted sequences in six of them; only one case had an intermediate-high signal intensity on SE and FSE T2-weighted sequences. Both contrast-enhanced CT and MRI showed precocious enhancement in association with multiple peripheral hypertrophic blood vessels. On the basis of integrated imaging data obtained by US, CT, and MRI, it is possible to evaluate the lesion extension to provide a loco-regional staging, to characterize IMTs, and to allow an optimal therapeutical planning. (orig.)

  12. Tc-99m-galactosyl-neoglycoalbumin (Tc-NGA) liver imaging: Potential application in liver transplantation

    International Nuclear Information System (INIS)

    Tc-NGA is a hepatocyte receptor-specific imaging agent whose uptake by the liver has been shown to be dependent upon blood flow and receptor concentration. The combination of anatomic and physiologic information obtained with Tc-NGA may provide a new tool for studying hepatic function in liver transplant recipients. To evaluate the potential role of Tc-NGA in liver transplant recipients, studies were performed in four groups of pigs: controls (n=18); common bile duct (CBD) ligation (n=8); orthotopic liver transplant (n=9); and acute hepatic artery ligation (n=1). Serial studies performed in two animals with CBD ligation demonstrated normal imaging anatomy with minor changes in the hepatic time-activity curves when compared to control studies. Studies in liver-transplanted animals showed significant changes in the hepatic time-activity curves during acute rejection and in preservation-related ischemic injury. Tc-NGA also demonstrated focal areas of hepatic infarction in a hepatic allograft within 24 hours of transplantation. The hepatic artery ligation study showed massive changes in the hepatic time-activity curve within two hours after ligation, with a diffuse decrease in hepatic activity. These results indicate that: (1) extrahepatic biliary tract obstruction causes only minor changes in Tc-NGA uptake; (2) Tc-NGA uptake by the liver is very sensitive to acute hepatic ischemia; (3) Tc-NGA may indicate the presence of preservation damage in the early postoperative period; and (4) Tc-NGA hepatic time-activity curves demonstrate significant changes during acute rejection

  13. Imaging modes for potential mapping in semiconductor devices by electron holography with improved lateral resolution

    Energy Technology Data Exchange (ETDEWEB)

    Sickmann, Jan, E-mail: jan.sickmann@triebenberg.de [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany); Formanek, Petr; Linck, Martin [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany); Muehle, Uwe [Institut fuer Werkstoffwissenschaft, Technische Universitaet Bergakademie Freiberg, 09599 Freiberg (Germany); Lichte, Hannes [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany)

    2011-03-15

    Electron holography is the highest resolving tool for dopant profiling at nanometre-scale resolution. In order to measure the object areas of interest in a hologram, both a wide field of view and a sufficient lateral resolution are required. The usual path of rays for recording holograms with an electron biprism using the standard objective lens does not meet these requirements, because the field of view amounts to some 10 nm only, however, at a resolution of 0.1 nm better than needed here. Therefore, instead of the standard objective lens, the Lorentz lens is widely used for holography of semiconductors, since it provides a field of view up to 1000 nm at a sufficient lateral resolution of about 10 nm. Since the size of semiconductor structures is steadily shrinking, there is now a need for better lateral resolution at an appropriate field of view. Therefore, additional paths of rays for recording holograms are studied with special emphasis on the parameters field of view and lateral resolution. The findings allow an optimized scheme with a field of view of 200 nm and a lateral resolution of 3.3 nm filling the gap between the existing set-ups. In addition, the Lorentz lens is no longer required for investigation of non-magnetic materials, since the new paths of rays are realized with the standard objective lens and diffraction lens. An example proves the applicability of this arrangement for future semiconductor technology. -- Research highlights: {yields} Imaging modes for potential mapping in semiconductor devices by electron holography. {yields} Using objective and diffraction lens for imaging instead of Lorentz lens. {yields} Detailed investigation of four different paths of rays and its basic parameters for holographic application: field of view, lateral resolution, signal resolution. {yields} Measuring the phase profile of a field effect transistor with 3 nm lateral resolution at field of view of 200 nm.

  14. Green Tea Polyphenols Potentiate the Action of Nerve Growth Factor to Induce Neuritogenesis: Possible Role of Reactive Oxygen Species

    OpenAIRE

    Gundimeda, Usha; McNeill, Thomas H.; Schiffman, Jason E.; Hinton, David R.; Gopalakrishna, Rayudu

    2010-01-01

    Exogenously administered nerve growth factor (NGF) repairs injured axons, but it does not cross the blood-brain barrier. Thus, agents that could potentiate the neuritogenic ability of endogenous NGF would be of great utility in treating neurological injuries. Using the PC12 cell model, here we show that unfractionated green tea polyphenols (GTPP) at low concentrations (0.1 μg/ml) potentiate the ability of low concentrations of NGF (2 ng/ml) to induce neuritogenesis at a level comparable to th...

  15. Image processing of airborne geophysical data: a potential exploration tool for atomic minerals

    International Nuclear Information System (INIS)

    Data sets obtained from airborne gamma-ray spectrometric (AGRS) and aeromagnetic (AM) surveys, after necessary correction, are usually presented as profiles or as contour maps for interpretation in mineral exploration and geological analysis. Currently, imaging of the geophysical data sets have been extensively used as they have many advantages in their usage compared to conventional techniques. For the application of image processing techniques to the AGRS and AM data, software programs were customized for converting the digital data compatible to the satellite image processing system (SIPS). The geophysical data has been imaged and rectified to a poly conic projection, using cubic convolution resampling technique. While imaging, the radioelemental concentration values are rescaled to 256 grey levels. Software for the statistical information of radioelements and printing of coloured paper image have also been developed. Some of the image processing techniques used include, generation of colour composite images for preparing radioelemental (eU,eTh, and K) images and radioelemental colour composite images (K,eTh, eU) enabling display of a combined radioelemental distribution. Aeromagnetic data on the other hand are displayed in grey tone, pseudo-colours, and shaded relief images. Many other image enhancement techniques used for improving the display for further interpretation comprise, band ratioing, band combinations, filtering, look up table manipulation, and other similar functions. Advanced image processing techniques such as the principal component analysis (PCA) for understanding the geochemical and geological phenomena and the hue saturation and intensity (HSI) transformation for integration of radioelemental data with its corresponding satellite images facilitated display of radioelemental images draped over the satellite image. Statistics of radioelement and inter-elemental relationship has been obtained. The paper deals with the methodology adopted in the

  16. Monoclonal antibody RM2 as a potential ligand for a new immunotracer for prostate cancer imaging

    International Nuclear Information System (INIS)

    Objectives: To investigate the potential of monoclonal antibody (mAb) RM2 as a ligand for a radioimmunotracer for prostate cancer imaging. Methods: Labeling was conducted with mAb RM2 and 125I using the chloramine-T method. The cell study was conducted with PC-3 and LNCaP, which are prostate cancer cell lines, and MCF-7, which is a breast cancer cell line. The cells were treated or untreated with unlabeled mAb RM2 to block the haptoglobin-β chains expressed on the surface of the prostate cancer cells. 125I-mAb RM2 was added into the cell culture media and cellular uptake of 125I-mAb RM2 was evaluated at 1, 3 and 6 hours of incubation. For the in vivo biodistribution study, PC-3 cells were implanted in athymic male mice. The animals were injected intravenously with 125I-mAb RM2. At 24, 48 and 72 hours after tracer injection, the animals were sacrificed and the activity levels of blood and tissue samples were determined. Results: The uptake of 125I-mAb RM2 in the PC-3 and LNCaP cells increased according to the incubation time, while the uptake of 125I-mAb RM2 in MCF-7 cells did not show any increase up to 6 hours. The increase of 125I-RM2 uptake was not observed when the PC-3 and LNCaP cells were pre-treated with unlabeled RM2. In the biodistribution studies, 125I-mAb RM2 showed marked uptake into the implanted PC-3 cells. In PC-3 tumor-bearing mice, the tumor muscle ratio of 125I-RM2 was increased for up to 72 hours in a time-dependent manner. Conclusions: 125I-mAb RM2 showed excellent prostate cancer cell targeting in vitro and in vivo. Therefore, mAb RM2 seems to be a potential candidate for an immunoligand for prostate cancer imaging.

  17. Determination of thermodynamic potentials and the aggregation number for micelles with the mass-action model by isothermal titration calorimetry

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Westh, Peter; Holm, René

    2015-01-01

    The aggregation number (n), thermodynamic potentials (ΔG, ΔH, ΔS) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters...

  18. Design and application of measuring system of evoked compound action potential%诱发动作电位测量系统的设计与应用

    Institute of Scientific and Technical Information of China (English)

    孟丽; 李平; 訾蕊; 费兴波

    2015-01-01

    目的:为获得电信号刺激神经纤维时的动作电位,本文设计了一种电诱发复合动作电位测量系统,解决了诱发动作电位的精确采集问题,有效去除了本底噪声的影响。方法分析了范围在十几微伏的电诱发复合动作电位到几十毫伏电极电位测量时存在的难点,以及一个测量系统正常工作时需要满足的测量放大器共模容限和差模容限及电流源电压容限问题。基于此,本文提出采用3级运算放大器级联的方式实现诱发动作电位的采集。系统主要由3级级联放大器、自动零点调整环节和基准电压部分组成,实现对弱信号的放大、消除本底噪声和提供过压保护。结果采用本文设计的系统,测量得到11 mV 的蛙类坐骨神经干复合动作电位和17μV 的豚鼠耳蜗电诱发复合动作电位,验证了本系统可有效测量各种诱发电位。结论采用3级放大器级联的方式和自动零点跟踪方式解决了微弱信号的有效放大和精确采集技术,为进一步研究通过电信号直接刺激神经纤维所产生的动作电位的特性提供可靠的测量手段。%Objective When the nerve fiber is stimulated by the electrical pulse,there is an evoked compound action potential which indicates the synchronism property of the nerve fiber. In order to obtain the precise action potential,a measuring system of evoked compound action potential is presented in this paper. The system can collect the compound action potential precisely and eliminate the effect of ground noise. Methods Firstly,we analyzed the difficulty in the measurement of the compound action potential which ranged from μV level to the mV level. Secondly,we discussed the common-mode tolerance,differential mode tolerance and the voltage margin of the electric current which guaranteed the proper functioning of the measuring system. Based on the issues,we proposed a measuring system of compound action

  19. NS5806 partially restores action potential duration but fails to ameliorate calcium transient dysfunction in a computational model of canine heart failure

    DEFF Research Database (Denmark)

    Maleckar, Mary M; Lines, Glenn T; Koivumäki, Jussi T;

    2014-01-01

    AIMS: The study investigates how increased Ito, as mediated by the activator NS5806, affects excitation-contraction coupling in chronic heart failure (HF). We hypothesized that restoring spike-and-dome morphology of the action potential (AP) to a healthy phenotype would be insufficient to restore...... activation. CONCLUSIONS: Downstream effects of a compound acting exclusively on sarcolemmal ion channels are difficult to predict. Remediation of APD to pre-failing state does not ameliorate dysfunction in CaT; however, restoration of notch depth appears to impart modest benefit and a likelihood...

  20. X-ray phase sensitive imaging methods: basic physical principles and potential medical applications

    OpenAIRE

    Chen, Guang-Hong; Zambelli, Joseph; Bevins, Nicholas; Qi, Zhihua; Li, Ke

    2010-01-01

    Phase sensitive imaging theoretically allows for a drastic reduction in x-ray dose while simultaneously achieving comparable or better spatial and contrast resolution compared to traditional x-ray absorption based imaging. Several techniques exist to extract the phase information from an x-ray signal, including x-ray interferometry, diffraction enhanced imaging, in-line holography, coded aperture x-ray imaging, and grating-based interferometry. The physics of each method is reviewed, along wi...

  1. Myocardial first-pass perfusion imaging with hybrid-EPI: frequency-offsets and potential artefacts

    OpenAIRE

    Ferreira Pedro F; Gatehouse Peter D; Firmin David N

    2012-01-01

    Abstract Background First-pass myocardial perfusion is often imaged with a tailored hybrid centric interleaved echo-planar-imaging sequence, providing rapid image acquisition with good contrast enhancement. The centric interleaved phase-encode order minimises the effective time-of-echo but it is sensitive to frequency-offsets. This short article aims to show possible artefacts that might originate with this sequence, in the context of first-pass perfusion imaging, when frequency-offsets are p...

  2. Magnetic Resonance Imaging Interpretation in Patients with Sciatica Who Are Potential Candidates for Lumbar Disc Surgery

    NARCIS (Netherlands)

    A. el Barzouhi (Abdelilah); C.L.A.M. Vleggeert-Lankamp (Carmen); G.J. Lycklama à Nijeholt (Geert); B.F.W. van der Kallen (Bas); W.B. van den Hout (Wilbert); A.J.H. Verwoerd (Annemieke); B.W. Koes (Bart); W.C. Peul (Wilco)

    2013-01-01

    textabstractBackground:Magnetic Resonance Imaging (MRI) is considered the mainstay imaging investigation in patients suspected of lumbar disc herniations. Both imaging and clinical findings determine the final decision of surgery. The objective of this study was to assess MRI observer variation in p

  3. Magnetic Resonance Imaging Interpretation in Patients with Sciatica Who Are Potential Candidates for Lumbar Disc Surgery

    NARCIS (Netherlands)

    el Barzouhi, Abdelilah; Vleggeert-Lankamp, Carmen L. A. M.; Nijeholt, Geert J. Lycklama A.; Van der Kallen, Bas F.; Van den Hout, Wilbert B.; Verwoerd, Annemieke J. H.; Koes, Bart W.; Peul, Wilco C.

    2013-01-01

    Background: Magnetic Resonance Imaging (MRI) is considered the mainstay imaging investigation in patients suspected of lumbar disc herniations. Both imaging and clinical findings determine the final decision of surgery. The objective of this study was to assess MRI observer variation in patients wit

  4. [11C]-Acetoacetate PET imaging: a potential early marker for cardiac heart failure

    International Nuclear Information System (INIS)

    The ketone body acetoacetate could be used as an alternate nutrient for the heart, and it also has the potential to improve cardiac function in an ischemic–reperfusion model or reduce the mitochondrial production of oxidative stress involved in cardiotoxicity. In this study, [11C]-acetoacetate was investigated as an early marker of intracellular damage in heart failure. Methods: A rat cardiotoxicity heart failure model was induced by doxorubicin, Dox(+). [14C]-Acetoacetate, a non-positron (β −) emitting radiotracer, was used to characterize the arterial blood input function and myocardial mitochondrial uptake. Afterward, [11C]-acetoacetate (β +) myocardial PET images were obtained for kinetic analysis and heart function assessment in control Dox(−) (n = 15) and treated Dox(+) (n = 6) rats. The uptake rate (K1) and myocardial clearance rate (k2or kmono) were extracted. Results: [14C]-Acetoacetate in the blood was increased in Dox(+), from 2 min post-injection until the last withdrawal point when the heart was harvested, as well as the uptake in the heart and myocardial mitochondria (unpaired t-test, p < 0.05). PET kinetic analysis of [11C]-acetoacetate showed that rate constants K1, k2 and kmono were decreased in Dox(+) (p < 0.05) combined with a reduction of 24% of the left ventricular ejection fraction (p < 0.001). Conclusion: Radioactive acetoacetate ex vivo analysis [14C], and in vivo kinetic [11C] studies provided evidence that [11C]-acetoacetate can assess heart failure Dox(+). Contrary to myocardial flow reserve (rest–stress protocol), [11C]-acetoacetate can be used to assess reduced kinetic rate constants without requirement of hyperemic stress response. The proposed [11C]-acetoacetate cardiac radiotracer in the investigation of heart disease is novel and paves the way to a potential role for [11C]-acetoacetate in cardiac pathophysiology

  5. Diffusion tensor imaging of the inferior colliculus and brainstem auditory-evoked potentials in preterm infants

    Energy Technology Data Exchange (ETDEWEB)

    Reiman, Milla; Lehtonen, Liisa; Lapinleimu, Helena [Turku University Central Hospital, Department of Paediatrics, Turku (Finland); Parkkola, Riitta [Turku University Central Hospital, Department of Radiology and Turku PET Centre, Turku (Finland); Johansson, Reijo [Turku University Central Hospital, Department of Otorhinolaryngology, Turku (Finland); Jaeaeskelaeinen, Satu K. [Turku University Central Hospital, Department of Clinical Neurophysiology, Turku (Finland); Kujari, Harry [Turku University Central Hospital, Department of Pathology, Turku (Finland); Haataja, Leena [Turku University Central Hospital, Department of Paediatric Neurology, Turku (Finland)

    2009-08-15

    Preterm and low-birth-weight infants have an increased risk of sensorineural hearing loss. Brainstem auditory-evoked potentials (BAEP) are an effective method to detect subtle deficits in impulse conduction in the auditory pathway. Abnormalities on diffusion tensor imaging (DTI) have been shown to be associated with perinatal white-matter injury and reduced fractional anisotropy (FA) has been reported in patients with sensorineural hearing loss. To evaluate the possibility of a correlation between BAEP and DTI of the inferior colliculus in preterm infants. DTI at term age and BAEP measurements were performed on all very-low-birth-weight or very preterm study infants (n=56). FA and apparent diffusion coefficient (ADC) of the inferior colliculus were measured from the DTI. Shorter BAEP wave I, III, and V latencies and I-III and I-V intervals and higher wave V amplitude correlated with higher FA of the inferior colliculus. The association between the DTI findings of the inferior colliculus and BAEP responses suggests that DTI can be used to assess the integrity of the auditory pathway in preterm infants. (orig.)

  6. Investigation of the potential causes of partial scan artifacts in dynamic CT myocardial perfusion imaging

    Science.gov (United States)

    Tao, Yinghua; Speidel, Michael; Szczykutowicz, Timothy; Chen, Guang-Hong

    2014-03-01

    In recent years, there have been several findings regarding CT number variations (partial scan artifact or PSA) across time in dynamic myocardial perfusion studies with short scan gated reconstruction. These variations are correlated with the view angle range corresponding to the short scan acquisition for a given cardiac phase, which can vary from one cardiac cycle to another due to the asynchrony between heart rate and gantry rotation speed. In this study, we investigate several potential causes of PSA, including noise, beam hardening and scatter, using numerical simulations. In addition, we investigate partial scan artifact in a single source 64-slice diagnostic CT scanner in vivo data sets, and report its effect on perfusion analysis. Results indicated that among all three factors investigated, scatter can cause obvious partial scan artifact in dynamic myocardial perfusion imaging. Further, scatter is a low frequency phenomenon and is not heavily dependent on the changing contrasts, as both the frequency method and the virtual scan method are effective in reducing partial scan artifact. However, PSA does not necessarily lead to different blood volume maps compared to the full scan, because these maps are usually generated with a curve fitting procedure.

  7. Imaging a multidimensional multichannel potential energy surface: Photodetachment of H-(NH3) and NH4-

    Science.gov (United States)

    Hu, Qichi; Song, Hongwei; Johnson, Christopher J.; Li, Jun; Guo, Hua; Continetti, Robert E.

    2016-06-01

    Probes of the Born-Oppenheimer potential energy surfaces governing polyatomic molecules often rely on spectroscopy for the bound regions or collision experiments in the continuum. A combined spectroscopic and half-collision approach to image nuclear dynamics in a multidimensional and multichannel system is reported here. The Rydberg radical NH4 and the double Rydberg anion NH4- represent a polyatomic system for benchmarking electronic structure and nine-dimensional quantum dynamics calculations. Photodetachment of the H-(NH3) ion-dipole complex and the NH4- DRA probes different regions on the neutral NH4 PES. Photoelectron energy and angular distributions at photon energies of 1.17, 1.60, and 2.33 eV compare well with quantum dynamics. Photoelectron-photofragment coincidence experiments indicate dissociation of the nascent NH4 Rydberg radical occurs to H + NH3 with a peak kinetic energy of 0.13 eV, showing the ground state of NH4 to be unstable, decaying by tunneling-induced dissociation on a time scale beyond the present scope of multidimensional quantum dynamics.

  8. Potential of 57Ni/57Co generator system for radiolabelling proteins for imaging

    International Nuclear Information System (INIS)

    Full text: There is increasing interest in the use of inert metal complexes for radiolabelling proteins. The present study involves an investigation into the use to the parent/daughter system 57Ni/57Co for PET and SPECT imaging. In order to assess the potential of the system for such applications it is important to examine whether the ligand chosen complexes with both 57Ni and 57Co. A selection of ligands with varying number of donor groups and open-chain and macrocyclic ligands were chosen; ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), 1,4,8,11 - tetraazocyclotetradecane-1 4,8,11-tetraacetic acid (TETA) and diaminohydroxyaryl - diethylenetriaminepentaacetic acid, (DAHA-EDTA). Complexation behaviour over a range of pH and temperatures was investigated. Results show that the ligands have strong complexation for 57Ni however once 57Ni decayed to 57Co evidence ol chemical instability was noted. The DAHA-EDTA ligand (developed in house) was observed to be the most stable under conditions studied. lt was selected for use in radiolabelling B72.3 antibody and preliminary radiolabelling conditions were established

  9. A preliminary investigation of the potential of phase contrast x-ray imaging in the field of homeland security

    Science.gov (United States)

    Olivo, A.; Chana, D.; Speller, R.

    2008-11-01

    A novel technique based on coded apertures which makes x-ray phase contrast imaging (XPCi) feasible with conventional sources has been recently developed at University College London. This technique is expected to enable for the first time real-world applications of XPCi in fields as diverse as medical, biological and scientific imaging, industrial inspections and security scans. This paper focuses on XPCi applications in homeland security. A simulation of coded-aperture XPCi, which was experimentally validated in a previous work, has been used to produce images of potential threat objects, and to quantitatively assess detail visibility improvements in terms of contrast and signal-to-noise ratio over conventional techniques based on absorption. Free-space propagation phase contrast images taken with synchrotron radiation (SR) are also presented. Although not directly related to the coded-aperture technique used in the simulation, these can be considered indicative of the image quality that would be made available through coded-aperture XPCi with conventional sources: previous studies have demonstrated that this technique provides image enhancements compatible with those obtained with free-space propagation phase contrast with SR. Substantial enhancements in image quality and improvement in detail detectability in cluttered environments are demonstrated in this way. The results presented in this study and the software used to generate them will provide the basis for the design and realization of a dedicated imaging prototype.

  10. Images

    Data.gov (United States)

    National Aeronautics and Space Administration — Images for the website main pages and all configurations. The upload and access points for the other images are: Website Template RSW images BSCW Images HIRENASD...

  11. How a Small Family Run Business Adopted Critical Reflection Action Learning Using Hand Drawn Images to Initiate Organisational Change

    Science.gov (United States)

    Shepherd, Gary

    2016-01-01

    In this account of practice I would like to share my experiences of facilitating a Critical Reflection Action Learning (CRAL) set with a small family run business, struggling to make change and expand their services due to the problems they encountered in separating their business lives from their family lives. The account I present here is based…

  12. [A new ECG electrode concept for the conduction of fetal heart action potentials without penetration of the skin].

    Science.gov (United States)

    Schmidt, S; Langner, K; Rothe, J; Saling, E

    1982-10-01

    Internal cardiotocography is an important method for reliable supervision of the fetus during labor. The main task is the prevention of fetal hypoxia. However, there is a considerable disadvantage as the electrodes used penetrate the fetal skin, creating a possible entry point for organisms. The concept we have developed forms a new way of decreasing the risk of infection during labor by conducting the fetal heart rate potentials without penetrating the skin. The electrode is fixed to the skin of the presenting part by tissue adhesive and electrical contact between the fetal skin and the wire of the electrode is established through using electrolyte fluid.

  13. Sustained Exocytosis after Action Potential-Like Stimulation at Low Frequencies in Mouse Chromaffin Cells Depends on a Dynamin-Dependent Fast Endocytotic Process

    Science.gov (United States)

    Moya-Díaz, José; Álvarez, Yanina D.; Montenegro, Mauricio; Bayonés, Lucas; Belingheri, Ana V.; González-Jamett, Arlek M.; Cárdenas, Ana M.; Marengo, Fernando D.

    2016-01-01

    Under basal conditions the action potential firing rate of adrenal chromaffin cells is lower than 0.5 Hz. The maintenance of the secretory response at such frequencies requires a continuous replenishment of releasable vesicles. However, the mechanism that allows such vesicle replenishment remains unclear. Here, using membrane capacitance measurements on mouse chromaffin cells, we studied the mechanism of replenishment of a group of vesicles released by a single action potential-like stimulus (APls). The exocytosis triggered by APls (ETAP) represents a fraction (40%) of the immediately releasable pool, a group of vesicles highly coupled to voltage dependent calcium channels. ETAP was replenished with a time constant of 0.73 ± 0.11 s, fast enough to maintain synchronous exocytosis at 0.2–0.5 Hz stimulation. Regarding the mechanism involved in rapid ETAP replenishment, we found that it depends on the ready releasable pool; indeed depletion of this vesicle pool significantly delays ETAP replenishment. On the other hand, ETAP replenishment also correlates with a dynamin-dependent fast endocytosis process (τ = 0.53 ± 0.01 s). In this regard, disruption of dynamin function markedly inhibits the fast endocytosis and delays ETAP replenishment, but also significantly decreases the synchronous exocytosis during repetitive APls stimulation at low frequencies (0.2 and 0.5 Hz). Considering these findings, we propose a model in where both the transfer of vesicles from ready releasable pool and fast endocytosis allow rapid ETAP replenishment during low stimulation frequencies. PMID:27507935

  14. A combined method to estimate parameters of the thalamocortical model from a heavily noise-corrupted time series of action potential

    Science.gov (United States)

    Wang, Ruofan; Wang, Jiang; Deng, Bin; Liu, Chen; Wei, Xile; Tsang, K. M.; Chan, W. L.

    2014-03-01

    A combined method composing of the unscented Kalman filter (UKF) and the synchronization-based method is proposed for estimating electrophysiological variables and parameters of a thalamocortical (TC) neuron model, which is commonly used for studying Parkinson's disease for its relay role of connecting the basal ganglia and the cortex. In this work, we take into account the condition when only the time series of action potential with heavy noise are available. Numerical results demonstrate that not only this method can estimate model parameters from the extracted time series of action potential successfully but also the effect of its estimation is much better than the only use of the UKF or synchronization-based method, with a higher accuracy and a better robustness against noise, especially under the severe noise conditions. Considering the rather important role of TC neuron in the normal and pathological brain functions, the exploration of the method to estimate the critical parameters could have important implications for the study of its nonlinear dynamics and further treatment of Parkinson's disease.

  15. SUSTAINED EXOCYTOSIS AFTER ACTION POTENTIAL-LIKE STIMULATION AT LOW FREQUENCIES IN MOUSE CHROMAFFIN CELLS DEPENDS ON A DYNAMIN-DEPENDENT FAST ENDOCYTOTIC PROCESS

    Directory of Open Access Journals (Sweden)

    José Moya-Díaz

    2016-07-01

    Full Text Available Under basal conditions the action potential firing rate of adrenal chromaffin cells is lower than 0.5 Hz. The maintenance of the secretory response at such frequencies requires a continuous replenishment of releasable vesicles. However, the mechanism that allows such vesicle replenishment remains unclear. Here, using membrane capacitance measurements on mouse chromaffin cells, we studied the mechanism of replenishment of a group of vesicles released by a single action potential-like stimulus (APls. The exocytosis triggered by APls (ETAP represents a fraction (40% of the immediately releasable pool, a group of vesicles highly coupled to voltage dependent calcium channels. ETAP was replenished with a time constant of 0.73 +/- 0.11 s, fast enough to maintain synchronous exocytosis at 0.2-0.5 Hz stimulation. Regarding the mechanism involved in rapid ETAP replenishment, we found that it depends on the ready releasable pool; indeed depletion of this vesicle pool significantly delays ETAP replenishment. On the other hand, ETAP replenishment also correlates with a dynamin-dependent fast endocytosis process (τ=0.53±0.01 s. In this regard, disruption of dynamin function markedly inhibits the fast endocytosis and delays ETAP replenishment, but also significantly decreases the synchronous exocytosis during repetitive APls stimulation at low frequencies (0.2 and 0.5 Hz. Considering these findings, we propose a model in where both the transfer of vesicles from ready releasable pool and fast endocytosis allow rapid ETAP replenishment during low stimulation frequencies.

  16. A combined method to estimate parameters of the thalamocortical model from a heavily noise-corrupted time series of action potential

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruofan; Wang, Jiang; Deng, Bin, E-mail: dengbin@tju.edu.cn; Liu, Chen; Wei, Xile [Department of Electrical and Automation Engineering, Tianjin University, Tianjin (China); Tsang, K. M.; Chan, W. L. [Department of Electrical Engineering, The Hong Kong Polytechnic University, Kowloon (Hong Kong)

    2014-03-15

    A combined method composing of the unscented Kalman filter (UKF) and the synchronization-based method is proposed for estimating electrophysiological variables and parameters of a thalamocortical (TC) neuron model, which is commonly used for studying Parkinson's disease for its relay role of connecting the basal ganglia and the cortex. In this work, we take into account the condition when only the time series of action potential with heavy noise are available. Numerical results demonstrate that not only this method can estimate model parameters from the extracted time series of action potential successfully but also the effect of its estimation is much better than the only use of the UKF or synchronization-based method, with a higher accuracy and a better robustness against noise, especially under the severe noise conditions. Considering the rather important role of TC neuron in the normal and pathological brain functions, the exploration of the method to estimate the critical parameters could have important implications for the study of its nonlinear dynamics and further treatment of Parkinson's disease.

  17. Effect of Diabetes on Brain Structure: The Action to Control Cardiovascular Risk in Diabetes MR Imaging Baseline Data

    OpenAIRE

    Bryan, R. Nick; Bilello, Michel; Davatzikos, Christos; Lazar, Ronald M.; Murray, Anne; Horowitz, Karen; Lovato, James; Miller, Michael E.; Williamson, Jeff; Launer, Lenore J

    2014-01-01

    The results of this study show that measures of longer duration of diabetes or biochemical severity correlated primarily with brain atrophy, but not with white matter lesion volume, which is the major MR imaging marker of small vessel ischemic disease.

  18. Conjugation of cholesterol to HIV-1 fusion inhibitor C34 increases peptide-membrane interactions potentiating its action.

    Directory of Open Access Journals (Sweden)

    Axel Hollmann

    Full Text Available Recently, the covalent binding of a cholesterol moiety to a classical HIV-1 fusion inhibitor peptide, C34, was shown to potentiate its antiviral activity. Our purpose was to evaluate the interaction of cholesterol-conjugated and native C34 with membrane model systems and human blood cells to understand the effects of this derivatization. Lipid vesicles and monolayers with defined compositions were used as model membranes. C34-cholesterol partitions more to fluid phase membranes that mimic biological membranes. Importantly, there is a preference of the conjugate for liquid ordered membranes, rich in cholesterol and/or sphingomyelin, as observed both from partition and surface pressure studies. In human erythrocytes and peripheral blood mononuclear cells (PBMC, C34-cholesterol significantly decreases the membrane dipole potential. In PBMC, the conjugate was 14- and 115-fold more membranotropic than T-1249 and enfuvirtide, respectively. C34 or cholesterol alone did not show significant membrane activity. The enhanced interaction of C34-cholesterol with biological membranes correlates with its higher antiviral potency. Higher partitions for lipid-raft like compositions direct the drug to the receptor-rich domains where membrane fusion is likely to occur. This intermediary membrane binding step may facilitate the drug delivery to gp41 in its pre-fusion state.

  19. Identification of sodium channel isoforms that mediate action potential firing in lamina I/II spinal cord neurons

    Directory of Open Access Journals (Sweden)

    Smith Paula L

    2011-09-01

    Full Text Available Abstract Background Voltage-gated sodium channels play key roles in acute and chronic pain processing. The molecular, biophysical, and pharmacological properties of sodium channel currents have been extensively studied for peripheral nociceptors while the properties of sodium channel currents in dorsal horn spinal cord neurons remain incompletely understood. Thus far, investigations into the roles of sodium channel function in nociceptive signaling have primarily focused on recombinant channels or peripheral nociceptors. Here, we utilize recordings from lamina I/II neurons withdrawn from the surface of spinal cord slices to systematically determine the functional properties of sodium channels expressed within the superficial dorsal horn. Results Sodium channel currents within lamina I/II neurons exhibited relatively hyperpolarized voltage-dependent properties and fast kinetics of both inactivation and recovery from inactivation, enabling small changes in neuronal membrane potentials to have large effects on intrinsic excitability. By combining biophysical and pharmacological channel properties with quantitative real-time PCR results, we demonstrate that functional sodium channel currents within lamina I/II neurons are predominantly composed of the NaV1.2 and NaV1.3 isoforms. Conclusions Overall, lamina I/II neurons express a unique combination of functional sodium channels that are highly divergent from the sodium channel isoforms found within peripheral nociceptors, creating potentially complementary or distinct ion channel targets for future pain therapeutics.

  20. CT for evaluation of potential renal donors – How does iterative reconstruction influence image quality and dose?

    International Nuclear Information System (INIS)

    Purpose: To assess ASIR (adaptive statistical iterative reconstruction) technique regarding dose reduction and its impact on image quality in evaluation CTs of potential kidney donors. Materials and methods: Between May and November 2013, a prospective study of 53 assumingly healthy potential kidney donors was conducted. The subjects underwent abdominal evaluation CT prior to the planned explantation of a kidney and were randomly divided into 2 groups: Group A was examined with an ASIR 40 protocol (n = 26), group B (n = 27) was examined using a standard FBP (filtered back projection) protocol. Image quality was assessed both quantitatively (by obtaining attenuation values in different organ regions and calculating SNR and CNRs) and qualitatively (by two observers who evaluated image quality using a 5-point scale system). Applied dose was analyzed as CTDIvol (mGy), total DLP (mGy × cm) and effective dose (mSv). Results: Applied dose in group A was about 26% lower than in group B (p < 0.05). Between both groups, dose determining parameters such as scan length and patients’ body diameter showed no significant difference. SNR (signal-to-noise ratio) was significantly higher in group A (p < 0.05). CNRs (contrast-to-noise ratios) for different tissues were not significantly different. Observer rated image quality showed no significant difference. Conclusion: ASIR can contribute to a relevant dose reduction without any loss of image quality in CT scans for evaluating potential kidney donors

  1. Healthy universities--time for action: a qualitative research study exploring the potential for a national programme.

    Science.gov (United States)

    Dooris, Mark; Doherty, Sharon

    2010-03-01

    Despite the absence of national or international steers, there is within England growing interest in the Healthy University approach. This article introduces Healthy Universities; reports on a qualitative study exploring the potential for a national programme contributing to health, well-being and sustainable development; and concludes with reflections and recommendations. The study used questionnaires and interviews with key informants from English higher education institutions and national stakeholder organizations. The findings confirmed that higher education offers significant potential to impact positively on the health and well-being of students, staff and wider communities through education, research, knowledge exchange and institutional practice. There was strong support for extending the healthy settings approach beyond schools and further education, through a National Healthy Higher Education Programme that provides a whole system Healthy University Framework. Informants argued that although there are important public health drivers, it will also be necessary to show how a Healthy Universities can help achieve core business objectives and contribute to related agendas such as sustainability. Two models were discussed: an accreditation scheme with externally assessed standardized achievement criteria; and a flexible and light-touch framework focusing on change-related processes and utilizing self-assessment. While highlighting the appeal of league tables, many informants feared that a top-down approach could backfire, generating resistance and resulting in minimal compliance. In contrast, the majority felt that a process-focused aspirational model would be more likely to win hearts and minds and facilitate system-level change. Key recommendations relate to national programme development, research and evaluation and international collaboration and networking. PMID:20167825

  2. Magnetic resonance imaging of the shoulder: a review of potential sources of diagnostic errors

    International Nuclear Information System (INIS)

    Shoulder magnetic resonance (MR) imaging and MR arthrography are frequently utilized in the evaluation of shoulder pain and instability. The clinical scenario and imaging findings may be confusing to clinicians and radiologists and may present diagnostic challenges for those involved in evaluating and treating shoulder pathology. Often rotator cuff and labral abnormalities may be coexistent, clinical manifestations of denervation syndromes may be confusing to clinicians, and normal anatomic variations, imaging pitfalls, and various artifacts may cause dilemmas for the radiologist. This article will review the most frequently encountered mimickers and pitfalls of MR imaging of the shoulder. (orig.)

  3. Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

    Energy Technology Data Exchange (ETDEWEB)

    Maniraj, M [UGC-DAE Confortium for Scientific Research; Rai, Abhishek [UGC-DAE Confortium for Scientific Research; Barman, S R [UGC-DAE Confortium for Scientific Research; Krajci, M [Slovak Academy of Sciences; Schlagel, Deborah L [Ames Laboratory; Lograsso, Thomas A [Ames Laboratory; Horn, K [Fritz-Haber-Institut der Max-Planck-Gesellschaft

    2014-09-01

    We study the unoccupied region of the electronic structure of the fivefold symmetric surface of an icosahedral (i) Al-Pd-Mn quasicrystal. A feature that exhibits parabolic dispersion with an effective mass of (1.15±0.1)me and tracks the change in the work function is assigned to an image potential resonance because our density functional calculation shows an absence of band gap in the respective energy region. We show that Sn grows pseudomorphically on i-Al-Pd-Mn as predicted by density functional theory calculations, and the energy of the image potential resonance tracks the change in the work function with Sn coverage. The image potential resonance appears much weaker in the spectrum from the related crystalline Al-Pd-Mn surface, demonstrating that its strength is related to the compatibility of the quasiperiodic wave functions in i-Al-Pd-Mn with the free-electron-like image potential states. Our investigation of the energy region immediately above EF provides unambiguous evidence for the presence of a pseudogap, in agreement with our density functional theory calculations.

  4. Practices of Visual Communication in a Primary School Classroom: Digital Image Collection as a Potential Semiotic Mode

    Science.gov (United States)

    Björkvall, Anders

    2014-01-01

    "One-to-one" computing projects in which learners work with individual laptops or tablets across subjects are rapidly increasing in number. One aspect of this is that as the laptops give access to the Internet; digital images and texts--potentially from all over the globe--move into the classroom in an unprecedented manner. The paper…

  5. The Zoning of Forest Fire Potential of Gulestan Province Forests Using Granular Computing and MODIS Images

    Directory of Open Access Journals (Sweden)

    A. Jalilzadeh Shadlouei

    2013-09-01

    Full Text Available There are many vegetation in Iran. This is because of extent of Iran and its width. One of these vegetation is forest vegetation most prevalent in Northern provinces named Guilan, Mazandaran, Gulestan, Ardebil as well as East Azerbaijan. These forests are always threatened by natural forest fires so much so that there have been reports of tens of fires in recent years. Forest fires are one of the major environmental as well as economic, social and security concerns in the world causing much damages. According to climatology, forest fires are one of the important factors in the formation and dispersion of vegetation. Also, regarding the environment, forest fires cause the emission of considerable amounts of greenhouse gases, smoke and dust into the atmosphere which in turn causes the earth temperature to rise up and are unhealthy to humans, animals and vegetation. In agriculture droughts are the usual side effects of these fires. The causes of forest fires could be categorized as either Human or Natural Causes. Naturally, it is impossible to completely contain forest fires; however, areas with high potentials of fire could be designated and analysed to decrease the risk of fires. The zoning of forest fire potential is a multi-criteria problem always accompanied by inherent uncertainty like other multi-criteria problems. So far, various methods and algorithm for zoning hazardous areas via Remote Sensing (RS and Geospatial Information System (GIS have been offered. This paper aims at zoning forest fire potential of Gulestan Province of Iran forests utilizing Remote Sensing, Geospatial Information System, meteorological data, MODIS images and granular computing method. Granular computing is part of granular mathematical and one way of solving multi-criteria problems such forest fire potential zoning supervised by one expert or some experts , and it offers rules for classification with the least inconsistencies. On the basis of the experts’ opinion

  6. Cardiac risk stratification with myocardial perfusion imaging in potential renal-pancreas transplant recipients

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, M.C.; Larcos, G.; Chapman, J. [Westmead Hospital, Westmead, Sydney, NSW (Australia). Departments of Nuclear Medicine and Ultrasound

    1998-06-01

    Full text: Combined renal/pancreas transplantation is used in patients with severe type-1 diabetes and renal failure. Many patients have asymptomatic coronary artery disease (CAD). Thus, myocardial perfusion imaging (MPI) is widely used for preoperative risk assessment, however, its value has recently been challenged. The purpose of this study was to determine the predictive value of MPI compared to coronary angiography and/or thirty day perioperative cardiac events (cardiac death, myocardial infarction and unstable angina). We reviewed the MPI in 132 patients that were referred for possible renal pancreas transplantation during the period between 1987 - June 1997. Fifty five patients were excluded because of: still awaiting transplantation (n=19) ongoing medical assessment (n=21), received kidney only transplant (n=6) or other factors (n=9). Thus, 77 patients form the basis of this report. Seventy one patients were transplanted, 5 had coronary angiography and one died before transplantation but with coronary anatomy defined at autopsy. All patients (39 male, 38 female; mean age 37 years) had Tl-201 or Tc-99m MIBI SPECT at Westmead (n=54) or elsewhere (n=23). Patients underwent MPI, a mean of 12.1 months before transplantation and a mean of 6 months before coronary angiography or autopsy. MPI was normal in 64 (83%) and abnormal in 13 (17%) patients. Of the abnormal MPI, 7 patients had CAD and one had unstable angina post-operatively (PPV = 8/13; 61%). One patient had a fixed defect post CABG but proceeded to transplant with-out event; the other 4 patients had normal coronary anatomy. Of the normal MPIs there were no transplant related cardiac events, but one patient required CABG >12 months post MPI and a further patient died >12 months post transplant and was shown to have CAD at autopsy (NPV=62/64;97%). In conclusion we have found an excellent NPV and an acceptable PPV for MPI in potential renal pancreas graft recipients

  7. Gabor-like Image Filtering using a Neural Microcircuit

    OpenAIRE

    C. Mayr; A. Heittmann; Schüffny, R.

    2014-01-01

    In this letter, we present an implementation of a neural microcircuit for image processing employing Hebbian-adaptive learning. The neuronal circuit utilizes only excitatory synapses to correlate action potentials, extracting the uncorrelated ones, which contain significant image information. This circuit is capable of approximating Gabor-like image filtering and other image processing functions

  8. The angiogenic effect of dracorhodin perchlorate on human umbilical vein endothelial cells and its potential mechanism of action.

    Science.gov (United States)

    Li, Feng; Jiang, Tao; Liu, Wei; Hu, Quan; Yin, Huinan

    2016-08-01

    Hyperglycemia is the key clinical feature of diabetes, and may induce refractory wound lesions and impaired angiogenesis. Dracorhodin perchlorate (Dra) is the major ingredient of dragon's blood and it has been used as a medicine to treat chronic wounds, such as diabetic foot, since ancient times in many cultures. The current study aimed to investigate the effect of Dra on human umbilical vein endothelial cells (HUVECs) under high‑glucose (HG) stimulation and its potential mechanism. Dra was observed to increase the multiplication capacity of HUVECs both under low glucose (LG) and HG concentrations. Additionally, migration and tube formation in HUVECs was facilitated by Dra. The expression levels of Ras, mitogen‑activated protein kinase (MAPK) and vascular endothelial growth factor, which are key components of the Ras/MAPK pathway, were upregulated following Dra treatment. The present study is the first report, to the best of our knowledge, of the effects of Dra on wound healing, and the association with the Ras/MAPK signaling pathway. PMID:27357516

  9. Recent actions taken on methyl bromide under the Montreal Protocol: Their potential economic implications on international trade

    International Nuclear Information System (INIS)

    Methyl bromide (MB) produced and used by man is a versatile, highly effective, fastacting fumigant employed in a number of important ways to kill organisms destructive to plants. A wide spectrum of commodities is treated with MB. The compound is unique in that it provides a wide range of pest control, may be applied to a broad spectrum of both food and non-food commodities, can be used for fumigation of large and small quantities of materials, and, when applied properly, leaves no residues of toxicological significance. Recently, this compound has come under scientific scrutiny and has been identified as a potentially potent ozone depleting chemical. As a result, countries operating under the Montreal Protocol will be restricting its use, and, in some cases, eliminating its use altogether. To date there are no alternative chemical fumigants to replace methyl bromide. Non-chemical treatments such as irradiation, hot and cold treatments, modified atmosphere, etc., are the most promising. The paper focuses on the magnitude of the economic consequences on international trade and the necessity to have available alternative treatments that are highly effective, fast-acting, and practical. 8 refs, 12 tabs

  10. Synthesis and Bioconjugation of Gold Nanoparticles as Potential Molecular Probes for Light-Based Imaging Techniques

    NARCIS (Netherlands)

    Rayavarapu, Raja Gopal; Petersen, Wilma; Ungureanu, Constantin; Post, Janine N.; Leeuwen, van Ton G.; Manohar, Srirang

    2007-01-01

    We have synthesized and characterized gold nanoparticles (spheres and rods) with optical extinction bands within the “optical imaging window.” The intense plasmon resonant driven absorption and scattering peaks of these nanoparticles make them suitable as contrast agents for optical imaging techniqu

  11. Myocardial first-pass perfusion imaging with hybrid-EPI: frequency-offsets and potential artefacts

    Directory of Open Access Journals (Sweden)

    Ferreira Pedro F

    2012-06-01

    Full Text Available Abstract Background First-pass myocardial perfusion is often imaged with a tailored hybrid centric interleaved echo-planar-imaging sequence, providing rapid image acquisition with good contrast enhancement. The centric interleaved phase-encode order minimises the effective time-of-echo but it is sensitive to frequency-offsets. This short article aims to show possible artefacts that might originate with this sequence, in the context of first-pass perfusion imaging, when frequency-offsets are present. Non-uniform magnitude modulation effects were also analysed. Methods Numerical and phantom simulations were used to illustrate the effects of frequency-offsets and non-uniform magnitude modulation with this sequence in a typical perfusion protocol. In vivo data was post-processed to analyse the h-EPI’s sensitivity to the frequency-offsets. Results The centric phase-order was shown to be highly sensitive to frequency-offsets due to its symmetrical phase slope. Resulting artefacts include blurring, and splitting of the image into two identical copies along the phase-encode direction. It was also shown that frequency-offsets can introduce signal loss and ghosting of the right ventricle signal into the myocardium. The in vivo results were confirmed by numerical and phantom simulations. Magnitude modulation effects were found to be small. Conclusions Imaging first-pass myocardial perfusion with an hybrid centric echo-planar-imaging sequence can be corrupted with ghosting and splitting of the image due to frequency-offsets.

  12. Molecular mechanisms of action and potential biomarkers of growth inhibition of dasatinib (BMS-354825) on hepatocellular carcinoma cells

    International Nuclear Information System (INIS)

    Molecular targeted therapy has emerged as a promising treatment of Hepatocellular carcinoma (HCC). One potential target is the Src family Kinase (SFK). C-Src, a non-receptor tyrosine kinase is a critical link of multiple signal pathways that regulate proliferation, invasion, survival, metastasis, and angiogenesis. In this study, we evaluated the effects of a novel SFK inhibitor, dasatinib (BMS-354825), on SFK/FAK/p130CAS, PI3K/PTEN/Akt/mTOR, Ras/Raf/MAPK and Stats pathways in 9 HCC cell lines. Growth inhibition was assessed by MTS assay. EGFR, Src and downstream proteins FAK, Akt, MAPK42/44, Stat3 expressions were measured by western blot. Cell adhesion, migration and invasion were performed with and without dasatinib treatment. The IC50 of 9 cell lines ranged from 0.7 μM ~ 14.2 μM. In general the growth inhibition by dasatinib was related to total Src (t-Src) and the ratio of activated Src (p-Src) to t-Src. There was good correlation of the sensitivity to dasatinib and the inhibition level of p-Src, p-FAK576/577 and p-Akt. No inhibition was found on Stat3 and MAPK42/44 in all cell lines. The inhibition of cell adhesion, migration and invasion were correlated with p-FAK inhibition. Dasatinib inhibits the proliferation, adhesion, migration and invasion of HCC cells in vitro via inhibiting of Src tyrosine kinase and affecting SFK/FAK and PI3K/PTEN/Akt, but not Ras/Raf/MEK/ERK and JAK/Stat pathways. T-Src and p-Src/t-Src may be useful biomarkers to select HCC patients for dasatinib treatment

  13. Addictive evaluation of cholic acid-verticinone ester, a potential cough therapeutic agent with agonist action of opioid receptor

    Institute of Scientific and Technical Information of China (English)

    Jiu-liang ZHANG; Hui WANG; Chang CHEN; Hui-fang PI; Han-li RUAN; Peng ZHANG; Ji-zhou WU

    2009-01-01

    Aim: The purpose of this work was to search for potential drugs with potent antitussive and expectorant activities as well as a low toxicity, but without addictive properties. Cholic acid-verticinone ester (CA-Ver) was synthesized based on the clearly elucidated antitussive and expectorant activities of verticinone in bulbs of Fritillaria and different bile acids in Snake Bile. In our previous study, CA-Vet showed a much more potent activity than codeine phosphate. This study was carried out to investigate the central antitussive mechanism and the addictive evaluation of CA-Ver.Methods: Testing on a capsaicin-induced cough model of mice pretreated with naloxone, a non-selective opioid receptor antagonist, was performed for the observation of CA-Ver's central antitussive mechanism. We then took naloxone-induced withdrawal tests of mice for the judgment of CA-Ver's addiction. Lastly, we determined the opioid dependence of CA-Ver in the guinea pig ileum. Results: The test on the capsaicin-induced cough model showed that naloxone could block the antitussive effect of CA-Ver,suggesting the antitussive mechanism of CA-Ver was related to the central opioid receptors. The naloxone-urged withdrawal tests of the mice showed that CA-Ver was not addictive, and the test of the opioid dependence in the guinea pig ileum showed that CA-Ver had no withdrawal response.Conclusion: These findings suggested that CA-Ver deserved attention for its potent antitussive effects related to the central opioid receptors, but without addiction, and had a good development perspective.

  14. Investigation of the potential use of hyperspectral imaging for stand-off detection of person-borne IEDs

    Science.gov (United States)

    Cooksey, Catherine; Allen, David

    2011-06-01

    Advances in hyperspectral sensors and algorithms may benefit the detection of person-borne improvised explosive devices (PB-IEDs). While portions of the electromagnetic spectrum, such as the x-ray and terahertz regions, have been investigated for this application, the spectral region of the ultraviolet (UV) through shortwave infrared (SWIR) (250 nm to 2500 nm) has received little attention. The purpose of this work was to investigate what, if any, potential there may be for exploiting the spectral region of the UV through SWIR for the detection of hidden objects under the clothing of individuals. The optical properties of both common fabrics and materials potentially used to contain threat objects were measured, and a simple example using a hyperspectral imager is provided to illustrate the combined effect. The approach, measurement methods, and results are described in this paper, and the potential for hyperspectral imaging is addressed.

  15. Quantitative imaging of the electrostatic field and potential generated by a transmembrane protein pore at subnanometer resolution.

    Science.gov (United States)

    Pfreundschuh, Moritz; Hensen, Ulf; Müller, Daniel J

    2013-01-01

    Elucidating the mechanisms by which proteins translocate small molecules and ions through transmembrane pores and channels is of great interest in biology, medicine, and nanotechnology. However, the characterization of pore forming proteins in their native state lacks suitable methods that are capable of high-resolution imaging (~1 nm) while simultaneously mapping physical and chemical properties. Here we report how force-distance (FD) curve-based atomic force microscopy (AFM) imaging can be applied to image the native pore forming outer membrane protein F (OmpF) at subnanometer resolution and to quantify the electrostatic field and potential generated by the transmembrane pore. We further observe the electrostatic field and potential of the OmpF pore switching "on" and "off" in dependence of the electrolyte concentration. Because electrostatic field and potential select for charged molecules and ions and guide them to the transmembrane pore the insights are of fundamental importance to understand the pore function. These experimental results establish FD-based AFM as a unique tool to image biological systems to subnanometer resolution and to quantify their electrostatic properties. PMID:24079830

  16. Remote Monitoring of the Heart Condition of Athletes by Measuring the Cardiac Action Potential Propagation Time Using a Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Amang Sudarsono

    2016-04-01

    Full Text Available Highly performing athletes are susceptible to cardiac damage of several kinds which may be irreversible. The monitoring of heart rate and ECG waveforms from such subjects by wireless sensor networks has been reported in health and sports care documents. However, a more decisive parameter for instant to instant changes would be the time of Cardiac Action Potential Propagation. This time, which can be between 15-20 ms would shoot suddenly in acute stress in highly performing athletes for short durations. Repeated incidents of such rising values will tend to cause irreversible damage to the heart. We developed the technique of measuring this time and reporting it through a wireless sensor network to monitoring station.

  17. Biophysical characterization of inwardly rectifying potassium currents (I(K1) I(K,ACh), I(K,Ca)) using sinus rhythm or atrial fibrillation action potential waveforms

    DEFF Research Database (Denmark)

    Tang, Chuyi; Skibsbye, Lasse; Yuan, Lei;

    2015-01-01

    remain unclear. Both I(K1) and I(K,ACh) are implicated in atrial fibrillation (AF), and recently also I(K,Ca) has been speculated to be linked with the genesis and sustainability of AF. All these three currents have been shown to be involved in the electrical remodeling in the atria of patients suffering...... to voltage protocols adapted from atrial action potentials recorded in human tissue at 1 and 3 Hz. The current recordings were performed in the HEK-293 heterologous cell system expressing either I(K1), I(K,ACh) or I(K,Ca) to establish the individual contribution of each of these currents during the voltage...

  18. Potential of hybrid {sup 18}F-fluorocholine PET/MRI for prostate cancer imaging

    Energy Technology Data Exchange (ETDEWEB)

    Perrot, Thomas de; Scheffler, Max; Vallee, Jean-Paul [Geneva University Hospitals and University of Geneva, Division of Radiology, Geneve 14 (Switzerland); Rager, Olivier; Ratib, Osman [Geneva University Hospitals, Division of Nuclear Medicine, Geneva (Switzerland); Lord, Martin [University of Montreal Hospital Center, Division of Nuclear Medicine, Montreal (Canada); Pusztaszeri, Marc [Geneva University Hospitals, Division of Clinical Pathology, Geneva (Switzerland); Iselin, Christophe [Geneva University Hospitals, Division of Urologic Surgery, Geneva (Switzerland)

    2014-09-15

    To report the first results of hybrid {sup 18}F-fluorocholine PET/MRI imaging for the detection of prostate cancer. This analysis included 26 consecutive patients scheduled for prostate PET/MRI before radical prostatectomy. The examinations were performed on a hybrid whole-body PET/MRI scanner. The MR acquisitions which included T2-weighted, diffusion-weighted and dynamic contrast-enhanced sequences were followed during the same session by whole-body PET scans. Parametric maps were constructed to measure normalized T2-weighted intensity (nT2), apparent diffusion coefficient (ADC), volume transfer constant (K {sup trans}), extravascular extracellular volume fraction (v{sub e}) and standardized uptake values (SUV). With pathology as the gold standard, ROC curves were calculated using logistic regression for each parameter and for the best combination with and without PET to obtain a MR model versus a PETMR model. Of the 26 patients initially selected, 3 were excluded due to absence of an endorectal coil (2 patients) or prosthesis artefacts (1 patient). In the whole prostate, the area under the curve (AUC) for SUV{sub max}, ADC, nT2, K {sup trans} and v{sub e} were 0.762, 0.756, 0.685, 0.611 and 0.529 with a best threshold at 3.044 for SUV{sub max} and 1.075 x 10{sup -3} mm{sup 2}/s for ADC. The anatomical distinction between the transition zone and the peripheral zone showed the potential of the adjunctive use of PET. In the peripheral zone, the AUC of 0.893 for the PETMR model was significantly greater (p = 0.0402) than the AUC of 0.84 for the MR model only. In the whole prostate, no relevant correlation was observed between ADC and SUV{sub max}. The SUV{sub max} was not affected by the Gleason score. The performance of a hybrid whole-body {sup 18}F-fluorocholine PET/MRI scan in the same session combined with a prostatic MR examination did not interfere with the diagnostic accuracy of the MR sequences. The registration of the PET data and the T2 anatomical MR

  19. The Public Image of Libraries and Librarians as a Potential Barrier to Rural Access.

    Science.gov (United States)

    MacDonald, Brad

    1995-01-01

    Examines stereotypes of the librarian as serious barriers to rural information access, and offers strategies for improving the public image of rural libraries and of the people who keep them functioning. (Author/JKP)

  20. Optical-based molecular imaging: contrast agents and potential medical applications

    International Nuclear Information System (INIS)

    Laser- and sensitive charge-coupled device technology together with advanced mathematical modelling of photon propagation in tissue has prompted the development of novel optical imaging technologies. Fast surface-weighted imaging modalities, such as fluorescence reflectance imaging (FRI) and 3D quantitative fluorescence-mediated tomography have now become available [1, 2]. These technical advances are paralleled by a rapid development of a whole range of new optical contrasting strategies, which are designed to generate molecular contrast within a living organism. The combination of both, technical advances of light detection and the refinement of optical contrast media, finally yields a new spectrum of tools for in vivo molecular diagnostics. Whereas the technical aspects of optical imaging are covered in more detail in a previous review article in ''European Radiology'' [3], this article focuses on new developments in optical contrasting strategies and design of optical contrast agents for in vivo diagnostics. (orig.)

  1. Menthol-induced action potentials in Conocephalum conicum as a result of unspecific interactions between menthol and the lipid phase of the plasma membrane.

    Science.gov (United States)

    Kupisz, Kamila; Trebacz, Kazimierz; Gruszecki, Wiesław I

    2015-07-01

    Our previous study has shown that the liverwort Conocephalum conicum generates action potentials (APs) in response to both temperature drop and menthol, which are also activators of the TRPM8 (transient receptor potential melastatin 8) receptor in animals. Not only similarities but also differences between electrical reactions to menthol and cooling observed in the liverwort aroused our interest in the action of menthol at the molecular level. Patch-clamp investigations have shown that menthol causes a reduction of current flowing through slow vacuolar (SV) channels to 29 ± 10% of the initial value (n = 9); simultaneously, it does not influence magnitudes of currents passing through a single SV channel. This may point to an unspecific interaction between menthol and the lipid phase of the membrane. An influence of menthol on lipid organization in membranes was investigated in two-component monomolecular layers formed with menthol and dipalmitoylphosphatidylcholine (DPPC) at the argon-water interface. Analyses of the mean molecular area parameters vs the molar fraction of the menthol component have shown over-additivity (approximately 20 Å(2) ) in the region of high molar fractions of menthol. Infrared absorption spectroscopy studies have shown that menthol, most probably, induces breaking of a hydrogen bond network formed by ester carbonyl groups and water bridges in the lipid membrane and binds to the polar head group region of DPPC. We conclude that the disruption in the lipid phase of the membrane influences ion channels and/or pumps and subsequently causes generation of APs in excitable plants such as C. conicum.

  2. ERK 1/2 and PI-3 kinase pathways as a potential mechanism of ghrelin action on cell proliferation and apoptosis in the porcine ovarian follicular cells.

    Science.gov (United States)

    Rak-Mardyla, A; Gregoraszczuk, E L

    2010-08-01

    Recently, we reported the stimulatory effect of ghrelin on ovarian cell proliferation in parallel with the inhibitory action of ghrelin on cell apoptosis. The aim of the presented data propose local activation of extracellular signal-regulated protein kinase 1 and 2 (ERK 1/2) and phosphoinositide-3 (PI-3) kinase pathways as a mechanism of ghrelin effect in the porcine ovary. To test this hypothesis, action of ghrelin on levels of ERK 1/2 with PI-3 kinase activity and protein expression using ELISA and western blot analysis, respectively, was examined. Additionally, to determine which pathways (ERK 1/2 or PI-3 kinase) are the potential signals of ghrelin-mediated cell proliferation and apoptosis in ovarian cells, we used PD098059 (50 microM) and wortmannin (200 microM), well-known inhibitors of these kinases. Treatment of ovarian coculture cells with ghrelin (100, 250, 500 and 1000 pg/ml) showed stimulation of phospho-ERK 1/2 levels and PI-3 kinase activity, with the maximum effect observed after 15 min of cell incubation. Additionally, western blot analysis indicated that ghrelin increased expression of both kinases. Moreover, ghrelin used in combination with PD098059 or wortmannin significantly decreased cell proliferation, which was measured by the Alamar Blue assay and increased apoptosis, which was measured by caspase - 3 activity and DNA fragmentation. In conclusion, these results suggest that the ERK 1/2 and PI-3 kinase pathways may be potential signals of ghrelin mediate the cell proliferation and apoptosis of ovary cells.

  3. The potential of pigeons as surrogate observers in medical image perception studies

    Science.gov (United States)

    Krupinski, Elizabeth A.; Levenson, Richard M.; Navarro, Victor; Wasserman, Edward A.

    2016-03-01

    Assessment of medical image quality and how changes in image appearance impact performance are critical but assessment can be expensive and time-consuming. Could an animal (pigeon) observer with well-known visual skills and documented ability to distinguish complex visual stimuli serve as a surrogate for the human observer? Using sets of whole slide pathology (WSI) and mammographic images we trained pigeons (cohorts of 4) to detect and/or classify lesions in medical images. Standard training methods were used. A chamber equipped with a 15' display with a resistive touchscreen was used to display the images and record responses (pecks). Pigeon pellets were dispensed for correct responses. The pigeons readily learned to distinguish benign from malignant breast cancer histopathology in WSI (mean % correct responses rose 50% to 85% over 15 days) and generalized readily from 4X to 10X and 20X magnifications; to detect microcalcifications (mean % correct responses rose 50% to over 85% over 25 days); to distinguish benign from malignant breast masses (3 of 4 birds learned this task to around 80% and 60% over 10 days); and ignore compression artifacts in WSI (performance with uncompressed slides averaged 95% correct; 15:1 and 27:1 compression slides averaged 92% and 90% correct). Pigeons models may help us better understand medical image perception and may be useful in quality assessment by serving as surrogate observers for certain types of studies.

  4. Clinical evaluation of the computed tomography attenuation correction map for myocardial perfusion imaging: the potential for incidental pathology detection.

    Science.gov (United States)

    Tootell, Andrew; Vinjamuri, Sobhan; Elias, Mark; Hogg, Peter

    2012-11-01

    The benefits of hybrid imaging in nuclear medicine have been proven to increase the diagnostic accuracy and sensitivity of many procedures by localizing or characterizing lesions or by correcting emission data to more accurately represent radiopharmaceutical distribution. Single-photon emission computed tomography/computed tomography (SPECT/CT) has a significant role in the diagnosis and follow-up of ischaemic heart disease with attenuation correction data being obtained on an integrated CT scanner. Initially, the CT component of hybrid SPECT/CT systems was what could be described as low specification utilizing fixed output parameters. As technology has progressed, the CT component of newer systems has specifications that are identical to that of stand-alone diagnostic systems. Irrespective of the type of scanner used, the computed tomography attenuation correction (CTAC) for myocardial perfusion imaging produces low-quality, limited-range CT images of the chest that include the mediastinum, lung fields and surrounding soft tissues. The diagnostic potential of this data set is unclear; yet, examples exist whereby significant pathology can be identified and investigated further. Despite guidance from a number of professional bodies suggesting that evaluation of the resulting images for every medical exposure be carried out, there is no indication as to whether this should include the evaluation of CTAC images. This review aims to initiate discussion by examining the ethical, legal, financial and practical issues (e.g. CT specification and image quality) surrounding the clinical evaluation of the CTAC for myocardial perfusion imaging images. Reference to discussions that have taken place, and continue to take place, in other modalities, current European and UK legislations, and guidelines and research in the field will be made.

  5. Action potential initial dynamical control and analysis of a minimum neuron model%最小神经元模型放电起始动态控制与分析

    Institute of Scientific and Technical Information of China (English)

    金淇涛; 王江; 魏熙乐; 邓斌; 车艳秋

    2011-01-01

    本文采用最小神经元模型,从生理学角度设计wash-out滤波器,实现了不同放电起始动态机理之间的转换,并证明wash-out滤波器控制通过影响阈下电流的竞争结果改变了神经元的放电起始动态机理.%Neuron is a basic unit of information transmission in the nervous system . Neuron encodes the information input from the dendrites by generating action potential sequences of different firing patterns. The different firing patterns result from different action potential initial dynamic mechanisms for neurons to generate spikes. The result of competition between neuron ion currents with different dynamic features in the sub threshold potential determines the action potential initial dynamic mechanism. In this paper, we adopt a minimum neuron model to design the wash-out filter from a physiological view for achieving the transition between different action potential initial dynamic mechanisms and for verifying that the wash-out filter control changes the action potential initial dynamic mechanism of neuron by affecting the result of competition between currents with different dynamic features in the sub-threshold potential.

  6. Potential Applications of Flat-Panel Volumetric CT in Morphologic, Functional Small Animal Imaging

    Directory of Open Access Journals (Sweden)

    Susanne Greschus

    2005-08-01

    Full Text Available Noninvasive radiologic imaging has recently gained considerable interest in basic, preclinical research for monitoring disease progression, therapeutic efficacy. In this report, we introduce flat-panel volumetric computed tomography (fpVCT as a powerful new tool for noninvasive imaging of different organ systems in preclinical research. The three-dimensional visualization that is achieved by isotropic high-resolution datasets is illustrated for the skeleton, chest, abdominal organs, brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model, the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, kidney down to the subsegmental level. Functional application of fpVCT in dynamic contrast-enhanced scans of the rat brain delivered physiologically reliable data of perfusion, tissue blood volume. Beyond scanning of small animal models as demonstrated here, fpVCT provides the ability to image animals up to the size of primates.

  7. Imaging of Small Animal Peripheral Artery Disease Models: Recent Advancements and Translational Potential

    Directory of Open Access Journals (Sweden)

    Jenny B. Lin

    2015-05-01

    Full Text Available Peripheral artery disease (PAD is a broad disorder encompassing multiple forms of arterial disease outside of the heart. As such, PAD development is a multifactorial process with a variety of manifestations. For example, aneurysms are pathological expansions of an artery that can lead to rupture, while ischemic atherosclerosis reduces blood flow, increasing the risk of claudication, poor wound healing, limb amputation, and stroke. Current PAD treatment is often ineffective or associated with serious risks, largely because these disorders are commonly undiagnosed or misdiagnosed. Active areas of research are focused on detecting and characterizing deleterious arterial changes at early stages using non-invasive imaging strategies, such as ultrasound, as well as emerging technologies like photoacoustic imaging. Earlier disease detection and characterization could improve interventional strategies, leading to better prognosis in PAD patients. While rodents are being used to investigate PAD pathophysiology, imaging of these animal models has been underutilized. This review focuses on structural and molecular information and disease progression revealed by recent imaging efforts of aortic, cerebral, and peripheral vascular disease models in mice, rats, and rabbits. Effective translation to humans involves better understanding of underlying PAD pathophysiology to develop novel therapeutics and apply non-invasive imaging techniques in the clinic.

  8. Results and potential of somatostatin in receptor imaging in gastroenteropancreatic tract tumours

    International Nuclear Information System (INIS)

    Somatostatin receptor imaging with 111Inpentetreotide is widely accepted as an essential step in the management of patients affected by neuroendocrine tumours of the gastro-entero-pancreatic tract. Many data are already available on the high sensitivity of this technique. In this work is presented a review of the published data together with the results of a study involving 253 patients submitted to somatostatin receptor imaging in three Italian hospitals. The patients were divided into two groups treated with different acquisition and processing protocols. The overall sensitivity was as high as (169/176) 96% in both groups, while the specificity was higher in the group in which semi-quantitative evaluation of somatostatin receptor density was performed: (23/26) 88% vs (39/51) 76%. The use of this method is recommended to increase the specificity of 111Inpentetreotide imaging. The results with somatostatin receptor imaging in neuroendocrine tumours of the gastro-entero-pancreatic tract demonstrate that all figures of merit are excellent when imaging is accurately performed and analysed by experienced operators

  9. Image quality in multidetector CT of the paranasal sinuses. Potential of dose reduction using an adaptive post-processing filter

    International Nuclear Information System (INIS)

    Purpose: Evaluation of subjective image quality in dose-reduced multi-detector CT (MDCT) of paranasal sinuses using a 2D non-linear adaptive post-processing filter (2D-NLAF). Materials and Methods: MDCT of paranasal sinuses was simulated using a human head phantom at a Somatom Sensation Cardiac 64 (Siemens, Erlangen). At constant collimation (64 x 0.6 mm) und pitch (p = 1), the tube current (50, 100, 200 mAs) and tube potential (80, 100, 120 kVp) were modified. The radiation exposure was represented by CTDIvol. Four independent blinded radiologists evaluated the image quality of axial 2 mm images and coronal reformations concerning the assessment of 'fractures' and 'soft tissue processes'. The subjective image quality of original and post-processed images using a 2D-NLAF (SharpViewCT registered, Sweden) was graded on a 5-point scale ('1' excellent - '5' not adequate) and compared. Results: Compared to the protocol with the best image quality (120kVp/ 200 mAs) 2D-NLAF led to a significant improvement in the subjective image quality at 100 kVp/ 100 mAs (score '1.4' with filter versus '2.2' without) and 120 kVp/ 50 mAs ('1.6' versus '2.0') (p < 0.03) particularly for high contrasts ('fractures', p < 0.001). In 'soft tissue processes', 2D-NLAF provided improved quality from '2.1' to '1.4' (p < 0.04) at 100 kVp/ 100 mAs. Down to a CTDIvol of 8 mGy, the image quality was rated 'good', and down to 5 mGy 'diagnostic'. Conclusion: The phantom study indicates a dose reduction potential in MDCT of paranasal sinuses up to 58 % compared to a standard dose protocol using a 2D-NLAF without an essential loss of image quality. 2D-NLAF is particularly effective at 100 kVp/ 100 mAs and 120 kVp/ 50 mAs. (orig.)

  10. Os cuboideum secundarium: A rare accessory ossicle with the potential to mimic a mass on magnetic resonance imaging

    International Nuclear Information System (INIS)

    Accessory ossicles are common incidental findings on radiographs of the ankle and foot. While typically asymptomatic and of no clinical significance, they are sometimes associated with local pain or even mistaken for pathological conditions such as fractures. Given the potential for misinterpretation, it is important to understand their typical locations and appearances. This case highlights an exceptionally rare accessory ossicle called the os cuboideum secundarium, located adjacent to the cuboid and calcaneus. Interestingly, this case demonstrates the potential for this rare ossicle to mimic a mass on magnetic resonance imaging (MRI). Furthermore, despite the significant improvements in the understanding of musculoskeletal pathology afforded by advancements in cross-sectional imaging techniques, this case is a reminder of certain pitfalls that remain. Lastly, it highlights the importance of radiographs as an initial diagnostic study in evaluating foot pain. (orig.)

  11. Os cuboideum secundarium: A rare accessory ossicle with the potential to mimic a mass on magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kauffmann, Gregory [University of Chicago, Pritzker School of Medicine, Chicago, IL (United States); Stacy, G.S. [University of Chicago, Section of Musculoskeletal Radiology, Department of Radiology, Chicago, IL (United States)

    2014-01-15

    Accessory ossicles are common incidental findings on radiographs of the ankle and foot. While typically asymptomatic and of no clinical significance, they are sometimes associated with local pain or even mistaken for pathological conditions such as fractures. Given the potential for misinterpretation, it is important to understand their typical locations and appearances. This case highlights an exceptionally rare accessory ossicle called the os cuboideum secundarium, located adjacent to the cuboid and calcaneus. Interestingly, this case demonstrates the potential for this rare ossicle to mimic a mass on magnetic resonance imaging (MRI). Furthermore, despite the significant improvements in the understanding of musculoskeletal pathology afforded by advancements in cross-sectional imaging techniques, this case is a reminder of certain pitfalls that remain. Lastly, it highlights the importance of radiographs as an initial diagnostic study in evaluating foot pain. (orig.)

  12. Skullcap and germander: preventing potential toxicity through the application of hyperspectral imaging and multivariate image analysis as a novel quality control method.

    Science.gov (United States)

    Sandasi, Maxleene; Vermaak, Ilze; Chen, Weiyang; Viljoen, Alvaro M

    2014-10-01

    Scutellaria lateriflora (skullcap) is a medicinal herb that has a long history of use in the treatment of ailments such as insomnia and anxiety. Commercial herbal formulations claiming to contain S. laterifolia herba have flooded the consumer markets. However, due to intentional or unintentional adulteration, cases of hepatotoxicity have been reported. Possible adulteration with the potentially hepatotoxic Teucrium spp., T. canadense and T. chamaedrys has been reported. In this study, hyperspectral imaging in combination with multivariate image analysis methods was used to differentiate S. laterifolia, T. canadense, and T. chamaedrys raw materials in a non-destructive manner. Furthermore, the ability to detect adulteration of raw materials using the developed multivariate models was also investigated. Chemical images were captured using a shortwave infrared pushbroom imaging system in the wavelength range 920-2514 nm. Principal component analysis was applied to the images to investigate chemical differences between the species. Partial least squares discriminant analysis was used to model pre-assigned class images, and the classification model predicted the levels of adulteration in spiked raw materials. UHPLC-MS as an independent analytical technique was used to confirm chemical differences between the three species. The ability of hyperspectral chemical imaging as a non-destructive technique in the differentiation of the three species was achieved with three distinct clusters in the score scatter plot. A 92.3 % variation in modelled data using PC1 and PC2 was correlated to chemical differences between the three species. Near infrared signals in the regions 1924 nm and 2092 nm (positive P1), 1993 nm and 2186 nm (negative P1), 1918 nm, 2092 nm, and 2266 nm (positive P2), as well as 1993 nm and 2303 nm (negative P2) were identified as containing discriminating information using the loadings line plots. Chemical imaging of spiked samples showed

  13. Cameras a Million Miles Apart: Stereoscopic Imaging Potential with the Hubble and James Webb Space Telescopes

    CERN Document Server

    Green, Joel D; Stansberry, John A; Meinke, Bonnie

    2016-01-01

    The two most powerful optical/IR telescopes in history -- NASA's Hubble and James Webb Space Telescopes -- will be in space at the same time. We have a unique opportunity to leverage the 1.5 million kilometer separation between the two telescopic nodal points to obtain simultaneously captured stereoscopic images of asteroids, comets, moons and planets in our Solar System. Given the recent resurgence in stereo-3D movies and the recent emergence of VR-enabled mobile devices, these stereoscopic images provide a unique opportunity to engage the public with unprecedented views of various Solar System objects. Here, we present the technical requirements for acquiring stereoscopic images of Solar System objects, given the constraints of the telescopic equipment and the orbits of the target objects, and we present a handful of examples.

  14. Determination of thermodynamic potentials and the aggregation number for micelles with the mass-action model by isothermal titration calorimetry: A case study on bile salts.

    Science.gov (United States)

    Olesen, Niels Erik; Westh, Peter; Holm, René

    2015-09-01

    The aggregation number (n), thermodynamic potentials (ΔG, ΔH, ΔS) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters of micelles with ITC were compared to a mass-action model (MAM) of reaction type: n⋅S⇌Mn. This analysis can provide guidelines for future ITC studies of systems behaving in accordance with this model such as micelles and proteins that undergo self-association to oligomers. Micelles with small aggregation numbers, as those of bile salts, are interesting because such small aggregates cannot be characterized as a separate macroscopic phase and the widely applied pseudo-phase model (PPM) is inaccurate. In the present work it was demonstrated that the aggregation number of micelles was constant at low concentrations enabling determination of the thermodynamic potentials by the MAM. A correlation between the aggregation number and the heat capacity was found, which implies that the dehydrated surface area of bile salts increases with the aggregation number. This is in accordance with Tanford's principles of opposing forces where neighbouring molecules in the aggregate are better able to shield from the surrounding hydrophilic environment when the aggregation number increases.

  15. LMI1195 PET imaging in evaluation of regional cardiac sympathetic denervation and its potential role in antiarrhythmic drug treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ming; Bozek, Jody; Lamoy, Melanie; Kagan, Mikhail; Benites, Pedro; Onthank, David; Robinson, Simon P. [Lantheus Medical Imaging, Discovery Research, N. Billerica, MA (United States)

    2012-12-15

    Regional cardiac sympathetic denervation (RCSD) associated with reduced noradrenaline transporter (NAT) function has been linked to cardiac arrhythmia. This study examined the association of LMI1195, an {sup 18}F-labeled NAT substrate developed for positron emission tomography (PET) imaging, with NAT in vitro, and its imaging to detect RCSD and guide antiarrhythmic drug treatment in vivo. LMI1195 association with NAT was assessed in comparison with other substrates, noradrenaline (NA) and {sup 123}I-metaiodobenzylguanidine (MIBG), in NAT-expressing cells. LMI1195 cardiac imaging was performed for evaluation of RCSD in a rabbit model surgically developed by regional phenol application on the left ventricular (LV) wall. The normal LV areas in images were quantified as regions with radioactivity {>=}50 % maximum. Potential impact of RCSD on dofetilide, an antiarrhythmic drug, induced ECG changes was assessed. NAT blockade with desipramine reduced LMI1195 cell uptake by 90 {+-} 3 %, similar to NA and MIBG. NA, MIBG, or self inhibited LMI1195 cell uptake concentration-dependently with comparable IC{sub 50} values (1.09, 0.21, and 0.90 {mu}M). LMI1195 cardiac imaging differentiated innervated and denervated areas in RCSD rabbits. The surgery resulted in a large denervated LV area at 2 weeks which was partially recovered at 12 weeks. Myocardial perfusion imaging with flurpiridaz F 18 showed normal perfusion in RCSD areas. Dofetilide induced more prominent QTc prolongation in RCSD than control animals. However, changes in heart rate were comparable. LMI1195 exhibits high association with NAT and can be used for imaging RCSD. The detected RCSD increases cardiac risks to the antiarrhythmic drug, dofetilide, by inducing more QTc prolongation. (orig.)

  16. Fusion imaging of computed tomographic pulmonary angiography and SPECT ventilation/perfusion scintigraphy: initial experience and potential benefit

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Benjamin [Royal North Shore Hospital, Department of Respiratory Medicine, St Leonards (Australia); University of Sydney, Northern Clinical School, Faculty of Medicine, Sydney (Australia); Bailey, Dale [Royal North Shore Hospital, Department of Nuclear Medicine, St Leonards (Australia); University of Sydney, Schools of Physics and Medical Radiation Science, Sydney (Australia); Roach, Paul; Bailey, Elizabeth [Royal North Shore Hospital, Department of Nuclear Medicine, St Leonards (Australia); King, Gregory [Royal North Shore Hospital, Department of Respiratory Medicine, St Leonards (Australia); University of Sydney, Northern Clinical School, Faculty of Medicine, Sydney (Australia); The Woolcock Institute of Medical Research, Camperdown (Australia)

    2007-01-15

    The objective of this study was to examine the feasibility of fusing ventilation and perfusion data from single-photon emission computed tomography (SPECT) ventilation perfusion (V/Q) scintigraphy together with computed tomographic pulmonary angiography (CTPA) data. We sought to determine the accuracy of this fusion process. In addition, we correlated the findings of this technique with the final clinical diagnosis. Thirty consecutive patients (17 female, 13 male) who had undergone both CTPA and SPECT V/Q scintigraphy during their admission for investigation of potential pulmonary embolism were identified retrospectively. Image datasets from these two modalities were co-registered and fused using commercial software. Accuracy of the fusion process was determined subjectively by correlation between modalities of the anatomical boundaries and co-existent pleuro-parenchymal abnormalities. In all 30 cases, SPECT V/Q images were accurately fused with CTPA images. An automated registration algorithm was sufficient alone in 23 cases (77%). Additional linear z-axis scaling was applied in seven cases. There was accurate topographical co-localisation of vascular, parenchymal and pleural disease on the fused images. Nine patients who had positive CTPA performed as an initial investigation had co-localised perfusion defects on the subsequent fused CTPA/SPECT images. Three of the 11 V/Q scans initially reported as intermediate could be reinterpreted as low probability owing to co-localisation of defects with parenchymal or pleural pathology. Accurate fusion of SPECT V/Q scintigraphy to CTPA images is possible. This technique may be clinically useful in patients who have non-diagnostic initial investigations or in whom corroborative imaging is sought. (orig.)

  17. Fusion imaging of computed tomographic pulmonary angiography and SPECT ventilation/perfusion scintigraphy: initial experience and potential benefit

    International Nuclear Information System (INIS)

    The objective of this study was to examine the feasibility of fusing ventilation and perfusion data from single-photon emission computed tomography (SPECT) ventilation perfusion (V/Q) scintigraphy together with computed tomographic pulmonary angiography (CTPA) data. We sought to determine the accuracy of this fusion process. In addition, we correlated the findings of this technique with the final clinical diagnosis. Thirty consecutive patients (17 female, 13 male) who had undergone both CTPA and SPECT V/Q scintigraphy during their admission for investigation of potential pulmonary embolism were identified retrospectively. Image datasets from these two modalities were co-registered and fused using commercial software. Accuracy of the fusion process was determined subjectively by correlation between modalities of the anatomical boundaries and co-existent pleuro-parenchymal abnormalities. In all 30 cases, SPECT V/Q images were accurately fused with CTPA images. An automated registration algorithm was sufficient alone in 23 cases (77%). Additional linear z-axis scaling was applied in seven cases. There was accurate topographical co-localisation of vascular, parenchymal and pleural disease on the fused images. Nine patients who had positive CTPA performed as an initial investigation had co-localised perfusion defects on the subsequent fused CTPA/SPECT images. Three of the 11 V/Q scans initially reported as intermediate could be reinterpreted as low probability owing to co-localisation of defects with parenchymal or pleural pathology. Accurate fusion of SPECT V/Q scintigraphy to CTPA images is possible. This technique may be clinically useful in patients who have non-diagnostic initial investigations or in whom corroborative imaging is sought. (orig.)

  18. Process versus product in social learning: comparative diffusion tensor imaging of neural systems for action execution-observation matching in macaques, chimpanzees, and humans.

    Science.gov (United States)

    Hecht, Erin E; Gutman, David A; Preuss, Todd M; Sanchez, Mar M; Parr, Lisa A; Rilling, James K

    2013-05-01

    Social learning varies among primate species. Macaques only copy the product of observed actions, or emulate, while humans and chimpanzees also copy the process, or imitate. In humans, imitation is linked to the mirror system. Here we compare mirror system connectivity across these species using diffusion tensor imaging. In macaques and chimpanzees, the preponderance of this circuitry consists of frontal-temporal connections via the extreme/external capsules. In contrast, humans have more substantial temporal-parietal and frontal-parietal connections via the middle/inferior longitudinal fasciculi and the third branch of the superior longitudinal fasciculus. In chimpanzees and humans, but not in macaques, this circuitry includes connections with inferior temporal cortex. In humans alone, connections with superior parietal cortex were also detected. We suggest a model linking species differences in mirror system connectivity and responsivity with species differences in behavior, including adaptations for imitation and social learning of tool use. PMID:22539611

  19. MR Imaging with Intermolecular Multiple quantum Coherences (iMQCs):Fundamental Questions and Potentials

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ Pursuit of new contrast in imaging has been the driving force behind many innovative applications of physics in medical MRI. Even though the use of intramolecular multiple quantum coherence in NMR spectroscopy has a long history, intermolecular multiple quantum coherence (iMQC) among spins on different molecules, such as protonproton iMQC in water, was considered impossible for many years.

  20. Task-independent effects are potential confounders in longitudinal imaging studies of learning in schizophrenia

    Directory of Open Access Journals (Sweden)

    Michele Korostil

    2016-01-01

    The strong interaction between group and time suggests that both the scanning experience as a whole and the transition between task-types evokes a different response in persons with schizophrenia and may confound interpretation of learning-related longitudinal imaging experiments if not explicitly considered.

  1. A review of potential image fusion methods for remote sensing-based irrigation management: Part II

    Science.gov (United States)

    Satellite-based sensors provide data at either greater spectral and coarser spatial resolutions, or lower spectral and finer spatial resolutions due to complementary spectral and spatial characteristics of optical sensor systems. In order to overcome this limitation, image fusion has been suggested ...

  2. From Exoplanets to Quasars: Detection of Potential Damped Lyman Alpha Absorbing Galaxies Using Angular Differential Imaging

    CERN Document Server

    Johnson-Groh, Mara; Ellison, Sara L

    2016-01-01

    The advantages of angular differential imaging (ADI) has been previously untested in imaging the host galaxies of damped Lyman alpha (DLA) systems. In this pilot study, we present the first application of ADI to directly imaging the host galaxy of the DLA seen towards the quasar J1431+3952. K-band imaging of the field surrounding J1431+3952 was obtained on the Gemini North telescope with the adaptive optics system and a laser guide star. We computed a sensitivity curve that demonstrates the sensitivity of our observations as a function of K-band magnitude, impact parameter and DLA angular size. For an impact parameter of 0.5" (3.4 kpc at the redshift of the absorber) our mass sensitivity is log (M_star/M_sun) ~ 9.2 and drops to ~ 9.0 at separations beyond ~ 6 kpc for the smallest size model galaxy. Three candidate galaxies are identified within 5". Stellar masses were computed from the K-band photometry yielding values of log (M_star/M_sun) ~ 9.9, 9.7 and 11.1 respectively. The likely identification of the ab...

  3. Preclinical Evaluation of Raman Nanoparticle Biodistribution for their Potential Use in Clinical Endoscopy Imaging

    DEFF Research Database (Denmark)

    Zavaleta, Cristina L; Hartman, Keith B; Miao, Zheng;

    2011-01-01

    Raman imaging offers unsurpassed sensitivity and multiplexing capabilities. However, its limited depth of light penetration makes direct clinical translation challenging. Therefore, a more suitable way to harness its attributes in a clinical setting would be to couple Raman spectroscopy with endo...

  4. Envisat/ASAR Images for the Calibration of Wind Drag Action in the Doñana Wetlands 2D Hydrodynamic Model

    Directory of Open Access Journals (Sweden)

    Anaïs Ramos-Fuertes

    2013-12-01

    Full Text Available Doñana National Park wetlands are located in southwest Spain, on the right bank of the Guadalquivir River, near the Atlantic Ocean coast. The wetlands dry out completely every summer and progressively flood again throughout the fall and winter seasons. Given the flatness of Doñana’s topography, the wind drag action can induce the flooding or emergence of extensive areas, detectable in remote sensing images. Envisat/ASAR scenes acquired before and during strong and persistent wind episodes enabled the spatial delineation of the wind-induced water displacement. A two-dimensional hydrodynamic model of Doñana wetlands was built in 2006 with the aim to predict the effect of proposed hydrologic restoration actions within Doñana’s basin. In this work, on-site wind records and concurrent ASAR scenes are used for the calibration of the wind-drag modeling by assessing different formulations. Results show a good adjustment between the modeled and observed wind drag effect. Displacements of up to 2 km in the wind direction are satisfactorily reproduced by the hydrodynamic model, while including an atmospheric stability parameter led to no significant improvement of the results. Such evidence will contribute to a more accurate simulation of hypothetic or design scenarios, when no information is available for the atmospheric stability assessment.

  5. The trochlear pre-ossification center: a normal developmental stage and potential pitfall on MR images

    International Nuclear Information System (INIS)

    The hypertrophic changes that occur in the cartilage of an epiphysis prior to the onset of ossification are known as the pre-ossification center. Awareness of the appearance of the pre-ossification center on MR images is important to avoid confusing normal developmental changes with pathology. The purpose of this study was to determine the characteristics of the trochlear pre-ossification center on MR imaging and examine age and gender differences. We retrospectively analyzed MR images from 61 children. The trochleas were categorized into three types on the basis of signal intensity (SI). Trochlear types were compared to age and gender. There was no significant difference between the ages of boys and girls. Type 1 trochleas showed homogeneous SI on all pulse sequences. Type 2 trochleas demonstrated a focus of high SI in the epiphyseal cartilage on fat-suppressed water-sensitive sequences, with high or intermediate SI on gradient-echo images (pre-ossification center). Type 3 trochleas showed low SI on fat-suppressed water-sensitive sequences and gradient-echo images. Thirty-seven trochleas were described as type 1, sixteen as type 2 and eight as type 3. ANOVAs confirmed a statistically significant difference in the age of children with type 3 trochleas and those with types 1 and 2 (P < 0.001). Spearman rank correlations determined a positive relationship between trochlear type and age of the children (r = 0.53). Development-related changes in the trochlea follow a predictable pattern. The signal characteristics of the pre-ossification center likely reflect normal chondrocyte hypertrophy and an increase in free water in the matrix. (orig.)

  6. Dose reduction and image quality in MDCT of the upper abdomen. Potential of an adaptive post-processing filter

    International Nuclear Information System (INIS)

    Purpose: To evaluate the effects of a 2D non-linear adaptive post-processing filter (2D-NLAF) on image quality in dose-reduced multi-detector CT (MDCT) of the upper abdomen. Materials and Methods: MDCT of the upper abdomen was simulated on a 64-slice scanner using a multi-modal anthropomorphic phantom (CIRS, Norfolk, USA). While keeping the collimation (64 x 0.6 mm) and pitch (p = 1) unchanged, the tube current (100 - 500 mAs) and tube potential (80 - 140 kVp) were varied to perform MDCT as high dose (CTDI > 20), middle dose (CTDI 10-20) and low dose (CTDI < 10) level protocols. Four independent blinded radiologists evaluated axial images with a thickness of 7 and 3 mm with respect to the presentation of ''mesenteric low contrast lesions'', ''liver veins'', ''liver cysts'', ''renal cysts'' and ''big vessels''. The subjective image quality of original data and post-processed images using a 2D-NLAF (SharpViewCT, Linkoeping, Sweden) was graded on a 5-point scale (from ''1'' not visible to ''5'' excellent) and statistically analyzed. The effective dose (E) was estimated using commercial software (CT-EXPO). Results: For all protocol groups, 2D-NLAF led to a significant improvement in subjective image quality for all examined lesions (p < 0.01), particularly at the protocols of middle dose (E: 5 - 8 mSv) and low dose level (E: 1-5 mSv). A maximum effect was seen in middle dose protocols for ''low contrast lesions'' (score ''3.3'' with filter versus ''2.5'' without) and ''liver veins'' (''4.5'' versus ''3.9''). Conclusion: The phantom study indicates a potential dose reduction of up to 50% in MDCT of the upper abdomen by use of a 2D-NLAF, which should be further examined in clinical trails. (orig.)

  7. Georectification and snow classification of webcam images: potential for complementing satellite-derrived snow maps over Switzerland

    Science.gov (United States)

    Dizerens, Céline; Hüsler, Fabia; Wunderle, Stefan

    2016-04-01

    The spatial and temporal variability of snow cover has a significant impact on climate and environment and is of great socio-economic importance for the European Alps. Satellite remote sensing data is widely used to study snow cover variability and can provide spatially comprehensive information on snow cover extent. However, cloud cover strongly impedes the surface view and hence limits the number of useful snow observations. Outdoor webcam images not only offer unique potential for complementing satellite-derived snow retrieval under cloudy conditions but could also serve as a reference for improved validation of satellite-based approaches. Thousands of webcams are currently connected to the Internet and deliver freely available images with high temporal and spatial resolutions. To exploit the untapped potential of these webcams, a semi-automatic procedure was developed to generate snow cover maps based on webcam images. We used daily webcam images of the Swiss alpine region to apply, improve, and extend existing approaches dealing with the positioning of photographs within a terrain model, appropriate georectification, and the automatic snow classification of such photographs. In this presentation, we provide an overview of the implemented procedure and demonstrate how our registration approach automatically resolves the orientation of a webcam by using a high-resolution digital elevation model and the webcam's position. This allows snow-classified pixels of webcam images to be related to their real-world coordinates. We present several examples of resulting snow cover maps, which have the same resolution as the digital elevation model and indicate whether each grid cell is snow-covered, snow-free, or not visible from webcams' positions. The procedure is expected to work under almost any weather condition and demonstrates the feasibility of using webcams for the retrieval of high-resolution snow cover information.

  8. High throughput ratio imaging to profile caspase activity: potential application in multiparameter high content apoptosis analysis and drug screening.

    Directory of Open Access Journals (Sweden)

    Jeena Joseph

    Full Text Available Recent advancement in the area of green fluorescent protein techniques coupled with microscopic imaging has significantly contributed in defining and dissecting subcellular changes of apoptosis with high spatio-temporal resolution. Although single cell based studies using EGFP and associated techniques have provided valuable information of initiation and hierarchical changes of apoptosis, they are yet to be exploited for multiparameter cell based real time analysis for possible drug screening or pathway defining in a high throughput manner. Here we have developed multiple cancer cell lines expressing FRET sensors for active caspases and adapted them for high throughput live cell ratio imaging, enabling high content image based multiparameter analysis. Sensitivity of the system to detect live cell caspase activation was substantiated by confocal acceptor bleaching as well as wide field FRET imaging. Multiple caspase-specific activities of DEVDase, IETDase and LEHDase were analysed simultaneously with other decisive events of cell death. Through simultaneous analysis of caspase activation by FRET ratio change coupled with detection of mitochondrial membrane potential loss or superoxide generation, we identified several antitumor agents that induced caspase activation with or without membrane potential loss or superoxide generation. Also, cells that escaped the initial drug-induced caspase activation could be easily followed up for defining long term fate. Employing such a revisit imaging strategy of the same area, we have tracked the caspase surviving fractions with multiple drugs and its subsequent response to retreatment, revealing drug-dependent diverging fate of surviving cells. This thereby indicates towards a complex control of drug induced tumor resistance. The technique described here has wider application in both screening of compound libraries as well as in defining apoptotic pathways by linking multiple signaling to identify non

  9. Character of diaphragm compound muscle action potential and phrenic nerve conduction time in patients with obstructive sleep apnea-hypopnea syndrome

    Institute of Scientific and Technical Information of China (English)

    Yuhong Hou; Rongchang Chen; Jinbing Pan; Yuanming Luo; Nanshan Zhong

    2008-01-01

    BACKGROUND: Both hypoxia and carbon dioxide retention can damage phrenic nerve and muscle conduction, as well as diaphragm function. Diaphragm compound muscle action potential and phrenic nerve conduction time are reliable indicators for measuring phrenic nerve and diaphragm function.OBJECTIVES: To verify the hypothesis that changes of phrenic nerve conduction time (PNCT) and diaphragm compound muscle action potential (CMAP) in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients might contribute to the decline of phrenic nerve and diaphragm function. PNCT and CMAP were measured with multipair esophageal electrodes combined with unilateral magnetic stimulation.DESIGN, TIME AND SETTING: Case controlled study. The experiment was carried out in Guangzhou Institute of Respiratory Disease, Guangzhou Medical College, from June 2005 to April 2006.PARTICIPANTS: Twenty seven OSAHS patients and eight primary snoring subjects from Guangzhou Institute of Respiratory Disease, Guangzhou Medical College were recruited and all subjects were diagnosed by polysomnography (PSG). Sixteen healthy, non-snoring subjects in the hospital for medical examination during the same time period were selected as the control group.METHODS: Esophageal electrodes, made by Guangzhou Institute of Respiratory Disease, combined with unilateral magnetic stimulation, were used to measure PNCT and CMAP of all subjects. PNCT was defined as the time from stimulation artifact to the onset of CMAP and diaphragm CMAP amplitude was measured from peak to peak. Oxygen desaturation index and apnea-hypopnea index were measured using PSG, and their relevance to PNCT and CMAP were analyzed. PNCT and CMAP in five OSAHS patients were repeatedly measured after effective nasal continuous positive airway pressure treatment for more than 2 months.MAIN OUTCOME MEAAURES: (1) PNCT and diaphragm CMAP of suhjects in each group. (2) Relevance of oxygen desaturation index and apnea-hypopnea index to PNCT and CMAP. (3

  10. Preparation and evaluation of technetium-99m labeled cardiac glycoside derivatives as potential myocardial imaging agent

    Energy Technology Data Exchange (ETDEWEB)

    Misra, Mridula; Sarkar, H.S.; Chatterjee, Mita; Banerjee, Somenath

    1988-01-01

    Three cardiac glycosides, two natural, cymarin and convallotoxin and one synthetic, strophanthidin-..beta..-D-glucoside were converted to their thiosemicarbazone and subsequently radiolabeled with sup(99m)Tc by chelation. The resulting radioactive chelate complexes were evaluated in animals to determine the suitability of this class of compounds for myocardial imaging. It was observed from the animal biodistribution data of the three radioactive compounds that there was a considerable variation in the heart to non-target organ uptake ratio. A possible explanation of this variation was offered in the light of their lipophilic character, protein binding ability and affinity towards non-target receptors. It is anticipated that this study may help to develop a sup(99m)Tc-cardiac glycoside complex with better distribution characteristics, and such a compound may offer a suitable alternative to /sup 201/Tl, which is at present used for myocardial imaging.

  11. Small animal image-guided radiotherapy: status, considerations and potential for translational impact

    OpenAIRE

    Butterworth, K. T.; Prise, K M; Verhaegen, F

    2014-01-01

    Radiation biology is being transformed by the implementation of small animal image-guided precision radiotherapy into pre-clinical research programmes worldwide. We report on the current status and developments of the small animal radiotherapy field, suggest criteria for the design and execution of effective studies and contend that this powerful emerging technology, used in combination with relevant small animal models, holds much promise for translational impact in radiation oncology.

  12. Potential Application of Fluorescence Imaging for Assessing Fecal Contamination of Soil and Compost Maturity

    Directory of Open Access Journals (Sweden)

    Hyunjeong Cho

    2016-08-01

    Full Text Available Pathogenic microorganisms can lead to serious outbreaks of foodborne illnesses, particularly if fresh produce becomes contaminated and then happens to be inappropriately handled in a manner that can incubate pathogens. Pathogenic microbial contamination of produce can occur through a variety of pathways, such as from the excrement of domesticated and wild animals, biological soil amendment, agricultural water, worker health and hygiene, and field tools used during growth and harvest. The use of mature manure compost and preventative control of fecal contamination from wildlife and livestock are subject to safety standards to minimize the risk of foodborne illness associated with produce. However, in a field production environment, neither traces of animal feces nor the degree of maturity of manure compost can be identified by the naked eye. In this study, we investigated hyperspectral fluorescence imaging techniques to characterize fecal samples from bovine, swine, poultry, and sheep species, and to determine feasibilities for both detecting the presence of animal feces as well as identifying the species origin of the feces in mixtures of soil and feces. In addition, the imaging techniques were evaluated for assessing the maturity of manure compost. The animal feces exhibited dynamic and unique fluorescence emission features that allowed for the detection of the presence of feces and showed that identification of the species origin of fecal matter present in soil-feces mixtures is feasible. Furthermore, the results indicate that using simple single-band fluorescence imaging at the fluorescence emission maximum for animal feces, simpler than full-spectrum hyperspectral fluorescence imaging, can be used to assess the maturity of manure compost.

  13. Imaging of normal and pathologic joint synovium using nonlinear optical microscopy as a potential diagnostic tool

    OpenAIRE

    Tiwari, Nivedan; Chabra, Sanjay; Mehdi, Sheherbano; Sweet, Paula; Krasieva, Tatiana B.; Pool, Roy; Andrews, Brian; Peavy, George M.

    2010-01-01

    An estimated 1.3 million people in the United States suffer from rheumatoid arthritis (RA). RA causes profound changes in the synovial membrane of joints, and without early diagnosis and intervention, progresses to permanent alterations in joint structure and function. The purpose of this study is to determine if nonlinear optical microscopy (NLOM) can utilize the natural intrinsic fluorescence properties of tissue to generate images that would allow visualization of the structural and cellul...

  14. Diagnostic merits of current and potential applications of single photon and positron imaging: a perspective

    Energy Technology Data Exchange (ETDEWEB)

    Harper, P. V.

    1978-01-01

    A brief review of the limitations of medical radionuclide imaging techniques in competition with x-ray CAT scanning and ultrasound suggest that the emphasis in this are should be on measurement of the physiologic uptake of tracer materials. Tomography greatly improves the possibilities of quantitation of this uptake - examples using positron and single photon techniques are presented for /sup 13/NH/sub 3/ and /sup 201/Tl in the heart.

  15. Electromyography (image)

    Science.gov (United States)

    ... Each muscle fiber that contracts will produce an action potential. The presence, size, and shape of the wave form of the action potential produced on the oscilloscope, provides information about the ...

  16. Texture features on T2-weighted magnetic resonance imaging: new potential biomarkers for prostate cancer aggressiveness

    Science.gov (United States)

    Vignati, A.; Mazzetti, S.; Giannini, V.; Russo, F.; Bollito, E.; Porpiglia, F.; Stasi, M.; Regge, D.

    2015-04-01

    To explore contrast (C) and homogeneity (H) gray-level co-occurrence matrix texture features on T2-weighted (T2w) Magnetic Resonance (MR) images and apparent diffusion coefficient (ADC) maps for predicting prostate cancer (PCa) aggressiveness, and to compare them with traditional ADC metrics for differentiating low- from intermediate/high-grade PCas. The local Ethics Committee approved this prospective study of 93 patients (median age, 65 years), who underwent 1.5 T multiparametric endorectal MR imaging before prostatectomy. Clinically significant (volume ≥0.5 ml) peripheral tumours were outlined on histological sections, contoured on T2w and ADC images, and their pathological Gleason Score (pGS) was recorded. C, H, and traditional ADC metrics (mean, median, 10th and 25th percentile) were calculated on the largest lesion slice, and correlated with the pGS through the Spearman correlation coefficient. The area under the receiver operating characteristic curve (AUC) assessed how parameters differentiate pGS = 6 from pGS ≥ 7. The dataset included 49 clinically significant PCas with a balanced distribution of pGS. The Spearman ρ and AUC values on ADC were: -0.489, 0.823 (mean) -0.522, 0.821 (median) -0.569, 0.854 (10th percentile) -0.556, 0.854 (25th percentile) -0.386, 0.871 (C); 0.533, 0.923 (H); while on T2w they were: -0.654, 0.945 (C); 0.645, 0.962 (H). AUC of H on ADC and T2w, and C on T2w were significantly higher than that of the mean ADC (p = 0.05). H and C calculated on T2w images outperform ADC parameters in correlating with pGS and differentiating low- from intermediate/high-risk PCas, supporting the role of T2w MR imaging in assessing PCa biological aggressiveness.

  17. Non-uniform noise spatial distribution in CT myocardial perfusion and a potential solution: statistical image reconstruction

    Science.gov (United States)

    Thériault Lauzier, Pascal; Tang, Jie; Chen, Guang-Hong

    2012-03-01

    Myocardial perfusion scans are an important tool in the assessment of myocardial viability following an infarction. Cardiac perfusion analysis using CT datasets is limited by the presence of so-called partial scan artifacts. These artifacts are due to variations in beam hardening and scatter between different short-scan angular ranges. In this research, another angular range dependent effect is investigated: non-uniform noise spatial distribution. Images reconstructed using filtered backprojection (FBP) are subject to this effect. Statistical image reconstruction (SIR) is proposed as a potential solution. A numerical phantom with added Poisson noise was simulated and two swines were scanned in vivo to study the effect of FBP and SIR on the spatial uniformity of the noise distribution. It was demonstrated that images reconstructed using FBP often show variations in noise on the order of 50% between different time frames. This variation is mitigated to about 10% using SIR. The noise level is also reduced by a factor of 2 in SIR images. Finally, it is demonstrated that the measurement of quantitative perfusion metrics are generally more accurate when SIR is used instead of FBP.

  18. Increased excitability and altered action potential waveform in cerebellar granule neurons of the Ts65Dn mouse model of Down syndrome.

    Science.gov (United States)

    Usowicz, Maria M; Garden, Claire L P

    2012-07-17

    Down syndrome (DS) is characterized by intellectual disability and impaired motor control. Lack of coordinated movement, poor balance, and unclear speech imply dysfunction of the cerebellum, which is known to be reduced in volume in DS. The principal cause of the smaller cerebellum is a diminished number of granule cells (GCs). These neurons form the 'input layer' of the cerebellar cortex, where sensorimotor information carried by incoming mossy fibers is transformed before it is conveyed to Purkinje cells and inhibitory interneurons. However, it is not known how processing of this information is affected in the hypogranular cerebellum that characterizes DS. Here we explore the possibility that the electrical properties of the surviving GCs are changed. We find that in the Ts65Dn mouse model of DS, GCs have a higher input resistance at voltages approaching the threshold for firing, which causes them to be more excitable. In addition, they fire narrower and larger amplitude action potentials. These subtly modified electrical properties may result in atypical transfer of information at the input layer of the cerebellum.

  19. Anti-hyperlipidemic effects and potential mechanisms of action of the caffeoylquinic acid-rich Pandanus tectorius fruit extract in hamsters fed a high fat-diet.

    Directory of Open Access Journals (Sweden)

    Xiaopo Zhang

    Full Text Available Hyperlipidemia is considered to be one of the greatest risk factors contributing to the prevalence and severity of cardiovascular diseases. In this work, we investigated the anti-hyperlipidemic effect and potential mechanism of action of the Pandanus tectorius fruit extract in hamsters fed a high fat-diet (HFD. The n-butanol fraction of the P. tectorius fruit ethanol extract (PTF-b was rich in caffeoylquinic acids (CQAs. Administration of PTF-b for 4 weeks effectively decreased retroperitoneal fat and the serum levels of total cholesterol (TC, triglycerides (TG and low density lipoprotein-cholesterol (LDL-c and hepatic TC and TG. The lipid signals (fatty acids, and cholesterol in the liver as determined by nuclear magnetic resonance (NMR were correspondingly reduced. Realtime quantitative PCR showed that the mRNA levels of PPARα and PPARα-regulated genes such as ACO, CPT1, LPL and HSL were largely enhanced by PTF-b. The transcription of LDLR, CYP7A1, and PPARγ was also upregulated. Treatment with PTF-b significantly stimulated the activation of AMP-activated protein kinase (AMPK as well as the activity of serum and hepatic lipoprotein lipase (LPL. Together, these results suggest that administration of the PTF-b enriched in CQAs moderates hyperlipidemia and improves the liver lipid profile. These effects may be caused, at least in part, by increasing the expression of PPARα and its downstream genes and by upregulation of LPL and AMPK activities.

  20. Recording and analysis of electrically evoked compound action potentials (ECAPs) with MED-EL cochlear implants and different artifact reduction strategies in Matlab.

    Science.gov (United States)

    Bahmer, Andreas; Peter, Otto; Baumann, Uwe

    2010-08-15

    Electrically evoked compound action potentials (ECAPs) are used in auditory research to evaluate the response of the auditory nerve to electrical stimulation. Animal preparations are typically used for the recording. With the introduction of a new generation of cochlear implants, however it is possible to record the response of the auditory nerve to electrical stimulation in humans as well, which is used in the clinic to test whether the implant works properly and whether the auditory nerve is responsive. Currently, ECAPs are used to estimate thresholds for speech processor programs. In addition, ECAPs recordings allow new research to be addressed, e.g., to evaluate enhanced electrical stimulation patterns. Research platforms are required to test user-defined stimuli and algorithms for the ECAPs analysis. Clinical fitting software that records ECAPs is not flexible enough for this purpose. To enable a larger group of scientists to pursue research in this field, we introduce a flexible setup that allows to change stimulation and recording parameters. ECAP recording and analysis software was developed in Matlab (The Mathworks, Inc.) for standard PC, using a National instruments (PCI-6533, National Instruments, Austin, TX) card and a Research Interface Box 2 (RIB2, Department of Ion Physics and Applied Physics at the University of Innsbruck, Innsbruck, Austria) for MED-EL cochlear implants. ECAP recordings of a human subject with three different artifact reduction methods (alternating, Miller modified masker-probe, triphasic pulses) are presented and compared.